A method for forming a refractory metal layer that features two-stage nucleation prior to bulk deposition of the same. The method includes placing a substrate in a deposition zone, flowing, into the deposition zone during a first deposition stage, a silicon source, such as a silane gas, and a tungsten source, such as tungsten-hexafluoride gas, so as to obtain a predetermined ratio of the two gases therein. During a second deposition stage, subsequent to the first deposition stage, the ratio of the two gases is varied. Specifically, in the first deposition stage there is a greater quantity of silane gas than tungsten-hexafluoride gas. In the second deposition stage there may be a greater quantity of tungsten-hexafluoride than silane.