Abstract: In the direction from the first main surface toward the second main surface through each of the second impurity region and the fourth impurity region, a concentration profile of an n-type impurity has a second relative maximum value and a fourth relative maximum value located closer to the first main surface than a position where the second relative maximum value is exhibited. The fourth relative maximum value is larger than the third relative maximum value, the third relative maximum value is larger than the second relative maximum value, and the second relative maximum value is larger than the first relative maximum value.

Abstract: A semiconductor device includes a first layer of first conductivity type and including an element region where semiconductor elements are to be formed, an annular second layer of second conductivity type formed to include a surface of the first layer, and surrounding the element region in a plan view, a third layer of second conductivity type formed in the first layer and separated more from the surface than the second layer, and sandwiching a portion of the first layer between the second and third layers, a fourth layer of second conductivity type and electrically connecting the second and third layers, and an electrode electrically connected to the fourth layer inside the second layer in the plan view. effective concentration of a second conductivity type impurity included in the second layer is higher than that of the first layer, and lower than that of the third layer.

Abstract: A semiconductor device includes a first layer of first conductivity type and including an element region where semiconductor elements are to be formed, an annular second layer of second conductivity type formed to include a surface of the first layer, and surrounding the element region in a plan view, a third layer of second conductivity type formed in the first layer and separated more from the surface than the second layer, and sandwiching a portion of the first layer between the second and third layers, a fourth layer of second conductivity type and electrically connecting the second and third layers, and an electrode electrically connected to the fourth layer inside the second layer in the plan view. effective concentration of a second conductivity type impurity included in the second layer is higher than that of the first layer, and lower than that of the third layer.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate and a gate insulating film. The silicon carbide substrate includes a first impurity region, a second impurity region, a third impurity region, a fourth impurity region, a fifth impurity region, and a sixth impurity region. A first main surface of the silicon carbide substrate is provided with a trench defined by a side surface and a bottom portion. The sixth impurity region includes a first region which faces the bottom portion and a second region which faces a second main surface of the silicon carbide substrate. The first region is higher in impurity concentration than the second region. In a direction perpendicular to the second main surface, a fifth main surface of the fourth impurity region is located between a sixth main surface of the second impurity region and the second main surface.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate, a gate insulating film, and a gate electrode. The gate insulating film is provided as being in contact with the first main surface of the silicon carbide substrate. The gate electrode is provided on the gate insulating film such that the gate insulating film lies between the gate electrode and the silicon carbide substrate. In a first stress test in which a gate voltage of ?5 V is applied to the gate electrode for 100 hours at a temperature of 175° C., an absolute value of a difference between a first threshold voltage and a second threshold voltage is not more than 0.5 V, with a threshold voltage before the first stress test being defined as the first threshold voltage and a threshold voltage after the first stress test being defined as the second threshold voltage.

Abstract: A silicon carbide layer includes a drift region, a body region and a source region. The drift region constitutes a first main surface and has a first conductivity type. The body region is provided on the drift region, and has a second conductivity type. It is provided on the body region to be separated from the drift region, constitutes a second main surface, and has the first conductivity type. The silicon carbide layer is provided with a trench including a first side wall portion and a first bottom portion. The silicon carbide layer is embedded in the drift region to face the first bottom portion, and includes a second conductivity type region having the second conductivity type. The second conductivity type region is electrically connected to the source region.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate and a gate insulating film. The silicon carbide substrate includes a first impurity region, a second impurity region, a third impurity region, a fourth impurity region, a fifth impurity region, and a sixth impurity region. A first main surface of the silicon carbide substrate is provided with a trench defined by a side surface and a bottom portion. The sixth impurity region includes a first region which faces the bottom portion and a second region which faces a second main surface of the silicon carbide substrate. The first region is higher in impurity concentration than the second region. In a direction perpendicular to the second main surface, a fifth main surface of the fourth impurity region is located between a sixth main surface of the second impurity region and the second main surface.

Abstract: A silicon carbide film has first and second main surfaces. The second main surface has an element formation surface and a termination surface. The silicon carbide film has a first range that constitutes a first main surface and an intermediate surface opposite to the first main surface, and a second range that is provided on the intermediate surface and constitutes the element formation surface. The first range includes: a first breakdown voltage holding layer, and a guard ring region partially provided at the intermediate surface in the termination portion. The second range has a second breakdown voltage holding layer. The second range has one of a structure only having the second breakdown voltage holding layer in the termination portion and a structure disposed only in the element portion of the element portion and the termination portion.

Abstract: A silicon carbide layer includes a drift region, a body region and a source region. The drift region constitutes a first main surface and has a first conductivity type. The body region is provided on the drift region, and has a second conductivity type. It is provided on the body region to be separated from the drift region, constitutes a second main surface, and has the first conductivity type. The silicon carbide layer is provided with a trench including a first side wall portion and a first bottom portion. The silicon carbide layer is embedded in the drift region to face the first bottom portion, and includes a second conductivity type region having the second conductivity type. The second conductivity type region is electrically connected to the source region.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate, a gate oxide film, and a gate electrode. A trench is provided in the main surface to have a side surface and a bottom portion. A contact point between a first side surface portion and a second side surface portion is located in a third impurity region. An angle formed by the first side surface portion and a straight line extending through the contact point and parallel to the main surface is smaller than an angle formed by the second side surface portion and a boundary surface between a first impurity region and a second impurity region. A thickness of a portion of the gate oxide film on the contact point between the main surface and the first side surface portion is larger than a thickness of a portion of the gate oxide film on the second impurity region.

