Post on 11-Oct-2020
transcript
Laser-
Laboratorium
Göttingen e.V.
Laser-Laboratorium Göttingen e.V.
Hans-Adolf-Krebs Weg 1
D-37077 Göttingen
Table-top EUV/XUV source for
metrology applications
NEXAFS spectroscopy
Klaus Mann
Dept. Optics / Short Wavelengths
2
Dept. “Optics / Short Wavelengths”
Beam and Optics Characterization (DUV)
Beam propagation
Wavefront
coherence
M²
Optics test (351…193 nm)
(Long term) degradation (109 pulses)
Non-linear processes
LIDT
Absorption / Scatter losses
Wavefront deformation
EUV/XUV technology
Source & Optics
Metrology
Material interaction
Types of laser produced plasmas
Target material Solid Liquid Gas
Advantages + conversion
efficiency
+ Small plasma
(~50µm)
+ conversion
efficiency
+ mass limited,
small target
(~50µm)
+ „clean“ (no
debris)
+ high flexibility
+ high stability
+ low effort
Disadvantages unflexible
„dirty“ (debris)
high effort
debris:
„snowballing“
relatively low
brilliance
size ~300µm
3
EUV/XUV radiation:
Lab source for metrology
Nd:YAG
Laser
EUV source
chamber
Laser power supply
Spezifications:
- Wavelength: 1 - 20nm
- Pulse energy (Xe): 4mJ (4 sr, 2%BW)
- Conversion eff.: 0.45% (Xe)
- Pulse length: 6ns
- Plasma size: ~ 300µm
EUV: 10…20nm XUV: 1…10nm
pulsed Xenon gas jet
laser
EUV
Pinhole
camera
• Univ. Prag
• Univ. Göttingen
• Max-Planck Inst.
5
LLG-Activities Based on
EUV LPP Source
Direct structuring Reflectometry
NEXAFS spectroscopy XUV microscopy
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 8510
-4
10-3
10-2
10-1
100
Ref
lect
ivit
y
Sample angle
6
Ablation / damage thresholds
@13.5nm
Laser driven EUV/XUV plasma source setup
1.2 J/cm2 (@ 13,5 nm, 2 % bandwidth)
7.4 J/cm2 (filtered by 2 Mo/Si mirrors)
Damage thresholds of
mirrors / substrates single-pulse damage
F. Barkusky, K. Mann et al., Optics Express 18, 4347 (2010)
F. Barkusky, K.Mann et al., J. Appl. Phys. 101, 124908 (2007)
Integrated source and optics system:
EUV direct structuring
1µm PMMA
Color Centers in LiF
Resolution 130nm
Period 1.4µm
Schwarzschild objective
@13.5nm (Mo/Si):
PMMA
EUV Diffraction experiment
pure EUV radiation !
(@ 13.5 nm, 2% BW)
- Pinhole ( 50µm) behind plasma
- mesh before objective
diffraction pattern imprinted on PMMA
= Near-edge x-ray absorption fine-structure
200 250 300 350 400 450
0
2000
4000
6000
8000
10000
12000
14000
0,0
0,2
0,4
0,6
0,8
1,0
Inte
nsity [C
CD
-Co
un
ts]
Photonenenergy [eV]
without sample
with Polyimid (d=200nm)
Transmission Carbon (CXRO)
Tra
nsm
issio
n
Plasma in Kr gas jet „water window“ / Polyimide (d=200nm):
Absorption in unoccupied molecular orbitals
„Fingerprint“ of molecules
Soft x-rays with lab source:
NEXAFS Spectroscopy
Carbon
K-edge
surface-sensitive chemical analytics
polychromatic concept
280 290 300 310 320
0,0
0,5
1,0
1,5
2,0
*C-N
*C=C
*C=O
*C=O
Op
tisch
e D
ich
te [a
.u.]
Photonen-Energie [eV]
*C=C
C. Peth, K. Mann et al.,J. Phys. D 41 (2008) 105202
Polyimide
60 pulses
Synchrotron data
(J. Stöhr):
Setup of NEXAFS Spectrometer
Table-top system
„Single-shot“
Pump-probe exp.
