Patent ID: 6768958
Filing Date: 2004-07-27
Classification: G03F

Abstract:
A computer-implemented method for automatically calibrating a masking process simulator, comprising the steps of:(a) performing a masking process using a calibration mask and process parameters to produce a calibration pattern on a wafer; (b) creating an SEM image of the calibration pattern using a scanning electron microscope (SEM); (c) detecting edges of the pattern from the digital image using pattern recognition; (d) inputting data defining the calibration mask and the process parameters into a process simulator to produce an alim image estimating the calibration pattern that would be produced by the masking process; (e) overlaying the alim image and the detected edges of the digital image; (f) measuring a distance between contours of the pattern in the alim image and the detected edge; and (g) using one or more mathematical algorithms to iteratively change values of subset of the processing parameters input to the simulator until a set of processing parameter values are found that producers a minimum distance between the contours of the pattern in the alim image and the detected edges, wherein the subset of processing parameters includes focus, diffusion, sigma in, sigma out, angle of the pole location, numerical aperture, sigma of the pole, spherical, coma_x, coma_y, and intensity contour, thereby effectively calibrating the process simulator to compensate for process variations of the masking process.