Transient Swelling During Development of Poly(methyl methacrylate) Resist

For the realization of further miniaturization at scale of 10 nm and below in semiconductor devices, it is essential to understand the dissolution kinetics of resist films in developer. In this study, the change in molecular weight and dissolution kinetics induced by ionizing radiation in poly(methyl methacrylate) (PMMA) resist films were studied using a quartz crystal microbalance method and gel permeation chromatography. The weight-averaged molecular weight Mw was changed from 50000 to 996000. Three types of developers (o-xylene and 1:3 and 1:7 mixing solutions of methyl isobutyl ketone and isopropanol) were examined. The kinetics during the development of PMMA films was classified into three patterns. In low Mw region, only dissolution was observed. In middle Mw region, both swelling and dissolution were observed. In high Mw region, only swelling was observed. The boundaries between regions were dependent of the developer and independent of the initial molecular weight of PMMA.