CMP and cleaning

Which correctly describes the basic configuration of a CMP tool?

  1. AThe wafer is milled with an ion beam in vacuum
  2. BThe wafer is simply immersed in a solution to dissolve material
  3. CA wafer held by a polishing head is pressed against a polishing pad on a rotating platen while slurry is supplied
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Answer: C. A wafer held by a polishing head is pressed against a polishing pad on a rotating platen while slurry is supplied

In a CMP tool, a platen covered with a polishing pad rotates, and a polishing head holds the wafer face-down against it. Slurry containing abrasive particles and chemicals is supplied, and chemical action combined with mechanical abrasion removes material. The pad surface is conditioned with a dresser.

  • A. Milling with an ion beam is ion milling or similar.
  • B. Simple immersion is wet etching.
  • C. Correct. The wafer is pressed against a rotating pad and polished with slurry.
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More CMP and cleaning questions

  1. In Cu interconnect CMP, why is polishing generally divided into stages?
  2. Which correctly describes the general difference between hard and soft CMP polishing pads?
  3. What is the state of a silicon surface whose last cleaning step was dilute hydrofluoric acid?
  4. What is the main purpose of installing filters in the lines that supply CMP slurry to the polisher?
  5. When removing particles from a wafer surface by cleaning, how does particle size generally relate to ease of removal?