Thermal and acid‐catalyzed deprotection kinetics in candidate deep ultraviolet resist materials

Deep ultraviolet (UV) chemically amplified (CA) resists are leading candidates for semiconductor lithography manufacturing in the sub‐half‐micron regime. In this article, we describe in situ, high data rate, accurate measurements of the chemical kinetics that occur in CA resists during the post‐exposure bake. The thermal and acid‐catalyzed deprotection of two candidate deep‐UV resist materials, poly(p‐t‐butoxycarbonyloxystyrene) (PTBOCST) and poly(t‐butylmethacrylate) (PTBMA), was characterized. The thermal deprotection of PTBOCST and PTBMA showed auto‐accelerated behavior as the reaction proceeds, while the acid‐catalyzed deprotection displayed inhibition as extent of conversion increased. We propose models for the thermal and acid‐catalyzed deprotection and extracted rate coefficients using a stochastic kinetics simulator. Excellent agreement between the model and experimental data was obtained.