1

A Flexible ActiveA Flexible Active--matrix Electronic Paper matrix Electronic Paper Display Driven with Amorphous Oxide Display Driven with Amorphous Oxide

SemiconductorsSemiconductors

M. Ito, M. Kon, M. Ishizaki, C. Miyazaki, and Y. Ugajin

Toppan Printing Co., Ltd.

Technical Research Institute

2

OutlineOutline

1. Background--- Electronic Paper--- Flexible Display--- Oxide TFT

2. Experimental3. Results

--- Characteristics of amorphous oxide TFT on plastic film--- Flexible electrophoretic display driven with amorphous

oxide array--- Proposing further cost reduction process of providing

oxide TFT array

4. Future Scope5. Summary

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What is Electronic Paper?What is Electronic Paper?

Display Printed Media

· Dynamically Rewritable· Compatible with Digital

Information· Less Waste

· Readability· Portability· No Power Consumption

: Best of Both Worlds!Electronic Paper

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What is Essential for Electronic Paper?What is Essential for Electronic Paper?

RewritableRewritable Image StabilityImage Stability ReflectiveReflective

Thin & LightThin & LightHigh ContrastHigh Contrast

Wide Viewing AngleWide Viewing Angle

ColorColor

High ResolutionHigh Resolution

FlexibilityFlexibility

PriorityPriority

HighHigh

LowLow

MustMust

Proposed by Proposed by TakasoTakaso(Techno(Techno--SystemSystem--Research)Research)

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Philips LiquavistaElectrowetting

SiPix, Toppan FormsMicrocup

E Ink, Toppan PrintingMicrocapsuleElectrophoretic

Electrochemical

GyriconTwist BallRotatable Beads

BridgestoneElectronic Liquid Powder

Powder Movement

Pilot CorporationMagnetic ParticleMagnetphoretic

Zenithal Bistable DisplaysBistable TN

Dai Nippon InkPolymer Network

Kent, Fujitsu, Asahi GlassCholesteric LCD

LCD

AffiliationDisplay Method

Various Types of Electronic PaperVarious Types of Electronic Paper

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Figures of Merit for Various Electronic Paper TechnologyFigures of Merit for Various Electronic Paper Technology

ColorB/W

28464489MOEMS

47876745Bistable nematic

47776845Zenithal bistable

55755957Microcups

15643657Cavities and ribs

1089551068E Ink

ResultsMaturityElectronics Factor

Materials

Factor

TFT Factor

Image Quality

A. Henzen, The present and future of electronic paper, EuroDisplay 2005, p174

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E Ink Electrophoretic DisplayE Ink Electrophoretic Display

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Clear Fluid

Positively Charged White Pigment

Electrophoretic & Reflective

How E Inks WorkHow E Inks Work

Negatively Charged Black Pigment

9http://www.eink.com/

ITO

Microcapsule

Adhesive

E Ink Imaging FilmE Ink Imaging Film

E Ink Imaging Film

Thin Film Transistor (TFT)

Dark StateLight State Light State

+ + + + + + +- - - - - - - - - -

PET Film

Resolution is determined by pixel electrodes of TFT.

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PaperPaper--like Readabilitylike Readability

3 Key Benefits of E Ink Display3 Key Benefits of E Ink Display

UltraUltra--Low Power ConsumptionLow Power Consumption

Thin & Light Thin & Light

Higher contrast than newspaperWide viewing angle

Image stability

E Ink Imaging Film is on plastic substrate

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Announcement of Strategic Partnership in 2002Announcement of Strategic Partnership in 2002

E Ink & TOPPANE Ink & TOPPAN

- Major Shareholder- Color Filter Collaboration- Manufacturing Partner

TOPPAN manufactures E Ink Imaging Film (PET/ITO/Microcapsules/Adhesive)

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SONY eSONY e--Book Reader Book Reader LIBRILIBRIéé

Launched April 2004 in Japan

1st Commercial E Ink Display- 6" SVGA- High Resolution (appox. 170ppi)- 4 Gray Levels

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Applying a Color FilterApplying a Color Filter

Similar to Reflective LCD

+ + ­

R G B W

Bouchard, et.al., SID 1934 (2006)

4096 colors

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E Ink Electronic DisplayE Ink Electronic Display

RewritableRewritable Image StabilityImage Stability ReflectiveReflective

Thin & LightThin & LightHigh ContrastHigh Contrast

Wide Viewing AngleWide Viewing Angle

ColorColor

High ResolutionHigh Resolution

FlexibilityFlexibility

Already Already AchievedAchieved

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Flexible DisplayFlexible Display

