An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily used as an electronic switch which, as it was developed, came to combine high efficiency and fast switching. It consists of four alternating layers (P-N-P-N) that are controlled by a metal-oxide-semiconductor (MOS) gate structure without regenerative action. Although the structure of the IGBT is topologically the same as a thyristor with a 'MOS' gate (MOS gate thyristor), the thyristor action is completely suppressed and only the transistor action is permitted in the entire device operation range. It is used in switching power supplies in high power applications: variable-frequency drives (VFDs), electric cars, trains, variable speed refrigerators, lamp ballasts, and air-conditioners.
A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics. Such a device is also called a power device or, when used in an integrated circuit, a power IC.
A metal gate, in the context of a lateral metal-oxide-semiconductor (MOS) stack, is just that—the gate material is made from a metal.
A thyristor is a solid-state semiconductor device with four layers of alternating P- and N-type materials. It acts exclusively as a bistable switch, conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reversed biased, or until the voltage is removed. There are two designs, differing in what triggers the conducting state. In a three-lead thyristor, a small current on its Gate lead controls the larger current of the Anode to Cathode path. In a two-lead thyristor, conduction begins when the potential difference between the Anode and Cathode themselves is sufficiently large.
Since it is designed to turn on and off rapidly, the IGBT can synthesize complex waveforms with pulse-width modulation and low-pass filters, so it is also used in switching amplifiers in sound systems and industrial control systems. In switching applications modern devices feature pulse repetition rates well into the ultrasonic range—frequencies which are at least ten times the highest audio frequency handled by the device when used as an analog audio amplifier.
Pulse width modulation (PWM), or pulse-duration modulation (PDM), is a method of reducing the average power delivered by an electrical signal, by effectively chopping it up into discrete parts. The average value of voltage fed to the load is controlled by turning the switch between supply and load on and off at a fast rate. The longer the switch is on compared to the off periods, the higher the total power supplied to the load. Along with MPPT maximum power point tracking, it is one of the primary methods of reducing the output of solar panels to that which can be utilized by a battery. PWM is particularly suited for running inertial loads such as motors, which are not as easily affected by this discrete switching, because they have inertia to react slow. The PWM switching frequency has to be high enough not to affect the load, which is to say that the resultant waveform perceived by the load must be as smooth as possible.
A low-pass filter (LPF) is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filter design. The filter is sometimes called a high-cut filter, or treble-cut filter in audio applications. A low-pass filter is the complement of a high-pass filter.
A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large Industrial control systems which are used for controlling processes or machines.
|IGBT comparison table|
|Device characteristic||Power bipolar||Power MOSFET||IGBT|
|Voltage rating||High <1kV||High <1kV||Very high >1kV|
|Current rating||High <500A||High >500A||High >500A|
|Input drive||Current ratio hFE|
|Switching speed||Slow (µs)||Fast (ns)||Medium|
An IGBT cell is constructed similarly to a n-channel vertical-construction power MOSFET, except the n+ drain is replaced with a p+ collector layer, thus forming a vertical PNP bipolar junction transistor. This additional p+ region creates a cascade connection of a PNP bipolar junction transistor with the surface n-channel MOSFET.
A power MOSFET is a specific type of MOSFET designed to handle significant power levels.
A bipolar junction transistor is a type of transistor that uses both electrons and holes as charge carriers.
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of field-effect transistor that is fabricated by the controlled oxidation of a semiconductor, typically silicon. It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. The MOSFET is the basic building block of modern electronics. Since its invention by Mohamed M. Atalla and Dawon Kahng at Bell Labs in November 1959, the MOSFET has become the most widely manufactured device in history, with an estimated total of 13 sextillion (1.3 × 1022) MOS transistors manufactured between 1960 and 2018.
