SiOx Barrier Films for Flexible Display SiOx Barrier Films ...€¦ · SiOx Barrier Films for...
Transcript of SiOx Barrier Films for Flexible Display SiOx Barrier Films ...€¦ · SiOx Barrier Films for...
AIMCAL 2005 Fall Technical Conference
1
SiOx Barrier Films for Flexible Display SiOx Barrier Films for Flexible Display
T. Komori, H. Kobayashi, and H. UyamaTechnical Research Institute, TOPPAN PRINTING CO., LTD.
AIMCAL 2005 Fall Technical Conference
2
OutlineOutline
■ Introduction ■ Introduction
■ SiOx Deposition by PECVD ■ SiOx Deposition by PECVD
■ Application to Flexible Displays■ Application to Flexible Displays
□ Color Filter□ Color Filter
□ OLED□ OLED
□ Ca test□ Ca test
AIMCAL 2005 Fall Technical Conference
3
High insulation
High gas barrier
Low refractive index
Food packages
Electrical devices
Optical devices
PropertiesProperties
High transparency
Applications Applications
SiOx Barrier CoatingSiOx Barrier Coating
AIMCAL 2005 Fall Technical Conference
4
SiOx film
Thermal evaporation
LPCVD
High speed deposition for packaging barrier.
The Methods to Obtain SiOx FilmThe Methods to Obtain SiOx Film
PVD
CVD
Optical coating
Sputtering
Ion plating
Insulation layer
Optical coating
High barrier film
Plasma enhanced CVD
AIMCAL 2005 Fall Technical Conference
5
10- 3 g/m2/day
10- 2 g/m2/day
10- 1 g/m2/day
100 g/m2/day
101 g/m2/day
Polymer substrate
Packaging barrier
LCD Color filter
OLEDUnder 10- 5 g/m2/day
Electronic PaperElectronic Paper
Water Vapor Transmission Rate (WVTR)Water Vapor Transmission Rate (WVTR)
MOCON detection limit
AIMCAL 2005 Fall Technical Conference
6
High density
Low stress
Composition Reduce impurities and micro defects
Avoid crack and delaminating
Defect less Smooth surface
More dense layer
No defects
To Obtain SiOx Barrier FilmTo Obtain SiOx Barrier Film
Surface morphology of substrate, etc
Barrier propertyDifficulty
AIMCAL 2005 Fall Technical Conference
7
Color Filter
O2: 0.5〔 cm3/m2/day〕
H2O: 0.1〔 g/m2/day〕
> 85%
Ra < 5 nm
OLED
O2: 0.001〔 cm3/m2/day〕
H2O: 10-5〔 g/m2/day〕
> 200゜ C For Color Filter process
Must maintain physical and optical properties after photolithographic processing
Barrier property
Transparency
Chemical proof
Surface morphology
Heat resistant ofthe substrate
> 100゜ C Depending on type of OLED
Ra < 10 nm without any spiky defects
> 85%
Requirements for Display FilmsRequirements for Display Films
AIMCAL 2005 Fall Technical Conference
8
Plastic Substrates for DisplayPlastic Substrates for Display
Typical properties of glass and plastic films
PET = Polyethylene terephthalatePC = PolycarbonatePES = Polyether sulfoneCOP = cyclic-olefin polymer
Glass PET PC PES COPWVTR (g/m2/day @ 100µm) - 4.6 4 124 0.4
Tg (°C) 660 69 155 223 163Water absorption (%) - 0.7 0.3 1.4 0.01Transmittance (%) 93 87 90 89 91
Refractive index (@550nm) 1.54 1.66 1.58 1.65 1.53Haze (%) <0.5 0.6 0.8 <0.1 <0.1
Relative density 2.52 1.40 1.99 1.37 1.01Tensile strength (Mpa) - 190 85 80 75Tensile elongation (%) - 180 230 23 5
Coefficient ofthermal expansion (/°C)
5x10-6 2x10-5 7x10-5 6x10-5 6x10-5
AIMCAL 2005 Fall Technical Conference
9
Roll-to-roll PECVD
SiOx
HMDSO+O2
Method:
Barrier:
Source material:
■ SiOx deposition process using PECVD
SiOx Deposition by PECVD SiOx Deposition by PECVD
CH3
CH3
H3C Si
CH3
CH3
CH3SiO
HMDSO (Hexamethyldisiloxane)
Winding Room
Deposition Room
HMDSO
RF Source
Electrode
O2
MFCMFC
HMDSO Inlet
Pumping
PumpingSubstrate
Main Roll
Winding roll
rewinding roll
Winding Room
Deposition Room
HMDSO
RF Source
Electrode
O2
MFCMFC
HMDSO Inlet
Pumping
PumpingSubstrate
Main Roll
Winding roll
rewinding roll
PET (175μm)
PES (200μm)
COP (100μm)
Substrate:
AIMCAL 2005 Fall Technical Conference
10
Low transparency
Low density
Increase of dangling bonds
Using HMDSO PrecursorUsing HMDSO PrecursorProblem of PECVD ProcessProblem of PECVD Process
Must be deposited at low temperature <50゜ C
Precursor including methyl-group
Carbon incorporation causes deterioration of SiOx film properties
AIMCAL 2005 Fall Technical Conference
11
Transmittance of SiOx Deposited by PECVDTransmittance of SiOx Deposited by PECVD
Light transmittance of the SiOx deposited film is as same as that of the substrate.
50
60
70
80
90
100
350 450 550 650 750
wavelength (nm)
T%
PES PES/SiOx(100nm)
AIMCAL 2005 Fall Technical Conference
12
400100016002200280034004000
Wavenumber (cm-1
)
T [a
.u.]
