Reactive deposition of nitrides and oxides using a twin-cathode inverted cylindrical magnetron

Nitrides and oxides of aluminum and other metals were reactively sputtered in a twin-cathode inverted cylindrical magnetron run with mid-frequency pow er. This geometry is particularly suited for coating three-dimensional obje cts of complex shape. However, high rate reactive sputtering in such an enc losed cathode has not been reported and presents unknown processing conditi ons. High rate deposition requires operation at a point that is normally un stable. For aluminum nitride films, high pumping speed was sufficient to en sure stable operation. Reactive deposition of oxides required feedback from the discharge current to control the flow of oxygen. This was successful f or the relatively simple case of aluminum oxide, and the much more complica ted case of titanium oxide. Films were deposited onto glass substrates unde r conditions of different pressure, power, and reactive gas flow. Reactive gas flows were found where good films of aluminum nitride and aluminum oxid e could be deposited at high rates. Rates (relative to pure aluminum) were 32% for aluminum nitride and 26-40% for aluminum oxide. Both aluminum nitri de and aluminum oxide films were insulating, non-absorbing, and adherent to the glass substrates. (C) 2000 Elsevier Science B.V. All rights reserved.