Abstract: A memristor has a first electrode, a second electrode parallel to the first electrode, and a switching layer disposing between the first and second electrodes. The switching layer contains a conduction channel and a reservoir zone. The conduction channel has a Fermi glass material with a variable concentration of mobile ions. The reservoir zone is laterally disposed relative to the conduction channel, and functions as a source/sink of mobile ions for the conduction channel. In the switching operation, under the cooperative driving force of both electric field and thermal effects, the mobile ions are moved into or out of the laterally disposed reservoir zone to vary the concentration of the mobile ions in the conduction channel to change the conductivity of the Fermi glass material.

Abstract: A semiconductor structure with an improved shallow trench isolation (STI) region and method of fabrication is disclosed. The STI region comprises a lower portion filled with oxide and an upper portion comprising a high Young's modulus (HYM) liner disposed on the lower portion and trench sidewalls and filled with oxide. The HYM liner is disposed adjacent to source-drain regions, and serves to reduce stress relaxation within the shallow trench isolation (STI) oxide, which has a relatively low Young's modulus and is soft. Hence, the HYM liner serves to increase the desired stress imparted by the embedded stressor source-drain regions, which enhances carrier mobility, thus increasing semiconductor performance.

Abstract: Provided are a semiconductor device and a method of manufacturing the same. The method of manufacturing a semiconductor device includes forming an active fin on a substrate; oxidizing a portion of the active fin to form an insulating pattern between the active fin and the substrate; forming a first gate pattern on the substrate, wherein the first gate pattern crosses the active fin; exposing the substrate on both sides of the first gate pattern; and forming source/drain regions on the exposed substrate.

Abstract: A semiconductor device according to embodiments includes a semiconductor substrate, first semiconductor layers of a first conductive type provided on a surface of the semiconductor substrate, extend in a first direction, and are surrounded by a gate layer, second semiconductor layers of the first conductive type provided between the first semiconductor layers, a third semiconductor layer of the first conductive type provided at ends of the first direction of the first semiconductor layers and is surrounded by the gate layer, a fourth semiconductor layer of a second conductive type provided in the semiconductor substrate, a sixth semiconductor layer of the first conductive type provided on a back surface of the semiconductor substrate, a seventh semiconductor layer of the second conductive type provided between the sixth semiconductor layer and the first semiconductor layers, an emitter electrode, and a collector electrode.

Abstract: Devices and methods for forming semiconductor devices with fins at tight fin pitches are provided. One method includes, for instance: obtaining an intermediate semiconductor device; growing an epi layer over the substrate; forming a doped layer below the epi layer; depositing a first oxide layer on the epi layer; applying a dielectric material on the first oxide layer; and depositing a lithography stack on the dielectric material. One intermediate semiconductor device includes, for instance: a substrate with at least one n-well region and at least one p-well region; a doped layer over the substrate; an epi layer over the doped layer; a first oxide layer over the epi layer; a dielectric layer over the first oxide layer; and a lithography stack over the dielectric layer.

Abstract: A semiconductor device includes a fin portion protruding from a substrate. The fin portion includes a base part, an intermediate part on the base part, and a channel part on the intermediate part. A width of the intermediate part is less than a width of the base part and greater than a width of the channel part. A gate electrode coves both sidewalls and a top surface of the channel part, and a device isolation pattern covers both sidewalls of the base part and both sidewalls of the intermediate part.

Abstract: A method of fabricating a FET device is provided that includes the following steps. A wafer is provided. At least one active area is formed in the wafer. A plurality of dummy gates is formed over the active area. Spaces between the dummy gates are filled with a dielectric gap fill material such that one or more keyholes are formed in the dielectric gap fill material between the dummy gates. The dummy gates are removed to reveal a plurality of gate canyons in the dielectric gap fill material. A mask is formed that divides at least one of the gate canyons, blocks off one or more of the keyholes and leaves one or more of the keyholes un-blocked. At least one gate stack material is deposited onto the wafer filling the gate canyons and the un-blocked keyholes. A FET device is also provided.

Abstract: A heat mitigated bipolar resistive switch includes a BRS matrix sandwiched between first and second electrodes and a heat mitigator. The BRS matrix is to support bipolar switching of a conduction channel formed between the first and second electrodes through BRS matrix. The heat mitigator is to reduce heat in the BRS matrix generated during bipolar switching. The heat mitigator includes one or both of a parallel-connected NDR element to limit current flowing in the BRS matrix and a high thermal conductivity material to conduct the generated heat away from the BRS matrix above a predetermined elevated temperature.

