Provided is a gate voltage determination apparatus of a MOS transistor having a gate electrode, a gate insulating film and a channel region, the gate voltage determination apparatus including: a characteristic acquisition unit configured to acquire current-voltage characteristics showing a relationship between a gate current flowing through the gate electrodes and a gate voltage when the gate voltage applied to the gate electrode is changed from a higher voltage side to a lower voltage side; and a voltage determination unit configured to determine, based on a value of the gate voltage at which the gate current shows a peak waveform in the current-voltage characteristics, an off-gate voltage to be applied to the gate electrode when turning off the MOS transistor.

A semiconductor device according to one or more embodiments may include: on a semiconductor substrate, a high voltage circuit region; a transistor element region; an isolation region that elementally isolates the transistor element region from the high voltage circuit region; and a capacitively coupled field plate including plural lines of conductors, wherein the capacitively coupled field plate is provided to extend circumferentially along an outer circumferential portion of the high voltage circuit region and across the transistor element region, in a plan view of the semiconductor device, and one or more dividing sections divides at least one of the plural lines of conductors in the capacitively coupled field plate to make the at least one line discontinuous.

A semiconductor device includes a P-type body region and an N-type drift region disposed in a substrate; a gate electrode, disposed on the P-type body region and the N-type drift region, including a high concentration doping region and a high resistance region, wherein a dopant concentration of the high concentration doping region is higher than a dopant concentration of the high resistance region; a spacer disposed on a side of the gate electrode; a highly doped source region disposed in the P-type body region; and a highly doped drain region disposed in the N-type body region. The high concentration doping region overlaps the P-type body region, and the high resistance region overlaps the N-type drift region.

A semiconductor device includes a semiconductor layer structure of a wide band-gap semiconductor material. The semiconductor layer structure includes a drift region having a first conductivity type and a well region having a second conductivity type. A plurality of segmented gate trenches extend in a first direction in the semiconductor layer structure. The segmented gate trenches include respective gate trench segments that are spaced apart from each other in the first direction with intervening regions of the semiconductor layer structure therebetween. Related devices and fabrication methods are also discussed.

A lateral double-diffused metal-oxide-semiconductor (LDMOS) transistor including a breakdown voltage clamp includes a drain n+ region, a source n+ region, a gate, and a p-type reduced surface field (PRSF) layer including one or more bridge portions. Each of the one or more bridge portions extends below the drain n+ region in a thickness direction. Another LDMOS transistor includes a drain n+ region, a source n+ region, a gate, an n-type reduced surface field (NRSF) layer disposed between the source n+ region and the drain n+ region in a lateral direction, a PRSF layer disposed below the NRSF layer in a thickness direction orthogonal to the lateral direction, and a p-type buried layer (PBL) disposed below the PRSF layer in the thickness direction. The drain n+ region is disposed over the PBL in the thickness direction.

A multi-transistor device includes first and second lateral double-diffused metal-oxide-semiconductor field effect (LDMOS) transistors sharing a first p-type reduced surface field (RESURF) layer and a first drain n+ region. In certain embodiments, the first LDMOS transistor includes a first drift region, the second LDMOS transistor includes a second drift region, and the first and second drift regions are at least partially separated by the first p-type RESURF layer in a thickness direction.

A semiconductor device includes a semiconductor substrate, a transistor section, a diode section, and a boundary section provided between the transistor section and the diode section in the semiconductor substrate. The transistor section has gate trench portions which are provided from an upper surface of the semiconductor substrate to a position deeper than that of an emitter region, and to each of which a gate potential is applied. An upper-surface-side lifetime reduction region is provided on the upper surface side of the semiconductor substrate in the diode section and a partial region of the boundary section, and is not provided in a region that is overlapped with the gate trench portion in the transistor section in a surface parallel to the upper surface of the semiconductor substrate.

A method to fabricate a transistor includes implanting dopants into a semiconductor to form a drift layer having majority carriers of a first type; etching a trench into the semiconductor; thermally growing an oxide liner into and on the trench and the drift layer; depositing an oxide onto the oxide liner on the trench to form a shallow trench isolation region; implanting dopants into the semiconductor to form a drain region in contact with the drift layer and having majority carriers of the first type; implanting dopants into the semiconductor to form a body region having majority carriers of a second type; forming a gate oxide over a portion of the drift layer and the body region; forming a gate over the gate oxide; and implanting dopants into the body region to form a source region having majority carriers of the first type.

A semiconductor device comprises: a substrate; a well region provided in the substrate, having a second conductivity type; source regions having a first conductivity type; body tile regions having the second conductivity type, the source regions and the body tie regions being alternately arranged in a conductive channel width direction so as to form a first region extending along the conductive channel width direction, and a boundary where the edges of the source regions and the edges of the body tie regions are alternately arranged being formed on two sides of the first region; and a conductive auxiliary region having the first conductivity type, provided on at least one side of the first region, and directly contacting the boundary, a contact part comprising the edge of at least one source region on the boundary and the edge of at least one body tie region on the boundary.

A high withstand voltage isolation region has a first diffusion layer of a second conductivity type formed on a principal surface of a semiconductor substrate. The high withstand voltage MOS has a second diffusion layer of the second conductivity type formed on the principal surface of the semiconductor substrate. A low side circuit region has a third diffusion layer of a first conductivity type formed on the principal surface of the semiconductor substrate. A fourth diffusion layer of the first conductivity type having a higher impurity concentration than the semiconductor substrate is formed on the principal surface of the semiconductor substrate exposed between the first diffusion layer and the second diffusion layer. The fourth diffusion layer extends from the high side circuit region to the low side circuit region and does not contact the third diffusion layer.