SEM contours are used to complement CD measurements in OPC model calibration. This is done to capture 2D information about printed features into the model while CD measurement data is kept to maintain accuracy for 1D features. As the method progresses, there are emerging challenges that are normally not found in CD based calibration. One such challenge is the need to align SEM contours with calibration features. This is particularly important in determining model accuracy since contour calibration typically involves a cost function that compares the SEM contours to the simulated print images. This paper describes the proposed technique and compare the results of calibration between aligned and misaligned contour data.
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