OPTICAL-PROPERTIES OF NITRIDE COATINGS DEPOSITED AT LOW SUBSTRATE TEMPERATURES

Hard coatings of TiN and ZrN were reactively sputtered onto various glass, aluminum and steel substrates at temperatures below 400 K. Various thicknesses between 10 and 50 nm were chosen, as well as thicker films of 350 nm. Films were deposited with and without a negative substrate bias of 80 V at various nitrogen partial pressures. Thicker, stoichiometric TiN coatings (2 μm) were produced also at a temperature of 750 K by ion plating. The optical properties (reflectivity and, where possible, transmittance) were measured in the wavelength range of 0.35 μm to 2 μm. It was found that the quality of the coatings depends on the deposition temperature and the substrate bias. Improved quality can be achieved with hot substrates. When acceptable, about 5% lower reflectivity can be obtained at deposition temperatures below 400 K. The films proved to be abrasion resistant at thicknesses 23 nm and more. © 1990.