Abstract: A transistor semiconductor die includes a drift layer, a first dielectric layer, a first metallization layer, a second dielectric layer, a second metallization layer, a first plurality of electrodes, and a second plurality of electrodes. The first dielectric layer is over the drift layer. The first metallization layer is over the first dielectric layer such that at least a portion of the first metallization layer provides a first contact pad. The second dielectric layer is over the first metallization layer. The second metallization layer is over the second dielectric layer such that at least a portion of the second metallization layer provides a second contact pad and the second metallization layer at least partially overlaps the first metallization layer. The transistor semiconductor die is configured to selectively conduct current between the first contact pad and a third contact pad based on signals provided at the second contact pad.

Abstract: One example discloses a voltage select circuit, comprising: a first input configured to receive a first input voltage; a second input configured to receive a second input voltage; a first diode having a first polarity coupled to the first input; a second diode having a first polarity coupled to the second input; an output coupled to a second polarity of both the first and second diodes; a diode bypass circuit coupled to the first input and the output in parallel with the first diode, and coupled to the second input; and wherein the bypass circuit is configured to pass the first input voltage to the output if an absolute value of the second input voltage is less than a voltage drop of the second diode.

Abstract: Embodiments of a transistor control device for controlling a bi-directional power transistor are disclosed. In an embodiment, a transistor control device for controlling a bi-directional power transistor includes a resistor connectable to a body terminal of the bi-directional power transistor and a transistor body switch circuit connectable to the resistor, to a drain terminal of the bi-directional power transistor, and to a source terminal of the bi-directional power transistor. The transistor body switch circuit includes switch devices and alternating current (AC) capacitive voltage dividers connected to control terminals of the switch devices. The AC capacitive voltage dividers are configured to control the switch devices to switch a voltage of the body terminal of the bi-directional power transistor as a function of a voltage between the drain terminal of the bi-directional power transistor and the source terminal of the bi-directional power transistor.

Abstract: A gate amplification triac including in a semiconductor substrate of a first conductivity type a vertical triac and a lateral bipolar transistor having its emitter connected to the triac gate, its base connected to a control terminal, and its collector connected to a terminal intended to be connected to a first reference voltage, the main terminal of the triac on the side of the transistor being intended to be connected to a second reference voltage, the transistor being formed in a first well of the second conductivity type and the triac comprising on the transistor side a second well of the second conductivity type, the first and second wells being formed so that the substrate-well breakdown voltage of the transistor is greater than the substrate-well breakdown voltage of the triac by at least the difference between the first and second reference voltages.

Abstract: A protection clamp is provided between a first terminal and a second terminal, and includes a multi-gate high electron mobility transistor (HEMT), a current limiting circuit, and a forward trigger control circuit. The multi-gate HEMT includes a drain/source, a source/drain, a first depletion-mode (D-mode) gate, a second D-mode gate, and an enhancement-mode (E-mode) gate disposed between the first and second D-mode gates. The drain/source and the first D-mode gate are connected to the first terminal and the source/drain and the second D-mode gate are connected to the second terminal. The forward trigger control and the current limiting circuits are coupled between the E-mode gate and the first and second terminals, respectively. The forward trigger control circuit provides an activation voltage to the E-mode gate when a voltage of the first terminal exceeds a voltage of the second terminal by a forward trigger voltage.

Abstract: An electrostatic discharge protection clamp adapted to limit a voltage appearing across protected terminals of an integrated circuit to which the electrostatic discharge protection clamp is coupled is presented. The electrostatic discharge protection clamp includes a substrate, and a first electrostatic discharge protection device formed over the substrate.

Abstract: A bi-directional triode thyristor (TRIAC) device for high voltage electrostatic discharge (ESD) protection may include a substrate, an N+ doped buried layer, an N-type well region and two P-type well regions. The N+ doped buried layer may be disposed proximate to the substrate. The N-type well region may encompass the two P-type well regions such that a portion of the N-type well region is interposed between the two P-type well regions. The P-type well regions may be disposed proximate to the N+ doped buried layer and comprise one or more N+ doped plates and one or more P+ doped plates. The portion of the N-type well region that is interposed between the two P-type well regions may comprise one or more P-type portions, such as a P+ doped plate or a P-type implant.

