Evolution as applied to optical lithography

The recent advancement of water immersion technology into lithography for 193nm wavelengths has allowed the numerical aperture (NA) of lithographic lenses to exceed 1.0 or a hyper-NA region. This allows resolution limits to extend to the 45nm node and beyond with NA>1.35. At these extreme NAs, the imaging within the photoresist is accomplished by not only using water immersion but also using polarized light lithography. This paper will show how the advances in current state-of-the-art in immersion, hyper-NA lithography have been preceded by extraordinary evolutionary behavior in lenses and imaging. We show the latest results and discuss the various phenomena that may arise using these systems show possible evolution paths in immersion lithography. We discuss and analyze the various issues with Hyper-NA technology that may force a paradigm change from single exposure imaging to multiple patterning techniques. In addition, we show that the future of optical lithography is likely to go well beyond the 30nm regime using advancements in 193nm double-patterning technology and/or the use of extreme ultra-violet (EUV) optical systems.