Abstract: The present invention discloses a lateral double diffused metal oxide semiconductor (LDMOS) device and a manufacturing method thereof. The LDMOS device is formed in a first conductive type substrate, and includes a high voltage well, a first field oxide region, at least one second field oxide region, a source, a drain, a body region, and a gate. The second field oxide region is located between the first field oxide region and the drain from top view. The distribution of the concentration of the second conductive type impurities in the high voltage well is related to the location of the second field oxide region.

Abstract: A drift layer of a super junction semiconductor device includes first portions of a first conductivity type and second portions of a second conductivity type opposite to the first conductivity type. The first and second portions are formed both in a cell area and in an edge area surrounding the cell area, wherein an on-state or forward current through the drift layer flows through the first portions in the cell area. At least one of the first and second portions other than the first portions in the cell area includes an auxiliary structure or contains auxiliary impurities to locally reduce the avalanche rate. Locally reducing the avalanche rate increases the total voltage blocking capability of the super junction semiconductor device.

Abstract: Methods and systems for improved analog performance of core CMOS transistors may comprise a semiconductor die comprising both input/output (I/O) complementary metal oxide semiconductor (CMOS) transistors and core CMOS transistors. A doping profile of a subset of the core CMOS transistors may comprise lightly-doped drain and pocket implant layers between source and drain layers below a gate insulator, and a doping profile of another subset of the core CMOS transistors may be constant between source and drain layer. The core CMOS devices may comprise sub-100 nanometer gate lengths. An output resistance of the second subset of the core CMOS transistors may be increased by the constant doping profile between the source and drain layers. The second subset of the core CMOS transistors may be operable to amplify analog signals. The first subset of the core CMOS transistors may be operable to process digital signals.

Abstract: A method of forming a semiconductor structure includes providing an active layer and forming adjacent gate structures on the active layer. The gate structures each have sidewalls such that first spacers are formed on the sidewalls. A raised region is epitaxially grown on the active layer between the adjacent gate structures and at least one trench that extends through the raised region and through the active region is formed, whereby the at least one trench separates the raised region into a first raised region corresponding to a first transistor and a second raised region corresponding to a second transistor. The first raised region and second raised region are electrically isolated by the at least one trench.

Abstract: A method of making a silicon-on-insulator (SOI) semiconductor device includes etching an undercut isolation trench into an SOI substrate, the SOI substrate comprising a bottom substrate, a buried oxide (BOX) layer formed on the bottom substrate, and a top SOI layer formed on the BOX layer, wherein the undercut isolation trench extends through the top SOI layer and the BOX layer and into the bottom substrate such that a portion of the undercut isolation trench is located in the bottom substrate underneath the BOX layer. The undercut isolation trench is filled with an undercut fill comprising an insulating material to form an undercut isolation region. A field effect transistor (FET) device is formed on the top SOI layer adjacent to the undercut isolation region, wherein the undercut isolation region extends underneath a source/drain region of the FET.

Abstract: A memory cell and a peripheral circuit each having a gate electrode are formed on a semiconductor substrate. The periphery of the gate electrodes is covered with an organic insulating layer. A stopper film and a hard mask layer are formed on the gate electrodes and the organic insulating layer, and contact holes are formed between the gate electrodes in a self-aligning manner. Contact electrodes are embedded in the contact holes to provide electrical connection to diffusion layers formed on the semiconductor substrate on either side of each gate electrode.

Abstract: Transistor devices which include semiconductor layers with integrated hole collector regions are described. The hole collector regions are configured to collect holes generated in the transistor device during operation and transport them away from the active regions of the device. The hole collector regions can be electrically connected or coupled to the source, the drain, or a field plate of the device. The hole collector regions can be doped, for example p-type or nominally p-type, and can be capable of conducting holes but not electrons.

Abstract: A semiconductor device includes a cell region and a contact region, the cell region including a functional unit including a gate electrode, a source and a drain electrode, and the contact region including a gate pad. The gate electrode, the gate pad and the source electrode are disposed on a first main surface of a semiconductor substrate, and the drain electrode is disposed on a second main surface of the semiconductor substrate, the second main surface being opposite to the first main surface. A shielding member is disposed between the gate pad and the drain electrode, the shielding member being electrically connected to the source electrode.

