The present disclosure discloses an exemplary method for fabricating a gate structure comprising depositing and patterning a dummy oxide layer and a dummy gate electrode layer on a substrate; surrounding the dummy oxide layer and the dummy gate electrode layer with a sacrificial layer; surrounding the sacrificial layer with a nitrogen-containing dielectric layer; surrounding the nitrogen-containing dielectric layer with an interlayer dielectric layer; removing the dummy gate electrode layer; removing the dummy oxide layer; removing the sacrificial layer to form an opening in the nitrogen-containing dielectric layer; and depositing a gate dielectric; and depositing a gate electrode.