Post on 18-Jul-2020
2012 International Workshop on EUV and Soft X-Ray Sources
October 11th, 2012, UCD, Dublin, Ireland
Takeshi Higashiguchi1
1Utsunomiya University 2Nagaoka University of Technology 3HiLASE Project, Institute of Physics AS, Czech Republic 4University College Dublin (UCD)
Takamitsu Otsuka1, Weihua Jiang2, Akira Endo3, Thomas Cummins4,
Colm O’Gorman4, Bowen Li4, Deirdre Kilbane4, Padraig Dunne4, and
Gerry O'Sullivan4
Session 11, S11
Plasma-based UTA Emission in BEUV
& Water Window Spectral Regions
XUV & EUV sources
- Compact discharge 40-nm source
- 13.5-nm high brightness sources
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Wavelength (nm)
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Wavelength (nm)
150 ps10 ns
BEUV & WW-SXR sources
- BEUV sources at 6.X nm
- Water window SXR sources
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15000
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.)
Figure 2: Takeshi Higashiguchi et al.
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Experimental result700 eV
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0.20190 eV
(a)
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Wavelength (nm)
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From Banine presentation shows as follows:
(1) extensive (beyond 8 nm@~2017)
(2) 6.X nm choice: Best transmission & Easier Manufacturing
(3) Source: New fuel is needed (Gd and/or Tb, other???)
(4) R ~ 80% (cal), R ~ 40% (exp)@La/B4C MLM
(5) Optical throughput for 6.7 nm & 13.5 nm is comparable!!!
Why 6.X nm EUV source? Beyond EUV (BEUV) source
Another material plasmas UTA emission from high-Z plasma
Various target emissions
Introduction…
from previous presentation
S. S. Churilov et al., Phys. Scr. 80, 045303 (2009).
6.7 nm: Gd, Tb plasmas Mo/B4C mirror
gf spectra & ionic population We confirm the UTA resonant lines around 6.7 nm
6.0 6.5 7.0 7.5 8.00
70
70
70
70
70
70
70Gd
12+
Gd13+
Gd14+
Gd15+
Gd16+
Gd17+
Gd18+
Wavelength (nm)
gf
6.0 6.5 7.0 7.5 8.00
35
35
35
35
35
35
35Gd
19+
Gd20+
Gd21+
Gd22+
Gd23+
Gd24+
Gd25+
Wavelength (nm)
T. Otsuka et al., Appl. Phys. Lett. 97, 111503 (2010).
B. Li et al. Appl. Phys. Lett. 99, 231502 (2010).
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nsity (
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Wavelength (nm)
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Wavelength (nm)
Gd
Tb
Gd and/or Tb plasmas for 6.X nm
Feasibility study for 6.X-nm sources
Feasibility study for 6.X-nm sources
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Wavelength (nm)
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Wavelength (nm)
Gd
Tb
Which wavelengths at 6.X nm?
