Abslracl-A quantitative model is developed for the first time, that comprehends all the unique characteristifs of NBTI degradation. Several models are critically examined to develop a reactioddiffusion based modeling framework for predicting interface state generation during NBTI stress. NBTI degradation is found to be dominated by difTusion of neutral atomic and molecular hydrogen related defects. Additionally, the presence of hydrogen gettering sites such as unsaturated grain houndaries significantly enhance NBTI degradation, whereas hydrogen sources reduce NBTI degradation. The model also suggests the possible mechanisms for saturation. The model is calibrated over a range of stress temperatures and voltages. The model captures recovery, experimental delay and frequency effects successfully.

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We describe a quantitative relationship between ID and V, driven NBTl specifications. Mobility degradation is shown to be a significant (-40%) contributor to ID degradation. We report for the first time, degradation in gate-drain capacitance (CGo) due to NBTI. The impact of this COD degradation on circuit performance is quantified for both digital and analog circuits. We find that CGD degradation has a greater impact on the analog circuit studied than the digital circuit. We demonstrate that there is an optimum operating voltage that balances NBTI degradation against transistor voltage headroom. Further, a numerical model based on the reaction-diffision theory has been developed, which is found to satisfactorily describe degradation, recovery and postrecovery response to stress.

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Since nitrided oxides improve gate leakage at the expense of NBTI, one must optimize nitrogen concentration in oxinitride samples for reliable performance and reduced power dissipation. Here, we analyze wide range of NBTI stress data to develop a predictive model for gate leakage and first selfconsistent model for field acceleration within R-D framework. This model anticipates a novel design diagram for co-optimization of leakage and NBTI for arbitrary nitrogen concentration and effective oxide thickness.1. Introduction Since nitrided oxides (SiON) improve gate leakage (J G ) [1-6] at the expense of NBTI performance (∆V T ) [7,8], one must necessarily optimize N 2 concentration (%N) in gate-oxides for high-performance ICs. Despite its importance, however, a quantitative analysis of leakage/NBTI trade-off (as a function of %N), has never been reported and the question "Is cooptimization of NBTI/leakage possible at any %N?" has never been answered. In this paper, we simultaneously measure gate leakage and delay-free NBTI over broad range of stress-fields, stress-temperatures and %N, model gate leakage current (J G ) and NBTI degradation within a theoretically consistent framework (hole-assisted thermal generation of interface traps) of field-dependent R-D model, and conclude that although there is no optimum %N for NBTI/leakage, the reduction in J G at NBTI-limited %N (~15-25%, depending on failure criterion) can be significant and would reduce power dissipation without affecting NBTI-margin.2. Gate Leakage Comprehensive simulation [9] (which includes the effects of multi-subband electron/hole quantization, poly-depletion, etc.) of the measured J G -V G for both N-and PMOS (Fig. 1) was done to extract the model parameters as a function of %N (Fig. 2). We assume that any variation in the spatial-profile of nitrogen results only in second-order correction to calculated J G . Contrary to popular belief [2-6, 10], the oxide parameters do not scale linearly with %N. All the parameters have approximately a quadratic fit with %N. Here, effective oxide thickness (EOT) is obtained from simulation of CV, and physical thickness (T PHY ) and %N are determined by XPS [11]. These %N-dependent parameters are used to calculate J G (N,EOT) for arbitrary %N and EOT, as shown in Fig. 10b. -1.0 -0.5 0.0