summary of japanese academic support program for lpp · pdf files. fujioka, t. aota, k. nagai,...
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EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Yasukazu Izawa, Katsunobu Nishihara, Hiroaki Nishimura, Masahiro Nakatsuka,Takayasu Mochizuki*, Tatsuo Okada**, Shoichi Kubodera***
Noriaki Miyanaga, and Kunioki MIma
Institute of Laser Engineering, Osaka University*Laboratory of Advanced Science and Technology for Industry, University of Hyogo
** Graduate School of Information Science and Electrical Engineering, Kyushu University*** Faculty of Engineering, Miyazaki University
Summary of Japanese Academic Support Programfor LPP EUV Source
2006 International EUVL SymposiumOctober 16 - 18, 2006, Barcelona, Spain
This work was performed under the auspices of Leading Project promoted by MEXT, JAPAN.
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Contributors
Theory and simulationH. Tanuma, H. Ohashi (Tokyo Metropolitan University)F. Koike (Kitasato University) K. Fujima (Yamanashi University) R. More, T. Kato (National Institute of Fusion Science)A. Sasaki (Advanced Photon Research Center, JAEA)M. Murakami, Y. -G. Kang ( Osaka University)A. Sunahara, H. Furukawa (Institute for Laser Technology)T. Kagawa (Nara Womens College)T. Nishikawa (Okayama University)
ExperimentsS. Fujioka, T. Aota, K. Nagai, T. Norimatsu ( Osaka University)S. Uchida, Y. Shimada, M. Yamaura, K. Hashimoto (Institute for Laser Technology)S. Miyamoto, S. Amano, E. Fujiwara (University of Hyogo)S. Namba (Hiroshima University)A. Takahashi (Kyushu University)T. Higashiguchi (Miyazaki University)
Laser developmentsH. Fujita, K. Tsubakimoto, H. Yoshida ( ILE, Osaka University)
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
MEXT project(2003 - 2007)
Objectives: EUVL system R&D
Objectives1) Understanding physics of EUV source plasma and
providing guidelines for practical EUV source design・High power and high efficiency
EUV data base (experiments and simulations)Optimization of EUV plasma (laser and target)
・Clean, debris free sourceData base on ion and neutral atom emissionSuppression of high energy ions
2) Development of new targetslow density,minimum-mass, high feed rate
3) Development of laser technology5 kW/5 kHz DPSSLcompact, high efficiency, good beam quality, long life
MEXT: Ministry of Education, Culture, Science and TechnologyMETI; Ministry of Economy, Trade and Industry
Basic research on EUV plasma is important.
METI projectEUVA
(2002 - 2007)
Collaboration
Objectives
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
EUV power : 300W at source @10 - 30kHz・Large size plasma: 400 ~ 700 μm・Low laser intensity: ~ 1011 W/cm2
・Low electron density: 1019 ~ 1021 cm-3
・Electron temperature: 20 ~ 40 eV
low density targetfoam, double pulse, punch-out
optically too thin
optimum density-depth product1
2
510
2
510
2010.6 μm
τL=pl
asm
a sc
ale
leng
th (
μm)
10
100
1000
1017 1018 1019 1020
ion number density (cm-3)
etenduelim
it1m
m2sr (Ω
=π)
1.06 μm0.53 μm0.25 μm
12
510
1ns2ns
5ns10ns
20ns
optically too thick
Design windows for high power EUV source
For Sn, selection of laser wavelength and pulse width is importantbecause of large opacity for EUV emission.
Sn plasma absorbs EUV emission.
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Tran
smis
sion
18161412108Wavelength (nm)
Te ~ 30 eV
Te ~ 0 eV
Sn
Guidelines
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Research flow to high power and efficient EUV source
Radiation hydro code
Atomic data
0 5 10 15 20
0.9x1011 W/cm2
0.9x1012 W/cm2
1x1011 W/cm2
1x1012 W/cm2
Experiment
wavelength (nm)
Simulation
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
1010 1011 1012
実 験
シミュレーション
Con
vers
ion
effic
ienc
y (%
)
Laser intensity (W/cm2)
Inte
nsity
Atomic model
Design of high power and clean EUV sourceEUV experiment
Conversion efficiency
Ele
ctro
n te
mpe
ratu
re(e
V)
Ion density (/cm3)1020
10
20
30
50
80
3%
2%
4%
101910181017
レー
ザー
強度
験
3% 実
Benchmark
Laser: I, τ, λTarget: Z, ρ,
Inte
nsity
Xe10+
Xe11+
Xe9+
8 10 12 14 16 18
4d-5p
Xe10+
Xe9+
4d-4f
By CXS
By HULLAC Code
wavelength (nm)
Benchmark
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Tran
smis
sion
18161412108Wavelength (nm)
Te ~ 30 eV
Te ~ 0 eV
Sn
Simulation
Experiment
Data base
Guidelines
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Emission spectra from charge-selected Xe and Sn ions were measured.
