Patent ID: 7387866

Claim:
A computer implemented method for designing anti-reflective coating layers with desirable properties comprising: a) modeling a first anti-reflective coating with a first index of refraction, a first absorption, and a first thickness, wherein the first thickness is slightly less than a total maximum allowable thickness for said anti-reflective coating layers based on the requirements of a desired integrated circuit fabrication process; b) modeling a second anti-reflective coating with a second index of refraction, a second absorption, and second thickness, wherein the first and second indices of refraction are different, and the combined thicknesses of the first and second anti-reflective coatings is approximately equal to said total maximum allowable thickness; c) modeling the reflective properties of the anti-reflective coatings using a lithography modeling program; d) evaluating the reflective properties of said first and second anti-reflective coatings relative to a set of desired reflective properties; e) adjusting the thicknesses, indices of refraction, and absorptions of the anti-reflective coatings based on said evaluating step; f) repeating steps c, d, and e to arrive at a solution for anti-reflective coating layers which provide desired reflective properties.