CMP and cleaning

As CMP continues, the polishing pad temperature rises. How does the removal rate generally change?

  1. ATemperature does not affect the removal rate
  2. BFaster chemical reactions and similar effects tend to raise the removal rate, which also causes within-wafer variation
  3. CThe removal rate drops and polishing always stops
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Answer: B. Faster chemical reactions and similar effects tend to raise the removal rate, which also causes within-wafer variation

When friction during polishing raises the temperature of the pad and slurry, the slurry's chemical reactions speed up and the removal rate tends to rise. Because the temperature distribution leads to within-wafer variation, techniques to monitor and control pad temperature are also used.

  • A. Temperature affects the removal rate through chemical action.
  • B. Correct. The rate tends to rise, which also causes variation.
  • C. A temperature rise does not stop polishing.
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More CMP and cleaning questions

  1. In SC-1 (a mixture of ammonia and hydrogen peroxide), what role does the hydrogen peroxide play?
  2. Which method is commonly used to count particles on a wafer surface after cleaning?
  3. Why is it considered important to transfer wafers to cleaning right after CMP while still wet, without letting them dry?
  4. What is a point of caution for batch cleaning, in which many wafers are immersed in the same tank of cleaning solution?
  5. Which cleaning method, researched and commercialized for removing particles without collapsing fine patterns, sprays tiny particles of cryogenic carbon dioxide or argon?