A method of patterning a photoresist layer includes forming a photoresist layer on a substrate, exposing the photoresist layer to light using a first light source so as to induce a chemical change in the photoresist layer, performing a post-exposure bake process on the photoresist layer, the post-exposure bake process including irradiating the photoresist layer with at least two shots of laser light from a second light source such that the photoresist layer is heated to a first temperature, and performing a developing process on the photoresist layer after the post-exposure bake process, the development process selectively removing a portion of the photoresist layer.