Abstract: A silicon carbide semiconductor substrate includes: a base substrate that has a main surface having an outer diameter of not less than 100 mm and that is made of single-crystal silicon carbide; and an epitaxial layer formed on the main surface. The silicon carbide semiconductor substrate has an amount of warpage of not less than ?100 ?m and not more than 100 ?m when a substrate temperature is a room temperature and has an amount of warpage of not less than ?1.5 mm and not more than 1.5 mm when the substrate temperature is 400° C.

Abstract: A silicon carbide semiconductor device includes: a silicon carbide off substrate including a main surface having an off angle relative to a basal plane, the main surface being provided with a trench, the trench having a plurality of side walls and a bottom portion; a gate insulating film covering the side walls and the bottom portion; and a gate electrode provided on the gate insulating film, each of the side walls having an angle of more than 65° and not more than 80° relative to the basal plane in the trench, opening directions of the plurality of side walls being all at a silicon plane side or a carbon plane side.

Abstract: A trench has first to third side surfaces respectively constituted of first to third semiconductor layers. A first side wall portion included in a first insulating film has first to third regions respectively located on the first to third side surfaces. A second insulating film has a second side wall portion located on the first side wall portion. The second side wall portion has one end and the other end, the one end being connected to the second bottom portion of the second insulating film, the other end being located on one of the first and second regions, the other end being separated from the third region.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate, a gate insulating film, and a gate electrode. The gate insulating film is provided as being in contact with the first main surface of the silicon carbide substrate. The gate electrode is provided on the gate insulating film such that the gate insulating film lies between the gate electrode and the silicon carbide substrate. In a first stress test in which a gate voltage of ?5 V is applied to the gate electrode for 100 hours at a temperature of 175° C., an absolute value of a difference between a first threshold voltage and a second threshold voltage is not more than 0.5 V, with a threshold voltage before the first stress test being defined as the first threshold voltage and a threshold voltage after the first stress test being defined as the second threshold voltage.

Abstract: A silicon carbide semiconductor device includes a silicon carbide substrate, a gate insulating film, and a gate electrode. The gate insulating film is provided as being in contact with the first main surface of the silicon carbide substrate. The gate electrode is provided on the gate insulating film such that the gate insulating film lies between the gate electrode and the silicon carbide substrate. In a first stress test in which a gate voltage of ?5 V is applied to the gate electrode for 100 hours at a temperature of 175° C., an absolute value of a difference between a first threshold voltage and a second threshold voltage is not more than 0.5 V, with a threshold voltage before the first stress test being defined as the first threshold voltage and a threshold voltage after the first stress test being defined as the second threshold voltage.

Abstract: A silicon carbide semiconductor device includes a silicon carbide semiconductor layer having a main surface, the main surface of the silicon carbide semiconductor layer being provided with a trench having a closed shape when seen in plan view, the trench including a bottom, a plurality of sidewalls continuous with the bottom, and a sidewall-connecting corner portion at a connection portion between two adjacent sidewalls of the plurality of sidewalls, the silicon carbide semiconductor device further including a gate insulating film covering the bottom and the sidewalls of the trench, and a gate electrode provided on the gate insulating film, between the bottom and an upper end of the trench, the thickness of the gate insulating film at the sidewall-connecting corner portion of the trench being greater than the thickness of the gate insulating film at a portion other than the sidewall-connecting corner portion.

Abstract: A silicon carbide semiconductor substrate includes: a base substrate that has a main surface having an outer diameter of not less than 100 mm and that is made of single-crystal silicon carbide; an epitaxial layer formed on the main surface; and a deformation suppression layer formed on a backside surface of the base substrate opposite to the main surface. In this way, the deformation suppression layer suppresses the substrate from being deformed (for example, warped during high-temperature treatment). This can reduce a risk of causing defects such as crack in the silicon carbide semiconductor substrate during the manufacturing process in performing a method for manufacturing a silicon carbide semiconductor device using the silicon carbide semiconductor substrate.

Abstract: The steps of preparing a silicon carbide layer having a main surface, forming on the main surface, a first mask layer located on a first region to be a channel region and having a first opening portion on each of opposing regions with the first region lying therebetween, and forming a high-concentration impurity region having a first conductivity type and being higher in impurity concentration than the silicon carbide layer in a region exposed through the first opening portion, by implanting ions into the main surface with the first mask layer being interposed are included.

Abstract: A silicon carbide semiconductor device includes a silicon carbide layer having a first main surface and a second main surface opposite to the first main surface. In the second main surface of the silicon carbide layer, a trench having a depth in a direction from the second main surface toward the first main surface is provided, and the trench has a sidewall portion where a second layer and a third layer are exposed and a bottom portion, where a first layer is exposed. A position of the bottom portion of the trench in a direction of depth of the trench is located on a side of the second main surface relative to a site located closest to the first main surface in a region where the second layer and the first layer are in contact with each other, or located as deep as the site in the direction of depth.

Abstract: A trench having an opening and a corner portion is formed in a silicon carbide substrate. A corner insulating film is formed to cover the corner portion. A gate insulating film is formed to cover a region extending from the opening to the corner portion. The step of forming the gate insulating film includes a step of thermally oxidizing the trench provided with the corner insulating film. The step of thermally oxidizing the trench includes a step of heating the silicon carbide substrate at not less than 1300° C. Accordingly, sufficient insulation reliability of the gate insulating film is secured near the opening of the trench while preventing dielectric breakdown of the gate oxide film at the bottom portion of the trench.