Oxidation and diffusion

What is the main purpose of introducing nitrogen into the gate oxide to make an oxynitride (SiON)?

  1. ATo suppress boron penetration from the gate electrode and improve reliability
  2. BTo make the film conductive
  3. CTo increase the etch rate
Show answer and explanation

Answer: A. To suppress boron penetration from the gate electrode and improve reliability

Boron in p+ polysilicon gates can penetrate thin gate oxide into the channel and shift the threshold voltage. Adding nitrogen suppresses boron diffusion and slightly raises the dielectric constant. It also improves reliability, such as resistance to hot carriers.

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More Oxidation and diffusion questions

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