Yield and quality control

Which control chart monitors shifts in a process's mean and changes in its spread at the same time by plotting each sample group's mean and range (max − min) over time?

  1. AX̄-R chart
  2. Bp chart
  3. CPareto chart
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Answer: A. X̄-R chart

The X̄-R chart computes the mean (X̄) and range (R) for each sample group of fixed size and plots each on its own chart. The mean chart monitors shifts in the process center and the range chart monitors changes in spread. A p chart controls the defective fraction.

  • A. Correct. It monitors the mean and range together.
  • B. A p chart controls the defective fraction.
  • C. A Pareto chart is not a control chart but a chart sorting items by frequency.
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More Yield and quality control questions

  1. Which system manages which lot is at which step and tool, under what conditions it was processed and so on, directing and recording the production flow in a factory?
  2. In sampling inspection, which judges an entire lot as accepted or rejected by inspecting a sample, which metric expresses the quality level considered acceptable?
  3. When analyzing yield data, which example correctly illustrates that "a correlation between two quantities does not mean one causes the other"?
  4. Which correctly describes efforts to raise yield by analyzing the large amounts of equipment data, metrology data and test results accumulated in a fab with machine learning and similar methods?
  5. Which yield model accounts for defects that occur clustered unevenly on the wafer?