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Multilayer coating for EUV collector mirrors
© Fraunhofer IOF
Solutions with light – meet challenges and offer opportunities
Multilayer coating for EUV collector mirrors
Multilayer coating for EUV collector mirrors
Fraunhofer IOF Angewandte Optik und Feinmechanik Jena, Germany
Dublin, November 9th, 2011
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
Multilayer coating for EUV collector mirrors
Contents
Introduction
Characterization of LPP collector substrates
Multilayer coating of LPP collectors
Summary and acknowledgement
Multilayer coating for EUV collector mirrors
Contents
Introduction
Characterization of LPP collector substrates
Multilayer coating of LPP collectors
Summary and acknowledgement
Multilayer coating for EUV collector mirrors
Coating and characterization of LPP collector optics
[Nature Photonics 4, 24-26 (2010)]
Multilayer coating for EUV collector mirrors
LPP collector coating challenges
R > 65 %
l = (13.5 ± 0.03) nm
Dd = 0.015 nm = 15 pm
Diameter: > 660 mm
Lens sag: > 150 mm
Tilt: > 45 deg
Weight: > 40 kg
Multilayer coating for EUV collector mirrors
LPP collector coating challenges
R > 65 %
l = (13.5 ± 0.03) nm
Dd = 0.015 nm = 15 pm
Diameter: > 660 mm
Lens sag: > 150 mm
Tilt: > 45 deg
Weight: > 40 kg
± 15 pm
> 660 mm
+ 25 %
Multilayer coating for EUV collector mirrors
Contents
Introduction
Characterization of LPP collector substrates
Multilayer coating of LPP collectors
Summary and acknowledgement
Multilayer coating for EUV collector mirrors
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, …
Superior characterization method for EUV collector mirrors before coating
Light scattering measurements (IOF instrument
Albatross)
Multilayer coating for EUV collector mirrors
AFM measurements + modeling
of roughness evolution
Angle resolved scattering at l = 13.5 nm
EUV scatterometer
at IOF (MERLIN)
The basics: Scatter modeling of EUV multilayer coatings
Separate effects of substrate and thin film ML
Roughness enhancement of ML = f(substrate roughness)
Influence of substrate roughness becomes dominant if HSFR > 0.1 nm
M. Trost et al., “Influence of the substrate finish and thin film roughness on the optical performance of Mo/Si multilayers,“ Applied Optics (2011)
Important basis for prediction of EUV performance of given substrate before coating
-30 -20 -10 0 10 20 3010
-4
10-3
10-2
10-1
100
101
102
103
104
AR
S (
sr-1
)
s (°)
General model (substrate + thin film roughness)
Intrinsic thin film roughness only
(perfect substrate)
Substrate roughness only
(perfect coating)
Measurement
Multilayer coating for EUV collector mirrors
est.
HS
FR
(n
m)
sample 1 sample 2
0.7
0.5
0.3
0.1
0.6
0.4
0.2
0.1 1 10 10010
-1
101
103
105
107
PS
D(n
m4)
f (µm-1
)
position 1
position 2
extrapolation
HSFR=0.14 nm
HSFR=1.07 nm
sample 1sample 2extrapolation
HSFR mapping
from ARS measurements PSD analysis
Perfect fractal behavior at smooth and rough areas
Prediction of performance at 13.5 nm based on detailed roughness
information (PSD, HSFR)
Multilayer coating for EUV collector mirrors
sample 1 sample 2 sample 2
pre
d.
R (
%)
me
asure
d R
(%
)
65 65
55 55
45 45
35 35
60 60
50 50
40 40
sample 1
Prediction based on roughness data
obtained from scattering (before coating)
Reflectance measurements
at PTB, Berlin (after coating)
Good correlation between predicted and experimental data
Accuracy of average predicted reflectance < 1%
Reflectance drops to 35 %
Multilayer coating for EUV collector mirrors
est. HSFR (nm)
0.7
0.5
0.3
0.1
0.6
0.4
0.2
j=0°
j=20°
j=60°
j=100°
j=140°
j=180°
j=220°
j=40°
j=80°
j=120°
j=160°
j=200°
j=240°
j=280°
j=300°
j=260°
j=320°
j=340°
R=305 mm
Thorough characterization of collector substrate before coating
Check for homogeneity and defects
Fast data acquisition: mapping of
entire sample surface (100%
characterization)
High sensitivity to roughness
(average HSFR = 0.1 nm)
Multilayer coating for EUV collector mirrors
Contents
Introduction
Characterization of LPP collector substrates
Multilayer coating of LPP collectors
Summary and acknowledgement
Multilayer coating for EUV collector mirrors
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
Multilayer coating for EUV collector mirrors
Maximum reflectance along four
lines within clear aperture of
collector mirror:
R ~ 65% @ r < 240 mm
R ~ 62% @ r = 250 … 320 mm
Measurements: PTB Berlin
j = 0°
j = 90°
j = 180°
j = 270°
Reflectivity of LPP collector mirror
Multilayer coating for EUV collector mirrors
Center wavelength along four
lines within clear aperture of
collector mirror:
l = (13.50 ± 0.03) nm
Measurements: PTB Berlin
j = 0°
j = 90°
j = 180°
j = 270°
Reflectivity of LPP collector mirror
Multilayer coating for EUV collector mirrors
Measurement of reflectance
along four lines within clear
aperture of collector mirror:
108 measurement curves
Measurements: PTB Berlin
j = 0°
j = 90°
j = 180°
j = 270°
Reflectivity of LPP collector mirror
Multilayer coating for EUV collector mirrors
Contents
Introduction
Characterization of LPP collector substrates
Multilayer coating of LPP collectors
Summary and acknowledgement
Multilayer coating for EUV collector mirrors
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)
Multilayer coating for EUV collector mirrors
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 team @ 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
Multilayer coating for EUV collector mirrors Thank you!