Correction of thickness uniformity of meter-scale Ag film

Abstract

Meter-scale optical films have become core components in large-size optical systems. Improving film thickness uniformity is a crucial issue to ensure optical properties. Ag films are commonly used as high-reflection mirrors for optical systems. Here a meter-scale magnetron sputtering equipment has been independently developed for coating Ag films. Two strategies were performed to correct the film thickness uniformity in the horizontal direction and vertical directions respectively. Specifically, the film thickness uniformity at the horizontal position was guaranteed by scanning the target parallel to the horizontal direction. Meanwhile, a mask was designed to optimize vertical film thickness uniformity. The film thickness, fitted by X-ray reflectometry (XRR), non-uniformity is less than 3% both in the 1800 mm range of the horizontal direction and the 1100 mm range of the vertical direction. This study has brought new insight into the development of meter-scale thin film optics.