Abstract: A method of simulating a post-exposure bake (PEB) process for chemically amplified resists having photoacids and protection-sites comprises the following steps. First, the initial PEB parameters are input to represent a temperature-time history of the PEB process. Then, the reaction constants and a diffusion coefficient are input to represent the chemically amplified resists. Wherein the reaction constants are temperature-dependent, and the diffusion coefficient is temperature-dependent and protection-site-dependent in the entire course of the PEB simulation. The protection-site concentration of the chemically amplified resists is computed by using an implicit scheme, and the photoacid concentrations are computed in a space occupied by the chemically amplified resists based on the diffusion coefficient by using an implicit scheme.