Abstract: In case of performing annealing at a temperature of 1300° C. or higher, it is not possible to sufficiently suppress escape of nitrogen from a GaN layer even if a cap layer is provided thereon. Thereby, the front surface of the GaN layer is roughened. A semiconductor device manufacturing method of manufacturing a semiconductor device having a nitride semiconductor layer is provided. The semiconductor device manufacturing method includes: implanting, into a predetermined region of the nitride semiconductor layer, n-type or p-type impurities relative to the nitride semiconductor layer; forming, by atomic layer deposition, a first protective film containing a nitride on and in direct contact with at least the predetermined region; and annealing the nitride semiconductor layer and the first protective film at a temperature of 1300° C. or higher.

Abstract: When a channel formation region is formed of GaN in a MOSFET, there are cases where the actual threshold voltage (Vth) is lower than the setting value thereof and the actual carrier mobility (?) during the ON state is lower than the setting value thereof. The reason for threshold voltage (Vth) and the carrier mobility (?) being lower than the setting values is unknown. A MOSFET including a gallium nitride substrate, an epitaxial layer made of gallium nitride provided on top of the gallium nitride substrate, a gate insulating film provided in direct contact with the epitaxial layer, and a gate electrode provided in contact with the gate insulating film. The gallium nitride substrate has a dislocation density less than or equal to 1E+6 cm?2, and the epitaxial layer has a region with a p-type impurity concentration less than or equal to 5E+17 cm?3.

Abstract: If a SiO2 film is formed on a semiconductor substrate using TEOS (tetraethylorthosilicate: Si(OC2H5)4), carbon (C) may be mixed in the SiO2 film in some cases. In a SiO2 film, carbon may function as fixed charges. For example, if carbon (C) is mixed in a SiO2 film as a gate insulating film of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), the gate threshold voltage (Vth) may fluctuate. A semiconductor device using a gallium nitride semiconductor layer is provided. The semiconductor device includes: a silicon dioxide film that is provided at least partially in direct contact with the gallium nitride semiconductor layer and has impurity atoms, wherein the silicon dioxide film contains as the impurity atoms: carbon at concentration higher than 0 cm?3 and lower than 2E+18 cm?3; and gallium at concentration equal to or lower than 1E+17 cm?3.

Abstract: Provided is a semiconductor device including at least two isolation trench portions; a mesa region that is provided between the at least two isolation trench portions and includes a source region having a first conduction type, a base region having a second conduction type and at least a portion thereof provided below the source region, and a gate trench portion; and a contact layer that is an epitaxial layer provided at least in contact with side portions of the mesa region and bottom portions of the isolation trench portions positioned lower than the gate trench portion, and having a second-conduction-type impurity concentration higher than that of the base region, wherein the same impurities as in the contact layer are present in the source region, or the contact layer is provided higher than the source region.

Abstract: To more easily form a structure that mitigates the electrical field focus at the bottom portion of the trench gate and prevents decreases and variations in the gate threshold value (Vth), provided is a semiconductor device including a semiconductor substrate; a second semiconductor region with a second conduction type that is provided above the semiconductor substrate and includes a first semiconductor region with a first conduction type in a portion thereof; a third semiconductor region that is provided above the second semiconductor region and has a higher second conduction type impurity concentration than the second semiconductor region; and a gate trench that penetrates through the third semiconductor region and is provided on top of the first semiconductor region. The gate trench includes a gate insulating film provided on side walls and a bottom portion of the gate trench and a gate electrode provided in contact with the gate insulating film.

Abstract: In a case where a semiconductor layer is epitaxially grown on a step shape formed due to CBL (current blocking layer) formation, the crystallinity of the semiconductor layer lowers. Also, a GaN layer that is epitaxially regrown on the CBL is not formed continuously by epitaxial growth, and therefore the crystallinity of the GaN layer lowers. A vertical semiconductor device manufacturing method is provided that comprises: a step of epitaxially growing a gallium nitride-based n-type semiconductor layer on a gallium nitride-based semiconductor substrate; a step of epitaxially growing a gallium nitride-based p-type semiconductor layer on the n-type semiconductor layer; and a step of ion-implanting p-type impurities to form a p+-type embedded region selectively in a predetermined depth range across the boundary between the n-type semiconductor layer and the p-type semiconductor layer.

