Barrier layer for interconnect structures of a semiconductor wafer and method for depositing the barrier layer

An interconnect structure of a semiconductor device includes a tungsten plug deposited in a via or contact window. A barrier layer separates the tungsten plug from the surface of a dielectric material within which the contact window or via is formed. The barrier layer is a composite of at least two films. The first film formed on the surface of the dielectric material within the via is a tungsten silicide film. The second film is a tungsten film formed on the tungsten silicide film. A tungsten plug is formed on the tungsten film to complete interconnect structure. The barrier layer is deposited using a sputtering technique performed in a deposition chamber. The chamber includes tungsten silicide target from which the tungsten silicide film is deposited, and a tungsten coil from which the tungsten film is deposited.