Lateral Insulated Gate Bipolar Transistor Research Articles

Analysis and characterization of the segmented anode LIGBT

A LIGBT (lateral insulated gate bipolar transistor) structure, called the segmented-anode LIGBT, is presented and analyzed. The anode structure responsible for the injection of minority carriers for conductivity modulation is implemented using segments of p/sup +/ and n/sup +/ diffusion along the device width. This minimizes the forward bias of the p/sup +/ injector during device turn-off, resulting in higher switching speed compared to the shorted-anode LIGBT. Since the n/sup +/ region required for electron extraction is implemented along the device width and consumes only a small amount of area, a reduction in device size is also achieved. The switching speed and reduced device size result in better tradeoff between on-resistance and turn-off time compared with other LIGBTs. Two-dimensional numerical simulations are carried out to demonstrate the operation and characteristics of the structure, and the experimental inductive and resistive switching characteristics of the structure are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of new lateral insulated gate bipolar transistor structures for power applications

This paper aims to describe the physical behaviour of different lateral insulated gate bipolar transistor (LIGBT) structures. It reviews a variety of LIGBTs and a new modification of the basic LIGBT structure consisting of a buried layer, an auxiliary cathode and a highly doped sinker between the MOS channel and the auxiliary cathode. Results from two-dimensional numerical simulations show an improvement in the device current in comparison with other LIGBT structures.

CMOS compatible shorted anode auxiliary cathode lateral insulated gate bipolar transistors

The performance of CMOS-compatible, shorted-anode, auxiliary-cathode lateral insulated gate bipolar transistors (SA-ACLIGBT), fabricated using a standard 2.5- mu m high-voltage integrated circuit process, is investigated. Typical on-state current densities of more than 240 A/cm/sup 2/ at a gate voltage of 10 V and a forward voltage of 5 V have been obtained. These devices show a latchup-free, current saturation behavior when compared to equivalent shorted-anode LIGBTs. Measured high-voltage turnoff characteristics of the SA-ACLIGBT are superior to those of the conventional SA-LIGBT. These results confirm that by including an auxiliary cathode and extending a p/sup +/ buried layer from under the p well into the drift region of the SA-LIGBT structure, the holes flowing into the p well can be diverted to improve device performance. The auxiliary cathode plays a vital role in preventing the triggering of the parasitic thyristor; it also plays an important role in extracting minority carriers during the turnoff transient.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Model for DMOST threshold voltage

An analytical model for the channel region in MOS-gated power transistors has been developed. The model takes into account the effect of substrate doping gradient on the threshold voltage of the transistor and it can be applied to lateral and vertical DMOS and IGBT transistor structures. The model has been tested by comparing the calculated I–V characteristics for an MOS structure having various doping gradients to the results from a 2-D device simulator.

Analysis of negative differential resistance in the I-V characteristics of shorted-anode LIGBT's

The physical mechanism responsible for the negative differential resistance (NDR) in the current-voltage characteristics of the shorted anode lateral insulated gate bipolar transistor (SA-LIGBT) is explained through two-dimensional numerical simulation. The NDR regime is an inherent feature of all SA-LIGBTs, and results from the two different conduction mechanisms responsible for current flow in the device. These conduction mechanisms are minority-carrier injection and majority-carrier flow. Since both the anode geometry and the doping profile control the onset and the degree of minority-carrier injection, the effect these parameters have on the NDR is investigated. A simple lumped-element equivalent model of the SA-LIGBT allows qualitative predictions to be made on how changes in the device geometry and doping profiles influence the NDR regime. It is shown that conductivity modulation is a necessary but not sufficient condition for the occurrence of negative resistance in SA-LIGBT devices. Also required is a large voltage drop in the high-resistivity drift region before conductivity modulation is initiated. This causes small changes in the anode current level, greatly decreasing the total resistance across the drift region.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A versatile 700-1200-V IC process for analog and switching applications

An IC process with a wide range of devices up to 1200 V is described. In addition to low-voltage bipolars and CMOS and 230-V VDMOS it provides 700-V high-side LDMOS, HV-PMOS (EPMOS) and low-voltage circuitry, low-side 1200-V LDMOS and 700-V LIGBT (lateral insulated-gate bipolar transistor), as well as 700-V interconnection. These features have been realized by using a substrate of higher resistance in a 250-300-V IC process and by adaptation in the Resurf structure for lateral DMOS. Application examples for flyback and half-bridge power conversion and as a power-bridge driver are given. >

Lateral MOS-gated power devices-a unified view

The authors present a unified view of lateral MOS-gated power devices based on the underlying device physics. This unified view facilities a qualitative understanding of the relative merit of different devices and their performance. Various MOS-controlled power and high-voltage devices can be viewed in a unified approach depending on the type of MOS gate control of the main current flowing through the device. The majority-carrier devices tend to favor speed over on-resistance. The mixed (bipolar-type) devices tend to favor lower on-resistance than speed. Hybrid devices are between these two extremes. Specifically, for high-frequency, high-voltage, and low-current applications the lateral DMOS (LDMOS) transistor is the device with the most desirable characteristics. At lower switching frequency and low-to-moderate current levels, the lateral IGBT (LIGBT) provides the same functionality with substantial areas savings. Lateral MOS-controlled thyristors (LMCTs) are suitable for low switching speed, high current applications.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lateral insulated-gate bipolar transistor (LIGBT) with a segmented anode structure

