The analyses on the surface properties of the annealed-diamond membrane

Polycrystalline diamond films were deposited using methane/hydrogen gas mixture on silicon substrates by a microwave plasma chemical vapor deposition (MPCVD) system. From X-ray photoelectron spectroscopy (XPS) analysis, the oxygen and the C signals were observed for the as-deposited diamond film. The oxygen signal was due to physiosorbed water or weakly bound oxygen species. After the 800 °C annealing process, the SiSi (99.8 eV), SiO (102.8 eV), SiOx (104.8 eV) and the CO (286.5 eV) bonds appeared for the surface of the diamond film. Moreover, it was shown that the film quality was improved by the 800 °C annealing process. However, it was found that the oxygen signal decreased and the silicon and siliconoxide bonds almost disappeared for the top surface of the annealed-diamond membrane. It was suggested the oxidized dangling bonds and the silicon components on diamond crystallite surfaces were etched away partly by back-etching process. Furthermore, from Auger electron spectroscopy (AES) analyses, the oxygen and the silicon signals were approximately estimated to be more than 1100 Å from the bottom surface of annealed-diamond membrane. This indicated that the non-diamond components (included the SiC, SiO2 and amorphous carbon, etc.) in the diamond/silicon interface might be thermally diffused through the grain boundaries to the top surface of the annealed-diamond membrane. These findings may be influential in the development on the characteristic of diamond electrical devices in the future.