A device includes a semiconductor substrate, a buried doped isolation layer disposed in the semiconductor substrate to isolate the device, a drain region disposed in the semiconductor substrate and to which a voltage is applied during operation, and a depletion region disposed in the semiconductor substrate and having a conductivity type in common with the buried doped isolation barrier and the drain region. The depletion region reaches a depth in the semiconductor substrate to be in contact with the buried doped isolation layer. The depletion region establishes an electrical link between the buried doped isolation layer and the drain region such that the buried doped isolation layer is biased at a voltage level lower than the voltage applied to the drain region.

A semiconductor device include a substrate, a first well region formed in the substrate, a first isolation structure formed in the first well region, a Schottky barrier structure formed on the first well region, and a plurality of assist structures formed on the first well region. The substrate includes a first conductivity type, the first well region includes a second conductivity type, and the first conductivity type and the second conductivity type are complementary to each other. The assist structures physically contact the first well region.

A silicon carbide field effect transistor includes a silicon carbide substrate, an n-type drift layer, a p-type epitaxy layer, a source region, a trench gate, at least one p-type doped region, a source, a dielectric layer and a drain. The p-type doped region is disposed at the n-type drift layer to be adjacent to one lateral side of the trench gate, and includes a first doped block and a plurality of second doped blocks arranged at an interval from the first doped block towards the silicon carbide substrate. Further, a thickness of the second doped blocks does not exceed 2 um. Accordingly, not only the issue of limitations posed by the energy of ion implantation is solved, but also an electric field at a bottom and a corner of the trench gate is effectively reduced, thereby enhancing the reliability of the silicon carbide field effect transistor.

An integrated circuit includes an active device formed in a semiconductor layer of a first conductivity type, a first guard ring of the first conductivity type formed in the semiconductor layer surrounding at least part of the active device; a second guard ring of the second conductivity type formed in the semiconductor layer surrounding the first guard ring and the active device and including comprising alternating first well regions of the first conductivity type and the second well regions of the second conductivity type, the first and second well regions being electrically shorted together and electrically coupled to a ground potential or floating; and a third guard ring of the first conductivity type formed in the semiconductor layer surrounding the second guard ring. The first and third guard rings do not receive direct electrical connection.

A semiconductor device includes a diode region and an IGBT region. The diode region includes a front side anode region, an n-type diode barrier region, an n-type diode pillar region reaching the diode barrier region through the front side anode region, and a p-type back side anode region separated from the front side anode region by the diode barrier region. The IGBT region includes a front side body region, an n-type IGBT barrier region, and a back side body region separated from the front side body region by the IGBT barrier region. When a gate-off voltage is applied to a gate electrode, a resistance between the IGBT barrier region and the emitter electrode is higher than a resistance between the diode barrier region and the anode electrode.

In one general aspect, an apparatus can include a silicon carbide (SiC) device can include a gate dielectric, a first doped region having a first conductivity type, a body region of the first conductivity type, and a second doped region having a second conductivity type. The second doped region has a first portion disposed between the first doped region and the body region, and the second doped region has a second portion disposed between the first doped region and the gate dielectric.

A semiconductor device and a fabrication method are provided. The semiconductor device is fabricated by providing a substrate with a device area surrounded by a seal ring area, forming a buried deep-well layer in the substrate of the seal ring area, forming a first well region and a second well region in the substrate above the buried deep-well layer with the first well region surrounding the device area and the second well region surrounding the first well region, forming a heavily doped region in the substrate above the buried deep-well layer and between the first well region and the second well region, and forming a seal ring structure connecting to the heavily doped region. The buried deep-well layer, the first well region, and the second well region all have a first doping type while the heavily doped region and the substrate have a second doping type.

A semiconductor device includes a semiconductor layer made of a wide bandgap semiconductor and including a gate trench; a gate insulating film formed on the gate trench; and a gate electrode embedded in the gate trench to be opposed to the semiconductor layer through the gate insulating film. The semiconductor layer includes a first conductivity type source region; a second conductivity type body region; a first conductivity type drift region; a second conductivity type first breakdown voltage holding region; a source trench passing through the first conductivity type source region and the second conductivity type body region from the front surface and reaching a drain region; and a second conductivity type second breakdown voltage region selectively formed on an edge portion of the source trench where the sidewall and the bottom wall thereof intersect with each other in a parallel region of the source trench.

A semiconductor substrate having a first main surface and a transistor cell includes a drift region, a body region between the drift region and the first main surface, an active trench at the first main surface extending into the drift region, a gate insulating layer at sidewalls and a bottom side of the active trench, a gate conductive layer in the active trench, a source region in the body region, and adjacent to the active trench, a body trench at the first main surface extending into the drift region, the body trench being adjacent to the body region and to the drift region, an insulating layer at sidewalls and at a bottom side of the body trench, the insulating layer being asymmetric with respect to an axis extending perpendicular to the first main surface at a center of the body trench, and a conductive layer in the body trench.

A silicon carbide semiconductor device includes a silicon carbide layer having a first main surface and a second main surface opposite to the first main surface. In the second main surface of the silicon carbide layer, a trench having a depth in a direction from the second main surface toward the first main surface is provided, and the trench has a sidewall portion where a second layer and a third layer are exposed and a bottom portion, where a first layer is exposed. A position of the bottom portion of the trench in a direction of depth of the trench is located on a side of the second main surface relative to a site located closest to the first main surface in a region where the second layer and the first layer are in contact with each other, or located as deep as the site in the direction of depth.