Polishing Characteristics of 4H-SiC Si-face and C-face by Plasma Chemical Vaporization Machining

摘要

Silicon carbide (SiC) is a promising semiconductor material for power devices. However, it is so hard and so chemically stable that there is no efficient method of machining it without causing damage to the machined surface. Plasma chemical vaporization machining (PCVM) is plasma etching in atmospheric-pressure plasma. PCVM has a high removal rate equivalent to those of conventional machining methods such as grinding and lapping, because the radical density in atmospheric-pressure plasma is much higher than that in normal low-pressure plasma. In this paper, the polishing characteristics of SiC by PCVM are described. As a result of machining, the surface roughnesses of both Si- and C-faces were improved under a relatively low-etch-rate (100-200 nm/min) condition. The C-face was also improved under a relatively high-etch-rate (approximately 10 μm/min) condition, and a very smooth surface (below 2 nm peak-to-valley in a 500-nm-square area) was achieved.