CN114975696A

CN114975696A - Micro light-emitting diode, display panel and preparation method

Info

Publication number: CN114975696A
Application number: CN202210554330.XA
Authority: CN
Inventors: 吴涛; 管云芳
Original assignee: Shenzhen Stan Technology Co Ltd
Current assignee: Shenzhen Stan Technology Co Ltd
Priority date: 2022-05-20
Filing date: 2022-05-20
Publication date: 2022-08-30

Abstract

The application discloses a micro light-emitting diode, a display panel and a preparation method, and relates to the technical field of micro light-emitting diodes. The preparation method of the micro light-emitting diode comprises the following steps: sequentially manufacturing an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer on a substrate to manufacture an epitaxial wafer on the substrate; etching the epitaxial wafer from the P-type semiconductor layer to the N-type semiconductor layer to obtain a plurality of light-emitting steps and an N-type semiconductor vacant region, so that the light-emitting steps surround the N-type semiconductor vacant region at intervals in the circumferential direction; and manufacturing a first electrode on one side of the light-emitting step, which is far away from the substrate, manufacturing a second electrode in the N-type semiconductor vacant area, wherein the plurality of light-emitting steps in the same micro light-emitting diode share one second electrode. According to the preparation method of the micro light-emitting diode, the transfer times can be reduced and the transfer efficiency can be improved when the subsequent micro light-emitting diode is transferred.

Description

Micro light-emitting diode, display panel and preparation method

Technical Field

The application relates to the technical field of micro light-emitting diodes, in particular to a micro light-emitting diode, a display panel and a preparation method.

Background

The Micro-LED display technology is a display technology in which a conventional LED structure is miniaturized and arrayed, and a driving circuit is fabricated using a Complementary Metal Oxide Semiconductor (CMOS) or a Thin Film Transistor (TFT) to realize address control and individual driving of each pixel.

Although Micro-LEDs have significant advantages as Display technologies compared to Liquid Crystal Displays (LCDs) and Organic Light-Emitting Semiconductors (OLEDs), the industrialization of Micro-LEDs faces a number of important technical challenges, such as the mass transfer of Micro-LEDs. At present, a Micro-light emitting diode (Micro-LED) is generally transferred in a mounting (Pick-Place) mode and the like, but the problems of low transfer speed and the like still exist, and the problems of low efficiency and high cost are caused.

Disclosure of Invention

The application provides a micro light-emitting diode, a display panel and a preparation method, which aim to reduce the difficulty of micro light-emitting diode transfer and improve the transfer efficiency.

In a first aspect, the present application provides:

a method for preparing a micro light-emitting diode comprises the following steps:

sequentially manufacturing an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer on a substrate to manufacture an epitaxial wafer on the substrate;

etching the epitaxial wafer from the P-type semiconductor layer to the N-type semiconductor layer to obtain a plurality of light-emitting steps and an N-type semiconductor vacant region, so that the light-emitting steps surround the N-type semiconductor vacant region at intervals in the circumferential direction;

and manufacturing a first electrode on one side of the light-emitting step, which is far away from the substrate, manufacturing a second electrode in the N-type semiconductor vacant area, wherein the plurality of light-emitting steps in the same micro light-emitting diode share one second electrode.

In some possible embodiments, the fabricating a second electrode in the N-type semiconductor vacant region includes:

evaporating a first metal layer on one side of the epitaxial wafer, which is far away from the substrate, and enabling the first metal layer to cover the N-type semiconductor layer in the N-type semiconductor vacant region;

and evaporating a second metal layer on one side of the first metal layer, which is far away from the substrate, so that the second metal layer is positioned in the N-type semiconductor vacant area, and the surface of one side, which is far away from the substrate, of the second metal layer is flush with the surface of one side, which is far away from the light-emitting step, of the first electrode.

In some possible embodiments, before evaporating the second metal layer on the side of the first metal layer away from the substrate, the method for manufacturing a micro light emitting diode further includes:

depositing a protective layer on the surface of at least one side of the epitaxial wafer, which is far away from the substrate, and covering the first metal layer;

and slotting on the protective layer to expose the first metal layer in the N-type semiconductor vacant region.

