A semiconductor device with a metal gate is disclosed. The device includes a semiconductor substrate, source and drain features on the semiconductor substrate, and a gate stack over the semiconductor substrate and disposed between the source and drain features. The gate stack includes an interfacial layer (IL) layer, a high-k (HK) dielectric layer formed over the semiconductor substrate, an oxygen scavenging metal formed on top of the HK dielectric layer, a scaling equivalent oxide thickness (EOT) formed by using a low temperature oxygen scavenging technique, and a stack of metals gate layers deposited over the oxygen scavenging metal layer.