Dispersion transfer method of micro light-emitting diodes

Abstract

The present invention provides a method for dispersive transfer of micro light-emitting diodes. The dispersive transfer method includes: providing a substrate, and fabricating micro light-emitting diodes arranged in an array with a predetermined interval on the substrate; fabricating a first absorption part arranged in an array with a target interval on the side of the substrate facing away from the micro light-emitting diodes; the first absorption part is arranged corresponding to the micro light-emitting diodes, the target interval is an integer multiple of the predetermined interval, and the integer multiple is greater than or equal to 2; adopting a laser ablation process, irradiating the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part, and transferring some of the micro light-emitting diodes to an intermediate substrate; moving the substrate, and irradiating the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part again, repeating until all the micro light-emitting diodes are transferred to the target position on the intermediate substrate; transferring the micro light-emitting diodes on the intermediate substrate to a target substrate.

Description

Technical Field

[0001] The present application relates to the field of displays, and in particular, to a method for dispersing and transferring micro light-emitting diodes. Background Art

[0002] Micro light-emitting diodes (Mini / Micro Light Emitting Diode, abbreviated as MLED) have become one of the hotspots of future display technologies due to their advantages such as fast response, high color gamut, high pixel density, and low energy consumption.

[0003] After the micro light-emitting diode chips are fabricated, they need to be transferred one by one to the predetermined positions on the display substrate. However, the size of a single micro light-emitting diode chip in the micro light-emitting diode array is much smaller than the pixel size on the display substrate. Therefore, during the transfer process of the micro light-emitting diode chips, the micro light-emitting diode chips need to be dispersed.

[0004] Currently, the indirect transfer and dispersion method is generally adopted. Part of the micro light-emitting diodes located on the carrier substrate are picked up by a transfer head and transferred and bonded to the receiving substrate, and this process is repeated in sequence until the dispersion transfer of the micro light-emitting diode chips is completed. This method has an excessive workload and low transfer and dispersion efficiency. Summary of the Invention

[0005] The present invention provides a method for dispersing and transferring micro light-emitting diodes to achieve the dispersion transfer of micro light-emitting diodes, reduce the workload of the dispersion transfer of micro light-emitting diodes, and lower the cost of the dispersion transfer of micro light-emitting diodes.

[0006] To solve the above problems, the technical solutions provided by the present invention are as follows:

[0007] The present invention provides a method for dispersing and transferring micro light-emitting diodes, and the dispersion transfer method includes:

[0008] Providing a substrate, and fabricating micro light-emitting diodes arranged in an array with a predetermined interval on the substrate;

[0009] Fabricating a first absorption part arranged in an array with a target interval on the side of the substrate facing away from the micro light-emitting diodes; the first absorption part is arranged corresponding to the micro light-emitting diodes, the target interval is an integer multiple of the predetermined interval, and the integer multiple is greater than or equal to 2;

[0010] Using a laser to irradiate the substrate and the micro light-emitting diodes from the side of the first absorption part, and transferring part of the micro light-emitting diodes to an intermediate substrate;

[0011] Move the substrate, and irradiate the substrate and the micro light-emitting diodes from the side of the first absorption part with a laser again, and repeat until all the micro light-emitting diodes are transferred to the target position on the intermediate substrate;

[0012] Transfer the micro light-emitting diodes on the intermediate substrate to the target substrate.

[0013] Optionally, in some embodiments of the present invention, the first absorption part covers the corresponding micro light-emitting diodes.

[0014] Optionally, in some embodiments of the present invention, the area of the first absorption part is greater than or equal to the area of the micro light-emitting diodes, and the diameter of the first absorption part is less than the predetermined interval.

[0015] Optionally, in some embodiments of the present invention, the thickness range of the first absorption part is 10 Å - 100 Å.

[0016] Optionally, in some embodiments of the present invention, the transmittance of the first absorption part to the laser is 50% - 80%.

[0017] Optionally, in some embodiments of the present invention, the material of the first absorption part is amorphous silicon.

[0018] Optionally, in some embodiments of the present invention, the step of using a laser to irradiate the substrate and the micro light-emitting diodes from the side of the first absorption part and transferring some of the micro light-emitting diodes to the intermediate substrate includes:

[0019] Use a laser to irradiate the substrate and the micro light-emitting diodes from the side of the first absorption part, and transfer the micro light-emitting diodes not corresponding to the first absorption part to the intermediate substrate.

