Semiconductor light-emitting element for display pixels, and display device comprising same

Abstract

A semiconductor light-emitting element for display pixels, according to an embodiment of the present invention, comprises: a light-emitting structure including a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer; and a reflective layer disposed under the light-emitting structure, wherein the upper surface of the reflective layer can be flat and the lower surface thereof can have roughness.

Description

Semiconductor light-emitting element for display pixels and display device including the same

[0001] The present invention relates to a semiconductor light-emitting element for a display pixel and a display device including the same.

[0002] Large-area displays include liquid crystal displays (LCDs), OLED displays, and micro-LED displays.

[0003] A micro-LED display is a display that uses micro-LEDs, which are semiconductor light-emitting elements with a diameter or cross-sectional area of ​​100㎛ or less, as display elements.

[0004] Micro-LED displays use semiconductor light-emitting diodes (micro-LEDs) as display elements, so they have superior performance in many characteristics, including contrast ratio, response speed, color reproducibility, viewing angle, brightness, resolution, lifespan, luminous efficiency, and brightness.

[0005] In particular, micro-LED displays have the advantage of being able to freely adjust the size and resolution by separating and combining the screen in a modular manner, and of being able to implement a flexible display.

[0006]

[0007] However, large-scale micro-LED displays require millions or more micro-LEDs, which poses a technical challenge in quickly and accurately transferring micro-LEDs to the display panel.

[0008] Recently developed transfer technologies include the pick and place process, the laser lift-off method, and the self-assembly method.

[0009] Among these, the self-assembly method is advantageous for implementing large-screen display devices, as it is a method in which semiconductor light-emitting elements find their own assembly positions within a fluid.

[0010] Recently, U.S. Patent No. 9,825,202 presented a micro-LED structure suitable for self-assembly, but research on the technology for manufacturing displays through self-assembly of micro-LEDs is still insufficient.

[0011] In particular, in the case of rapidly transferring millions or more semiconductor light-emitting elements to a large display in the prior art, there is a technical problem that although the transfer speed can be improved, the transfer error rate can increase, resulting in a lower transfer yield.

[0012] Meanwhile, when the semiconductor light-emitting device being internally studied is assembled and transferred to a panel substrate, the adhesive strength between the semiconductor light-emitting device and the assembled substrate reduces the pickup rate of the semiconductor light-emitting device, resulting in a decrease in the transfer yield. Consequently, the pressure applied to the semiconductor light-emitting device to increase the adhesive strength between the stamp and the semiconductor light-emitting device increases, potentially damaging the semiconductor light-emitting device and leading to a decrease in the transfer yield.

[0013] One of the technical challenges of the embodiment is to improve the transfer yield of semiconductor light-emitting devices.

[0014] In addition, one of the technical challenges of the embodiment is to form a rough structure on the back of a semiconductor light-emitting device without a separate additional process.

[0015] In addition, one of the technical challenges of the embodiment is to control the reflectivity and pickup rate of the semiconductor light-emitting device by controlling the thickness of the reflective layer.

[0016] The technical problems of the embodiment are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0017] A semiconductor light-emitting device for a display pixel according to an embodiment includes a light-emitting structure having a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; and a reflective layer disposed under the light-emitting structure; wherein an upper surface of the reflective layer may have a flat shape and a lower surface may have a roughness shape.

[0018] Additionally, in an embodiment, the reflective layer may include a first reflective layer and a first region.

[0019] Additionally, in an embodiment, the reflective layer may include at least one of an alloy made of Au, Ag, Ge, or a combination thereof.

[0020] Additionally, in the embodiment, the first region is in contact with the lower surface of the first conductive semiconductor light-emitting element and can penetrate the first reflective layer.

[0021] In addition, the embodiment further includes a magnetic layer disposed under the reflective layer,

[0022] The surface of the magnetic layer may correspond to the shape of the lower surface of the reflective layer.

[0023] Additionally, in the embodiment, the area of ​​the lower surface of the first region may be larger than the area of ​​the upper surface.

