Patent ID: 8484587
Filing Date: 2013-07-09
Classification: G03F,G06F

Abstract:
1. A method for simulating a photolithographic process, comprising: receiving first information comprising parameters of an illumination system of a photolithographic exposure system; receiving second information comprising parameters of a projection-processing system of the photolithographic exposure system; computing, by use of a computer, from said first information third information characterizing said illumination system by a plurality of modes impingent upon a mask being illuminated thereby and a respective plurality of mode weights, said mask having a mask transmittance function; receiving fourth information comprising a plurality of basis spatial functions not dependent on at least one process variation and not dependent on a target depth; computing from said third and fourth information a plurality of model kernels, each model kernel corresponding to a product of one of said basis spatial functions and one of said modes; computing a plurality of convolution results corresponding to a convolution of the mask transmittance function with each of said model kernels; computing a plurality of partial intensity functions, each partial intensity function corresponding to a first subset of said convolution results associated with a first of said basis spatial functions and a second subset of said convolution results associated with a second of said basis spatial functions, each partial intensity function computed as a modewise weighted sum of the products of pective members of said first and second subsets; computing from said second information a plurality of expansion coefficients characterizing said projection processing system in conjunction with said basis spatial functions, said expansion coefficients being dependent on at least one of the process variation and the target depth; computing a resultant intensity as a sum of said partial intensity functions weighted according to corresponding pairs of said expansion coefficients; whereby said resultant intensity may be subsequently computed for different values of said process variation and target depth without requiring a recomputation of said partial intensity functions.