Light emitting diode, display device using the same, and method of manufacturing the same

Abstract

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

Description

Technical Field

[0001] This disclosure applies to the field of display device technology, such as to micro light-emitting diodes (LEDs), display devices using LEDs, and methods for manufacturing the same. Background Technology

[0002] In recent years, display devices with excellent characteristics such as ultra-thinness and flexibility have been developed in the field of display technology. Currently, the main commercial displays are represented by liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs).

[0003] However, LCDs suffer from problems such as long response times and difficulty in achieving flexibility, while OLEDs suffer from problems such as short lifespan and low mass production yield.

[0004] On the other hand, a light-emitting diode (LED) is a well-known semiconductor light-emitting element capable of converting electrical current into light energy. Since the commercialization of red LEDs using GaAsP compound semiconductors in 1962, LEDs have been used as display light sources in electronic devices (including information and communication equipment) and in conjunction with GaP:N-type green LEDs. Therefore, a method for implementing a display using a semiconductor light-emitting element can be proposed to solve the aforementioned problems. Compared with filament light-emitting elements, this LED has many advantages such as long lifespan, low power consumption, excellent initial drive characteristics, and strong vibration resistance.

[0005] AuGe alloys, commonly used in n-type electrodes, have low reflectivity. Furthermore, after heat treatment to form ohmic contacts, the reflectivity of AuGe alloys decreases to approximately 20%.

[0006] To solve this problem, various metal layer structures were tried, but it was difficult to simultaneously satisfy both electrical and optical properties.

[0007] To address this issue, a structure was proposed that partially forms an ohmic contact and the remainder forms a reflective film. However, this structure is difficult to implement due to the micrometer-scale 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 was proposed, but its reflective efficiency is reduced compared to a single metal.

[0009] In addition, the gold Au reflective film, which is mainly used in red light-emitting elements, is very expensive to manufacture and will interdiffuse with aluminum Al, which is used as a bridging metal in the display device, thus forming an inhomogeneous intermetallic compound (IMC).

[0010] Due to the high diffusion rate at the aluminum-gold interface, Kirkendall voids can form in the gold-rich region. These voids not only reduce the current flow area, thus increasing resistance, but also lead to reliability issues in the long run.

[0011] Therefore, a method is needed to solve this type of problem. Summary of the Invention

[0012] Technical issues

[0013] This disclosure aims to provide a light-emitting element, a display device using the light-emitting element, and a method for manufacturing the light-emitting element, wherein the light extraction efficiency of the light-emitting element can be improved, thereby also improving the efficiency of the display device.

[0014] Furthermore, this disclosure also aims to provide a light-emitting element, a display device using the light-emitting element, and a method for manufacturing the light-emitting element, wherein the light extraction efficiency of the red light-emitting element can be improved, thereby also improving the efficiency of the display device.

[0015] Furthermore, this disclosure also aims to provide a light-emitting element, a display device using the light-emitting element, and a method for manufacturing the light-emitting element, wherein the reflectivity and ohmic contact characteristics of the light-emitting element can be improved.

[0016] Furthermore, this disclosure aims to provide a light-emitting element, a display device using the light-emitting element, and a method for manufacturing the light-emitting element to solve panel reliability-related problems (e.g., increased resistance, reduced strength, performance degradation, etc.), which may be caused by alloy inhomogeneities that may occur when forming connecting electrodes during panel manufacturing.

[0017] Furthermore, the embodiments disclosed herein are intended to address various problems not mentioned herein. Those skilled in the art will understand these problems based on the overall disclosure and accompanying drawings.

[0018] Technical solution

[0019] As a first aspect of solving the above problems, this disclosure provides a light-emitting element, the light-emitting element comprising: a first conductivity type semiconductor layer; a second conductivity type semiconductor layer; an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; a first contact layer having at least a portion electrically connected to a first surface of the first conductivity type semiconductor layer in a discontinuous manner; and a reflective layer disposed on the first contact layer.

[0020] In one implementation of the first aspect, the first contact layer may form an ohmic contact with the first conductivity type semiconductor layer at a portion that is electrically connected to the first surface in a discontinuous manner.

[0021] In one implementation of the first aspect, the ohmic contact can be formed by diffusing at least a portion of the first contact layer into the first conductivity type semiconductor layer.

[0022] In one implementation of the first aspect, the first contact layer may include: a first metal forming an ohmic contact with the first conductivity type semiconductor layer; and a second metal for diffusing the first metal.

[0023] In one implementation of the first aspect, the first metal and the second metal can form an alloy.

[0024] In one implementation of the first aspect, the first metal may include a region diffused into the semiconductor layer of the first conductivity type.

[0025] In one implementation of the first aspect, an interface may exist between the first contact layer and the reflective layer.

[0026] In one implementation of the first aspect, the reflective layer may be a single metal layer containing Ag.

[0027] In one implementation of the first aspect, the first metal may include Ge, and the second metal may include Au.

[0028] In one implementation of the first aspect, the light-emitting element may further include a magnetic layer disposed on the reflective layer.

[0029] In one implementation of the first aspect, the light-emitting element may further include a second contact layer located on a second surface opposite to the first surface relative to the active layer, and electrically connected to the first conductivity type semiconductor layer.

[0030] In one implementation of the first aspect, the first contact layer may occupy 5% to 20% of the total area of ​​the first surface.

[0031] As a second aspect of solving the above problems, this disclosure provides a method for manufacturing a light-emitting element, the light-emitting element including a semiconductor layer, the semiconductor layer including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, the method including the following steps: forming a first contact layer on the first conductivity type semiconductor layer; and forming a reflective layer on a first metal layer, wherein forming the first contact layer includes: forming a first layer, wherein a first metal and a second metal are alloyed on the first conductivity type semiconductor layer; forming a second layer including the second metal on the first layer; performing a heat treatment; and removing the second layer.

[0032] In one implementation of the second aspect, the step of forming the first contact layer may include: forming a photoresist layer that opens a first surface of the first conductivity type semiconductor layer; continuously forming the first layer and the second layer on the first surface; and removing the photoresist.

[0033] In one implementation of the second aspect, the step of forming the first contact layer may be performed simultaneously with the second conductivity type semiconductor layer being attached to the transfer substrate through the sacrificial layer.

[0034] In one implementation of the second aspect, the method may further include forming a reflective layer on the surface where the second layer has been removed.

[0035] In one implementation of the second aspect, the method may further include forming a magnetic layer on the reflective layer.

[0036] As a third aspect of solving the above problems, this disclosure provides a display device using a semiconductor light-emitting element, the display device comprising: a wiring substrate on which a first electrode is disposed; a light-emitting element including a semiconductor layer disposed on the wiring substrate to form a unit sub-pixel; a first connecting 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 connecting electrode; and a second connecting electrode located on the planarization layer and electrically connected to the opposite side of the semiconductor layer of the light-emitting element, wherein the light-emitting element comprises: a first contact layer having at least a portion electrically connected discontinuously to a first surface of the semiconductor layer; and a reflective layer disposed on the first contact layer.

[0037] Beneficial effects

[0038] According to the embodiments of this disclosure, the following effects are achieved.

[0039] First, according to the embodiments of this disclosure, an ohmic contact metal can be formed in a portion of the light-emitting element having a vertical structure, and a highly reflective metal can be formed in the remaining portion, thereby improving the light extraction efficiency of the light-emitting element.

[0040] The first contact layer can add a rough surface to the bottom surface (first surface) of the first conductivity type semiconductor layer, thereby further improving the light extraction efficiency through the first surface.

[0041] Since this first contact layer primarily affects the formation of ohmic contacts and rough surfaces, the consumption of materials (especially gold, Au) required to form the first contact layer can be greatly reduced.

[0042] Since the reflective layer is made of a single metal, no additional heat treatment is required, thus avoiding the reduction in reflectivity that can occur due to alloying with surrounding materials during the heat treatment process.

