New results of 1.7 kV and 6.5 kV single chip IGBTs under repetitive SC events are presented and compared with the results of 1.2 kV IGBTs. An observed current filament pattern as well as the filament lateral distance in 1.7 kV IGBTs are compared with the results of 1.2 kV IGBTs. Device simulation was performed by designing 2D as well as 3D IGBT structures to explain the trend of the filament lateral distance as a function of different voltage class. The current filament pattern produced with the help of 3D simulation was compared with the observed current filaments from experimental results. Possible reasons for the mismatch between measurement and 3D-simulation results are discussed.

This work investigates modification on the top-side aluminium (Al) metallisation of 1.2 kV insulated-gate bipolar transistors (IGBTs) under repetitive short-circuit (SC) type-I measurements for two different parasitic inductances of 45 and 380 nH. The presence of current-density filaments starting at the collector side during SC leads to local temperature increase of the emitter metallisation and thus to modification of the top Al surface in the pattern of the current filaments. Here, two techniques thermo-reflectance microscopy, which can detect the surface temperature during repetitive short circuits directly and Al modifications after repetitive SC with analysis under optical microscope after the test have been considered. At 45 nH, with different DC-link voltages from 300 to 600 V, the Al modification pattern is non-uniform and it becomes uniform for V-DC>600 V. However, for 380 nH parasitic inductance and for DC-link voltages 300 and 400 V, the Al reconstruction shows a non-uniform pattern and becomes uniform for V-DC >= 500 V. The SC simulations were performed by using a simplified front-side IGBT structure using variable DC-link voltages and inductances to reproduce the filament behaviour.

This work shows an investigation of repetitive Short-Circuit (SC) operation of 1200 V-15 A IGBT far above the Short-Circuit Safe Operating Area (SC-SOA). The goal behind this work was to perform repetitive SC tests with test conditions provoking the formation of current filaments in the short-circuit pulse, which leads to a nonhomogeneous heating but not to a destruction. The target was to investigate unknown physical effects that lead to device degradation during the repetitive SC test. The IGBT device shows strong deterioration in its blocking characteristic after it was subjected to several 1000 SC pulses at extremely high SC levels.

This work investigates the relation of the two destruction modes, the so-called energy destruction and the electrical destruction, during short-circuit operation of an Insulated Gate Bipolar Transistor (IGBT). The critical energy as a function of the short circuit current reveals a kink indicating the transition between two different failure modes. The failure signatures show that energy destruction takes place at lower currents and electrical destruction at higher currents. This supports the hypothesis that there is a huge current range with non-destructive filaments at low dc-link voltages. For both destruction mechanisms, the final failure occurs locally. For the energy destruction, the current crowding happens very late during the runaway itself, whereas in the case of an electrical destruction, filaments are formed mainly by an electrical mechanism leading to a stronger local self-heating. Both mechanisms take place far above the safe operating area of the chip.

In this paper, we demonstrate for the first time experimentally measured current filaments in IGBTs under repetitive Short-Circuit (SC) events. These current filaments were discovered with the help of Thermo-Reflectance Microscopy (TRM). The destruction current as function of the applied collector-emitter voltage (V-CE) was determined for two differently wire-bonded 15A-1200V IGBT chips. The repetitive SC events in combination with TRM measurement indicate a wide range of non-destructive current filaments at different VCE. Similar filament formation under short-circuit conditions were observed in supporting TCAD device simulations based on multi-cell IGBT structure. These filaments have similar dimensions to the current filaments measured by TRM.

In this work, we introduce a new collector IGBT structure that shows a huge improvement of the short-circuit (SC) ruggedness without deteriorating the static and dynamic losses of the device. The Injection Enhanced Floating Emitter (IEFE) concept enhances the emitter efficiency at the collector side by means of higher hole current injection which increases the bipolar current gain of the IGBT device. The simulation results indicate that the proposed structure can suppress a SC turn-off failure due to an electrical current crowding to a considerable extent. The critical pulse width to avoid thermal runaway of the leakage current after the SC event can be increased.

