Semiconductor light-emitting element for display pixel and display device comprising same

Abstract

A semiconductor light-emitting element for a display pixel according to an embodiment comprises: a light-emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; and a first electrode disposed under the light-emitting structure, wherein the first electrode includes a first concave-convex structure on a lower surface thereof, and the first concave-convex structure may be disposed in a central region of the first electrode.

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, although the transfer speed can be improved, there is a technical problem in that the transfer error rate can increase, resulting in a lower transfer yield.

[0012] Meanwhile, a self-assembly transfer process using dielectrophoresis (DEP) is being attempted in related technologies, but there is a problem of low self-assembly rate due to non-uniformity of DEP force.

[0013] In addition, when assembling a semiconductor light-emitting device on an assembly substrate and then transferring it to a panel substrate, there is a problem in that the pickup rate decreases due to the adhesive strength between the semiconductor light-emitting device and the assembly substrate, leading to a decrease in the transfer yield.

[0014] One of the technical challenges of the embodiment is to improve the assembly rate of semiconductor light-emitting devices.

[0015] One of the technical challenges of the embodiment is to improve the transfer yield of semiconductor light-emitting devices to a panel substrate after self-assembly.

[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 including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; and a first electrode disposed under the light-emitting structure; wherein the first electrode includes a first concave-convex structure on a lower surface, and the first concave-convex structure can be disposed in a central region of the first electrode.

[0018] Additionally, in the embodiment, the first electrode includes a first region surrounding the first concave-convex structure, and the first region may have a flat surface.

[0019] Additionally, in the embodiment, the first electrode further includes a second protruding structure on the lower surface, and the second protruding structure can be arranged around the periphery of the lower surface of the first electrode.

[0020] Additionally, in the embodiment, the first electrode includes a protective layer, a magnetic layer disposed on the protective layer, and a reflective layer disposed on the magnetic layer, and the first uneven structure may be disposed on the lower surface of the protective layer.

[0021] Additionally, in the embodiment, the thickness of the first concave structure may be smaller than the thickness of the protective layer.

[0022] Additionally, in the embodiment, the second uneven structure surrounds the first uneven structure, and the thickness of the second uneven structure may be the same as the thickness of the first uneven structure.

[0023] In addition, the embodiment further includes a passivation layer surrounding a side surface of the light-emitting structure, and a lower surface of the passivation layer may be disposed at a height higher than the upper surface of the first electrode.

[0024]

[0025] In addition, a display device including a semiconductor light-emitting element according to an embodiment includes: a substrate; 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 lower wiring and the semiconductor light-emitting element; wherein the semiconductor light-emitting element includes: a light-emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; and a first electrode disposed under the light-emitting structure; wherein the first electrode includes a first uneven structure on a lower surface, and the first uneven structure can be disposed in a central region of the first electrode.

[0026] Additionally, the embodiment may further include a second recessed structure arranged to surround the first recessed structure.

[0027] Additionally, in an embodiment, the adhesive layer may be characterized by being interlocked with the first uneven structure.

[0028] The semiconductor light-emitting device for display pixels according to the embodiment has a technical effect in that as the surface area of ​​the back surface of the semiconductor light-emitting device increases, the influence of the electromagnetic force during self-assembly increases, thereby increasing the dielectrophoretic (DEP) force and improving the assembly rate.

[0029] For example, in the embodiment, as the surface area increases by forming a rough structure on the back of the semiconductor light-emitting device, the electromagnetic force applied by the assembly electrode and the assembly magnet increases, so that the self-assembly rate using the DEP force can be improved.

[0030] In addition, the embodiment has a technical effect in that after the semiconductor light-emitting element is assembled on the assembly substrate, the area in contact with the assembly substrate is reduced by the first uneven structure, thereby improving the pickup rate and thus improving the transfer yield.

[0031] For example, since the first electrode of the semiconductor light-emitting device includes a rough structure, the area in contact with the assembly substrate is reduced, and thus the adhesive strength with the assembly substrate is reduced, so that the pickup rate can be improved.

[0032] In addition, the embodiment has a technical effect in that when a semiconductor light-emitting device is assembled, the contact area with the assembly substrate increases as the first region has a flat surface, thereby improving the assembly rate.

