Alexander Philippou

RCDC-IGBT study for low-voltage applications

The desaturation and charge recovery behavior for 1200-V RC-IGBTs with diode control is investigated. The low thickness of the drift-region of modern 1200-V IGBTs results in significantly reduced time constants of the diode-control feature. While a low desaturation time constant is well acceptable, the recovery time constant becomes critical when compared to typical locking time requirements of common gate driver units. The impact of different locking times on the overall performance is discussed and a novel device concept for RC-IGBTs is presented which overcomes this issue. The FWD-mode of the novel RC-IGBT is desaturated at a gate-emitter voltage of 0 V allowing for the first time a desaturation pulse pattern which may disregard the locking time requirements of the driving-unit.

Automated vertical design optimization of a 1200V IGBT

Many important performance parameters in an IGBT power semiconductor are heavily affected by its field-stop profile, its device thickness and its collector-side p-doping concentration. To find the optimum combination of these design parameters is of high importance for an optimal IGBT design. The optimization criteria include low switching and on-state losses as well as limited maximum overshoot voltage and modest current and voltage rise and fall times. This work focusses on an automated global optimization scheme to solve this issue. The method and definition of a proper target function are briefly explained. Finally, design optimizations found under different constraints are discussed.

A new sub-micron trench cell concept in ultrathin wafer technology for next generation 1200 V IGBTs

The overall growing trend towards electrification and, at the same time, the urgent need to minimize energy consumption strongly requires higher energy efficiency in power electronics. We present a new technology concept for next generation 1200 V IGBTs with vastly reduced overall power losses using an optimized micro-pattern trench (MPT) cell design with sub-micron mesas. Further important parameters relevant for inverters driving electrical machines were optimized, including turn-off softness, dv/dt-controllability, and short circuit capability, providing a right-fit solution to customer requirements.

Automated vertical design co-optimization of a 1200V IGBT and diode

In this work, we concentrate on extending our optimization method for IGBTs [1] in drives applications by incorporating diode parameters in addition to IGBT parameters. For this purpose, the fabrication process of the diode, including a platinum diffusion and its parameters for lifetime adjustment [2], was added to the optimization loop. Consequently, the simulation of an IGBT turn-on event in the optimization loop was required.

Critical overcurrent turn-off close to IGBT current saturation

A failure mechanism in the edge termination of a 1200V IGBT during overcurrent turn-off is studied with simulations and verified by experiments. The position of the destruction in the experiment can be correlated to the formation of a critical filament in the simulation. The destruction mechanism is investigated in detail. It is only observed if the IGBT enters its current saturation regime. I.e., the IGBT survives a turn-off from the same current level for an increased gate voltage. It is shown that an IGBT provided with a properly-designed High Dynamic Ruggedness (HDR) edge termination structure [1] is no longer susceptible to the destruction mechanism.