Abstract: A method of manufacturing a semiconductor device includes: forming a trench on a surface of a semiconductor substrate; forming an oxide film on side surfaces and a bottom surface of the trench; removing at least a part of the oxide film by dry etching from the bottom surface of the trench; and ion-implanting conductive impurities into the semiconductor substrate through the bottom surface of the trench after the dry etching. The dry etching is reactive ion etching in which etching gas including fluorocarbon based gas having a carbon atom ring structure, oxygen gas, and argon gas is used.

Abstract: A switching element including: a bottom insulating layer disposed at a bottom of a trench; a side surface insulating film covering a side surface of the trench; and a gate electrode disposed inside the trench and insulated from a semiconductor substrate. The semiconductor substrate has a bottom region and a connection region. The bottom region is in contact with the bottom insulating layer. The connection region is in contact with the bottom insulating layer and the side surface insulating film, and connects a body region to the bottom region. An area of the connection region in which the bottom insulating layer contacts to the connection region includes an area with lower a second conductivity-type impurity concentration than a minimum value of the second conductivity-type impurity concentration in an area of the connection region in which the side surface insulating film contacts the connection region.

Abstract: A method of manufacturing a switching element is provided. The method including: preparing a semiconductor substrate which includes an n-type drain region, a p-type body region, and a trench penetrating the body region and reaching the drain region; and forming a lateral surface p-type region extending along a lateral surface of the trench below the body region by heating the semiconductor substrate so as to make a part of the body region flow into the trench. The switching element includes: a gate insulating layer covering an inner surface of the trench; a bottom p-type region in contact with the gate insulating layer at a bottom surface of the trench and connected to the lateral surface p-type region; an n-type source region; and a gate electrode provided in the trench.

Abstract: A SiC single crystal seed of the present invention has a main surface with an offset angle of at least 2° but not more than 20° relative to the {0001} plane, and at least one sub-growth surface, wherein the sub-growth surface includes an initial facet formation surface that is on the offset upstream side of the main surface and has an inclination angle ? relative to the {0001} plane with an absolute value of less than 2° in any direction, and the initial facet formation surface has a screw dislocation starting point.

Abstract: A semiconductor device may be provided with a semiconductor substrate, an upper electrode, a lower electrode and a gate electrode provided within a trench via a gate insulator film. The semiconductor substrate may include a p-type body layer being in contact with the upper electrode, an n-type drift layer intervening between the body layer and the lower electrode, a p-type floating region provided along a bottom surface of the trench, and a p-type connection region extending between the body layer and the floating region along a side surface of the trench. The trench may include a first section where the connection region is not provided and a second section where the connection region is provided. An inclination angle of the side surface of the trench in the second section may be greater than an inclination angle of the side surface of the trench in the first section.

Abstract: A trench gate semiconductor switching element is provided. The semiconductor substrate of this element includes a second conductivity type bottom region in contact with the gate insulation layer at a bottom surface of the trench; and a first conductivity type second semiconductor region extending from a position in contact with a lower surface of the body region to a position in contact with a lower surface of the bottom region, and in contact with the gate insulation layer on a lower side of the body region. The bottom region includes a low concentration region in contact with the gate insulation layer in a first range of the bottom surface positioned at an end in a long direction of the trench; and a high concentration region in contact with the gate insulation layer in a second range of the bottom surface adjacent to the first range.

Abstract: A trench gate semiconductor switching element is provided. The semiconductor substrate of the element includes a second conductivity type bottom region in contact with the gate insulation layer at a bottom surface of the trench, and a first conductivity type second semiconductor region extending from a position in contact with a lower surface of the body region to a position in contact with a lower surface of the bottom region. The bottom region includes a first bottom region in contact with the gate insulation layer in a first range of the bottom surface positioned at an end in a long direction of the trench and extending from the bottom surface to a first position; and a second bottom region in contact with the gate insulation layer in a second range adjacent to the first range and extending from the bottom surface to a second position lower than the first position.