[0033] 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.

[0034] Figure 1 is an exemplary diagram of a living room of a house in which a display device according to an embodiment is placed.

[0035] Figure 2 is an enlarged view of the first panel area in the display device of Figure 1.

[0036] Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0037] 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.

[0038] Fig. 5 is a cross-sectional view of a semiconductor light-emitting element for a display pixel according to the first embodiment.

[0039] Fig. 6 is a cross-sectional view of a semiconductor light-emitting element for a display pixel according to a second embodiment.

[0040] Figures 7a to 7e are manufacturing process diagrams of a semiconductor light-emitting element for a display pixel according to the first embodiment.

[0041] Fig. 8 is a display device including a semiconductor light-emitting element according to the third embodiment.

[0042] FIGS. 9A to 9E are process diagrams for manufacturing a display device including a semiconductor light-emitting element according to a third embodiment.

[0043] 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.

[0044] 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.

[0045]

[0046] A light-emitting element and a display device including the same according to the following embodiment are described.

[0047] FIG. 1 illustrates a living room of a house in which a display device (100) according to an embodiment is placed.

[0048] 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.

[0049] 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.

[0050] 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.

[0051]

[0052] Figure 2 is an enlarged view of the first panel area (A1) in the display device of Figure 1.

[0053] 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.

[0054] The first panel area (A1) may include a plurality of light-emitting elements (150) arranged for each unit pixel (PX in FIG. 2).

[0055] 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.

[0056]

[0057] Next, Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0058] 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).

[0059] 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.

[0060] 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.

[0061] 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.

[0062]

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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).

[0073] 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).

[0074] 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.

[0075]

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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).

[0080] 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).

[0081] 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.

[0082] 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).

[0083] 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).

[0084] 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.

[0085] 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.

[0086] 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).

[0087] 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.

[0088]

[0089] Fig. 5 is a cross-sectional view of a semiconductor light-emitting device for a display pixel according to a first embodiment. Hereinafter, the “semiconductor light-emitting device for a display pixel” is abbreviated as “semiconductor light-emitting device.” Referring to Fig. 5, the semiconductor light-emitting device (150) according to the first embodiment may be a vertical semiconductor light-emitting device, but is not limited thereto. The semiconductor light-emitting device (150) may include a light-emitting structure (135), a first electrode (130), a second electrode (139), and a passivation layer (140).

[0090] The above light-emitting structure (135) may include a first conductive semiconductor layer (136), an active layer (137) disposed on the first conductive semiconductor layer (136), and a second conductive semiconductor layer (138) disposed on the active layer (137).

[0091] The first conductive semiconductor layer (136) may be an n-type semiconductor layer, and the second conductive semiconductor layer (138) may be a p-type semiconductor layer, but is not limited thereto. The first conductive semiconductor layer (136), the active layer (137), and the second conductive semiconductor layer (138) 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.

[0092] For example, the first conductive semiconductor layer (136) may include a first conductive dopant, and the second conductive semiconductor layer (138) 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).

[0093] The active layer (137) 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.

[0094] In addition, it may include a second electrode (139) disposed on the light-emitting structure (135). The second electrode (139) 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 (138). In addition, the lower surface of the passivation layer is disposed at a height higher than the upper surface of the first electrode.

[0095] Meanwhile, the semiconductor light-emitting device being studied internally has a flat first electrode located on the back, so the adhesion to the substrate is strong, and there is a problem that the pickup rate decreases when picking up the chip with a stamp, which leads to a problem of reduced production yield.

[0096]

[0097] Meanwhile, in order to solve the above problem, in the first embodiment, the first electrode (130) may include a reflective layer (134) disposed under the light-emitting structure (135), an adhesive layer (133) disposed under the reflective layer (134), a magnetic layer (132) disposed under the adhesive layer 133, and a protective layer (131) disposed under the magnetic layer (132). The reflective layer (134) may reflect light emitted from the active layer (137) upward to improve light efficiency. The reflective layer (134) may have a flat surface. In addition, the magnetic layer (132) may allow the semiconductor light-emitting element to move to the assembly hole by the assembly magnet during self-assembly.

