6.7nm 리소그래피용 브래그 반사형 거울과 흡수체 물질 연구

Abstract

Beyond extreme ultraviolet lithography (BEUVL) is considered to be a future patterning technology using light source with wavelength of 6.7 nm. However, it is difficult to optimize the material system for BEUV mask consisting of reflector and absorber design with an optimized multilayer mirror and absorber layer of the reflective mask. In this study, we propose a lanthanum nitride/boron (LaN-/B) Bragg reflector for 6.7nm through optical simulation. Instead of BEUV absorber, we propose 6% attenuated phase shifting absorber stack to utilize 180 degrees phase shift effect at the edge of pattern. For the absorber stack, we used tantalum nitride (TaN)/ palladium (Pd) and tantalum nitride (TaN)/ ruthenium (Ru). As a result, the BEUV mask with optimized reflector and attenuated phase shifting absorber is expected to exhibit a better imaging performance (i.e., higher normalized image log slope and reduced mask shadowing effect) under 6.7nm illumination compared to the conventional binary intensity mask.