PLASMA-ASSISTED DEPOSITION OF HARD MATERIAL LAYERS FROM ORGANOMETALLIC PRECURSORS

Using amido-substituted titanium or zirconium compounds as starting substances, the deposition temperature for hard material layers, e.g. Ti(C,N) and Zr(C,N), can be decreased below the temperature of the usual plasma-assisted chemical vapour deposition process. In the temperature range from 550 to 850 K 'hard-material-like'' coatings were obtained, the deposition rate of which amounted to 2-3 mum h-1. The layers have been characterized regarding composition, morphology and microstructure. The C and N contents of the coatings are dependent on temperature, gas phase composition and plasma power. Transmission electron microscopy investigations of ''TiN'' layers revealed a small grain size in the initial range followed by a typical columnar growth. Fragments or crack products of the organometallic precursors inserted in the layers influence the hard material properties unfavourably. The experiments are compared with thermally activated deposition and discussed taking into consideration thermodynamical calculations for the Ti-N-C-H system (with regard to organometallic starting compounds).