Reverse Conducting IGBT Research Articles

Simulation study of a novel GaN on Si Quasi‐Vertical Reverse‐Conducting Insulated Gate Bipolar Transistor

Abstract In this paper, a novel GaN on Si quasi-vertical reverse conducting insulated gate bipolar transistor(RC-IGBT) with a new NPN structure is proposed and simulated by Silvaco TCAD. The distinctive feature of this structure lies in fabricating the original bottom P-Collector on the wafer surface. In comparison to conventional IGBT devices with PNPN structures, this NPN structure overcomes two major challenges: the difficulty in forming ohmic contacts due to the activation difficulty of the bottom P-GaN and the necessity of creating backside through-holes for electrode formation. Simultaneously, the N-GaN in the emitter and reverse-conducting regions can be selectively regrown through Metal-Organic Chemical Vapor Deposition (MOCVD) or Molecular Beam Epitaxy (MBE), avoiding the etching effect of top-layer N-GaN on P-GaN during the fabrication of P-type electrodes. This approach demonstrates a high level of process feasibility. In this paper, Silvaco TCAD is used to simulate the static and dynamic characteristics of this novel quasi-vertical RC-IGBT device. The simulation results reveal that the device has a high saturation current(Ion,sat) density of 18224.67A/cm2 at Vge=14V,a threshold voltage (Vth) of 5V,a breakdown voltage of 828V,a latch-up voltage of 800V ,and a switching speed of nanoseconds. In addition, the selection of device parameters is studied in this paper.

16kV 4H-SiC Reverse-Conducting IGBT With a Collector-Side Injection-Enhanced Structure for Low Reverse-Conducting Voltage

16kV 4H-SiC Reverse-Conducting IGBT With a Collector-Side Injection-Enhanced Structure for Low Reverse-Conducting Voltage

Novel fast-switching P-poly trench collector reverse conducting IGBT with different N-buffer position

A novel fast-switching P-poly trench collector reverse-conducting insulated gate bipolar transistor (RC-IGBT) with different N-buffer position (DBP) is proposed and investigated. Firstly, the N-buffer on P-poly Trench-Collector (TC) not on P+ and N+ collector will unaffected realize snapback-free with and without interface charge exist in the forward conduction. Secondly, N-buffer on TC can keep the fast extraction channel to the N+ collector open all the time, so that the ultralow turn-off loss (EOFF) can be achieved in IGBT mode, and the reverse recovery charge (Qrr) can be reduced in diode mode. Thirdly, N-buffer on TC makes the electric field distribution more uniform during forward blocking, thus further improving the breakdown voltage (BV). Fourth, N-buffer on TC can also provide more electrons to reduce forward peak recovery voltage (VFRM) during diode forward recovery mode. Compared with PNTC RC-IGBT, the proposed RC-IGBT enjoys lager breakdown voltage, and can reduce VFRM by 83%, Qrr by 27%, and the EOFF by 36%.

Novel Low-Loss Reverse-Conducting Insulated-Gate Bipolar Transitor with Collector-Side Injection-Enhanced Structure

In this paper, a new concept of low-loss Reverse-Conducting Insulated-Gate Bipolar Transistor with Collector-side Injection-Enhanced structure (RC-IGBT-CIE) is proposed and investigated using simulations. In reverse conduction (the on state of the diode mode), the CIE structure enhances the collector-side carrier concentration of the proposed RC-IGBT-CIE, which results in low reverse-conducting voltage (VF). The low reverse recovery loss and low turn-on loss using an inductive load circuit are obtained by using the modified carrier concentration profile resulted from both the CIE effect and the low-injection-efficiency p-emitter. Simulation results show that, with the same sum of turn-on loss and reverse recovery loss (Eon + Erec), when compared to conventional RC-IGBT with anti-parallel thyristor (RC-IGBT-thyristor), the RC-IGBT-CIE reduces VF by 9.2%, and meanwhile, with the same total conducting voltage (Von, sat + VF), the total switching loss (Eoff + Eon + Erec) is reduced by 20.9% but does not sacrifice short-circuit capability.

