Recent Progress in EUV Resist Outgas Research at EIDEC

The suppression of extreme ultraviolet (EUV) resist outgassing is one of the challenges in high-volume manufacturing with EUV lithography (EUVL), because it contributes to the contamination of the EUV scanner mirror optics, resulting in reflectivity loss. The outgas qualification using a witness sample (WS) has been developed into the general method for clarifying commercially available, chemically amplified resists. In our recent study, a resist outgas model is proposed and tested to investigate the contamination thickness' dependency on exposure dose. The model successfully explains the experimental outgas phenomenon. It is estimated that increasing exposure dose, in resists with low activation energies (Ea) in deprotection reactions, results in extreme increase in contamination thickness. The detail is explained in this paper.