Heating effect of the radiation chemistry of polyhydroxystyrene-type chemically amplified resists

摘要

The photomask used in the lithography process has the important role of transferring circuit pattern images onto the photoresist. To meet the demand for increased photomask manufacturing throughput, the current density of electron beam (EB) writers has been increased. EB exposure locally increases the resist temperature on the mask substrate depending on various factors, including current density, shot size, and writing order. Resist sensitivity increases with irradiated resist temperature, a phenomenon known as "heating effect". In this study, we reported the cause of the temperature-dependent sensitivity increase in a polyhydroxystyrene-type chemically amplified resist. The experimental results, including acid generation efficiency measurements and pulse radiolysis with changing temperature, suggest that the heating effect is mainly caused by the deprotonation efficiency associated with the radical cation of the base polymer.