Towards all-dry lithography: Electron-beam patternable poly(glycidyl methacrylate) thin films from hot filament chemical vapor deposition

Chemical vapor deposition (CVD) of resist thin films is a dry processing alternative to the conventional spin casting of resists. However, the sensitivity and resolution of plasma CVD resists are limited due to the crosslinked structure in the deposited films. In this study, we demonstrated hot filament chemical vapor deposition (HFCVD) of poly(glycidyl methacrylate) (PGMA) thin films with improved sensitivity and resolution under electron-beam irradiation. We also demonstrated supercritical CO2 development of the HFCVD PGMA thin films, which indicates the potential for an “all-dry” lithographic process. The pendent epoxide groups were retained in the low-energy HFCVD process, and linear polymeric structure was achieved. The HFCVD PGMA films have an electron-beam sensitivity of 27μC∕cm2 using conventional development and an electron-beam sensitivity of 15μC∕cm2 using supercritical CO2 development. Decreasing film number-average molecular weight (Mn) decreases sensitivity but improves resolution by alleviating the swelling of small features. The PGMA film with Mn 4700g∕mol resolved 80nm features using conventional development and 300nm features using supercritical CO2 development.