Separation of Hole Trapping and Interface-State Generation by Ultrafast Measurement on Dynamic Negative-Bias Temperature Instability

Abstract

Hole trapping and interface-state components of negative-bias temperature instability (NBTI)-induced thresholdvoltage shift are separated via ultrafast switching measurement. Based on the phenomenological observation that dynamic NBTI is determined by a cyclic hole trapping/detrapping mechanism and that interface-state generation is relatively permanent, the time dependence of hole trapping during stress is precisely determined and then subtracted from the overall degradation of the first cycle to yield the time dependence of interface-state generation. Interface-state generation is shown to exhibit power-law time dependence with an initial exponent of ∼0.5, which subsequently decreases to a steady value of 0.25 after ∼1000 s at the stress condition studied (oxide field ∼9 MV/cm). This evolution is shown to be consistent to that obtained via the charge-pumping method, confirming the underlying principle of the approach.

A new eye on NBTI-induced traps up to device lifetime using on the fly oxide trap method

“…The NBTI-induced N it and N bt time characteristics show an evident power-law time-dependence t n with exponent n of 0.16-0.17 and 0.03-0.08, respectively. These results are in perfect agreement with those previously published by different groups [1,9,10]. The first exponent is often attributed to H 2 diffusion mechanism in the R-D framework [14], while in conventional CP, n is about 0.3 [1].…”

“…Not only our experimental method shows the same exponents as those found elsewhere [1,9,10,14], but it is easy to use without any pre-assumption and/or additional method as well. In fact and contrarily to this work, Ming Fu et al [1] combine two methods OTF-V th and OTFIT to extract N bt from V th and N it (see table I).…”

“…It allows measuring both interface-trap and switching oxide-trap [border-trap (N bt )] individually. However and contrary to existing methods [7][8][9], the present method extracts N it and N bt using stress and CP in the same timeframe without stopping the stress. This method is derived from Oxide-trap charge-pumping (OTCP) method, developed for radiation effect [11,12].…”

“…Subsequently, V ot [induced by oxide-trap increase (N ot )] is found by subtracting V it from the amount of V th . Other research group has used the cyclic dynamic of NBTI which is supposed governed solely by hole trapping/detrapping mechanism with assumption that N it is permanent [9,10].…”

A Discharge-Based Pulse Technique for Probing the Energy Distribution of Positive Charges in Gate Dielectric

“…However, when the measurement time is kept shorter than 20 µs [3,12], the recovery becomes negligible. Conventionally, the second requirement is met by measuring the entire Id~Vg and then extracting Vt by using either the constant current method [12,18] or the max-gm extrapolation method [19]. This is supported by typical instruments for the standard Stress-Measure-Stress (SMS) sequence.…”