A p-type semiconductor region is formed in a front surface side of an n-type semiconductor substrate. An n-type field stop (FS) region including protons as a donor is formed in a rear surface side of the semiconductor substrate. A concentration distribution of the donors in the FS region include first, second, third and fourth peaks in order from a front surface to the rear surface. Each of the peaks has a peak maximum point, and peak end points formed at both sides of the peak maximum point. The peak maximum points of the first and second peaks are higher than the peak maximum point of the third peak. The peak maximum point of the third peak is lower than the peak maximum point of the fourth peak.

A semiconductor device is an IGBT of a trench-gate structure and has a storage region directly beneath a p.sup.-type base region. The semiconductor device has gate trenches and dummy trenches as trenches configuring the trench-gate structure. An interval (mesa width) at which the trenches are disposed is in a range of 0.7 m to 2 m. In each of the gate trenches, a gate electrode of a gate potential is provided via a first gate insulating film. In each of the dummy trenches, a dummy gate electrode of an emitter potential is provided via a second gate insulating film. A total number of the gate electrode is in a range of 60% to 84% of a total number of the dummy electrodes.

A semiconductor device includes a first region in which a drift, base, and accumulation regions are stacked. Transistor cells are each provided partially in the first region and include at least one trench extending into the drift region. A second region includes a well region provided on an edge termination region side surrounding the first region. A third region of a predetermined width is between the first and second regions, inside of which the transistor cells are partially provided. A bottom region is provided in the first region, adjacent to a bottom of the trench, and between the accumulation and drift regions, the bottom region not extending into the third region, its upper surface located below the base region's lower surface; and first and second electrodes configured to flow current therebetween. The bottom region is spaced apart from the base region by the accumulation region in the depth direction.

A semiconductor device includes a gate electrode embedded in each of a plurality of first trenches through an insulating film. The gate electrode includes a first gate electrode electrically connected to a first gate pad and a second gate electrode electrically connected to a second gate pad. A charge period and a discharge period of gate capacitance parasitic on the second gate electrode are shorter than a charge period and a discharge period of gate capacitance parasitic on the first gate electrode, respectively.

A semiconductor device according to one or more embodiments is disclosed. A first semiconductor region includes a first semiconductor region, a second semiconductor region, a third semiconductor region, a first trench and a fourth semiconductor region. A second semiconductor region includes a fifth semiconductor region, a sixth semiconductor region, a second trench, and a second inner trench electrode. A dummy region includes a seventh semiconductor region that is arranged on the first semiconductor region between the first semiconductor region and the second semiconductor region, a third trench penetrating the seventh semiconductor region in a depth direction; and a third inner trench electrode electrically connected to the first inner trench electrode through a third insulating film in the third trench.

A semiconductor device includes an SiC semiconductor layer which has a first main surface on one side and a second main surface on the other side, a semiconductor element which is formed in the first main surface, a raised portion group which includes a plurality of raised portions formed at intervals from each other at the second main surface and has a first portion in which some of the raised portions among the plurality of raised portions overlap each other in a first direction view as viewed in a first direction which is one of the plane directions of the second main surface, and an electrode which is formed on the second main surface and connected to the raised portion group.

A semiconductor apparatus includes a flat portion disposed in a predetermined region containing a central depth position of a semiconductor substrate, between a fist peak disposed in an upper surface side of the semiconductor substrate and a second peak disposed in a lower surface side of the semiconductor substrate, and having a substantially flat concentration higher than a bulk donor concentration in a donor concentration distribution in a depth direction of a semiconductor substrate. The entire oxygen chemical concentration between the first peak and the second peak ranges from 310.sup.15 atoms/cm.sup.3 to 210.sup.18 atoms/cm.sup.3.

A semiconductor device with an active transistor cell comprising a p-doped first and second base layers, surrounding an n type source region, the device further comprising a plurality of first gate electrodes embedded in trench recesses, has additional fortifying p-doped layers embedding the opposite ends of the trench recesses. The additional fortifying layers do not affect the active cell design in terms of cell pitch i.e., the design rules for transistor cell spacing, or hole drainage between the transistor cells, but reduce the gate-collector parasitic capacitance of the semiconductor, hence leading to optimum low conduction and switching losses. To further reduce the gate-collector capacitance, the trench recesses embedding the first gate electrodes can be formed with thicker insulating layers in regions that do not abut the first base layers, so as not to negatively impact the value of the threshold voltage.

Provided is a semiconductor device including a portion which operates as a transistor, in which the transistor includes a gate trench portion to which a gate voltage is applied, an emitter region in contact with the gate trench portion, and a base region in contact with the gate trench portion, and a threshold voltage at which the transistor transits from an off state to an on state in an ambient temperature of 25 C. is larger than a half of a first voltage for turning on the transistor.

A semiconductor device including an IGBT with improved switching characteristics is provided. Inside trenches formed inside a semiconductor substrate of an active cell, a trench gate electrode and a trench emitter electrode are formed through a gate insulating film. An n-type hole barrier region is formed inside the semiconductor substrate located between the trenches. A p-type base region is formed inside the hole barrier region. An n-type emitter region is formed inside the base region. A p-type floating region is formed inside the semiconductor substrate of an inactive cell. A depth of the floating region is shallower than each depth of the trenches, and is deeper than a depth of the base region.