First p.sup.+-type regions are provided directly beneath trenches, separate from a p-type base region and facing bottoms of the trenches in a depth direction. The first p.sup.+-type regions are exposed at the bottoms of the trenches and are in contact with a gate insulating film at the bottoms of the trenches. Second p.sup.+-type regions are each provided between (mesa region) adjacent trenches, separate from the first p.sup.+-type regions and the trenches. Drain-side edges of the second p.sup.+-type regions are positioned closer to a source side than are drain-side edges of the first p.sup.+-type regions. In each mesa region, an n.sup.+-type region is provided separate from the first p.sup.+-type regions and the trenches. The n.sup.+-type regions are adjacent to and face the second p.sup.+-type regions in the depth direction.

A main semiconductor device element has first and second p.sup.+-type high-concentration regions that mitigate electric field applied to bottoms of trenches. The first p.sup.+-type high-concentration regions are provided separate from p-type base regions, face the bottoms of the trenches in a depth direction, and extend in a linear shape in a first direction that is a same direction in which the trenches extend. Between adjacent trenches of the trenches, the second p.sup.+-type high-concentration regions are provided scattered in the first direction, separate from the first p.sup.+-type high-concentration regions and the trenches and in contact with the p-type base regions. Between the second p.sup.+-type high-concentration regions adjacent to one another in the first direction, n-type current spreading regions or n.sup.+-type high-concentration regions having an impurity concentration higher than that of the n-type current spreading regions are provided in contact with the second p.sup.+-type high-concentration regions.

A semiconductor structure is provided. The semiconductor structure includes a substrate, a first doped region formed in the substrate, a second doped region formed in the substrate and surrounding the first doped region, and a plurality of strip third doped regions formed in the substrate and located underneath the first doped region and the second doped region. In addition, the first doped region has a doping type which is the opposite of that of the second doped region. The strip third doped region has a doping type which is the same as that of the second doped region.

Power semiconductor devices comprise a wide bandgap semiconductor layer structure, a gate pad on the wide bandgap semiconductor layer structure, a plurality of gate fingers on the wide bandgap semiconductor layer structure, and a plurality of lumped gate resistors electrically coupled between the gate pad and the gate fingers.

Power semiconductor devices comprise a gate pad, a plurality of gate fingers, and a first gate resistor and a first switch that are coupled between the gate pad and the gate fingers.

A semiconductor device includes a semiconductor part, a first electrode at a back surface of the semiconductor part; a second electrode at a front surface of the semiconductor part; third and fourth electrodes provided between the semiconductor part and the second electrode. The third and fourth electrodes are arranged in a first direction along the front surface of the semiconductor part. The third electrode is electrically insulated from the semiconductor part by a first insulating film. The third electrode is electrically insulated from the second electrode by a second insulating film. The fourth electrode is electrically insulated from the semiconductor part by a third insulating film. The fourth electrode is electrically isolated from the third electrode. the third and fourth electrodes extend into the semiconductor part. The fourth electrode includes a material having a larger thermal conductivity than a thermal conductivity of a material of the third electrode.

A semiconductor device includes a semiconductor layer structure of a wide band-gap semiconductor material. The semiconductor layer structure includes a drift region having a first conductivity type and a well region having a second conductivity type. A plurality of segmented gate trenches extend in a first direction in the semiconductor layer structure. The segmented gate trenches include respective gate trench segments that are spaced apart from each other in the first direction with intervening regions of the semiconductor layer structure therebetween. Related devices and fabrication methods are also discussed.

Semiconductor devices and methods of forming the devices are provided. Semiconductor devices include a semiconductor layer structure comprising a trench in an upper surface thereof, a dielectric layer in a lower portion of the trench, and a gate electrode in the trench and on the dielectric layer opposite the semiconductor layer structure. The trench may include rounded upper corner and a rounded lower corner. A center portion of a top surface of the dielectric layer may be curved, and the dielectric layer may be on opposed sidewalls of the trench. The dielectric layer may include a bottom dielectric layer on a bottom surface of the trench and on lower portions of the sidewalls of the trench and a gate dielectric layer on upper portions of the sidewalls of the trench and on the bottom dielectric layer.

A semiconductor device comprises a substrate, a semiconductor layer formed on the substrate; and a high-voltage termination. The high-voltage termination includes a plurality of floating field rings, a deep trench and a dielectric material is disposed within the deep trench. The plurality of floating field rings are formed in the semiconductor layer and respectively disposed around a region of the semiconductor layer. The deep trench is formed in the semiconductor layer and concentrically disposed around an outermost floating field ring of the plurality of floating field rings. The high-voltage termination may also include a field plate disposed over the floating field rings, the deep trench, or both.

A process of forming a gate insulating film in a silicon carbide semiconductor device. The process includes performing a first stage of a nitriding heat treatment by a gas containing oxygen and nitrogen, followed by depositing an oxide film, and then performing a second stage of the nitriding heat treatment by a gas containing nitric oxide and nitrogen. The amount of nitrogen at the treatment starting point of the first stage of the nitriding heat treatment is greater than the amount of nitrogen at the treatment starting point of the second stage of the nitriding heat treatment. The amount of nitrogen at the treatment ending point of the second stage of the nitriding heat treatment is greater than the amount of nitrogen at the treatment ending point of the first stage of the nitriding heat treatment.