Nonpunch-through Insulated Gate Bipolar Transistor Research Articles

고전압 Non Punch Through IGBT 및 Field Stop IGBT 최적화 설계에 관한 연구

An IGBT (insulated gate bipolar transistor) device has an excellent current-conducting capability. It has been widely employed as a switching device to use in power supplies, converters, solar inverters, and household appliances or the like, designed to handle high power. The aim with IGBT is to meet the requirements for use in ideal power semiconductor devices with a high breakdown voltage, an on-state voltage drop, a high switching speed, and high reliability for power-device applications. In general, the concentration of the drift region decreases when the breakdown voltage increases, but the on-resistance and other characteristics should be reduced to improve the breakdown voltage and on-state voltage drop characteristics by optimizing the design and structure changes. In this paper, using the T-CAD, we designed the NPT-IGBT (non punch-through IGBT) and FS-IGBT (field stop IGBT) and analyzed the electrical characteristics of those devices. Our analysis of the electrical characteristics showed that the FS-IGBT was superior to the NPT-IGBT in terms of the on-state voltage drop.

Improvement of Switching Speed of a 600-V Nonpunch-Through Insulated Gate Bipolar Transistor Using Fast Neutron Irradiation

Abstract Fast neutron irradiation was used to improve the switching speed of a 600-V nonpunch-through insulated gate bipolar transistor. Fast neutron irradiation was carried out at 30-MeV energy in doses of 1 × 10 8 n/cm 2 , 1 × 10 9 n/cm 2 , 1 × 10 10 n/cm 2 , and 1 × 10 11 n/cm 2 . Electrical characteristics such as current–voltage, forward on-state voltage drop, and switching speed of the device were analyzed and compared with those prior to irradiation. The on-state voltage drop of the initial devices prior to irradiation was 2.08 V, which increased to 2.10 V, 2.20 V, 2.3 V, and 2.4 V, respectively, depending on the irradiation dose. This effect arises because of the lattice defects generated by the fast neutrons. In particular, the turnoff delay time was reduced to 92 nanoseconds, 45% of that prior to irradiation, which means there is a substantial improvement in the switching speed of the device.

Experimental study of the anode injection efficiency reduction of 3.3-kV-class NPT-IGBTs due to backside processes

The anode injection efficiency reduction of 3.3-kV-class non-punch-through insulated-gate bipolar transistors (NPT-IGBTs) due to backside processes is experimentally studied through comparing the forward blocking capabilities of the experiments and the theoretical breakdown model in this paper. Wafer lifetimes are measured by a μ-PCD method, and well designed NPT-IGBTs with a final wafer thickness of 500 μm are fabricated. The test results show higher breakdown voltages than the theoretical breakdown model in which anode injection efficiency reduction is not considered. This indicates that anode injection efficiency reduction must be considered in the breakdown model. Furthermore, the parameters related to anode injection efficiency reduction are estimated according to the experimental data.

A prognostic approach for non-punch through and field stop IGBTs

Development of prognostic approaches for insulated gate bipolar transistors (IGBTs) is of interest in order to improve availability, reduce downtime, and prevent failures of power electronics. In this study, a prognostic approach was developed to identify anomalous behavior in non-punch through (NPT) and field stop (FS) IGBTs and predict their remaining useful life. NPT and FS IGBTs were subjected to electrical–thermal stresses until their failure. X-ray analysis performed before and after the stress tests revealed degradation in the die attach. The gate–emitter voltage (VGE), collector–emitter voltage (VCE), collector–emitter current (ICE), and case temperature were monitored in situ during the experiment. The on-state collector–emitter voltage (VCE(ON)) increased and the on-state collector–emitter current (ICE(ON)) decreased during the test. A Mahalanobis distance (MD) approach was implemented using the VCE(ON) and ICE(ON) parameters for anomaly detection. Upon anomaly detection, the particle filter algorithm was triggered to predict the remaining useful life of the IGBT. The system model for the particle filter was obtained by a least squares regression of the VCE(ON) at the mean test temperature. The failure threshold was defined as a 20% increase in VCE(ON). The particle filter approach, developed using the system model based on the VCE(ON), was demonstrated to provide mean time to failure estimates of IGBT remaining useful life with an error of approximately 20% at the time of anomaly detection.

A transient model for insulated gate bipolar transistors (IGBTs)

In this paper, we present a physics-based model for the non punch-through (NPT) insulated gate bipolar transistor (IGBT) during transient turn off period. The steady state part of the model is derived from the solution of the ambipolar diffusion equation in the drift region of the NPT IGBT. The transient component of the model is based on the availability of a newly developed expression for the excess carrier concentration in the base. The transient voltage and current are obtained both numerically and analytically from this model. The theoretical predictions of both approaches are compared with experimental data and found to be in good agreement.

