Light-emitting diode structure with improved bonding yield

Abstract

A light-emitting diode structure for improving bonding yield includes a light-emitting diode, a plurality of contact electrodes, an insulating layer structure, and a plurality of bonding electrodes. One side of the light-emitting diode includes a boss structure. The contact electrodes are arranged on the boss structure and are separated from each other when viewed from above. The insulating layer structure is arranged on the contact electrodes. The bonding electrodes are arranged on the insulating layer structure and cover at least one contact electrode respectively. The side of the bonding electrode away from the light-emitting diode has a first platform and a second platform. The second platform is located on the first platform and is farther away from the boss structure than the first platform. The surface area of ​​the vertical projection of the second platform on the light-emitting diode is smaller than the surface area of ​​the vertical projection of the first platform on the light-emitting diode, and the vertical projection of the second platform is located within the vertical projection of the first platform. The present invention achieves the effect of good electrical contact between the light-emitting diode and the contact pad on the display panel during the bonding process through the relatively raised structure of the second platform.

Description

Technical Field

[0001] The present disclosure relates to a light emitting diode structure with improved bonding yield. Background Art

[0002] The statements herein merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] In recent years, various new types of displays have gradually emerged. Most of these displays are developing in the direction of increasing resolution and energy saving, and micro light-emitting diodes (μLEDs) are one of the important development types.

[0004] μLED shrinks the size of traditional LEDs to the order of about 100 microns or even tens of microns. At this order of magnitude, the number of LEDs in the same area increases dramatically, so the yield of LEDs transferred from the growth substrate to the display panel must reach more than 99%. With today's process technology, there are still many technical challenges to be solved in this mass transfer. For example, the last step of mass transfer is the bonding process, which is a key procedure for bonding μLEDs to the display panel. Because the size of μLEDs is too small, there are limitations on bonding materials and methods, and it is very challenging to achieve a high yield. Summary of the invention

[0005] In the above-mentioned bonding process, a method that has been used is to first apply a glue layer on the display panel, and then use mechanical pressure to push the μLED through the glue layer and electrically contact the contact pad on the display panel. However, this method still has the problem of poor contact.

[0006] In view of this, some embodiments of the present disclosure disclose a light-emitting diode structure that improves bonding yield, including a light-emitting diode, a plurality of contact electrodes, an insulating layer structure, and a plurality of bonding electrodes. One side of the light-emitting diode includes a plurality of boss structures. The contact electrodes are arranged on the boss structures, and the contact electrodes are separated from each other when viewed from above. The insulating layer structure is arranged on the contact electrodes. The bonding electrodes are arranged on the insulating layer structure and cover at least one contact electrode respectively. A side of the bonding electrode away from the light-emitting diode has a first platform and a second platform. The second platform is located on the first platform and is farther away from the boss structure than the first platform. The surface area of ​​the vertical projection of the second platform on the light-emitting diode is smaller than the surface area of ​​the vertical projection of the first platform on the light-emitting diode, and the vertical projection of the second platform is located within the vertical projection of the first platform.

[0007] In one or more embodiments of the present disclosure, the surface morphologies of the insulating layer structure, the boss structure, and the contact electrode are substantially conformal, and the surface morphologies of the bonding electrode and the insulating layer structure are substantially conformal.

[0008] In one or more embodiments of the present disclosure, the surface area of ​​each second platform perpendicularly projected on the LED is less than about 80 square microns. The surface area of ​​the LED perpendicularly projected in the direction of the projection plane is between about 100 square microns and 10,000 square microns.

[0009] In one or more embodiments of the present disclosure, the insulating layer structure includes a first insulating layer and a second insulating layer. The first insulating layer contacts and is disposed on the sidewall and upper surface of the light-emitting diode and the side and surface of the boss structure. The second insulating layer is disposed on the first insulating layer and is substantially conformal to the first insulating layer.

[0010] In one or more embodiments of the present disclosure, the light emitting diode structure further includes a mirror conductive layer disposed between the first insulating layer and the second insulating layer, and the mirror conductive layer contacts the contact electrode.

[0011] In one or more embodiments of the present disclosure, the second insulating layer has a through hole, and at least one bonding electrode contacts the mirror conductive layer through the through hole.

[0012] In one or more embodiments of the present disclosure, a vertical projection range of the through hole on the light emitting diode is separated from a vertical projection range of the contact electrode on the light emitting diode.

[0013] In one or more embodiments of the present disclosure, a vertical projection of the second platform on the light-emitting diode at least partially overlaps with a vertical projection of the contact electrode on the light-emitting diode.

