Ion implantation

Under the same annealing conditions, how does the sheet resistance of the implanted layer generally change when the implant dose is increased?

  1. AIt decreases
  2. BIt increases
  3. CIt does not change
Show answer and explanation

Answer: A. It decreases

A larger dose increases the total amount of dopant in the implanted layer and thus the number of carriers, so sheet resistance decreases. However, above the dopant's solid solubility, more dopant cannot be fully activated, so increasing the dose lowers sheet resistance less.

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More Ion implantation questions

  1. What must be considered when using photoresist as a mask for ion implantation?
  2. 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?
  3. 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?
  4. When dopants are activated by annealing, which property sets the upper limit of the concentration that can be electrically activated?
  5. Which is a characteristic of laser annealing?