Process materials (gases and chemicals)

What is the most appropriate approximate purity required of polycrystalline silicon (polysilicon) feedstock for semiconductors?

  1. AAbout 99%
  2. BAbout 99.99%
  3. CAbout 99.999999999% (11N)
Show answer and explanation

Answer: C. About 99.999999999% (11N)

Semiconductor-grade silicon requires extremely high purity, about 'eleven nines' (11N). Even tiny amounts of metal impurities can greatly change device characteristics. Silicon for solar cells can be of somewhat lower purity.

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