ZIRCONIUM CARBONITRIDE FILMS PRODUCED BY PLASMA-ASSISTED METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION

Zirconium carbonitride thin films were deposited on steel substrates by means of the d.c. plasma-assisted chemical vapour deposition technique using tetrakis-(methylethylamido)-zirconium (Zr(NMeEt)(4))and tetrakis-(diethylamido)-zirconium(Zr(NEt(2))(4)) as precursors. Depositions were successfully carried out at a substrate temperature of 350 degrees C using the carrier gases hydrogen, nitrogen and argon at a total pressure of 200 Pa. The influence of the precursors on the deposition rate and film morphology was studied by scanning electron microscopy. By means of X-ray diffraction and X-ray photoelectron spectroscopy (XPS) it was established that f.c.c. Zr(C,N) coatings were obtained which contain a significant amount of oxygen and organic bonded carbon. Using Zr(NEt(2))(4) as the starting source, the substrate temperature was varied from 200 to 500 degrees C. The deposition rate, morphology and chemical composition of the coatings depend on the substrate temperature. Up to a temperature of 400 degrees C, fine-grained polycrystalline Zr(C,N) coatings were obtained. If the substrate temperature was kept below 300 degrees C, the morphology of these coatings exhibited a columnar structure. XPS measurements revealed that the amount of organic bonded carbon impurities in the films decreased at deposition temperatures above 250 degrees C. The Vickers hardness of the coatings deposited at 300 degrees C at maximum growth rate reached 2000 HV.