SUBSTRATE CLEANING IN A

HIGH VACUUM ENVIRONMENT

Sheila Hamilton

Teknek Limited

Issue

• Particles of contamination on substrates

cause defects in coating, printing,

lamination and vacuum deposition

processes used in Flat Panel display

manufacturing

• Defects cause significant yield loss

• Removal of particles is essential for high

functionality and reliability

AIMCAL 2013

Technology Drivers

AIMCAL 2013

• Films are getting thinner - more difficult to process

• Coatings are getting thinner – even nanoscale particles can

• penetrate the entire thickness of the coating causing pinholes

• No air or wet systems can be used in vacuum environments

• Smaller particles can now cause defects

• Barrier properties are more demanding

Challenges

AIMCAL 2013

• Need a cleaning system which can

operate under vacuum

• Needs to be able to remove very small

particles

• Cannot use air or liquid for cleaning

• Must not alter the surface energy

• Must not outgas

Contact Cleaning Technology

The Teknek Cleaning Core

PPT 7 / 21

AIMCAL 2013

Cleaning Technologies

AIMCAL 2013

Defect reduction in optical

coating

AIMCAL 2013

Repeat Defects

AIMCAL 2013

Pinhole reduction in metallised film

0

10

20

30

40

50

60

70

No cleaning CRC Vacuum Plasma

Cleaning Operation

Pin

ho

le D

en

sit

y (

>5

µ)

/ c

m²

(x1

00

) Average Pinhole

Density of commercially

available metallised

polyester film

AIMCAL 2013

Outgassing Test

• Scud Vacuum System 032

• 2 small rollers

• 2 sheets adhesive

• Pumped down to 1E-7 mbar

• Time in vacuum 66 hours

• Each sample weighed before and after.

AIMCAL 2013

Ultracleen RGA

AIMCAL 2013

Ultracleen Outgassing

AIMCAL 2013

Nanocleen RGA

AIMCAL 2013

Adhesive Roll RGA

AIMCAL 2013

Cleaning Efficiency Test

roller roller vacuum

condition adhesive sheet condition weight

before weight

after Differen

ce [g]

nanocleen ambient ambient 4.31 4.57 0.26

1 weekend in vac (0.1

mbar) 4.31 4.54 0.25

18 hours in high vac (1e-6

mbar) 4.3 4.55 0.25

1 weekend in vac

(0.1 mbar) ambient 4.31 4.57 0.26

1 weekend in vac

(1e-6 mbar) ambient 4.3 4.55 0.25

nanocleen ambient ambient 4.31 4.6 0.26

ambient ambient 4.3 4.55 0.25

AIMCAL 2013

AIMCAL 2013

AREAS OF APPLICATION

• After stripping of protective film to remove

possibility of static induced recontamination

• Immediately prior to sputtering to remove any

particles deposited from the walls of the

chamber

• Before rewind to stop particles imprinting on the

layer below or fracturing the film

• Cleaning the protective film at rewind prior to

application to stop damage to the coating

AIMCAL 2013

Benefits

• Teknek technology can now

– Remove particles down to 100 nm

– From all types of substrates

– As thin as 15 microns

– In both sheet and roll format

– At speeds from 1m/min to 300m/min

– In a high vacuum environment

– Without silicone

– Gives significant yield improvements

AIMCAL 2013

Acknowledgements

• European Funding Programme FP7

Clean4Yield project

• The Holst Institute, Eindhoven

• The Technical University of Dresden

AIMCAL 2013