The object is to provide a semiconductor device that prevents a snapback operation and has excellent heat dissipation. The semiconductor device includes a semiconductor substrate, transistor portions, diode portions, a surface electrode, and external wiring. The transistor portions and the diode portions are provided in the semiconductor substrate and are arranged in one direction parallel with the surface of the semiconductor substrate. A bonding portion of the external wiring is connected to the surface electrode. The transistor portions and the diode portions are provided in a first region and a second region and alternately arranged in the one direction. A first transistor width and a first diode width in the first region are smaller than a width of the bonding portion. A second transistor width and a second diode width in the second region are larger than the width of the bonding portion.

A trench-type MESFET includes an n-type semiconductor layer including a Ga.sub.2O.sub.3-based single crystal and including plural trenches opening on one surface, first insulators respectively buried in bottom portions of the plural trenches, gate electrodes respectively buried in the plural trenches so as to be placed on the first insulators and so that side surfaces thereof are in contact with the n-type semiconductor layer, a source electrode connected to a mesa-shaped portion between the adjacent trenches of the n-type semiconductor layer, second insulators respectively buried in the plural trenches so as to be placed on the gate electrodes to insulate the gate electrodes and the source electrode, and a drain electrode directly or indirectly connected to the n-type semiconductor layer on a side opposite to the source electrode.

Provided is a semiconductor apparatus, wherein a doping concentration distribution in the buffer region has a deepest slope where a doping concentration monotonically decreases to a position where it comes in contact with the drift region in a direction from the lower surface of the semiconductor substrate toward an upper surface, a hydrogen chemical concentration distribution in the buffer region includes in a first depth range provided with the slope: a first decrease portion where a hydrogen chemical concentration decreases toward the upper surface side; a second decrease portion located closer to the upper surface side than the first decrease portion is and where the chemical concentration decreases; and an intermediate portion arranged between the first and second decrease portions, and the intermediate portion has: a flat portion where the distribution is uniform; a peak in a slope of the chemical concentration; or a kink portion of the chemical concentration.

In a semiconductor device, a semiconductor substrate has an IGBT region and a FWD, and includes a first conductivity type drift layer, a second conductivity type base layer disposed on the drift layer, a second conductivity type collector layer disposed opposite to the base layer with respect to the drift layer in the IGBT region, and a first conductivity type cathode layer disposed opposite to the base layer with respect to the drift layer in the FWD region. The collector layer includes an extension portion that covers only a part of the cathode layer on a side adjacent to the drift layer. Alternatively, the collector layer includes an extension portion that entirely covers a region of the cathode layer adjacent to the drift layer, and has an area density of 3.5×10.sup.12 cm.sup.−2 or less.

Provided is a semiconductor device including: a buffer region having a doping concentration higher than a bulk donor concentration; a first low-concentration hydrogen peak in the buffer region; a second low-concentration hydrogen peak in the buffer region closer to a lower surface than the first low-concentration hydrogen peak; a high-concentration hydrogen peak in the buffer region closer to the lower surface than the second low-concentration hydrogen peak, the high-concentration hydrogen peak having a hydrogen chemical concentration higher than that of the second low-concentration hydrogen peak; and a flat region including a region between the two low-concentration hydrogen peaks and a region including the second low-concentration hydrogen peak, and having a doping concentration higher than a bulk donor concentration, an average value of the doping concentration being equal to or smaller than a local minimum value of a doping concentration between the second low-concentration hydrogen peak and the high-concentration hydrogen peak.

Provided is a semiconductor device including: a semiconductor substrate having a drift region of a first conductivity type; and a buffer region of the first conductivity type provided between the drift region and a lower surface of the semiconductor substrate and having a higher doping concentration than the drift region. The buffer region has two or more helium chemical concentration peaks arranged at different positions in a depth direction of the semiconductor substrate.

A semiconductor device includes: a semiconductor substrate including a front surface, a back surface that is opposite to the front surface, and a drift layer of a first conductive type disposed between the front surface and the back surface; a first diffusion layer of a second conductive type provided between the drift layer and the front surface; a second diffusion layer provided between the drift layer and the back surface; a first buffer layer of the first conductive type provided between the drift layer and the second diffusion layer, having a concentration higher than that of the drift layer, and into which a proton is injected; and a second buffer layer of the first conductive type provided between the first buffer layer and the second diffusion layer and having a concentration higher than that of the drift layer, wherein a peak concentration of the second buffer layer is higher than a peak concentration of the first buffer layer, an impurity concentration of the first buffer layer gradually decreases toward the back surface, a length from a peak position of the first buffer layer to a boundary between the drift layer and the first buffer layer is represented by Xa, a length from the peak position to a boundary between the first buffer layer and the second buffer layer is represented by Xb, and Xb>5 Xa.

Plural sessions of proton irradiation are performed by differing ranges from a substrate rear surface side. After first to fourth n-type layers of differing depths are formed, the protons are activated. Next, helium is irradiated to a position deeper than the ranges of the proton irradiation from the substrate rear surface, introducing lattice defects. When the amount of lattice defects is adjusted by heat treatment, protons not activated in a fourth n-type layer are diffused, forming a fifth n-type layer contacting an anode side of the fourth n-type layer and having a carrier concentration distribution that decreases toward the anode side by a more gradual slope than that of the fourth n-type layer. The fifth n-type layer that includes protons and helium and the first to fourth n-type layers that include protons constitute an n-type FS layer. Thus, a semiconductor device having improved reliability and lower cost may be provided.

Provided is a semiconductor device comprising a semiconductor substrate containing oxygen. An oxygen concentration distribution in a depth direction of the semiconductor substrate has a high oxygen concentration part where an oxygen concentration is higher on a further upper surface-side than a center in the depth direction of the semiconductor substrate than in a lower surface of the semiconductor substrate. The high oxygen concentration part may have a concentration peak in the oxygen concentration distribution. A crystal defect density distribution in the depth direction of the semiconductor substrate has an upper surface-side density peak on the upper surface-side of the semiconductor substrate, and the upper surface-side density peak may be arranged within a depth range in which the oxygen concentration is equal to or greater than 50% of a peak value of the concentration peak.

Provided is a semiconductor device comprising: a semiconductor substrate; a gate trench section that is provided from an upper surface to an inside of the semiconductor substrate and extends in a predetermined extending direction on the upper surface of the semiconductor substrate; a mesa section in contact to the gate trench section in an arrangement direction orthogonal the extending direction; and an interlayer dielectric film provided above the semiconductor substrate; wherein the interlayer dielectric film is provided above at least a part of the gate trench section in the arrangement direction; a contact hole through which the mesa section is exposed is provided to the interlayer dielectric film; and a width of the contact hole in the arrangement direction is equal to or greater than a width of the mesa section in the arrangement direction.