An SiC semiconductor device has a p type region including a low concentration region and a high concentration region filled in a trench formed in a cell region. A p type column is provided by the low concentration region, and a p.sup.+ type deep layer is provided by the high concentration region. Thus, since a SJ structure can be made by the p type column and the n type column provided by the n type drift layer, an on-state resistance can be reduced. As a drain potential can be blocked by the p.sup.+ type deep layer, at turnoff, an electric field applied to the gate insulation film can be alleviated and thus breakage of the gate insulation film can be restricted. Therefore, the SiC semiconductor device can realize the reduction of the on-state resistance and the restriction of breakage of the gate insulation film.

According to one embodiment, a method for manufacturing a semiconductor device comprises making a first opening, ion-implanting an impurity of a second conductivity type, and forming a third semiconductor layer of the second conductivity type. The first opening is made in a second semiconductor layer. The second semiconductor layer is provided on a first semiconductor layer. The first opening extends in a second direction. A dimension in a third direction of an upper part of the first opening is longer than a dimension in the third direction of a lower part of the first opening. The third direction is perpendicular to the first direction and the second direction. The impurity of the second conductivity type is ion-implanted into a side surface of the lower part of the first opening. The third semiconductor layer of the second conductivity type is formed in an interior of the first opening.

In one embodiment, a power MOSFET vertically conducts current. A bottom electrode may be connected to a positive voltage, and a top electrode may be connected to a low voltage, such as a load connected to ground. A gate and/or a field plate, such as polysilicon, is within a trench. The trench has a tapered oxide layer insulating the polysilicon from the silicon walls. The oxide is much thicker near the bottom of the trench than near the top to increase the breakdown voltage. The tapered oxide is formed by implanting nitrogen into the trench walls to form a tapered nitrogen dopant concentration. This forms a tapered silicon nitride layer after an anneal. The tapered silicon nitride variably inhibits oxide growth in a subsequent oxidation step.

A semiconductor device according to an embodiment includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a third semiconductor layer of the first conductivity type, a fourth semiconductor layer of the second conductivity type, a first electrode connected to the second semiconductor layer and the fourth semiconductor layer, a second electrode facing the second semiconductor layer with an insulating film interposed, a fifth semiconductor layer of the second conductivity type, a sixth semiconductor layer of the first conductivity type, a seventh semiconductor layer of the second conductivity type, a third electrode connected to the fifth semiconductor layer and the seventh semiconductor layer, and a fourth electrode facing the fifth semiconductor layer with an insulating film interposed.

A vertical power switching device, such as a vertical superjunction metal-oxide-semiconductor field-effect-transistor (MOSFET), in which termination structures in the corners of the integrated circuit are stretched to efficiently shape the lateral electric field. Termination structures in the device include such features as doped regions, field plates, insulator films, and high-voltage conductive regions and elements at the applied substrate voltage. Edges of these termination structures are shaped and placed according to a 2.sup.nd-order smooth, non-circular analytic function so as to extend deeper into the die corner from the core region of the device than a constant-distance path. Also disclosed are electrically floating guard rings in the termination region, to inhibit triggering of parasitic p-n-p-n structures.

Various improvements in vertical transistors, such as IGBTs, are disclosed. The improvements include forming periodic highly-doped p-type emitter dots in the top surface region of a growth substrate, followed by growing the various transistor layers, followed by grounding down the bottom surface of the substrate, followed by a wet etch of the bottom surface to expose the heavily doped p+ layer. A metal contact is then formed over the p+ layer. In another improvement, edge termination structures utilize p-dopants implanted in trenches to create deep p-regions for shaping the electric field, and shallow p-regions between the trenches for rapidly removing holes after turn-off. In another improvement, a dual buffer layer using an n-layer and distributed n+ regions improves breakdown voltage and saturation voltage. In another improvement, p-zones of different concentrations in a termination structure are formed by varying pitches of trenches. In another improvement, beveled saw streets increase breakdown voltage.

An insulated gate silicon carbide semiconductor device includes: a drift layer of a first conductivity type on a silicon carbide substrate of 4H type with a {0001} plane having an off-angle of more than 0 as a main surface; a first base region; a source region; a trench; a gate insulating film; a protective diffusion layer; and a second base region. The trench sidewall surface in contact with the second base region is a surface having a trench off-angle of more than 0 in a <0001> direction with respect to a plane parallel to the <0001> direction. The insulated gate silicon carbide semiconductor device can relieve an electric field of a gate insulating film and suppress an increase in on-resistance and provide a method for manufacturing the same.

There are disclosed herein various implementations of an insulated-gate bipolar transistor (IGBT) having a deep superjunction structure. Such an IGBT includes a drift region having a first conductivity type situated over a collector having a second conductivity type. The IGBT also includes a gate trench extending through a base having the second conductivity type into the drift region. In addition, the IGBT includes a deep superjunction structure situated under the gate trench. The deep superjunction structure includes one or more first conductivity regions having the first conductivity type and two or more second conductivity region having the second conductivity type, the one or more first conductivity regions and the two or more second conductivity regions configured to substantially charge-balance the deep superjunction structure.

A HEMT device comprising a M-plane III-Nitride material substrate, a p-doped epitaxial layer of III-Nitride material grown on said substrate; a recess etched in said p-doped epitaxial layer, the recess having a plane wall parallel to a polar plane of the III-Nitride material; a carrier carrying layer formed on said plane wall of the recess; a carrier supply layer formed on said at least one carrier carrying layer, such that a 2DEG region is formed in the carrier carrying layer at the interface with the carrier supply layer along said plane wall of the recess; a doped source region formed at the surface of said p-doped epitaxial layer such that the doped source region is separated from said 2DEG region by a channel region; a gate insulating layer formed on the channel region; and a gate contact layer formed on the gate insulating layer.

A semiconductor device includes a semiconductor substrate in which an active region and an edge termination region are defined, a semiconductor element formed in the active region, and first to fourth P layers formed in a region spanning from an edge portion of the active region to the edge termination region in the surface of the semiconductor substrate. The first to fourth P layers respectively have surface concentrations P(1) to P(4) that decrease in this order, bottom-end distances D(1) to D(4) that increase in this order, and distances B(1) to B(4) to the edge of the semiconductor substrate that increase in this order. The surface concentration P(4) is 10 to 1000 times the impurity concentration of the semiconductor substrate, and the bottom-end distance D(4) is in the range of 15 to 30 m.