Abstract: The disclosure relates to a dummy gate electrode of a semiconductor device. An embodiment comprises a substrate comprising a first surface; an insulation region covering a portion of the first surface, wherein the top of the insulation region defines a second surface; and a dummy gate electrode over the second surface, wherein the dummy gate electrode comprises a bottom and a base broader than the bottom, wherein a ratio of a width of the bottom to a width of the base is from about 0.5 to about 0.9.

Abstract: Isolated and bulk semiconductor devices formed on a same bulk substrate and methods to form such devices are described. For example, a semiconductor structure includes a first semiconductor device having a first semiconductor body disposed on a bulk substrate. The first semiconductor body has an uppermost surface with a first horizontal plane. The semiconductor structure also includes a second semiconductor device having a second semiconductor body disposed on an isolation pedestal. The isolation pedestal is disposed on the bulk substrate. The second semiconductor body has an uppermost surface with a second horizontal plane. The first and second horizontal planes are co-planar.

Abstract: A CMOS device structure and method of manufacturing the same are provided. The CMOS device structure includes a substrate having a first region and a second region. The CMOS device structure further includes a first gate formed in the first region overlying a first channel region in the substrate. The CMOS device structure further includes a first pair of source/drain regions formed in the first region on either side of the first channel region. Each region of the pair of source/drain regions has a substantially V-shaped concave top surface.

Abstract: An integrated circuit is provided. The integrated circuit includes a substrate, a first FinFET device supported by the substrate, the first FinFET device having a first fin with a non-tiered fin profile, and a second FinFET supported by the substrate, the second FinFET having a second fin with a tiered fin profile.

Abstract: One illustrative device disclosed herein includes a continuous active region defined in a semiconducting substrate, first and second transistors formed in and above the continuous active region, each of the first and second transistors comprising a plurality of doped regions formed in the continuous active region, a conductive isolating electrode positioned above the continuous active region between the first and second transistors and a power rail conductively coupled to the conductive isolating electrode.

Abstract: A semiconductor integrated circuit designing method capable of minimizing a parasitic capacitance generated by an overhead in conductive lines, especially a gate line, a semiconductor integrated circuit according to the designing method, and a fabricating method thereof are provided. A method of designing a semiconductor integrated circuit having a FinFET architecture, includes: performing a pre-simulation of the semiconductor integrated circuit to be designed; designing a layout of components of the semiconductor integrated circuit based on a result of the pre-simulation, the components comprising first and second device areas and a first conductive line extending across the first and second device areas; modifying a first cutting area, that is arranged between the first and second device areas and electrically cuts the first conductive line, according to at least one design rule to minimize an overhead of the first conductive line created by the first cutting area.

Abstract: The present disclosure relates to a semiconductor device and a method of manufacturing the same. The semiconductor device may include a first metal gate electrode provided in a NMOS region of a substrate; and a second metal gate electrode provided in a PMOS region of the substrate, wherein the first and second metal gate electrodes may be formed of TiN material or TiAlN material. Here, the first metal gate electrode may have a higher titanium (Ti) content than the second metal gate electrode, and the second metal gate electrode may have a higher nitrogen (N) content than the first metal gate electrode.

Abstract: The present disclosure describes a semiconductor device. The device includes a semiconductor substrate, an isolation structure formed in the substrate for isolating a first active region and a second active region, a first transistor formed in the first active region, the first transistor having a high-k gate dielectric layer and a metal gate with a first work function formed over the high-k gate dielectric layer, and a second transistor formed in the second active region, the second transistor having the high-k gate dielectric layer and a metal gate with a second work function formed over the high-k gate dielectric layer. The metal gates are formed from at least a single metal layer having the first work function and the second work function.

Abstract: Systems and methods are disclosed for processing radio frequency (RF) signals using one or more FET transistors disposed on or above a high-resistivity region of a substrate. The substrate may include bulk silicon, at least a portion of which has high-resistivity characteristics. For example, the bulk substrate may have a resistivity greater than 500 Ohm*cm, such as around 1 kOhm*cm. In certain embodiments, one or more of the FET devices are surrounded by a low-resistivity implant configured to reduce effects of harmonic and other interference.

