Multiple layer barrier metal for device component formed in contact trench

A method for fabricating a semiconductor device formed on a semiconductor substrate including a low-doped region proximate a contact trench, the method comprising:

• a) forming the contact trench proximate the low-doped region;
• b) depositing a first metal layer on a bottom and sidewalls of the contact trench, wherein the first metal layer includes a nitride;
• c) depositing a second layer on top of the first layer and onto portions of the sidewalls not covered by the first metal layer, wherein the second metal layer blocks diffusion between tungsten and the semiconductor of the substrate;
• and
• d) depositing tungsten in a remaining portion of the contact trench to form a tungsten plug, wherein the second metal layer includes Aluminum-copper.

A method for fabricating a semiconductor device formed on a semiconductor substrate including a low-doped region proximate a contact trench, the method comprising:

• a) forming the contact trench proximate the low-doped region;
• b) depositing a first metal layer on a bottom and sidewalls of the contact trench wherein the first metal layer includes a nitride;
• c) depositing a second layer on top of the first layer and onto portions of the sidewalls not covered by the first metal layer, wherein the second metal layer blocks diffusion between tungsten and the semiconductor of the substrate;
• and
• d) depositing tungsten in a remaining portion of the contact trench to form a tungsten plug, wherein the second metal layer includes an aluminum alloy.