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随着绿色制造技术在切削加工中的应用，在高速铣削加工中采用压缩空气冷却取代切削液冷却已成为一种不错的选择。但是，对于具体的高速铣削加工任务，选用何种冷却方式更为恰当，则应根据不同的加工目的和被加工材料仔细加以权衡，以获得最佳的加工效果。以下是选择冷却方式时需要考虑的四个主要工艺因素。
1．工件材料的硬度
如果工件材料的硬度≥42HRC，选择压缩空气冷却通常可获得更佳的效果。高速铣削高硬度材料的加工特点为：①切削温度很高；②切屑在冷作硬化作用下会变得比母体材料更硬。切削此类材料时，如果采用切削液冷却，可能会使刀具承受间歇性升温－冷却造成的热冲击，温度的剧烈变化容易引起硬质合金切削刃碎裂。反之，如果采用压缩空气冷却，不仅可使刀具温度保持恒定，而且可将切屑吹离切削区，避免因高硬度切屑的二次切削（re-cutting）作用对刀具造成损坏。
2．工件材料的种类
如果工件材料的硬度<42HRC，则应根据工件材料的种类确定选用何种冷却方式。在高速铣削粘性材料（如铝、软性不锈钢等）时，通常需要选用切削液冷却。切削液可对刀具起到润滑作用，且可使切屑易于向上滑出容屑槽并与刀具后角分离。而在高速铣削大多数模具钢（如P20，H13，S7， NAK55，D2等）时，压缩空气冷却可能是正确的选择。如果在加工中发现工件材料与刀具发生粘连现象，则可能提示需要采用切削液；但也可能提示需要选用不同的刀具涂层。
3．刀具涂层
氮碳化钛（TiCN）涂层和氮铝钛（TiAlN）涂层是高速铣削模具钢时最常用的两种刀具涂层。球头铣刀在低于245m/min （800sfm）的切削速度下铣削硬度小于42HRC的工件材料（或圆铣刀在低于600sfm的切削速度下铣削相同材料）时，刀具采用TiCN涂层较为合适。如果被加工材料的硬度或切削速度高于上述切削参数范围，则最好选用TiAlN涂层。
TiCN涂层对切削液冷却具有很好的适应性。虽然切削温度的剧烈变化仍有可能引起硬质合金切削刃碎裂，但在上述切削参数范围内进行加工，一般不会产生足以引起热冲击危险的切削高温。
反之，高温切削性能较好的TiAlN涂层不太适合切削液冷却。这种涂层在进行高温切削时，可在涂层外表面形成一层坚硬而光滑的氧化铝层，有助于提高刀具的切削性能。（事实上，美国Millstar公司开发的“Exalon”TiAlN涂层的高温切削性能更为先进，这种TiAlN涂层的外面又增加了一层固体润滑层，可使切屑更易于沿着刀具切削刃滑离。）
石墨电极工件的铣削加工对刀具涂层的要求一般不太严格，选用TiAlN涂层或金刚石涂层均可。虽然这两种涂层采用压缩空气冷却即可获得很好的切削效果，但许多加工车间仍然愿意使用切削液，这是因为切削液有助于清除加工中产生的粉尘。
4．表面光洁度要求
用球头铣刀进行高速铣削时，为了获得较高的工件表面光洁度，可能需要采用切削液冷却。由于球头铣刀端部的切削速度为零，采用切削液可起到很好的润滑作用。当用典型的球头铣刀进行微进给精铣加工时，位于铣刀端部低速切削区域的工件材料可能会卡在“横刃（web）”内。处于红热状态的残留材料被刀具拖曳着划过工件，并可能熔焊在工件表面，从而破坏工件的表面光洁度。
在乾式切削方式以最新型BW冷風微型窩流管槍加上油霧裝置、可以提升加工面RA出糙度、重點冷風出風量為零下5度C、可以減輕刀具因切割產生高溫、http://tw.tool-tool.com/powder4_c.htm、輕微油霧增加刀具壽命、使被加工材料尺寸變形與加工表面細緻、在復合材料與潔淨加工環境更能提高環保。
歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對廠商高品質的刀具需求，我們可以協助廠商滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS刀具、協助客戶設計刀具流程、Carbide Cutting tools設計、航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、汽車業刀具設計等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！ BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 TEL:+886 4 24710048 / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,TaiwanWelcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
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2007年5月20日 星期日
如何提高数控机床的精度www.tool-tool.com
Bewise Inc. www.tool-tool.com Reference source from the internet.
随着我国经济的飞速发展，数控机床作为新一代工作母机，在机械制造中已得到广泛的应用，精密加工技术的迅速发展和零件加工精度的不断提高，对数控机床的精度也提出了更高的要求。尽管用户在选购数控机床时，都十分看重机床的位置精度，特别是各轴的定位精度和重复定位精度。但是这些使用中的数控机床精度到底如何呢? 大量统计资料表明：65.7%以上的新机床，安装时都不符合其技术指标；90%使用中的数控机床处于失准工作状态。因此，对机床工作状态进行监控和对机床精度进行经常的测试是非常必要的，以便及时发现和解决问题，提高零件加工精度。
目前数控机床位置精度的检验通常采用国际标准ISO230-2或国家标准GB10931-89等。同一台机床，由于采用的标准不同，所得到的位置精度也不相同，因此在选择数控机床的精度指标时，也要注意它所采用的标准。数控机床的位置标准通常指各数控轴的反向偏差和定位精度。对于这二者的测定和补偿是提高加工精度的必要途径。
一、反向偏差
在数控机床上，由于各坐标轴进给传动链上驱动部件(如伺服电动机、伺服液压马达和步进电动机等)的反向死区、各机械运动传动副的反向间隙等误差的存在，造成各坐标轴在由正向运动转为反向运动时形成反向偏差，通常也称反向间隙或失动量。对于采用半闭环伺服系统的数控机床，反向偏差的存在就会影响到机床的定位精度和重复定位精度，从而影响产品的加工精度。如在G01切削运动时，反向偏差会影响插补运动的精度，若偏差过大就会造成“圆不够圆，方不够方”的情形；而在G00快速定位运动中，反向偏差影响机床的定位精度，使得钻孔、镗孔等孔加工时各孔间的位置精度降低。同时，随着设备投入运行时间的增长，反向偏差还会随因磨损造成运动副间隙的逐渐增大而增加，因此需要定期对机床各坐标轴的反向偏差进行测定和补偿。
（1）反向偏差的测定
反向偏差的测定方法：在所测量坐标轴的行程内，预先向正向或反向移动一个距离并以此停止位置为基准，再在同一方向给予一定移动指令值，使之移动一段距离，然后再往相反方向移动相同的距离，测量停止位置与基准位置之差。在靠近行程的中点及两端的三个位置分别进行多次测定(一般为七次)，求出各个位置上的平均值，以所得平均值中的最大值为反向偏差测量值。在测量时一定要先移动一段距离，否则不能得到正确的反向偏差值。
测量直线运动轴的反向偏差时，测量工具通常采有千分表或百分表，若条件允许，可使用双频激光干涉仪进行测量。当采用千分表或百分表进行测量时，需要注意的是表座和表杆不要伸出过高过长，因为测量时由于悬臂较长，表座易受力移动，造成计数不准，补偿值也就不真实了。若采用编程法实现测量，则能使测量过程变得更便捷更精确。
例如，在三坐标立式机床上测量X轴的反向偏差，可先将表压住主轴的圆柱表面，然后运行如下程序进行测量：
N10 G91 G01 X50 F1000；工作台右移
N20 X－50；工作台左移，消除传动间隙
N30 G04 X5；暂停以便观察
N40 Z50；Z轴抬高让开
N50 X-50：工作台左移
N60 X50：工作台右移复位
N70 Z-50：Z轴复位
N80 G04 X5：暂停以便观察
N90 M99；
需要注意的是，在工作台不同的运行速度下所测出的结果会有所不同。一般情况下，低速的测出值要比高速的大，特别是在机床轴负荷和运动阻力较大时。低速运动时工作台运动速度较低，不易发生过冲超程(相对“反向间隙”)，因此测出值较大；在高速时，由于工作台速度较高，容易发生过冲超程，测得值偏小。
回转运动轴反向偏差量的测量方法与直线轴相同，只是用于检测的仪器不同而已。
（2）反向偏差的补偿
国产数控机床，定位精度有不少>0.02mm，但没有补偿功能。对这类机床，在某些场合下，可用编程法实现单向定位，清除反向间隙，在机械部分不变的情况下，只要低速单向定位到达插补起始点，然后再开始插补加工。插补进给中遇反向时，给反向间隙值再正式插补，即可提高插补加工的精度，基本上可以保证零件的公差要求。
对于其他类别的数控机床，通常数控装置内存中设有若干个地址,专供存储各轴的反向间隙值。当机床的某个轴被指令改变运动方向时，数控装置会自动读取该轴的反向间隙值，对坐标位移指令值进行补偿、修正，使机床准确地定位在指令位置上，消除或减小反向偏差对机床精度的不利影响。
一般数控系统只有单一的反向间隙补偿值可供使用，为了兼顾高、低速的运动精度，除了要在机械上做得更好以外，只能将在快速运动时测得的反向偏差值作为补偿值输入，因此难以做到平衡、兼顾快速定位精度和切削时的插补精度。
对于FANUC0i、FANUC18i等数控系统，有用于快速运动(G00)和低速切削进给运动(G01)的两种反向间隙补偿可供选用。根据进给方式的不同，数控系统自动选择使用不同的补偿值，完成较高精度的加工。
将G01切削进给运动测得的反向间隙值A 输入参数NO11851(G01的测试速度可根据常用的切削进给速度及机床特性来决定)，将G00测得的反向间隙值B 输入参数NO11852。需要注意的是，若要数控系统执行分别指定的反向间隙补偿，应将参数号码1800的第四位(RBK)设定为1；若RBK设定为0，则不执行分别指定的反向间隙补偿。G02、G03、JOG与G01使用相同的补偿值。
二、定位精度
数控机床的定位精度是指所测量的机床运动部件在数控系统控制下运动所能达到的位置精度，是数控机床有别于普通机床的一项重要精度，它与机床的几何精度共同对机床切削精度产生重要的影响，尤其对孔隙加工中的孔距误差具有决定性的影响。一台数控机床可以从它所能达到的定位精度判出它的加工精度，所以对数控机床的定位精度进行检测和补偿是保证加工质量的必要途径。
（1）定位精度的测定
目前多采用双频激光干涉仪对机床检测和处理分析，利用激光干涉测量原理，以激光实时波长为测量基准，所以提高了测试精度及增强了适用范围。检测方法如下：
①安装双频激光干涉仪；
②在需要测量的机床坐标轴方向上安装光学测量装置；
③调整激光头，使测量轴线与机床移动轴线共线或平行，即将光路预调准直；
④待激光预热后输入测量参数；
⑤按规定的测量程序运动机床进行测量；
⑥数据处理及结果输出。
（2）定位精度的补偿
若测得数控机床的定位误差超出误差允许范围，则必须对机床进行误差补偿。常用方法是计算出螺距误差补偿表，手动输入机床CNC系统，从而消除定位误差，由于数控机床三轴或四轴补偿点可能有几百上千点，所以手动补偿需要花费较多时间，并且容易出错。
现在通过RS232接口将计算机与机床CNC控制器联接起来，用VB编写的自动校准软件控制激光干涉仪与数控机床同步工作，实现对数控机床定位精度的自动检测及自动螺距误差补偿，其补偿方法如下：
①备份CNC 控制系统中的已有补偿参数；
②由计算机产生进行逐点定位精度测量的机床CNC程序，并传送给CNC 系统；
③自动测量各点的定位误差；
④根据指定的补偿点产生一组新的补偿参数，并传送给CNC系统，螺距自动补偿完成；
⑤重复③进行精度验证。
根据数控机床各轴的精度状况，利用螺距误差自动补偿功能和反向间隙补偿功能，合理地选择分配各轴补偿点，使数控机床达到最佳精度状态，并大大提高了检测机床定位精度的效率。
定位精度是数控机床的一个重要指标。尽管在用户购选时可以尽量挑选精度高误差小的机床，但是随着设备投入使用时间越长，设备磨损越厉害，造成机床的定位误差越来越大，这对加工和生产的零件有着致命的影响。采用以上方法对机床各坐标轴的反向偏差、定位精度进行准确测量和补偿，可以很好地减小或消除反向偏差对机床精度的不利影响，提高机床的定位精度，使机床处于最佳精度状态，从而保证零件的加工质量。
歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對廠商高品質的刀具需求，我們可以協助廠商滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS刀具、協助客戶設計刀具流程、Carbide Cutting tools設計、航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、汽車業刀具設計等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！ BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 TEL:+886 4 24710048 / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,TaiwanWelcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
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随着我国经济的飞速发展，数控机床作为新一代工作母机，在机械制造中已得到广泛的应用，精密加工技术的迅速发展和零件加工精度的不断提高，对数控机床的精度也提出了更高的要求。尽管用户在选购数控机床时，都十分看重机床的位置精度，特别是各轴的定位精度和重复定位精度。但是这些使用中的数控机床精度到底如何呢? 大量统计资料表明：65.7%以上的新机床，安装时都不符合其技术指标；90%使用中的数控机床处于失准工作状态。因此，对机床工作状态进行监控和对机床精度进行经常的测试是非常必要的，以便及时发现和解决问题，提高零件加工精度。
目前数控机床位置精度的检验通常采用国际标准ISO230-2或国家标准GB10931-89等。同一台机床，由于采用的标准不同，所得到的位置精度也不相同，因此在选择数控机床的精度指标时，也要注意它所采用的标准。数控机床的位置标准通常指各数控轴的反向偏差和定位精度。对于这二者的测定和补偿是提高加工精度的必要途径。
一、反向偏差
在数控机床上，由于各坐标轴进给传动链上驱动部件(如伺服电动机、伺服液压马达和步进电动机等)的反向死区、各机械运动传动副的反向间隙等误差的存在，造成各坐标轴在由正向运动转为反向运动时形成反向偏差，通常也称反向间隙或失动量。对于采用半闭环伺服系统的数控机床，反向偏差的存在就会影响到机床的定位精度和重复定位精度，从而影响产品的加工精度。如在G01切削运动时，反向偏差会影响插补运动的精度，若偏差过大就会造成“圆不够圆，方不够方”的情形；而在G00快速定位运动中，反向偏差影响机床的定位精度，使得钻孔、镗孔等孔加工时各孔间的位置精度降低。同时，随着设备投入运行时间的增长，反向偏差还会随因磨损造成运动副间隙的逐渐增大而增加，因此需要定期对机床各坐标轴的反向偏差进行测定和补偿。
（1）反向偏差的测定
反向偏差的测定方法：在所测量坐标轴的行程内，预先向正向或反向移动一个距离并以此停止位置为基准，再在同一方向给予一定移动指令值，使之移动一段距离，然后再往相反方向移动相同的距离，测量停止位置与基准位置之差。在靠近行程的中点及两端的三个位置分别进行多次测定(一般为七次)，求出各个位置上的平均值，以所得平均值中的最大值为反向偏差测量值。在测量时一定要先移动一段距离，否则不能得到正确的反向偏差值。
测量直线运动轴的反向偏差时，测量工具通常采有千分表或百分表，若条件允许，可使用双频激光干涉仪进行测量。当采用千分表或百分表进行测量时，需要注意的是表座和表杆不要伸出过高过长，因为测量时由于悬臂较长，表座易受力移动，造成计数不准，补偿值也就不真实了。若采用编程法实现测量，则能使测量过程变得更便捷更精确。
例如，在三坐标立式机床上测量X轴的反向偏差，可先将表压住主轴的圆柱表面，然后运行如下程序进行测量：
N10 G91 G01 X50 F1000；工作台右移
N20 X－50；工作台左移，消除传动间隙
N30 G04 X5；暂停以便观察
N40 Z50；Z轴抬高让开
N50 X-50：工作台左移
N60 X50：工作台右移复位
N70 Z-50：Z轴复位
N80 G04 X5：暂停以便观察
N90 M99；
需要注意的是，在工作台不同的运行速度下所测出的结果会有所不同。一般情况下，低速的测出值要比高速的大，特别是在机床轴负荷和运动阻力较大时。低速运动时工作台运动速度较低，不易发生过冲超程(相对“反向间隙”)，因此测出值较大；在高速时，由于工作台速度较高，容易发生过冲超程，测得值偏小。
回转运动轴反向偏差量的测量方法与直线轴相同，只是用于检测的仪器不同而已。
（2）反向偏差的补偿
国产数控机床，定位精度有不少>0.02mm，但没有补偿功能。对这类机床，在某些场合下，可用编程法实现单向定位，清除反向间隙，在机械部分不变的情况下，只要低速单向定位到达插补起始点，然后再开始插补加工。插补进给中遇反向时，给反向间隙值再正式插补，即可提高插补加工的精度，基本上可以保证零件的公差要求。
对于其他类别的数控机床，通常数控装置内存中设有若干个地址,专供存储各轴的反向间隙值。当机床的某个轴被指令改变运动方向时，数控装置会自动读取该轴的反向间隙值，对坐标位移指令值进行补偿、修正，使机床准确地定位在指令位置上，消除或减小反向偏差对机床精度的不利影响。
一般数控系统只有单一的反向间隙补偿值可供使用，为了兼顾高、低速的运动精度，除了要在机械上做得更好以外，只能将在快速运动时测得的反向偏差值作为补偿值输入，因此难以做到平衡、兼顾快速定位精度和切削时的插补精度。
对于FANUC0i、FANUC18i等数控系统，有用于快速运动(G00)和低速切削进给运动(G01)的两种反向间隙补偿可供选用。根据进给方式的不同，数控系统自动选择使用不同的补偿值，完成较高精度的加工。
将G01切削进给运动测得的反向间隙值A 输入参数NO11851(G01的测试速度可根据常用的切削进给速度及机床特性来决定)，将G00测得的反向间隙值B 输入参数NO11852。需要注意的是，若要数控系统执行分别指定的反向间隙补偿，应将参数号码1800的第四位(RBK)设定为1；若RBK设定为0，则不执行分别指定的反向间隙补偿。G02、G03、JOG与G01使用相同的补偿值。
二、定位精度
数控机床的定位精度是指所测量的机床运动部件在数控系统控制下运动所能达到的位置精度，是数控机床有别于普通机床的一项重要精度，它与机床的几何精度共同对机床切削精度产生重要的影响，尤其对孔隙加工中的孔距误差具有决定性的影响。一台数控机床可以从它所能达到的定位精度判出它的加工精度，所以对数控机床的定位精度进行检测和补偿是保证加工质量的必要途径。
（1）定位精度的测定
目前多采用双频激光干涉仪对机床检测和处理分析，利用激光干涉测量原理，以激光实时波长为测量基准，所以提高了测试精度及增强了适用范围。检测方法如下：
①安装双频激光干涉仪；
②在需要测量的机床坐标轴方向上安装光学测量装置；
③调整激光头，使测量轴线与机床移动轴线共线或平行，即将光路预调准直；
④待激光预热后输入测量参数；
⑤按规定的测量程序运动机床进行测量；
⑥数据处理及结果输出。
（2）定位精度的补偿
若测得数控机床的定位误差超出误差允许范围，则必须对机床进行误差补偿。常用方法是计算出螺距误差补偿表，手动输入机床CNC系统，从而消除定位误差，由于数控机床三轴或四轴补偿点可能有几百上千点，所以手动补偿需要花费较多时间，并且容易出错。
现在通过RS232接口将计算机与机床CNC控制器联接起来，用VB编写的自动校准软件控制激光干涉仪与数控机床同步工作，实现对数控机床定位精度的自动检测及自动螺距误差补偿，其补偿方法如下：
①备份CNC 控制系统中的已有补偿参数；
②由计算机产生进行逐点定位精度测量的机床CNC程序，并传送给CNC 系统；
③自动测量各点的定位误差；
④根据指定的补偿点产生一组新的补偿参数，并传送给CNC系统，螺距自动补偿完成；
⑤重复③进行精度验证。
根据数控机床各轴的精度状况，利用螺距误差自动补偿功能和反向间隙补偿功能，合理地选择分配各轴补偿点，使数控机床达到最佳精度状态，并大大提高了检测机床定位精度的效率。
定位精度是数控机床的一个重要指标。尽管在用户购选时可以尽量挑选精度高误差小的机床，但是随着设备投入使用时间越长，设备磨损越厉害，造成机床的定位误差越来越大，这对加工和生产的零件有着致命的影响。采用以上方法对机床各坐标轴的反向偏差、定位精度进行准确测量和补偿，可以很好地减小或消除反向偏差对机床精度的不利影响，提高机床的定位精度，使机床处于最佳精度状态，从而保证零件的加工质量。
歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對廠商高品質的刀具需求，我們可以協助廠商滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS刀具、協助客戶設計刀具流程、Carbide Cutting tools設計、航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、汽車業刀具設計等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！ BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 TEL:+886 4 24710048 / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,TaiwanWelcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
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五轴联动数控加工中的刀具补偿方法www.tool-tool.com
Bewise Inc. www.tool-tool.com Reference source from the internet.
