Abstract: First and second ranges of a silicon carbide film have an interface. The first range includes: a first breakdown voltage holding layer having a first conductivity type; and an outer edge embedded region provided at an interface in the outer edge portion and having a second conductivity type. The second range includes a second breakdown voltage holding layer having the first conductivity type. A semiconductor element is formed in the second range. The first range includes: a central section facing the semiconductor element in the central portion in a thickness direction; and an outer edge section facing the semiconductor element in the outer edge portion in the thickness direction. At the interface, the outer edge section includes a portion having an impurity concentration different from the impurity concentration of the central section.

Abstract: A silicon carbide semiconductor device has a silicon carbide substrate, a gate insulating film, and a gate electrode. Silicon carbide substrate includes a first impurity region having a first conductivity type, a well region being in contact with the first impurity region and having a second conductivity type which is different from the first conductivity type, and a second impurity region separated from the first impurity region by the well region and having the first conductivity type. The gate insulating film is in contact with the first impurity region and the well region. The gate electrode is in contact with the gate insulating film and is arranged opposite to the well region with respect to the gate insulating film. A specific on-resistance at a voltage which is half a gate driving voltage applied to the gate electrode is smaller than twice the specific on-resistance at the gate driving voltage.

Abstract: A semiconductor device employing silicon carbide, and the like are provided. In the semiconductor device, even when an electrode material and an upper electrode material are different, a problem does not take place at an interface at which these different types of metals are in contact with each other, thus obtaining high reliability in long-term use. The semiconductor device includes: a contact electrode 16 in contact with silicon carbides 14, 18; and an upper electrode 19 electrically conductive to the contact electrode. The contact electrode 16 is formed of an alloy including titanium, aluminum, and silicon, the upper electrode 19 is formed of aluminum or an aluminum alloy, and the upper electrode achieves the electric conduction to the contact electrode with the upper electrode making contact with the contact electrode.

Abstract: Each of first to third impurity regions of a silicon carbide substrate has a portion located on a flat surface of a first main surface. On the flat surface, a gate insulating film connects the first and third impurity regions to each other. On the flat surface, a first main electrode is in contact with the third impurity region. A second main electrode is provided on a second main surface. A side wall insulating film covers a side wall surface of the first main surface. The side wall surface is inclined by not less than 50° and not more than 80° relative to a {000-1} plane. In this way, a leakage current is suppressed in a silicon carbide semiconductor device.

Abstract: A silicon carbide substrate including a first layer having first conductivity type, a second layer having second conductivity type, and a third layer having the first conductivity type is formed. A trench provided with an inner surface having a side wall surface and a bottom surface is formed, the side wall surface extending through the third layer and the second layer and reaching the first layer, the bottom surface being formed of the first layer. A silicon film is formed to cover the bottom surface. A gate oxide film is formed on the inner surface by oxidation in the trench. The gate oxide film includes a first portion formed by oxidation of the silicon carbide substrate, and a second portion formed by oxidation of the silicon film on the bottom surface. Accordingly, a method for manufacturing a silicon carbide semiconductor device having a high breakdown voltage is provided.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate and an electrode. The silicon carbide substrates includes a first impurity region, a second impurity region, a third impurity region, a fourth impurity region, and an intermediate impurity region, the intermediate impurity region being interposed between the third impurity region and the fourth impurity region and having an impurity concentration that is lower than the concentration of a first conductivity type impurity in the third impurity region and that is lower than the concentration of a second conductivity type impurity in the fourth impurity region. The electrode is in contact with each of the third impurity region and the fourth impurity region on the main surface of the silicon carbide substrate. The concentration of the first conductivity type impurity in the third impurity region in contact with the electrode is not less than 5×1019 cm?3.

Abstract: A method for manufacturing a silicon carbide semiconductor device includes the following steps. A silicon carbide substrate is prepared. A first heating step of heating the silicon carbide substrate in an atmosphere of oxygen is performed. A second heating step of heating the silicon carbide substrate to a temperature of 1300° C. or more and 1500° C. or less in an atmosphere of gas containing nitrogen atoms or phosphorus atoms is performed after the first heating step. A third heating step of heating the silicon carbide substrate in an atmosphere of a first inert gas is performed after the second heating step. Thus, the silicon carbide semiconductor device in which threshold voltage variation is small, and a method for manufacturing the same can be provided.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate, a gate insulating film, a gate electrode, an interlayer insulating film, and a gate interconnection. The silicon carbide substrate includes: a first impurity region; a second impurity region provided on the first impurity region; and a third impurity region provided on the second impurity region so as to be separated from the first impurity region. A trench has a side portion and a bottom portion, the side portion extending to the first impurity region through the third impurity region and the second impurity region, the bottom portion being located in the first impurity region. When viewed in across section, the interlayer insulating film extends from above the third impurity region to above the gate electrode so as to cover the corner portion.

Abstract: A MOSFET includes: a substrate having a first trench formed therein, the first trench opening on a side of one main surface; a gate insulating film; and a gate electrode. The substrate includes an n type source region, a p type body region, an n type drift region, and a p type deep region making contact with the body region and extending to a region deeper than the first trench. The first trench is formed such that a distance between the wall surface and the deep region increases with increasing distance from the main surface of the substrate.