Si-CH3Si-O-Si
Si-CH3CH3
(a)
(b)
(c)
FT-IR Spectra of SiOx FilmsFT-IR Spectra of SiOx Films
0.1
0.2
0.4
HMDSO/O2 flow ratio
Rf power 0.5kW
The absorptions from carbon incorporation were not indicated.
AIMCAL 2005 Fall Technical Conference
13
1.450
1.455
1.460
1.465
1.470
1.475
1.480
1.485
1.490
1.495
0 0.1 0.2 0.3 0.4 0.5
HMDSO/O2 flow ratio
Refractive index
Refractive Index of SiOx FilmsRefractive Index of SiOx Films
Stoichiometric SiO2
0.5kW
1.0kW
SiOx film with O-rich or low density or
Incorporation of Si-OH or Si-C
SiOx film with Si-rich
λ =628.8
AIMCAL 2005 Fall Technical Conference
14
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
0 0.1 0.2 0.3 0.4 0.5
HMDSO/O2 flow ratio
Density [g/cm3]
Stoichiometric SiO2
Density of SiOx FilmsDensity of SiOx Films
0.5kW
1.0kW
XRR = X-Ray Refractivity
32.2g/cm »
The density of thermally oxidated SiO2
AIMCAL 2005 Fall Technical Conference
15
MOCON PERMATRAN 3/33( 40℃ -90%Rh)
Detection limit ofMOCON
Barrier Properties of SiOx FilmsBarrier Properties of SiOx Films
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
1.0E+02
0 20 40 60 80 100 120
SiOx thickness (nm)
WVTR (g/m2/day)
PET PES COP
WVTR of the barrier film deposited only 60nm SiOx reached detection limit of MOCON.
AIMCAL 2005 Fall Technical Conference
16
1. UV ozone cleaning
2. Color resist coating
3. Drying under reduced pressure
4. UV exposure
5. Development
6. Cleaning, drying
7. Thermal curing (180゜ C-60min)
Color Filter process = Photolithographic processing
This process was repeated 3 times for color filter fabrication.
Fabrication of Color FilterFabrication of Color Filter
Chemical resistance(e.g. alkali, acid and solvent)
Heat resistance
AIMCAL 2005 Fall Technical Conference
17
Fabrication of Film color filter on Barrier Film( Substrate: PES)
< 0.01g/m2/dayBarrier film*
Detection limit ofMOCON
< 0.01g/m2/day
Barrier film* / color filter
Detection limit ofMOCON
Fabrication of Color Filter on Barrier FilmFabrication of Color Filter on Barrier Film
Degradation of WVTR was not observed before and after color filter process.
* Both side SiOx coating.
AIMCAL 2005 Fall Technical Conference
18
Glass substrate
Anode (ITO)
Hole transport Layer
Light emitting layer (Polymer type)
CaAg
Adhesive agent
Encapsulation film
Encapsulation Test Using Barrier FilmEncapsulation Test Using Barrier Film
OLED structure which uses a barrier film for encapsulation .
OLED test piece for estimation of WVTR
AIMCAL 2005 Fall Technical Conference
19
Estimation method of WVTR
60℃ 90%RH.
46 hours
Barrier filmWVTR=0.03g/m2/day
Encapsulation Test Using Barrier FilmEncapsulation Test Using Barrier Film
The ratio of dark spot (DS) is observed for 500 hours under 60゜ C 90%RH.environment
Dark spot
AIMCAL 2005 Fall Technical Conference
20
Observation of Dark SpotObservation of Dark Spot
Conditions: 60℃ 90%RH
Time [H] Initial 112 160 328 424 520
Reference
Sample A
Sample B
Barrier film delaminated fromthe OLED
(glass)
AIMCAL 2005 Fall Technical Conference
21
0.00
0.20
0.40
0.60
0.80
1.00
0 100 200 300 400 500 600 700
Time [H]
Area ratio of DS [%]
Conditions: 60℃ 90%RH
Encapsulation Test Using Barrier FilmsEncapsulation Test Using Barrier Films
Sample A maintains low area ratio of DS for 500h, comparable to that of glass encapsulation.
Sample B, DS growth was observed and the barrier film was delaminated.
Reference (glass)
Sample A
Sample B
AIMCAL 2005 Fall Technical Conference
22
Water though the barrier film reacts with Ca layer immediately.
Ca test piece
Ca Test for Estimation of WVTRCa Test for Estimation of WVTR
Ca corrosion area was measured by optical micro scope.
Ca 100nm
Barrier film
Glass
Adhesive agent
Ca corrosion
AIMCAL 2005 Fall Technical Conference
23
Appearance of After 196 Hours Test PieceAppearance of After 196 Hours Test Piece
a) 60nm SiOx b) Thicker SiOx
c) Both side SiOx
A certain thickness was required to obtain defect-free barrier film.
Conditions: 60℃ 90%RH
AIMCAL 2005 Fall Technical Conference
24
SummarySummary
■ A study of the SiOx coated film by plasma enhanced CVD for display has been presented.
■ Optimizing deposition conditions, WVTR became MOCON detection limit by minimal thickness. The SiOx film obtained on optimized condition approached density 2.2 g/cm3 and refractive index 1.465.
■ Degradation of barrier property was not seen before and after color filter process. These results represent that the SiOx film has resistance against chemicals.
■ From encapsulation test and Ca test, the SiOx barrier film was estimated suitable for OLED.
AIMCAL 2005 Fall Technical Conference
25
Flexible OLED Flexible OLED
The OLED display was fabricated on plastic substrate with SiOx barrier layer.
Uniform luminescence and good flexibility were obtained.
BACK TO LIST