High index 193 nm immersion lithography: The beginning or the end of the road

Abstract

For several years, SEMATECH has invested significant effort into extending 193 nm immersion lithography by developing a set of high index materials. For high index immersion lithography (HIL) to enable 1.70NA imaging, a high index lens element with an absorbance < 0.005/cm, a fluid with an index of >= 1.80, and a resist with an index >1.9 are needed. This paper reviews the success or failure of various HIL components and presents the top final material prospects and properties in each category. Since this abstract was submitted, the industry has decided to cease any effort in HIL, not because of fundamental showstoppers but because of timing. This choice was made even though the only currently available technology the can enable 32 nm and 22 nm manufacturing is double patterning. This may represent a paradigm shift for the semiconductor industry and lithography. It may very well be that using lithography as the main driver for scaling is now past. Due to economic forces in the industry, opportunity costs will force performance scaling using alternative technology.