Charge exchange spectroscopy (CXS)Xe+q + ( He, Ar, Xe) Xe+q-1 ( n, l )
Xe+q-1 ( n’, l’ ) + hν
5 10 15 20 25 30 35 40
Inte
nsity
/ ar
b. u
nits
Wavelength / nm
q = 15
14
13
6
12
11
10
9
Snq+ - Xe
8
5
q = 7
6 12 18 24
Inte
nsity
/ ar
b. u
nits
Wavelength / nm
q = 18
17
16
15
14
13
q = 8
12
11
10
9
Xeq+ - He
4d-5f
4d-5p
4d-5p
4d-4f
13.5nm
Atomic data
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
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Atomic codes were improved by measured spectra.
12.5 13.0 13.5 14.0 14.5
CXS: Xe11+ + HeNIST: Xe10+
EUVA(DPP)
HULLAC
Cowan
Grasp
Wavelength (nm)
Atomic code
Observed peaks and HULLAC calculations
Xe
Sn
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
2D radiation hydro-code was developed.
ni
Te
< Z >
78
69
10
+200
+100
0
-100
-200
0 100 200 300 400 500 600X (μm)
Y (μm)
+200
+100
0
-100
-200
Y (μm)
+200
+100
0
-100
-200
Y (μm)
Sn plane target, laser diameter: 100μm
Radiation hydro-code
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Electron density distribution was reproduced well by 2D code.
Experiment
T=0ns(Laser peak)
T=4ns
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Radiation hydrodynamic simulation reproduces wellthe measured spectra.
Radiation hydro-code
80
60
40
20
0
Inte
nsity
(arb
. uni
t)
20151050Wavelength (nm)
40
30
20
10
0
Inte
nsity
(arb
. uni
t)
20151050Wavelength (nm)
20
15
10
5
0
Inte
nsity
(arb
. uni
t)
20151050Wavelength (nm)
Laser intensity 9 x 1010 W/cm2
Laser intensity3 x 1011 W/cm2
Laser intensity9 x 1011 W/cm2
80
60
40
20Inte
nsity
(arb
. uni
t)
20151050Wavelength (nm)
706050403020100
Inte
nsity
(arb
. uni
t)
20151050Wavelength (nm)
20
15
10
5
0
Inte
nsity
(arb
. uni
t)
20151050Wavelength (nm)
Experiment
Simulation
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Optimum conditions for high conversion were obtained.
For solid targetSn: short pulse laser (~ 2 ns), CE > 4%Xe: long pulse laser (> 10 ns), CE ~ 2%Li: long pulse laser (> 10 ns), CE ~ 4%
10
20
30
50
80
ion density [cm-3]1017 1018 1019 1020
Li 20 ns
1017 1018 1019 1020
ion density [cm-3]
10
20
30
50
80 Xe 15ns
10
20
30
50
80
1017 1018 1019 1020ion density [cm-3]
elec
tron
tem
pera
ture
[eV
]
Sn 2ns
For Sn, opacity effect is important. Low density target is better.
Data base by simulation
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
1.5x1011 W/cm2ω: 1064 nm
2ω: 532 nm4ω: 266 nm
CE
(a.u
.)
1010 1011 1012
0.2
0.4
0.6
0.8
1.0
0
532 nm252 nm
Sn
Laser intensity (W/cm2)
1064 nm
CE
(a
.u.)
CO2YAG1064nm
109 1010 1011
10
20
30Sn
Laser intensity (W/cm2)
イオ
ン電
流(a
.u.)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
CE
expe
rimen
t (%
)
10102 3 4 5 6 7
10112 3 4 5 6 7
10122
Laser intensity (W/cm 2)
2.5
2.0
1.5
1.0
0.5
0.0
CE sim
ulation (%)
1.2 ns
10 ns
2 〜 3 ns
8 〜10 ns
F/30
Laser intensity (W/cm2)
Sn2.0
1.5
1.0
0.5
Con
vers
ion
effic
ienc
y (%
)
10102 3 4 5 6 7 8
10112 3 4 5 6 7 8
1012
Laser intensity (W/cm2)
1.2 ns pulse duration 2.3 ns pulse duration 5.6 ns pulse duration 8.5 ns pulse duration
Pulse width dependenceWavelength dependence
1600
1400
1200
1000
800
600
400
200
0
Ener
gy n
orm
aliz
ed in
tens
ity
201816141210Wavelength (nm)
τ = 1.2 nsτ = 2.3 nsτ = 5.6 nsτ = 8.5 ns
For long τ, EUV emission decreases due to
self-absorption in plasma.
Sn, 1μm
Data base by experiments: Sn
For solid Sn target, opacity effect is important.
