IMAGING SIMS FOR THE INVESTIGATION OF SUBSTRATE SURFACES FOR CVD DIAMOND DEPOSITION

The influence of substrate surface preparation on diamond nucleation i s a major topic in the investigation of CVD-diamond deposition. The su bstrate, polishing material, its grain size, and the resulting surface roughness all influence diamond nucleation. Diamond can nucleate at s cratches or residues of the polishing process which are providing nucl eation sites. In this paper the surface of molybdenum and substrates p olished with SiC and diamond powder was studied by imaging (2- and 3-d imensional) secondary ion mass spectrometry. The distribution and grai n size of polishing residues (SiC, diamond) were determined and the re action of diamond with the substrate during heating to deposition temp erature was investigated. In this case a laterally inhomogeneous syste m of carbon containing species had to be characterized. Therefore comp ound-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 tr eatment and can provide nucleation sites for diamond deposition.