Electronic properties and reliability of the silicon dioxide / silicon carbide interface

Abstract

Silicon carbide has been preferred over other wide band-gap semiconductors for high power applications because of its unique ability to grow a thermal oxide, challenges lie in the quality of the dielectric and of the SiO2/SiC interface.

This thesis focuses on the electrical properties and the reliability of the oxide and its interface with silicon carbide. In particular, the effects of processing parameters, such as implant activation, oxidation conditions (partial pressure), and post-oxidation anneal (nitridation), are considered. Tests are performed on metal-oxide-semiconductor (MOS) capacitors probed by capacitance-voltage measurements (CV), carrier injection (tunneling, photo-emission, irradiation), and time-dependent dielectric breakdown (TDDB). The most important new finding is that nitrogen, required for passivating the complex SiO2/SiC interface, can be detrimental to its reliability. Indeed, nitridation leads to the formation of hole traps, yielding large voltage instabilities.