Abstract: One feature pertains to an integrated circuit, comprising an access transistor and an antifuse. The access transistor includes at least one source/drain region, and the antifuse has a conductor-insulator-conductor structure. The antifuse includes a first conductor that acts as a first electrode, and also includes an antifuse dielectric, and a second conductor. A first surface of the first electrode is coupled to a first surface of the antifuse dielectric, a second surface of the antifuse dielectric is coupled to a first surface of the second conductor. The second conductor is electrically coupled to the access transistor's source/drain region. The antifuse is adapted to transition from an open circuit state to a closed circuit state if a programming voltage Vpp greater than or equal to an antifuse dielectric breakdown voltage is applied between the first electrode and the second conductor.

Abstract: High voltage three-dimensional devices having dielectric liners and methods of forming high voltage three-dimensional devices having dielectric liners are described. For example, a semiconductor structure includes a first fin active region and a second fin active region disposed above a substrate. A first gate structure is disposed above a top surface of, and along sidewalls of, the first fin active region. The first gate structure includes a first gate dielectric composed of a first dielectric layer disposed on the first fin active region, and a second, different, dielectric layer disposed on the first dielectric layer. The semiconductor structure also includes a second gate structure disposed above a top surface of, and along sidewalls of, the second fin active region. The second gate structure includes a second gate dielectric composed of the second dielectric layer disposed on the second fin active region.

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: A semiconductor structure includes first, second, and third transistor elements each having a first screening region concurrently formed therein. A second screening region is formed in the second and third transistor elements such that there is at least one characteristic of the screening region in the second transistor element that is different than the second screening region in the third transistor element.

Abstract: Through gate fin isolation for non-planar transistors in a microelectronic device, such as an integrated circuit (IC). In embodiments, ends of adjacent semiconductor fins are electrically isolated from each other with an isolation region that is self-aligned to gate electrodes of the semiconductor fins enabling higher transistor packing density and other benefits. In an embodiment, a single mask is employed to form a plurality of sacrificial placeholder stripes of a fixed pitch, a first subset of placeholder stripes is removed and isolation cuts made into the semiconductor fins in openings resulting from the first subset removal while a second subset of the placeholder stripes is replaced with gate electrodes.

Abstract: A semiconductor structure is provided. The structure includes a semiconductor substrate of a semiconductor material and a gate dielectric having a high dielectric constant dielectric layer with a dielectric constant greater than silicon. The gate dielectric is located on the semiconductor substrate. A gate electrode abuts the gate dielectric. The gate electrodes includes a lower metal layer abutting the gate dielectric, a scavenging metal layer abutting the lower metal layer, an upper metal layer abutting the scavenging metal layer, and a silicon layer abutting the upper metal layer. The scavenging metal layer reduces an oxidized layer at an interface between the upper metal layer and the silicon layer responsive to annealing.

Abstract: Improved silicide formation and associated devices are disclosed. An exemplary semiconductor device includes a semiconductor substrate, a fin structure disposed over the semiconductor substrate and having spaced source and drain regions extending outwardly from a channel region, and a gate structure disposed on a portion of the fin structure, the gate structure engaging the fin structure adjacent to the channel region. The device also includes a first silicide layer disposed on the fin structure, the first silicide layer extending outwardly from the gate structure along a top portion of the source region and a second silicide layer disposed on the fin structure, the second silicide layer extending outwardly from the gate structure along a top portion of the drain region. Further, the device includes a source contact conductively coupled to the first silicide layer and a drain contact conductively coupled to the second silicide layer.

Abstract: A method of manufacturing multiple finFET devices having different thickness gate oxides. The method may include depositing a first dielectric layer on top of the semiconductor substrate, on top of a first fin, and on top of a second fin; forming a first dummy gate stack; forming a second dummy gate stack; removing the first and second dummy gates selective to the first and second gate oxides; masking a portion of the semiconductor structure comprising the second fin, and removing the first gate oxide from atop the first fin; and depositing a second dielectric layer within the first opening, and within the second opening, the second dielectric layer being located on top of the first fin and adjacent to the exposed sidewalls of the first pair of dielectric spacers, and on top of the second gate oxide and adjacent to the exposed sidewalls of the second pair of dielectric spacers.

