Progress in EUV Resist Development

Abstract

For next generation lithography, several technologies have been proposed to achieve the ultra-fine patterning required for the 32nm node and beyond. Extreme ultraviolet (EUV) lithography is one of the promising candidates but faces several critical issues with resist performance. Line width roughness (LWR) is regarded as one of the major issues to be improved to ensure device reliability and performance. One direction for decreasing LWR is to reformulate current polymer based resist. The other direction is to apply new materials such as molecular glass and polymer bound photoacid generators (PAG). In this study, the performance of EUV resist based on more traditional polymers as well as molecular glass have been investigated. In the case of polymer-based resist, it was found that resist based on partially protected polyhydroxystyrene with an acid labile group had the potential to resolve 26nm line and space patterns by using PAG with short acid diffusion length. Further optimization of not only resist formulation, but also process condition is necessary to improve performance. It was found that the resist based on new molecular glass, Noria which was partially protected with an acid labile group resolved 28nm line and space patterns. The optimization of resist formulation using protected Noira is on-going.