Abstract: A field effect transistor includes a stacked body, a source electrode, a drain electrode, a gate electrode, a dielectric layer and a silicon nitride layer. The stacked layer has a heterojunction made of a nitride semiconductor. The source and drain electrodes are provided on a surface of the stacked body. The gate electrode is provided on the surface of the stacked body between the source and the drain electrodes, and has a field plate portion. The dielectric layer is provided so as to cover an intersection line of a first side surface of the gate electrode and the surface of the stacked body. The silicon nitride layer is provided so as to cover a region between the source electrode and the gate electrode and a region between the dielectric layer and the drain electrode. The field plate portion protrudes from the first side surface.

Abstract: One illustrative method disclosed includes, among other things, forming a fin in a substrate, forming a well implant region in at least the substrate, forming a punch-stop implant region in the fin, performing at least one neutral implantation process with at least one neutral implant material to form a neutral boron-diffusion-blocking implant region in the fin, wherein an upper surface of the neutral boron-diffusion-blocking implant region is positioned closer to an upper surface of the fin than either the punch-stop implant region or the well implant region and, after forming the well implant region, the punch-stop implant region and the neutral boron-diffusion-blocking implant region, forming a gate structure above the fin.

Abstract: Systems and methods for molecular sensing are described. Molecular sensors are described which are based on field-effect or bipolar junction transistors. These transistors have a nanopillar with a functionalized layer contacted to either the base or the gate electrode. The functional layer can bind molecules, which causes an electrical signal in the sensor.

Abstract: Stacked chip systems and design structures for stacked chip systems, as well as methods and computer program products for placing thermal conduction paths in a stacked chip system. The method may include determining an availability of space in a layout of an interconnect structure of a first chip for a fill shape structure extending partially through the interconnect structure to thermally couple a metal feature in the interconnect structure with a bonding layer between the interconnect structure of the first chip and a second chip. If space is available, the fill shape structure may be placed in the layout of the interconnect structure of the first chip. The stacked chip system may include the first and second chips, the bonding layer between the interconnect structure of the first chip and the second chip, and the fill shape structure.

Abstract: A carbon nanotube composition that exhibits an excellent printability when use is made for a printing device, especially, exhibits an excellent prevention of drying on the printing apparatus. A carbon nanotube ink composition comprises carbon nanotubes, a solvent, an imidazolidinone compound represented by chemical formula (1) and a propylene urea compound represented by chemical formula (2).

Abstract: A composite high dielectric constant (high-k) gate dielectric includes a stack of a doped high-k gate dielectric and an undoped high-k gate dielectric. The doped high-k gate dielectric can be formed by providing a stack of a first high-k dielectric material layer and a dopant metal layer and annealing the stack to induce the diffusion of the dopant metal into the first high-k dielectric material layer. The undoped high-k gate dielectric is formed by subsequently depositing a second high-k dielectric material layer. The composite high-k gate dielectric can provide an increased gate-leakage oxide thickness without increasing inversion oxide thickness.

Abstract: Collections of laterally crystallized semiconductor islands for use in thin film transistors and systems and methods for making same are described. A display device includes a plurality of thin film transistors (TFTs) on a substrate, such that the TFTs are spaced apart from each other and each include a channel region that has a crystalline microstructure and a direction along which a channel current flows. The channel region of each of the TFTs contains a crystallographic grain that spans the length of that channel region along its channel direction. Each crystallographic grain in the channel region of each of the TFTs is physically disconnected from and crystallographically uncorrelated with each crystallographic grain in the channel region of each adjacent TFT.

Abstract: An integrated circuit with electrically programmable fuse circuitry coupled to a programming transistor is provided. The programming transistor may be a metal-oxide-semiconductor transistor that is separated from other circuitry in an integrated circuit substrate with shallow trench isolation. The electrically programmable fuse circuitry may be formed in a second layer above the integrated circuit substrate using a conductive material which may be tungsten-based. This second layer may further include interconnect wires made from the same conductive material. The electrically programmable fuse may be coupled to the programming transistor through vias and routing paths in a fourth layer above the integrated circuit substrate. The routing paths in the fourth layer may be made from a conductive material which may be different than the fuse conductive material used to form the programmable fuse circuitry.

