Wave Front Phase Imaging (WFPI), a new wafer geometry technique, is presented, that acquires 16.3 million data points in 12 seconds on a full 300mm wafer, providing lateral resolution of 65μm while holding the wafer vertically. The flatness of the silicon wafers used to manufacture integrated circuits (IC) is controlled to tight tolerances to help ensure that the full wafer is sufficiently flat for lithographic processing. Advanced lithographic patterning processes require a detailed map of the free, non-gravitational wafer shape to avoid overlay errors caused by depth-of-focus issues. For a wafer shape system to perform in a high-volume manufacturing environment, repeatability is a critical measure that needs to be tested. We present WFPI as a new technique with high resolution and high data count acquired at very high-speed using a system where the wafer is free from the effects of gravity and with a very high repeatability as measured according to the Semi standards M49.
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