ORGANIC ELECTRONICS: PHOTOLITHOGRAPHY OR PRINTING. Giles Lloyd Flex Europe Conference, 25th October 2016

Transcription

1 ORGANIC ELECTRONICS: PHOTOLITHOGRAPHY OR PRINTING Giles Lloyd Flex Europe Conference, 25th October 2016

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3 Organic Electronics: Photoligthography or Printing? Lithography Printing Enabling flexible TFT sheet-fed production using traditional mask-based microfabrication techniques Enabling flexible electronics from the roll Ultimate approach to cost effective manufacture of large & small area electronics Layers patterned additively - no subtractive etching, photolithography, or vacuum processing steps required Source Passivation Gate Dielectric 2 Dielectric 1 OSC Planarisation Substrate Drain Organic TFT Stack Fastest integration route to market enabling display makers to fill existing LCD lines with minimal investment Layers patterned with light for high resolution displays Organic TFT made in-house with Merck OTFT and photo-resist materials 3 Source: FlexEnable.com

4 Organic Semiconductors Merck Performance Materials polymer semiconductors deliver performance combined with solution processability Drain current [A] 1E-4 1E-5 1E-6 1E-7 1E-8 1E-9 1E-10 1E-11 V D -5V, -60V Linear Saturated SP400 1E Gate voltage [V] lisicon SP Mobility cm 2 /Vs Mobility [cm 2 /Vs] Drain current [A] 1E-4 1E-5 1E-6 1E-7 1E-8 1E-9 1E-10 1E-11 V D -5V, -60V Linear Saturated SP E Gate voltage [V] lisicon SP500 Mobility > 2 cm 2 /Vs Mobility [cm 2 /Vs] 4

5 5 PHOTOLITHOGRAPHY

6 The Whole Package lisicon P-series passivation/interlayer Low-k for low capacitive coupling All the organic actives and passives plus support materials lisicon AP-series cross-linked dielectrics Robust surface for gate-metal processing Merck Performance Materials FPD Photoresist Standard positive tone resist, optimised strippers Passivation/Interlayer Source Gate Dielectric 2 Dielectric 1 OSC Planarisation Substrate Drain lisicon D-series Low-k dielectrics Clean, low-k interface and good solvent resistance lisicon SP-series Polymer Semiconductors Performance better than amorphous silicon Electrodes Gold, Silver lisicon P-series Planarisation Stable surface for uniform semiconductor coating. Substrate Glass, PEN, PET etc. 6

7 Collaboration Makes Us Stronger High Performance OTFT OTFT for Printing OTFT for Photolithography Chilworth, UK OTFT Chemistry, Formulation & Printing Fully Printed OTFT stack High Resolution FPD Photoresist Photopatterned OTFT stack + = <600 PPI <600~750PPI >750PPI Hsinchu, Taiwan Photoresist Materials Conventional PR 2 µm CD Performance Materials High Contrast PR 1.5 µm CD Performance Materials Chemically Amplified PR 1 µm CD In development 7

8 D-series dielectric and Patterning Developed for photolithography applications Dielectric constant of 2.0 Low solvent permeability* protects the OSC interface Compatible with full photolithography process: g/h-line UV Patterned OSC/Dielectric 1 FPD PR FPD PR PR Dielectric nm layer of dielectric 1 >1 um layer of FPD photoresist 50 mj/cm 2 UV (aligner or stepper) O 2 RIE etch Strip with DMSO (or alternative) TMAH develop 8 *Solvent permeability Permeability reduced by a factor of 4 compared to previous generation dielectric (measured using PGMEA)

9 AP-series Dielectric UV Cross-linkable 2 nd 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 g/h-line UV Dielectric nm layer of dielectric 2 ~200 mj/cm2 UV (aligner or stepper) i-line or g/h-line Develop with PGMEA ~1 J/cm 2 hard cure Deposit gate (evaporation or sputtering) 9

10 Patterned OTFT Device Data SP400 Current [A] Un-patterned TFTs exhibit a significant parasitic current SP500 Attributed to bulk conductivity through the semiconductor layer Patterning gives significant benefits to OTFT performance Significant reduction in parasitic current Order-of-magnitude reduction in offcurrent The full stack and process is transferrable to SP500 The same benefits are seen Identical materials and process On/off ratio > 10 7 can be achieved Reduced leakage Gate Voltage [V] Current [A] Reduced leakage Un-patterned TFT (as-spun) Drain current Gate Current Un-patterned TFT (as-spun) Drain current Gate Current Gate Voltage [V]

