Etching

Which method is commonly used to detect the endpoint of dry etching?

  1. AWeighing the wafer
  2. BMonitoring changes in the plasma's emission spectrum
  3. CChecking visually after etching
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Answer: B. Monitoring changes in the plasma's emission spectrum

When the film being etched is gone and the underlayer is exposed, the reaction products in the plasma change, and the intensity of emission at specific wavelengths changes. Monitoring these changes in the emission spectrum detects the etch endpoint in real time (optical emission spectroscopy, OES).

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More Etching questions

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