The etching properties of silicon carbide (SiC) are of interest in two distinct technologies. First, its electrical properties make it a promising semiconductor for integrated circuit (IC) devices for high temperature operation. Second, its resistance to radiation damage and to attack by atomic hydrogen have prompted active consideration of SiC as a protective liner for plasma-facing components of fusion reactors. Therefore there is both chemical and nuclear engineering interest in this material. The objectives of the proposed research are to determine the conditions under which silicon carbide is etched by reactive gases (hydrogen, fluorine, and chlorine atoms) and to determine the mechanism of the surface reactions responsible for etching. Etching condition refer top the nature of the gaseous reactant, its pressure, the SiC temperature and the intensity and energy of energetic ions impinging on the reacting surface. This problem will be approached using a high-pressure (up to 1 Torr) rf plasma reactor and a low-pressure (up to 0.0001 Torr) molecular beam reactor. The problem is attacked at two levels. The first is a fundamental mechanistic study using the molecular beam-mass spectrometric method. The second is by plasma etching in a reactor representative of realistic integrated-circuit production. The molecular beam technique provides information ont he molecular nature of reaction products and their residence times on the surface. Such data can be use to elucidate the elementary reactions occurring on the surface and the kinetics of each of these steps. In order to take full advantage of the fundamental mechanistic information provided by the molecular beam method, it is necessary to relate these experiments to etching studies carried out at pressures normally used to fabricate ICs. This connection will be accomplished by performing etching studies in an rf glow-discharge reactor which is capable of both downstream atom etching and direct plasma etching. Comparison of etching results from these two discharge modes can provide insight into the role of the plasma in etch processes and will also link the mechanistic molecular beam results to etching under conditions of technological utility.
