Over 1000V semi-superjunction MOSFET with ultra-low on-resistance below the Si-limit

Si-MOSFETs with the breakdown voltage of over 1000 V were demonstrated, for the first time, realizing low on-resistance below the theoretical Si-limit. The fabricated MOSFETs have semi-superjunction (SemiSJ) structure, which is the combination of superjunction (SJ) structure and n-bottom assisted layer (BAL). The SemiSJ MOSFETs realize both the high breakdown voltage of 1100 and 1400 V and the low on-resistance of 54 and 163 mΩcm², respectively. The fabrication process for the high voltage SemiSJ-MOSFET was completely equivalent to a 600-V class SJ-MOSFET process, which implies that a single optimized process for forming SJ structure for 600 V-class MOSFET can be used for a wide voltage range extending up to 1200 V MOSFET. These results show the possibility of new Si power-MOSFET with higher application voltage range.