Patent ID: 12243861

BEST MODE

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and redundant description thereof will be omitted. As used herein, the suffixes “module” and “unit” are added or used interchangeably to facilitate preparation of this specification and are not intended to suggest distinct meanings or functions. In describing embodiments disclosed in this specification, relevant well-known technologies may not be described in detail in order not to obscure the subject matter of the embodiments disclosed in this specification. In addition, it should be noted that the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical spirit disclosed in the present specification.

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

In addition, when an element such as a layer, region or module is described as being “on” another element, it is to be understood that the element may be directly on the other element or there may be an intermediate element between them.

The display device described herein is a concept including all display devices that display information with a unit pixel or a set of unit pixels. Therefore, the display device may be applied not only to finished products but also to parts. For example, a panel corresponding to a part of a digital TV also independently corresponds to the display device in the present specification. The finished products include a mobile phone, a smartphone, a laptop, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet, an Ultrabook, a digital TV, a desktop computer, and the like.

However, it will be readily apparent to those skilled in the art that the configuration according to the embodiments described herein is applicable even to a new product that will be developed later as a display device.

In addition, the semiconductor light emitting element mentioned in this specification is a concept including an LED, a micro LED, and the like, and may be used interchangeably therewith.

FIG.1is a conceptual view illustrating an embodiment of a display device using a semiconductor light emitting element according to the present disclosure.

As shown inFIG.1, information processed by a controller (not shown) of a display device100may be displayed using a flexible display.

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

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 like paper while maintaining the display characteristics of a conventional flat panel display.

When the flexible display remains in an unbent state (e.g., a state having an infinite radius of curvature) (hereinafter referred to as a first state), the display area of the flexible display forms a flat surface. When the display in the first state is changed to a bent state (e.g., a state having a finite radius of curvature) (hereinafter referred to as a second state) by external force, the display area may be a curved surface. As shown inFIG.1, the information displayed in the second state may be visual information output on a curved surface. Such visual information may be implemented by independently controlling the light emission of sub-pixels arranged in a matrix form. The unit pixel may mean, for example, a minimum unit for implementing one color.

The unit pixel of the flexible display may be implemented by a semiconductor light emitting element. In the present disclosure, a light emitting diode (LED) is exemplified as a type of the semiconductor light emitting element configured to convert electric current into light. The LED may be formed in a small size, and may thus serve as a unit pixel even in the second state.

Hereinafter, a flexible display implemented using the LED will be described in more detail with reference to the drawings.

FIG.2is a partially enlarged view showing part A ofFIG.1.

FIGS.3A and3Bare cross-sectional views taken along lines B-B and C-C inFIG.2.

FIG.4is a conceptual view illustrating the flip-chip type semiconductor light emitting element ofFIGS.3A and3B.

FIGS.5A to5Care conceptual views illustrating various examples of implementation of colors in relation to a flip-chip type semiconductor light emitting element.

As shown inFIGS.2,3A and3B, the display device100using a passive matrix (PM) type semiconductor light emitting element is exemplified as the display device100using a semiconductor light emitting element. However, the examples described below are also applicable to an active matrix (AM) type semiconductor light emitting element.

The display device100shown inFIG.1may include a substrate110, a first electrode120, a conductive adhesive layer130, a second electrode140, and at least one semiconductor light emitting element150, as shown inFIG.2.

The substrate110may be a flexible substrate. For example, to implement a flexible display device, the substrate110may include glass or polyimide (PI). Any insulative and flexible material such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) may be employed. In addition, the substrate110may be formed of either a transparent material or an opaque material.

The substrate110may be a wiring substrate on which the first electrode120is disposed. Thus, the first electrode120may be positioned on the substrate110.

As shown inFIG.3A, an insulating layer160may be disposed on the substrate110on which the first electrode120is positioned, and an auxiliary electrode170may be positioned on the insulating layer160. In this case, a stack in which the insulating layer160is laminated on the substrate110may be a single wiring substrate. More specifically, the insulating layer160may be formed of an insulative and flexible material such as PI, PET, or PEN, and may be integrated with the substrate110to form a single substrate.

The auxiliary electrode170, which is an electrode that electrically connects the first electrode120and the semiconductor light emitting element150, is positioned on the insulating layer160, and is disposed to correspond to the position of the first electrode120. For example, the auxiliary electrode170may have a dot shape and may be electrically connected to the first electrode120by an electrode hole171formed through the insulating layer160. The electrode hole171may be formed by filling a via hole with a conductive material.

As shown inFIG.2or3A, a conductive adhesive layer130may be formed on one surface of the insulating layer160, but embodiments of the present disclosure are not limited thereto. For example, a layer performing a specific function may be formed between the insulating layer160and the conductive adhesive layer130, or the conductive adhesive layer130may be disposed on the substrate110without the insulating layer160. In a structure in which the conductive adhesive layer130is disposed on the substrate110, the conductive adhesive layer130may serve as an insulating layer.

The conductive adhesive layer130may be a layer having adhesiveness and conductivity. For this purpose, a material having conductivity and a material having adhesiveness may be mixed in the conductive adhesive layer130. In addition, the conductive adhesive layer130may have ductility, thereby providing making the display device flexible.

As an example, the conductive adhesive layer130may be an anisotropic conductive film (ACF), an anisotropic conductive paste, a solution containing conductive particles, or the like. The conductive adhesive layer130may be configured as a layer that allows electrical interconnection in the direction of the Z-axis extending through the thickness, but is electrically insulative in the horizontal X-Y direction. Accordingly, the conductive adhesive layer130may be referred to as a Z-axis conductive layer (hereinafter, referred to simply as a “conductive adhesive layer”).

