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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.
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