## LSU Historical Dissertations and Theses

1990

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Electrical and Computer Engineering

Pratul K. Ajmera

#### Abstract

A technique for low temperature oxidation of silicon in dry oxygen ambient at temperatures between 25$\sp\circ$C to 500$\sp\circ$C using negative point-to-plane corona discharge is developed. The oxidation rate is a strong function of temperature is found to increase significantly in comparison with the conventional thermal oxidation rate. For the thicker films, the refractive index of the grown oxide layer approaches the value obtained for high temperature thermally grown oxide. The effects of some independent process parameters such as time, temperature, and ion current on the oxidation of silicon are studied. The electrical quality of the grown oxide film is investigated. The C-V characteristic curves of the MOS capacitors of the oxide grown by this technique show shifts in the flat-band voltage. The shift of flat-band voltage is found to be a function of oxidation temperature and the corona current during the oxidation process. The leakage current of the capacitor fabricated negative and positive gate bias voltages. When the aluminum plate of the capacitor is biased negative with respect to the substrate, the measured value of the current is substantially higher than the measured current value under positive bias. The mechanism of the leakage current for the oxide grown at room temperature is studied. The interface trap density spectrum in the range of 5 $\times$ 10$\sp{10}$ to 5 $\times$ 10$\sp{13}$ cm$\sp{-2}$ (eV)$\sp{-1}$ is obtained for the oxide grown at 400$\sp\circ$C for one hour with 1 cm electrode distance at 1 atm pressure in dry oxygen ambient. The oxide film grown by this method has a potential for application in device fabrication technology. The application of the Nicollian and Reisman oxidation model indicates that the oxidation process at a given temperature under corona discharge is more strongly surface reaction controlled than thermal oxidation of silicon. The observed high rate of oxidation of silicon by corona discharge in a dry oxygen ambient may be associated with stress relief and an increase in the viscous flow of the grown SiO$\sb2$ film during oxidation.

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