True Origin of Gate Ringing in Superjunction MOSFETs: Device View

As superjunction devices are scaled down to smaller dimensions, the gate ringing becomes more prominent in dynamic switching. The exact origin of superjunction MOSFET's gate ringing has not been so far identified as the conventional three-terminal measurement method cannot capture the dynamic behavior of the device, in particular the redistribution of charge between the different internal capacitive components in the superjunction structure. In this article, it is found that the gate ringing is highly related to the input capacitance. Specifically, by employing a TCAD model with a split gate method, the gate-to-source (C
_GS
) and gate-to-drain (C
_GD
) current are investigated during the dynamic transitions. The gate ringing is highly dependent on sum of the input capacitances (C
_GS
+ C
_GD
) for the turn-on. In the case of the turn-off, however, the gate ringing is affected by the ratio of the input capacitances (C
_GD
/C
_GS
) and a lower CGS is desirable for a low gate oscillation.