Study of De-protection Reactions for Chemically Amplified Resists

An existing FT-IR spectrometer system incorporating a bake plate for in situ observation of protection group removal reactions (de-protection reactions) of chemically amplified resists is modified, leading to the development of a new de-protection reaction model. Modifications to the FT-IR spectrometer system are made to ensure full contact between a wafer and the bake plate, as is the case in actual PEB systems. Processes during initial wafer heating are found to be different to the previous equipment, in which a gap of 0.2 mm existed between the wafer and baking plate. Because the results of the improved system disagree with a previous model, a new model which fits the observed data much more consistently is proposed. The new de-protection reaction model incorporates the effects of acid evaporation, which are found to be significant.