The ACF is a film in which an anisotropic conductive medium is mixed with an insulating base member. When the ACF is subjected to heat and pressure, only a specific portion thereof becomes conductive by the anisotropic conductive medium. Hereinafter, it will be described that heat and pressure are applied to the ACF. However, another method may be used to make the ACF partially conductive. The other method may be, for example, application of only one of the heat and pressure or UV curing.

In addition, the anisotropic conductive medium may be, for example, conductive balls or conductive particles. For example, the ACF may be a film in which conductive balls are mixed with an insulating base member. Thus, when heat and pressure are applied to the ACF, only a specific portion of the ACF is allowed to be conductive by the conductive balls. The ACF may contain a plurality of particles formed by coating the core of a conductive material with an insulating film made of a polymer material. In this case, as the insulating film is destroyed in a portion to which heat and pressure are applied, the portion is made to be conductive by the core. At this time, the cores may be deformed to form layers that contact each other in the thickness direction of the film. As a more specific example, heat and pressure are applied to the whole ACF, and an electrical connection in the Z-axis direction is partially formed by the height difference of a counterpart adhered by the ACF.

As another example, the ACF may contain a plurality of particles formed by coating an insulating core with a conductive material. In this case, as the conductive material is deformed (pressed) in a portion to which heat and pressure are applied, the portion is made to be conductive in the thickness direction of the film. As another example, the conductive material may be disposed through the insulating base member in the Z-axis direction to provide conductivity in the thickness direction of the film. In this case, the conductive material may have a pointed end.

The ACF may be a fixed array ACF in which conductive balls are inserted into one surface of the insulating base member. More specifically, the insulating base member may be formed of an adhesive material, and the conductive balls may be intensively disposed on the bottom portion of the insulating base member. Thus, when the base member is subjected to heat and pressure, it may be deformed together with the conductive balls, exhibiting conductivity in the vertical direction.

However, the present disclosure is not necessarily limited thereto, and the ACF may be formed by randomly mixing conductive balls in the insulating base member, or may be composed of a plurality of layers with conductive balls arranged on one of the layers (as a double-ACF).

The anisotropic conductive paste may be a combination of a paste and conductive balls, and may be a paste in which conductive balls are mixed with an insulating and adhesive base material. Also, the solution containing conductive particles may be a solution containing any conductive particles or nanoparticles.

Referring back toFIG.3A, the second electrode140is positioned on the insulating layer160and spaced apart from the auxiliary electrode170. That is, the conductive adhesive layer130is disposed on the insulating layer160having the auxiliary electrode170and the second electrode140positioned thereon.

After the conductive adhesive layer130is formed with the auxiliary electrode170and the second electrode140positioned on the insulating layer160, the semiconductor light emitting element150is connected thereto in a flip-chip form by applying heat and pressure. Thereby, the semiconductor light emitting element150is electrically connected to the first electrode120and the second electrode140.

Referring toFIG.4, the semiconductor light emitting element may be a flip chip-type light emitting device.

For example, the semiconductor light emitting element may include a p-type electrode156, a p-type semiconductor layer155on which the p-type electrode156is formed, an active layer154formed on the p-type semiconductor layer155, an n-type semiconductor layer153formed on the active layer154, and an n-type electrode152disposed on the n-type semiconductor layer153and horizontally spaced apart from the p-type electrode156. In this case, the p-type electrode156may be electrically connected to the auxiliary electrode170, which is shown inFIGS.3A and3B, by the conductive adhesive layer130, and the n-type electrode152may be electrically connected to the second electrode140.

Referring back toFIGS.2,3A and3B, the auxiliary electrode170may be elongated in one direction. Thus, one auxiliary electrode may be electrically connected to the plurality of semiconductor light emitting elements150. For example, p-type electrodes of semiconductor light emitting elements on left and right sides of an auxiliary electrode may be electrically connected to one auxiliary electrode.

More specifically, the semiconductor light emitting element150may be press-fitted into the conductive adhesive layer130by heat and pressure. Thereby, only the portions of the semiconductor light emitting element150between the p-type electrode156and the auxiliary electrode170and between the n-type electrode152and the second electrode140may exhibit conductivity, and the other portions of the semiconductor light emitting element150do not exhibit conductivity as they are not press-fitted. In this way, the conductive adhesive layer130interconnects and electrically connects the semiconductor light emitting element150and the auxiliary electrode170and interconnects and electrically connects the semiconductor light emitting element150and the second electrode140.

The plurality of semiconductor light emitting elements150may constitute a light emitting device array, and a phosphor conversion layer180may be formed on the light emitting device array.

The light emitting device array may include a plurality of semiconductor light emitting elements having different luminance values. Each semiconductor light emitting element150may constitute a unit pixel and may be electrically connected to the first electrode120. For example, a plurality of first electrodes120may 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 plurality of first electrodes.

In addition, since the semiconductor light emitting elements are connected in a flip-chip form, semiconductor light emitting elements grown on a transparent dielectric substrate may be used. The semiconductor light emitting elements may be, for example, nitride semiconductor light emitting elements. Since the semiconductor light emitting element150has excellent luminance, it may constitute an individual unit pixel even when it has a small size.

As shown inFIG.3, a partition wall190may be formed between the semiconductor light emitting elements150. In this case, the partition wall190may serve to separate individual unit pixels from each other, and may be integrated with the conductive adhesive layer130. For example, by inserting the semiconductor light emitting element150into the ACF, the base member of the ACF may form the partition wall.

In addition, when the base member of the ACF is black, the partition wall190may have reflectance and increase contrast even without a separate black insulator.