Abstract: A vertical MOSFET having a compound semiconductor layer is provided, the vertical MOSFET comprising a gate electrode, a gate insulating film provided between the gate electrode and the compound semiconductor layer, a drift region provided directly in contact with at least a part of the gate insulating film and being a part of the compound semiconductor layer, and a high resistance region provided at least in the drift region, is positioned below at least a part of the gate insulating film, and has a higher resistance value per unit length than that of the drift region.

Abstract: An ion implantation results in defects generated in a nitride semiconductor layer. If the nitride semiconductor layer is set at a particular temperature for a predetermined time period after the ion implantation, the defects may probably be clustering. Provided is a manufacturing method of a semiconductor device including a nitride semiconductor layer comprising: implanting impurities in the nitride semiconductor layer; and increasing a temperature of the nitride semiconductor layer from an initial temperature to a target temperature and annealing the nitride semiconductor layer at the target temperature for a predetermined time period; wherein in the annealing, in at least part of temperature regions below a first temperature between the initial temperature and the target temperature, the nitride semiconductor layer is annealed at a temperature increase speed lower than in a temperature region not lower than the first temperature.

Abstract: The semiconductor transistor according the present invention includes an active layer composed of a GaN-based semiconductor and a gate insulating film formed on the active layer. The gate insulating film has a first insulating film including one or more compounds selected from the group consisting of Al2O3, HfO2, ZrO2, La2O3, and Y2O3 formed on the active layer, and a second insulating film composed of SiO2 formed on the first insulating film.

Abstract: In case of performing annealing at a temperature of 1300° C. or higher, it is not possible to sufficiently suppress escape of nitrogen from a GaN layer even if a cap layer is provided thereon. Thereby, the front surface of the GaN layer is roughened. A semiconductor device manufacturing method of manufacturing a semiconductor device having a nitride semiconductor layer is provided. The semiconductor device manufacturing method includes: implanting, into a predetermined region of the nitride semiconductor layer, n-type or p-type impurities relative to the nitride semiconductor layer; forming, by atomic layer deposition, a first protective film containing a nitride on and in direct contact with at least the predetermined region; and annealing the nitride semiconductor layer and the first protective film at a temperature of 1300° C. or higher.

Abstract: Provided is a manufacturing method of a semiconductor device including a vertical MOSFET having a planar gate. The manufacturing method of a semiconductor device includes forming a n-type gallium nitride layer on a gallium nitride monocrystalline substrate, and forming an impurity-implanted region that contains impurities at a uniform concentration in a direction parallel to a main surface of the gallium nitride monocrystalline substrate, by ion-implanting the impurities into the n-type gallium nitride layer, where the impurities include at least one type selected from among magnesium, beryllium, calcium and zinc. Here, at least part of the impurity-implanted region serves as a channel forming region of the vertical MOSFET.

Abstract: An ion implantation results in defects generated in a nitride semiconductor layer. If the nitride semiconductor layer is set at a particular temperature for a predetermined time period after the ion implantation, the defects may probably be clustering. Provided is a manufacturing method of a semiconductor device including a nitride semiconductor layer comprising: implanting impurities in the nitride semiconductor layer; and increasing a temperature of the nitride semiconductor layer from an initial temperature to a target temperature and annealing the nitride semiconductor layer at the target temperature for a predetermined time period; wherein in the annealing, in at least part of temperature regions below a first temperature between the initial temperature and the target temperature, the nitride semiconductor layer is annealed at a temperature increase speed lower than in a temperature region not lower than the first temperature.

Abstract: When a nitride semiconductor layer into which impurity ions have been implanted is subjected to annealing after a protective film is provided on the nitride semiconductor layer, vacancy defects may be disadvantageously prevented from escaping outside through the surface of the nitride semiconductor layer and disappearing. A manufacturing method of a semiconductor device including a nitride semiconductor layer is provided. The manufacturing method includes implanting impurities into the nitride semiconductor layer, performing a first annealing on the nitride semiconductor layer at a first temperature within an atmosphere of a nitrogen atom containing gas without providing a protective film on the nitride semiconductor layer, forming the protective film on the nitride semiconductor layer after the first annealing, and after the protective film is formed, performing a second annealing on the nitride semiconductor layer at a second temperature that is higher than the first temperature.

Abstract: A radiation monitor for accurately measuring the dose rate of radiation by suppressing the risk of explosion or the like is provided. The radiation monitor includes a radiation emitting element which includes a light emitting part emitting light of an intensity corresponding to a dose rate of incident radiation, an optical fiber which is connected to the radiation emitting element and transmits the light emitted from the light emitting part, an electric pulse converter which is connected to the optical fiber and transmits one electric pulse for one photon of the transmitted light, an electric pulse detector which is connected to the electric pulse converter and counts the electric pulse transmitted from the electric pulse converter, and an analyzer which is connected to the electric pulse detector and converts the electric pulse count rate obtained by the electric pulse detector into a radiation dose rate.

