Silicon wafers

What causes "slip", a problem when large-diameter wafers are heat-treated at high temperature?

  1. AStress from temperature differences within the wafer or its own weight shifts crystal planes and introduces dislocations
  2. BParticles adhere to the wafer surface
  3. CThe impurity concentration decreases
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Answer: A. Stress from temperature differences within the wafer or its own weight shifts crystal planes and introduces dislocations

Silicon weakens at high temperature, so stress from temperature differences during rapid heating or cooling, or from the wafer's own weight at the support points, makes crystal planes slide and introduces dislocations (slip). Because this causes device leakage and yield loss, ramp rates and support methods are carefully designed.

  • A. Correct. Stress shifts crystal planes and introduces dislocations.
  • B. Particle adhesion is a contamination problem, not slip.
  • C. A change in impurity concentration is not slip.
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More Silicon wafers questions

  1. Which is closest to the mass of one silicon wafer 300 mm in diameter and 775 µm thick? (Silicon density is about 2.33 g/cm³.)
  2. Which method has been used to make multicrystalline silicon ingots for solar cells cheaply and in large volumes?
  3. When finishing a CZ pull, why is the ingot diameter gradually reduced (a tail cone is formed) before separating it from the melt?
  4. Which is closest to the typical concentration of interstitial oxygen in silicon crystals grown by the CZ method?
  5. In the mirror polishing (final CMP polishing) of silicon wafers, what is commonly used as the abrasive in the slurry?