Method of manufacturing a semiconductor device

A method for manufacturing a semiconductor device includes obtaining a design layout for a target layer of an optical proximity correction process, the design layout including a first block and a second block being a repetition block of the first block, dividing the design layout into a plurality of patches, performing the optical proximity correction process on the patches of the first block, applying corrected patches of the first block to the patches of the second block, respectively, forming a correction layout by performing the optical proximity correction process on boundary patches of the second block, fabricating a photomask corresponding to the correction layout, and forming patterns on a substrate corresponding to the photomask. Each of the patches is a standard unit on which the optical proximity correction process is performed.