Increasing lithographic depth of focus window using wafer topography
Various embodiments provide for topography aware optical proximity correction that can improve depth of focus during wafer lithography. The system can determine the topography of the wafer using real process information. The topographical variations can be based on random defects or structural details. The system can divide the wafer into regions based on the topography of the regions and determine depth of focus values for each of the regions. Optical proximity correction can then be performed on each region separately, using the separate defocus values to yield an accurate, topographically aware optical proximity correction model for the wafer. For regions with varying topography, optical proximity correction can be performed for two defocus values corresponding to the high and low extremes, such that the resulting simulated contour is satisfies a predetermined criterion associated with accuracy.
Cypress Semiconductor Corporation
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Xiaohai
Li