Characterization of cosputtered tungsten carbide thin films

Polycrystalline thin films of W-C were deposited on single-crystal Si(111) or SiO/sub 2/ substrates by r.f. planar magnetron cosputtering of graphite and tungsten targets. The reaction of these W-C films in the presence or absence of an additional bonding layer of titanium with silicon or SiO/sub 2/ substrates was studied in the temperature range from 500 to 800 C by a combination of backscattering spectrometry, scanning electron microscopy, x-ray diffraction, and sheet-resistivity measurements. Films of composition W43C57 are of the cubic WC1-x phase and have a room temperature resistivity of 100 micro ohms cm. On thermal annealing for 30 min in vacuum on silicon substrates, they form blisters above 700 C. Films of composition W73C25 are of the hexagonal alpha W/sub 2/C phase and have a room-temperature resistivity of 140 micro ohms cm. On silicon substrates, they are thermally stable up to 800 C annealing. WSi/sub 2/ is observed only above 800 C annealing. The sheet resistance at room temperature of films of either composition on SiO/sub 2/ is unchanged after annealing up to 800 C.