Capacitive behaviour in Super Junction trench MOSFET devices

This paper exploits for the first time the capacitive behaviour of Super Junction (SJ) Trench Power MOSFETs as a characterization method to determine their Charge Balance (CB). Differently from blocking voltage methods, the capacitive method allows the CB extraction in 800 V SJ devices by using low voltage systems (<;30 V) to extract the drain-source capacitance (C_ds) in function of the drain-source voltage (V_ds). Hence, the device-under-test is never stressed in avalanche, avoiding device degradation and/or destruction. The correlation between the minimum C_ds value at 25 V and the optimum CB is demonstrated by TCAD simulations and measurements. As a result, the highest breakdown voltage (V_bd), corresponding to the optimum CB, is determined by measuring C_ds at 25 V. Moreover, the maximum V_ds pinch voltage (V_pinch) exhibits a maximum value when C_ds at 25 V is minimum, thus also being an interesting parameter to monitor.