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Market Forecast of Flexible DisplayMarket Forecast of Flexible Display

Sources： iSuppli

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Definition of FlexibilityDefinition of Flexibility

Four types of flexibility Four types of flexibility (Proposed by (Proposed by OmodaniOmodani, Tokai University), Tokai University)

Seiko-watch

Polymer VisionPolymer VisionPlastic LogicPlastic Logic

FormedFormed FlexibleFlexibleFlatFlat Rollable, FoldableRollable, Foldable

Level of ChallengeEasyEasy DifficultDifficult

Thin, Light, NonThin, Light, Non--fragilefragileDisplay made on plastic or other non-glass substrate

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Flexible DisplayFlexible Display

The backplane (TFT) is a key limiting factor in The backplane (TFT) is a key limiting factor in the commercialization of flexible displaysthe commercialization of flexible displays

Sources： iSuppli

Electronic display cardsElectronic display cardsPOP signagePOP signageLarger signageLarger signage

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Examples of Flexible TFTExamples of Flexible TFT

Organic TFTOrganic TFT

Philips & Polymer VisionPlastic Logic

Low mobilityPoor stability

Low process temperatureLong-term stabilityHigh mobility

Novel MaterialNovel Material

Heavy Expensive (Passivation)

aa--Si on SUS foilSi on SUS foilLG. Philips LCD

polypoly--Si Si (Transfer Technique)(Transfer Technique)

SEIKO EPSON

Difficulty in large area fabricationExpensive

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600 ºC1070.2Sol-gelZnOJPD 36, L105 (2003)

R. T.3× 10527SputterZnOAPL 85, 2541 (2004)

300 ºC10720Sputter(Zn,Sn)OAPL 86, 13503 (2005)

InZnO

aa--IGZOIGZO

Zn0.9 Mg0.1 O

SnO2

InGaO3(ZnO)5

ZnO

ZnO

Material

450 ºC1051SputterJAP 93, 1624 (2003)

JAP 97, 64505 (2005)

Nature 432, 488 (2004)Nature 432, 488 (2004)

APL 84, 2685 (2004)

JPD 37, 2810 (2004)

Science 300, 1269 (2003)

APL 82, 733 (2003)

Publication

300 ºC

R. T.R. T.

600 ºC

600 ºC

1400 ºC

> 600 ºC

Process Temp.

1035Sputter

1050.8Sputter

10610Sputter

>10>1055>10>10PLDPLD

10680PLD+R-SPE

1072.5Sputter

on/off ratio

mFE

(cm2/Vs)

Process

Transparent Oxide SemiconductorsTransparent Oxide Semiconductors

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K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano and H. HosonoNature 432, 488 (2004)

mFE > 10 cm2/Vs, on/off ratio > 106

Room temperature process

Amorphous Oxide Semiconductor : aAmorphous Oxide Semiconductor : a--InGaZnOInGaZnO

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Mechanism of High MobilityMechanism of High Mobility

K. Nomura et.al.,Nature 432, 488 (2004)

Covalent Semiconductors (Si)

Post-transition-metal Oxide Semiconductors

H. Hosono et.al., J. Non-Cryst. Solids, 198-200, 165 (1996)

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E Ink Imaging FilmE Ink Imaging Film Flexible Flexible aa--InGaZnO TFT ArrayInGaZnO TFT Array

capacitor

PEN

SiON

ITO (G)

ITO(S) ITO(D)a-IGZO

ITO

Ink LayerAdhesive

PET

Flexible Electronic PaperFlexible Electronic Paper

Flexible FPL

Flexible TFT array

PET

PEN

Lamination of E Ink Imaging FilmsLamination of E Ink Imaging Films

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ExperimentalExperimental

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Substrate : PEN (polyethylene naphthalete)Structure : Bottom Gate

Ar, O2

Ar, O2

Ar, O2

Ar, O2

Gas

50 nmITODC Sputtering

ITOSource & Drain

50 nmInGaZnO4RF Sputtering

a-IGZOChannel

280 nmSiNRF Sputtering

SiONGate Insulator

50 nmITODC Sputtering

ITOGate

ThicknessTargetProcessMaterial

Experimental DetailsExperimental Details

Room Temperature Process

Standard photolithography and lift-off technique

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2 inches, 80 × 60 pixels

Flexible TFT Array on PEN Film Magnified Image

Pixel Size : 500mm × 500mm

PEN / ITO[G] / SiON / a-IGZO / ITO [S&D]

Flexible Amorphous Oxide TFT ArrayFlexible Amorphous Oxide TFT Array

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ResultsResults

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Transfer Characteristic Output Characteristic

