Silicon wafers

Which is a known effect of adding a trace of nitrogen during CZ crystal growth (nitrogen doping)?

  1. AIt promotes oxygen precipitation and shrinks the voids formed by clustered vacancies in the crystal
  2. BThe crystal diameter automatically increases
  3. CThe crystal becomes heavily n-type
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Answer: A. It promotes oxygen precipitation and shrinks the voids formed by clustered vacancies in the crystal

Adding a trace of nitrogen makes nuclei for oxygen precipitation form more easily, improving gettering capability, and it shrinks void defects formed by clustering vacancies so they are easier to eliminate in later heat treatment. The amount added is very small, and its effect as a donor is hardly a concern.

  • A. Correct. It promotes oxygen precipitation and shrinks voids.
  • B. The diameter is set by the pulling conditions.
  • C. The amount is tiny, so conductivity type and resistivity are hardly affected.
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More Silicon wafers questions

  1. Which method selectively and shallowly etches defect regions so that dislocations and stacking faults in silicon can be observed with an optical microscope?
  2. In CZ crystals, what are the periodic, striped variations in dopant or oxygen concentration caused by fluctuations such as temperature at the growth interface called?
  3. Along which crystal planes does single-crystal silicon cleave most easily?
  4. Which method is most widely used to produce single-crystal silicon for LSIs?
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