Low Switching Loss Built-In Diode of High-Voltage RC-IGBT with Shortened P+ Emitter

In this paper, a low switching loss built-in diode of a high-voltage reverse-conducting insulated gate bipolar transistor (RC-IGBT) is proposed without deteriorating IGBT characteristics. It features a particular shortened P+ emitter (SE) in the diode part of RC-IGBT. Firstly, the shortened P+ emitter in the diode part can suppress the hole injection efficiency resulting in the reduced carriers extracted during the reverse recovery process. The peak of the reverse recovery current and switching loss of the built-in diode during reverse recovery is therefore lowered. Simulation results indicate that the diode’s reverse recovery loss of the proposed RC-IGBT is lowered by 20% compared with that of the conventional RC-IGBT. Secondly, the separate design of the P+ emitter prevents the performance of IGBT from deteriorating. Finally, the wafer process of the proposed RC-IGBT is almost the same as that of conventional RC-IGBT, which makes it a promising candidate for manufacturing.

A Novel Concept of Electron–Hole Enhancement for Superjunction Reverse-Conducting Insulated Gate Bipolar Transistor with Electron-Blocking Layer

A novel snapback-free superjunction reverse-conducting insulated gate bipolar transistor (SJ-RC-IGBT) is proposed and verified by simulation. In the SJ-RC-IGBT, the parasitic P/N/P/N structure as thyristor or Shockley diode demonstrates large conductivity due to an overabundance of carriers for reverse conduction. By preventing electrons from leaking across the N+ region at the collector side, the extra electron-blocking (EB) layer introduced in the SJ-RC-IGBT can dramatically enhance electron-hole pairs in the N/P-pillars. Hence, the SJ-RC-IGBT demonstrates a low on-state voltage (Von). In addition, snapback-free characteristics and a large safe operating area (SOA) are also achieved in the SJ-RC-IGBT. During the turn-off process, a significant amount of electrons are extracted by parasitic MOS across the EB layer at the collector side to decrease the turn-off loss (Eoff). According to the optimized results, the SJ-RC-IGBT with EB layer obtains an ultralow Eoff of 3.9 mJ/cm2 at Von = 1.38 V with 88% and 81% decreases, respectively, compared with the conventional reverse-conducting IGBT (CRC-IGBT) and superjunction IGBT (SJ-IGBT).

Experimental Investigation on Displacement Damage Effects of Trench Field-Stop Reverse-Conducting Insulated-Gate Bipolar Transistor

The insulated-gate bipolar transistor (IGBT) is characterized by metal-oxide-silicon (MOS)-gating, high current density, and high blocking capabilities. The trench field-stop reverse-conducting IGBT (TFR-IGBT) is distinguished from conventional IGBT (CON-IGBT) by trench MOS gate, field-stop layer, and collector-short structure. As a composite structure made of MOS and bipolar junction transistors (BJTs), TFR-IGBT is susceptible to displacement damage (DD). This work reports the DD effects on TFR-IGBT with the fast neutron fluence up to a fluence of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> . The transfer, forward conductive, and forward blocking characteristics are degraded subsequent to neutron exposures. The suppression of the hump current in the transfer curve is observed by neutron-induced damage. This article proposes, from a device physics perspective, the mechanism behind the characteristics degradation from DD in TFR-IGBT. The dependencies of the key parameters on neutron fluence are analytically modeled. Our models provide a good fit to the experimental data of the IGP20N65H5 TFR-IGBT subjected to fission neutrons.

