Patent ID: 8884395

Claim:
A Schottky diode comprising: a deep well in a substrate; an isolation layer in the substrate; a guard ring of a first conductive type in the deep well comprising a first region and a second region and located at one side of the isolation layer; a well region of a second conductive type in the deep well and located at an opposite side of the isolation layer; a first electrode over the substrate and coupled to the deep well and the guard ring; and a second electrode over the substrate and coupled to the well region, wherein the first region of the guard ring overlaps with the isolation layer and the second region of the guard ring does not overlap with the isolation layer, wherein a width of a top surface of the first region is different from a width of a top surface of the second region, and wherein the well region comprises: a third impurity region having a third doping concentration being in contact with the second electrode; a second impurity region having a second doping concentration below the third impurity region; and a first impurity region having a first doping concentration below the second impurity region, wherein the third doping concentration is greater than the first doping concentration.