Microvoids at theSiO2/Si interface

Abstract

A variable-energy positron beam was used to study device-quality ${\mathrm{SiO}}_2$ (≊50-nm thick) grown thermally on the Si(100) surface. The unusual observation of ortho-positronium 3γ decay at the interface demonstrates that microvoids >1 nm in size are present, most likely as a consequence of the thermal oxidation process. Other interfacial defects were also observed, illustrating the sensitivity of positron studies for studying interfacial properties.