Investigation of long-term drift effects of SiC MOSFETs under power cycling like gate conditions

Conference: CIPS 2022 - 12th International Conference on Integrated Power Electronics Systems
03/15/2022 - 03/17/2022 at Berlin, Germany

Proceedings: ETG-Fb. 165: CIPS 2022

Pages: 6Language: englishTyp: PDF

Authors:
Kempiak, Carsten; Lindemann, Andreas (Otto-von-Guericke-University, Magdeburg, Germany)

Abstract:
Power cycling tests are an established routine in the qualification process of power electronic devices. New challenges however evolve from the application to wide band gap devices: In case of SiC MOSFETs, the threshold voltage Vth is continuously shifting during the test execution affecting the on-state resistance RDS;on and thus the induced thermomechanical stress as well as a reliable failure indication. The impact of such drift effects – solely caused by the gate bias – is investigated in this work by applying similar gate conditions as during a power cycling test, but at constant temperature without load current flow. This way, any influence of package degradations can be excluded. A test setup was developed for this investigation, allowing the in-line monitoring of DeltaVth and DeltaRDS;on. The impact of the voltage class, the gate turn-off voltage and the temperature are investigated and discussed. A modelling approach and a compensation concept are proposed in addition, revealing that the proportion of the channel resistance on RDS;on is the decisive parameter when evaluating the impact of DeltaVth on DeltaRDS;on and that an additional drift effect – not covered by DeltaVth – can occur under bipolar switching conditions.