发明名称 |
Etch rate monitor using collimated light and method of using same |
摘要 |
An etch rate monitor for use with semiconductor wafer etching processes includes a source of light of normal incidence to the wafer surface through a window in the etching chamber. In a first embodiment, a Fresnel or positive lens is used to collect some of the diffraction orders caused by the repetitive patterns on the wafer surface which merge from the window. In alternate embodiments, a concave spherical mirror and/or a photodetector system are used to collect the diffraction orders. A collimating lens applies these diffraction orders of normal incidence to interference filters which reject plasma and ambient light and pass the diffraction orders to a photodetector to monitor etch rate as a function of the cycle period between interference minima or maxima caused by the difference in path length between the etched and not etched surfaces of the wafer.
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申请公布号 |
US5337144(A) |
申请公布日期 |
1994.08.09 |
申请号 |
US19920880464 |
申请日期 |
1992.05.05 |
申请人 |
APPLIED MATERIALS, INC. |
发明人 |
STRUL, BRUNO;DE GEUS, RICHARD;EBBING, PETER |
分类号 |
G01B11/06;G01B11/22;(IPC1-7):G01B9/02 |
主分类号 |
G01B11/06 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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