As another example, a reflective partition wall may be separately provided as the partition wall190. In this case, the partition wall190may include a black or white insulator depending on the purpose of the display device. When a partition wall including a white insulator is used, reflectivity may be increased. When a partition wall including a black insulator is used, it may have reflectance and increase contrast.

The phosphor conversion layer180may be positioned on the outer surface of the semiconductor light emitting element150. For example, the semiconductor light emitting element150may be a blue semiconductor light emitting element that emits blue (B) light, and the phosphor conversion layer180may function to convert the blue (B) light into a color of a unit pixel. The phosphor conversion layer180may be a red phosphor181or a green phosphor182constituting an individual pixel.

That is, the red phosphor181capable of converting blue light into red (R) light may be laminated on a blue semiconductor light emitting element at a position of a unit pixel of red color, and the green phosphor182capable of converting blue light into green (G) light may be laminated on the blue semiconductor light emitting element at a position of a unit pixel of green color. Only the blue semiconductor light emitting element may be used alone in the portion constituting the unit pixel of blue color. In this case, unit pixels of red (R), green (G), and blue (B) may constitute one pixel. More specifically, a phosphor of one color may be laminated along each line of the first electrode120. Accordingly, one line on the first electrode120may be an electrode for controlling one color. That is, red (R), green (G), and blue (B) may be sequentially disposed along the second electrode140, thereby implementing a unit pixel.

However, embodiments of the present disclosure are not limited thereto. Unit pixels of red (R), green (G), and blue (B) may be implemented by combining the semiconductor light emitting element150and the quantum dot (QD) rather than using the phosphor.

Also, a black matrix191may be disposed between the phosphor conversion layers to improve contrast. That is, the black matrix191may improve contrast of light and darkness.

However, embodiments of the present disclosure are not limited thereto, and anther structure may be applied to implement blue, red, and green colors.

Referring toFIG.5A, each semiconductor light emitting element may be implemented as a high-power light emitting device emitting light of various colors including blue by using gallium nitride (GaN) as a main material and adding indium (In) and/or aluminum (Al).

In this case, each semiconductor light emitting element may be a red, green, or blue semiconductor light emitting element to form a unit pixel (sub-pixel). For example, red, green, and blue semiconductor light emitting elements R, G, and B may be alternately disposed, and unit pixels of red, green, and blue may constitute one pixel by the red, green and blue semiconductor light emitting elements. Thereby, a full-color display may be implemented.

Referring toFIG.5B, the semiconductor light emitting element150amay include a white light emitting device W having a yellow phosphor conversion layer, which is provided for each device. In this case, in order to form a unit pixel, a red phosphor conversion layer181, a green phosphor conversion layer182, and a blue phosphor conversion layer183may be disposed on the white light emitting device W. In addition, a unit pixel may be formed using a color filter repeating red, green, and blue on the white light emitting device W.

Referring toFIG.5C, a red phosphor conversion layer184, a green phosphor conversion layer185, and a blue phosphor conversion layer185may be provided on a ultraviolet light emitting device. Not only visible light but also ultraviolet (UV) light may be used in the entire region of the semiconductor light emitting element. In an embodiment, UV may be used as an excitation source of the upper phosphor in the semiconductor light emitting element.

Referring back to this example, the semiconductor light emitting element is positioned on the conductive adhesive layer to constitute a unit pixel in the display device. Since the semiconductor light emitting element has excellent luminance, individual unit pixels may be configured despite even when the semiconductor light emitting element has a small size.

Regarding the size of such an individual semiconductor light emitting element, the length of each side of the device may be, for example, 80 μm or less, and the device may have a rectangular or square shape. When the semiconductor light emitting element has a rectangular shape, the size thereof may be less than or equal to 20 μm×80 μm.

In addition, even when a square semiconductor light emitting element having a side length of 10 μm is used as a unit pixel, sufficient brightness to form a display device may be obtained.

Therefore, for example, in case of a rectangular pixel having a unit pixel size of 600 μm×300 μm (i.e., one side by the other side), a distance of a semiconductor light emitting element becomes sufficiently long relatively.

Thus, in this case, it is able to implement a flexible display device having high image quality over HD image quality.

The above-described display device using the semiconductor light emitting element may be prepared by a new fabricating method. Such a fabricating method will be described with reference toFIG.6as follows.

FIG.6shows cross-sectional views of a method of fabricating a display device using a semiconductor light emitting element according to the present disclosure.

Referring toFIG.6, first of all, a conductive adhesive layer130is formed on an insulating layer160located between an auxiliary electrode170and a second electrode140. The insulating layer160is tacked on a wiring substrate110. On the wiring substrate110, a first electrode120, the auxiliary electrode170and the second electrode140are disposed. In this case, the first electrode120and the second electrode140may be disposed in mutually orthogonal directions, respectively. In order to implement a flexible display device, the wiring substrate110and the insulating layer160may include glass or polyimide (PI) each.

For example, the conductive adhesive layer130may be implemented by an anisotropic conductive film. To this end, an anisotropic conductive film may be coated on the substrate on which the insulating layer160is located.

Subsequently, a temporary substrate112, on which a plurality of semiconductor light emitting elements150configuring individual pixels are located to correspond to locations of the auxiliary electrode170and the second electrodes140, is disposed in a manner that the semiconductor light emitting element150confronts the auxiliary electrode170and the second electrode140.

In this regard, the temporary112substrate112is a growing substrate for growing the semiconductor light emitting element150and may include a sapphire or silicon substrate.

The semiconductor light emitting element is configured to have a space and size for configuring a display device when formed in unit of wafer, thereby being effectively used for the display device.