[0043] In addition, it can also solve panel reliability problems (such as increased resistance, reduced strength, and degraded performance) that may occur during the formation of connecting electrodes in the panel manufacturing process due to the inhomogeneity of the Au-Al alloy.

[0044] Furthermore, according to another embodiment of this disclosure, there are other effects not mentioned herein. These other effects will be understood by those skilled in the art based on the overall disclosure and accompanying drawings. Attached Figure Description

[0045] Figure 1 This is a conceptual diagram illustrating an embodiment of a display device using a semiconductor light-emitting element according to the present disclosure.

[0046] Figure 2 It is shown Figure 1 A magnified view of part A shown.

[0047] Figure 3a and Figure 3b It is along Figure 2 Cross-sectional view taken by the cutting lines BB and CC.

[0048] Figure 4 This is an example Figure 3a and Figure 3b The diagram shown is a conceptual representation of a flip-chip semiconductor light-emitting element.

[0049] Figures 5a to 5c This is a conceptual diagram illustrating various examples of how color can be implemented in flip-chip semiconductor light-emitting elements.

[0050] Figure 6A cross-sectional view is shown of a method for manufacturing a display device using a semiconductor light-emitting element according to the present disclosure.

[0051] Figure 7 This is a perspective view of a display device using a semiconductor light-emitting element according to another embodiment of the present disclosure.

[0052] Figure 8 It is along Figure 7 The cross-sectional view shown is taken by the cutting line DD.

[0053] Figure 9 It is shown Figure 8 The diagram shows a conceptual representation of a vertical semiconductor light-emitting element.

[0054] Figure 10 This is a cross-sectional view showing a light-emitting element according to an embodiment of the present disclosure.

[0055] Figure 11 This is a graph showing the reflectivity of a metal that can be used as a reflective layer as a function of wavelength.

[0056] Figures 12 to 19 This is a diagram illustrating the process of manufacturing a light-emitting element according to an embodiment of the present disclosure.

[0057] Figure 20 and Figure 21 These are photographs and analytical photographs showing an example of the formation of the first contact layer.

[0058] Figure 22 This is a cross-sectional view showing a display device using a light-emitting element according to an embodiment of the present disclosure. Detailed Implementation

[0059] Reference will now be made in detail to embodiments of this disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings to denote the same or similar parts, and redundant descriptions thereof will be omitted. As used herein, the suffixes “module” and “unit” are added or used interchangeably for the purpose of preparing this specification and are not intended to imply different meanings or functions. In describing the embodiments disclosed in this specification, related well-known techniques may not be described in detail in order not to obscure the subject matter of the embodiments disclosed in this specification. Furthermore, it should be noted that the drawings are provided only for ease of understanding of the embodiments disclosed in this specification and should not be construed as limiting the technical spirit disclosed in this specification.

[0060] Furthermore, although the accompanying drawings are described separately for simplicity, embodiments implemented by combining at least two or more drawings are also within the scope of this disclosure.

[0061] Furthermore, when an element such as a layer, region, or module is described as being "on" another element, it should be understood that the element may be directly on the other element, or there may be an intermediate element between them.

[0062] The display device described herein is a concept encompassing all display devices that display information per unit pixel or a group of unit pixels. Therefore, this display device can be applied not only to finished products but also to components. For example, a panel corresponding to a part of a digital television also independently corresponds to the display device described in this specification. Finished products include mobile phones, smartphones, laptops, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, tablet computers, tablet PCs, ultrabooks, digital TVs, desktop computers, etc.

[0063] However, it will be apparent to those skilled in the art that the configuration according to the embodiments described herein can even be applied to new products that will later be developed into display devices.

[0064] Furthermore, the semiconductor light-emitting elements mentioned in this specification include concepts such as LEDs and micro LEDs, and can be used interchangeably with them.

[0065] Figure 1 This is a conceptual diagram illustrating an embodiment of a display device using a semiconductor light-emitting element according to the present disclosure.

[0066] like Figure 1 As shown, information processed by the controller (not shown) of the display device 100 can be displayed using a flexible display.

[0067] The flexible display may include, for example, a display that can be warped, bent, twisted, folded, or rolled up by external force.

[0068] Furthermore, the flexible display may be, for example, a display manufactured on a thin and flexible substrate that can be warped, bent, folded or rolled up like paper, while maintaining the display characteristics of a conventional flat panel display.

[0069] When the flexible display remains in an unbent state (e.g., a state with an infinite radius of curvature) (hereinafter referred to as the first state), the display area of ​​the flexible display forms a flat surface. When the display in the first state is bent under the action of an external force (e.g., a state with a finite radius of curvature) (hereinafter referred to as the second state), the display area can be a curved surface. Figure 1 As shown, the information displayed in the second state can be visual information output on a curved surface. This visual information can be achieved by independently controlling the emission of sub-pixels arranged in a matrix. A unit pixel can, for example, represent the smallest unit used to achieve a color.

[0070] The unit pixel of a flexible display can be implemented using a semiconductor light-emitting element. In this disclosure, a light-emitting diode (LED) is exemplified as a semiconductor light-emitting element used to convert electric current into light. LEDs can be made into very small sizes, and therefore can serve as unit pixels even in a second state.

[0071] The flexible display implemented using LEDs will now be described in more detail with reference to the accompanying drawings.

[0072] Figure 2 yes Figure 1 A magnified view of part A in the middle.

[0073] Figure 3a and Figure 3b It is along Figure 2 The cross-sectional view taken from the BB and CC lines.

[0074] like Figure 2 , Figure 3a and Figure 3b As shown, a display device 100 using a passive matrix (PM) type semiconductor light-emitting element has been described as an example. However, the examples described below are also applicable to the case of using an active matrix (AM) type semiconductor light-emitting element.

[0075] Figure 1 The display device 100 shown may include 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, such as Figure 2 As shown.

[0076] The substrate 110 can be a flexible substrate. For example, to realize a flexible display device, the substrate 110 may include glass or polyimide (PI). Any insulating and flexible material, such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET), may be used. In addition, the substrate 110 may be made of transparent or opaque materials.

[0077] The substrate 110 may be a wiring substrate, on which the first electrode 120 is disposed. Therefore, the first electrode 120 may be positioned on the substrate 110.

[0078] like Figure 3aAs shown, the insulating layer 160 can be disposed on the substrate 110 where the first electrode 120 is positioned, and the auxiliary electrode 170 can be disposed on the insulating layer 160. In this case, the stacked structure of the insulating layer 160 laminated on the substrate 110 can be a single wiring substrate. More specifically, the insulating layer 160 can be made of an insulating flexible material (e.g., PI, PET, or PEN) and can be integrated with the substrate 110 to form a single substrate.

[0079] The auxiliary electrode 170 is an electrode that electrically connects the first electrode 120 and the semiconductor light-emitting element 150. It is located on the insulating layer 160 and is positioned corresponding to the first electrode 120. For example, the auxiliary electrode 170 can be dot-shaped and can be electrically connected to the first electrode 120 through an electrode hole 171 formed through the insulating layer 160. The electrode hole 171 can be formed by filling the via with a conductive material.

[0080] like Figure 2 or Figure 3a As shown, a conductive adhesive layer 130 can be formed on one surface of the insulating layer 160, but the embodiments of this disclosure are not limited thereto. For example, a layer with a specific function can be formed between the insulating layer 160 and the conductive adhesive layer 130, or the conductive adhesive layer 130 can be disposed on the substrate 110 without the insulating layer 160. In the structure in which the conductive adhesive layer 130 is disposed on the substrate 110, the conductive adhesive layer 130 can serve as an insulating layer.

[0081] The conductive adhesive layer 130 can be a layer that has both adhesive and conductive properties. For this purpose, a material with both conductive and adhesive properties can be incorporated into the conductive adhesive layer 130. Furthermore, the conductive adhesive layer 130 can be malleable, thereby making the display device flexible.

