Metal-titanium dioxide-silicon capacitors

Titanium dioxide capacitors were fabricated on silicon wafers using electron-beam evaporation. The titanium dioxide (TiO₂) films on the silicon wafers were annealed in oxygen at 900° C to assure conversion of the films to the rutile phase. For long anneal times with thin films, significant silicon dioxide (SiO₂) grows under the TiO₂ as a result of oxygen diffusion through the TiO₂ film. Good quality TiO₂ films were obtained in the thickness range of 500 Å to 10,000 Å. Aluminum electrodes were evaporated on the TiO₂ to complete the capacitors. Capacitive densities of greater than 2 pf/sq. mil with a leakage current of less than 2 nanoamps/sq. mil were obtained. Longer anneal times result in a trade off of lower capacitance with less leakage and higher breakdown voltages due to the influence of the SiO₂ layer.