[0020] Optionally, in some embodiments of the present invention, the step of moving the substrate, and irradiating the substrate and the micro light-emitting diodes from the side of the first absorption part with a laser again, and repeating until all the micro light-emitting diodes are transferred to the target position on the intermediate substrate includes:

[0021] Move the substrate, and irradiate the substrate and the micro light-emitting diodes from the side of the first absorption part with a laser again, and transfer the micro light-emitting diodes corresponding to the first absorption part to the intermediate substrate.

[0022] Optionally, in some embodiments of the present invention, while preparing the first absorption part on the side of the substrate facing away from the micro light-emitting diode array, the dispersion transfer method further includes:

[0023] A second absorption part with an array arrangement and having the target interval is prepared on the side of the substrate away from the micro light-emitting diode; the thickness of the second absorption part is twice the thickness of the first absorption part.

[0024] Optionally, in some embodiments of the present invention, there is the predetermined interval or the target interval between adjacent first absorption parts and second absorption parts.

[0025] The present invention provides a method for dispersive transfer of micro light-emitting diodes. By arranging a first absorption part corresponding to some of the micro light-emitting diodes on the side of the substrate away from the micro light-emitting diodes, the first absorption part absorbs and blocks part of the laser energy. When transferring the micro light-emitting diodes, the micro light-emitting diodes not corresponding to the first absorption part are transferred first, and the micro light-emitting diodes corresponding to the first absorption part are transferred later, thereby realizing the dispersive transfer of the micro light-emitting diodes; this dispersive transfer process only requires multiple laser irradiations and does not require other transfer tools, with simple operation, reducing the workload of the dispersive transfer of micro light-emitting diodes and lowering the cost of the dispersive transfer of micro light-emitting diodes. Description of the Drawings

[0026] The following will, in conjunction with the drawings, make the technical solutions and other beneficial effects of the present application obvious through a detailed description of the specific embodiments of the present application.

[0027] Figure 1 It is a flowchart of the method for dispersive transfer of micro light-emitting diodes provided by an embodiment of the present invention;

[0028] Figure 2 It is a first structural schematic diagram of the method for dispersive transfer of micro light-emitting diodes provided by an embodiment of the present invention;

[0029] Figure 3 It is a second structural schematic diagram of the method for dispersive transfer of micro light-emitting diodes provided by an embodiment of the present invention. Detailed Embodiments

[0030] The following will, in conjunction with the specific implementation schemes of the present invention, clearly and completely describe the technical solutions in the implementation schemes and / or embodiments of the present invention. Obviously, the following described implementation schemes and / or embodiments are only a part of the implementation schemes and / or embodiments of the present invention, rather than all of the implementation schemes and / or embodiments. Based on the implementation schemes and / or embodiments in the present invention, all other implementation schemes and / or embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] The directional terms mentioned in the present invention, such as [up], [down], [left], [right], [front], [rear], [inside], [outside], [side], etc., are only references to the directions in the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, rather than for limiting the present invention. The terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0032] Aiming at the problems of excessive workload and low transfer and dispersion efficiency in the existing micro-light emitting diode dispersion transfer method, the present invention provides a micro-light emitting diode dispersion transfer method to solve this problem.

[0033] In one embodiment, please refer to Figure 1 and Figure 2 , Figure 1 which shows the flowchart of the micro-light emitting diode dispersion transfer method provided by the embodiment of the present invention, Figure 2 and Figure 1 and Figure 2 show the first structural schematic diagram of the micro-light emitting diode dispersion transfer method provided by the embodiment of the present invention. As shown in

[0034] Step B1: Provide a substrate, and prepare micro-light emitting diodes arranged in an array with a predetermined interval on the substrate.

[0035] Specifically, please refer to Figure 2 (a) therein. Since the structure of micro-light emitting diodes usually requires the use of Metal-organic Chemical Vapor Deposition (abbreviated as MOCVD), and the deposition temperature of the metal-organic chemical vapor deposition process generally needs to reach above 1000 degrees Celsius, therefore, the substrate 11 generally uses a sapphire substrate, a silicon carbide substrate or a silicon substrate, etc.

