Light-emitting diode, display device using same, and manufacturing method therefor

Abstract

The present invention is applicable to the technical field related to display devices, and relates to, for example, a micro light-emitting diode (LED), a display device using same, and a manufacturing method therefor. The present invention may include: a first conductivity type semiconductor layer; a second conductivity type semiconductor layer; an active layer positioned between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; a first contact layer at least a portion of which is discontinuously and electrically connected to a first surface of the first conductivity type semiconductor layer; and a reflective layer positioned on the first contact layer.

Description

Light-emitting element, display device using same, and manufacturing method thereof

[0001] The present invention is applicable to the technical field related to display devices, and relates to, for example, a micro LED (Light Emitting Diode), a display device using the same, and a manufacturing method thereof.

[0002] Recently, display devices with superior characteristics, such as thinness and flexibility, are being developed in the display technology field. In contrast, the major displays currently commercialized are represented by LCD (Liquid Crystal Display) and OLED (Organic Light Emitting Diode).

[0003] However, in the case of LCD, there are problems such as slow response time and difficulty in implementing flexibility, and in the case of OLED, there are problems such as short lifespan and poor mass production yield.

[0004] Meanwhile, a light-emitting diode (LED) is a semiconductor light-emitting device well known for converting electric current into light. Starting with the commercialization of a red LED using a GaAsP compound semiconductor in 1962, it has been used as a light source for display images in electronic devices including information and communication devices, along with a green LED of the GaP:N series. Therefore, a method for solving the above-mentioned problem by implementing a display using a semiconductor light-emitting device can be presented. The semiconductor light-emitting device has various advantages such as a long lifespan, low power consumption, excellent initial driving characteristics, and high vibration resistance compared to a filament-based light-emitting device.

[0005] The AuGe alloy metal, commonly used to enhance the electrical properties of the n-type electrode of LEDs, has low reflectivity. Furthermore, after heat treatment to form an ohmic contact, the reflectivity of the AuGe alloy decreases by approximately 20%.

[0006] To improve this, various metal layer structures are being attempted, but it is difficult to simultaneously satisfy electrical and optical properties.

[0007] To address this issue, a configuration has been proposed that forms a partial ohmic contact and a reflective film over the remaining portion. However, structural implementation is challenging due to the microscopic size of the light-emitting element chip.

[0008] In addition, a reflective film covering the entire n-type semiconductor layer in the form of an alloy has been proposed, but the reflection efficiency may be lower than that of a single metal.

[0009] In addition, the gold (Au) reflective film, which is mainly used in red light-emitting devices, is expensive to manufacture, and inter-diffusion with aluminum (Al), which is used as a bridge metal in display devices, can occur, forming a non-uniform inter-metallic compound (IMC).

[0010] Due to the rapid diffusion rate at the Al-Au interface, Kirkendall voids can form in the Au-rich region. These voids not only increase resistance by reducing the area through which current can flow, but can also cause long-term reliability issues.

[0011] Therefore, a solution to these problems is required.

[0012] The technical problem to be solved by the present invention is to provide a light-emitting element capable of improving the light extraction efficiency of the light-emitting element and thereby improving the efficiency of the display device, a display device using the same, and a manufacturing method thereof.

[0013] In addition, the present invention aims to provide a light-emitting element capable of improving the light extraction efficiency of a red light-emitting element, thereby improving the efficiency of a display device, a display device using the same, and a manufacturing method thereof.

[0014] In addition, the present invention seeks to provide a light-emitting element capable of improving reflectivity along with ohmic contact characteristics of the light-emitting element, a display device using the same, and a manufacturing method thereof.

[0015] Meanwhile, the present invention aims to provide a light-emitting element capable of improving problems related to panel reliability (e.g., increased resistance, weakness, degradation, etc.) that may be caused by non-uniform alloys that may occur during the formation of connecting electrodes in the panel process, a display device using the same, and a manufacturing method thereof.

[0016] Furthermore, the purpose of one embodiment of the present invention is to solve various problems not mentioned herein. Those skilled in the art will understand the full scope of the invention through the specification and drawings.

[0017] As a first aspect for achieving the above object, the present invention can be configured to include a first conductive semiconductor layer; a second conductive semiconductor layer; an active layer positioned between the first conductive semiconductor layer and the second conductive semiconductor layer; a first contact layer at least a portion of which is discontinuously electrically connected to a first surface of the first conductive semiconductor layer; and a reflective layer positioned on the first contact layer.

[0018] As an exemplary embodiment, the first contact layer can form an ohmic contact with the first conductive semiconductor layer at a portion that is electrically discontinuously connected to the first surface.

[0019] As an exemplary embodiment, the ohmic contact may be one in which at least a portion of the first contact layer is diffused into the first conductive semiconductor layer.

[0020] As an exemplary embodiment, the first contact layer may include a first metal forming an ohmic contact with the first conductive semiconductor layer; and a second metal diffusing the first metal.

[0021] As an exemplary embodiment, the first metal and the second metal may form an alloy.

[0022] As an exemplary embodiment, the first metal may include a region diffused into the first conductive semiconductor layer.

[0023] As an exemplary embodiment, an interface may exist between the first contact layer and the reflective layer.

[0024] As an exemplary embodiment, the reflective layer may be formed of a single metal layer including Ag.

[0025] As an exemplary embodiment, the first metal may include Ge and the second metal may include Au.

[0026] As an exemplary embodiment, the reflective layer may further include a magnetic layer positioned on the reflective layer.

[0027] As an exemplary embodiment, the second contact layer may further be positioned on a second surface opposite to the first surface with respect to the active layer and electrically connected to the first conductive semiconductor layer.

[0028] As an exemplary embodiment, the first contact layer may occupy an area of ​​5 to 20% of the total area of ​​the first surface.

[0029] As a second aspect for achieving the above object, the present invention provides a method for manufacturing a light-emitting device including a semiconductor layer including a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer positioned between the first conductive semiconductor layer and the second conductive semiconductor layer, the method comprising: forming a first contact layer on the first conductive semiconductor layer; and forming a reflective layer on the first metal layer, wherein the forming of the first contact layer may include: forming a first layer on the first conductive semiconductor layer in which a first metal and a second metal form an alloy; forming a second layer including the second metal on the first layer; performing a heat treatment; and removing the second layer.

[0030] As an exemplary embodiment, the step of forming the first contact layer may include the step of forming a photoresist layer that opens a first surface of the first conductive semiconductor layer; the step of continuously forming the first layer and the second layer on the first surface; and the step of removing the photoresist.

[0031] As an exemplary embodiment, the step of forming the first contact layer may be performed while the second conductive semiconductor layer is attached to the transfer substrate through the sacrificial layer.

[0032] As an exemplary embodiment, the method may further include forming a reflective layer on the surface from which the second layer has been removed.

[0033] As an exemplary embodiment, the method may further include forming a magnetic layer on the reflective layer.

[0034] As a third aspect for achieving the above object, the present invention provides a display device using a semiconductor light emitting element, comprising: a wiring substrate on which first electrodes are arranged; a light emitting element including a semiconductor layer disposed on the wiring substrate to form a unit subpixel; a first connection electrode electrically connecting the first electrode to one side of the semiconductor layer of the light emitting element; a planarization layer covering the light emitting element and the first connection electrode; and a second connection electrode positioned on the planarization layer and electrically connected to the other side of the semiconductor layer of the light emitting element, wherein the light emitting element may include a first contact layer at least a portion of which is electrically discontinuously connected to a first surface of the semiconductor layer; and a reflective layer positioned on the first contact layer.

[0035] According to one embodiment of the present invention, the following effects are achieved.

[0036] First, according to an embodiment of the present invention, the light extraction efficiency of the light emitting element can be improved by forming a metal for ohmic contact in some areas of a vertically structured light emitting element and forming a highly reflective metal in the remaining areas.

[0037] The first contact layer can further improve the hole extraction efficiency through the first surface by adding a rough surface to the lower surface (first surface) of the first conductive semiconductor layer.

[0038] Since this first contact layer mainly affects the formation of ohmic contact and rough surface, the consumption of material (particularly, gold (Au)) for forming the first contact layer can be significantly reduced.

