A semiconductor device includes a semiconductor substrate, a transistor region, a diode region, a boundary trench gate, and a carrier control region. The boundary trench gate is provided in a boundary portion between the transistor region and the diode region.

The carrier control region is provided as a surface layer of the semiconductor substrate at a position closer to the boundary trench gate than the source layer located between the boundary trench gate and the trench gate. A concentration of first conductivity type impurities contained in the carrier control region is higher than a concentration of the first conductivity type impurities contained in the source layer or a concentration of second conductivity type impurities contained in the carrier control region is lower than a concentration of the second conductivity type impurities contained in the source layer.

To provide a highly reliable semiconductor device having both an improved breakdown voltage and a reduced withstand voltage leakage current. An intermediate resistive field plate is comprised of a first intermediate resistive field plate coupled, at one end thereof, to an inner-circumferential-side resistive field plate and, at the other end, to an outer-circumferential-side resistive field plate and a plurality of second intermediate resistive field plates. The first intermediate resistive field plate has a planar pattern that is equipped with a plurality of first portions separated from each other in a first direction connecting the inner-circumferential resistive field plate to the outer-circumferential-side resistive field plate and linearly extending in a second direction orthogonal to the first direction, and repeats reciprocation along the second direction. The second intermediate resistive field plates are each connected with a first end portion on one side of the first portions and extend with a curvature.

A semiconductor device includes a polycrystalline silicon part buried in a termination region of a silicon layer. The polycrystalline silicon part contacts the silicon layer, has a higher crystal grain density than the silicon layer, and includes a heavy metal. The silicon layer includes a drift layer located in a cell region and the termination region. The drift layer has a lower first-conductivity-type impurity concentration than a silicon substrate. The drift layer includes a same element of heavy metal as the heavy metal included in the polycrystalline silicon part.

A semiconductor device includes a semiconductor substrate having a first conductivity type region including a first conductivity type impurity. A first gate structure is on the semiconductor substrate overlying the first conductivity type region. A second conductivity type region including a second conductivity type impurity is formed in the semiconductor substrate. A barrier layer is located between the first conductivity type region and the second conductivity type region. The barrier layer prevents diffusion of the second conductivity type impurity from the second conductivity type region into the first conductivity type region.

A semiconductor device includes etch stop films formed on the first gate electrode, the first source region, the first drain region, and the shallow trench isolation regions, respectively. First interlayer insulating films are formed on the etch stop film, respectively. Deep trenches are formed in the substrate between adjacent ones of the first interlayer insulating films to overlap the shallow trench isolation regions. Sidewall insulating films are formed in the deep trenches, respectively. A gap-fill insulating film is formed on the sidewall insulating film. A second interlayer insulating film is formed on the gap-fill insulating film. A top surface of the second interlayer insulating film is substantially planar and a bottom surface of the second interlayer insulating film is undulating.

A semiconductor device according to the present invention includes: a semiconductor layer including a first conductivity type semiconductor region and a second conductivity type semiconductor region joined to the first conductivity type semiconductor region; and a surface electrode connected to the second conductivity type region on one surface of the semiconductor layer, including a first Al-based electrode, a second Al-based electrode, an Al-based oxide film interposed between the first Al-based electrode and the second Al-based electrode, and a plated layer on the second Al-based electrode.

A bidirectional switch is formed in a semiconductor substrate of a first conductivity type. The switch includes first and second thyristors connected in antiparallel extending vertically between front and rear surfaces of the substrate. A vertical peripheral wall of the second conductivity type connects the front surface to the rear surface and surrounds the thyristors. On the front surface, in a ring-shaped region of the substrate separating the vertical peripheral wall from the thyristors, a first region of the first conductivity type is provided having a doping level greater than the substrate and having the shape of a ring-shaped band portion partially surrounding the first thyristor and stopping at the level of the adjacent region between the first and second thyristors.

A semiconductor device according to the present invention includes a channel region of a first conductivity type, disposed at a front surface portion of a semiconductor layer, an emitter region of a second conductivity type, disposed at a front surface portion of the channel region, a drift region of the second conductivity type, disposed in the semiconductor layer at a rear surface side of the channel region, a collector region of the first conductivity type, disposed in the semiconductor layer at a rear surface side of the drift region, a gate trench, formed in the semiconductor layer, a gate electrode, embedded in the gate trench, and a convex region of the second conductivity type, projecting selectively from the drift region to the channel region side at a position separated from a side surface of the gate trench.

A diode includes an n type semiconductor layer including an n type cathode layer and an n type drift layer that has an impurity concentration lower than the n type cathode layer and that is disposed on the n type cathode layer, a p type anode layer disposed at a surface part of the n type drift layer, a p type hole implantation layer selectively disposed at the n type cathode layer, an anode electrode electrically connected to the p type anode layer, and a cathode electrode electrically connected to the n type cathode layer and to the p type hole implantation layer, and the p type hole implantation layer has a diameter of 20 μm or more.

In a method of manufacturing a semiconductor device having an oxide film removing step where an oxide film formed on a surface of a semiconductor substrate is partially removed, the oxide film removing step includes: a first step where a resist glass layer is selectively formed on an upper surface of the oxide film without using an exposure step; a second step where the resist glass layer is densified by baking the resist glass layer; and a third step where the oxide film is partially removed using the resist glass layer as a mask, wherein the resist glass layer is made of resist glass which contains at least SiO.sub.2, B.sub.2O.sub.3, Al.sub.2O.sub.3, and at least two oxides of alkaline earth metals selected from a group consisting of CaO, MgO and BaO, and substantially contains none of Pb, As, Sb, Li, Na, K, and Zn.