[0024] Additionally, in the embodiment, the lower surface of the first conductive semiconductor layer may have a larger area in contact with the first reflective layer than an area in contact with the first region.

[0025] Additionally, in the embodiment, the first region includes a plurality of

[0026] At least one of the plurality of first regions may have a reverse tapered shape.

[0027] Additionally, in embodiments, the magnetic layer may not include Ge.

[0028]

[0029] In addition, a display device including a semiconductor light emitting element according to another embodiment comprises: a substrate;

[0030] A lower wiring disposed on the substrate; an adhesive layer disposed on the lower wiring; a semiconductor light-emitting element disposed on the adhesive layer; and a first panel wiring electrically connecting the semiconductor light-emitting element and the lower wiring, wherein the semiconductor light-emitting element may include a semiconductor light-emitting element for a display pixel according to any one of claims 1 to 9.

[0031] A semiconductor light-emitting element for a display pixel according to an embodiment has a technical effect that can improve a pickup rate during a transfer process using a stamp.

[0032] For example, in an embodiment, a rough structure is formed on the back of a semiconductor light-emitting element, thereby reducing the contact area with the assembly substrate and improving the pickup rate.

[0033] In addition, the embodiment has a technical effect of being able to form a rough structure on the back of a semiconductor light-emitting device without a separate additional process.

[0034] For example, an embodiment can form a rough structure on the back surface by utilizing the agglomeration phenomenon of AuAg and Ge.

[0035] In addition, the embodiment has a technical effect of being able to control the reflectivity and pickup rate of a semiconductor light-emitting device.

[0036] For example, the embodiment can control the reflectivity and pickup rate of the semiconductor light-emitting element by controlling the thickness of the first and second reflective layers.

[0037] The technical effects of the embodiments are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0038] Figure 1 is an exemplary diagram of a living room of a house in which a display device according to an embodiment is placed.

[0039] Figure 2 is an enlarged view of the first panel area in the display device of Figure 1.

[0040] Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0041] Fig. 4 is an exemplary diagram showing a light-emitting element according to an embodiment being assembled on a substrate by a self-assembly method.

[0042] Fig. 5 is a cross-sectional view of a semiconductor light-emitting element for a display pixel according to an embodiment.

[0043] Figure 6 is a drawing showing area B of Figure 5 in detail.

[0044] Figure 7 is a drawing showing part of the manufacturing process of the embodiment.

[0045] Figures 8a to 8c are drawings showing a transfer process of a semiconductor light-emitting device according to an embodiment.

[0046] Hereinafter, embodiments disclosed in the present specification will be described in detail with reference to the attached drawings. The suffixes "module" and "part" used in the following description for components are given or used interchangeably for the sake of ease of writing the specification, and do not in themselves have distinct meanings or roles. In addition, the attached drawings are intended to facilitate easy understanding of the embodiments disclosed in the present specification, and the technical ideas disclosed in the present specification are not limited by the attached drawings. In addition, when an element such as a layer, region, or substrate is referred to as existing "on" another element, this includes that it may be directly on the other element, or that other intermediate elements may exist therebetween.

[0047] The display devices described in this specification may include digital TVs, mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, tablet PCs, Ultra-Books, desktop computers, and the like. However, the configuration according to the embodiments described in this specification may also be applied to devices capable of displaying, even if they are new product types developed in the future.

[0048]

[0049] A light-emitting element and a display device including the same according to the following embodiment are described.

[0050] FIG. 1 illustrates a living room of a house in which a display device (100) according to an embodiment is placed.

[0051] The display device (100) of the embodiment can display the status of various electronic products such as a washing machine (101), a robot vacuum cleaner (102), and an air purifier (103), and can communicate with each electronic product based on IOT and control each electronic product based on user setting data.

[0052] A display device (100) according to an embodiment may include a flexible display manufactured on a thin and flexible substrate. The flexible display can be bent or rolled like paper while maintaining the characteristics of a conventional flat panel display.

[0053] In a flexible display, visual information can be realized by independently controlling the emission of unit pixels arranged in a matrix form. A unit pixel refers to the smallest unit for realizing a single color. The unit pixels of a flexible display can be realized by light-emitting elements. In an embodiment, the light-emitting elements may be micro-LEDs or nano-LEDs, but are not limited thereto.

