Past, current and future development in microlithography excimer lasers and EUV light sources

Abstract

Excimer laser lithography was developed in the 2nd half of 1980's by combinating the concepts of monochromatic projection optics and line-narrowed excimer lasers. Excimer laser has now been lithography used in industry for 15 years. During this period, KrF, ArF and F₂ excimer lasers, and the tequniques of immersion, double patterning are developed very rapidly. The power of the first KrF excimer laser power was only 1W, but the power of the latest ArF laser GT62A (developed in 2009) is 90W. On the other hand EUV lithography is mainly used below the 32nm node. We have already demonstrated the power of 69W at an intermediate focus using with an LPP-EUV source. A 400W EUV light source appears seems feasible. The history, current status, and future development in light sources for microlithography are described.