Tungsten Films on Si / SiO2 Made from Spun Polyoxometalates and Their Application in the Electroless Deposition of Metals

Metallic tungsten films, derived from a tungsten‐rich negative tone DUV resist, were characterized with respect to their grain structure, physical properties, and chemical composition. Atomic force microscopy, low angle x‐ray diffraction, adhesion testing, four‐point resistivity probing. Auger and ESCA analysis with depth profiling, and UV‐visible absorption spectroscopy. Key findings are: grain sizes of the tungsten nuclei depend on the temperature of reduction of the tungsten oxide to metal and vary from 30 nm for the 450°C reduced films to 250 nm for the films reduced at 700°C. The films are contaminated with tungsten carbide and oxide. Higher reduction temperatures favor purity. The tungsten nuclei were palladium activated in a solution for micropatterning of selective electroless deposition of nickel and copper. In activation, Pd2+ is reduced to Pd0 while W0 is oxidized, probably to . The Pd0 grains deposited next to and in electrical contact with the tungsten grains, rather than on them. The palladium grain size did not depend on that of tungsten.