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Transmission Grating Spectrometer for EUV Lithography

Transmission Grating Spectrometer for EUV Lithography. Nathan Gray. Advisors: Alexander Shevelko, Larry Knight, and Scott Bergeson. Student Group Members: Matthew Harrison, Jeff Kemp, Bryce Allred, Jershon Lopez. Extreme Ultraviolet (EUV). 1-1000 Å.

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Transmission Grating Spectrometer for EUV Lithography

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  1. Transmission Grating Spectrometer for EUV Lithography Nathan Gray Advisors: Alexander Shevelko, Larry Knight, and Scott Bergeson Student Group Members: Matthew Harrison, Jeff Kemp, Bryce Allred, Jershon Lopez

  2. Extreme Ultraviolet (EUV) 1-1000 Å Image modified from: NASAexplores Models of the Electromagnetic Spectrum student sheet.lot.astro.utoronto.ca/spectrum.html

  3. Extreme Ultraviolet (EUV) • Absorbed by Everything: • Air 1-1000 Å Image modified from: NASAexplores Models of the Electromagnetic Spectrum student sheet.lot.astro.utoronto.ca/spectrum.html

  4. Extreme Ultraviolet (EUV) • Absorbed by Everything: • Air • Glass 1-1000 Å Image modified from: NASAexplores Models of the Electromagnetic Spectrum student sheet.lot.astro.utoronto.ca/spectrum.html

  5. Extreme Ultraviolet (EUV) • Absorbed by Everything: • Air • Glass • Plastic 1-1000 Å Image modified from: NASAexplores Models of the Electromagnetic Spectrum student sheet.lot.astro.utoronto.ca/spectrum.html

  6. Extreme Ultraviolet (EUV) • Absorbed by Everything: • Air • Glass • Plastic • Ponies 1-1000 Å Image modified from: NASAexplores Models of the Electromagnetic Spectrum student sheet.lot.astro.utoronto.ca/spectrum.html

  7. Extreme Ultraviolet (EUV) Must operate under vacuum (our chamber is at 30-100 mtorr) • Absorbed by Everything: • Air • Glass • Plastic Must use mirrors in place of conventional optics. This makes spectroscopy in the EUV range complicated.

  8. EUV range transmission gratings:

  9. EUV range transmission gratings: Recent transmission grating development allows for EUV range gratings 200 nm period (5000 lines/mm)

  10. EUV range transmission gratings: Recent transmission grating development allows for EUV range gratings 200 nm period (5000 lines/mm) Transmission grating spectrometers are superior to reflection grating spectrometers

  11. Possible Configurations Simple Transmission Grating Spectrometer Entrance Slit Detector Grating

  12. Possible Configurations Spherical Mirror • Single Mirror Geometry Entrance Slit Detector Grating • High spectral resolution and luminosity • Mirror collects large solid angle

  13. Our Configurations Detector • Double Mirror Geometry Entrance Slit Flat Mirror Spherical Mirror Grating Designed by Dr. Alexander Shevelko

  14. Knight/Shevelko Group Spectrometer Configuration

  15. Electron Temperature StudyTungsten

  16. Efficiency Calculation Major advantage of transmission grating over reflection grating Must take transmission through wires into account (phase shift) Materials: Au 25 nm Au 25 nm Radiation Si4N3 200 nm

  17. Formulae

  18. Efficiency Calculation Fujikawa et al. Method Schopper et al. Method H. W. Schopper et al., Appl. Opt. 16, 1088 (1977). C. Fujikawa et al., Rev. Sci. Instrum. 69, 2849 (1998).

  19. Absolute Calibration grating efficiency X spherical mirror reflectivity X flat mirror reflectivity = total spectrometer efficiency

  20. Absolute Calibration grating efficiency X spherical mirror reflectivity X flat mirror reflectivity = total spectrometer efficiency total spectrometer efficiency X detector calibration = absolute calibration

  21. Absolute Calibration grating efficiency X spherical mirror reflectivity X flat mirror reflectivity = total spectrometer efficiency total spectrometer efficiency X detector calibration = absolute calibration absolute calibration = Intensity scaled to units of actual photon flux, instead of just relative intensity.

  22. Absolute Calibration grating efficiency X spherical mirror reflectivity X flat mirror reflectivity = total spectrometer efficiency total spectrometer efficiency X detector calibration = absolute calibration absolute calibration = Intensity scaled to units of actual photon flux, instead of just relative intensity. Detector calibration: completed at Lebedev Physical Institute by Oleg Yakushev

  23. EUV Lithography International Technology Roadmap for Semiconductors printable patterns with 32 nm between features are required by the semiconductor industry by 2009

  24. EUV Lithography Main limitation is wavelength of light source Higher Resolution requires a source with smaller wavelength

  25. Typical EUV wafer scanner • V. Bakshi, EUV Sources for Lithography, SPIE Press Book, 2006.

  26. EUV Lithography Typical EUV Lithography apparatus: • 11 mirror multilayer Mo/Sn multilayer mirrors with reflections around 66% each. • The overall transmission in the EUV scanner is less than 1%, • The mirrors reflect a bandwidth of 2% around a central wavelength of 135 °A.

  27. EUV Lithography Source candidates: Lithium and Tin plasmas

  28. EUV Lithography • Mirror heating • Unwanted radiation • Target purity • Plasma parameters (electron temperatures, absolute outputs, etc.)

  29. Current WRS Planned WRS with multiple gratings

  30. Acknowledgements • Dr. Shevelko • Dr. Knight • Matt Harrison and the other members of my group • The chemists (especially Dr. Asplund)

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