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.

Provided is a semiconductor device manufacturing method comprising: forming an impurity region including a first impurity on a semiconductor wafer; annealing the semiconductor wafer in a state where a lower surface of the semiconductor wafer is supported; and removing at least a part of the impurity region by removing a region including the lower surface of the semiconductor wafer. The first impurity may be oxygen. After the annealing, a maximum value of a concentration of the first impurity in the impurity region may be equal to or greater than 1×10.sup.18/cm.sup.3.

A semiconductor device includes an N+ type substrate, an N− type layer disposed on a first surface of the N+ type substrate and having a trench opened to a surface opposite to the surface facing the N+ type substrate, a P type region disposed in the N− type layer and disposed on a side surface of the trench, a gate electrode disposed in the trench, and a source electrode and a drain electrode insulated from the gate electrode. The N− type layer includes a P type shield region covering a bottom surface and an edge of the trench.

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.

A method of processing a power semiconductor device includes: providing a semiconductor body with a drift region of a first conductivity type; forming a plurality of trenches extending into the semiconductor body along a vertical direction and arranged adjacent to each other along a first lateral direction; providing a mask arrangement at the semiconductor body, the mask arrangement having a lateral structure according to which some of the trenches are exposed and at least one of the trenches is covered by the mask arrangement along the first lateral direction; forming, below bottoms of the exposed trenches, a plurality of doping regions of a second conductivity type complementary to the first conductivity type; removing the mask arrangement; and extending the plurality of doping regions in parallel to the first lateral direction such that the plurality of doping regions overlap and form a barrier region of the second conductivity type adjacent to the bottoms of the exposed trenches.

A semiconductor device includes a semiconductor part having a first surface and a second surface opposite to the first surface, a first electrode on the first surface, a second electrode on the second surface, first to third control electrodes between the first electrode and the semiconductor part. The first to third control electrodes are biased independently from each other. The semiconductor part includes a first layer of a first-conductivity-type, a second layer of a second-conductivity-type, a third layer of the first-conductivity-type and the fourth layer of the second-conductivity-type. The second layer is provided between the first layer and the first electrode. The third layer is selectively provided between the second layer and the first electrode. The fourth layer is provided between the first layer and the second electrode. The second layer opposes the first to third control electrode with insulating films interposed.

The first layer is located on the first electrode and has the first conductivity type. The second layer is located on the first layer and has the second conductivity type. The third layer is located on the second layer. The second electrode is located on the third layer. The fourth layer is located between the second layer and the third layer, and has the second conductivity type. The third layer includes the first portion and the second portion. The first portion has the second conductivity type and has a peak value of an impurity concentration higher than the peak value of the impurity concentration in the second layer. The second portion has the first conductivity type. The area of the second portion accounts for not less than 20% and not more than 95% of the total area of the first portion and the second portion.

Provided is a semiconductor device including: a semiconductor substrate doped with an impurity; a front-surface-side electrode provided at a side of a front surface of the semiconductor substrate; and a back-surface-side electrode provided at a side of a back surface of the semiconductor substrate; wherein the semiconductor substrate includes: a peak region arranged at the side of the back surface of the semiconductor substrate and having one or more peaks of an impurity concentration; a high concentration region arranged closer to the front surface than the peak region and having an impurity concentration more gently sloped than the one or more peaks; and a low concentration region arranged closer to the front surface than the high concentration region and having an impurity concentration lower than the impurity concentration of the high concentration region and a substrate concentration of the semiconductor substrate.

A power semiconductor device is disclosed. The device includes a semiconductor body coupled to a first load terminal structure and a second load terminal structure, a first cell and a second cell. A first mesa is included in the first cell, the first mesa including: a first port region and a first channel region. A second mesa included in the second cell, the second mesa including a second port region. A third cell is electrically connected to the second load terminal structure and electrically connected to a drift region. The third cell includes a third mesa comprising: a third port region, a third channel region, and a third control electrode.

A power semiconductor device is disclosed. In one example, the device includes a semiconductor body coupled to a first load terminal structure and a second load terminal structure. An active cell field is implemented in the semiconductor body. The active cell field is surrounded by an edge termination zone. A plurality of first cells and a plurality of second cells are provided in the active cell field. Each first cell includes a first mesa, the first mesa including: a first port region and a first channel region. Each second cell includes a second mesa, the second mesa including a second port region. The active cell field is surrounded by a drainage region that is arranged between the active cell field and the edge termination zone.