XUV plasma (Kr)
with pinhole camera
Single pulse NEXAFS spectra
NEXAFS spectroscopy on thin films
Lipid membranes (carbon K-edge)
E. Novakova, C. Peth, K. Mann, T. Salditt et al.: Biointerphases, 3 (2008) FB44
285 290 295 300 305 310 315
0
1
2
3
4
Optic
al d
ensi
ty
Photon energy (eV)
C=C*
DOPS
DOPC
DMPC
4,4 4,3 4,2 4,1 4 3,9
Wavelength [nm]
(T. Salditt)
NEXAFS spectra of PMMA
PLD: PMMA films (200nm)
Softer as bulk material shorter polymer chains
C=C bonds visible
280 285 290 295 300 305 3100,0
0,2
0,4
0,6
0,8
1,0
*C-O
*C=O
*C=C
optical density (
a.u
.)
photon energy (eV)
PMMA, untreated
PMMA, UV irradiated (5h)
*C-C
UV irradiation
Chemical changes :
Loss of C=C bonds
Increase of C=O bonds
repolymerization
bulk material
B. Fuchs, P. Großmann, K. Mann, H.U. Krebs et al., Appl. Phys. A98, 711-715 (2010)
NEXAFS spectrum PCMO
14
300 400 500 600 700 800 900 10001,0
1,1
1,2
1,3
1,4
1,5
1,6
1,7
1,8
1,9
2,0
Optical T
hic
kness [a.u
.]
Photon-Energy (eV)
NEXAFS-Spectrum PCMOCaL 2,3
NK
OK
MnL 2,3
PrM 4,5
▲Perovskit-type Manganate
Pr1-xCaxMnO3
525 530 535 540 545 550 555 5601,0
1,1
1,2
1,3
1,4
Optica
l T
hic
kn
ess
Photon-Energy /eV
NEXAFS-Spektrum PCMO, O K-Kante
EELS Referenzdaten
: Pr, Ca
: O
: Mn
High-Tc superconductor
Every element visible
Agreement with reference
pump-probe experiments Radiation-induced
phase transition (~100K)
O K-edge
(S. Techert)
XUV source improvements:
Comparison: ns – ps laser
Xe (Z = 54)
Single pulse XUV spectra
200 400 600 800 100010
1
102
103
104
200 400 600 800 100010
1
102
103
104
200 400 600 800 1000
101
102
103
200 400 600 800 100010
2
103
104
200 400 600 800 100010
2
103
104
200 400 600 800 100010
2
103
104
Photon energy (eV)
Single-Pulse - Max. Laserpulse-Energy - Al filteredNitrogen Oxygen Neon
Photon energy (eV) Photon energy (eV)
Photon energy (eV)
Argon Krypton Xenon
Photon energy (eV) Photon energy (eV)
Single pulse XUV spectra
Single pulse XUV spectra
Single pulse spectra:
O (Z = 8) Ne (Z = 10) N (Z = 7)
Ar (Z = 18) Kr (Z = 36)
8ns
450mJ
150ps
380mJ
Peak brillance of isolated N line @ = 2.88nm:
6*1017 (ns-Laser) 1.2*1020 Ph./(s mrad2 mm2 0,1%BW) (ps-Laser)
The barrel shock – Schlieren images
10-3mbar
1 bar
Nitrogen
10bar
ambient
pressure:
16
500µm
The barrel shock
17
Nitrogen
10 bar
Helium
170 mbar
Wavefront
Density
Nitrogen
10 bar
Helium
170 mbar
18
Nitrogen
10 bar
Vacuum
~10-3 mbar
500 µm 500 µm
Plasma generation with/without the barrel shock
Nitrogen
10 bar
Helium
170 mbar
19
Nitrogen
10 bar
Vacuum
~10-3 mbar
500 µm 500 µm
Plasma generation with/without the barrel shock
Enhancement of particle density in gas jet:
increased brillance from shock wave
Pinhole camera image of Nitrogen plasma p=10bar / Ti-filtered
pamb = 10-3 mbar pamb = 170 mbar
Summary and Outlook
EUV / XUV source
Compact, clean, reliable
Line or broad-band radiation (1…20nm)
EUV: reflectometry, direct structuring / ablation studies
XUV: NEXAFS for chemical surface analysis
Further increase of brilliance / higher photon energies
Entire spectrum in single pulse / pump-probe
scanning spectro-microscopy
• Dr. B. Schäfer
• Dr. A. Bayer
• Dr. U. Leinhos
• Dr. F. Barkusky
• J.O. Dette
• M. Lübbecke
• M. Reese
• B. Flöter
• P. Grossmann
• M. Olschewski
• S. Döring
• T. Mey
• J. Sudradjat
Thank You !