刀具补偿是现代计算机数控（CNC）系统所具有的重要功能之一，可分为刀具半径补偿和长度补偿两种。就目前而言，应用于二维轮廓加工的两坐标联动数控系统基本都具备刀具补偿功能，而多坐标（三坐标以上）联动数控系统中对于刀具补偿功能还未能得到较好解决。特别是五轴联动加工中，由于刀具的旋转运动，使得五轴联动刀具补偿较难实现。国外几个主要CNC生产商在其高档的五轴联动数控系统中已经带有刀具补偿功能，如SIEMENS的SINUMERIC840D系统具有将三维空间向量转换为实际机械轴角度的计算能力的“3D Tool Radius Compensation”功能，而所带的坐标转换（或位置变换）功能其实质就是五轴刀具长度补偿。国内有关五轴联动加工刀具补偿方法的研究并不多，因此，本文将对五轴加工中的刀具补偿问题进行深入研究，分别对五轴加工中的刀具半径补偿和长度补偿的实现方法进行详细叙述，以期能建立并完善五轴联动CNC系统的刀具半径和长度补偿功能。
1 五坐标加工数控程序的生成
五坐标加工主要应用于复杂曲面零件如整体叶轮等的加工，因此其数控程序的生成必须借助于一些自动编程软件如UGII、HyperMill等。在应用这些软件进行五坐标数控编程时得到的刀位文件（CLF）是不依赖于具体机床结构和形式的，而且它提供了五轴曲面加工时刀具底端面中心（以下简称为刀具中心）在工件坐标系下要求位移到的位置坐标以及刀轴的方位矢量等信息，但CLF文件的生成却依据了选用刀具的形式（如平底刀等）和刀具半径等参数。因此，五轴加工程序的生成与刀具参数设定有密切的关系。另外，利用编程软件的后置处理模块根据选用五轴数控机床的结构形式等参数将CLF文件转换成加工曲面所需的数控程序。假定某加工程序段为：G01XxYyZzAaCc其中位置坐标值x、y、z可以是刀具中心坐标也可以是机床主轴端（Spindle none）的坐标a、c分别为绕X轴、Z轴的角度坐标值。当x、y、z为刀具中心坐标时称为刀具中心编程，当x、y、z为主轴端坐标时称为主轴端编程，如图1所示。但无论哪种编程方式都需数控系统具有刀具自动补偿功能才能加工出我们所需要的零件。以下将以图2所示结构形式五轴数控机床和刀具（平底刀）中心编程为例分别叙述五轴联动加工中的刀具半径补偿和长度补偿。
2 现行五轴数控编程在刀具半径补偿方面的不足
上节中叙述的五坐标数控加工编程方式和得到的数控指令格式是根据国际标准化组织（ISO）有关数控编程的标准ISO 6983进行的。对平面两轴或两轴半的加工而言，在ISO 6983中常使用G41/G42功能来补偿刀具半径。补偿时根据数控程序中提供的相关信息如G17/G18/G19进行加工平面选择配合G41/G42左右刀具补偿选取，利用一般较低档的控制器即可完成。但是，对于三轴特别是五轴加工，即刀具半径的补偿要在三维空间完成，ISO 6983中所提供的信息则显得不足，如G17/G18/G19、G41/G42等已经失效，插补程序段中提供的数据信息又仅仅是刀具中心点坐标和刀具轴的方位角，刀具半径补偿实际上不可能进行，因为控制器不知道该往哪个方向进行补偿，而这个方向对于刀具半径补偿非常重要。因此，如果要进行三维空间刀具半径补偿功能，则必须在数控加工程序段中提供补偿方向向量等信息，如FANUC15-MA(FANUC,1994)、CINCINNATI MILACRON ACRA-MATIC 950(CINCINNATI,1990)等，FANUC控制器采用了1JK码来表示，而CINCINNATI则是采用POR码来表示。另外，在后置处理方面，目前的CAM编程系统通常并不提供刀具补偿向量模式，只有在五轴机床的原厂商对其个别型式的五轴机床专用的后置处理程序，才提供了这种五轴三维刀具补偿向量模式的输出，但其价格却相当昂贵。本文假定得到的加工程序段中提供了刀具半径补偿向量。
3五轴刀具半径补偿
在进行刀具中心编程时，由CAD/CAM软件生成的数控程序是根据编程刀具半径计算出来的刀具中心运动轨迹。实际加工时，必须保证刀具半径与编程时刀具半径相等。一旦刀具半径发生改变，尤其是刀具在加工的过程由于磨损而造成尺寸变化时，程序的重复使用就受到很大的限制，必须根据所用刀具半径返回CAD/CAM系统重新产生CLF文件经后置处理生成新的NC程序。这样会造成程序维护不易，生产效率无法提高，若考虑更换新刀具加工，则又存在增加备用刀具成本的缺点。如果所使用的五轴CNC系统带有刀具半径补偿功能，则原有的程序和刀具仍然可用，只需在加工前测量出刀具实际半径值即可，不必每次加工都保证所使用刀具半径与编程刀具半径相等。如图3所示的是使用刀具半径补偿功能前后对加工结果的影响。
如图4所示，在加工过程中某数控加工程序段表示的刀具中心位置坐标、刀轴方位角度坐标以及补偿方向单位向量为 ，刀具与加工表面切触于点 ，进给方向垂直纸面向里，刀具底沿在纸面的投影为一椭圆。图4中实线表示编程使用的刀具，半径为Rp，点划线表示实际加工时所用的刀具，半径为R。显然当R=Rp时刀具底沿与理论加工表面切触于C，无须进行半径补偿而直接进行长度补偿计算主轴端点位置坐标即可。但是若RRP时，则必须先进行半径补偿，半径补偿的目的是要让实际加工刀具的底沿仍与理论加工表面切触于C。图5中虚线表示刀具沿补偿方向进行补偿后刀具的位置。
定义：将由编程刀具中心位置即 指向刀具半径补偿后实际加工刀具中心 的矢量称为刀具半径补偿向量，用Vr表示。
由刀具半径补偿向量定义可得
式(2)中｛ip，jp，kp｝在程序段中已给出，为已知，由式(1)和式(2)可以很容易求得刀具半径补偿向量Vr为
由式(3)和式(4)可得到刀具半径补偿后实际加工刀具中心O的坐标分别为
因为刀具半径补偿不能改变刀具姿态，也就是补偿前后刀具轴向方位角不变，刀具只是沿Vr平移，插补预处理时只需将得到的主轴端点坐标做平移变换即可。
4五轴刀具长度补偿
ISO 6983标准中规定了刀具旋转的角度，从而也就能确定出刀具的轴向向量，因此刀具长度补偿仍然有效，长度补偿的方向即为刀具的轴向向量。从编程方面看，无论采用哪种编程得到的数控加工程序，CNC控制器中刀具长度补偿功能对最后的加工结果都非常重要。如果刀具中心编程得到的数控程序不经过长度补偿得到主轴端点坐标，则数控系统会将刀具中心点误认为是主轴端点，加工结果可想而知，如图5a所示。主轴端编程是根据编程中使用的刀具长度计算出来的主轴端点的运动轨迹。实际加工时，必须保证刀具长度与编程时刀具长度相等。一旦刀具长度发生改变，
则刀具中心点不可能到达编程时的刀具中心，因此也需要对刀具长度变化进行补偿。如图5b所示为主轴端编程时刀具长度补偿前后对加工结果的影响。以下将讨论图5a所示刀具中心编程中的刀具长度补偿。
图5a中假定加工刀具长度为l，刀具半径补偿后的刀具中心位置坐标及刀轴方位角度坐标分别为(x,y,z,ap,cp)，要求的是主轴端点坐标(xs,ys,zs)。问题关键在于刀具轴向单位向量T的求解。如图2可知，初始状态下，刀具竖直向下且平行于机床坐标系的Z轴，即T0={0,0,1}。刀具分别绕X轴和Z轴旋转ap和cp角后刀轴单位向量为T，由坐标变换原理有
由式（6）可得
主轴端点坐标可由下式确定出
综合式（5）和式（8）可得图2所示结构形式的五轴联动数控机床采用刀具中心点编程时经刀具半径和长度补偿后的刀具主轴端点坐标表示为
将式（9）中的位置坐标和摆角坐标(ap,cp)输入插补模块即可使刀具中心按照编程轨迹运行。
5结语
基于刀具补偿功能在五轴数控加工中的重要性，本文在分析现行编程标准对于实现刀具半径补偿功能不足的基础上，通过引入刀具半径补偿向量讨论了图2所示结构形式的五轴联动数控机床的刀具长度和半径补偿的实现。对于其他形式的机床可以通过类似的方法分别实现刀具半径补偿和长度补偿。
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刀具补偿是现代计算机数控（CNC）系统所具有的重要功能之一，可分为刀具半径补偿和长度补偿两种。就目前而言，应用于二维轮廓加工的两坐标联动数控系统基本都具备刀具补偿功能，而多坐标（三坐标以上）联动数控系统中对于刀具补偿功能还未能得到较好解决。特别是五轴联动加工中，由于刀具的旋转运动，使得五轴联动刀具补偿较难实现。国外几个主要CNC生产商在其高档的五轴联动数控系统中已经带有刀具补偿功能，如SIEMENS的SINUMERIC840D系统具有将三维空间向量转换为实际机械轴角度的计算能力的“3D Tool Radius Compensation”功能，而所带的坐标转换（或位置变换）功能其实质就是五轴刀具长度补偿。国内有关五轴联动加工刀具补偿方法的研究并不多，因此，本文将对五轴加工中的刀具补偿问题进行深入研究，分别对五轴加工中的刀具半径补偿和长度补偿的实现方法进行详细叙述，以期能建立并完善五轴联动CNC系统的刀具半径和长度补偿功能。
1 五坐标加工数控程序的生成
五坐标加工主要应用于复杂曲面零件如整体叶轮等的加工，因此其数控程序的生成必须借助于一些自动编程软件如UGII、HyperMill等。在应用这些软件进行五坐标数控编程时得到的刀位文件（CLF）是不依赖于具体机床结构和形式的，而且它提供了五轴曲面加工时刀具底端面中心（以下简称为刀具中心）在工件坐标系下要求位移到的位置坐标以及刀轴的方位矢量等信息，但CLF文件的生成却依据了选用刀具的形式（如平底刀等）和刀具半径等参数。因此，五轴加工程序的生成与刀具参数设定有密切的关系。另外，利用编程软件的后置处理模块根据选用五轴数控机床的结构形式等参数将CLF文件转换成加工曲面所需的数控程序。假定某加工程序段为：G01XxYyZzAaCc其中位置坐标值x、y、z可以是刀具中心坐标也可以是机床主轴端（Spindle none）的坐标a、c分别为绕X轴、Z轴的角度坐标值。当x、y、z为刀具中心坐标时称为刀具中心编程，当x、y、z为主轴端坐标时称为主轴端编程，如图1所示。但无论哪种编程方式都需数控系统具有刀具自动补偿功能才能加工出我们所需要的零件。以下将以图2所示结构形式五轴数控机床和刀具（平底刀）中心编程为例分别叙述五轴联动加工中的刀具半径补偿和长度补偿。
2 现行五轴数控编程在刀具半径补偿方面的不足
上节中叙述的五坐标数控加工编程方式和得到的数控指令格式是根据国际标准化组织（ISO）有关数控编程的标准ISO 6983进行的。对平面两轴或两轴半的加工而言，在ISO 6983中常使用G41/G42功能来补偿刀具半径。补偿时根据数控程序中提供的相关信息如G17/G18/G19进行加工平面选择配合G41/G42左右刀具补偿选取，利用一般较低档的控制器即可完成。但是，对于三轴特别是五轴加工，即刀具半径的补偿要在三维空间完成，ISO 6983中所提供的信息则显得不足，如G17/G18/G19、G41/G42等已经失效，插补程序段中提供的数据信息又仅仅是刀具中心点坐标和刀具轴的方位角，刀具半径补偿实际上不可能进行，因为控制器不知道该往哪个方向进行补偿，而这个方向对于刀具半径补偿非常重要。因此，如果要进行三维空间刀具半径补偿功能，则必须在数控加工程序段中提供补偿方向向量等信息，如FANUC15-MA(FANUC,1994)、CINCINNATI MILACRON ACRA-MATIC 950(CINCINNATI,1990)等，FANUC控制器采用了1JK码来表示，而CINCINNATI则是采用POR码来表示。另外，在后置处理方面，目前的CAM编程系统通常并不提供刀具补偿向量模式，只有在五轴机床的原厂商对其个别型式的五轴机床专用的后置处理程序，才提供了这种五轴三维刀具补偿向量模式的输出，但其价格却相当昂贵。本文假定得到的加工程序段中提供了刀具半径补偿向量。
3五轴刀具半径补偿
在进行刀具中心编程时，由CAD/CAM软件生成的数控程序是根据编程刀具半径计算出来的刀具中心运动轨迹。实际加工时，必须保证刀具半径与编程时刀具半径相等。一旦刀具半径发生改变，尤其是刀具在加工的过程由于磨损而造成尺寸变化时，程序的重复使用就受到很大的限制，必须根据所用刀具半径返回CAD/CAM系统重新产生CLF文件经后置处理生成新的NC程序。这样会造成程序维护不易，生产效率无法提高，若考虑更换新刀具加工，则又存在增加备用刀具成本的缺点。如果所使用的五轴CNC系统带有刀具半径补偿功能，则原有的程序和刀具仍然可用，只需在加工前测量出刀具实际半径值即可，不必每次加工都保证所使用刀具半径与编程刀具半径相等。如图3所示的是使用刀具半径补偿功能前后对加工结果的影响。
如图4所示，在加工过程中某数控加工程序段表示的刀具中心位置坐标、刀轴方位角度坐标以及补偿方向单位向量为 ，刀具与加工表面切触于点 ，进给方向垂直纸面向里，刀具底沿在纸面的投影为一椭圆。图4中实线表示编程使用的刀具，半径为Rp，点划线表示实际加工时所用的刀具，半径为R。显然当R=Rp时刀具底沿与理论加工表面切触于C，无须进行半径补偿而直接进行长度补偿计算主轴端点位置坐标即可。但是若RRP时，则必须先进行半径补偿，半径补偿的目的是要让实际加工刀具的底沿仍与理论加工表面切触于C。图5中虚线表示刀具沿补偿方向进行补偿后刀具的位置。
定义：将由编程刀具中心位置即 指向刀具半径补偿后实际加工刀具中心 的矢量称为刀具半径补偿向量，用Vr表示。
由刀具半径补偿向量定义可得
式(2)中｛ip，jp，kp｝在程序段中已给出，为已知，由式(1)和式(2)可以很容易求得刀具半径补偿向量Vr为
由式(3)和式(4)可得到刀具半径补偿后实际加工刀具中心O的坐标分别为
因为刀具半径补偿不能改变刀具姿态，也就是补偿前后刀具轴向方位角不变，刀具只是沿Vr平移，插补预处理时只需将得到的主轴端点坐标做平移变换即可。
4五轴刀具长度补偿
ISO 6983标准中规定了刀具旋转的角度，从而也就能确定出刀具的轴向向量，因此刀具长度补偿仍然有效，长度补偿的方向即为刀具的轴向向量。从编程方面看，无论采用哪种编程得到的数控加工程序，CNC控制器中刀具长度补偿功能对最后的加工结果都非常重要。如果刀具中心编程得到的数控程序不经过长度补偿得到主轴端点坐标，则数控系统会将刀具中心点误认为是主轴端点，加工结果可想而知，如图5a所示。主轴端编程是根据编程中使用的刀具长度计算出来的主轴端点的运动轨迹。实际加工时，必须保证刀具长度与编程时刀具长度相等。一旦刀具长度发生改变，
则刀具中心点不可能到达编程时的刀具中心，因此也需要对刀具长度变化进行补偿。如图5b所示为主轴端编程时刀具长度补偿前后对加工结果的影响。以下将讨论图5a所示刀具中心编程中的刀具长度补偿。
图5a中假定加工刀具长度为l，刀具半径补偿后的刀具中心位置坐标及刀轴方位角度坐标分别为(x,y,z,ap,cp)，要求的是主轴端点坐标(xs,ys,zs)。问题关键在于刀具轴向单位向量T的求解。如图2可知，初始状态下，刀具竖直向下且平行于机床坐标系的Z轴，即T0={0,0,1}。刀具分别绕X轴和Z轴旋转ap和cp角后刀轴单位向量为T，由坐标变换原理有
由式（6）可得
主轴端点坐标可由下式确定出
综合式（5）和式（8）可得图2所示结构形式的五轴联动数控机床采用刀具中心点编程时经刀具半径和长度补偿后的刀具主轴端点坐标表示为
将式（9）中的位置坐标和摆角坐标(ap,cp)输入插补模块即可使刀具中心按照编程轨迹运行。
5结语
基于刀具补偿功能在五轴数控加工中的重要性，本文在分析现行编程标准对于实现刀具半径补偿功能不足的基础上，通过引入刀具半径补偿向量讨论了图2所示结构形式的五轴联动数控机床的刀具长度和半径补偿的实现。对于其他形式的机床可以通过类似的方法分别实现刀具半径补偿和长度补偿。
Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
Bewise Inc. www.tool-tool.com
Tool www.tool-tool.com
Bewise Inc. www.tool-tool.com Reference source from the internet.
portable cutting tool 便携式切割工具
cutting tool 刀削工具; 切削工具
portable electric tool 轻便电力工具
portable electrical tool 轻便电力工具
portable machine tool 轻便工具机
portable power tool 便携式电动工具
d portable electric tool 手提式轻便电力工具
ternal screw cutting tool 内螺纹车刀
right hand cutting tool 右车刀
measuring and cutting tool 量具刃具
metal cutting machine tool 金属切削机床
metal cutting tool 切悉具
multiple cutting edge tool 多刃刀具
non-standard cutting tool 非标准刀具
ordinary cutting tool 普通切削刀具
pipe cutting machine tool 切管机床
plane cutting tool 平面刀具
planer cutting tool 刨床切削刀具
precision cutting tool 精密刀具
right-hand-cutting tool 右削车刀
round-nose cutting tool 圆头切刀
screw cutting tool 螺纹车刀
single cutting tool 单刃刀
single-edged cutting tool 单刃刀
single-point cutting tool 单刃刀具
thread cutting tool 螺纹切削刀具
thread-cutting tool 螺纹切削刀具
tube cutting machine tool 管子切割机床
under cutting turning tool 沉割车刀
welding-cutting tool 焊割具
male screw cutting tool 外螺纹车刀
machine tool cutting oil 机床切削油
machine cutting tool 机床切削工具
lathe cutting tool 车床切削刀具
laser cutting machine tool 激光切割机
land of cutting tool 刀刃棱面; 刀刃梭面
internal screw cutting tool 内螺纹车刀
gear cutting tool 齿轮加工刀具; 齿轮切削刀具; 齿轮切削刀具
external screw cutting tool 外螺纹车刀
female screw cutting tool 内螺纹车刀
fiber-cutting tool 光纤切割工具
fibre-cutting tool 光纤切割工具
ged cutting tool 单刃刀
hand cutting tool 手工刀具
high precision cutting tool 高精密度切削工具
alumina-based cutting tool 氧化铝基切削工具
angle cutting tool 倒角铣刀
cemented carbide cutting tool 硬质合金刀具
ceramic coated cutting tool 陶瓷涂层切削工具
ceramic cutting tool 陶瓷刀具
combination cutting tool 复合刀具
composite ceramic cutting tool 复合陶瓷刀具
corundum cutting tool 硬质合金刀具
cutting off tool 切断车刀
cutting off tool rest 车刀架
cutting tool alloy 切悉具合金
cutting tool life 切悉具寿命
cutting tool presetter 调刀仪
cutting tool steel 刃具钢; 切削工具钢
cutting-away tool 切削工具
cutting-in tool 切进刀
cutting-off tool 割刀
cutting-tool angle 刀具角度
cutting-tool coolant oil 切削工具冷却油
cutting-tool engineering 刀具技术
cutting-tool lubricant 刀具冷却润滑剂
cutting-tool steel 切削工具钢
cutting-tool wear 刀具磨损
down-cutting tool 立刨刀; 插刀; 插刀
hand-held portable electric tool 手提式轻便电力工具
cutting tool arbor for CNC machine tool 数控机床刀杆
new composite ceramic cutting tool 新型复合陶瓷刀具
non-standard axial cutting tool 非标准轴向刀具
non-standard carbide cutting tool 非标准合金刀具
penetration of a cutting tool 吃刀
silicon nitride based cutting tool 氮化硅基切削工具
square hole cutting slotting tool 方孔插刀
les for holding cutting tool 刀具孔数
indexable carbide insert cutting tool 硬质合金可转位刀具
indexable mechanically-clamped cutting tool 可转位机夹刀具
gear cutting tool grinding machine 齿轮切削工具磨床
ceramic coated metal cutting tool 陶瓷涂层金属切削工具
cutting tool for CNC machine 数控机床刀具
cutting tool for paperboard-box 纸箱刀具
cutting-tool damage detection device 刀具损伤探测器
number of holes for holding cutting tool 刀具孔数
single-point tool thread cutting machine 单刃刀具螺纹铣床
high-speed and multi-tool cutting method 高速多刀复刃切削法
AL2 O3-SiC whisker cutting tool 碳化硅晶须增强氧化铝切削工具
portable electric tool (电钻电锯等) 手提式电动工具
portable 携带; 携带式; 携带式的; 携带用机械; &nb....
