Silicon wafers

In the mirror polishing (final CMP polishing) of silicon wafers, what is commonly used as the abrasive in the slurry?

  1. AIron powder
  2. BColloidal silica (fine silica particles)
  3. CLarge diamond grains
Show answer and explanation

Answer: B. Colloidal silica (fine silica particles)

Final wafer polishing uses colloidal silica, with silica particles of several tens of nanometers dispersed in an alkaline liquid. Combining chemical action with the mechanical action of the fine particles gives a mirror finish with few scratches.

  • A. Iron powder would cause metal contamination and is not used.
  • B. Correct. A liquid with dispersed fine silica particles is used.
  • C. Large diamond grains would leave deep scratches and could not produce a mirror finish.
Practice this topic Back to topic

More Silicon wafers questions

  1. What is the main use of low-resistivity n⁺ silicon wafers heavily doped with arsenic or antimony?
  2. When CZ silicon is heat-treated around 450 °C, oxygen atoms can cluster and act as donors, changing the wafer's resistivity. What is this called?
  3. To analyze metal contamination on a wafer surface with high sensitivity, which preparation method dissolves the surface oxide with hydrofluoric acid vapor and collects it in a droplet for analysis?
  4. What are the very gentle undulations on a wafer surface, with lateral wavelengths of a few millimeters and heights of tens of nanometers, called?
  5. Compared with FZ silicon, how does the interstitial oxygen in CZ silicon affect the wafer's mechanical strength?