SCAVENGING METAL STACK FOR A HIGH-K GATE DIELECTRIC

A semiconductor structure is provided. The structure includes a semiconductor substrate of a semiconductor material and a gate dielectric having a high dielectric constant dielectric layer with a dielectric constant greater than silicon. The gate dielectric is located on the semiconductor substrate. A gate electrode abuts the gate dielectric. The gate electrodes includes a lower metal layer abutting the gate dielectric, a scavenging metal layer abutting the lower metal layer, an upper metal layer abutting the scavenging metal layer, and a silicon layer abutting the upper metal layer. The scavenging metal layer reduces an oxidized layer at an interface between the upper metal layer and the silicon layer responsive to annealing.