Abstract: An electronic isolation device is formed on a monolithic substrate and includes a plurality of passive isolation components. The isolation components are formed in three metal levels. The first metal level is separated from the monolithic substrate by an inorganic PMD layer. The second metal level is separated from the first metal level by a layer of silicon dioxide. The third metal level is separated from the second metal level by at least 20 microns of polyimide or PBO. The isolation components include bondpads on the third metal level for connections to other devices. A dielectric layer is formed over the third metal level, exposing the bondpads. The isolation device contains no transistors.

Abstract: An insulating layer is provided with a projecting structural body, and a channel formation region of an oxide semiconductor layer is provided in contact with the projecting structural body, whereby the channel formation region is extended in a three dimensional direction (a direction perpendicular to a substrate). Thus, it is possible to miniaturize a transistor and to extend an effective channel length of the transistor. Further, an upper end corner portion of the projecting structural body, where a top surface and a side surface of the projecting structural body intersect with each other, is curved, and the oxide semiconductor layer is formed to include a crystal having a c-axis perpendicular to the curved surface.

Abstract: A semiconductor device including a semiconductor substrate having a surface including an active semiconductor device including one of a laser and a photodiode; and a visual indicator disposed on the semiconductor body and at least adjacent to a portion of said active semiconductor device, the indicator having a state that shows if damage to the active semiconductor device may have occurred.

Abstract: A thin-film transistor having a protection layer for a planarization layer. The protection layer prevents reduction of the planarization layer during an ashing process, thereby preventing the formation of a steeply tapered via hole through the planarization layer. In this manner, the via hole may be coated with a conductive element that may serve as a conductive path between a common electrode and the drain of the transistor.

Abstract: The control of gate widths is improved for system-on-a-chip (SoC) devices which require multiple gate dielectric “gate” thicknesses, e.g., for analog and digital processing on the same chip. A hard mask is formed to protect a thick gate while the thin gate region is etched to remove oxide (sometimes referred to as a preclean step). The patterned substrate is then processed to selectively deposit a second thickness of gate material. The thin gate may be silicon oxide and the physical thickness of the thin gate may be less than that of the thick gate. In a preferred embodiment, the substrate is not exposed to air or atmosphere after the hardmask is removed.

Abstract: Insulating layers can be formed over a semiconductor device region and etched in a manner that substantially reduces or prevents the amount of etching of the underlying channel region. A first insulating layer can be formed over a gate region and a semiconductor device region. A second insulating layer can be formed over the first insulating layer. A third insulating layer can be formed over the second insulating layer. A portion of the third insulating layer can be etched using a first etching process. A portion of the first and second insulating layers beneath the etched portion of the third insulating layer can be etched using at least a second etching process different from the first etching process.

Abstract: A method of trimming spacers includes etching a silicon oxide spacer when forming an outmost spacer, so that a silicon carbon nitride spacer contacting the gate electrode exposes an area. The exposure area of the silicon carbon nitride spacer can then be partly removed by phosphate acid. At the end of the semiconductor process, at least part of the top surface of the silicon carbon nitride spacer will be lower than the top surface of a gate electrode.

Abstract: A TSV structure, method of making the TSV structure and methods of testing the TSV structure. The structure including: a trench extending from a top surface of a semiconductor substrate to a bottom surface of the semiconductor substrate, the trench surrounding a core region of the semiconductor substrate; a dielectric liner on all sidewalls of the trench; and an electrical conductor filling all remaining space in the trench, the dielectric liner electrically isolating the electrical conductor from the semiconductor substrate and from the core region.

Abstract: A MOS transistor includes a gate structure on a substrate, and the gate structure includes a wetting layer, a transitional layer and a low resistivity material from bottom to top, wherein the transitional layer has the properties of a work function layer, and the gate structure does not have any work function layers. Moreover, the present invention provides a MOS transistor process forming said MOS transistor.