[0036] The micro-light emitting diode 12 includes a gallium nitride epitaxial layer, an N-type gallium nitride layer, a multi-quantum well layer, a P-type gallium nitride layer, an insulating layer, a current diffusion layer, a protective layer, and an N-type and p-type electrode layer stacked in sequence on the base substrate 11. The multi-quantum well layer is arranged between the N-type gallium nitride layer and the P-type gallium nitride layer. The multi-quantum well layer is generally composed of multiple overlapping indium gallium nitride layers and gallium nitride layers. The insulating layer and the protective layer are generally insulating material layers such as silicon oxide or silicon nitride. The material of the current diffusion layer is generally transparent indium tin oxide, or graphene or other metals. The N-type and P-type electrode layers are any one of platinum, gold, nickel, chromium and other metals or their alloys. The micro-light emitting diode 12 can also be other structures known to those skilled in the art. The micro-light emitting diode 12 can be prepared by any method for preparing an MLED chip known to those skilled in the art, and is not particularly limited here.

[0037] The micro LEDs 12 are arranged in an array on the base substrate 11 , and the distance between the centers of two adjacent micro LEDs 12 is the predetermined interval L1 .

[0038] Step B2, preparing a first absorption portion arranged in an array and having a target interval on a side of the base substrate away from the micro-LED; the first absorption portion is arranged corresponding to the micro-LED, the target interval is an integer multiple of the predetermined interval, and the integer multiple is greater than or equal to 2.

[0039] Please refer to Figure 2 In (b), an absorption layer is deposited on the side of the base substrate 11 away from the micro-LED 12, and the absorption layer is patterned to obtain the first absorption part 13. The first absorption parts 13 are arranged in an array on the base substrate 11, and the centers of two adjacent first absorption parts 13 have the target interval L2. The target interval L2 is consistent with the distance between the centers of two adjacent pixels of the display panel, and the target interval L2 is an integer multiple of the predetermined interval L1, and the integer multiple is greater than or equal to 2.

[0040] The first absorption portion 13 is provided corresponding to the micro-LED 12, and the first absorption portion 13 covers the corresponding micro-LED 12, thereby shielding the micro-LED 12 corresponding to the first absorption portion 13. The area of ​​the first absorption portion 13 is greater than or equal to the area of ​​the micro-LED 12, and the diameter of the first absorption portion 13 is less than the predetermined interval L1, thereby preventing the first absorption portion 13 from shielding or covering the adjacent micro-LED 12.

[0041] When only the first absorption part 13 is included on the side of the substrate 11 facing away from the micro light-emitting diode, the target interval L2 is twice the predetermined interval L1; the number of the first absorption parts 13 is half of that of the micro light-emitting diodes 12, and the first absorption parts 13 cover the micro light-emitting diodes 12 at intervals, as shown in Figure 2 (b). The thickness range of the first absorption part 13 is 10 Å - 100 Å, and preferably the thickness range of the first absorption part 13 is 30 Å - 40 Å. The material of the first absorption part 13 is amorphous silicon. The transmittance of the first absorption part 13 to visible light is approximately 90%, and the transmittance of the first absorption part 13 to ultraviolet laser is 50% - 80%, and preferably the transmittance of the first absorption part 13 to ultraviolet laser is 60% - 70%.

[0042] Step B3: Adopt a laser ablation process to irradiate the substrate and the micro light-emitting diode with laser light from the side of the first absorption part, and transfer part of the micro light-emitting diodes to an intermediate substrate.

[0043] Specifically, please refer to Figure 2 (c). The semiconductor laser emits a laser beam with a wavelength range of 300 nm - 400 nm, and the laser beam irradiates the substrate 11 and the micro light-emitting diode 12 from the side of the first absorption part 13. Due to the different bandgap widths between the gallium nitride epitaxial layer and the substrate 11, when the gallium nitride epitaxial layer is irradiated with the laser beam, the low-bandwidth gallium nitride epitaxial layer absorbs the laser energy and expands due to heat, so that the contact area between the micro light-emitting diode 12 and the substrate 11 becomes smaller. Under the action of gravity, the micro light-emitting diode 12 is peeled off from the substrate 11 onto the intermediate substrate 14.

