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www.joanneum.at June 24th, 2015 - Chemnitz
„Large-area patterning by roller-based
nanoimprint lithography“
Ursula Palfinger, Dieter Nees, Stephan Ruttloff,
Markus Leitgeb, Maria Belegratis, Barbara Stadlober
JOANNEUM RESEARCH Forschungsgesellschaft
Institute MATERIALS, Weiz, Austria
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2 Outline
Motivation – Small structures on large areas
Technology – Roll-to-roll Nanoimprinting (R2R NIL)
Processes
Machinery
Materials – Prerequisites for residual-free imprinting
Applications – Roller-based fabrication of highly resolved metal patterns by a combination of residual-free NIL and a subsequent lift-off for transparent conductive foils and product ID features
Summary
Outline
June 24th, 2015 - Chemnitz
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Small structures on large areas 3
Motivation
Superhydro-
phobicity Lotus effect
Point-of-Care
Diagnostics
Structural
Colours Camouflage,
Attraction
Light
management
Low
friction Riblets
Flexible
electronics OFETs
Adhesion Gecko-effect
Architecture Antireflectivity
Others:
Transport
Traffic
Security
Packaging
Energy Harvesting
…
Where is highly resolved
patterning on large areas
interesting?
June 24th, 2015 - Chemnitz
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Small structures on large areas 4
Motivation
Point-of-Care
Diagnostics
Structural
Colours Camouflage,
Attraction
Light
management
Low
friction Riblets
Flexible
electronics OFETs
Adhesion Gecko-effect
Architecture Antireflectivity
How can we
produce them? 1) micro and nano
2) 2D – 2.5D
3) large flexible areas
4) industrial process
Superhydro-
phobicity Lotus effect
June 24th, 2015 - Chemnitz
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Nanoimprint lithography 5
Technology
Fast + accurate method for structure transfer
UV or thermal curing of resist
Very versatile (geometries, structure size)
June 24th, 2015 - Chemnitz
Working stamp
Substrate, resist
Contact, imprint
Curing: T, UV
Release
1
2
3
4
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Nanoimprint lithography 6
Technology
Stamp Imprint
CD = 1.6 µm
June 24th, 2015 - Chemnitz
Fast + accurate method for structure transfer
UV or thermal curing of resist
Very versatile (geometries, structure size)
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Nanoimprint lithography 7
Technology
Stamp Imprint
CD = 200 nm
June 24th, 2015 - Chemnitz
Fast + accurate method for structure transfer
UV or thermal curing of resist
Very versatile (geometries, structure size)
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Nanoimprint lithography 8
Technology
Critical issues – Batch NIL (serial)
- Master (pattern quality, roughness)
- Control of adhesion between master and resist
- Resist viscosity (filling)
- Curing behavior (fast, low shrinkage)
- Fabrication volumes and process time
- Upscaling?
June 24th, 2015 - Chemnitz
Working stamp
Substrate, resist
Contact, imprint
Curing: T, UV
Release
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9
Technology
Roll-to-Roll Nanoimprint lithography
June 24th, 2015 - Chemnitz
line pressure
Substrate
Photoresin
(liquid)
Photoresin
(structured
and cured)
Working stamp
Substrate, resist
Contact, imprint
Curing: T, UV
Release rubber-coated
counter roller
Shim
on
roller
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Roll-to-Roll Nanoimprint lithography 10
Technology
Max. web width = 250 mm
Web speed = 0.5 – 30 m/min
Max. UV intensity = 200 W/cm
Line pressure UV-NIL = 18 kN
Line pressure HE = 100 kN
June 24th, 2015 - Chemnitz
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Resolution and throughput of printing technologies 11
Technology
Hig
h (
>1
) M
ediu
m
(0
,01
-1)
Low
(<
0,0
1)
High Resolution (< 10 µm) Medium Resolution
(10-50 µm) Low Resolution (> 50 µm)
Laser
ablation
R2R
photolitho
Inkjet
Rotary
screen Flexo
Gravure
Offset
Source: OE-A 2009, 3D-MM
Minimum feature size (µm)
Th
rou
gh
put (m
2/s
)
1 10 100 500
100
1
10-2
10-4
R2R – Nanoimprint lithography
R2R-vacuum
Flat
screen
June 24th, 2015 - Chemnitz
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12
Technology
Hig
h (
>1
) M
ediu
m
(0
,01
-1)
Low
(<
0,0
1)
High Resolution (< 10 µm) Medium Resolution
(10-50 µm) Low Resolution (> 50 µm)
Laser
ablation
R2R
photolitho
Inkjet
Rotary
screen Flexo
Gravure
Offset
Minimum feature size (µm)
Th
rou
gh
put (m
2/s
)
1 10 100 500
100
1
10-2
10-4
R2R – Nanoimprint lithography
R2R-vacuum
Flat
screen