Abstract: A semiconductor device with buried word line structures and methods of forming the semiconductor device are provided. The semiconductor device includes a plurality of insulating line patterns extending in a direction in a substrate, a plurality of word lines alternately with ones of the plurality of insulating line patterns, the plurality of word lines extending in the direction and comprising a metal, a plurality of first doped regions on respective ones of the plurality of the word lines and between two adjacent ones of the plurality of insulating line patterns, an interlayer insulating film on the plurality of insulating line patterns and the plurality of first doped regions, the interlayer insulating film including a plurality of openings exposing upper surfaces of ones of the plurality of first doped regions and a plurality of second doped regions contacting respective ones of the plurality of first doped regions within the openings.

Abstract: One method disclosed herein includes, prior to forming an isolation region in a semiconducting substrate for the device, forming a doped well region and a doped punch-stop region in the substrate, introducing a dopant material that is adapted to retard diffusion of boron or phosphorous into the substrate to form a dopant-containing layer proximate an upper surface of the substrate, performing an epitaxial deposition process to form an undoped semiconducting material above the dopant-containing layer, forming a plurality of spaced-apart trenches that extend at least partially into the substrate, wherein the trenches define a fin for the device comprised of at least the undoped semiconducting material, forming at least a local isolation insulating material in the trenches, and forming a gate structure around at least the undoped semiconducting material, wherein a bottom of a gate electrode is positioned approximately level with or below a bottom of the undoped semiconducting material.

Abstract: Semiconductor devices are provided. A semiconductor device may include a transistor area and a resistor area. The transistor area may include a gate structure. The resistor area may include an insulating layer and a resistor structure on the insulating layer. A top surface of the gate structure and a top surface of the resistor structure may be substantially coplanar.

Abstract: In one general aspsect, a semiconductor device can include at least a first device region and a second device region disposed at a surface of a semiconductor region where the second device region is adjacent to the first device region and spaced apart from the first device region. That semiconductor device can include a connection region disposed between the first device region and the second device region, and a trench extending into the semiconductor region and at least extending from the first device region, through the connection region, and to the second device region. The semiconductor device can include a dielectric layer lining opposing sidewalls of the trench, an electrode disposed in the trench, and a conductive trace disposed over a portion of the trench in the connection region and electrically coupled to a portion of the electrode disposed in the connection region.

Abstract: The present disclosure is directed to a method of manufacturing a FinFET structure in which at least one initial set of fin structures is formed by photolithographic processes, followed by forming an additional fin structure by epitaxial growth of a semiconductor material between the initial set of fin structures. The method allows for formation of FinFET structures having increased fin density.

Abstract: A design structure is embodied in a machine readable medium for designing, manufacturing, or testing a design. The design structure includes a high-leakage dielectric formed over an active region of a FET and a low-leakage dielectric formed on the active region and adjacent the high-leakage dielectric. The low-leakage dielectric has a lower leakage than the high-leakage dielectric. Also provided is a structure and method of fabricating the structure.

Abstract: A method of fabricating a FET device is provided that includes the following steps. A wafer is provided. At least one active area is formed in the wafer. A plurality of dummy gates is formed over the active area. Spaces between the dummy gates are filled with a dielectric gap fill material such that one or more keyholes are formed in the dielectric gap fill material between the dummy gates. The dummy gates are removed to reveal a plurality of gate canyons in the dielectric gap fill material. A mask is formed that divides at least one of the gate canyons, blocks off one or more of the keyholes and leaves one or more of the keyholes un-blocked. At least one gate stack material is deposited onto the wafer filling the gate canyons and the un-blocked keyholes. A FET device is also provided.

Abstract: To provide a semiconductor element in which generation of oxygen vacancies in an oxide semiconductor thin film can be suppressed. The semiconductor element has a structure in which, in a gate insulating film, the nitrogen content of regions which do not overlap with a gate electrode is higher than the nitrogen content of a region which overlaps with the gate electrode. A nitride film has an excellent property of preventing impurity diffusion; thus, with the structure, release of oxygen in the oxide semiconductor film, in particular, in the channel formation region, to the outside of the semiconductor element can be effectively suppressed.

Abstract: A semiconductor device including an NMOS region and a PMOS region; the NMOS region having a gate structure including a first high-k gate dielectric, a first work function setting metal and a gate electrode fill material; the PMOS region having a gate structure comprising a second high-k gate dielectric, a second work function setting metal and a gate electrode fill material; wherein the first gate dielectric is different than the second gate dielectric and the first work function setting metal is different than the second work function setting metal. Also disclosed are methods for fabricating the semiconductor device which include a gate last process.

