Hideki Yamane

Leading-edge adamantyl polymers designed for 193 nm lithography

There are some practical candidates for next generation lithography (NGL). However, many subjects are left behind and there is still no effective technique. One of those subjects is reduction of line edge roughness (LER)/line width roughness (LWR). As compared with 2-methyl-2-adamantyl methacrylate which is mostly used in 193nm lithography as acid cleavable monomer, it became clear that our new monomers were effective in reduction of LER/LWR by measuring surface roughness (Ra) with the analysis of atomic force microscopy (AFM). We found out that the monomers which have acetal as acid cleavable unit has high exposure sensitivity and effective in the reduction of Ra. Moreover, we tried to synthesize high refractive index polymer by introducing a sulfur atom that is another subject of NGL. By synthesizing some monomers, it became clear that the bond type of sulfur atom affects a refractive index greatly. It was also checked that a refractive index and transparency have a relation of a trade-off. The adamantyl acrylate monomers are mostly used in 193 nm lithography due to their high transparency and excellent contrast after the development. We have designed and synthesized various monomers based on adamantane moieties from 65nm node forward the 32 nm node. So, we think that its our duty to challenge from the design of a monomer to those subjects for NGL.