Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/04—Coating on selected surface areas, e.g. using masks
  • C23C14/048—Coating on selected surface areas, e.g. using masks using irradiation by energy or particles
• • 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
  • H10K59/30—Devices specially adapted for multicolour light emission
  • H10K59/38—Devices specially adapted for multicolour light emission comprising colour filters or colour changing media [CCM]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
  • H10K71/10—Deposition of organic active material
  • H10K71/18—Deposition of organic active material using non-liquid printing techniques, e.g. thermal transfer printing from a donor sheet

Definitions

• the present invention relates to a fabrication method for high resolution full color organic light emitting diode (“OLED”) displays.
• the present invention relates to a method of selectively depositing emitting elements or portions thereof on the subpixels of desired color on the OLED display.
• photolithographic patterning that includes wet processing may be used. This introduces potential hydrolysis and oxidation of organic OLED materials.
• the two former approaches are technologically more feasible because all pixels emit the same color, and CCM and/or color filters can be patterned independently and then aligned on top of OLED pixels.
• the display design that uses blue color monochrome pixelated display with CCM is preferable for the following reasons: a) it uses blue monochrome display thus eliminating problem of differential aging of phosphor components; b) blue light absorbed by the CCM media and re-emitted with high quantum efficiency of luminescence can provide higher display brightness than white display with color filters; (c) thin films of highly absorbing CCM can be evaporated directly on top of the transparent display encapsulation layer thus maximizing light collection and eliminating cross-talk between neighboring pixels.
• CCM layer(s) is patterned using lithography, which is a multi-step process and often requires wet processing. This increases product cost and introduces potential damage to the OLED display.
• the present innovation is directed to a new effective method for fabrication of high- resolution full color passive or active matrix self-emitting OLED displays with independently driven red, green and blue emitting elements (subpixels) placed next to each other.
• This fabrication method can be applied for OLEDs with layers made of organic materials including low-molecular weight materials, oligomers and polymers, or combination of those prepared by vacuum deposition, spin-coating, self-assembly, Langmuir-Blodgett or any other technique or combination of those.
• This fabrication method can also be applied for OLEDs with layers made of organic and inorganic materials.
• the main idea of the suggested method is to selectively transfer certain areas of prefabricated organic layer for OLED, or of combination of those layers, or of whole OLED structure including one or both electrodes, or of whole OLED structure including one or both electrodes and passivation layer, from the source substrate to the receiving wafer or substrate with prefabricated electronic circuitry, active- or passive matrix structure, and, possible, bottom electrode and one or few organic layers in such a way that subpixels corresponding to one color only are covered at a time. Transfer of named layer(s) should occur due to laser ablation from the source substrate or by instant heating of the latter in vacuum.
• the present invention is directed to a method of fabricating a full color organic light emitting diode display.
• the method includes the step of providing a wafer including at least one of prefabricated circuitry, a bottom electrode and at least one organic layer.
• the method further includes the step of providing a first substrate having a first color specific organic light emitting layer formed thereon.
• the method also includes the step of selectively applying electromagnetic radiation to the first substrate to transfer portions of the color specific light emitting layer onto to the wafer to form at least one first color specific subpixel.
• the first substrate includes a release layer located between the substrate and the first color specific light emitting layer.
• the source of electromagnetic radiation may be a UV light source.
• the method may further include the step of removing the substrate having a first color specific organic light emitting layer formed thereon, after formation of the at least one first color specific subpixel.
• the method may further include the steps of providing a substrate having a second color specific organic light emitting layer formed thereon, and selectively applying the electromagnetic radiation to the second substrate to transfer portions of the second color specific light emitting layer onto to the wafer to form at least one second color specific subpixel.
• the second substrate may further include a release layer located between the second substrate and the second color specific light emitting layer.
• the release layer is designed to protect the at least one organic layer damage by the UV light used for ablation.
• the first color specific light emitting layer may be different from the second light emitting layer.
