Colour control of titanium nitride coatings produced by reactive magnetronsputtering at temperature less than 100 degrees C

Decorative dry coatings are extensively used nowadays to replace the curren t pollutant wet coating processes, but the links between the coating appear ance and the physical properties are usually not fully understood. This pap er presents the results obtained by optical measurements in order to invest igate the import of titanium nitride physical properties such as stoichiome try and structure on the coating visual appearance for TiNx thin films depo sited by DC reactive magnetron sputtering at temperature lower than 100 deg rees C onto grounded substrate. It was shown that colours going from metall ic grey to gold and finally brownish red have been obtained when the N-2 fl ow is raised. These TiNx layer colour variations can be resolved in terms o f the Drude model. As titanium metallic bonds decrease in the film, the abs orbed part of the spectra moves towards lower energies, and when the minimu m titanium content in the deposited films is reached (N-2 mass flow>4 seem) , defects also reduce the amortised spectra towards slightly more reddish e nergies, but are difficult to control. In conclusion, as the N-2 content in the gas discharge guides the nitrogen composition, it is the key parameter in colour control for TiNx sputtered films, especially when N-2 mass flow is less than 4 sccm. (C) 1999 Elsevier Science S.A. All rights reserved.