Q-type mechanically-clamped carbide cutting-off tool 机夹Q型切断刀
CO^2 laser cutting and carving machine tool 二氧化碳激光切割及雕刻机床
CO2 laser cutting and carving machine tool 二氧化碳激光切割及雕刻机床
cutting 削减; 下锯; 数控切削; 删节; &....
tool 走狗; 装在马车; 装配工具; 爪牙; ....
portable color portable 手提的手提彩色电视
Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
Bewise Inc. www.tool-tool.com
portable cutting tool 便携式切割工具
cutting tool 刀削工具; 切削工具
portable electric tool 轻便电力工具
portable electrical tool 轻便电力工具
portable machine tool 轻便工具机
portable power tool 便携式电动工具
d portable electric tool 手提式轻便电力工具
ternal screw cutting tool 内螺纹车刀
right hand cutting tool 右车刀
measuring and cutting tool 量具刃具
metal cutting machine tool 金属切削机床
metal cutting tool 切悉具
multiple cutting edge tool 多刃刀具
non-standard cutting tool 非标准刀具
ordinary cutting tool 普通切削刀具
pipe cutting machine tool 切管机床
plane cutting tool 平面刀具
planer cutting tool 刨床切削刀具
precision cutting tool 精密刀具
right-hand-cutting tool 右削车刀
round-nose cutting tool 圆头切刀
screw cutting tool 螺纹车刀
single cutting tool 单刃刀
single-edged cutting tool 单刃刀
single-point cutting tool 单刃刀具
thread cutting tool 螺纹切削刀具
thread-cutting tool 螺纹切削刀具
tube cutting machine tool 管子切割机床
under cutting turning tool 沉割车刀
welding-cutting tool 焊割具
male screw cutting tool 外螺纹车刀
machine tool cutting oil 机床切削油
machine cutting tool 机床切削工具
lathe cutting tool 车床切削刀具
laser cutting machine tool 激光切割机
land of cutting tool 刀刃棱面; 刀刃梭面
internal screw cutting tool 内螺纹车刀
gear cutting tool 齿轮加工刀具; 齿轮切削刀具; 齿轮切削刀具
external screw cutting tool 外螺纹车刀
female screw cutting tool 内螺纹车刀
fiber-cutting tool 光纤切割工具
fibre-cutting tool 光纤切割工具
ged cutting tool 单刃刀
hand cutting tool 手工刀具
high precision cutting tool 高精密度切削工具
alumina-based cutting tool 氧化铝基切削工具
angle cutting tool 倒角铣刀
cemented carbide cutting tool 硬质合金刀具
ceramic coated cutting tool 陶瓷涂层切削工具
ceramic cutting tool 陶瓷刀具
combination cutting tool 复合刀具
composite ceramic cutting tool 复合陶瓷刀具
corundum cutting tool 硬质合金刀具
cutting off tool 切断车刀
cutting off tool rest 车刀架
cutting tool alloy 切悉具合金
cutting tool life 切悉具寿命
cutting tool presetter 调刀仪
cutting tool steel 刃具钢; 切削工具钢
cutting-away tool 切削工具
cutting-in tool 切进刀
cutting-off tool 割刀
cutting-tool angle 刀具角度
cutting-tool coolant oil 切削工具冷却油
cutting-tool engineering 刀具技术
cutting-tool lubricant 刀具冷却润滑剂
cutting-tool steel 切削工具钢
cutting-tool wear 刀具磨损
down-cutting tool 立刨刀; 插刀; 插刀
hand-held portable electric tool 手提式轻便电力工具
cutting tool arbor for CNC machine tool 数控机床刀杆
new composite ceramic cutting tool 新型复合陶瓷刀具
non-standard axial cutting tool 非标准轴向刀具
non-standard carbide cutting tool 非标准合金刀具
penetration of a cutting tool 吃刀
silicon nitride based cutting tool 氮化硅基切削工具
square hole cutting slotting tool 方孔插刀
les for holding cutting tool 刀具孔数
indexable carbide insert cutting tool 硬质合金可转位刀具
indexable mechanically-clamped cutting tool 可转位机夹刀具
gear cutting tool grinding machine 齿轮切削工具磨床
ceramic coated metal cutting tool 陶瓷涂层金属切削工具
cutting tool for CNC machine 数控机床刀具
cutting tool for paperboard-box 纸箱刀具
cutting-tool damage detection device 刀具损伤探测器
number of holes for holding cutting tool 刀具孔数
single-point tool thread cutting machine 单刃刀具螺纹铣床
high-speed and multi-tool cutting method 高速多刀复刃切削法
AL2 O3-SiC whisker cutting tool 碳化硅晶须增强氧化铝切削工具
portable electric tool (电钻电锯等) 手提式电动工具
portable 携带; 携带式; 携带式的; 携带用机械; &nb....
Q-type mechanically-clamped carbide cutting-off tool 机夹Q型切断刀
CO^2 laser cutting and carving machine tool 二氧化碳激光切割及雕刻机床
CO2 laser cutting and carving machine tool 二氧化碳激光切割及雕刻机床
cutting 削减; 下锯; 数控切削; 删节; &....
tool 走狗; 装在马车; 装配工具; 爪牙; ....
portable color portable 手提的手提彩色电视
Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
Bewise Inc. www.tool-tool.com
nanotechnology / Feynman's Talk www.tool-tool.com
Bewise Inc. www.tool-tool.com Reference source from the internet.
There's Plenty of Room at the Bottom
An Invitation to Enter a New Field of Physics
ref: http://elearning.stut.edu.tw/m_facture/Nanotech/Web/ch11.htm
by Richard P. Feynman
This transcript of the classic talk that Richard Feynman gave on December 29th 1959 at the annual meeting of the American Physical Society at the California Institute of Technology (Caltech) was first published in the February 1960 issue of Caltech's Engineering and Science, which owns the copyright. It has been made available on the web at http://www.zyvex.com/nanotech/feynman.html with their kind permission.
Information on the Feynman Prizes
Links to pages on Feynman
For an account of the talk and how people reacted to it, see chapter 4 of Nano! by Ed Regis, Little/Brown 1995. An excellent technical introduction to nanotechnology is Nanosystems: molecular machinery, manufacturing, and computation by K. Eric Drexler, Wiley 1992.
I imagine experimental physicists must often look with envy at men like Kamerlingh Onnes, who discovered a field like low temperature, which seems to be bottomless and in which one can go down and down. Such a man is then a leader and has some temporary monopoly in a scientific adventure. Percy Bridgman, in designing a way to obtain higher pressures, opened up another new field and was able to move into it and to lead us all along. The development of ever higher vacuum was a continuing development of the same kind.
I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, ``What are the strange particles?'') but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications.
What I want to talk about is the problem of manipulating and controlling things on a small scale.
As soon as I mention this, people tell me about miniaturization, and how far it has progressed today. They tell me about electric motors that are the size of the nail on your small finger. And there is a device on the market, they tell me, by which you can write the Lord's Prayer on the head of a pin. But that's nothing; that's the most primitive, halting step in the direction I intend to discuss. It is a staggeringly small world that is below. In the year 2000, when they look back at this age, they will wonder why it was not until the year 1960 that anybody began seriously to move in this direction.
Why cannot we write the entire 24 volumes of the Encyclopedia Brittanica on the head of a pin?
Let's see what would be involved. The head of a pin is a sixteenth of an inch across. If you magnify it by 25,000 diameters, the area of the head of the pin is then equal to the area of all the pages of the Encyclopaedia Brittanica. Therefore, all it is necessary to do is to reduce in size all the writing in the Encyclopaedia by 25,000 times. Is that possible? The resolving power of the eye is about 1/120 of an inch---that is roughly the diameter of one of the little dots on the fine half-tone reproductions in the Encyclopaedia. This, when you demagnify it by 25,000 times, is still 80 angstroms in diameter---32 atoms across, in an ordinary metal. In other words, one of those dots still would contain in its area 1,000 atoms. So, each dot can easily be adjusted in size as required by the photoengraving, and there is no question that there is enough room on the head of a pin to put all of the Encyclopaedia Brittanica.
Furthermore, it can be read if it is so written. Let's imagine that it is written in raised letters of metal; that is, where the black is in the Encyclopedia, we have raised letters of metal that are actually 1/25,000 of their ordinary size. How would we read it?
If we had something written in such a way, we could read it using techniques in common use today. (They will undoubtedly find a better way when we do actually have it written, but to make my point conservatively I shall just take techniques we know today.) We would press the metal into a plastic material and make a mold of it, then peel the plastic off very carefully, evaporate silica into the plastic to get a very thin film, then shadow it by evaporating gold at an angle against the silica so that all the little letters will appear clearly, dissolve the plastic away from the silica film, and then look through it with an electron microscope!
There is no question that if the thing were reduced by 25,000 times in the form of raised letters on the pin, it would be easy for us to read it today. Furthermore; there is no question that we would find it easy to make copies of the master; we would just need to press the same metal plate again into plastic and we would have another copy.
How do we write small?
The next question is: How do we write it? We have no standard technique to do this now. But let me argue that it is not as difficult as it first appears to be. We can reverse the lenses of the electron microscope in order to demagnify as well as magnify. A source of ions, sent through the microscope lenses in reverse, could be focused to a very small spot. We could write with that spot like we write in a TV cathode ray oscilloscope, by going across in lines, and having an adjustment which determines the amount of material which is going to be deposited as we scan in lines.
This method might be very slow because of space charge limitations. There will be more rapid methods. We could first make, perhaps by some photo process, a screen which has holes in it in the form of the letters. Then we would strike an arc behind the holes and draw metallic ions through the holes; then we could again use our system of lenses and make a small image in the form of ions, which would deposit the metal on the pin.
A simpler way might be this (though I am not sure it would work): We take light and, through an optical microscope running backwards, we focus it onto a very small photoelectric screen. Then electrons come away from the screen where the light is shining. These electrons are focused down in size by the electron microscope lenses to impinge directly upon the surface of the metal. Will such a beam etch away the metal if it is run long enough? I don't know. If it doesn't work for a metal surface, it must be possible to find some surface with which to coat the original pin so that, where the electrons bombard, a change is made which we could recognize later.
There is no intensity problem in these devices---not what you are used to in magnification, where you have to take a few electrons and spread them over a bigger and bigger screen; it is just the opposite. The light which we get from a page is concentrated onto a very small area so it is very intense. The few electrons which come from the photoelectric screen are demagnified down to a very tiny area so that, again, they are very intense. I don't know why this hasn't been done yet!
That's the Encyclopaedia Brittanica on the head of a pin, but let's consider all the books in the world. The Library of Congress has approximately 9 million volumes; the British Museum Library has 5 million volumes; there are also 5 million volumes in the National Library in France. Undoubtedly there are duplications, so let us say that there are some 24 million volumes of interest in the world.
What would happen if I print all this down at the scale we have been discussing? How much space would it take? It would take, of course, the area of about a million pinheads because, instead of there being just the 24 volumes of the Encyclopaedia, there are 24 million volumes. The million pinheads can be put in a square of a thousand pins on a side, or an area of about 3 square yards. That is to say, the silica replica with the paper-thin backing of plastic, with which we have made the copies, with all this information, is on an area of approximately the size of 35 pages of the Encyclopaedia. That is about half as many pages as there are in this magazine. All of the information which all of mankind has every recorded in books can be carried around in a pamphlet in your hand---and not written in code, but a simple reproduction of the original pictures, engravings, and everything else on a small scale without loss of resolution.
What would our librarian at Caltech say, as she runs all over from one building to another, if I tell her that, ten years from now, all of the information that she is struggling to keep track of--- 120,000 volumes, stacked from the floor to the ceiling, drawers full of cards, storage rooms full of the older books---can be kept on just one library card! When the University of Brazil, for example, finds that their library is burned, we can send them a copy of every book in our library by striking off a copy from the master plate in a few hours and mailing it in an envelope no bigger or heavier than any other ordinary air mail letter.
Now, the name of this talk is ``There is Plenty of Room at the Bottom''---not just ``There is Room at the Bottom.'' What I have demonstrated is that there is room---that you can decrease the size of things in a practical way. I now want to show that there is plenty of room. I will not now discuss how we are going to do it, but only what is possible in principle---in other words, what is possible according to the laws of physics. I am not inventing anti-gravity, which is possible someday only if the laws are not what we think. I am telling you what could be done if the laws are what we think; we are not doing it simply because we haven't yet gotten around to it.
Information on a small scale
Suppose that, instead of trying to reproduce the pictures and all the information directly in its present form, we write only the information content in a code of dots and dashes, or something like that, to represent the various letters. Each letter represents six or seven ``bits'' of information; that is, you need only about six or seven dots or dashes for each letter. Now, instead of writing everything, as I did before, on the surface of the head of a pin, I am going to use the interior of the material as well.
Let us represent a dot by a small spot of one metal, the next dash, by an adjacent spot of another metal, and so on. Suppose, to be conservative, that a bit of information is going to require a little cube of atoms 5 times 5 times 5---that is 125 atoms. Perhaps we need a hundred and some odd atoms to make sure that the information is not lost through diffusion, or through some other process.
I have estimated how many letters there are in the Encyclopaedia, and I have assumed that each of my 24 million books is as big as an Encyclopaedia volume, and have calculated, then, how many bits of information there are (10^15). For each bit I allow 100 atoms. And it turns out that all of the information that man has carefully accumulated in all the books in the world can be written in this form in a cube of material one two-hundredth of an inch wide--- which is the barest piece of dust that can be made out by the human eye. So there is plenty of room at the bottom! Don't tell me about microfilm!
This fact---that enormous amounts of information can be carried in an exceedingly small space---is, of course, well known to the biologists, and resolves the mystery which existed before we understood all this clearly, of how it could be that, in the tiniest cell, all of the information for the organization of a complex creature such as ourselves can be stored. All this information---whether we have brown eyes, or whether we think at all, or that in the embryo the jawbone should first develop with a little hole in the side so that later a nerve can grow through it---all this information is contained in a very tiny fraction of the cell in the form of long-chain DNA molecules in which approximately 50 atoms are used for one bit of information about the cell.
Better electron microscopes
If I have written in a code, with 5 times 5 times 5 atoms to a bit, the question is: How could I read it today? The electron microscope is not quite good enough, with the greatest care and effort, it can only resolve about 10 angstroms. I would like to try and impress upon you while I am talking about all of these things on a small scale, the importance of improving the electron microscope by a hundred times. It is not impossible; it is not against the laws of diffraction of the electron. The wave length of the electron in such a microscope is only 1/20 of an angstrom. So it should be possible to see the individual atoms. What good would it be to see individual atoms distinctly?
We have friends in other fields---in biology, for instance. We physicists often look at them and say, ``You know the reason you fellows are making so little progress?'' (Actually I don't know any field where they are making more rapid progress than they are in biology today.) ``You should use more mathematics, like we do.'' They could answer us---but they're polite, so I'll answer for them: ``What you should do in order for us to make more rapid progress is to make the electron microscope 100 times better.''
What are the most central and fundamental problems of biology today? They are questions like: What is the sequence of bases in the DNA? What happens when you have a mutation? How is the base order in the DNA connected to the order of amino acids in the protein? What is the structure of the RNA; is it single-chain or double-chain, and how is it related in its order of bases to the DNA? What is the organization of the microsomes? How are proteins synthesized? Where does the RNA go? How does it sit? Where do the proteins sit? Where do the amino acids go in? In photosynthesis, where is the chlorophyll; how is it arranged; where are the carotenoids involved in this thing? What is the system of the conversion of light into chemical energy?
It is very easy to answer many of these fundamental biological questions; you just look at the thing! You will see the order of bases in the chain; you will see the structure of the microsome. Unfortunately, the present microscope sees at a scale which is just a bit too crude. Make the microscope one hundred times more powerful, and many problems of biology would be made very much easier. I exaggerate, of course, but the biologists would surely be very thankful to you---and they would prefer that to the criticism that they should use more mathematics.
The theory of chemical processes today is based on theoretical physics. In this sense, physics supplies the foundation of chemistry. But chemistry also has analysis. If you have a strange substance and you want to know what it is, you go through a long and complicated process of chemical analysis. You can analyze almost anything today, so I am a little late with my idea. But if the physicists wanted to, they could also dig under the chemists in the problem of chemical analysis. It would be very easy to make an analysis of any complicated chemical substance; all one would have to do would be to look at it and see where the atoms are. The only trouble is that the electron microscope is one hundred times too poor. (Later, I would like to ask the question: Can the physicists do something about the third problem of chemistry---namely, synthesis? Is there a physical way to synthesize any chemical substance?
The reason the electron microscope is so poor is that the f- value of the lenses is only 1 part to 1,000; you don't have a big enough numerical aperture. And I know that there are theorems which prove that it is impossible, with axially symmetrical stationary field lenses, to produce an f-value any bigger than so and so; and therefore the resolving power at the present time is at its theoretical maximum. But in every theorem there are assumptions. Why must the field be symmetrical? I put this out as a challenge: Is there no way to make the electron microscope more powerful?
The marvelous biological system
The biological example of writing information on a small scale has inspired me to think of something that should be possible. Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly small. Many of the cells are very tiny, but they are very active; they manufacture various substances; they walk around; they wiggle; and they do all kinds of marvelous things---all on a very small scale. Also, they store information. Consider the possibility that we too can make a thing very small which does what we want---that we can manufacture an object that maneuvers at that level!
There may even be an economic point to this business of making things very small. Let me remind you of some of the problems of computing machines. In computers we have to store an enormous amount of information. The kind of writing that I was mentioning before, in which I had everything down as a distribution of metal, is permanent. Much more interesting to a computer is a way of writing, erasing, and writing something else. (This is usually because we don't want to waste the material on which we have just written. Yet if we could write it in a very small space, it wouldn't make any difference; it could just be thrown away after it was read. It doesn't cost very much for the material).
Miniaturizing the computer
I don't know how to do this on a small scale in a practical way, but I do know that computing machines are very large; they fill rooms. Why can't we make them very small, make them of little wires, little elements---and by little, I mean little. For instance, the wires should be 10 or 100 atoms in diameter, and the circuits should be a few thousand angstroms across. Everybody who has analyzed the logical theory of computers has come to the conclusion that the possibilities of computers are very interesting---if they could be made to be more complicated by several orders of magnitude. If they had millions of times as many elements, they could make judgments. They would have time to calculate what is the best way to make the calculation that they are about to make. They could select the method of analysis which, from their experience, is better than the one that we would give to them. And in many other ways, they would have new qualitative features.
