The inventive concepts provide a method for forming a hard mask pattern. The method includes forming a hard mask layer on an etch target layer disposed on a substrate, forming a photoresist pattern having an opening exposing one region of the hard mask layer, performing an oxygen ion implantation process on the one region using the photoresist pattern as a mask to form an oxidized portion in the one region, and patterning the hard mask layer using the oxidized portion as an etch mask.