Testing and inspection

What is the inspection called that measures TEG parameters such as threshold voltage and sheet resistance on wafers that have completed front-end processing, to confirm the process met specifications?

  1. AWAT (wafer acceptance test) / parametric test
  2. BFinal test
  3. CBurn-in
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Answer: A. WAT (wafer acceptance test) / parametric test

WAT measures the electrical parameters of TEGs (threshold voltage, on-current, sheet resistance, contact resistance and so on) after front-end processing is complete. Wafers out of specification do not proceed, and the data are also used to monitor and improve the process. Its purpose differs from tests of chip functionality.

  • A. Correct. It checks process results through parameters.
  • B. Final test judges finished products after packaging.
  • C. Burn-in is a stress test to remove early failures.
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More Testing and inspection questions

  1. In test fixtures connecting the tester and IC, which component uses thin spring-loaded pins to make reliable contact with terminals?
  2. What is the printed circuit board called that attaches to the tester's test head, carries the IC socket and peripheral components and routes signals to the IC for each product?
  3. What is the main advantage of vertical probe cards, which stand the needles perpendicular to the pads?
  4. As wafer testing continues, aluminum debris from the pads and the like accumulates on the probe tips. What is done periodically in response?
  5. What is the purpose of enabling a prober's wafer stage (chuck) to be controlled to high or low temperature?