Testing and inspection

In wafer testing, where on the chip do the probe card needles make contact?

  1. AOn top of transistor gates
  2. BOn the chip's electrode pads
  3. COnly at the center of the wafer's back
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Answer: B. On the chip's electrode pads

In wafer testing, the many needles of a probe card contact electrode pads arranged around each chip, and the tester applies power and signals and measures the responses. The pads are the same electrodes later used for wire bonding or bump connections.

  • A. Transistor gates lie beneath the wiring layers and cannot be probed directly.
  • B. Correct. The needles contact the electrode pads.
  • C. The wafer back alone cannot connect to each circuit terminal.
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More Testing and inspection questions

  1. What is the basic method for judging whether a chip is good in logic circuit testing?
  2. In testing, what is the set of sequences of 0 and 1 signals applied to a chip's inputs, together with the expected responses, called?
  3. What are the dedicated patterns called, placed between chips on the wafer (in scribe lines) and elsewhere, used to measure characteristics of transistors, resistors and the like to evaluate the process?
  4. 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?
  5. In test fixtures connecting the tester and IC, which component uses thin spring-loaded pins to make reliable contact with terminals?