[0098] Additionally, the protective layer (131) may include a metal material. For example, the protective layer (131) may include Ti or Ni, but is not limited thereto.

[0099] At this time, the protective layer (131) may include a first uneven structure (145). The first uneven structure (145) may be formed in a portion of the protective layer (131). The first uneven structure (145) may be formed by etching the surface of the protective layer (131). The first uneven structure (145) may be formed in a central region of the protective layer (131). In addition, the thickness of the first uneven structure (145) may be smaller than the thickness of the protective layer (131).

[0100] Accordingly, the embodiment has a technical effect in that the assembly rate can be improved by increasing the influence of electromagnetic force during self-assembly as the surface area of ​​the back surface of the semiconductor light-emitting element (150) increases.

[0101] In addition, the embodiment has a technical effect in that after the semiconductor light-emitting element (150) is assembled on the assembly substrate, the area in contact with the assembly substrate is reduced by the first uneven structure (145), thereby improving the pickup rate and thus improving the transfer yield.

[0102] In addition, the protective layer (131) may include a first region (147) in which the first uneven structure (145) is not formed. The first region (147) may have a flat surface. Accordingly, the embodiment has a technical effect in that when a semiconductor light-emitting device is assembled, the contact area with the assembly substrate increases due to the first region (147) having a flat surface, thereby improving the assembly rate.

[0103]

[0104] Fig. 6 is a cross-sectional view of a semiconductor light-emitting device according to a second embodiment. Referring to Fig. 6, the first electrode (130) of the semiconductor light-emitting device (150) may include at least one of a reflective layer (134), an adhesive layer (133), a magnetic layer (132), and a protective layer (131).

[0105] Additionally, the first electrode (130) may include a first-second uneven structure (143) on the rear surface. The first-second uneven structure (143) may be arranged in the central region of the lower surface of the first electrode (130).

[0106] Additionally, the second embodiment may include a second recessed structure (146) arranged to surround the first-second recessed structure (143).

[0107] The second uneven structure (146) may be arranged on the back of the protective layer (131). The thickness of the second uneven structure (146) may be the same as the thickness of the first-second uneven structure (143).

[0108] The lower surface of the first electrode (130) may be covered by the first-second uneven structure (143) and the second uneven structure (146). The second uneven structure (146) may be formed by etching the surface of the protective layer (131).

[0109] The protective layer (131) includes a metal material, and may include, for example, one of Ti and Ni, but is not limited thereto. In addition, the thickness of the second uneven structure (146) may be smaller than the thickness of the protective layer (131). Accordingly, in the second embodiment, the area of ​​the bottom surface of the semiconductor light-emitting device in contact with the surface of the assembly substrate may be reduced. Accordingly, the second embodiment has a technical effect of improving the pickup rate and thus the transfer yield when transferring the semiconductor light-emitting device from the assembly substrate to the panel substrate.

[0110]

[0111] Figures 7a to 7e are manufacturing process diagrams of a semiconductor light-emitting device according to an embodiment.

[0112] First, referring to FIG. 7a, a light-emitting structure (135) can be grown on a growth substrate (105). In addition, a passivation layer (140) can be deposited on the light-emitting structure (135). The passivation layer (140) can cover both the top and side surfaces of the light-emitting structure (135). In addition, a sacrificial layer (107) can be formed on the passivation layer (140). The sacrificial layer (107) can include Al, but is not limited thereto.

[0113]

[0114] Next, referring to FIG. 7b, a bonding layer (170) may be placed on the sacrificial layer (107). The bonding layer (170) may be placed to completely cover the sacrificial layer (107), but is not limited thereto. A temporary substrate (106) may be placed on the bonding layer (170). The temporary substrate (106) may be a sapphire substrate, but is not limited thereto. Thereafter, the temporary substrate (106) and the bonding layer (170) may be bonded through a thermal bonding process.

