| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Monday Sessions |
| Session PS+SE-MoA |
| Session: | Advanced FEOL / Gate Etching II |
| Presenter: | Takuji Uesugi, Tohoku University, Japan |
| Authors: | T. Uesugi, Tohoku University, Japan A. Wada, Tohoku University, Japan S. Maeda, Mitsubishi Rayon, Japan K. Kato, Mitsubishi Rayon, Japan A. Yasuda, Mitsubishi Rayon, Japan S. Sakuma, Mitsubishi Rayon, Japan S. Samukawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
ArF excimer laser (193nm) lithography technique is widely used in the fabrication of sub-50-nm devices. During plasma etching processes, however, the activated species radiated from plasma, such as ions, radicals, and photons, cause damages to ArF photoresist, resulting in low etching resistance and formation of line-edge roughness (LER). To solve these issues, we investigated the interaction between irradiated species from plasma and polymer structure of ArF photoresist. In our previous study, we found that improvement of stability of lactone group in side chain of ArF photoresist realized decrease in etching rate and reduction of the surface roughness of ArF photoresist.
In this study, to further improve the etching resistance and the surface roughness of ArF photoresist, we proposed a new polymer structure of ArF photoresist. Our newly developed ArF photoresist structure has acrylate group in main chain polymer structure, while usual ArF photoresist has methacrylate group in main chain polymer structure. We prepared silicon wafers coated by ArF photoresists with methacrylate group and acrylate group and etched them using chlorine plasma. As a result, these two types of photoresists had almost same etching rates. This result suggests that main chain structure of ArF photoresist does not affect its etching rate. On the other hands, the surface roughness of acrylate type photoresist after etching was drastically reduced in comparison with that of methacrylate type photoresist. It is considered to be due to stronger bonding energy of acrylate group than methacrylate group. From this result, it is concluded that the acrylate type ArF photoresist structure is very effective to suppress the roughness formation in ArF photoresist.