Flexible Glass Substrates for Continuous Manufacturing

Science &Technology

Flexible glass substratesfor continuous manufacturing

Corning - S. Garner , G. Merz , J. Tosch,J. Matusick, X. Li , D. Marshall

CAMM - C. Chase, J. Steiner, D. Yepez,J. Switzer, P. Moschak

February 9, 2011

2© Corning Incorporated 2011Science & Technology

Outline

• Flexible glass for electronic devices

• Flexible glass mechanical reliability– Strength– Coatings– Stress

• Roll-to-roll photolithography

• Summary


Flexible Glass Enables High-Quality ElectronicsSubstrate choice critical for device fabrication & performance• Substrate integrates designs, materials, & processes

– Essential for overall optimization– Glass enables improved resolution, registration, performance & lifetime

Flexible Glass•Thermal stability•Dimensional stability•Hermeticity•Optical transmission•Surface roughness

Device DesignsE-paper, touch sensor, PV, OLED

MaterialsConductor, semiconductor, dielectric

Continuous Processes•Patterning (gravure, ink jet, photolithography)•Etching (wet, plasma)•Coating (lamination, slot die, vacuum)

Capabilities

Requirements

Flexible glasssubstrate

Flexible glassbarrier


Glass Surface & Bulk Properties Optimize DevicesFlexible glass device capability demonstrated in <170µm LCD

• Twisted nematic LCD• qVGA (320 x RGB x 240)• 4”diagonal (80mm x 60mm)• Pixel size 83µm x 250µm• Aperture 52%

• a-Si:H active matrix backplane• TFT channel L=10µm, W=50µm

• Polymeric substrates not compatible– 300°C backplane fabrication– 210°C frontplane fabrication

• 75µm flexible glass thickness– LC cell <170µm

S. Hoehla, et al., “Full Color AM-LCDs on Flexible Glass Substrates”, IDW 2010, p.1689-1692.


0

20

40

60

80

100

200 400 600 800Wavelength (nm)

Tran

smis

sion

(%)

Glass Enables Performance & Process OptimizationFlexible glass offers dimensional stability for R2R fabrication

Surface Roughness

Glass PEN Polyimide

0

1

2

3

4

A B A B A B

Ra

(nm

) Ra

0

50

100

150

200

Rpv

(nm

)

Rpv

Optical TransmissionGlass

PEN

Polyimide

Dimensional Stability

0

10

20

30

40

50

0 0.5 1 1.5 2Strain (%)

Stre

ss (M

Pa)

Glass25°C

PEN25°C

Polyimide25°C

& 150°C

150°C

150°C


Mechanical Reliability of Flexible GlassSubstrate solutions optimized for continuous processing

• Mechanical reliability of glass understood– Failure due to distributions of defects & applied stresses– Bend strength independent of thickness

• Mechanical reliability requires controlling defects & applied stress– High strength glass forming including surfaces & edges– Protecting substrate from damage– Managing stresses during conveyance, handling & application

0

100

200

300

400

500

0 5 10 15 20 25 30Bend Radius (cm)

Ben

d St

ress

(MPa

)

500µm100µm

50µm

1.000.100.01

90

50

2010

5

21

Bend Radius (cm)

Failu

rePr

obab

ility

(%)

0.11Bend Radius (cm)

10

100µm200µm

~10mm


Glass After Forming is Inherently StrongManaging defect size & distribution enables reliability• Pristine glass surfaces are extremely strong

– Bend strengths >6GPa measured in substrate compositions– Subsequent handling & environment can reduce strength ~100x

• Glass strength depends on glass history– Quality of surfaces & edges critical

1000500200100502010

99

90

50

20

10

5

2

1

Bend Stress (MPa)

Failu

rePr

o bab

ilit y

( %)

Surface damage

Crack systems

Edge quality affects bend strength

Surface quality affects bend strength


Protective Coatings Preserve Glass StrengthCoating selection specific to application

• Crack systems form when flaw size & stress reach threshold

• Coatings minimize contact damage induced during:– Handling, packaging, shipping– Device manufacturing– In-service use

• Coating optimized for specific device & fabrication processes– Material & thickness selected for anticipated conditions– Full-width and partial-width coatings enable different device designs– Mechanical properties dominated by glass

Coated Substrate Cross-Section

70µm glass 10µm coatings


Convey Flexible Glass with Roller SystemsRequires managing bend stress during device fabrication

• Flexible glass is flexible –Do not handle as rigid substrate– Stiffness of 50µm glass 120µm PEN– Control stresses through roller handling system– Approach compatible with sheet-fed or roll-to-roll systems

Conveyance in CAMM ECD Tool Al Sputtering in CAMM General Vac System

Un-wind

Re-wind Glass webDeposition

drum

Glass web


Flexible Glass is Compatible with R2R ProcessingDemonstrated continuous ITO patterning

CoolingDrum

ITO Deposition Slot Die Coating

Supply Roll Take-Up Roll

Exposure

Supply Roll Take-Up Roll

Development & Etch


• Spooled glass with partial width coating• 10µm ITO lines with 30 Ω resistivity

Roll-to-Roll Patterning of 10µm ITO LinesDeposition, slot coat, repeated exposure, develop & etch

Patterned Photoresist

Reflection

Transmission

50µm

50µm

Patterned ITO

Reflection

Transmission

50µm

50µm


Summary

• Flexible glass offers advantages for device designs, materials & processes– Includes dimensional & thermal stability and hermeticity– Enables high performance active devices

• Glass mechanical reliability understood– Form high initial strength & minimize defects– Manage stresses with appropriate conveyance– Optimized solutions are application specific

• Flexible glass is compatible with continuous processing– Demonstrated patterning of 10µm ITO lines– Process optimizations possible to take advantage of glass capabilities


Acknowledgements

• Corning– Scott Glaesemann– Don Clark– Jill VanDewoestine– Michael Sorensen

• CAMM– Mark Poliks

Flexible Glass Substrates for Continuous Manufacturing

Documents