ROLE OF MICROSTRUCTURE IN FORMING THIN CARBON-FILM PROPERTIES

Amorphous carbon (a-C) films were deposited by d.c. magnetron sputtering of a graphite target in argon gas and by thermal evaporation of graphite rods. A series of films were prepared by sputtering at different power levels in the range 10-250 W and different substrate temperatures in the range 15-600-degrees-C. Si-Ti-Al-0 ceramic plates and single crystals of Si and NaCl were used as substrates. The resistivity in two directions-parallel and perpendicular to the substrate surface-and Vickers hardness as a function of substrate temperature T(s) were measured. For magnetron-sputtered films the dependence of the above parameters on discharge power was also measured. The structure of the a-C films was examined by electron diffraction. The phenomenon of resistivity anisotropy in a-C films was revealed. It was shown that under magnetron sputtering either ''diamond-like'' (when T(s) < 100-degrees-C) or ''graphitic'' (when T(s) > 100-degrees-C) carbon films were formed. This transition and the diamond-like properties of such films (when T(s) < 100-degrees-C) are assumed to be due rather to peculiarities of the film microstructure than to the sp3/sp2 bonding ratio.