Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
  • H10K59/10—OLED displays
  • H10K59/17—Passive-matrix OLED displays
  • H10K59/173—Passive-matrix OLED displays comprising banks or shadow masks
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/80—Constructional details
  • H10K50/805—Electrodes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
  • H10K59/80—Constructional details
  • H10K59/805—Electrodes

Definitions

• the invention relates to a method for producing structured electrodes, in particular of organic electroluminescent components with a structured electrode, such as displays having structured metal electrodes.
• Thin layers in particular with a thickness in the range from 1 nm to 10 ⁇ m, find a variety of technological applications, for example in semiconductor production, microelectronics, sensors and display technology. Structuring of the layers is almost always required for the production of components, the required structure sizes ranging from the sub- ⁇ range to the entire substrate area and the required variety of shapes being almost unlimited.
• lithographic processes available in many variants are generally used for the structuring. All processes have in common that the layers to be structured come into contact with more or less aggressive chemicals, such as photoresists, solvents, developer liquids and etching gases. In some applications, however, such contacts lead to the destruction or at least damage to the layers to be structured. This applies, for example, to organic light-emitting diodes.
• OLEDs Organic light emitting diodes
• ie electroluminescent diodes are used primarily in displays (see, for example, US Pat. No. 4,356,429 and US Pat. No. 5,247,190).
• the construction and manufacture of OLED displays are typically carried out as follows.
• a substrate for example glass, is coated over the entire surface with a transparent electrode (bottom electrode, anode), for example made of indium tin oxide (ITO).
• ITO indium tin oxide
• Both the transparent bottom electrode and the top electrode (cathode) must be structured in order to produce pixel matrix displays.
• Both electrodes are usually structured in the form of parallel conductor tracks, the conductor tracks of the bottom electrode and top electrode being perpendicular to one another.
• the bottom electrode is structured using a photolithographic process, including wet-chemical etching processes, the details of which are known to the person skilled in the art.
• the resolution that can be achieved with these methods is essentially limited by the photolithographic steps and the nature of the bottom electrode. According to the prior art, both pixel sizes and non-emitting spaces between the pixels of a few micrometers in size can be realized.
• the length of the strip-shaped conductor tracks of the bottom electrode can be up to many centimeters. Depending on the used
• Lithography mask can also generate emitting areas up to a size of several square centimeters.
• the sequence of the individual emitting areas can be regular (pixel matrix display) or variable (symbol representations).
• organic layers are applied to the substrate with the structured transparent bottom electrode.
• These organic layers can consist of polymers, oligomers, low molecular weight compounds or mixtures thereof.
• Processes from the liquid phase are usually used to apply polymers, for example polyaniline, poly (p-phenylene-vinylene) and poly (2-methoxy-5- (2'-ethyl) -hexyloxy-p-phenylene-vinylene) (Application of a solution by means of spin coating or knife coating), while vapor deposition is preferred for low-molecular and oligomeric compounds (vapor deposition or “physical vapor Deposition ", PVD).
• low molecular weight, preferably positive charge transport compounds are: N, N '-Bis (3-methylphenyl) -N, N' bis (phenyl) benzidine (-TPD), 4, 4 ', 4''-Tris- (N-3-methylphenyl-N-phenylamino) triphenylamine (m-MTDATA) and 4, 4', 4 '' -Tris- (carbazol-9-yl) triphenylamine ( TCTA)
• the emitter used is, for example, hydroxyquinoline aluminum III salt (Alq), which can be doped with suitable chromophores (quinacridone derivatives, aromatic hydrocarbons, etc.) as well as layers influencing the long-term properties, for example made of copper phthalocyanine.
• the total thickness of the layer sequence can be between 10 nm and 10 ⁇ m, typically it is in the range between 50 and 200 nm.
• the top electrode usually consists of a metal, which is generally applied by vapor deposition (thermal evaporation, sputtering or electron beam evaporation). Preference is given to using base metals and thus, in particular, reactive to water and oxygen, such as lithium, magnesium, aluminum and calcium, and alloys of these metals with one another or with other metals.
• the structuring of the metal electrode required for producing a pixel matrix arrangement is generally achieved by the metal being applied through a shadow mask which has correspondingly shaped openings.
• An OLED display produced in this way can contain additional devices that influence the electro-optical properties, such as UV filters, polarization filters, anti-reflective coatings, devices known as “micro-cavities”, and color conversion and color correction filters. Furthermore, there is hermetic packaging (“Packaging”) available, through which the organic electroluminescent displays against environmental influences such as moisture and mechanical niche loads are protected. There may also be thin film transistors for driving the individual picture elements (“pixels”).
