Reactive magnetron sputtering of titanium and its oxides

Abstract
Ti and TiOx films have been made by vacuum and reactive evaporation, respectively, using electron beam heating. However, magnetron sputtering of Ti and its oxides is of interest because of the system’s simplicity and possible applications in the semiconductor and metallurgical industries. An investigation has been made into the discharge and deposition characteristics of a planar magnetron. Using a water-cooled Ti target operated at up to 1200 W in Ar and Ar+O2 mixtures, the results obtained show that V/I curves fall into two groups. Thus a high operating voltage is needed at either a low input power or high O2-gas content which is the characteristic mode for high oxidized film growth. High power inputs (even in the presence of a 25% O2 content) or low O2 content resulted in a low operating voltage and the growth of substantially metallic films. The effects of O2 on the discharge characteristic are briefly considered. Deposition rate curves as a function of power input for different gas mixtures are presented for these two growth modes. Also ’’phase diagrams’’ for both dc and rf power inputs are given which roughly classify the conditions needed to produce deposits tending to the metallic or oxide states. The film growth conditions for rf and dc magnetrons were similar but generally with rf a higher power input was needed to obtain metallic films and this was attributed to the reduced deposition efficiency of the rf system.