Testing and inspection

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?

  1. ADummy gate
  2. BAlignment mark
  3. CTEG (test element group)
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Answer: C. TEG (test element group)

A TEG is a collection of simple structures such as transistors, resistors, capacitors and wiring chains for evaluating how well the process turned out. Placed in scribe lines and elsewhere, their electrical characteristics are measured to confirm that the steps were performed correctly.

  • A. Dummy gates are non-functional gates placed for processing uniformity and the like.
  • B. Alignment marks are markers for exposure alignment.
  • C. Correct. They are test patterns for process evaluation.
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More Testing and inspection questions

  1. 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?
  2. In test fixtures connecting the tester and IC, which component uses thin spring-loaded pins to make reliable contact with terminals?
  3. 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?
  4. What is the main advantage of vertical probe cards, which stand the needles perpendicular to the pads?
  5. As wafer testing continues, aluminum debris from the pads and the like accumulates on the probe tips. What is done periodically in response?