Enhancement of diamond nucleation by applying substrate bias in ECR plasma CVD

초록

Uniform diamond nucleation was achieved on the Si substrate over a large area using low pressure ECR microwave plasma CVD. Diamond nucleation density as high as 109cm-2 was obtained by using a CH4/He gas mixture when the substrate was positively biased with respect to the grounded chamber wall. Radical densities higher than those with the CH4 - H2 gas mixture were obtained using the CH4 - He gas mixture. A suitable positive bias voltage applied to the substrate with respect to the chamber enhances diamond nucleation. When a negative substrate bias voltage is applied, diamond nucleation is prohibited by high energy ion bombardment on the substrate. Also the dependence of diamond nucleation density on gas concentrations, substrate bias voltage, and microwave power was investigated.