Mario Netzel

Application of carrier lifetime control by irradiation to 1.2kV NPT IGBTs

Device simulation, based on an extended recombination model and previously determined recombination center parameters, serves as design tool for carrier-lifetime controlled, state-of-the-art 1.2kV NPT IGBTs. Homogenous and local recombination center profiles are considered. The sensitivity of important device characteristics to the type of the recombination center profile is investigated in simulation and experiment. A possible application, the improvement of reverse leakage properties of reverse blocking capable NPT IGBTs, is discussed.

The plasma extraction transit-time oscillation in bipolar power Devices-Mechanism,EMC effects, and prevention

Under certain conditions, radio frequency (RF) oscillations may occur during the turn off of bipolar power devices. These oscillations are related to the plasma extraction transit time (PETT) effect. The mechanism of the oscillation and the complex dependencies for the occurrence of the effect are discussed in this paper. Three-dimensional electromagnetic compatibility (EMC) simulation is used to investigate modifications of the power module layout that shift its resonance point and therefore, effectively suppress the unwanted RF oscillations. EMC measurements and examples of failures of power electronic equipment related to the occurrence of PETT oscillations demonstrate the necessity for suppressing this effect.

PT-IGBT and freewheeling diode for 3.3 kV using lifetime control techniques and low-efficiency emitters

The adjustment of emitter efficiency by variation of doping profiles or application of lifetime control techniques such as irradiation of electrons and helium are two generally recognized concepts for the improvement of power device characteristics. In this work both concepts were studied by use of device simulation for the development of an IGBT and freewheeling diode chipset for 3.3 kV. Simulations were performed using an extended recombination model and recombination center data taken from measurements at different irradiated devices. Finally, this lead to the manufacturing of an IGBT using low-emitter efficiency and an irradiated freewheeling diode. The experimental results are in good accordance with the previously performed simulations and give evidence of the capabilities of present device simulation tools.

Comparison of different cell concepts for 1200 V NPT-IGBTs

IGBTs are relatively new power devices combining bipolar and unipolar properties. In this work we carried out theoretical investigations of IGBT cells with different concepts and properties using the two-dimensional device simulator ToSCA and the process simulation system DIOS. The investigations are done at three different cell types: a common planer gate cell with different p-base depths, a cell with double implanted emitter and a cell with a trench gate structure. For the realization of devices with low static losses and a high degree of ruggedness an advanced cell concept is necessary. For ruggedness modelling of the IGBTs the calculation of the short circuit current is used. It is shown, that the concept of IGBTs with double implanted emitter is a good alternative to the trench IGBT concept. An improvement of the short circuit behaviour of this device is possible in addition with lower static losses.