recent advances in development and application of compact … · 2018. 12. 10. · xenon gas puff...
TRANSCRIPT
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Recent Advances in Development and Application of Compact Laser Plasma
Soft X-ray Sources based on a Gas Puff Target
Henryk Fiedorowicz, Andrzej Bartnik, Przemysław Wachulak, Karol Janulewicz,
Roman Jarocki, Jerzy Kostecki, Tomasz Fok, Łukasz Węgrzyński
Institute of Optoelectronics
Military University of Technology
Warsaw, Poland
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https://www.euvlitho.com/2015/S3.pdf
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Outline
Introduction
- soft X-rays and extreme ultraviolet (EUV)
- laser plasma soft X-ray/EUV source
- gas puff target approach
Source applications
- EUV metrology
- EUV and soft X-ray imaging,
- EUV processing material,
- EUV photoionization studies,
- soft X-ray radiobiology,
- soft X-ray absorption spectroscopy (NEXAFS)
- soft X-ray optical coherence tomography (X-OCT)
Conclusions
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Henryk Fiedorowicz, Andrzej Bartnik, Karol Janulewicz, Przemysław Wachulak
Roman Jarocki, Jerzy Kostecki, Mirosław Szczurek,
Daniel Adjei, Inam Ul Ahad, Mesfin Ayele, Tomasz Fok, Martin Duda, Ismail Saber,
Alfio Torrisi, Łukasz Węgrzyński
Laser-Matter Interaction (LMI) Group
Research goals: Development of laser-driven sources of X-rays and EUV
for application in science and technology
http://www.ztl.wat.edu.pl/zoplzm/
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Introduction
Nanowaves
Soft X-rays (XUV) 0.1 λ < 10 nm
Extreme Ultraviolet (EUV) 10 λ < 121 nm (He Lyman-alpha)
Motivations
- nanometer resolution (nanolithography & nanoimaging)
- nanometer penetration depth (processing of surfaces & nanoanalysis)
- elemental mapping (nanoscale)
Generation
- synchrotrons, FELs
- plasma sources (discharge plasmas, laser plasmas)
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ISO International Standard 21348 http://www.spacewx.com/ISO_solar_standard.html
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Introduction
Focusing
lens
Vacuum
chamber
Laser system (ns, J)
Oscillator Amplifier Target system solid, liquid, gas
Soft X-rays & EUV Laser plasma
Ne 1019 – 1022 cm-3
Te 50 – 500 eV Nd:glass
Nd:YAG
KrF
CO2
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Source characteristics
- high single-pulse brightness
- short-pulse duration
- easy tuning of wavelength
- low investment costs
Main disadvantages
- laser target operation
- target debris production
Schematic of laser plasma soft X-ray/EUV source
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Introduction
outer nozzle inner nozzle
high-Z gas
(xenon, krypton, argon)
low-Z gas
(helium,
hydrogen) laser beam
electromagnetic valve system
schematic of a double-str eam gas puff target
X-ray backlighting images
Fiedorowicz et al. Appl. Phys. B 70 (2000) 305; Patent No.: US 6,469,310 B1 8
Double-stream gas puff target
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Comparison with solid targets
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xenon gas puff
solid copper
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CC
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solid iron
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wavelength, nm
xenon gas puff
solid tin
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wavelength, nm
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EUV Emission from a Double-Stream Xenon/Helium Gas Puff Target Irradiated with a Nd:YAG Laser
wavelength, nmwavelength, nm
xenon gas puff
solid aluminium
• EUV emissions from various solid and an xenon gas puff targets irradiated with
a Nd:YAG laser (0.5J/10ns)
- Elimination of debris
- Operation with repetition
- Conversion efficiency improvement Gas puff target
Fiedorowicz et al. Opt. Commun. 184 (2000) 161 9
ILE
Osaka
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Laser systems
We use commercial nanosecond Nd:YAG lasers
EKSPLA Compact Flash-Lamp Pumped
Q-switched Nd:YAG Lasers
NL300 Series
4 ns/0.8 J/10 Hz
