Silicon wafers

What are the very gentle undulations on a wafer surface, with lateral wavelengths of a few millimeters and heights of tens of nanometers, called?

  1. ANanotopography
  2. BNotch
  3. CSurface roughness
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Answer: A. Nanotopography

Nanotopography refers to gentle undulations with lateral extents of about 0.2 to 20 mm and heights of a few to tens of nanometers. When films are planarized by CMP, these cause film thickness to vary along the undulations, so they are tightly controlled in wafers for advanced devices.

  • A. Correct. It is gentle undulation of tens of nanometers with millimeter-scale periods.
  • B. A notch is a cut in the wafer edge.
  • C. Surface roughness is finer unevenness with shorter periods (nm to µm).
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More Silicon wafers questions

  1. Compared with FZ silicon, how does the interstitial oxygen in CZ silicon affect the wafer's mechanical strength?
  2. Which is a known effect of adding a trace of nitrogen during CZ crystal growth (nitrogen doping)?
  3. Which method selectively and shallowly etches defect regions so that dislocations and stacking faults in silicon can be observed with an optical microscope?
  4. 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?
  5. Along which crystal planes does single-crystal silicon cleave most easily?