Abstract: Semiconductor devices, methods and apparatus for forming the same are provided. The semiconductor device includes a substrate having a source and drain region and a gate electrode stack on the substrate between the source and drain regions. The gate electrode stack includes a conductive film layer on a gate dielectric layer, a refractory metal silicon nitride film layer on the conductive film layer, and a tungsten film layer on the refractory metal silicon nitride film layer. In one embodiment, the method includes positioning a substrate within a processing chamber, wherein the substrate includes a source and drain region, a gate dielectric layer between the source and drain regions, and a conductive film layer on the gate dielectric layer. The method also includes depositing a refractory metal silicon nitride film layer on the conductive film layer and depositing a tungsten film layer on the refractory metal silicon nitride film layer.

Abstract: A method for producing a MEMS device having improved charge elimination characteristics includes providing a substrate having one or more layers, and applying a first charge elimination layer onto at least one portion of one given layer of the substrate. The method may then (1) apply a sacrificial layer onto the first charge elimination layer, (2) apply a second charge elimination layer onto at least a portion of the sacrificial layer, and (3) deposit a movable layer onto at least a portion of the second charge elimination layer. To form a structure within the movable layer the method may etch the movable layer. The method may then etch the sacrificial layer to release the structure.

Abstract: A gas pressure measuring cell configuration has a thermal conduction vacuum cell according to Pirani (Pi), with a measuring chamber housing enclosing a measuring chamber and with a measuring connection which channels the gas pressure P to be measured into the measuring chamber. The measuring chamber has a heatable measuring filament connected to an electronic measuring circuitry. The electronic measuring circuitry is in thermal contact on one side of an insulating carrier plate and the carrier plate forms on the opposite side a component of the measuring chamber housing, wherein the measuring filament in series with a measuring resistor (Rm) is supplied directly by the electronic measuring circuitry in feedback and wherein the electronic measuring circuitry directly determines the resistance of the measuring filament.

Abstract: A Micro Electromechanical System (MEMS) pressure sensor may include a first substrate provided with a sensitive diaphragm of a capacitive pressure sensing unit, an electrical connecting layer and a first bonding layer on a surface of the first substrate; and a second substrate provided with an inter-conductor dielectric layer, a conductor connecting layer in the inter-conductor dielectric layer and/or a second bonding layer on a surface of the second substrate. The second substrate is arranged opposite to the first substrate, and the second substrate is fixedly coupled to the first substrate via the first bonding layer and the second bonding layer; a pattern of the first bonding layer is corresponding to a pattern of the second bonding layer, and both the first bonding layer and the second bonding layer are formed of a conductive material.

Abstract: A packaged integrated device includes a package substrate having a first surface and a second surface opposite the first surface, and the package substrate has a hole therethrough. The integrated device package also includes a first lid mounted on the first surface of the package substrate to define a first cavity, and a second lid mounted on the second surface of the package substrate to define a second cavity. A microelectromechanical systems (MEMS) die can be mounted on the first surface of the package substrate inside the first cavity and over the hole. A port can be formed in the first lid or the second lid.

Abstract: A micro-electro-mechanical system (MEMS) microphone may include a sensitive diaphragm and a fixed electrode corresponding to the sensitive diaphragm; at least one sensitive diaphragm support located on the surface of the sensitive diaphragm corresponding to the fixed electrode; and a sensitive diaphragm support arm coupled to the sensitive diaphragm support.

Abstract: A semiconductor device package having a cavity formed using film-assisted molding techniques is provided. Through the use of such techniques the cavity can be formed in specific locations in the molded package, such as on top of a device die mounted on the package substrate or a lead frame. In order to overcome cavity wall angular limitations introduced by conformability issues associated with film-assisted molding, a gel reservoir feature is formed so that gel used to protect components in the cavity does not come in contact with a lid covering the cavity or the junction between the lid and the package attachment region. The gel reservoir is used in conjunction with a formed level setting feature that controls the height of gel in the cavity. Benefits include decreased volume of the cavity, thereby decreasing an amount of gel-fill needed and thus reducing production cost of the package.

