Stress at the Si—SiO2interface and its relationship to interface states

The existence and origin of the interfacial stress between thermally grown silicon dioxide and single-crystal silicon are demonstrated. An oxide grown at about 1200°C will be under about 50 000 psi compressive stress. Interface state density is shown to be correlated to the magnitude of this compressive stress. An attempt is made to explain the correlation using a vacancy model for the interface states. The relationship is such that the higher the stress the lower the interface state density. It has been shown that the interface state density is inversely related to the dislocation density, therefore the vacancy model. The information and treatment are considered to apply to all solid-solid interfaces; the paper is therefore of more general interest and not restricted to the silicon-silicon dioxide system alone.