A semiconductor device is disclosed that includes: a substrate; a first dielectric layer formed over the substrate and formed of a first high-k material, the first high-k material selected from the group consisting of HfO2, HfSiO, HfSiON, HfTaO, HfTiO, HfTiTaO, HfAlON, and HfZrO; a second dielectric layer formed over the first dielectric layer and formed of a second high-k material, the second high-k material being different than the first high-k material and selected from the group consisting of HfO2, HfSiO, HfSiON, HfTaO, HfTiO, HfTiTaO, HfAlON, and HfZrO; and a metal gate formed over the second dielectric layer. The first dielectric layer includes ions selected from the group consisting of N, O, and Si.