Subsequently, the wiring substrate110and the temporary substrate112are thermally compressed together. By the thermocompression, the wiring substrate110and the temporary substrate112are bonded together. Owing to the property of an anisotropic conductive film having conductivity by thermocompression, only a portion among the semiconductor light emitting element150, the auxiliary electrode170and the second electrode140has conductivity, via which the electrodes and the semiconductor light emitting element150may be connected electrically. In this case, the semiconductor light emitting element150is inserted into the anisotropic conductive film, by which a partition may be formed between the semiconductor light emitting elements150.

Then the temporary substrate112is removed. For example, the temporary substrate112may be removed using Laser Lift-Off (LLO) or Chemical Lift-Off (CLO).

Finally, by removing the temporary substrate112, the semiconductor light emitting elements150exposed externally. If necessary, the wiring substrate110to which the semiconductor light emitting elements150are coupled may be coated with silicon oxide (SiOx) or the like to form a transparent insulating layer (not shown).

In addition, a step of forming a phosphor layer on one side of the semiconductor light emitting element150may be further included. For example, the semiconductor light emitting element150may include a blue semiconductor light emitting element emitting Blue (B) light, and a red or green phosphor for converting the blue (B) light into a color of a unit pixel may form a layer on one side of the blue semiconductor light emitting element.

The above-described fabricating method or structure of the display device using the semiconductor light emitting element may be modified into various forms. For example, the above-described display device may employ a vertical semiconductor light emitting element.

Furthermore, a modification or embodiment described in the following may use the same or similar reference numbers for the same or similar configurations of the former example and the former description may apply thereto.

FIG.7is a perspective diagram of a display device using a semiconductor light emitting element according to another embodiment of the present disclosure,FIG.8is a cross-sectional diagram taken along a cutting line D-D shown inFIG.8, andFIG.9is a conceptual diagram showing a vertical type semiconductor light emitting element shown inFIG.8.

Referring to the present drawings, a display device may employ a vertical semiconductor light emitting device of a Passive Matrix (PM) type.

The display device includes a substrate210, a first electrode220, a conductive adhesive layer230, a second electrode240and at least one semiconductor light emitting element250.

The substrate210is a wiring substrate on which the first electrode220is disposed and may contain polyimide (PI) to implement a flexible display device. Besides, the substrate210may use any substance that is insulating and flexible.

The first electrode210is located on the substrate210and may be formed as a bar type electrode that is long in one direction. The first electrode220may be configured to play a role as a data electrode.

The conductive adhesive layer230is formed on the substrate210where the first electrode220is located. Like a display device to which a light emitting device of a flip chip type is applied, the conductive adhesive layer230may include one of an Anisotropic Conductive Film (ACF), an anisotropic conductive paste, a conductive particle contained solution and the like. Yet, in the present embodiment, a case of implementing the conductive adhesive layer230with the anisotropic conductive film is exemplified.

After the conductive adhesive layer has been placed in the state that the first electrode220is located on the substrate210, if the semiconductor light emitting element250is connected by applying heat and pressure thereto, the semiconductor light emitting element250is electrically connected to the first electrode220. In doing so, the semiconductor light emitting element250is preferably disposed to be located on the first electrode220.

If heat and pressure is applied to an anisotropic conductive film, as described above, since the anisotropic conductive film has conductivity partially in a thickness direction, the electrical connection is established. Therefore, the anisotropic conductive film is partitioned into a conductive portion and a non-conductive portion.

Furthermore, since the anisotropic conductive film contains an adhesive component, the conductive adhesive layer230implements mechanical coupling between the semiconductor light emitting element250and the first electrode220as well as mechanical connection.

Thus, the semiconductor light emitting element250is located on the conductive adhesive layer230, via which an individual pixel is configured in the display device. As the semiconductor light emitting element250has excellent luminance, an individual unit pixel may be configured in small size as well. Regarding a size of the individual semiconductor light emitting element250, a length of one side may be equal to or smaller than 80 μm for example and the individual semiconductor light emitting element250may include a rectangular or square element. For example, the rectangular element may have a size equal to or smaller than 20 μm×80 PM.

The semiconductor light emitting element250may have a vertical structure.

Among the vertical type semiconductor light emitting elements, a plurality of second electrodes240respectively and electrically connected to the vertical type semiconductor light emitting elements250are located in a manner of being disposed in a direction crossing with a length direction of the first electrode220.

Referring toFIG.9, the vertical type semiconductor light emitting element250includes a p-type electrode256, a p-type semiconductor layer255formed on the p-type electrode256, an active layer254formed on the p-type semiconductor layer255, an n-type semiconductor layer253formed on the active layer254, and an n-type electrode252formed on then-type semiconductor layer253. In this case, the p-type electrode256located on a bottom side may be electrically connected to the first electrode220by the conductive adhesive layer230, and the n-type electrode252located on a top side may be electrically connected to a second electrode240described later. Since such a vertical type semiconductor light emitting element250can dispose the electrodes at top and bottom, it is considerably advantageous in reducing a chip size.

Referring toFIG.8again, a phosphor layer280may formed on one side of the semiconductor light emitting element250. For example, the semiconductor light emitting element250may include a blue semiconductor light emitting element251emitting blue (B) light, and a phosphor layer280for converting the blue (B) light into a color of a unit pixel may be provided. In this regard, the phosphor layer280may include a red phosphor281and a green phosphor282configuring an individual pixel.

