Etching

Which is a characteristic of downstream etching, which supplies only plasma-generated radicals to the wafer?

  1. AStrong ion bombardment makes it highly anisotropic
  2. BWith almost no ion bombardment, it etches isotropically with little damage
  3. CIt etches with chemical solutions
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Answer: B. With almost no ion bombardment, it etches isotropically with little damage

In downstream etching, the plasma is generated away from the wafer, and only long-lived neutral radicals reach it. Without ion bombardment there is little damage, and etching is isotropic. It is used for resist removal and for removing films in damage-sensitive steps.

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More Etching questions

  1. Which are examples of profile defects seen in high-aspect-ratio etching?
  2. If the oxide etch rate is 100 nm/min and the mask is consumed at 20 nm/min, what is the selectivity to the mask?
  3. Which solution, made by buffering hydrofluoric acid with ammonium fluoride, is used for wet etching of SiO2?
  4. Why is cryogenic etching, which cools the wafer to very low temperatures, attracting attention for high-aspect-ratio processing?
  5. Because changes in the condition of an etch chamber's walls alter results, what is it called to process dummy wafers before product to stabilize the chamber?