CrO_xF_y as a material for attenuated phase-shift masks in ArF lithography

摘要

We investigated the durability of CrO_xF_y film, which is used as a shifter for attenuated phase-shift masks (Att-PSMs), under ArF excimer laser irradiation. The phase shift of an as-deposited film decreased and the transmittance increased due to the disappearance of interfaces, which was caused by the migration of atoms. To improve durability, the sample was annealed at 300 deg C to remove the interfaces, and the surface was etched to recover the decreased transmittance caused by the annealing. As a result, the lifetime became 1.5 years, which is sufficient for practical devices. The depth-of-focus of an ArF photoresist was 1.2 mu m for a 0.13 mu m line-and-space pattern and 0.5 mu m for a 0.13 mu m isolated contact-hole pattern when Att-PSMs made from CrO_xF_y film were used.