Solid Sn target: high CE for short pulse (~ns), long λ laser
Experimental results are well reproduced by simulation.
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Conversion efficiency is improved by reducing target mass-density for long pulse laser.
Nd:YAG [1064 nm, 10ns]
2 4 6 8 10 12
2.5
2.0
1.0
1.5
0.5
0
SnO 2 (23%)SnO 2 (7%)
Sn (bulk)
Laser intensity (x1010 W/cm2)
CE
(%
/2πs
r/2%
BW
)
Sn concentration: 6%wt
-200 0 200 400 6000
0.5
1
1.5
Pulse separation time (ns)
EUV
CE
(%)
single pulse
Double-pulse
Pre-pulse: 0.1 J (<1010 Wcm-2) 0.5 μmMain Pulse: 0.5 J (2 x 1011 Wcm-2) 1μm
Low-density Foam Colloidal jet containing nanoparticles(double pulse irradiation)
Double pulse irradiation is effectivefor high efficiency.
With decrease of mass-density, CE and spectral purity are improved.
Long pulse (~10ns) laser can be applicable for low density target.
Data base by experiments: Sn
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
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-200 0 200 400 6000
0.5
1
1.5
2
2.5
Delay time (ns)
CE
(%)
Pre-pulse: 60 mJ (<109 Wcm-2) 0.5μmMain Pulse: 500 mJ (7 x 1010 Wcm-2) 1μm
Conversion efficiency was measured for different laser and target conditions.
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
CE
(arb
. uni
t) (1
3.5n
m/2
%bw
)
1010 2 3 4 5 6 7 891011 2 3 4 5 6 7 89
1012 2
Laser intensity (W/cm2)
BA C D
ω 2ω 3ω
0.3J/
0.5J/
1.2J/ω
0.25-0.5J/ 0.25/
ω
3ω
ω
2ω
Spec
tral
Inte
nsity
(A.U
.)
1816141210864wavelength(nm)
f31962ω /0.5J
f2750ω /0.5J
f26903ω /0.25J (x2)
Solid Xe targetLaser Intensity=1.5x10 11
W/cm 2
13.5nm
CE
(a
.u.)
Solid Xe
Solid Li
Solid Li
ダブルパルス照射
Laser intensity (W/cm2)
Without plasma
0
0.5
1
1.5
2
2.5
3
3.5
4
0
0.05
0.1
0.15
0.2
0.25
0 1 1010 2 1010 3 1010 4 1010
EUV energyC.E.
C.E
. [%]
laser intensity [W/cmCO2
2 ]CO2 laser intensity (W/cm2)
EU
V e
nerg
y [m
J/2π
sr/2
%B
W]
Xe target: high CE by long λ laser Li target: high CE by short λ laser
Xe jet
Data base by experiments: Xe and Li
Wavelength dependence: Xe Wavelength dependence: Li
Laser intensity (W/cm2)
Double pulseirradiation
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
10-4
10-3
10-2
10-1
100
0.1 1 10
Nor
mal
ized
spe
ctru
m d
N/d
ε
Ion kinetic energy ε (keV)
Experiment
Present model
1
(α =3, ε0= 3.0 keV)
Maximum ion energy predicted by the present analytical model
103
104
105
106
Ion
num
ber
3 4 5 6 7 8 9103
2 3 4 5 6 7 8 9104
Ion energy (eV)
punch-out
slab
Sn1+ Sn2+
Sn1+
Sn2+Sn3+
Ion emission
Isothermal expansion model reproduces well ion energy distribution.
10-6
10-5
10-4
10-3
10-2
10-1
100
0.1 1 10Ion kinetic energy ε (keV)
Experiment
(α =1, ε0=1.7 keV)
Nor
mal
ized
spe
ctru
m d
N/d
ε
Present model
1
Planar target
Cylindrical target
Maximum ion energy drastically decreases for low density target.
0 1 2 3 40
2
4
6
8
10
Ion velocity (x107 cm/s)
Ion
curre
nt (a
rb. u
nits
)
Single pulse
Dual pulsesDouble pulse
irradiation
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Neutral atom: Sn
LIF(Laser Induced Fluorescence)to measure neutral atomic density of Sn
1 μm 200 nm 100 nm 60 nmPlane
Laser for plasma
Laser for excitation
Plane orthin foil
Excitationλ21 = 286.33 nm
Fluorescenceλ23 = 317.50 nm
5p2 3P2g3 = 5
6s 3P1g2 = 3
5p2 3P0g1 = 1
Energy level of atomic Sn
With reducing target thickness, almost all Sn atoms in the laser irradiated region are ionized, and fluorescence on the laser axis decreases. Fluorescence in the outer region is due to Snatoms ablated from the outer region of laser irradiation.