Novel Backside Structure for Reverse Conducting Insulated-Gate Bipolar Transistor With Two Different Collector Trench

A novel reverse-conducting insulated gate bipolar transistor (RC-IGBT) with two different collector trench (DCT) is proposed. One of the collector trenches is filled with heavily doped N-type polysilicon (N-poly) and the other is filled with heavily doped N- and P-poly. An electron accumulation layer is formed along the sidewall of trench owing to built-in potential difference between the N-poly and the N-drift region. The electron accumulation layer and collector trenches block the electric field, which behaves just like the N-buffer layer of the conventional RC-IGBT (Con. RC-IGBT). Similarly, due to potential difference between the P-poly and N-drift region, a high-density hole inversion layer is formed to narrow the electron current path as a high resistance. The DCT RC-IGBT achieves snapback-free in a small cell pitch without additional control. Moreover, the DCT RC-IGBT shows better tradeoff between turn-off loss and ON-state voltage drop than that of con. RC-IGBT. For the same forward voltage drop, the turn-off loss is reduced by 26%.

A snapback-free reverse-conducting IGBT with multiple extraction channels

A snapback-free reverse-conducting IGBT with multiple extraction channels

Thermal Performances and Annual Damages Comparison of MMC Using Reverse Conducting IGBT and Conventional IGBT Module

Insulated gate bipolar transistor (IGBT) modules in modular multilevel converters (MMCs) have inherent unbalanced power loss distribution and temperature swing. Some chips may become the hotspots and have much larger temperature swing than others, which seriously compromises the lifetime of the IGBT modules. Therefore, effective improvement measures that are low cost become crucial for the IGBT modules in MMC. Reverse conducting IGBT (RC-IGBT) constructs the IGBT and freewheel diode in a single chip, which has the advantages of lower thermal resistance, lower switching loss, and larger heat capacity. In this article, a new generation of RC-IGBT module and conventional IGBT (Con-IGBT) module from Fuji Electric with the same packaging are both used in the MMC. A newly defined current density for RC-IGBT and Con-IGBT module is proposed. The thermal performances and annual damages of the two modules under different power factors are comprehensively compared at the same module current density. The results show that when the power factor is greater than 0.4, using RC-IGBT can significantly improve the thermal performance of MMC submodules (SMs) and extend their lifetime. In addition, the reasons for the comparison results are also discussed in this article. Finally, the advantages of RC-IGBT in terms of thermal performances are verified by experiment. This article also provides a guideline for the design of MMC SMs.

A Method for Thermal Resistance Test of Reverse-Conducting IGBT (RC-IGBT)

The RC-IGBT is integrated IGBT and fast recovery diode (FRD) on the same chip. RC-IGBT has smaller size, higher power density, lower cost, and higher reliability. However, due to the snap-back effect, the traditional test circuit and method cannot accurately measure the thermal resistance of RC-IGBT. In this paper, a thermal resistance test circuit based on series compensation of two devices is proposed, and the voltage drop Vec of the body diode is taken as the temperature sensitive parameter of RC-IGBT. The thermal response curve is obtained basing on the change of Vec with temperature. By comparing the traditional method with the new method, it can be seen that the new method can greatly improve the test accuracy.

Electrical Characteristics of 1,200 V Reverse Conducting-IGBT

Electrical Characteristics of 1,200 V Reverse Conducting-IGBT

An Improved V CE–E OFF Tradeoff and Snapback-Free RC-IGBT With P⁺ Pillars

In this article, a novel snapback-free reverse-conducting insulated-gate bipolar transistor (RC-IGBT) with P+ pillars at the collector side (PPC) is proposed and investigated by TCAD simulations. This structure features the P+ pillar structure at the side of collector and exits a gap of N-buffers above N+ collector. The P+ pillars increase the distributed resistance below the buffer layer during turn-on transient, show bipolar mode, and eliminate the snapback phenomenon. Accordingly, the structure eliminates the snapback phenomenon with a smaller half-cell pitch of ${10}~\mu \text{m}$ , making that the device is more reliable and suitable for parallel connection. For the same forward voltage drop, the turn-off loss of the PPC structure is reduced by 34%.