[0039] Since the reflective layer is formed from a single metal without additional heat treatment, there may be no decrease in reflectivity due to alloy formation with surrounding materials during the heat treatment process.

[0040] Meanwhile, it is possible to improve problems related to panel reliability (e.g., increased resistance, weakness, degradation, etc.) that may arise due to non-uniform Au-Al alloy that may occur during the formation of connecting electrodes in the panel process.

[0041] Furthermore, according to another embodiment of the present invention, there are additional technical effects not mentioned herein. Those skilled in the art will understand the full scope of the specification and drawings.

[0042] Figure 1 is a conceptual diagram showing an example of a display device using a semiconductor light emitting element of the present invention.

[0043] Figure 2 is a partially enlarged view of part A of Figure 1.

[0044] Figures 3a and 3b are cross-sectional views taken along lines BB and CC of Figure 2.

[0045] Fig. 4 is a conceptual diagram showing the flip chip type semiconductor light emitting element of Fig. 3.

[0046] FIGS. 5A to 5C are conceptual diagrams showing various forms of implementing color in relation to a flip-chip type semiconductor light-emitting device.

[0047] Figure 6 is a cross-sectional view showing an example of a method for manufacturing a display device using a semiconductor light emitting element of the present invention.

[0048] Fig. 7 is a perspective view showing another example of a display device using a semiconductor light emitting element of the present invention.

[0049] Fig. 8 is a cross-sectional view taken along line DD of Fig. 7.

[0050] Fig. 9 is a conceptual diagram showing the vertical semiconductor light-emitting element of Fig. 8.

[0051] Fig. 10 is a cross-sectional view showing a light-emitting element according to one embodiment of the present invention.

[0052] Figure 11 is a graph showing the reflectivity according to wavelength of metals that can be used as a reflective layer.

[0053] FIGS. 12 to 19 are drawings for explaining a manufacturing process of a light-emitting element according to one embodiment of the present invention.

[0054] Figures 20 and 21 are photographs and analysis photographs showing examples in which the first contact layer is formed.

[0055] Fig. 22 is a cross-sectional view showing a display device using a light-emitting element according to one embodiment of the present invention.

[0056] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components will be given the same reference numbers, and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably only for the convenience of writing the specification, and do not in themselves have distinct meanings or roles. In addition, when describing the embodiments disclosed in this specification, if it is determined that a specific description of a related known technology may obscure the gist of the embodiments disclosed in this specification, a detailed description thereof will be omitted. In addition, it should be noted that the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and should not be construed as limiting the technical ideas disclosed in this specification by the attached drawings.

[0057] Furthermore, for the convenience of explanation, each drawing is described, but it is also within the scope of the present invention for a person skilled in the art to implement another embodiment by combining at least two drawings.

[0058] Additionally, when an element such as a layer, region or substrate is referred to as existing "on" another element, it will be understood that this may be directly on the other element, or that there may be intermediate elements in between.

[0059] The display device described in this specification is a concept that includes all display devices that display information as a unit pixel or a set of unit pixels. Therefore, it can be applied not only to finished products but also to components. For example, a panel corresponding to a component of a digital TV is also a display device in this specification. Finished products may include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, slate PCs, tablet PCs, Ultrabooks, digital TVs, desktop computers, etc.

[0060] However, those skilled in the art will readily recognize that the configuration according to the embodiments described herein may be applied to devices capable of displaying, even if they are new product types developed in the future.

[0061] The semiconductor light-emitting device mentioned in the specification includes LEDs, micro LEDs, etc., and may be used interchangeably.

[0062]

[0063] Figure 1 is a conceptual diagram showing an example of a display device using a semiconductor light emitting element of the present invention.

[0064] As illustrated in FIG. 1, information processed in the control unit (not shown) of the display device (100) can be displayed using a flexible display.

[0065] A flexible display includes, for example, a display that can be bent, curved, twisted, folded, or rolled by an external force.

[0066] Furthermore, a flexible display can be a display manufactured on a thin and flexible substrate that can be bent, folded, or rolled like paper, while maintaining the display characteristics of a conventional flat panel display, for example.

[0067] When the flexible display is not bent (e.g., when it has an infinite radius of curvature, hereinafter referred to as the first state), the display area of ​​the flexible display becomes a plane. When it is bent by an external force in this first state (e.g., when it has a finite radius of curvature, hereinafter referred to as the second state), the display area can become a curved surface. As illustrated in Fig. 1, information displayed in the second state can be visual information output on the curved surface. This visual information is implemented by independently controlling the light emission of sub-pixels arranged in a matrix form. Here, a sub-pixel means, for example, the smallest unit for implementing one color.

[0068] The unit pixels of such flexible displays can be implemented by semiconductor light-emitting elements. In the present invention, a light-emitting element is exemplified as a type of semiconductor light-emitting element that converts current into light. An example of a light-emitting element is a light-emitting diode (LED). Such a light-emitting diode is formed in a small size, thereby enabling it to function as a unit pixel even in the second state.

[0069] A flexible display implemented using such a light-emitting diode will be described in detail with reference to the drawings below.

[0070] Figure 2 is a partially enlarged view of part A of Figure 1.

[0071] Figures 3a and 3b are cross-sectional views taken along lines BB and CC of Figure 2.

[0072] As illustrated in FIGS. 2, 3a, and 3b, a display device (100) using a passive matrix (PM) type semiconductor light-emitting device is exemplified as a display device (100) using a semiconductor light-emitting device. However, the example described below can also be applied to an active matrix (AM) type semiconductor light-emitting device.

[0073] As illustrated in FIG. 2, the display device (100) includes a substrate (110), a first electrode (120), a conductive adhesive layer (130), a second electrode (140), and at least one semiconductor light emitting element (150).

[0074] The substrate (110) may be a flexible substrate. For example, to implement a flexible display device, the substrate (110) may include glass or polyimide (PI). In addition, any insulating and flexible material, such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET), may be used. Furthermore, the substrate (110) may be made of either a transparent or opaque material.

[0075] The substrate (110) can be a wiring substrate on which the first electrode (120) is arranged, and thus the first electrode (120) can be positioned on the substrate (110).

[0076] As illustrated in FIG. 3A, an insulating layer (160) may be placed on a substrate (110) where a first electrode (120) is positioned, and an auxiliary electrode (170) may be positioned on the insulating layer (160). In this case, a state in which the insulating layer (160) is laminated on the substrate (110) may become a single wiring board. More specifically, the insulating layer (160) may be made of an insulating and flexible material, such as polyimide (PI), PET, PEN, etc., and may be formed integrally with the substrate (110) to form a single substrate.

[0077] The auxiliary electrode (170) is an electrode that electrically connects the first electrode (120) and the semiconductor light emitting element (150), is located on the insulating layer (160), and is arranged corresponding to the position of the first electrode (120). For example, the auxiliary electrode (170) has a dot shape and can be electrically connected to the first electrode (120) by an electrode hole (171) penetrating the insulating layer (160). The electrode hole (171) can be formed by filling a conductive material in a via hole.

[0078] As illustrated in FIG. 2 or FIG. 3a, a conductive adhesive layer (130) is formed on one surface of the insulating layer (160), but the present invention is not necessarily limited thereto. For example, a layer performing a specific function may be formed between the insulating layer (160) and the conductive adhesive layer (130), or a structure in which the conductive adhesive layer (130) is disposed on the substrate (110) without the insulating layer (160) is also possible. In a structure in which the conductive adhesive layer (130) is disposed on the substrate (110), the conductive adhesive layer (130) may function as an insulating layer.

[0079] The conductive adhesive layer (130) may be a layer having adhesive and conductive properties, and for this purpose, a conductive material and an adhesive material may be mixed in the conductive adhesive layer (130). In addition, the conductive adhesive layer (130) has flexibility, thereby enabling a flexible function in the display device.

[0080] As an example, the conductive adhesive layer (130) may be an anisotropic conductive film (ACF), an anisotropic conductive paste, a solution containing conductive particles, etc. The conductive adhesive layer (130) may be configured as a layer that allows electrical interconnection in the Z direction penetrating the thickness, but has electrical insulation in the horizontal XY direction. Therefore, the conductive adhesive layer (130) may be referred to as a Z-axis conductive layer (however, hereinafter referred to as a 'conductive adhesive layer').