If I look at your face I immediately recognize that I have seen it before. (Actually, my friends will say I have chosen an unfortunate example here for the subject of this illustration. At least I recognize that it is a man and not an apple.) Yet there is no machine which, with that speed, can take a picture of a face and say even that it is a man; and much less that it is the same man that you showed it before---unless it is exactly the same picture. If the face is changed; if I am closer to the face; if I am further from the face; if the light changes---I recognize it anyway. Now, this little computer I carry in my head is easily able to do that. The computers that we build are not able to do that. The number of elements in this bone box of mine are enormously greater than the number of elements in our ``wonderful'' computers. But our mechanical computers are too big; the elements in this box are microscopic. I want to make some that are submicroscopic.
If we wanted to make a computer that had all these marvelous extra qualitative abilities, we would have to make it, perhaps, the size of the Pentagon. This has several disadvantages. First, it requires too much material; there may not be enough germanium in the world for all the transistors which would have to be put into this enormous thing. There is also the problem of heat generation and power consumption; TVA would be needed to run the computer. But an even more practical difficulty is that the computer would be limited to a certain speed. Because of its large size, there is finite time required to get the information from one place to another. The information cannot go any faster than the speed of light---so, ultimately, when our computers get faster and faster and more and more elaborate, we will have to make them smaller and smaller.
But there is plenty of room to make them smaller. There is nothing that I can see in the physical laws that says the computer elements cannot be made enormously smaller than they are now. In fact, there may be certain advantages.
Miniaturization by evaporation
How can we make such a device? What kind of manufacturing processes would we use? One possibility we might consider, since we have talked about writing by putting atoms down in a certain arrangement, would be to evaporate the material, then evaporate the insulator next to it. Then, for the next layer, evaporate another position of a wire, another insulator, and so on. So, you simply evaporate until you have a block of stuff which has the elements--- coils and condensers, transistors and so on---of exceedingly fine dimensions.
But I would like to discuss, just for amusement, that there are other possibilities. Why can't we manufacture these small computers somewhat like we manufacture the big ones? Why can't we drill holes, cut things, solder things, stamp things out, mold different shapes all at an infinitesimal level? What are the limitations as to how small a thing has to be before you can no longer mold it? How many times when you are working on something frustratingly tiny like your wife's wrist watch, have you said to yourself, ``If I could only train an ant to do this!'' What I would like to suggest is the possibility of training an ant to train a mite to do this. What are the possibilities of small but movable machines? They may or may not be useful, but they surely would be fun to make.
Consider any machine---for example, an automobile---and ask about the problems of making an infinitesimal machine like it. Suppose, in the particular design of the automobile, we need a certain precision of the parts; we need an accuracy, let's suppose, of 4/10,000 of an inch. If things are more inaccurate than that in the shape of the cylinder and so on, it isn't going to work very well. If I make the thing too small, I have to worry about the size of the atoms; I can't make a circle of ``balls'' so to speak, if the circle is too small. So, if I make the error, corresponding to 4/10,000 of an inch, correspond to an error of 10 atoms, it turns out that I can reduce the dimensions of an automobile 4,000 times, approximately---so that it is 1 mm. across. Obviously, if you redesign the car so that it would work with a much larger tolerance, which is not at all impossible, then you could make a much smaller device.
It is interesting to consider what the problems are in such small machines. Firstly, with parts stressed to the same degree, the forces go as the area you are reducing, so that things like weight and inertia are of relatively no importance. The strength of material, in other words, is very much greater in proportion. The stresses and expansion of the flywheel from centrifugal force, for example, would be the same proportion only if the rotational speed is increased in the same proportion as we decrease the size. On the other hand, the metals that we use have a grain structure, and this would be very annoying at small scale because the material is not homogeneous. Plastics and glass and things of this amorphous nature are very much more homogeneous, and so we would have to make our machines out of such materials.
There are problems associated with the electrical part of the system---with the copper wires and the magnetic parts. The magnetic properties on a very small scale are not the same as on a large scale; there is the ``domain'' problem involved. A big magnet made of millions of domains can only be made on a small scale with one domain. The electrical equipment won't simply be scaled down; it has to be redesigned. But I can see no reason why it can't be redesigned to work again.
Problems of lubrication
Lubrication involves some interesting points. The effective viscosity of oil would be higher and higher in proportion as we went down (and if we increase the speed as much as we can). If we don't increase the speed so much, and change from oil to kerosene or some other fluid, the problem is not so bad. But actually we may not have to lubricate at all! We have a lot of extra force. Let the bearings run dry; they won't run hot because the heat escapes away from such a small device very, very rapidly.
This rapid heat loss would prevent the gasoline from exploding, so an internal combustion engine is impossible. Other chemical reactions, liberating energy when cold, can be used. Probably an external supply of electrical power would be most convenient for such small machines.
What would be the utility of such machines? Who knows? Of course, a small automobile would only be useful for the mites to drive around in, and I suppose our Christian interests don't go that far. However, we did note the possibility of the manufacture of small elements for computers in completely automatic factories, containing lathes and other machine tools at the very small level. The small lathe would not have to be exactly like our big lathe. I leave to your imagination the improvement of the design to take full advantage of the properties of things on a small scale, and in such a way that the fully automatic aspect would be easiest to manage.
A friend of mine (Albert R. Hibbs) suggests a very interesting possibility for relatively small machines. He says that, although it is a very wild idea, it would be interesting in surgery if you could swallow the surgeon. You put the mechanical surgeon inside the blood vessel and it goes into the heart and ``looks'' around. (Of course the information has to be fed out.) It finds out which valve is the faulty one and takes a little knife and slices it out. Other small machines might be permanently incorporated in the body to assist some inadequately-functioning organ.
Now comes the interesting question: How do we make such a tiny mechanism? I leave that to you. However, let me suggest one weird possibility. You know, in the atomic energy plants they have materials and machines that they can't handle directly because they have become radioactive. To unscrew nuts and put on bolts and so on, they have a set of master and slave hands, so that by operating a set of levers here, you control the ``hands'' there, and can turn them this way and that so you can handle things quite nicely.
Most of these devices are actually made rather simply, in that there is a particular cable, like a marionette string, that goes directly from the controls to the ``hands.'' But, of course, things also have been made using servo motors, so that the connection between the one thing and the other is electrical rather than mechanical. When you turn the levers, they turn a servo motor, and it changes the electrical currents in the wires, which repositions a motor at the other end.
Now, I want to build much the same device---a master-slave system which operates electrically. But I want the slaves to be made especially carefully by modern large-scale machinists so that they are one-fourth the scale of the ``hands'' that you ordinarily maneuver. So you have a scheme by which you can do things at one- quarter scale anyway---the little servo motors with little hands play with little nuts and bolts; they drill little holes; they are four times smaller. Aha! So I manufacture a quarter-size lathe; I manufacture quarter-size tools; and I make, at the one-quarter scale, still another set of hands again relatively one-quarter size! This is one-sixteenth size, from my point of view. And after I finish doing this I wire directly from my large-scale system, through transformers perhaps, to the one-sixteenth-size servo motors. Thus I can now manipulate the one-sixteenth size hands.
Well, you get the principle from there on. It is rather a difficult program, but it is a possibility. You might say that one can go much farther in one step than from one to four. Of course, this has all to be designed very carefully and it is not necessary simply to make it like hands. If you thought of it very carefully, you could probably arrive at a much better system for doing such things.
If you work through a pantograph, even today, you can get much more than a factor of four in even one step. But you can't work directly through a pantograph which makes a smaller pantograph which then makes a smaller pantograph---because of the looseness of the holes and the irregularities of construction. The end of the pantograph wiggles with a relatively greater irregularity than the irregularity with which you move your hands. In going down this scale, I would find the end of the pantograph on the end of the pantograph on the end of the pantograph shaking so badly that it wasn't doing anything sensible at all.
At each stage, it is necessary to improve the precision of the apparatus. If, for instance, having made a small lathe with a pantograph, we find its lead screw irregular---more irregular than the large-scale one---we could lap the lead screw against breakable nuts that you can reverse in the usual way back and forth until this lead screw is, at its scale, as accurate as our original lead screws, at our scale.
We can make flats by rubbing unflat surfaces in triplicates together---in three pairs---and the flats then become flatter than the thing you started with. Thus, it is not impossible to improve precision on a small scale by the correct operations. So, when we build this stuff, it is necessary at each step to improve the accuracy of the equipment by working for awhile down there, making accurate lead screws, Johansen blocks, and all the other materials which we use in accurate machine work at the higher level. We have to stop at each level and manufacture all the stuff to go to the next level---a very long and very difficult program. Perhaps you can figure a better way than that to get down to small scale more rapidly.
Yet, after all this, you have just got one little baby lathe four thousand times smaller than usual. But we were thinking of making an enormous computer, which we were going to build by drilling holes on this lathe to make little washers for the computer. How many washers can you manufacture on this one lathe?
A hundred tiny hands
When I make my first set of slave ``hands'' at one-fourth scale, I am going to make ten sets. I make ten sets of ``hands,'' and I wire them to my original levers so they each do exactly the same thing at the same time in parallel. Now, when I am making my new devices one-quarter again as small, I let each one manufacture ten copies, so that I would have a hundred ``hands'' at the 1/16th size.
Where am I going to put the million lathes that I am going to have? Why, there is nothing to it; the volume is much less than that of even one full-scale lathe. For instance, if I made a billion little lathes, each 1/4000 of the scale of a regular lathe, there are plenty of materials and space available because in the billion little ones there is less than 2 percent of the materials in one big lathe.
It doesn't cost anything for materials, you see. So I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously, drilling holes, stamping parts, and so on.
As we go down in size, there are a number of interesting problems that arise. All things do not simply scale down in proportion. There is the problem that materials stick together by the molecular (Van der Waals) attractions. It would be like this: After you have made a part and you unscrew the nut from a bolt, it isn't going to fall down because the gravity isn't appreciable; it would even be hard to get it off the bolt. It would be like those old movies of a man with his hands full of molasses, trying to get rid of a glass of water. There will be several problems of this nature that we will have to be ready to design for.
Rearranging the atoms
But I am not afraid to consider the final question as to whether, ultimately---in the great future---we can arrange the atoms the way we want; the very atoms, all the way down! What would happen if we could arrange the atoms one by one the way we want them (within reason, of course; you can't put them so that they are chemically unstable, for example).
Up to now, we have been content to dig in the ground to find minerals. We heat them and we do things on a large scale with them, and we hope to get a pure substance with just so much impurity, and so on. But we must always accept some atomic arrangement that nature gives us. We haven't got anything, say, with a ``checkerboard'' arrangement, with the impurity atoms exactly arranged 1,000 angstroms apart, or in some other particular pattern.
What could we do with layered structures with just the right layers? What would the properties of materials be if we could really arrange the atoms the way we want them? They would be very interesting to investigate theoretically. I can't see exactly what would happen, but I can hardly doubt that when we have some control of the arrangement of things on a small scale we will get an enormously greater range of possible properties that substances can have, and of different things that we can do.
Consider, for example, a piece of material in which we make little coils and condensers (or their solid state analogs) 1,000 or 10,000 angstroms in a circuit, one right next to the other, over a large area, with little antennas sticking out at the other end---a whole series of circuits. Is it possible, for example, to emit light from a whole set of antennas, like we emit radio waves from an organized set of antennas to beam the radio programs to Europe? The same thing would be to beam the light out in a definite direction with very high intensity. (Perhaps such a beam is not very useful technically or economically.)
I have thought about some of the problems of building electric circuits on a small scale, and the problem of resistance is serious. If you build a corresponding circuit on a small scale, its natural frequency goes up, since the wave length goes down as the scale; but the skin depth only decreases with the square root of the scale ratio, and so resistive problems are of increasing difficulty. Possibly we can beat resistance through the use of superconductivity if the frequency is not too high, or by other tricks.
Atoms in a small world
When we get to the very, very small world---say circuits of seven atoms---we have a lot of new things that would happen that represent completely new opportunities for design. Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum mechanics. So, as we go down and fiddle around with the atoms down there, we are working with different laws, and we can expect to do different things. We can manufacture in different ways. We can use, not just circuits, but some system involving the quantized energy levels, or the interactions of quantized spins, etc.
Another thing we will notice is that, if we go down far enough, all of our devices can be mass produced so that they are absolutely perfect copies of one another. We cannot build two large machines so that the dimensions are exactly the same. But if your machine is only 100 atoms high, you only have to get it correct to one-half of one percent to make sure the other machine is exactly the same size---namely, 100 atoms high!
At the atomic level, we have new kinds of forces and new kinds of possibilities, new kinds of effects. The problems of manufacture and reproduction of materials will be quite different. I am, as I said, inspired by the biological phenomena in which chemical forces are used in repetitious fashion to produce all kinds of weird effects (one of which is the author).
The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big.
Ultimately, we can do chemical synthesis. A chemist comes to us and says, ``Look, I want a molecule that has the atoms arranged thus and so; make me that molecule.'' The chemist does a mysterious thing when he wants to make a molecule. He sees that it has got that ring, so he mixes this and that, and he shakes it, and he fiddles around. And, at the end of a difficult process, he usually does succeed in synthesizing what he wants. By the time I get my devices working, so that we can do it by physics, he will have figured out how to synthesize absolutely anything, so that this will really be useless.
But it is interesting that it would be, in principle, possible (I think) for a physicist to synthesize any chemical substance that the chemist writes down. Give the orders and the physicist synthesizes it. How? Put the atoms down where the chemist says, and so you make the substance. The problems of chemistry and biology can be greatly helped if our ability to see what we are doing, and to do things on an atomic level, is ultimately developed---a development which I think cannot be avoided.
Now, you might say, ``Who should do this and why should they do it?'' Well, I pointed out a few of the economic applications, but I know that the reason that you would do it might be just for fun. But have some fun! Let's have a competition between laboratories. Let one laboratory make a tiny motor which it sends to another lab which sends it back with a thing that fits inside the shaft of the first motor.
High school competition
Just for the fun of it, and in order to get kids interested in this field, I would propose that someone who has some contact with the high schools think of making some kind of high school competition. After all, we haven't even started in this field, and even the kids can write smaller than has ever been written before. They could have competition in high schools. The Los Angeles high school could send a pin to the Venice high school on which it says, ``How's this?'' They get the pin back, and in the dot of the ``i'' it says, ``Not so hot.''
Perhaps this doesn't excite you to do it, and only economics will do so. Then I want to do something; but I can't do it at the present moment, because I haven't prepared the ground. It is my intention to offer a prize of $1,000 to the first guy who can take the information on the page of a book and put it on an area 1/25,000 smaller in linear scale in such manner that it can be read by an electron microscope.
And I want to offer another prize---if I can figure out how to phrase it so that I don't get into a mess of arguments about definitions---of another $1,000 to the first guy who makes an operating electric motor---a rotating electric motor which can be controlled from the outside and, not counting the lead-in wires, is only 1/64 inch cube.
I do not expect that such prizes will have to wait very long for claimants.
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There's Plenty of Room at the Bottom
An Invitation to Enter a New Field of Physics
ref: http://elearning.stut.edu.tw/m_facture/Nanotech/Web/ch11.htm
by Richard P. Feynman
This transcript of the classic talk that Richard Feynman gave on December 29th 1959 at the annual meeting of the American Physical Society at the California Institute of Technology (Caltech) was first published in the February 1960 issue of Caltech's Engineering and Science, which owns the copyright. It has been made available on the web at http://www.zyvex.com/nanotech/feynman.html with their kind permission.
Information on the Feynman Prizes
Links to pages on Feynman
For an account of the talk and how people reacted to it, see chapter 4 of Nano! by Ed Regis, Little/Brown 1995. An excellent technical introduction to nanotechnology is Nanosystems: molecular machinery, manufacturing, and computation by K. Eric Drexler, Wiley 1992.
I imagine experimental physicists must often look with envy at men like Kamerlingh Onnes, who discovered a field like low temperature, which seems to be bottomless and in which one can go down and down. Such a man is then a leader and has some temporary monopoly in a scientific adventure. Percy Bridgman, in designing a way to obtain higher pressures, opened up another new field and was able to move into it and to lead us all along. The development of ever higher vacuum was a continuing development of the same kind.
I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, ``What are the strange particles?'') but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications.
What I want to talk about is the problem of manipulating and controlling things on a small scale.
As soon as I mention this, people tell me about miniaturization, and how far it has progressed today. They tell me about electric motors that are the size of the nail on your small finger. And there is a device on the market, they tell me, by which you can write the Lord's Prayer on the head of a pin. But that's nothing; that's the most primitive, halting step in the direction I intend to discuss. It is a staggeringly small world that is below. In the year 2000, when they look back at this age, they will wonder why it was not until the year 1960 that anybody began seriously to move in this direction.
Why cannot we write the entire 24 volumes of the Encyclopedia Brittanica on the head of a pin?
Let's see what would be involved. The head of a pin is a sixteenth of an inch across. If you magnify it by 25,000 diameters, the area of the head of the pin is then equal to the area of all the pages of the Encyclopaedia Brittanica. Therefore, all it is necessary to do is to reduce in size all the writing in the Encyclopaedia by 25,000 times. Is that possible? The resolving power of the eye is about 1/120 of an inch---that is roughly the diameter of one of the little dots on the fine half-tone reproductions in the Encyclopaedia. This, when you demagnify it by 25,000 times, is still 80 angstroms in diameter---32 atoms across, in an ordinary metal. In other words, one of those dots still would contain in its area 1,000 atoms. So, each dot can easily be adjusted in size as required by the photoengraving, and there is no question that there is enough room on the head of a pin to put all of the Encyclopaedia Brittanica.
Furthermore, it can be read if it is so written. Let's imagine that it is written in raised letters of metal; that is, where the black is in the Encyclopedia, we have raised letters of metal that are actually 1/25,000 of their ordinary size. How would we read it?
If we had something written in such a way, we could read it using techniques in common use today. (They will undoubtedly find a better way when we do actually have it written, but to make my point conservatively I shall just take techniques we know today.) We would press the metal into a plastic material and make a mold of it, then peel the plastic off very carefully, evaporate silica into the plastic to get a very thin film, then shadow it by evaporating gold at an angle against the silica so that all the little letters will appear clearly, dissolve the plastic away from the silica film, and then look through it with an electron microscope!
There is no question that if the thing were reduced by 25,000 times in the form of raised letters on the pin, it would be easy for us to read it today. Furthermore; there is no question that we would find it easy to make copies of the master; we would just need to press the same metal plate again into plastic and we would have another copy.
How do we write small?
The next question is: How do we write it? We have no standard technique to do this now. But let me argue that it is not as difficult as it first appears to be. We can reverse the lenses of the electron microscope in order to demagnify as well as magnify. A source of ions, sent through the microscope lenses in reverse, could be focused to a very small spot. We could write with that spot like we write in a TV cathode ray oscilloscope, by going across in lines, and having an adjustment which determines the amount of material which is going to be deposited as we scan in lines.
This method might be very slow because of space charge limitations. There will be more rapid methods. We could first make, perhaps by some photo process, a screen which has holes in it in the form of the letters. Then we would strike an arc behind the holes and draw metallic ions through the holes; then we could again use our system of lenses and make a small image in the form of ions, which would deposit the metal on the pin.
A simpler way might be this (though I am not sure it would work): We take light and, through an optical microscope running backwards, we focus it onto a very small photoelectric screen. Then electrons come away from the screen where the light is shining. These electrons are focused down in size by the electron microscope lenses to impinge directly upon the surface of the metal. Will such a beam etch away the metal if it is run long enough? I don't know. If it doesn't work for a metal surface, it must be possible to find some surface with which to coat the original pin so that, where the electrons bombard, a change is made which we could recognize later.
There is no intensity problem in these devices---not what you are used to in magnification, where you have to take a few electrons and spread them over a bigger and bigger screen; it is just the opposite. The light which we get from a page is concentrated onto a very small area so it is very intense. The few electrons which come from the photoelectric screen are demagnified down to a very tiny area so that, again, they are very intense. I don't know why this hasn't been done yet!
That's the Encyclopaedia Brittanica on the head of a pin, but let's consider all the books in the world. The Library of Congress has approximately 9 million volumes; the British Museum Library has 5 million volumes; there are also 5 million volumes in the National Library in France. Undoubtedly there are duplications, so let us say that there are some 24 million volumes of interest in the world.
