Isolation of NBTI Stress Generated Interface Trap and Hole-Trapping Components in PNO p-MOSFETs

Abstract

Abstract-In this paper, a simple phenomenological technique is used to isolate the hole-trapping and interface trap generation components during negative bias temperature instability (NBTI) stress in plasma nitrided oxide (PNO) p-MOSFETs. This isolation methodology reconciles the apparent differences between experimentally measured NBTI power-law time exponents obtained by ultrafast on-the-fly I DLIN method, which are the ones obtained using slightly delayed but very long-time measurements, and the corresponding exponents predicted by the reaction-diffusion model. A systematic validation of the isolation technique is provided through degradation data taken over a broad range of operating conditions and a wide variety of PNO processes, to establish the robustness and uniqueness of the separation procedure.Index Terms-Activation energy, field acceleration, hole trapping, interface traps, negative bias temperature instability (NBTI), plasma oxynitride, p-MOSFET, reaction-diffusion (R-D) model, time exponent.

On the thermal activation of negative bias temperature instability

“…4. In a recent paper [15], it was suggested that the initial degradation of the pMOSFET is due to elastic tunneling. However in this study elastic (temperature-independent) charge trapping contributions were not detectable during either stress or recovery.…”

A Common Framework of NBTI Generation and Recovery in Plasma-Nitrided SiON p-MOSFETs

“…As a result, although ΔV h fraction is different for different stress times and T 's (see Fig. 2), t h corresponding to ΔV h recovery remains identical as the magnitude of ΔV h is identical for various stress times (due to fast ΔV h saturation) and stress T 's (due to negligible T activation of ΔV h [6]). A correlated recovery of ΔV h and ΔV IT at the early-recovery phase would result in different t h 's as a function of stress duration and stress/recovery T , contrary to the observed results.…”

“…., yet to recover) during recovery (following different stress times), at identical stress/recovery E OX and T , for N = 42% and an EOT = 1.46-nm SiON device. Very large T -independent short-time (submillisecond) degradation has been identified as due to ΔV h , while long-time degradation has been correlated to ΔV IT [6]. Assuming fast saturation (t < 1 s) of ΔV h , a constant ΔV h has been subtracted from long time (t > 10 s)ΔV T to obtain ΔV IT that shows n = 0.16 (see [6] for details), which remains consistent with very long-time stress data [16], [17].…”

“…Very large T -independent short-time (submillisecond) degradation has been identified as due to ΔV h , while long-time degradation has been correlated to ΔV IT [6]. Assuming fast saturation (t < 1 s) of ΔV h , a constant ΔV h has been subtracted from long time (t > 10 s)ΔV T to obtain ΔV IT that shows n = 0.16 (see [6] for details), which remains consistent with very long-time stress data [16], [17]. Such an isolation method has been shown to yield consistent E OX and T dependence of ΔV h and ΔV IT over a wide range of N%'s and EOTs of the SiON gate insulator.…”

“…Based on these results, SiON process dependence has been attributed to the relative differences in trapped holes (ΔV h 's) in preexisting bulk insulator traps and generation of interface traps (ΔV IT 's) that contribute to the overall ΔV T . For the stress phase, the ΔV h and ΔV IT contributions to the overall ΔV T have been consistently separated for p-MOSFETs having different plasma-nitrided (PN) SiON processes [6]. It has been shown that ΔV h and ΔV IT generation does not show any correlation as SiON processes and stress conditions are varied.…”