A Novel Self-Controlled Double Trench Gate Snapback Free Reverse-Conducting IGBT With a Built-in Trench Barrier Diode

A novel double gate snap-back free reverse-conducting insulated-gate bipolar transistor (RC-IGBT) is proposed in this article, which merges a trench field stop IGBT and a trench barrier diode in a monolithic device. The backside n-channel works at weak inversion mode in forward conduction state and can be automatically turned into strong inversion mode in the reverse conduction state. Therefore, bidirectional conduction capability with snapback free characteristics is achieved in the novel RC-IGBT. Performance comparison with conventional RC-IGBT is carried out based on Sentaurus device simulations, the results show that the novel RC-IGBT device in this article exhibits excellent overall performance in both IGBT and diode modes, the reverse recovery performance is significantly improved owing to the topside trench barrier structure and backside self-controlled carrier injection, compared to the conventional RC-IGBT, the proposed device demonstrates 32% lower ${I}_{\text {rrm}}$ and 63% lower ${t}_{\text {rr}}$ .

Reverse-Conducting Insulated Gate Bipolar Transistor: A Review of Current Technologies

The reverse-conducting insulated gate bipolar transistor (RC-IGBT) has several benefits over a separate IGBT and diode solution and has the potential to become the dominant device within many power electronic applications; including, but not limited to, motor control, resonant converters, and switch-mode power supplies. However, the device inherently suffers from many undesirable design tradeoffs which have prevented its widespread use. One of the most critical issues is the snapback seen in the forward conduction characteristic which can prevent full turn-on of the device and result in the device becoming unsuitable for parallel operation (required in many high voltage modules). This phenomenon can be suppressed but at the expense of the reverse conduction performance. This paper provides an overview of the technical design challenges presented by the RC-IGBT structure and reviews alternative device concepts which have been proposed in literature. Analysis shows that these alternate concepts either present a tradeoff in performance characteristics, an inability to be manufactured, or a requirement for a custom gate drive.

A Snapback-Free Reverse Conducting Insulated-Gate Bipolar Transistor With Discontinuous Field-Stop Layer

In this paper, a novel reverse conducting insulator gate bipolar transistor (RC-IGBT) with discontinuous field-stop (DFS) layer is proposed and investigated. The DFS increases the distributed resistance near the collector side in the unipolar mode; and thus, eliminates the snapback phenomenon with a reduced half-cell pitch of $60~\mu \text{m}$ . In the blocking state, the depletion region is pinched off by the DFS and thus punchthrough is avoided, ensuring high breakdown voltage of 1200 V. The DFS RC-IGBT shows higher short-circuit ruggedness and increases the short-circuit duration time by 30% compared with the conventional RC-IGBT due to the decreased base transport factor. The proposed structure also achieves better tradeoff between turn-OFF loss and forward voltage drop. For the same forward voltage drop, the turn-OFF loss is reduced by 30%.

Simulation Study of a Novel Snapback-Free and Low Turn-Off Loss Reverse-Conducting IGBT With Controllable Trench Gate

A novel ultra-fast snapback-free controllable trench gate (CTG) reverse-conducting insulated gate bipolar transistor (RC-IGBT) is proposed and investigated by simulation. It features a CTG in the collector side and a bias voltage ( ${V}_{\text {RC}}$ ) is applied between the CTG and collector electrode. In the forward conduction state with ${V}_{{\text {RC}}} , a high-density hole inversion layer is formed around the CTG. The CTG acts as not only a folded controllable hole injector to enhance the hole injection efficiency, but also an electron barrier to increase the distributed resistance. The CTG RC-IGBT achieves a low on-state voltage drop ( ${V}_{{ \mathrm{\scriptscriptstyle ON}}}$ ) and snapback-free with a small cell pitch. In the blocking state with ${V}_{\text {RC}} > {0}$ , an electron accumulation layer is formed around the CTG. The electron layer together with the CTG acts as an equivalent N-buffer layer to stop the electric field and support high breakdown voltage. During turn-off, the CTG RC-IGBT behaves like a unipolar device without long tail current because the hole injection is deactivated by properly switching the ${V}_{\text {RC}}$ . Compared with conventional RC-IGBT, the proposed device decreases the ${V}_{\text {on}}$ and turn-off energy loss ( ${E}_{\text{off}}$ ) by 34% and 74%, respectively, under the load current of 100 A/cm2 and bus voltage of 600 V.

