Full-Field Mask Error Enhancement Function

A computer system, comprising:

• a processor;
• a memory;
• and
• a program module for determining a source pattern to illuminate a photo-mask during a photo-lithographic process, the program module stored in the memory and configured to be executed by the processor, wherein the program module is configured to determine a full-field MEEF associated with a mask pattern for use in a photo-lithographic process, the program module including:
• instructions for generating one or more simulated wafer patterns corresponding to the mask pattern at an image plane in an optical path associated with the photo-lithographic process;
• and
• instructions for determining the full-field MEEF, which includes MEEF values in multiple directions at positions along one or more contours that define boundaries of one or more features in the one or more simulated wafer patterns, wherein at least one of the MEEF values is at a position on a contour where a critical dimension for a feature associated with the contour is undefined.