Hybrid Schottky injection MOS-gated power transistor

A modified Schottky injection field effect transistor (SINFET) which offers lower on-resistance and a switching speed comparable to conventional n-channel LDMOSTs is described. The fabrication process is similar to that of an LDMOS transistor but with the high-low (n+n-) `ohmic? contact at the drain replaced by a parallel combination of a Schottky barrier and a pn junction diode. This hybrid anode injects minority carriers into the n- drift region, which in turn provides conductivity modulation. A current handling capability 3.5 times larger than that of the LDMOST is achieved. With the minority carrier injection level limited by the Schottky barrier, the total amount of minority carriers injected by the hybrid anode is much lower than that injected by the pn junction diode alone. Thus, the device speed is comparable to the conventional n-channel LDMOST. By minimising the shunting resistance in the p-channel region, devices with a latch-up current density of 400 A/cm2 are obtained.     

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⁺ and n⁺ diffusion along the device width. This minimizes the forward bias of the p⁺ injector during device turn-off, resulting in higher switching speed compared to the shorted-anode LIGBT. Since the n⁺ 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     

Experimental demonstration of an ultra-fast double gate inversion layer emitter transistor (DG-ILET)

In this letter we demonstrate experimentally a novel ultra-fast power device structure termed the double gate inversion layer emitter transistor (DG-ILET). The device is made in HV CMOS technology and its operation is based on a new physical injection mechanism previously reported and demonstrated experimentally (Udrea et al., 1996), namely the use of a MOS inversion layer as a minority carrier injector. The DG-ILET offers very fast turn-off associated with anode shorted lateral IGBT structures and low on-state voltage drop similar to standard lateral IGBTs without anode shorts. Unlike anode shorted structures, the DG-ILET does not exhibit a long, undesirable on-state snapback.     

Lateral insulated-gate bipolar transistor (LIGBT) with a segmentedanode 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 ⁺ and n⁺ 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     

混合型LIGBT／LDMOS晶体管瞬态响应的电荷控制模型

本文提出一种新型横向绝缘栅双极晶体管／横向扩散ＭＯＳ混合晶体管（ＬＩＧＢＴ／ＬＤＭＯＳ），在有非平衡电子抽出下截止瞬态响应的电荷控制模型。由考虑非准静态效应的积分式连续性方程，导出双载流子动态电荷控制表示式；计及其中双极晶体管宽漂移区的电导调制效应和瞬态电荷分布效应，利用保角变换求得抽出区导通电阻，从而获得归一化瞬态截止电流和瞬态截止时间及它们与漂移区长度的材料参数，特别是与两器件宽度经的关系，据     

The SINFET—A Schottky injection MOS-gated power transistor

A new MOS-gated power device, the Schottky injection FET (SINFET), is described in this paper. The device offers 6 times higher current handling capability than conventional n-channel power LDMOS transistors of comparable size and voltage capability and still maintains a comparable switching speed. The low on-resistance is obtained by conductivity modulation of the high-resistivity n- drift region using a Schottky injector. Since only a small number of minority carriers are injected, the speed of the device is not degraded substantially and high latchup resistance is achieved. Breakdown voltages and specific on-resistance observed on typical devices are 170 V and 0.01 Ω . cm², respectively. Gate-turn off times are of the order of 30 ns. Two-dimensional simulation and experimental results comparing the SIN-FET with the LDMOST and lateral insulated gate transistor (LIGT) are presented.     

A new gradual hole injection dual-gate LIGBT

A new shorted-anode lateral insulated gate bipolar transistor (SA-LIGBT), entitled gradual hole injection dual gate LIGBT (GHI-LIGBT), is proposed and fabricated. The new device employs a dual gate and p⁺ injector in order to initiate the hole injection gradually from the anode electrode into the drift region so that the negative differential resistance (NDR) regime may be eliminated. The experimental results show that the NDR regime, which may cause undesirable device characteristics, is completely eliminated in the GHI-LIGBT, and the forward voltage drop is reduced by 1 V at the current density of 200 A/cm² in comparison with the conventional SA-LIGBT     

Analysis of negative differential resistance in theI-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     

An insightful analysis of the hybrid insulated-gate bipolartransistor

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     

SOI-LIGBT寄生晶体管电流增益的研究

采用二维器件模拟仿真软件Tsuprem4和Medici模拟了SOI-LIGBT的n型缓冲层掺杂剂量、阳极p+阱区长度、漂移区长度以及阳极所加电压对SOI-LIGBT寄生晶体管电流增益β的影响,通过理论分析定性的解释了产生上述现象的原因和机理,并且通过实验测试结果进一步验证了分析结论的正确性。其中,n型缓冲层掺杂剂量对电流增益β的影响最为明显,漂移区长度的影响最弱。基本完成了对SOI-LIGBT寄生晶体管电流增益β主要工艺影响因素的定性分析,对于SOI-LIGBT的设计有一定的借鉴意义。     

On-state analytical modeling of IGBTs with local lifetime control

A two-dimensional on-state analytical model of the insulated gate bipolar transistor (IGBT) with local lifetime control is developed. The model accounts for the effect of local lifetime killing in particular the effective value of the lifetime and the position of the local lifetime control region on the excess carrier distribution in the IGBT during its on-state operation. It is shown that the local lifetime killing in the vicinity of the anode junction causes a reduction in the anode injection efficiency leading to improved on-state/turn-off behavior. The accuracy of the analytical model is verified through numerical simulations carried out using the MEDICI device simulator.     

