Abstract: Methods of manufacturing and processing semiconductor devices (i.e., electronic devices) are described. The methods include treating a surface of a metal gate stack with a radical treatment. The radical treatment may be used to treat one or more layers or surfaces of layers in the metal gate stack. The radical treatment may be performed once or multiple times during the methods described herein. The radical treatment comprises flowing one or more of nitrogen radicals (N2*) and hydrogen radicals (H*) over the surface of the metal gate stack.

Abstract: Embodiments of the present disclosure are related to methods of preventing aluminum diffusion in a metal gate stack (e.g., high-? metal gate (HKMG) stacks and nMOS FET metal gate stacks). Some embodiments relate to a barrier layer for preventing aluminum diffusion into high-? metal oxide layers. The barrier layer described herein is configured to reduce threshold voltage (Vt) shift and reduce leakage in the metal gate stacks. Additional embodiments relate to methods of forming a metal gate stack having the barrier layer described herein. The barrier layer may include one or more of amorphous silicon (a-Si), titanium silicon nitride (TiSiN), tantalum nitride (TaN), or titanium tantalum nitride (TiTaN).