CMP and cleaning

Which cleaning method applies MHz-range ultrasound to the cleaning solution to remove tiny particles from the wafer surface?

  1. AAshing
  2. BMegasonic cleaning
  3. CScribing
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Answer: B. Megasonic cleaning

Megasonic cleaning applies ultrasound of around 1 MHz to the cleaning solution, and the liquid's vibration detaches tiny particles from the surface. Compared with kHz-range ultrasonic cleaning, it removes small particles with less damage to fine patterns.

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More CMP and cleaning questions

  1. What is the main purpose of cleaning with ozone dissolved in ultrapure water (ozonated water)?
  2. What is the role of benzotriazole (BTA) and similar additives in copper CMP slurries?
  3. What is the role of the retaining ring that surrounds the wafer in a CMP polishing head?
  4. Why are particles, once detached, unlikely to redeposit in alkaline cleaning solutions such as SC-1?
  5. What problems are caused by metal contamination such as iron and copper on the wafer surface?