In some possible embodiments, the fabricating a first electrode on a side of the light emitting step away from the substrate includes:

depositing a current diffusion layer on one side of the light-emitting step away from the substrate;

and evaporating a first metal layer on one side of the epitaxial wafer, which is far away from the substrate, and covering the current diffusion layer with the first metal layer so as to form the first electrode on one side of the current diffusion layer, which is far away from the light-emitting step.

In some possible embodiments, the method for manufacturing a micro light emitting diode further includes:

and manufacturing a light blocking layer at least in the circumferential direction of the light-emitting step and avoiding one side, close to the second electrode, in the light-emitting step.

In some possible embodiments, the etching the epitaxial wafer from the P-type semiconductor layer to the N-type semiconductor layer to obtain a plurality of light-emitting steps and an N-type semiconductor vacant region, and the light-emitting steps are spaced around the circumference of the N-type semiconductor vacant region, including:

etching the epitaxial wafer from the P-type semiconductor layer to the surface of one side, close to the substrate, of the N-type semiconductor layer so as to form a plurality of micro light-emitting diode matrixes on the substrate;

and etching the micro light-emitting diode substrate from the P-type semiconductor layer to the N-type semiconductor layer to obtain a plurality of light-emitting steps and an N-type semiconductor vacant area, so that the light-emitting steps surround the N-type semiconductor vacant area at intervals in the circumferential direction.

In a second aspect, the present application also provides a micro light emitting diode, comprising:

a substrate;

the epitaxial wafer is arranged on one side of the substrate, an N-type semiconductor vacant area and a plurality of light-emitting steps are arranged on one side of the epitaxial wafer, which is far away from the substrate, and the light-emitting steps surround the N-type semiconductor vacant area at intervals in the circumferential direction;

the first electrodes are arranged on one sides, far away from the substrate, of the light-emitting steps in a one-to-one correspondence mode; and

and the second electrode is arranged in the N-type semiconductor vacant area, and the plurality of light-emitting steps in the same micro light-emitting diode share one second electrode.

In some possible embodiments, a side surface of the second electrode away from the substrate is flush with a side surface of the first electrode away from the light-emitting step.

In some possible embodiments, a light blocking layer is further disposed around the light emitting step, and the light blocking layer avoids a side of the light emitting step close to the second electrode.

In a third aspect, the present application further provides a display panel including the micro light emitting diode provided in the present application.

In some possible embodiments, the display panel further includes a driving board;

and the surface of one side of the plurality of first electrodes, which is far away from the substrate, and the surface of one side of the second electrodes, which is far away from the substrate, are both bonded with the driving board through conductive adhesive.

The beneficial effect of this application is: the application provides a micro light-emitting diode, a display panel and a preparation method, wherein the preparation method of the micro light-emitting diode is used for preparing the micro light-emitting diode. By the method for manufacturing the micro light-emitting diode, a plurality of light-emitting steps can be obtained in the same micro light-emitting diode, and the plurality of light-emitting steps can share one second electrode. Therefore, in the transfer process of the micro light-emitting diode, the transfer times of the micro light-emitting diode can be reduced, and the transfer efficiency is improved. Simultaneously, compare in the little emitting diode who only includes a pixel, this application can make single little emitting diode have relatively great volume under the unchangeable circumstances of single pixel volume, and then can reduce the degree of difficulty that little emitting diode shifted, further promotes transfer efficiency. In addition, part of pixel points in the same micro light-emitting diode can be used as standby pixels, and the maintenance cost of the corresponding display panel can be reduced in subsequent use.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 shows a schematic flow diagram of a method for fabricating a micro-LED in some embodiments;

FIG. 2 shows a schematic diagram illustrating the structure of an epitaxial wafer and a substrate in some embodiments;

FIG. 3 illustrates a flow chart for fabricating a light emitting step and an N-type semiconductor vacant region in some embodiments;

FIG. 4 illustrates a flow diagram for etching a micro LED body in some embodiments;

FIG. 5 shows a schematic structural diagram of a micro light emitting diode matrix in some embodiments;

FIG. 6 shows a schematic structural diagram of a micro LED body after etching in some embodiments;

FIG. 7 is a schematic diagram illustrating a top view of a micro LED substrate after etching in some embodiments;

FIG. 8 is a schematic diagram showing a top view of a micro LED substrate after etching in further embodiments;

FIG. 9 shows a schematic flow chart of the preparation of the first and second electrodes in some embodiments;

