Ion implantation

What is the main purpose of annealing (heat treatment) after ion implantation?

  1. ATo evaporate and remove the implanted dopants
  2. BTo repair crystal damage and place dopants on lattice sites to activate them electrically
  3. CTo grow a thick oxide on the wafer surface
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Answer: B. To repair crystal damage and place dopants on lattice sites to activate them electrically

Implanted ions disrupt the silicon crystal, and many end up in positions where they do not act as donors or acceptors. Annealing repairs the crystal damage and moves dopants onto lattice sites, activating them. Short heating methods such as RTA are used so that dopants do not diffuse too much.

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More Ion implantation questions

  1. Which is a common way to suppress channeling (ions traveling too deep through gaps in the crystal) in ion implantation?
  2. Which unit is used for the dose in ion implantation?
  3. Which is a correct technique for forming shallow junctions for the sources and drains of scaled transistors?
  4. Which correctly pairs the distribution that approximates the depth profile of implanted dopants with the term for the depth of its peak?
  5. In an ion implanter, which part uses a magnetic field to select only the desired ion species?