[0054]

[0055] Figure 2 is an enlarged view of the first panel area (A1) in the display device of Figure 1.

[0056] According to FIG. 2, the display device (100) of the embodiment can be manufactured by mechanically and electrically connecting a plurality of panel areas, such as the first panel area (A1), through tiling.

[0057] The first panel area (A1) may include a plurality of light-emitting elements (150) arranged for each unit pixel (PX in FIG. 2).

[0058] For example, a unit pixel (PX) may include a first sub-pixel (PX1), a second sub-pixel (PX2), and a third sub-pixel (PX3). For example, a plurality of red light-emitting elements (150R) may be arranged in the first sub-pixel (PX1), a plurality of green light-emitting elements (150G) may be arranged in the second sub-pixel (PX2), and a plurality of blue light-emitting elements (150B) may be arranged in the third sub-pixel (PX3). The unit pixel (PX) may further include a fourth sub-pixel in which no light-emitting element is arranged, but this is not limited thereto. Meanwhile, the light-emitting element (150) may be a semiconductor light-emitting element.

[0059]

[0060] Next, Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0061] Referring to FIG. 3, the display device (100) of the embodiment may include a substrate (200), assembly wiring (201, 202), a first insulating layer (211a), a second insulating layer (211b), a third insulating layer (206), and a plurality of light-emitting elements (150).

[0062] The assembly wiring may include a first assembly wiring (201) and a second assembly wiring (202) that are spaced apart from each other. The first assembly wiring (201) and the second assembly wiring (202) may be provided to generate a dielectrophoretic force for assembling the light emitting element (150). In addition, the first assembly wiring (201) and the second assembly wiring (202) may be electrically connected to electrodes of the light emitting element to function as electrodes of the display panel.

[0063] The assembly wiring (201, 202) may be formed of a light-transmitting electrode (ITO) or may include a metal material with excellent electrical conductivity. For example, the assembly wiring (201, 202) may be formed of at least one of titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), tungsten (W), molybdenum (Mo), or an alloy thereof.

[0064] A first insulating layer (211a) may be disposed between the first assembly wiring (201) and the second assembly wiring (202), and a second insulating layer (211b) may be disposed on the first assembly wiring (201) and the second assembly wiring (202). The first insulating layer (211a) and the second insulating layer (211b) may be an oxide film, a nitride film, or the like, but are not limited thereto.

[0065]

[0066] The light-emitting element (150) may include a red light-emitting element (150), a green light-emitting element (150G), and a blue light-emitting element (150B0) to form a unit pixel (sub-pixel), but is not limited thereto, and may also include a red phosphor and a green phosphor to implement red and green, respectively.

[0067] The substrate (200) may be formed of glass or polyimide. In addition, the substrate (200) may include a flexible material such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET). In addition, the substrate (200) may be a transparent material, but is not limited thereto.

[0068] The third insulating layer (206) may include an insulating and flexible material such as polyimide, PEN, PET, etc., and may be formed integrally with the substrate (200) to form a single substrate.

[0069] The third insulating layer (206) may be a conductive adhesive layer having adhesive properties and conductivity, and the conductive adhesive layer may be flexible to enable a flexible function of the display device. For example, the third insulating layer (206) may be a conductive adhesive layer such as an anisotropic conductive film (ACF) or an anisotropic conductive medium, a solution containing conductive particles, etc. The conductive adhesive layer may be a layer that is electrically conductive in a direction vertical to the thickness, but electrically insulating in a direction horizontal to the thickness.

[0070] The third insulating layer (206) may include an assembly hole (203) into which a light-emitting element (150) is inserted. Therefore, during self-assembly, the light-emitting element (150) can be easily inserted into the assembly hole (203) of the third insulating layer (206). The assembly hole (203) may be referred to as an insertion hole, a fixing hole, an alignment hole, or the like.

[0071] The gap between the assembly wiring (201, 202) is formed to be smaller than the width of the light emitting element (150) and the width of the assembly hole (203), so that the assembly position of the light emitting element (150) can be fixed more precisely using an electric field.

