Etching

Which correctly describes one mechanism by which dry etching achieves anisotropy?

  1. AA passivation film deposited on the sidewalls prevents lateral etching, while ion bombardment removes it from the bottom so etching proceeds there
  2. BOnly the sidewalls dissolve quickly
  3. CThe chemical solution reacts equally in all directions
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Answer: A. A passivation film deposited on the sidewalls prevents lateral etching, while ion bombardment removes it from the bottom so etching proceeds there

In dry etching, films from reaction products and gases deposit on the sidewalls and prevent lateral etching. Meanwhile, ions striking the bottom vertically remove the passivation film, so etching proceeds there. This mechanism produces vertical profiles.

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More Etching questions

  1. Which solution is commonly used for wet etching of silicon nitride?
  2. During plasma etching, what is the phenomenon called in which conductors acting as antennas, such as long wires, collect charge and damage the gate oxide they connect to?
  3. Which is a characteristic of wet etching of silicon with potassium hydroxide (KOH) solution?
  4. Which is a characteristic of inductively coupled plasma (ICP) etching equipment?
  5. Which metric indicates how small the variation in etch rate is across the wafer?