On the dispersive versus arrhenius temperature activation of nbti time evolution in plasma nitrided gate oxides: measurements, theory, and implications

Abstract

Negative Bias Temperature Instability (NBTI) is studied in p-MOSFETs having Decoupled Plasma Nitrided (DPN) gate oxides (EOT range of 12A O through 22A O ). Threshold voltage shift (∆V T ) is shown to be primarily due to interface trap generation (∆N IT ) and significant hole trapping (∆N OT ) has not been observed. ∆V T follows power-law time (t) dependence and Arrhenius temperature (T) activation. IntroductionNBTI is a serious reliability concern for p-MOSFETs [1]. Oxynitrides (required for suppressing boron penetration and gate leakage) show worse NBTI than control oxides and has attracted much attention [2][3][4][5]. It is important to correctly measure and extrapolate t evolution of ∆V T to accurately determine device lifetime. However, this extrapolation is complicated since (i) impact of delay time on measurement is not fully understood, (ii) ∆V T origin (∆N IT that predicts t

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

“…3,7 This "H 2 R-D" model also provides a consistent interpretation of temperature and field dependencies of NBTI for long-term stress, as extensively studied for devices with SiO 2 , plasma SiON, and thin thermal SiON dielectrics. 2,5,6,8 Although the classical "H 2 R-D" model provides an excellent interpretation for long-term stress data, our analysis shows that ͑1͒ the predictions of this model is inconsistent with the short term, sub-10 s, NBTI degradation ͓see Fig. 1͑b͔͒ and ͑2͒ in contrast to long-term degradation, the shortterm time exponent of NBTI degradation depends on the measurement techniques.…”

“…This figure also signifies that H 2 diffusion ͑alone͒ cannot properly explain the short-term stress data with the parameters normally used in the model. 2 predicts a change in n from 1 ͑for reaction-limited region 1,7 ͒ to 1/6 ͑for H 2 diffusion-limited region 3,7 ͒ within approximately one order of time scale ͑see the dashed asymptotes in Fig. 1͑b͒͒, experiments indicate a wider transition region ͑Fig.…”

“…[1][2][3][4][5][6][7] At long stress time ͑t stress Ͼ 10-100 s͒, ⌬V T shows a power law behavior when plotted with respect to time ͑⌬V T ϳ At n ͒ with a consistent time exponent ͑n͒ of ϳ1 / 6. This time exponent is independent of the measurement techniques used to monitor ⌬V T ͓e.g., ultrafast measurement ͑UFM͒, 9 "delay-free" on-the-fly I dlin measurement ͑OTFM͒, 2,3,5,6,8 etc.͔. The R-D model attributes the robust ͑constant over several decades in time 4 ͒ long-term n ϳ 1 / 6 exponent to the diffusion of molecular hydrogen ͑H 2 ͒.…”

“…The origin of such degradation has been debated for the last few years, and it is now generally accepted that, for devices with SiO 2 , plasma SiON, and thin thermal SiON gate dielectrics, NBTI degradation results mainly from depassivation of Si-H bonds at the Si/dielectric interface and resultant diffusion of hydrogen species into gate dielectric and poly-Si. [1][2][3][4][5][6][7][8] As such, several groups have used the reaction-diffusion ͑R-D͒ model to interpret NBTI degradation. [1][2][3][4][5][6][7] At long stress time ͑t stress Ͼ 10-100 s͒, ⌬V T shows a power law behavior when plotted with respect to time ͑⌬V T ϳ At n ͒ with a consistent time exponent ͑n͒ of ϳ1 / 6.…”

“…[1][2][3][4][5][6][7][8] As such, several groups have used the reaction-diffusion ͑R-D͒ model to interpret NBTI degradation. [1][2][3][4][5][6][7] At long stress time ͑t stress Ͼ 10-100 s͒, ⌬V T shows a power law behavior when plotted with respect to time ͑⌬V T ϳ At n ͒ with a consistent time exponent ͑n͒ of ϳ1 / 6. This time exponent is independent of the measurement techniques used to monitor ⌬V T ͓e.g., ultrafast measurement ͑UFM͒, 9 "delay-free" on-the-fly I dlin measurement ͑OTFM͒, 2,3,5,6,8 etc.͔.…”