Fabrication of tungsten films by metallorganic chemical vapor deposition

Tungsten films growing on copper substrates were fabricated by metallorganic chemical vapor deposition (MOCVD). The chemical purity, crystallographic phase, cross-sectional texture, and resistivity of the deposited films both before and after annealing treatment were investigated by X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and four-point probe method. It is found that the films deposited at 460A degrees C are metastable beta-W with (211) orientation and can change into alpha-W when annealed in high-purity hydrogen atmosphere at high temperature. There are small amounts of C and O in the films, and the W content of the films increases with increasing deposition temperature and also goes up after annealing in high-purity hydrogen atmosphere. The films have columnar microstructures and the texture evolution during their growth on copper substrates can be divided into three stages. The resistivity of the as-deposited films is in the range of 87-104 mu I (c) A center dot cm, and low resistivity is obtained after annealing in high-purity hydrogen atmosphere.