Semiconductor device and method

A method comprising:

• generating a first plasma from a first precursor gas, the first precursor gas comprising helium;
• separating charged species in the first plasma from metastable species in the first plasma;
• mixing the metastable species with a second precursor gas, the second precursor gas comprising hydrogen, wherein the mixing the first plasma with the second precursor gas generates a second plasma;
• and
• exposing a work function layer on a semiconductor fin to the second plasma, the semiconductor fin extending from a substrate.

A method comprising:

• forming a fin extending from a substrate;
• depositing a dielectric layer over the fin;
• depositing a first work function layer over the dielectric layer, the first work function layer comprising tungsten;
• exposing the first work function layer to a metastable plasma generated from metastable nitrogen, metastable helium, and hydrogen atoms;
• depositing a second work function layer over the dielectric layer and the first work function layer, wherein the second work function layer is deposited in physical contact with the dielectric layer in a first region and the first work function layer in a second region;
• and
• forming a gate electrode over the first work function layer and the second work function layer.