Abstract: A semiconductor device may include an element region and a peripheral voltage withstanding region. The peripheral voltage withstanding region includes inner circumferential guard rings; and outer circumferential guard rings having a width narrower than a width of the inner circumferential guard rings. An interval between the inner circumferential guard rings is narrower than an interval between the outer circumferential guard rings. Each of the inner circumferential guard rings includes a first high concentration region and a first low concentration region. Each of the outer circumferential guard rings includes a second high concentration region and a second low concentration region. A width of a part of each first low concentration region that is exposed on a front surface of the semiconductor device is wider than a width of a part of each second low concentration region that is exposed on the front surface.

Abstract: A diode includes: a semiconductor substrate including a first surface including a first range and a second range surrounding the first range, the first surface of the semiconductor substrate protruding in the first range from the second range such that the first surface having a step along a border between the first range and the second range; a first electrode that is in Schottky contact with the first electrode within the first range; an interlayer insulating film that covers the step, the second range, and an end portion of the first electrode; and a field plate electrode conductively connected to the first electrode. The field plate electrode covers a region of the interlayer insulating film covering the end portion of the first electrode and a region of the interlayer insulating film covering the step, and extends onto a region of the interlayer insulating film covering the second range.

Abstract: A diode includes a semiconductor substrate; a top surface electrode in contact with a part of the top surface of the semiconductor substrate; and a bottom surface electrode in contact with at least a part of the bottom surface of the semiconductor substrate. The semiconductor substrate includes: an n-type high-concentration layer in ohmic contact with the bottom surface electrode; an n-type intermediate-concentration layer on a part of the n-type high-concentration layer; and an n-type low-concentration layer on a part of the n-type high-concentration layer. The n-type low-concentration layer surrounds the n-type intermediate-concentration layer. The top surface electrode is in Schottky contact with a top surface of the n-type intermediate-concentration layer, and a contact region where the top surface electrode and the semiconductor substrate are in contact extends onto then-type low-concentration layer beyond the n-type intermediate-concentration layer.

Abstract: A switching device may include a semiconductor substrate; gate trenches; bottom insulating layers covering bottom surfaces of the gate trenches; gate insulating layers covering side surfaces of the gate trenches; and gate electrodes arranged in the gate trenches. The gate insulating layers in a center portion may have a first thickness and a first dielectric constant, and one or more of the gate insulating layers in a peripheral portion may have, within at least a part of the peripheral portion, a second thickness thicker than the first thickness and a second dielectric constant greater than the first dielectric constant. The semiconductor substrate may include a first region being in contact with the gate insulating layers, a body region being in contact with the gate insulating layers under the first region, and a second region being in contact with the gate insulating layers under the body region.

Abstract: A SiC single crystal includes, in a plane substantially parallel to a c-plane thereof, a region (A) in which edge dislocations having a Burgers vector (A) in a specific direction are unevenly distributed, and a region (B) in which basal plane dislocations having a Burgers vector (B) in a specific direction are unevenly distributed. The region (A) is located in a <1-100> direction with respect to a facet portion, while the region (B) is located in a <11-20> direction with respect to the facet portion. A SiC substrate is produced by cutting a SiC wafer from the SiC single crystal in a direction substantially parallel to the c-plane, and cutting the SiC substrate from the SiC wafer such that the SiC substrate mainly contains one of the region (A) and the region (B). A SiC device is fabricated using the SiC substrate.

Abstract: A switching device includes a semiconductor substrate; first and second trenches; gate insulating layers; and gate electrodes. The semiconductor substrate includes a first semiconductor region of a first conductivity type, a body region of a second conductivity type, a second semiconductor region of the first conductivity type, first and second bottom semiconductor regions of the second conductivity type disposed in areas extending to bottom surfaces of the first and second trenches, and a connection semiconductor region of the second conductivity type extending from the first trench to reach the second trench in a depth range from a depth of a lower end of the body region to a depth of the bottom surfaces of the first and second trenches, the connection semiconductor region contacting the second semiconductor region, and being connected to the body region, and the first and second bottom semiconductor regions.

