Lithography

What is the main cause of the stochastic fluctuations that are a problem in EUV lithography?

  1. AEUV light has a longer wavelength than ArF
  2. BEUV lithography uses lenses
  3. CEach EUV photon carries much energy, so there are fewer photons for the same dose
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Answer: C. Each EUV photon carries much energy, so there are fewer photons for the same dose

An EUV photon (13.5 nm) carries about 14 times the energy of an ArF photon (193 nm), so the number of photons delivered at the same dose is much smaller. In tiny regions, statistical variation in photon count becomes large, causing stochastic defects such as missing or bridged patterns and LER.

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More Lithography questions

  1. Why are defects buried inside the multilayer of an EUV mask a problem?
  2. What is the range of exposure dose and focus over which pattern dimensions stay within tolerance called?
  3. In LELE (litho-etch-litho-etch) double patterning, what is especially strictly required?
  4. What is the wavelength of the mercury lamp's i-line?
  5. Which technique illuminates the mask from oblique directions to improve the resolution of fine patterns?