A.E. Yakshin, R.W.E. van de Kruijs, E. Zoethout, I

A.E. Yakshin, R.W.E. van de Kruijs, E. Zoethout, I

Interface engineering of Mo/Si multilayers for enhanced
reflectance in EUVL applications
A.E. Yakshin, R.W.E. van de Kruijs, E. Zoethout, I. Nedelcu, E. Louis, F. Bijkerk FOM Rijnhuizen, Nieuwegein, The Netherlands
H. Enkisch, S. Müllender, Carl Zeiss, Germany
Coating facilities @ FOM
Deposition processes: principle layout of
different process elements
Available technologies
Combination of deposition with particles of
different energy
layer thickness monitor
(x-ray + quartz)
substrate
plasma surface
treatment
ion surface
treatment
- Combines thermal, medium energy
deposition, plasma & ion surface
treatment
E-beam
evaporation
- TPM * method
Thermal energy
particles
- precision deposition of ultra-thin film
- deposition compounds
Magnetron
sputtering
Free
movement
of particles
E~0.1 eV
- tunable energy of particles
Thermal & medium energy
deposition
(TPM sputtering)
• Extended parameter range & collection of deposition
techniques
• Goal: Technology development for future Zeiss coaters &
process exploration
E-beam
4:1 B/C (B4C)
14000
Low energy ion
bombardment
+ + +
plasma
E ~ 10-50 eV
Interferometry:
• 0.2 nm B4C S=-150 MPa
• 0.4 nm B4C S=-250 MPa
Si
12000
Mo
10000
Diffraction from Mo crystallites
B4C on Si_0.2
6000
B4C on Mo_0.1
4000
2000
15000
B4C
15200
15400
15600
15800
16000
16200
16400
Time (s)
~4.0nm
Intensity, cps
B4C on Mo_0.2
0.015
8000
16000
14000
12000
10000
8000
0.01
Lattice strain
Intensity, cps
~4.0nm
16000
B4C on both_0.2
B4C, 2 on Mo, 3 on Si
B4C, 4 on Mo, 5 on Si
0.005
std
std
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-0.005
6000
out-of-plane strain
4000
2000
0
5000
10000
15000
20000
25000
30000
in-plane strain
-0.01
fc200406
0
Sin 2 Ψ (diffraction angle)
35000
Time (s)
B4C compound in 4:1 stoichiometry can be
obtained using both processes
0
0
Example of stress analysis
Raw in-situ signal (not filtered)
4:1 B/C (B4C)
0
Ar+, Kr+
Gas phase
collision
processes
Ion bombardment: atom mobility, reconstruction, formation of
compounds
* TPM – thermalized particles magnetron
Example: E-beam deposition of B4C interlayers
using X-ray monitoring
Magnetron
+ + +
Higher energy particles: growth of the bulk layer
• in-vacuum XPS, AES, SEM
Example of XPS analysis: B4C layer
E << 10 eV
Thermal E particles: nucleation 1-2 monolayers of a new layer,
avoiding intermixing
• low energy ion surface analysis
• Reflectivity: >68 % (capped real optic)
E~10 eV
- x-ray monitoring + quartz combined
thermal energy deposition
(e-beam evaporation)
• in-vacuum STM (pending)
• Lifetime: 30.000 hrs
Surface
+ + +
melt
Analysis
• Focus:
Low energy
particles
E~100-1000 eV
- Precision thickness control
Properties
High energy
particles
0
- Variable deposition geometry
Surface
treatment
TPM
Diffraction in qualitative agreement with interferometry
measurements
X-ray monitoring allows to control growth of
thin interlayers
Thermal stability Mo/X/Si/X
Best EUV reflectances
70.5% @ 13.3 nm
0,8
70.15% @ 13.5 nm
0,7
PTB data
Reflectance
0,6
1.5 degrees offnormal
0,5
Barrier layer X at
two interfaces
0,4
0,3
0,2
0,1
0
12,7
12,9
13,1
13,3
13,5
13,7
13,9
14,1
Wavelength, nm
No change is observed in ML properties around 100°C
Bandwidth
Conclusions
0.8
Reflectance
depth
graded
ML
With barriers
Plain multilayer
0.6
0.5
New e-beam and magnetron-based coating technologies
allow interface engineering
Best value 70.5% @ 13.3 nm, 70.15% @ 13.5 nm
0.3
Stress -250 MPa without stress compensation layer:
considerably lower than earlier magnetron results on barrier
layers (400MPa, M. Shiraishi SPIE 2004-5374-11)
0.2
0.1
Wavelength (nm)
0
12.8
13
13.2
13.4
13.6
Carl Zeiss (Oberkochen )
Reflectivities above 70% routinely obtained both by e-beam
and magnetron sputtering
FWHM=0.53-0.54
0.4
Acknowledgments
Example calculation
depth graded ML
Measurement
0.7
Current trade-off between reflectivity and stability shows
possibility for improvement.
13.8
14
Bandwidth slightly increases after introducing barriers, in
agreement with calculations
Further broadening requires optimized stack designs
Ref: Kozhevnikov et.al, 6PXRMS 2002, Chamonix
First results on thermal stability preserving high reflectivity
are very promising (<0.01 nm CTW @ 150°C)
BW approaches theoretical 0.55 nm value when using barrier
layers
http://www. zeiss.de/
BMBF Project ‘Grundlagen der EUV -Lithographie 13N8088 and
MEDEA Project EXTATIC
’
Foundation for Fundamental Research on Matter (Utrecht)
http://www. fom.nl/ and
www. rijnh.nl
More Moore, IST–1-507754 -IP
ASM Lithography ( Veldhoven, The Netherlands)