A comparative study for mask defect tolerance on phase and transmission for dry and immersion 193-nm lithography

Abstract

193nm immersion lithography has successfully enabled numerical aperture (NA) greater than 1.0 which allows rooms for improvement in resolution as well as depth of focus. In this study, critical dimension (CD) and depth of focus (DOF) performance for the 45nm technology node for dry and immersion lithography is compared using commercial available simulation tool. The study is based on one dimensional line and space pattern with pitch vary from 150 to 500nm. The effects of mask transmission and phase angle change on CD through pitch performance and DOF are also presented in this paper. Increase in mask transmission will result in increase of CD through pitch and reduction of DOF. When phase angle for the phase shift mask is less than 180 degree, CD through pitch and DOF drop. Finally, mask defects caused by haze on several locations which include MoSi lines, line edges, and space between line ends are simulated. The influence of these defects on CD and the potential line end bridging problem is presented.