[0081] An anisotropic conductive film is a film in which an anisotropic conductive medium is mixed with an insulating base material, and when heat and / or pressure are applied, only a specific portion becomes conductive due to the anisotropic conductive medium. Hereinafter, the anisotropic conductive film is described as being subjected to heat and / or pressure, but other methods may be applied to partially make the anisotropic conductive film conductive. The other methods described above may include, for example, applying only one of heat and / or pressure, or UV curing.

[0082] In addition, the anisotropic conductive medium can be, for example, conductive balls or conductive particles. For example, an anisotropic conductive film is a film in which conductive balls are mixed with an insulating base member, and when heat and / or pressure are applied, only a specific portion becomes conductive due to the conductive balls. An anisotropic conductive film can be a state containing a plurality of particles in which a core of a conductive material is covered by an insulating film made of a polymer material, and in this case, a portion to which heat and pressure are applied becomes conductive due to the core as the insulating film is destroyed. At this time, the shape of the core can be deformed to form a layer that contacts each other in the thickness direction of the film. As a more specific example, heat and pressure are applied to the entire anisotropic conductive film, and an electrical connection in the Z-direction is partially formed due to the height difference of the counterpart to which the anisotropic conductive film is adhered.

[0083] As another example, an anisotropic conductive film may contain a plurality of particles coated with a conductive material on an insulating core. In this case, the conductive material deforms (sticks together) in the area where heat and pressure are applied, thereby providing conductivity in the thickness direction of the film. As another example, a conductive material may penetrate the insulating base member in the Z-axis direction, thereby providing conductivity in the thickness direction of the film. In this case, the conductive material may have pointed ends.

[0084] The anisotropic conductive film may be a fixed array anisotropic conductive film (ACF) configured with conductive balls inserted into one surface of an insulating base member. More specifically, the insulating base member is formed of an adhesive material, the conductive balls are concentratedly arranged on the bottom portion of the insulating base member, and when heat or pressure is applied to the base member, the conductive balls deform together with the conductive balls, thereby becoming conductive in the vertical direction.

[0085] However, the present invention is not necessarily limited thereto, and the anisotropic conductive film may be in a form in which conductive balls are randomly mixed into an insulating base member, or in a form in which conductive balls are arranged in one of the layers (double-ACF).

[0086] Anisotropic conductive paste is a combination of paste and conductive balls. It can be a paste in which conductive balls are mixed with an insulating and adhesive base material. Furthermore, the solution containing conductive particles can be a solution containing conductive particles or nanoparticles.

[0087] Referring again to FIG. 3a, the second electrode (140) is positioned on the insulating layer (160) and spaced apart from the auxiliary electrode (170). That is, the conductive adhesive layer (130) is positioned on the insulating layer (160) where the auxiliary electrode (170) and the second electrode (140) are positioned.

[0088] After forming a conductive adhesive layer (130) with the auxiliary electrode (170) and the second electrode (140) positioned on the insulating layer (160), when the semiconductor light-emitting element (150) is connected in a flip-chip form by applying heat and pressure, the semiconductor light-emitting element (150) is electrically connected to the first electrode (120) and the second electrode (140).

[0089] Fig. 4 is a conceptual diagram showing the flip chip type semiconductor light emitting element of Fig. 3.

[0090] Referring to FIG. 4, the semiconductor light-emitting element can be a flip chip type light-emitting element.

[0091] For example, a semiconductor light-emitting device includes a p-type electrode (156), a p-type semiconductor layer (155) on which the p-type electrode (156) is formed, an active layer (154) formed on the p-type semiconductor layer (155), an n-type semiconductor layer (153) formed on the active layer (154), and an n-type electrode (152) horizontally spaced apart from the p-type electrode (156) on the n-type semiconductor layer (153). In this case, the p-type electrode (156) can be electrically connected to the auxiliary electrode (170) and the conductive adhesive layer (130) as shown in FIGS. 3A and 3B, and the n-type electrode (152) can be electrically connected to the second electrode (140).

[0092] Referring again to FIGS. 2, 3a, and 3b, the auxiliary electrode (170) is formed to be elongated in one direction, so that one auxiliary electrode can be electrically connected to a plurality of semiconductor light-emitting elements (150). For example, the p-type electrodes of the semiconductor light-emitting elements on the left and right of the auxiliary electrode can be electrically connected to one auxiliary electrode.

[0093] More specifically, the semiconductor light-emitting element (150) is pressed into the interior of the conductive adhesive layer (130) by heat and pressure, and thereby conductivity is provided only in the portion between the p-type electrode (156) and the auxiliary electrode (170) of the semiconductor light-emitting element (150) and the portion between the n-type electrode (152) of the semiconductor light-emitting element (150) and the second electrode (140), and the remaining portions do not have conductivity because the semiconductor light-emitting element is not pressed in. In this way, the conductive adhesive layer (130) not only mutually connects the semiconductor light-emitting element (150) and the auxiliary electrode (170) and the semiconductor light-emitting element (150) and the second electrode (140) but also forms an electrical connection.

[0094] In addition, a plurality of semiconductor light-emitting elements (150) constitute a light-emitting element array, and a phosphor layer (180) is formed on the light-emitting element array.

[0095] The light-emitting element array may include a plurality of semiconductor light-emitting elements having different luminance values. Each semiconductor light-emitting element (150) constitutes a unit pixel and is electrically connected to a first electrode (120). For example, there may be a plurality of first electrodes (120), the semiconductor light-emitting elements may be arranged in, for example, several rows, and the semiconductor light-emitting elements in each row may be electrically connected to any one of the plurality of first electrodes.

[0096] In addition, since the semiconductor light-emitting devices are connected in a flip-chip configuration, semiconductor light-emitting devices grown on a transparent dielectric substrate can be utilized. Furthermore, the semiconductor light-emitting devices may be, for example, nitride semiconductor light-emitting devices. Since the semiconductor light-emitting device (150) has excellent brightness, individual unit pixels can be configured even in a small size.

[0097] As illustrated in FIGS. 3A and 3B, a partition wall (190) may be positioned between the semiconductor light-emitting elements (150). In this case, the partition wall (190) may serve to separate individual unit pixels from each other and may be formed integrally with the conductive adhesive layer (130). For example, when the semiconductor light-emitting elements (150) are inserted into the anisotropic conductive film, the base member of the anisotropic conductive film may form a partition wall.

[0098] Additionally, if the base member of the anisotropic conductive film is black, the barrier rib (190) can have reflective properties and the contrast ratio can be increased without a separate black insulator.

[0099] As another example, a reflective barrier (190) may be provided separately. In this case, the barrier (190) may include a black or white insulator, depending on the purpose of the display device. When a barrier made of white insulator is used, the reflectivity may be enhanced, and when a barrier made of black insulator is used, the reflective properties may be maintained while simultaneously increasing the contrast ratio.

[0100] The phosphor layer (180) may be positioned on the outer surface of the semiconductor light-emitting element (150). For example, the semiconductor light-emitting element (150) is a blue semiconductor light-emitting element that emits blue (B) light, and the phosphor layer (180) performs the function of converting the blue (B) light into the color of a unit pixel. The phosphor layer (180) may be a red phosphor (181) or a green phosphor (182) that constitutes an individual pixel.

[0101] That is, at a position forming a red unit pixel, a red phosphor (181) capable of converting blue light into red (R) light may be laminated on a blue semiconductor light-emitting element, and at a position forming a green unit pixel, a green phosphor (182) capable of converting blue light into green (G) light may be laminated on a blue semiconductor light-emitting element. In addition, only a blue semiconductor light-emitting element may be used alone in a portion forming a blue unit pixel. In this case, red (R), green (G), and blue (B) unit pixels may form one pixel. More specifically, a phosphor of one color may be laminated along each line of the first electrode (120). Therefore, one line in the first electrode (120) may become an electrode that controls one color. That is, along the second electrode (140), red (R), green (G), and blue (B) may be sequentially arranged, thereby implementing a unit pixel.

