Transfer method of semiconductor light-emitting device for display pixels

Abstract

In a transfer method of a semiconductor light-emitting device for display pixels, according to an embodiment, is a transfer method of a semiconductor light-emitting device comprising: a light-emitting structure including a first conductive-type semiconductor layer, an active layer disposed on the first conductive-type semiconductor layer and a second conductive-type semiconductor layer disposed on the active layer; and a passivation layer disposed on the light-emitting structure, the method comprising the steps of: forming a sacrificial layer on the semiconductor light-emitting device; and bonding the semiconductor light-emitting device to a transfer substrate by interposing the sacrificial layer therebetween, wherein the sacrificial layer is disposed between the semiconductor light-emitting device and the transfer substrate.

Description

Transfer method of semiconductor light-emitting elements for display pixels

[0001] The embodiment relates to a method for transferring a semiconductor light-emitting element for a display pixel.

[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, organic materials are used in the transfer process of semiconductor light-emitting devices, but there is a problem that the organic materials remain in the subsequent process and act as foreign substances, causing contamination of the semiconductor light-emitting devices.

[0014] One of the technical challenges of the embodiment is to simplify the transfer process of semiconductor light-emitting devices.

[0015] Additionally, one of the technical challenges of the embodiment is to prevent the generation of foreign substances during the transcription process.

[0016] Additionally, one of the technical challenges of the embodiment is to prevent bonding failure between the semiconductor light-emitting element and the transfer substrate.

[0017] Additionally, one of the technical challenges of the embodiment is to prevent misalignment of miniaturized chips during the transfer process.

[0018] Additionally, one of the technical challenges of the embodiment is to improve the transfer rate of semiconductor light-emitting devices.

[0019] 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.

[0020] A transfer method of a semiconductor light-emitting device for a display pixel according to an embodiment comprises a light-emitting structure including a first conductive semiconductor layer, an active layer disposed on the first conductive semiconductor layer, a second conductive semiconductor layer disposed on the active layer, and a passivation layer disposed on the light-emitting structure, the method comprising: forming a sacrificial layer on the semiconductor light-emitting device; and bonding the semiconductor light-emitting device to a transfer substrate via the sacrificial layer; wherein the sacrificial layer may be disposed between the semiconductor light-emitting device and the transfer substrate.

[0021] Additionally, in an embodiment, an organic material may not be placed between the semiconductor light-emitting element and the transfer substrate.

[0022] Additionally, in the embodiment, the sacrificial layer (145) may include any one of Al, Cu, Ag, Au, Ni, Pt, W, Ti, Mo, Fe, Co, Sn, Zn, Pb, Mg, carbon steel, Inconel, and stainless steel.

[0023] Additionally, in embodiments, the transfer substrate may further include a first metal layer.

[0024] Additionally, in an embodiment, the first metal layer may include the same metal as the sacrificial layer.

[0025] Additionally, the embodiment may further include a step of forming a second electrode on the rear surface of the first conductive semiconductor layer.

[0026] Additionally, the embodiment may further include a step of forming a side electrode on the rear surface of the second electrode.

[0027] Additionally, in the embodiment, the transfer substrate may include a bonding region, which is a region where the semiconductor light-emitting element is bonded, and may include a second-1 electrode disposed outside the bonding region of the transfer substrate.

[0028] In addition, the embodiment further includes a step of removing the sacrificial layer to separate the semiconductor light-emitting element from the transfer substrate, wherein the bonding area of ​​the transfer substrate may expose the surface of the transfer substrate.

[0029] In addition, in the embodiment, the step of bonding the semiconductor light-emitting element to the transfer substrate may be performed within a range of 100 to 1000, and the pressure may be performed within a range of 500 N to 100 kN.

[0030] The method for transferring a semiconductor light-emitting element for a display pixel according to an embodiment has a technical effect of simplifying the transfer process of the semiconductor light-emitting element.

