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US-20260130047-A1 - LIGHT-EMITTING DISPLAY DEVICE, METHOD FOR MANUFACTURING SUCH A DEVICE AND LIGHT-EMITTING DISPLAY SYSTEM

US20260130047A1US 20260130047 A1US20260130047 A1US 20260130047A1US-20260130047-A1

Abstract

A method for manufacturing a light-emitting display device from islands separated by a trench, the method including filling the trench with an insulating structural element; forming a protective strip only partly covering each of the islands and overlapping the structural element; partially etching the structural element so as to form a pillar under the protective strip such that the same has cantilevered parts; and depositing an organic layer resulting in two distinct and separate portions, a first portion continuously extending over each island and over the protective strip, and a second portion extending over the substrate.

Inventors

  • Clément BALLOT
  • Adrien Gasse
  • Gunther Haas

Assignees

  • Commissariat à l'énergie atomique et aux énergies alternatives
  • MICROOLED

Dates

Publication Date
20260507
Application Date
20251104
Priority Date
20241104

Claims (19)

  1. 1 . A method ( 300 ) for manufacturing a light-emitting display device ( 200 ) from a precursor ( 100 ), said precursor ( 100 ) comprising a plurality of islands ( 101 ) disposed on a substrate ( 102 ), each island ( 101 ) comprising a support layer ( 104 ) extending over the substrate ( 102 ); and a conductive layer ( 103 ) extending over the support layer ( 104 ), the islands being separated two by two by a trench ( 106 ), the method ( 300 ) comprising: filling each trench ( 106 ) separating the islands ( 101 ) with a structural element ( 107 ) electrically insulating the islands ( 101 ), for each trench ( 106 ), filling being performed until said structural element ( 107 ) reaches the top of the islands ( 101 ) separated by said trench ( 106 ); forming at least one protective strip ( 108 ), each protective strip ( 108 ) connecting two islands ( 101 ) between them by overlapping the trench ( 102 ) separating said two islands ( 101 ) and by covering the structural element ( 107 ) extending in the trench ( 106 ), each protective strip ( 108 ) only partly covering each of the two islands ( 101 ) that it connects; partially etching the structural element ( 107 ) selectively with respect to each protective strip ( 108 ) and with respect to the conductive layers ( 103 ) of the islands ( 101 ), partially etching comprising at least one isotropic etching phase, partially etching being performed so as to retain only a portion ( 109 ) of the structural element ( 107 ) disposed under each protective strip ( 108 ) and said portion ( 109 ) forming a pillar for each protective strip ( 108 ), partially etching being further performed so that at least one part ( 110 a , 110 b ) of each protective strip ( 108 ) extends in a cantilevered fashion beyond the pillar ( 109 ) supporting it; and anisotropically depositing an organic layer ( 201 ) at an angle substantially perpendicular to the substrate ( 102 ), resulting in two portions ( 201 - 1 , 201 - 2 ) distinct and separate from the organic layer ( 201 ), including a first portion ( 201 - 1 ) continuously extending over each island ( 101 ) and over each protective strip ( 108 ), and a second portion ( 201 - 2 ) extending over the substrate ( 102 ), a deposition thickness of the organic layer ( 201 ) being selected such that the second portion ( 203 ) of the organic layer ( 201 ) does not reach said at least one cantilevered part ( 110 a , 110 b ) of each protective strip ( 108 ).
  2. 2 . The method ( 300 ) according to claim 1 , wherein partially etching the structural element ( 107 ) is performed such that the lateral gap (D 110 ) of said at least one cantilevered part ( 110 a , 110 b ) of each protective strip ( 108 ) relative to the pillar ( 109 ) supporting it is strictly greater than 100 nm.
  3. 3 . The method ( 300 ) according to one of claims 1 or 2 , wherein for each trench ( 106 ), filling is performed until the structural element ( 107 ) goes beyond the conductive layers ( 103 ) of the two islands ( 101 ) separated by said trench ( 106 ) by a height of between 10 nm and 100 nm.
  4. 4 . The method ( 300 ) according to claim 3 , wherein each island ( 101 ) comprises, prior to filling each trench ( 106 ), a sacrificial layer ( 105 ) extending over the conductive layer ( 103 ), filling each trench ( 106 ) with the structural element ( 107 ) being performed such that the structural element ( 107 ) reaches the top of the sacrificial layers ( 105 ) extending over the islands ( 101 ).
  5. 5 . The method ( 300 ) according to claim 4 , further comprising, after filling each trench ( 106 ) and before forming each protective strip ( 108 ), etching the sacrificial layer ( 105 ) of each island ( 101 ) selectively relative to the structural element ( 107 ), etching being performed with stopping at said conductive layer ( 103 ) of said island ( 101 ).
  6. 6 . The method ( 300 ) according to one of claims 4 or 5 , wherein, for each trench ( 106 ), filling with the structural element ( 107 ) comprises: depositing a layer of electrically insulating material so as to completely fill said trench ( 106 ); polishing the layer of insulating material with stopping at the sacrificial layer ( 105 ) of each island ( 101 ).
