Which polishing method, studied for uses that require low mechanical force, combines electrochemical dissolution to planarize metal?

Answer: B. CMP combined with electropolishing (ECMP)

ECMP (electrochemical mechanical planarization) dissolves the wafer's metal film electrochemically with the film as the anode, while slight mechanical action selectively removes the high points. Because the down-force can be small, it has been researched for purposes such as planarizing Cu wiring on mechanically weak low-k films.

• A. Ion implantation introduces impurities.
• B. Correct. It is polishing combined with electrochemical dissolution.
• C. Thermal oxidation forms an oxide film.