A method for forming a semiconductor device is provided. The method includes applying a photoresist composition over a substrate, thereby forming a photoresist layer over the substrate; performing a first baking process to the photoresist layer; exposing the photoresist layer to an extreme ultraviolet (EUV) radiation, thereby forming a pattern therein; performing a second baking process to the photoresist layer; and developing the photoresist layer having the pattern therein using a developer, thereby forming a patterned photoresist layer. The first baking process and the second baking process are conducted under an ambient atmosphere having a humidity level ranging from 55% to 100%.