High rate and process control of reactive sputtering by gas pulsing:: the Ti-O system

Titanium oxide thin films were deposited by de reactive magnetron sputtering from a pure titanium target in a mixture of Ar + O-2. The reactive gas was injected with a well-controlled pulsed technique. A constant pulsing period was used for every deposition whereas the O-2 injection time was changed systematically. Pulsing the reactive gas led to an increase of the deposition rate (up to 70% of the metallic rate) and an improvement of the electrical conductivity of the films (sigma = 21 S m(-1) at 300 K) keeping an optical transmittance of 63% in the visible region. The influence of the modulated reactive gas flow rate on the crystallographic structure and composition was also investigated. Real time measurements of the electrical parameters of the titanium target and of the oxygen partial pressure by differential mass spectrometry show that the significant improvements of the reactive gas pulsing technique are due to the possibility to process alternately in metallic/compound mode. (C) 2000 Elsevier Science B.V. All rights reserved.