Abstract: A high voltage isolation protection device for low voltage communication interface systems in mixed-signal high voltage electronic circuit is disclosed. According to one aspect, the protection device includes a semiconductor structure configured to provide isolation between low voltage terminals and protection from transient events. The protection device includes a thyristor having an anode, a cathode, and a gate, and a thyristor cathode-gate control region that is built into the protection device. The protection device is configured to provide multiple built-in path-up to power-high terminals and path-down to power-low terminals at different voltage levels. The protection device also includes independently built-in discharge paths to the common substrate that is connected to a different power-low voltage reference. The conduction paths may be built into a single structure with dual isolation regions.

Abstract: Device structures, fabrication methods, operating methods, and design structures for a silicon controlled rectifier. The method includes applying a mechanical stress to a region of a silicon controlled rectifier (SCR) at a level sufficient to modulate a trigger current of the SCR. The device and design structures include a SCR with an anode, a cathode, a first region, and a second region of opposite conductivity type to the first region. The first and second regions of the SCR are disposed in a current-carrying path between the anode and cathode of the SCR. A layer is positioned on a top surface of a semiconductor substrate relative to the first region and configured to cause a mechanical stress in the first region of the SCR at a level sufficient to modulate a trigger current of the SCR.

Abstract: A vertical transient voltage suppressor for protecting an electronic device is disclosed. The vertical transient voltage includes a conductivity type substrate having highly doping concentration; a first type lightly doped region is arranged on the conductivity type substrate, wherein the conductivity type substrate and the first type lightly doped region respectively belong to opposite types; a first type heavily doped region and a second type heavily doped region are arranged in the first type lightly doped region, wherein the first and second type heavily doped regions and the conductivity type substrate belong to same types; and a deep first type heavily doped region is arranged on the conductivity type substrate and neighbors the first type lightly doped region, wherein the deep first type heavily doped region and the first type lightly doped region respectively belong to opposite types, and wherein the deep first type heavily doped region is coupled to the first type heavily doped region.

Abstract: A vertical four-quadrant triac wherein the gate region, arranged on the side of a front surface, includes a U-shaped region of a first conductivity type, the base of the U lying against one side of the structure, the main front surface region of the second conductivity type extending in front of the gate region and being surrounded with portions of the main front surface region of the first conductivity type.

Abstract: A bi-directional switch circuit includes a pair of N-type MOS devices connected in series with a common source terminal, and a pair of P-type MOS devices connected in series with a common source terminal. The series connected N-type devices are connected in parallel with the series connected P-type devices in a configuration that includes a first input/output (I/O) point of the switch circuit being connected to a drain of a first one of the N-type devices and a drain of a first one of the P-type devices. The parallel configuration also includes a second I/O point of the switch circuit being connected to a drain of a second one of the N-type devices and a drain of a second one of the P-type devices.

Abstract: In one embodiment, a transistor is formed to have a first current flow path to selectively conduct current in both directions through the transistor and to have a second current flow path to selectively conduct current in one direction.

Abstract: In a DIAC-like device that includes an n+ and a p+ region connected to the high voltage node, and an n+ and a p+ region connected to the low voltage node, at least two MOS devices are formed between the n+ and p+ region connected to the high voltage node, and the n+ and p+ region connected to the low voltage node.

Abstract: A protection device includes a triac and triggering units. Each triggering unit is formed by a MOS transistor configured to operate at least temporarily in a hybrid operating mode and a field-effect diode. The field-effect diode has a controlled gate that is connected to the gate of the MOS transistor.

Abstract: A gate amplification triac including in a semiconductor substrate of a first conductivity type a vertical triac and a lateral bipolar transistor having its emitter connected to the triac gate, its base connected to a control terminal, and its collector connected to a terminal intended to be connected to a first reference voltage, the main terminal of the triac on the side of the transistor being intended to be connected to a second reference voltage, the transistor being formed in a first well of the second conductivity type and the triac comprising on the transistor side a second well of the second conductivity type, the first and second wells being formed so that the substrate-well breakdown voltage of the transistor is greater than the substrate-well breakdown voltage of the triac by at least the difference between the first and second reference voltages.

Abstract: A vertical bidirectional switch of the type having its control referenced to the rear surface, including on its rear surface a first main electrode and on its front surface a second main electrode and a gate electrode, this switch being controllable by a positive voltage between its gate and its first electrode, wherein the gate electrode is arranged on the front surface of a via crossing the chip in which the switch is formed.

