A Trench-Field-Plate High-Voltage Power MOSFET

In this article, a trench-field-plate (TFP) high-voltage power MOSFET is proposed. Instead of using a conventional n- drift region, the TFP power MOSFET features benzocyclobutene dielectric in the sidewall of deep trenches in the drift region and a sloped field plate (FP) inside each of the trenches. The TFP structure employed in the drift region modulates the electric field in the OFF-state, resulting in a higher breakdown voltage (BV) than that of conventional power MOSFETs. Simulation results show that the specific ON-resistance of the TFP power MOSFET is approximately one-third that of the conventional power MOSFET and about 50% lower than that of the silicon limit for the same BV. In addition, compared with superjunction devices, the TFP power MOSFET is able to provide better reverse recovery characteristics, including a reduction in peak reverse recovery current (IRRM) and reverse recovery charge (QRR) by 24% and 37%, respectively. Moreover, a pi-n diode employing the TFP structure is fabricated, which is essentially identical to a power MOSFET in the OFF-state, to demonstrate the BV characteristics. The fabricated TFP p-i-n diode has a BV of 522 V, which is 2.3 times that of a conventional p-i-n diode fabricated on the same substrate.