GROWTH OF DIAMOND FILMS ON SI(100) WITH AND WITHOUT BORON-NITRIDE BUFFER LAYER

Diamond films were grown on Si(100) and boron nitride deposited Si(100) substrates using hot filament chemical vapor deposition (HFCVD) technique. Microstructure and morphology of diamond films have been investigated systematically as a function of CH4 and H-2 ratio and the ambient pressure. The deposited films were characterized by employing techniques such as scanning electron microscopy (SEM) and laser Raman spectroscopy. The average size and growth rate of diamond particles were found to increase with the CH4 to H-2 ratio and decrease with the ambient pressure. Maximum growth rate of synthetic diamond deposited on Si(100) was found to be approximately 3.5-mu-m/hr for the film deposited at 20 Torr with CH4:H-2 approximately 1.5:100 (substrate temperature approximately 850-degrees-C). In most of these depositions, the morphology of the diamond crystals was cubic with significant secondary nucleation at higher methane concentrations and ambient pressure. The diamond film deposited on Si(100) with BN buffer layer shows an improvement in growth rate and the coverage, and the secondary nucleation was found to be substantially reduced, resulting in relatively smooth morphology. MicroRaman investigations show less amorphous graphite formation and better structural quality of diamond film than the one deposited without the BN buffer layer.