Applicaton of blends and side chain Si-O copolymers as high-etch-resistant sub-100-nm e-beam resists

Abstract

Recently, there is significant interest in using chemically amplified (CA) resists for electron beam (E-Beam) applications including mask making, direct write, and projection printing. CA resists provide superior lithographic performance in comparison to traditional non CA E-beam resists in particular high contrast, resolution, and sensitivity. Due to the electron scattering effect and the image collapse problem, thinner imaging layer is desirable. Sufficient etch selectivity is needed to compensate reduced resist thickness. Therefore, there is a need to have a high etch resistant resist system which can survive Cr etch (Cl2/O2RIE etchant) process in mask making. For device making, the thin film bilayer approach needs a resist that can withstand O2 etch for image transfer to the underlayer. We have found Si-O containing polymer has the etch characteristics for both applications. In the first approach, using a blend of KRS-XE and silsesquioxane polymer, we have been able to resolve resist images down to 50nm with etch rate 20% slower than conventional novolak I- line resist systems. In the second approach, we have investigated the copolymer of vinyl phenol and acrylate siloxy silane systems. Superior litho performance and etch properties have been observed. In this presentation, we will discuss the chemistry, the miscibility in blends, etch characteristics and lithographic performance of these resist systems.