FIG. 10 shows a schematic view of the structure of the light emitting steps after deposition of the current spreading layer in some embodiments;

FIG. 11 is a schematic diagram of the micro-LED substrate after fabrication of a first metal layer in some embodiments;

FIG. 12 is a schematic diagram of the structure of the micro light emitting diode substrate after the protective layer is prepared in some embodiments;

FIG. 13 illustrates a schematic diagram of the structure after the protective layer has been grooved in some embodiments;

FIG. 14 is a schematic diagram of the structure of the micro-LED substrate after fabrication of the second metal layer in some embodiments;

FIG. 15 shows a schematic view of a micro LED structure in some embodiments;

FIG. 16 illustrates a schematic top view of a micro LED in some embodiments;

FIG. 17 is a schematic top view of a micro LED in further embodiments;

fig. 18 is a schematic diagram showing the structure of the micro light emitting diode connected to the driving board in some embodiments.

Description of the main element symbols:

1000-micro light emitting diode; 1100-micro light emitting diode matrix; 100-an epitaxial wafer; a 101-N type semiconductor layer; 102-a light emitting layer; 103-P type semiconductor layer; 111-a light emitting step; 112-N type semiconductor dummy regions; 200-a substrate; 310-a first electrode; 320-a second electrode; 400-current spreading layer; 510-a first metal layer; 520-a second metal layer; 600-a protective layer; 611-a first slot; 612-a second slot; 700-light blocking layer; 2000-drive plate.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the terms "central," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

The embodiment provides a method for manufacturing a micro light-emitting diode, which can be used for processing and manufacturing the micro light-emitting diode 1000 comprising a plurality of pixel points. Therefore, in the subsequent transfer process of the micro light-emitting diodes, the transfer times and difficulty of the micro light-emitting diodes 1000 can be reduced, standby pixel points can be provided for the display panel, and the cost and difficulty of later maintenance of the display panel are reduced.

As shown in fig. 1 and 2, the method for preparing a micro light emitting diode may include:

s100, an N-type semiconductor layer 101, a light emitting layer 102 and a P-type semiconductor layer 103 are sequentially formed on a substrate 200 to form an epitaxial wafer 100 on the substrate 200.

The substrate 200 may be used as a carrier for manufacturing the micro light emitting diode 1000, and other structures of the micro light emitting diode 1000 may be manufactured on the substrate 200. In one embodiment, substrate 200 may be sapphire (Al) ₂ O ₃ ) A substrate, a silicon (Si) substrate, a silicon carbide (SiC) substrate, or the like.

In an embodiment, the N-type semiconductor layer 101, the light emitting layer 102, and the P-type semiconductor layer 103 may be sequentially grown on one surface of the substrate 200 to obtain the epitaxial wafer 100. In some embodiments, the N-type semiconductor layer 101 may be an N-type gallium nitride (N-GaN) layer, and the light-emitting layer 102 may be a Multiple Quantum Well (MQWs) light-emitting layer. The P-type semiconductor layer 103 may be a P-type gallium nitride (P-GaN) layer.

It is understood that the N-type semiconductor layer 101 may be used to provide electrons and the P-type semiconductor layer 103 may be used to provide electron holes. Under the action of the current, both the excess electrons in the N-type semiconductor layer 101 and the excess electron holes in the P-type semiconductor layer 103 can move to the light-emitting layer 102, and the excess electrons in the N-type semiconductor layer 101 and the excess electron holes in the P-type semiconductor layer 103 can recombine in the light-emitting layer 102 to generate photons to emit light, so that the light-emitting effect of the micro light-emitting diode 1000 can be realized.

In an embodiment, different material layers in the epitaxial wafer 100 may be grown by different epitaxial growth methods, respectively. Illustratively, the growth of the different material layers in the epitaxial wafer 100 may be performed, for example, by a vapor phase epitaxial growth method, a liquid phase epitaxial growth method, a molecular beam epitaxial growth method, or the like, respectively.

S200, the epitaxial wafer 100 is etched from the P-type semiconductor layer 103 to the N-type semiconductor layer 101 to obtain a plurality of light emitting steps 111 and an N-type semiconductor vacant region 112, such that the plurality of light emitting steps 111 surround the N-type semiconductor vacant region 112 at intervals.

