The dual gate base resistance controlled thyristor

A new device concept, called the dual gate base resistance controlled thyristor (DG-BRT), is introduced for simultaneously obtaining the low on-state voltage drop of a thyristor together with a good forward biased safe operating area. The two gates are used to control an N-channel and a P-channel MOSFET integrated with a thyristor structure using the DMOS process. When a positive bias is applied to both gates, the device operates in the thyristor-mode with a low on-state voltage drop at even high current densities. When a negative bias is applied to the OFF-gate, the device operates in the IGBT-mode with the saturated current controlled by the positive bias applied to the ON-gate. The results of two-dimensional numerical simulations and measurements performed on devices with 600 V forward blocking capability are reported     

The injection efficiency controlled IGBT

An IGBT structure in which the anode injection efficiency changes with current density, the injection efficiency controlled IGBT (EEC-IGBT), is proposed. The anode injection efficiency of the IEC-IGBT is controlled via a current sensor inherent in its structure. Anode injection efficiency is strongly enhanced at low device current density and significantly reduced at high device current density. This enables the device to have a low on-state voltage drop (V_on) and superior safe operation area (SOA), making it very suitable for high-power applications. Simulation results based on 3.3 KV DMOS NPT devices indicate the on-state voltage drop of the IEC-IGBT is reduced by 0.6 V (20%) and the short-circuit SOA (SCSOA) is improved by several times compared to the conventional IGBT     

A novel single gate MOS controlled current saturated thyristor

A novel single gate MOS controlled current saturation thyristor (MCST) device is proposed. In the on-state the MCST operates in thyristor-like mode at low anode voltage and enters the IGBT-like mode automatically with increasing anode voltage, offering a low on-state voltage drop and current saturation capability. Simulation results based on 6.5 kV trench devices indicate the turn-off energy loss of the MCST is reduced by over 35% compared to the IGBT. The saturation current density of the MCST is strongly dependent on the on-set voltage of the p ⁺ buffer/n-well junction, leading to its excellent safe operation area (SOA) and making it suitable for high power applications     

一种新型SOI衬底上带有阳极辅助栅结构的SJ-LIGBT

提出了一种新型的SOI衬底上的横向绝缘栅双极型晶体管(LIGBT)。该LIGBT在漂移区采用了超结(SJ)结构,并且在阳极采用了新颖的阳极辅助栅结构。这种器件由于采用了上述2种结构,相比于普通的LIGBT,它的正向压降更低,开关速度更快。文章对器件的一些关键参数(如P-drift区掺杂浓度、阳极栅宽度和载流子寿命)对器件关断时间的影响进行了仿真。仿真结果表明,提出的新型结构器件与常规LIGBT器件相比,关断速度可以提高30%。     

Optimized design of 4H-SiC floating junction power Schottky barrier diodes

SiC floating junction Schottky barrier diodes were simulated with software MEDICI 4.0 and their device structures were optimized based on forward and reverse electrical characteristics.Compared with the conventional power Schottky barrier diode,the device structure is featured by a highly doped drift region and embedded floating junction region,which can ensure high breakdown voltage while keeping lower specific on-state resistance,solved the contradiction between forward voltage drop and breakdown voltage.The simulation results show that with optimized structure parameter,the breakdown voltage Can reach 4 kV and the specific on-resistance is 8.3 mΩ·cm2.     

Performance analysis of the segment npn anode LIGBT

The performance of a high-voltage lateral insulated gate bipolar transistor (LIGBTs) with segmented n+p/n anode fabricated in junction isolation technology is experimentally investigated at both room and elevated temperatures. Detailed two dimensional numerical modeling of a vertical representation of the structure shows that significant electron current passes through the n/sup +/p/n segment of the anode region during the on-state and when devices are subjected to clamped inductive switching. It is shown that the magnitude of electron current can be controlled by modifying the p-base charge which enables enhancement of the turn-off loss/forward voltage drop tradeoff in comparison to conventional LIGBTs.     

High current density 800-V 4H-SiC gate turn-off thyristors

4H-SiC gate turn-off thyristors (GTOs) were fabricated using the recently developed inductively-coupled plasma (ICP) dry etching technique. DC and ac characterisation have been done to evaluate forward blocking voltage, leakage current, on-state voltage drop and switching performance. GTOs over 800 V dc blocking capability has been demonstrated with a blocking layer thickness of 7 μm. The dc on-state voltage drops of a typical device at 25 and 300°C were 4.5 and 3.6 V, respectively, for a current density of 1000 A/cm². The devices can be reliably turned on and turned off under an anode current density of 5000 A/cm² without observable degradation     

An insulated gate bipolar transistor employing the plugged n anode

A vertical Insulated Gate Bipolar Transistor, entitled CB-IGBT(Carrier-inducing Barrier-controlled IGBT) has been proposed and verified by a two-dimensional numerical simulation. The structure of the proposed device is almost identical with that of the conventional IGBT, except for the anode structure in which the p-barrier region and n⁺ anode region are employed. In the CB-IGBT, the potential barrier height at the junction between the p-barrier region and n-drift region is controlled by the amount of carriers, so that the trade-off relation between the on-state voltage drop and the switching speed is decoupled efficiently. The switching speed of CB-IGBT is so much enhanced with a negligible increase of the on-state voltage drop, since electrons stored in the n-drift region can be extracted rapidly into the n⁺ anode via p-barrier region during turn-off process.     

