Abstract: A method of fabricating a semiconductor device which includes providing a silicon substrate having a patterned mask thereover to expose a portion of the surface of the substrate. The exposed surface portion is oxidized to form a sacrificial silicon oxide region to a predetermined depth in the substrate at the exposed portions of the substrate. The sacrificial silicon oxide is then removed by a HF etch and a second region of silicon oxide is formed in the substrate in the region from which the sacrificial silicon oxide was removed. The step of removing the silicon oxide also includes removing a portion of the pad oxide. The sacrificial silicon oxide has a thickness less than the second region of silicon oxide which is from about 10 percent to about 30 percent of the thickness of the second region of silicon oxide. The oxidation steps are thermal oxidation steps in an oxygen-containing ambient.