Crosstalk Induced Shoot-Through in BTI-Stressed Symmetrical & Asymmetrical Double-Trench SiC Power MOSFETs

Abstract

In this paper, the crosstalk-induced shoot-through current and induced gate voltage of SiC planar MOSFETs, SiC symmetrical double-trench MOSFETs and SiC asymmetrical double-trench MOSFETs is investigated on a half-bridge circuit to analyse the impact of temperature, drain-source voltage switching rate, gate resistance and load current level on crosstalk-induced properties of different SiC MOSFET structures. It shows that due to the smaller gate-source capacitance, the two double-trench MOSFETs exhibit higher induced gate voltage during crosstalk with the same external gate resistance, which together with the higher transconductance, yield higher shoot-through current than the planar MOSFET. Accordingly, their shoot-through current decreases with increasing of the load current while the planar MOSFET exhibits an opposite trend. The different trend of shoot-through current with temperature on DUTs reveals that the crosstalk in different device structures are dominated by different mechanisms, i.e. threshold voltage and channel mobility with the gate-source capacitance influencing the amplitude. Impact of bias temperature instability with positive and negative gate stressing is measured with a range of stress and recover periods at temperateness ranging between 25 °C to 175 °C. These measurements show that the peak shoot-through correlates with the threshold drift, though with less sensitivity for SiC symmetrical and asymmetrical double-trench MOSFETs compared with the planar SiC MOSFET where the inter-dependence is pronounced. A model is developed for the induced gate voltage and shoot-through current during crosstalk with channel current considered. The comparison of the model results with measurement confirms its capability to predict crosstalk in different MOSFET structures.

Keywords

• MOSFET
• silicon carbide
• crosstalk
• double-trench
• Bias temperature instability