Abstract: A method is provided for fabricating a semiconductor device. A semiconductor substrate is provided. A first high-k dielectric layer is formed on the semiconductor substrate. A first treatment is performed on the high-k dielectric layer. In an embodiment, the treatment includes a UV radiation in the presence of O2 and/or O3. A second high-k dielectric layer is formed on the treated first high-k dielectric layer. A second treatment is performed on the second high-k dielectric layer. In an embodiment, the high-k dielectric layer forms a gate dielectric layer of a field effect transistor.