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

A method for forming a barrier layer on an interconnect structure, comprising the steps of:

• forming a first tungsten silicide film within a recess formed on a topographical structure on a semiconductor substrate;
• forming a tungsten film onto said first tungsten silicide film;
• forming a tungsten plug within said recess and over said tungsten film;
• and
• forming a second tungsten silicide film, within the recess, between the tungsten film and the tungsten plug.

A method for forming a tungsten plug on a semiconductor device having a dielectric material formed over a substrate and a recess formed in the dielectric material, and said tungsten plug to be formed within the recess, the method comprising the steps of:

• (a) conformally depositing tungsten silicide at a predetermined deposition rate to a substantially uniform predetermined thickness along walls of the recess to form a first film;
• (b) conformally depositing tungsten to a substantially uniform predetermined thickness over the tungsten silicide within the recess while reducing the rate of deposition of the tungsten silicide for the first film at about the same time as, or after starting the deposition of tungsten for the second film within the recess and, after said tungsten silicide reaches said predetermined thickness thereof to form a second film;
• (c) depositing tungsten silicide within the recess while said tungsten is being depositing within the recess thereby forming a tungsten silicide gradient within said second film;
• and,
• (d) depositing tungsten within the recess over the second film to form said tungsten plug.