[0072] A third insulating layer (206) is formed on the assembly wiring (201, 202) to protect the assembly wiring (201, 202) from the fluid (1200) and prevent leakage of current flowing in the assembly wiring (201, 202). The third insulating layer (206) may be formed as a single layer or multiple layers of an inorganic insulator such as silica or alumina or an organic insulator.

[0073] Additionally, the third insulating layer (206) may include an insulating and flexible material such as polyimide, PEN, PET, etc., and may be formed integrally with the substrate (200) to form a single substrate.

[0074] The third insulating layer (206) may be an adhesive insulating layer or a conductive adhesive layer having conductivity. The third insulating layer (206) may be flexible, thereby enabling a flexible function of the display device.

[0075] The third insulating layer (206) has a partition wall, and an assembly hole (203) can be formed by this partition wall. For example, when forming the substrate (200), a part of the third insulating layer (206) is removed, so that each of the light emitting elements (150) can be assembled into the assembly hole (203) of the third insulating layer (206).

[0076] An assembly hole (203) is formed in the substrate (200) to which light-emitting elements (150) are coupled, and the surface where the assembly hole (203) is formed can come into contact with a fluid (1200). The assembly hole (203) can guide the exact assembly position of the light-emitting elements (150).

[0077] Meanwhile, the assembly hole (203) may have a shape and size corresponding to the shape of the light-emitting element (150) to be assembled at the corresponding position. Accordingly, it is possible to prevent another light-emitting element from being assembled in the assembly hole (203) or multiple light-emitting elements from being assembled.

[0078]

[0079] FIG. 4 is a drawing showing an example in which a light-emitting element according to an embodiment is assembled on a substrate by a self-assembly method, and the self-assembly method of the light-emitting element is explained with reference to the drawings.

[0080] The substrate (200) may be a panel substrate of a display device. In the following description, the substrate (200) is described as a panel substrate of a display device, but the embodiment is not limited thereto.

[0081] Referring to FIG. 4, a plurality of light-emitting elements (150) may be placed in a chamber (1300) filled with a fluid (1200). The fluid (1200) may be, but is not limited to, water such as ultrapure water. The chamber may be referred to as a tank, a container, a vessel, or the like.

[0082] After this, the substrate (200) can be placed on the chamber (1300). Depending on the embodiment, the substrate (200) can also be introduced into the chamber (1300).

[0083] As shown in FIG. 3, a pair of assembly wirings (201, 202) corresponding to each light emitting element (150) to be assembled can be arranged on the substrate (200).

[0084] Referring to FIG. 4, after the substrate (200) is placed, an assembly device (1100) including a magnetic body can move along the substrate (200). For example, a magnet or an electromagnet can be used as the magnetic body. The assembly device (1100) can move in contact with the substrate (200) to maximize the area affected by the magnetic field within the fluid (1200). Depending on the embodiment, the assembly device (1100) may include a plurality of magnetic bodies or may include magnetic bodies of a size corresponding to that of the substrate (200). In this case, the movement distance of the assembly device (1100) may be limited within a predetermined range.

[0085] By the magnetic field generated by the assembly device (1100), the light emitting element (150) within the chamber (1300) can move toward the assembly device (1100).

[0086] The light emitting element (150) may move toward the assembly device (1100) and enter the assembly hole (203) by the dielectric electrophoretic force (DEP force) to come into contact with the substrate (200).

[0087] Specifically, the assembly wiring (201, 202) forms an electric field by an externally supplied power source, and a dielectric force can be formed between the assembly wiring (201, 202) by this electric field. The light-emitting element (150) can be fixed to the assembly hole (203) on the substrate (200) by this dielectric force.

[0088] The light emitting element (150) in contact with the substrate (200) can be prevented from being detached by the movement of the assembly device (1100) due to the electric field applied by the assembly wiring (201, 202) formed on the substrate (200). According to an embodiment, the time required for each of the light emitting elements (150) to be assembled on the substrate (200) can be drastically shortened by the self-assembly method using the electromagnetic field described above, so that a large-area, high-pixel display can be implemented more quickly and economically.

