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Metrology by pupil imaging Mike Adel, March 2014.

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Presentation on theme: "Metrology by pupil imaging Mike Adel, March 2014."— Presentation transcript:

1 Metrology by pupil imaging Mike 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 6 confidential Field imaging architecture Illumination Field Stop Fiber from source Image Sensor Objective Target BS Mirror pupil

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

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

9 9 Overlay metrology is enabled by quantification of symmetry breaking. Field imaging Pupil imaging S0S0 S +1 S -1 Pupil image -F 0 F0F0 Rotational Symmetry Translational Symmetry

10 It’s all about diffraction θ d dSinθ = mλ

11 For zero offset, first orders are symmetric. I+I+ I_ I0I0 A x1 = I_- I + X1 X2Y2 Y1

12 With 4 cells, overlay can be measured in x & y X1 X2Y2 Y1

13 Summary  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. -F 0 F0F0

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

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

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