EUV resist outgassing analysis in selete - art. no. 692342

Resists outgassing is one concern for extreme ultraviolet lithography (EUVL). The release of resist outgassing in an EUV exposure tool system can contaminate optics which could mean a decrease in EUV beam energy reaching the wafer surface. This could translate to lower throughputs and lesser productivity. One big reason why more information regarding EUV resist outgassing and the development of control and/or reduction techniques are necessary. To gain a deeper understanding of what factors affect the release of EUV resist outgassing in a vacuum chamber, an analysis of resist outgassing release characteristics using pressure rise method with an ion gauge and component classification using quadropole mass spectrometry (QMS) was performed. Utilizing poly-hydroxystyrene tert-butoxycarbonyl (PHS-t-BOC) model resists as reference, resist outgassing upon EUV exposure were found to be mainly composed of protecting group components released either by de-protection due to photoacids from PAG and decomposition of the protecting group component and photo acid generator (PAG). No significant amounts of quencher or solvent components were detected. It was also found that decomposed PAG are released upon EUV exposure but are not affected by the variation of other components of the resist. The release of protecting groups as resist outgassing meanwhile, are directly affected by the deprotection and neutralization reactions occurring in the resist film upon EUV exposure.