Etching

Which correctly describes the "plasma" used in dry etching?

  1. AA very cold liquid
  2. BA state of gas that is ionized, containing a mixture of electrons, ions, radicals and so on
  3. CA solid metal
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Answer: B. A state of gas that is ionized, containing a mixture of electrons, ions, radicals and so on

Plasma is a state in which power applied to a gas accelerates electrons and ionizes atoms and molecules, giving a mixture of electrons, ions, highly reactive radicals and neutral molecules. Dry etching uses the ions and radicals to remove film.

  • A. Plasma is not a liquid.
  • B. Correct. It is an ionized state of gas.
  • C. Plasma is not a solid.
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More Etching questions

  1. If etching proceeds at 100 nm/min for 3 minutes, how much film is removed?
  2. In wet etching, how does the etch rate generally change when the solution temperature is raised?
  3. 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?
  4. What is the masking scheme called that stacks three layers, an organic (carbon) film at the bottom, a silicon-containing middle layer and resist on top, to etch fine patterns deeply?
  5. Which gas can etch silicon isotropically without a plasma, for example to remove sacrificial layers in MEMS?