[0014] In one or more embodiments of the present disclosure, the light emitting diode structure further includes a mirror conductive layer disposed between the boss structure and the insulating layer structure and covering the contact electrode.

[0015] In one or more embodiments of the present disclosure, the insulating layer structure has a through hole, at least one bonding electrode contacts the mirror conductor layer through the through hole, and a vertical projection range of the through hole on the light emitting diode is separated from a vertical projection range of the contact electrode on the light emitting diode.

[0016] The bonding electrode disclosed in the present invention has both the functions of electrical connection and improving the bonding yield. Through the double-layer platform structure of the first platform and the second platform, the second platform is more convex and has a smaller surface area, so that the light-emitting diode structure can better pass through the glue layer on the bonding substrate during the bonding process and have good electrical contact with the contact pad on the display panel, while at the same time not reducing the light-emitting area of ​​the light-emitting diode structure.

[0017] In order to make the above features and advantages of the present disclosure more obvious and understandable, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A A schematic cross-sectional view of a light emitting diode structure in some embodiments of the present disclosure is shown;

[0019] Figure 1B A schematic top view of a light emitting diode structure in some embodiments of the present disclosure is shown;

[0020] Figure 2 A schematic cross-sectional view of a light emitting diode structure in some embodiments of the present disclosure is shown;

[0021] Figure 3 A cross-sectional view showing a light emitting diode structure bonded to a display panel in some embodiments of the present disclosure is shown.

[0022]

Explanation of symbols

[0023] 1000: Light Emitting Diode Structure

[0024] 100: Light Emitting Diode

[0025] 102: Boss structure

[0026] 1022: Side

[0027] 1024: Surface

[0028] 104: Side wall

[0029] 106: Upper surface

[0030] 200,200': Contact electrode

[0031] 300: Insulation layer structure

[0032] 310: first insulating layer

[0033] 320: Second insulation layer

[0034] 330: The third insulating layer

[0035] 400: Bonding electrode

[0036] 402: First Platform

[0037] 404: Second Platform

[0038] 500, 500A: mirror conductor layer

[0039] 600: Display board

[0040] 610: Contact pad

[0041] 620: Adhesive layer

[0042] V:Through hole DETAILED DESCRIPTION

[0043] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation and specific embodiments of the present disclosure; however, this is not the only form of implementing or using the specific embodiments of the present disclosure. The various embodiments disclosed below can be combined or replaced with each other under beneficial circumstances, and other embodiments can be added to one embodiment without further recording or explanation.

[0044] In the following description, many specific details will be described in detail to enable the reader to fully understand the following embodiments. However, the embodiments of the present disclosure can be practiced without these specific details. In other cases, in order to simplify the drawings, well-known structures and devices are only schematically depicted in the drawings.

[0045] refer to Figure 1A and Figure 1B . Figure 1A A cross-sectional view of a light emitting diode structure 1000 in some embodiments of the present disclosure is shown. Figure 1B A schematic top view of a light emitting diode structure 1000 in some embodiments of the present disclosure is shown, and the dotted circle portion represents a structure that can only be seen through perspective. Figure 1B The section line A-A' in the Figure 1A The illustrated content. The light-emitting diode structure 1000 includes a light-emitting diode 100, a plurality of contact electrodes 200, an insulating layer structure 300, and a plurality of bonding electrodes 400. One side of the light-emitting diode 100 includes a boss structure 102. The light-emitting diode 100 can be a light-emitting structure that is biased toward blue light, such as a structure based on gallium nitride (GaN); or a light-emitting structure that is biased toward yellow light / red light, such as a structure based on gallium phosphide (GaP). The light-emitting diode 100 can also be composed of other common light-emitting semiconductor substrates, which are not listed in detail here.

[0046] The boss structure 102 may include an N-doped semiconductor material and a P-doped semiconductor material. When the light-emitting diode 100 is a GaN substrate, the side of the boss structure 102 adjacent to the contact electrode 200 may be P-doped GaN, and the side away from the contact electrode 200 may be N-doped GaN. When the light-emitting diode 100 is a GaP substrate, the side of the boss structure 102 adjacent to the contact electrode 200 may be N-doped aluminum gallium indium phosphide (AlGaInP), and the side away from the contact electrode 200 may be P-doped GaP.