缓冲层与透明阳极结构对GCT通态特性的影响

在建立GCT器件模型的基础上,研究了缓冲层与透明阳极结构对GCT性能影响。模拟结果表明,缓冲层与透明阳极各自区域中的总杂质量是决定GCT的通态压降的关键因素。通过协调各自区域的峰值掺杂浓度与厚度,可以合理地控制该区域的总杂质量,降低GCT的通态压降。此外,缓冲层和透明阳极相结合结构加速了器件关断过程中载流子的泄放,改善了GCT关断性能。这些结果对于进一步优化GCT器件设计与制造有着重要的参考价值。     

Dual MOS gate controlled thyristor (DMGCT) structure withshort-circuit withstand capability superior to IGBT

A dual MOS gate controlled thyristor (DMGCT) structure is analyzed with experimental data and shown to have superior performance over insulated-gate bipolar transistor (IGBT) for power switching applications. The DMGCT device structure consists of a thyristor structure with the thyristor current constrained to flow via the channel region of a MOSFET. Although this increases the on-state voltage drop in the thyristor current path by a small amount due to the voltage drop across the low-voltage series MOSFET, this structure allows control of the thyristor current by the gate voltage applied to the MOSFET even after latch-up of the thyristor. This configuration allows uniform turn-off in the device with no current crowding. The DMGCT does not have any parasitic thyristor structure. In contrast to the IGBT, the saturation current of the DMGCT can be controlled independently of the on-state voltage drop     

The dual gate emitter switched thyristor (DG-EST)

A new device structure, called the dual gate emitter switched thyristor (DG-EST), is introduced for simultaneously obtaining on-state voltage drops lower than that of the conventional emitter switched thyristor (C-EST) and the high-voltage current saturation features of the Dual Channel EST (DC-EST). The DG-EST contains a DC-EST section and a C-EST section with a common thyristor section that can be controlled using two independent gate electrodes. When a positive bias is applied to both the gates, the device operates in a thyristor mode with the thyristor current constrained to flow through two lateral MOSFETs which minimizes the on-state voltage drop. When a “zero” bias is applied to the gate of the conventional EST, the device exhibits high-voltage current saturation, with the bias on the gate of the DC-EST controlling the saturated current. In this paper, the results of measurements performed on devices fabricated with a six-mask IGBT-like process are reported     

Numerical analysis of turn-off characteristics for a gate turn-off thyristor with a shorted anode emitter

Turn-off current waveform for a gate turn-off thyristor (GTO) with a shorted anode emitter has been calculated numerically by solving the semiconductor basic equations in an equivalent one-dimensional model device. This model is derived from the analysis of current and carrier distributions obtained by a two-dimensional calculation of the on-state of GTO. A calculated turn-off current waveform agrees well with the experimental waveform. The computational time of one case is about 2 min. It is shown that this one-dimensional analysis method is useful for the calculation of the turn-off time. Using this one-dimensional model during the turn-off process and the two-dimensional model in the on-state, the relation between turn-off time and the forward voltage drop can be obtained in relation to the shorted emitter structure. It is shown that the shorted emitter structure is useful to improve this tradeoff relation.     

Electron irradiation of field-controlled thyristors

The influence of 3-MeV electron irradiation upon the characteristics of asymmetrical field-controlled thyristors has been examined for fluences of up to 16 Mrad. In addition to the lifetime reduction due to the radiation damage, carrier removal effects have also been observed in the very lightly doped n-base region of these devices. The leakage current, even after radiation at the highest fluenee, is not significantly increased and the blocking characteristies of these devices are not degraded. In fact, a small improvement in the blocking gain has been observed at low gate voltages. The electron irradiation has been found to increase the forward voltage drop during current conduction and to reduce the forced gate turn-off time. Gate turn-off times of less than 500 ns have been achieved by irradiation with a fluence of 16 Mrad. However, this is accompanied by a large increase in the forward voltage drop. Tradeoff curves between the forward voltage drop and the gate turn-off time have been obtained. From these curves, it has been determined that gate turnoff times of 1 µs can be obtained without a significant increase in the forward voltage drop for devices capable of blocking up to 600 V.     

