发明申请
US20080266561A1 OPTICAL GAIN APPROACH FOR ENHANCEMENT OF OVERLAY AND ALIGNMENT SYSTEMS PERFORMANCE 失效
增强覆盖和对准系统性能的光学增益方法

OPTICAL GAIN APPROACH FOR ENHANCEMENT OF OVERLAY AND ALIGNMENT SYSTEMS PERFORMANCE
摘要:
A resultant image of a grating target may be obtained by dividing an image of the target into first and second portions and optically modifying the first and/or second portion such that a final image formed from their combination is characterized by a Moiré pattern. The resultant image may be analyzed to determine a shift in the grating target from a shift in the Moiré pattern. Optical alignment apparatus may include a first beam splitter, an image transformation element optically coupled to the first beam splitter, and a second beam splitter. The first beam splitter divides an image of a grating target into first and second portions. The second beam splitter combines the first portion and the second portion. The image transformation element optically modifies the first and/or second portion such that a final image formed from their combination is characterized by a Moiré pattern.
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