Methods to adjust threshold voltage in semiconductor devices

A method of forming a device on a substrate, comprising:

• providing a substrate having a partially fabricated first device disposed on the substrate, the first device including a first film stack comprising a first dielectric layer and a first high-k dielectric layer disposed atop the first dielectric layer;
• depositing a first metal layer atop the first film stack;
• and
• modifying a first upper surface of the first metal layer by exposing the first upper surface to a non-reactive species to physically modify the exposed first upper surface to form at least one of dangling bonds or lattice defects atop and by exposing the physically modified first upper surface to a reactive species to chemically modify the first upper surface to adjust a first threshold voltage of the first device, wherein the modification of the first upper surface does not extend through to a first lower surface of the first metal layer.