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

www.cocoon.ugent.be 2 SIM User Forum - Gent - 2014-11-19

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.


Conformal coating of complex 3D surfaces



ALD coated tissue paper

Thermal ALD, TMA + H2O, 50°C, 200 cycles.



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.


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


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


ALD – a coating technique for the nano era

TiO2/V2O5/TiO2 multilayer coating of a carbon nanotube


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


Functional nanocoatings in micro-electronics

http://www.asm.com/images/stories/products/himg_ci79.jpg


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


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


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.


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.


ALD on powders

Longrie et al., Surface and Coatings Technology, 213 (2012) 183.

Geldart diagram


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


FUNC

FUNC: Tools for dry nanofunctionalization of

particles and fibrous materials

http://www.vub.ac.be/

Functionalization of novel types of powder substrates

– Polymer particles

– Steel fibres / CNTs

– Porous powders

Atmospheric plasma @ VITO

Thermal and PE-ALD @ UGent


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.

www.cocoon.ugent.be SIM User Forum - Gent - 2014-11-19 20

ACKNOWLEDGEMENTS

CoCooN Conformal Coating of Nanomaterials

Prof. dr. Christophe Detavernier Dr. Davy Deduytsche Dr. ir. Delphine Longrie ...

surface functionalization by atomic layer deposition...2014/11/19 · sim user forum - gent -...

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