Floating island and thick bottom oxide trench gate MOSFET (FITMOS) - a 60V ultra low on-resistance novel MOSFET with superior internal body diode

Abstract

A MOSFET structure named FITMOS has been successfully developed that exhibits record-low loss in the 60 volts breakdown voltage range. The breakdown voltage of 64 volts and specific on-resistance of 22m/spl Omega/mm/sup 2/ (V/sub gs/=15V) this performance exceeds the unipolar limit (Chenming Hu, 1979). The device has a body diode with superior reverse recovery characteristics and exhibits an extremely small value for RonQgd. The distinctive feature of this device is the use of floating islands formed by self-alignment and trench gates with a thick oxide layer on the bottoms. This structure can also be used for the terminal portion of the device, so the increase in the number of fabrication processes is less than 5%. Moreover, the rate of nondefective gates in 3-by-4-mm rectangular devices on an 8-inch wafer is at least 98%.