Organic electronics: Photolithography or printingsemieurope.omnibooksonline.com/2016/semicon_europa/2016FLEX Eur… · Organic Electronics: Photolithography or Printing ... Merck

Giles LloydFlex Europe Conference, 25th October 2016

ORGANIC ELECTRONICS: PHOTOLITHOGRAPHY OR PRINTING

Organic Electronics: Photoligthography or Printing? Lithography

Enabling flexible TFT sheet-fed

production using traditional mask-based microfabrication techniques

Layers patterned with light for high

resolution displays

Enabling flexible electronics from the roll

Printing

Ultimate approach to cost effective

manufacture of large & small area electronics

Organic TFT made

in-house with Merck OTFT and photo-resist materials

Organic TFT Stack

Source: FlexEnable.com

Fastest integration route to

market enabling display makers to ‘fill’ existing LCD lines with minimal investment

Layers patterned additively - no

subtractive etching, photolithography, or vacuum processing steps required

3

Dielectric 2

Dielectric 1

OSC

Substrate

Source Drain

Gate

Planarisation

Passivation

Organic Electronics: Printing or Photolith? ¦ Flex Conference, 25th October 2016

4 Organic Electronics: Printing or Photolith? ¦ Flex Conference, 25th October 2016

OE: Photolithography or Printing?

Organic Semiconductors

-30 -20 -10 0 101E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

VD -5V, -60V

Linear

Saturated

Gate voltage [V]

Dra

in c

urr

ent [A

]

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Mobili

ty [cm

2/V

s]

Merck Performance Materials polymer semiconductors deliver performance combined withsolution processability

-30 -20 -10 0 101E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4D

rain

curr

ent [A

]

Gate voltage [V]

VD -5V, -60V

Linear

Saturated0.0

0.5

1.0

1.5

2.0

Mobili

ty [cm

2/V

s]

SP400 SP500

lisicon® SP400

Mobility 0.5 – 1 cm2/Vs

lisicon® SP500

Mobility > 2 cm2/Vs

PHOTOLITHOGRAPHY

5



The Whole Package

Dielectric 2

Dielectric 1

OSC

Substrate

Source Drain

Gate

Planarisation

All the organic actives and passives plus support materials

Passivation/Interlayer

SubstrateGlass, PEN, PET etc.

lisicon® P-series PlanarisationStable surface for uniform semiconductor coating.

ElectrodesGold, Silver

lisicon® SP-series Polymer SemiconductorsPerformance better than amorphous silicon

lisicon® D-series Low-k dielectricsClean, low-k interface and good solvent resistance

lisicon® AP-series cross-linked dielectricsRobust surface for gate-metal processing

lisicon® P-series passivation/interlayerLow-k for low capacitive coupling

Merck Performance Materials FPD PhotoresistStandard positive tone resist, optimised strippers



Collaboration Makes Us Stronger

Hsinchu, Taiwan

PhotoresistMaterials

<600 PPI <600~750PPI >750PPI

High Resolution FPD Photoresist

Conventional PR2 µm CD

Performance Materials High Contrast PR1.5 µm CD

Performance Materials Chemically Amplified PR1 µm CD

Chilworth, UK

OTFT Chemistry, Formulation & Printing

High Performance OTFT

In development

OTFT for Printing OTFT for Photolithography

Fully Printed OTFTstack

Photopatterned OTFT stack

+ =



D-series dielectric and Patterning

Dielectric 1

FPDPR

FPDPR PR

300 nm layer of dielectric 1

>1 um layer of FPD photoresist

50 mJ/cm2 UV

(aligner or stepper)

TMAH develop

O2 RIE etch Strip with DMSO

(or alternative)

g/h-line UV

Developed for photolithography applications

• Dielectric constant of 2.0

• Low solvent permeability* protects the OSC interface

• Compatible with full photolithography process:

*Solvent permeability

Permeability reduced by a factor of 4 compared to previous generation dielectric(measured using PGMEA)

