Fine control of deposition film compositions using radio-frequency reactive sputtering with periodic gas additions

Thin films of titanium nitride are prepared on metallic substrates using rf reactive sputtering. A pure titanium target and argon plasma are used with reactive gas of nitrogen in the sputter. The pressure of Ar is 0.53 Pa, an d the input power 300 W. The reactive gas is periodically added to a consta nt plasma supporting Ar flow as a form of square waves, and this is called the modulation method. Wide atomic ratios of N to Ti, 0.3 to unity, are obt ained by changing the duty ratio or period, where the stoichiometric ratio of TiN is unity. The variation of the atomic ratio is slower than that of t he continuous nitrogen gas addition and this promises easy handling for pro ducing a film with a particular atomic ratio. Moreover, the deposition rate s are maintained within a factor of 30% decrease. These results indicate po ssible application to bulky material preparations such as functionally grad ient materials (FGMs) and FGM-like intermediate layers for composite materi als. (C) 1999 American Vacuum Society. [S0734-2101(99)00406-6].