A semiconductor device includes: a semiconductor substrate having opposing first and second main surfaces; a plurality of transistor cells each including a source region, a drift zone, a body region separating the source region from the drift zone, a field plate trench extending into the drift zone and including a field plate, and a planar gate on the first main surface and configured to control current through a channel of the body region; a drain region at the second main surface; and a diffusion barrier structure including alternating layers of Si and oxygen-doped Si and a Si capping layer on the alternating layers of Si and oxygen-doped Si. The diffusion barrier structure may be interposed between body regions of adjacent transistor cells and/or extend along the channel of each transistor cell and/or vertically extend in the semiconductor substrate between adjacent field plate trenches.

A semiconductor device includes a backside contact and a substrate. An epitaxial field stop region may be formed on the substrate with a graded doping profile that decreases with distance away from the substrate, and an epitaxial drift region may be formed adjacent to the epitaxial field stop region. A frontside device may be formed on the epitaxial drift region.

According to one embodiment, a nitride semiconductor includes a base body, a nitride member, and an intermediate region provided between the base body and the nitride member. The nitride member includes a first nitride region including Al.sub.x1Ga.sub.1-x1N (0<x1≤1), and a second nitride region including Al.sub.x2Ga.sub.1-x2N (0≤x2<1, x2<x1). The first nitride region is between the intermediate region and the second nitride region. The intermediate region includes nitrogen and carbon. A concentration of carbon in the intermediate region is not less than 1.5×10.sup.19/cm.sup.3 and not more than 6×10.sup.20/cm.sup.3.

According to one embodiment, a nitride semiconductor includes a base body, a nitride member, and an intermediate region provided between the base body and the nitride member. The nitride member includes a first nitride region including Al.sub.x1Ga.sub.1-x1N (0<x1≤1), and a second nitride region including Al.sub.x2Ga.sub.1-x2N (0≤x2<1, x2<x1). The first nitride region is between the intermediate region and the second nitride region. The intermediate region includes nitrogen and carbon. A concentration of carbon in the intermediate region is not less than 1.5×10.sup.19/cm.sup.3 and not more than 6×10.sup.20/cm.sup.3.

According to one embodiment, a nitride semiconductor includes a base body, and a nitride member. The nitride member includes a first nitride region including Al.sub.x1Ga.sub.1-x1N (0<x1≤1), and a second nitride region including Al.sub.x2Ga.sub.1-x2N (0≤x2<1, x2<x1). The first nitride region is between the base body and the second nitride region. The first nitride region includes a first portion and a second portion. The second portion is between the first portion and the second nitride region. An oxygen concentration in the first portion is higher than an oxygen concentration in the second portion. The oxygen concentration in the second portion is not more than 1×10.sup.18/cm.sup.3. A first thickness of the first portion in a first direction from the first to second nitride regions is thinner than a second thickness of the second portion in the first direction.

According to one embodiment, a nitride semiconductor includes a base body, and a nitride member. The nitride member includes a first nitride region including Al.sub.x1Ga.sub.1-x1N (0<x1≤1), and a second nitride region including Al.sub.x2Ga.sub.1-x2N (0≤x2<1, x2<x1). The first nitride region is between the base body and the second nitride region. The first nitride region includes a first portion and a second portion. The second portion is between the first portion and the second nitride region. An oxygen concentration in the first portion is higher than an oxygen concentration in the second portion. The oxygen concentration in the second portion is not more than 1×10.sup.18/cm.sup.3. A first thickness of the first portion in a first direction from the first to second nitride regions is thinner than a second thickness of the second portion in the first direction.

A semiconductor includes an active pattern with a lower pattern and sheet patterns spaced apart from the lower pattern in a first direction, a source/drain pattern on the lower pattern, the source/drain pattern being in contact with the sheet patterns, and gate structures on opposite sides of the source/drain pattern, the gate structures being spaced apart from each other along a second direction and including gate electrodes that surround the sheet patterns, wherein the source/drain pattern includes a first epitaxial region having at least one of antimony and bismuth, the first epitaxial region having a bottom part in contact with the lower pattern, but not with the sheet patterns, and a thickness of the bottom part increasing and decreasing away from the gate structures in the second direction, and a second epitaxial region on the first epitaxial region, the second epitaxial region including phosphorus.

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.

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.