Resist outgassing characteristics in extreme ultraviolet lithography

Extreme ultraviolet (EUV) lithography requires a vacuum environment for exposure. The hydrocarbons outgassing ion species affect the reflectivity of the mask and the imaging mirror under EUV irradiation. Concerning the high-annealing-type chemically amplified (CA) resist based on the polyhydroxy styrene (PHS) resin, it is confirmed that propylene glycol monomethylether (PGME) which is employed as a solvent has the lowest outgassing characteristics under EUV irradiation. Mitigation of the hydrocarbons outgassing species and line edge roughness (LER) requires the main-chain-decomposition-type CA resist. From the outgassing measurement results, the methacrylate base resin can be employed in the resist process in EUV lithography.