[0031] For example, the embodiment can simplify the transfer process by performing the bonding process without organic patterning.

[0032] In addition, the embodiment has a technical effect of preventing contamination of a semiconductor light-emitting element during a transfer process.

[0033] For example, the embodiment can prevent contamination of a semiconductor light-emitting device because the bonding process is performed without forming an organic substance that acts as a foreign substance in the fluid.

[0034] Additionally, the embodiment has a technical effect of preventing misalignment of a miniaturized chip.

[0035] For example, the embodiment can prevent the problem of chip misalignment due to the fluidity of organic materials during bonding.

[0036] In addition, the embodiment has a technical effect that can improve the transfer rate of a semiconductor light-emitting device.

[0037] For example, the embodiment can prevent foreign substances from penetrating into the assembly hole and interfering with the transfer of the semiconductor light-emitting element.

[0038] 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.

[0039] Figure 1 is an exemplary diagram of a living room of a house in which a display device according to an embodiment is placed.

[0040] Figure 2 is an enlarged view of the first panel area in the display device of Figure 1.

[0041] Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0042] 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.

[0043] Figure 5 is an SEM photograph showing the bonding state of a semiconductor light-emitting device being studied internally.

[0044] Figures 6 to 11 are process diagrams of a transfer method for a semiconductor light-emitting device according to the first embodiment.

[0045] Figure 12 is a drawing showing a transfer substrate to which an embodiment is applied.

[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] Fig. 2 is an enlarged view of the first panel area (A1) in the display device of Fig. 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 photograph showing a portion of the transfer process of a semiconductor light-emitting device being studied internally. In the transfer process of a semiconductor light-emitting device being studied internally, a sacrificial layer and a bonding material are used when fixing the semiconductor light-emitting device to a temporary substrate. Referring to Fig. 5, a sacrificial layer (45) is present on a semiconductor light-emitting device (50), and a bonding material (25) is arranged for bonding with a transfer substrate (60), so that the semiconductor light-emitting device (50) can be bonded on the transfer substrate (60). The sacrificial layer may include a metallic material. In addition, the bonding material may include an organic material.

[0093] Meanwhile, in the process of separating the semiconductor light-emitting element (50) from the transfer substrate (60), a bonding material (25) remains. The bonding material (25) may remain on the surface of the temporary substrate and may exist in the area where the semiconductor light-emitting element is bonded. In addition, the bonding material (25) may remain on the semiconductor light-emitting element (50) and may act as a foreign substance in the fluid when the fluid is dispersed. Accordingly, the remaining bonding material acts as a foreign substance in a subsequent process, and may penetrate into the assembly hole or adhere to the surface of the semiconductor light-emitting element, thereby lowering the yield of the transfer process.

[0094] In addition, as semiconductor light-emitting devices become smaller, bonding materials (25) also become smaller, increasing the difficulty of patterning, reducing bonding strength, and causing organic materials to cause misalignment of chips.

[0095]

[0096] Hereinafter, an embodiment for solving the above problem will be described.

[0097] Figures 6 to 11 are process diagrams showing a transfer method of a semiconductor light-emitting element for a display pixel according to an embodiment. Referring to Figure 6, a buffer layer (120) may be formed on a growth substrate (115). In addition, a light-emitting structure (130) may be formed on the buffer layer (120). The 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).

[0098] 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.

[0099] 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).

[0100] 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 (132) 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 (132). 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 (132).

[0101] A first electrode (134) may be placed on the light-emitting structure (130). The first electrode (134) may be formed as a transparent electrode. For example, it may include ITO, IZO, ZnO, etc., but is not limited thereto.

