Line-edge-roughness (LER) and the relationship to resist processing and materials design is a critical problem for sub-65 nm photolithography. In this work we investigate how chemical composition fluctuations (heterogeneity) produced by the reaction-diffusion of photoacids in chemically amplified photoresists affect the resulting LER through computer simulation. A 3-dimensional microscopic picture of reaction-diffusion of individual photoacid accounts for the deprotection fluctuation formed by the post exposure bake (PEB). The resulting LER is related to both the gradient of average deprotection profile and the degree of local chemical heterogeneity. The effect of dose contrast, PEB time, diffusivity of photoacid and trapping strength on the chemical heterogeneity are evaluated and compared to neutron reflectivity measurements.
Proceedings Title: Proceedings of SPIE
Conference Dates: February 25-March 2, 2007
Conference Location: San Jose, CA
Conference Title: SPIE Advanced Lithography
Pub Type: Conferences
diffusion, LER, line edge roughness, photo acid, photoresist, simulation, thin film