To understand the functioning of the gallium arsenide (GaAs) pin diode and to allow predictive simulations it is essential to have knowledge of the underlying physics. The GaAs pin diode is described with the help of experimental and simulation results. The static characteristics of 15 A – 600 V GaAs pin diodes were measured at ambient and elevated temperature. A quasi-one-dimensional simulation model was designed and compared with experimentally measured results. The surge current behaviour was investigated for GaAs pin diodes at two different temperatures. A thermal simulation was performed to give an overview over temperature distribution inside the GaAs pin diode. Several important physical device models and various parametric data were incorporated for theoretical investigation of these diodes. Good agreement between experimental and simulated results of GaAs pin diodes was found at all temperatures.

High measurement accuracy is the basis for a precise determination of the junction temperature Tj. Temperature measurement can be performed by means of temperature sensitive parameters (TSP) using the VCE(T)-method, however, internal semiconductor processes like the removal of stored charge in bipolar devices have to be respected. The aim of this work is to determine the earliest time point of accurate measurement tMD after switching off, as well as dependencies on device voltage classes and applied battery voltage. Measurement results are confirmed by performing the simulation with Sentaurus TCAD. Dependencies of delay tMD on temperature, applied measurement current and battery voltage are demonstrated for IGBT and silicon diode.

This paper discusses power cycling as a method to evaluate the reliability of interconnections in power electronic devices. While the approach proved a reliable tool for investigating the potential of improvement for alternative interconnect technologies and rejecting design flaws, precise estimations about lifetime in the field are still challenging. Many questions are still in discussion, such as ultra-high cycle fatigue, applicability of Miner's rule, or the influence of on-time and cross-effects with mechanical shocks or humidity. This leaves application engineers with a blurred safety margin. In the following basic considerations of power cycling are described. The introduction shows two applications with different load profiles. Section 2 explains methods of temperature measurement. In Section 3 theoretical requirements for measurement accuracy are given, the obstacle minimal measurement delay and possible workarounds are evaluated. Finally aging effects and their acceleration in different devices are discussed in Section 4. In the conclusion suggestions for power cycling methods and a revision of the end-of-life criteria are made.

This paper discusses the limitation in measurement accuracy of junction temperature measurements of bipolar devices. A limiting factor the measurement delay, caused by slow removal of charge carriers, was investigated by single pulse measurements and evaluated by simulations. A minimal measurement delay of 650μs was found for a 6,5kV IGBT at high temperature.

This paper demonstrates the detailed work on high voltage IGBTs using simulations and experiments. The current-voltage characteristics were measured up to the break through point in forward bias operating region at two different temperatures for a 50 A/4.5 kV rated IGBT chip. The experimentally measured data were in good agreement with the simulation results. It was also shown that the IGBTs are able to clamp high collector-emitter voltages although a low gate turn-off resistor in combination with a high parasitic inductance was applied. Uniform 4-cell and 8-cell IGBT models were created into the TCAD device simulator to conduct an investigation. An engendered filamentation behaviour during short-circuit turn-off was briefly reviewed using isothermal as well as thermal simulations and semiconductor approaches for development of filaments. The current filament inside the active cells of the IGBT is considered as one of the possible destruction mechanism for the device failure.

Measurements show that the IGBT is able to clamp the collector-emitter voltage to a certain value at short-circuit turn-off despite a very low gate turn-off resistor in combination with a high parasitic inductance is applied. The IGBT itself reduces the turn-off diC/dt by avalanche injection. However, device destructions during fast turn-off were observed which cannot be linked with an overvoltage failure mode. Measurements and semiconductor simulations of high-voltage IGBTs explain the self-clamping mechanism in detail. Possible failures which can be connected with filamentation processes are described. Options for improving the IGBT robustness during short-circuit turn-off are discussed.

This paper describes how to measure the complete output characteristic of a high-voltage IGBT non-destructively up to the breakdown point and beyond. Hereby, a deep knowledge of the IGBT behaviour at high voltages and saturation currents is gained. To construct the complete characteristic, short-circuit and curve-tracer measurements are combined. The results are compared and recapitulated with semiconductor simulations of IGBT models fitted to experimental characteristics.