The present disclosure provides an embodiment of a method for lithography patterning. The method includes coating a photoresist layer over a substrate, wherein the photoresist layer includes a first polymer, and a first photo-acid generator (PAG), and a chemical additive mixed in a solvent; performing an exposing process to the photoresist layer; and performing a developing process to the photoresist layer to form a patterned photoresist layer. The chemical additive has a non-uniform distribution in the photoresist layer.