Tb Gd
6.67 nm@LaN/B MLM
B. Li et al. Appl. Phys. Lett. 101, 013112 (2012).
Complex target (proposal, preliminary)
• Max MLM reflectivity peak lies between the peaks of Gd and Tb
- Bowen et al., APL 101, 013112 (2012)
• Gd – 6.76 nm LaNB4C – 6.66 nm
• Tb – 6.5 nm LaNB – 6.63 nm
• Gd/Tb mix plasma could yield higher in band emission
• Wavelength “Tuning” may be possible
• Atomic calculations coupled with CR code
O’ Gorman et al. – in preparation
1064 nm,
150ps
•T =150 ps
•Spectral profile shows higher in band
emission
•Dual laser plasma
•Higher temperature and more absorption
•Emission has higher spectral purity than Gd & Tb
Solid complex target
Low-density complex target
1064 nm,
150ps
1064 nm,
10 ns Gd/Tb
Gd/Tb Gd/Tb
Form Gd/Tb Target with 30% initial density
Similar results with reduced absorption
Other plasma: Phosphorus
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• Phosphorus spectra observed using 10 ns Nd:YAG laser, φ = 7x1011 W/cm2
• Line emission observed in 6.5-6.8 nm region due to 2p5 – 2p43d transitions of P6+ and 2p4 – 2p33s transitions of P7+ ions
• Wavelength of line emission appears better matched to in-band of MLM than Gd and Tb UTA
6.2 6.4 6.6 6.8 7 7.2 7.40
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Wavelength (nm)
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P spectrum
Gd spectrum
MLM in-band 6.656 nm
T. Cummins et al. (In preparation)
* Gd spectrum taken from C. O’Gorman et al Appl. Phys. Lett. 100, 141108 (2012)
* Tb spectrum taken from S. S. Churilov et al Phys. Scr. 80 (2009)
6.2 6.4 6.6 6.8 7 7.2 7.40
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Wavelength (nm)
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nsity (
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P spectrum
Tb spectrum
MLM in-band 6.63 nm
Line emission from Phosphorus plasma
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0.5
1
Electron temperature (eV)
Ion
po
pu
latio
n
0 20 40 60 800
5
10
15
Ave
rag
e io
niz
atio
n <
Z>
1+
11+
10+7+6+5+3+
2+ 4+
9+8+
• FLYCHK code calculates ion population states and average ionization as a function of electron temperature
• Optimum electron temperature to achieve P6+-P7+ is around 30 eV, comparable to existing requirement for Sn, and lower than > 140 eV for Gd and Tb
• Normalised in-band measurements show peak emission at around 7x1011 W/cm2
1011
1012
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Laser intensity (W/cm2)
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CE for 6.63 nm MLM
CE for 6.656 nm MLM
T. Cummins et al. (In preparation)
Line emission from Phosphorus plasma
Optimum electron temperature: 110 eV
CO2 laser intensity:
2.4 × 1011 W/cm2
B. Li et al. Appl. Phys. Lett. 99, 231502 (2010).
Development of hybrid laser
CO2 laser-produced plasma behavior? - Low density, high temperature plasma
Etendue - Expanding plasma size depends on temperature
- Incident angle to 0.6%BW MLM at 6.X nm
- etc…
Low density & 100-eV plasmas
CO2 laser-produced Sn plasma
Y. Ueno et al. Appl. Phys. Lett. 91, 231501 (2007).
CE is expected to be 1.5% at the bandwidth of 0.6% for 6.X-nm BEUV.
2011 EUV Sources Workshop Nov 7-10 Dublin 7
Experiments on LPP with CO2 laser C
E, %
EUV (hole)
EUV (flat target)
CO2 laser
EUV (large hole) In
ten
sity,
a.u
.
3 shots 4 shots 5 shots 7 shots
View of holes in 80 Gd foil after
defined number of laser shots
Target – Gd foil 80 thick
Laser energy 600 mJ
Laser spot dia. 300
Pulse duration 100 ns
Pow. density ~1010 W/cm2
CO2 laser-produced Gd plasma at ISAN
CEs are comparable under 2%BW Gd and Tb have the similar property due to Dn = 0 UTA emission
EUV CEs
(in 2% BW)
1064 nm: 1.1%
532 nm: 0.7%
355 nm: 0.5%
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Wavelength (nm)
1064 nm532 nm355 nm
Spot diameter: 50 um (FWHM)
Laser energy: 320 mJ
Laser intensity: 1.6 x 1012 W/cm2
T. Otsuka et al., APL 97, 111503 (2010).
T. Otsuka et al., APL 97, 231503 (2010).
Next step: short CO2 laser installation sub-ns 10-Hz hybrid 10.6-um laser development
Palitra Optical Parametric Amplifier Tuning Curves
Wavelength (nm)1000 10000
Co
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(%
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UV3
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UV1
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VIS1
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IR1
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IR3
Typical Efficiencies with Quantronix Amplifier System, Pulse Duration 70-200 fsCO2 laser
20 uJ (160 uJ)
Expected:
160 mJ
Summary fro 6.x-nm BEUV
We have demonstrated the efficient EUV sources
- Numerical evaluation of Gd and Tb (by Li, Kilbane & O’Sullivan)
- Proposal of mixing target for MLM (by O’Gorman & Otsuka)
- P plasma for low-temp plasma (by Cummins & Otsuka)
- Hybrid laser system (by Otsuka, Sakaue, Miura & Endo)
Our objective is a demonstration of high-brightness, high energy EUV/soft x-
ray source in water window (3.2 nm) for the first time in the world!!!
