Abstract
Threshold voltage ( V TH) shift due to bias temperature instability (BTI) is a well-known problem in SiC mosfet s that occurs due to oxide traps in the SiC/SiO2 gate interface. The reduced band offsets and increased interface/fixed oxide traps in SiC mosfet s makes this a more critical problem compared to silicon. Before qualification, power devices are subjected to gate bias stress tests after which V TH shift is monitored. However, some recovery occurs between the end of the stress and V TH characterization, thereby potentially underestimating the extent of the problem. In applications where the SiC mosfet module is turned off with a negative bias at high temperature, if the V TH shift is severe enough, there may be electrothermal failure due to current crowding since parallel devices lose synchronization during turn- on . In this paper, a novel method that uses the forward voltage of the body diode during reverse conduction of a small sensing current is introduced as a technique for monitoring V TH shift and recovery due to BTI. This non-invasive method exploits the increased body effect that is peculiar to SiC mosfet s due to the higher body diode forward voltage. With the proposed method, it is possible to non-invasively assess V TH shift dynamically during BTI characterization tests.
Highlights
A Novel Non-Intrusive Technique for BTI Characterization in SiC MOSFETsAbstract— Threshold voltage (VTH) shift due to Bias Temperature Instability (BTI) is a well-known problem in SiC MOSFETs that occurs due to oxide traps in the SiC/SiO2 gate interface
Bias Temperature Instability (BTI) is a well-known reliability hazard in SiC MOSFETs
This paper has introduced a novel method of monitoring threshold shift from BTI using the body effect in SiC power MOSFETs
Summary
Abstract— Threshold voltage (VTH) shift due to Bias Temperature Instability (BTI) is a well-known problem in SiC MOSFETs that occurs due to oxide traps in the SiC/SiO2 gate interface. A novel method that uses the forward voltage of the body diode during reverse conduction of a small sensing current is introduced as a technique for monitoring VTH shift and recovery due to BTI. This non-invasive method exploits the increased body effect that is peculiar to SiC MOSFETs due to the higher body diode forward voltage. It is possible to non-invasively assess VTH shift dynamically during BTI characterization tests
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