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 switching device including: a body of semiconductor material, which has a first conductivity type and is delimited by a front surface; a contact layer of a first conductive material, which extends in contact with the front surface; and a plurality of buried regions, which have a second conductivity type and are arranged within the semiconductor body, at a distance from the contact layer.

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.

Provided is a semiconductor device manufacturing method. The device has a substrate including one and another surfaces. A first semiconductor region of a first conductivity type is formed in the substrate. A second conductivity type, second semiconductor region is provided in a first surface layer, that includes the one surface, of the substrate. A first electrode is in contact with the second semiconductor region to form a junction therebetween. A first conductivity type, third semiconductor region is provided in a second surface layer, that includes the another surface, of the substrate. The third semiconductor region has a higher impurity concentration than the first semiconductor region. A fourth semiconductor region of the second conductivity type is provided in the first semiconductor region at a location deeper than the third semiconductor region from the another surface. A second electrode is in contact with the third semiconductor region.

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.

A vertical drift metal-oxide-semiconductor (VDMOS) transistor with improved contact to source and body regions, and a method of fabricating the same. A masked ion implant of the source regions into opposite-type body regions defines the locations of body contact regions, which are implanted subsequently with a blanket implant. The surface of the source regions and body contact regions are silicide clad, and an overlying insulator layer deposited and planarized. Contact openings are formed through the planarized insulator layer, within which conductive plugs are formed to contact the metal silicide, and thus the source and body regions of the device. A metal conductor is formed overall to the desired thickness, and contacts the conductive plugs to provide bias to the source and body regions.

A low dynamic resistance, low capacitance diode of a semiconductor device includes a heavily-doped n-type substrate. A lightly-doped n-type layer 1 micron to 5 microns thick is disposed on the n-type substrate. A lightly-doped p-type layer 3 microns to 8 microns thick is disposed on the n-type layer. The low dynamic resistance, low capacitance diode, of the semiconductor device includes a p-type buried layer, with a peak dopant density above 110.sup.17 cm.sup.3, extending from the p-type layer through the n-type layer to the n-type substrate. The low dynamic resistance, low capacitance diode also includes an n-type region disposed in the p-type layer, extending to a top surface of the p-type layer.

An integrated circuit and method having an extended drain MOS transistor with a buried drift region, a drain diffused link, a channel diffused link, and an isolation link which electrically isolated the source, where the isolation diffused link is formed by implanting through segmented areas to dilute the doping to less than two-thirds the doping in the drain diffused link.

A semiconductor device is provided. The semiconductor device includes a substrate; an epitaxial layer; a first conductive type first well region disposed in the substrate and the epitaxial layer; a second conductive type first buried layer and a second conductive type second buried layer disposed at opposite sides of the first conductive type first well region, respectively; a first conductive type second well region disposed in the epitaxial layer and being in direct contact with the first conductive type first well region; a second conductive type third buried layer disposed in the first conductive type first well region and/or the first conductive type second well region; a second conductive type doped region disposed in the first conductive type second well region; a gate structure; a drain contact plug; and a source contact plug.

A method for forming an integrated circuit includes forming a first guard ring around at least one transistor over a substrate. The method further includes forming a second guard ring around the first guard ring. The method further includes forming a first doped region adjacent to the first guard ring, the first doped region having a first dopant type. The method further includes forming a second doped region adjacent to the second guard ring, the second doped region having a second dopant type.