Interconnect processes

In electromigration testing, wires shorter than a certain length show greatly extended lifetimes, with almost no degradation. What is this phenomenon called?

  1. AThe Blech effect (short-length effect)
  2. BThe Miller effect
  3. CThe Early effect
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Answer: A. The Blech effect (short-length effect)

When electromigration carries atoms in one direction, a stress gradient builds up toward the wire end and drives a counter-flow of atoms. In short wires this back-flow balances the current-driven flow, so degradation hardly proceeds. This critical product of length and current density is called the Blech effect and is used in design rules for current density.

  • A. Correct. It is the suppression of degradation in short wires.
  • B. The Miller effect makes feedback capacitance appear multiplied by the gain.
  • C. The Early effect concerns the slope of transistor output characteristics.
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More Interconnect processes questions

  1. When a wire becomes narrower than its grains so that grain boundaries line up across the wire, what is this structure called, and how does it affect electromigration?
  2. When high-frequency signals flow in a wire, what is the phenomenon called in which current concentrates near the conductor surface and the effective resistance rises?
  3. What is the design practice called in which active devices and wiring are placed directly beneath the bond pads used for wire bonding and the like?
  4. Which technique deposits a Cu alloy with a small addition of manganese or similar and, through annealing, lets a thin barrier form spontaneously at the interface with the dielectric?
  5. For long, wide wires such as the clock network of a chip running at several GHz, which wire property must be considered in addition to resistance and capacitance?