600V semi-superconjunction MOSFET

New superconjunction (SJ) structure is proposed and demonstrated for the power-switching device with remarkable advantage over conventional SJ structure. An n-doped layer is connected to the bottom of the SJ structure for the proposed structure. It is found with experiment and simulation that the proposed structure shows both the lower on-resistance and the softer recovery of body diode than conventional SJ MOSFET. The fabricated Semi-SJ MOSFETs realize Ron as low as 54 m/spl Omega/cm/sup 2/ (48 m/spl Omega/cm/sup 2/ in calculation) at 690 V breakdown voltage with only half depth of the p-column than the conventional SJ MOSFET. The softness factor of body diode is also improved in the factor of 4.5. The proposed MOSFET is very attractive for H-bridge topology applications such as UPSs and small inverter systems thanks to the low on-resistance and the soft recovery body diode.