Etching

Which gases are commonly used for dry etching of polysilicon gates?

  1. ANitrogen (N2)
  2. BHelium (He)
  3. CHalogen gases such as chlorine (Cl2) and hydrogen bromide (HBr)
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Answer: C. Halogen gases such as chlorine (Cl2) and hydrogen bromide (HBr)

Polysilicon etching often uses halogen gases such as chlorine and hydrogen bromide. They react with silicon to form volatile chlorides and bromides and give high selectivity to the underlying gate oxide.

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More Etching questions

  1. What is the process called that removes photoresist by oxidizing it to ash with oxygen plasma or similar?
  2. Which is a characteristic of atomic layer etching (ALE)?
  3. Which correctly describes one mechanism by which dry etching achieves anisotropy?
  4. Which solution is commonly used for wet etching of silicon nitride?
  5. 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?