Comparative study of chromeless and attenuated phase shift mask for 0.3-k1 ArF lithography of DRAM

The purpose of this paper is to do the direct comparison of between the novel chrome-less phase shift mask (CLM), which is suggest by Chen et. al. recently, and attenuated phase shift mask which has been in the main stream of DRAM lithography. Our study is focused on the question of whether the CLM technology has a potential advantages compared with attenuated PSM, so as to substitute the position of it in 0.3 k1 lithography era of DRAM. Firstly, some basic characteristics of both masks are studied, that is intensity distribution of diffraction orders and optical proximity effect etc. And then mask layouts are optimized through the resist patterning simulation for various critical layers of DRAM with CLM and attenuated PSM, respectively. Resolution performances such as exposure latitude and DOF margin and mask error enhancing factor etc. are compared through the simulations and experiments. In addition, it is also studied in the point of mask manufacturing of CLM such as phase control issues, defect printability, mask polarity, and so forth.