• the method may further include the steps of removing the second substrate after formation of the at least one second color specific subpixel, providing a third substrate having a third color specific organic light emitting layer formed thereon, and selectively applying the electromagnetic radiation to the third substrate to transfer portions of the third color specific light emitting layer onto to the wafer to form at least one third color specific subpixel.
• the third substrate may further include a release layer located between the third substrate and the third color specific light emitting layer. Additionally, the first color specific light emitting layer and the second light emitting layer may be different from the third light emitting layer.
• the present invention is also directed to a new effective method for fabrication of high-resolution full color passive- or active matrix self-emitting OLED displays with independently driven red, green and blue emitting elements (subpixels) placed next to each other.
• This fabrication method may be applied for blue color OLEDs with layers made of organic materials including low-molecular weight materials, oligomers and polymers, or combination of those prepared by vacuum deposition, spin-coating, self-assembly, Langmuir- Blodgett or any other technique or combination of those.
• This fabrication method can also be applied for blue OLEDs with layers made of organic and inorganic materials.
• This fabrication method can also be applied for any type of blue light emitting displays using CCM to produce full color.
• the main idea of the suggested method is to selectively transfer certain areas of pre-fabricated CCM layer, or of a color filter, or combination of CCM layer and color filter, from the source substrate to the receiving wafer with pre-fabricated electronic circuitry and active- or passive OLED monochrome display in such a way that pixels corresponding to one color only are covered at a time. Transfer of the named layer(s) may occur due to laser ablation from the source substrate or by instant heating of the latter in vacuum.
• Source substrate is made of thin material non-transparent to UV and visible light (i.e., metal, ceramics) and instead of ablation the proper area(s) of this substrate is (are) instantly heated by pulsed focused source of electromagnetic radiation such as IR light or electron or ion beam.
• Low substrate thickness prevents spreading of heat across the substrate and allows selective heating of organic areas on this substrate.
• This technique is applicable to vacuum deposition of CCM layer only and requires vacuum between source substrate and wafer. All of the above is for up-emitting active matrix display. All of the above is for down-emitting passive and active matrix displays when CCM and/or color filters and monochrome pixelated displayed are placed on the opposite sides of the transparent support.
• the above-described method eliminates the air gap between display and CCM/color filters because they can be placed directly on top of the display. That improves color quality because cross-talk between pixels of color bleeding decreases dramatically. That also improves display brightness and power efficiency because all light emitted from the top electrode is now collected by the CCM/color filter.
• the present invention also makes the process of CCM and/or color filter deposition much easier and cheaper because only optical alignment of display wafer and source substrate with CCM/filter layer is needed, and ablation is a single step process.
• the present invention also eliminates using a shadow mask and multi-step lithography, both processes not practical for miniature OLED displays with pixel size of few microns. Elimination of wet and/or oxygen plasma processing used for lithography decreases contamination and improves display lifetime significantly.
• Minimum size of pixel is limited by the diffraction of light only.
• the diffraction limit is less or about 0.3-0.5 ⁇ m.
• the present invention is also directed to a method of fabricating a full color organic light emitting diode display.
• the method may include the steps of providing a wafer having at least one organic light emitting diode formed thereon, providing a first source substrate having at least a first color changing layer formed thereon, and positioning said first source substrate adj acent said wafer, and selectively transferring a portion of said at least a first color changing layer from said first source substrate to said at least one organic light emitting diode.
• the step of selectively transferring the at least a first color changing layer includes the step of ablating the first source substrate to selectively transfer a portion of the at least a first color changing layer to the at least one organic light emitting diode.
• the method may further include the steps of removing the first source substrate after transferring the at least a first color changing layer from the first source substrate to the at least one organic light emitting diode, providing a second source substrate having at least a second color changing layer formed thereon, positioning the second source substrate adjacent the wafer, and selectively transferring a portion of the at least a second color changing layer from the second source substrate to the at least one organic light emitting diode.
• the step of selectively transferring the at least a second color changing layer includes the step of ablating the second source substrate to selectively transfer a portion of the at least a second color changing layer to the at least one organic light emitting diode.