Abstract: An apparatus including a die including a first side and an opposite second side including a device side with contact points and lateral sidewalls defining a thickness of the die; a build-up carrier coupled to the second side of the die, the build-up carrier including a plurality of alternating layers of conductive material and insulating material, wherein at least one of the layers of conductive material is coupled to one of the contact points of the die; and at least one device within the build-up carrier disposed in an area void of a layer of patterned conductive material. A method and an apparatus including a computing device including a package including a microprocessor are also disclosed.

Abstract: An MEMS pressure sensor comprising: a first substrate (100) having a sensing diaphragm (101a) of a piezoelectric pressure sensing unit (101), an electrical connection diffusion layer (103), and a first bonding layer (102) on a surface of the first substrate (100), a second substrate (200) having an inter-conductor dielectric layer (203), a conductor connection layer (201) arranged within the inter-conductor dielectric layer (203), and a second bonding layer (202) on a surface of the second substrate (200). The second substrate (200) and the first substrate (100) are oppositely arranged, and are fixedly coupled via the first bonding layer (102) and the second bonding layer (202); the first bonding layer (102) and the second bonding layer (202) have matching patterns and are both made from a conductive material. Also provided is a method for manufacturing the MEMS pressure sensor.

Abstract: Various embodiments may configure a magnetic stack with a magnetically free layer, a reference structure, and a biasing layer. The magnetically free layer and reference structure can each be respectively configured with first and second magnetizations aligned along a first plane while the biasing layer has a third magnetization aligned along a second plane, substantially perpendicular to the first plane.

Abstract: Provided is a perpendicularly magnetized magnetic tunnel junction device including at least one multi-layer. The multi-layer includes a first metal oxide layer, a first ferromagnetic layer, a first modified layer and a second ferromagnetic layer. The first ferromagnetic layer is located on the first metal oxide layer, and the second ferromagnetic layer is located on the first ferromagnetic layer. The first modified layer is sandwiched between the first ferromagnetic layer and the second ferromagnetic layer.

Abstract: A storage element including a storage layer configured to hold information by use of a magnetization state of a magnetic material, with a pinned magnetization layer being provided on one side of the storage layer, with a tunnel insulation layer, and with the direction of magnetization of the storage layer being changed through injection of spin polarized electrons by passing a current in the lamination direction, so as to record information in the storage layer, wherein a spin barrier layer configured to restrain diffusion of the spin polarized electrons is provided on the side, opposite to the pinned magnetization layer, of the storage layer; and the spin barrier layer includes at least one material selected from the group composing of oxides, nitrides, and fluorides.

Abstract: Monolithic optical sensor devices, and methods for fabricating such devices, are described herein. In an embodiment, a semiconductor wafer substrate includes a plurality of photodetector (PD) regions. A wafer-level inorganic dielectric optical filter is deposited and thereby formed over at least a subset of the plurality of PD regions. One or more wafer-level organic color filter(s) is/are deposited and thereby formed on one or more selected portion(s) of the wafer-level inorganic dielectric optical filter that is/are over selected ones of the PD regions. For example, an organic red filter, an organic green filter and an organic blue filter can be over, respectively, portions of the wafer-level inorganic dielectric optical filter that are over first, second and third PD regions.

Abstract: In an image sensor, if a pixel for focusing has a structure having a light-shielding layer for performing pupil division, between the micro lens and the photoelectric conversion unit, the pixel may be configured such that the focal position of the micro lens is positioned further on the micro lens side than the light-shielding layer, and the distance from the focal position of the micro lens to the light-shielding layer is greater than 0 and less than nF?, where n is the refractive index at the focal position of the micro lens, F is the aperture value of the micro lens, and ? is the diffraction limit of the micro lens. This enables variation in the pupil intensity distribution of the pixel for focusing due to positional production tolerance of components to be suppressed.

Abstract: A method for forming an image sensor device is provided. First, a lens is provided and a first sacrificial element is formed thereon. An electromagnetic interference layer is formed on the lens and the first sacrificial element, and the first sacrificial element and electromagnetic interference layer thereon are removed to form an electromagnetic interference pattern having an opening exposing a selected portion of the lens. A second sacrificial element is formed in the opening to cover a center region of the selected portion of the lens. A peripheral region of the selected portion of the lens remains exposed. A light-shielding layer is formed on the electromagnetic interference pattern, second sacrificial element, and peripheral region of the selected portion of the lens. The second sacrificial element and light-shielding pattern are removed to expose the center region of the selected portion of the lens as a light transmitting region.

