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Highly oriented diamond particles were deposited on the mirror-polished (100) silicon substrates in the belljar type microwave plasma deposition system. The diamond films were deposited by a three-step process consisting of carburization, bias-enhanced nucleation and growth. The bias-enhanced nucleation was performed under the deposition conditions such as 2-3% of methane concentration in hydrogen, 1333-2666 Pa of total pressure, the negative bias voltage below 200V and the substrate temperature of 1073 K. By adjusting the geometry of the substrate and substrate holder, very dense disc-shaped plasma was formed on the substrate when the bias voltage was below 200V. As characterized by transmission electron microscopy (TEM), almost perfectly oriented diamond particles were obtained only in this dense plasma. From the results of the optical emission spectra of disc-shaped dense plasma, it was found that the concentrations of atomic hydrogen and hydrocarbon radicals were increased with negative bias w)ltagc. As a result, it was suggested that the highly oriented diamonds were obtained by the combination of the high dose of hydrocarbon radicals and the increased hydrogen etching effects.

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Almost perfectly oriented heteroepitaxial diamond film was deposited on the (100)Si substrate by the carburization, bias-enhanced nucleation, and growth process in a dense plasma using a bell-jar-type microwave-plasma chemical vapor deposition (CVD) system with an ASTeX 1.5 kW magnetron plasma source. This dense plasma was a prerequisite for the perfect orientation and was not obtained simply by increasing microwave power, but was obtained by introducing a graphite block between the substrate and the substrate holder. The plasma was concentrated over the substrate especially at the four corners with a thickness of several millimeters.