Metrology and analysis

In production-line metrology, why are only selected wafers or points often measured rather than all of them?

  1. ABecause measuring everything would destroy the product
  2. BBecause metrology tools can be used only once a day
  3. CBecause metrology costs time and money, samples are measured to the extent needed to understand process variation
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Answer: C. Because metrology costs time and money, samples are measured to the extent needed to understand process variation

Metrology consumes tool time and cost, and measuring every point on every wafer would slow production. Measurements therefore follow a sampling plan that sets how many wafers per lot and how many points per wafer to measure, matched to the nature of process variation.

  • A. Most metrology is non-destructive and does not damage product.
  • B. Metrology tools can be used continuously.
  • C. Correct. Samples are measured with time and cost in mind.
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More Metrology and analysis questions

  1. Which correctly describes observing a cross-section in detail after breaking or milling the wafer?
  2. Which pair correctly names a measuring instrument's property of "small spread when measuring the same thing repeatedly" and that of "measured values being close to the true value"?
  3. Which spectroscopic method is often used to evaluate stress (strain) in silicon locally and non-destructively?
  4. Which method is used to observe solder joint voids and wire shapes inside a package in three dimensions without destroying it?
  5. Which tool is widely used to find delamination at interfaces inside a package, such as between molding compound and chip, non-destructively?