Liquid-jet laser-plasma sources for sub-13 nm emission · Sub 13 nm: Which are our options? Prague...
Transcript of Liquid-jet laser-plasma sources for sub-13 nm emission · Sub 13 nm: Which are our options? Prague...
Biomedical and X-Ray Physics, KTH, Stockholm Prague 2018
Liquid-jet laser-plasma sources for
sub-13 nm emission
Hans HertzBiomedical & X-Ray Physics
Dept. of Applied Physics
Royal Inst. of Technol. (KTH)
Stockholm
&
COB: Excillum AB
Biomedical and X-Ray Physics, KTH, Stockholm
Present source for 13 nm EUVL
Prague 2018
• Wavelength: =13.5 nm
• Regenerative target: Sn
• High-reflectivity mirror: Mo/Si
From O’Sullivan, J Phys B (2015)
Biomedical and X-Ray Physics, KTH, Stockholm
Why shorter wavelength?
Prague 2018
Key issues:
• Laser-plasma source @ sub-13 nm• Power
• Target
• stable
• regenerative
• Mirror reflectivity
• Photo resist sensitivity
RESOLUTION= 𝑘1𝑁𝐴
DOF = 𝑘2𝑁𝐴 2
Biomedical and X-Ray Physics, KTH, Stockholm Prague 2018
What do we have?
Liquid-jet/droplet laser-plasma sources
50 mm
2-4 nm: Water-window =11-13 nm: EUV Litho
Rymell et al, Opt. Commun. (1993)
+ High rep.-rate operation
+ High-power operation
+ Tailored spectral emission
+ Negligible debris
/>500
Ethanol
Rymell et al, APL (1995); Berglund et al APL (1997);Jansson et al, RSI (2005) ;Hansson et al, MNE (2001);Takman et al APL (2004) ;Martz et al, Opt. Lett. (2012)
2.4 nm Liquid nitrogenPrinciples
Biomedical and X-Ray Physics, KTH, Stockholm Prague 2018
Photon flux
Source size
2000 Hz
100 Hz
10 Hz
= 2.48 nm power:
200 W, 600 ps, 2 KHz DPSS laser plasma
Spectral brightness:
Lab source at early-bending-magn level!
Martz et al, Opt. Lett. (2012)
Biomedical and X-Ray Physics, KTH, Stockholm
Sub 13 nm:
Which are our options?
Prague 2018
Xe
C Ka
From O’Sullivan, J Phys B (2015)
Target (nm) Mirror
Sn 13.5 Mo/Si
Xe 11.5 Mo/Be, Ru/Be..
Gd, Tb 6-7 La/B
C, N 2-4 W/B4C, Cr/Sc
• moderately/highly charged ions
• n=4 − n=4 transitions
Biomedical and X-Ray Physics, KTH, Stockholm
Liquid-jet/droplet basics
LaminarTransition Turbulent
Spray
Biomedical and X-Ray Physics, KTH, Stockholm
Liquid-jet/droplet basics
Stability: Laminar flow region
L
L= 𝑙𝑛𝑎
𝑜
𝑣8𝑎3
+
6𝑎
LN2 jet
Biomedical and X-Ray Physics, KTH, Stockholm
=13.5 nm:
First liquid-tin-jet source
Prague 2018
Jansson et al .
Appl. Phys. Lett. (2004)
Stable jet @ >250 C Spectral match Debris:
CE: 2.5% into (2%BW2sr)
1 h gave coating
Mitigation need: ~108
PRESENTLY:
Sn liquid jets is the source for HVM EUV litho
Biomedical and X-Ray Physics, KTH, Stockholm
=11.5 nm:
First liquid-xenon-jet source
Prague 2018
Hansson et al, Microel. Engin. (2000);
Spectrum
Jet cooling
Stability
50 mm
Exp. arrangement
Biomedical and X-Ray Physics, KTH, Stockholm
Cryogenic liquid jets:
LN2 jet laser-plasma stability
Prague 2018
Freeze Burst Sinuous Spray
instability
CW Pulsed
Illumination
Classical liquid-jet stabilityHigh-speed jet imaging4 ns laser, 20 Hz
Fogelqvist et al, J. Appl. Phys. (2015)
LN2 liquid-jet
stability
Biomedical and X-Ray Physics, KTH, Stockholm
Avoiding evaporative effects while still keeping
pressure low
Prague 2018
Local radiative heating
No
stabilizationPressure
stabilizationRadiative heat
stabilization
Biomedical and X-Ray Physics, KTH, Stockholm
Long-term stability: 1h
Prague 2018
Biomedical and X-Ray Physics, KTH, Stockholm
=11.5 nm:
Mirrors
Prague 2018
Chkhalo & Salashchenko, EUVL workshop 2013
Biomedical and X-Ray Physics, KTH, Stockholm
= 6-7 nm:
Gd, Tb
Prague 2018
La/B mirrors:
theoretically R=80%
From O’Sullivan, J Phys B (2015)
Biomedical and X-Ray Physics, KTH, Stockholm
= 6-7 nm w/ Gd, Tb
in liquid jets?