• Pixels thin film transistors for driving the individual picture elements
• a fine structuring of the metal electrode in the form of conductor tracks is required, i.e. Both the width of the conductor tracks and the gaps must be structurable while adhering to tight tolerances in the ⁇ m range.
• the width of a conductor track can be between 10 ⁇ m and several hundred micrometers, preferably between 100 and 300 ⁇ m.
• shadow masks i.e. thin sheets or disks with openings shaped according to the desired structure
• only layers can be structured which have been produced by CVD or PVD methods.
• the achievable resolution - due to the finite distance between the mask and the substrate - results in relatively poor values, and large areas cannot be produced due to bending of the shadow masks.
• the object of the invention is a generally applicable
• Boundary is maintained, and wherein the first layer has a higher solubility rate in a liquid developer than the second layer and the second layer can be structured and crosslinked - that the second layer is structured and the structure is transferred to the first layer and then the second layer is crosslinked or the second layer is first structured and crosslinked and then the structure is transferred to the first layer, the second layer having a greater structure width than the first layer and the difference in the structure width of the two layers being retained during crosslinking, and that an electrode is deposited on the second layer.
• the invention creates a novel method for the maskless production of structured electrodes, in particular for organic electroluminescent components. Above all, this method enables the production of structured metal electrodes, in particular for organic ones electroluminescent displays. This method can be used to produce structures which are suitable for large-area displays, and it is also possible to structure metal electrodes on electroluminescent polymers. The method according to the invention is also particularly suitable for those applications in which the lithographic method, which is in itself suitable for production, in accordance with German patent application Akt.Z. 197 45 610.3 ("Production of organic electroluminescent components") is not sufficient.
• the two layers are preferably applied to a bottom electrode located on the substrate.
• at least one organic functional layer is then first applied to the second layer, and then a top electrode is deposited on the organic functional layer.
• the top electrode which preferably has a small work function for electrons and thus functions as an electron-injecting electrode, consists in particular of metal or a metallic alloy.
• this electrode can also have a layer structure, a metal or ITO layer being arranged as a (transparent) electrode on a thin dielectric layer ( ⁇ 5 nm), which consists, for example, of lithium fluoride or aluminum oxide.
• the first layer applied to the bottom electrode which may be structured, ie the lower layer, is not damaged when the second layer (upper layer) is applied and that there is a defined boundary between the two layers preserved.
• the first and / or the second layer advantageously consists of an organic film-forming material, preferably of a photoresist.
• Photoresists which are also referred to as photoresists, are light-sensitive, film-forming materials, the solubility behavior of which changes as a result of exposure or exposure to radiation; a distinction is made between positive and negative photoresists. If in the present case both the upper and the lower layer consist of a photoresist and both photoresists are sensitive in the same wavelength range, then the photoresist of the lower layer must not be a negative working system.
• the method according to the invention includes, as an essential feature, a photolithographic process in which at least two layers are applied to the transparent bottom electrode, optionally after its structuring, of which the first layer consists of a lacquer or a positive photoresist and the second layer consists of a positive or negative photoresist; in the case of a first layer of photoresist, this is flood-exposed before the second layer is applied.
• the layers are then structured in such a way that the organic functional layers and the (metallic) top electrode can be applied or deposited over their area.
• the structuring of the layers or the top electrode is transverse to the structuring of the bottom electrode.
• the organic functional layer (s) can generally be applied to the second layer either by a thermal evaporation process or from a solution, for example by spin coating or knife coating and subsequent drying.
• the first of the two layers must be overcoatable. This means that the two layers can be applied one above the other without so-called intermixing, ie the lacquers used are soluble in different solvents, so that the (photo) lacquer of the first layer through the solvent for the photoresist second layer is not attacked. This ensures that the defined structure of the first layer is retained when the second layer is applied and that a defined boundary exists between the two layers.
