Patent ID: 7727881

Claim:
A method of forming a protective layer of material on or within an exposed metal surface of a partially fabricated semiconductor device having a pattern of metal layers in a dielectric, the method comprising: pre-cleaning the partially fabricated semiconductor device to at least partially remove metal oxide from the metal layers by treating the surface of the partially fabricated semiconductor device with a plasma comprising a reducing gas; (a) after the pre-cleaning, contacting the partially fabricated semiconductor device with a nitrogen containing reactant for a period of time in an absence of plasma, wherein the nitrogen containing reactant interacts with the exposed metal surface of a metal layer, to form a metal nitride at the surface of said metal layer, thereby passivating said metal surface; and (b) subsequently contacting the partially fabricated semiconductor device with a second reactant in an absence of plasma, such that the second reactant reacts with unpassivated metal atoms of the metal layer and chemically transforms the top portion of the metal layer into a first protective self-aligned buffer layer, wherein said first protective self-aligned buffer layer resides entirely within said metal layer; and wherein the depth of the first protective self-aligned buffer layer formed in (b) is regulated by an amount of the metal nitride formed in (a), such that formation of the increased amounts of the metal nitride in (a) decreases the depth of said first protective self-aligned buffer layer in (b).