[0082] For example, the conductive adhesive layer 130 can be an anisotropic conductive film (ACF), an anisotropic conductive paste, a solution containing conductive particles, etc. The conductive adhesive layer 130 can be configured to allow electrical interconnection along the Z-axis direction (through its thickness), but to be electrically insulating in the horizontal XY direction. Therefore, the conductive adhesive layer 130 can be referred to as the Z-axis conductive layer (hereinafter referred to as the "conductive adhesive layer").

[0083] Anisotropic conductive film (ACF) is a film made by mixing an anisotropic conductive medium with an insulating substrate. When ACF is heated and pressurized, only specific portions of it become conductive due to the anisotropic conductive medium. Methods for applying heat and pressure to ACF are described below. However, other methods can also be used to make ACF partially conductive. For example, other methods may include applying heat and pressure only or ultraviolet curing.

[0084] Furthermore, the anisotropic conductive medium can be conductive spheres or conductive particles. For example, an ACF can be a film formed by mixing conductive spheres with an insulating substrate component. Therefore, when heat and pressure are applied to the ACF, only specific portions of the ACF will become conductive due to the action of the conductive spheres. The ACF can contain multiple particles formed by coating an insulating film made of a polymer material onto a conductive material core. In this case, as the insulating film is broken down in the portion subjected to heat and pressure, the core makes that portion conductive. At this time, the core deforms, forming layers that are in contact with each other along the film thickness direction. More specifically, applying heat and pressure to the entire ACF partially forms an electrical connection in the Z-axis direction through the height difference of the mating parts adhered to the ACF.

[0085] As another example, the ACF can comprise multiple particles formed by coating an insulating core with a conductive material. In this case, when the conductive material is deformed (compressed) in a portion subjected to heat and pressure, that portion becomes conductive in the thickness direction of the film. As yet another example, the conductive material can be positioned to pass through the insulating substrate member along the Z-axis, thereby becoming conductive in the thickness direction of the film. In this case, the conductive material can have a pointed tip.

[0086] The ACF can be a fixed array ACF, in which conductive balls are inserted into one surface of an insulating substrate member. More specifically, the insulating substrate member can be made of an adhesive material, and the conductive balls can be densely arranged on the bottom of the insulating substrate member. Therefore, when the substrate member is subjected to heat and pressure, it can deform together with the conductive balls, thereby exhibiting conductivity in the vertical direction.

[0087] However, this disclosure is not necessarily limited thereto. The ACF may be formed by randomly mixing conductive spheres in an insulating substrate member, or it may consist of multiple layers, one of which has conductive spheres arranged on it (as a double ACF).

[0088] The anisotropic conductive paste can be a combination of paste and conductive spheres, or a paste formed by mixing conductive spheres with an insulating adhesive substrate material. Furthermore, the solution containing conductive particles can be a solution containing any conductive particles or nanoparticles.

[0089] See Figure 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 disposed on the insulating layer 160 on which the auxiliary electrode 170 and the second electrode 140 are positioned.

[0090] After forming the conductive adhesive layer 130 with the auxiliary electrode 170 and the second electrode 140 positioned on the insulating layer 160, the semiconductor light-emitting element 150 is attached to the conductive adhesive layer 130 in a flip-chip form by applying heat and pressure. Thus, the semiconductor light-emitting element 150 is electrically connected to the first electrode 120 and the second electrode 140.

[0091] Figure 4 This is an example Figure 3a and Figure 3b A conceptual diagram of a flip-chip semiconductor light-emitting element.

[0092] See Figure 4 The semiconductor light-emitting element can be a flip-chip type light-emitting device.

[0093] For example, a semiconductor light-emitting element may include 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 disposed on the n-type semiconductor layer 153 and horizontally spaced from the p-type electrode 156. In this case, the p-type electrode 156 can be connected to the conductive adhesive layer 130. Figure 3a and Figure 3b The auxiliary electrode 170 shown is electrically connected, and the n-type electrode 152 can be electrically connected to the second electrode 140.

[0094] review Figure 2 , Figure 3a and Figure 3b The auxiliary electrode 170 can be elongated in one direction. Therefore, one auxiliary electrode can be electrically connected to multiple semiconductor light-emitting elements 150. For example, the p-type electrodes of the semiconductor light-emitting elements located on the left and right sides of the auxiliary electrode can be electrically connected to the auxiliary electrode.

[0095] More specifically, the semiconductor light-emitting element 150 can be press-fitted into the conductive adhesive layer 130 using heat and pressure. Thus, only the portions of the semiconductor light-emitting element 150 located between the p-type electrode 156 and the auxiliary electrode 170, and between the n-type electrode 152 and the second electrode 140, are conductive, while the other portions of the semiconductor light-emitting element 150 are non-conductive due to the lack of press-fitting. In this way, the conductive adhesive layer 130 interconnects and electrically connects the semiconductor light-emitting element 150 to the auxiliary electrode 170, and also interconnects and electrically connects the semiconductor light-emitting element 150 to the second electrode 140.

[0096] Multiple semiconductor light-emitting elements 150 can form a light-emitting device array, and a fluorescence conversion layer 180 can be formed on the light-emitting device array.

[0097] The light-emitting device array may include multiple semiconductor light-emitting elements with different brightness values. Each semiconductor light-emitting element 150 may constitute a unit pixel and may be electrically connected to a first electrode 120. For example, multiple first electrodes 120 may be provided, and the semiconductor light-emitting elements may be arranged in, for example, several columns. The semiconductor light-emitting elements in each column may be electrically connected to any one of the multiple first electrodes.

[0098] Furthermore, since the semiconductor light-emitting elements are connected in a flip-chip manner, semiconductor light-emitting elements grown on a transparent dielectric substrate can be used. The semiconductor light-emitting elements can be, for example, nitride semiconductor light-emitting elements. Because the semiconductor light-emitting element 150 has excellent brightness, even when the size is small, the semiconductor light-emitting element 150 can constitute a single unit pixel.

[0099] like Figure 3a and Figure 3b As shown, spacers 190 can be formed between the semiconductor light-emitting elements 150. In this case, the spacers 190 can be used to separate individual unit pixels from each other and can be integrated with the conductive adhesive layer 130. For example, spacers can be formed in the substrate members of the ACF by inserting the semiconductor light-emitting elements 150 into the ACF.

[0100] Furthermore, when the base component of the ACF is black, the spacer 190 can be reflective and enhance contrast even without a separate black insulator.

[0101] As another example, a reflective spacer can be provided separately as spacer 190. In this case, spacer 190 can include a black or white insulator, depending on the application of the display device. When using a spacer including a white insulator, reflectivity can be increased. When using a spacer including a black insulator, it can be reflective and have improved contrast.

[0102] The fluorescence conversion layer 180 can be positioned on the outer surface of the semiconductor light-emitting element 150. For example, the semiconductor light-emitting element 150 can be a blue semiconductor light-emitting element that emits blue light B, and the fluorescence conversion layer 180 can function to convert the blue light B into the color of a unit pixel. The fluorescence conversion layer 180 can be a red phosphor 181 or a green phosphor 182 that constitutes a single pixel.

[0103] In other words, a red phosphor 181 capable of converting blue light into red light (R) can be laminated onto a blue semiconductor light-emitting element located at the position of a red unit pixel; a green phosphor 182 capable of converting blue light into green light (G) can be laminated onto a blue semiconductor light-emitting element located at the position of a green unit pixel. In the portion constituting the blue unit pixel, only a blue semiconductor light-emitting element can be used. In this case, red (R), green (G), and blue (B) unit pixels can constitute one pixel. More specifically, a phosphor of one color can be laminated along each row of the first electrode 120. Therefore, a row on the first electrode 120 can be an electrode for controlling one color. That is, red (R), green (G), and blue (B) can be sequentially arranged along the second electrode 140 to achieve a unit pixel.

