A high quality LPCVD SiO2 film with interface quality, trapping behavior, and intrinsic dielectric integrity comparable to dry thermal oxide is demonstrated. By stacking thermal and high quality LPCVD SiO2 films, gate oxides with very different defect densities are demonstrated. The tradeoffs between quality of each SiO2 layer and the ability of one layer to compensate for defects in the other layer are presented. The lowest defect density (much lower than a conventional dry thermal oxide film) is observed in a stacked gate oxide consisting of a 95 Å thermal oxide followed by a 25 Å LPCVD oxide deposition and a short reoxidation. Thicker LPCVD oxide layers increase the defect density of the stacked dielectric compared to this optimal case. These results demonstrate that an optimized thermal/LPCVD oxide stacked dielectric is a promising candidate as the gate oxide of ULSI MOS devices.