[0047] The contact electrodes 200 are disposed on the boss structure 102. When the light emitting diode structure 1000 is viewed from above, the plurality of contact electrodes 200 are separated from each other in a perspective view. The above-mentioned view from above refers to a view from the -Z direction. Figure 1A The contact electrode 200 may be composed of a doped semiconductor material layer and / or a metal layer, wherein two opposite surfaces of the doped semiconductor material layer contact the metal layer and the boss structure 102 of the light-emitting diode 100, respectively, to help reduce the resistance of the electrical contact surface between the contact electrode 200 and the semiconductor. Due to limitations in material selection, the contact electrodes 200 are mostly more light-absorbing. Generally speaking, the structure of the contact electrode 200 in the prior art is mostly strip-shaped or planar, that is, one contact electrode 200 is used to contact a large-area boss structure 102. In contrast, the contact electrode 200 described in the above-mentioned embodiments of the present disclosure is a plurality of small-area electrodes (such as Figure 1B In this structure, not only can the light absorption of the contact electrode 200 be reduced, but also the subsequent bonding electrode 400 can be more easily formed into a double-layer platform structure.

[0048] The insulating layer structure 300 is disposed on the contact electrode 200. The bonding electrode 400 is disposed on the insulating layer structure 300 and covers at least one of the aforementioned plurality of contact electrodes 200. The bonding electrode 400 has a first platform 402 and a second platform 404 on a side away from the light-emitting diode 100. The second platform 404 is located on the first platform 402 and is farther away from the boss structure 102 than the first platform 402. The surface area of ​​the vertical projection of the second platform 404 on the light-emitting diode 100 is smaller than the surface area of ​​the vertical projection of the first platform 402 on the light-emitting diode 100. The aforementioned vertical projection of the second platform 404 is located within the aforementioned vertical projection of the first platform 402. By disposing the first platform 402 and the second platform 404 on top, the quality of the contact surface between the light-emitting diode structure 1000 and the bonding target substrate can be improved in the last step of the bonding process of the transfer process, thereby increasing the success rate of the bonding process. The reason for this is that the second platform 404 has a smaller surface area, that is, it is more convex. Therefore, during the transfer process, the structure of the second platform 404 can better penetrate (displace) the adhesive layer and bond with the transfer target substrate. The schematic diagram of this part will be shown later ( Figure 3). In some embodiments, the first platform 402 and the second platform 404 are integrally formed and can be completed in the same process (such as a metal plating process). In some embodiments, the insulating layer structure 300 is substantially conformal to the surface morphology of the boss structure 102, and is substantially conformal to the surface morphology of each contact electrode 200. The surface morphology of the bonding electrode 400 is substantially conformal to that of the insulating layer structure 300. Under the above-mentioned embodiment, due to the presence of the first platform 402, it is not necessary to reduce the boss structure 102 to match the surface area of ​​the second platform 404, so the light-emitting layer (active layer) area in the boss structure 102 can be improved while improving the quality of the upper open contact surface.

[0049] In some embodiments, the vertical projection of the second platform 404 on the light-emitting diode 100 at least partially overlaps with the vertical projection of the contact electrode 200 on the light-emitting diode 100. In other words, the structure of the second platform 404 is arranged directly above the contact electrode 200 (in the +Z direction), that is, directly above the boss structure 102 (in the +Z direction). Such an arrangement can make the formation of a double-layer platform structure (for example, the first platform 402 and the second platform 404 structure depicted in the embodiment) easier and the use of materials more economical. In some embodiments, the surface area of ​​the vertical projection of each second platform 404 on the light-emitting diode 100 is less than about 80 square microns. The light-emitting diode 100 is parallel to the direction in which the vertical projection plane extends (i.e. Figure 1A The surface area of ​​the substrate (in the XY plane extending direction) is between about 100 square microns and 10,000 square microns. Under the above surface area conditions, the upper opening bonding process can achieve better electrical contact quality with the target substrate.

[0050] In some embodiments, the insulating layer structure 300 includes a first insulating layer 310 and a second insulating layer 320. The first insulating layer 310 contacts and is disposed on the sidewall 104 and the upper surface 106 of the light-emitting diode 100 and the side surface 1022 and the surface 1024 of the boss structure 102. The second insulating layer 320 is disposed on the first insulating layer 310 and is substantially conformal to the first insulating layer 310. In some embodiments, the insulating layer structure 300 further includes a third insulating layer 330, which is disposed on the second insulating layer 320 and is substantially conformal to the second insulating layer 320. The first insulating layer 310, the second insulating layer 320, and the third insulating layer 330 may be insulating layers formed by atomic layer deposition (ALD).

[0051] In some embodiments, the light emitting diode structure 1000 further includes a mirror conductor layer 500 disposed between the first insulating layer 310 and the second insulating layer 320. The mirror conductor layer 500 contacts the aforementioned plurality of contact electrodes 200, and has a much larger area than the contact electrodes 200 in the XY plane extension direction, so as to diffuse and guide the current to be injected into each contact electrode 200, so as to increase the current uniformity of the light emitting diode 100 in the XY extension direction and improve the light emitting efficiency. In some embodiments, the second insulating layer 320 and / or the third insulating layer 330 are formed and have a through hole V. At least one bonding electrode 400 contacts the mirror conductor layer 500 through the through hole V.

