Analysis of the threshold voltage turn-around effect in high-voltage n-MOSFETs due to hot-carrier stress

Abstract

The turn-around effect of the threshold voltage shift during hot-carrier stress has been investigated. Such a phenomenon is explained by the interplay between interface states and oxide traps, i.e. by the compensation of the rapidly created oxide charges by the more slowly created interface states. To prove this idea, a refined extraction scheme for the defect distribution from charge-pumping measurements has been employed. The obtained results are in a good agreement with the findings of our physics-based model of hot-carrier degradation. This approach considers not only damage produced by channel electrons but also by secondary generated channel holes. Although the contribution of the holes to the total defect creation is smaller compared to that of electrons, their impact on the threshold voltage shift is comparable with the electronic contribution. The reason behind this trend is that hole-induced traps are shifted towards the source, thereby more severely affecting the device behavior.

Local oxide capacitance as a crucial parameter for characterization of hot-carrier degradation in long-channel n-MOSFETs

“…9 that the obtained defect profiles feature two peaks starting from $10 2 s. Moreover, Fig. 14,15 This result is confirmed by the findings of our HCD model, 14 which shows that these peaks are related to the contributions induced by primary channel electrons and secondary holes generated by impact ionization caused by the injection of hot electrons. 7 depicts the same tendency) demonstrates that these peaks just correspond to the maxima of the electron and hole acceleration integrals.…”

“…As we demonstrated in Ref. As a result, the N it fraction induced by holes should be much less than their relative contribution to the linear drain current change 14,15 because the hole contribution is considerably shifted toward the source. In literature, one may find different criteria how efficiently carriers interact with the Si-H bond, e.g., the maximum of the electric field, the carrier dynamic temperature, position where the distribution function demonstrates most extended high-energy tales, etc.…”

Investigation of Hot Carrier Stress and Constant Voltage Stress in High- <inline-formula> <tex-math notation="LaTeX">$\kappa$</tex-math></inline-formula> Si-Based TFETs

“…3 also shows that the shifts of characteristics increase at the first stage, but then slightly decrease at longer stress time (> 100 s), and the trend can be observed also in other samples under HCS stress. In [22], a similar trend was reported in nMOSFETs due to HCS which was called "threshold voltage turn-around effect" and attributed to the secondary holes generated by impact ionization due to hot electrons. Here, we study TFET instead of MOSFET, but the impact ionization is even stronger [8].…”

Modeling of hot-carrier degradation based on thorough carrier transport treatment

“…5,right one can also see that the maximum of the interface state density coincides neither with the electric field peak nor with the maximum of the carrier temperature/energy. Instead, we have recently shown [27,65,66] that the quantity which controls hot-carrier degradation is the carrier acceleration integral (AI) which will be introduced below.…”