Oxidation and diffusion

In thermal diffusion, what is the step called that drives dopants deeper after a fixed amount has been introduced at the surface?

  1. APredeposition
  2. BEpitaxy
  3. CDrive-in
Show answer and explanation

Answer: C. Drive-in

Thermal diffusion is often done in two steps: predeposition introduces a fixed amount of dopant at the surface, then drive-in stops the supply and heats the wafer to diffuse the dopant inward to the desired depth and profile. Today, ion implantation is generally used to introduce dopants, and subsequent heat treatment adjusts the profile.

Practice this topic Back to topic

More Oxidation and diffusion questions

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