Lithography

What does "CDU", controlled in lithography, mean?

  1. AThe supply voltage of the exposure tool
  2. BThe variation of pattern dimensions (CD) across the wafer or within a shot
  3. CThe uniformity of resist color
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Answer: B. The variation of pattern dimensions (CD) across the wafer or within a shot

CD (critical dimension) refers to important dimensions such as line widths, and CDU (CD uniformity) expresses how much they vary. CD variation translates directly into variation in transistor characteristics, so exposure dose, focus and resist processing conditions are tightly controlled to keep it small.

  • A. It is not a supply voltage.
  • B. Correct. It is the variation in dimensions.
  • C. It is not color uniformity.
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More Lithography questions

  1. What is the material called, used to make photomasks, consisting of a quartz glass substrate pre-coated with a light-blocking film and similar?
  2. Which correctly describes writing patterns directly into resist on the wafer with an electron beam, without a mask?
  3. How is 13.5 nm light generated in the light source of an EUV lithography tool?
  4. What is the process called that removes, with solvent, the resist that builds up around the wafer edge after spin coating?
  5. In current scanner exposure tools, what is the typical maximum area on the wafer that can be exposed in one exposure (one shot)?