Development of a W/Si thin film for the single-layered attenuated phase-shifting mask for 248-nm lithography

A novel material system of W/Si film which consisted of W, Si and their oxides has been developed for the single-layered attenuated phase- shifter (SAttPS) for the KrF excimer laser lithography. The W/Si film was deposited on quartz substrate by an RF sputtering, using WSi2 as a target and Ar and O2 mixtures as sputtering gases. The W/Si film has been shown to have excellent properties for the SAttPS such as controllability of the optical transmittance, electric conductivity, chemical durability and adequate adhesion to quartz substrate, in the same way as the film for i-line lithography previously reported. As- deposited W/Si film with the thickness of 975 angstrom and the transmittance of 7.1% at 248 nm showed no changes in the refractive index and some changes in the extinction coefficient after the KrF excimer laser irradiation up to 200 kJ/cm2. Annealing at 350 degree(s)C for 60 min under atmospheric He environment, however, let to no degradation in the extinction coefficient after the laser irradiation. The annealed W/Si film is expected to be a promising material of the KrF SAttPS.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.