US Patent 7911022 Isolation structure in field device

A semiconductor device. The semiconductor device comprises an isolation structure and two heavily doped regions of a second conductivity type spaced apart from each other by the isolation structure. The isolation structure comprises an isolation region in a semiconductor substrate and a heavily doped region of the first conductivity type. The isolation region has an opening and the heavily doped region of the first conductivity type is substantially surrounded by the opening of the isolation region.