The effect of intrinsic body resistance on the breakdown characteristics of DBTS NFD SOI MOSFET´s

The existence of non-zero body resistance (R_B) in the DBTS (double-body-tied-to-source) NFD (non-fully depleted) SOI MOSFET structure leads to bipolar-induced premature breakdown, the mechanism of which is similar to the parasitic bipolar effect in the bulk MOSFET. The conditions can be misleading, however, because the holding voltage and the snapback voltage are indistinguishably referred to as the breakdown voltage, and the stated condition for breakdown, i.e., (M-1)β=1, is independent of R_B. To clarify this issue and to give physical insight regarding the efficacy of the DBTS, we analyze the breakdown characteristics and their dependence on R_B, and we present simple but physical descriptions of the holding and snapback voltages. The derivations are aided and supported by simulations using SOISPICE-3, in which we have implemented a physics-based model for the NFD SOI MOSFET