Lithography

How is 13.5 nm light generated in the light source of an EUV lithography tool?

  1. ABy discharge in a mercury lamp
  2. BBy wavelength-converting ArF excimer laser light
  3. CBy hitting tiny droplets of tin with a powerful laser to create plasma
Show answer and explanation

Answer: C. By hitting tiny droplets of tin with a powerful laser to create plasma

The EUV source fires a high-power CO2 laser at tens of thousands of tiny tin droplets per second, turning them into hot plasma, and collects the 13.5 nm light emitted with multilayer mirrors (the LPP method). Obtaining enough brightness stably was a major hurdle in making EUV practical.

  • A. Mercury lamps are sources of i-line and similar light.
  • B. 13.5 nm is not produced by converting ArF light.
  • C. Correct. Tin droplets are turned into plasma by a laser.
Practice this topic Back to topic

More Lithography questions

  1. What is the process called that removes, with solvent, the resist that builds up around the wafer edge after spin coating?
  2. In current scanner exposure tools, what is the typical maximum area on the wafer that can be exposed in one exposure (one shot)?
  3. Which technique uses computation to jointly optimize the illumination shape of the exposure tool and the mask pattern to improve resolution?
  4. In immersion lithography with very high numerical aperture (NA), why does light polarization need to be considered?
  5. What is the main cause of "flare", a problem in EUV lithography?