[0102] However, the present invention is not necessarily limited thereto, and instead of a fluorescent substance, a semiconductor light-emitting element (150) and a quantum dot (QD) may be combined to implement unit pixels of red (R), green (G), and blue (B).

[0103] Additionally, a black matrix (191) may be placed between each of the phosphor layers to improve contrast. That is, the black matrix (191) may improve the contrast between light and dark.

[0104] However, the present invention is not necessarily limited to this, and other structures for implementing blue, red, and green may be applied.

[0105] FIGS. 5A to 5C are conceptual diagrams showing various forms of implementing color in relation to a flip-chip type semiconductor light-emitting device.

[0106] Referring to FIG. 5a, each semiconductor light-emitting element (150) can be implemented as a high-output light-emitting element that emits various colors including blue by using gallium nitride (GaN) as a main material and adding indium (In) and / or aluminum (Al).

[0107] In this case, the semiconductor light-emitting elements (150) may be red (R), green (G), and blue (B) semiconductor light-emitting elements to form unit pixels (sub-pixels), respectively. For example, red, green, and blue semiconductor light-emitting elements (R, G, B) are alternately arranged, and the red, green, and blue unit pixels form one pixel by the red, green, and blue semiconductor light-emitting elements, thereby enabling a full-color display to be implemented.

[0108] Referring to FIG. 5b, the semiconductor light-emitting element (150a) may be provided with a white light-emitting element (W) in which a yellow phosphor layer is provided for each individual element. In this case, in order to form a unit pixel, a red phosphor layer (181), a green phosphor layer (182), and a blue phosphor layer (183) may be provided on the white light-emitting element (W). In addition, a unit pixel may be formed by using a color filter in which red, green, and blue are repeated on the white light-emitting element (W).

[0109] Referring to FIG. 5c, the semiconductor light-emitting element (150b) can also have a structure in which a red phosphor layer (184), a green phosphor layer (185), and a blue phosphor layer (186) are provided on an ultraviolet light-emitting element (UV). In this way, the semiconductor light-emitting element can be used in the entire range from visible light to ultraviolet (UV), and can be expanded to the form of a semiconductor light-emitting element in which ultraviolet (UV) can be used as an excitation source of the upper phosphor.

[0110] Revisiting this example, semiconductor light-emitting elements are positioned on a conductive adhesive layer to form unit pixels in a display device. Because semiconductor light-emitting elements have excellent luminance, they can form individual unit pixels even in small sizes.

[0111] The size of such individual semiconductor light-emitting devices (150, 150a, 150b) may be, for example, a side length of 80 μm or less, and may be a rectangular or square device. In the case of a rectangular device, the size may be 20×80 μm or less.

[0112] In addition, even if a square semiconductor light-emitting element (150, 150a, 150b) with a side length of 10㎛ is used as a unit pixel, sufficient brightness is displayed to form a display device.

[0113] Therefore, as an example, if the unit pixel size is a rectangular pixel with one side being 600 ㎛ and the other side being 300 ㎛, the distance between the semiconductor light emitting elements (150, 150a, 150b) becomes relatively sufficiently large.

[0114] Therefore, in these cases, it is possible to implement a flexible display device having a high quality higher than HD quality.

[0115] The display device using the semiconductor light-emitting element described above can be manufactured using a novel manufacturing method. The manufacturing method will be described below with reference to FIG. 6.

[0116] Figure 6 is a cross-sectional view showing an example of a method for manufacturing a display device using a semiconductor light emitting element of the present invention.

[0117] As illustrated in Fig. 6, first, a conductive adhesive layer (130) is formed on an insulating layer (160) where an auxiliary electrode (170) and a second electrode (140) are positioned. The insulating layer (160) is laminated on a first substrate (110) to form a single substrate (or wiring substrate), and the first electrode (120), the auxiliary electrode (170), and the second electrode (140) are arranged on the wiring substrate. In this case, the first electrode (120) and the second electrode (140) may be arranged in a mutually orthogonal direction. In addition, in order to implement a flexible display device, the first substrate (110) and the insulating layer (160) may each include glass or polyimide (PI).

[0118] The conductive adhesive layer (130) can be implemented, for example, by an anisotropic conductive film, and for this purpose, the anisotropic conductive film can be applied to the substrate on which the insulating layer (160) is positioned.

[0119] Next, a second substrate (112) corresponding to the positions of the auxiliary electrodes (170) and the second electrodes (140) and having a plurality of semiconductor light-emitting elements (150) constituting individual pixels is positioned so that the semiconductor light-emitting elements (150) face the auxiliary electrodes (170) and the second electrodes (140).

[0120] In this case, the second substrate (112) is a growth substrate for growing a semiconductor light-emitting element (150), and may be a sapphire substrate or a silicon substrate.

[0121] Semiconductor light emitting elements can be effectively used in display devices by having a spacing and size that can form a display device when formed in wafer units.

[0122] Next, the wiring board and the second substrate (112) are thermally compressed. For example, the wiring board and the second substrate (112) can be thermally compressed by applying an ACF press head. The wiring board and the second substrate (112) are bonded by thermal compression. Due to the characteristics of the anisotropic conductive film having conductivity by thermal compression, only the portion between the semiconductor light-emitting element (150) and the auxiliary electrode (170) and the second electrode (140) becomes conductive, and through this, the electrodes and the semiconductor light-emitting element (150) can be electrically connected. At this time, the semiconductor light-emitting element (150) is inserted into the anisotropic conductive film, and through this, a partition wall can be formed between the semiconductor light-emitting elements (150).

[0123] Next, the second substrate (112) is removed. For example, the second substrate (112) can be removed using a laser lift-off (LLO) method or a chemical lift-off (CLO) method.

[0124] Finally, the second substrate (112) is removed to expose the semiconductor light-emitting elements (150) to the outside. If necessary, the wiring substrate to which the semiconductor light-emitting elements (150) are coupled may be coated with silicon oxide (SiOx) or the like to form a transparent insulating layer (not shown).

[0125] In addition, a step of forming a phosphor layer on one surface of the semiconductor light-emitting element (150) may be further included. For example, the semiconductor light-emitting element (150) is a blue semiconductor light-emitting element that emits blue (B) light, and a red phosphor or a green phosphor for converting the blue (B) light into the color of a unit pixel may be formed as a layer on one surface of the blue semiconductor light-emitting element.

[0126] The manufacturing method and structure of the display device using the semiconductor light-emitting element described above can be modified in various ways. For example, a vertical semiconductor light-emitting element can also be applied to the display device described above.

[0127] In addition, in the modified examples or embodiments described below, the same or similar reference numbers are given to the same or similar configurations as the previous examples, and the description thereof is replaced with the first description.

[0128] FIG. 7 is a perspective view showing another embodiment of a display device using a semiconductor light-emitting element of the invention, FIG. 8 is a cross-sectional view taken along line DD of FIG. 7, and FIG. 9 is a conceptual diagram showing the vertical semiconductor light-emitting element of FIG. 8.

[0129] Referring to these drawings, the display device may be a display device using a vertical semiconductor light-emitting element of the passive matrix (PM) method.

[0130] The display device includes a substrate (210), a first electrode (220), a conductive adhesive layer (230), a second electrode (240), and at least one semiconductor light emitting element (250).

[0131] The substrate (210) is a wiring substrate on which the first electrode (220) is arranged, and may include polyimide (PI) to implement a flexible display device. In addition, any material that is insulating and flexible may be used.

[0132] The first electrode (220) is positioned on the substrate (210) and may be formed as a long bar-shaped electrode in one direction. The first electrode (220) may be configured to function as a data electrode.

[0133] The conductive adhesive layer (230) is formed on the substrate (210) where the first electrode (220) is positioned. As in a display device to which a flip chip type light-emitting element is applied, the conductive adhesive layer (230) may be an anisotropic conductive film (ACF), an anisotropic conductive paste, a solution containing conductive particles, etc. However, in the present embodiment, a case in which the conductive adhesive layer (230) is implemented by an anisotropic conductive film is exemplified.

[0134] After positioning the anisotropic conductive film with the first electrode (220) positioned on the substrate (210), when the semiconductor light-emitting element (250) is connected by applying heat and pressure, the semiconductor light-emitting element (250) is electrically connected to the first electrode (220). At this time, it is preferable that the semiconductor light-emitting element (250) be positioned so as to be positioned on the first electrode (220).

