ELECTRICAL-PROPERTIES OF THIN ANODIC OXIDES FORMED ON SILICON IN AQUEOUS NH4OH SOLUTIONS

The capacitance vs. voltage and current density vs. voltage characteri stics of silicon dioxide films formed by anodization of silicon in dil ute ammonium hydroxide solutions have been measured. Postoxidation ann ealing (POA) ai temperatures up to 700-degrees-C greatly reduces the l eakage currents and results in breakdown voltages in excess of 10 MV/c m. However, leakage currents are still in excess of those obtained by thermal oxidation, possibly indicating some residual structural imperf ection such as a transition layer or roughness at the silicon-silicon dioxide interface. The combination of a POA at 700-degrees-C with a po stmetallization anneal in forming gas at 400-degrees-C have reduced th e interface state densities to 4 X 10(10) eV-1 cm-2 with fixed charge densities at the interface of -7 x 10(11) charge/cm2.