Solutions with light - EUV Litho – Promoting EUV Lithography via … · 2017-02-15 · Solutions with light ... Introduction Characterization of LPP collector substrates Multilayer

Multilayer coating for EUV collector mirrors

© Fraunhofer IOF

Solutions with light – meet challenges and offer opportunities



[email protected]

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


Contents

Introduction

Characterization of LPP collector substrates

Multilayer coating of LPP collectors

Summary and acknowledgement


Contents

Introduction





Coating and characterization of LPP collector optics

[Nature Photonics 4, 24-26 (2010)]


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


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 %


Contents

Introduction





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)


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


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)


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 %


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)


Contents

Introduction





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


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


Center wavelength along four

lines within clear aperture of

collector mirror:

l = (13.50 ± 0.03) nm


j = 0°

j = 90°

j = 180°

j = 270°



Measurement of reflectance

along four lines within clear

aperture of collector mirror:

108 measurement curves


j = 0°

j = 90°

j = 180°

j = 270°



Contents

Introduction





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)


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!

Documents

Solutions with light - EUV Litho – Promoting EUV Lithography via … · 2017-02-15 · Solutions with light ... Introduction Characterization of LPP collector substrates Multilayer