• the photolithographic process step also requires that the first layer have a higher development rate than the second layer. This means that in the treatment of the lacquer layers with a developer solution, which is required for the structuring after the exposure, the first layer dissolves faster than the second layer. It is advantageous if the two layers are treated with the same developer, which is in particular an aqueous alkaline developer, i.e. can be developed.
• Suitable inorganic materials are, for example, silicon dioxide, silicon nitride and aluminum oxide.
• the lower layer can, for example, also consist of an alkaline developable non-photosensitive polyimide.
• the lower layer is advantageously photosensitive and preferably consists of a positive photoresist based on polyglutarimide or polybenzoxazole.
• the upper layer is advantageously also a photoresist.
• This layer preferably consists of a positive photoresist (positive resist) based on novolak / diazoquinone or of a negative photoresist (negative resist) based on novolak / crosslinker / photo acid.
• Poly (methyl methacrylate) (PMMA) can also be used as a positive resist, and crosslinkable poly- (silphenylene siloxanes) can also be used as a negative resist, for example.
• the upper layer indirectly. Then serves as layer material for example such as amorphous carbon (aC) or amorphous hydrogen-containing carbon (aC: H).
• aC amorphous carbon
• aC: H amorphous hydrogen-containing carbon
• TSI Top Surface Imaging
• a process control of the type mentioned above results in a structure shown in the figure, the second layer having a greater structure width than the first layer (“overhang structure”).
• the second layer which preferably consists of a film-forming organic material, is crosslinked, which increases mechanical stability and thermal resistance.
• the overhang structure is not affected by the crosslinking.
• the overhang of the second layer is stabilized, so that larger areas, in particular long edges, can be realized and the layer can be produced by means of solvent processes.
• the stable overhang then effects the structuring of the subsequently applied layers, because at the edge of the overhang both CVD or PVD processes and layers applied from the liquid phase tear off and thus separate into different zones, i.e. be structured.
• These are in particular organic functional layers, i.e. electroluminescent layers, and electrodes.
• the difference in the structural width (“overhang”) is advantageously between 0.1 and 50 ⁇ m, in particular between 1 and 10 ⁇ m.
• the thickness of the lower layer is preferably 0.1 to 30 ⁇ m, in particular 0.5 to 10 ⁇ m, and that of the upper layer 0.1 to 30 ⁇ m, in particular 0.5 to 5 ⁇ m.
• the figure shows - not to scale - a schematic cross section through an organic light-emitting diode produced by the method according to the invention.
• a transparent structured bottom electrode 2 on a substrate 1.
• the subsequent layers are a lower photoresist layer 3, an upper photoresist layer 4, which is cross-linked, and an organic functional layer 5.
• the structured top electrode 6 (metal electrode) is then located on the organic functional layer 5.
• the display is manufactured according to the following process steps: 1. A glass plate coated with indium tin oxide (ITO) over the entire surface is structured with the aid of a photolithographic process with subsequent wet chemical etching in such a way that parallel conductor tracks with a width of approx. 200 ⁇ m and a There is a gap of approx. 50 ⁇ m. The conductor tracks are each about 2 cm long and may contain additives for contacting at their outer end. The photoresist used in the structuring is completely removed. 2. The glass plate is heated for about 1 h at a temperature of 250 ° C, then a commercial photoresist is on the
• magnesium is applied to the active surface of the display by thermal evaporation in a layer thickness of 100 nm (deposition rate:
• a 1% solution of an electroluminescent polymer based on fluorene in xylene is spun onto a glass plate with a layer structure produced according to Example 1 (4000 rpm, 30 s). The mixture is then dried at 85 ° C. for 60 s. Without using a mask, calcium is then applied to the active surface of the display by thermal evaporation in a layer thickness of 100 nm (deposition rate: 1 nm / s, pressure: 10 ⁇ 5 mbar). Without interrupting the vacuum, silver is then - also by thermal evaporation - applied to the active display area in a layer thickness of 100 nm (deposition rate: 1 nm / s, pressure: 10 ⁇ 5 mbar).

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• Electroluminescent Light Sources (AREA)

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• 1999
  • 1999-04-13 TW TW088105841A patent/TW411726B/zh not_active IP Right Cessation
  • 1999-06-07 WO PCT/DE1999/001655 patent/WO1999066568A1/de not_active Ceased
  • 1999-06-07 CN CNB998074934A patent/CN100385704C/zh not_active Expired - Lifetime
  • 1999-06-07 DE DE59915061T patent/DE59915061D1/de not_active Expired - Lifetime
  • 1999-06-07 KR KR1020007014416A patent/KR100631249B1/ko not_active Expired - Fee Related
  • 1999-06-07 CA CA002335317A patent/CA2335317A1/en not_active Abandoned
  • 1999-06-07 JP JP2000555305A patent/JP2002518813A/ja active Pending
  • 1999-06-07 EP EP99936420A patent/EP1095413B1/de not_active Expired - Lifetime
• 2000
  • 2000-12-18 US US09/737,656 patent/US20010017516A1/en not_active Abandoned
• 2004
  • 2004-05-21 US US10/850,799 patent/US6885150B2/en not_active Expired - Lifetime

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