Patent ID: 8762901

Claim:
A method for process proximity correction, the method comprising: obtaining a point spread function (PSF) from test patterns, the test patterns including an etching process performed thereon; generating a target layout with polygonal patterns; dividing the target layout into grid cells; generating a density map including long-range layout densities, each of the long-range layout densities being obtained from the polygonal patterns located within a corresponding one of the grid cells; performing a convolution of the long-range layout densities with the PSF to obtain long-range etch skews for the grid cells; and generating an etch bias model including short-range etch skews and the long-range etch skews, each of the short-range etch skews being obtained from a neighboring region of a target pattern selected from the polygonal patterns in each of the grid cells; and performing the process proximity correction on the target layout using the etch bias model in order to design a photomask layout.