MECHANISM OF DIAMOND FORMATION ON SUBSTRATES ABRADED WITH A MIXTURE OF DIAMOND AND METAL POWDERS

In this work we report a study of CVD diamond formation on silicon sub strates abraded with diamond, metal, and a mixture of diamond and meta l powders. It was found that the deposited diamond particles density ( DPD) obtained after abrasion with diamond powder can be enhanced by a few orders of magnitude by abrasion with a mixed metal/diamond slurry, whereas no enhancement was observed by use for surface abrasion a met al slurry alone. The residual diamond slurry density (RDSD) left on th e substrates by abrasion with diamond slurry was measured from AFM ima ges. It was observed that DPD followed by abrasion with pure diamond s lurry does not exceed 10% of RDSD, whereas the presence of some metal residues alongside with diamond debris, may increase this value almost to 100%. The enhancement in DPD was in the order: virgin approximate to(Cu, Fe or Ti) < Di < (Cu + Di) < (Fe + Di) < (Ti + Di). These effec ts are explained qualitatively as follows. It is suggested that metal residues influence the rates of CVD diamond growth through facilitatio n of conversion of non-sp(3)-bonded carbon species to the sp(3)-one ab ove the growing surface. This enhancement in sp(3)-bonded carbon surfa ce concentration at the initial stages of deposition (before a stable substrate is formed) prevents the smallest diamond residues from being completely etched by atomic hydrogen.