MICROWAVE PLASMA CHARACTERISTICS DURING BIAS-ENHANCED NUCLEATION OF DIAMOND - AN OPTICAL-EMISSION SPECTROSCOPIC STUDY

A negative bias applied to a nondiamond substrate at the initiation of microwave plasma-enhanced chemical-vapor deposition of thin-film diam ond can lead to diamond nucleation, high crystalline density, and an i mproved level of crystallographic alignment. In this work, optical emi ssion spectroscopy has been used to study changes in the chemical spec ies within the. plasma that occur as a result the applied bias to a tu ngsten substrate. The ratio of C-2 to CH species detected changes cons iderably as does the atomic hydrogen intensity as the bias is applied. Both effects appear to be greatest near the substrate surface. The re sults are discussed in terms of possible origins for the bias-enhanced nucleation process. (C) 1996 American Institute of Physics.