[0044] When the laser beam irradiates the first absorption part 13, part of the energy of the laser beam is blocked and absorbed by the first absorption part 13, and only 50% - 80% of the energy passes through the first absorption part 13 to reach the substrate 11 and even the micro light-emitting diode 12; for the part not covered by the first absorption part 13, about 95% of the energy of the laser beam reaches the micro light-emitting diode 12. Therefore, by controlling the irradiation time of the laser beam, the micro light-emitting diodes 12 not covered and blocked by the first absorption part 13 are irradiated with sufficient laser energy and transferred to the intermediate substrate 14; the micro light-emitting diodes 12 covered and blocked by the first absorption part 13 remain on the intermediate substrate 14 because they are not irradiated with sufficient laser energy. The micro light-emitting diodes 12 transferred to the intermediate substrate 14 have the target interval L2.

[0045] Step B4, move the base substrate, and irradiate the base substrate and the micro-LEDs with laser again from the first absorption part side, and repeat until all the micro-LEDs are transferred to the target position of the intermediate substrate.

[0046] Please refer to Figure 2 In step (d), the base substrate 11 is moved to the remaining blank positions of the target substrate 14, and the laser beam is used again to irradiate the base substrate 11 and the micro-LEDs 12 from the first absorption portion 13 side, so that the micro-LEDs 12 on the base substrate 11 that are covered and blocked by the first absorption portion 13 are transferred to the intermediate substrate 14. The micro-LEDs 12 on the intermediate substrate 14 all have the target interval L2.

[0047] Step B5: transferring the micro light emitting diodes on the intermediate substrate to a target substrate.

[0048] Please refer to Figure 2 In (e), the micro-LEDs 12 are transferred from the intermediate substrate 14 to the target substrate 15, and the micro-LEDs 12 on the target substrate 15 also have the target interval L2. At this point, the micro-LEDs 12 on the base substrate 11 with the predetermined interval L1 are transferred to the target substrate with the target interval L2, and the dispersed transfer of the micro-LEDs 12 is completed.

[0049] In the embodiment of the present invention, a first absorption portion corresponding to a part of the micro-LEDs is arranged on a side of the base substrate away from the micro-LEDs, and the first absorption portion absorbs and blocks part of the laser energy. When the micro-LEDs are transferred, the micro-LEDs not corresponding to the first absorption portion are transferred first, and the micro-LEDs corresponding to the first absorption portion are transferred later, thereby realizing the dispersed transfer of the micro-LEDs.

[0050] When the target interval L2 is significantly different from the predetermined interval L1, for example, when the target interval L2 is three times the predetermined interval L1, the micro-LED 12 needs to be irradiated with laser light three times to complete the three-fold distance dispersion transfer. Figure 3 , Figure 3 A second structural schematic diagram of the micro-LED dispersion method provided in an embodiment of the present invention is shown.

[0051] Then, the step B2 should be: preparing the first absorption part 13 and the second absorption part 16 arranged in an array and having the target interval L2 on the side of the base substrate 11 away from the micro-LED 12 .

[0052] Please refer to Figure 3 In (b), the target interval L2 is provided between the centers of adjacent first absorbing parts 13, the target interval L2 is provided between the centers of adjacent second absorbing parts 16, and the target interval L2 or the predetermined interval L1 is provided between the centers of adjacent first absorbing parts 13 and second absorbing parts 16. Similarly, the second absorbing part 16 is provided corresponding to the micro-LED 12, and the second absorbing part 16 covers the corresponding micro-LED 12. The area of ​​the second absorbing part 16 is greater than or equal to the area of ​​the micro-LED 12, and the diameter of the second absorbing part 16 is less than the predetermined interval L1. Preferably, the diameter of the second absorbing part 16 is the same as the diameter of the first absorbing part 13. The thickness of the second absorbing part 16 is twice the thickness of the first absorbing part 13.

[0053] Then, the step B4 further includes: moving the base substrate, and irradiating the base substrate and the micro-LEDs with laser for a third time from the first absorption part side until all the micro-LEDs are transferred to the target position of the intermediate substrate.

