Characterization and modeling of electrical resistivity of sputtered tungsten films

Tungsten (W) thin films were deposited on a polyimide substrate by sputteri ng deposition inn pure argon plasma using a triode discharge system. The pr operties of these W films were investigated as functions of ions energy, ar gon pressure and film thickness. The composition and crystallographic and m icrographic structures of W films were determined by Rutherford backscatter ing spectroscopy and x-ray diffraction techniques, respectively. Less than 6 at. % argon and metallic impurities (duc to the sputtering chamber config uration) was incorporated into the W films and different volume ratios of t ungsten crystallographic phases (Wa and WP) were observed in the films. The electrical resistivity of Wa films was interpreted from impurity concentra tions and the microstructure with a model based on electron scattering mech anisms at grain boundaries. It was shown that the electron reflectivity of the grain boundaries depends of the size of the grains. In order to evaluat e the contribution of wp phase on the electrical resistivity of biphase W f ilms, two models were proposed. The model of the averaged effect of the two phases leads to calculations that are in good agreement with experimental results and an intrinsic resistivity of WP phase is proposed to be close to 30 mu Omega cm. (C) 2001 American Vacuum Society.