Extending single-exposure patterning towards 38-nm half-pitch using 1.35 NA immersion

Immersion lithography started to become the main workhorse for volume production of 45-nm devices, and while waiting for EUV lithography, immersion will continue to be the main technology for further shrinks. In a first step single exposure can be stretched towards the 0.25 k1 limit, after which various double patterning methods are lining up to print 32-nm and even 22-nm devices. The immersion exposure system plays a key role here, and continuous improvement steps are required to support tighter CD and overlay budgets. Additionally cost of ownership (COO) needs to be reduced and one important way to achieve this is to increase the wafer productivity. In this paper we discuss the design and performance of a new improved immersion exposure system XT:1950i. This system will extend immersion towards 38-nm half pitch resolution using a 1.35 NA lens and extreme off axis illumination (e.g. dipole). The system improvements result in better CDU, more accurate overlay towards 4-nm and higher wafer productivity towards 148- wph. Last but not least a next step in immersion technology is implemented. A novel immersion hood is introduced giving more robust low and stable defects performance.