Novel Termination Structure Eliminating Bipolar Degradation of SBD-embedded SiC-MOSFET

To suppress bipolar current from the peripheral p-type well region (p-well) of an SBD-embedded SiC-MOSFET, a novel termination structure named capacitively coupled termination (CCT) is demonstrated. CCT, where only a large n-type region formed within the peripheral p-well is connected to the source electrode, enables to suppress bipolar current from the peripheral p-well because there is no ohmic contact pass from the source electrode to the p-well. Suppression of bipolar current from the peripheral p-well of an SBD-embedded SiC-MOSFET with CCT is verified by electro-luminescence (EL) measurement. Sufficient avalanche and dV/dt ruggedness of an SBD-embedded SiC-MOSFET with CCT are also obtained owing to the significantly low gain of the parasitic bipolar transistor and large capacitance of the pn-diode consisting of the n-type region and the peripheral p-well. By applying CCT, the SBD-embedded SiC-MOSFET, which is free from bipolar degradation in whole area of the chip, has been achieved.