Shuhei Yamaguchi

Properties of the novel de-protecting unit for next generation ArF resist polymer

Viewpoint of lithographic performance, the chemically amplified resist (CAR) is still promising candidates for the 32 nm node device manufacturing or below. However, CAR has an issue of low exposure latitude (EL) in the above node. To overcome the issue, it is important to control the acid diffusion at de-protecting process of the lithography system. We focused on a monomer unit that is able to control the acid diffusion during the post exposure bake (PEB) process. A novel secondary ester type methacrylate monomer was designed and synthesized as the unit that generates acid trapping ability according to the de-protecting reaction. The de-protecting reaction proceeded at general condition, and the acid trapping ability was confirmed by the model reaction in the solution. The unit must be useful as the adjusting unit of the acid diffusion. We also investigated the copolymers having this adjusting unit and the typical tertiary ester de-protecting unit for ArF resist main polymer. We will discuss the feature of the polymer including the de-protecting unit and its applications for next generation ArF chemically amplified resist.

Effects of the statistical fluctuation of PAG and quencher on LWR of ArF resists

In order to improve line width roughness (LWR) of chemically amplified resists (CARs) without trade-offs with other lithographic performances such as exposure latitude (EL) and sensitivity, we investigated effects of the spatial fluctuation of sensitivity on LWR of ArF resists. Compared a statistical model with experiments, it was clarified that LWR of ArF resists was caused by the fluctuation of sensitivity due to the fluctuation of the PAG and quencher concentration. Furthermore, we developed novel photoactive materials such as a transparent PAG and an nPAG-1Amine which were predicted to be useful for reducing the statistical fluctuation of sensitivity by the theoretical model. LWR was successfully improved using these photoactive materials. This study not only provided new insight into the root cause of LWR, but also proved efficacy of the theory-based material design.