[0104] However, the embodiments disclosed herein are not limited thereto. Individual pixels of red (R), green (G), and blue (B) can be achieved by combining the semiconductor light-emitting element 150 with quantum dots (QDs) instead of using phosphors.

[0105] In addition, a black matrix 191 can be set between the fluorescence conversion layers to improve contrast. That is, the black matrix 191 can improve the contrast between light and dark areas.

[0106] However, the embodiments disclosed herein are not limited thereto, and other structures may also be used to achieve blue, red and green.

[0107] Figures 5a to 5c This is a conceptual diagram illustrating various examples of how colors can be implemented in relation to flip-chip semiconductor light-emitting elements.

[0108] See Figure 5a By using gallium nitride (GaN) as the main material and adding indium (In) and / or aluminum (Al), individual semiconductor light-emitting elements can be realized as high-power light-emitting devices that emit various colors of light, including blue.

[0109] In this configuration, each semiconductor light-emitting element can be a red, green, or blue semiconductor light-emitting element to form a unit pixel (sub-pixel). For example, the red, green, and blue semiconductor light-emitting elements R, G, and B can be alternately arranged, and a red, green, and blue unit pixel can be composed of these red, green, and blue semiconductor light-emitting elements. This allows for full-color display.

[0110] See Figure 5bThe semiconductor light-emitting element 150a may include a white light-emitting device W having a yellow phosphor conversion layer disposed for each device. In this case, to form a unit pixel, a red phosphor conversion layer 181, a green phosphor conversion layer 182, and a blue phosphor conversion layer 183 may be disposed on the white light-emitting device W. Furthermore, repeating red, green, and blue color filters may be used on the white light-emitting device W to form a unit pixel.

[0111] See Figure 5c A red phosphor conversion layer 184, a green phosphor conversion layer 185, and a blue phosphor conversion layer 186 can be disposed on the ultraviolet light emission device. Visible light and ultraviolet light can be used throughout the entire area of ​​the semiconductor light-emitting element. In this embodiment, ultraviolet light can be used as the excitation source for the upper phosphor layer in the semiconductor light-emitting element.

[0112] Returning to this example, the semiconductor light-emitting element is positioned on the conductive adhesive layer to form a unit pixel in the display device. Because semiconductor light-emitting elements have excellent brightness, individual unit pixels can be configured even when the size of the semiconductor light-emitting element is small.

[0113] Regarding the dimensions of individual semiconductor light-emitting elements, for example, the side length of the device can be less than 80 μm, and the device can be rectangular or square. When the semiconductor light-emitting element is rectangular, its dimensions can be less than or equal to 20 μm × 80 μm.

[0114] Furthermore, even using a square semiconductor light-emitting element with a side length of 10 μm as the unit pixel, sufficient brightness can be obtained to form a display device.

[0115] Therefore, for example, for a rectangular pixel with a unit pixel size of 600 μm × 300 μm (i.e., side length), the distance between semiconductor light-emitting elements is relatively long.

[0116] Therefore, under these circumstances, it is possible to realize a flexible display device with high image quality that is superior to HD image quality.

[0117] The aforementioned display device using semiconductor light-emitting elements can be manufactured using a novel method. The following will refer to... Figure 6 Describe this manufacturing method.

[0118] Figure 6 A cross-sectional view is shown of a method for manufacturing a display device using a semiconductor light-emitting element according to the present disclosure.

[0119] See Figure 6First, a conductive adhesive layer 130 is formed on an insulating layer 160 located between the auxiliary electrode 170 and the second electrode 140. The insulating layer 160 is then attached to a wiring substrate 110. A first electrode 120, an auxiliary electrode 170, and a second electrode 140 are disposed on the wiring substrate 110. In this case, the first electrode 120 and the second electrode 140 can be disposed in mutually orthogonal directions. To realize a flexible display device, the wiring substrate 110 and the insulating layer 160 can each comprise glass or polyimide (PI).

[0120] For example, the conductive adhesive layer 130 can be implemented using an anisotropic conductive film. For this purpose, an anisotropic conductive film can be coated on the substrate where the insulating layer 160 is located.

[0121] Subsequently, a temporary substrate 112 is provided, on which a plurality of semiconductor light-emitting elements 150, each configured with an individual pixel, are provided corresponding to the positions of the auxiliary electrode 170 and the second electrode 140. The temporary substrate 112 is configured such that the semiconductor light-emitting elements 150 are opposite to the auxiliary electrode 170 and the second electrode 140.

[0122] In this regard, the temporary substrate 112 is a growth substrate for growing the semiconductor light-emitting element 150, and may include a sapphire or silicon substrate.

[0123] Semiconductor light-emitting elements are configured to have space and dimensions for arranging display devices when formed on a wafer-by-wafer basis, thereby being used effectively in display devices.

[0124] Subsequently, the wiring substrate 110 and the temporary substrate 112 are hot-pressed together. Through hot pressing, the wiring substrate 110 and the temporary substrate 112 are bonded together. Because the anisotropic conductive film has thermo-conductive properties, only a portion of the semiconductor light-emitting element 150, the auxiliary electrode 170, and the second electrode 140 are conductive; through this portion, the electrode and the semiconductor light-emitting element 150 can be electrically connected. In this case, the semiconductor light-emitting element 150 is inserted into the anisotropic conductive film, and spacers can be formed between the semiconductor light-emitting elements 150 by the anisotropic conductive film.

[0125] The temporary substrate 112 is then removed. For example, laser lift-off (LLO) or chemical lift-off (CLO) can be used to remove the temporary substrate 112.

[0126] Finally, by removing the temporary substrate 112, the semiconductor light-emitting element 150 is exposed to the outside. If necessary, the wiring substrate 110 connected to the semiconductor light-emitting element 150 may be coated with silicon oxide (SiOx) or the like to form a transparent insulating layer (not shown).

[0127] In addition, the step of forming a phosphor layer on one side of the semiconductor light-emitting element 150 may be included. For example, the semiconductor light-emitting element 150 may include a blue semiconductor light-emitting element that emits blue light B, and a red or green phosphor layer for converting blue light B into the color of a unit pixel may be formed on one side of the blue semiconductor light-emitting element.

[0128] The manufacturing method or structure of the display device using semiconductor light-emitting elements described above can be modified in various ways. For example, the display device described above can employ a vertical semiconductor light-emitting element.

[0129] Furthermore, the modifications or implementations described below may use the same or similar reference numerals as those in the foregoing implementations, and the foregoing description also applies to these modifications or implementations.

[0130] Figure 7 This is a perspective view of a display device using a semiconductor light-emitting element according to another embodiment of the present disclosure. Figure 8 It is along Figure 7 The cross-sectional view shown is taken by the cutting line DD, and... Figure 9 It is shown Figure 8 The diagram shows a conceptual representation of a vertical semiconductor light-emitting element.

[0131] Referring to the attached diagram, the display device may employ a passive matrix (PM) type vertical semiconductor light-emitting device.

[0132] 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.

[0133] The substrate 210 is a wiring substrate on which the first electrode 220 is disposed, and may contain polyimide (PI) to realize a flexible display device. In addition, the substrate 210 can be made of any insulating and flexible material.

[0134] The first electrode 220 is located on the substrate 210 and can be formed as a strip electrode that is longer in one direction. The first electrode 220 can be configured to function as a data electrode.

[0135] A conductive adhesive layer 230 is formed on a substrate 210 on which the first electrode 220 is disposed. Similar to a display device with a flip-chip type light-emitting device, the conductive adhesive layer 230 may include an anisotropic conductive film (ACF), anisotropic conductive paste, a solution containing conductive particles, etc. However, in this embodiment, only the case where an anisotropic conductive film is used as the conductive adhesive layer 230 is illustrated by way of example.

