Abstract
Diamond has superior characteristics such as the highest thermal conductivity and dielectric breakdown field, and is expected to be a good candidate material for the next generation semiconductor device. On the other hand, the etching and the mechanical processing are much difficult because of chemical and physical stabilities of diamond. As the device materials must be polished without the crystallographic distortion beneath a polished substrate, the simplified planarization techniques accompanied with high surface quality is intensely required. The ultraviolet rays excited polishing of single crystal diamond substrates has been studied in our laboratory. The UV-polishing characteristics, such as higher polishing rate and superior final surface roughness, have been revealed in these many years. This work will interpret the UV-polishing mechanism to achieve a well-polished diamond substrate satisfied for the requirement of the semiconductor device materials. The effects of the ultraviolet irradiation and processing atmosphere on the polishing rate and surface integrities were carefully examined. The polishing mechanism was discussed using experimental results of the luminous phenomenon, CO gas concentration and TEM observation of abrasion powder. The polishing model based on these discussions was proposed, and high-grade diamond wafer was finally obtained by the UV-polishing under the polishing conditions decided by the proposed polishing model.
