Ion implantation

What problem tends to arise when removing photoresist that has received a high-dose ion implant?

  1. AThe resist becomes transparent
  2. BThe surface becomes a carbonized, hardened crust, and rapid heating during normal ashing tends to make it burst from gas inside (popping)
  3. CThe resist dissolves away in water
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Answer: B. The surface becomes a carbonized, hardened crust, and rapid heating during normal ashing tends to make it burst from gas inside (popping)

Resist that has received a high-dose implant forms a carbonized, hard crust on its surface. Ashing it at high temperature right away makes gas from the soft resist underneath burst the crust, causing residues and particles. Measures such as stepping up from low temperature are required.

  • A. Becoming transparent is not the problem.
  • B. Correct. The hardened crust and popping are the problem.
  • C. Implanted resist actually becomes harder to remove.
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More Ion implantation questions

  1. In ion implantation, which parameter mainly determines how deep the dopants are implanted (the range)?
  2. What is the main purpose of annealing (heat treatment) after ion implantation?
  3. Which is a common way to suppress channeling (ions traveling too deep through gaps in the crystal) in ion implantation?
  4. Which unit is used for the dose in ion implantation?
  5. Which is a correct technique for forming shallow junctions for the sources and drains of scaled transistors?