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.

A technique of reducing the manufacturing cost of a semiconductor device is provided, There is provided a method of manufacturing a semiconductor device comprising an ion implantation process of implanting at least one of magnesium and beryllium by ion implantation into a first semiconductor layer that is mainly formed from a group III nitride; and a heating process of heating the first semiconductor layer in an atmosphere that includes an anneal gas of at least one of magnesium and beryllium, after the ion implantation process.

A trench IGBT includes a floating P well and a floating N+ well that extends down into the floating P well. A bottom surface of the floating P well has a novel waved contour so that it has thinner portions and thicker portions. When the IGBT is on, electrons flow from an N+ emitter, vertically through a channel along a trench sidewall, and to an N type drift layer. Additional electrons flow through the channel but then pass under the trench, through the floating P well to the floating N+ well, and laterally through the floating N+ well. NPN transistors are located at thinner portions of the floating P type well. The NPN transistors inject electrons from the floating N+ type well down into the N drift layer. The extra electron injection reduces V.sub.CE(SAT). The waved contour can be made without adding any masking step to an IGBT manufacturing process.

A semiconductor device includes: a semiconductor substrate having a main surface; a first insulating film formed in a convex shape and provided on the main surface of the semiconductor substrate; a first diffusion layer formed on the semiconductor substrate and provided to surround the first insulating film formed in a convex shape, the first diffusion layer being different in conductivity type from the semiconductor substrate; a first conductive layer formed so as to extend across the first insulating film formed in a convex shape, the first conductive layer forming a fuse element; and a second insulating film provided on the first conductive layer.

A method of manufacturing a semiconductor device includes forming a first trench in a semiconductor substrate from a first side, forming a semiconductor layer adjoining the semiconductor substrate at the first side, the semiconductor layer capping the first trench at the first side, and forming a contact at a second side of the semiconductor substrate opposite to the first side.

A semiconductor device includes a semiconductor region with a charge balance region on a junction blocking region, the junction blocking region having a lower doping concentration. The junction blocking region extends between a pair of trench structures in cross-sectional view. The trench structures are provided in the semiconductor region and include at least one insulated electrode. In some embodiments, the semiconductor device further includes a first doped region disposed between the pair of trench structures. The semiconductor device may further include one or more features configured to improve operating performance. The features include a localized doped region adjoining a lower surface of a first doped region and spaced apart from the trench structure, a notch disposed proximate to the lower surface of the first doped region, and/or the at least one insulated electrode configured to have a wide portion adjoining a narrow portion.

A method of manufacturing a semiconductor device includes forming electrode trenches in a semiconductor substrate between semiconductor mesas that separate the electrode trenches, the semiconductor mesas including portions of a drift layer of a first conductivity type and a body layer of a second, complementary conductivity type between a first surface of the semiconductor substrate and the drift layer, respectively. The method further includes forming isolated source zones of the first conductivity type in the semiconductor mesas, the source zones extending from the first surface into the body layer. The method also includes forming separation structures in the semiconductor mesas between neighboring source zones arranged along an extension direction of the semiconductor mesas, the separation structures forming partial or complete constrictions of the semiconductor mesa, respectively.

A performance of a semiconductor device is improved. A semiconductor device includes two element portions and an interposition portion interposed between the two element portions. The interposition portion includes a p-type body region formed in a part of a semiconductor layer, the part being located between two trenches, and two p-type floating regions formed in two respective parts of the semiconductor layer, the two respective portions being located on both sides of the p-type body region via the two respective trenches. A lower end of the p-type floating region is arranged on a lower side with reference to a lower end of the p-type body region.

Proton irradiation is performed a plurality of times from rear surface of an n-type semiconductor substrate, which is an n.sup. drift layer, forming an n-type FS layer having lower resistance than the n-type semiconductor substrate in the rear surface of the n.sup. drift layer. When the proton irradiation is performed a plurality of times, the next proton irradiation is performed to as to compensate for a reduction in mobility due to disorder which remains after the previous proton irradiation. In this case, the second or subsequent proton irradiation is performed at the position of the disorder which is formed by the previous proton irradiation. In this way, even after proton irradiation and a heat treatment, the disorder is reduced and it is possible to prevent deterioration of characteristics, such as increase in leakage current. It is possible to form an n-type FS layer including a high-concentration hydrogen-related donor layer.

Semiconductor devices includes a thin epitaxial layer (nanotube) formed on sidewalls of mesas formed in a semiconductor layer. In one embodiment, a semiconductor device includes a first semiconductor layer, a second semiconductor layer formed thereon and of the opposite conductivity type, and a first epitaxial layer formed on mesas of the second semiconductor layer. An electric field along a length of the first epitaxial layer is uniformly distributed.