Investigation of higher breakdown voltages of multi layer insulating films by voltage clamp phenomenon

The voltage clamp phenomenon was investigated by measuring the dielectric characteristics of Ta₂O₅/SrTiO₃ and SiO₂/Ta₂O₅ multilayer films. These films consist of alternating high- and low-dielectric-constant layers. It was attempted to raise the between voltage of the multilayer films by lowering the resistivity of the insulating film with the low dielectric constant in a high electric field to a value near its breakdown strength. In this way, applied voltages higher than the breakdown field strength of the low-dielectric-constant film can be applied to the high-dielectric-constant insulating, and shared voltages of the former can be kept constant, as if in a voltage clamp, during any further applied voltage rise. The Ta₂O₅/SrTiO₃ film was found to exhibit voltage clamp, resulting in higher breakdown strengths, but the SiO₂/Ta₂O₅ film did not, and it was necessary to improve the deposition method used for the SiO₂ film. A self-healing breakdown characteristic was found to be necessary for the multilayer insulating film to attain higher breakdown strengths due to the voltage clamp phenomenon