Methods for forming low resistivity contacts

A method of forming a contact structure on a semiconductor substrate, comprising:

• forming a metal layer on a surface of the contact structure by maintaining a first temperature of a substrate and providing a first carrier gas, a first metal-containing precursor, and a first hydrogen-containing precursor to a first deposition chamber, wherein:
• the contact structure comprises a feature formed in a surface of the semiconductor substrate,
• the feature comprises an opening that is defined by a bottom surface and sidewalls, which comprise a dielectric material, and
• the metal layer is formed over the sidewalls and the bottom surface and the metal layer comprises a metal and a silicon containing material;
• exposing the metal layer formed over the sidewalls and bottom surface to a nitrogen containing plasma to cause a portion of the metal layer to form a nitrided layer;
• exposing the nitrided layer to a metal chloride containing precursor to remove a top portion of the nitrided layer from the sidewalls and surface of the semiconductor substrate;
• and
• depositing a metal gap fill material over the nitrided layer to fill the feature formed in the surface of the semiconductor substrate.