Abstract: In the condition where a nozzle for applying a coating liquid is disposed on the lower side of a substrate and a substrate surface controlled in wettability is faced down, the nozzle and the substrate are moved relative to each other, whereby the coating liquid is applied to a desired region of the substrate, and then the coating liquid is dried, to obtain a pattern included a dried coating layer.

Abstract: A device and method for fabrication includes providing a first substrate assembly including a first substrate and a first metal layer formed on the first substrate and a second substrate assembly including a second substrate and a second metal layer formed on the second substrate. The first metal layer is joined to the second metal layer using a cold welding process wherein one of the first substrate and the second substrate includes a semiconductor channel layer for forming a transistor device.

Abstract: A compound semiconductor device includes a substrate having an opening formed from the rear side thereof; a compound semiconductor layer disposed over the surface of the substrate; a local p-type region in the compound semiconductor layer, partially exposed at the end of the substrate opening; and a rear electrode made of a conductive material, disposed in the substrate opening so as to be connected to the local p-type region.

Abstract: A larger substrate can be used, and a transistor having a desirably high field-effect mobility can be manufactured through formation of an oxide semiconductor layer having a high degree of crystallinity, whereby a large-sized display device, a high-performance semiconductor device, or the like can be put into practical use. A first multi-component oxide semiconductor layer is formed over a substrate and a single-component oxide semiconductor layer is formed thereover; then, crystal growth is carried out from a surface to an inside by performing heat treatment at 500° C. to 1000° C. inclusive, preferably 550° C. to 750° C. inclusive so that a first multi-component oxide semiconductor layer including single crystal regions and a single-component oxide semiconductor layer including single crystal regions are formed; and a second multi-component oxide semiconductor layer including single crystal regions is stacked over the single-component oxide semiconductor layer including single crystal regions.

Abstract: A semiconductor device may include a first transistor, a second transistor connected in series to the first transistor through a first junction, and a third transistor connected in series to the second transistor through a second junction. Here, a high voltage is supplied to one of the first and second junctions, and a turn-off voltage is supplied to a gate of the second transistor.

Abstract: An object is to provide a semiconductor device with improved reliability in which a defect stemming from an end portion of a semiconductor layer provided in an island shape is prevented, and a manufacturing method thereof. Over a substrate having an insulating surface, an island-shaped semiconductor layer is formed, a first alteration treatment is performed, a first insulating film is formed on a surface of the island-shaped semiconductor layer, the first insulating film is removed, a second alteration treatment is performed on the island-shaped semiconductor from which the first insulating film is removed, a second insulating film is formed on a surface of the island-shaped semiconductor layer, and a conductive layer is formed over the second insulating film. An upper end portion of the island-shaped semiconductor layer has curvature by the first alteration treatment and the second alteration treatment.

Abstract: A semiconductor device is provided that includes a fin having a first gate and a second gate formed on a first sidewall of the fin in a first trench, wherein the first gate is formed above the second gate. The device includes a third gate and a fourth gate formed on a second sidewall of the fin in a second trench, wherein the third gate is formed above the fourth gate. Methods of manufacturing and operating the device are also included. A method of operation may include biasing the first gate and the fourth gate to create a current path across the fin.

Abstract: According to one embodiment, a solid-state imaging device includes a first element formation region surrounded by an element isolation region in a semiconductor substrate having a first and a second surface, an upper element isolation layer on the first surface in the element formation region, a lower element isolation layer between the second surface and the upper element isolation layer, a first photodiode in the element formation region, a floating diffusion in the element formation region, and a first transistor disposed between the first photodiode and the floating diffusion. A side surface of the lower element isolation layer protrudes closer to the transistor than a side surface of the upper element isolation layer.

Abstract: In order to suppress an off leak current of an off transistor for ESD protection, in an NMOS for ESD protection whose isolation region has a shallow trench structure, a drain region is placed apart from the shallow trench isolation region so as not to be in direct contact with the shallow trench isolation region in a region where the drain region of the NMOS transistor for ESD protection is adjacent to at least a gate electrode of the NMOS transistor for ESD protection.