• the method may further include the steps of removing the second source substrate after transferring the at least a second color changing layer from the second source substrate to the at least one organic light emitting diode, providing a third source substrate having at least a third color changing layer formed thereon, positioning the third source substrate adj acent the wafer, and selectively transferring a portion of the at least a third color changing layer from the third source substrate to the at least one organic light emitting diode.
• the step of selectively transferring the at least a third color changing layer includes the step of ablating the third source substrate to selectively transfer a portion of the at least a third color changing layer to the at least one organic light emitting diode.
• Fig. 1 illustrates the alignment of the wafer or substrate and the source substrate prior to the ablation process as part of formation of the high resolution full color OLED display according to a first embodiment of the present invention
• Fig. 2 illustrates the ablation process according to the fabrication method of the first embodiment of the present invention
• Fig. 3 illustrates the transfer of at least the organic layer according to the fabrication method of the first embodiment of the present invention
• Fig. 4 illustrates the alignment of the wafer or substrate and the source substrate in accordance with the ablation of a first color filter or CCM layer according to a second embodiment of the present invention
• Fig. 5 illustrates the transfer of the first color filter or CCM layer according to the fabrication method according to the second embodiment of the present invention
• Fig. 6 illustrates the alignment of the wafer or substrate and the source substrate in accordance with the ablation of a second color filter or CCM layer according to a second embodiment of the present invention
• Fig. 7 illustrates the transfer of the second color filter or CCM layer according to the fabrication method according to the second embodiment of the present invention
• Fig. 8 illustrates the alignment of the wafer or substrate and the source substrate in accordance with the ablation of a third color filter or CCM layer according to a second embodiment of the present invention.
• Fig. 9 illustrates the transfer of the third color filter or CCM layer according to the fabrication method according to the second embodiment of the present invention.
• Fig. 9 illustrates the transfer of the third color filter or CCM layer according to the fabrication method according to the second embodiment of the present invention.
• Detailed Description of Preferred Embodiments A method of fabricating a full color OLED display having high resolution will now be described in connection with Figs. 1-3.
• the individual subpixels of the OLED display have the same layer composition and structure.
• the blue, green and red OLED subpixels differ only by the chemical composition of the emitting layer.
• a bottom or first electrode, at least one organic layer and transport layer are deposited on a wafer or substrate 10.
• the first electrode, at least one organic layer and transport layer are collectively referenced as reference numeral 11 in Figs. 1-3.
• the formation of a blue subpixel, for example, will now be described.
• a source substrate 20 is predeposited with a doped emitter layer 22.
• a release layer 21 is also predeposited between the source 20 and doped emitter layer 22.
• the doped emitter layer 22 has a sufficient thickness of several hundred Angstrom.
• the source substrate 20 and the wafer or substrate 10 are separated by spacers 30.
• the source substrate 20 and the wafer or substrate 10 are separated by a distance of less than 1 ⁇ m.
• the substrate 20 and wafer or substrate 10 are located in inert gas atmosphere.
• Laser light 40 is used for the ablation of the doped emitter layer 22 to transfer the layer 22 to the subpixel 1 as shown in Fig. 2.
• the laser light 40 is aligned on the substrate
• the release layer 21 facilitates the ablation process.
• the release layer 21 is preferably formed from a thin layer of an appropriate material which is highly absorbing of the wavelength of light used during the ablation.
• the release layer 21 may be formed from a polyimide that is capable of absorbing UV light.
• the present invention is not limited to the use of polyimide; rather other materials with suitable wavelength absorbing properties are considered to be within the scope of the present invention.
• the release layer also protects organic OLED's layers from photo decomposition.
• the release layer 21 strongly absorbs the UV light and ablates. It is preferred that the source substrate 20 be exposed to a pulsed laser light. This permits the transfer of doped emitter layer 22, as shown in Fig. 2, while preventing disintegration of the emitter layer 22.
• the layer 22 has been transferred to the blue subpixel 1, as shown in Fig. 3, the substrate 20 is removed and replaced with a new source substrate having an emitter layer for formation of green subpixels.
• the laser light 40 is realigned such that areas of the substrate facing the green subpixels will be exposed.
