A new generation of power MOSFET based on the concept of “Floating Islands”

¹ LAAS/CNRS, 7 avenue du Colonel Roche, 31077 Toulouse Cedex 4, France
² MOTOROLA Semiconducteurs SA, avenue du Général Eisenhower, BP 1029, 31023 Toulouse Cedex, France

Corresponding authors: cezac@laas.fr morancho@laas.fr rossel@laas.fr tranduc@laas.fr tpow02@email.sps.mot.com

Received: 7 December 1999
Revised: 1 January 2000
Accepted: 28 April 2000
Published online: 15 June 2000

Abstract

In this paper, a new concept called "Floating Islands diode" (FLI-diode) is proposed: the voltage handling capability of this new diode is assumed by the association of several PN junctions in series. This concept can be applied to any power devices (lateral or vertical). An example of vertical power MOSFET based on this concept is presented here: this new structure, called "FLIMOSFET", exhibits improved on-state resistance performance when compared to the conventional VDMOSFET. For instance, for a breakdown voltage of 900 volts, the theoretical performance are strongly improved in term of specific on-resistance (reduction of about 70% relative to the conventional structure and 40% relative to the silicon limit). Moreover the specific on-resistance theoretical limits of FLIMOSFET family are determined and compared to those of the "Superjunction" MOS Transistor family: this comparison shows the strong interest of the FLIMOSFET in the 200 volts-1000 volts breakdown voltage range.