Super-resolution enhancement method with phase-shifting mask available for random patterns

Abstract

We propose new two phase shifting masks: centerline phase-shifting mask (CL-PSM) and outline phase-shifting mask (OL-PSM). CL-PSM enhances the DOF of line patterns more than alternating phase-shifting masks. OL-PSM drastically improves the resolution of the contact pattern compared with attenuated phase-shifting masks. Both CL-PSM and OL-PSM are classified as strong resolution enhancement technologies. Furthermore, they can be applied to random logic patterns without multiple exposures. They will allow us to make sub-65-nm node logic LSIs with ArF lithography, and will also be useful for VUV lithography.