A method for process proximity correction may include 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.