Tungsten-containing amorphous carbon films deposited by pulsed vacuum arc

Amorphous carbon (a-C) films with a wide range of W concentrations have bee n produced by mixing C+ and Wn+ plasma streams originated in filtered catho dic are plasma sources. Adhesion of these films to silicon substrates was v ery high, and was achieved by atomically mixing the film and the Si at the interface. The deposition of the tungsten-doped amorphous carbon films was carried out at room temperature, and the energy of the depositing ions was in the range of 100-6 keV. The films were characterized by TEM, XRD, XPS, R ES and Raman spectroscopy. Small additions of W to amorphous carbon signifi cantly decrease the magnitude of the compressive stresses that are present in these films. The corresponding decrease in hardness with increasing W co ntent was not nearly as significant. Film hardness varied between 63 GPa (w ith 1 at.% W) and 20 GPa (the bulk value for WC) and depended not only on t he W content but also on the depositing ion energy. At W contents between 2 0 and 50 at.%, the film consisted of crystalline WC dispersed in an amorpho us C matrix. At W content below 20 at.%, the WC present in the film was amo rphous, and the film consisted then of mixtures of a-WC and a-C. (C) 1999 E lsevier Science S.A. All rights reserved.