Enhancement of diamond nucleation by applying substrate bias in ECR plasma chemical vapour deposition Original Research Article

Uniform diamond nucleation was achieved on a Si substrate over a large area using low pressure Electron Cyclotron Resonance microwave plasma chemical vapour deposition (CVD). Diamond nucleation density as high as 109 cm−2 was obtained using a CH4He gas mixture when the substrate was positively biased with respect to the grounded chamber wall. Radical densities higher than those with the CH4H2 gas mixture were obtained using the CH4He 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.