Abstract: Disclosed is a photodiode carrier which can equalize the frequency response characteristics of a plurality of mounted photodiodes. A photodiode carrier as disclosed includes a diode array connection region, first and second signal side electrodes connected to the diode array connection region, first and second bias side electrodes connected to the diode array connection region, and first and second condensers connected between the electrode disposed on the way of the first and the second bias side electrodes and the ground electrode, wherein the electrodes disposed on the way of the first and the second bias side electrodes are located in the about equal distance from the diode array connection region 7 as a start point.

Abstract: A semiconductor light-receiving element includes: a light-receiving portion that is provided on a semi-insulating substrate and has a mesa shape in which semiconductor layers are laminated; a lamination structure of insulating films that is provided on a part of a side face of the light-receiving portion and has a structure in which a first insulating film comprised of a silicon nitride film, a second insulating film comprised of a silicon oxynitride film and a third insulating film comprised of a silicon nitride film are laminated in contact with each other; and a resin film that is provided adjacent to the light-receiving portion, the resin film being sandwiched in or between any of the first insulating film, the second insulating film and the third insulating film.

Abstract: A semiconductor assemblage of a super-trench Schottky barrier diode (STSBD) made up of an n+ substrate, an n-epilayer, trenches etched into the n-epilayer that have a width and a distance from the n+ substrate, mesa regions between the adjacent trenches having a width, a metal layer on the front side of the chip that is a Schottky contact and serves as an anode electrode, and a metal layer on the back side of the chip that is an ohmic contact and serves as a cathode electrode, wherein multiple Schottky contacts having a width or distance and a distance between the Schottky contacts, and between the Schottky contact as anode electrode and the first Schottky contact, are located on the trench wall.

Abstract: A Schottky diode includes a device structure having a central portion and a plurality of fingers. Distal portions of the fingers overlie leakage current control (LCC) regions. An LCC region is relatively narrow and deep, terminating in proximity to a buried layer of like polarity. Under reverse bias, depletion regions forming in an active region lying between the buried layer and the LCC regions occupy the entire extent of the active region and thereby provide a carrier depleted wall. An analogous depletion region occurs in the active region residing between any pair of adjacent fingers. If the fingers include latitudinal oriented fingers and longitudinal oriented fingers, depletion region blockades in three different orthogonal orientations may occur. The formation of the LCC regions may include the use of a high dose, low energy phosphorous implant using an LCC implant mask and the isolation structures as an additional hard mask.

Abstract: An integrated circuit is provided. The integrated circuit includes a first contact disposed over a first source/drain region, a second contact disposed over a second source/drain region, a polysilicon disposed over a gate, the polysilicon interposed between the first contact and the second contact, a first polysilicon contact bridging the polysilicon and the first contact within an active region, and an output structure electrically coupled to the first polysilicon contact.

Abstract: The width of a heavily-doped sinker is substantially reduced by forming the heavily-doped sinker to lie in between a number of closely-spaced trench isolation structures, which have been formed in a semiconductor material. During drive-in, the closely-spaced trench isolation structures significantly limit the lateral diffusion.

Abstract: A device includes a dielectric layer, a passive device including a portion in the dielectric layer, and a plurality of voids in the dielectric layer and encircling the passive device.

Abstract: Atomic layer deposition (ALD) of TaAlC for capacitor integration is generally described. For example, a semiconductor structure includes a plurality of semiconductor devices disposed in or above a substrate. One or more dielectric layers are disposed above the plurality of semiconductor devices. A metal-insulator-metal (MIM) capacitor is disposed in at least one of the dielectric layers, the MIM capacitor includes an electrode having a conformal layer of TaAlC and the MIM capacitor is electrically coupled to one or more of the semiconductor devices. Other embodiments are also disclosed and claimed.

Abstract: Disclosed are methods for forming a thin film resistor and terminal bond pad simultaneously. A method includes simultaneously forming a terminal bond pad on a terminal wire and a thin film resistor on two other wires.

Abstract: Devices and methods are provided, wherein a diode string is provided in a well and the well is biased with an intermediate voltage between voltages applied to terminals of the diode string.