ION ENERGY DISTRIBUTIONS IN THE BIAS ENHANCED NUCLEATION OF CVD DIAMOND

摘要

In situ ion beam mass spectrometry was used to measure ion fluxes and ion energy distributions in the vicinity of the substrate surface, during the bias enhanced nucleation process of MW PECVD of diamond. The dependence of the ion energy distributions as well as the fluxes on changes in the bias voltage and the methane content of the feed gas has been studied under typical bias enhanced nucleation (BEN) conditions, varying the bias voltage and the methane concentration. Our findings support models of BEN that are based on the subplantation of ions into the surface layer. These results also imply that beside the energy distribution, chemical reactivity too may play an important role in the nucleation process. Mass selective energy distribution measure-merits have also been performed before and after the onset of nucleation. It was found that both ion fluxes and ion energies increase significantly as nuclei are formed on the surface. These results may explain the loss of oriented nucleation in the late phase of the BEN process.