Multilayer coating for EUV collector mirrors. Solutions with light. meet challenges and offer opportunities. Fraunhofer IOF

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1 Solutions with light meet challenges and offer opportunities Fraunhofer IOF

2 Multilayer coating for EUV collector mirrors 2011 International Workshop on EUV and Soft X- Ray Sources Hagen Pauer, Marco Perske, Sergiy Yulin, Marcus Trost, Sven Schröder, Angela Duparré, Torsten Feigl, Norbert Kaiser Fraunhofer IOF Angewandte Optik und Feinmechanik Jena, Germany Dublin, November 9 th, 2011 hagen.pauer@iof.fraunhofer.de

3 Contents Introduction Characterization of LPP collector substrates Multilayer coating of LPP collectors Summary and acknowledgement

4 Contents Introduction Characterization of LPP collector substrates Multilayer coating of LPP collectors Summary and acknowledgement

5 Coating and characterization of LPP collector optics [Nature Photonics 4, (2010)]

6 LPP collector coating challenges Multilayer coating for EUV collector mirrors R > 65 % l = (13.5 ± 0.03) nm Dd = nm = 15 pm Diameter: > 660 mm Lens sag: > 150 mm Tilt: Weight: > 45 deg > 40 kg

7 LPP collector coating challenges Multilayer coating for EUV collector mirrors R > 65 % l = (13.5 ± 0.03) nm + 25 % ± 15 pm Dd = nm = 15 pm Diameter: > 660 mm Lens sag: > 150 mm Tilt: Weight: > 45 deg > 40 kg > 660 mm

8 Contents Introduction Characterization of LPP collector substrates Multilayer coating of LPP collectors Summary and acknowledgement

9 Surface characterization of EUV collector substrates No robust roughness data available Complex geometry Required roughness sensitivity New approach: Roughness characterization through light scattering measurements at l = 405 nm Non-contact Fast, robust High sensitivity Information about roughness, defects, homogeneity, Light scattering measurements (IOF instrument Albatross) Superior characterization method for EUV collector mirrors before coating

10 ARS (sr -1 ) Multilayer coating for EUV collector mirrors The basics: Scatter modeling of EUV multilayer coatings AFM measurements + modeling of roughness evolution Angle resolved scattering at l = 13.5 nm EUV scatterometer at IOF (MERLIN) General model (substrate + thin film roughness) Intrinsic thin film roughness only (perfect substrate) Substrate roughness only (perfect coating) Measurement Separate effects of substrate and thin film ML Roughness enhancement of ML = f(substrate roughness) s ( ) Influence of substrate roughness becomes dominant if HSFR > 0.1 nm Important basis for prediction of EUV performance of given substrate before coating M. Trost et al., Influence of the substrate finish and thin film roughness on the optical performance of Mo/Si multilayers, Applied Optics (2011)

11 est. HSFR (nm) PSD (nm 4 ) Multilayer coating for EUV collector mirrors HSFR mapping from ARS measurements sample 1 sample PSD analysis sample position 1 sample position 2 extrapolation HSFR=1.07 nm HSFR=0.14 nm f (µm -1 ) Perfect fractal behavior at smooth and rough areas Prediction of performance at 13.5 nm based on detailed roughness information (PSD, HSFR)

12 pred. R (%) measured R (%) Multilayer coating for EUV collector mirrors Prediction based on roughness data obtained from scattering (before coating) Reflectance measurements at PTB, Berlin (after coating) sample 1 sample 2 sample 1 sample Reflectance drops to 35 % Good correlation between predicted and experimental data Accuracy of average predicted reflectance < 1%

13 j=100 j=80 j=120 j=60 j=140 j=160 j=180 j=200 j=40 j=20 j=0 est. HSFR (nm) 0.7 j= Fast data acquisition: mapping of entire sample surface (100% characterization) High sensitivity to roughness (average HSFR = 0.1 nm) j=220 j= j=240 j=260 j=280 j=300 R=305 mm Thorough characterization of collector substrate before coating Check for homogeneity and defects

14 Contents Introduction Characterization of LPP collector substrates Multilayer coating of LPP collectors Summary and acknowledgement

15 NESSY New EUV Sputtering System Design and realization of an EUV sputtering system Conception: magnetron sputtering of rotating and fast spinning substrates up to Ø 665 mm four deposition targets deposition of graded multilayers on curved substrates

16 Reflectivity of LPP collector mirror Multilayer coating for EUV collector mirrors j = 180 j = 90 j = 270 j = 0 Maximum reflectance along four lines within clear aperture of collector mirror: R ~ r < 240 mm R ~ r = mm Measurements: PTB Berlin

17 Reflectivity of LPP collector mirror Multilayer coating for EUV collector mirrors j = 180 j = 90 j = 270 j = 0 Center wavelength along four lines within clear aperture of collector mirror: l = (13.50 ± 0.03) nm Measurements: PTB Berlin

18 Reflectivity of LPP collector mirror Multilayer coating for EUV collector mirrors j = 180 j = 90 j = 270 j = 0 Measurement of reflectance along four lines within clear aperture of collector mirror: 108 measurement curves Measurements: PTB Berlin

19 Contents Introduction Characterization of LPP collector substrates Multilayer coating of LPP collectors Summary and acknowledgement

20 Summary Characterization of EUV collector optics: - development of light scattering techniques for HSFR substrate characterization - predict EUV reflectance before coating Multilayer coating of EUV collector optics: - R > 65 % and d-spacing accuracy of Dd < 15 pm on world s largest EUV multilayer mirror (Ø > 660 mm)

21 Acknowledgements Cymer for LPP source development: Norbert Böwering, Kevin Cumming, Bruno La Fontaine, David Brandt, Igor Fomenkov, Alex Ershov, Kay Hoffmann and many others PTB Berlin team for EUV reflectivity measurements: Frank Scholze, Christian Laubis, Christian Buchholz, Annett Kampe Jana Puls, Christian Stadelhoff, Martin Biel EUV project Fraunhofer IOF: Christoph Damm, Andreas Gebhardt, Tobias Herffurth, Christina Hüttl, Robert Jende, Thomas Müller, Viatcheslav Nesterenko, Michael Scheler, Thomas Peschel, Stefan Risse, Sebastian Scheiding, Christoph Schenk, Ronald Schmidt, Mark Schürmann, Uwe Zeitner

22 Multilayer coating for EUV collector Thank mirrors you!