Prague 2018
E.g., C16H28GdN5O9
MRI contrast agent
7% Gd by weight
Increase possible
,,: waterlike
Biomedical and X-Ray Physics, KTH, Stockholm
= 6-7 nm w/ Gd, Tb
nanoparticle slurries?
Prague 2018
(a) (b) (c)
(d) (e)
Y Zr Nb
Uniform size distribution
Potentially >10-20 % by weight
,,: waterlikeLi et al, submitted (2018)
MRI contrast agent :
Gd2O3 NP:s
Biomedical and X-Ray Physics, KTH, Stockholm
= 2-4 nm?
Prague 2018
Ethanol
Methanol
Liquid nitrogen
Rymell et al, Opt. Commun. (1993) Berglund et al, RSI (1996)
Biomedical and X-Ray Physics, KTH, Stockholm
= 2-4 nm
Power?
Prague 2018
Ultraviolet prepulse for enhanced x-ray emission and brightness
from droplet-target laser plasmasM. Berglund,a) L. Rymell, and H. M. Hertz
Department of Physics, Lund Institute of Technology, P. O. Box 118, S-221 00 Lund, Sweden
~Received 28 May 1996; accepted for publication 9 July 1996
We show that an ultraviolet prepulse significantly enhances the water-window x-ray emission and
brightness for a droplet-target laser plasma. By combining a 65 mJ, 120 ps, =532 nm main pulse
with an up to 3 mJ prepulse, the emitted x-ray photon flux may be increased more than eight times.
The resulting C VI =3.37 nm line emission is more than 3×1012 photons/sr.pulse, corresponding
to a conversion efficiency above 3%/line. The integrated spectral brightness is increased two times
and is found to reach its maximum for different prepulse parameters than those resulting in
maximum photon flux. © 1996 American Institute of Physics. @S0003-6951~96!03938-1#
Berglund et al, APL (1996)
106 drops/sec
Biomedical and X-Ray Physics, KTH, Stockholm
= 2-4 nm
Power II
Prague 2018
Berglund et al, APL 1996: Target: C2H5OH (52% C by weight)
Emission: = 3.37 nm E=368 eV (C VI)
Laser: 3+65 mJ/pulse
Flux: 3×1012 photons/sr×pulse
Assume:Rep rate: 105 Hz
Laser: 100 mJ/pulse (i.e., 10 kW)
Collection: sr
Results in:Approx. 100 W @ =3.37 nm
Issues?:Jet stability?
Self absorption?
Biomedical and X-Ray Physics, KTH, Stockholm
Summary
• Liquid-jet laser plasmas w/ =2-11 nm
emission are decently well understood.
• Power? – possibly
• Stability? – possibly
• Mirrors? – see upcoming talk
• Will it happen?
Prague 2018
Biomedical and X-Ray Physics, KTH, Stockholm
Biomedical & X-Ray PhysicsDept of Appl. Physics @ KTH/Stockholm
Soft X-Rays
Hard X-Rays Eye Optics
X-Ray Optics
Ultrasonics
ultrasound control
Nanochemistry
Teaching & Technical
Biomedical and X-Ray Physics, KTH, Stockholm
Which are our options?
Prague 2018
From xxxx, SPIE ()
Biomedical and X-Ray Physics, KTH, Stockholm
IN PARALLELL
First liquid-droplet EUV source – oxygen @ 13 nm
Prague 2018
Rymell et al, Proc. XRM IV (1993)
Ethanol target
Nd:YAG 10 ns
Low debris
Biomedical and X-Ray Physics, KTH, Stockholm
EUV sources II:
Next liquid-droplet EUV source - water droplets
Prague 2018
Inte
nsi
ty (
arb
. u
nit
s)1
0.5
010 11 12 13 14 15
Wavelength (nm)
Hertz et al, SPIE (1995)
Malmqvist et al, EUV Litho, OSA (1996)
Why use liquid jet/droplet laser-plasmas for HVM EUV litho?
• Thermal• Hot plasma at a distance
• High average power via high rep rate• Rapid target material production
O VII @ 13 nm
Biomedical and X-Ray Physics, KTH, Stockholm
Liquid-jet/droplet laser-plasma sources:
Early history
Prague 2018
1992
First liquid-droplet
Laser-plasma slide
First spectrum
First crew
1988?
First XRM slide1990
Cf. Göttingen