Etching

What is the aspect ratio of a hole or trench formed by etching?

  1. AThe ratio of depth to width (opening diameter)
  2. BThe ratio of top area to bottom area
  3. CThe ratio of the etch rates of the target film and the mask
Show answer and explanation

Answer: A. The ratio of depth to width (opening diameter)

The aspect ratio is the depth of a hole or trench divided by its width. Etching deep, narrow structures with aspect ratios over several tens, such as the memory holes in 3D NAND, is particularly difficult and a major challenge for etching technology. The ratio of etch rates is selectivity.

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More Etching questions

  1. What is the phenomenon called in which the etch rate decreases as patterns become narrower and deeper?
  2. Which gases are commonly used for dry etching of polysilicon gates?
  3. What is the process called that removes photoresist by oxidizing it to ash with oxygen plasma or similar?
  4. Which is a characteristic of atomic layer etching (ALE)?
  5. Which correctly describes one mechanism by which dry etching achieves anisotropy?