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Metrology by pupil imaging Mike Adel, March 2014

Metrology by pupil imaging Mike Adel, March 2014. Outline. The pupil Animal kingdom Optics Pupil imaging Optical architecture The Fourier domain Overlay metrology by pupil imaging What is overlay? Target architecture Quantification. Evolution has generated diversity in pupil structure.

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Metrology by pupil imaging Mike Adel, March 2014

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  1. Metrology by pupil imagingMike Adel, March 2014

  2. Outline • The pupil • Animal kingdom • Optics • Pupil imaging • Optical architecture • The Fourier domain • Overlay metrology by pupil imaging • What is overlay? • Target architecture • Quantification

  3. Evolution has generated diversity in pupil structure.

  4. The pupil means many things Exposure vs Depth of field

  5. What happens when we put the image sensor in the pupil?

  6. confidential Field imaging architecture Fiber from source Image Sensor BS pupil Illumination Field Stop Mirror Objective Target

  7. confidential Pupil imaging architecture Pupil image Sensor Fiber from source CFS Apodizer (spatial filter) Apodizer (spatial filter) IFS BS Mirror Objective Target

  8. What is overlay metrology and why is it important? Scanner wavelength [nm] Very Tight (Ångstrom level) Position Control

  9. S-1 S+1 S0 Overlay metrology is enabled by quantification of symmetry breaking. Pupil imaging Field imaging F0 -F0 Translational Symmetry Rotational Symmetry Pupil image

  10. It’s all about diffraction θ d dSinθ = m λ

  11. For zero offset, first orders are symmetric. I+ Y1 X1 I0 X2 Y2 I_ Ax1 = I_- I+

  12. With 4 cells, overlay can be measured in x & y Y1 X1 X2 Y2

  13. Summary F0 -F0 • The pupil has many meanings and uses in optics. • The pupil is also a location in the optical path which enables the image to be viewed in the Fourier domain. • Overlay metrology is enabled by pupil imaging of overlaid periodic structures. • Translational offsets between periodic structures are required in order to quantify symmetry breaking in the pupil image.

  14. Thank You Acknowledgements: Thanks to Mark Ghinovker for DFTs…

  15. UP Shorter wavelength = higher resolutionEvolution of lithography light sources Mercury lamp & power supply ~$5k Circa 1985 Excimer Laser & beamline ~$500k Circa 2005 EUV light source ~ 5m$? Circa 2015? Tungsten filament light source & power supply ~$500 Circa 1965 EUV KrF G-Line ArF What happens in the meantime? H-Line I-Line 13.5

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