High transmittance attenuated phase shifting mask of chromium aluminum oxynitride

Abstract

In this study, high-transmittance attenuated Phase Shift Masks(HT -Att-PSMs) have been investigated to satisfy the requirements of 20±5% transmittance and 180° phase shift at the exposure wavelength of 193 nm for ArF laser (248 nm for KrF laser) and less than 40% transmittance at the inspection wavelength of 248 nm(365 nm for KrF laser). Chromium aluminum oxynitride has been studied as a new candidate material for HT -Att-PSM. At first, optimum conditions of composition and thickness were shown by n(refractive index)-k(extinction coefficient)-d(thickness) charts developed to simulate the optimum range of optical constant for HT -Att-PSM using the matrix method. Chromium aluminum oxynitride films were deposited by changing of variables such as target composition, gas flow rate, deposition power and deposition pressure to find optimum conditions to meet the simulated range. This study examined effects of processing variables on the optical properties of chromium aluminum oxynitride films and established optimum conditions of chromium aluminum oxynitride films for HT -Att-PSM.