As shown in fig. 3, in some embodiments, step S200 may include:

s210, etching the epitaxial wafer 100 from the P-type semiconductor layer 103 to the surface of the N-type semiconductor layer 101 close to one side of the substrate 200, so as to form a plurality of micro light-emitting diode matrixes 1100 on the substrate 200.

As shown in fig. 5, in some embodiments, the epitaxial wafer 100 may be etched and divided to obtain a plurality of micro-led bodies 1100. It is understood that a micro-led substrate 1100 may be used to form a micro-led 1000. Accordingly, a plurality of micro-leds 1000 may be simultaneously fabricated on the substrate 200.

Of course, in other embodiments, it is not excluded to fabricate one micro-led 1000 on the substrate 200. Accordingly, the operation of step S210 may be omitted.

As shown in fig. 4, in some embodiments, step S210 may include:

and S211, depositing a mask layer on the surface of the epitaxial wafer 100 far away from the substrate 200.

The mask layer may be formed of, but not limited to, photoresist, silicon dioxide (SiO) ₂ ) And metal or insulating layers. In an embodiment, the mask layer may be made of photoresist.

S212, the mask layer is patterned to determine an etched region and a non-etched region of the epitaxial wafer 100.

Specifically, a specific region of the mask layer may be exposed according to a patterning design, and may be irradiated with ultraviolet rays or the like, for example. The exposed mask layer in the specific region is dissolved by a solution such as a developing solution to expose the epitaxial wafer 100 in the specific region. It is understood that the particular region may correspond to an etched region in the epitaxial wafer 100.

And S213, etching the epitaxial wafer 100 from the P-type semiconductor layer 103 to the surface of the N-type semiconductor layer 101 close to the substrate 200 in the etching area.

Illustratively, the epitaxial wafer 100 may be etched by an Inductively Coupled Plasma (ICP) etcher to divide the epitaxial wafer 100 into a plurality of micro led substrates 1100.

Specifically, the product obtained in step S212 may be placed in an inductively coupled plasma etcher and passed through chlorine (Cl) ₂ ) Boron trichloride (BCl) ₃ ) And argon (Ar) to etch the etched area of the epitaxial wafer 100 to obtain a plurality of micro light emitting diode bodies 1100.

And S214, removing the mask layer of the non-etching area.

Illustratively, the mask layer in the non-etching area can be removed by a plasma dry photoresist stripping process. Then, the mask layer is cleaned by acetone and isopropanol for 5min respectively to remove the residual mask layer, and then the mask layer can be cleaned by deionized water. After the cleaning is finished, the glass can be dried by nitrogen.

S220, the micro led substrate 1100 is etched from the P-type semiconductor layer 103 to the N-type semiconductor layer 101 to obtain a plurality of light emitting steps 111 and an N-type semiconductor vacant region 112, wherein the plurality of light emitting steps 111 surround the N-type semiconductor vacant region 112 at intervals.

Specifically, as shown in fig. 6, the epitaxial wafer 100 in the micro led base 1100 may be etched, and a plurality of light emitting steps 111 and an N-type semiconductor vacant region 112 may be formed on a side of the same micro led base 1100 away from the substrate 200. In one embodiment, the light emitting steps 111 may be uniformly spaced around the circumference of the N-type semiconductor vacant region 112. It will be appreciated that a light emitting step 111 may be used as a pixel. In addition, the light emitting step 111 may be provided in a shape of a circle, a square, a sector, an ellipse, a rectangle, etc., as needed, and is not particularly limited herein.

As shown in fig. 7, two light emitting steps 111 may be etched on the same micro led substrate 1100, and both of the two light emitting steps 111 may be a square step structure. The two light-emitting steps 111 can be disposed on two opposite sides of the N-type semiconductor vacant areas 112.

In other embodiments, as shown in fig. 8, four light emitting steps 111 can be etched on the same micro led substrate 1100, and the four light emitting steps 111 can be a fan-shaped step structure. The four light emitting steps 111 may be uniformly spaced apart and disposed in the circumferential direction of the N-type semiconductor vacant region 112.

Of course, in other embodiments, it is not excluded to arrange the plurality of light emitting steps 111 in a non-uniform state.

In some embodiments, the micro light emitting diode body 1100 may be etched by a photolithography process to obtain a plurality of light emitting steps 111 and an N-type semiconductor vacant region 112. The specific operation process of the photolithography process may refer to the specific operation process of step S210, and is not described herein again.

