Technological realization of low on-resistance FLYMOS/spl trade/ transistors dedicated to automotive applications

The present 14 Volts automotive electrical system will soon become 42 Volts. For these future automotive applications, development of 80 Volts power MOSFETs exhibiting low on-resistance is desired. The "floating island" MOSFET (FLIMOSFET) is one of the new candidates to break the silicon limit, which is the "specific on-resistance / breakdown voltage" trade-off limit of conventional power MOSFETs. In this paper, the "floating island" concept has been implemented on silicon: new vertical N-channel FLIMOSFETs (FLYMOStrade) dedicated to automotive applications (below 100 Volts) have been fabricated for the first time, using two steps epitaxy process. Experimental results show that FLYMOStrade transistors exhibit lower breakdown voltages than what was expected by simulations (maximum of 73 Volts) but also improved specific on-resistances compared to the conventional VDMOSFET (33% improvement of the specific on-resistance for the same breakdown voltage). In other words, in terms of "specific on-resistance / breakdown voltage" trade-off, the FLYMOStrade is one of the best MOS devices in low voltage applications. These measurements validate the "floating island" concept and the efficiency of the original edge cell that is used in the FLYMOStrade technology