INVESTIGATIONS ON MICROSTRUCTURE, COMPOSITION AND PROPERTIES OF PECVDTINX-COATINGS

Nearly stoichiometric TiNx-coatings have been deposited on different s ubstrates using a gaseous reaction mixture of TiCl4, N-2, H-2 and Ar i n a pulsed d.c. plasma discharge. The influence of substrate temperatu re: plasma power density, argon partial pressure and type of substrate on chlorine content, texture and microstructure of the coatings has b een investigated keeping constant the other parameters of the plasma e nhanced chemical vapor deposition (PECVD) process. Microstructure has been characterized by scanning electron microscopy (SEM) fractographs of the coatings and by determination of texture. The chlorine content quantitatively determined from energy-dispersive X-ray spectra (EDX) u sing a chlorine containing mineral as standard decreases on an increas e of substrate temperature or plasma power density. Texture changes fr om <200> to <111> and random and microstructure changes from columnar growth to granular for decreasing substrate temperature as well as dec reasing plasma power density. Argon partial pressure does not affect t he microstructure but the texture. The properties of the coatings are independent of type of substrate for higher plasma power densities. Ox ygen present at the surface of the substrate stimulates the developmen t of a texture at low plasma power densities.