What would happen if I print all this down at the scale we have been discussing? How much space would it take? It would take, of course, the area of about a million pinheads because, instead of there being just the 24 volumes of the Encyclopaedia, there are 24 million volumes. The million pinheads can be put in a square of a thousand pins on a side, or an area of about 3 square yards. That is to say, the silica replica with the paper-thin backing of plastic, with which we have made the copies, with all this information, is on an area of approximately the size of 35 pages of the Encyclopaedia. That is about half as many pages as there are in this magazine. All of the information which all of mankind has every recorded in books can be carried around in a pamphlet in your hand---and not written in code, but a simple reproduction of the original pictures, engravings, and everything else on a small scale without loss of resolution.
What would our librarian at Caltech say, as she runs all over from one building to another, if I tell her that, ten years from now, all of the information that she is struggling to keep track of--- 120,000 volumes, stacked from the floor to the ceiling, drawers full of cards, storage rooms full of the older books---can be kept on just one library card! When the University of Brazil, for example, finds that their library is burned, we can send them a copy of every book in our library by striking off a copy from the master plate in a few hours and mailing it in an envelope no bigger or heavier than any other ordinary air mail letter.
Now, the name of this talk is ``There is Plenty of Room at the Bottom''---not just ``There is Room at the Bottom.'' What I have demonstrated is that there is room---that you can decrease the size of things in a practical way. I now want to show that there is plenty of room. I will not now discuss how we are going to do it, but only what is possible in principle---in other words, what is possible according to the laws of physics. I am not inventing anti-gravity, which is possible someday only if the laws are not what we think. I am telling you what could be done if the laws are what we think; we are not doing it simply because we haven't yet gotten around to it.
Information on a small scale
Suppose that, instead of trying to reproduce the pictures and all the information directly in its present form, we write only the information content in a code of dots and dashes, or something like that, to represent the various letters. Each letter represents six or seven ``bits'' of information; that is, you need only about six or seven dots or dashes for each letter. Now, instead of writing everything, as I did before, on the surface of the head of a pin, I am going to use the interior of the material as well.
Let us represent a dot by a small spot of one metal, the next dash, by an adjacent spot of another metal, and so on. Suppose, to be conservative, that a bit of information is going to require a little cube of atoms 5 times 5 times 5---that is 125 atoms. Perhaps we need a hundred and some odd atoms to make sure that the information is not lost through diffusion, or through some other process.
I have estimated how many letters there are in the Encyclopaedia, and I have assumed that each of my 24 million books is as big as an Encyclopaedia volume, and have calculated, then, how many bits of information there are (10^15). For each bit I allow 100 atoms. And it turns out that all of the information that man has carefully accumulated in all the books in the world can be written in this form in a cube of material one two-hundredth of an inch wide--- which is the barest piece of dust that can be made out by the human eye. So there is plenty of room at the bottom! Don't tell me about microfilm!
This fact---that enormous amounts of information can be carried in an exceedingly small space---is, of course, well known to the biologists, and resolves the mystery which existed before we understood all this clearly, of how it could be that, in the tiniest cell, all of the information for the organization of a complex creature such as ourselves can be stored. All this information---whether we have brown eyes, or whether we think at all, or that in the embryo the jawbone should first develop with a little hole in the side so that later a nerve can grow through it---all this information is contained in a very tiny fraction of the cell in the form of long-chain DNA molecules in which approximately 50 atoms are used for one bit of information about the cell.
Better electron microscopes
If I have written in a code, with 5 times 5 times 5 atoms to a bit, the question is: How could I read it today? The electron microscope is not quite good enough, with the greatest care and effort, it can only resolve about 10 angstroms. I would like to try and impress upon you while I am talking about all of these things on a small scale, the importance of improving the electron microscope by a hundred times. It is not impossible; it is not against the laws of diffraction of the electron. The wave length of the electron in such a microscope is only 1/20 of an angstrom. So it should be possible to see the individual atoms. What good would it be to see individual atoms distinctly?
We have friends in other fields---in biology, for instance. We physicists often look at them and say, ``You know the reason you fellows are making so little progress?'' (Actually I don't know any field where they are making more rapid progress than they are in biology today.) ``You should use more mathematics, like we do.'' They could answer us---but they're polite, so I'll answer for them: ``What you should do in order for us to make more rapid progress is to make the electron microscope 100 times better.''
What are the most central and fundamental problems of biology today? They are questions like: What is the sequence of bases in the DNA? What happens when you have a mutation? How is the base order in the DNA connected to the order of amino acids in the protein? What is the structure of the RNA; is it single-chain or double-chain, and how is it related in its order of bases to the DNA? What is the organization of the microsomes? How are proteins synthesized? Where does the RNA go? How does it sit? Where do the proteins sit? Where do the amino acids go in? In photosynthesis, where is the chlorophyll; how is it arranged; where are the carotenoids involved in this thing? What is the system of the conversion of light into chemical energy?
It is very easy to answer many of these fundamental biological questions; you just look at the thing! You will see the order of bases in the chain; you will see the structure of the microsome. Unfortunately, the present microscope sees at a scale which is just a bit too crude. Make the microscope one hundred times more powerful, and many problems of biology would be made very much easier. I exaggerate, of course, but the biologists would surely be very thankful to you---and they would prefer that to the criticism that they should use more mathematics.
The theory of chemical processes today is based on theoretical physics. In this sense, physics supplies the foundation of chemistry. But chemistry also has analysis. If you have a strange substance and you want to know what it is, you go through a long and complicated process of chemical analysis. You can analyze almost anything today, so I am a little late with my idea. But if the physicists wanted to, they could also dig under the chemists in the problem of chemical analysis. It would be very easy to make an analysis of any complicated chemical substance; all one would have to do would be to look at it and see where the atoms are. The only trouble is that the electron microscope is one hundred times too poor. (Later, I would like to ask the question: Can the physicists do something about the third problem of chemistry---namely, synthesis? Is there a physical way to synthesize any chemical substance?
The reason the electron microscope is so poor is that the f- value of the lenses is only 1 part to 1,000; you don't have a big enough numerical aperture. And I know that there are theorems which prove that it is impossible, with axially symmetrical stationary field lenses, to produce an f-value any bigger than so and so; and therefore the resolving power at the present time is at its theoretical maximum. But in every theorem there are assumptions. Why must the field be symmetrical? I put this out as a challenge: Is there no way to make the electron microscope more powerful?
The marvelous biological system
The biological example of writing information on a small scale has inspired me to think of something that should be possible. Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly small. Many of the cells are very tiny, but they are very active; they manufacture various substances; they walk around; they wiggle; and they do all kinds of marvelous things---all on a very small scale. Also, they store information. Consider the possibility that we too can make a thing very small which does what we want---that we can manufacture an object that maneuvers at that level!
There may even be an economic point to this business of making things very small. Let me remind you of some of the problems of computing machines. In computers we have to store an enormous amount of information. The kind of writing that I was mentioning before, in which I had everything down as a distribution of metal, is permanent. Much more interesting to a computer is a way of writing, erasing, and writing something else. (This is usually because we don't want to waste the material on which we have just written. Yet if we could write it in a very small space, it wouldn't make any difference; it could just be thrown away after it was read. It doesn't cost very much for the material).
Miniaturizing the computer
I don't know how to do this on a small scale in a practical way, but I do know that computing machines are very large; they fill rooms. Why can't we make them very small, make them of little wires, little elements---and by little, I mean little. For instance, the wires should be 10 or 100 atoms in diameter, and the circuits should be a few thousand angstroms across. Everybody who has analyzed the logical theory of computers has come to the conclusion that the possibilities of computers are very interesting---if they could be made to be more complicated by several orders of magnitude. If they had millions of times as many elements, they could make judgments. They would have time to calculate what is the best way to make the calculation that they are about to make. They could select the method of analysis which, from their experience, is better than the one that we would give to them. And in many other ways, they would have new qualitative features.
If I look at your face I immediately recognize that I have seen it before. (Actually, my friends will say I have chosen an unfortunate example here for the subject of this illustration. At least I recognize that it is a man and not an apple.) Yet there is no machine which, with that speed, can take a picture of a face and say even that it is a man; and much less that it is the same man that you showed it before---unless it is exactly the same picture. If the face is changed; if I am closer to the face; if I am further from the face; if the light changes---I recognize it anyway. Now, this little computer I carry in my head is easily able to do that. The computers that we build are not able to do that. The number of elements in this bone box of mine are enormously greater than the number of elements in our ``wonderful'' computers. But our mechanical computers are too big; the elements in this box are microscopic. I want to make some that are submicroscopic.
If we wanted to make a computer that had all these marvelous extra qualitative abilities, we would have to make it, perhaps, the size of the Pentagon. This has several disadvantages. First, it requires too much material; there may not be enough germanium in the world for all the transistors which would have to be put into this enormous thing. There is also the problem of heat generation and power consumption; TVA would be needed to run the computer. But an even more practical difficulty is that the computer would be limited to a certain speed. Because of its large size, there is finite time required to get the information from one place to another. The information cannot go any faster than the speed of light---so, ultimately, when our computers get faster and faster and more and more elaborate, we will have to make them smaller and smaller.
But there is plenty of room to make them smaller. There is nothing that I can see in the physical laws that says the computer elements cannot be made enormously smaller than they are now. In fact, there may be certain advantages.
Miniaturization by evaporation
How can we make such a device? What kind of manufacturing processes would we use? One possibility we might consider, since we have talked about writing by putting atoms down in a certain arrangement, would be to evaporate the material, then evaporate the insulator next to it. Then, for the next layer, evaporate another position of a wire, another insulator, and so on. So, you simply evaporate until you have a block of stuff which has the elements--- coils and condensers, transistors and so on---of exceedingly fine dimensions.
But I would like to discuss, just for amusement, that there are other possibilities. Why can't we manufacture these small computers somewhat like we manufacture the big ones? Why can't we drill holes, cut things, solder things, stamp things out, mold different shapes all at an infinitesimal level? What are the limitations as to how small a thing has to be before you can no longer mold it? How many times when you are working on something frustratingly tiny like your wife's wrist watch, have you said to yourself, ``If I could only train an ant to do this!'' What I would like to suggest is the possibility of training an ant to train a mite to do this. What are the possibilities of small but movable machines? They may or may not be useful, but they surely would be fun to make.
Consider any machine---for example, an automobile---and ask about the problems of making an infinitesimal machine like it. Suppose, in the particular design of the automobile, we need a certain precision of the parts; we need an accuracy, let's suppose, of 4/10,000 of an inch. If things are more inaccurate than that in the shape of the cylinder and so on, it isn't going to work very well. If I make the thing too small, I have to worry about the size of the atoms; I can't make a circle of ``balls'' so to speak, if the circle is too small. So, if I make the error, corresponding to 4/10,000 of an inch, correspond to an error of 10 atoms, it turns out that I can reduce the dimensions of an automobile 4,000 times, approximately---so that it is 1 mm. across. Obviously, if you redesign the car so that it would work with a much larger tolerance, which is not at all impossible, then you could make a much smaller device.
It is interesting to consider what the problems are in such small machines. Firstly, with parts stressed to the same degree, the forces go as the area you are reducing, so that things like weight and inertia are of relatively no importance. The strength of material, in other words, is very much greater in proportion. The stresses and expansion of the flywheel from centrifugal force, for example, would be the same proportion only if the rotational speed is increased in the same proportion as we decrease the size. On the other hand, the metals that we use have a grain structure, and this would be very annoying at small scale because the material is not homogeneous. Plastics and glass and things of this amorphous nature are very much more homogeneous, and so we would have to make our machines out of such materials.
There are problems associated with the electrical part of the system---with the copper wires and the magnetic parts. The magnetic properties on a very small scale are not the same as on a large scale; there is the ``domain'' problem involved. A big magnet made of millions of domains can only be made on a small scale with one domain. The electrical equipment won't simply be scaled down; it has to be redesigned. But I can see no reason why it can't be redesigned to work again.
Problems of lubrication
Lubrication involves some interesting points. The effective viscosity of oil would be higher and higher in proportion as we went down (and if we increase the speed as much as we can). If we don't increase the speed so much, and change from oil to kerosene or some other fluid, the problem is not so bad. But actually we may not have to lubricate at all! We have a lot of extra force. Let the bearings run dry; they won't run hot because the heat escapes away from such a small device very, very rapidly.
This rapid heat loss would prevent the gasoline from exploding, so an internal combustion engine is impossible. Other chemical reactions, liberating energy when cold, can be used. Probably an external supply of electrical power would be most convenient for such small machines.
What would be the utility of such machines? Who knows? Of course, a small automobile would only be useful for the mites to drive around in, and I suppose our Christian interests don't go that far. However, we did note the possibility of the manufacture of small elements for computers in completely automatic factories, containing lathes and other machine tools at the very small level. The small lathe would not have to be exactly like our big lathe. I leave to your imagination the improvement of the design to take full advantage of the properties of things on a small scale, and in such a way that the fully automatic aspect would be easiest to manage.
A friend of mine (Albert R. Hibbs) suggests a very interesting possibility for relatively small machines. He says that, although it is a very wild idea, it would be interesting in surgery if you could swallow the surgeon. You put the mechanical surgeon inside the blood vessel and it goes into the heart and ``looks'' around. (Of course the information has to be fed out.) It finds out which valve is the faulty one and takes a little knife and slices it out. Other small machines might be permanently incorporated in the body to assist some inadequately-functioning organ.
Now comes the interesting question: How do we make such a tiny mechanism? I leave that to you. However, let me suggest one weird possibility. You know, in the atomic energy plants they have materials and machines that they can't handle directly because they have become radioactive. To unscrew nuts and put on bolts and so on, they have a set of master and slave hands, so that by operating a set of levers here, you control the ``hands'' there, and can turn them this way and that so you can handle things quite nicely.
Most of these devices are actually made rather simply, in that there is a particular cable, like a marionette string, that goes directly from the controls to the ``hands.'' But, of course, things also have been made using servo motors, so that the connection between the one thing and the other is electrical rather than mechanical. When you turn the levers, they turn a servo motor, and it changes the electrical currents in the wires, which repositions a motor at the other end.
Now, I want to build much the same device---a master-slave system which operates electrically. But I want the slaves to be made especially carefully by modern large-scale machinists so that they are one-fourth the scale of the ``hands'' that you ordinarily maneuver. So you have a scheme by which you can do things at one- quarter scale anyway---the little servo motors with little hands play with little nuts and bolts; they drill little holes; they are four times smaller. Aha! So I manufacture a quarter-size lathe; I manufacture quarter-size tools; and I make, at the one-quarter scale, still another set of hands again relatively one-quarter size! This is one-sixteenth size, from my point of view. And after I finish doing this I wire directly from my large-scale system, through transformers perhaps, to the one-sixteenth-size servo motors. Thus I can now manipulate the one-sixteenth size hands.
Well, you get the principle from there on. It is rather a difficult program, but it is a possibility. You might say that one can go much farther in one step than from one to four. Of course, this has all to be designed very carefully and it is not necessary simply to make it like hands. If you thought of it very carefully, you could probably arrive at a much better system for doing such things.
If you work through a pantograph, even today, you can get much more than a factor of four in even one step. But you can't work directly through a pantograph which makes a smaller pantograph which then makes a smaller pantograph---because of the looseness of the holes and the irregularities of construction. The end of the pantograph wiggles with a relatively greater irregularity than the irregularity with which you move your hands. In going down this scale, I would find the end of the pantograph on the end of the pantograph on the end of the pantograph shaking so badly that it wasn't doing anything sensible at all.
At each stage, it is necessary to improve the precision of the apparatus. If, for instance, having made a small lathe with a pantograph, we find its lead screw irregular---more irregular than the large-scale one---we could lap the lead screw against breakable nuts that you can reverse in the usual way back and forth until this lead screw is, at its scale, as accurate as our original lead screws, at our scale.
We can make flats by rubbing unflat surfaces in triplicates together---in three pairs---and the flats then become flatter than the thing you started with. Thus, it is not impossible to improve precision on a small scale by the correct operations. So, when we build this stuff, it is necessary at each step to improve the accuracy of the equipment by working for awhile down there, making accurate lead screws, Johansen blocks, and all the other materials which we use in accurate machine work at the higher level. We have to stop at each level and manufacture all the stuff to go to the next level---a very long and very difficult program. Perhaps you can figure a better way than that to get down to small scale more rapidly.
Yet, after all this, you have just got one little baby lathe four thousand times smaller than usual. But we were thinking of making an enormous computer, which we were going to build by drilling holes on this lathe to make little washers for the computer. How many washers can you manufacture on this one lathe?
A hundred tiny hands
When I make my first set of slave ``hands'' at one-fourth scale, I am going to make ten sets. I make ten sets of ``hands,'' and I wire them to my original levers so they each do exactly the same thing at the same time in parallel. Now, when I am making my new devices one-quarter again as small, I let each one manufacture ten copies, so that I would have a hundred ``hands'' at the 1/16th size.
Where am I going to put the million lathes that I am going to have? Why, there is nothing to it; the volume is much less than that of even one full-scale lathe. For instance, if I made a billion little lathes, each 1/4000 of the scale of a regular lathe, there are plenty of materials and space available because in the billion little ones there is less than 2 percent of the materials in one big lathe.
It doesn't cost anything for materials, you see. So I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously, drilling holes, stamping parts, and so on.
As we go down in size, there are a number of interesting problems that arise. All things do not simply scale down in proportion. There is the problem that materials stick together by the molecular (Van der Waals) attractions. It would be like this: After you have made a part and you unscrew the nut from a bolt, it isn't going to fall down because the gravity isn't appreciable; it would even be hard to get it off the bolt. It would be like those old movies of a man with his hands full of molasses, trying to get rid of a glass of water. There will be several problems of this nature that we will have to be ready to design for.
Rearranging the atoms
But I am not afraid to consider the final question as to whether, ultimately---in the great future---we can arrange the atoms the way we want; the very atoms, all the way down! What would happen if we could arrange the atoms one by one the way we want them (within reason, of course; you can't put them so that they are chemically unstable, for example).
Up to now, we have been content to dig in the ground to find minerals. We heat them and we do things on a large scale with them, and we hope to get a pure substance with just so much impurity, and so on. But we must always accept some atomic arrangement that nature gives us. We haven't got anything, say, with a ``checkerboard'' arrangement, with the impurity atoms exactly arranged 1,000 angstroms apart, or in some other particular pattern.
What could we do with layered structures with just the right layers? What would the properties of materials be if we could really arrange the atoms the way we want them? They would be very interesting to investigate theoretically. I can't see exactly what would happen, but I can hardly doubt that when we have some control of the arrangement of things on a small scale we will get an enormously greater range of possible properties that substances can have, and of different things that we can do.
Consider, for example, a piece of material in which we make little coils and condensers (or their solid state analogs) 1,000 or 10,000 angstroms in a circuit, one right next to the other, over a large area, with little antennas sticking out at the other end---a whole series of circuits. Is it possible, for example, to emit light from a whole set of antennas, like we emit radio waves from an organized set of antennas to beam the radio programs to Europe? The same thing would be to beam the light out in a definite direction with very high intensity. (Perhaps such a beam is not very useful technically or economically.)
I have thought about some of the problems of building electric circuits on a small scale, and the problem of resistance is serious. If you build a corresponding circuit on a small scale, its natural frequency goes up, since the wave length goes down as the scale; but the skin depth only decreases with the square root of the scale ratio, and so resistive problems are of increasing difficulty. Possibly we can beat resistance through the use of superconductivity if the frequency is not too high, or by other tricks.
Atoms in a small world
When we get to the very, very small world---say circuits of seven atoms---we have a lot of new things that would happen that represent completely new opportunities for design. Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum mechanics. So, as we go down and fiddle around with the atoms down there, we are working with different laws, and we can expect to do different things. We can manufacture in different ways. We can use, not just circuits, but some system involving the quantized energy levels, or the interactions of quantized spins, etc.
Another thing we will notice is that, if we go down far enough, all of our devices can be mass produced so that they are absolutely perfect copies of one another. We cannot build two large machines so that the dimensions are exactly the same. But if your machine is only 100 atoms high, you only have to get it correct to one-half of one percent to make sure the other machine is exactly the same size---namely, 100 atoms high!
At the atomic level, we have new kinds of forces and new kinds of possibilities, new kinds of effects. The problems of manufacture and reproduction of materials will be quite different. I am, as I said, inspired by the biological phenomena in which chemical forces are used in repetitious fashion to produce all kinds of weird effects (one of which is the author).
