Using soft-edge flip-flops to compensate NBTI-induced delay degradation

ABSTRACT

We present a low-overhead solution to tackle the delay increase caused by Negative Bias Temperature Instability (NBTI), which has emerged as the most critical reliability issue in sub-90nm technology nodes.

The proposed solution consists of using special type of registers, called soft-edge flip-flops (SEFFs), which allow to compensate for the delay increase by introducing a transparency window. SEFFs are an effective alternative to existing solutions such as threshold, supply, or body-bias voltage modulation, since they provide minimum area and power overhead, and can seamlessly replace regular FFs.

Results show that delay degradation up-to 60ps after 10 years of aging can be accounted for with a very small (less than 1%) area penalty.

REFERENCES

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INDEX TERMS

Primary Classification:
  B. Hardware
  B.8 Performance and Reliability
      B.8.0 General

General Terms:
Design, Performance, Reliability

Keywords:
circuit reliability, device aging, flip-flop, nbti, seff, setup and hold time