Research on Single-Phase PWM Converter with Reverse Conducting IGBT Based on Loss Threshold Desaturation Control

In the application of vehicle power supply and distributed power generation, there are strict requirements for the pulse width modulation (PWM) converter regarding power density and reliability. When compared with the conventional insulated gate bipolar transistor (IGBT) module, the Reverse Conducting-Insulated Gate Bipolar Transistor (RC-IGBT) with the same package has a lower thermal resistance and higher current tolerance. By applying the gate desaturation control, the reverse recovery loss of the RC-IGBT diode may be reduced. In this paper, a loss threshold desaturation control method is studied to improve the output characteristics of the single-phase PWM converter with a low switching frequency. The gate desaturation control characteristics of the RC-IGBT’s diode are studied. A proper current limit is set to avoid the ineffective infliction of the desaturation pulse, while the bridge arm current crosses zero. The expectation of optimized loss decrease is obtained, and the better performance for the RC-IGBTs of the single-phase PWM converter is achieved through the optimized desaturation pulse distribution. Finally, the improved predictive current control algorithm that is applied to the PWM converter with RC-IGBTs is simulated, and is operated and tested on the scaled reduced power platform. The results prove that the gate desaturation control with the improved predictive current algorithm may effectively improve the RC-IGBT’s characteristics, and realize the stable output of the PWM converter.

Loss Characteristics of 6.5 kV RC-IGBT Applied to a Traction Converter

6.5 kV level IGBT (Insulated Gate Bipolar Transistor) modules are widely applied in megawatt locomotive (MCUs) traction converters, to achieve an upper 3.5 kV DC link, which is beneficial for decreasing power losses and increasing the power density. Reverse Conducting IGBT (RC-IGBT) constructs the conventional IGBT function and freewheel diode function in a single chip, which has a greater flow ability in the same package volume. In the same cooling conditions, RC-IGBT allows for a higher operating temperature. In this paper, a mathematic model is developed, referring to the datasheets and measurement data, to study the 6.5 kV/1000 A RC-IGBT switching features. The relationship among the gate desaturated pulse, conducting losses, and recovery losses is discussed. Simulations and tests were carried out to consider the influence of total losses on the different amplitudes and durations of the desaturated pulse. The RC-IGBT traction converter system with gate pulse desaturated control is built, and the simulation and measurements show that the total losses of RC-IGBT with desaturated control decreased comparing to the RC-IGBT without desaturated control or conventional IGBT. Finally, a proportional small power platform is developed, and the test results prove the correction of the theory analysis.

Multiphase Power Converter Integration in Si: Dual-Chip and Ultimate Monolithic Integrations

This paper deals with the monolithic integration of a multiphase generic static power converter (dc/ac or ac/dc). The integration aims at minimizing wire bonds in order to improve the electrical performance as well as the reliability of power converters. To that end, three multiterminal monolithic power Si chips are devised and extensively studied by 2-D simulations. The first power chip integrates the reverse-conducting IGBT devices that compose the high-side part of the converter circuit. This chip is called the common anode and is validated through experimental realizations. The second power chip integrates the reverse-conducting IGBT devices that compose the low-side part of the converter. This chip is called the common cathode chip. The common anode and cathode power chips are judiciously packaged on a Printed Circuit Board substrate over which an insulating Kapton film is laid and through which window openings are realized. The partial flip-chip packaging, of the two power chips, enables the realization of a compact power H-bridge converter with the lowest stray inductance. The third chip integrates the power converter within a single silicon chip and, consequently, eliminates wire bonds. It is considered as the ultimate integration approach. The latter is validated on a monolithic H-bridge inverter by using Sentaurus mixed-mode 2-D numerical simulations.