roll-to-roll technology for transparent high barrier films · roll-to-roll technology for...

Roll-to-roll Technology for Transparent High Barrier Films

Presented at the AIMCAL Fall Technical Conference,October 19 - 22, 2008, Myrtle Beach, SC, USA

Nicolas Schiller, John Fahlteich, Matthias Fahland, Waldemar SchönbergerFraunhofer FEP, Germany

InstitutElektronenstrahl- undPlasmatechnik

aFraunhofer

FEP

Outline

Motivation and Approach

Magnetron PECVD process

Layer properties

Summary and Conclusion

Roll-to-roll Technology for Transparent High Barrier FilmsPresented at the AIMCAL Fall Technical Conference 2008

"Be flexible:" Flexible displays, signage, lightning, and solar cells

offer unique application and cost saving potentials.

Source: PolymerVision

Source: Konarka


Flexible substrates

Potential benefits for designers and users

• thin,

• low weight

• new design concepts

• Ultra low cost applications

Potential benefits for producers

• Roll-to-roll production scheme

However, Encapsulation is needed to protect the device from water vapor and oxygen


water vapor oxygen

Electronic devicepermeation barrier

flexible solar cell

flexible OLED

today:• Ultra-High-Barrier olny

with glass• not flexible

future:• thin film encapsulation for

ultra-high-barrier• low cost• flexible


Direct Encapsulation vs. Barrier Foil

Direct Encapsulation Barrier Foil

• All encapsulation processes must be compatible

• Substrate exposed to (plasma) process• All in vacuum roll-to-roll encapsulation

possible

• Free choice for processes (combine vacuumand non-vacuum processes)

• OLED and barrier development independent• Additional process: lamination


14.10.2008

Requirements and coating technologies for transparent barriers

10010110-110-210-310-410-510-6

Water Vapour Transmission [g / m² day]

Food Packaging

Solar Modules

Organic Electronic Devices

Polymers (intrinsic)

Evaporation

Sputtering

Combination Processes


barrier layer

Substrate(polymer film, OLED, solar cell…)

defect in barrier layer

Models suggest that barrier performance is controlled by defects in the barrier layer. (The layer itself is supposed to be impermeable.)

All concepts to improve barrier performance are focused to hinder the growth of defects.

Challenge of thin film encapsulation


Concept: dense single layer

Virtually defect free or low defect single barrier layer

• Atomic Layer Deposition – thin layer by layer deposition[1]

• Ion-beam assisted sputter deposition[2]

[2] R. Dunkel: High Performance low cost single layer barrier coatingson plastic, General Atomics Produktpräsentation

[1] P. F. Carcia et al.: APPLIED PHYSICS LETTERS 89, 031915 (2006)

sputtered Al2O3

GA - Super Sapphire

[2]

barrier layer

Substrate

Concepts: graded single layer

Graded (organic/inorganic/organic) layer


[1] A. G. Erlat et al.: Ultra-High Barrier Coatings for Flexible OrganicElectronics, SVC – 48th Technical Conference Proceedings, p. 116 (2005)

inorganicorganic

[1]

• Variation of film composition by changing process gas

• Batch-process not applicable for roll-to-roll encapsulation

interlayerbarrier layer


barrier layer

Multi-layer barrier

defect in barrier layer

• defect decoupling: tortuous path for moisture and oxygen diffusion

• increased lag time of diffusion

• decoupling of mechanical stress


Example: multi-layer barrier with ORMOCER®s

ORMOCER®

barrier layer ("PVD-layer")




Outline



Layer properties

Summary


All-in-vacuum approach: interlayer by Magnetron PECVD

interlayer: PECVD-layerbarrier layer ("PVD-layer")



"PVD-layer": Layer deposited by Physical Vapor Deposition (e.g.sputtering)


Why PECVD / PVD multilayer structure?