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EKSPLA High-Energy Flash-Lamp Pumped
Q-switched Nd:YAG Lasers
NL310 Series
1-10 ns/10 J/10 Hz
Quantel High-Energy Pulsed Nd:YAG
Lasers
YG980 Series
8-11 ns/2.5 J/10 Hz
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Compact laser plasma EUV source
compact laser-plasma EUV source based on a gas puff target irradiated with
a commercial Nd:YAG laser (4 ns/0.5 J/10 Hz) was developed for EUV metrology
EUV lamp
EUV metrology setup
Fiedorowicz et al. J. Alloys & Comp. 401 (2005) 99
10 cm
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EUV source parameters
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
0
50.00
100.0
200.0
300.0
350.0
400.0
500.0
600.0
Z Axis (mm)
Y A
xis
(m
m)
Spectral image at 13.5 nm
400 m
EUV spectrum
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Nd:YAG laser (4ns; 0.5J)
tXe
=800s, tH=400s
Inte
nsity (
CC
D c
ou
nts
)
Wavelength, nm
CE at 13.5 nm
1.5 - 2 %
0 5 10 15 20 25 30 35
0.000
0.005
0.010
0.015
5 ns
Am
plit
ud
e, V
Time, ns
Time profile
Fiedorowicz et al., J.Alloys&Comp. 401 (2005) 99
Rakowski et al. Appl. Phys B 101 (2010) 773 12
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Laser plasma soft X-ray source
Laser parameters 0.8J, 4ns, 10Hz
Gas (argon or nitrogen) pressure 10 bar
Wavelength range
2.5-4nm
Photon number in 4
3.51014 /pulse
Photon energy in 4
28.1mJ/pulse
Wavelength
2.88nm
Photon number in 4
5.61013 /pulse
Photon energy in 4
3.9mJ/pulse
Wachulak et al. Nucl. Instr. Meth. (2010)
Argon
Nitrogen
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wavelength [nm]
nitrogen
oxygen
argon
xenon
krypton
Soft X-ray spectra
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X-ray absorption fine structure (XAFS) spectroscopy
X-ray absorption fine structure (XAFS) spectroscopy is a technique to probe the local
structure of matter by studying the oscillations above the X-ray absorption edge.
A typical XAFS spectrum exhibits two energy regions: the near-edge region (NEXAFS or
XANES) and the extended one (EXAFS).
The NEXAFS is more sensitive to the electronic structure, while the EXAFS gives more
information on bond distances, coordination numbers and local disorder.
NEXAFS is also very sensitive to the bonding environment of the absorbing atom.
over 500 participants 15
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Near-edge X-ray absorption fine structure (NEXAFS)
The NEXAFS technique is usually performed at synchrotron radiation sources.
XPS/NEXAFS endstation installed on HE-SGM beamline at BESSY II
However, compact laboratory NEXAFS systems have been developed.
Laser-Laboratorium Gottingen Institut für Optik und Atomare Physik
Technical University Berlin
Institute of Optoelectronics
Military University of Technology, Warsaw
5.9 m
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Compact system for NEXAFS spectroscopy
Compact system for near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been
developed using a laser plasma soft X-ray source based on a gas puff target
Schematic of the NEXAFS system Experimental setup of the NEXAFS system
Typical reference and sample
spectra for a 1 m thick PET foil
Attenuation coefficient
near the carbon K- edge
NEXAFS spectrum for a 1
m thick PET sample
Wachulak et al. Optics Express 26, 8260 (2018)
Elem
ent
Mea
sure
d [%]
Theo
retic
al
[%]
C 65.9 62.5
H 4.8 4.2
O 29.3 33.3
Elemental
composition
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2-D elemental mapping with NEXAFS
2-D elemental mapping of an EUV-irradiated PET sample was demonstrated using a compact
NEXAFS spectromicroscopy system with a laser plasma soft X-ray source based on a gas puff target
Schematic of the NEXAFS spectromicroscopy system
2-D composition maps for carbon, hydrogen and oxygen
NEXAFS spectrum for a 1 m thick PET
sample (pristine and EUV-modified)
Wachulak et al. Spectrochimica B 145, 107 (2018)
Modification of PET with EUV
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Single-shot NEXAFS spectroscopy
Experimental setup for the single-shot NEXAFS spectroscopy
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inte
nsity [a
.u.]
