Interconnect processes

Where are voids due to electromigration likely to form?

  1. AWhere the flow of metal atoms is discontinuous, such as at the boundary between a via and a wire
  2. BIn the middle of a wire carrying no current
  3. CIn the package substrate outside the chip
Show answer and explanation

Answer: A. Where the flow of metal atoms is discontinuous, such as at the boundary between a via and a wire

In electromigration, atoms are pushed along by the flow of electrons. Where the flow of atoms is interrupted, such as at a via-wire boundary, atoms leave but are not replenished, so voids form easily. Designs counter this with measures such as using multiple vias.

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More Interconnect processes questions

  1. In highly scaled LSIs, how has wiring delay trended compared with gate delay?
  2. What problem must be watched for when etching or ashing low-k films?
  3. What is the time-dependent dielectric breakdown of the insulator between wires called, which is becoming more important as wire spacing shrinks?
  4. What is the main role of the wiring inside an LSI?
  5. Which correctly describes "multilevel wiring" in an LSI?