Epitaxial Growth of Diamond on Chemically Modified Surface of Foreign Substrates

大面积单晶薄膜的形成是CVD金刚石研究的目标之一，因为它在微电子器件技术中具有巨大的潜力。本研究采用微波等离子体化学气相沉积(MPCVD)技术，通过不同的方法对衬底表面进行处理，获得了高取向的金刚石薄膜。首先，系统研究了金刚石、c-BN、氧化铝和金属硼化物等微粉的划痕对金刚石沉积的影响。划痕后的Si(100)表面形成的金刚石粒子密度大大增加，但在所有情况下都形成了多晶膜。在c-BN单晶的(100)和(111)面上证实了定向金刚石膜的异质外延成核和生长。另一方面，利用偏压增强型MPCVD在(100)Si衬底上生长了高度取向的金刚石薄膜，在最佳工艺条件下渗碳的Si表面呈现出纳米尺度的网状结构。这种结构的形成对(100)取向金刚石颗粒的形核是必不可少的。然后，通过改变反应条件以利于(111)面的生长，抑制了随机取向的金刚石颗粒的生长。最后，在反应物体系中掺入CO_2，得到高度(100)取向的扁平金刚石薄膜。

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.