Ion implantation

In an ion implanter, what is the energy of a doubly charged ion (twice the charge) accelerated through 50 kV?

  1. A100 keV
  2. B25 keV
  3. C50 keV
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Answer: A. 100 keV

The energy an ion gains is charge × acceleration voltage. A singly charged ion gets 50 keV, but a doubly charged ion, with twice the charge, gets 100 keV. This allows implants at energies above the tool's maximum voltage.

  • A. Correct. 2 × 50 kV = 100 keV.
  • B. 25 keV would correspond to half the charge.
  • C. 50 keV is for a singly charged ion.
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More Ion implantation questions

  1. Which type of ion implanter is mainly used for medium-dose implants such as MOSFET threshold-voltage adjustment and wells?
  2. 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?
  3. Why is the wafer cooled during high-current ion implantation?
  4. What is the typical distribution of crystal damage created by ion implantation?
  5. What method has commonly been used to introduce impurities into a MOSFET's polysilicon gate electrode to lower its resistance?