  7. 7 . The method ( 300 ) according to one of claims 4 or 5 , wherein, for each trench ( 106 ), filling with the structural element ( 107 ) comprises the following steps of: conformally depositing a dielectric layer in said trench ( 106 ); depositing a layer of filling material onto the dielectric layer so as to completely fill said trench ( 106 ); polishing the dielectric layer and the filling layer with stopping at the sacrificial layer ( 105 ) of each island ( 101 ).
  8. 8 . The method ( 300 ) according to claim 7 , wherein the filling material is amorphous silicon or polycrystalline silicon.
  9. 9 . The method ( 300 ) according to one of claims 1 to 8 , comprising, prior to forming each protective strip ( 108 ), creeping or swelling the structural element ( 107 ) so that it goes over a portion of the conductive layer of each island ( 101 ), forming at least one continuous, ridge-less free surface extending from the conductive layer ( 103 ) of one of the islands ( 101 ) to the conductive layer of another island ( 101 ), each free surface having a slope, measured relative to the substrate ( 102 ), of between −45 degrees and 45 degrees and preferably between −20 degrees and +20 degrees.
  10. 10 . The method ( 300 ) according to one of claims 1 to 9 , wherein each protective strip ( 108 ) is electrically insulating.
  11. 11 . The method ( 300 ) according to one of claims 1 to 10 , wherein partially etching the structural element ( 107 ) comprises at least one anisotropic etching phase and at least one isotropic etching phase, for example alternately, each anisotropic etching phase being performed with a directivity substantially perpendicular to the substrate ( 102 ).
  12. 12 . The method ( 300 ) according to one of claims 1 to 11 , comprising, after depositing the organic layer ( 201 ), anisotropically depositing an additional conductive layer ( 204 ), resulting in two portions ( 204 - 1 , 204 - 2 ) distinct and separate from the additional conductive layer ( 204 ), including a first portion ( 204 - 1 ) of the additional conductive layer ( 204 ) continuously extending over the first portion ( 201 - 1 ) of the organic material layer ( 201 ), and a second portion ( 204 - 2 ) of the additional conductive layer ( 204 ) extending over the second portion ( 2021 - 2 ) of the organic layer ( 201 ), a deposition thickness of the additional conductive layer ( 204 ) being selected such that the second portion ( 204 - 2 ) of the additional conductive layer ( 204 ) does not reach said at least one cantilevered part ( 110 a , 110 b ) of each protective strip ( 108 ).
  13. 13 . The method ( 300 ) according to one of claims 1 to 12 , wherein partially etching the structural element ( 107 ) is further performed so as to partially etch the support layer ( 104 ) of each island ( 101 ) such that, for each island ( 101 ), at least one part ( 114 ) of the conductive layer ( 103 ) of said island ( 101 ) extends in a cantilevered fashion beyond the support layer ( 104 ) of said island ( 101 ).
  14. 14 . A light-emitting display device ( 200 ) comprising a plurality of islands ( 101 ) disposed on a substrate ( 102 ), each island comprising a support layer ( 104 ) extending over the substrate ( 102 ) and a conductive layer ( 103 ) extending over the support layer ( 104 ), the device comprising: at least one trench ( 106 ) separating the islands ( 101 ) two by two; at least one protective strip ( 108 ), each protective strip ( 108 ) connecting two islands ( 101 ) to each other by overlapping the trench ( 102 ) separating said two islands ( 101 ), each protective strip ( 108 ) only partly covering each of the two islands ( 101 ); at least one pillar ( 109 ) at least partly filling a trench and electrically insulating the islands ( 101 ) separated by said trench ( 106 ), each pillar ( 109 ) reaching or going beyond the top of the two islands ( 101 ) separated by said trench ( 106 ), each pillar being disposed under a protective strip ( 108 ) to support said protective strip ( 108 ) such that at least one part ( 110 a , 110 b ) of said protective strip ( 108 ) extends in a cantilevered fashion beyond said pillar ( 109 ); and an organic layer ( 201 ) having two portions ( 201 - 1 , 201 - 2 ) distinct and separate from each other, including a first portion ( 201 - 1 ) continuously extending over each island ( 101 ) and over each protective strip ( 108 ), and a second portion ( 201 - 2 ) extending over the substrate ( 102 ) without reaching said at least one cantilevered part ( 110 a , 110 b ) of each protective strip ( 108 ).
  15. 15 . The display device ( 200 ) according to claim 14 , wherein the lateral gap (D 110 ) of said at least one cantilevered part ( 110 a , 110 b ) of each protective strip ( 108 ) relative to the pillar ( 109 ) supporting it is strictly greater than 100 nm.
  16. 16 . The display device ( 200 ) according to one of claims 14 or 15 , wherein said at least one pillar ( 109 ) is made from an electrically insulating material.
  17. 17 . The display device ( 200 ) according to one of claims 14 to 16 , wherein said at least one pillar ( 109 ) comprises a dielectric layer, for electrically insulating the islands ( 101 ) separated by said at least one pillar ( 109 ); and a filling material, serving as a support for the protective strip ( 108 ), the dielectric layer of said at least one pillar separating the filling material of said at least one pillar from each island ( 101 ).
  18. 18 . The display device ( 200 ) according to any of claims 14 to 16 , wherein said at least one pillar ( 109 ) has a continuous, ridge-less surface over which the protective strip ( 108 ) extends, said continuous, ridge-less surface extending from the conductive layer ( 103 ) of one of the islands ( 101 ) to the conductive layer of another island ( 101 ), each continuous, ridge-less surface having a slope, measured relative to the substrate ( 102 ), between −45 degrees and 45 degrees and preferably between −20 degrees and +20 degrees.
