Silicon wafers

To analyze metal contamination on a wafer surface with high sensitivity, which preparation method dissolves the surface oxide with hydrofluoric acid vapor and collects it in a droplet for analysis?

  1. AFour-point probe
  2. BSEM observation
  3. CVPD (vapor phase decomposition)
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Answer: C. VPD (vapor phase decomposition)

VPD (vapor phase decomposition) uses HF vapor to decompose the native oxide on the wafer surface and gathers the surface metal impurities into a droplet. Analyzing the collected liquid with ICP-MS or similar allows trace metal contamination over the whole wafer to be measured with high sensitivity.

  • A. The four-point probe measures resistivity.
  • B. SEM shows surface shape and is not suited to quantifying trace metals.
  • C. Correct. Surface contamination is gathered into a droplet for analysis.
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More Silicon wafers questions

  1. What are the very gentle undulations on a wafer surface, with lateral wavelengths of a few millimeters and heights of tens of nanometers, called?
  2. Compared with FZ silicon, how does the interstitial oxygen in CZ silicon affect the wafer's mechanical strength?
  3. Which is a known effect of adding a trace of nitrogen during CZ crystal growth (nitrogen doping)?
  4. Which method selectively and shallowly etches defect regions so that dislocations and stacking faults in silicon can be observed with an optical microscope?
  5. 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?