Patent ID: 8629028

Claim:
A method of forming a semiconductor device comprising: forming an oxide containing isolation region in a semiconductor substrate to define an active semiconductor region; forming a blanket gate stack including a high-k gate dielectric layer on the active semiconductor region, wherein at least a portion of the gate stack extends from the active semiconductor device region to the oxide containing isolation region; etching the blanket gate stack to provide an opening over the oxide containing isolation region, wherein a base of the opening is provided by a surface of the oxide containing isolation region; isotropically etching the surface of the oxide containing isolation region that is exposed by the opening to remove a portion of the oxide containing isolation region that is in contact with the high-k gate dielectric layer and form an undercut region at an interface between the blanket gate stack and the oxide containing isolation region; forming an encapsulating dielectric material in the undercut region in contact with the high-k gate dielectric layer and along sidewalls of the opening through the blanket gate stack; and patterning the blanket gate stack to form a gate structure.