Dielectric isolation type semiconductor device

摘要

A dielectric isolation type semiconductor device can achieve high dielectric resistance while preventing the dielectric strength thereof from being limited depending on the thickness of a dielectric layer and the thickness of a first semiconductor layer. A drift N^- region is bonded to a semiconductor substrate through a buried oxide film to from a high withstand-voltage device in the drift N^- region. A first field plate is formed on the drift N^- region in the vicinity of a drain electrode. A first high silicon concentration region composed of a buried N⁺ region is formed in a porous oxide film region forming a part of the buried oxide film at a location right under the drain electrode. The drain electrode and the first field plate are electrically connected to the first high silicon concentration region through a drain N^- well region.