NUCLEATION AND GROWTH OF DIAMOND IN A MICROWAVE PLASMA ON SUBSTRATE PRETREATED WITH NONOXIDE CERAMIC PARTICLES

Changes in morphology and nucleation density in an early growth stage of diamond formation on a substrate surface are investigated by high-resolution scanning electron microscopy. The substrate, a p-type (100) silicon wafer, is abraded with various ceramic particles including borides, carbides, nitrides or silicides suspended in acetone by an ultrasonic method. Before and after deposition of diamond for 1 h by the microwave plasma-enhanced CVD technique, exactly the same points on the substrate are observed. The role of the abrasion is found to implant fine particles of abrasives on the substrate surface, and the implanted particles act as nucleation sites for diamond from the vapor phase. Boride particles, especially MoB, LaB6 and TaB2, are effective, suggesting the commitment of boron compounds in the CVD reaction.