金刚石薄膜负偏压形核的边缘效应

 在微波等离子体化学气相沉积装置中，研究了金刚石薄膜在Si (100)面上的负偏压形核行为，结果表明，偏压大小对金刚石的形核均匀性有显著影响，而甲烷浓度主要影响形核时间，对金刚石的最大核密度影响不大。在硅片尺寸小于钼支撑架时，形核行为存在明显的边缘效应，即在偏压值低于-150 V时，硅片边缘金刚石核密度急剧降低，远低于硅片中央；在甲烷浓度比较低时，硅片边缘核密度要高于中间。研究表明，造成这种现象的主要原因是硅片下的钼支撑架发射电子所致，过量的原子H对金刚石的形核是不利的。

Brim Effect of Negative Bias-Enhanced Nucleation of Diamond Film on Silicon Substrate

Diamond nucleation improved by negative bias-enhanced technology on Si(100) substrate has been investigated on a microwave plasma enhanced chemical vapor deposition(MPCVD) apparatus using a gas mixture of methane and hydrogen.The results show that the bias voltage has a significant effect on the uniformity of the nucleation density and the concentration of the methane mainly relevant to the nucleation time.There is an obvious brim effect of the nucleation when the size of the silicon substrate is less than that of the Mo substrate holder.The nucleation density of the side is higher than that of the center on the substrate when the bias voltage is lower than -150 V. The nucleation density of the side decrease significantly with the bias voltage when the bias voltage is lower than -150 V.There are nearly no nuclei on the side of silicon when the bias voltage is -200 V.This effect may be contributed to the electron emission of the diamond on Mo substrate holder.The concentration of the methane has little effect on the nucleation density at a fixed bias voltage. Increasing the methane concentration is useful for decreasing the nucleation time.