The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big.
Ultimately, we can do chemical synthesis. A chemist comes to us and says, ``Look, I want a molecule that has the atoms arranged thus and so; make me that molecule.'' The chemist does a mysterious thing when he wants to make a molecule. He sees that it has got that ring, so he mixes this and that, and he shakes it, and he fiddles around. And, at the end of a difficult process, he usually does succeed in synthesizing what he wants. By the time I get my devices working, so that we can do it by physics, he will have figured out how to synthesize absolutely anything, so that this will really be useless.
But it is interesting that it would be, in principle, possible (I think) for a physicist to synthesize any chemical substance that the chemist writes down. Give the orders and the physicist synthesizes it. How? Put the atoms down where the chemist says, and so you make the substance. The problems of chemistry and biology can be greatly helped if our ability to see what we are doing, and to do things on an atomic level, is ultimately developed---a development which I think cannot be avoided.
Now, you might say, ``Who should do this and why should they do it?'' Well, I pointed out a few of the economic applications, but I know that the reason that you would do it might be just for fun. But have some fun! Let's have a competition between laboratories. Let one laboratory make a tiny motor which it sends to another lab which sends it back with a thing that fits inside the shaft of the first motor.
High school competition
Just for the fun of it, and in order to get kids interested in this field, I would propose that someone who has some contact with the high schools think of making some kind of high school competition. After all, we haven't even started in this field, and even the kids can write smaller than has ever been written before. They could have competition in high schools. The Los Angeles high school could send a pin to the Venice high school on which it says, ``How's this?'' They get the pin back, and in the dot of the ``i'' it says, ``Not so hot.''
Perhaps this doesn't excite you to do it, and only economics will do so. Then I want to do something; but I can't do it at the present moment, because I haven't prepared the ground. It is my intention to offer a prize of $1,000 to the first guy who can take the information on the page of a book and put it on an area 1/25,000 smaller in linear scale in such manner that it can be read by an electron microscope.
And I want to offer another prize---if I can figure out how to phrase it so that I don't get into a mess of arguments about definitions---of another $1,000 to the first guy who makes an operating electric motor---a rotating electric motor which can be controlled from the outside and, not counting the lead-in wires, is only 1/64 inch cube.
I do not expect that such prizes will have to wait very long for claimants.
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【彭子豪】
記得有一句知名手機廠的廣告詞－「科技始終來自人性」，但科技日新月異，常發現真的要人性化，還頗困難。尤其科技製品都來自少數人的實驗室中，這也是為何「科技新品」在追求市場量能時，常常反而無法將產品應用普及進而大賣。但如是以幸福傳達出全新科技觀，似乎值得人類期待，全新通訊應用WiMAX就是有這種能耐及魅力。
為何WiMAX可和幸福畫上等號，主因在此全新的無線通訊技術，可針對國內無線通訊技術如2G、3G及WiFi等，提供全面性的提升，將目前各項行動應用擴散到全台灣的每一個角落，打破過去通訊應用只能在都會區或是高人口密集度區域中發揮外，還可將現有應用達到高速應用化。簡單來說，WiMAX可將資訊流通及應用達到扁平化、全民化，相關應用不再只是由電信等相關業者提出需求及應用，而是全民當家，提出自己的需求，創造無線通訊應用的新幸福指標。
無線高速傳輸 克服山區網路建設難題
以台南縣後壁鄉為例，這一個名風淳樸的山地鄉鎮，但對於當地下一代的台灣主人翁，要和都市區域的小孩一樣，能利用網路來看世界似乎相當困難，更別說鄉內學校利用網路進行遠距教學，主因網路建設無法完全深入山區，不只建設成本過高外，如遇颱風還可能造成通訊中斷，因此WiMAX所提供的無線高速傳輸效能及最高30公里的涵蓋區域，就成為後壁鄉能和全台乃至全世界接軌的重要推手。
因此當地在學生不只在學校內，可利用WiMAX上網外，還可和國內其他學校進行遠距教學，提高中部地區的教學品質，真正縮短城鄉間的資訊差距。另一角度來看，在都會區的學校，也因WiMAX的應用，了解中部偏遠區域的人文風情，讓來自台灣之美散佈到全國。
同樣的例子也出現在南投縣仁愛鄉春陽國小中。在教育部的全力支援下，國立暨南大學的網路應用服務中心為當地提供一對多的網路教學服務。每周四下午，春陽國小的中、高年級學生，可在電腦教室中，利用網路和暨南大學的大哥哥們討論電腦入門課程。上述過去較難鋪設網路主幹的區域，全因WiMAX的應用，都可體會到網路世界的多元。
路況管理 動態資料即時傳遞
WiMAX的應用不只這點，只要能發揮天馬行空的相像空間，都可創造WiMAX的全新應用。以路況管理為例，在一般都會區都有監視器做存證攝影，但受限於無線頻寬的因素，只能在發生事情後再給予調閱。有了WiMAX就不同，未來如發生交通肇事事故，在交管中心找到資料的同時，就可將動態資料立即傳輸到附近管區員警手上，縮短偵查所需的時間。由於WiMAX可供高速移動傳輸，就算車速達到100公里在高速公路上奔馳，還是能輕鬆接收。
對於非都會中心，路況管理較不容易，但多數危險路況都出現在此相關區域中，只要有WiMAX技術這些都得以解決。以大同公司為例，日前就以 WiMAX技術針對砂石車，研發出全新服務應用，若有非法的砂石車進入監控區域，監控人員能立刻透過WiMAX監看，並進行後續處理，避免交通事故的發生。
由上述可知，WiMAX和過去無線傳輸應用不同，比WiFi的應用廣，載具不只是手機，也可是筆記型電腦、桌上型電腦、PDA等，速度及頻寬更比3G高，但價格將會更低。由於屬於列為M－Taiwan新十大建設中，基本基地台在國家通訊委員會（NCC）的規定下，可和現有2G、3G基地台共構，因此對於民眾來說，在家與戶外都可以單一帳號無線上網，在享受便利性同時，全新的應用服務所需負擔的費用也將比現在更低 (只需500元以下)。
全台民眾生活 跨越界線大串聯
目前在政府積極推動下，我國在WiMAX的推廣及應用走的比其他國家還快，專業度更不輸其他國家。且台灣地型特殊，更利於WiMAX發展，因此不少國際大廠都將台灣設定為WiMAX重點推廣地區，這也是為何國內每項成功案例都可吸引國際間矚目的主因。目前台灣是WiMAX Forum（由Intel、Alvarion、Fujitsu、BT Group等組成）宣布的全球第四個WiMAX認證測試中心實驗室，並且是全球首座移動與固定式兼具的認證測試實驗室，這足以代表WiMAX Fo-rum對我國WiMAX產業的重視。
目前國際間對於WiMAX網路布建三大趨勢：一、技術趨勢：全球WiMAX網路佈建，技術16e (行動式)佈建比重將超過16d (固定式)。二、頻譜趨勢：全球WiMAX網路佈建使用頻譜將往2.5GHz移動。三、業者趨勢：全球WiMAX網路佈建，固網型業者加入戰局的比率大幅成長，顯示固網反攻行動之趨勢。上述趨勢剛好和我國發展WiMAX的方向相近，再加上政府積極投入，因此台灣民眾更可比全球其他地區，提早享受到幸福指數最高的行動無線傳輸應用服務外，更能因WiMAX將台灣民眾的生活不受地區串聯起來。
WiMAX小檔案（Worldwide interoperability for Microwave Access）
優點：高速傳輸達75Mbps，3G最高2Mbps涵蓋面郊區30公里，都會區2至7公里，WiFi只有100公尺在家與戶外都可以單一帳號無線上網，且上網費用比現在低 (500元以下) 基地台可和2G、3G共構，避免基地台在區會都過多之疑慮電磁波相對較低，民眾健康更有保障。
幸福指標：提供政府在治安、交通、醫療走入行動化。針對教育方面，偏遠地區拉寬頻主幹更具經濟效益，故WiMAX可提供遠距教學方案、各大校園內提供行動圖書館、互動教學及校園安全等。個人方面視訊電話不再出現馬賽克、玩線上遊戲不怕斷線，針對商務人士可打造出最佳「無線」辦公環境。
【2007/05/03 經濟日報】
Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
Bewise Inc. www.tool-tool.com
【彭子豪】
記得有一句知名手機廠的廣告詞－「科技始終來自人性」，但科技日新月異，常發現真的要人性化，還頗困難。尤其科技製品都來自少數人的實驗室中，這也是為何「科技新品」在追求市場量能時，常常反而無法將產品應用普及進而大賣。但如是以幸福傳達出全新科技觀，似乎值得人類期待，全新通訊應用WiMAX就是有這種能耐及魅力。
為何WiMAX可和幸福畫上等號，主因在此全新的無線通訊技術，可針對國內無線通訊技術如2G、3G及WiFi等，提供全面性的提升，將目前各項行動應用擴散到全台灣的每一個角落，打破過去通訊應用只能在都會區或是高人口密集度區域中發揮外，還可將現有應用達到高速應用化。簡單來說，WiMAX可將資訊流通及應用達到扁平化、全民化，相關應用不再只是由電信等相關業者提出需求及應用，而是全民當家，提出自己的需求，創造無線通訊應用的新幸福指標。
無線高速傳輸 克服山區網路建設難題
以台南縣後壁鄉為例，這一個名風淳樸的山地鄉鎮，但對於當地下一代的台灣主人翁，要和都市區域的小孩一樣，能利用網路來看世界似乎相當困難，更別說鄉內學校利用網路進行遠距教學，主因網路建設無法完全深入山區，不只建設成本過高外，如遇颱風還可能造成通訊中斷，因此WiMAX所提供的無線高速傳輸效能及最高30公里的涵蓋區域，就成為後壁鄉能和全台乃至全世界接軌的重要推手。
因此當地在學生不只在學校內，可利用WiMAX上網外，還可和國內其他學校進行遠距教學，提高中部地區的教學品質，真正縮短城鄉間的資訊差距。另一角度來看，在都會區的學校，也因WiMAX的應用，了解中部偏遠區域的人文風情，讓來自台灣之美散佈到全國。
同樣的例子也出現在南投縣仁愛鄉春陽國小中。在教育部的全力支援下，國立暨南大學的網路應用服務中心為當地提供一對多的網路教學服務。每周四下午，春陽國小的中、高年級學生，可在電腦教室中，利用網路和暨南大學的大哥哥們討論電腦入門課程。上述過去較難鋪設網路主幹的區域，全因WiMAX的應用，都可體會到網路世界的多元。
路況管理 動態資料即時傳遞
WiMAX的應用不只這點，只要能發揮天馬行空的相像空間，都可創造WiMAX的全新應用。以路況管理為例，在一般都會區都有監視器做存證攝影，但受限於無線頻寬的因素，只能在發生事情後再給予調閱。有了WiMAX就不同，未來如發生交通肇事事故，在交管中心找到資料的同時，就可將動態資料立即傳輸到附近管區員警手上，縮短偵查所需的時間。由於WiMAX可供高速移動傳輸，就算車速達到100公里在高速公路上奔馳，還是能輕鬆接收。
對於非都會中心，路況管理較不容易，但多數危險路況都出現在此相關區域中，只要有WiMAX技術這些都得以解決。以大同公司為例，日前就以 WiMAX技術針對砂石車，研發出全新服務應用，若有非法的砂石車進入監控區域，監控人員能立刻透過WiMAX監看，並進行後續處理，避免交通事故的發生。
由上述可知，WiMAX和過去無線傳輸應用不同，比WiFi的應用廣，載具不只是手機，也可是筆記型電腦、桌上型電腦、PDA等，速度及頻寬更比3G高，但價格將會更低。由於屬於列為M－Taiwan新十大建設中，基本基地台在國家通訊委員會（NCC）的規定下，可和現有2G、3G基地台共構，因此對於民眾來說，在家與戶外都可以單一帳號無線上網，在享受便利性同時，全新的應用服務所需負擔的費用也將比現在更低 (只需500元以下)。
全台民眾生活 跨越界線大串聯
目前在政府積極推動下，我國在WiMAX的推廣及應用走的比其他國家還快，專業度更不輸其他國家。且台灣地型特殊，更利於WiMAX發展，因此不少國際大廠都將台灣設定為WiMAX重點推廣地區，這也是為何國內每項成功案例都可吸引國際間矚目的主因。目前台灣是WiMAX Forum（由Intel、Alvarion、Fujitsu、BT Group等組成）宣布的全球第四個WiMAX認證測試中心實驗室，並且是全球首座移動與固定式兼具的認證測試實驗室，這足以代表WiMAX Fo-rum對我國WiMAX產業的重視。
目前國際間對於WiMAX網路布建三大趨勢：一、技術趨勢：全球WiMAX網路佈建，技術16e (行動式)佈建比重將超過16d (固定式)。二、頻譜趨勢：全球WiMAX網路佈建使用頻譜將往2.5GHz移動。三、業者趨勢：全球WiMAX網路佈建，固網型業者加入戰局的比率大幅成長，顯示固網反攻行動之趨勢。上述趨勢剛好和我國發展WiMAX的方向相近，再加上政府積極投入，因此台灣民眾更可比全球其他地區，提早享受到幸福指數最高的行動無線傳輸應用服務外，更能因WiMAX將台灣民眾的生活不受地區串聯起來。
WiMAX小檔案（Worldwide interoperability for Microwave Access）
優點：高速傳輸達75Mbps，3G最高2Mbps涵蓋面郊區30公里，都會區2至7公里，WiFi只有100公尺在家與戶外都可以單一帳號無線上網，且上網費用比現在低 (500元以下) 基地台可和2G、3G共構，避免基地台在區會都過多之疑慮電磁波相對較低，民眾健康更有保障。
幸福指標：提供政府在治安、交通、醫療走入行動化。針對教育方面，偏遠地區拉寬頻主幹更具經濟效益，故WiMAX可提供遠距教學方案、各大校園內提供行動圖書館、互動教學及校園安全等。個人方面視訊電話不再出現馬賽克、玩線上遊戲不怕斷線，針對商務人士可打造出最佳「無線」辦公環境。
【2007/05/03 經濟日報】
Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, ,,,etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, it’s our pleasure to serve for you. BW product including: utting tool、aerospace tool .HSS Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、Carbide end mill、Aerospace cutting tool、Carbide drill、High speed steel、Milling cutter、Core drill、Taperd end mills、Metric end mills、Miniature end mills、Pilot reamer、Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、NAS tool、DIN tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angeled carbide end mills、Carbide torus cutters、Carbide ball-noseed slot drills、Mould cutter、Tool manufacturer.
Bewise Inc. www.tool-tool.com
PVD / CVD薄膜沈積(Thin Film Deposition)www.tool-tool.com
Bewise Inc. www.tool-tool.com Reference source from the internet.
