NBTI mechanism explored on the back gate bias for pMOSFETs

Body Bias Dependence of Bias Temperature Instability (BTI) in Bulk FinFET Technology

“…As shown in Figure 4a, BTI degradation in PMOS FinFETs has the opposite body bias dependence compared with the trend observed in planar devices. [ 4 ] That is, when V b changes from FBB to RBB, the degradation of BTI increases rather decrease. Figure 4b shows that when V b is biased at Type II, the results have an opposite trend with the results in Figure 4a, but the change in BTI degradation cause by body bias is negligible if the V b changes from −1 to 1 V. Here, it is also worth mentioning that a very large FBB can lead to an extremely large degradation.…”

“…Since the |V th0 | is a monotonically increasing function as the V b changes from forward body bias (FBB) to reversal body bias (RBB), the FBB can cause more BTI degradation under same V g , as have been reported in planar devices. [4][5][6][7][8] However, due to the fully depleted tall fin structure, the |V th0 | modulation in bulk FinFETs caused by body effect is very weak, as shown in Figure 1. As a result, changing body bias is generally considered to have little impact on BTI degradation in FinFETs.…”

A comprehensive modeling of dynamic negative-bias temperature instability in PMOS body-tied FinFETs

“…An increment of the hole concentration by accumulated electrons at the center of the fin due to virtually floating-body (V sub = −0.2 V) is dominant in the low-oxide-field (E ox ) condition [5]. In contrast, a decrease of hole concentration from the substrate to the gate is dominant in high-E ox condition due to negative V sub in stress states [12]. More electrons were induced at the interface due to forwardly biased substrate in recovery states.…”