Advanced Sheet-to-Sheet and Roll-to-Roll thin-film processing on ultra-thin flexible glass for flexible electronic devices

Transcription

1 Advanced Sheet-to-Sheet and Roll-to-Roll thin-film processing on ultra-thin flexible glass for flexible electronic devices M. Junghaehnel 1, J. Westphalen 1, F. Naumann 2, G. Lorenz 2, M. Fahland 1, S. Mogck 1 1) Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP 2) Fraunhofer Institute for Applied Microstructure of Materials and Systems IMWS page 1

2 Progress in ultra-thin glass product development d < 0.2 mm d ~ mm d > 1 mm Flexible Glass Glass manufacturer Products Coatings Lighting Equipment S2S, R2R Display Processing Sensors Handling Energy storage Cutting Automotive page 2

3 S2S technologies for PVD of ultra-thin flexible glass In-line S2S vacuum coater for inorganic thinfilms Substrate size for UTG max. 600 x 600 mm² ~ Gen 3.5 format PVD and PECVD processes Post annealing: Heating up to 400 C or Flash Lamp Annealing (FLA) Stand alone UTG handling or glass on carrier technology page 3

4 S2S technologies for PVD of ultra-thin flexible glass Example hot ITO 150 nm ITO 100 µm Corning Willow Glass Substrate size: 500 x 500 mm² Thermal annealing in 400 C after coating ITO properties: R sq. ~ 12 Ω T VIS ~ 87.3% ρ ~ Ω cm 2016 Fraunhofer FEP Source: M. Junghähnel et al.; 59th SVC 2016 page 4

5 Challenges in processing of flexible glass Additional issues must be taken into consideration: Selection of the substrate thickness 10 mm Pre-conditioning Process parameters Coating design Post processing ITO on 100 µm UTG ITO 1000 nm Beside functional properties Mechanical properties of the substrate-layer-compound FhG internal project ZUG4Flex ITO on 10 mm 50 µm UTG ITO 750 nm page 5

6 Characterizations of flexible glass substrates Types of flexible glass 100 µm thickness 3 different glass suppliers Substrate states: Substrates in initial state - uncoated ITO coated not annealed After post annealing Sputtering Process used target ITO 90/10 length 750 mm p process T power coating rate 0.3 Pa Pa RT 3 kw, DC-Mode nm m/min O 2 (Ar + O 2 ) 0, 5, 10 % post 350 C in vacuum/ 6-23 J/cm², 2 ms Strength testing sample size 10x10mm² number of samples for each glass 63 page 6

7 Mechanical Characterization of flexible glass Characterization of substrates initial state Analysis to define the initial state before PVD-coating Measurement of: Surface hardness and Young s modulus nano-indentation Surface topology - WLI Fracture strength of the sample surface both glass sides Indentation Stress measurement Strength testing page 7

8 Mechanical Characterization of flexible glass Surface Hardness and Young s modulus Comparable to literature data No significant differences of the Young s modulus between the front and back Small variation in the surface hardness between the samples (max ~5%) page 8

9 Mechanical Characterization of flexible glass Surface topology (substrate curvature) WLI measurement of the surface (reference for stress estimation): elliptic paraboloidal behavior hyperbolic paraboloidal behavior A significant deformation of all sample types can be measured Radius of curvature [m] sample size 1x1cm² Substrate A (blue) Substrate A (red) Substrate B (blue) Substrate B (red) Substrate C (blue) Substrate C (red) 12.1 page 9

10 Mechanical Characterization of flexible glass Surface Fracture Strength *) theoretical bending radius of the surface strength neglecting edge flaws µm glass thickness) Ball on Ring test: r* theor. ~ 0.9 mm Stress Calculation r* theor. ~ 1.6 mm The surface strength of all UTG-types is much higher than the edge strength Differences of the surface strength between the sample types of appr. 65% A theoretical max bending radius of mm of the surface can be assumed. page 10

11 Mechanical Characterization of flexible glass Influence of ITO layer deposition Curvature measurement (WLI) and stress after ITO deposition 2000 O 2 /Ar+O 2 concentration Surface at WP 0.3 Pa Flow O 2 = 0 sccm Compressive Stress [MPa] Surface at WP 0.3 Pa Flow O 2 = 4 sccm Pa 0.9 Pa page 11

12 Mechanical Characterization of flexible glass Influence of thermal annealing Hardness [GPa] Modulus [GPa] Using nano-indentation, a strong reduction of the ITO-hardness and the Youngs modulus is measured. The resulting parameter are in a comparable range to the initial substrate. page 12

13 Mechanical Characterization of flexible glass Influence of thermal annealing Substrate type A Estimated influence of the post-annealing to the fracture strength A further reduction (~55%) of the fracture strength. Characteristic Fracture Stress [MPa] Weibull Modulus *) theoretical bending radius of the surface strength neglecting edge flaws (@100 µm glass thickness) page 13

14 The road from S2S to R2R FOSA LabX 330 Glass R2R vacuum coater Special winding system for UTG handling Substrate width: 330 mm Substrate thickness: µm Coating temperature: 350 C Rollers touching substrate backside only Application examples ITO AR page 14 BMBF KONFEKT (FKZ 13N13818)

15 FOSA LabX 330 Glass machine scheme page 15 BMBF KONFEKT (FKZ 13N13818)

16 FOSA LabX 330 Glass Example AR coating 1st pass In-line monitoring) Both stations on Adjustment of the rate ratio to coat the first two layers in one run No monitoring film thickness to low NbO x (Nb 2 O 5 ) Si (SiO 2 ) page 16 BMBF KONFEKT (FKZ 13N13818)

17 FOSA LabX 330 Glass Example AR coating 2nd pass In-line monitoring) Nb 2 O 5 on ; SiO 2 off Same power than during the 1st pass Higher band speed Monitoring off NbO x (Nb 2 O 5 ) Si (SiO 2 ) page 17 BMBF KONFEKT (FKZ 13N13818)

18 FOSA LabX 330 Glass Example AR coating 3rd pass In-line monitoring) Both stations on Same rate ratio like 1st pass lower band speed Monitoring on NbO x (Nb 2 O 5 ) Si (SiO 2 ) page 18 BMBF KONFEKT (FKZ 13N13818)

19 FOSA LabX 330 Glass Example AR coating 100 µm Schott glass 100 Single side coated Transmission/Reflection [%] T R Wavelength [nm] page 19 BMBF KONFEKT (FKZ 13N13818)

20 FOSA LabX 330 Glass Example ITO page 20 BMBF KONFEKT (FKZ 13N13818)

21 FOSA LabX 330 Glass page 21 BMBF KONFEKT (FKZ 13N13818)

22 Process capabilities on flexible Fraunhofer FEP page 22

23 Summary Mechanical Characterization of flexible glass allowing a deeper understanding of the interaction of PVD processes to the mechanical properties, an identification of critical process parameters with respect to fragility of the glass substrate, the optimization of critical process parameters to enhance fracture strength properties, information of further handling conditions after PVD deposition The road from S2S to R2R Next step in flexible glass processing is successfully done Integration in production lines Reduction of fabrication risks focus applications page 23

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25 Thank you very much for your attention! Kindly acknowledgements: BMBF KONFEKT (FKZ 13N13818) Fraunhofer MEF-project ZUG4Flex Corning Inc. Schott AG NEG Co., Ltd VON ARDENNE GmbH # Booth 1004 page 25 CONTACT: Manuela.Junghaehnel@fep.fraunhofer.de Coordinator Flexible Glass FEP