[0052] In addition, in order to better diffuse and increase the uniformity of the current, the vertical projection range of the through hole V on the light-emitting diode 100 and the vertical projection range of the contact electrode 200 on the light-emitting diode 100 are separated from each other. In other words, the through hole V is not directly arranged above the contact electrode 200 (in the +Z direction), which allows the current injected from the through hole V into the mirror conductor layer 500 to diffuse horizontally (along the XY plane direction) to multiple contact electrodes 200 and then enter the semiconductor layer of the light-emitting diode 100 to achieve the effect of current diffusion. In addition, the setting of the mirror conductor layer 500 can also reflect the light emitted by the light-emitting diode 100 to increase the light extraction rate in the -Z direction. The mirror conductor layer 500 can be arranged conformally with the boss structure 102 and cover the side surface 1022 and the upper surface 106 to achieve a better light reflection effect. The mirror conductor layer 500 can be composed of silver (silver, Ag), but is not limited thereto.

[0053] refer to Figure 2 . Figure 2 A schematic cross-sectional view of the light-emitting diode structure 1000A in some embodiments of the present disclosure is shown. In some embodiments, the mirror conductor layer 500A is disposed between the boss structure 102 and the insulating layer structure 300 and covers and contacts the aforementioned contact electrode 200. In some embodiments, the mirror conductor layer 500A is entirely located above the boss structure 102 and contacts and covers the surface 1024 of the boss structure 102 and the contact electrode 200 on its entire surface. Through the aforementioned large-area electrical contact, the effect of enhancing current diffusion can be achieved. Of course, a conductive layer (for example, an indium tin oxide (ITO) film) may also be disposed between the mirror conductor layer 500A and the boss structure 102 to achieve a uniform current effect. Figure 2In the illustrated embodiment, the insulating layer structure 300 has a through hole V. At least one bonding electrode 400 contacts the mirror conductor layer 500A through the through hole V, and the vertical projection range of the through hole V on the light-emitting diode 100 is separated from the vertical projection range of the contact electrode 200 on the light-emitting diode 100. In some embodiments, the bonding electrode 400 can even directly contact the semiconductor of the light-emitting diode 100 through the through hole V, or contact the semiconductor of the light-emitting diode 100 through a contact electrode 200', providing multiple electrical contact points and achieving a better current diffusion effect.

[0054] refer to Figure 3 . Figure 3 The cross-sectional view of some embodiments of the present disclosure showing the LED structure 1000 being bonded to the display panel 600 is shown. As mentioned above, the structures of the first platform 402 and the second platform 404 of the LED structure 1000 can improve the electrical contact quality after the bonding process. Figure 3 That is, a schematic diagram after the bonding process is completed is shown. In some embodiments, by applying pressure to the light-emitting diode structure 1000 and / or the display panel 600, the second platform 404 passes through and pushes away the glue layer 620 (for example, polymethylmethacrylate (PMMA), but not limited thereto) on the display panel 600, and contacts the contact pad 610 on the display panel 600. Through the double-layer platform setting described in the above embodiments of this document, through the area size and position relationship between the first platform 402 and the second platform 404 on the XY plane, the second platform 404 can easily push away the glue layer 620 and generate better electrical contact with the contact pad 610, thereby improving the process yield.

[0055] In summary, the embodiments disclosed herein provide a light-emitting diode structure with improved bonding yield. By setting up a double-layer platform of a first platform and a second platform, and utilizing a structure in which the second platform is relatively convex and has a smaller surface area, the light-emitting diode structure can better penetrate the glue layer on the bonding substrate during the bonding process and have good electrical contact with the contact pad on the display panel, while not reducing the light-emitting area of ​​the light-emitting diode structure. In addition, the setting of the mirror conductor layer further improves the current diffusion effect in the light-emitting diode and the light extraction rate of the light-emitting diode.

[0056] Although the present disclosure has been disclosed as above by way of embodiments, it is not intended to limit the present disclosure. Anyone skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the scope defined in the attached claims.

