Improving Thickness Uniformity of Amorphous Oxide Films Deposited on Large Substrates by Optical Flux Mapping

Abstract

In this study, three amorphous oxide thin films are prepared by an electron beam evaporation combined with ion-assisted deposition technique. With the aid of optical flux mapping method, thin film thickness distribution with good uniformity can be obtained by appropriate coating masks. Three metal oxide single-layer thin films are SiO2, Ta2O5 and Nb2O5, respectively. These thin films were deposited on a substrate holder with a radius of 275 mm that was divided into five different segments. Based on the optical flux mapping method, we can effectively simulate the geometric dimensions of the coating mask and obtain the width of the coating mask at different segments. If the film thickness uniformity is a function of masking area and center angle, it is necessary to determine the thickness distribution of the different segments and use a surface profiler to accurately measure the film thickness. We analyzed the thickness uniformity of three oxide films deposited at five different segments. The experimental measurement results show that the deviation of thickness uniformity is 0.38% for SiO2, 0.36% for Ta2O5, and 0.15% for Nb2O5 thin films, respectively.