The basic IGBT mode of operation, where a pnp transistor is driven by a MOSFET (metal-oxide-semiconductor field-effect transistor), was first proposed by K. Yamagami and Y. Akagiri of Mitsubishi Electric in the Japanese patent S47-21739, which was filed in 1968.Following the commercialization of power MOSFETs in the 1970s, B. Jayant Baliga submitted a patent disclosure at General Electric (GE) in 1977 describing a power semiconductor device with the IGBT mode of operation, including the MOS gating of thyristors, a four-layer VMOS (V-groove MOSFET) structure, and the use of MOS-gated structures to control a four-layer semiconductor device. He began fabricating the IGBT device with the assistance of Margaret Lazeri at GE in 1978 and successfully completed the project in 1979. The results of the experiments were reported in 1979. The device structure was referred to as a "V-groove MOSFET device with the drain region replaced by a p-type anode region" in this paper and subsequently as "the insulated-gate rectifier" (IGR), the insulated-gate transistor (IGT), the conductivity-modulated field-effect transistor (COMFET) and "bipolar-mode MOSFET".
Mitsubishi Electric Corporation is a Japanese multinational electronics and electrical equipment manufacturing company headquartered in Tokyo, Japan. It is one of the core companies of Mitsubishi.
A patent is a form of intellectual property that gives its owner the legal right to exclude others from making, using, selling, and importing an invention for a limited period of years, in exchange for publishing an enabling public disclosure of the invention. In most countries patent rights fall under civil law and the patent holder needs to sue someone infringing the patent in order to enforce his or her rights. In some industries patents are an essential form of competitive advantage; in others they are irrelevant.
Bantval Jayant Baliga is an Indian electrical engineer best known for his work in power semiconductor devices, and particularly the invention of the insulated gate bipolar transistor (IGBT).
An MOS-controlled triac device was reported by B. W. Scharf and J. D. Plummer with their lateral four-layer device (SCR) in 1978. [ citation needed ]Plummer filed a patent application for this mode of operation in the four-layer device (SCR) in 1978. USP No. 4199774 was issued in 1980, and B1 Re33209 was reissued in 1996. The IGBT mode of operation in the four-layer device (SCR) switched to thyristor operation if the collector current exceeded the latch-up current, which is known as "holding current" in the well known theory of the thyristor.
The development of IGBT was characterized by the efforts to completely suppress the thyristor operation or the latch-up in the four-layer device because the latch-up caused the fatal device failure. The technology of IGBT had, thus, been established when the complete suppression of the latch-up of the parasitic thyristor was achieved as described in the following.
Hans W. Becke and Carl F. Wheatley developed a similar device, for which they filed a patent application in 1980, and which they referred to as "power MOSFET with an anode region".The patent claimed that "no thyristor action occurs under any device operating conditions". The device had an overall similar structure to Baliga's earlier IGBT device reported in 1979, as well as a similar title.
A. Nakagawa et. al. invented the device design concept of non-latch-up IGBTs in 1984.The invention is characterized by the device design setting the device saturation current below the latch-up current, which triggers the parasitic thyristor. This invention realized complete suppression of the parasitic thyristor action, for the first time, because the maximal collector current was limited by the saturation current and never exceeded the latch-up current. After the invention of the device design concept of non-latch-up IGBTs, IGBTs evolved rapidly, and the design of non-latch-up IGBTs became a de facto standard and the patent of non-latch-up IGBTs became the basic IGBT patent of actual devices.
In the early development stage of IGBT, all the researchers tried to increase the latch-up current itself in order to suppress the latch-up of the parasitic thyristor. However, all these efforts failed because IGBT could conduct enormously large current. Successful suppression of the latch-up was made possible by limiting the maximal collector current, which IGBT could conduct, below the latch-up current by controlling/reducing the saturation current of the inherent MOSFET. This was the concept of non-latch-up IGBT. “Becke’s device” was made possible by the non-latch-up IGBT.
The IGBT is characterized by its ability to simultaneously handle a high voltage and a large current. The product of the voltage and the current density that the IGBT can handle reached more than 5×105 W/cm2, which far exceeded the value, 2×105 W/cm2, of existing power devices such as bipolar transistors and power MOSFETs. This is a consequence of the large safe operating area of the IGBT. The IGBT is the most rugged and the strongest power device that ever developed, thus, providing users with easy use of the device and displaced bipolar transistors and even GTOs. This excellent feature of the IGBT had suddenly emerged when the non-latch-up IGBT was established in 1984 by solving the problem of so-called “latch-up,” which is the main cause of device destruction or device failure. Before that, the developed devices were very weak and were easy to be destroyed because of “latch-up.”