[0102]

[0103] Referring to FIG. 7, a first passivation layer (140) may be arranged to cover the light-emitting structure (130). The first passivation layer (140) may be formed from the upper surface of the light-emitting structure (130) to a portion of the growth substrate (115). In addition, a sacrificial layer (145) may be formed on the first passivation layer (140). The sacrificial layer (145) may include a metal. For example, the sacrificial layer (145) may include Al, Cu, Ag, Au, Ni, Pt, W, Ti, Mo, Fe, Co, Sn, Zn, Pb, Mg, carbon steel, Inconel, stainless steel, etc., and may be formed of the same kind, different kinds, a combination of three kinds, etc., but is not limited thereto.

[0104]

[0105] FIG. 8A is a conceptual diagram illustrating bonding of a semiconductor light-emitting element (150) and a transfer substrate (160) according to a first embodiment. Referring to FIG. 8A, the semiconductor light-emitting element formed in FIG. 7 can be bonded to a transfer substrate (160). In the first embodiment, the sacrificial layer (145) is brought into direct contact with the transfer substrate (160), and then the sacrificial layer (145) and the transfer substrate (160) can be bonded under high temperature and high pressure conditions. The transfer substrate (160) may include sapphire (Al2O3), but is not limited thereto.

[0106] At this time, no organic material may exist between the passivation layer (140) of the semiconductor light-emitting element and the transfer substrate (160). Only a sacrificial layer (145) may exist between the semiconductor light-emitting element (150) and the transfer substrate (160).

[0107] Meanwhile, when a semiconductor light-emitting device is bonded to a transfer substrate without a separate bonding material (organic material), there is a problem that the semiconductor light-emitting device may be damaged. For example, the first electrode (134) may be damaged due to pressure during the bonding process. As a result, a problem with the semiconductor light-emitting device lighting may occur. In addition, there is a problem that air bubbles are trapped in the bonding area between the transfer substrate and the semiconductor light-emitting device, preventing the semiconductor light-emitting device from being bonded.

[0108] Meanwhile, in the embodiment, the temperature of the bonding process may be 100°C to 1000°C. In addition, the pressure in the bonding process may be 500N to 100kN. In the embodiment, the sacrificial layer (145) and the transfer substrate (160) may be bonded within the temperature and pressure range of the bonding process. In addition, the temperature of the bonding process may be lower than the melting point of the material constituting the sacrificial layer. The sacrificial layer (145) may be bonded in a solid state rather than in a liquid state.

[0109] Accordingly, the embodiment can bond a semiconductor light-emitting element to a transfer substrate without a bonding material composed of an organic material. Accordingly, the embodiment has the technical effect of simplifying the transfer process by enabling a bonding process without a patterning process of the organic material. In addition, the embodiment has the technical effect of preventing the problem of the organic material acting as a foreign substance during fluid dispersion. In addition, the embodiment has the technical effect of improving alignment accuracy in the bonding area and improving the transfer rate even when the semiconductor light-emitting element is miniaturized.

[0110]

[0111] In addition, Fig. 8b is a drawing showing the bonding of a semiconductor light-emitting element and a transfer substrate according to the second embodiment. Referring to Fig. 8b, the transfer substrate (160) may further include a first metal layer (163). Accordingly, the sacrificial layer (145) of the semiconductor light-emitting element may be in direct contact with the first metal layer (163). The first metal layer (163) may include the same metal as the sacrificial layer (145), but is not limited thereto. The first metal layer (163) may include any one of Al, Cu, Ag, Au, Ni, Pt, W, Ti, Mo, Fe, Co, Sn, Zn, Pb, Mg, carbon steel, Inconel, and stainless steel, and may be formed of the same kind, different kinds, or a combination of three kinds thereof.

[0112] Under high temperature and high pressure conditions, the first metal layer (163) and the sacrificial layer (145) can form a metallic bond by diffusion in the solid state. Meanwhile, the process temperature may be lower than the melting point of the metals of the first metal layer (163) and the sacrificial layer (145). Accordingly, the first metal layer (163) and the sacrificial layer (145) can be directly bonded without a separate bonding material.

