Combinatorial approach for the synthesis of terpolymers and their novel application as very-high-contrast resists for x-ray nanolithography

Novel resist systems for x-ray lithography, specifically optimized in terms of contrast enhancement are described. Based on terpolymers of methyl methacrylate (MMA)-tert-butylacrylate-polyhedral oligosilsesquioxanes (POSS) synthesized by solution polymerization, these systems were optimized by a combinatorial approach. It is shown that the mass ratio of $\mathrm{MMA/POSS}\text{=85.7/14.3}$ leads to maximum contrast (23.5) without sacrificing the sensitivity (1350 mJ/cm²) which remains comparable to that of standard PMMA. Such major contrast enhancement shows that the above organic/inorganic nanocomposites are promising candidates for sub-100 nm lithography.