Lateral Power Mosfet For Megahertz-Frequency, High-Density Dc/Dc Converters

Abstract

DC/DC converters to power future CPU cores mandate low-voltage power metal-oxide semiconductor field-effect transistors (MOSFETs) with ultra low on-resistance and gate charge. Conventional vertical trench MOSFETs cannot meet the challenge. In this paper, we introduce an alternative device solution, the large-area lateral power MOSFET with a unique metal interconnect scheme and a chip-scale package. We have designed and fabricated a family of lateral power MOSFETs including a sub-10 V class power MOSFET with a record-low R DS(ON) of 1 mΩ at a gate voltage of 6 V, approximately 50% of the lowest RDS(ON) previously reported. The new device has a total gate charge Qg of 22 nC at 4.5 V and a performance figures of merit of less than 30 mΩ - nC, a 3 × improvement over the state of the art trench MOSFETs. This new MOSFET was used in a 100-W dc/dc converter as the synchronous rectifiers to achieve a 3.5-MHz pulse-width modulation switching frequency, 97%-99% efficiency, and a power density of 970 W/in3. The new lateral MOSEFT technology offers a viable solution for the next-generation, multimegahertz, high-density dc/dc converters for future CPU cores and many other high-performance power management applications. © 2006 IEEE