[0113] Accordingly, the second embodiment has the technical effect of being able to bond a semiconductor light-emitting element to a transfer substrate without using an organic material through the metal bonding of the sacrificial layer (145) and the first metal layer (163). Accordingly, the second embodiment has the technical effect of being able to prevent the organic material from acting as a foreign substance that interferes with transfer and preventing contamination of the semiconductor light-emitting element.

[0114]

[0115] Referring to Fig. 9, after the semiconductor light-emitting element bonded to the transfer substrate (160) is inverted, the growth substrate can be removed. Depending on the epi material, LLO (Laser-lift off) or CLO (Chemical-lift off) can be used to remove the growth substrate. In addition, a portion of the passivation layer (140) and the buffer layer located on the back of the semiconductor light-emitting element can be removed. Accordingly, the buffer layer can expose the back of the first conductive semiconductor layer (131).

[0116]

[0117] Referring to FIG. 10, a second electrode (135) may be placed on a first conductive semiconductor layer (131). Meanwhile, the second electrode (135) may include an ohmic contact layer. In addition, the second electrode (135) may include a magnetic layer.

[0118] Meanwhile, in the process of forming the second electrode (135), the 2-1 electrode (136) may be formed in an area of ​​the transfer substrate (160) where the semiconductor light-emitting element is not bonded. The 2-1 electrode (136) is the same electrode as the second electrode (135). The 2-1 electrode (136) may be spaced apart from the semiconductor light-emitting element. The 2-1 electrode (136) may remain even if the semiconductor light-emitting element is removed from the transfer substrate (160).

[0119] In addition, a side wiring (165) may be arranged on the second electrode (135). In addition, the side electrode (165) may be arranged to cover the second electrode (135). The side electrode (165) may include a region in contact with the second electrode (135) and a region in contact with the passivation layer (140). The side electrode (165) may overlap the first conductive semiconductor layer (131) in the horizontal direction.

[0120]

[0121] Referring to FIG. 11, the sacrificial layer (145) may be removed to separate the semiconductor light-emitting element (150) from the transfer substrate (160). The separated semiconductor light-emitting element (150) may be fluidly dispersed and assembled on an assembly substrate. Meanwhile, the transfer substrate (160) may include a bonding area (168) where the semiconductor light-emitting element (150) was bonded. The surface of the transfer substrate (160) may be exposed as is in the bonding area (168). In detail, a bonding material, for example, an organic material, may not be present in the bonding area (168). In addition, the transfer substrate (160) may include a second-first electrode (136) outside the bonding area (168). The distance between the second-first electrodes (136) arranged spaced apart from each other may correspond to the diameter of the semiconductor light-emitting element.

[0122] In addition, when the semiconductor light-emitting element is bonded and then separated while the first metal layer (163) is formed on the transfer substrate (160) in FIG. 8b, the first metal layer (163) may remain on the transfer substrate (160). In this case, the first metal layer (163) may be disposed on the transfer substrate (160), and the second-first electrode (136) may be disposed on the first metal layer (163). In addition, the surface of the first metal layer (163) may be exposed as is in the bonding area of ​​the transfer substrate (160).

[0123]

[0124] Fig. 12(a) is a drawing showing a transfer substrate of a semiconductor light-emitting device being studied internally. Referring to Fig. 12(a), the transfer substrate of the semiconductor light-emitting device may have a semiconductor light-emitting device (50) bonded thereto. Meanwhile, an organic material is used during the bonding process, which reduces the stability of the bonding process and acts as a foreign substance, hindering the bonding of the semiconductor light-emitting device. Accordingly, as in region B, there is a problem in that the semiconductor light-emitting device is not bonded, resulting in a significant decrease in the transfer yield.

