Towards Understanding the Physics of Gate Switching Instability in Silicon Carbide MOSFETs
Maximilian W. Feil, Katja Waschneck, H. Reisinger, Judith Berens, Thomas Aichinger, Paul Salmen, Gerald Rescher, Wolfgang Gustin, Tibor Grasser
Abstract
Bias temperature instability (BTI) is a well-investigated degradation mechanism in technologies based on silicon, gallium nitride, or silicon carbide (SiC). Essentially, it leads to a drift in the threshold voltage and to a reduction in mobility after application of a gate bias, and becomes worse at elevated temperatures. However, as discovered recently, the threshold voltage drift of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) has different properties than those known from BTI when the gate terminal of the device is switched in a bipolar mode. This new degradation mechanism has recently been termed gate switching instability (GSI). To further understand this degradation mechanism and the underlying physics, we have used pre- and post-stress impedance characterization and in-situ ultra-fast threshold voltage measurements. Most importantly, we show that the gate switching leads to the creation of fast, acceptor-like interface defects that lead to a shift in threshold voltage, and hence appear to be responsible for GSI.