3-1 何謂薄膜沈積
在機械工業、電子工業或半導體工業領域，為了對所使用的材料賦與某種特性在材料表面上以各種方法形成被膜（一層薄膜），而加以使用，假如此被膜經由原子層的過程所形成時，一般將此等薄膜沈積稱為蒸鍍（蒸著）處理。採用蒸鍍處理時，以原子或分子的層次控制蒸鍍粒子使其形成被膜，因此可以得到以熱平衡狀態無法得到的具有特殊構造及功能的被膜。
薄膜沈積是目前最流行的表面處理法之一，可應用於裝飾品、餐具、刀具、工具、模具、半導體元件等之表面處理，泛指在各種金屬材料、超硬合金、陶瓷材料及晶圓基板的表面上，成長一層同質或異質材料薄膜的製程，以期獲得美觀耐磨、耐熱、耐蝕等特性。
薄膜沈積依據沈積過程中，是否含有化學反應的機制，可以區分為物理氣相沈積（Physical Vapor Deposition，簡稱PVD）通常稱為物理蒸鍍及化學氣相沈積（Chemical Vapor Deposition，簡稱CVD）通常稱為化學蒸鍍。
隨著沈積技術及沈積參數差異，所沈積薄膜的結構可能是『單晶』、『多晶』、或『非結晶』的結構。單晶薄膜的沈積在積體電路製程中特別重要，稱為是『磊晶』(epitaxy)。相較於晶圓基板，磊晶成長的半導體薄膜的優點主要有：可以在沈積過程中直接摻雜施體或受體，因此可以精確控制薄膜中的『摻質分佈』(dopant profile)，而且不包含氧與碳等雜質。
3-2 薄膜沈積機制
薄膜的成長是一連串複雜的過程所構成的。圖（一）為薄膜成長機制的說明圖。圖中首先到達基板的原子必須將縱向動量發散，原子才能『吸附』(adsorption)在基板上。這些原子會在基板表面發生形成薄膜所須要的化學反應。所形成的薄膜構成原子會在基板表面作擴散運動，這個現象稱為吸附原子的『表面遷徙』(surface migration)。當原子彼此相互碰撞時會結合而形成原子團過程，稱為『成核』(nucleation)。
原子團必須達到一定的大小之後，才能持續不斷穩定成長。因此小原子團會傾向彼此聚合以形成一較大的原子團，以調降整體能量。原子團的不斷成長會形成『核島』(island)。核島之間的縫隙須要填補原子才能使核島彼此接合而形成整個連續的薄膜。而無法與基板鍵結的原子則會由基板表面脫離而成為自由原子，這個步驟稱為原子的『吸解』(desorption)。PVD與CVD的差別在於：PVD的吸附與吸解是物理性的吸附與吸解作用，而CVD的吸附與吸解則是化學性的吸附與吸解反應。
圖（一） 薄膜沈積機制的說明圖
3-3 物理氣相沈積（物理蒸鍍）（PVD）
PVD顧名思義是以物理機制來進行薄膜湚積而不涉及化學反應的製程技術，所謂物理機制是物質的相變化現象，如蒸鍍(Evaporation)，蒸鍍源由固態轉化為氣態，濺鍍（Sputtering），蒸鍍源則由氣態轉化為電漿態。
PVD法係以真空、測射、離子化、或離子束等法使純金屬揮發，與碳化氫、氮氣等氣體作用，在加熱至400~600℃（1~3小時）的工件表面上，蒸鍍碳化物、氮化物、氧化物、硼化物等1~10μm厚之微細粒狀晶薄膜，因其蒸鍍溫度較低，結合性稍差（無擴散結合作用），且背對金屬蒸發源之工件陰部會產生蒸鍍不良現象。其優點為蒸鍍溫度較低，適用於經淬火－高溫回火之工、模具。若以回火溫度以下之低溫蒸鍍，其變形量極微，可維持高精密度，蒸鍍後不須再加工。表（一）為各種PVD法的比較。
PVD蒸鍍法
真空蒸鍍
濺射蒸鍍
離子蒸鍍
粒子生成機構
熱能
動能
熱能
膜生成速率
可提高
(<75μm/min)
純金屬以外很低
(Cu：1μm/min)
可提高
(<25μm/min)
粒子
原子、離子
原子、離子
原子、離子
蒸鍍均勻性
複雜形狀
若無氣體攪拌就不佳
良好，但膜厚分佈不均
良好，但膜厚分佈不均
小盲孔
不佳
不佳
不佳
蒸鍍金屬
可
可
可
蒸鍍合金
可
可
可
蒸鍍耐熱化合物
可
可
可
粒子能量
很低0.1~0.5eV
可提高1~100eV
可提高1~100Ev
惰性氣體離子衝擊
通常不可以
可，或依形狀不可
可
表面與層間的混合
通常無
可
可
加熱（外加熱）
可，通常有
通常無
可，或無
蒸鍍速率10-9m/sec
1.67~1250
0.17~16.7
0.50~833
表一 三種PVD法之比較
物理氣相沈積(Physical Vapor Deposition，PVD)是今日在半導體製程中，被廣泛運用於金屬鍍膜的技術。以現今之金屬化製程而言：舉凡Ti、TiW等所謂的反擴散層(Barrier Layer)，或是黏合層(Glue Layer)；Al之栓塞(plug)及導線(Interconnects)連接，以及高溫金屬如WSI、W、Co等，都使用物理氣相沈積法來完成。雖然小尺寸的金屬沈積以化學氣相沈積為佳，但物理氣相沈積法可說在半導體製程上，仍扮演著舉足輕重的角色。
一般來說，物理氣相沈積法可包含下列三種不同之技術：
(一) 蒸鍍(Evaporation)
(二) 分子束磊晶成長(Molecular Beam Epitaxy，MBE)
(三) 濺鍍(Sputter)
表（二）為此三種方法之比較。由於濺鍍可以同時達成極佳的沈積效率、大尺寸的沈積厚度控制、精確的成份控制及較底的製造成本。所以濺鍍是現今矽基半導體工業所唯一採用的方式，而且相信在可預見的將來，濺鍍也不易被取代。至於蒸鍍及分子束磊晶成長之應用，現在大約皆集中於實驗室級設備，或是化合物半導體工業中。
性質
方法
沈積速率
大尺寸厚度控制
精確成份控制
可沈積材料之選用
整體製造成本（COO）
蒸鍍(Evaporation)
極慢
差
差
少
差
分子束磊晶成長(MBE)
極慢
差
優秀
少
差
濺鍍(Sputter)
佳
佳
佳
多
優秀
表二 三種物理氣相沈積法之比較
由於濺鍍本身受到濺射原子多元散射方向的影響，不易得到在接觸洞連續且均勻覆蓋(Conformal)的金屬膜，進而影響填洞(Hole Filling)或栓塞(Plug-In)的能力；因此，現在濺鍍技術的重點，莫不著重於改進填洞時之階梯覆蓋率(Step Coverage)，以增加Ti/TiN反擴散層/黏合層/濕潤層(wetting Layer)等之厚度，或是發展鋁栓塞(Al-plug)及平坦化製程(Planarization)，以改善元件之電磁特性，並簡化製造流程，降低成本等。
3-3-1 蒸鍍(Evaporation)原理
蒸鍍是在高真空狀況下，將所要蒸鍍的材料利用電阻或電子束加熱達到熔化溫度，使原子蒸發，到達並附著在基板表面上的一種鍍膜技術。
在蒸鍍過程中，基板溫度對蒸鍍薄膜的性質會有很重要的影響。通常基板也須要適當加熱，使得蒸鍍原子具有足夠的能量，可以在基板表面自由移動，如此才能形成均勻的薄膜。基板加熱至150℃以上時，可以使沈積膜與基板間形成良好的鍵結而不致剝落。
3-3-2 濺鍍(Sputter)的原理
電漿(Plasma)是一種遭受部份離子化的氣體(Partially lonized Gases)。藉著
在兩個相對應的金屬電極板(Electrodes)上施以電壓，假如電極板間的氣體分子濃度在某一特定的區間，電極板表面因離子轟擊(Ion Bombardment)所產生的二次電子(Secondary Electrons)，在電極板所提供的電場下，將獲得足夠的能量，而與電極板間的氣體分子因撞擊而進行所謂的?/span>解離(Dissociation)?/span>，?/span>離子化(Ionization)?/span>，及?/span>激發(Excitation)?/span>等反應，而產生離子、原子、原子團(Radicals)，及更多的電子，以維持電漿內各粒子間的濃度平衡。（詳見表三）
1.分子分解 (Molecular Dissociation)
ｅ－+A2→A+A+ｅ－
2.原子電離 (Atomic Ionization)
ｅ－+A→A++2ｅ－
3.分子電離 (Molecular Dissociation)
ｅ－+A2→A2++2ｅ－
4.原子激發 (Atomic Excitation)
ｅ－+A→A*+ｅ－
5.分子激發 (Molecular Excitation)
ｅ－+A2→A2*+ｅ－
表三 二次電子與氣體分子之撞擊狀況
圖（二）顯示一個DC電漿的陰極電板遭受離子轟擊的情形。脫離電將的帶正電荷離子，在暗區的電場加速下，將獲得極高的能量。當離子與陰電極產生轟擊之後，基於動量轉換(Momentum Transfer)的原理，離子轟擊除了會產生二次電子以外，還會把電極板表面的原子給?/span>打擊?/span>出來，這個動作，我們稱之為?/span>濺擊(Sputtering)?/span>
這些被擊出的電極板原子將進入電漿裡，然後利用諸如擴散(Diffusion)等的方式，最後傳遞到晶片的表面，並因而沈積。這種利用電漿獨特的雕子轟擊，以動量轉換的原理，在氣相中(Gas Phase)製備沈積元素以便進行薄膜沈積的PVD技術，稱之為?/span>測鍍(sputtering Deposition)。?/span>基於以上的模型，測鍍的沈積機制，大致上可以區分為以下幾個步驟：
(1) 電漿內所產生的部份離子，將脫離電漿並往陰極板移動。
(2) 經加速的離子將轟撞(Bombard)在陰電極板的表面除產生二次電子外，且因此而擊出電極板原子。
(3) 被擊出的電極板原子將進入電漿內，且最後傳遞到另一個放置有晶片的電極板的表面。
(4) 這些被吸附(Adsorded)在晶片表面的吸附原子(Adatoms)，將進行薄膜的沈積。
圖（二） 測鍍(Sputter)示意圖
3-3-3 離子化金屬電漿(Ionized Metal Plasma，簡稱IMP)
IMP技術，應用了較一般金屬測鍍高上10-100倍的電漿密度。自1996
年由Applied Materials公司推出後，立即受到廣泛的注意。
IMP的基本示意圖，如圖（三）所示，這其中包含了一組傳統的磁式直流電源(Magnetion DC Power)，以及另一組無線電頻率之交流電(RF Power)。由Magnetion DC Power產生的電漿，用來將靶極上的金屬原子濺射出來。當這些金屬原子行經濺鍍室中的空間時，若通入較高的製程氣壓，則這些金屬原子便有大幅的機會，與氣體產生大量碰撞，因而首先被?/span>熱激化?Thermally Activated)；若與此同時，施於RF power之電磁震盪，因此加速這些金屬與氣體及電子間的碰撞，則便有大量的濺鍍金屬可被?/span>離子化?Ionized)，而不再如傳統濺鍍的是中性原子，也因此IMP電漿密度會較一般濺鍍為高，大約是在1011至1012cm-3之間。這些離子化的濺鍍金屬，會因在晶圓台座上，所自然因電漿而形成之自生負偏壓(Self-Bias)，而被直線加速往晶圓表面前進。如此一來，便可獲致方向性極佳的原子流量（換句話說，極優異的底部覆蓋率），與不錯的沈積速率。此外，我們亦可在晶圓台座上選擇性地裝上另一組RF偏壓，以期達到更佳的底部覆蓋率，並且更可藉此改變沈積薄膜的晶體結構。
圖（三） IMP示意圖
如上所述，濺鍍金屬被離子化的機率，取決於其停留在電漿中的時間。若停留時間愈長，則其被熱淚化與離子化的機率也愈大。通常由靶極被濺射下來的金屬原子，都帶有極高的能量（-1到10eV）與極高的速度。這些高速原子在電漿中停留時間極短，便會到達晶圓表面，而無法被有效的離子化。因此IMP必須藉金屬原子與氣體之有效碰撞，來減慢其速度，以增長其停留時間。也因此，IMP必須在較高的壓力下操作(~>10mtorr)，以便先增加金屬與氣體碰撞的機會。
與傳統濺鍍相比，IMP有較低及更均勻分佈的電阻值，同時IMP亦可以沈積較少之厚度，仍可達到所需的底部覆蓋厚度。如此一來，不僅可直接減少金屬沈積的成本，更因沈積時間亦得以縮短，整體的晶片產能率(Throughput)，將得以提高，所以製造成本(Cost of Owner ship , COO)將遠較傳統濺鍍為低。正因IMP的眾多優點，它已被眾多半導體公司寄予厚望，認為是可以運用於0.25μm以下世代的革命性製程。
3-3-4 未來PVD的發展趨勢
(1) 將PVD與CVD整合在同一系統上
隨著元件的尺寸繼續縮小，傳統的濺鍍方法已無法勝任小於0.25μm的製程。前述的IMP，則可以提供一合適的新製程，以應用於下一代製程的需求。然而由於現今IMP TiN製程尚未完全成熟，而嘗試利用IMP來沈積Al，則可能會因IMP的電漿溫度，接近Al的熔點，而有無法運用之憾。為了解決此一難題，相信CVD TiN以及CVD Al將會有極大的可能，與IMP同時應用，而形成一完整的PVD/CVD整合系統。舉例來說，Ti/TiN的反擴散層，可以應用IMP Ti及CVD TiN在同一系統內，依序連續使用二個沈積室來加以完成。如此不僅不需使用各別的PVD及CVD兩套設備，更可因為製程未中斷暴露於大氣之中，而避免了界面氧化、吸濕及微塵等問題，而提高了晶片的良率與元件的電性及可靠性。
(2) 發展低溫PVD製程，以保證低介電常數之介電化合物。
(3) 當線寬0.18μm以下的世代來臨時，銅製程是否能成功地取代鋁製程以及反擴散層Ta/TaN/Wn技術是否成熟？如上所述，均是未來非常值得研究而且迫切需要發展的課題。
3-4 化學氣相沈積（化學蒸鍍）（CVD）
CVD是將反應源以氣體形式通入反應腔中，經由氧化，還原或與基板反應之方式進行化學反應，其生成物藉內擴散作用而沈積基板表面上。
CVD法係將金屬氯化物、碳化氫、氮氣等氣體導入密閉之容器內，在真空、低壓、電漿等氣氛狀況下把工作加熱至1000℃附近2~8小時，將所需之碳化物、氮化物、氧化物、硼化物等柱狀晶薄膜沈積在工件表面，膜厚約1~30μm（5~10μm），結合性良好（蒸鍍溫度高，有擴散結合現象），較複雜之形狀及小孔隙都能蒸鍍；唯若用於工、模具鋼，因其蒸鍍溫度高於鋼料之回火溫度，故蒸鍍後需重新施予淬火－回火，不適用於具尺寸精密要求之工、模具。
1.密閉容器 2.電熱爐 3.氣化器 4.固體氣化器 5.回收槽 6.旋轉泵 7.液體排出泵
圖（四） 典型之CVD裝置示意圖
3-4-1 CVD原理
在半導體製程上，CVD反應的環境，包括：溫度、壓力、氣體的供給方式、流量、氣體混合比及反應器裝置等等。基本上氣體傳輸、熱能傳遞及反應進行三方面，亦即反應氣體被導入反應器中，藉由擴散方式經過邊界層(boundary layer)到達晶片表面，而由晶片表面提供反應所需的能量，反應氣體就在晶片表面產生化學變化，生成固體生成物，而沈積在晶片表面。
3-4-2 CVD反應機制
圖（四）顯示在化學氣相沈積程所包含的主要機制。其中可以分為下列五個主畏的步驟：(a).首先在沈積室中導入反應氣體，以及稀釋用的惰性氣體所構成的混合氣體，『主氣流』(mainstream)、(b).主氣流中的反應氣體原子或分子往內擴散移動通過停滯的『邊界層』(boundary layer)而到達基板表面、(c).反應氣體原子被『吸附』(adsorbed)在基板上、(d).吸附原子(adatoms)在基板表面遷徙，並且產生薄膜成長所須要的表面化學反應、(e).表面化學反應所產生的氣庇生成物被『吸解』(desorbed)，並且往外擴散通過邊界層而進入主氣流中，並由沈積室中被排除。
圖（五） 學氣相沈積的五個主要機制：
(a).導入反應物主氣流
(b).反應物內擴散
(c).原子吸附
(d).表面化學反應
(e).生成物外擴散及移除
3-4-3 CVD的種類與比較
在積體電路製程中，經常使用的CVD技術有：(1).『大氣壓化學氣相沈積』(atmospheric pressure CVD、縮寫APCVD)系統、(2).『低壓化學氣相沈積』(low pressure CVD、縮寫LPCVD)系統、(3).『電漿輔助化學氣相沈積』(plasma enhanced CVD、縮寫PECVD)系統。在表（四）中將上述的三種CVD製程間的相對優缺點加以列表比較，並且就CVD製程在積體電路製程中的各種可能的應用加以歸納。
製程
優點
缺點
應用
APCVD
反應器結構簡單
沈積速率快
低溫製程
步階覆蓋能力差
粒子污染
低溫氧化物
LPCVD
高純度
步階覆蓋極佳
可沈積大面積晶片
高溫製程
低沈積速率
高溫氧化物
多晶矽
鎢，矽化鎢
PECVD
低溫製程
高沈積速率
步階覆蓋性良好
化學污染
粒子污染
低溫絕緣體
鈍化層
表四 各種CVD製程的優缺點比較及其應用
3-4-4 大氣壓化學氣相沈積系統
APCVD是在近於大氣壓的狀況下進行化學氣相沈積的系統。圖（五）是一個連續式APCVD系統的結構示意圖。圖中晶片是經由輸送帶傳送進入沈積室內以進行CVD作業，這種作業方式適合晶圓廠的固定製程。圖中工作氣體是由中央導入，而在外圍處的快速氮氣氣流會形成『氣簾』(air curtain)作用，可藉此氮氣氣流來分隔沈積室內外的氣體，使沈積室內的危險氣體不致外洩。
APCVD系統的優點是具有高沈積速率，而連續式生產更是具有相當高的產出數，因此適合積體電路製程。APCVD系統的其他優點還有良好的薄膜均勻度，並且可以沈積直徑較大的晶片。然而APCVD的缺點與限制則是須要快速的氣流，而且氣相化學反應發生。在大氣壓狀況下，氣體分子彼此碰撞機率很高，因此很容易會發生氣相反應，使得所沈積的薄膜中會包含微粒。通常在積體電路製程中。APCVD只應用於成長保護鈍化層。此外，粉塵也會卡在沈積室壁上，因此須要經常清洗沈積室。
圖（六） 大氣壓化學氣相沈積(APCVD)系統結構示意圖
3-4-5 低壓化學氣相沈積系統
低壓化學氣相沈積(LPCVD)是在低於大氣壓狀況下進行沈積。圖（六）是一個典型的低壓化學氣相沈積系統的結構示意圖。在這個系統中沈積室(deposition chamber)是由石英管(quartz tube)所構成，而晶片則是豎立於一個特製的固定架上，這是一種『批次型式』(batch-type)的沈積製程方式。這種系統是一個熱壁系統，加熱裝置是置於石英管外。在LPCVD系統中須要安裝一個真空幫浦，使沈積室內保持在所設定的低壓狀況，並且使用壓力計來監控製程壓力。在『三區高溫爐』(3-zone furnace)中溫度是由氣體入口處往出口處逐漸升高，以彌補由於氣體濃度在下游處的降低，所可能造成的沈積速率不均勻現象。
與APCVD系統相比較，LPCVD系統的主要優點在於具有優異的薄膜均勻度，以及較佳的階梯覆蓋能力，並且可以沈積大面積的晶片；而LPCVD的缺點則是沈積速率較低，而且經常使用具有毒性、腐蝕性、可燃性的氣體。由於LPCVD所沈積的薄膜具有較優良的性質，因此在積體電路製程中LPCVD是用以成長磊晶薄膜及其它品質要求較高的薄膜。
圖（七） 低壓化學氣相沈積（LPCVD）系統結構示意圖
3-4-6 電漿輔助化學氣相沈積系統
電漿輔助化學氣相沈積（PECVD）系統使用電漿的輔助能量，使得沈積反應的溫度得以降低。在PECVD中由於電漿的作用而會有光線的放射出來，因此又稱為『輝光放射』(glow discharge)系統。圖（七）是一個PECVD系統的結構示意圖。圖中沈積室通常是由上下的兩片鋁板，以及鋁或玻璃的腔壁所構成的。臏體內有上下兩塊鋁製電極，晶片則是放置於下面的電極基板之上。電極基板則是由電阻絲或燈泡加熱至100℃至400℃之間的溫度範圍。當在二個電極板間外加一個13.56MHz的『射頻』(radio frequency，縮寫RF)電壓時，在二個電極之間會有輝光放射的現象。工作氣體則是由沈積室外緣處導入，並且作徑向流動通過輝光放射區域，而在沈積室中央處由真空幫浦加以排出。
PECVD的沈積原理與一般的CVD之間並沒有太大的差異。電漿中的反應物是化學活性較高的離子或自由基，而且基板表面受到離子的撞擊也會使得化學活性提高。這兩項因素都可促進基板表面的化學反應速率，因此PECVD在較低的溫度即可沈積薄膜。在積體電路製程中，PECVD通常是用來沈積SiO2 與Si3N4 等介電質薄膜。PECVD的主要優點是具有較低的沈積溫度；而PECVD的缺點則是產量低，容易會有微粒的污染。而且薄膜中常含有大量的氫原子。
圖（八） 電漿輔助化學氣相沈積系統的結構示意圖
3-5 CVD與PVD之比較
1. 選材：
化學蒸鍍－裝飾品、超硬合金、陶瓷
物理蒸鍍－高溫回火之工、模具鋼
2. 蒸鍍溫度、時間及膜厚比較
化學蒸鍍－1000℃附近，2~8小時，1~30μm(通常5~10μm)
物理蒸鍍－400~600℃，1~3小時，1~10μm
3. 物性比較
化學蒸鍍皮膜之結合性良好，較複雜之形狀及小孔隙都能蒸鍍；唯若用於工、模具鋼，因其蒸鍍溫度高於鋼料之回火溫度，故蒸鍍後需重施予淬火－回火，不適用於具精密尺寸要求之工、模具。
不需強度要求之裝飾品、超硬合金、陶瓷等則無上述顧慮，故能適用。物理蒸鍍皮膜之結合性較差，且背對金屬蒸發源之處理件陰部會產生蒸鍍不良現象；但其蒸鍍溫度可低於工、模具鋼的高溫回火溫度，且其蒸鍍後之變形甚微，故適用於經高溫回火之精密工具、模具。
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3-1 何謂薄膜沈積
