Formation and Properties of Thin Tunnelable SiO2 Films Using a Vaporized O 2 Source at Liquid N 2 Temperature

Abstract

A high temperature (700°–1100°C) oxidation process for the formation of thin tunnelable (20–70Å) is described. This oxidation process uses liquid at liquid temperature as a source of oxidant and oxygen is vaporized just before the furnace tube to supply a water‐free oxidant ambient. The activation energy (20.2 kcal/mole) of oxidation rate differs from that previous (43.9 kcal/mole) which has been evaluated for thin oxide growth using the partial pressure method. By the use of this technique we can control thickness to ±0.5Å accuracy. The rate of oxidation has been found to be governed by the inverse‐logarithmic growth law, i.e., Mott‐Cabrera's field‐assisted diffusion law. Electrical characteristics, such as dynamic conductance, capacitance, and tunnel current, are measured and discussed. The increment of the oxidation temperature is found to result in the decrease of surface‐state density at the interface. The process described enables the way for wider application of thin oxide devices.