Suiter Swantz pc llo
Method and system for regional phase unwrapping with pattern-assisted correction
A wafer metrology system includes an interferometer sub-system and a controller. The interferometer sub-system is configured to generate an interferogram with an intensity map that corresponds to a modulated representation of a wafer surface. Further, the interferometer sub-system includes a detector configured to capture the interferogram. The controller includes one or more processors configured to generate a wrapped phase map of the interferogram, define patterns associated with features on the wafer, and correct phase discontinuities by applying a phase unwrapping procedure to the wrapped phase map to generate an unwrapped phase map and correcting phase discontinuities in the unwrapped phase map based on the patterns, or by combining phase unwrapping and correction in a unified step. Further, the patterns comprise two or more structures such that a portion of the unwrapped phase map associated with structures of the same type is continuous across borders separating structures of the same type.
KLA—Tencor Corporation
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Helen Xiaowei Xuan
Liu Li Zhao