Improvement of Pad Life in Mirror Polishing for GaAs Wafers

Abstract

GaAs wafers have contributed greatly to improve the performance of light-receiving and light-emitting devices. For such applications, a very low level of roughness, of the order of 0.1nmRa, is required on GaAs wafers. If a polishing pad is used for a long time, the polishing rate decreases and the roughness on the wafer increases with increase of polishing time. In this study, the surface morphology of the polishing pad was focused as a dominant factor affecting the polishing rate, and, using an image processing technique, a quantitative approach was tried based on an optical microscope image. For the purpose of increasing the lifetime of polishing pads, a further study was made in which the polishing resistance, which correlates strongly with the polishing rate, was monitored.