A study of the interfacial microstructure and composition of CVD diamond films — effect of neon

Abstract

High quality and less defective diamond films grown by microwave plasma chemical vapor deposition (CVD) on silicon were prepared and characterized by transmission electron microscopy (TEM), X-ray diffraction, Auger electron spectroscopy (AES) and Raman spectroscopy. Both plan-view and cross-sectional TEM specimens were made from diamond films deposited in ethane/neon/hydrogen plasma mixtures. It is found that the addition of neon can change the surface morphology of the diamond film from triangular {111} to square {100} facets. The results of TEM, electron energy loss spectroscopy (EELS) and AES indicate that a high quality of diamond film can be achieved through an ionization process of neon in methane/hydrogen plasma. The EELS and energy dispersive spectrometer, which in-situ combined with TEM equipment, were used to analyze the chemistry of interfacial layer. The diamond films prepared in this study were frequently grown on an amorphous carbon layer which initially formed on the surface of silicon substrate. The interfacial layers may be strongly dependent on substrate pretreatments. For instance, the diamond nucleation rate could be enhanced by modifying the surface of the substrate material using a process that ultrasonically stimulated cavitation-erosion in an aqueous suspension of diamond dusts. The diamond crystallites growing on this surface were of a much more uniform size than was achieved after the more conventional lapping process.