11 11 PRINTING

12 Printing - Major goals 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 12

13 lisicon SP400 OTFT stack development Gate lisicon AP048 - Printable (e.g. Gravure) - UV curable high chemical resistance - Good wetting properties Dielectric 2 Dielectric 1 lisicon D320 - Low-k - Printable, (e.g. Gravure and Screen) - Optimised for high performance and stability Source OSC Substrate Drain lisicon SP400 - Printable (e.g. Gravure and Flexo) - Performance close to amorphous silicon - Stable and uniform Note:- Source/drain contacts are Ag and printed by Flexo. Ag gate contact screen printed. lisicon M001 - Provides low contact resistance - Printable (Ink-jet, spray, syringe dispensing ) 13

14 Printing process development Formulation development OE: Photolithography or Printing? Formulation development concept Gravure printing Feature quality and resolution Layer thickness requirements SP400 Viscosity Solid content Profiles of Gravure printed SP400 and dielectrics taken through interferometric confocal microscope Optimisation of printing parameters Engraving type Cell size D320 AP048 14

15 OE: Printing or Photolithography? SP400 printing process Gravure printing using mechanically engraved cells Uniform thickness of the printed features in nm range SP400 surface roughness <5nm similar to planarised PEN SP400 features in a range of nm thickness Gravure printed using different rasters 30nm thick Example of a Gravure printed feature of SP400 (30nm thick and 100µm wide) on Q65 HA taken through interferometric confocal microscope Gravure printed SP400 on a flexo printed Source/Drain electrode structure taken through optical microscope 300µm 150nm thick 15

16 SP400 Printing at VTT Printed at 16

17 Dielectrics: D320 and AP048 - printing Gravure printing, mechanically engraved cells (GRT GmbH & Co. KG) Uniform thickness profiles, variations <7% of the total thickness Thicknesses achievable for D320: nm Gravure printed D320 line with engraving cell image (middle) and profile taken by using mechanical profilometer (Dektak) 400 nm Gravure printed AP048 and profile taken through confocal microscopy with engraving cell image nm 500µm 0 100µm 0 µm µm

18 The final stack electrical performance 100µm Good transfer characteristic achieved for all the channel lengths from 30 to 130µm Leakage currents <10pA No hysteresis was observed Full printed OTFT devices Optical microscope image of 55 x 1000µm (L x W) printed S/D electrode structure used for the OTFT stack giving transfer curves as shown on the right Drain Current [A] Typical transfer characteristic from 55 x 1000µm (L x W) printed OTFT Gate Voltage [V] V D = -1 V V D = -3 V V D = -30 V 18

19 ATLASS EU-Funded Project Merck co-ordinates EU-funded project exploring new applications for (printed) active-matrix backplanes * Merck interlayer (S2S) Merck dielectric (R2R) Pressure sensor for crash testing Fully-printed OTFT Stack Both OSC & passives patterned through additive manufacturing Sensing skin for robotics Temperature sensor (NFC) Intelligent label (NFC) Non-industrial pilot lines *Advanced high-resolution printing of organic Transistors for Large-Area Smart Surfaces. 14 EU partners. 19

20 OTFTs in real Flexible Display applications Different display medias (electrophoretic, LCD, OLED) have been demonstrated using OTFT backplanes OTFTs for EPD OTFTs for LCD OTFTs for OLED Flexible electrophoretic display OTFT integrated with liquid crystal frontplane OTFT-driven OLED display prototype Source: 20

21 Flexible Display Example use cases! Digital transport signage Digital fashion 21

22 The final remarks Organic Electronics: Photolithography or Printing...? Either! or Both! 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! 22

23 DR GILES LLOYD Senior Manager, Marketing and Project Management PM-A, New Platforms. Southampton, UK DR MARK JAMES R&D Director PM-A, New Platforms Southampton, UK

24 Disclaimer Products are warranted to meet the specifications set forth on their label/packaging and/or certificate of analysis at the time of shipment or for the expressly stated duration. Merck provides information and advice on application technologies and relevant regulations based upon its current knowledge and opinion. MERCK MAKES NO REPRESENTATION OR WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE REGARDING 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 kind resulting from any use or failure of the products. Customer is responsible for and must independently determine the suitability of Merck s products for its products, intended use and processes. The foregoing information and suggestions are also provided without warranty of non-infringement as to intellectual property rights of third parties and shall not be construed as any inducement to infringe the rights of third parties. Customer shall be responsible for obtaining any applicable third party intellectual property licenses. All sales are subject to Merck s complete Terms and Conditions of Sale. 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 their proprietors. 24