턴-오프 시 PT-IGBT의 애노드 전압 강하 모델링

In this paper, transient characteristics of the Punch Through Insulated Gate Bipolar Transistor (PT-IGBT) have been studied. On the contrary to Non-Punch Through Insulated Gate Bipolar Transistor(NPT-IGBT), it has a buffer layer and reduces switching power loss. It has a simple drive circuit controlled by the gate voltage of the MOSFET and low on-state resistance of the bipolar junction transistor. The transient characteristics of the PT-IGBT have been analyzed analytically. Excess minority carrier and charge distribution in active base region, the rate of anode voltage with time are expressed analytically by adding the influence of buffer layer. The experimental data is obtained from manufacturer. The theoretical predictions of the analysis have been compared with the experimental data obtained from the measurement of a device(600 V, 15 A) and show good agreement.

Experimental Investigation of Pulsed-Laser-Annealed Ultralow-Conduction-Loss 600-V Nonpunchthrough Insulated-Gate Bipolar Transistors

Using a double-pulsed-laser-annealing process, an ultralow-conduction-loss 600-V nonpunchthrough (NPT) insulated-gate bipolar transistor (IGBT) is realized with a highly activated anode structure. This ultralow conduction loss has not been achievable prior to this due to the limited thermal budget in conventional annealing processes. The laser-annealed NPT IGBT demonstrates the ON-state voltage drop from 1.17 to 1.49 V at the collector current density of 165 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which implies that a wide range of tradeoff performance between the conduction and switching losses can be generated according to various requirements of applications. This brief presents the characteristics of the laser-annealed NPT IGBT, depending on the splits of laser-irradiation conditions, and the implications of the low thermal-budget annealing process.

Rated Overload Characteristics of IGBTs for Low-Voltage and High-Voltage Devices

By a vertical shrink of the nonpunchthrough insulated gate bipolar transistor (NPT IGBT) to a structure with a thin n-base and a low-doped field stop layer a new IGBT can be realized with drastically reduced overall losses. In particular, the combination of the field stop concept with the trench transistor cell results in an almost ideal carrier concentration for a device with minimum on-state voltage and lowest switching losses. This concept has been developed for IGBTs and diodes from 600 V up to 6.5 kV. While the tradeoff behavior (on-state voltage V/sub CEsat/ or V/sub F/ to tail charge) and the overall ruggedness (short circuit, positive temperature coefficient in V/sub CEsat/, temperature independence in tail charge, etc.) is independent of voltage and current ratings the switching characteristics of the lower voltage parts (blocking voltage V/sub Br/<2 kV) is different in handling to the high-voltage transistors (V/sub Br/>2kV). With the HE-EMCON diode and the new field stop NPT IGBT up to 1700 V there is almost no limitation in the switching behavior, however, there are some considerations-a certain value in the external gate resistor has to be taken. High-voltage parts usually have lower current density compared to low-voltage transistors so that the "dynamic" electrical field strength is more critical in high-voltage diodes and IGBTs.

A new punch-through IGBT having a new n-buffer layer

Insulated gate bipolar transistors (IGBTs) based on the non-punch-through (NPT) design approach exhibit excellent safe operating area (SOA) and short-circuit endurance, a positive temperature coefficient of on-state voltage over the operating current range, and low silicon cost. These merits have supported the development and commercialization of NPT IGBTs above the 1200-V class. However, the need for quite thin silicon to obtain competitive on-state losses at 1200-V and below classes has hindered the use of the NPT approach in this area. A new punch-through (PT) IGBT has been developed which exhibits the merits of the NPT approach, rugged SOA and short-circuit endurance, while also having a better tradeoff relation between on-state voltage and turn-off loss than either existing NPT or third-generation PT IGBTs.

Analysis of Temperature Behavior of the NPT-IGBT's Characteristics

An analytical model for calculating the forward voltage of a conventional NPT-IGBT (Non-Punch Through Insulated Gate Bipolar Transistor) is presented, taking into account decrease of the current densities in the epi layer near the cathode junction. Simulation results of the temperature dependent forward voltage and emitter injection efficiency for an IGBT with blocking capability of 1700 V are shown to support the model developed with temperature dependent mobilities. The present model allows a good agreement with the simulation results within 10% in error.