Abstract: A power semiconductor device includes: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type and a third semiconductor layer of a second conductivity type formed on the first semiconductor layer and alternately arranged along at least one direction parallel to a surface of the first semiconductor layer; a first main electrode; a fourth semiconductor layer of the second conductivity type selectively formed in a surface of the second semiconductor layer and a surface of the third semiconductor layer; a fifth semiconductor layer of the first conductivity type selectively formed in a surface of the fourth semiconductor layer; a second main electrode; and a control electrode. At least one of the second and the third semiconductor layers has a dopant concentration profile along the one direction, the dopant concentration profile having a local minimum at a position except both ends thereof.

Abstract: A gate-first processing scheme for forming a nanomesh field effect transistor is provided. An alternating stack of two different semiconductor materials is patterned to include two pad regions and nanowire regions. A semiconductor material is laterally etched selective to another semiconductor material to form a nanomesh including suspended semiconductor nanowires. A stack of a gate dielectric, a gate electrode, and a gate cap dielectric is formed over the nanomesh. A dielectric spacer is formed around the gate electrode. An isotropic etch is employed to remove dielectric materials that are formed in lateral recesses of the patterned alternating stack. A selective epitaxy process can be employed to form a source region and a drain region.

Abstract: Semiconductor devices including a substrate (e.g., silicon substrate), a multi-layer structure disposed on a portion of the substrate, and at least one electrode disposed on the multi-layer structure and methods of manufacturing the same are provided. The multi-layer structure may include an active layer containing a Group III-V material and a current blocking layer disposed between the substrate and the active layer. The semiconductor device may further include a buffer layer disposed between the substrate and the active layer. In a case that the substrate is a p-type, the buffer layer may be an n-type material layer and the current blocking layer may be a p-type material layer. The current blocking layer may contain a Group III-V material. A mask layer having an opening may be disposed on the substrate so that the multi-layer structure may be disposed on the portion of the substrate exposed by the opening.

Abstract: A method of forming a semiconductor device that includes forming a high-k gate dielectric layer on a semiconductor substrate, wherein an oxide containing interfacial layer can be present between the high-k gate dielectric layer and the semiconductor substrate. A scavenging metal stack may be formed on the high-k gate dielectric layer. An annealing process may be applied to the scavenging metal stack during which the scavenging metal stack removes oxide material from the oxide containing interfacial layer, wherein the oxide containing interfacial layer is thinned by removing of the oxide material. A gate conductor layer is formed on the high-k gate dielectric layer. The gate conductor layer and the high-k gate dielectric layer are then patterned to provide a gate structure. A source region and a drain region are then formed on opposing sides of the gate structure.

Abstract: A method of forming a semiconductor device that includes forming a high-k gate dielectric layer on a semiconductor substrate, wherein an oxide containing interfacial layer can be present between the high-k gate dielectric layer and the semiconductor substrate. A scavenging metal stack may be formed on the high-k gate dielectric layer. An annealing process may be applied to the scavenging metal stack during which the scavenging metal stack removes oxide material from the oxide containing interfacial layer, wherein the oxide containing interfacial layer is thinned by removing of the oxide material. A gate conductor layer is formed on the high-k gate dielectric layer. The gate conductor layer and the high-k gate dielectric layer are then patterned to provide a gate structure. A source region and a drain region are then formed on opposing sides of the gate structure.

Abstract: A nano resonator includes a substrate, a first insulating layer disposed on the substrate, a first source disposed on the first insulating layer at a first position, a first drain disposed on the first insulating layer at a second position spaced apart from the first position so that the first drain faces the first source, a first nano-wire channel having a first end connected to the first source and a second end connected to the first drain, and having a doping type and a doping concentration that are identical to a doping type and a doping concentration of the first source and the first drain, and a second nano-wire channel disposed at a predetermined distance from the first nano-wire channel in a direction perpendicular to the substrate or a direction parallel to the substrate.

Abstract: A solid-state image sensor includes a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type that is arranged to contact a lower face of the first semiconductor region and functions as a charge accumulation region, a third semiconductor region including side faces surrounded by the second semiconductor region, a fourth semiconductor region of the second conductivity type that is arranged apart from the second semiconductor region, and a transfer gate that forms a channel to transfer charges accumulated in the second semiconductor region to the fourth semiconductor region. The third semiconductor region is one of a semiconductor region of the first conductivity type and a semiconductor region of the second conductivity type whose impurity concentration is lower than that in the second semiconductor region.