A semiconductor device and manufacturing method is disclosed. One embodiment provides a common substrate of a first conductivity type and at least two wells of a second conductivity type. A buried high resistivity region and at least an insulating structure is provided insulating the first well from the second well. The insulating structure extends through the buried high resistivity region and includes a conductive plug in Ohmic contact with the first semiconductor region. A method for forming an integrated semiconductor device is also provided.