STEP COVERAGE OF TUNGSTEN FILMS DEPOSITED BY GERMANE REDUCTION OF WF6

The step coverage of tungsten films deposited by the germane reduction of WF6 is investigated. The step coverage modulus for the germane pro cess is influenced only by the deposition temperature. It hardly depen ds on the partial pressures of the reactive species. These results are confirmed by experiments on structures with a large internal surface as compared to the access area. The stepcoverage of the films deposite d by this process is excellent and sufficient to fill small (0.5 mu m) contact holes with a high aspect ratio.