A novel high performance insulated gate bipolar transistor

For the first time, a new concept of LDE-IGBT (local drift-region enhanced IGBT) is proposed and verified by two-dimensional (2D) device-circuit mixed simulations. The structure of the proposed device is almost identical to that of the conventional IGBT, except for an additional n⁺ plugged region under the gate contact. The proposed device exhibits larger maximum operating current, meaning higher current capability, which is expected for high-power operation. The simulation results indicate the LDE-IGBT can obtain a low on-state voltage drop with negligible increase of turn-off time due to lower sensitivity of turn-off time to the novel structure. Therefore, the trade-off relation between on-state voltage and turn-off time is improved and decoupled efficiently. Finally, the effects of three novel structure parameters on the on-state voltage are demonstrated in detail.     

具有积累层沟道的槽栅IGBT结构

提出了一种具有积累层沟道的槽栅IGBT结构。仿真结果表明：在阻断电压为1200V,集电极电流密度为100 A/cm2,温度分别为300K和400K下的情况下,积累层沟道槽栅IGBT的正向压降分别为1.5V 和2V而常规槽栅IGBT分别为1.7V和2.4V。新结构比常规槽栅IGBT具有更低的开态压降和更大的正向安全工作区。文中同时分析了积累层沟道槽栅IGBT的阻断特性和关断特性。     

IEGT的高温特性与闩锁失效分析(英文)

介绍了平面栅电子注入增强型栅极晶体管(IEGT)的闩锁效应,讨论了温度对关键特性参数如通态压降、正向阻断电压及开关时间的影响。利用ISE软件模拟了IEGT在高温下的导通特性、阻断特性和开关特性,分析了IEGT在高温下的失效原因,提出了改善其高温安全工作区(SOA)的措施。     

Insulated gate bipolar transistor with trench gate structure of accumulation channel

An accumulation channel trench gate insulated gate bipolar transistor (ACT-IGBT) is proposed. The simu-lation results show that for a blocking capability of 1200 V, the on-state voltage drops of ACT-IGBT are 1.5 and 2 V at a temperature of 300 and 400 K, respectively, at a collector current density of 100 A/cm~2. In contrast, the on-state voltage drops of a conventional trench gate IGBT (CT-IGBT) are 1.7 and 2.4 V at a temperature of 300 and 400 K,respectively. Compared to the CT-IGBT, the ACT-IGBT has a lower on-state voltage drop and a larger forward bias safe operating area. Meanwhile, the forward blocking characteristics and turn-off performance of the ACT-IGBT are also analyzed.     

Vertical channel field-controlled thyristors with high gain and fast switching speeds

A new, planar, surface-grid, field-controlled thyristor (FCT) structure is described. The structure is fabricated by using orientation-dependent (preferential) etching and selective vapor epitaxial growth to obtain vertical grid walls. The resulting high channel-length-to-width aspect ratio produces devices with high blocking gains and fast gate turnoff speeds. Devices have been fabricated with the capability of blocking more than 1000 V with an applied grid bias of 32 V, and simultaneously exhibiting a low forward voltage drop in the on-state. These surface-grid devices exhibit gate turnoff capability with turnoff times of less than 500 ns at a rated cathode-anode current of 1 A.     

Implementing the TIL Concept in high-power GTO's

This work reports the results obtained in the implementation of the novel two interdigitation level (TIL) gate-cathode configuration in high-voltage (2000 V), high-current (600 A), gate turn-off (GTO) thyristors. It is shown that the implementation of the TIL concept in high-power GTO's, while relaxing the trade-off between the doping/ width of the p base and the main electrical parameters, offers a fair balance between manufacturability ease/cost effectiveness and overall device performance. A distinct benefit obtained through the implementation of the TIL pattern in high-power GTO's is expressed by the ability of devices with an active area of only 1.7 cm²to safely switch off an anode current of 600 A with a practically usable operational turn-off gain Goffof 5-8. The low on-state voltage drop of gold-doped, high-power TIL GTO's is accompanied by a high nonrepetitive surge current capability. The trial devices possess a good latching/turn-on sensitivity accompanied by an immunity to noise (high dV/dt capability).     

Comparison of high speed DI-LIGBT structures

The performance of the DI segmented collector (SC)-LIGBT is compared to the collector shorted (CS)-LIGBT. The SC-LIGBT allows for adjusting the tradeoff between switching speed and on-state voltage drop by simply changing the P⁺ collector segment width during device layout. In contrast to previously reported junction isolated (JI) devices, the DI SC-LIGBT was observed to have a turnoff speed similar to the CS-LIGBT with a higher forward drop than the conventional LIGBT. The on-state performance of the integral diodes of the SC-LIGBTs was found to be superior to the integral diode of the CS-LIGBT. The integral diodes of both the CS and the SC-LIGBTs were found to have much superior switching characteristics compared to a lateral PiN diode at the expense of a higher on-state voltage drop. Thus, the superior switching characteristics of the integral diode in the SC-LIGBT complements its fast switching behavior making this device attractive for compact, high frequency, high efficient, power ICs.