Etching

Why is it difficult to pattern copper wiring directly by dry etching?

  1. ABecause copper does not conduct electricity
  2. BBecause copper is too soft
  3. CBecause copper halides are not volatile, so the reaction products cannot be removed
Show answer and explanation

Answer: C. Because copper halides are not volatile, so the reaction products cannot be removed

Aluminum reacts with chlorine to form volatile aluminum chloride and can be dry-etched, but copper chlorides and similar compounds are not volatile and remain on the surface. Copper wiring is therefore made without etching by the damascene process, filling trenches and polishing by CMP.

Practice this topic Back to topic

More Etching questions

  1. In gate etching, what is the phenomenon called in which the pattern sidewall is undercut laterally near the boundary with the underlying insulator?
  2. Why are reaction products (polymers) left on pattern sidewalls removed after dry etching?
  3. What is needed to etch oxide and stop on the nitride underneath?
  4. What is the role of etching in semiconductor manufacturing?
  5. Which correctly describes the "plasma" used in dry etching?