Yield and quality control

In a semiconductor fab, what is the time from wafer start to completion called?

  1. ARefresh period
  2. BCycle time (manufacturing lead time)
  3. CClock period
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Answer: B. Cycle time (manufacturing lead time)

Cycle time is the time from starting a wafer in the fab until it completes all steps, reaching several months for advanced logic. The shorter it is, the faster the response to orders and the faster the learning loop from finding a problem to confirming a fix, speeding yield improvement.

  • A. A refresh period is the DRAM data retention cycle.
  • B. Correct. It is the time from start to completion.
  • C. A clock period is the cycle of circuit operation.
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More Yield and quality control questions

  1. 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?
  2. 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?
  3. In sampling inspection, which judges an entire lot as accepted or rejected by inspecting a sample, which metric expresses the quality level considered acceptable?
  4. When analyzing yield data, which example correctly illustrates that "a correlation between two quantities does not mean one causes the other"?
  5. 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?