• the ablation process is then repeated. The same procedure is repeated for the formation of red subpixels. Once the formation of the blue, green and red subpixels is complete, the remaining organic layer or layers and the top or second electrode are deposited on the subpixel. This is performed in a separate chamber.
• more than one organic layer of the OLED may be transferred during the ablation process.
• the whole stack of OLED's organic layers may be transferred by the ablation process.
• the whole stack of organic layers and the second electrode may be transferred by the ablation process, whereby only the bottom or first electrode is pre-deposited on the wafer or substrate.
• the transferring of the entire OLED including electrodes by the ablation process is contemplated by the present inventors and considered to be within the scope of the present invention. It is contemplated by the inventors of the present invention that an antireflection layer may be pre-deposited on the source substrate between the second electrode and the release layer and between the release layer and the OLED.
• the antireflection layer may be transferred by the ablation process. It is contemplated that an encapsulating material, including for example a getter material, may be pre-deposited on the source substrate between the second electrode and the release layer and the OLED, wherein the encapsulating material is transferred during the ablation process to encapsulate the display.
• an encapsulating material including for example a getter material, may be pre-deposited on the source substrate between the second electrode and the release layer and the OLED, wherein the encapsulating material is transferred during the ablation process to encapsulate the display.
• the encapsulating material may be used in conjunction with the antireflection layer, described above. Furthermore, it is contemplated that the material used to form the release layer may be used to encapsulate the OLED device.
• the layers may be transferred by instantly heating through a pulsed focused source of electromagnetic radiation.
• the source of electromagnetic radiation may be IR light, an electron beam or an ion beam.
• the source substrate should be formed from a thin material that is non-transparent to UV and visible light.
• the substrate may be formed from a metal or a ceramic.
• the thin substrate material prevents the spreading of heat across the source substrate, which allows for the selective heating of organic areas on the substrate. It is preferred that this process be used in connection with the vacuum deposition of the emitter layer only.
• a full color OLED display 50 using color changing media is produced using laser ablation.
• CCM color changing media
• the present method will be described, by way of example, in connection with the fabrication of a passive matrix monochrome display 50.
• the display 50 has independently addressable blue OLED pixels.
• the present invention is not limited to the fabrication of a display 50 consisting of upwardly emitting independently addressable blue pixels; rather, both upwardly and downwardly emitting OLED devices are considered to be well within the scope of the present invention.
• blue OLED displays including, but not limited to polymers.
• organic/inorganic blue LED display organic/inorganic blue LED displays
• inorganic blue LED displays are considered to be well within the scope of the present invention.
• full color up- emitting active matrix display and both downwardly emitting passive and active matrix displays are considered to be well within the scope of the present invention.
• a pixelated upwardly emitting active matrix display 50 is independently formed.
• a single display or a number of displays may be prefabricated on a wafer or substrate 51.
• the display 50 is preferably formed on silicon substrate or wafer. It, however, is contemplated that other suitable substrate materials are considered to be well within the scope of the present invention.
• the substrate 51 preferably incorporates driving electronics and a buffer electrode. At least one organic stack 52 is formed on the substrate for each pixel.
• the top layer 53 of the display 50 includes a transparent or semi-transparent top electrode.
• the top electrode 53 is preferably formed from a thin metal including but not limited to Mg:Ag, indium tin oxide (ITO), Mg:Ag with ITO on top of it, IZO, and Ca with ZnSe on top of it.
• the top electrode 53 is not limited to these materials; rather, it is contemplated that other suitable materials for forming the top electrode are considered to be well within the scope of the present invention.
• a semi-transparent encapsulation layer 54 may be provided on top of the top electrode 53.
• the wafer or substrate 51 includes optical alignment marks, not shown. The optical alignment marks are placed outside the display area. The marks are provided for alignment with a semi-transparent substrate 60, 70 or 80, discussed below.
• a source substrate 60 is used in connection with the fabrication of the full color OLED display 50.
• the source substrate 60 is preferably formed from a semi-transparent material (e.g., glass).
• a blue filter layer 61 (for correction of spectral coordinates for blue color emitted by the OLED display) with thickness of less than a pixel size (2-3 microns) is pre-deposited on the source substrate 60.