Namely, at a location of configuring a red unit pixel, the red phosphor281capable of converting blue light into red (R) light may be stacked on a blue semiconductor light emitting element. At a location of configuring a green unit pixel, the green phosphor282capable of converting blue light into green (G) light may be stacked on the blue semiconductor light emitting element. Moreover, the blue semiconductor light emitting element may be singly usable for a portion that configures a blue unit pixel. In this case, the unit pixels of red (R), green (G) and blue (B) may configure a single pixel.

Yet, the present disclosure is non-limited by the above description. In a display device to which a light emitting element of a flip chip type is applied, as described above, a different structure for implementing blue, red and green may be applicable.

Regarding the present embodiment again, the second electrode240is located between the semiconductor light emitting elements250and connected to the semiconductor light emitting elements electrically. For example, the semiconductor light emitting elements250are disposed in a plurality of columns, and the second electrode240may be located between the columns of the semiconductor light emitting elements250.

Since a distance between the semiconductor light emitting elements250configuring the individual pixel is sufficiently long, the second electrode240may be located between the semiconductor light emitting elements250.

The second electrode240may be formed as an electrode of a bar type that is long in one direction and disposed in a direction vertical to the first electrode.

In addition, the second electrode240and the semiconductor light emitting element250may be electrically connected to each other by a connecting electrode protruding from the second electrode240. Particularly, the connecting electrode may include a n-type electrode of the semiconductor light emitting element250. For example, the n-type electrode is formed as an ohmic electrode for ohmic contact, and the second electrode covers at least one portion of the ohmic electrode by printing or deposition. Thus, the second electrode240and the n-type electrode of the semiconductor light emitting element250may be electrically connected to each other.

Referring toFIG.8again, the second electrode240may be located on the conductive adhesive layer230. In some cases, a transparent insulating layer (not shown) containing silicon oxide (SiOx) and the like may be formed on the substrate210having the semiconductor light emitting element250formed thereon. If the second electrode240is placed after the transparent insulating layer has been formed, the second electrode240is located on the transparent insulating layer. Alternatively, the second electrode240may be formed in a manner of being spaced apart from the conductive adhesive layer230or the transparent insulating layer.

If a transparent electrode of Indium Tin Oxide (ITO) or the like is sued to place the second electrode240on the semiconductor light emitting element250, there is a problem that ITO substance has poor adhesiveness to an n-type semiconductor layer. Therefore, according to the present disclosure, as the second electrode240is placed between the semiconductor light emitting elements250, it is advantageous in that a transparent electrode of ITO is not used. Thus, light extraction efficiency can be improved using a conductive substance having good adhesiveness to an n-type semiconductor layer as a horizontal electrode without restriction on transparent substance selection.

Referring toFIG.8again, a partition290may be located between the semiconductor light emitting elements250. Namely, in order to isolate the semiconductor light emitting element250configuring the individual pixel, the partition290may be disposed between the vertical type semiconductor light emitting elements250. In this case, the partition290may play a role in separating the individual unit pixels from each other and be formed with the conductive adhesive layer230as an integral part. For example, by inserting the semiconductor light emitting element250in an anisotropic conductive film, a base member of the anisotropic conductive film may form the partition.

In addition, if the base member of the anisotropic conductive film is black, the partition290may have reflective property as well as a contrast ratio may be increased, without a separate block insulator.

For another example, a reflective partition may be separately provided as the partition190. The partition290may include a black or white insulator depending on the purpose of the display device.

In case that the second electrode240is located right onto the conductive adhesive layer230between the semiconductor light emitting elements250, the partition290may be located between the vertical type semiconductor light emitting element250and the second electrode240each. Therefore, an individual unit pixel may be configured using the semiconductor light emitting element250. Since a distance between the semiconductor light emitting elements250is sufficiently long, the second electrode240can be placed between the semiconductor light emitting elements250. And, it may bring an effect of implementing a flexible display device having HD image quality.

In addition, as shown inFIG.8, a black matrix291may be disposed between the respective phosphors for the contrast ratio improvement. Namely, the black matrix291may improve the contrast between light and shade.

FIG.10is a diagram schematically illustrating a method for manufacturing a display device using a semiconductor light emitting element.

First, the semiconductor light emitting elements are formed on the growing substrate (S1010). The semiconductor light emitting elements may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer. In addition, a first conductivity type electrode formed on the first conductivity type semiconductor layer and a second conductivity type electrode formed on the second conductivity type semiconductor layer may be further included.

The semiconductor light emitting elements may be a horizontal type semiconductor light emitting element or the vertical type semiconductor light emitting element. However, in the case of the vertical type semiconductor light emitting element, because the first conductivity type electrode and the second conductivity type electrode face each other, a process of separating the semiconductor light emitting element from the growing substrate and forming a conductivity type electrode in one direction is added in a subsequent process. In addition, as will be described later, the semiconductor light emitting element may include a magnetic layer for a self-assembly process.

In order to utilize the semiconductor light emitting elements in the display device, in general, three types of semiconductor light emitting elements that emit light of colors corresponding to red (R), green (G), and blue (B) are required. Because semiconductor light emitting elements emitting light of one color are formed on one growing substrate, a separate substrate is required for the display device that implements individual unit pixels using the three types of semiconductor light emitting elements. Therefore, individual semiconductor light emitting elements must be separated from the growing substrate and assembled or transferred onto a final substrate. The final substrate is a substrate on which a process of forming a wiring electrode for applying a voltage to the semiconductor light emitting element such that the semiconductor light emitting element may emit light is performed.

Therefore, the semiconductor light emitting elements emitting the light of the respective colors may be transferred back to the final substrate after moving to the transfer substrate or the assembly substrate (S1020). In some cases, when performing the wiring process directly on the transfer substrate or the assembly substrate, the transfer substrate or the assembly substrate serves as the final substrate.

