FinFET structures and methods of forming the same

A device, comprising:

• a first semiconductor fin protruding from a substrate;
• a gate stack extending over the first semiconductor fin, wherein the gate stack comprises:
• a gate dielectric layer over the first semiconductor fin;
• a first seed layer over the gate dielectric layer;
• a second seed layer over the first seed layer, wherein the second seed layer has a different structure than the first seed layer;
• and
• a conductive layer over the second seed layer, wherein the first seed layer, the second seed layer, and the conductive layer comprise the same conductive material;
• and
• source and drain regions on portions of the first semiconductor fin adjacent the gate stack.

A semiconductor device, comprising:

• a fin extending over a semiconductor substrate;
• an isolation region adjacent the fin;
• a gate structure along sidewalls and over a top surface of a channel region of the fin, wherein the gate structure comprises:
• a gate dielectric layer over the channel region;
• a first amorphous seed layer over the gate dielectric layer;
• a first crystalline seed layer over the gate dielectric layer;
• and
• a bulk metal material over the first amorphous seed layer and over the first crystalline seed layer, wherein the bulk metal material, the first amorphous seed layer, and the first crystalline seed layer comprise the same conductive material;
• and
• an epitaxial region over the fin adjacent the gate structure.