[0054] Please refer to Figure 3 In (e), since the thickness of the second absorption part 16 is twice that of the first absorption part 13, the blocking and absorbing effect of the second absorption part 16 on the laser beam is twice that of the first absorption part 13. Therefore, during the first two laser irradiation processes, the micro-LED 12 covered and blocked by the second absorption part 16 continues to remain on the base substrate 11 because it does not absorb enough laser energy, and is peeled off from the base substrate 11 and transferred to the intermediate substrate 14 during the third laser irradiation process.

[0055] In summary, an embodiment of the present invention provides a method for the dispersed transfer of micro-LEDs, by setting a first absorption portion corresponding to part of the micro-LEDs on a side of the substrate away from the micro-LEDs, and absorbing the blocked part of the laser energy through the first absorption portion. When the micro-LEDs are transferred, the micro-LEDs not corresponding to the first absorption portion are transferred first, and the micro-LEDs corresponding to the first absorption portion are transferred later, thereby realizing the dispersed transfer of the micro-LEDs. The dispersed transfer process only requires multiple laser irradiations and does not require other transfer tools. The operation is simple, which reduces the workload of the dispersed transfer of micro-LEDs and reduces the cost of the dispersed transfer of micro-LEDs.

[0056] The above has introduced in detail the method for dispersing and transferring micro light-emitting diodes provided by the embodiments of the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for dispersing and transferring micro light-emitting diodes, characterized in that, Including: Providing a substrate, and fabricating micro light-emitting diodes arranged in an array with a predetermined interval on the substrate; Fabricating a first absorption part arranged in an array with a target interval on a side of the substrate facing away from the micro light-emitting diodes; the first absorption part is arranged corresponding to the micro light-emitting diodes, the target interval is an integer multiple of the predetermined interval, and the integer multiple is greater than or equal to 2; Adopting a laser ablation process to irradiate the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part, and transferring the micro light-emitting diodes not covered and blocked by the first absorption part to an intermediate substrate; Moving the substrate, and irradiating the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part again, repeating until all the micro light-emitting diodes covered and blocked by the first absorption part are transferred to a target position on the intermediate substrate; Transferring the micro light-emitting diodes on the intermediate substrate to a target substrate.

2. The dispersion transfer method according to claim 1, wherein The first absorption part covers the corresponding micro light-emitting diodes.

3. The dispersion transfer method according to claim 2, wherein The area of the first absorption part is greater than or equal to the area of the micro light-emitting diodes, and the diameter of the first absorption part is less than the predetermined interval.

4. The dispersion transfer method according to claim 1, characterized in that, The thickness range of the first absorption part is 10 Å - 100 Å.

5. The dispersion transfer method according to claim 1, wherein The transmittance of the first absorption part to the laser is 50% - 80%.

6. The dispersion transfer method according to claim 1, characterized in that, The material of the first absorption part is amorphous silicon.

7. The dispersion transfer method according to claim 1, wherein The step of adopting a laser ablation process to irradiate the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part, and transferring the micro light-emitting diodes not covered and blocked by the first absorption part to an intermediate substrate includes: Adopting a laser with a wavelength range of 300 nm - 400 nm to irradiate the substrate and the micro light-emitting diodes from the side of the first absorption part, and transferring the micro light-emitting diodes corresponding to the first absorption part to the intermediate substrate.

8. The dispersion transfer method according to claim 7, wherein The step of moving the substrate, and irradiating the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part again, repeating until all the micro light-emitting diodes covered and blocked by the first absorption part are transferred to a target position on the intermediate substrate includes: Moving the substrate, and irradiating the substrate and the micro light-emitting diodes with laser light from the side of the first absorption part again, and transferring the micro light-emitting diodes corresponding to the first absorption part to the intermediate substrate.

9. The dispersion transfer method according to any one of claims 1 to 8, characterized in that While fabricating the first absorption part on a side of the substrate facing away from the micro light-emitting diode array, the dispersion transfer method further includes: Fabricating a second absorption part arranged in an array with the target interval on a side of the substrate facing away from the micro light-emitting diodes; the thickness of the second absorption part is twice the thickness of the first absorption part.

10. The dispersion transfer method according to claim 9, characterized in that, There is the predetermined interval or the target interval between adjacent first absorption parts and second absorption parts.

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