Ion implantation

What must be considered when using photoresist as a mask for ion implantation?

  1. AThe thinner the resist, the better
  2. BThe resist does not need to be removed after implantation
  3. CThe resist must be thick enough for the implant energy so that ions do not penetrate it
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Answer: C. The resist must be thick enough for the implant energy so that ions do not penetrate it

If the resist is too thin, high-energy ions penetrate it and are implanted into masked areas too. Thickness must therefore suit the implant energy and ion species. High-dose implants harden the resist surface and make it hard to remove, so ashing conditions also need attention.

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More Ion implantation questions

  1. What is an advantage of plasma doping, in which the wafer is exposed directly to a dopant-containing plasma and implanted with low-energy ions?
  2. When implanting with the wafer tilted, what is the phenomenon called in which areas in the shadow of tall patterns such as resist receive no implant?
  3. When dopants are activated by annealing, which property sets the upper limit of the concentration that can be electrically activated?
  4. Which is a characteristic of laser annealing?
  5. In ion implantation, how is the dose made uniform across the wafer?