Silicon wafers

Compared with FZ silicon, how does the interstitial oxygen in CZ silicon affect the wafer's mechanical strength?

  1. AOxygen always makes the wafer more brittle
  2. BIt has no effect on mechanical strength
  3. COxygen pins dislocations and makes them harder to move, so the wafer resists slip during heat treatment
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Answer: C. Oxygen pins dislocations and makes them harder to move, so the wafer resists slip during heat treatment

Interstitial oxygen gathers around dislocations and pins them, making them harder to move. CZ wafers containing oxygen therefore tend to resist slip and warpage during heat treatment better than oxygen-poor FZ wafers. This is one reason CZ wafers are used for large-diameter LSI production.

  • A. Interstitial oxygen actually tends to increase strength.
  • B. It does affect mechanical strength.
  • C. Correct. It pins dislocations and makes slip less likely.
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More Silicon wafers questions

  1. Which is a known effect of adding a trace of nitrogen during CZ crystal growth (nitrogen doping)?
  2. Which method selectively and shallowly etches defect regions so that dislocations and stacking faults in silicon can be observed with an optical microscope?
  3. 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?
  4. Along which crystal planes does single-crystal silicon cleave most easily?
  5. Which method is most widely used to produce single-crystal silicon for LSIs?