• the source substrate 60 includes alignment marks, not shown.
• the source substrate 60 and the wafer 51 which are separated by a spacer of less than 1 ⁇ m, are placed in an inert atmosphere.
• the alignment marks on the source substrate 60 and the wafer 51 are aligned. Laser light used for ablation of organic layers is aligned in such a way that only areas facing designated blue display pixels or rows/columns of designated blue display pixels will be exposed.
• a thin release layer 62 of an appropriate material (such as polyimide), which is highly absorbing in the wavelength of interest (UV) is deposited on the source substrate 60 prior to deposition of the filter layer 61.
• This release layer 62 will strongly absorb the UV light and ablate, thereby releasing the ablated area including the blue filter layer 61 from the source substrate 60.
• An adhesive layer 64 may be provided on the filter layer 61 prior to the ablation process to enhance adhesion of the filter layer 61 to the top electrode 53.
• a laser pulse hits the source substrate 60, which transfers the color filter 61 or CCM and adhesive layers 63 to the display 50. These layers are placed on top of the corresponding display subpixels, as shown in Figs, 4-9.
• the color filter layer 61, CCM layers 71 and 81 and adhesive layer leave the source substrate 60, 70, and 80 only the areas that have a release layer if the pulse energy of the laser is chosen correctly, as shown in Figs. 5, 7 and 9.
• the blue filter layer 61 is transferred and secured to the top electrode/encapsulation layer.
• the release layer 62 prevents the disintegration of the organic color filter layer.
• the release layer 61, 71 and 81 is pre- patterned such that the it corresponds to the display pattern.
• the blue color filter layer 61 and the CCM layers 71 and 81, described below, are not patterned; rather, these layers deposited by either vacuum deposition, or spin-coating or spray coating, or any other technique allowing deposition of uniform layer having a thickness of less than a few microns.
• the source substrate 60 is replaced with the new source substrate 70 having a blue-to-red CCM layer 71.
• the new source substrate 70 also includes a release layer 72 and an adhesive layer 73, as described above. Laser light used for ablation of organic layers is realigned in such a way that only areas facing designated red pixels or rows/columns of designated red pixels will be exposed and the ablation process described above is repeated.
• the source substrate 70 is replaced with the new source substrate 80 having a blue-to-green CCM layer 81.
• the new source substrate 80 also includes a release layer 82 and an adhesive layer 83, as described above.
• Laser light used for ablation of organic layers is realigned in such a way that only areas facing designated green pixels or rows/columns of designated green pixels will be exposed and the ablation process, described above, is repeated to transfer the layer 81, as shown in Fig. 9.
• the blue-to-green and blue-to-red source substrates 70 and 80 differ only by CCM and possibly by color filters. Both source substrates 70 and 80 include alignment marks.
• At least one encapsulation layer(s) is deposited the assembly in a separate chamber to seal the display.
• an anti-reflection layer may be pre-deposited on the source substrate between CCM layer and/or color filter layer and release layer.
• the anti-reflection layer may also include a getter material.
• an encapsulating material preferably containing a getter material, may be pre-deposited on the source substrate between CCM and the release layer for the final source substrate to encapsulate the display.
• the material forming the release layer may also for an encapsulating layer on the display 50.
• the source substrate may be made of thin material (i.e., metal , ceramics) that is non-transparent to UV and visible light.
• a pulsed focused source of electromagnetic radiation e.g., IR light, electron beam or ion beam.
• a low substrate thickness prevents spreading of heat across the substrate and allows selective heating of organic areas on this substrate.
• This technique is applicable to vacuum deposition of CCM layer and only requires vacuum between source substrate and wafer.
• the CCM and/or color filters and monochrome pixelated display are placed on the opposite side of the transparent substrate.

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• 1999
  • 1999-09-03 EP EP19990946723 patent/EP1116260A1/de not_active Withdrawn
  • 1999-09-03 WO PCT/US1999/020107 patent/WO2000014777A1/en not_active Application Discontinuation

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