Reverse recovery behavior of 100V-class trench field plate power MOSFETs by pitch shrinkage for DC- DC converters

Abstract Cell pitch shrinking is a key technology for reducing on-resistance in trench field plate power MOSFETs. While the estimation methods for on-resistance and capacitance are well established, the reverse recovery charge (Q rr ) behavior is more complex. The purpose of this study is to clarify how the reverse recovery characteristics of the parasitic body diode change under a low on-resistance design, discussing underlying mechanisms and design implications. We investigate 100 V-class devices through both experimental measurements and simulations. Increased epitaxial doping resulting from pitch reduction decreases excess carrier concentration, reducing Q rr and producing a soft recovery waveform. Although soft recovery suppresses oscillations caused by parasitic inductance, it can induce current ringing below zero amps, thereby increasing power loss. We further evaluate losses when these devices are used in a non-isolated DC-DC converter. While soft recovery is generally considered effective for noise suppression, our calculations reveal that it can have a negative impact on power loss.