Physical Modeling of Deprotection Induced Thickness Loss

High activation energy, chemically amplified resist systems exhibit a 4% to 15% volume shrinkage during the post-exposure bake process. Current lithography process simulators do not take this volume shrinkage into account, thus violating the continuity equations used to model the process. This work aims at describing the kinetics of the post-exposure bake process by tracking the volume shrinkage observed in high activation resists. A dynamic model is derived and corroborated with experimental results for Shipley UV5. A global simulation technique is then used in conjunction with the models to extract the lithography parameters for these resists.