© Fraunhofer ILT
Klaus Bergmann
EUV Source Workshop, October,9th, Dublin, Ireland
Discharge based EUV Sources for Metrology
© Fraunhofer ILT
Overview
Introduction
Technology and current status of HCT sources at ILT
Brilliance scaling for 13.5 nm
Conclusions
© Fraunhofer ILT
P:<ordner>name.ppt
History of EUV sources at ILT
Laser
Tin Supply
Electrode 1 Electrode 2
Laser
Tin Supply
Electrode 1 Electrode 2
1997 2001 2003 2011 2006 year
© Fraunhofer ILT
P:<ordner>name.ppt
Current XUV activities at ILT
Development of sources for EUV
lithography based on tin vacuum arc
(together with Xtreme)
Sources for metrology in the range
soft x-ray and EUV
XUV-Applications
(Support of TOS, RWTH Aachen University)
EUVL source development
Interference lithography
X-ray microscopy
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Technical base: Philips HCT source
Philips Xenon Source
ASML a-demo Tool
HCT principle was
patented by ILT
collaboration on
power scaling for use
as EUVL source
source delivered first
light in ASML a-demo
tool
currently used in the
field as metrology source
(mirror contamination,
optics characterization)
© Fraunhofer ILT
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Next Generation Source at Fraunhofer ILT
technical base is the HCT source
developed with Philips EUV
new system allows for higher
input power and pulse energy
simplified and more compact
source head design
emission in the soft x-ray to
extreme ultraviolet range
increased electrode lifetime
© Fraunhofer ILT
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Technical concept
Scheme of electrode system
max. input power: 25 kW
max. pulse energy: 20 J
emission at 13.5nm: >50 W/(2psr 2%b.w.)
typical plasma length: 3-5 mm
accessible collection angle: >80°
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Selected examples of applications (1)
Inband Energy Monitor
Absolute calibration of EUV diagnostics
Gracing / Normal Incidence Reflectometer
Inband Screen Tool
0,00
20,00
40,00
60,00
80,00
100,00
60 65 70 75 80 85 90
PS328704 3rd
PS 328704 1st
PS328704 2nd
ML-Mirror
Ru-Mirror
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Selected examples of applications (2)
Interference Lithography (11 nm) X-Ray Microscopy
(2.9 nm)
9 10 11 12 13 14 15
0
10
20
30
40
50
60
70
PU
LS
E IN
TE
NS
ITY
[ m
J/ (2psr
nm
) ]
WAVELENGTH [ nm ]
PbS nanocrystals for solar cells
Nitrogen emission spectrum
Xe/Ar emission spectrum
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P:<ordner>name.ppt
Progress in Electrode lifetime
Pinch Plasma
Sputtering due to pinch plasma
Cathode spots
erosion due to sputtering and
cathode spots
most critical consumable is cathode
intermediate plate allows for
reducing the influence of cathode erosion
improvement by use of other metal
envisioned interval for exchange of
electrodes is 1Gshot
Cathode after 100 Mshot
Molybdenum Metal with higher
melting point
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How do we measure “Peak Brilliance”
pinhole camera + Zr coated silicon nitride window
2
2/1
5.13
r
CEEfL nmin
peakp
-2000 -1500 -1000 -500 0 500 1000 1500 20000
1
2
3
4
5
6
7
BR
ILL
IAN
CE
[ a
rb.
