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Abstract

A method of forming a tungsten plug in a semiconductor device includes forming a contact hole in an insulating layer, forming a contiguous titanium layer in the contact hole and on the insulating layer, forming a titanium nitride layer on the titanium layer. forming a thin tungsten layer of about 50 angstroms or less on the titanium nitride layer by CVD (chemical vapor deposition), annealing the structure once the thin tungsten layer has been formed, and depositing additional tungsten by CVD to completely fill the contact hole. The titanium nitride layer can be formed by a discrete CVD process or as a result of the annealing process. Forming a thin tungsten layer by CVD before the contact hole is completely filled in with tungsten is used to stabilize the titanium layer. For instance, a small amount of fluorine from the source gas of the thin tungsten layer diffuses into the titanium layer. Annealing the structure then diffuses the fluorine uniformly throughout the titanium layer to the point where additional fluorine from the subsequent CVD process of depositing tungsten can not diffuse into the titanium layer This, in turn, prevents a reaction at the titanium layer from taking place at the time the contact hole is filled in completely with tungsten. Accordingly, the titanium nitride layer remains adhered to the insulating layer.

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First Claim