Cobalt selectivity improvement in selective cobalt process sequence

A method for forming a cobalt cap, comprising:

• positioning a substrate within a processing chamber, wherein the substrate comprises a copper surface and a dielectric surface with a plurality of exposed methyl groups;
• exposing the substrate to a deposition gas comprising a cobalt precursor gas at a first temperature to form a cobalt-containing layer selectively over the copper surface, the cobalt-containing layer comprising an inactive surface;
• forming a plasma in the presence of a treatment gas to create an activated treatment gas, the treatment gas comprising ammonia;
• delivering the activated treatment gas to the inactive surface of the cobalt-containing layer to create an active surface, wherein one or more of the plurality of exposed methyl groups are removed;
• regenerating the exposed methyl groups using a carbon containing deposition gas;
• sequentially repeating the exposing of the substrate to the deposition gas, forming of the plasma in the presence of the treatment gas, delivering the activated treatment gas and regenerating the exposed methyl groups using the carbon containing deposition gas until the cobalt-containing layer has achieved the desired thickness;
• and
• depositing a dielectric barrier layer over the cobalt-containing layer and the dielectric surface.

A method for forming a cobalt cap, comprising:

• exposing the processing chamber to a silicon nitride deposition gas in the presence of high RF power;
• exposing the processing chamber to a densifying gas comprising ammonia in the presence of high RF power;
• positioning a substrate within a processing chamber, wherein the substrate comprises a copper surface with a contamination layer and a dielectric surface with a plurality of exposed methyl groups;
• exposing the substrate to a preclean gas during an anneal process at a first temperature, wherein the exposed methyl groups are preserved and wherein the contamination layer is removed;
• exposing the substrate to a deposition gas comprising a cobalt precursor gas at a second temperature to form a cobalt-containing layer selectively over the copper surface, the cobalt-containing layer comprising an inactive surface;
• forming a plasma in the presence of a treatment gas to create an activated treatment gas, the treatment gas comprising ammonia;
• delivering the activated treatment gas to the inactive surface of the cobalt-containing layer to create an active surface, wherein one or more of the plurality of exposed methyl groups are removed;
• regenerating the exposed methyl groups using a carbon containing deposition gas;
• sequentially repeating the exposing of the substrate to the deposition gas, forming of the plasma in the presence of the treatment gas, delivering the activated treatment gas and regenerating the exposed methyl groups using a carbon containing deposition gas until the cobalt-containing layer has achieved the desired thickness;
• and
• depositing a dielectric barrier layer over the cobalt-containing layer and the dielectric surface.