Optimizing collector component lifetime in EUV Sn-DPP sources

A. Hassanein, J.P. Allain, V. Sizyuk, and V. Bakshi*

Argonne National Laboratory*SEMATECH

October 19, 2006Presented at the SEMATECH EUVL Source WorkshopBarcelona, Spain

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Outline:Source debris at high powerDebris mitigation systems at high powerCollector mirrors operation at high powerCollector lifetime requirementsRole of computational modeling is vital with appropriate benchmarkingIn-situ metrology (IMPACT) and modeling efforts

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4

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Source Debris Reduction

Our group studied various methods and optimization designs to increase erosion lifetime of electrode materials (i.e., feasible mitigation system, longer optics lifetime, etc.) in discharge produced plasma and laser produced plasma. These include:

– Computational models for plasma pinch dynamics, integrated with Atomic physics data and radiation transport, and plasma-material interactions

– Develop new and improved electrode materials such as advanced metallic and pseudo alloys, liquid surfaces, etc…

– Increase source efficiency by optimization of discharge dynamics, electrode-less configurations, multiple laser-beams

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Example of Gas Jet Mitigation and Example of Gas Jet Mitigation and Ion MitigationIon Mitigation

Interaction of debris with background gas and gaseous jet (left figure)Mitigation techniques applying magnetic fields

– 3D hydrodynamic interaction of debris with various mitigation systems– Debris energy and angular distribution before/after mitigation system

Combination and Integration of various mitigation systems

Rdet= 5 cm

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He Mitigation (0.5 Tesla)He Mitigation (0.5 Tesla)

Energy dependence Xe ions at DetectorFor various chamber gas densities:1·10-9, 5·10-9, 1·10-8 g/cm-3

Xe-ions Mitigation in He Jet (~5 Pa)

<E> ≈ 2170 eV<E> ≈ 221 eV<E> ≈ 127 eV <E> ≈ 251 eV

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He Mitigation (1 Tesla)He Mitigation (1 Tesla)

Angular dependence Xe ions at DetectorFor various chamber gas densities:1·10-9, 5·10-9, 1·10-8 g/cm-3

Xe-ions Mitigation in He Jet (~5 Pa)

1010

HEIGHTSHEIGHTS--EUVEUV XeXe--ions Mitigated at ions Mitigated at αα = 0= 0°° DirectionDirection

%100Amount Relative 0

0

⋅= =

=

αsource

αdetector

NN

Magnetic field >0.5 Tesla can be used effectivelyfor redirection of fast ions away from mirror surfaces

Combination of gas jet (~5Pa) & external magnetic field ~ 0.5 T can be used for effective mitigation of fast ions

Influence of the external magnetic field ~ 0.5T on EUV source pinch characteristics (size and form) needs investigation

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HEIGHTS-EUV modeling for source and debris mitigation under HVM conditions

Mitigation systems using background and/or flowing gas will introduce several effects under high-power and high-frequency operation– EUV/out-of-band radiation-induced ionization– EUV intensity reductions– Effect of impurities on plasma and pinch dynamics

Debris shields and other internal components will face other limits:– Higher erosion levels– Deposition of EUV fuel and subsequent erosion– Handling of large heat loads

Study of innovative debris mitigation systems (i.e, E- and B-fields) on EUV source plasma characteristics and performance

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IMPACT in-situ metrologies

Electron source: Auger Spec

Multiple ion sources: ion-induced mechanismsSurface analysis: LEISS, DRS

PHOIBOS HESAEnergy analysis

In-situ heating, grazing incidence

QCM-DCU: in-situ erosion data

X-ray source: XPS

EUV source: In-situ EUV reflectivity

Measurement of EUV 13.5-nm reflectivity in-situ during Sn exposure of mirrors

Inficon Quadrupolemass spectrometer (QMS)

Oxford Sci e-beam Sn evap source

Single and

Multi-layer mirror testing

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101 102 103 10410-2

10-1

100

101

Xe+ on Ru (IMPACT, 2005) Xe+ on Ru (IMPACT, 2005) Ar+ on Ru (IMPACT, 2005) Ar+ on Ru thin film (100 Angstroms, IMPACT, 2005) Sn+ on 0.5 Sn-Ru (IMPACT 2005) SIBIDET Argonne Code, Ar on Ru

Spu

tterin

g Y

ield

(ato

m /

ion)

Incident Particle Energy (eV)

Ar+,Sn+, Xe+ on RuThreshold Regime

High-energyregime

Particle-induced erosion modeling and benchmarking to IMPACT data

Energies above 1 keV sputter yields ~ 1-2 atoms/ion; damage is deeper (may be important for MLM) and the maximum erosion yield is achieved at about 8 keVAr, Sn and Xe sputter Ru similarly within 50% with thresholds below 100 eVFactor of 2-3 increase in sputtering from normal to oblique incidence at 1keV

0 10 20 30 40 50 60 700.1

1

10 IMPACT data: 1-keV Xe+ on Ru SLM TRIM-SP simulation data

Tota

l spu

tterin

g yi

eld

(ato

ms/

ion)

Incident angle (degrees)

incident angle with respect to surface normal

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Implantation of energetic Sn ions in Ru mirror surfaces

Sn+ implanted very close to the surface (top 1-1.5 nm) reaching a surface Sn equilibrium fraction of about 50% after a 1-2 x 1016 cm-2 dose (this can vary with incidence angle)

Sn ions are implanted and self-sputter; in addition they sputter Ru atoms

A very thin mixed region of Sn and Ru atoms is created with important implications to 13.5-nm reflectivity

0 500 1000 1500 20000.0

0.2

0.4

0.6

0.8

1.00.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Low-energy ion scattering data

Sn

surfa

ceno

rmal

ized

frac

tion

(a.u

.)