Abstract: A voltage-controlled vertical bi-directional monolithic switch, referenced with respect to the rear surface of the switch, formed from a lightly-doped N-type semiconductor substrate, in which the control structure includes, on the front surface side, a first P-type well in which is formed an N-type region, and a second P-type well in which is formed a MOS transistor, the first P-type well and the gate of the MOS transistor being connected to a control terminal, said N-type region being connected to a main terminal of the MOS transistor, and the second main terminal of the MOS transistor being connected to the rear surface voltage of the switch.

Abstract: An electrostatic discharge (ESD) protection circuit, methods of fabricating an ESD protection circuit, methods of providing ESD protection, and design structures for an ESD protection circuit. An NFET may be formed in a p-well and a PFET may be formed in an n-well. A butted p-n junction formed between the p-well and n-well results in an NPNP structure that forms an SCR integrated with the NFET and PFET. The NFET, PFET and SCR are configured to collectively protect a pad, such as a power pad, from ESD events. During normal operation, the NFET, PFET, and SCR are biased by an RC-trigger circuit so that the ESD protection circuit is in a high impedance state. During an ESD event while the chip is unpowered, the RC-trigger circuit outputs trigger signals that cause the SCR, NFET, and PFET to enter into conductive states and cooperatively to shunt ESD currents away from the protected pad.

Abstract: The semiconductor device for protection from electrostatic discharges comprises several modules (MDi) for protection from electrostatic discharges comprising triggerable elements (TRi) coupled with triggering means, the said modules being connected between two terminals by the intermediary of a resistive network (R). A common semiconductor layer contacts all of the modules, each triggerable element (TRi) having at least one gate (GHi), and the triggering means comprise a single triggering circuit (TC) common to all of the triggerable elements and whose output is connected to the gates of all of the triggerable elements.

Abstract: An Adjustable Field Effect Rectifier uses aspects of MOSFET structure together with an adjustment pocket or region to result in a device that functions reliably and efficiently at high voltages without significant negative resistance, while also permitting fast recovery and operation at high frequency without large electromagnetic interference.

Abstract: The present invention improves the performance of a semiconductor device formed with a triac. A thyristor is formed between a back surface electrode and an electrode by p-type semiconductor regions, an n-type substrate region, p-type semiconductor regions and an n-type semiconductor region. A thyristor is formed therebetween by the p-type semiconductor regions, the n-type substrate region, the p-type semiconductor regions and an n-type semiconductor region. The two thyristors are opposite in the direction of currents flowing between the back surface electrode and the electrode. The p-type semiconductor region of a high impurity concentration is formed so as to be internally included in the p-type semiconductor region of a low impurity concentration. The p-type semiconductor region of a low impurity concentration is interposed between the p-type semiconductor region of a high impurity concentration and the n-type substrate region.

Abstract: An apparatus and method for high voltage transient electrical overstress protection are disclosed. In one embodiment, the apparatus includes an internal circuit electrically connected between a first node and a second node; and a protection circuit electrically connected between the first node and the second node. The protection circuit is configured to protect the internal circuit from transient electrical overstress events while maintaining a relatively high holding voltage upon activation.

Abstract: A vertical four-quadrant triac wherein the gate region, arranged on the side of a front surface, includes a U-shaped region of a first conductivity type, the base of the U lying against one side of the structure, the main front surface region of the second conductivity type extending in front of the gate region and being surrounded with portions of the main front surface region of the first conductivity type.

Abstract: A Dual-directional Silicon Controlled Rectifier (DSCR) includes a substrate of a first conductivity type, a buried layer formed on the substrate and of a second conductivity type, a first well and a second well formed on the buried layer and of the first conductivity type, a third well formed between the first well and the second well and of the second conductivity type, and a doped region formed between a first semiconductor region and a third semiconductor region and of the second conductivity type. The doped region includes a part of the third well. The DSCR may regulate a breakdown voltage of a junction thereof. Therefore, when an I/O voltage of an Integrated Circuit (IC) is much higher than a working voltage, a false action may not occur.

Abstract: In a DIAC-like device that includes an n+ and a p+ region connected to the high voltage node, and an n+ and a p+ region connected to the low voltage node, at least two MOS devices are formed between the n+ and p+ region connected to the high voltage node, and the n+ and p+ region connected to the low voltage node.

Abstract: According to one embodiment, in a reverse conducting-insulated gate bipolar transistor, the buffer layer is provided on the backside of the second base layer, has a higher impurity concentration in comparison with the second base layer. The first collector layer is in contact with a portion of the backside of the buffer layer, has a higher impurity concentration in comparison with the second base layer. The second collector layer is in contact with a portion of the backside of the buffer layer, is provided so as to surround the first collector layer, has a higher impurity concentration in comparison with the first base layer. The third collector layer is in contact with a portion of the backside of the buffer layer, is provided so as to surround the second collector layer, has a higher impurity concentration in comparison with the second collector layer.

