Feasibility study of immersion system using high-index materials

In this paper, we discuss the feasibility of ArF immersion system using high-index materials. For the next generation of lithography, we focus on ArF immersion system using high-index materials. It is possible to increase the NA up to 1.45 using a high-index fluid (HIF) whose refractive index is about 1.65 as an immersion fluid. HIF materials have some advantages as higher transparency and lower evaporation heat compared with water. On the other hand, HIF immersion system has some issues that are not involved with water immersion system. The stability of HIF transparency easily degraded by dissolved oxygen or laser irradiation.