Epitaxial Growth of Diamond on Chemically Modified Surface of Foreign Substrates

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The formation of large-area single-crystal films is a goal of CVD diamond research because of their great potential in microelectronic device technology. In the present study, microwave plasma chemical vapor deposition (MPCVD) was adopted and highlyorientated diamond film was formed by treating the substrate surface by various methods.First, the effect of scratching with fine powders such as diamond, c-BN,alumina and metal borides on diamond deposition was systematically examined. The population density of diamond particles formed on the scratched Si (100) face was greatly increased, but a polycrystalline film was formed in all cases. Heteroepitaxial nucleation and growth of an orientated diamond film were confirmed on the (100) and (111) planes of c-BN single crystal. However, the formation of c-BN single-crystal film was not realized yet.On the other hand, a highly orientated diamond film was grown on the (100) Si substrate by a bias-enhanced MPCVD.The Si surface carburized under optimum conditions showed a "Mesh Structure" on the nanometer scale. The formation of this structure was essential for the nucleation of (100) orientated diamond particles. The growth of randomly orientated diamond particles was then suppressed by changing the reaction condition to that favorable for the (111) growth. At the final stage, CO_2 was mixed in the reactant system and a highly (100) orientated flat diamond film was obtained.