A solution for performing an optical proximity correction (OPC) process on a layout by incorporating a critical dimension (CD) correction is provided. A method may include separating the layout into a first portion and a second portion corresponding to the two exposures; creating a model for calculating a CD correction for a site on the first portion, the model corresponding to a topography change on the site due to the double exposures; implementing an OPC iteration for the fragment based on the model to generate an OPC solution for the first portion; and combining the OPC solution for the first portion with an OPC solution for the second portion to generate an OPC solution for the layout to generate a mask for fabricating a structure using the layout.