Imaging SIMS for the investigation of substrate surfaces for CVD diamond deposition

Abstract

The influence of substrate surface preparation on diamond nucleation is a major topic in the investigation of CVD-diamond deposition. The substrate, polishing material, its grain size, and the resulting surface roughness all influence diamond nucleation. Diamond can nucleate at scratches or residues of the polishing process which are providing nucleation sites. In this paper the surface of molybdenum and substrates polished with SiC and diamond powder was studied by imaging (2- and 3-dimensional) secondary ion mass spectrometry. The distribution and grain size of polishing residues (SiC, diamond) were determined and the reaction of diamond with the substrate during heating to deposition temperature was investigated. In this case a laterally inhomogeneous system of carbon containing species had to be characterized. Therefore compound-specific secondary ion mass spectrometry had to be performed. The results suggested that diamond residues on molybdenum substrates are partly dissolved during the heat treatment. The measurements indicate that a fraction of the diamond residues is still present after heat treatment and can provide nucleation sites for diamond deposition.