IGBT is defined as a transistor. Thus, the device, which operates in IGBT-mode and switches to thyristor operation in higher current, should not be called as IGBT. Thus, the invention of Plummer, US Pat. No. 419977, RE33209, which is cited above, is not IGBT. MOS gate thyristor is not IGBT, either. Even "IGT" is not actual IGBT, because the switching safe operation area is narrow and limited by latch-up and because the allowable maximal collector current could not be turned-off due to thyristor action of "latch-up." The detailed discussions will be necessary.
Practical devices capable of operating over an extended current range were first reported by B. Jayant Baliga et al. in 1982.The first experimental demonstration of a practical discrete vertical IGBT device was reported by Baliga at the IEEE International Electron Devices Meeting (IEDM) that year. General Electric commercialized Baliga's IBGT device the same year. Baliga was inducted into the National Inventors Hall of Fame for the invention of the IGBT.
A similar paper was also submitted by J. P. Russel et al. to IEEE Electron Device Letter in 1982.The applications for the device were initially regarded by the power electronics community to be severely restricted by its slow switching speed and latch-up of the parasitic thyristor structure inherent within the device. However, it was demonstrated by Baliga and also by A. M. Goodman et al. in 1983 that the switching speed could be adjusted over a broad range by using electron irradiation. This was followed by demonstration of operation of the device at elevated temperatures by Baliga in 1985. Successful efforts to suppress the latch-up of the parasitic thyristor and the scaling of the voltage rating of the devices at GE allowed the introduction of commercial devices in 1983, which could be utilized for a wide variety of applications. The electrical characteristics of GE's device, IGT D94FQ/FR4, were reported in detail by Marvin W. Smith in the proceedings of PCI April 1984. Marvin W. Smith showed in Fig.12 of the proceedings that turn-off above 10 amperes for gate resistance of 5kOhm and above 5 amperes for gate resistance of 1kOhm was limited by switching safe operating area although IGT D94FQ/FR4 was able to conduct 40 amperes of collector current. Marvin W. Smith also stated that the switching safe operating area was limited by the latch-up of the parasitic thyristor.
Complete suppression of the parasitic thyristor action and the resultant non-latch-up IGBT operation for the entire device operation range was achieved by A. Nakagawa et al. in 1984.The non-latch-up design concept was filed for US patents. To test the lack of latch-up, the prototype 1200 V IGBTs were directly connected without any loads across a 600 V constant voltage source and were switched on for 25 microseconds. The entire 600 V was dropped across the device and a large short circuit current flowed. The devices successfully withstood this severe condition. This was the first demonstration of so-called "short-circuit-withstanding-capability" in IGBTs. Non-latch-up IGBT operation was ensured, for the first time, for the entire device operation range. In this sense, the non-latch-up IGBT proposed by Hans W. Becke and Carl F. Wheatley was realized by A. Nakagawa et al. in 1984. Products of non-latch-up IGBTs were first commercialized by Toshiba in 1985. This was the real birth of the present IGBT.
Once the non-latch-up capability was achieved in IGBTs, it was found that IGBTs exhibited very rugged and a very large safe operating area. It was demonstrated that the product of the operating current density and the collector voltage exceeded the theoretical limit of bipolar transistors, 2×105 W/cm2, and reached 5×105 W/cm2.
The insulating material is typically made of solid polymers which have issues with degradation. There are developments that use an ion gel to improve manufacturing and reduce the voltage required.
The first-generation IGBTs of the 1980s and early 1990s were prone to failure through effects such as latchup (in which the device will not turn off as long as current is flowing) and secondary breakdown (in which a localized hotspot in the device goes into thermal runaway and burns the device out at high currents). Second-generation devices were much improved. The current third-generation IGBTs are even better, with speed rivaling power MOSFETs, and excellent ruggedness and tolerance of overloads.Extremely high pulse ratings of second and third-generation devices also make them useful for generating large power pulses in areas including particle and plasma physics, where they are starting to supersede older devices such as thyratrons and triggered spark gaps. High pulse ratings and low prices on the surplus market also make them attractive to the high-voltage hobbyists for controlling large amounts of power to drive devices such as solid-state Tesla coils and coilguns.
