Ion implantation

Which is a correct technique for forming shallow junctions for the sources and drains of scaled transistors?

  1. AImplanting at high energy followed by a long furnace anneal
  2. BForming them by thermal oxidation alone, without ion implantation
  3. CImplanting at low energy followed by very short anneals (such as spike or laser annealing)
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Answer: C. Implanting at low energy followed by very short anneals (such as spike or laser annealing)

Shallow junctions start with shallow, low-energy implants. Then, so that dopants do not diffuse and deepen the junction during annealing, spike anneals that reach high temperature only briefly, or flash-lamp and laser anneals that heat for a millisecond or less, are used to activate dopants while limiting diffusion.

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More Ion implantation questions

  1. Which correctly pairs the distribution that approximates the depth profile of implanted dopants with the term for the depth of its peak?
  2. In an ion implanter, which part uses a magnetic field to select only the desired ion species?
  3. What is the main advantage of ion implantation over thermal diffusion?
  4. What is the purpose of pre-amorphization implantation (PAI)?
  5. What is used to suppress wafer charging (charge-up) during ion implantation?