A novel lateral insulated-gate bipolar transistor (LIGBT) structure, called the segmented anode LIGBT, is presented. In this structure, the anode, which is responsible for the injection of minority carriers for conductivity modulation, is implemented using segments of p/sup +/ and n/sup +/ diffusions along the device width. This segmented design of the anode structure results in higher switching speed and reduction in device size. Depending on the value of the specific ON resistance, experimental results show that the segmented anode LIGBT has from 20% to 250% reduction in turn-off time as compared to the shorted anode LIGBT.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Kirk effect in the LIGBT devices

A study is made of the DC current-voltage characteristics of several different LIGBT (lateral insulated-gate bipolar transistor) devices both theoretically and experimentally. The theoretical part is based on the analytical expressions and includes some improvements as compared to the earlier circuit simulation models for the LIGBTs. This work extends the range of validity of these models. The fit between the theory and experiments is satisfactory also in the saturated regime of the current-voltage curves. The importance of the Kirk effect is emphasized especially for devices with short distances between the anode and cathode.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Interaction between monolithic, junction-isolated lateral insulated-gate bipolar transistors

The static and dynamic interaction between monolithically integrated n- and p-channel, high-voltage lateral insulated-gate bipolar transistors (LGBTs) are studied. In the chosen system partition, three common-source, n-channel LIBGTs are monolithically integrated on one chip using junction isolation, while the p-channel counterparts are on a separate chip. Devices on lightly doped substrates, despite their higher forward drop and longer turn-off time than those on heavily doped substrates, exhibited a lesser degree of interaction with adjacent devices, and thus are preferable for power ICs. Even though the steady-state current that flows into the emitters of adjacent devices in the ON-state is small (<5%), there are substantial (as much as 40%) current surges during the turn-on and turn-off transients. Also, the emitter areas also act as minority-carrier injectors during the last phase of the turn-off process. Similar observations are made on LIGBTs with collector shorts and hybrid Schottky injection field-effect transistors (HSINFETs), despite their faster turn-off times.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Nonuniform and latchup current detection in lateral conductivity modulated FETs

Three-dimensional effects on current distribution in lateral conductivity modulated power transistors such as the lateral insulated-gate bipolar transistor (LIGBT) are studied using the infrared microscopy technique. Nonuniform current distribution and the location of the latchup sites in these devices have been identified. This provides experimental insights into the design and optimization of these high-voltage power transistors. For optimized p/sup +/ anode LIGBT devices with a breakdown voltage of 600 V, a current density of 200 A/cm/sup 2/ at a forward voltage of 2 V, which is comparable to the DMOS IGBT, and a latchup current density above 800 A/cm/sup 2/ have been obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Comparison of p-channel lateral insulated-gate bipolar transistors with and without collector shorts

The performances of p-channel lateral insulated-gate bipolar transistors (LIGBTs) with and without collector shorts on n/sup -/ epi/n/sup +/ substrates are compared. The collector-shorted devices have a 4* improvement in turn-off time but about 1-V higher forward drop, due to a substantially reduced vertical current component. The addition of a buried layer on the emitter side increases the forward drop and reduces the turn-off time slightly for both types of LIGBTs. The presence of the collector shorts significantly improves the breakdown voltage but increases the percentage of the lateral current component, leading to a lower maximum gate controllable current.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Power integrated circuits-progress, prospects and challenges

Summary form only given. PICs (power integrated circuits) are defined as ICs combining high-voltage and/or high-current components monolithically with low-voltage/low-current control components. Broadly, three classes of technologies, based on the techniques for isolating the high- and low-voltage components, have been developed for PICs: junction-isolated, self-isolated and dielectrically isolated. Each of these technologies has found its way into applications that result in optimal performance per unit cost. Simultaneously with the development of technologies, several advancements have been made in high-voltage/power devices suitable for integration. These included the reduced surface field lateral double diffused MOS transistor (RESURF LDMOS), the isolated vertical DMOS (VDMOS), the lateral insulated gate bipolar transistor (LIGBT), the high-voltage RESURF bipolar transistors, the Schottky injection FET (SINFET), and the trench sidewall channel DMOS (TDMOS). Innovative device designs like the LIGBT have resulted in die sizes reduced by a factor of 3 to 5 and therefore in lower cost. In high-current applications, trench-based power devices are being developed for silicon die size reduction by more than a factor of 2. Additionally, with high-density control sections and cell-library-based automated design methods, custom ASIC (application-specific IC) designs are being developed rapidly at lower cost. >

Interaction Between Monolithic, Multiple, Junction-Isolated, Lateral Insulated Gate Bipolar Transistors

