Optical properties of Si-O-N-F films as a phase shift mask material for 157 nm optical lithography

Abstract

Si-O-N-F has been studied as a new candidate material for a high transmittance attenuated phase shift mask (HT-Att-PSM). The requirements of HT-Att-PSM are 20 +/- 5% transmittance and 180degrees phase shift at the exposure wavelength (157 nm) and less than 40% transmittance at the inspection wavelength (193 nm). Si-O-N-F films were deposited with varying process parameters, such as gas flow rate and deposition time, to find optimum conditions to meet the above requirements. In this study, the effects of process parameters on the optical properties and the degradation of Si-O-N-F films were examined. To satisfy the requirements of HT-Att-PSM, a new mask structure was suggested and analyzed. (C) 2003 Published by Elsevier Science B.V.