0 10 20 30 40 500.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

VGS

= 0VVGS

= 10V

VGS

= 20V

VGS

= 30V

VGS

= 40V

VGS

= 50V

Dra

in C

urre

nt, I

DS (

A)

Drain Voltage, VDS

(V)

normally off, mFE : 5 cm2/Vs

PEN / ITO[G] / SiON / a-IGZO / ITO [S&D]

Characteristics of an Amorphous Oxide TFT on PENCharacteristics of an Amorphous Oxide TFT on PEN

-20 -10 0 10 20 30 40 50

10-12

10-11

1x10-10

1x10-9

1x10-8

1x10-7

1x10-6

1x10-5

I DS (

A)

VGS

(V)

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Images of Flexible Electrophoretic Displays Images of Flexible Electrophoretic Displays Driven with aDriven with a--IGZO TFT ArrayIGZO TFT Array

supplied by supplied by

Electrophoretic imaging filmElectrophoretic imaging film

Thickness : 320 Thickness : 320 mmmmWeight : 1.3 gWeight : 1.3 g

E Ink Microcapsule Driven with a-InGaZnO TFT

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Progress Since 2005Progress Since 2005

October 2005

IDW 2005IDW 2005

2006

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For further cost reductionFor further cost reduction-- Fabrication process of oxide TFT Fabrication process of oxide TFT --

GateGate

Deposition of ITOSpin coating of resistExposureDevelopmentEtchingRemoval of resist

ChannelChannel

Deposition of SiON

Source & DrainSource & DrainSpin coating of resistExposureDevelopment Deposition of ITOLift-off

Deposition of a-IGZOSpin coating of resistExposureDevelopmentEtchingRemoval of resist

InsulatorInsulator

PEN

SiON

ITO (G)

ITO(S) ITO(D)a-IGZO

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Applying Printing ProcessApplying Printing Process

GateGateDeposition of ITOSpin coating of resistExposureDevelopmentEtchingRemoval of resist

ChannelChannelDeposition of SiON

Source & DrainSource & Drain

Spin coating of resistExposureDevelopment Deposition of ITOLift-off

Deposition of a-IGZOSpin coating of resistExposureDevelopmentEtchingRemoval of resist

InsulatorInsulator

Screen printing of Ag pasteDrying

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-5 0 5 10 15 2010-13

10-12

10-11

1x10-10

1x10-9

1x10-8

1x10-7

1x10-6

1x10-5

on/off ratio : 2.4E7

VDS

= 8V

Dra

in C

urre

nt, I

DS (

A)

Gate Voltage, VGS

(V)

Screen printed Ag

Drain

Glass / ITO [G] / SiON(150nm) / a-IGZO / printedprinted--Ag [S & D]Ag [S & D]Bottom Gate Structure

W = 10,000mm L = 41mm

mFE = 2 ~ 3 cm2/Vs

Source

Transfer Characteristic

Characteristics of an Amorphous Oxide TFTCharacteristics of an Amorphous Oxide TFT –– Printed S&D Printed S&D --

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Future ScopeFuture Scope

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Product of Vacuum Web Coating in TOPPANProduct of Vacuum Web Coating in TOPPAN

Gas Barrier

Evaporation, Sputter, PECVD

Anti-Reflection Film

Gas Barrier Films for- Food Package- Pharmaceutical Products- OLED (under development)

Transparent Conductive Oxide(ITO etc.)

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Future ScopeFuture Scope

Vacuum Web CoatingPrinting Process

Low Cost TFT on Plastic Films

Flexible electronics can cover a vast range of applicationsFlexible electronics can cover a vast range of applicationsDisplays, Photovoltaics, RFID etc.Displays, Photovoltaics, RFID etc.

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·· Demonstration of flexible, active-matrix, electronic paper display driven with amorphous oxide array

·· Flexible and transparent backplane using a-InGaZnO as an active channel is realized by standard sputtering technique at room temperature onto PEN film.

·· Successfully applying printed source and drain electrodes to oxide TFT.

· Average field effect mobility of 5 cm2/Vs, · On-off ratio with more than 6 orders of magnitude

SummarySummary

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AcknowledgmentAcknowledgment

We would like to express our deepest appreciation to Professor Hosono of Tokyo Institute of Technology for providing valuable suggestions.

We are thankful to E Ink Corp. for graciously supplying us with electrophoretic imaging film.

We would like to thank to Mr. N. Sekine, Mr. T. Okubo, Mr. O. Kina, Mr. R. Matsubara and Mr. K. Hatta of Toppan Printing. Co., Ltd. for offering beneficial advices.