Abstract: A bidirectional silicon-controlled rectifier, wherein the conventional field oxide layer, which separates an anode structure from a cathode structure, is replaced by a field oxide layer having floating gates, a virtual gate or a virtual active region. Thus, the present invention can reduce or escape from the bird's beak effect of a field oxide layer, which results in crystalline defects, a concentrated current and a higher magnetic field and then causes abnormal operation of a rectifier. Thereby, the present invention can also reduce signal loss.

Abstract: A voltage-controlled vertical bi-directional monolithic switch, referenced with respect to the rear surface of the switch, formed from a lightly-doped N-type semiconductor substrate, in which the control structure includes, on the front surface side, a first P-type well in which is formed an N-type region, and a second P-type well in which is formed a MOS transistor, the first P-type well and the gate of the MOS transistor being connected to a control terminal, said N-type region being connected to a main terminal of the MOS transistor, and the second main terminal of the MOS transistor being connected to the rear surface voltage of the switch.

Abstract: A bidirectional switch controllable by a voltage between its gate and rear electrode and including an N-type semiconductor substrate surrounded with a P-type well; on the front surface side, a P-type well in which is formed a first N-type region; on the rear surface side, a P-type layer in which is formed a second N-type region. The well is doped to less than 1016 at./cm3, the exposed surfaces of this well being heavily P-type doped. At least a third P-type region, of same doping level as the well, is formed on the front surface side in the substrate, and contains at least a fourth N-type region of a doping level lower than 1017 at./cm3, on which is formed a Schottky contact.

Abstract: Symmetrical/asymmetrical bidirectional S-shaped I-V characteristics with trigger voltages ranging from 10 V to over 40 V and relatively high holding current are obtained for advanced sub-micron silicided CMOS (Complementary Metal Oxide Semiconductor)/BiCMOS (Bipolar CMOS) technologies by custom implementation of P1-N2-P2-N1//N1-P3-N3-P1 lateral structures with embedded ballast resistance 58, 58A, 56, 56A and periphery guard-ring isolation 88-86. The bidirectional protection devices render a high level of electrostatic discharge (ESD) immunity for advanced CMOS/BiCMOS processes with no latchup problems. Novel design-adapted multifinger 354/interdigitated 336 layout schemes of the ESD protection cells allow for scaling-up the ESD performance of the protection structure and custom integration, while the I-V characteristics 480 are adjustable to the operating conditions of the integrated circuit (IC).

Abstract: Process variation-tolerant diodes and diode-connected thin film transistors (TFTs), printed or patterned structures (e.g., circuitry) containing such diodes and TFTs, methods of making the same, and applications of the same for identification tags and sensors are disclosed. A patterned structure comprising a complementary pair of diodes or diode-connected TFTs in series can stabilize the threshold voltage (Vt) of a diode manufactured using printing or laser writing techniques. The present invention advantageously utilizes the separation between the Vt of an NMOS TFT (Vtn) and the Vt of a PMOS TFT (Vtp) to establish and/or improve stability of a forward voltage drop across a printed or laser-written diode. Further applications of the present invention relate to reference voltage generators, voltage clamp circuits, methods of controlling voltages on related or differential signal transmission lines, and RFID and EAS tags and sensors.

Abstract: The present invention improves the performance of a semiconductor device formed with a triac. A thyristor is formed between a back surface electrode and an electrode by p-type semiconductor regions, an n-type substrate region, p-type semiconductor regions and an n-type semiconductor region. A thyristor is formed therebetween by the p-type semiconductor regions, the n-type substrate region, the p-type semiconductor regions and an n-type semiconductor region. The two thyristors are opposite in the direction of currents flowing between the back surface electrode and the electrode. The p-type semiconductor region of a high impurity concentration is formed so as to be internally included in the p-type semiconductor region of a low impurity concentration. The p-type semiconductor region of a low impurity concentration is interposed between the p-type semiconductor region of a high impurity concentration and the n-type substrate region.

Abstract: A high-voltage vertical power component including a lightly-doped semiconductor substrate of a first conductivity type and, on the side of an upper surface, an upper semiconductor layer of the second conductivity type which does not extend all the way to the component periphery, wherein the component periphery includes, on the lower surface side, a ring-shaped diffused region of the second conductivity type extending across from one third to half of the component thickness; and on the upper surface side, an insulated ring-shaped groove crossing the substrate to penetrate into an upper portion of ring-shaped region.

