Modeling and minimization of PMOS NBTI effect for robust nanometer design

ABSTRACT

Negative bias temperature instability (NBTI) has become the dominant reliability concern for nanoscale PMOS transistors. In this paper, a predictive model is developed for the degradation of NBTI in both static and dynamic operations. Model scalability and generality are comprehensively verified with experimental data over a wide range of process and bias conditions. By implementing the new model into SPICE for an industrial 90nm technology, key insights are obtained for the development of robust design solutions: (1) the most effective techniques to mitigate the NBTI degradation are VDD tuning, PMOS sizing, and reducing the duty cycle; (2) an optimal VDD exists to minimize the degradation of circuit performance; (3) tuning gate length or the switching frequency has little impact on the NBTI effect; (4) a new switching scenario is identified for worst case timing analysis during NBTI stress.

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INDEX TERMS

Primary Classification:
  B. Hardware
  B.7 INTEGRATED CIRCUITS
      B.7.2 Design Aids

Additional Classification:
  B. Hardware
  B.8 Performance and Reliability
      B.8.2 Performance Analysis and Design Aids

General Terms:
Design, Experimentation, Performance, Reliability

Keywords:
NBTI, performance degradation, reliability, temperature, threshold voltage, variability