CMP and cleaning

Which known problem tends to occur if rinsing after SPM (sulfuric acid and hydrogen peroxide) cleaning is insufficient?

  1. ASulfate ions and the like remain on the surface and later cause haze and defects
  2. BThe wafer becomes thicker
  3. CThe surface becomes n-type
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Answer: A. Sulfate ions and the like remain on the surface and later cause haze and defects

Sulfuric acid is viscous and tends to remain on surfaces, so insufficient rinsing leaves sulfate ions that can react with ammonia and the like in the air, producing haze from precipitated crystals and defects. Countermeasures include thorough rinsing with hot water.

  • A. Correct. Residual sulfate ions cause haze and defects.
  • B. The wafer does not become thicker.
  • C. The conductivity type does not change.
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More CMP and cleaning questions

  1. Which polishing method, studied for uses that require low mechanical force, combines electrochemical dissolution to planarize metal?
  2. Which correctly describes CMP (chemical mechanical polishing)?
  3. What is the main purpose of SC-1 (a mixture of ammonia and hydrogen peroxide) in RCA cleaning?
  4. Which correctly describes 'dishing' in CMP?
  5. What is the main purpose of cleaning with dilute hydrofluoric acid (DHF)?