Abstract: A bidirectional transient voltage suppression device is disclosed. The bi-directional transient voltage suppression device comprises a semiconductor die. The semiconductor die has a multi-layer structure comprising a semiconductor substrate of a first conductivity type, a buried layer of a second conductivity type, an epitaxial layer, and five diffused regions. The buried layer and the semiconductor substrate form a first semiconductor junction. The first diffused region of the second conductivity type and the semiconductor substrate form a second semiconductor junction. The fourth diffused region of the first conductivity type and the third diffused region of the second conductivity type form a third semiconductor junction. The fifth diffused region of the first conductivity type and the second diffused region of the second conductivity type form a fourth semiconductor junction.

Abstract: In one embodiment, a transistor is formed to have a first current flow path to selectively conduct current in both directions through the transistor and to have a second current flow path to selectively conduct current in one direction.

Abstract: An integrated low leakage Schottky diode has a Schottky barrier junction proximate one side of an MOS gate with one end of a drift region on an opposite side of the gate. Below the Schottky metal and the gate oxide is a RESURF structure of an N? layer over a P? layer which also forms the drift region that ends at the diode's cathode in one embodiment of the present invention. The N? and P? layers have an upward concave shape under the gate. The gate electrode and the Schottky metal are connected to the diode's anode. A P? layer lies between the RESURF structure and an NISO region which has an electrical connection to the anode. A P+ layer under the Schottky metal is in contact with the P? layer through a P well.

Abstract: A semiconductor substrate has a second conductivity type cathode layer formed thereon. The cathode layer has a first conductivity type base layer formed thereon. A first anode region of the second conductivity type is formed in the surface of the base layer. A second anode region of the first conductivity type is formed in the first anode region. A first semiconductor region of the first conductivity type is formed in contact with the semiconductor substrate. A second semiconductor region of the second conductivity type is formed adjacent to the first semiconductor region and in contact with the cathode layer. An intermediate electrode is formed on the surfaces of the first semiconductor region and the contact region.

Abstract: A bidirectional switch includes a plurality of unit cells 11 including a first ohmic electrode 15, a first gate electrode 17, a second gate electrode 18, and a second ohmic electrode 16. The first gate electrodes 15 are electrically connected via a first interconnection 31 to a first gate electrode pad 43. The second gate electrodes 18 are electrically connected via a second interconnection 32 to a second gate electrode pad 44. A unit cell 11 including a first gate electrode 17 having the shortest interconnect distance from the first gate electrode pad 43 includes a second gate electrode 18 having the shortest interconnect distance from the second gate electrode pad 44.

Abstract: An integrated low leakage Schottky diode has a Schottky barrier junction proximate one side of an MOS gate with one end of a drift region on an opposite side of the gate. Below the Schottky metal and the gate oxide is a RESURF structure of an N? layer over a P? layer which also forms the drift region that ends at the diode's cathode in one embodiment of the present invention. The N? and P? layers have an upward concave shape under the gate. The gate electrode and the Schottky metal are connected to the diode's anode. A P? layer lies between the RESURF structure and an NISO region which has an electrical connection to the anode. A P+ layer under the Schottky metal is in contact with the P? layer through a P well.

Abstract: A bidirectional transient voltage suppression device is disclosed. The bi-directional transient voltage suppression device comprises a semiconductor die. The semiconductor die has a multi-layer structure comprising a semiconductor substrate of a first conductivity type, a buried layer of a second conductivity type, an epitaxial layer, and five diffused regions. The buried layer and the semiconductor substrate form a first semiconductor junction. The first diffused region of the second conductivity type and the semiconductor substrate form a second semiconductor junction. The fourth diffused region of the first conductivity type and the third diffused region of the second conductivity type form a third semiconductor junction. The fifth diffused region of the first conductivity type and the second diffused region of the second conductivity type form a fourth semiconductor junction.

Abstract: A bidirectional switch includes a first switch and a second switch. The switch includes a well region of a first-conductivity-type formed on a semiconductor substrate, and serving as drains of the first switch and the second switch, a gate electrode of the first switch provided in a first trench formed in the well region through a first gate insulating film, a gate electrode of the second switch formed in a second trench formed in the well region so as to be spaced apart from the first trench with a second gate insulating film, a source region of the first switch formed on a side wall of the first trench, and on a surface of the well region via a first channel region of a second-conductivity-type, and a source region of the second switch formed on a side wall of the second trench, and on a surface of the well region via a second channel region of the second-conductivity-type. The well region is formed in a region between the first trench and the second trench.

