SEMICONDUCTOR DEVICE WITH STRAINED CHANNELS INDUCED BY HIGH-K CAPPING METAL LAYERS

摘要

A semiconductor device with a metal gate is disclosed. The device includes a semiconductor substrate including a plurality of source and drain features to form a p-channel and an n-channel. The device also includes a gate stack over the semiconductor substrate and disposed between the source and drain features. The gate stack includes a high-k (HK) dielectric layer formed over the semiconductor substrate. A tensile stress HK capping layer is formed on top of the HK dielectric layer in close proximity to the p-channel, and a compressive stress HK N-work function (N-WF) metal layer is formed on top of the HK dielectric layer in close proximity to the n-channel. A stack of metal gate layers is deposited over the capping layers.