Application of high-refractive index fluid to KrF-immersion lithography

Abstract

This paper describes the material characteristics for KrF-immersion lithography with a high refractive index fluid. We have obtained promising results in soaking experiments involving KrF lithography without topcoat film. Although water is currently used as the immersion fluid in 193nm lithography, providing suitable refractive index (n=1.44@193nm and n=1.37@248nm) and transmittance (>99%/mm), it is found to have leaching issues when used with KrF resist. On the other hand, our high refractive index fluid (JSR-HIL-001), which was developed for ArF immersion purposes, satisfies the following requirements: HIL-001 has indicated promising characteristics as a 248nm-immmersion fluid. The refractive index is 1.54@248nm and the transmittance is >99%/mm. In this paper the physical and chemical properties of HIL-001 for KrF-immersion fluid application are discussed in detail.