Effects of CH4/H2 flow rate ratio, chuck bias and microwave power on the structural properties and particle
densities of diamond thin films deposited on Ti substrates in microwave plasma CVD were examined. High quality
diamond thin films were deposited on Ti substrates in 2~3 CH4 Vol.% conditions due to the preferential formation of sp3-
bonds and selective removal of sp2-bonds in the CH4/H2 mixtures, and the mechanism for the formation of diamond
particles on Ti was analysed. Diamond particle density increased with increasing negative chuck bias to Ti substrate due to
bias-enhanced nucleation of diamond and the threshold voltage was found at ~.50 V. With increasing microwave power the
evolution from micro-crystalline graphite layer to diamond layer was observed.