In other embodiments, the mask layer in the non-etching region in step S210 may be reserved in step S220, and after the micro light emitting diode substrate 1100 is etched, the remaining mask layer is removed.

It can be understood that during the etching process of the micro light emitting diode body 1100, the N-type semiconductor layer 101 is not etched through, i.e., the position corresponding to the N-type semiconductor vacant region 112, and the substrate 200 further includes a certain thickness of the N-type semiconductor layer 101.

In an embodiment, the plurality of micro light emitting diode bodies 1100 on the substrate 200 may be etched and the subsequent steps performed simultaneously.

And S300, manufacturing a first electrode 310 on the side of the light-emitting step 111 far away from the substrate 200, and manufacturing a second electrode 320 in the N-type semiconductor vacant region 112.

As shown in fig. 9 to 14, in some embodiments, the step S300 may specifically include:

and S310, depositing a current diffusion layer 400 on the side, away from the substrate 200, of the light-emitting step 111.

As shown in fig. 10, in particular, Indium Tin Oxide (ITO), zinc Oxide (ZnO), or a plurality of metal layers, etc. may be deposited on the surface of the light emitting step 111 far from the substrate 200 by a magnetron sputtering method to form the current diffusion layer 400. The multi-layer metal layer includes, but is not limited to, Ti (titanium), Al (aluminum), Au (gold), Pt (platinum), Ni (nickel), etc.

In some embodiments, after the current spreading layer 400 is deposited, a rapid thermal annealing process may be performed thereon, which may improve the ohmic contact performance between the current spreading layer 400 and the P-type semiconductor layer 103 to ensure the transmission quality of the current. For example, the micro light emitting diode substrate 1100 with the current spreading layer 400 deposited thereon may be first placed in nitrogen (N) at 550 deg.C to 570 deg.C ₂ ) Treating for 5min in the environment, and then placing in nitrogen (N) ₂ ) With oxygen (O) ₂ ) The ratio is 4: 1 for 5min, and then naturally cooling to 70-80 ℃.

S320, evaporating a first metal layer 510 on a side of the epitaxial wafer 100 away from the substrate 200.

Specifically, as shown in fig. 11, the first metal layer 510 may cover the current diffusion layer 400 and the N-type semiconductor layer 101 located in the N-type semiconductor vacant region 112. Accordingly, the first electrode 310 may be formed on a side of the current diffusion layer 400 away from the light emitting step 111, i.e., the first electrode 310 may refer to a region of the first metal layer 510 on the surface of the current diffusion layer 400.

In an embodiment, a titanium/aluminum/titanium/gold (Ti/Al/Ti/Au) metal layer may be sequentially deposited on the surface of the N-type semiconductor layer 101 and the surface of the current diffusion layer 400 by an ion beam evaporation method to obtain the first metal layer 510.

In other embodiments, the first metal layer 510 may also be made of a nickel/iron/platinum/palladium (Ni/Fe/Pt/Pd) metal layer, or other conductive material.

And S330, depositing a protective layer 600 on at least one surface of the epitaxial wafer 100 far away from the substrate 200.

As shown in fig. 12, 16, and 17, in some embodiments, the protective layer 600 may cover both the circumferential sidewall of the light emitting step 111 and the first metal layer 510. Therefore, the protection layer 600 can protect other structural layers in the micro light emitting diode 1000, and prevent impurity atoms from being adsorbed on the surface of the micro light emitting diode 1000 to cause pollution, thereby ensuring the light emitting effect of the micro light emitting diode 1000, and simultaneously, realizing the short circuit prevention protection of the micro light emitting diode 1000.

In some embodiments, the protective layer 600 may be deposited on the side of the epitaxial wafer 100 remote from the substrate 200 by a Plasma Enhanced Chemical Vapor Deposition (PECVD) method. Wherein the protection layer 600 may be made of silicon oxide (SiO) ₂ Silicon nitride (Si) ₃ N ₄ ) Or aluminum oxide (Al) ₂ O ₃ ) And the like.

In other embodiments, when the same micro led substrate 1100 includes three or more light-emitting steps 111, the opposite sidewall positions of two adjacent light-emitting steps 111 do not need to be covered with the protection layer 600.

S340, a trench is opened on the protection layer 600 to expose the first electrode 310 and the first metal layer 510 in the N-type semiconductor vacant region 112.

