Effect of off-axis geometry on the thickness profile of film produced by vacuum thermal evaporation

Abstract

A fundamental issue in physical vapor deposition techniques is the uneven thickness profiles of the produced films. In this work, off-axis substrate geometry was investigated to find possible source-substrate configurations that provide the best film uniformity. Substrate rotation and translation was modeled using coordinate system transformations. Thickness profiles and modulation values were then calculated as a function of substrate position and shape. It is observed that the thickness modulation is minimized when the substrate is translated along the plane symmetrical and central to the strip source. For substrates of varying degrees of rotation, the points of minimum modulation increase with distance from the source as the degree of rotation increases. Thickness profiles are more uniform in circular substrates compared to square substrates. Specific behavior of angled substrates under varying evaporation parameters and substrates undergoing dynamic rotation and/or translation can be further investigated.