Combined bipolar-field effect transistor resurf devices

摘要

A combined bipolar-field effect transistor RESURF device includes a lightly-doped epitaxial buried layer of a first conductivity type located between a semiconductor substrate of the first conductivity type and an epitaxial surface layer of a second conductivity type opposite to that of the first. The doping concentration and thickness of the epitaxial surface layer are selected in accordance with the Reduced Surface Field (RESURF) technique. A highly-doped buried region of the second conductivity type is located beneath the base region of the device and is sandwiched between the epitaxial buried layer and the epitaxial surface layer. The advantages of such a device include a substantially reduced "on" resistance, a more compact and flexible configuration, improved switching characteristics, reduced base device current requirements, and improved isolation. The device may be further enhanced by providing a buried annular region of the first conductivity type around and in contact with the buried region, and a surface-adjoining annular region of the first conductivity may be provided adjacent the base region.