CMP and cleaning

What is the role of benzotriazole (BTA) and similar additives in copper CMP slurries?

  1. ATo form a protective film on the copper surface, suppressing excessive etching and corrosion
  2. BTo make the abrasive particles larger
  3. CTo color the slurry
Show answer and explanation

Answer: A. To form a protective film on the copper surface, suppressing excessive etching and corrosion

Cu CMP slurries contain components that oxidize and dissolve copper, which on their own would also dissolve copper in recessed areas. Corrosion inhibitors such as BTA form a protective film on the copper surface so that only raised areas contacted by the pad are polished, achieving both planarization and corrosion prevention.

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More CMP and cleaning questions

  1. What is the role of the retaining ring that surrounds the wafer in a CMP polishing head?
  2. Why are particles, once detached, unlikely to redeposit in alkaline cleaning solutions such as SC-1?
  3. What problems are caused by metal contamination such as iron and copper on the wafer surface?
  4. What is the main cause of fine scratches on the wafer surface in CMP?
  5. To prevent fine structures from collapsing, which method removes native oxide and the like without using liquids?