energy [eV]
krypton (reference)
spectrum
System parameters:
NL129 (Ekspla) laser system:
E=10 J, t=1 ns
1 shot , NEXAFS spectrum acquisition
Kr-11bar, He-5bar pressure
Sample: 1mm thick PET
Wachulak et al., Materials 11, 1303 (2018)
Martin Duda
Poster – P24
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Single-shot NEXAFS spectroscopy
Single-shot NEXAFS spectroscopy results for PET sample
20 Wachulak et al., Materials 11, 1303 (2018)
Single-shot PET NEXAFS spectrum
* Dhez, O. et al., J. Electron. Spectrosc. Relat.
Phenom. 128, 1 (2008)
*
Spectral component assignment
Sample PET foil 1 mm thick (C10H8O4)n
Method Composition [%] Global error [%]
C H O
Theoretical w/w % 62.5 4.2 33.3 0
Experiment 10% step for each peak 67.6 3.8 28.6 2.3
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Optical coherence tomography (OCT)
Optical coherence tomography (OCT) is a well-known imaging technique that uses
coherent light to capture micrometer-resolution, two- and three-dimensional images
from optical scattering media. Images are created from reflections of the light.
The axial resolution of OCT is in the order of the coherence length of a light source lc
which depends on the central wavelength λ0 and the spectral width (FWHM) of the
source ΔλFWHM.
OCT with broadband visible and near-infrared sources typically reach axial (depth)
resolutions in the order of a few micrometers.
G. Paulus & Ch. Rödel „Short-wavelength coherent tomography”
US Patent No.: US 7,656,538 B2
For Gaussian shaped spectrum
the coherence length is defined:
The axial resolution improvement has been proposed by extention of optical coherence
tomography (OCT) to the short-wavelength coherent tomography (XCT) using
extreme ultraviolet and soft X-rays.
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X-ray coherence tomography (XCT)
Realizing a classical Time-domain XCT (TD-XCT) using a Michelson interferometer
is highly demanding because of problems with optics.
In order to overcome these problems, the use of a variant of Fourier-domain XCT
(FD-XCT) setup has been proposed.
A schematic of the proposed FD-XCT setup:
The probing beam is reflected at the layer surfaces of the sample. The beams
interfere and cause a modulated reflected spectrum that can be measured with a
grating spectrometer.
The toroidal mirror images the sample surface onto the CCD camera. The reference
wave and the sample wave share the same path. Moreover, using this variety of
XCT, a beam splitter can be completely avoided.
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XCT using synchrotron radiation
A proof-of-principle experiment and the first demonstration of XCT has been recently
performed at synchrotron radiation sources at DESY (Deutsches Elektronen-
Synchrotron) and BESSY (Berliner Elektronenspeicherring-Gesellschaft fur
Synchrotronstrahlung).
5 nm Au
Si
Sketch of the sample 3-D XCT image of a silicon-based sample
with different buried layers of gold
The depth structure was reconstructed by analyzing the
spectral interferogram.
Lateral imaging was achieved by scanning the focused
beam over the sample with a lateral resolution of 200 μm
As XCT exploits the surface reflection as a reference,
the sketch on right of the picture shows the sample
how it is expected to be measured.
S. Fuchs, Ch. Rödel, A. Blinne, U. Zastrau, M. Wünsche, V. Hilbert, L. Glaser, J. Viefhaus, E. Frumker, P. Corkum, E. Förster &
G.G. Paulus, Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation,
Scientific Reports 6, 20658 (2016)
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XCT using synchrotron radiation
(a) Recorded reflected spectral intensity for EUV (40–12 nm) of the layer system (c). The blue dots
correspond to the CCD-cameras pixels the red curve is the interpolation.
(b) Reconstructed depth profile: The two gold layers appear clearly separated, thus the resolution is
better than 18 nm.