[0089] At this time, a predetermined solder layer (not shown) is formed between the light-emitting element (150) assembled on the assembly hole (203) of the substrate (200) and the assembly electrode, thereby improving the bonding strength of the light-emitting element (150).

[0090] Next, a molding layer (not shown) may be formed in the assembly hole (203) of the substrate (200). The molding layer may be a light-transmitting resin or a resin containing a reflective material or a scattering material.

[0091]

[0092] Fig. 5 is a cross-sectional view of a semiconductor light-emitting device for a display pixel according to an embodiment. Hereinafter, the "semiconductor light-emitting device for a display pixel" will be abbreviated as "semiconductor light-emitting device." Referring to Fig. 5, the semiconductor light-emitting device (150) according to the embodiment may be a semiconductor light-emitting device that emits red color, but is not limited thereto. In addition, the semiconductor light-emitting device (150) according to the embodiment may be a vertical semiconductor light-emitting device, but is not limited thereto.

[0093] The above semiconductor light-emitting device (150) may include a light-emitting structure (130), a first electrode (134), a reflective layer (135), a magnetic layer (138), and a passivation layer (140).

[0094] The above light-emitting structure (130) may include a first conductive semiconductor layer (131), an active layer (132) disposed on the first conductive semiconductor layer (131), and a second conductive semiconductor layer (133) disposed on the active layer (132).

[0095] The first conductive semiconductor layer (131) may be an n-type semiconductor layer, and the second conductive semiconductor layer (133) may be a p-type semiconductor layer, but is not limited thereto. The first conductive semiconductor layer (131), the active layer (132), and the second conductive semiconductor layer (133) may be formed of a compound semiconductor material. For example, the compound semiconductor material may be a group III-V compound semiconductor material, a group II-VI compound material, etc. For example, the compound semiconductor may be a binary compound selected from the group consisting of GaP, GaAs, GaSb, AlP, AlAs, AlSb, InP, InAs, InSb, and mixtures thereof; a ternary compound selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlInP, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, and mixtures thereof; and a group consisting of four-element compounds selected from the group consisting of AlGaInP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb and mixtures thereof.

[0096] For example, the first conductive semiconductor layer (131) may include a first conductive dopant, and the second conductive semiconductor layer (133) may include a second conductive dopant. For example, the first conductive dopant may be an n-type dopant such as silicon (Si), and the second conductive dopant may be a p-type dopant such as boron (B).

[0097] The active layer (132) is a region that generates light, and can generate light having a specific wavelength band depending on the material properties of the compound semiconductor. In addition, the active layer may have a multiple quantum well or single quantum well structure, and the wavelength band may be determined by the energy band gap of the compound semiconductor included in the active layer. Therefore, the semiconductor light-emitting device of the embodiment can generate UV light, blue light, green light, and red light depending on the energy band gap of the compound semiconductor included in the active layer.

[0098] In addition, it may include a first electrode (134) disposed on the light-emitting structure (130). The first electrode (134) may include a transparent conductive material such as ITO, ZnO, GZO, IGZO, etc., and may transmit an electrical signal from a wiring for driving a semiconductor light-emitting element to a second conductive semiconductor layer (133).

[0099]

[0100] In addition, the semiconductor light-emitting device (150) according to the embodiment may further include a reflective layer (135) disposed on the lower surface of the light-emitting structure (130). The reflective layer (135) may improve light efficiency by reflecting light generated from the active layer (132) upward. In addition, the reflective layer (135) may function as an ohmic contact layer of the first conductive semiconductor layer (131).

[0101] Additionally, the reflective layer (135) may include a first reflective layer (136) and a first region (137). The first reflective layer (136) may be in contact with the lower surface of the first conductive semiconductor layer (131).

[0102] The first reflective layer (136) may have a flat interface in contact with the first conductive semiconductor layer (131). Accordingly, there is a technical effect in which reflectivity is improved, thereby further enhancing light efficiency.

