Investigation on the Self-Sustained Oscillation of Superjunction MOSFET Intrinsic Diode

This paper presents the analyses on the self-sustained oscillation of superjunction MOSFET intrinsic diode. At first, the characteristics of the self-sustained oscillation for the superjunction MOSFET intrinsic diode are identified by the double-pulse switching test. The test results show that the self-sustained oscillation with significant self-amplification phenomenon can be triggered during the reverse recovery transient of superjunction MOSFET intrinsic diode. Based on the Sentaurus TCAD simulation, the self-sustained oscillation is reproduced. The simulation results reveal the root cause of the self-sustained oscillation. Due to the snappy reverse recovery of superjunction MOSFET intrinsic diode, the steep slope of diode snap off current can generate high voltage across the common source inductance, which drives the gate-source voltage and turns on the high-side MOSFET. The unexpected MOSFET turn-on can, in return, enhance the steepness of the current slope when the diode snap off. This leads to a positive feedback process and self-sustained oscillation is generated. In the end, based on the theoretical analyses and experimental results, the necessary methods that can suppress the oscillation are presented.