Etching

Which correctly describes anisotropic etching?

  1. AEtching proceeds mainly vertically and hardly at all laterally
  2. BEtching proceeds at the same rate in all directions
  3. COnly the mask material is selectively removed
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Answer: A. Etching proceeds mainly vertically and hardly at all laterally

In anisotropic etching, vertical etching proceeds preferentially, for example due to ion bombardment, and there is almost no lateral etching undercutting the mask. The mask pattern is therefore transferred accurately, allowing fine, vertical features to be formed.

Cross-sections of isotropic and anisotropic etching Isotropic etching Also etches sideways, under the mask Anisotropic etching Etches only downward; pattern is exact Mask Etched film Underlayer
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More Etching questions

  1. Which correctly describes 'selectivity' in etching?
  2. Which is a general characteristic of wet etching?
  3. Which correctly describes reactive ion etching (RIE)?
  4. Which method is commonly used to detect the endpoint of dry etching?
  5. What is the aspect ratio of a hole or trench formed by etching?