Effects of molecular weight and dispersity on performance of main-chain-scission-type resist

Electron beam (EB) lithography is an indispensable technology for nanofabrication. We investigated the effects of the molecular weight distribution (molecular weight and dispersity) on the sensitivity and resolution of a main-chain-scission-type EB resist (ZEP520A; Zeon) by gel permeation chromatography and scanning electron microscopy. With the decrease in the half-pitch of line-and-space patterns, the dose range for fabricating the patterns became narrow. It was found that the dose range can be increased by making the molecular weight dispersity narrower, the molecular weight larger, and the dissolution rate lower. By increasing the dose range, the resolution of ZEP520A was improved.