CMP and cleaning

Compared with planarization by thermal reflow or etch-back, what is an advantage of CMP?

  1. AIt is always cheaper
  2. BIt produces no polishing debris at all
  3. CIt achieves planarization over wide areas across the whole wafer (global planarization)
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Answer: C. It achieves planarization over wide areas across the whole wafer (global planarization)

Reflow and etch-back can smooth local steps but have difficulty planarizing wide areas across the wafer. CMP preferentially polishes raised areas with a stiff pad, achieving high planarity across the chip and wafer, which made multilevel interconnects possible.

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More CMP and cleaning questions

  1. Which correctly describes the order and purposes of SC-1 and SC-2 in standard RCA cleaning?
  2. What is the main cause of pattern collapse when cleaning and drying high-aspect-ratio patterns?
  3. Why are oxidizers such as hydrogen peroxide added to the slurry in tungsten CMP?
  4. What is a correct design countermeasure to the CMP removal amount varying with pattern density within a chip?
  5. What is the approximate size of the abrasive particles in CMP slurries?