Evaluation of actively clamped resonant link inverter for low-output harmonic distortion high-power-density power converters

The suitability of a soft-switched actively clamped resonant DC-link (ACRDCL) inverter for low-output harmonic distortion/high-power-density power conversion is evaluated. Modulation and control techniques for achieving low-output harmonic distortion are described. Performance and power density of the ACRDCL inverter are maximized through the optimal design of the clamp circuit, resonant components, and output filter components. The ACRDCL inverter simulation and design are validated experimentally. For the same output kilovoltamperes, efficiency and harmonic performance as the ACRDCL inverter, hard-switched designs are compared. Methods to increase the power density of the ACRDCL are proposed, including the use of recently developed nonpunchthrough insulated gate bipolar transistors.

Thermal stability of IGBT high-frequency operation

Thermal stability of high-frequency insulated gate bipolar transistor (IGBT) operation is studied in this paper. The nonpunch-through IGBT is found to be stable when operated within its rated temperature. Thermal runaway occurs with punch-through IGBTs at temperatures below the maximum junction temperature when operated at high frequency at well below rated current, with snubber or soft-switching circuits.

Maximum operating junction temperature of PT andNPT IGBTs

The maximum operating junction temperatures of punch-through (PT) and non-punch-through (NPT) insulated gate bipolar transistors (IGBTs) at high frequency are investigated experimentally. The maximum junction temperature of the PT IGBT varies with circuit conditions and is in the range 115–170°C. The NPT IGBT can typically operate at junction temperatures up to 230°C in various circuits.

Zero voltage switching behavior of punchthrough and nonpunchthrough insulated gate bipolar transistors (IGBT's)

The switching performance of silicon (Si) punchthrough (PT) and a nonpunchthrough (NPT) insulated gate bipolar transistors (IGBT's) is compared under zero voltage switching (ZVS), both experimentally and using two-dimensional (2-D) device simulator. Extensive experimental results are obtained for both the devices under ZVS turn-on and turn-off, under a wide range of operating conditions. The switching performance is then analyzed using a finite element based device simulator which shows good agreement with the measured data. The device simulator is used to study the turn-on and turn-off behavior of the two devices. It is shown that, although both the devices behave similarly during ZVS turn-on, with the characteristic forward recovery voltage spike due to conductivity modulation lag, the turn-off wave forms during ZVS are different for the two devices. Punchthrough device shows a tail bump during turn-off as opposed to a tail plateau shown by nonpunch-though device. The device simulator is used to study this difference in turn-off behavior. The simulator is also used to analyze the characteristic ZVS turn-on voltage wave form in more detail. Temperature dependence of the static and ZVS characteristics is also studied, for both the devices, and it is pointed out that turnoff of an NPT-IGBT is much less dependent on temperature as opposed to that of a PT-IGBT.

A study of the internal device dynamics of punch-through and nonpunch-through IGBTs under zero-current switching

The effective use of power insulated gate bipolar transistors (IGBTs) requires a good understanding of their internal device physics. This understanding is essential for the optimal interaction among the IGBTs, their snubber elements and the power circuit in which the IGBTs operate. As switching frequencies are pushed to higher values, switching loss reduction becomes an essential part of the design and optimization process. Soft switching techniques such as zero-voltage switching (ZVS) and zero-current switching (ZCS) are widely used for this purpose. This study provides an insight into the internal dynamic behavior of IGBTs under zero-current switching. The latter is accomplished through mixed-mode simulation, providing the necessary insight for the improvement of circuit and device performance. In particular, the authors have analyzed the behavior of the negative current in nonpunch-through (NPT) devices after the first zero-current crossing and the effect of the turn-off delay on the tail current. They have also experimentally characterized punch-through (PT) and NPT IGBTs to confirm the insights provided by the mixed-mode simulation.

Switching dynamics of IGBTs in soft-switching converters

Next generation of power semiconductor devices will be designed and optimized to meet the specific application requirements. Mixed-mode simulations are used to study the carrier dynamics in punch-through and nonpunch-through Insulated Gate Bipolar Transistor (IGBT) structures during soft- and hard-switching conditions. The simulation results are shown to qualitatively predict the measured bump in the tail current with varying output dv/dt conditions and excessive forward conduction voltage under varying di/dt conditions. A new physical effect termed modulation lag is shown to occur during turn-on under soft-switching conditions. This mechanism is caused by the fact that minority carrier injection into the base of the bipolar transistor significantly lags behind the rate at which drift region conductivity can be modulated. The proposed phenomenon leads to an inductive effect that results in dynamic voltage saturation during turn-on and causes excessive forward voltage drop. >