Ion implantation

When implanted into silicon at the same energy, how do the ranges of arsenic (mass 75) and phosphorus (mass 31) compare?

  1. AArsenic goes deeper
  2. BBoth reach the same depth
  3. CThe heavier arsenic stops shallower
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Answer: C. The heavier arsenic stops shallower

At the same energy, heavier ions lose energy more readily in collisions with silicon atoms and stop at shallower depths. Arsenic is heavier than phosphorus, so its range is shorter, making it suitable for shallow junctions.

  • A. The heavier arsenic stops shallower.
  • B. Their masses differ, so their ranges differ.
  • C. Correct. Heavier ions stop shallower.
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More Ion implantation questions

  1. In an ion implanter, what is the energy of a doubly charged ion (twice the charge) accelerated through 50 kV?
  2. Which type of ion implanter is mainly used for medium-dose implants such as MOSFET threshold-voltage adjustment and wells?
  3. What is the pair of a vacancy and an interstitial atom called, created in the crystal when an implanted ion knocks a silicon atom out of place?
  4. Why is the wafer cooled during high-current ion implantation?
  5. What is the typical distribution of crystal damage created by ion implantation?