Patent ID: 7795674

Claim:
A semiconductor device, comprising: a semiconductor substrate of a first conductivity type and first dopant concentration and having a surface; a first well of the first conductivity type and second dopant concentration located in the substrate; a second well of a second, opposite, conductivity type and third dopant concentration located in the substrate, separated from or in contact with the first well and forming a PN junction with the first well or the substrate, which PN junction extends substantially to the surface; a third region of the second conductivity type and a fourth dopant concentration, located in the substrate, extending substantially to the surface and laterally separated from the first well, and adapted when biased to form a space charge region at least partly in the substrate or the first well or in a combination thereof; a first gate overlying a part of the first well or a part of the substrate between the first and second wells or both; a second gate spaced apart from the first gate and overlying at least a part of the second well; and an ohmic contact to the substrate within the space charge region and electrically coupled to the second gate.