Extending 1.35 NA immersion lithography down to 1x nm production nodes

Mainstream high-end lithography is currently focusing on 32 nm node and 22 nm node where 1.35 NA immersion technology is well established for the most critical layers. Double-patterning and spacer-patterning techniques have been developed and are being widely used to print the most critical layers. Further down the lithography roadmap we see 1x nm nodes coming where EUV lithography will take over critical layers from immersion. In order to enable a smooth industry-wide transition towards EUV, 1.35 NA immersion technology will continue to play a critical role in manufacturing front end layers in the coming years. Using immersion technology beyond the 22 nm node, we expect an increase in the use of double and even quadruple patterning technology for the critical layers. This demands tighter control of especially overlay and focus performance on the 1.35 NA immersion tools. Also fully flexible illumination and wave front control will be needed to optimize the contrast for these low k1 applications. In this paper we present the state-of-the-art system performance of today's 1.35 NA ArF immersion tool production workhorse, the TWINSCAN NXT:1950i. Furthermore we show the required scanner improvements on imaging, overlay and cost of ownership to enable device shrink below the 20 nm node in 2013 using immersion technology.