Patterned OSC/Dielectric 1



AP-series Dielectric

500 nm layer of dielectric 2

~200 mJ/cm2 UV

(aligner or stepper)

i-line or g/h-line

Develop with PGMEA

~1 J/cm2 “hard” cure

Deposit gate

(evaporation or sputtering)

Dielectric 2

g/h-line UV

UV Cross-linkable 2nd layer dielectric

• Dielectric constant of 2.5

• Resistant to metal sputtering and etching (including film edges)

• Formulated for use in i-line exposure tools (g/h-line under development) 10 um via-holes patterned in dielectric 2



Patterned OTFT Device Data

Un-patterned TFT (as-spun)Drain currentGate Current

Un-patterned TFT (as-spun)Drain currentGate Current

SP400

-60 -40 -20 0 20

10-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

Curr

ent

[A]

Gate Voltage [V]

SP500Un-patterned TFTs exhibit a significant parasitic current

• Attributed to bulk conductivity through the semiconductor layer

-60 -40 -20 0 20

10-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

Curr

ent

[A]

Gate Voltage [V]

Patterning gives significant benefits to OTFT performance

• Significant reduction in parasitic current

• Order-of-magnitude reduction in off-current

The full stack and process is transferrable to SP500

• The same benefits are seen

• Identical materials and process

• On/off ratio > 107 can be achieved

Reducedleakage

Reducedleakage

PRINTING

11


Performance, stability and stack robustness:

Chemistry of the active components

Solvents providing homogeneous structures

Good interfacial properties (electrical + mechanical)

Safety / environmental friendliness:

Engineered solubility profile of the solid components

Non-toxic and non-flammable solvents can be used

Formulations compliant with industrial-scale manufacturing lines

Processability

Simple and stable processing, R2R compatible (no surface treatments such as Vac. Plasma or Corona)

Focus on high resolution: limited and controlable ink spreading with negligible edge effects


Printing - Major goals


lisicon®SP400 – OTFT stack development

lisicon® SP400- Printable (e.g. Gravure and Flexo)- Performance close to amorphous silicon- Stable and uniform

lisicon® M001- Provides low contact resistance- Printable (Ink-jet, spray, syringe

dispensing…)

lisicon® D320- Low-k- Printable, (e.g. Gravure and Screen)- Optimised for high performance and stability

lisicon® AP048- Printable (e.g. Gravure)- UV curable – high chemical resistance- Good wetting properties


Dielectric 2

Dielectric 1

OSC

Substrate

Source Drain

Gate

Note:- Source/drain contacts are Ag and printed by Flexo. Ag gate contact screen printed.


Formulation development concept – Gravure printingOE: Photolithography or Printing?

Layer thickness requirements

Feature quality and resolution

Form

ula

tion

develo

pm

ent

Pri

nting p

rocess

develo

pm

ent

ViscositySolid

content

Cell sizeEngraving

type

Optimisation of printing parameters

D320

SP400

AP048

Profiles of Gravure printed SP400 and dielectrics takenthroughinterferometric confocal microscope


OE: Printing or Photolithography?

SP400 printing process

Gravure printing using mechanically engraved cells

Uniform thickness of the printed features in 30 - 150nm range

SP400 surface roughness <5nm – similar to planarised PEN

Example of a Gravure printed feature of SP400(30nm thick and 100µm wide) on Q65 HA takenthrough interferometric confocal microscope

300µm

30nm thick

150nm thick

Gravure printed SP400 on a flexo printed Source/Drain electrode structuretaken through optical microscope

SP400 features in a range of 30 – 150nm thicknessGravure printed using different rasters



SP400 Printing at VTT

Printed at…



Dielectrics: D320 and AP048 - printing

120

-200

100

µm 750 800

100µm

400nm

0 500µm

0 µm 100 400

nm

Gravure printed D320 line with engraving cell image (middle) and profile taken by using mechanical profilometer (Dektak)

