Interface engineering of a ZrO2/SiO2/Si layered structure by in situ reoxidation and its oxygen-pressure-dependent thermal stability

Abstract

Reactions at ${\mathrm{ZrO}}_2/{\mathrm{SiO}}_2/\mathrm{Si}$ interfaces during fabrication and postannealing have been studied in detail. The layered structures were fabricated by deposition of a thin Zr layer on a chemical oxide, followed by oxidation in an UHV chamber without air exposure (i.e., in situ reoxidation). On-line x-ray photoelectron spectroscopy was used to show that in situ reoxidation can be used for precisely designing interfacial structures. It was found that the thermal stability of ${\mathrm{ZrO}}_2/{\mathrm{SiO}}_2/\mathrm{Si}$ interfaces crucially depends on oxygen ambient; that is, while the interfaces are stable up to 900 °C under UHV conditions, annealing in ${\text{1×10}}^{\text{−4}} \mathrm{Torr}$ oxygen results in formation of interfacial Zr silicate. Moreover, the ${\mathrm{ZrO}}_{\mathrm{2}}$ overlayer was found to accelerate the interfacial oxidation reaction.