The method (S1020) for disposing the semiconductor light emitting element on the transfer substrate or the assembly substrate may be roughly divided into three types.

A first type is a method (S1021) for moving the semiconductor light emitting element from the growing substrate to the transfer substrate by the stamp process. The stamp process refers to a process of separating the semiconductor light emitting element from the growing substrate through a protrusion using a substrate that is made of a flexible material and having the adhesive protrusion. By adjusting a spacing and an arrangement of the protrusions, the semiconductor light emitting element of the growing substrate may be selectively separated.

A second type is a method (S1022) for assembling the semiconductor light emitting element onto the assembly substrate using the self-assembly process. For the self-assembly process, the semiconductor light emitting element must exist independently by being separated from the growing substrate, so that the semiconductor light emitting elements are separated from the growing substrate through a laser lift-off (LLO) process or the like as much as the required number of semiconductor light emitting elements. Thereafter, the semiconductor light emitting elements are dispersed in a fluid and assembled onto the assembly substrate using an electromagnetic field.

The self-assembly process may simultaneously assemble the semiconductor light emitting elements that respectively implement the R, G, and B colors on one assembly substrate, or assemble the semiconductor light emitting element of the individual color through an individual assembly substrate.

A third type is a method (S1023) for mixing the stamp process and the self-assembly process. First, the semiconductor light emitting elements are placed on the assembly substrate through the self-assembly process, and then the semiconductor light emitting elements are moved to the final substrate through the stamp process. In the case of the assembly substrate, because it is difficult to implement the assembly substrate in a large area due to a location of the assembly substrate during the self-assembly process, a contact with the fluid, an influence of the electromagnetic fields, or the like, a process of transferring the semiconductor light emitting elements to the final substrate of a large area after assembling the semiconductor light emitting elements using an assembly substrate of an appropriate area may be performed several times with the stamp process.

When a plurality of semiconductor light emitting elements constituting the individual unit pixel are placed on the final substrate, the wiring process for electrically connecting the semiconductor light emitting elements to each other is performed (S1030).

The wiring electrode formed through the wiring process electrically connects the semiconductor light emitting elements assembled or transferred onto the substrate to the substrate. In addition, a transistor for driving an active matrix may be previously formed beneath the substrate. Accordingly, the wiring electrode may be electrically connected to the transistor.

In one example, innumerable semiconductor light emitting elements are required for a large-area display device, so that the self-assembly process is preferable. In order to further improve an assembly speed, among the self-assembly processes, it may be preferred that the semiconductor light emitting elements of the respective colors are simultaneously assembled onto one assembly substrate. In addition, in order for the semiconductor light emitting elements of the respective colors to be assembled at predetermined specific positions on the assembly substrate, it may be required for the semiconductor light emitting elements to have a mutually exclusive structure.

FIG.11is a diagram showing one embodiment of a method for assembling a semiconductor light emitting element onto a substrate by a self-assembly process.

FIG.12is an enlarged view of a portion E inFIG.11.

Referring toFIGS.11and12, a semiconductor light emitting element1150may be input into a chamber1130filled with a fluid1120.

Thereafter, the assembly substrate1110may be disposed on the chamber1130. According to an embodiment, the assembly substrate1110may be introduced into the chamber1130. In this regard, a direction in which the assembly substrate1110is introduced is a direction in which an assembly groove1111of the assembly substrate1110faces the fluid1120.

A pair of electrodes1112and1113corresponding to each semiconductor light emitting element1150to be assembled may be formed on the assembly substrate1110. The electrodes1112and1113may be implemented as transparent electrodes (ITO) or may be implemented using other common materials. The electrodes1112and1113correspond to assembly electrodes that stably fix the semiconductor light emitting element1150in contact with the assembly electrodes1112and1113by generating an electric field as a voltage is applied thereto.

Specifically, an alternating voltage may be applied to the electrodes1112and1113, and the semiconductor light emitting element1150floating around the electrodes1112and1113may have a polarity by dielectric polarization. In addition, the dielectrically polarized semiconductor light emitting element may be moved in a specific direction or fixed by a non-uniform electric field formed around the electrodes1112and1113. This is referred to as dielectrophoresis. In a self-assembly process of the present disclosure, the semiconductor light emitting element1150may be stably fixed into the assembly groove1111using the dielectrophoresis.

In addition, a spacing between the assembly electrodes1112and1113may be, for example, smaller than a width of the semiconductor light emitting element1150and a diameter of the assembly groove1111, so that an assembly position of the semiconductor light emitting element1150using the electric field may be more precisely fixed.

In addition, an assembly insulating layer1114may be formed on the assembly electrodes1112and1113to protect the electrodes1112and1113from the fluid1120and to prevent leakage of current flowing through the assembly electrodes1112and1113. For example, the assembled insulating film1114may be composed of a single layer or multiple layers of an inorganic insulator such as silica or alumina or an organic insulator. In addition, the assembly insulating layer1114may have a minimum thickness for preventing damage to the assembly electrodes1112and1113when assembling the semiconductor light emitting element1150and may have a maximum thickness for stably assembling the semiconductor light emitting element1150.

A partition wall1115may be formed on the assembly insulating layer1114. A partial region of the partition wall1115may be located above the assembly electrodes1112and1113, and the remaining region thereof may be located above the assembly substrate1110.

For example, when manufacturing the assembly substrate1110, as a portion of the partition wall formed on the entire assembly insulating layer1114is removed, the assembly groove1111in which each of the semiconductor light emitting elements1150is coupled to the assembly substrate1110may be defined.