Abstract: A method of manufacturing a nitride semiconductor device is provided, comprising: forming, on a substrate, a first laminated body where a first nitride semiconductor layer, a second nitride semiconductor layer and a third nitride semiconductor layer are laminated in this order; subsequent to the forming, removing a partial region of the third nitride semiconductor layer, subsequent to the removing; implanting ions to the first nitride semiconductor layer from the partial region where the third nitride semiconductor layer is removed at least through the second nitride semiconductor layer; and subsequent to the implanting the ions, annealing the first laminated body.

Abstract: Inside an IGBT using GaN or SiC, light having an energy of approximately 3 [eV] is generated. Therefore, defects are caused in the gate insulating film of the IGBT. Furthermore, the charge trapped at a deep level becomes excited and moves to the channel region, thereby causing the gate threshold voltage to fluctuate from the predetermined value. Provided is a semiconductor device including a normally-ON semiconductor element that includes a first semiconductor layer capable of conductivity modulation and a first gate electrode, but does not include a gate insulating film between the first gate electrode and the first semiconductor layer; and a normally-OFF semiconductor element that includes a second semiconductor layer, a second gate electrode, and a gate insulating film between the second semiconductor layer and the second gate electrode. The normally-ON semiconductor element and the normally-OFF semiconductor element are connected in series.

Abstract: When a defect region is present near the pn junction in a GaN layer, lattice defects are present in the depletion layer. Therefore, when a reverse bias is applied to the pn junction, the defects in the depletion layer cause the generated current to flow as a leakage current. The leakage current flowing through the depletion layer can cause a decrease in the withstand voltage at the pn junction. Provided is a semiconductor device using gallium nitride, including a gallium nitride layer including an n-type region. The gallium nitride layer includes a first p-type well region and a second p-type well region that is provided on at least a portion of the first p-type well region and has a peak region with a higher p-type impurity concentration than the first p-type well region.

Abstract: Inside an IGBT using GaN or SiC, light having an energy of approximately 3 [eV] is generated. Therefore, defects are caused in the gate insulating film of the IGBT. Furthermore, the charge trapped at a deep level becomes excited and moves to the channel region, thereby causing the gate threshold voltage to fluctuate from the predetermined value. Provided is a semiconductor device including a normally-ON semiconductor element that includes a first semiconductor layer capable of conductivity modulation and a first gate electrode, but does not include a gate insulating film between the first gate electrode and the first semiconductor layer; and a normally-OFF semiconductor element that includes a second semiconductor layer, a second gate electrode, and a gate insulating film between the second semiconductor layer and the second gate electrode. The normally-ON semiconductor element and the normally-OFF semiconductor element are connected in series.

Abstract: A method for producing a semiconductor device having a nitride-based semiconductor layer includes forming an aluminum nitride layer on a surface of the nitride-based semiconductor layer at a forming temperature and in a growth atmosphere for aluminum nitride; and performing a thermal treatment on the nitride-based semiconductor layer and the aluminum nitride layer, at a treatment temperature that is higher than the forming temperature and in the growth atmosphere for aluminum nitride. For example, an n-GaN layer is formed on an n-GaN substrate, and thereafter the n-GaN layer is doped with an impurity. A cap layer of an epitaxial film made up of AlN is formed, by MOCVD, on the surface of the n-GaN layer. Thermal treatment for activation annealing activates the impurity in the n-GaN layer in an atmosphere that causes AlN to grow, or in an atmosphere in which growth and decomposition of AlN are substantially balanced.

Abstract: When a channel formation region is formed of GaN in a MOSFET, there are cases where the actual threshold voltage (Vth) is lower than the setting value thereof and the actual carrier mobility (?) during the ON state is lower than the setting value thereof. The reason for threshold voltage (Vth) and the carrier mobility (?) being lower than the setting values is unknown. A MOSFET including a gallium nitride substrate, an epitaxial layer made of gallium nitride provided on top of the gallium nitride substrate, a gate insulating film provided in direct contact with the epitaxial layer, and a gate electrode provided in contact with the gate insulating film. The gallium nitride substrate has a dislocation density less than or equal to 1E+6 cm?2, and the epitaxial layer has a region with a p-type impurity concentration less than or equal to 5E+17 cm?3.