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.     

Interaction between monolithic, junction-isolated lateralinsulated-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     

A novel high voltage LIGBT with an n-region in p-substrate

A novel 4μm thickness drift region lateral insulated gate bipolar transistor with a floating n-region(NRLIGBT) in p-substrate is proposed.Due to the field modulation from the n-region,the vertical blocking capability is enhanced and the breakdown voltage is improved significantly.Low area cost,high current capability and short turn-off time are achieved because of the high average electric field per micron.Simulation results show that the blocking capability of the new LIGBT increases by about 58%when compared with the conventional LIGBT (C-LIGBT) for the same 100μm drift region length.Furthermore,the turn-off time is shorter than that of the conventional LIGBT for nearly same blocking capability.     

Novel lateral IGBT with n-region controlled anode on SOI substrate

A new lateral insulated-gate bipolar transistor (LIGBT) structure on SOI substrate, called an n-region controlled anode LIGBT (NCA-LIGBT), is proposed and discussed. The n-region controlled anode concept results in fast switch speeds, efficient area usage and effective suppression NDR in forward I-V characteristics. Simulation results of the key parameters (n-region doping concentration, length, thickness and p-base doping concentration) show that the NCA-LIGBT has a good tradeoff between turn-off time and on-state voltage drop. The proposed LIGBT is a novel device for power ICs such as PDP scan driver ICs.     

Charge-control analysis of the COMFET turn-off transient

A quasi-static charge-control analysis of the unique transient turn-off characteristic of the COMFET is developed. The analysis describes the transient behavior in terms of steady ON-state current components that flow in the constituent MOSFET and BJT in the basic COMFET structure. The effects of the expanding depletion region at the cathode and of minority-carrier injection into the anode are properly accounted for. Consequently, the physics underlying the turnoff time is clarified, and device design criteria for shortening it, without considerably degrading the ON-state current conduction capability, are suggested.     

The SINFET: a new high conductance, high switching speed MOS-gated transistor

A new MOS power semiconductor device with a very low on-resistance and a switching speed comparable to conventional n-channel power MOSFETs is described. The fabrication process is similar to that of an n-channel lateral DMOS transistor but with the conventional high-low `ohmic? drain contact replaced by a Schottky contact. In operation, the Schottky contact injects minority carriers to conductivity-modulate the n- drift region, thereby reducing the on-resistance by a factor of about ten compared with those of conventional n-channel power MOSFETs of comparable size and voltage capability. Furthermore, since only a small number of minority carriers are injected, the device speed is comparable to conventional n-channel power MOSFETs.     

Radial confinement in lateral power devices

The aim of this paper is to demonstrate a novel, radial confinement approach to improve the breakdown performance of a lateral power device. The key feature is that the drift region width decreases gradually from the anode to the cathode to achieve charge confinement in the radial direction. As a result, the n⁻ drift region concentration can be increased by a factor of 7 in comparison to a conventional counterpart leading to a lower specific on-state resistance. This technique is applicable to silicon-on-insulator technologies, such as the SOI or SOS, and to high-voltage thin-film transistor technologies on glass. Experimental results from radial diodes fabricated in SOS technology show a blocking capability higher than from those of their conventional counterparts.     

A new lateral anode switched thyristor (LAST) with currentsaturation and low turn-off time

A novel MOS-gate controlled thyristor, entitled lateral anode switched thyristor (LAST), which exhibits a high current saturation and a low turn-off time, is proposed and successfully fabricated. Experimental results show that the new LAST achieves a current saturation capability larger than 1200 A/cm² even at high anode voltages. The forward voltage drop of LAST is 1.2 V at 100 A/cm ² where 10 V was biased to the dual gates. The turn-off time of LAST without any lifetime-control process is 1.5 μs while that of LAST without p⁺ diverter is about 2.9 μs. Our experimental data indicates that the p⁺ diverter successfully diverts holes in the drift region during the turn-off and a turn-off time is considerably decreased in the proposed LAST. The LAST, where any trouble-some parasitic thyristor mechanism is eliminated, completely suppresses a latch-up and increases the maximum controllable current considerably