Testing and inspection

As wafer testing continues, aluminum debris from the pads and the like accumulates on the probe tips. What is done periodically in response?

  1. AThe probe tips are cleaned, for example with an abrasive sheet
  2. BThe needles are oiled
  3. CThe needles are bent
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Answer: A. The probe tips are cleaned, for example with an abrasive sheet

Debris and oxide on the tips raise contact resistance, preventing accurate measurement and causing good chips to be judged defective. After testing a set number of chips, the tips are therefore scrubbed on an abrasive sheet or similar to clean them and stabilize contact.

  • A. Correct. The tips are cleaned periodically.
  • B. Oil would cause poor contact and contamination.
  • C. Bending the needles would prevent proper contact.
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More Testing and inspection questions

  1. What is the purpose of enabling a prober's wafer stage (chuck) to be controlled to high or low temperature?
  2. In logic testing, which pair correctly names the test that exhaustively detects structural faults (such as stuck-at faults) using scan and similar, and the test that checks function as in actual operation?
  3. What is it called when good chips are judged defective and discarded because test limits are too strict or measurements are unstable?
  4. In memory testing, what is the main purpose of making a map recording which bits at which addresses failed?
  5. When compressing scan test outputs, why must signals whose value (0 or 1) is undetermined in simulation (unknowns, X) be removed?