在機械工業、電子工業或半導體工業領域，為了對所使用的材料賦與某種特性在材料表面上以各種方法形成被膜（一層薄膜），而加以使用，假如此被膜經由原子層的過程所形成時，一般將此等薄膜沈積稱為蒸鍍（蒸著）處理。採用蒸鍍處理時，以原子或分子的層次控制蒸鍍粒子使其形成被膜，因此可以得到以熱平衡狀態無法得到的具有特殊構造及功能的被膜。
薄膜沈積是目前最流行的表面處理法之一，可應用於裝飾品、餐具、刀具、工具、模具、半導體元件等之表面處理，泛指在各種金屬材料、超硬合金、陶瓷材料及晶圓基板的表面上，成長一層同質或異質材料薄膜的製程，以期獲得美觀耐磨、耐熱、耐蝕等特性。
薄膜沈積依據沈積過程中，是否含有化學反應的機制，可以區分為物理氣相沈積（Physical Vapor Deposition，簡稱PVD）通常稱為物理蒸鍍及化學氣相沈積（Chemical Vapor Deposition，簡稱CVD）通常稱為化學蒸鍍。
隨著沈積技術及沈積參數差異，所沈積薄膜的結構可能是『單晶』、『多晶』、或『非結晶』的結構。單晶薄膜的沈積在積體電路製程中特別重要，稱為是『磊晶』(epitaxy)。相較於晶圓基板，磊晶成長的半導體薄膜的優點主要有：可以在沈積過程中直接摻雜施體或受體，因此可以精確控制薄膜中的『摻質分佈』(dopant profile)，而且不包含氧與碳等雜質。
3-2 薄膜沈積機制
薄膜的成長是一連串複雜的過程所構成的。圖（一）為薄膜成長機制的說明圖。圖中首先到達基板的原子必須將縱向動量發散，原子才能『吸附』(adsorption)在基板上。這些原子會在基板表面發生形成薄膜所須要的化學反應。所形成的薄膜構成原子會在基板表面作擴散運動，這個現象稱為吸附原子的『表面遷徙』(surface migration)。當原子彼此相互碰撞時會結合而形成原子團過程，稱為『成核』(nucleation)。
原子團必須達到一定的大小之後，才能持續不斷穩定成長。因此小原子團會傾向彼此聚合以形成一較大的原子團，以調降整體能量。原子團的不斷成長會形成『核島』(island)。核島之間的縫隙須要填補原子才能使核島彼此接合而形成整個連續的薄膜。而無法與基板鍵結的原子則會由基板表面脫離而成為自由原子，這個步驟稱為原子的『吸解』(desorption)。PVD與CVD的差別在於：PVD的吸附與吸解是物理性的吸附與吸解作用，而CVD的吸附與吸解則是化學性的吸附與吸解反應。
圖（一） 薄膜沈積機制的說明圖
3-3 物理氣相沈積（物理蒸鍍）（PVD）
PVD顧名思義是以物理機制來進行薄膜湚積而不涉及化學反應的製程技術，所謂物理機制是物質的相變化現象，如蒸鍍(Evaporation)，蒸鍍源由固態轉化為氣態，濺鍍（Sputtering），蒸鍍源則由氣態轉化為電漿態。
PVD法係以真空、測射、離子化、或離子束等法使純金屬揮發，與碳化氫、氮氣等氣體作用，在加熱至400~600℃（1~3小時）的工件表面上，蒸鍍碳化物、氮化物、氧化物、硼化物等1~10μm厚之微細粒狀晶薄膜，因其蒸鍍溫度較低，結合性稍差（無擴散結合作用），且背對金屬蒸發源之工件陰部會產生蒸鍍不良現象。其優點為蒸鍍溫度較低，適用於經淬火－高溫回火之工、模具。若以回火溫度以下之低溫蒸鍍，其變形量極微，可維持高精密度，蒸鍍後不須再加工。表（一）為各種PVD法的比較。
PVD蒸鍍法
真空蒸鍍
濺射蒸鍍
離子蒸鍍
粒子生成機構
熱能
動能
熱能
膜生成速率
可提高
(<75μm/min)
純金屬以外很低
(Cu：1μm/min)
可提高
(<25μm/min)
粒子
原子、離子
原子、離子
原子、離子
蒸鍍均勻性
複雜形狀
若無氣體攪拌就不佳
良好，但膜厚分佈不均
良好，但膜厚分佈不均
小盲孔
不佳
不佳
不佳
蒸鍍金屬
可
可
可
蒸鍍合金
可
可
可
蒸鍍耐熱化合物
可
可
可
粒子能量
很低0.1~0.5eV
可提高1~100eV
可提高1~100Ev
惰性氣體離子衝擊
通常不可以
可，或依形狀不可
可
表面與層間的混合
通常無
可
可
加熱（外加熱）
可，通常有
通常無
可，或無
蒸鍍速率10-9m/sec
1.67~1250
0.17~16.7
0.50~833
表一 三種PVD法之比較
物理氣相沈積(Physical Vapor Deposition，PVD)是今日在半導體製程中，被廣泛運用於金屬鍍膜的技術。以現今之金屬化製程而言：舉凡Ti、TiW等所謂的反擴散層(Barrier Layer)，或是黏合層(Glue Layer)；Al之栓塞(plug)及導線(Interconnects)連接，以及高溫金屬如WSI、W、Co等，都使用物理氣相沈積法來完成。雖然小尺寸的金屬沈積以化學氣相沈積為佳，但物理氣相沈積法可說在半導體製程上，仍扮演著舉足輕重的角色。
一般來說，物理氣相沈積法可包含下列三種不同之技術：
(一) 蒸鍍(Evaporation)
(二) 分子束磊晶成長(Molecular Beam Epitaxy，MBE)
(三) 濺鍍(Sputter)
表（二）為此三種方法之比較。由於濺鍍可以同時達成極佳的沈積效率、大尺寸的沈積厚度控制、精確的成份控制及較底的製造成本。所以濺鍍是現今矽基半導體工業所唯一採用的方式，而且相信在可預見的將來，濺鍍也不易被取代。至於蒸鍍及分子束磊晶成長之應用，現在大約皆集中於實驗室級設備，或是化合物半導體工業中。
性質
方法
沈積速率
大尺寸厚度控制
精確成份控制
可沈積材料之選用
整體製造成本（COO）
蒸鍍(Evaporation)
極慢
差
差
少
差
分子束磊晶成長(MBE)
極慢
差
優秀
少
差
濺鍍(Sputter)
佳
佳
佳
多
優秀
表二 三種物理氣相沈積法之比較
由於濺鍍本身受到濺射原子多元散射方向的影響，不易得到在接觸洞連續且均勻覆蓋(Conformal)的金屬膜，進而影響填洞(Hole Filling)或栓塞(Plug-In)的能力；因此，現在濺鍍技術的重點，莫不著重於改進填洞時之階梯覆蓋率(Step Coverage)，以增加Ti/TiN反擴散層/黏合層/濕潤層(wetting Layer)等之厚度，或是發展鋁栓塞(Al-plug)及平坦化製程(Planarization)，以改善元件之電磁特性，並簡化製造流程，降低成本等。
3-3-1 蒸鍍(Evaporation)原理
蒸鍍是在高真空狀況下，將所要蒸鍍的材料利用電阻或電子束加熱達到熔化溫度，使原子蒸發，到達並附著在基板表面上的一種鍍膜技術。
在蒸鍍過程中，基板溫度對蒸鍍薄膜的性質會有很重要的影響。通常基板也須要適當加熱，使得蒸鍍原子具有足夠的能量，可以在基板表面自由移動，如此才能形成均勻的薄膜。基板加熱至150℃以上時，可以使沈積膜與基板間形成良好的鍵結而不致剝落。
3-3-2 濺鍍(Sputter)的原理
電漿(Plasma)是一種遭受部份離子化的氣體(Partially lonized Gases)。藉著
在兩個相對應的金屬電極板(Electrodes)上施以電壓，假如電極板間的氣體分子濃度在某一特定的區間，電極板表面因離子轟擊(Ion Bombardment)所產生的二次電子(Secondary Electrons)，在電極板所提供的電場下，將獲得足夠的能量，而與電極板間的氣體分子因撞擊而進行所謂的?/span>解離(Dissociation)?/span>，?/span>離子化(Ionization)?/span>，及?/span>激發(Excitation)?/span>等反應，而產生離子、原子、原子團(Radicals)，及更多的電子，以維持電漿內各粒子間的濃度平衡。（詳見表三）
1.分子分解 (Molecular Dissociation)
ｅ－+A2→A+A+ｅ－
2.原子電離 (Atomic Ionization)
ｅ－+A→A++2ｅ－
3.分子電離 (Molecular Dissociation)
ｅ－+A2→A2++2ｅ－
4.原子激發 (Atomic Excitation)
ｅ－+A→A*+ｅ－
5.分子激發 (Molecular Excitation)
ｅ－+A2→A2*+ｅ－
表三 二次電子與氣體分子之撞擊狀況
圖（二）顯示一個DC電漿的陰極電板遭受離子轟擊的情形。脫離電將的帶正電荷離子，在暗區的電場加速下，將獲得極高的能量。當離子與陰電極產生轟擊之後，基於動量轉換(Momentum Transfer)的原理，離子轟擊除了會產生二次電子以外，還會把電極板表面的原子給?/span>打擊?/span>出來，這個動作，我們稱之為?/span>濺擊(Sputtering)?/span>
這些被擊出的電極板原子將進入電漿裡，然後利用諸如擴散(Diffusion)等的方式，最後傳遞到晶片的表面，並因而沈積。這種利用電漿獨特的雕子轟擊，以動量轉換的原理，在氣相中(Gas Phase)製備沈積元素以便進行薄膜沈積的PVD技術，稱之為?/span>測鍍(sputtering Deposition)。?/span>基於以上的模型，測鍍的沈積機制，大致上可以區分為以下幾個步驟：
(1) 電漿內所產生的部份離子，將脫離電漿並往陰極板移動。
(2) 經加速的離子將轟撞(Bombard)在陰電極板的表面除產生二次電子外，且因此而擊出電極板原子。
(3) 被擊出的電極板原子將進入電漿內，且最後傳遞到另一個放置有晶片的電極板的表面。
(4) 這些被吸附(Adsorded)在晶片表面的吸附原子(Adatoms)，將進行薄膜的沈積。
圖（二） 測鍍(Sputter)示意圖
3-3-3 離子化金屬電漿(Ionized Metal Plasma，簡稱IMP)
IMP技術，應用了較一般金屬測鍍高上10-100倍的電漿密度。自1996
年由Applied Materials公司推出後，立即受到廣泛的注意。
IMP的基本示意圖，如圖（三）所示，這其中包含了一組傳統的磁式直流電源(Magnetion DC Power)，以及另一組無線電頻率之交流電(RF Power)。由Magnetion DC Power產生的電漿，用來將靶極上的金屬原子濺射出來。當這些金屬原子行經濺鍍室中的空間時，若通入較高的製程氣壓，則這些金屬原子便有大幅的機會，與氣體產生大量碰撞，因而首先被?/span>熱激化?Thermally Activated)；若與此同時，施於RF power之電磁震盪，因此加速這些金屬與氣體及電子間的碰撞，則便有大量的濺鍍金屬可被?/span>離子化?Ionized)，而不再如傳統濺鍍的是中性原子，也因此IMP電漿密度會較一般濺鍍為高，大約是在1011至1012cm-3之間。這些離子化的濺鍍金屬，會因在晶圓台座上，所自然因電漿而形成之自生負偏壓(Self-Bias)，而被直線加速往晶圓表面前進。如此一來，便可獲致方向性極佳的原子流量（換句話說，極優異的底部覆蓋率），與不錯的沈積速率。此外，我們亦可在晶圓台座上選擇性地裝上另一組RF偏壓，以期達到更佳的底部覆蓋率，並且更可藉此改變沈積薄膜的晶體結構。
圖（三） IMP示意圖
如上所述，濺鍍金屬被離子化的機率，取決於其停留在電漿中的時間。若停留時間愈長，則其被熱淚化與離子化的機率也愈大。通常由靶極被濺射下來的金屬原子，都帶有極高的能量（-1到10eV）與極高的速度。這些高速原子在電漿中停留時間極短，便會到達晶圓表面，而無法被有效的離子化。因此IMP必須藉金屬原子與氣體之有效碰撞，來減慢其速度，以增長其停留時間。也因此，IMP必須在較高的壓力下操作(~>10mtorr)，以便先增加金屬與氣體碰撞的機會。
與傳統濺鍍相比，IMP有較低及更均勻分佈的電阻值，同時IMP亦可以沈積較少之厚度，仍可達到所需的底部覆蓋厚度。如此一來，不僅可直接減少金屬沈積的成本，更因沈積時間亦得以縮短，整體的晶片產能率(Throughput)，將得以提高，所以製造成本(Cost of Owner ship , COO)將遠較傳統濺鍍為低。正因IMP的眾多優點，它已被眾多半導體公司寄予厚望，認為是可以運用於0.25μm以下世代的革命性製程。
3-3-4 未來PVD的發展趨勢
(1) 將PVD與CVD整合在同一系統上
隨著元件的尺寸繼續縮小，傳統的濺鍍方法已無法勝任小於0.25μm的製程。前述的IMP，則可以提供一合適的新製程，以應用於下一代製程的需求。然而由於現今IMP TiN製程尚未完全成熟，而嘗試利用IMP來沈積Al，則可能會因IMP的電漿溫度，接近Al的熔點，而有無法運用之憾。為了解決此一難題，相信CVD TiN以及CVD Al將會有極大的可能，與IMP同時應用，而形成一完整的PVD/CVD整合系統。舉例來說，Ti/TiN的反擴散層，可以應用IMP Ti及CVD TiN在同一系統內，依序連續使用二個沈積室來加以完成。如此不僅不需使用各別的PVD及CVD兩套設備，更可因為製程未中斷暴露於大氣之中，而避免了界面氧化、吸濕及微塵等問題，而提高了晶片的良率與元件的電性及可靠性。
(2) 發展低溫PVD製程，以保證低介電常數之介電化合物。
(3) 當線寬0.18μm以下的世代來臨時，銅製程是否能成功地取代鋁製程以及反擴散層Ta/TaN/Wn技術是否成熟？如上所述，均是未來非常值得研究而且迫切需要發展的課題。
3-4 化學氣相沈積（化學蒸鍍）（CVD）
CVD是將反應源以氣體形式通入反應腔中，經由氧化，還原或與基板反應之方式進行化學反應，其生成物藉內擴散作用而沈積基板表面上。
CVD法係將金屬氯化物、碳化氫、氮氣等氣體導入密閉之容器內，在真空、低壓、電漿等氣氛狀況下把工作加熱至1000℃附近2~8小時，將所需之碳化物、氮化物、氧化物、硼化物等柱狀晶薄膜沈積在工件表面，膜厚約1~30μm（5~10μm），結合性良好（蒸鍍溫度高，有擴散結合現象），較複雜之形狀及小孔隙都能蒸鍍；唯若用於工、模具鋼，因其蒸鍍溫度高於鋼料之回火溫度，故蒸鍍後需重新施予淬火－回火，不適用於具尺寸精密要求之工、模具。
1.密閉容器 2.電熱爐 3.氣化器 4.固體氣化器 5.回收槽 6.旋轉泵 7.液體排出泵
圖（四） 典型之CVD裝置示意圖
3-4-1 CVD原理
在半導體製程上，CVD反應的環境，包括：溫度、壓力、氣體的供給方式、流量、氣體混合比及反應器裝置等等。基本上氣體傳輸、熱能傳遞及反應進行三方面，亦即反應氣體被導入反應器中，藉由擴散方式經過邊界層(boundary layer)到達晶片表面，而由晶片表面提供反應所需的能量，反應氣體就在晶片表面產生化學變化，生成固體生成物，而沈積在晶片表面。
3-4-2 CVD反應機制
圖（四）顯示在化學氣相沈積程所包含的主要機制。其中可以分為下列五個主畏的步驟：(a).首先在沈積室中導入反應氣體，以及稀釋用的惰性氣體所構成的混合氣體，『主氣流』(mainstream)、(b).主氣流中的反應氣體原子或分子往內擴散移動通過停滯的『邊界層』(boundary layer)而到達基板表面、(c).反應氣體原子被『吸附』(adsorbed)在基板上、(d).吸附原子(adatoms)在基板表面遷徙，並且產生薄膜成長所須要的表面化學反應、(e).表面化學反應所產生的氣庇生成物被『吸解』(desorbed)，並且往外擴散通過邊界層而進入主氣流中，並由沈積室中被排除。
圖（五） 學氣相沈積的五個主要機制：
(a).導入反應物主氣流
(b).反應物內擴散
(c).原子吸附
(d).表面化學反應
(e).生成物外擴散及移除
3-4-3 CVD的種類與比較
在積體電路製程中，經常使用的CVD技術有：(1).『大氣壓化學氣相沈積』(atmospheric pressure CVD、縮寫APCVD)系統、(2).『低壓化學氣相沈積』(low pressure CVD、縮寫LPCVD)系統、(3).『電漿輔助化學氣相沈積』(plasma enhanced CVD、縮寫PECVD)系統。在表（四）中將上述的三種CVD製程間的相對優缺點加以列表比較，並且就CVD製程在積體電路製程中的各種可能的應用加以歸納。
製程
優點
缺點
應用
APCVD
反應器結構簡單
沈積速率快
低溫製程
步階覆蓋能力差
粒子污染
低溫氧化物
LPCVD
高純度
步階覆蓋極佳
可沈積大面積晶片
高溫製程
低沈積速率
高溫氧化物
多晶矽
鎢，矽化鎢
PECVD
低溫製程
高沈積速率
步階覆蓋性良好
化學污染
粒子污染
低溫絕緣體
鈍化層
表四 各種CVD製程的優缺點比較及其應用
3-4-4 大氣壓化學氣相沈積系統
APCVD是在近於大氣壓的狀況下進行化學氣相沈積的系統。圖（五）是一個連續式APCVD系統的結構示意圖。圖中晶片是經由輸送帶傳送進入沈積室內以進行CVD作業，這種作業方式適合晶圓廠的固定製程。圖中工作氣體是由中央導入，而在外圍處的快速氮氣氣流會形成『氣簾』(air curtain)作用，可藉此氮氣氣流來分隔沈積室內外的氣體，使沈積室內的危險氣體不致外洩。
APCVD系統的優點是具有高沈積速率，而連續式生產更是具有相當高的產出數，因此適合積體電路製程。APCVD系統的其他優點還有良好的薄膜均勻度，並且可以沈積直徑較大的晶片。然而APCVD的缺點與限制則是須要快速的氣流，而且氣相化學反應發生。在大氣壓狀況下，氣體分子彼此碰撞機率很高，因此很容易會發生氣相反應，使得所沈積的薄膜中會包含微粒。通常在積體電路製程中。APCVD只應用於成長保護鈍化層。此外，粉塵也會卡在沈積室壁上，因此須要經常清洗沈積室。
圖（六） 大氣壓化學氣相沈積(APCVD)系統結構示意圖
3-4-5 低壓化學氣相沈積系統
低壓化學氣相沈積(LPCVD)是在低於大氣壓狀況下進行沈積。圖（六）是一個典型的低壓化學氣相沈積系統的結構示意圖。在這個系統中沈積室(deposition chamber)是由石英管(quartz tube)所構成，而晶片則是豎立於一個特製的固定架上，這是一種『批次型式』(batch-type)的沈積製程方式。這種系統是一個熱壁系統，加熱裝置是置於石英管外。在LPCVD系統中須要安裝一個真空幫浦，使沈積室內保持在所設定的低壓狀況，並且使用壓力計來監控製程壓力。在『三區高溫爐』(3-zone furnace)中溫度是由氣體入口處往出口處逐漸升高，以彌補由於氣體濃度在下游處的降低，所可能造成的沈積速率不均勻現象。
與APCVD系統相比較，LPCVD系統的主要優點在於具有優異的薄膜均勻度，以及較佳的階梯覆蓋能力，並且可以沈積大面積的晶片；而LPCVD的缺點則是沈積速率較低，而且經常使用具有毒性、腐蝕性、可燃性的氣體。由於LPCVD所沈積的薄膜具有較優良的性質，因此在積體電路製程中LPCVD是用以成長磊晶薄膜及其它品質要求較高的薄膜。
圖（七） 低壓化學氣相沈積（LPCVD）系統結構示意圖
3-4-6 電漿輔助化學氣相沈積系統
電漿輔助化學氣相沈積（PECVD）系統使用電漿的輔助能量，使得沈積反應的溫度得以降低。在PECVD中由於電漿的作用而會有光線的放射出來，因此又稱為『輝光放射』(glow discharge)系統。圖（七）是一個PECVD系統的結構示意圖。圖中沈積室通常是由上下的兩片鋁板，以及鋁或玻璃的腔壁所構成的。臏體內有上下兩塊鋁製電極，晶片則是放置於下面的電極基板之上。電極基板則是由電阻絲或燈泡加熱至100℃至400℃之間的溫度範圍。當在二個電極板間外加一個13.56MHz的『射頻』(radio frequency，縮寫RF)電壓時，在二個電極之間會有輝光放射的現象。工作氣體則是由沈積室外緣處導入，並且作徑向流動通過輝光放射區域，而在沈積室中央處由真空幫浦加以排出。
PECVD的沈積原理與一般的CVD之間並沒有太大的差異。電漿中的反應物是化學活性較高的離子或自由基，而且基板表面受到離子的撞擊也會使得化學活性提高。這兩項因素都可促進基板表面的化學反應速率，因此PECVD在較低的溫度即可沈積薄膜。在積體電路製程中，PECVD通常是用來沈積SiO2 與Si3N4 等介電質薄膜。PECVD的主要優點是具有較低的沈積溫度；而PECVD的缺點則是產量低，容易會有微粒的污染。而且薄膜中常含有大量的氫原子。
圖（八） 電漿輔助化學氣相沈積系統的結構示意圖
3-5 CVD與PVD之比較
1. 選材：
化學蒸鍍－裝飾品、超硬合金、陶瓷
物理蒸鍍－高溫回火之工、模具鋼
2. 蒸鍍溫度、時間及膜厚比較
化學蒸鍍－1000℃附近，2~8小時，1~30μm(通常5~10μm)
物理蒸鍍－400~600℃，1~3小時，1~10μm
3. 物性比較
化學蒸鍍皮膜之結合性良好，較複雜之形狀及小孔隙都能蒸鍍；唯若用於工、模具鋼，因其蒸鍍溫度高於鋼料之回火溫度，故蒸鍍後需重施予淬火－回火，不適用於具精密尺寸要求之工、模具。
不需強度要求之裝飾品、超硬合金、陶瓷等則無上述顧慮，故能適用。物理蒸鍍皮膜之結合性較差，且背對金屬蒸發源之處理件陰部會產生蒸鍍不良現象；但其蒸鍍溫度可低於工、模具鋼的高溫回火溫度，且其蒸鍍後之變形甚微，故適用於經高溫回火之精密工具、模具。
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