Surface Functionalization by Atomic Layer Deposition...2014/11/19 · SIM User Forum - Gent -...
Transcript of Surface Functionalization by Atomic Layer Deposition...2014/11/19 · SIM User Forum - Gent -...
Surface Functionalization by Atomic Layer Deposition
Geert Rampelberg
SIM User Forum - Gent - 2014-11-19
CoCooN Conformal Coating of Nanomaterials
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Atomic layer deposition (ALD)
• Gas-phase thin film deposition technique
• Cyclic process of self-limiting surface reactions layer-by-layer growth
Example : ALD growth of Al2O3 from trimethyl aluminum (TMA) and H2O
TMA pulse Self-saturated chemisorption
One (sub)monolayer of Al2O3
New OH groups at the surface Water pulse
Figure courtesy of Cambridge Nano-Tech Inc.
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Conformal coating of complex 3D surfaces
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Conformal coating of complex 3D surfaces
ALD coated tissue paper
Thermal ALD, TMA + H2O, 50°C, 200 cycles.
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Conformal coating of complex 3D surfaces
After combustion of the cellulose template: hollow structure, consisting of freestanding 20nm Al2O3 ALD film.
Direct, macroscopic illustration of the conformality of ALD, and of its potential for coating porous and fibrous materials.
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Linearity: thickness proportional with number of cycles
• Linear growth of Al2O3 as a function of ALD cycles • Atomic level control of layer thickness • Limitation to thin films – ALD as a method for nanocoatings & surface engineering
Growth rate per cycle from linear fit
0.85 Angstrom/cycle
0 50 100 150 200
0
50
100
150
50 52 54 56 58 60
36
38
40
42
44
Thic
kness (
Angstr
om
)
Cycle number
5 nm
Advantages of ALD
Excellent conformality
Excellent control of
Thickness
Stoichiometry
Highly uniform
Easily upscalable
Limitations of ALD
Slow – limited to nanocoatings and surface engineering
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Advantages and limitations of ALD
Layer-by-layer deposition
ALD is ideal tool for 3D surface engineering
• Controlling surface properties: adhesion, friction, hydrophobicity
• Surface functionalization: catalysis
• Surface passivation: diffusion barriers, encapsulation, anti-corrosion
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ALD – a coating technique for the nano era
TiO2/V2O5/TiO2 multilayer coating of a carbon nanotube
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ALD for surface engineering: Making a Kleenex tissue hydrophobic …
“Original” tissue ALD coated tissue (200 cycles Al2O3)
Thermal ALD, TMA + H2O, 50°C
Davy Deduytsche
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Functional nanocoatings in micro-electronics
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ALD nanocoatings for encapsulation: Protecting silver objects from tarnishing
Problem: silver objects require cleaning
after some time
ALD solution: 10nm Al2O3 “sapphire-like”
coating
Accelerated tarnishing test:
uncoated
ALD coated
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Scalability: batch, spatial, R2R
Spatial
ALD
e.g. SolayTec: 4500 wafers/hour
Roll to roll
ALD
Beneq: 400.000 m²/year
Large
batch
ALD
reactors
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Reactor concepts for thermal ALD on powders
Rotary reactor
Spatial ALD particle reactor
Fluidized bed
reactor
Vibrating reactor
D. Longrie et al., J. Vac. Sci. Technol. A, 32(1), Jan/Feb 2014.
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Rotary reactor for thermal and PE-ALD on powders
Precursors and reactants
Turbomolecular pump
Connection for MS / OES
Furnace
Rotating dielectric tube
Plasma coil (ICP)
• First PE-ALD on powders worldwide!
• Patent application: rotary reactor for PE-ALD on powders.
• Advantages of PE-ALD: – Lower processing
temperatures – Higher quality coatings – Cheaper precursor
chemistry available
• Demonstrated oxide/nitride coatings on oxide/metal particles.
D. Longrie et al., J. Vac. Sci. Technol. A, 32(1), Jan/Feb 2014.
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ALD on powders
Longrie et al., Surface and Coatings Technology, 213 (2012) 183.
Geldart diagram
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Applications
LED: Encapsulation of phosphor powders
Battery powders: improved cyclability
Catalysis: • Induce / enhance catalytic
activity • Reduce material
consumption (e.g. Pt)
140 150 160 170 180 190 200 210 2200
20
40
60
80
100
convers
ion (
%)
temperature (°C)
parent CBV-712
ALD-coated CBV-712
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FUNC
FUNC: Tools for dry nanofunctionalization of
particles and fibrous materials
Functionalization of novel types of powder substrates
– Polymer particles
– Steel fibres / CNTs
– Porous powders
Atmospheric plasma @ VITO
Thermal and PE-ALD @ UGent
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AP & ALD
WP1 Surface functionalization of
polymer particles by AP / ALD
WP2 Surface functionalization of porous particles by AP/ALD
WP3 Surface functionalization of micro/nanofibers by AP/ALD
WP4 – Characterization
Report on coating feasibility + properties
Report on application targets D wrt. non-functionalized reference
A1: Dispersability (NANOFORCE/SHE) A2: Flowability (STREAM) A3: Adhesion to matrix (NANOFORCE) A4: Chemical stability in various pH (SHE)
G1: Uniformity of coverage G2: Control of degree of coverage G3: Adhesion of coating to particle/fiber G4: Conformality / pinhole free
FOTO
Strategisch initiatief Materialen – SIM
P/a. Mr. Guido Verhoeven
General manager SIM
Technologiepark 935
9052 Zwijnaarde.
Drogenbos, 28 October 2012
Concerning: SIM Horizontal program TRAP – “TOOLS FOR RATIONAL
PROCESSING OF NANOPARTICLE BASED MATERIALS”
Dear Mr. Verhoeven,
With this letter, CYTEC Surface Specialties, formally endorses the rationale behind
the research proposed in the SBO project.
Especially the SBO-1 INSITU (“Tools for investigating the properties of nanoparticle
suspensions during dispersing and processing”) is of direct interest to our coatings
business.
In particular, we want to emphasize the importance of controlling and characterizing
the state of dispersed matter in liquid coating carriers in order to develop the full
property balance in the end coating application. We cite a few examples where our
business can effectively benefit from a technological lead following the approach
described in the SBO.
(a) The remarkable growth in market share of water-based radiation curable resins
along with the expansion of the product range towards complex colloidal
systems urge for the implementation of optimal dispersion processes, bearing
in mind that they also define the ultimate coating properties. Hence, strategies
for the improvement or modification of coating properties by controlling the
topology and morphology of colloidal resin particles are worth to be explored
in this field. Rheology, stability and film structure are three aspects that need
to be addressed at an early stage in order to design a robust liquid coating
system.
(b) Incorporation of functional organic or inorganic nanoparticles in a radiation
curable resin often causes rheological issues which severely limits application
of the liquid system on a substrate before transformation into a solid coating.
The presence of aggregates or other structures is detrimental to the
functionality development and, worse, may affect adversely the ultimate
performances of the materials. Predictive tools that can help to overcome the
rheological hurdles will open significant opportunities in the design of new
hybrid radiation curable resins.
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ACKNOWLEDGEMENTS
CoCooN Conformal Coating of Nanomaterials
Prof. dr. Christophe Detavernier Dr. Davy Deduytsche Dr. ir. Delphine Longrie ...