Ion energy distributions and their evolution during bias-enhanced nucleation of chemical vapor deposition of diamond

Ion beam mass spectrometry was used for in situ, real-time, mass-selective energy analysis of the incoming ions during bias-enhanced nucleation in mic rowave plasma chemical vapor deposition of diamond. H-y(+) and CxHy+ fluxes versus energy have been measured in the incubation period and after the on set of nucleation enhancement. Hydrocarbons with x = 2 are dominant among n o the ions that strike the surface, and species with low hydrogen content ( y = 3) are most abundant. At 200 V bias, in the incubation period, the ener gy distributions of the main hydrocarbon ions have a broad peak with a smal l high-energy tail. The average energies an between 50 and 70 eV. H+ shows a wide distribution between 10 and 150 eV. On lowering the bias to a value below which nucleation enhancement becomes negligible the average ion energ ies decrease to about 30-35 eV. After the sharp increase of the sample curr ent. which accompanies the onset of nucleation enhancement. the flux and av erage ion energies increase significantly. C2H2+ becomes the dominant speci es with average energy of about 100 eV. A considerable flux of H+ and H-3() ions reaches the surface with energy as high as 160-180 eV. (C) 2000 Else vier Science S.A. All rights reserved.