[0115]

[0116] Next, referring to FIG. 7c, after the temporary substrate (106) of FIG. 7b is turned over, a process of removing the growth substrate connected to the light-emitting structure (135) may be performed. The growth substrate may be removed by a laser lift off (LLO) process or a chemical lift off (CLO) process, but is not limited thereto. In addition, after the growth substrate is removed, a portion of the passivation layer may be removed. Subsequently, a portion of the sacrificial layer (107) may be removed. The sacrificial layer (107) may be removed in an area such that only the sacrificial layer (107) disposed under the light-emitting structure (135) remains. The passivation layer (140) and the sacrificial layer (107) may be removed by etching, but are not limited thereto.

[0117] Although FIG. 7c illustrates a portion of the bonding layer (170) being removed, the bonding layer (170) may not be removed. Referring briefly to (a) of FIG. 7e, a portion of the bonding layer (170) may be removed. The bonding layer (170) may be removed up to the height of the lower surface of the sacrificial layer (107). In addition, referring to (b) of FIG. 7e, the bonding layer (170) may not be removed, and the upper surface of the bonding layer (170) may have a height corresponding to the rear surface of the light-emitting structure (135).

[0118]

[0119] Next, referring to FIG. 7d, a first electrode (130) may be deposited on the back surface of the exposed light-emitting structure (135). The first electrode (130) may include at least one of a reflective layer, an adhesive layer, a magnetic layer, and a protective layer. The first electrode (130) may include Ti, Ni, or the like, but is not limited thereto. The first electrode (130) may be deposited in the remaining area of ​​the bonding layer (170) where the light-emitting structure (135) is not disposed, but may be removed thereafter.

[0120]

[0121] Next, referring to FIG. 7e, a process of partially etching the first electrode (130) positioned on the rear surface of the light-emitting structure (135) is performed. Plasma may be used for etching the first electrode (130).

[0122] First, referring to (a) of FIG. 7e, the height of the bonding layer (170) may be lower than the height of the light-emitting structure (135). The height of the upper surface of the bonding layer (170) may be lower than the lower surface of the light-emitting structure (135). When there is a height difference between the light-emitting structure (135) and the bonding layer (170), an atmosphere may be formed in which the plasma is not concentrated on the light-emitting structure (135) but escapes to an area with a lower height.

[0123] Accordingly, the first electrode (130) may be subjected to plasma etching only in the central region, rather than being etched in the entire region. Accordingly, the first electrode (130) may have a first uneven structure (145) formed in the central region, and the first region (147) where the first uneven structure (145) is not formed may have a flat surface. The thickness of the first uneven structure (145) may be smaller than the thickness of the first electrode (130).

[0124] In addition, in (b) of FIG. 7e, the bonding layer (170) may have a height corresponding to the height of the light-emitting structure (135). There may be no height difference between the back surface of the light-emitting structure (135) and the bonding layer (170). In this case, when plasma etching is performed, the plasma may uniformly etch the entire area. Accordingly, a second uneven structure (146) is formed on the first electrode (130), and a flat area may not be formed. The thickness of the second uneven structure (146) may be smaller than the thickness of the first electrode (130).

[0125]

[0126] Fig. 8 is a cross-sectional view of a display device (155) including a semiconductor light-emitting element according to the third embodiment.

[0127] Referring to Fig. 8, a lower wiring (115) may be arranged on a panel substrate (110). In addition, an adhesive layer (120) may be arranged on the lower wiring (115). The adhesive layer (120) may expose a portion of the lower wiring (115). In addition, a semiconductor light-emitting element (150) may be arranged on the adhesive layer (120).

[0128] The semiconductor light-emitting device (150) may include a light-emitting structure, a first electrode (130), and a second electrode (139). The first electrode (130) may be electrically connected to the lower wiring (115) by a first panel wiring (125). The first panel wiring (125) may be in contact with a side surface of the first electrode (130).

[0129] Additionally, a planarization layer (180) may be arranged to cover the semiconductor light-emitting element and the first panel wiring (125). A second panel wiring (165) may be arranged on the planarization layer (180) and connected to the second electrode (139) of the semiconductor light-emitting element (150). The second panel wiring (165) may include a transparent electrode.

