Etching

What is needed to etch oxide and stop on the nitride underneath?

  1. ALow selectivity
  2. BIsotropic etching
  3. CHigh etch selectivity of oxide to nitride
Show answer and explanation

Answer: C. High etch selectivity of oxide to nitride

To stop on nitride, conditions are needed that etch oxide quickly while barely etching nitride. Selectivity of oxide to nitride is raised, for example, by using carbon-rich fluorocarbon gas conditions. This is important in forming self-aligned contacts.

Practice this topic Back to topic

More Etching questions

  1. What is the role of etching in semiconductor manufacturing?
  2. Which correctly describes the "plasma" used in dry etching?
  3. If etching proceeds at 100 nm/min for 3 minutes, how much film is removed?
  4. In wet etching, how does the etch rate generally change when the solution temperature is raised?
  5. In plasma tools such as capacitively coupled ones, what is the phenomenon called in which the wafer-side electrode naturally acquires a negative DC potential that accelerates ions toward the wafer?