Lithography

Based on the resolution formula R = k1 × λ / NA, how can resolution be improved (R made smaller)?

  1. AShorten the exposure wavelength and increase the numerical aperture (NA)
  2. BLengthen the exposure wavelength and decrease NA
  3. CLengthen the exposure wavelength and increase NA
Show answer and explanation

Answer: A. Shorten the exposure wavelength and increase the numerical aperture (NA)

Since R = k1 × λ / NA, a smaller R needs a shorter wavelength λ and a larger numerical aperture NA. Exposure light sources have moved to shorter wavelengths: g-line (436 nm), i-line (365 nm), KrF (248 nm), ArF (193 nm) and EUV (13.5 nm). ArF immersion lithography fills the space between lens and wafer with water to raise NA above 1.

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More Lithography questions

  1. What wavelength of light is used in EUV lithography?
  2. Which correctly describes positive photoresist?
  3. Which correctly describes ArF immersion lithography?
  4. Which correctly describes double patterning (multiple patterning)?
  5. How does the depth of focus (DOF) generally change when the numerical aperture (NA) of an exposure tool is increased?