[0130] Meanwhile, the first electrode (130) of the semiconductor light-emitting device (150) may include a first concave-convex structure (145). Although only the first concave-convex structure (145) is illustrated in FIG. 8, a second concave-convex structure arranged to surround the first concave-convex structure (145) may be further included. The thickness of the second concave-convex structure may be the same as the thickness of the first concave-convex structure. In addition, the adhesive layer (120) may be interlocked with the first concave-convex structure (145). The first concave-convex structure (145) not only has a technical effect of improving a pick-up rate in the process of transferring the semiconductor light-emitting device (150) from a temporary substrate to a panel substrate, but also has a technical effect of strengthening a fixing force for fixing the semiconductor light-emitting device (150) to the panel substrate (110) by increasing the area in contact with the adhesive layer (120) due to the concave-convex structure.

[0131]

[0132] FIGS. 9A to 9E are manufacturing process diagrams of a display device including a semiconductor light-emitting element according to a third embodiment. First, referring to FIG. 9A, an assembly wiring (112) may be arranged on an assembly substrate (108). In addition, an insulating layer may be arranged to cover the assembly wiring (112). In addition, a semiconductor light-emitting element (150) may be assembled on the insulating layer by the assembly wiring (112). The semiconductor light-emitting element (150) may include a plurality of elements, and may include a first semiconductor light-emitting element (150a), a second semiconductor light-emitting element (150b), and a third semiconductor light-emitting element (150c). The first semiconductor light-emitting element (150a), the second semiconductor light-emitting element (150b), and the third semiconductor light-emitting element (150c) may emit red, green, and blue light, respectively, but are not limited thereto.

[0133] In addition, a stamp (190) may be placed on the plurality of semiconductor light-emitting devices (150) as a process for transferring the assembled semiconductor light-emitting devices to a panel substrate. The stamp (190) may include PDMS, but is not limited thereto. In addition, the stamp (190) may be provided with a protrusion corresponding to each upper surface of the semiconductor light-emitting devices (150).

[0134] Meanwhile, the semiconductor light-emitting device (150) may include a first uneven structure (145) on the rear surface. The first uneven structure (145) may be located at the center of the rear surface of the semiconductor light-emitting device (150), but is not limited thereto. In addition, the remaining area of ​​the rear surface of the semiconductor light-emitting device (150) excluding the first uneven structure (145) may be flat, but is not limited thereto.

[0135]

[0136] Next, referring to FIG. 9b, the semiconductor light emitting device (150) can be picked up by the stamp (190). Referring briefly to FIG. 9a, the surface area of ​​the bottom surface of the semiconductor light emitting device (150) can be reduced by the first uneven structure (145). Accordingly, the contact area between the semiconductor light emitting device (150) and the insulating layer can be reduced. Accordingly, the adhesive strength between the semiconductor light emitting device (150) and the insulating layer is reduced, so that there is a technical effect of improving the pick-up rate when picking up the semiconductor light emitting device (150) using the stamp (190).

[0137]

[0138] Next, referring to FIG. 9c, the semiconductor light emitting device (150) picked up from the stamp can be transferred to the panel substrate (110). A lower wiring (115) can be placed on the panel substrate (110), and an insulating layer (113) can be placed to cover the lower wiring (115). In addition, an adhesive layer (120) can be placed on the insulating layer (113). A plurality of semiconductor light emitting devices (150) can be placed to correspond to the positions of the respective lower wirings (115). In addition, after the semiconductor light emitting device (150) is placed on the adhesive layer (120), a predetermined pressure can be applied by the stamp. Meanwhile, since the semiconductor light emitting device (150) includes a first uneven structure (145) on the rear surface, the contact area can increase when it is placed on the adhesive layer (120) from the stamp. Accordingly, the embodiment has a technical effect in that the adhesive strength between the semiconductor light-emitting element (150) and the adhesive layer (120) can be increased, thereby improving the transfer yield.

[0139]

[0140] Next, referring to FIG. 9d, after the semiconductor light-emitting element (150) is transferred to the panel substrate (110), a wiring process may be performed. First, the adhesive layer in the remaining area, excluding the adhesive layer (120) in contact with the semiconductor light-emitting element (150), may be etched. In addition, in order to expose the lower wiring (115) to be connected to the semiconductor light-emitting element (150), the adhesive layer (120) and the insulating layer (113) may be etched to form a via hole (115H).

