A method of fabricating a semiconductor device is disclosed, the method generally including the steps of: forming a gate dielectric layer on a semiconductor substrate;forming a gate electrode on the gate dielectric layer;forming an etch stop layer on the gate electrode;forming a capacitor on the semiconductor substrate adjacent to the gate electrode;after forming the capacitor, forming a contact hole passing through the etch stop layer on the gate electrode;and, diffusing deuterium into the gate dielectric layer through the contact hole.