[0135] As described above, such electrical connections are created because, when heat and pressure are applied to an anisotropic conductive film, it becomes partially conductive along its thickness. Therefore, the anisotropic conductive film is divided into a conductive portion and a non-conductive portion along its thickness.

[0136] In addition, since the anisotropic conductive film contains an adhesive component, the conductive adhesive layer (230) implements not only electrical connection but also mechanical bonding between the semiconductor light-emitting element (250) and the first electrode (220).

[0137] In this way, the semiconductor light-emitting element (250) is positioned on the conductive adhesive layer (230), thereby forming individual pixels in the display device. Since the semiconductor light-emitting element (250) has excellent brightness, it can form individual unit pixels even with a small size. The size of the individual semiconductor light-emitting element (250) may be, for example, a side length of 80 μm or less, and may be a rectangular or square element. In the case of a rectangular element, the size may be, for example, 20 X 80 μm or less.

[0138] These semiconductor light emitting elements (250) can have a vertical structure.

[0139] Between the vertical semiconductor light-emitting elements, a plurality of second electrodes (240) are positioned in a direction intersecting the longitudinal direction of the first electrode (220) and electrically connected to the vertical semiconductor light-emitting elements (250).

[0140] Referring to FIG. 9, this vertical semiconductor light-emitting device includes a p-type electrode (256), a p-type semiconductor layer (255) formed on the p-type electrode (256), an active layer (254) formed on the p-type semiconductor layer (255), an n-type semiconductor layer (253) formed on the active layer (254), and an n-type electrode (252) formed on the n-type semiconductor layer (253). In this case, the p-type electrode (256) located at the bottom can be electrically connected to the first electrode (220) by a conductive adhesive layer (230), and the n-type electrode (252) located at the top can be electrically connected to the second electrode (240) described below. This vertical semiconductor light-emitting device (250) has a great advantage in that the chip size can be reduced because the electrodes can be arranged vertically.

[0141] Referring again to FIG. 8, a phosphor layer (280) may be formed on one surface of a semiconductor light-emitting element (250). For example, the semiconductor light-emitting element (250) may be a blue semiconductor light-emitting element (251) that emits blue (B) light, and a phosphor layer (280) may be provided to convert the blue (B) light into the color of a unit pixel. In this case, the phosphor layer (280) may be a red phosphor (281) and a green phosphor (282) that constitute individual pixels.

[0142] That is, at a position forming a red unit pixel, a red phosphor (281) capable of converting blue light into red (R) light may be laminated on a blue semiconductor light-emitting element, and at a position forming a green unit pixel, a green phosphor (282) capable of converting blue light into green (G) light may be laminated on a blue semiconductor light-emitting element. In addition, only a blue semiconductor light-emitting element may be used alone in a portion forming a blue unit pixel. In this case, red (R), green (G), and blue (B) unit pixels may form one pixel.

[0143] However, the present invention is not necessarily limited thereto, and other structures for implementing blue, red, and green colors may be applied as described above in a display device to which a flip chip type light-emitting element is applied.

[0144] Looking again at the present embodiment, the second electrode (240) is positioned between the semiconductor light-emitting elements (250) and is electrically connected to the semiconductor light-emitting elements (250). For example, the semiconductor light-emitting elements (250) may be arranged in multiple rows, and the second electrode (240) may be positioned between the rows of the semiconductor light-emitting elements (250).

[0145] Since the distance between the semiconductor light-emitting elements (250) forming individual pixels is sufficiently large, the second electrode (240) can be positioned between the semiconductor light-emitting elements (250).

[0146] The second electrode (240) can be formed as a long bar-shaped electrode in one direction and can be arranged in a direction perpendicular to the first electrode.

[0147] In addition, the second electrode (240) and the semiconductor light-emitting element (250) can be electrically connected by a connecting electrode protruding from the second electrode (240). More specifically, the connecting electrode can be an n-type electrode of the semiconductor light-emitting element (250). For example, the n-type electrode is formed as an ohmic electrode for ohmic contact, and the second electrode (240) covers at least a portion of the ohmic electrode by printing or deposition. Through this, the second electrode (240) and the n-type electrode of the semiconductor light-emitting element (250) can be electrically connected.

[0148] Referring again to FIG. 8, the second electrode (240) may be positioned on the conductive adhesive layer (230). In some cases, a transparent insulating layer (not shown) including silicon oxide (SiOx) or the like may be formed on the substrate (210) on which the semiconductor light emitting element (250) is formed. When the second electrode (240) is positioned after the transparent insulating layer is formed, the second electrode (240) is positioned on the transparent insulating layer. In addition, the second electrode (240) may be formed spaced apart from the conductive adhesive layer (230) or the transparent insulating layer.

[0149] If a transparent electrode such as ITO (Indium Tin Oxide) is used to position the second electrode (240) on the semiconductor light emitting element (250), the ITO material has a problem in that it has poor adhesion to the n-type semiconductor layer. Therefore, the present invention has an advantage in that it is not necessary to use a transparent electrode such as ITO by positioning the second electrode (240) between the semiconductor light emitting elements (250). Accordingly, without being restricted by the selection of a transparent material, it is possible to improve the light extraction efficiency by using a conductive material having good adhesion to the n-type semiconductor layer as a horizontal electrode.

[0150] Referring back to FIG. 8, a partition wall (290) may be positioned between the semiconductor light-emitting elements (250). That is, the partition wall (290) may be positioned between the vertical semiconductor light-emitting elements (250) to isolate the semiconductor light-emitting elements (250) forming individual pixels. In this case, the partition wall (290) may serve to separate the individual unit pixels from each other and may be formed integrally with the conductive adhesive layer (230). For example, when the semiconductor light-emitting elements (250) are inserted into the anisotropic conductive film, the base member of the anisotropic conductive film may form the partition wall (290).

[0151] In addition, if the base member of the anisotropic conductive film is black, the barrier rib (290) can have reflective properties and the contrast ratio can be increased without a separate black insulator.

[0152] As another example, a reflective barrier (290) may be provided separately. The barrier (290) may include a black or white insulator depending on the purpose of the display device.

[0153] If the second electrode (240) is positioned directly on the conductive adhesive layer (230) between the semiconductor light-emitting elements (250), the partition wall (290) can be positioned between the vertical semiconductor light-emitting elements (250) and the second electrode (240). Therefore, individual unit pixels can be configured even in a small size using the semiconductor light-emitting elements (250), and the distance between the semiconductor light-emitting elements (250) can be made relatively large enough so that the second electrode (240) can be positioned between the semiconductor light-emitting elements (250), thereby achieving the effect of implementing a flexible display device having HD picture quality.

[0154] Additionally, as illustrated in FIG. 8, a black matrix (291) may be placed between each fluorescent substance to improve contrast. That is, the black matrix (291) may improve the contrast between light and dark.

[0155] In the display device using the semiconductor light-emitting element of the present invention described above, the semiconductor light-emitting element is placed on a wiring board in a flip chip type and used as an individual pixel.

[0156]

[0157] Fig. 10 is a cross-sectional view showing a light-emitting element according to one embodiment of the present invention.

[0158] Referring to Fig. 10, a light-emitting element (330) according to one embodiment of the present invention may include a semiconductor layer including a first conductive semiconductor layer (331), a second conductive semiconductor layer (332), and an active layer (333) positioned between the first conductive semiconductor layer (331) and the second conductive semiconductor layer (332). The horizontal cross-sectional shape of this semiconductor layer may be any one of a circular, elliptical, or polygonal shape.

[0159] For example, the first conductivity type may be n-type. Accordingly, the second conductivity type may be p-type. Hereinafter, embodiments of the present invention will be described based on an example in which the first conductivity type is n-type and the second conductivity type is p-type. For example, the first conductivity type semiconductor layer (331) may be an n-type semiconductor layer and the second conductivity type semiconductor layer (332) may be a p-type semiconductor layer. However, embodiments of the present invention are not limited thereto. That is, as another example, the first conductivity type semiconductor layer (331) may be a p-type semiconductor layer and the second conductivity type semiconductor layer (332) may be an n-type semiconductor layer.

