Abstract
We have designed and developed a variety of hexafluoroalcohol (HFA) pendant methacrylate monomers and the corresponding imaging polymers for ArF lithography. It was found that HFA side chains are critical for "swelling free" dissolution properties for the polymers and resists. Through the incorporation of HFA functionalities, ArF resists can obtain linear dissolution properties commonly seen in 248nm ESCAP resists. These improved dissolution properties in turn significantly reduce PEB sensitivity of higher activation protecting group (e.g., methyladamantanyl) based ArF resists. We have also showed that the fluorine impact on etch rates can be modulated through the insertion of cyclic and aliphatic spacers between the main chain and the HFA functionalities. The key application space for HFA-methacrylate resists appears to be trench level lithography. It was also demonstrated that these HFA materials are compatible with immersion lithography and result in dramatically improved process windows for iso trench features, in addition to other lines/space features.
