Decomposition analysis of molecular resists to further CD control

We have designed and synthesized molecular resist material, which has just only two part protecting groups in one molecule (Prot-Mad-2). The resist can resolve below 30 nm hp pattern. We analyzed decomposition reaction using Prot-Mad-2 at the un-exposed and exposed area quantitatively by taking advantage of its property of high purity and simple structure. From the HPLC results, it was found that main decomposition reaction was deprotection of Prot-Mad-2. The ratio of one part de-protected material (Deprot-1-prot-Mad-1) and fully de-protected material (Deprot-2) changed with exposure dose. It was found that exposure dose of surface roughness maximum coincided with the exposure dose where materials of two-part protection, one part de-protection and fully de-protection existed equally in the resist film. Furthermore, dissolution rates of Prot-Mad-2, Deprot-1-prot-Mad-1 and Deprot-2 were totally different. It is considered that surface roughness was generated by different dissolution rates in the presence of Prot-Mad-2, Deprot-1-prot-Mad-1 and Deprot-2. Our result suggests that reducing a variety of dissolution rates at exposed and un-exposed boundary is a key to improve line edge roughness (LER).