[0136] After the conductive adhesive layer is placed on the substrate 210 with the first electrode 220 located on the substrate 210, if heating and pressure are applied to the semiconductor light-emitting element 250, the semiconductor light-emitting element 250 is electrically connected to the first electrode 220. In doing so, the semiconductor light-emitting element 250 is preferably disposed on the first electrode 220.

[0137] If heating and pressure are applied to the anisotropic conductive film, as described above, an electrical connection can be established because the anisotropic conductive film is partially conductive in the thickness direction. Therefore, the anisotropic conductive film is divided into conductive and non-conductive portions.

[0138] Furthermore, since the anisotropic conductive film contains adhesive components, the conductive adhesive layer 230 enables mechanical connection and mechanical linkage between the semiconductor light-emitting element 250 and the first electrode 220.

[0139] Therefore, the semiconductor light-emitting element 250 is located on the conductive adhesive layer 230, through which individual pixels are configured in the display device. Because the semiconductor light-emitting element 250 has excellent brightness, the size of each individual pixel can also be very small. Regarding the size of the individual semiconductor light-emitting element 250, the length of one side can be equal to or less than, for example, 80 micrometers, and the individual semiconductor light-emitting element 260 can include a rectangle or a square. For example, a rectangular element can have a size equal to or less than 20 micrometers × 80 micrometers.

[0140] The semiconductor light-emitting element 250 can have a vertical structure.

[0141] In the vertical semiconductor light-emitting element, a plurality of second electrodes 240, which are respectively and electrically connected to the vertical semiconductor light-emitting element 250, are arranged in a manner that intersects with the length direction of the first electrode 220.

[0142] See Figure 9 The vertical semiconductor light-emitting element 250 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 on the bottom side can be electrically connected to the first electrode 220 through a conductive adhesive layer 230, and the n-type electrode 252 located on the top side can be electrically connected to the second electrode 240 described later. Since the electrodes of this vertical semiconductor light-emitting element 250 can be disposed at the top and bottom, it has a significant advantage in reducing chip size.

[0143] See you again Figure 8A phosphor layer 280 may be formed on one side of the semiconductor light-emitting element 250. For example, the semiconductor light-emitting element 250 may include a blue semiconductor light-emitting element 251 that emits blue light B, and may provide a phosphor layer 280 for converting blue light B into the color of a unit pixel. In this regard, the phosphor layer 280 may include a red phosphor 281 and a green phosphor 282 configured for individual pixels.

[0144] That is, at the location where a red unit pixel is configured, a red phosphor 281 capable of converting blue light (R) can be stacked on the blue semiconductor light-emitting element. At the location where a green unit pixel is configured, a green phosphor 282 capable of converting blue light (G) can be stacked on the blue semiconductor light-emitting element. Furthermore, the blue semiconductor light-emitting element can be used alone for the portion configuring the blue unit pixel. In this case, a single pixel can be configured for each of the red (R), green (G), and blue (B) units.

[0145] However, this disclosure is not limited to the above description. As mentioned above, different structures can be used to achieve blue, red, and green in display devices that employ flip-chip light-emitting elements.

[0146] Taking this embodiment as an example again, the second electrode 240 is located between the semiconductor light-emitting elements 250 and is electrically connected to the semiconductor light-emitting elements. For example, the semiconductor light-emitting elements 250 are arranged in multiple columns, and the second electrode 240 may be located between each column of semiconductor light-emitting elements 250.

[0147] Since the distance between the semiconductor light-emitting elements 250 configured with individual pixels is long enough, the second electrode 240 can be located between each semiconductor light-emitting element 250.

[0148] The second electrode 240 may be formed as a strip electrode that is longer in a certain direction and is arranged in a direction perpendicular to the first electrode.

[0149] Furthermore, the second electrode 240 and the semiconductor light-emitting element 250 can be electrically connected to each other via a connection electrode protruding from the second electrode 240. Specifically, the connection electrode may include an n-type electrode of the semiconductor light-emitting element 250. For example, the n-type electrode is formed as an ohmic electrode for an ohmic contact, and the second electrode covers at least a portion of the ohmic electrode by printing or deposition. Therefore, the second electrode 240 and the n-type electrode of the semiconductor light-emitting element 250 can be electrically connected to each other.

[0150] See you again Figure 8The second electrode 240 may be located on the conductive adhesive layer 230. In some cases, a transparent insulating layer (not shown) containing silicon oxide (SiOx) or the like may be formed on the substrate 210 on which the semiconductor light-emitting element 250 is formed. If the second electrode 240 is provided after the transparent insulating layer is formed, the second electrode 240 is located on the transparent insulating layer. Alternatively, the second electrode 240 may be spaced apart from the conductive adhesive layer 230 or the transparent insulating layer by a certain distance.

[0151] If a transparent electrode such as indium tin oxide (ITO) is used to mount the second electrode 240 onto the semiconductor light-emitting element 250, there is a problem of poor adhesion between the ITO material and the n-type semiconductor layer. Therefore, according to this disclosure, since the second electrode 240 is disposed between the semiconductor light-emitting elements 250, it is advantageous not to use an ITO transparent electrode. Therefore, a conductive material with good adhesion to the n-type semiconductor layer can be used as the horizontal electrode, and the choice of transparent material is not limited, thereby improving light extraction efficiency.

[0152] See you again Figure 8 The spacer 290 can be located between the semiconductor light-emitting elements 250. That is, in order to isolate the semiconductor light-emitting elements 250 that are configured with individual pixels, the spacer 290 can be provided between the vertical semiconductor light-emitting elements 250. In this case, the spacer 290 can serve to separate the individual unit pixels from each other, and can be formed as an integral part with the conductive adhesive layer 230. For example, the spacer can be formed by inserting the semiconductor light-emitting elements 250 into the anisotropic conductive film, and the substrate member of the anisotropic conductive film.

[0153] Furthermore, if the substrate of the anisotropic conductive film is black, the spacer 290 can have reflective properties and can improve contrast without the need for a separate insulator.

[0154] For example, a reflective spacer 290 can be provided separately as spacer 190. Spacer 290 may contain a black or white insulator, depending on the application of the display device.

[0155] With the second electrode 240 directly located on the conductive adhesive layer 230 between the semiconductor light-emitting elements 250, the spacers 290 can be positioned between the vertical semiconductor light-emitting elements 250 and the second electrode 240. Therefore, individual unit pixels can be configured using the semiconductor light-emitting elements 250. Since the distance between the semiconductor light-emitting elements 250 is sufficiently long, the second electrode 240 can be disposed between the semiconductor light-emitting elements 250. This allows for the realization of a flexible display device with HD image quality.

[0156] In addition, such as Figure 8As shown, a black matrix 291 can be placed between each fluorescent element to improve contrast. In other words, the black matrix 291 can improve the contrast between light and dark areas.

[0157] In the display device according to the present disclosure, the semiconductor light-emitting element is disposed on the wiring substrate in a flip-chip configuration and serves as an individual pixel.

[0158] Figure 10 This is a cross-sectional view showing a light-emitting element according to an embodiment of the present disclosure.

[0159] See Figure 10 According to embodiments of the present disclosure, the light-emitting element 330 may include a semiconductor layer, which includes a first conductivity type semiconductor layer 331, a second conductivity type semiconductor layer 332, and an active layer 333 disposed between the first conductivity type semiconductor layer 331 and the second conductivity type semiconductor layer 332. The horizontal cross-sectional shape of the semiconductor layer may be circular, elliptical, or polygonal.

[0160] For example, the first conductivity type can be n-type. Correspondingly, the second conductivity type can be p-type. The following will focus on examples of this disclosure where the first conductivity type is n-type and the second conductivity type is p-type. For example, the first conductivity type semiconductor layer 331 can be an n-type semiconductor layer, and the second conductivity type semiconductor layer 332 can be a p-type semiconductor layer. However, embodiments of this disclosure are not limited thereto. For example, the first conductivity type semiconductor layer 331 can be a p-type semiconductor layer, and the second conductivity type semiconductor layer 332 can be an n-type semiconductor layer.

