Critical analysis of short-term negative bias temperature instability measurements: Explaining the effect of time-zero delay for on-the-fly measurements

Abstract

Recently several groups have used the reaction-diffusion (R-D) model with H2 diffusion in interpreting negative bias temperature Instability (NBTI) degradation. While the classical “H2 R-D” model can interpret long-term NBTI behavior, it is inconsistent with short-term stress data obtained by recently developed ultrafast measurements and widely used on-the-fly measurements. Moreover, experimental data from various techniques are not consistent with each other. Here, the authors show that the H2 R-D model must be generalized to consistently interpret NBTI at all time scales. The generalized model highlights the previously unappreciated role of time-zero delay in reconciling differences among the so-called delay-free on-the-fly measurements.

Recent Issues in Negative-Bias Temperature Instability: Initial Degradation, Field Dependence of Interface Trap Generation, Hole Trapping Effects, and Relaxation

“…In addition, different experimental groups have observed n > 1/6 region at a different OTFM timeframe [16], [19], [29], [32]. We show in Section II-C that this discrepancy results from the previously unappreciated role of time-zero delay for OTFM [37]. Finally, in addition to very short term transients in < 10 s, we explore the possible origin of n < 1/6 (very soft saturation) at a very long time stress time in Section II-D. 2) Field dependence.…”

“…• C) and for films of various N 2 concentrations and thicknesses [18], and 3) refinement of the R-D models [36], [37] provide us with an opportunity to explore both the short-term NBTI degradation and fast transient relaxation, as well as detailed physical mechanisms of the phenomenological parameters of both the R-D model and hole trapping kinetics in much greater detail than previously possible. We will systematically discuss these generalizations in this paper.…”

“…Indeed, whereas UFM done by Reisinger et al [19] shows a steady state before ∼1 s, the same signature is observed at ∼1 s [16] and ∼100 s [29], [32] for OTFM measurements. This puzzle is resolved (discussed below) by a careful consideration of initial-delay contamination in the so-called "delay-free" OTFM experiments (similar delay contamination in OTFM is also reported in [28] and [37]). …”

“…Although neutral charge state may not be a stable form of atomic hydrogen, its transient formation is indeed possible [38]. Therefore, diffusion of both H and H 2 as well as H ↔ H 2 conversion are explicitly incorporated in the generalized R-D framework by the following [36], [37]:…”

Mobility degradation due to interface traps in plasma oxynitride PMOS devices

“…We also perform NBTI stress/recovery measurements using OTF-I D technique [17,25,28] for each sample. Time-zero delay (t 0 ) [15,31] for OTF-I D is chosen as 1μs [28]. ( )…”