The device proposed by J. D. Plummer in 1978 (US Patent Re.33209) is the same structure as a thyristor with a MOS gate. Plummer discovered and proposed that the device can be used as a transistor although the device operates as a thyristor in higher current density level. J. D. Plummer reported this fact in his technical paper: "A MOS-Controlled Triac Devices" B.W. Scharf and J.D. Plummer, 1978 IEEE International Solid-State Circuits Conference, SESSION XVI FAM 16.6. [ citation needed ] However, the Becke's patent (US Patent 4364073) did not disclose any measures to realize actual devices.The device proposed by J. D. Plummer is referred here as “Plummer’s device.” On the other hand, Hans W. Becke proposed, in 1980, another device in which the thyristor action is completely eliminated under any device operating conditions although the basic device structure is the same as that proposed by J. D. Plummer. The device developed by Hans W. Becke is referred here as “Becke’s device” and is described in US Patent 4364073. The difference between “Plummer’s device” and “Becke’s device” is that “Plummer’s device” has the mode of thyristor action in its operation range and “Becke’s device” never has the mode of thyristor action in its entire operation range. This is a critical point, because the thyristor action is the same as so-called “latch-up.” “Latch-up” is the main cause of fatal device failure. Thus, theoretically, “Plummer’s device” never realizes a rugged or strong power device which has a large safe operating area. The large safe operating area can be achieved only after “latch-up” is completely suppressed and eliminated in the entire device operation range.
Despite Becke’s patent describing a similar structure to Baliga's earlier IGBT device,several IGBT manufacturers paid the license fee of Becke’s patent. Toshiba commercialized “non-latch-up IGBT” in 1985. Stanford University insisted in 1991 that Toshiba’s device infringed US Patent RE33209 of “Plummer’s device.” Toshiba answered that “non-latch-up IGBTs” never latched up in the entire device operation range and thus did not infringe US Patent RE33209 of “Plummer’s patent.” Stanford University never responded after Nov. 1992. Toshiba purchased the license of “Becke’s patent” but never paid any license fee for “Plummer’s device.” Other IGBT manufacturers also paid the license fee for Becke’s patent.
The IGBT combines the simple gate-drive characteristics of MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors. The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device. The IGBT is used in medium- to high-power applications like switched-mode power supplies, traction motor control and induction heating. Large IGBT modules typically consist of many devices in parallel and can have very high current-handling capabilities in the order of hundreds of amperes with blocking voltages of 6500 V . These IGBTs can control loads of hundreds of kilowatts.
An IGBT features a significantly lower forward voltage drop compared to a conventional MOSFET in higher blocking voltage rated devices, although MOSFETS exhibit much lower forward voltage at lower current densities due to the absence of a diode Vf in the IGBT's output BJT. As the blocking voltage rating of both MOSFET and IGBT devices increases, the depth of the n- drift region must increase and the doping must decrease, resulting in roughly square relationship decrease in forward conduction versus blocking voltage capability of the device. By injecting minority carriers (holes) from the collector p+ region into the n- drift region during forward conduction, the resistance of the n- drift region is considerably reduced. However, this resultant reduction in on-state forward voltage comes with several penalties:
In general, high voltage, high current and low switching frequencies favor the IGBT while low voltage, medium current and high switching frequencies are the domain of the MOSFET.
Circuits with IGBTs can be developed and modeled with various circuit simulating computer programs such as SPICE, Saber, and other programs. To simulate an IGBT circuit, the device (and other devices in the circuit) must have a model which predicts or simulates the device's response to various voltages and currents on their electrical terminals. For more precise simulations the effect of temperature on various parts of the IGBT may be included with the simulation. Two common methods of modeling are available: device physics-based model, equivalent circuits or macromodels. SPICE simulates IGBTs using a macromodel that combines an ensemble of components like FETs and BJTs in a Darlington configuration.[ citation needed ] An alternative physics-based model is the Hefner model, introduced by Allen Hefner of the National Institute of Standards and Technology. Hefner's model is fairly complex that has shown very good results. Hefner's model is described in a 1988 paper and was later extended to a thermo-electrical model which include the IGBT's response to internal heating. This model has been added to a version of the Saber simulation software.
The failure mechanisms of IGBTs includes overstress (O) and wearout(wo) separately.