Specifically, as shown in fig. 13, two slots, namely a first slot 611 and a second slot 612, may be formed in the protection layer 600. The first slot 611 is opened at a position corresponding to the first electrode 310, so that a part of the structure of the first electrode 310 can be exposed through the first slot 611, so that the micro light emitting diode 1000 can be connected to the driving board 2000 by the first electrode 310 in use. The second slot 612 may be opened corresponding to the first metal layer 510 at the location of the N-type semiconductor vacant region 112, so as to expose a portion of the first metal layer 510 at the location of the N-type semiconductor vacant region 112.

In some embodiments, the protective layer 600 may be grooved by a photolithography process, and the specific operation process of the photolithography process may refer to step S210, which is not described herein again.

S350, evaporating a second metal layer 520 on a side of the first metal layer 510 away from the substrate 200, and positioning the second metal layer 520 in the N-type semiconductor vacant region 112.

In one embodiment, as shown in fig. 14, the second metal layer 520 can be evaporated by ion beam evaporation in the exposed region of the first metal layer 510 with respect to the second slot 612. The second metal layer 520 may be made of a titanium/aluminum/titanium/gold (Ti/Al/Ti/Au) metal layer, a nickel/iron/platinum/palladium (Ni/Fe/Pt/Pd) metal layer, or other types of conductive metal layers. It is understood that the second metal layer 520 can be in electrical communication with the first metal layer 510 to achieve electrical communication.

In one embodiment, the second metal layer 520 and the first metal layer 510 at the location of the N-type semiconductor vacant region 112 may form the second electrode 320 together. It is understood that a plurality of light emitting steps 111 in the same micro light emitting diode 1000 may share the same second electrode 320. Therefore, the number of the second electrodes 320 in the micro light emitting diode 1000 can be reduced, thereby saving space and reducing material consumption.

In some embodiments, a surface of the second metal layer 520 on a side away from the substrate 200 may be flush with a surface of the first electrode 310 on a side away from the light emitting step 111. When the micro light emitting diode 1000 is applied to a structure such as a display panel, the micro light emitting diode 1000 may be conveniently connected to the corresponding driving board 2000 by Anisotropic Conductive Film (ACF).

As shown in fig. 1, 15 to 17, in some embodiments, the method for manufacturing a micro light emitting diode may further include:

s400, a light blocking layer 700 is formed at least in the circumferential direction of the light emitting step 111 and is kept away from the side of the light emitting step 111 close to the second electrode 320.

It can be understood that, when the second metal layer 520 is fabricated, the second metal layer 520 may fill the N-type semiconductor vacant region 112, that is, the peripheral side of the second metal layer 520 may contact the protection layer 600 on the corresponding sidewall of the light-emitting step 111, so as to ensure the stability between the structural members. Accordingly, a sidewall of the light emitting step 111 opposite to the second electrode 320 may not be provided with the light blocking layer 700. In some embodiments, the light blocking layer 700 may be selected from black glue and the like.

In an embodiment, the light blocking layer 700 may be formed by spraying black glue on the circumferential side wall of the light emitting step 111 through a spraying process, and curing the black glue through photo-curing or thermal curing. When three or more light-emitting steps 111 are provided, black glue may be directly injected into the gap between two adjacent light-emitting steps 111 and cured to form the light-blocking layer 700 at the corresponding position.

As shown in fig. 16, in some embodiments, when the light-blocking layer 700 is formed on the peripheral side of the light-emitting step 111, the light-blocking layer 700 may be formed on the relatively exposed portion of the peripheral side of the second electrode 320, and the relatively exposed portion of the peripheral side of the second electrode 320 may also be protected.

It is understood that the light blocking layer 700 can be used to block the lateral light of the whole micro led 1000, so as to avoid the optical crosstalk between the adjacent micro leds 1000. Meanwhile, the light blocking layer 700 may also block the lateral light emitting of a single light emitting step 111, so as to prevent the optical crosstalk between two adjacent light emitting steps 111 in the same micro light emitting diode 1000. On one hand, the brightness of a single light-emitting step 111 can be improved, and on the other hand, the contrast of a corresponding display panel can be improved, and the display effect is improved.

In some embodiments, after the light blocking layer 700 is prepared, the substrate 200 may be further diced to separate the plurality of micro light emitting diodes 1000 on the substrate 200 to form individual units.

