Lithography

What are the reference marks placed on a wafer so that each exposure can be accurately overlaid on patterns made in earlier steps called?

  1. AAlignment marks
  2. BNotch
  3. CScribe
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Answer: A. Alignment marks

Alignment marks are patterns for positioning, formed outside the chips on the wafer (for example on scribe lines). The exposure tool detects them optically and corrects for wafer position, rotation and expansion so the next layer is accurately overlaid on the previous one.

  • A. Correct. They are marks for alignment.
  • B. A notch is an edge cut indicating crystal orientation.
  • C. A scribe is the line (region) for separating chips, not the mark itself.
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More Lithography questions

  1. What does "CDU", controlled in lithography, mean?
  2. What is the material called, used to make photomasks, consisting of a quartz glass substrate pre-coated with a light-blocking film and similar?
  3. Which correctly describes writing patterns directly into resist on the wafer with an electron beam, without a mask?
  4. How is 13.5 nm light generated in the light source of an EUV lithography tool?
  5. What is the process called that removes, with solvent, the resist that builds up around the wafer edge after spin coating?