Formation of silicon oxide by the low‐temperature process and its application to electron devices

Abstract

The technology of forming silicon oxide film at low temperature was developed and the application of the oxide film to electronic devices was investigated. Silicon oxide was formed by anodic oxidation of silicon at room temperature. The anodic oxide was Si‐rich in the as‐grown state. When the anodic oxide film was annealed at 600°C in hydrogen atmosphere, followed by annealing at 450°C in the same ambient, the film became stoichiometric SiO2 and the SiO2/Si interface condition was improved because of the saturation of the unsaturated Si atoms at the interface. These mechanisms were evaluated by IR, AES, and SIMS analyses. The SiO2/Si interface was investigated by the degree of atomic dimension using TEM. As a result, it was found that the overall interface could be regarded as flat but it had local dents. After annealing, a transition region of one or two atom layers in thickness existed at the interface. It was found that the electrical properties of the annealed anodic oxide were comparable with those of an oxide film grown thermally by the MOS C‐V measurement. The input/output characteristics of an MOSFET with a gate oxide formed by this anodic oxide indicated that the anodic oxide formed at low temperature could be used for electronic devices.

Modified Constant‐Current Anodization: A Promising Mechanism for Minimizing Interface States in the Silicon/Silicon‐Oxide System of an Anodic Oxide Film

“…It offers a better interface with lower current density which is also true for large-size anodic oxides. 13 Nomura et al,24 in their study, have shown thai Nit of anodic oxides grown by 3 mA/cm 2 can be reduced satisfactorily if the oxide is subjected to successive constant voltage-stage of anodization and annealing. Since for a 6 ---> 3 mA/cm z the final current density is 3 mA/cm 2, it is more likely that if this oxide is treated in the same way large-size oxides had been treated, it will exhibit a superior interface.…”