[0103] Additionally, a magnetic layer (138) may be placed under the reflective layer (135). The magnetic layer (138) may include Ti, Ni, etc., but is not limited thereto.

[0104] Meanwhile, the lower surface of the first reflective layer (136) may include a roughness shape. Accordingly, the magnetic layer (138) disposed on the lower surface of the first reflective layer (136) may also include a roughness shape. Accordingly, the embodiment has a technical effect that when the pick-and-place process is performed after the semiconductor light-emitting device (150) is assembled, the contact area between the rear surface of the semiconductor light-emitting device and the assembly substrate is reduced, thereby improving the pick-up rate. In addition, accordingly, the embodiment has a technical effect that the transfer yield of the semiconductor light-emitting device can be improved.

[0105]

[0106] Meanwhile, in the embodiment, the reflective layer (135) may include at least one of Ag, Au, Ge, and an alloy containing them. For example, the reflective layer (135) may be formed by forming an AuAg alloy on the lower surface of the light-emitting structure (130), followed by depositing Ge and heat treatment. Among these, Ge may be cooled after the heat treatment, causing agglomeration with Au.

[0107] Accordingly, a first region (137) may be formed within the reflective layer (135). The first region (137) may have a cylindrical shape. In addition, the first region (137) may vertically penetrate the first reflective layer (136). In addition, the first region (137) may be formed at a random position within the reflective layer (135). In addition, the upper surface of the first region (137) may be in contact with the first conductive semiconductor layer (131). In addition, the lower surface of the first region (137) may be in contact with the magnetic layer (138). The first region (137) may be a region having a high density of Ge. The Au of the reflective layer (135) may escape from the lower surface of the reflective layer (135) due to agglomeration with Ge. Accordingly, a roughness shape can be formed on the lower surface of the reflective layer (135).

[0108] In addition, the first reflective layer (136) may have a high density of AuAg alloy. In addition, the area of ​​the first reflective layer (136) may be larger than the area of ​​the first region (137). Specifically, the area of ​​the upper surface of the first reflective layer (136) on the upper surface of the reflective layer (135) may be larger than the area of ​​the upper surface of the first region (137). In addition, the area of ​​the lower surface of the first conductive semiconductor layer (131) in contact with the first reflective layer (136) may be larger than the area in contact with the first region (137).

[0109] Accordingly, the embodiment has a technical effect in that the pickup rate can be improved as the back surface of the semiconductor light-emitting element includes roughness, and the reflectivity can be improved as the upper surface of the reflective layer has a flat shape.

[0110]

[0111] Next, FIG. 6 is a drawing showing area B of FIG. 5. Referring to FIG. 6, the reflective layer (135) may include a first reflective layer (136) and a first region (137). The first region (137) may include a plurality of first regions within the first reflective layer (136). At this time, the cross-section of the first region (137) may include a trapezoidal shape. In addition, at least one of the plurality of first regions (137) may have a reverse tapered shape. In addition, the first region (137) includes an upper surface and a lower surface, and the upper surface of the first region (137) may be in contact with the first conductive semiconductor layer (131). In addition, the lower surface of the first region (137) may be in contact with the magnetic layer (138).

[0112] Meanwhile, the first width (L1) of the lower surface of the first region (137) may be larger than the second width (L2) of the upper surface. In detail, the area of ​​the first region (137) in contact with the first conductive semiconductor layer (131) may be smaller than the area in contact with the magnetic layer (138). Therefore, the embodiment has a special technical effect of improving the pickup rate during the transfer process while minimizing the reduction in reflectivity as the area of ​​the upper surface of the first region (137) is formed smaller than the area of ​​the lower surface.

[0113]

[0114] Fig. 7 is a drawing showing a part of the manufacturing process of an embodiment. Referring to Fig. 7, a first-first reflective layer (142) may be formed on the back of a light-emitting structure (130). The first-first reflective layer (142) may include at least one of Ag, Au, and AuAg alloys. In addition, a first-second reflective layer (143) may be formed on the back of the first-first reflective layer (142). The first-second reflective layer (143) may have a layer shape. In addition, the first-second reflective layer (143) may include Ge. Subsequently, after the first-first reflective layer (142) and the first-second reflective layer (143) are formed, heat treatment may be performed.

