CMP and cleaning

What is the main purpose of a CMP head that can vary the pressure pressing the wafer in several concentric zones?

  1. ATo adjust removal at the wafer center, edge and elsewhere so the film thickness is uniform across the wafer
  2. BTo save slurry
  3. CTo spin the wafer faster
Show answer and explanation

Answer: A. To adjust removal at the wafer center, edge and elsewhere so the film thickness is uniform across the wafer

Removal rate is roughly proportional to pressure, so dividing the head into several concentric zones with independent pressures lets removal be tuned by location on the wafer. It is adjusted to the incoming film thickness profile so that the post-polish thickness is uniform.

  • A. Correct. Removal is tuned by location to achieve uniformity.
  • B. Saving slurry is not the purpose.
  • C. It is not a mechanism for spin speed.
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More CMP and cleaning questions

  1. Which CMP method fixes the abrasive particles in the polishing pad instead of putting them in the slurry?
  2. Which known problem tends to occur if rinsing after SPM (sulfuric acid and hydrogen peroxide) cleaning is insufficient?
  3. Which polishing method, studied for uses that require low mechanical force, combines electrochemical dissolution to planarize metal?
  4. Which correctly describes CMP (chemical mechanical polishing)?
  5. What is the main purpose of SC-1 (a mixture of ammonia and hydrogen peroxide) in RCA cleaning?