In the embodiment, the light emitting steps 111 are fabricated on the epitaxial wafer 100 of the same micro light emitting diode 1000, even though the same micro light emitting diode 1000 may include a plurality of pixels at the same time, thereby improving the utilization rate of the epitaxial wafer 100 and reducing the generation of waste materials. When the micro light emitting diode 1000 is applied to corresponding devices such as a display panel, transfer of a plurality of pixel points can be achieved simultaneously, transfer times of the micro light emitting diode 1000 can be reduced, and transfer efficiency is improved.

In addition, compared with the micro led 1000 including only one pixel, the embodiment can ensure that the volume of a single pixel meets the requirement, and at the same time, the manufactured micro led 1000 has a larger volume. Therefore, the actions such as grabbing in the micro light-emitting diode 1000 transferring process can be facilitated, the transferring difficulty of the micro light-emitting diode 1000 is reduced, the transferring efficiency can be further improved, and the processing efficiency of the display panel is improved.

When the micro led 1000 is used, in the same micro led 1000, of course, some pixel points may be used as spare pixel points. When another part of the pixel points are damaged, the standby pixel points can be started without replacing the micro light-emitting diode 1000, so that the later maintenance difficulty and the cost of the corresponding display panel can be reduced.

It is understood that in the same micro light emitting diode 1000, the on state between the second electrode 320 and the plurality of first electrodes 310 may be controlled by the driving board 2000 as needed. Specifically, in the same micro led 1000, the second electrode 320 can be simultaneously and respectively connected to each of the first electrodes 310, and drive each of the light-emitting steps 111 to emit light. Of course, in the same micro led 1000, the second electrode 320 may also be connected to a portion of the first electrodes 310, and drive the light-emitting steps 111 connected to the portion of the first electrodes 310 to emit light, and another portion of the light-emitting steps 111 may be in a non-light-emitting state as a spare pixel.

The embodiment also provides a micro light-emitting diode 1000 which can be processed by the micro light-emitting diode preparation method provided in the embodiment.

As shown in fig. 14 to 17, the micro light emitting diode 1000 may include a substrate 200, an epitaxial wafer 100, a first electrode 310, and a second electrode 320.

The epitaxial wafer 100 may include an N-type semiconductor layer 101, a light emitting layer 102, and a P-type semiconductor layer 103, which are sequentially stacked. The epitaxial wafer 100 may be disposed on one side of the substrate 200, wherein the N-type semiconductor layer 101 may be disposed near one side of the substrate 200. The side of the epitaxial wafer 100 away from the substrate 200 may be provided with a plurality of light emitting steps 111 and an N-type semiconductor vacant region 112, and the plurality of light emitting steps 111 may be disposed around the circumference of the N-type semiconductor vacant region 112 at intervals. In an embodiment, the light emitting step 111 may be configured in a shape of a circle, a square, a sector, an ellipse, a rectangle, etc., as needed, and is not particularly limited herein.

As shown in fig. 7 and 16, for example, the side of the epitaxial wafer 100 away from the substrate 200 may include two light emitting steps 111, and both of the two light emitting steps 111 may be a square step structure. The two light emitting steps 111 can be disposed on two opposite sides of the N-type semiconductor vacant region 112.

As shown in fig. 8 and 17, in other embodiments, the side of the epitaxial wafer 100 away from the substrate 200 may include four light emitting steps 111, and the four light emitting steps 111 may be a fan-shaped step structure. The four light emitting steps 111 may be uniformly spaced apart and disposed in the circumferential direction of the N-type semiconductor vacant region 112.

As shown in fig. 14 to 17, in the embodiment, the first electrode 310 may also be provided in plurality, and the number of the first electrodes 310 may be equal to the number of the light emitting steps 111. The first electrodes 310 are disposed on one side of the light emitting steps 111 away from the substrate 200 in a one-to-one correspondence manner, and the first electrodes 310 are electrically connected to the P-type semiconductor layer 103 in the light emitting steps 111 where the first electrodes 310 are located.

In some embodiments, a current diffusion layer 400 may be further disposed between the first electrode 310 and the light emitting step 111, and the current diffusion layer 400 may be electrically connected between the P-type semiconductor layer 103 and the first electrode 310.