[0115] At this time, the Ge of the 1-2 reflective layer (143) and the Au of the 1-1 reflective layer (142) may agglomerate with each other. Accordingly, the boundary between the 1-1 reflective layer and the 1-2 reflective layer may disappear, and a rough shape may be formed on the lower surface of the reflective layer (135) (see Fig. 6). In addition, Ge may form the first region through agglomeration.

[0116] Therefore, the embodiment has a technical effect of being able to form a rough structure on the back of a semiconductor light-emitting device without a separate roughening forming process.

[0117] Meanwhile, by controlling the thickness of the first-second reflective layer (143), the Ge content may be changed, thereby changing the area of ​​the first region within the reflective layer. As the area of ​​the first region on the upper surface of the reflective layer decreases, the reflectivity may be improved.

[0118] In addition, as the area of ​​the first region on the lower surface of the reflective layer increases, the pickup rate in the transfer process can be improved. Therefore, the embodiment has a technical effect of controlling the reflectivity and pickup rate of the semiconductor light-emitting element by controlling the thickness of the first-second reflective layer (143).

[0119]

[0120] FIGS. 8A to 8C are drawings illustrating a process for transferring a semiconductor light-emitting device according to an embodiment. First, referring to FIG. 8A, a plurality of assembly wirings (113) may be arranged on an assembly substrate (108). An insulating layer (115) may be arranged to cover the assembly wirings (113). The insulating layer (115) may have adhesive properties. In addition, a partition wall (160) having an assembly hole may be arranged on the insulating layer (115). A semiconductor light-emitting device (150) may be assembled into the assembly hole.

[0121] Additionally, a stamp (190) may be placed on an assembly substrate (108) on which a semiconductor light-emitting device (150) is assembled. The stamp (190) may include a protrusion to correspond to the upper surface of the semiconductor light-emitting device (150). The stamp (190) may pick up the semiconductor light-emitting device (150) from the assembly substrate (108) and transfer it to a panel substrate.

[0122] Meanwhile, the semiconductor light-emitting device being studied internally has a problem in that the pickup rate of the semiconductor light-emitting device decreases due to the adhesive strength between the semiconductor light-emitting device and the insulating layer during the pick-and-place process. In addition, since the adhesive strength between the semiconductor light-emitting device (150) and the stamp (190) must be greater than the adhesive strength between the semiconductor light-emitting device (150) and the insulating layer (115), there is a problem in that the semiconductor light-emitting device (150) is damaged during the pressurizing process.

[0123] To solve this problem, the embodiment may have a reflective layer (135) disposed on the rear surface of the semiconductor light-emitting element (150) in a rough form. Accordingly, there is a technical effect in which the contact area between the semiconductor light-emitting element (150) and the insulating layer (115) of the assembly substrate is reduced, thereby improving the pickup rate.

[0124]

[0125] Next, referring to FIG. 8b, the semiconductor light-emitting element (150) picked up by the stamp (190) can be transferred to a display panel. The display panel can include a panel substrate (110), a lower wiring (111), and an adhesive layer (112). The adhesive layer (112) can include a viscous material. When the semiconductor light-emitting element (150) is transferred onto the adhesive layer (112), the back surface of the semiconductor light-emitting element (150) has an uneven structure, thereby improving the contact area with the adhesive layer (112), thereby providing a technical effect of improving the fixing force.

[0126]

[0127] Next, referring to FIG. 8C, after the semiconductor light-emitting element is transferred to the panel substrate, a post-process may be performed to manufacture a display device. First, a lower wiring (111) may be arranged on the panel substrate (110). In addition, an adhesive layer (112) may be arranged on the lower wiring (111). A semiconductor light-emitting element (150) may be arranged on the adhesive layer (112). A via may be formed in a portion of the adhesive layer so that a portion of the upper surface of the lower wiring (111) is exposed. A first panel wiring (163) may be arranged so that the exposed lower wiring (111) and the lower electrode of the semiconductor light-emitting element (150) are connected. At this time, the lower electrode of the semiconductor light-emitting element (150) may include a reflective layer (135) and a magnetic layer (138). The first region (137) of the reflective layer (135) may function as an ohmic contact. In addition, the upper surface of the reflective layer (135) is flat, so that reflectivity can be improved, and the lower surface includes a rough structure, so that the adhesive strength with the adhesive layer (112) is strengthened, thereby providing a technical effect of improving the fixing strength.