Resolution and throughput of printing technologies
Source: OE-A 2009, 3D-MM
June 24th, 2015 - Chemnitz
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residue-free imprint
stuctured metal layer
metal
Application
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Creation of highly resolved metal patterns in R2R environment
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l : line width
s : space width
d : structure depth
ho: initial resist film thickness
Applications
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Critical for residual-free imprint: PATTERN GEOMETRY
June 24th, 2015 - Chemnitz
Structure depth and resist thickness
for open patterns
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t : imprint time
η : resist viscosity
l : imprinted line width
p : imprint pressure
hr : residual resist film thickness
ho : initial resist layer thickness
For vanishing residual resist film thickness
the imprint time approaches infinity ...
“Stefan’s equation”: p
H. Schift, J. Vac. Sci. Technol. 2008
Applications
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Critical for residual-free imprint: RESIST FLOW BEHAVIOR
June 24th, 2015 - Chemnitz
Squeeze flow model
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S = gSubstrate/Shim – (gSubstrate/Resin + gResinShim) < 0
gX/Y : interfacial energy S: spreading coefficient
SJ Choi, J. Colloid. Interface Sci. 2009
Applications
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Critical for residual-free imprint: SURFACES VS. RESIST CHEMISTRY
June 24th, 2015 - Chemnitz
Spontaneous dewetting and balance of interfacial forces
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• low viscosity
• water soluble
• monofunctional Non-ionic surfactant
η = 10 mPas
Photoinitator
e.g.
e.g.
Monomer
Tuning of interfacial energies
20 mN/m < g < 45 mN/m
Applications
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Critical for residual-free imprint: CHOICE OF RESIST
Auner, Palfinger et al, Organic Electronics, 2009+2010
Acrylate
UV-NIL resist for aqueous lift-off
polar rest group
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UV-Resist
PET
Applications
18 Residual-free R2R imprint
Zoom
SEM: cross section
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SEM: top view
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UV resist
PET
Applications
19 Residual-free R2R imprint
Zoom
SEM: cross section
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SEM: top view
1
2
water lift-off
metallization
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Applications
20 Al lines, CD = 1.6 µm
3 nm Cr + 30 nm Al
Lift-off with H2O
June 24th, 2015 - Chemnitz
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21
web direction
Applications
21 Al patterns, CD = 1.6 µm
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l/s = 1:4 web direction
Applications
22 Al patterns, CD = 400 nm
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SEM
Applications
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Application “nano”: Metal grids for transparent conductive foils
June 24th, 2015 - Chemnitz
400 nm
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SEM
Applications
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Application “nano”: Metal grids for transparent conductive foils
June 24th, 2015 - Chemnitz
400 nm
Source: PolyIC Source: Samsung PyzoFlex technology
Flexible displays, touch panels, sensor surfaces, shielding foils,…
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SEM
Applications
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Application “nano”: Metal grids for transparent conductive foils
200 nm
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Roller-based nanoimprinting is a large area, high resolution patterning
process with very high potential.
Residue-layer free R2R UV-NIL is possible, when pattern geometries
and stamp and resin surface chemistry is optimized.
We developed an acrylate-based imprint resin for water-based lift-off
and used it for highly-resolved metal patterning on foil without the
need of etching.
Applications can be seen in electronics, optics, sensing, security
features…, shown examples: transparent conducting, packaging
Summary
26 Summary
June 24th, 2015 - Chemnitz
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Dieter Nees
Markus Leitgeb
Stephan Ruttloff
Maria Belegratis
Herbert Gold
Laco Kuna
Volker Schmidt
Barbara Stadlober
Acknowledgements
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Lift-off in progress
Thank you for your interest!