[0161] In an exemplary embodiment, the light-emitting element can be a red light-emitting element for emitting red light. Such a red light-emitting element may include a GaAs- or InP-based semiconductor. For example, the red light-emitting element may include a compound semiconductor material composed of at least one element selected from In, Ga, As, and P. However, embodiments of this disclosure are not limited thereto.

[0162] Furthermore, the light-emitting element 330 according to embodiments of the present disclosure may include: a first contact layer 335, at least a portion of which is discontinuously electrically connected to a first surface of a first conductivity type semiconductor layer 331; and a reflective layer 336 located on the first contact layer 335.

[0163] As described above, the first contact layer 335 can be at least partially electrically connected to the first conductivity type semiconductor layer 331. Here, "discontinuously" or "at least partially" can refer to a state where the first contact layer 335 is in discontinuous contact with at least a portion of the bottom surface (first surface) of the first conductivity type semiconductor layer 331, which is the surface facing the reflective layer 336, such as... Figure 10 As shown.

[0164] For example, the first contact layer 335 can be positioned to partially form an ohmic contact with the first conductivity type semiconductor layer 331 without covering the entire bottom surface (first surface) of the first conductivity type semiconductor layer 331. In this respect, since the reflective layer 336 is positioned on the portion of the bottom surface (first surface) of the first conductivity type semiconductor layer 331 not covered by the first contact layer 335, the reflectivity of the light-emitting element can be kept from being significantly reduced by the first contact layer 335.

[0165] In an exemplary embodiment, the first contact layer 335 may occupy 5% to 20% of the total area of ​​the bottom surface (first surface) of the first conductivity type semiconductor layer 331.

[0166] The portion of the first contact layer 335 that is in ohmic contact with the first conductivity type semiconductor layer 331 may be the portion of the first contact layer 335 that diffuses into the first conductivity type semiconductor layer 331.

[0167] As an exemplary embodiment, the first contact layer 335 may include a first metal forming an ohmic contact with the first conductivity type 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.

[0168] As described above, the first metal constituting the first contact layer 335 may include a region (diffusion region) diffused into the first conductivity type semiconductor layer 331.

[0169] For example, the first metal may include germanium (Ge), and the second metal may include gold (Au). 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.

[0170] In this respect, Ge can diffuse into the first conductivity type semiconductor layer 331 to form an ohmic contact with the first conductivity type semiconductor layer 331. Au can help Ge spread uniformly onto the first surface without agglomeration.

[0171] This will be described in detail later.

[0172] In 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 not be alloyed, but may exist as independent layers.

[0173] For example, the reflective layer 336 can be formed into a single metal layer containing silver (Ag). Figure 11 This is a graph showing the reflectivity of a metal that can be used as a reflective layer as a function of wavelength. (See also...) Figure 11 Ag has relatively high reflectivity for red light. For example, for red light with wavelengths above 600 nm, Ag's reflectivity can be higher than that of gold (Au), aluminum (Al), and copper (Cu).

[0174] Ag alloys form at a slower rate than Au and exhibit more uniform formation. Furthermore, due to Ag's superior thermal / electrical properties compared to Au, current can flow easily without overheating or voids, even with a small contact area. Therefore, Ag can offer advantages in terms of reliability.

[0175] As described above, the first contact layer 335 can be positioned in a relatively inner region of the bottom surface (first surface) of the first conductivity type semiconductor layer 331, and the reflective layer 336 can be positioned in a relatively outer region.

[0176] As an exemplary embodiment, the light-emitting element 330 according to the embodiments of the present disclosure may further include a magnetic layer 337 disposed on the reflective layer 336.

[0177] For use as a sub-pixel in a display device, the light-emitting element 330 can be magnetically assembled to the wiring substrate 310 (see [reference]). Figure 22 The light-emitting element 330 can be assembled in a fluid using magnetic force, or on a separate assembly substrate (not shown). For example, the light-emitting element 330 can be assembled using magnetic force. Therefore, the magnetic layer 337 can assist in the process of assembling the light-emitting element 330 using magnetic force. Detailed description will be omitted here.

[0178] As an exemplary embodiment, the light-emitting element 330 according to the embodiments of the present disclosure may further include a second contact layer 334 located on a second surface (top surface) of the light-emitting element 330 opposite to the first surface (bottom surface) with reference to the active layer 333, and electrically connected to a semiconductor layer of a second conductivity type.

[0179] For example, the light-emitting element 330 may include a passivation layer 338 for protecting its outer surface from electrical shocks. The passivation layer 338 may be partially removed during the assembly process or the wiring connection process.

[0180] AuGe alloys, commonly used for electrical characteristics of n-type electrodes, exhibit low reflectivity. Furthermore, after heat treatment to form ohmic contacts, the reflectivity of AuGe alloys decreases to approximately 20%.

[0181] To solve this problem, various metal layer structures were tried, but it was difficult to simultaneously satisfy both electrical and optical properties.

[0182] To address this issue, a structure was proposed that partially forms an ohmic contact and the remainder forms a reflective film. However, due to the micrometer-scale size of the light-emitting element chip, this structure presents significant challenges in implementation.

[0183] In addition, a reflective film covering the entire n-type semiconductor layer in the form of an alloy was proposed, but its reflective efficiency is reduced compared to a single metal.

[0184] In particular, the gold Au reflective film, which is mainly used in red light-emitting elements, is very expensive to manufacture and can interdiffuse with aluminum Al, which is used as a bridging metal in the display device, thus forming an inhomogeneous intermetallic compound (IMC).

[0185] Due to the high diffusion rate at the Al-Au interface, Kirkendall voids may form in gold-rich regions. These voids not only reduce the area for current flow, thus increasing resistance, but also lead to reliability issues in the long run.

[0186] However, according to an exemplary embodiment of the present disclosure, as described above, a metal (first contact layer 335) for forming an n-type contact of a vertical structure light-emitting element 330 can be formed on a portion of the bottom surface (first surface) of the first conductivity type semiconductor layer 331, and a highly reflective metal (reflective layer 336) can be formed on the remaining area, thereby improving the light extraction efficiency of the light-emitting element 330.

[0187] The first contact layer 335 may add a rough surface to the bottom surface (first surface) of the first conductivity type semiconductor layer 331 to further improve the light extraction efficiency through the first surface.

[0188] Because this first contact layer 335 primarily affects the formation of ohmic contacts and rough surfaces, it can significantly reduce the consumption of materials (especially gold, Au) required to form the first contact layer 335.

[0189] Because the reflective layer 336 is made of a single metal without additional heat treatment, there is no reduction in reflectivity due to the formation of an alloy with the surrounding material during the heat treatment process.

[0190] In addition, it can also solve the problem of forming the connection electrode 342 during the panel manufacturing process (see Figure 22 This could lead to panel reliability issues (e.g., increased resistance, reduced strength, and decreased performance) due to Au-Al alloy inhomogeneity.

[0191] Figures 12 to 19 This is a schematic diagram of a method for manufacturing a light-emitting element according to an embodiment of the present disclosure. Wherein, Figure 16 and Figure 18 It is a photograph showing the contact surface.

[0192] The following will refer to Figures 12 to 19 The manufacturing method of the light-emitting element 330 according to the embodiments of the present disclosure is described step by step.

[0193] First, refer to Figure 12 The light-emitting element 330, which includes a semiconductor layer of the first conductivity type 331, a semiconductor layer of the second conductivity type 332, and an active layer 333, can be processed while attached to the transfer substrate 400 by means of the bonding layer 410.

[0194] For example, a sacrificial layer 420 may be provided between the bonding layer 410 and the light-emitting element 330. The sacrificial layer 420 is typically made of a metallic material, and the light-emitting element 330 can be separated from the transfer substrate 400 by removing the sacrificial layer 420.

