Abstract: A method of cleaning a SiC semiconductor includes the steps of forming an oxide film at the surface of a SiC semiconductor, and removing the oxide film. At the step of forming an oxide film, an oxide film is formed using ozone water having a concentration greater than or equal to 30 ppm. The forming step preferably includes the step of heating at least one of the surface of the SiC semiconductor and the ozone water. Thus, there can be obtained a method of cleaning a SiC semiconductor that can exhibit cleaning effect on the SiC semiconductor.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate. The silicon carbide substrate is composed of an element region provided with a semiconductor element portion and a termination region surrounding the element region as viewed in a plan view. The semiconductor element portion includes a drift region having a first conductivity type. The termination region includes a first electric field relaxing region contacting the element region and having a second conductivity type different from the first conductivity type, and a second electric field relaxing region arranged outside the first electric field relaxing region as viewed in the plan view, having the second conductivity type, and spaced from the first electric field relaxing region. A ratio calculated by dividing a width of the first electric field relaxing region by a thickness of the drift region is not less than 0.5 and not more than 1.83.

Abstract: A method of manufacturing a MOSFET includes the steps of preparing a silicon carbide substrate, forming an active layer on the silicon carbide substrate, forming a gate oxide film on the active layer, forming a gate electrode on the gate oxide film, forming a source contact electrode on the active layer, and forming a source interconnection on the source contact electrode. The step of forming the source interconnection includes the steps of forming a conductor film on the source contact electrode and processing the conductor film by etching the conductor film with reactive ion etching. Then, the method of manufacturing a MOSFET further includes the step of performing annealing of heating the silicon carbide substrate to a temperature not lower than 50° C. after the step of processing the conductor film.

Abstract: A collector layer having p type is formed on a silicon carbide substrate having n type. A drift layer having n type is formed on a top surface side of the collector layer. A body region provided on the drift layer and having p type, and an emitter region provided on the body region to be separated from the drift layer by the body region and having n type are formed. A bottom surface side of the collector layer is exposed by removing the silicon carbide substrate.

Abstract: A silicon carbide layer is epitaxially formed on a main surface of a substrate. The silicon carbide layer is provided with a trench having a side wall inclined relative to the main surface. The side wall has an off angle of not less than 50° and not more than 65° relative to a {0001} plane. A gate insulating film is provided on the side wall of the silicon carbide layer. The silicon carbide layer includes: a body region having a first conductivity type and facing a gate electrode with the gate insulating film being interposed therebetween; and a pair of regions separated from each other by the body region and having a second conductivity type. The body region has an impurity density of 5×1016 cm?3 or greater. This allows for an increased degree of freedom in setting a threshold voltage while suppressing decrease of channel mobility.

Abstract: When viewed in a plan view, a termination region (TM) surrounds an element region (CL). A first side of a silicon carbide substrate (SB) is thermally etched to form a side wall (ST) and a bottom surface (BT) in the silicon carbide substrate (SB) at the termination region (TM). The side wall (ST) has a plane orientation of one of {0-33-8} and {0-11-4}. The bottom surface (BT) has a plane orientation of {000-1}. On the side wall (ST) and the bottom surface (BT), an insulating film (8T) is formed. A first electrode (12) is formed on the first side of the silicon carbide substrate (SB) at the element region (CL). A second electrode (14) is formed on a second side of the silicon carbide substrate (SB).

Abstract: A silicon carbide layer is epitaxially formed on a main surface of a substrate. The silicon carbide layer is provided with a trench having a side wall inclined relative to the main surface. The side wall has an off angle of not less than 50° and not more than 65° relative to a {0001} plane. A gate insulating film is provided on the side wall of the silicon carbide layer. The silicon carbide layer includes: a body region having a first conductivity type and facing a gate electrode with the gate insulating film being interposed therebetween; and a pair of regions separated from each other by the body region and having a second conductivity type. The body region has an impurity density of 5×1016 cm?3 or greater. This allows for an increased degree of freedom in setting a threshold voltage while suppressing decrease of channel mobility.

Abstract: A MOSFET includes a semiconductor substrate having a trench formed in a main surface, a gate oxide film, a gate electrode, and a source interconnection. A semiconductor substrate includes an n-type drift layer and a p-type body layer. The trench is formed to penetrate the body layer and to reach the drift layer. The trench includes an outer peripheral trench arranged to surround an active region when viewed two-dimensionally. On the main surface opposite to the active region when viewed from the outer peripheral trench, a potential fixing region where the body layer is exposed is formed. The source interconnection is arranged to lie over the active region when viewed two-dimensionally. The potential fixing region is electrically connected to the source interconnection.

Abstract: A gate insulating film is provided on a trench. The gate insulating film has a trench insulating film and a bottom insulating film. The trench insulating film covers each of a side wall and a bottom portion. The bottom insulating film is provided on the bottom portion with a trench insulating film being interposed therebetween. The bottom insulating film has a carbon atom concentration lower than that of the trench insulating film. The gate electrode is in contact with a portion of the trench insulating film on the side wall. Accordingly, a low threshold voltage and a large breakdown voltage can be attained.

