Oxidation and diffusion

What is the main purpose of adding a small amount of chlorine-containing gas such as hydrogen chloride (HCl) during thermal oxidation?

  1. ATo make the oxide conductive
  2. BTo reduce the oxidation rate to zero
  3. CTo suppress the effects of mobile ions such as sodium and of metal contamination
Show answer and explanation

Answer: C. To suppress the effects of mobile ions such as sodium and of metal contamination

Oxidizing in a chlorine-containing atmosphere removes mobile ions such as sodium and metal contaminants as chlorides or neutralizes them in the oxide. As a result, the oxide's electrical characteristics and reliability improve.

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More Oxidation and diffusion questions

  1. When boron-doped silicon is thermally oxidized, how does the boron concentration on the silicon side near the interface tend to change?
  2. What is the heat treatment called that heats wafers one at a time to high temperature for a few seconds using lamps or similar sources?
  3. Which value is closest to the relative permittivity of SiO2 formed by thermal oxidation?
  4. Which is one of the major reasons silicon has been so widely used as a material for MOS devices?
  5. What problem occurs when mobile ions such as sodium are present in the gate oxide?