A device includes a buried oxide layer disposed on a substrate, a first region disposed on the buried oxide layer and a first ring region disposed in the first region. The first ring region includes a portion of a guardring. The device further includes a first terminal region disposed in the first ring region, a second ring region disposed in the first region and a second terminal region disposed in the second ring region. The first terminal region is connected to an anode and the second terminal region is connected to a cathode. The first region has a graded doping concentration. The first region, the second ring region and the second terminal region have a first conductivity type, and the first ring region and the first terminal region have a second conductivity type. The first conductivity type is different from the second conductivity type.

High voltage semiconductor devices are described herein. An exemplary semiconductor device includes a first doped region and a second doped region disposed in a substrate. The first doped region and the second doped region are oppositely doped and adjacently disposed in the substrate. A first isolation structure and a second isolation structure are disposed over the substrate, such that each are disposed at least partially over the first doped region. The first isolation structure is spaced apart from the second isolation structure. A resistor is disposed over a portion of the first isolation structure and electrically coupled to the first doped region. A field plate disposed over a portion of the second doped region and electrically coupled to the second doped region.

A method can be used to make a semiconductor device. A number of projecting regions are formed over a first semiconductor layer that has a first conductivity type. The first semiconductor layer is located on an insulating layer that overlies a semiconductor substrate. The projecting regions are spaced apart from each other. Using the projecting regions as an implantation mask, dopants having a second conductivity type are implanted into the first semiconductor layer, so as to form a sequence of PN junctions forming diodes in the first semiconductor layer. The diodes vertically extend from an upper surface of the first semiconductor layer to the insulating layer.

In a step, acceptor ions are implanted from a back surface of a semiconductor substrate. In a step, a wet process of immersing the semiconductor substrate in a chemical solution including hydrofluoric acid is performed, to introduce hydrogen atoms into the semiconductor substrate. In a step, proton radiation is provided to the back surface of the semiconductor substrate, to introduce hydrogen atoms into the semiconductor substrate and form radiation-induced defects. In a step, an annealing process is performed on the semiconductor substrate, to form hydrogen-related donors by reaction of the hydrogen atoms and the radiation-induced defects and reduce the radiation-induced defects.

A composite power element includes a substrate structure, an insulation layer, a dielectric layer, a MOSFET, and a Zener diode. The MOSFET is formed in a transistor formation region of the substrate structure. The Zener diode is formed in a circuit element formation region of the substrate structure, and includes a Zener diode doping structure that is formed in the substrate structure and is covered by the insulation layer. The Zener diode doping structure includes a first P-type doped region and a first N-type doped region that is formed on an inner side of the first P-type doped region. The Zener diode further includes a Zener diode metal structure that is formed on the dielectric layer and sequentially passes through the dielectric layer and the insulation layer to be electrically connected to the first P-type doped region and the first N-type doped region.

A bipolar semiconductor device includes at least a four-layer structure, a first main side with a first electrical contact, and a second main side with a second electrical contact separated from the first main side by at least a base layer of first conductivity type. A shorting layer of the first conductivity type is arranged on the second main side of the base layer. A third layer includes a patterned highly conductive material, such as metal and/or silicides, graphene, etc., and is deposited on the shorting. A fourth layer of the second conductivity type is arranged directly on the third layer, inserted between the shorting layer and the second electrical contact. This concept can be applied to any non-punch-through or punch-through reverse conducting IGBT designs, but is particularly effective for devices using thin wafers, and is also applicable to bipolar diodes in order to improve a soft recovery process.

A predetermined relational expression holds where a first distance along the in-plane direction from a channel of the first semiconductor layer to a third semiconductor layer that is the other of the collector layer and the cathode layer is designated as W, a second distance from the channel of the first semiconductor layer to the second semiconductor layer is designated as S, and a diffusion coefficient and a lifetime of a part of the semiconductor substrate between the channel of the first semiconductor layer and the third semiconductor layer are designated as D and τ, respectively.

A semiconductor device has transistor portions and diode portions. The transistor portions have a semiconductor substrate of a first conductivity type, a first semiconductor region of a second conductivity type, second semiconductor regions of the first conductivity type, gate insulating films, gate electrodes, a first semiconductor layer of the first conductivity type, a third semiconductor region of the second conductivity type, a first electrode, and a second electrode. The diode portions have the semiconductor substrate, the first semiconductor region, the first semiconductor layer, a fourth semiconductor region of the first conductivity type, the first electrode, and the second electrode. The first semiconductor layer has a predetermined region, a depth of the predetermined region from a second main surface of the semiconductor substrate is greater than a depth of a region of the first semiconductor layer excluding the predetermined region, from the second main surface of the semiconductor substrate.

A diode includes an anode electrode layer; a cathode electrode layer; a buffer layer of a first conductivity type formed between the anode electrode layer and the cathode electrode layer in a region extending to a location at a distance of 30 μm or more from the cathode electrode layer; a first semiconductor layer of the first conductivity type formed in a region between the anode electrode layer and the cathode electrode layer, and being in contact with the buffer layer of the first conductivity type; and a second semiconductor layer of a second conductivity type formed in a region between the anode electrode layer and the first semiconductor layer of the first conductivity type. The carrier concentration in the first semiconductor layer is lower than the carrier concentration in the buffer layer. The carrier concentration in the buffer layer is less than 1×10.sup.15 cm.sup.−3.

A semiconductor device includes a semiconductor substrate, an element region including an active element formed at the semiconductor substrate, a channel stopper formed in an outer peripheral region of the semiconductor substrate, and an insulating film that covers a surface of the semiconductor substrate and that has a first contact hole by which the channel stopper is exposed. The semiconductor device further includes a first field plate, a second field plate, and an equipotential ring electrode. The first field plate is formed on the insulating film, and faces the semiconductor substrate between the channel stopper and the element region through the insulating film. The second field plate is embedded in the insulating film, and faces the semiconductor substrate between the first field plate and the channel stopper through the insulating film. The equipotential ring electrode is formed along an outer peripheral region of the semiconductor substrate. The equipotential ring electrode is connected to the channel stopper through the first contact hole, and is connected to the first field plate, and is connected to the second field plate through a second contact hole formed in the insulating film.