[0141]

[0142] Next, referring to FIG. 9e, a first panel wiring (125) may be formed to be connected to the exposed lower wiring (115). The first panel wiring (125) may extend along the adhesive layer (120) to the side of the semiconductor light-emitting device (150). The first panel wiring (125) may be in contact with the side of the first electrode (130) of the semiconductor light-emitting device (150) to be electrically connected to the lower wiring (115). In addition, a planarization layer (180) may be formed to cover the first panel wiring (125) and the semiconductor light-emitting device (150). In addition, a second panel wiring (165) may be formed on the planarization layer (180) to supply power to the second electrode of the semiconductor light-emitting device (150). The second panel wiring (165) may include a transparent electrode.

[0143] Since the semiconductor light-emitting element (150) includes a first uneven structure (145) on the rear surface, there is a technical effect that the fixing force increases after the semiconductor light-emitting element (150) is transferred to the panel substrate (110), thereby improving the transfer yield.

[0144]

[0145] The semiconductor light-emitting device for display pixels according to the embodiment has a technical effect in that the assembly rate can be improved by increasing the influence of electromagnetic force during self-assembly as the surface area of ​​the back surface of the semiconductor light-emitting device increases.

[0146] For example, in the embodiment, as a surface area increases due to the formation of a rough structure on the back of a semiconductor light-emitting device, the electromagnetic force applied by the assembly electrode and the assembly magnet increases, thereby improving the assembly rate.

[0147] In addition, the embodiment has a technical effect in that after the semiconductor light-emitting element is assembled on the assembly substrate, the area in contact with the assembly substrate is reduced by the first uneven structure, thereby improving the pickup rate and thus improving the transfer yield.

[0148] For example, since the first electrode of the semiconductor light-emitting device includes a rough structure, the area in contact with the assembly substrate is reduced, and thus the adhesive strength with the assembly substrate is reduced, so that the pickup rate can be improved.

[0149] In addition, the embodiment has a technical effect that the contact area with the assembly substrate increases as the first region has a flat surface when the semiconductor light-emitting device is assembled, thereby improving the assembly rate.

[0150]

[0151] 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 may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0152] 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 first electrode disposed under the light-emitting structure; The first electrode includes a first concave-convex structure on the lower surface, A semiconductor light-emitting element for a display pixel, wherein the first concave-convex structure is arranged in the central region of the first electrode.

2. In paragraph 1, The first electrode includes a first region surrounding the first concave-convex structure, A semiconductor light-emitting element for a display pixel, wherein the first region has a flat surface.

3. In paragraph 1, The above first electrode further includes a second concave-convex structure on the lower surface, A semiconductor light-emitting element for a display pixel, wherein the second concave-convex structure is arranged around the periphery of the lower surface of the first electrode.

4. In paragraph 1, The above first electrode, It comprises a protective layer, a magnetic layer disposed on the protective layer, and a reflective layer disposed on the magnetic layer. A semiconductor light-emitting element for a display pixel, wherein the first uneven structure is arranged on the lower surface of the protective layer.

5. In paragraph 4, A semiconductor light-emitting element for a display pixel, wherein the thickness of the first concave structure is smaller than the thickness of the protective layer.

6. In paragraph 3, The above second concave structure surrounds the above first concave structure, A semiconductor light-emitting element for a display pixel, wherein the thickness of the second concave-convex structure is the same as the thickness of the first concave-convex structure.

7. In paragraph 1, It further includes a passivation layer surrounding the side of the above light-emitting structure, A semiconductor light-emitting element for a display pixel, wherein the lower surface of the passivation layer is positioned at a height higher than the upper surface of the first electrode.

8. 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 A first panel wiring electrically connecting the lower wiring and the semiconductor light emitting element; The above semiconductor light emitting device is, A light-emitting structure comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; and A first electrode disposed under the light-emitting structure; The first electrode includes a first concave-convex structure on the lower surface, A display device including a semiconductor light-emitting element, wherein the first concave structure is arranged in the central region of the first electrode.

9. In paragraph 8, A display device including a semiconductor light emitting element, further comprising a second concave structure arranged to surround the first concave structure.

10. In paragraph 8, A display device including a semiconductor light emitting element, characterized in that the adhesive layer and the first uneven structure are interlocked.

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