The influence of the process parameters on bias-enhanced nucleation of diamond on silicon was studied. When low pressures (<15 Torr) and/or high bias voltages (more than 350 V d.c.) were used, no significant diamond nucleation was observed; in some cases diamond was found to be removed under these conditions. Low bias voltages (below - 150 V d.c.) had very little effect on diamond nucleation, and higher process pressures (> 25 Torr) resulted in poor diamond film uniformities. A well defined process zone was determined in which a short bias duration (<20 min) may be utilized to obtain enhanced diamond nucleation densities and improved diamond film uniformities. The process factors responsible for these optimum responses were a pressure of similar to 20 Torr and a bias voltage of similar to -320 V d.c. using a 5%CH4-H-2 gas mixture.