Ruthenium seeding for corrosion free molybdenum growth

A method of forming a semiconductor device, the method comprising:

• exposing a top surface of a substrate to a first reactant and a ruthenium precursor to deposit a seed layer on the top surface of conductive metal layer on the substrate, the substrate comprising at least one feature formed in a dielectric layer, the dielectric layer defining a gap including sidewalls and a bottom, the seed layer depositing on the conductive metal layer;
• and
• exposing the seed layer to a second reactant and a metal precursor to selectively deposit a gap fill material on the seed layer.