Oxidation and diffusion

How does the thermal oxidation rate of silicon depend on crystal orientation?

  1. A(100) oxidizes faster than (111)
  2. BOxidation rate is the same regardless of orientation
  3. C(111) oxidizes faster than (100)
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Answer: C. (111) oxidizes faster than (100)

Under the same conditions, (111) surfaces oxidize faster than (100) surfaces because they have a higher surface atom density and more bonds available for oxidation. In structures such as FinFETs, where the sides and top have different orientations, this difference must be considered.

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More Oxidation and diffusion questions

  1. What is the main purpose of introducing nitrogen into the gate oxide to make an oxynitride (SiON)?
  2. Why can thermal oxide be used as a mask against dopants during diffusion?
  3. What is the heat treatment called, performed in a hydrogen-containing atmosphere to reduce interface states at the Si/SiO2 interface?
  4. What is the main purpose of adding a small amount of chlorine-containing gas such as hydrogen chloride (HCl) during thermal oxidation?
  5. When boron-doped silicon is thermally oxidized, how does the boron concentration on the silicon side near the interface tend to change?