(d) Recorded reflected spectral intensity for soft X-rays (4.4–2.3 nm) of the layer system (f). The blue
dots correspond to the energy measurement discretization and the red curve is the interpolation.
(e) Reconstructed depth profile: The front and backside of the platinum layer appear separated, thus the
resolution is better than 8 nm.
XCT signals for EUV and soft X-ray radiation
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XCT using laser plasma soft X-ray source
Schematic of the XCT setup
Soft X-ray spectrum
Experimental arrangement of the XCT setup
CCD
camera
Grating
spectrograph Laser plasma
soft X-ray source
Sample
chamber
Nd:YAG
laser
Sample (Mo/Si mirror)
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XCT using laser plasma soft X-ray source
(a) measured reflectivity of the Mo/Si
multilayer structure in the wavelength
range from 1.5 nm to 5.5 nm.
(b) k-space reflectivity spectrum with a
Gaussian-type window applied
(c) reconstruction of a depth information
from the Mo/Si structure, experimental
data (bottom, pink curve) and simulation
(top, blue curve).
(d) visualization of depth structure of the
sample; a comparison between
theoretical and experimental data.
Axial spatial resolution was estimated.
The FWHM of the peak, related to the first
Si-Mo interface equals to ~2 nm. Taking into
account another, well defined experimental
spectral peak at 30 nm depth, the FWHM is
estimated to be ~2.6 nm.
The axial spatial resolution in XCT can be
comparable to FWHM values and is of the
order of 2–2.6 nm.
Results of the preliminary XCT measurements
P. Wachulak, A. Bartnik, H. Fiedorowicz,
Optical coherence tomography (OCT) with 2 nm axial
resolution using a compact laser plasma soft X-ray source
Scientific Reports 8, 8494 (2018)
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XCT setup for 3-D imaging
Optical scheme of the XCT setup for 3-D imaging using a laser plasma light source
Optics and system parameters:
length of the optics d = 100.00 mm
object-image distance x = 800.00 mm
magnification = 4.3333
angle = 11.51 deg,
object distance x = 100.00 mm
image distance y = 600.00 mm
critical angle = 2.58 deg
Ellipsoidal mirrors parameters:
A = 400.177 mm, B = 11.906 mm
din = 15.759 mm, dout = 20.625 mm
NAin = [0.0786, 0.0515],
NAout = [0.0172, 0.0113
Detection system:
grating width = 2.0 mm,
grating period = 200.0 nm
grating - CCD distance z = 58.18 mm
CCD chip size = 13.0 mm,
number of pixels = 1024×1024
max wavelength = 22.2 nm,
dispersion = 0.043 nm/pix
source size = 0.10 mm,
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XCT setup for 3-D imaging
Schematic of the XCT setup for 3-D imaging using a laser plasma light source
Experimental vacuum
chamber
Nd:YAG laser system
Nd:YAG laser
(1.6 J, 6-10 ns, 20 Hz)
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Summary
compact laser plasma EUV and soft X-ray sources based on
a gas puff target have been developed,
the sources were used in metrology of EUV optics, EUV and
soft X-ray microscopy, EUV and soft X-ray pulsed radiography,
EUV processing materials, EUV photoionization studies, and
soft X-ray radiobiology,
application in soft X-ray absorption spectroscopy (NEXAFS),
soft X-ray optical coherence tomography has been recently
demonstrated,
new techniques based on a laser plasma soft X-ray and EUV
sources are ready for the use in ”real” research.
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Acknowledgements
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Funding
The research was supported by the Ministry of Science and Higher Education of
Poland (EUREKA project E! 3892 ModPolEUV and COST Action MP0601 project),
the Foundation for Polish Science (HOMING 2009 Programme), the National Centre
for Research and Development (LIDER Programme), the National Centre of Science
(Beethoven Programme) and the European Comission (Laserlab Europe, EXTATIC,
CEZAMAT and OPTOLAB projects).
Collaboration
Gerhard G. Paulus, Silvio Fuchs, Christian Rödel, Martin Wunsche, Johann Abel
(Institute of Optics and Quantum Electronics, Jena University, Germany)
http://www.ncbir.pl/