Preparation of low resistivity tungsten thin films deposited by microwave-plasma-enhanced chemical vapour deposition from the tungsten hexafluoride-hydrogen system

The characteristics of tungsten thin films deposited onto single-crystal Si(100) and silicon dioxide by microwave-plasma-enhanced chemical vapour deposition are studied as a function of the main parameters of the plasma-surface interaction. Throughout the whole pressure range investigated, the highest deposition rates are obtained for an optimum H-2-to-WF6 partial pressure ratio of 5. The evolutions of the deposition rate, purity, morphology and resistivity of tungsten films is investigated as functions of the plasma density, ion bombardment energy, substrate composition and temperature. In particular, the film resistivity decreases with increasing deposition temperature from ambient temperature to 300-degrees-C. At this temperature, a resistivity lower than 10 muOMEGA cm is obtained.