Claims

1. A light emitting diode structure for improving bonding yield, It is characterized in that include: A light emitting diode, one side of which includes a boss structure; A plurality of contact electrodes are disposed on the boss structure, wherein the plurality of contact electrodes are separated from each other when viewed from above; An insulating layer structure, disposed on the plurality of contact electrodes; a plurality of bonding electrodes, disposed on the insulating layer structure and respectively covering at least one of the plurality of contact electrodes, wherein a surface of one of the plurality of bonding electrodes away from the light-emitting diode comprises a first platform and a second platform, the second platform is located on the first platform and is farther away from the boss structure than the first platform, a surface area of ​​a vertical projection of the second platform on the light-emitting diode is smaller than a surface area of ​​a vertical projection of the first platform on the light-emitting diode, and a vertical projection of the second platform is located within a vertical projection of the first platform; and A mirror conductor layer, disposed between the boss structure and the insulating layer structure and covering the plurality of contact electrodes; The insulating layer structure has a through hole, one of the plurality of bonding electrodes contacts the mirror conductor layer through the through hole, and a vertical projection range of the through hole on the light-emitting diode is separated from a vertical projection range of the plurality of contact electrodes on the light-emitting diode.

2. The light emitting diode structure according to claim 1, It is characterized in that The insulating layer structure conforms to the surface morphology of the boss structure and the plurality of contact electrodes, and the plurality of bonding electrodes conforms to the surface morphology of the insulating layer structure.

3. The light emitting diode structure according to claim 1, It is characterized in that The surface area of ​​the second platform in a vertical projection on the light-emitting diode is less than 80 square microns, and the surface area of ​​the light-emitting diode in a direction extending from the vertical projection plane is between 100 square microns and 10,000 square microns.

4. The light emitting diode structure according to claim 1, It is characterized in that The insulating layer structure includes a first insulating layer and a second insulating layer, wherein the first insulating layer contacts and is arranged on the side wall and the upper surface of the light-emitting diode and the side and the surface of the boss structure, and the second insulating layer is arranged on the first insulating layer and conforms to the first insulating layer.

5. The light emitting diode structure according to claim 4, It is characterized in that The mirror conductor layer is disposed between the first insulating layer and the second insulating layer, and the mirror conductor layer contacts the plurality of contact electrodes.

6. The light emitting diode structure according to claim 5, It is characterized in that The second insulating layer includes the through hole.

7. The light emitting diode structure according to claim 1, It is characterized in that A vertical projection of the second platform on the light-emitting diode at least partially overlaps with a vertical projection of one of the plurality of contact electrodes on the light-emitting diode.

8. A light emitting diode structure for improving bonding yield, It is characterized in that include: A light emitting diode, one side of which includes a boss structure; a plurality of contact electrodes, at least one of which is disposed on the boss structure; An insulating layer structure is disposed on the contact electrode; a plurality of bonding electrodes disposed on the insulating layer structure and covering the contact electrode, wherein a surface of one of the plurality of bonding electrodes away from the light-emitting diode comprises a first platform and a second platform, the second platform is located on the first platform and is farther away from the boss structure than the first platform, a surface area of ​​a vertical projection of the second platform on the light-emitting diode is smaller than a surface area of ​​a vertical projection of the first platform on the light-emitting diode, and a vertical projection of the second platform is located within a vertical projection of the first platform; and A mirror conductor layer is disposed between the boss structure and the insulating layer structure and covers the contact electrode; The insulating layer structure has a through hole, one of the plurality of bonding electrodes contacts the mirror conductor layer through the through hole, and a vertical projection range of the through hole on the light-emitting diode is separated from a vertical projection range of the contact electrode on the light-emitting diode.

9. The light emitting diode structure according to claim 8, It is characterized in that The insulating layer structure conforms to the surface morphology of the boss structure and the contact electrode, and the bonding electrode conforms to the surface morphology of the insulating layer structure.

10. The light emitting diode structure according to claim 8, It is characterized in that The surface area of ​​the second platform in a vertical projection on the light-emitting diode is less than 80 square microns, and the surface area of ​​the light-emitting diode in a direction extending from the vertical projection plane is between 100 square microns and 10,000 square microns.

11. The light emitting diode structure according to claim 8, It is characterized in that The insulating layer structure comprises a first insulating layer and a second insulating layer, the first insulating layer contacts and is arranged on the side wall and the upper surface of the light emitting diode and the side and the surface of the boss structure, and the second insulating layer is arranged on the first insulating layer.

12. The light emitting diode structure according to claim 11, It is characterized in that The mirror conductor layer is disposed between the first insulating layer and the second insulating layer, and the mirror conductor layer contacts the contact electrode.

13. The light emitting diode structure according to claim 12, It is characterized in that The second insulating layer includes the through hole.

14. The light emitting diode structure according to claim 8, It is characterized in that A vertical projection of the second platform on the light-emitting diode at least partially overlaps with a vertical projection of the contact electrode on the light-emitting diode.

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