Insolubilization mechanism of chemically amplified negative photoresists

Abstract

This article reports on the difference of chemical reactions of polyvinylphenol (PVP) and novolak resin as a base polymer with a melamine cross-linker. Measurements by gel permeation chromatography (GPC) and solubility testing using alkaline developer and acetone indicate that a cross-linking reaction is predominant for dissolution inhibition in the case of the resists comprising PVP (PVP-type resists), while protection of hydroxyl groups for the developer is predominant in the case of the resists comprising novolak resin (novolak-type resists). The dissolution characteristics show that the novolak-type resists have higher contrast than the PVP-type resists. As the concentration of the melamine cross-linker increases, the resolution of the PVP-type resist becomes higher, while that of the novolak-type resist becomes lower. Significant differences in chemical reactions and lithographic performances were found between PVP and novolak resin for chemically amplified negative photoresists.