[0195] The light-emitting element 330, after contact treatment, can be dispersed in a liquid and assembled onto the wiring substrate 310 while the sacrificial layer 420 is removed. In this respect, the light-emitting element 330 can be assembled onto the wiring substrate 310 by magnetic force and dielectric electrophoresis. A detailed description of this process is omitted here.

[0196] The first contact layer 335 can be formed on the bottom surface of such a light-emitting element 330. The formation process of the first contact layer 335 will be described in detail below.

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

[0198] With the light-emitting element 330 partially attached to the transfer substrate 400 via the sacrificial layer 420 and the bonding layer 410, and with the portion on the first surface (bottom surface) of the first conductivity type semiconductor layer 331 for forming the first contact layer open, a photoresist layer 430 can be formed. Therefore, as... Figure 12 As shown, the photoresist layer 430 can contact the side of the structure of the light-emitting element 330, the sacrificial layer 420 and the bonding layer 410.

[0199] See afterward. Figure 13 The metal layer 335' used to form the first contact layer can be continuously formed on the first surface (bottom surface) of the first conductivity type semiconductor layer 331. The metal layer 335' includes a first layer 335-1 and a second layer 335-2.

[0200] Here, the first layer 335-1 may include the aforementioned first metal that forms an ohmic contact with the first conductivity type 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.

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

[0202] For example, the second layer 335-2 may include a second metal. In other words, the second layer 335-2 may include Au material. For example, the second layer 335-2 may be made of Au.

[0203] Next, refer to Figure 14 The photoresist layer 430 can be removed. Through this process, the first layer 335-1 and the second layer 335-2 are removed, leaving only the desired area, thereby forming the metal structure 335'' for forming the first contact layer.

[0204] This process can be called a self-alignment process. Therefore, additional processes and equipment for aligning the chip of the light-emitting element 330 at the micrometer scale are unnecessary.

[0205] Following this, a heat treatment process can be performed. Through the heat treatment process, the first layer 335-1 can form a region (diffusion region) that diffuses into the first conductivity type semiconductor layer 331. (Refer to...) Figure 15 This diffusion region can form an ohmic contact with the first conductivity type semiconductor layer 331, thereby forming a first contact layer 335. For example, heat treatment can be performed in a temperature range of 350°C to 450°C. Alternatively, heat treatment can be performed in a temperature range of 370°C to 410°C. Such a heat treatment temperature range can be more advantageous in terms of reflectivity.

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

[0207] In this respect, Ge can diffuse into the first conductivity type semiconductor layer 331 to form an ohmic contact with the first conductivity type semiconductor layer 331. Au can help Ge diffuse uniformly onto the first surface without agglomeration.

[0208] Figure 16 This is a photograph of the first surface (bottom surface) of the first conductive type semiconductor layer 331 of the circular light-emitting element. Figure 16 The state shown illustrates the second layer 335-2.

[0209] Next, the second layer 335-2 can be removed. Therefore, after removing the second layer 335-2, the following can be obtained: Figure 17 The state shown.

[0210] As described above, after the Ge diffusion region is formed through a heat treatment process, the remaining layer (second layer) can be removed. When an ohmic contact region is formed through Ge diffusion, the remaining region has a high light absorption rate, which is not conducive to reflection, so the remaining region can be removed.

[0211] Figure 18 It is a photograph of the first surface (bottom surface) of the first conductive semiconductor layer 331 of the circular light-emitting element after the second layer 335-2 has been removed. Figure 18 The stained portion shown can correspond to the Ge diffusion region. That is, in this portion, the first conductivity type semiconductor layer 331 can form an ohmic contact.

[0212] See Figure 19 After removing the second layer 335-2, a reflective layer 336 can be formed on the surface where the second layer 335-2 has been removed.

[0213] Such a reflective layer 336 substantially covers the first surface (bottom surface) of the first conductivity type semiconductor layer 331, so that all parts except the Ge diffusion region can be used for reflection.

[0214] Subsequently, as an exemplary embodiment, a magnetic layer 337 may be formed on the reflective layer 336.

[0215] In this state, when the sacrificial layer 420 is removed to separate the individual light-emitting elements 330, it is possible to manufacture an image such as... Figure 10 The light-emitting element 330 is shown in the indicated state.

[0216] Figure 20 and Figure 21 The photographs and analytical photographs show an example of the formation of the first contact layer. Figure 20 and Figure 21 The ohmic contact region (e.g., Ge diffusion region) is shown according to the thickness variation of the first layer 335-1 and the second layer 335-2.

[0217] For example, the diffusion shape of Ge may vary depending on the thickness of the AuGe constituting the first layer 335-1 and the heat treatment temperature. Therefore, by adjusting the thickness and the heat treatment temperature, at least one of the area ratio of the ohmic contact region and the reflectivity of the light-emitting element can be adjusted.

[0218] For example, considering the resistive characteristics, the minimum thickness of the AuGe constituting the first layer 335-1 can be 10 nm. In an exemplary embodiment, the thickness of the AuGe layer forming the first layer 335-1 can be from 10 nm to 50 nm. Therefore, the first contact layer 335 can occupy 5% to 20% of the total area of ​​the first surface.

[0219] first, Figure 20 The diagram shows the state where the thickness of the first layer 335-1 and the second layer 335-2 is 30 nm.

[0220] See Figure 20 (a) shows a photograph of the first surface (bottom surface) of the first conductive type semiconductor layer 331 of each circular light-emitting element. Figure 20 Image (b) shows the distribution of Ge atoms, and Figure 20 Image (c) shows the distribution of Au atoms.

[0221] Figure 21 The diagram shows the first layer 335-1 and the second layer 335-2 with thicknesses of 50 nm and 50 nm, respectively.

[0222] See Figure 21 (a) shows a photograph of the first surface (bottom surface) of the first conductive type semiconductor layer 331 of each circular light-emitting element. Figure 21 Image (b) shows the distribution of Ge atoms, and Figure 21 Image (c) shows the distribution of Au atoms.

[0223] As described above, the area ratio of the ohmic contact region may change as the thickness of the first layer 335-1 and the second layer 335-2 increases. Therefore, the reflectivity of the light-emitting element may also change.

[0224] Figure 22 This is a cross-sectional view of a display device using a light-emitting element according to an embodiment of the present disclosure.

[0225] See Figure 22 In the display device according to an embodiment of the present disclosure, the light-emitting element 330 constituting a unit sub-pixel may be disposed on a wiring substrate 310, on which a first electrode 312 is disposed. The wiring substrate 310 may include the first electrode 312 disposed on a substrate 311.

[0226] In the wiring substrate 310, a plurality of first electrodes 312 can be positioned on the substrate 311. Such first electrodes 312 can be used as wiring electrodes. The first electrodes 312 can be separated and disposed on the substrate 311. Therefore, the wiring electrodes can be used as data electrodes (pixel electrodes) or scan electrodes (common electrodes).

[0227] Although Figure 22The diagram shows a single light-emitting element 330, but a single light-emitting element 330 forming three unit sub-pixels can constitute a single pixel. Therefore, the light-emitting element 330 can include a red light-emitting element emitting red light, a green light-emitting element emitting green light, and a blue light-emitting element emitting blue light. Such unit pixels can be repeatedly disposed on the wiring substrate 310.

[0228] Although not shown, the first electrode 312 disposed on the wiring substrate 310 can be connected to a TFT layer in which thin-film transistors (TFTs) are disposed. Data electrodes (pixel electrodes) can be connected to such a TFT layer. A detailed description thereof is omitted here.

[0229] A spacer 320 for defining the mounting hole for the light-emitting element can be disposed between the wiring substrate 310 and the light-emitting element 330.

[0230] In an exemplary embodiment, at least one of the top and bottom surfaces of the light-emitting element 330 may be circular. For example, the light-emitting element 330 may be cylindrical or truncated conical.