As shown inFIG.12, the assembly groove1111into which the semiconductor light emitting element1150is coupled may be defined in the assembly substrate1110and a surface in which the assembly groove1111is defined may be in contact with the fluid1120. The assembly groove1111may guide the accurate assembly position of the semiconductor light emitting element1150.

In addition, the partition wall1115may be formed to have a certain inclination from an opening of the assembly groove1111toward a bottom surface. For example, by adjusting the inclination of the partition wall1115, the assembly groove1111may have the opening and the bottom surface and an area of the opening may be larger than an area of the bottom surface. Accordingly, the semiconductor light emitting element1150may be assembled at an accurate position on the bottom surface of the assembly groove1111.

The assembly groove1111may have a shape and a size corresponding to those of the semiconductor light emitting element1150to be assembled. Accordingly, it is possible to prevent other semiconductor light emitting elements from being assembled into the assembly groove1111or to prevent a plurality of semiconductor light emitting elements from being assembled into the assembly groove1111.

In addition, a depth of the assembly groove1111may be smaller than a vertical height of the semiconductor light emitting element1150. Therefore, the semiconductor light emitting element1150may have a structure protruding to a portion between the portions of the partition walls1115, and may easily come into contact with a protrusion of the transfer substrate during a transfer process that may occur after the assembly.

In addition, as shown inFIG.11, after the assembly substrate1110is disposed, an assembly apparatus1140containing a magnetic body may move along the assembly substrate1110. The assembly apparatus1140may move in contact with the assembly substrate1110in order to maximize a region of a magnetic field into the fluid1120. For example, the assembly apparatus1140may contain a plurality of magnetic bodies or may contain a magnetic body of a size corresponding to that of the assembly substrate1110. In this case, a moving distance of the assembly apparatus1140may be limited to be in a predetermined range.

The semiconductor light emitting element1150in the chamber1130may move toward the assembly apparatus1140by the magnetic field generated by the assembly apparatus1140.

While moving toward the assembly apparatus1140, the semiconductor light emitting element1150may enter the assembly groove1111and come into contact with the assembly substrate1110, as shown inFIG.12.

In addition, the semiconductor light emitting element1150may include a magnetic layer therein such that the self-assembly process may be performed.

The semiconductor light emitting element1150in contact with the assembly substrate1110may be prevented from deviating by the movement of the assembly device1140because of the electric field generated by the assembly electrodes1112and1113of the assembly substrate1110.

Accordingly, the plurality of semiconductor light emitting elements1150are simultaneously assembled to the assembly substrate1110in the self-assembly method using the electromagnetic field shown inFIGS.11and12.

FIG.13is an embodiment of a case in which a general vertical type semiconductor light emitting element is assembled onto an assembly substrate.

In general, in a case of a horizontal type semiconductor light emitting element, an element is assembled onto a substrate by the self-assembly method described with reference toFIGS.11and12, and then a process of forming a wiring electrode to be connected to each conductivity-type electrode on one surface of the element is performed.

On the other hand, in the case of the vertical type semiconductor light emitting element, the conductivity-type electrodes are respectively formed on both surfaces of the element. Therefore, when the semiconductor light emitting element is assembled onto the substrate, only a conductivity-type electrode on one surface is exposed on the substrate. Therefore, the wiring electrode may be formed in advance on the substrate for the electrical connection between the non-exposed conductivity-type electrode on the opposite surface and the substrate.

InFIG.13, (a) is a plan view showing a partition wall1315, an assembly groove1311defined by the partition wall1315, a wiring electrode1316disposed on a bottom of the assembly groove1311, and a semiconductor light emitting element1350assembled into the assembly groove1311. For smooth assembly, an area of the assembly groove1311is larger than an assembly area of the semiconductor light emitting element1350. Accordingly, the semiconductor light emitting element1350may be randomly positioned within the assembly groove1311. The wiring electrode1316for electrical connection between the semiconductor light emitting element1350and the assembly substrate may exist in a form of one bar as shown in (a) ofFIG.13.

InFIG.13, (b) shows a cross-sectional view of the semiconductor light emitting element1350assembled onto the assembly substrate in (a) ofFIG.13. The cross-sectional view exemplifies a case in which a defect has occurred. When it is normal for the semiconductor light emitting element1350to be horizontally directed on the assembly substrate, the semiconductor light emitting element1350may be assembled in a form inclined to one side as shown in (b) ofFIG.13. Alternatively, during a wiring process for electrical connection between the wiring electrode1316and the semiconductor light emitting element1350, the wiring electrode1316may be melted and thermally flow, so that the position of the element may be changed.

Specifically, as shown in in (b) ofFIG.13, a pair of assembly electrodes1312and1313are located on the substrate1310, and the assembly substrate1310includes a dielectric film1314for surrounding the assembly electrodes1312and1313and the partition wall1315for the assembly groove1311. In addition, the wiring electrode1316electrically connected to the semiconductor light emitting element1350is positioned on the dielectric film1314. The wiring electrode1316may be melted in the wiring process and may be electrically connected to the semiconductor light emitting element1350that comes into contact with the wiring electrode1316. Accordingly, the wiring electrode1316may include a low-melting-point metal layer that is relatively easy to melt. A width of the wiring electrode1316may be smaller than a width of the semiconductor light emitting element1350. This is because, when the width of the wiring electrode1316is greater than the width of the semiconductor light emitting element1350, an electric field generated through the assembly electrodes1312and1313in the self-assembly process may be shielded by the wiring electrode1316. In addition, in the wiring process, the wiring electrode1316may melt and flow, so that an excessive size of the wiring electrode may cause an unintended short-circuit defect in the thermal flow process. Accordingly, as shown in-FIG.13A or13B(a) of (b) ofFIG.13, the wiring electrode1316may be formed in a partial region of the assembly groove. However, in this case, as shown in (b) ofFIG.13, the semiconductor light emitting element1350assembled onto the assembly substrate may be inclined by the protruding wiring electrode1316. Accordingly, a contact area with the wiring electrode1316may decrease, and thus a contact resistance may increase. In addition, assuming that the plurality of semiconductor light emitting elements are assembled onto the substrate, because the semiconductor light emitting elements have different areas of contact with the wiring electrode, actually applied voltages may be different, and thus a difference may occur in light emission uniformity.

