Ion implantation

Which is a characteristic of laser annealing?

  1. AIt heats the whole wafer uniformly for a long time
  2. BIt heats slowly at low temperature
  3. CIt heats only near the wafer surface for an extremely short time, achieving high activation while limiting diffusion
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Answer: C. It heats only near the wafer surface for an extremely short time, achieving high activation while limiting diffusion

Laser annealing raises only the near-surface region to high temperature for an extremely short time, on the order of microseconds to nanoseconds. Dopants are activated before they can diffuse appreciably, giving shallow, low-resistance junctions. Because it heats underlying layers little, it is also used for back-side processes.

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More Ion implantation questions

  1. In ion implantation, how is the dose made uniform across the wafer?
  2. In an ion implanter, which component measures the beam current to determine the number of implanted ions (dose)?
  3. When forming shallow p-type junctions, what is the main purpose of implanting carbon or similar species together with boron (co-implantation)?
  4. Which gas is typically used in the ion source of an implanter to produce boron ions?
  5. Which is an example of an application of high-energy ion implantation reaching several MeV?