Main Goal: Development of an all-in-vacuum encapsulation technology for flexible

electronic devices

• Cost reduction with roll-to-roll encapsulation

• Magnetron-based PECVD and PVD run in one machine at the same time

• suitable for production of barrier films as well as direct encapsulation


Reactive Magnetron Sputtering


Magnetron PECVD

SiSi

O

CH3

pressure range: ca. 0,5 ... 5 Pa

High potential for large area/wide web processing

coating rate > 400 nm•m/min


multilayer stack for barriers

Combination of Sputtering with Magnetron based PECVD


Outline



Layer properties

Summary and Conclusion


Layer composition (HMDSO)

Process parameters:2.3 W/cm², HMDSO+O2= 80 sccm

measured using XPS

low amount of target material (Ti) incorporated into the layers

composition adjustable from silicon oxide like to polymer like layers

reference (sputtered SiO2)

0 6 13 19 25 31 38 44 50 560

10

20

30

40

50

60

Ti

Si

C

Con

cent

ratio

n [a

t. %

]

HMDSO/(HMDSO + O2) [%]

O


Mechanical Properties

• substrate: PET75 µm

• hardness measured for HMDSO:O2 = 1:10 using Nano-indentation

• lower hardness compared to sputtered layers

• low internal stress

6 13 19 25 31 38 44 500

1

2

3

4

5

9

10

SiCxOy - PECVD

sputtered SiO2

sputtered SiNx

hard

ness

[G

Pa]

HMDSO/(HMDSO + O2) [%]


Permeation Barrier Properties of SiOxCy

0 50 100 150 200 250 300 350 4000,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

WV

TR [

g/(m

²d)]

film thickness [nm]

ratio HMDSO:O2 7:73 20:60 40:40

substrate: 125 µm PET

polymer like layers reflect barrier properties of substrate

SiOx-like layers:WVTR > 0.2 g/(m2d)

increase of barrier performance at high thickness


Single layer optical coating (SiOxCy on PET)

• TEOS-based process

• Low internal stress

0 500 1000 1500 2000 2500

0

20

40

60

80

100

Tran

smis

sion

[%]

Wavelength [nm]

80 nm 240 nm uncoated PET


Magnetron PECVD in optical multilayer stacks

PET substrate

SiO Cx y

TiO2

appr. 640 nm

300 400 500 600 700 800

0

20

40

60

80

100

Tran

smis

sion

[%]

Wavelength [nm]

SiOxCy + reactively sputtered TiO2


Pilot sputter roll coater coFlex® 600flexible substrates (polymer webs, thin metal foils)

600 mm deposition width

web speed 0,1...100 m/min

6 coating stations (dual magnetrons)

Pulsed Magnetron Sputtering

Magnetron PECVD


Pilot roll coater novoFlex® 600flexible substrates (polymer webs, thin metal foils)

600 mm deposition width

web speed 0,1...600 m/min

double side coating

5 coating stations

combination of evaporation, sputtering and PECVD


Scaling up to pilot-scale


reactivesputtering

Magnetron-PECVD

Deposition Rates

• deposition rate increases with monomer flow

• higher rates at higher power: 400 nm*m/min possible at 20 kW (7 W/cm²) with HMDSO and HMDSN

HMDSN 10 kW


Long term process stability

plasma impedance increases within first 30 min

dynamic deposition rate stabilizes within 15 min

rate drift within 6 hours± 5%


Multilayer barriers - Sputtering + Magnetron-PECVD

PEN

ZnSnOx – 75 nm

SiOx - PECVD - 60 nm (7:73)

ZnSnOx – 75 nm

PEN

ZnSnOx – 75 nm

SiOx - PECVD - 60 nm (7:73)

PEN

ZnSnOx – 75 nm

WVTR = 0,045 g/(m²d)

WVTR = 0,045 g/(m²d)

WVTR = 0,007 g/(m²d)


Outline



Layer properties

Summary


Summary

InstitutElektronenstrahl- undPlasmatechnik

aFraunhofer

FEP

A novel concept for the all-in-vacuum, roll-to-roll deposition of multilayer barrier stacks has been developed. The basis of the concept is the in-line combination of magnetron sputtering and a magnetron PECVD-process.

The magnetron PECVD process offers several benefitslow working pressure of 0.5 Pa up to few Pa, thus allowing the in-line combination with sputtering processwide range of properties for SiOxCy layers high potential for large area processing by using dual magnetrons as power sourcehigh coating rates (> 400 nm•m/min)

Our basic concept allows an all-in-vacuum roll-to-roll deposition of multilayer barrier stacks. The process has been installed in a pilot-scale multi-chamber pilot roll-to-roll coater.

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