Coworkers:
Outline
1. Table-top EUV/XUV source
- experimental
2. Metrology applications
- reflectometry
- Damage of EUV optics
- NEXAFS spectroscopy
3. Source improvements
4. Characterization of EUV/XUV radiation (FLASH)
- wavefront measurement / Hartmann(-Shack) sensor
- optics alignment
23
24
Hartmann-Shack wavefront sensor:
wavefront:
Wavefront w(x,y)
= surface Poynting-Vektor S(x,y)
(ISO 15367-2)
directional
distribution
intensity
distribution
B. Flöter, K. Mann, K. Tiedtke et al. NIM A 635, S108–S112 (2011)
Hartmann
plate
EUV/XUV
Beam
Beam characterization of
Free Electron Laser FLASH
EUV-Hartmann sensor: Spot distribution:
Adjustment of
beam line optics:
= 5 – 30nm
Accuracy:
• ~ /15 wpv for EUV
26
Ablation / damage thresholds
@13.5nm
Laser driven EUV/XUV plasma source setup
1.2 J/cm2 (@ 13,5 nm, 2 % bandwidth)
7.4 J/cm2 (filtered by 2 Mo/Si mirrors)
Damage thresholds of
mirrors / substrates single-pulse damage
F. Barkusky, K. Mann et al., Optics Express 18, 4347 (2010) (OSA Spotlight)
Peak brillance of laser plasma source
400 450 500 550 600 650 700
0
10000
20000
30000
40000
50000
60000
N VII 1s2-1s5p
N VII 1s2-1s4p
N VI 1s2-1s6p
N VI 1s2-1s5p
N VII 1s2-1s3pN VI 1s
2-1s4p
N VII 1s2-1s2p
N VI 1s2-1s2p
CC
D-C
ounts
Photonenenergie (eV)
Stickstoff - Einzelpuls - Al gefiltert
N VI 1s2-1s3p
Isolated N VI 1s2-1s2p line @ 2.8787nm (Ti filtered)
Peak brillance [Photons/(s mrad2 mm2 0,1%BW)]
ns-Laser: 6*1017 (LLG, T. Wilhein)
ps-Laser: 1,2*1020 (LLG)
NEXAFS-Spektrum bisDMA
06.12.2011 Peter Großmann 28
Dünne Schichten bisDMA (Weichmacher)
Beeinflussung Polymerkettenlänge z.B. PMMA
Suche nach optimalem PLD – Parametersatz
Variation Target - Substratabstand
Parameter-Abhängigkeit der
C=C Bindungen
C=C Bindungen als Maß für die
Unversehrtheit des bisDMA
Kürzerer Abstand besseres
Ergebnis?
Weitere Untersuchungen nötig 280 285 290 295 300 305 310 315 320
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
*C=C
*C=C
*C=O
Optis
che D
ichte
(b. E
.)
Photonenenergie / eV
bisDMA, Abstand 30mm
bisDMA, Abstand 40mm
bisDMA, Abstand 50mm
*C-C
*C-O
Compact NEXAFS spectrometer
30
► EUV Reflectivity
of 75 nm thick
carbon layer
EUV reflectometry
10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.00
1000
2000
3000
4000
5000
6000
7000
Oxygen spectrum
Mo/Si filter mirror
Inte
nsi
ty a
.u.
Wavelength [nm]
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Ref
lect
ivit
y0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
10-4
10-3
10-2
10-1
100
Ref
lect
ivit
y
Sample angle
EUV spot on sample
@ =13nm:
Specifications: - wavelength: 12.98nm (oxygen line)
- angular resolution: 0.3°
- angular range: 1° - 85°
- dynamic range: 4 orders of mag.
Mo/Si
multilayer
mirrors
@13nm
R~60%
„Water window“ (2,2nm – 4,4nm)
31
2,0 2,5 3,0 3,5 4,0 4,5 5,0
0,1
1
10
O: 2,28 nm
Ti: 2,73 nm
N: 3,0 nm
Ca: 3,58 nm
C: 4,36 nm
Ti N
Ca
H2O
C
Ab
so
rptio
nle
ng
th /
µm
Wavelenght /nm
▼Absorption edges
▼Soft x-ray microscopy
D. Attwood