Role of counter-anion chemistry, free volume, and reaction byproducts in chemically amplified resists

Background: A fundamental understanding of the physical processes controlling deprotection in chemical amplified resists (CARs) is critical to improve their utility for high-resolution lithography.Aim/Approach: We employ a combined experimental and computational approach to examine the impacts of excess free volume generation, reaction byproducts, catalyst clustering, and catalyst counter-anion chemistry/size on deprotection rates in a model terpolymer CAR.Results: These studies demonstrate that catalyst diffusion can be enhanced by a combination of excess free volume and reaction byproducts, and that differences in the rotational mobility of the catalyst (controlled by counter-anion chemistry/size) play a key role in local reaction rates.Conclusions: Our results highlight that while many top-down models may capture experimental deprotection kinetics in chemically amplified resists, these models may not capture the underlying physics of the system. This further supports the necessity of incorporating experimental or atomistic data in the development of such models and in their extension to models of lithography.