  19. 19 . A light-emitting display system, comprising: a device ( 200 ) according to one of claims 14 to 18 ; and an active addressing matrix comprising a plurality of transistors, each transistor of the plurality of transistors being connected to the conductive layer ( 103 ) of one of the islands ( 101 ) of said device ( 200 ).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to French Patent Application No. 2412040, filed Nov. 4, 2024, the entire content of which is incorporated herein by reference in its entirety. FIELD The technical field of the invention is that of optoelectronic devices, and more particularly that of matrix display devices with organic light-emitting layers. The present invention relates to a method for manufacturing an OLED (Organic Light-Emitting Diode) type light-emitting display device, as well as a method for manufacturing such a device. The present invention finds beneficial application in the manufacture of display screens for electronic devices, and in particular for the manufacture of high-resolution colour display screens such as AMOLED (Active Matrix Organic Light-Emitting Diodes) display screens. The term “high resolution” designates pixels with a size smaller than 15 μm. BACKGROUND In the field of matrix display devices with organic light-emitting layers, OLED type matrix microdisplays having pixels arranged with a pitch of less than 20 μm, typically between 4 μm and 12 μm are known. When this type of matrix display is in colour, each pixel is subdivided into sub-pixels of different colours (typically three, having red, green and blue colours) which work together to make the pixel emit the desired colour. The surface of the sub-pixels can be rectangular, square, or other shapes (for example octagonal), and their size may depend on the colour. The typical size of sub-pixels can range from 1 μm to 20 μm. Each sub-pixel is generally formed by several superimposed layers, including a lower electrode (the anode) deposited onto a common substrate, several organic layers (at least one of which is emissive) forming an OLED stack on each lower electrode, and an upper electrode (the cathode). Documents FR3079909A1 and US2023/0041252A1 describe structures for forming OLED pixels (or OLED sub-pixels) of such a small size with improved industrial reliability. These structures have the common benefit of allowing smooth discretisation of the OLED stack and cathode to form pixels (or sub-pixels). The term “smooth discretisation” designates a structuring method that preserves performance of the OLED stack. In particular, solutions provided consist in performing discretisation of the OLED stack in a way other than through masking and removal steps, which generally require environments (humidity, temperatures above 90° C., solvents, ultraviolet light, etc.) that are harmful to organic materials. Document FR3079909 A1 thus describes a first OLED display device in which the lower electrodes of each sub-pixel are separated from each other by an insulating wall rising vertically from the substrate. Each wall acts as a separator between two neighbouring sub-pixels. The same document FR3079909 describes a second device in which the insulating walls are replaced with trenches into which an insulating layer is deposited. The insulating walls and trenches are formed before the OLED stack is deposited by thermal evaporation and play the same role. As the evaporation deposition technique is predominantly directional, the OLED stack is in an embodiment deposited onto the horizontal walls of the device, and not onto the side walls of the insulating walls or trenches. The OLED stack is thus broken up (or discretised) at the insulating walls or trenches. However, in practice, directivity of the deposition of the OLED stack is never total. Organic particles can therefore also be deposited onto the side walls of the insulating walls or trenches. And these particles are undesirable because they degrade insulation (electrical, optical) between the sub-pixels. Neighbouring sub-pixels can then interact with each other, for example through capacitive coupling or parasitic currents. These phenomena, known as crosstalk, lead to a degradation in performance of the display device. These phenomena are exacerbated when the sub-pixels are so-called “tandem” organic light-emitting diodes, i.e. when the sub-pixels comprise several OLED stacks stacked and connected in series by virtue of interconnection layers. Document US2023/0041252A1 offers a solution to this problem by describing sub-pixel separators that are disposed on a substrate and have a mushroom-shaped structure (or “hang-over” according to the terminology used in this document). More precisely, this mushroom-shaped structure comprises a lower part with sloping sides, forming the stem of the mushroom. It also comprises an upper part, wider than the lower part, which masks a region of the substrate. This upper part forms the cap of the mushroom. The sub-pixels are formed once the mushroom structures are in place. The OLED stack is then deposited onto these structures and broken up at the upper parts. Breaking up the OLED stack is performed with satisfactory reliability since the organic material cannot be deposited onto the region of the substrate masked by the u