THE GROWTH OF DIAMOND IN MICROWAVE PLASMA UNDER LOW-PRESSURE

The synthesis of diamond particles in a low pressure plasma has been studied, with emphasis on the investigation of the substrate effect and the plasma conditions. It was found that a special pre-treatment of silicon substrate made it possible to form dense films, and a thickness of about 15 mu m could be reached by 20 h discharge. Unfortunately, however, the prepared films had poor adhesion. Observations by scanning electron microscope showed that the poor adhesion was due to the fact that the film consisted of large particles with a diameter of about 10 mu m, and each particle had contacted to the substrate only by a point, not by a face. In addition, the plasma diagnostics of optical and ultraviolet emission spectroscopy revealed that CH and H radicals have come to be criteria for the formation of diamonds, and the ratio of radicals drastically affected the characteristics of the deposits. Nucleation and growth mechanism are also discussed.