Abstract: A wide gap semiconductor device includes a substrate and a Schottky electrode. The substrate formed of a wide gap semiconductor material has a main face, and includes a first-conductivity-type region and a second-conductivity-type region. The Schottky electrode is arranged adjoining the main face of the substrate. At the substrate, there is foamed a trench having a side face continuous with the main face and a bottom continuous with the side face. The Schottky electrode adjoins the first-conductivity-type region at the side face of the trench and the main face, and adjoins the second-conductivity-type region at the bottom of the trench. The side face of the trench is inclined relative to the main face of the substrate.

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 substrate has a first surface and a second surface, and includes a first region and a third region each having first conductivity type, as well as a second region and a fourth region each having second conductivity type. The third region surrounds the second region on the second surface. The fourth region has an impurity concentration higher than that of the second region, is in contact with the second region, and surrounds the third region on the second surface. A first main electrode is provided on the first surface. A second main electrode is in contact with each of the third and fourth regions. A gate insulating film is provided on the second region.

Abstract: There is provided a method for manufacturing a SiC semiconductor device achieving improved performance. The method for manufacturing the SiC semiconductor device includes the following steps. That is, a SiC semiconductor is prepared which has a first surface having at least a portion into which impurities are implanted. By cleaning the first surface of the SiC semiconductor, a second surface is formed. On the second surface, a Si-containing film is formed. By oxidizing the Si-containing film, an oxide film constituting the SiC semiconductor device is formed.

Abstract: A drift layer forms a first main surface of a silicon carbide layer and has a first conductivity type. A source region is provided to be spaced apart from the drift layer by a body region, forms a second main surface, and has the first conductivity type. A relaxing region is provided within the drift layer and has a distance Ld from the first main surface. The relaxing region has a second conductivity type and has an impurity dose amount Drx. The drift layer has an impurity concentration Nd between the first main surface and the relaxing region. Relation of Drx>Ld·Nd is satisfied. Thus, a silicon carbide semiconductor device having a high breakdown voltage is provided.

Abstract: A MOSFET includes a semiconductor substrate having a trench formed in a main surface, a gate oxide film, a gate electrode, and a source interconnection. A semiconductor substrate includes an n-type drift layer and a p-type body layer. The trench is formed to penetrate the body layer and to reach the drift layer. The trench includes an outer peripheral trench arranged to surround an active region when viewed two-dimensionally. On the main surface opposite to the active region when viewed from the outer peripheral trench, a potential fixing region where the body layer is exposed is formed. The source interconnection is arranged to lie over the active region when viewed two-dimensionally. The potential fixing region is electrically connected to the source interconnection.

Abstract: An IGBT includes a groove provided in a silicon carbide semiconductor layer, a body region of a first conductivity type provided in the silicon carbide semiconductor layer, and an insulating film covering at least a sidewall surface of the groove, the sidewall surface of the groove being a surface having an off angle of 50° or more and 65° or less with respect to a {0001} plane, the sidewall surface of the groove including a surface of the body region, the insulating film being in contact with at least the surface of the body region at the sidewall surface of the groove, and a first conductivity type impurity concentration in the body region being 5×1016 cm?3 or more.

Abstract: The substrate is made of a compound semiconductor, and has a recess, which opens at one main surface and has side wall surfaces when viewed in a cross section along a thickness direction. The gate insulating film is disposed on and in contact with each of the side wall surfaces. The substrate includes a source region having first conductivity type and disposed to be exposed at the side wall surface; and a body region having second conductivity type and disposed in contact with the source region at a side opposite to the one main surface so as to be exposed at the side wall surface, when viewed from the source region. The recess has a closed shape when viewed in a plan view. The side wall surfaces provide an outwardly projecting shape in every direction when viewed from an arbitrary location in the recess.

Abstract: A first layer is of a first conductivity type. A second layer is provided on the first layer and is of a second conductivity type. A third layer is provided on the second layer and isolated from the first layer by the second layer, and is of the first conductivity type. A trench is formed through the third layer and the second layer to reach the first layer. The first layer includes a relaxation region sandwiching a gate insulating film between itself and a gate electrode. The relaxation region is doped with a first impurity for providing the first conductivity type. The relaxation region is also doped with a second impurity for providing the second conductivity type in a concentration lower than that of the first impurity. As a result, an electric field relaxation structure for improving the breakdown voltage can be readily formed.

Abstract: The substrate is made of a compound semiconductor and has a plurality of first recesses, each of which opens at one main surface thereof and has a first side wall surface. The gate insulating film is disposed on and in contact with the first side wall surface. The gate electrode is disposed on and in contact with the gate insulating film. The substrate include: a source region having first conductivity type and disposed to face itself with a first recess interposed therebetween, when viewed in a cross section along the thickness direction; and a body region having second conductivity type and disposed to face itself with the first recess interposed therebetween. Portions of the source region facing each other are connected to each other in a region interposed between the first recess and another first recess adjacent to the first recess, when viewed in a plan view.

Abstract: A silicon carbide substrate includes a first layer of a first conductivity type, a second layer of a second conductivity type provided on the first layer, and a third layer provided on the second layer and doped with an impurity for providing the first conductivity type. The silicon carbide substrate has a trench formed through the third layer and the second layer to reach the first layer. The first layer has a concentration peak of the impurity in a position away from the trench in the first layer. As a result, a silicon carbide semiconductor device having an electric field relaxation structure that can be readily formed is provided.