Abstract: A floating region includes a high-concentration region and a low-concentration region that are arranged along a thickness direction of a silicon carbide substrate. A concentration of a p-type dopant in the low-concentration region is lower than a concentration of the p-type dopant in the high-concentration region. The high-concentration region contacts the low-concentration region, and is disposed between a bottom surface of a trench and the low-concentration region. In graph obtained by plotting the concentration of the p-type dopant in the floating region along the thickness direction, a bending point or an inflection point appears on a boundary between the high-concentration region and the low-concentration region. A content of the p-type dopant in the low-concentration region is equal to or higher than a content of an n-type dopant in a portion of the drift region, which is adjacent to the low-concentration region in the thickness direction.

Abstract: A switching element may include a semiconductor substrate, first and second trenches, a gate insulating layer, an interlayer insulating layer covering the semiconductor substrate, and an electrode on the interlayer insulating layer. A wide portion and a narrow portion may be arranged alternately between the first and second trenches. The interlayer insulating layer may include a contact hole in the wide portion. The electrode may be in contact with the semiconductor substrate within the contact hole. The semiconductor substrate may include an upper n-type region in contact with the gate insulating layer in the narrow portion and in contact with the electrode, a p-type body contact region in contact with the electrode, a p-type body region in contact with the gate insulating layer in the narrow portion, and a lower n-type region in contact with the gate insulating layer in the narrow portion.

Abstract: A switching device may be provided with: a semiconductor substrate; a trench provided in an upper surface of the semiconductor substrate; a gate insulating layer covering an inner surface of the trench; and a gate electrode located in the trench. The semiconductor substrate includes: a first semiconductor region being in contact with the gate insulating layer; a body region being in contact with the gate insulating layer under the first semiconductor region; a second semiconductor region being in contact with the gate insulating layer under the body region; a bottom region being in contact with the gate insulating layer at a bottom surface of the trench; and a connection region being in contact with the gate insulating layer at a lateral surface of the trench and connecting the body region and the bottom region. The connection region is thicker than the bottom region.

Abstract: A method of manufacturing a semiconductor device includes: forming a trench on a surface of a semiconductor substrate; forming an oxide film on side surfaces and a bottom surface of the trench; removing at least a part of the oxide film by dry etching from the bottom surface of the trench; and ion-implanting conductive impurities into the semiconductor substrate through the bottom surface of the trench after the dry etching. The dry etching is reactive ion etching in which etching gas including fluorocarbon based gas having a carbon atom ring structure, oxygen gas, and argon gas is used.

Abstract: An n-type drift region, a p-type first body region and a p-type contact region are formed on an SiC substrate by epitaxial growth. An opening is formed within the contact region by etching such that the first body region is exposed through the opening, and a p-type second body region is formed on the first body region exposed through the opening by epitaxial growth. An n-type source region is formed by epitaxial growth, and an opening is formed within a part of the source region located on the contact region by etching such that the contact region is exposed through the opening. A trench is formed by etching such that the trench extends from the source region to the drift region through the opening of the contact region, and a gate insulating film and a gate electrode are formed within the trench.

Abstract: A method of manufacturing a switching element is provided. The method including: preparing a semiconductor substrate which includes an n-type drain region, a p-type body region, and a trench penetrating the body region and reaching the drain region; and forming a lateral surface p-type region extending along a lateral surface of the trench below the body region by heating the semiconductor substrate so as to make a part of the body region flow into the trench. The switching element includes: a gate insulating layer covering an inner surface of the trench; a bottom p-type region in contact with the gate insulating layer at a bottom surface of the trench and connected to the lateral surface p-type region; an n-type source region; and a gate electrode provided in the trench.

Abstract: A method of manufacturing a semiconductor device is provided. The method includes: grinding a surface of an SiC wafer so that a crushed layer having a thickness of 5 nm or more is formed in a range exposed on the surface; forming a metal layer covering the crushed layer; and making the metal layer and the crushed layer react with each other by heating so as to form a silicide layer in ohmic contact with the SiC wafer. At least a part of the crushed layer covered with the metal layer transforms to the silicide layer over its entire depth.