Measurement of ion energy distributions in the bias enhanced nucleation ofchemical vapor deposited diamond

In situ, real-time, mass selective energy analysis of the incoming ions has been carried out during bias enhanced nucleation for diamond chemical vapo r deposition. The dependence of ion energies and fluxes as a function of th e bias voltage and CH4 concentration was measured. The main ionic species t hat strike the substrate surface during bias enhanced nucleation have energ ies between 50 and 80 eV and are characterized by a low H content. When the bias is lowered to the value at which nucleation enhancement becomes negli gible (100 V in our system), ions have an energy of about 30-40 eV, which i s the critical value for penetrating below the surface of a hydrogenated am orphous carbon layer. These findings strongly support the subplantation mod el of bias enhanced nucleation. (C) 1999 American Institute of Physics. [S0 021-8979(99)00522-8].