US Patent 7700977 Integrated circuit with a subsurface diode

An integrated circuit includes a first and second diode connected in parallel. The first diode has a first breakdown voltage and has first P type region and first N type region adjacent to each other at the surface of the substrate of a substrate to form a lateral diode. The second diode has a second breakdown voltage less than the first breakdown voltage and has a second P type region and second N type region lateral adjacent to each other in the substrate to form a lateral diode below the surface The first and second N type regions overlap and the first and second P type region being electrically connected whereby the first and second diodes are in parallel.