CMP and cleaning

What problems are caused by metal contamination such as iron and copper on the wafer surface?

  1. ADegraded characteristics and reliability, such as reduced carrier lifetime and lower gate oxide breakdown strength
  2. BThe wafer becomes lighter
  3. CThe wafer emits light
Show answer and explanation

Answer: A. Degraded characteristics and reliability, such as reduced carrier lifetime and lower gate oxide breakdown strength

Metal impurities act as recombination centers in silicon, reducing carrier lifetime and increasing junction leakage. When incorporated into oxides, they reduce breakdown strength and reliability. Metal contamination must therefore be kept extremely low by cleaning.

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More CMP and cleaning questions

  1. What is the main cause of fine scratches on the wafer surface in CMP?
  2. To prevent fine structures from collapsing, which method removes native oxide and the like without using liquids?
  3. Which combination correctly lists processes in which CMP is used?
  4. What is the operation called in which the surface of a CMP pad is dressed with a diamond tool to stabilize the removal rate?
  5. Compared with planarization by thermal reflow or etch-back, what is an advantage of CMP?