Time (s)

1.3 keV Sn+

Measured implantation depth (nm)

dynamic Monte Carlo code(ANL- SIBIDET)

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

Ru SLM exposed to 1.3-keV Sn+

SIBIDET

Sur

face

Sn

fract

ion

Fluence (1016 Sn ions/cm2)

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Independent measurements corroborate effect of implanted energetic Sn effect on EUV reflectivity

Left figure: XRR of Ru SLM exposed to 1-keV Sn+compared to mirror exposed to large Snvapor dose. Critical edge shows indirect evidence of mirror surface response

Right figure: In-situ at-wavelength (13.5-nm) reflectivity results of mirrors exposed to Sn for various energetic-to-thermal ratios, γ

0 5 10 15 20 25 30 350

20

40

60

80

100

Ru

γ < 0.01, Rh SLM γ < 0.01, Pd SLM

(with Sn thermal atom exposure) γ > 10, Ru SLM abs. EUV reflectivity (13.5-nm)

exp decay fit

Pd

Moderate reflectivity loss

% o

f ini

tial 1

3.5-

nm re

flect

ivity

(15-

deg)

Sn monolayers deposited (ML)

low reflectivity loss

IMD Computer Simulations(theoretical reflectivity loss)

Rh

exp decay fit

0.04 0.06 0.08 0.10 0.12 0.1410-4

10-3

10-2

10-1

100

Ref

lect

ivity

Q (1/A)

Ru SLM exposed to Sn vapor Ru 102, 2.3x1016 cm-2, 1keV Sn+

Ru 105, 0.9x1015 cm-2,1keV Sn+

Unexposed Ru SLM

critical edge for total external reflection

XRR with Cu-Kα (8-keV)

Allain and Hassanein,Miyasaki, 2004

Ex-situ

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Energetic vs thermal Sn interaction data from IMPACT

0 1 2 3 4

0 5 10 15 20 25 30 350

20

40

60

80

100

Sn Fluence (1016 cm-2)

Ru γ < 0.01, Rh SLM γ < 0.01, Pd SLM

(with Sn thermal atom exposure) γ > 10, Ru SLM abs. EUV reflectivity (13.5-nm)

exp decay fit

Pd

Moderate reflectivity loss

% o

f ini

tial r

efle

ctiv

ity(1

3.5-

nm, 1

5-de

g)

Sn monolayers deposited (ML)

low reflectivity loss

IMD Computer Simulations(theoretical reflectivity loss)

Rh

exp decay fitImplantation of energetic Sn at the surface leading to equilibrium EUV reflectivity loss

Thermal Sn does not deposit as a full layer on surface; surface morphology and structure are important

Currently investigating combined energetic and thermal Snexposure of SLM and effect on EUV reflectivity

* Sn ML deposited assumed from measured fluence

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Summary of Collector Mirror Studies in IMPACT

Experiments in IMPACT and computational modeling show that energetic Sn implants in the first 3-4 ML from the surfaceAn equilibrium Sn surface concentration is reached and varies depending on irradiation conditionsIn-situ EUV reflectivity data in IMPACT is compared to IMD modelingcode and important operating regimes are foundWhen energetic Sn particles dominate the source of debris, implantation mechanisms are in effect and 13.5-nm reflectivity reaches a steady state level of <10% loss up to 3-5 x 1016 cm-2 Sn doseWhen thermal Sn particles dominate the source of debris, deposition is the dominant mechanism and surface morphology and microstructurebecomes critical to 13.5-nm reflectivity performance. Losses range between 20-40% for a given Sn dose but still lower loss than theoretically predicted.For higher thermal Sn dose, the performance of Sn-deposited mirror surfaces approaches the theoretical value of more than 60% reflectivity loss.

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Acknowledgements

Our sponsors: Sematech and Intel Corporation

Our Collaborators:

– Xtreme Technologies

– Philips EUV

– ASML

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Advanced Computational Modeling of Mirror Surfaces exposed to conditions in EUVL sources

Advanced modeling coupled to fundamental experimental data in IMPACT and EUV source devices can lead to new mirror surface designs with superior performance

Ar on Ru atomistic simulations showing sputter thresholds between 25 and 35 eV for normal incidence

Monte Carlo dynamic surface codes model implantation of Sn as function of dose and demonstrate that Sn self-sputter leading to equilibrium concentrations of Sn ~ 50-60% at near surface region ~3-5 ML: This has been confirmed with experiments in IMPACT.

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Combined energetic and thermal Sn exposure measured in IMPACT

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

20406080

100

Ru 211, 1keV at normal incidence Pd 316, 1keV at normal incidence Rh 323, 1keV, normal inc. Ru 321 (energetic and thermal Sn, γ ~ 0.3)

1.3-keV Sn+ (normal incidence) on Ru, Rh, Pd%

Initi

al re

flect

ivity

(13.

5-nm

, 15-

deg)

γ = Rion/Rth

0.0

0.2

0.4

0.6

0.8

1.0

Sn fluence (1016 Sn+/cm2)

Sn

atom

ic fr

actio

n

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Surface roughness effects on EUV reflectivity from grazing incidence mirrors

110 120 130 140 150 160 1700.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

For energy ranges studied in IMPACT (0.5-5 keV) under heavy-ion bombardment, surface roughness varies only on the atomic scale: 0.2-nm up to 1.0-nmThis surface roughness range is only a 2-3% effect on EUV reflectivity

0.1-nm rms σ 0.5-nm 1.0-nm 2.0-nm 3.0-nm 4.0-nm 5.0-nm 6.0-nm 10.0-nm

Ref

lect

ivity

Wavelength (Angstroms)

10 degrees incidence20-nm Ru SLM

rms surface roughness

13.5-nm