Investigation on Applicability of Chromium Based Materials to Attenuated Phase shift Mask for DUV Exposure

Abstract

A simple method of optical constant evaluation is employed to measure refractive index (n) and absorption coefficient (k) of chromium oxide thin films deposited on transparent substrate in deep ultraviolet range. The validity of the method is verified by comparison with n. k values calculated from transmittance and phase shift measurement. The calculated n, k values of chromium oxide film were 3.3 and 0.64 at 193 nrn, respectively. It was found that there existed optimum film thickness in the range of 45-55 nm for DUV attenuated phase shift at 193 nm. Moreover the film quality has been improved to yield smooth and uniform film surface.