Forward-voltage-tunable schottky-integrated trench MOSFETs

We presented the 4-photo-mask schottky-integrated trench MOSFETs. Traditionally monolithic schottky-integrated MOSFETs are composed of two regions: one is MOSFET cells, the other is schottky cells. However, it needs additional mask and processes for schottky structures. 30V schottky-integrated trench MOSFETs by self-aligned schottky into every MOS cell was successfully fabricated in this paper. Trench mask was utilized for body implant and trench etching. Forward voltage (V_F) is tunable by tilt angle implant after contact etching. Furthermore, UIS (unclamped Inductive Switching) ability was also improved comparing to conventional trench MOSFETs. Finally, relationship between V_F, Idss (drain leakage current), and Qrr (reverse recovery charge) could be optimized for improving the efficiency for DC-DC converters.