Schottky Source LDMOS - Electrical SOA Improvement through BJT Suppression

No-Snapback LDMOS Using Adaptive RESURF and Hybrid Source for Ideal SOA

“…14 Thus, a lower resistance is seen by the holes, and an enhancement to the electrical SOA can be expected. Previously, this resistance reduction had been in the range 21%....58% [4]. The combination of these two mechanisms, reduced body resistance and reduced electron injection from the source, are key elements in suppressing the parasitic bipolar which fundamentally changes the nature of the failure mechanism compared to a conventional LDMOS.…”

“…The purpose of this additional well is to mitigate the high electric field that forms at the edge of the drain active region when the space charge in the drift region is compensated by electrons injected from the channel and therefore the space charge region boundary moves to the drain active edge. The benefit of this on the e-SOA have been described elsewhere [9] and this change has been instrumental in the improved performance compared to the first Schottky LDMOS results [4]. The physical mechanisms behind this will be discussed later in section V. The combination of the adaptive drain region, the Hybrid Source, optimal body and drift region design enable electrical operation at high trigger currents and voltages across all gate bias conditions.…”

“…Thus, a smaller base-emitter voltage is attained in response to hole flow from the drainbody breakdown and triggering of the BJT is postponed. An alternative method is to use a Hybrid Source [4], Fig. 2.…”

“…An alternative, novel approach is to utilize a Hybrid Source LDMOS architecture to provide unparalleled bipolar suppression. First introduced at ISPSD 2020 [4], this concept has been proven as not only a viable substitute for the highly doped body, but an even better complementary ESD solution when used together.…”

“…B.Toner is with X-Fab Sarawak Sdn. Bhd., Malaysia(e-mail: brendan.toner@xfab.com) R. Granzner, M. Frank and S. Eisenbrandt are with X-FAB Semiconductor Foundries GmbH, Erfurt, Germany L. Steinbeck is with X-FAB Dresden GmbH & Co. KG, Dresden, Germany G. M. Dolny, W. R. Richards, and T. J. Johnson are with Silicet Inc, Raleigh NC 27516 USA Hybrid Source LDMOS [4]. An improved overall architecture is presented to further enhance the performance, culminating in more than tenfold improvement of the BJT trigger current at grounded gate conditions.…”