On the mechanisms of bias enhanced nucleation of diamond

The mechanisms of bias enhanced nucleation (BEN) of diamond on silicon substrates are investigated by means of electrical measurements, OES investigations, and macroscopic as well as local characterization of BEN films. Based on electrical investigations we propose that the reproducibility and homogeneity problems often found in BEN are caused by diamond coated surfaces in the vicinity of the substrate. We further show that tile nucleation enhancement does not rely on changes in gas phase chemistry but rather on direct bombardment of the surface by ions with a mean energy of about 15 to 20 eV. The influence of bias voltage, carbon concentration in the gas phase: and substrate temperature on the nucleation process is investigated. Finally, the Films obtained by BEN are investigated by FTIR and stress measurements. A nucleation sequence (SiC formation: deposition of a hydrocarbon film, formation of diamond and simultaneous development of stress) is established and compared with SEM images of the Films. The role of each step of the sequence is discussed in detail.