A new generation of power lateral and vertical floating islands MOS structures

In this paper, new vertical and lateral MOS structures are proposed, in whi ch pf layers called floating islands are located in the drift region. These new structures, called "FLIMOS" (floating islands metal-oxide semiconducto r) transistors, are based on the FLI-diode concept in which the voltage han dling capability is obtained by many PN junctions in series instead of the conventional diode, where the breakdown voltage is supported by only one PN junction. In the medium voltage range (200-1000 V), the on-state performan ce of vertical FLIMOSFET is strongly improved when compared to the conventi onal MOSFET. For instance, for a 900-V vertical FLIMOSFET, a reduction of t he specific on-resistance of about 70% relative to the conventional structu re and of 40% relative to the silicon limit is observed. But for a 180-V la teral FLIMOSFET, a reduction of 28% relative to the conventional structure is observed, which is not a very significant improvement when compared to m edium voltage vertical devices. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.