Abstract: A silicon carbide semiconductor device includes an element region and a guard ring region. A semiconductor element is provided in the element region. The guard ring region surrounds the element region in a plan view and has a first conductivity type. The semiconductor element includes a drift region having a second conductivity type different from the first conductivity type. The guard ring region includes a linear region and a curvature region continuously connected to the linear region. A value obtained by dividing a radius of curvature of an inner circumference portion of the curvature region by a thickness of the drift region is not less than 5 and not more than 10. Accordingly, there can be provided a silicon carbide semiconductor device capable of improving a breakdown voltage while suppressing decrease of on-state current.

Abstract: A silicon carbide substrate including a first layer having first conductivity type, a second layer having second conductivity type, and a third layer having the first conductivity type is formed. A trench provided with an inner surface having a side wall surface and a bottom surface is formed, the side wall surface extending through the third layer and the second layer and reaching the first layer, the bottom surface being formed of the first layer. A silicon film is formed to cover the bottom surface. A gate oxide film is formed on the inner surface by oxidation in the trench. The gate oxide film includes a first portion formed by oxidation of the silicon carbide substrate, and a second portion formed by oxidation of the silicon film on the bottom surface. Accordingly, a method for manufacturing a silicon carbide semiconductor device having a high breakdown voltage is provided.

Abstract: A SiC substrate includes a first orientation flat parallel to the <11-20> direction, and a second orientation flat being in a direction intersecting the first orientation flat and being different from the first orientation flat in length. An alternative SiC substrate has a rectangular plane shape, and a main surface of the substrate includes a first side parallel to the <11-20> direction, a second side in a direction perpendicular to the first side, and a third side connecting the first side to the second side. A length of the third side projected in a direction in which the first side extends is different from a length of the third side projected in a direction in which the second side extends.

Abstract: An MOSFET includes a silicon carbide substrate, an active layer, a gate oxide film, and a gate electrode. The active layer includes a body region where an inversion layer is formed at a region in contact with the gate oxide film by application of voltage to the gate electrode. The body region includes a low concentration region arranged at a region where an inversion layer is formed, and containing impurities of low concentration, and a high concentration region adjacent to the low concentration region in the carrier mobile direction in the inversion layer, arranged in a region where the inversion layer is formed, and containing impurities higher in concentration than in the low concentration region.

Abstract: A method for manufacturing a high-quality semiconductor device having stable characteristics is provided. The method for manufacturing the semiconductor device includes the steps of: preparing a silicon carbide layer having a main surface; forming a trench in the main surface by removing a portion of the silicon carbide layer; and removing a portion of a side wall of the trench by thermal etching.

Abstract: A substrate is provided with a main surface having an off angle of 5° or smaller relative to a reference plane. The reference plane is a {000-1} plane in the case of hexagonal system and is a {111} plane in the case of cubic system. A silicon carbide layer is epitaxially formed on the main surface of the substrate. The silicon carbide layer is provided with a trench having first and second side walls opposite to each other. Each of the first and second side walls includes a channel region. Further, each of the first and second side walls substantially includes one of a {0-33-8} plane and a {01-1-4} plane in the case of the hexagonal system and substantially includes a {100} plane in the case of the cubic system.

Abstract: A silicon carbide semiconductor device having excellent electrical characteristics including channel mobility and a method for manufacturing the same are provided. The method for manufacturing a silicon carbide semiconductor device includes: an epitaxial layer forming step of preparing a semiconductor film of silicon carbide; a gate insulating film forming step of forming an oxide film on a surface of the semiconductor film; a nitrogen annealing step of performing heat treatment on the semiconductor film on which the oxide film is formed, in a nitrogen-containing atmosphere; and a post heat treatment step of performing, after the nitrogen annealing step, post heat treatment on the semiconductor film on which the oxide film is formed, in an atmosphere containing an inert gas. The heat treatment temperature in the post heat treatment step is higher than that in the nitrogen annealing step and lower than a melting point of the oxide film.

Abstract: An MOSFET includes a silicon carbide substrate, an active layer, a gate oxide film, and a gate electrode. The active layer includes a body region where an inversion layer is formed at a region in contact with the gate oxide film by application of voltage to the gate electrode. The body region includes a low concentration region arranged at a region where an inversion layer is formed, and containing impurities of low concentration, and a high concentration region adjacent to the low concentration region in the carrier mobile direction in the inversion layer, arranged in a region where the inversion layer is formed, and containing impurities higher in concentration than in the low concentration region.

Abstract: On a substrate, a silicon carbide layer provided with a main surface is formed. A mask is formed to cover a portion of the main surface of the silicon carbide layer. The main surface of the silicon carbide layer on which the mask is formed is thermally etched using chlorine-based gas so as to provide the silicon carbide layer with a side surface inclined relative to the main surface. The step of thermally etching is performed in an atmosphere in which the chlorine-based gas has a partial pressure of 50% or smaller.