Investigating deprotection-induced shrinkage and retro-grade sidewalls in NTD resists

摘要

Two aspects of NTD resists, deprotection-induced shrinkage, and retro-grade sidewalls, are investigated through experimentation and simulation. Simulation predicts that NTD resist profiles should often have retro-grade sidewall angles due to the attenuation of light as it propagates down through the resist. Resist shrinkage induced from both the deprotection during PEB and from exposure to electrons during SEM can cause CD and sidewall changes. The interplay between the shrinkage and the retro-grade sidewalls is discussed.