Reliability

In leading-edge LSI design, what is the practice called of anticipating transistor degradation from BTI and HCI over the usage period and checking that timing is met even with degraded characteristics?

  1. APhotolithography
  2. BWafer reclaim
  3. CAging-aware reliability design
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Answer: C. Aging-aware reliability design

Transistor characteristics degrade gradually during use, slowing circuits. Aging-aware reliability design predicts the amount of degradation from operating conditions with models, then runs circuit simulation and timing analysis with the degraded characteristics, securing margin so specifications are met until end of life.

  • A. Photolithography is the pattern transfer step.
  • B. Wafer reclaim reuses spent monitor wafers.
  • C. Correct. Circuits are designed to work even after degradation.
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  3. When electromigration in flip-chip solder bumps becomes a problem due to large currents, where are failures known to be especially likely?
  4. Regarding BTI degradation, part of the threshold voltage shift recovers once the stress is removed. What does this imply for evaluation?
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