Large-area thin film depositions – can ALD have a role?

Markku Leskelä

University of Helsinki

Department of Chemistry

Laboratory of Inorganic Chemistry

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Content

Existing large area applications

Emerging large area applications

Equipment used in large area applications

Where is ALD ?

Conclusions

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Existing large area applications

Often roll-to-roll coaters (web coaters)web shaped substrates

plasticspapermetal foils cloths

film deposition (immersion, gravure printing etc. excl.)most often by evaporation or sputtering but also by CVDlarge area, high throughput processes

up to 1000 m/minroll length up to 60 km, width up to 4 mbillions (109)of m2 every year

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Existing large area applications

decorative Al coatings (~30 nm) for packaginggas tight Al barriers (~50 nm) for food packagingcapacitor electrodes on two sides of polymer foils coatings (CoNi) for magnetic tapesCu coatings for flexible printed circuitsinfrared reflecting heat mirrors on polyester films

dielectric-metal-dielectric three-layer coatingfilms with special optical or magnetic properties forsecurity labels for anti-theft detectionmetals and transparent conductor for solar cells

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Existing large area applications

Usually single thin films Many glass applications: photocatalysts, conducting glasses

Photovoltaics needing several layers (made in one process) is growing fast

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Emerging large area applications

Coatings on paper and polymers (barriers) – low temperature processes Patterned filmsDisplaysPhotovoltaics (different PV approaches)

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Equipment used in large area applications

Plasma depositions (atmospheric plasma increases fast) Different PVD systems (sputtering, evaporation, PLD) and their combinationsSol-gelCVD (pyrolysis type)

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Pilkington, for example, uses for glasses:- plasma depositions (metals, oxides, nitrides) - sputtering (multi-layers) - CVD (precursors sprayed on hot glass – typically oxide films)

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Applied Materials’ system for flexible PV allowing deposition of all materials needed for a solar cell using different deposition techniques.

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Applied Materials, a giant tool manufacturer for microelectronics (Intel), modified its equipment for making flat-panel displays to fit the needs of the solar industry. Pictured here is a CVD system for making amorphous silicon solar cells.

11Evaporation used for metal coating

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PVD

Web coaters

each sputter compartment is separately pumped and nearly completely separated from the neighbor compartments: possibility to employ e.g. oxygen containing and inert atmospheres next to each other

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ALD technology now at Beneq Oy

ALD

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Large scale production ALD reactor by ASM Microchemistry in 90s.

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Reactor for 1.2 x 1.2 m

Beneq Oy

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Kodak, ALD 2008, Brugge

Interest towards roll-to roll ALD increases

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WO/2008/057625: SYSTEMS AND METHODS FOR ROLL-TO-ROLL ATOMIC LAYER DEPOSITION ON CONTINUOUSLY FED OBJECTSBy General Electric

Embodiments of the invention include a roll-to-roll atomic layer deposition (ALD) device. The device includes mechanisms to enable relative movement between a substrate to be deposited upon and various chambers containing ALD precursor gases.For ultra-high permeation barriers.

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1 m x 1 km x 1 nm = 1 cm3 material. 20 nm Al2O3 film = 20 cm3

= 70 g. Requires 100 g TMA and 37 g H2O. Excess increasesthe amounts 2-3 times. With gaseous precursors (RT) it maywork but with low volatility precursors material transport is a problem.

Is there any sense to make ALD roll to roll. ALD is aimed for high quality films on complex structures. Answer is maybe no ifsingle layer on flat surface is needed. Answer is yes if the material is more complicated (multilayer), surface is structured, or patterned structures (?) are needed.

Should the Finnish industry concentrate on tool manufacturingas now or is high volume production possible in Finland?