[0125] Meanwhile, Fig. 12(b) is a drawing showing a transfer substrate of a semiconductor light-emitting device to which an embodiment is applied. Referring to Fig. 12(b), in the embodiment, a semiconductor light-emitting device (150) may be bonded to a transfer substrate of a semiconductor light-emitting device without an organic material. Accordingly, the embodiment can improve the transfer yield by eliminating foreign matter factors, and the stability of the bonding process can be improved. In particular, the embodiment can significantly improve the bonding yield compared to Fig. 12(a), which has been studied internally.

[0126]

[0127] The method for transferring a semiconductor light-emitting element for a display pixel according to an embodiment has a technical effect of simplifying the transfer process of the semiconductor light-emitting element.

[0128] For example, the embodiment can simplify the transfer process by performing the bonding process without organic patterning.

[0129] In addition, the embodiment has a technical effect of preventing contamination of a semiconductor light-emitting element during a transfer process.

[0130] For example, the embodiment can prevent contamination of a semiconductor light-emitting device because the bonding process is performed without forming an organic substance that acts as a foreign substance in the fluid.

[0131] Additionally, the embodiment has a technical effect of preventing misalignment of a miniaturized chip.

[0132] For example, the embodiment can prevent the problem of chip misalignment due to the fluidity of organic materials during bonding.

[0133] In addition, the embodiment has a technical effect that can improve the transfer rate of a semiconductor light-emitting device.

[0134] For example, the embodiment can prevent foreign substances from penetrating into the assembly hole and interfering with the transfer of the semiconductor light-emitting element.

[0135]

[0136] 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.

[0137] 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 method for transferring a semiconductor light-emitting device including a first conductive semiconductor layer, an active layer disposed on the first conductive semiconductor layer, a light-emitting structure including a second conductive semiconductor layer disposed on the active layer, and a passivation layer disposed on the light-emitting structure, A step of forming a sacrificial layer on the semiconductor light-emitting element; and A step of bonding the semiconductor light-emitting element to a transfer substrate through the sacrificial layer; The sacrificial layer is disposed between the semiconductor light-emitting element and the transfer substrate. A method for transferring a semiconductor light-emitting element for a display pixel.

2. In paragraph 1, A transfer method for a semiconductor light-emitting element for a display pixel, wherein no organic material is placed between the semiconductor light-emitting element and the transfer substrate.

3. In paragraph 1, A method for transferring a semiconductor light-emitting element for a display pixel, wherein the sacrificial layer (145) comprises any one of Al, Cu, Ag, Au, Ni, Pt, W, Ti, Mo, Fe, Co, Sn, Zn, Pb, Mg, carbon steel, Inconel, and stainless steel.

4. In paragraph 1, A transfer method for a semiconductor light-emitting element for a display pixel, wherein the transfer substrate further includes a first metal layer.

5. In paragraph 4, A transfer method for a semiconductor light-emitting element for a display pixel, wherein the first metal layer comprises the same metal as the sacrificial layer.

6. In paragraph 1, A transfer method for a semiconductor light-emitting element for a display pixel, further comprising a step of forming a second electrode on the rear surface of the first conductive semiconductor layer.

7. In paragraph 6, A method for transferring a semiconductor light-emitting element for a display pixel, further comprising the step of forming a side electrode on the rear surface of the second electrode.

8. In paragraph 7, The above transfer substrate includes a bonding region, which is a region where the semiconductor light-emitting element is bonded, A transfer method for a semiconductor light-emitting element for a display pixel, comprising a second electrode arranged outside a bonding area of ​​the above transfer substrate.

9. In paragraph 1, Further comprising a step of removing the sacrificial layer to separate the semiconductor light emitting element from the transfer substrate, A method for transferring a semiconductor light-emitting element for a display pixel, wherein the bonding area of ​​the above transfer substrate exposes the surface of the above transfer substrate.

10. In paragraph 1, A method for transferring a semiconductor light-emitting element for a display pixel, wherein the step of bonding the semiconductor light-emitting element to a transfer substrate is performed at a pressure within a range of 100 to 1000 and 500 N to 100 kN.

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