32 nm Half pitch formation with high numerical aperture single exposure

Abstract

According to the ITRS roadmap, DRAM half pitch (hp) will reach to 32 and 20 nm in 2012 and 2017 respectively. However, it is difficult to make sub-40 nm node by single exposure technology with currently available 1.35 numerical aperture (NA) ArF immersion lithography. Although it is expected to enable 32 nm hp with either double patterning technology or extreme ultra-violet lithography, there are many problems to be solved with cost reduction. Thus, the study of high-index fluid immersion technology should be pursued simultaneously. ArF water immersion systems with 1.35 NA have already introduced for 40 nm hp production. ArF immersion lithography using high-index materials is being researched for the next generation lithography. Currently, many studies are undergoing in order to increase NA with higher index fluid and lens in immersion technology. The combination of LuAG (n=2.14) and third-generation fluid could be used to make 1.55 NA. This combination with 0.25 k1, 32 nm hp can be obtained by single exposure technology. In order to check the realization of this process and to check the possible process hurdles for this high NA single exposure technology, 32 nm hp with 1:1 line and space patterning is tried. Various illumination conditions are tried to make 1:1 32 nm hp and the exposure and develop conditions are varied to check whether this single exposure can give processible window. As a result, 32 nm hp can be obtained by single exposure technology with 1.55 NA. ©2009 SPIE.