Sublimation Mechanism for Polishing Silicon Carbide Wafers by Electron Beam

Abstract

At present, interest in silicon carbide is growing, as it has promising properties in some applications: high-temperature electronics, high-frequency power electronics and others. In this regard, it is necessary to produce high quality silicon carbide substrates from which device structures will be created. The proper quality is achieved through the operations, one of which is polishing. Currently, chemical-mechanical polishing method is widely used for this operation, which has some disadvantages: long processing time, high cost and low technical flexibility. A more promising technology for polishing SiC substrates may be electron-beam treatment, which leads to thermal modification of the silicon carbide surface and, as a sequence, to a reduction in roughness. In this paper, a heating model is discussed in relation to a possible polishing mechanism of silicon carbide during its electron-beam treatment, related to the sublimation of silicon formed by the thermal dissociation of SiC. The heating process of a model (rough) silicon carbide surface was modeled in COMSOL Multiphysics^® as a solution to the heat conduction problem. The model SiC surface is an array of straight pyramids. The simulation showed that as a result of electron beam heating, the tops of the pyramids are heated more strongly than their bases, which will lead to selective sublimation of silicon and reduction of roughness.