Evaluation of quartz dry etching profile for the PSM lithography performance

The phase shift mask (PSM) is one of the most effective approaches to improve ArF lithography performance. Recently, the quartz dry etching technology plays an important role to fabricate the PSM, such as space bias type Alternating (Alt.) PSM and chrome-less phase lithography (CPLTM) mask. The quartz etching profiles seems to be affected the lithography performance. In this paper, preliminary, we evaluate the nominal influences of quartz profile by rigorous electromagnetic field simulation. Then influence of the quartz profile is investigated by measuring the real masks. In this experiment, we intentionally fabricate Alt. PSM and CPLTM masks with the tapered side-wall and deeper micro-trench. Lithography performances of the real masks are measured by the aerial image measurement system (AIMS fab193). We compare the result of AIMS with simulation. We investigate the AIMS measurement well corresponds to the simulation. Side-wall angle and corner rounding strongly affect the lithography performance. However, micro-trench doesn't affect a lot.