un
its ]
RADIUS [ µm ]
calibrated energy monitor
Inband power (CE13.5nm) Emission profile (r1/2, )
f(r) f : repetition rate
Ein : electrical pulse energy
2
2/1
0
2
r
drrrf
f(r=0) = 1.0
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Parameter studies (1): Brilliance Efficiency
1 2 3 4 5 60,0
0,5
1,0
1,5
2,0
EF
FIC
IEN
CY
[ W
/ k
W m
m2 s
r ]
PULSE ENERGY [ J ]
peak brilliance at 300 Hz operation
red rhomb for old system at 8.7 kW
demonstrated 2.0 W/(kW mm2 sr)
at a pulse energy of 6.1 J
© Fraunhofer ILT
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Parameter studies (2): Variation of pulse energy
peak brilliance at 1000 Hz operation
low variation of profile coefficients
over wide range of pulse energies
-1500 -1000 -500 0 500 1000 15000,0
0,5
1,0
INT
EN
SIT
Y [
no
rm. ]
RADIUS [µm]
p:<eb_xuvquelle.laborbuch.bergmann.2012.120920>pinchprofile.opj
Normalized profiles for different energies
Ein / J r1/2 / µm *r1/22/ mm2
2.3 269 2.1 0.15
3.1 236 3.2 0.18
4.0 244 3.7 0.22
4.9 228 4.2 0.22
5.9 232 4.3 0.23
6.6 225 4.3 0.22
7.6 218 4.4 0.21
8.4 225 4.5 0.23
Brilliance efficiencies:
0.9 – 1.4 W/kWmm2sr
© Fraunhofer ILT
P:<ordner>name.ppt
Demonstration of 21 W/(mm2sr)
-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0-8
-7
-6
-5
-4
-3
-2
-1
0
1
VO
LT
AG
E [ k
V ]
TIME [ ms ]
0,00
0,01
0,02
0,03
0,04
0,05
0,06
DIO
DE
VO
LT
AG
E [ V
]
-1500 -1000 -500 0 500 1000 15000
1
2
3
4
5
6
7
PE
AK
BR
ILL
IAN
CE
[ m
J/m
m2sr]
RADIUS [ µm ]
2
2/1r
CEEfL in
peakp
f (repetition rate) : 3.3 kHz
Ein (pulse energy) : 6.0 J
CE (conversion eff.) : 0.3 %/2psr
(profile factor) : 5.8
r1/2 (radius) : 155 µm
Diode and voltage for 3.3 kHz, 6.0J Profile for 3.3 kHz, 6.0J
© Fraunhofer ILT
P:<ordner>name.ppt
Demonstration of 21 W/(mm2sr)
-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0-8
-7
-6
-5
-4
-3
-2
-1
0
1
VO
LT
AG
E [ k
V ]
TIME [ ms ]
0,00
0,01
0,02
0,03
0,04
0,05
0,06
DIO
DE
VO
LT
AG
E [ V
]
-1500 -1000 -500 0 500 1000 15000
1
2
3
4
5
6
7
PE
AK
BR
ILL
IAN
CE
[ m
J/m
m2sr]
RADIUS [ µm ]
2
2/1r
CEEfL in
peakp
f (repetition rate) : 3.3 kHz (2.5 kHz)
Ein (pulse energy) : 6.0 J (7.0 J)
CE (conversion eff.) : 0.3 %/2psr (0.4 %/2psr)
(profile factor) : 5.8 (4.8)
r1/2 (radius) : 155 µm (180 µm)
22.4 W/mm2sr
Diode and voltage for 3.3 kHz, 6.0J Profile for 3.3 kHz, 6.0J
© Fraunhofer ILT
P:<ordner>name.ppt
Scaling Potential >50 W/(mm2sr)
-1500 -1000 -500 0 500 1000 15000,0
0,2
0,4
0,6
0,8
1,0
NO
RM
. B
RIL
LIA
NC
E
RADIUS [ µm ]
260 µm diameter source profile (full) and profile from 21 W/mm2sr demonstration (dotted)
estimation of achievable brilliance
by multiplying realistic and already
demonstrated best of parameters
experience with previous system:
gas flow conditions is the key
optimization parameter
srmm
W
r
CEEfL in
peak 22
2/1
6.70p
20 kW 0.53 %
4.5 130 µm
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Considerations on Source-Collector-Module
Normal Incidence collector (Ray Tracing)
example for source-collector-module
with typical distance:
~1m source-mirror and mirror-focus
relaxed requirements for debris-mitigation
homogeneous illumination of sample over
~50 µm “easy” to achieve
mirror
source
focus
Intensity profile at IF
-50 -40 -30 -20 -10 0 10 20 30 40 5010000
15000
20000
INT
EN
SIT
Y [ a
rb. u
nits ]
RADIUS [ µm ]
p:<ex_xuvquelle.laborbuch.bergmann.2012.120920>if-homogeneity.opj
50 µm
homogeneity : <1.0%
© Fraunhofer ILT
P:<ordner>name.ppt
Conclusions
next discharge source has been taken in operation at ILT
technical base is status of development together with Philips EUV
new system is more compact and covers a larger parameter range
work on brilliance scaling just has started
demonstration of 21 W/(mm2 sr) into 2%b.w. for 13.5 nm at 20 kW input power
optimization potential for >50 W/mm2sr based on experimental data has been identified
© Fraunhofer ILT
P:<ordner>name.ppt
Acknowledgements
Markus Benk (currently at CXRO in Berkeley)
Jochen Vieker
Federal State NRW, Germany for financial support