Surface analysis of boron-doped polycrystalline diamond films deposited by a microwave plasma chemical vapor deposition system

Abstract

Polycrystalline diamond films were deposited on silicon substrates by a microwave plasma chemical vapor deposition (MPCVD) system. Raman, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used for the analyses of the diamond films. Prior to deposition the silicon substrate was seeded, by photoresist, with 0.1 μm (micron) diamond powder. Using this pretreatment technique results in an oxygen-rich phase on the substrate surface, oxygen is easily incorporated into diamond grain boundaries during the synthesis of the diamond films. The oxygenated phenomenon also increased after the diamond films were exposed to air for a period of time. Experiments showed that the diamond crystallite surfaces and the diamond grain boundaries are the two major sources causing the adsorption of oxygen on the surface layers of the diamond films. At room temperature, the reaction between the diamond grain boundaries and air is fast and oxidized dangling bonds are hard to remove. The oxidized dangling bonds are gradually formed on the diamond crystallite surfaces and are easily removed. The quality of the diamond film degraded after the boron ion implantation. The oxygenated phenomenon increased considerably after the boron-doped diamond films were annealed at 800°C and the quality of the boron-doped diamond films degraded appreciably. The oxygenation layer which is formed on the surface of the annealed boron-doped diamond film is difficult to be etched away.