[0160] As an exemplary embodiment, the light-emitting element may be a red light-emitting element for emitting red light. Such a red light-emitting element may include a semiconductor of the GaAs or InP series. For example, the red light-emitting element may include a compound semiconductor material composed of a combination of at least one of In, Ga, As, and P. However, embodiments of the present invention are not limited thereto.

[0161] In addition, a light emitting element (330) according to one embodiment of the present invention may be configured to include a first contact layer (335) at least part of which is discontinuously electrically connected to a first surface of a first conductive semiconductor layer (331) and a reflective layer (336) positioned on the first contact layer (335).

[0162] In this way, the first contact layer (335) can be electrically connected at least partially to the first conductive semiconductor layer (331). Here, discontinuous or at least partially can mean that the first contact layer (335) is in discontinuous contact at least partially with the lower surface (first surface) of the first conductive semiconductor layer (331) as shown in FIG. 10, i.e., the surface (first surface) facing the reflective layer (336).

[0163] For example, the first contact layer (335) may be positioned so as to form an ohmic contact with the first conductive semiconductor layer (331) partially without covering the entire lower surface (first surface) of the first conductive semiconductor layer (331). In this case, a reflective layer (336) is positioned on the lower surface (first surface) of the first conductive semiconductor layer (331) where the first contact layer (335) is not positioned, so that the reflectivity of the light-emitting element can be maintained without being significantly reduced by the first contact layer (335).

[0164] As an exemplary embodiment, the first contact layer (335) may occupy an area of ​​5 to 20% of the total area of ​​the lower surface (first surface) of the first conductive semiconductor layer (331).

[0165] The portion where the first contact layer (335) forms an ohmic contact with the first conductive semiconductor layer (331) may be a portion of the first contact layer (335) that has been diffused into the first conductive semiconductor layer (331).

[0166] As an exemplary embodiment, the first contact layer (335) may include a first metal forming an ohmic contact with the first conductive semiconductor layer (331) and a second metal for diffusing the first metal. For example, the first metal and the second metal may form an alloy.

[0167] In this way, the first metal forming the first contact layer (335) may include a region (diffusion region) diffused into the first conductive semiconductor layer (331).

[0168] For example, the first metal may include Ge, and the second metal may include Au. For example, the first contact layer (335) may form an alloy of gold (Au) and germanium (Ge). In other words, the first contact layer (335) may include an AuGe material.

[0169] Here, Ge can diffuse into the first conductive semiconductor layer (331) to form an ohmic contact with the first conductive semiconductor layer (331). Au can help Ge to spread evenly on the first surface without agglomerating.

[0170] This will be described in more detail later.

[0171] As an exemplary embodiment, an interface may exist between the first contact layer (335) and the reflective layer (336). For example, the first contact layer (335) and the reflective layer (336) may exist as separate layers without forming an alloy.

[0172] For example, the reflective layer (336) may be formed as a single metal layer including silver (Ag). Fig. 11 is a graph showing the reflectivity according to the wavelength of metals that can be used as the reflective layer. Referring to Fig. 11, Ag may have a relatively high reflectivity for red light. For example, Ag may have a higher reflectivity for red light, for example, light having a wavelength of 600 nm or more, than gold (Au), aluminum (Al), and copper (Cu).

[0173] Ag has a slower alloy formation rate than Au and is characterized by uniform formation. Furthermore, its superior thermal / electrical properties compared to Au facilitate current flow without overheating even with a small contact area. Furthermore, it can be advantageous in terms of reliability because voids are not formed.

[0174] In this way, the first contact layer (335) may be positioned in a relatively inner region of the lower surface (first surface) of the first conductive semiconductor layer (331), and the reflective layer (336) may be positioned in a relatively outer region.

[0175] As an exemplary embodiment, a light emitting element (330) according to one embodiment of the present invention may further include a magnetic layer (337) positioned on a reflective layer (336).

[0176] To be used as a subpixel of a display device, the light-emitting element (330) may be assembled using magnetism on a wiring board (310; see FIG. 22) or a separate assembly board (not shown). For example, the light-emitting element (330) may be assembled using magnetism in a fluid phase. Accordingly, the magnetic layer (337) may assist in the process of assembling the light-emitting element (330) using magnetism. A detailed description thereof will be omitted.

[0177] As an exemplary embodiment, a light emitting element (330) according to one embodiment of the present invention may further include a second contact layer (334) positioned on a second surface (upper surface) opposite to the first surface (lower surface) with respect to the active layer (333), and electrically connected to the second conductive semiconductor layer.

[0178] For example, the light emitting element (330) may include a passivation layer (338) to protect the outer surface from electrical shock. This passivation layer (338) may be partially removed during the assembly process or the wiring connection process.

[0179] The AuGe alloy metal, commonly used to improve the electrical properties of n-type electrodes, has low reflectivity. Furthermore, after heat treatment to form an ohmic contact, the reflectivity of the AuGe alloy decreases by approximately 20%.

[0180] To improve this, various metal layer structures are being attempted, but it is difficult to simultaneously satisfy electrical and optical properties.

[0181] To address this issue, a configuration has been proposed that forms a partial ohmic contact and a reflective film over the remaining portion. However, structural implementation is challenging due to the microscopic size of the light-emitting element chip.

[0182] In addition, a reflective film covering the entire n-type semiconductor layer in the form of an alloy has been proposed, but the reflection efficiency may be lower than that of a single metal.

[0183] In addition, the gold (Au) reflective film, which is mainly used in red light-emitting devices, is expensive to manufacture, and inter-diffusion with aluminum (Al), which is used as a bridge metal in display devices, can occur, forming a non-uniform inter-metallic compound (IMC).

[0184] Due to the rapid diffusion rate at the Al-Au interface, Kirkendall voids can form in the Au-rich region. These voids not only increase resistance by reducing the area through which current can flow, but can also cause long-term reliability issues.

[0185] However, according to this embodiment of the present invention, as described above, a metal (first contact layer (335)) for ohmic contact is formed in some areas of the lower surface (first surface) of the first conductive semiconductor layer (331) for forming an n-contact of the light-emitting element (330) of a vertical structure, and a highly reflective metal (reflective layer (336)) is formed in the remaining areas, thereby improving the light extraction efficiency of the light-emitting element (330).

[0186] The first contact layer (335) can further improve the hole extraction efficiency through the first surface by adding a rough surface to the lower surface (first surface) of the first conductive semiconductor layer (331).

[0187] Since this first contact layer (335) mainly affects the formation of ohmic contact and rough surface, the consumption of material (particularly, gold (Au)) for forming the first contact layer (335) can be greatly reduced.

[0188] Since the reflective layer (336) is formed of a single metal without additional heat treatment, a decrease in reflectivity due to alloy formation with surrounding materials during the heat treatment process may not occur.

[0189] Meanwhile, it is possible to improve problems related to panel reliability (e.g., increased resistance, weakness, degradation, etc.) that may be caused by non-uniform Au-Al alloy that may occur when forming a connecting electrode (342; see Fig. 22) in the panel process.

[0190]

[0191] Figures 12 to 19 are drawings for explaining a manufacturing process of a light-emitting element according to one embodiment of the present invention. Of these, Figures 16 and 18 are photographs showing a contact surface.

[0192] Hereinafter, with reference to FIGS. 12 to 19, a manufacturing process of a light-emitting element (330) according to one embodiment of the present invention will be described step by step.

[0193] First, referring to FIG. 12, a light-emitting element (330) structure including a semiconductor layer including a first conductive semiconductor layer (331), a second conductive semiconductor layer (332), and an active layer (333) can be processed while attached to a transfer substrate (400) by a bonding layer (410).

[0194] For example, a sacrificial layer (420) may be positioned between the bonding layer (410) and the light-emitting element (330). The sacrificial layer (420) is usually a metal material, and the light-emitting element (330) can be separated from the transfer substrate (400) by removing the sacrificial layer (420) later.

[0195] The light-emitting element (330) on which the contact process has been performed can be dispersed in a fluid and assembled into a wiring substrate (310) as the sacrificial layer (420) is removed. At this time, the light-emitting element (330) can be assembled into the wiring substrate (310) by magnetic force and dielectrophoresis. A description of this specific process is omitted.

