Hot target sputtering: A new way for high-rate deposition of stoichiometric ceramic films

Titanium nitride or dioxide coatings have been reactively sputter-deposited under unstable sputtering conditions using a cold or hot target. We have shown that increasing the sputtered titanium flux in cold target sputtering (CTS), by increasing either the discharge current or the discharge voltage, increases the metalloid content in the coating deposited when the target operates at the higher reactive gas flow rate of the elemental sputtering mode. Using a hot target allows a perfect stabilisation of the process in the presence of an argon–nitrogen discharge, whereas only a slight stabilisation occurs when the sputtering stage takes place in argon–oxygen mixtures. It is shown that the stabilisation effect of hot target sputtering (HTS) is due to the strong increase of reactive species diffusion into the bulk target, which is more pronounced with nitrogen than with oxygen, as soon as the target heats up to the α-Ti→β-Ti transformation temperature.