Microwave and hot filament chemical vapour deposition of diamond multilayers on Si and WC–Co substrates

A serious problem in the use of chemical-vapour-deposited polycrystalline diamond coatings in electronics, optics as well as in cutting tools is the high surface roughness. In our work, microcrystalline and nanocrystalline diamond films with a thickness of 0.5–5 μm were deposited using microwave chemical vapour deposition (MW CVD), and with a thickness of 1–4 μm by hot filament chemical vapour deposition (HF CVD). For both deposition technologies, we investigated the effect of a negative bias upon the formation of microcrystalline and nanocrystalline diamond multilayers. In the cases of smooth Si and relief WC–Co substrate surfaces, the multilayers were found to have a “cauliflower” look. The structure and composition of deposited layers were checked by scanning electron microscopy and Raman spectroscopy.