SURFACE CHARACTERISTICS OF THICK, FREE-STANDING DIAMOND FILM PREPARED BY CHEMICAL ETCHING AND RAPID THERMAL PROCESSING

Abstract

The surface characteristics and depth profile of free-standing polycrystalline diamond films chemically etched from silicon substrates have been studied using monochromatic X-ray photoelectron spectroscopy and Auger electron spectroscopy. Two different processes for isolating the diamond films from the silicon substrates have been performed. The isolated/annealed-diamond film was prepared by rapid thermal processing (RTP) of the diamond-on-silicon film at a temperature of 800°C before chemically etching the diamond film from the silicon substrate. The annealed/isolated film was prepared by first chemically etching the diamond film from the silicon substrate, and then subjecting the stand-alone film to RTP. The qualities of the film on the top faces were improved for both the isolated/annealed-diamond and annealed/isolated-diamond films as verified by Raman spectroscopy. XPS analysis revealed different oxidation characteristics on the top and bottom faces of the isolated/annealed-diamond and annealed/isolated-diamond films. Silicon was detected on the bottom surfaces. A higher silicon and oxygen intensity was observed on the isolated/annealed diamond films compared to the annealed/isolated films. This can be due to the facilitated thermal diffusion of silicon into the grain boundaries during the initial RTP step in the preparation of the isolated/annealed-diamond film.