Multilayer
mirror
Laser
Plasma light source
Soft X-ray CCD
Biological sample
EUV
Pinhole
Schwarzchild
Optics
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Experiment
Calculation
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Wavelength (nm)
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EUV & BEUV source study
Wavelength: 13.5 & 6.x nm
Lithography Life Innovation Compact source development for Bio.
Wavelength: 2-4 nm
Proposal (APL x 1)
In vivo cell observation Original micro source
Single shot, flash biological imaging
Si / SiO
Sn: 10 - 15 um φ
Laser 2
Shorter wavelength
APL x 7 (2010-2012)
New concept flash WW-SXR source
Moseley's law?
Z scaling: quasi-Moseley's law by Prof. O’Sullivan and Prof. Endo
UTA Z = 55: Cs
Z = 60: Nd
Z = 64: Gd
Z = 65: Tb
Z = 71: Lu
Numerical simulation
l (nm)
l (nm)
2 4
2 4
(a) Line spectrum
(b) UTA
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.)
Figure 2: Takeshi Higashiguchi et al.
Unresolved transition array (UTA)
T. Higashiguchi et al., Appl. Phys. Lett. 100, 014103 (2012).
New concept flash source
Bi plasma condition
T. Higashiguchi et al., Appl. Phys. Lett. 100, 014103 (2012).
Bi plasma spectral analysis
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Experimental result700 eV
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0.12
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0.20190 eV
(a)
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Wavelength (nm)
Inte
nsity (
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1: 4f-5g, < Bi35+
2,3: 4p-4d, 4d-4f,
Bi36+-Bi45+
4: 4d-4f
Appl. Phys. Lett. 100, 014103 (2012).
Dual laser pulse Bi plasma
Dual laser pulse Bi plasma
Observation of Leydig cell in culture solution
Sample: Cultured on SiN membrane and fixed by formalin solution.
Beam line: Spring-8 BL27SU,
• Photon energy: 260~600 eV (2.1 ~ 4.8 nm ),
• Exposure time: 0.8 180 sec,
• Spatial resolution: 1.1mm,
• Wavelength resolution: l/Dl = 2000
Image comparison:
536eV – 529eV VI diff. int. img. ROI
Prof. Ejima@Tohoku University
Absorption in a biological sample
透過率像 2.38nm
試料
水
Prof. Ejima@Tohoku University
Proposal of two-color WW-SXR source
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Experimental result700 eV
0
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0.08
0.12
0.16
0.20190 eV
(a)
12
3
4
1 2 3 4 5 6
Wavelength (nm)
Inte
nsity (
arb
. un
its)
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6
500
1000
15000
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Wavelength (nm)
Te (eV)
Rela
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inte
nsity (
a.u
.)
Figure 2: Takeshi Higashiguchi et al.
T. Higashiguchi et al., Appl. Phys. Lett. 100, 014103 (2012).
Challenging: 1-keV WW-SXR
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.)
Figure 2: Takeshi Higashiguchi et al.T. Higashiguchi et al., Appl. Phys. Lett. 100, 014103 (2012).
Low density & 100-eV plasmas
ne µ1/ lL2
Te µ (ILlL2 )1/2 µ lL / t L
Development of sub-ns CO2 (10.6 um) laser
Next step: short CO2 laser installation sub-ns 10-Hz hybrid 10.6-um laser development
Palitra Optical Parametric Amplifier Tuning Curves
Wavelength (nm)1000 10000
Co
nve
rsio
n E
ffic
ien
cy
(%
)
0.1
1
10
UV3
UV2
UV1
VIS3
VIS2
VIS1
Sign
alId
ler
IR1
IR2
IR3
Typical Efficiencies with Quantronix Amplifier System, Pulse Duration 70-200 fsCO2 laser
20 uJ (160 uJ)
Expected:
160 mJ
Future for more HW: collaboration
Summary
Thanks a million!!!