Abstract: High voltage silicon carbide (SiC) devices, for example, thyristors, are provided. A first SiC layer having a first conductivity type is provided on a first surface of a voltage blocking SiC substrate having a second conductivity type. A first region of SiC is provided on the first SiC layer and has the second conductivity type. A second region of SiC is provided in the first SiC layer, has the first conductivity type and is adjacent to the first region of SiC. A second SiC layer having the first conductivity type is provided on a second surface of the voltage blocking SiC substrate. A third region of SiC is provided on the second SiC layer and has the second conductivity type. A fourth region of SiC is provided in the second SiC layer, has the first conductivity type and is adjacent to the third region of SiC. First and second contacts are provided on the first and third regions of SiC, respectively. Related methods of fabricating high voltage SiC devices are also provided.

Abstract: An integrated low leakage Schottky diode has a Schottky barrier junction proximate one side of an MOS gate with one end of a drift region on an opposite side of the gate. Below the Schottky metal and the gate oxide is a RESURF structure of an N? layer over a P? layer which also forms the drift region that ends at the diode's cathode in one embodiment of the present invention. The N? and P? layers have an upward concave shape under the gate. The gate electrode and the Schottky metal are connected to the diode's anode. A P? layer lies between the RESURF structure and an NISO region which has an electrical connection to the anode. A P+ layer under the Schottky metal is in contact with the P? layer through a P well.

Abstract: The present invention discloses a bidirectional PNPN silicon-controlled rectifier comprising: a p-type substrate; a N-type epitaxial layer; a P-type well and two N-type wells all formed inside the N-type epitaxial layer with the two N-type wells respectively arranged at two sides of the P-type well; a first semiconductor area, a second semiconductor area and a third semiconductor area all formed inside the P-type well and all coupled to an anode, wherein the second semiconductor area and the third semiconductor area are respectively arranged at two sides of the first semiconductor area, and wherein the first semiconductor area is of first conduction type, and the second semiconductor area and the third semiconductor area are of second conduction type; and two P-type doped areas respectively formed inside the N-type wells, wherein each P-type doped area has a fourth semiconductor area neighboring the P-type well and a fifth semiconductor area, and wherein both the fourth semiconductor area and the fifth semico

Abstract: In one embodiment, a transistor is formed to have a first current flow path to selectively conduct current in both directions through the transistor and to have a second current flow path to selectively conduct current in one direction.

Abstract: A silicon controlled rectifier structure of polygonal layouts is provided. The polygonal first conductive type doped region is located in the middle of the polygonal second conductive type well. The first conductive type well shaped as a polygonal ring surrounds the second conductive type well and the second conductive type doped region is located within the first conductive type well and shaped as a polygonal ring concentric to the first conductive type well.

Abstract: In one embodiment, a transistor is formed to have a first current flow path to selectively conduct current in both directions through the transistor and to have a second current flow path to selectively conduct current in one direction.

Abstract: The present invention discloses an asymmetric bidirectional silicon-controlled rectifier, which comprises: a second conduction type substrate; a first conduction type undoped epitaxial layer formed on the substrate; a first well and a second well both formed inside the undoped epitaxial layer and separated by a portion of the undoped epitaxial layer; a first buried layer formed in a junction between the first well and the substrate; a second buried layer formed in a junction between the second well and the substrate; a first and a second semiconductor area with opposite conduction type both formed inside the first well; a third and a fourth semiconductor area with opposite conduction type both formed inside the second well, wherein the first and second semiconductor areas are connected to the anode of the silicon-controlled rectifier, and the third and fourth semiconductor areas are connected to the cathode of the silicon-controlled rectifier.

Abstract: The present invention discloses a symmetric bidirectional silicon-controlled rectifier, which comprises: a substrate; a buried layer formed on the substrate; a first well, a middle region and a second well, which are sequentially formed on the buried layer side-by-side; a first semiconductor area and a second semiconductor area both formed inside the first well; a third semiconductor area formed in a junction between the first well and the middle region, wherein a first gate is formed over a region between the second and third semiconductor areas; a fourth semiconductor area and a fifth semiconductor area both formed inside the second well; a sixth semiconductor area formed in a junction between the second well and the middle region, wherein a second gate is formed over a region between the fifth and sixth semiconductor areas.