Embodiments of the invention generally relate to transistors with high-k dielectric spacer liner to mitigate lateral oxide encroachment. In this regard a semiconductor device is introduced having a substrate, a high-k gate dielectric layer on the substrate, a metal gate electrode on the high-k gate dielectric layer, and a high-k dielectric layer on either side of and adjacent to the metal gate electrode and high-k gate dielectric layer, extending a distance away from the metal gate electrode and high-k gate dielectric layer on the substrate. Other embodiments are also disclosed and claimed.