Gravure printing, mechanically engraved cells (GRT GmbH & Co. KG)

Uniform thickness profiles, variations <7% of the total thickness

Thicknesses achievable for D320: 100 – 520nm

Gravure printed AP048and profile taken through confocal microscopy with engraving cell image



The final stack – electrical performance

Good transfer characteristic achieved for all the channel lengths from 30 to 130µm

Leakage currents <10pA

No hysteresis was observed

-40 -30 -20 -10 0 1010

-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

Dra

in C

urr

ent

[A]

Gate Voltage [V]

VD = -1 V

VD = -3 V

VD = -30 V

Typical transfer characteristic from 55 x 1000µm (L x W) printed OTFT

100µm

Optical microscope image of 55 x 1000µm (L x W) printed S/Delectrode structureused for the OTFT stackgiving transfer curves as shown on the right

Full printed OTFT devices



ATLASS EU-Funded Project

Both OSC & passives patterned through additive manufacturing

Merck co-ordinates

EU-funded project exploring new applications for (printed) active-matrix backplanes

Merck interlayer (S2S)

Merck dielectric (R2R)

Fully-printedOTFT Stack

*Advanced high-resolution printing of organic Transistors for Large-Area Smart Surfaces. 14 EU partners.

*

Pressure sensor for crash testing

Temperature sensor (NFC)

Intelligent label (NFC)

Sensing skin for robotics

Non-industrial pilot lines


Different display medias (electrophoretic, LCD, OLED) have been demonstrated using OTFT backplanes


OTFTs in real Flexible Display applications

OTFTs for EPD OTFTs for LCD OTFTs for OLED

Flexible electrophoretic display OTFT integrated with liquid crystal frontplane

OTFT-driven OLED display prototype

Source:


Digital transport signage Digital fashion

Flexible Display – Example use cases!



The final remarks

Organic Electronics: Photolithography or Printing...?

Material and formulation development demonstrated for both traditional photolithography and printing processes

Future production processes can use either or a combination of both!

In the near term, photolithography processes expected to dominate and allow utilization of existing infrastructure whilst the technology matures

In the long term, printing opens up new possibilities for production at ultra high volume, for example, continuous processes such as Roll to Roll!

Either! Both!or

R&D Director

PM-A, New Platforms

Southampton, UK

[email protected]

DR MARK JAMESSenior Manager, Marketing and Project Management

PM-A, New Platforms.

Southampton, UK

[email protected]

DR GILES LLOYD

Products are warranted to meet the specifications set forth on their label/packaging and/or certificate of analysis at thetime of shipment or for the expressly stated duration. Merck provides information and advice on application technologiesand relevant regulations based upon its current knowledge and opinion. MERCK MAKES NO REPRESENTATION ORWARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING MERCHANTABILITY OR FITNESS FOR A PARTICULAR USEREGARDING OUR PRODUCTS, THEIR APPLICATION OR ANY INFORMATION PROVIDED IN CONNECTION THEREWITH.Merck shall not in any event be liable for incidental, consequential, indirect, exemplary or special damages of any kindresulting from any use or failure of the products. Customer is responsible for and must independently determine thesuitability of Merck´s products for its products, intended use and processes. The foregoing information and suggestionsare also provided without warranty of non-infringement as to intellectual property rights of third parties and shall not beconstrued as any inducement to infringe the rights of third parties. Customer shall be responsible for obtaining anyapplicable third party intellectual property licenses. All sales are subject to Merck’s complete Terms and Conditions ofSale. Prices are subject to change without notice. Merck reserves the right to discontinue products without prior notice.

Merck, the vibrant M, lisicon® are trademarks of Merck KGaA, Darmstadt, Germany. All other trademarks pertain to theirproprietors.

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Organic electronics: Photolithography or printingsemieurope.omnibooksonline.com/2016/semicon_europa/2016FLEX Eur… · Organic Electronics: Photolithography or Printing ... Merck