[0196] A first contact layer (335) can be formed on the lower surface of the light-emitting element (330). Hereinafter, the process of forming the first contact layer (335) will be described in detail.

[0197] First, in order to form the first contact layer, a photoresist layer (430) that opens the first surface (bottom surface) of the first conductive semiconductor layer (331) can be formed.

[0198] In a state where the light emitting element (330) structure is locally attached to the transfer substrate (400) via the sacrificial layer (420) and the bonding layer (410), the photoresist layer (430) can be formed in a state where a portion for forming the first contact layer is opened on the first surface (bottom surface) of the first conductive semiconductor layer (331). Accordingly, as illustrated in FIG. 12, the photoresist layer (430) can be formed by contacting the side surface of the light emitting element (330) structure, the sacrificial layer (420), and the bonding layer (410).

[0199] Thereafter, referring to FIG. 13, a metal layer (335') for forming a first contact layer including a first layer (335-1) and a second layer (335-2) can be continuously formed on the first surface (bottom surface) of the first conductive semiconductor layer (331).

[0200] Here, the first layer (335-1) may include a first metal forming an ohmic contact with the first conductive semiconductor layer (331) described above and a second metal for diffusing the first metal. For example, the first metal and the second metal may form an alloy.

[0201] For example, the first metal may include Ge, and the second metal may include Au. For example, the first layer (335-1) may form an alloy of gold (Au) and germanium (Ge). In other words, the first layer (335-1) may include an AuGe material. For example, the first layer (335-1) may be formed of AuGe. This first layer (335-1) may form a first contact layer (335) after a subsequent heat treatment process.

[0202] For example, the second layer (335-2) may include a second metal. For example, the second layer (335-2) may include a Au material. For example, the second layer (335-2) may be formed of Au.

[0203] Next, referring to FIG. 14, the photoresist layer (430) can be removed. Through this process, the first layer (335-1) and the second layer (335-2) are removed so that only an appropriate area remains, thereby forming a metal structure (335'') for forming a first contact layer.

[0204] This process can be called a self-alignment process. Therefore, it has the advantage of eliminating the need for additional processes and equipment for alignment in micrometer-sized light-emitting element (330) chips.

[0205] Afterwards, a heat treatment process may be performed. Through the heat treatment process, the first layer (335-1) may form a region (diffusion region) diffused into the first conductive semiconductor layer (331). Referring to FIG. 15, this diffused region may form an ohmic contact with the first conductive semiconductor layer (331) to form the first contact layer (335). For example, the heat treatment process may be performed in a temperature range of 350°C to 450°C. As another example, the heat treatment process may be performed in a temperature range of 370°C to 410°C. This heat treatment temperature range may be more advantageous in terms of reflectance characteristics.

[0206] As described above, for example, the first contact layer (335) may be formed of an alloy of gold (Au) and germanium (Ge). In other words, the first contact layer (335) may include an AuGe material.

[0207] Here, Ge can diffuse into the first conductive semiconductor layer (331) to form an ohmic contact with the first conductive semiconductor layer (331). Au can help Ge to spread evenly on the first surface without agglomerating.

[0208] Fig. 16 is a photograph showing the first surface (bottom surface) of the first conductive semiconductor layer (331) of circular light-emitting elements. In the state of Fig. 16, the second layer (335-2) is visible.

[0209] Afterwards, the second layer (335-2) can be removed. In this way, when the second layer (335-2) is removed, a state as in Fig. 17 can be achieved.

[0210] In this way, after the Ge diffusion region is formed through the heat treatment process, the remaining layer (second layer) can be removed. Once the ohmic contact region is formed through Ge diffusion, the remaining region has high light absorption and is therefore disadvantageous for reflection, so it can be removed.

[0211] Fig. 18 is a photograph showing the first surface (bottom surface) of the first conductive semiconductor layer (331) of circular light-emitting elements after the removal of the second layer (335-2). The part that appears as a stain in Fig. 18 may correspond to a Ge diffusion region. That is, the first conductive semiconductor layer (331) in this part may form an ohmic contact.

[0212] Referring to FIG. 19, after the removal of the second layer (335-2), a process of forming a reflective layer (336) on the surface from which the second layer (335-2) was removed can be performed.

[0213] This reflective layer (336) substantially covers the first surface (bottom surface) of the first conductive semiconductor layer (331), so that the entire area other than the Ge diffusion region can be used for reflection.

[0214] Thereafter, as an exemplary embodiment, a process of forming a magnetic layer (337) on the reflective layer (336) can be performed.

[0215] In this state, by removing the sacrificial layer (420) and separating the individual light-emitting elements (330), a light-emitting element (330) in a state as shown in FIG. 10 can be manufactured.

[0216]

[0217] Figures 20 and 21 are photographs and analysis photographs showing examples of the formation of the first contact layer. Figures 20 and 21 show the ohmic contact region (e.g., Ge diffusion region) according to the thickness change of the first layer (335-1) and the second layer (335-2).

[0218] For example, the diffusion shape of Ge may vary depending on the thickness and heat treatment temperature of the AuGe forming the first layer (335-1). Therefore, by controlling the thickness and heat treatment temperature, it is possible to control at least one of the area ratio of the ohmic contact region and the reflectivity of the light-emitting element.

[0219] For example, the thickness of the AuGe forming the first layer (335-1) may have a minimum thickness of 10 nm in consideration of the resistance characteristics. As an exemplary embodiment, the thickness of the AuGe forming the first layer (335-1) may be formed to a thickness of 10 nm to 50 nm. Accordingly, the first contact layer (335) may occupy an area of ​​5 to 20% of the total area of ​​the first surface.

[0220] First, Fig. 20 shows the state in which the first layer (335-1) and the second layer (335-2) are formed with a thickness of 30 nm / 30 nm, respectively.

[0221] Referring to Fig. 20(a), it is a photograph showing the first surface (bottom surface) of the first conductive semiconductor layer (331) of the circular light-emitting elements. Fig. 20(b) is an image showing the distribution of Ge atoms, and Fig. 20(c) is an image showing the distribution of Au atoms.

[0222] Figure 21 shows the state in which the first layer (335-1) and the second layer (335-2) are formed with a thickness of 50 nm / 50 nm, respectively.

[0223] Referring to Fig. 21(a), it is a photograph showing the first surface (bottom surface) of the first conductive semiconductor layer (331) of the circular light-emitting elements. Fig. 21(b) is an image showing the distribution of Ge atoms, and Fig. 21(c) is an image showing the distribution of Au atoms.

[0224] In this way, the area ratio of the ohmic contact region may vary depending on the increase in the thickness of the first layer (335-1) and the second layer (335-2). Accordingly, the reflectivity of the light-emitting element may also vary.

[0225]

[0226] Fig. 22 is a cross-sectional view showing a display device using a light-emitting element according to one embodiment of the present invention.

[0227] Referring to FIG. 22, a display device according to one embodiment of the present invention may be configured by arranging light-emitting elements (330) forming unit subpixels on a wiring board (310) on which first electrodes (312) are arranged. The wiring board (310) may include first electrodes (312) arranged on a substrate (311).

[0228] The wiring board (310) may have a plurality of first electrodes (312) positioned on the board (311). These first electrodes (312) may be used as wiring electrodes. The first electrodes (312) may be positioned in sections on the board (311). Here, the wiring electrodes may be used as data electrodes (pixel electrodes) or scan electrodes (common electrodes).

[0229] Although one light-emitting element (330) is illustrated in FIG. 22, light-emitting elements (330) forming three unit sub-pixels may constitute a unit pixel. In this case, the light-emitting elements (330) may include a red light-emitting element that emits red light, a green light-emitting element that emits green light, and a blue light-emitting element that emits blue light. These unit pixels may be repeatedly provided on the wiring board (310).

[0230] Although not shown, the first electrode (312) arranged on the wiring board (310) may be connected to a TFT layer equipped with a thin film transistor (TFT). A data electrode (pixel electrode) may be connected to this TFT layer. A detailed description thereof is omitted.

[0231] A partition wall (320) for forming an assembly hole for the light emitting element may be positioned between the wiring board (310) and the light emitting element (330).

