Abstract
The strong photoabsorption of typical backbone polymers such as poly(4-hydroxystyrene) (PHS) has been a concern in extreme ultraviolet (EUV) lithography. The development of highly sensitive chemically amplified resists by polymer absorption enhancement seems an unacceptable strategy for overcoming this problem because the side wall angle is basically determined by the gradient of energy absorption, namely the absorption coefficient of the polymer. In this study, the feasibility of a high-absorption resist process was investigated by a simulation based on EUV sensitization mechanisms. Compared with PHS-based resists, the fourfold enhancement of polymer absorption is feasible without side wall degradation partly due to the long migration range of secondary electrons, although it is necessary to reduce the resist thickness to 20 nm.