Patent ID: 7834421

Claim:
An isolated diode formed in a P-type semiconductor substrate, the substrate not comprising an epitaxial layer, the isolated diode comprising: an N-type floor isolation region submerged in the substrate; a trench extending from a surface of the substrate at least to the floor isolation region, the trench having a central portion filled with a conductive material and a dielectric material lining the walls of the trench, the conductive material providing electrical contact from the floor isolation region to the surface of the substrate, the trench and the floor isolation region together forming an isolated pocket of the substrate; and a P-type anode region in the isolated pocket, the anode region extending from the surface of the substrate to the floor isolation region, the anode region comprising a shallow portion and a deep portion, the shallow portion being located adjacent the surface of the substrate, the deep portion being located below the shallow portion, the shallow portion having a first doping concentration, the deep portion having a second doping concentration, the second doping concentration being greater than the first doping concentration.