Importance of minimum-mass target
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Minimum-mass target
laser
Target: Sn coated sphereIntensity:1011W/cm2
Pulse width:2ns
With decrease of Sn thicknessemission to laser direction decreases,
Emission from Sn atoms
1.5
1.0
0.5
0.0
Con
vers
ion
effic
ienc
y (a
u)
5 6 7 810
2 3 4 5 6 7 8100
2 3 4 5 6 7 81000
Sn layer thickness (nm)
800
600
400
200
0
Emission intensity from
Sn(I) atoms
EUV emission
Emission from Sn atoms
40nm
Suppression of debris to C1 mirror
10nm50 nm
LASER
1300 nm
Sn0+ 452 nm
Sn coat shell500 μmφ
Coating thickness of 40 nm is enough to produce high power EUV emission. : minimum-mass target
Number of EUV photon required 〜number of ions: 30mJ/pulse 2 x 1015 ions
Emission from Sn neutrals linearly increases with coating thickness while
keeping constant EUV intensity.
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
New targets
Xe frost (low density foam) Annular jet (liquid Xe)
200µm
Li cavity orLi droplet
Recombination wall
Multi module laser
Multi module laser
Novel targets have been proposed and developed.
Low density foam (Sn)
Liquid droplet with Sn or Li Forced cooling by recombination (Li)
Punch out (tape or disc, Sn, Li)
Rotating drum (solid Xe)
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Two ways for minimum-mass Sn target
Pre-pulse
Droplet target
Main Pulse
EUV
Sn droplet
Colloidal droplet containing Sn nanoparticles
Sn jet > 1 km/s
1 mmheat laser
Minimum-mass target
# Double pulse irradiation:for 10 (100) kHz repetitionEUV energy / pulse:~ 30 (3) mJ number of Sn atoms:~ 2 x 1015 (1014)
Diameter of droplet:~ 50 (20) μm
Diameter of plasma:~ 400 (150) μm
Pre-pulse to expand plasmaMain pulseIntensity: ~1011 W/cm2
Pulse width: ~10 ns
# Punch-out target
Laser for punch-out
Base plate(transparent) Sn (1~10μm)
Heating laser
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
2 x 4 mm Rod, 2 pass
2 x 6 mm Rod, 2 pass
8 x 12 mm Rod, 2 pass
5 W
200 W
5000 W
(Regen. Amp) Fiber Front-end
SBS PC Mirror
Deformable Mirror
to Target Chamber/SBS Pulse Compression/Higher Harmonic Gen./Control of Focus Pattern
30 W
・Front end: Fiber oscillator + Fiber amplifier・Rod amplifier: Ceramic YAG, Uniform and high density pumping・Compensate for thermal effect: Image relaying and SBS PCM・System design: Simulation code (pumping, amplifier, propagation including diffraction)
1J/ 5kHz/ 5kW laser is under development.
Laser development
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Summary
・Guideline to achieve high conversion from laser to EUV radiationhas been established by the experiments and the simulation.
・For Sn plasma, opacity effect is important, and short pulse laserand low density target will be effective for high efficiency.
・High conversion efficiency was achieved.Sn: 3 % (spherical plasma), SnO2 foam: 2.5 %, Xe (solid): 1.1 %, Li: > 2%
・Minimum-mass targets were proposed.Sn droplet with double pulse irradiation and punch-out target
・5kHz/5kW laser is under development, and will be applied for high power EUV experiment.
EUVL SYMPOSIUM OCT. 16-18, 2006, Barcelona
Please visit our poster presentations.・S. Kubodera et al., Low-debris EUV source using a colloidal microjet target
containing tin dioxide nanoparticles.・T. Kagawa et al., Comparison of EUV spectra from Sn ions between theoretical
RCI simulation and experiment.・H. Nishimura et al., Laser and target optimization for the highest conversion to
13.5 nm EUV light with laser produced minimum-mass tin plasma.・A. Sasaki et al., Modeling of the atomic processes in EUVL source plasma.・T. Aota et al., Temperature and density measurement of laser-produced EUV plasmas.・A. Takahashi et al., Emission characteristics of neutral atoms and ions of laser-
produced tin plasma.・H. Tanuma et al., EUV emission spectra of charge-selected Sn ions in charge
exchange spectroscopy.・K. Tsubakimoto et al., Development of high-peak, high-average LD pumped
solid-state laser system for EUV generation.・S. Amano et al., LPP-EUV source using cryogenic Xe and lithium new scheme targets.・K. Nagai et al., Development of low-density target for highly efficient EUV generation.・K. Nishihara et al., Theoretical guidelines of LPP-EUV sources for HVM.・F. Koike et al., Systematics of atomic 4d-4f transitions of atomic ions in EUVL source
plasmas and neighboring atomic numbers.・A. Sunahara et al., Radiation hydrodynamic simulation for LPP EUV sources.
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