[0232] As an exemplary embodiment, at least one of the upper and lower surfaces of the light-emitting element (330) may be circular. For example, the light-emitting element (330) may have a cylindrical shape or a truncated cone shape.

[0233] In order to provide vertical selectivity when assembling the light-emitting element (330), the lower area of ​​the light-emitting element (330) may be larger than the upper area. For example, the area of ​​the surface close to the first contact layer (335) of the light-emitting element (330) may be larger than the area of ​​the surface farther from the first contact layer (335).

[0234] Additionally, the display device (300) may include a first connection electrode (340) that electrically connects one side of the first electrode (312) and the light-emitting element (330). This first connection electrode (340) may be made of a metal with high electrical conductivity, such as Al, Mo, Cu, Ag, or Pt.

[0235] As an exemplary embodiment, one side of the light-emitting element (330) to which the first connection electrode (340) is connected may be a side surface with respect to the light-emitting layer (active layer; 333) of the light-emitting element (330). For example, the first connection electrode (340) may be connected laterally with respect to a surface formed by the light-emitting layer (333) of the light-emitting element (330). The first connection electrode (340) may extend to the side surface of the first conductive semiconductor layer (331) of the light-emitting element (330) to form a side surface portion (342) and may be electrically connected to the first conductive semiconductor layer (331).

[0236] At this time, aluminum (Al) used as the first connecting electrode (340) and the reflective layer (336) of the light-emitting element (330) can form an alloy. By forming this alloy, the thermal / electrical characteristics of the light-emitting element and the display device can be improved.

[0237] In this way, the first connecting electrode (340) may include a side portion (342) positioned on the side of the light-emitting element (330) and a lower portion (343) positioned on the upper surface of the mounting layer (320).

[0238] Referring to Fig. 22, the first connecting electrode (340) may be provided on both sides of the light-emitting element (330). In some cases, the first connecting electrode (340) may be provided to cover the side of the light-emitting element (330).

[0239] Additionally, this first connecting electrode (340) may be electrically connected to the magnetic layer (337) of the light-emitting element (330). A metal such as Cr and / or Ti may be added to increase the adhesive strength of at least one of this magnetic layer (337) and the first connecting electrode (340).

[0240] A passivation layer (338) may be positioned on the outside of the portion where the first connection electrode (340) is connected on the side of the light-emitting element (330). In this way, the passivation layer (338) may be positioned on the outside of the light-emitting element (330), and the first connection electrode (340) may be positioned below the passivation layer (338). This passivation layer (338) may protect the outer surface of the light-emitting element (330).

[0241] A planarization layer (350) may be positioned on the side of the first connecting electrode (340) and the light-emitting element (330). The planarization layer (350) may cover the first connecting electrode (340) and the light-emitting element (330). The planarization layer (350) may have a height corresponding to the upper side of the light-emitting element (330), or may be provided at a higher height.

[0242] At this time, the second conductive semiconductor layer (332) on the upper side of the light-emitting element (330) may be exposed. For example, even when the planarization layer (350) has a height higher than the upper side of the light-emitting element (330), the second conductive semiconductor layer (332) of the light-emitting element (330) may be exposed.

[0243] Additionally, a second connection electrode (361) may be positioned on the flattening layer (350) and electrically connected to the other side of the light-emitting element (330). For example, the second connection electrode (361) may include a transparent electrode such as ITO. Accordingly, light emitted from the light-emitting element (330) may pass through the second connection electrode (361) and be emitted to the outside.

[0244] As mentioned above, the first electrode (312) and the second electrode (360) can be used as wiring electrodes. For example, the first electrode (312) can function as a data electrode (pixel electrode), and the second electrode (360) can function as a scan electrode (common electrode).

[0245] Referring to Fig. 22, the second connecting electrode (361) may be partially positioned on the light emitting element (330). In some cases, these second connecting electrodes (361) may be connected to each other by the second electrode (360).

[0246]

[0247] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0248] Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention but to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments.

[0249] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0250] According to the present invention, a semiconductor light-emitting element such as a micro LED and a display device using the same can be provided.

Claims

1. First challenge type semiconductor layer; Second challenge type semiconductor layer; An active layer positioned between the first conductive semiconductor layer and the second conductive semiconductor layer; A first contact layer, at least a portion of which is electrically discontinuously connected to the first surface of the first conductive semiconductor layer; and A light-emitting device characterized by comprising a reflective layer positioned on the first contact layer.

2. A light emitting device characterized in that in the first paragraph, the first contact layer forms an ohmic contact with the first conductive semiconductor layer at a portion that is electrically connected discontinuously to the first surface.

3. In the first paragraph, the ohmic contact is a light-emitting device characterized in that at least a portion of the first contact layer is diffused into the first conductive semiconductor layer.

4. In the first paragraph, the first contact layer is A first metal forming an ohmic contact with the first conductive semiconductor layer; A light emitting device characterized by comprising a second metal that diffuses the first metal.

5. A light emitting device according to claim 4, characterized in that the first metal and the second metal form an alloy.

6. A light-emitting device according to claim 4, characterized in that the first metal includes a region diffused into the inside of the first conductive semiconductor layer.

7. A light emitting device characterized in that, in the fourth paragraph, there is a boundary surface between the first contact layer and the reflective layer.

8. A light-emitting device according to claim 7, characterized in that the reflective layer comprises a single metal layer containing Ag.

9. A light-emitting device according to claim 4, characterized in that the first metal includes Ge and the second metal includes Au.

10. A light-emitting device according to claim 1, characterized in that it further comprises a magnetic layer positioned on the reflective layer.

11. A light-emitting device characterized in that, in the first paragraph, it further includes a second contact layer located on a second surface opposite to the first surface with respect to the active layer and electrically connected to the first conductive semiconductor layer.

12. A light emitting device according to claim 1, characterized in that the first contact layer occupies an area of ​​5 to 20% of the total area of ​​the first surface.

13. A method for manufacturing a light-emitting device comprising a semiconductor layer including a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer positioned between the first conductive semiconductor layer and the second conductive semiconductor layer, A step of forming a first contact layer on the first conductive semiconductor layer; and It comprises a step of forming a reflective layer on the first metal layer, The step of forming the first contact layer is: A step of forming a first layer in which a first metal and a second metal form an alloy on the first conductive semiconductor layer; A step of forming a second layer including the second metal on the first layer; heat treatment step; and A method for manufacturing a light-emitting device, characterized in that it comprises a step of removing the second layer.

14. In the 13th paragraph, the step of forming the first contact layer is: A step of forming a photoresist layer that opens a first surface of the first conductive semiconductor layer; A step of continuously forming the first layer and the second layer on the first surface; and A method for manufacturing a light-emitting device, characterized in that it comprises a step of removing the above photoresist.

15. In the 13th paragraph, the step of forming the first contact layer is: A method for manufacturing a light-emitting device, characterized in that the second conductive semiconductor layer is attached to a transfer substrate through a sacrificial layer.

16. A method for manufacturing a light-emitting device, characterized in that in claim 13, the first metal includes Ge and the second metal includes Au.

17. A method for manufacturing a light-emitting device, characterized in that it further comprises a step of forming a reflective layer on the surface from which the second layer has been removed, in accordance with claim 13.

18. A method for manufacturing a light-emitting device, characterized in that in claim 17, the reflective layer forms a single metal layer containing Ag.

19. A method for manufacturing a light-emitting device, characterized in that it further comprises a step of forming a magnetic layer on the reflective layer in the 13th paragraph.

20. In a display device using a semiconductor light-emitting element, A wiring board having a first electrode arranged thereon; A light emitting element including a semiconductor layer arranged on the above wiring board to form a unit subpixel; A first connection electrode electrically connecting one side of the semiconductor layer of the first electrode and the light-emitting element; A planarizing layer covering the light-emitting element and the first connecting electrode; and It is configured to include a second connection electrode positioned on the above-mentioned flattening layer and electrically connected to the other side of the semiconductor layer of the light-emitting element, The light emitting element comprises a first contact layer, at least a portion of which is electrically discontinuously connected to the first surface of the semiconductor layer; and A display device characterized by including a reflective layer positioned on the first contact layer.

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