[0128] Next, a planarization layer (180) may be placed to cover the semiconductor light-emitting element (150) and the first panel wiring (163). A second panel wiring (165) may be placed on the planarization layer (180) and electrically connected to the first electrode of the semiconductor light-emitting element (150).

[0129]

[0130] A semiconductor light-emitting element for a display pixel according to an embodiment has a technical effect that can improve a pickup rate during a transfer process using a stamp.

[0131] For example, in an embodiment, a rough structure is formed on the back of a semiconductor light-emitting element, thereby reducing the contact area with the assembly substrate and improving the pickup rate.

[0132] In addition, the embodiment has a technical effect of being able to form a rough structure on the back of a semiconductor light-emitting device without a separate additional process.

[0133] For example, an embodiment can form a rough structure on the back surface by utilizing the agglomeration phenomenon of AuAg and Ge.

[0134] In addition, the embodiment has a technical effect of being able to control the reflectivity and pickup rate of a semiconductor light-emitting device.

[0135] For example, the embodiment can control the reflectivity and pickup rate of the semiconductor light-emitting element by controlling the thickness of the first and second reflective layers.

[0136]

[0137] Although the present invention has been described above with reference to embodiments thereof, it will be readily understood by those skilled in the art that various modifications and changes to the present invention can be made without departing from the spirit and scope of the present invention as set forth in the claims below.

[0138]

[0139] The embodiments may be applied to, but are not limited to, display devices. For example, the embodiments may be applied to, but are not limited to, a micro-LED display using an inorganic light-emitting element, an LED, as a light-emitting pixel.

Claims

1. A light-emitting structure comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; and A reflective layer disposed under the above light-emitting structure; A semiconductor light-emitting element for a display pixel, wherein the upper surface of the above-mentioned reflective layer has a flat shape and the lower surface has a roughness shape.

2. In paragraph 1, A semiconductor light emitting element for a display pixel, wherein the reflective layer comprises a first reflective layer and a first region.

3. In paragraph 2, A semiconductor light-emitting element for a display pixel, wherein the reflective layer comprises at least one alloy made of Au, Ag, Ge or a combination thereof.

4. In paragraph 2, The above first region is in contact with the lower surface of the first conductive semiconductor light-emitting element, A semiconductor light-emitting element for a display pixel, penetrating the first reflective layer.

5. In paragraph 1, It further includes a magnetic layer disposed under the above reflective layer, A semiconductor light-emitting element for a display pixel, wherein the surface of the magnetic layer corresponds to the shape of the lower surface of the reflective layer.

6. In paragraph 2, A semiconductor light-emitting element for a display pixel, wherein the area of ​​the lower surface of the first region is larger than the area of ​​the upper surface.

7. In paragraph 2, A semiconductor light-emitting element for a display pixel, wherein the lower surface of the first conductive semiconductor layer has a larger area in contact with the first reflective layer than an area in contact with the first region.

8. In paragraph 2, The above first area includes a plurality of A semiconductor light emitting element for a display pixel, wherein at least one of the plurality of first regions has a reverse tapered shape.

9. In paragraph 5, A semiconductor light-emitting element for a display pixel, wherein the magnetic layer does not contain Ge.

10. Substrate; Lower wiring arranged on the above substrate; An adhesive layer disposed on the lower wiring; A semiconductor light emitting element disposed on the adhesive layer; and It includes a first panel wiring that electrically connects the semiconductor light emitting element and the lower wiring, A display device including a semiconductor light-emitting element, wherein the semiconductor light-emitting element comprises a semiconductor light-emitting element for a display pixel according to any one of claims 1 to 9.

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