Yield and quality control

What is the quantity called that, for each type of defect found by inspection, gives the fraction of chips containing that defect that actually fail electrically?

  1. AAspect ratio
  2. BSelectivity
  3. CKill ratio
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Answer: C. Kill ratio

The kill ratio is the fraction of chips with a given type of defect that fail at test. Whether a defect is fatal depends on its type, size and layer, so finding kill ratios shows which defects to prioritize and also allows yield to be predicted from inspection data.

  • A. Aspect ratio is the ratio of depth to width.
  • B. Selectivity is a ratio of etch rates.
  • C. Correct. It is the fraction of defects that actually cause failures.
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More Yield and quality control questions

  1. Which correctly states Little's law, relating work in progress (WIP), throughput and cycle time in a factory?
  2. What is the analysis called that statistically identifies, from the manufacturing histories of many lots, the tools, chambers, materials and the like commonly used by low-yield lots?
  3. Which statistical process control technique monitors several mutually correlated characteristics together, rather than one at a time, to detect abnormal combinations?
  4. When there are several tools of the same type, what is it called to adjust and manage them so that processing results differ little between tools and chambers?
  5. A wafer yields 500 chips, of which 450 are good. What is the yield of this wafer?