DC-glow discharge as a key step for the bias-enhanced nucleation of diamond by the HF CVD method

A novel method for in situ substrate surface pretreatment for the enhancement of CVD diamond nucleation density on mirror polished Si(100) is reported. During the pretreatment, a dc-glow discharge between a grounded substrate and a positively biased electrode is generated using a CH4/H-2 gas mixture. No additional gas phase activation by a hot filament (HF) is carried out during this stage. For subsequent diamond deposition, the dc-glow discharge is switched off, and the standard HF CVD growth conditions are applied. This method is compared with a thermal-assisted (TA) de-glow discharge pretreatment, i.e. a generation of the dc-glow discharge concurrently with thermal activation of CH4/H-2 gas mixture by HF. It is observed that both pretreatment methods result in the formation of carbon-containing film which serves as a precursor for subsequent diamond growth. The development of the film as a function of the deposition time is found to be similar after dc-glow discharge with and without additional gas phase activation by HF. From our results, it is suggested that the key step in the bias-enhanced nucleation (BEN) is generation of a stable dc-glow discharge. The deposited films are characterized by Raman spectroscopy, and High Resolution Scanning Electron Microscopy (HR SEM). (C) 1998 Elsevier Science S.A.