CMP and cleaning

Why are oxidizers such as hydrogen peroxide added to the slurry in tungsten CMP?

  1. ATo convert the tungsten surface into an oxide that is easy to polish
  2. BTo make the tungsten shine
  3. CTo cool the slurry
Show answer and explanation

Answer: A. To convert the tungsten surface into an oxide that is easy to polish

Tungsten is a hard metal that is difficult to polish mechanically. The oxidizer converts the surface into a soft oxide, which the abrasive particles then remove, and this is repeated as polishing proceeds. It is a clear example of the role of the 'chemical' part of CMP.

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More CMP and cleaning questions

  1. What is a correct design countermeasure to the CMP removal amount varying with pattern density within a chip?
  2. What is the approximate size of the abrasive particles in CMP slurries?
  3. What is the main purpose of diluting chemicals or using functional water in recent cleaning processes?
  4. What is the main purpose of cleaning the back and edge (bevel) of wafers?
  5. What is the main reason wafer cleaning is considered important in semiconductor manufacturing?