The wearout failures mainly include bias temperature instability (BTI), hot carrier injection (HCI), time-dependent dielectric breakdown (TDDB), electromigration (ECM), solder fatigue, material reconstruction, corrosion. The overstress failure mainly include electrostatic discharge (ESD), latch-up, avalanche, secondary breakdown, wire-bond liftoff and burnout.
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
N-type metal-oxide-semiconductor logic uses n-type MOSFETs to implement logic gates and other digital circuits. These nMOS transistors operate by creating an inversion layer in a p-type transistor body. This inversion layer, called the n-channel, can conduct electrons between n-type "source" and "drain" terminals. The n-channel is created by applying voltage to the third terminal, called the gate. Like other MOSFETs, nMOS transistors have four modes of operation: cut-off, triode, saturation, and velocity saturation.
Complementary metal–oxide–semiconductor (CMOS), also known as complementary-symmetry metal–oxide–semiconductor (COS-MOS), is a type of MOSFET fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuits (ICs), including microprocessors, microcontrollers, memory chips, and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors, data converters, RF circuits, and highly integrated transceivers for many types of communication.
For power semiconductor devices, the safe operating area (SOA) is defined as the voltage and current conditions over which the device can be expected to operate without self-damage.
MOS composite static induction thyristor is a combination of a MOS transistor connected in cascode relation to the SI-thyristor.
In integrated circuits, depletion-load NMOS is a form of digital logic family that uses only a single power supply voltage, unlike earlier nMOS logic families that needed more than one different power supply voltage. Although manufacturing these integrated circuits required additional processing steps, improved switching speed and the elimination of the extra power supply made this logic family the preferred choice for many microprocessors and other logic elements.
A VMOS transistor is a type of MOSFET. VMOS is also used for describing the V-groove shape vertically cut into the substrate material. VMOS is an acronym for "vertical metal oxide semiconductor", or "V-groove MOS".
The floating-gate MOSFET (FGMOS) is a type of MOSFET where the gate is electrically isolated, creating a floating node in DC, and a number of secondary gates or inputs are deposited above the floating gate (FG) and are electrically isolated from it. These inputs are only capacitively connected to the FG. Since the FG is completely surrounded by highly resistive material, the charge contained in it remains unchanged for long periods of time. Usually Fowler-Nordheim tunneling and hot-carrier injection mechanisms are used to modify the amount of charge stored in the FG.
In the field of electronics, a bootstrap circuit is one where part of the output of an amplifier stage is applied to the input, so as to alter the input impedance of the amplifier. When applied deliberately, the intention is usually to increase rather than decrease the impedance. Generally, any technique where part of the output of a system is used at startup is described as bootstrapping.
In electronics, a self-aligned gate is a transistor manufacturing feature whereby a refractory gate electrode region of a MOSFET is used as a mask for the doping of the source and drain regions. This technique ensures that the gate will slightly overlap the edges of the source and drain.
A gate turn-off thyristor (GTO) is a special type of thyristor, which is a high-power semiconductor device. It was invented by General Electric. GTOs, as opposed to normal thyristors, are fully controllable switches which can be turned on and off by their third lead, the gate lead.
An MOS-controlled thyristor (MCT) is a voltage-controlled fully controllable thyristor. It was invented by V.A.K. Temple. MCTs are similar in operation to GTO thyristors, but have voltage controlled insulated gates. They have two MOSFETs of opposite conductivity types in their equivalent circuits. One is responsible for turn-on and the other for turn-off. A thyristor with only one MOSFET in its equivalent circuit, which can only be turned on, is called an MOS-gated thyristor.
A transistor is a semiconductor device with at least three terminals for connection to an electric circuit. The vacuum-tube triode, also called a (thermionic) valve, was the transistor's precursor, introduced in 1907. The principle of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925.
A gate driver is a power amplifier that accepts a low-power input from a controller IC and produces a high-current drive input for the gate of a high-power transistor such as an IGBT or power MOSFET. Gate drivers can be provided either on-chip or as a discrete module. In essence, a gate driver consists of a level shifter in combination with an amplifier. A gate driver IC serves as the interface between control signals and power switches. An integrated gate-driver solution reduces design complexity, development time, bill of materials (BOM), and board space while improving reliability over discretely-implemented gate-drive solutions.
The field-effect transistor (FET) is an electronic device which uses an electric field to control the flow of current. FETs are devices with three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source.
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