Interaction Between Monolithic, Multiple, Junction-Isolated, Lateral Insulated Gate Bipolar Transistors

A new hybrid VDMOS-LIGBT transistor

A p-channel vertical DMOSFET structure coupled with a lateral IGBT (insulated-gate bipolar transistors) path is described. External resistors are placed in series with either the collector terminal (the bipolar-enhanced MOSFET (BIENFET) mode) or the drain terminal (the substrate collector-shorted (SCOSH) LIGBT mode) to vary the degree of minority-carrier injection. This creates the opportunity to obtain a device with externally programmable forward-drop/switching speed tradeoff. The device is shown experimentally to have forward drops close to those of vertical and lateral IGBTs and turn-off times close to that of MOSFETs. Typical forward drops at 93 A/cm/sup 2/ range from 3-4 V and corresponding turn-off times from 4.3 to 0.22 mu s when the drain resistor is varied. This device is considered particularly attractive as a high-frequency and high-voltage power switch. >

The effect of substrate doping on the performance of anode-shorted n-channel lateral insulated-gate bipolar transistors

The performance of n-channel lateral-insulated-gate bipolar transistors (n-LIGBTs) with anode shorts on p/sup -/ epi/p/sup +/ substrates is compared to that of anode-shorted n-LIGBTs on p/sup -/ substrates, as well as to that of conventional n-LIGBTs on either substrate. It is shown that both forward-voltage drop and turn-off time are better for anode-shorted devices fabricated on p/sup -/ epi/p/sup +/ substrate than for those on p/sup -/ substrates, due to a larger percentage component of vertical bipolar current and a lower collector resistance. Forward-voltage drops of 3.05 and 3.3 V at 133 A/cm/sup 2/ and turn-off times of 400 and 750 ns have been measured for devices on p/sup -/ epi/p/sup +/ and p/sup -/ substrates respectively. All the LIGBTs showed current limiting at two to four times the ON-state conduction current during dynamic switching.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An insightful analysis of the hybrid insulated-gate bipolar transistor

The shorted-anode or hybrid insulated-gate bipolar transistor (HIGBT) is examined theoretically (using a first-order analysis) and experimentally (using specially designed test structures) to give physical insight regarding the unique electrical properties of this power switching device. Basic differences between the HIGBT and the conventional lateral IGBT reflected by measurements of on-state conductance, transient turn-off time, and latchup current are explained and shown to be critically dependent on the structural geometry of the device. Also, a previously unacknowledged mode of operation of the HIGBT is demonstrated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Network representations of LIGBT structures for CAD of power integrated circuits

To enable computer-aided design (CAD) of power integrated circuits, physical models for lateral high-voltage/power (HV/P) devices, in particular lateral insulated-gate bipolar transistor (LIGBT) structures, are developed and implemented in SPICE. The models are charge-based, and, via regional partitioning, account for the unique features of HV/P devices unaccounted for in conventional equivalent-circuit models. The implementation of the models in the circuit simulator is flexible and allows these features (e.g. multidimensional carrier flow, conductivity modulation, latchup, transcapacitance) to be simulated without having to sacrifice much physics through excessive empiricism. Device measurement of specially designed test structures, supplemented with two-dimensional numerical device simulations, support the modeling methodology and the model parameter extraction.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A hybrid VIGBT-LDMOS transistor

A hybrid VIGBT-LDMOS transistor which consists of a VIGBT (vertical insulated-gate bipolar transistor) path with a lateral DMOSFET path, implemented in a 300-V, p-channel version, has been demonstrated. The device can be operated with series resistors attached to either the collector or the drain terminals. The case in which the collector resistor equals zero is called the LACOSH-VIGBT (lateral collector shorted-vertical IGBT), and the case in which the drain resistor equals zero is called LABIENFET (lateral bipolar enhanced DMOSFET). Experimental characterization of the LACOS-VIGBT showed that the onset of the minority injection is retarded from 0.6 to 1.1 V, and the forward drop varies from 1.4 to 3.6 V and from 1.1 to 3.0 V, with and without the collector short, respectively, for 1 A (14 A/cm/sup 2/) to 6 A (83 A/cm/sup 2/) of collector current. Corresponding improvements in turnoff times are 5.5-4.4 mu s vs. 9.5-7.2 mu s. The reverse conducting diode has a forward drop of 0.82-1.57 V for 1-6 A of current and a switching time over 10 mu s. In the LABIENFET mode, the forward drop at 1 A (14 A/cm/sup 2/) decreases from 15.6 to 1.4 V when the collector series resistance changes from 150 to 0 Omega , with corresponding turnoff times of 1.7-5.5 mu s. This device is attractive either as a fast switching VIGBT or as a low-voltage-drop FET, with an integral antiparallel diode.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

IIB-2 the effect of SIPOS on the performance of lateral insulated gate bipolar transistors

IIB-2 the effect of SIPOS on the performance of lateral insulated gate bipolar transistors