The second electrode 320 may be disposed in the N-type semiconductor vacant region 112, and the second electrode 320 is electrically connected to the N-type semiconductor layer 101 located in the N-type semiconductor vacant region 112. In some embodiments, a surface of the second electrode 320 on a side away from the substrate 200 may be flush with a surface of the first electrode 310 on a side away from the light emitting step 111. In an embodiment, the light emitting steps 111 in the same micro light emitting diode 1000 may share the same second electrode 320. Therefore, the number of the second electrodes 320 in the micro light emitting diode 1000 can be reduced, thereby saving space and reducing material consumption.

As shown in fig. 14 and 15, in some embodiments, the micro light emitting diode 1000 further includes a protective layer 600, and the protective layer 600 may be attached to a circumferential sidewall of the light emitting step 111 and a side of the light emitting step 111 away from the substrate 200. In addition, the passivation layer 600 is further formed with a first slot 611, the first slot 611 can be opposite to the first electrode 310, and a portion of the structure of the first electrode 310 can be exposed through the first slot 611.

As shown in fig. 15, further, the micro light emitting diode 1000 further includes a light blocking layer 700, and the light blocking layer 700 may be disposed around the light emitting step 111 and avoid a sidewall of the light emitting step 111 close to the second electrode 320. It is understood that the light blocking layer 700 may be located at a side of the protective layer 600 away from the light emitting step 111. In some embodiments, the light blocking layer 700 may be made of black glue.

In use, the light blocking layer 700 can be used to block the light emitting steps 111 from emitting light laterally, so as to avoid the problem of optical crosstalk between adjacent micro light emitting diodes 1000. Meanwhile, the light blocking layer 700 may also prevent optical crosstalk between two adjacent light emitting steps 111 in the same micro light emitting diode 1000.

As shown in fig. 18, a display panel is further provided in the embodiment, and may include a driving board 2000 and micro light emitting diodes 1000 provided in the embodiment.

The first electrode 310 and the second electrode 320 in the micro light emitting diode 1000 may be connected to the driving board 2000 through an anisotropic conductive adhesive. On the one hand, the mechanical connection between the micro light emitting diode 1000 and the driving board 2000 can be realized, i.e. the micro light emitting diode 1000 is fixed on the driving board 2000. On the other hand, the electrical connection between the micro light emitting diode 1000 and the driving board 2000 may also be achieved.

Of course, in other embodiments, other types of conductive paste, such as silver paste, may be used to connect the micro light emitting diode 1000 and the driving board 2000.

In the embodiment, the connection between the micro light emitting diode 1000 and the driving board 2000 is realized through the conductive adhesive, so that the problem of electrode short circuit caused by the traditional metal reflow soldering process can be avoided. Therefore, the product yield can be improved, and meanwhile, the loss of the micro light-emitting diode 1000 can be reduced, and the cost is reduced.

In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are exemplary and should not be construed as limiting the present application and that changes, modifications, substitutions and alterations in the above embodiments may be made by those of ordinary skill in the art within the scope of the present application.

Claims

1. A method for preparing a micro light-emitting diode is characterized by comprising the following steps:

2. The method of claim 1, wherein the fabricating a second electrode in the N-type semiconductor vacant area comprises:

3. A method according to claim 2, wherein before the step of evaporating a second metal layer on the side of the first metal layer away from the substrate, the method further comprises:

4. The method of claim 1, wherein the forming a first electrode on a side of the light-emitting step away from the substrate comprises:

5. A method of fabricating a micro-led according to claim 1, further comprising:

6. The method of claim 1, wherein the etching the epitaxial wafer from the P-type semiconductor layer to the N-type semiconductor layer to obtain a plurality of light emitting steps and an N-type semiconductor vacant region, and the step of forming the light emitting steps to surround the N-type semiconductor vacant region at intervals comprises:

7. A micro light emitting diode, comprising:

a substrate;

8. A micro light-emitting diode according to claim 7, wherein a surface of a side of the second electrode remote from the substrate is flush with a surface of a side of the first electrode remote from the light-emitting step.

9. The micro light-emitting diode of claim 7 or 8, wherein a light blocking layer is further disposed around the light-emitting step, and the light blocking layer avoids a side of the light-emitting step close to the second electrode.

10. A display panel comprising the micro light emitting diode according to claims 7 to 9.

11. The display panel according to claim 10, further comprising a driving board;