[0231] 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 surface area of ​​the light-emitting element 330 near the first contact layer 335 may be larger than the surface area away from the first contact layer 335.

[0232] Furthermore, the display device 300 may include a first connection electrode 340 that electrically connects the first electrode 312 to one side of the light-emitting element 330. The first connection electrode 340 may be made of a highly conductive metal, such as Al, Mo, Cu, Ag, or Pt.

[0233] In an exemplary embodiment, the side of the light-emitting element 330 connected to the first connection electrode 340 may be a side surface of the light-emitting layer (active layer) 333 of the light-emitting element 330. For example, the first connection electrode 340 may be laterally connected to the surface formed by the light-emitting layer 333 of the light-emitting element 330. Such a first connection electrode 340 may extend to the side surface of the first conductivity type semiconductor layer 331 of the light-emitting element 330 to form a side surface 342, thereby being electrically connected to the first conductivity type semiconductor layer 331.

[0234] In this respect, the aluminum Al used for the first connecting electrode 340 and the reflective layer 336 of the light-emitting element 330 can be formed into an alloy. The formation of such an alloy can improve the thermal / electrical characteristics of the light-emitting element and the display device.

[0235] As described above, the first connecting electrode 340 may include a side surface 342 positioned on the side of the light-emitting element 330 and a bottom surface 343 located on the top surface of the base layer 320.

[0236] See Figure 22 The first connecting electrode 340 may be disposed on both sides of the light-emitting element 330. In some cases, the first connecting electrode 340 may be disposed to cover the side of the light-emitting element 330.

[0237] Furthermore, the first connecting electrode 340 can be electrically connected to the magnetic layer 337 of the light-emitting element 330. To increase the adhesion between the magnetic layer 337 and at least one of the first connecting electrodes 340, metals such as Cr and / or Ti can be added.

[0238] The passivation layer 338 can be positioned on the exterior of the side of the light-emitting element 330 connected to the first connecting electrode 340. As described above, the passivation layer 338 can be positioned on the outside of the light-emitting element 330, and the first connecting electrode 340 can be positioned below the passivation layer 338. Such a passivation layer 338 can protect the outer surface of the light-emitting element 330.

[0239] The planarization layer 350 can be positioned on the side of the first connecting electrode 340 and the light-emitting element 330. The planarization layer 350 can cover the first connecting electrode 340 and the light-emitting element 330. The upper surface of the planarization layer 350 can be flush with or higher than the upper surface of the light-emitting element 330.

[0240] In this regard, the second conductivity type semiconductor layer 332 on the upper side of the light-emitting element 330 can be exposed. For example, even if the upper side of the planarization layer 350 has a higher vertical height than the upper side of the light-emitting element 330, the second conductivity type semiconductor layer 332 of the light-emitting element 330 can still be exposed.

[0241] Furthermore, a second connection electrode 361 may be provided, positioned on the planarization layer 350 and electrically connected to the other side of the light-emitting element 330. For example, such a second connection electrode 361 may include a transparent electrode, such as ITO. Therefore, light emitted from the light-emitting element 330 can pass through the second connection electrode 361 and be emitted outward.

[0242] As described above, the first electrode 312 and the second electrode 360 ​​can be used as wiring electrodes. For example, the first electrode 312 can be used as a data electrode (pixel electrode), and the second electrode 360 ​​can be used as a scan electrode (common electrode).

[0243] See Figure 22 The second connection electrode 361 may be partially located on the light-emitting element 330. In some cases, such a second connection electrode 361 can be connected to another second connection electrode via the second electrode 360.

[0244] The above description is merely an exemplary illustration of this disclosure, and those skilled in the art can make various modifications and variations to this disclosure without departing from its essential characteristics.

[0245] Therefore, the embodiments disclosed herein are intended to illustrate the disclosure and not to limit it, and the scope of the disclosure is not limited by such embodiments.

[0246] The scope of protection of this disclosure is defined by the appended claims, and all modifications and equivalents falling within the scope of the claims shall be included within the scope of this disclosure.

[0247] Industrial applicability

[0248] According to this disclosure, a semiconductor light-emitting device (e.g., a micro LED) and a display device using the light-emitting device can be provided.

Claims

1. A light-emitting element, the light-emitting element comprising: First conductivity type semiconductor layer; Second type of conductive semiconductor layer; An active layer is disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; A first contact layer, the first contact layer having at least a portion electrically connected in a discontinuous manner to a first surface of the first conductivity type semiconductor layer; as well as A reflective layer disposed on the first contact layer.

2. The light-emitting element according to claim 1, wherein, The first contact layer forms an ohmic contact with the first conductivity type semiconductor layer at a portion that is electrically connected to the first surface in a discontinuous manner.

3. The light-emitting element according to claim 1, wherein, The ohmic contact is formed by diffusing at least a portion of the first contact layer into the first conductivity type semiconductor layer.

4. The light-emitting element according to claim 1, wherein, The first contact layer includes: A first metal, wherein the first metal forms an ohmic contact with a semiconductor layer of the first conductivity type; and A second metal used to diffuse the first metal.

5. The light-emitting element according to claim 4, wherein, The first metal and the second metal form an alloy.

6. The light-emitting element according to claim 4, wherein, The first metal includes regions diffused into the semiconductor layer of the first conductivity type.

7. The light-emitting element according to claim 4, wherein, An interface exists between the first contact layer and the reflective layer.

8. The light-emitting element according to claim 7, wherein, The reflective layer is a single metal layer containing Ag.

9. The light-emitting element according to claim 4, wherein, The first metal includes Ge, and the second metal includes Au.

10. The light-emitting element according to claim 1, wherein the light-emitting element further comprises a magnetic layer disposed on the reflective layer.

11. The light-emitting element according to claim 1, further comprising 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 conductivity type semiconductor layer.

12. The light-emitting element according to claim 1, wherein, The first contact layer occupies 5% to 20% of the total area of ​​the first surface.

13. A method for manufacturing a light-emitting element, the light-emitting element comprising a semiconductor layer, the semiconductor layer comprising a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, the method comprising the following steps: A first contact layer is formed on the first conductivity type semiconductor layer; as well as A reflective layer is formed on the first metal layer. The step of forming the first contact layer includes: A first layer is formed, in which a first metal and a second metal are alloyed on the first conductivity type semiconductor layer; A second layer comprising the second metal is formed on the first layer; Perform heat treatment; and Remove the second layer.

14. The method according to claim 13, wherein, The steps for forming the first contact layer include: A photoresist layer is formed that opens the first surface of the first conductivity type semiconductor layer; The first layer and the second layer are continuously formed on the first surface; and Remove the photoresist.

15. The method according to claim 13, wherein, The step of forming the first contact layer is performed simultaneously with the second conductivity type semiconductor layer being attached to the transfer substrate through the sacrificial layer.

16. The method according to claim 13, wherein, The first metal includes Ge, and the second metal includes Au.

17. The method of claim 13, further comprising the step of: A reflective layer is formed on the surface where the second layer has been removed.

18. The method according to claim 17, wherein, The reflective layer is a single metal layer comprising Ag.

19. The method of claim 13, further comprising the step of: A magnetic layer is formed on the reflective layer.

20. A display device using a semiconductor light-emitting element, the display device comprising: A wiring substrate, on which a first electrode is disposed; A light-emitting element, the light-emitting element including a semiconductor layer disposed on the wiring substrate to form a unit sub-pixel; A first connecting electrode electrically connects 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 connecting electrode; as well as The second connection electrode is located on the planarization layer and is electrically connected to the opposite side of the semiconductor layer of the light-emitting element. The light-emitting element includes: A first contact layer, the first contact layer having at least a portion electrically connected in a discontinuous manner to a first surface of the semiconductor layer; and A reflective layer disposed on the first contact layer.

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