Temperature Dependence of Plasma Chemical Vaporization Machining of Silicon and Silicon Carbide

Abstract

Silicon carbide (SiC) is a promising semiconductor material for power devices. However, it is extremely hard and chemically stable; thus 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 because the radical density in atmospheric-pressure plasma is much higher than that in conventional low-pressure plasma. Although it was found that the machining characteristic of SiC by PCVM had stronger rf power dependence than that of Si, it has not been clear whether it is radical density dependence or temperature dependence. In this paper, the temperature dependences of the PCVM of Si and SiC are examined using pipe electrode apparatus. As a result, it is found that the removal rate of SiC has a much stronger temperature dependence than that of Si and that the surface roughness of the SiC Si face becomes worse as the etching temperature increases whereas that of the C face does not increase at etching temperatures of up to 360°C.