In one example, in order to prevent the inclination of the element, it is possible to devise a structure in which the wiring electrode is embedded in the groove by additionally defining a separate groove in the bottom surface of the assembly groove without protruding the wiring electrode from the bottom surface of the assembly groove. However, in this case, it is difficult to secure reliability of whether the semiconductor light emitting element is in proper contact with the wiring electrode. Therefore, based on the structure in which the wiring electrode protrudes from the bottom surface of the assembly groove, a structure of the assembly substrate and the wiring electrode in which the semiconductor light emitting element is horizontally assembled on the wiring electrode and further the change in the position of the horizontally assembled semiconductor light emitting element is also minimized in the wiring process is required.

Accordingly, an assembly substrate having a wiring electrode for solving the above problems and a display device using the same will be described later inFIGS.14to22.

FIG.14is a flowchart schematically illustrating a method for manufacturing a display device using an assembly substrate of the present disclosure.

First, the vertical type semiconductor light emitting element is formed (S1410). The vertical type semiconductor light emitting element may have the conductivity-type electrodes respectively at both ends thereof. Therefore, a conductivity-type electrode at one end may be formed together in the process of forming the semiconductor light emitting structure on the growth substrate, and the remaining conductivity-type electrode may be formed after transferring the semiconductor light emitting element using a separate transfer substrate. The semiconductor light emitting element is self-assembled in the fluid using the magnetic field and the electric field, so that the element may include the magnetic layer.

Thereafter, the assembly substrate having the assembly electrodes, the wiring electrode, and the assembly groove is prepared (S1420). The assembly electrodes generate a dielectrophoretic force in a relationship with the semiconductor light emitting element by the electric field, and the wiring electrode electrically connects the vertical type semiconductor light emitting element to the substrate. In addition, the wiring electrode may be composed of a base electrode and a low-melting-point junction portion positioned on the base electrode. In addition, the assembly groove guides the position where the semiconductor light emitting element is assembled.

Thereafter, the vertical type semiconductor light emitting element is put into the chamber filled with the fluid, and the assembly substrate is placed on the top surface of the chamber (S1430).

Thereafter, as described above, the semiconductor light emitting element is assembled into the assembly groove of the assembly substrate using the magnetic field and the electric field (S1440).

Finally, the assembly substrate is removed from the chamber, and the semiconductor light emitting element is electrically connected to the wiring electrode of the assembly substrate (S1450). Therefore, the conductivity-type electrode at one end of the semiconductor light emitting element and the substrate are electrically connected to each other.

Furthermore, the additional wiring process may be performed for the conductivity-type electrode formed at the other end of the semiconductor light emitting element.

In view of the entire gist of the present specification, at a level that may be understood by those skilled in the art, deleting and changing some operations of the flowchart shown inFIG.14also fall within the scope of the present disclosure.

FIG.15illustrates views of a vertical type semiconductor light emitting element electrically connected to a wiring electrode of an assembly substrate of the present disclosure.

InFIG.15, (a) is a plan view illustrating a partition wall1515, an assembly groove1511defined by the partition wall1515, a low-melting-point junction portion1517disposed on a bottom surface of the assembly groove1511, and a semiconductor light emitting element1550assembled in the assembly groove1511. For smooth assembly, an area of the assembly groove1511is larger than an assembly area of the semiconductor light emitting element1550. Accordingly, the semiconductor light emitting element1550may be randomly positioned within the assembly groove1511. The low-melting-point junction portion1517for electrical connection of the semiconductor light emitting element1550and the assembly substrate may have a form in which a plurality of bars intersect each other as shown in (a) ofFIG.15. The low-melting-point junction portion1517is formed on the base electrode. The wiring electrode of the present disclosure includes the low-melting-point junction portion1517and the base electrode. In addition, the low-melting-point junction portion1517may have a flow blocking angle at an intersection of the plurality of bars. As the flow blocking angle is formed at the intersection, when the low-melting-point junction portion1517is melted in the wiring process, a thermal flow amount of a corresponding region (the intersection) is smaller than those of other regions of the low-melting-point junction portion1517. For example, the thermal flow amount of the intersection region having the flow blocking angle may be smaller than a thermal flow amount of ends of the plurality of bars. Therefore, when the low-melting-point junction portion1517expands or flows by heat, although a movement is relatively easy in a direction of the ends of the plurality of bars, it is difficult to flow to the intersection region with the flow blocking angle. This will be described in detail later with reference toFIG.18.

In one example, (b) ofFIG.15illustrates a cross-sectional view of the semiconductor light emitting element1350assembled onto the assembly substrate in (a) ofFIG.15. As may be seen from the cross-sectional view, the semiconductor light emitting element1350may be horizontally directed on the assembly substrate unlike in in (b) ofFIG.13.

Specifically, as shown in (b) ofFIG.15, a pair of assembly electrodes1512and1513are located on the assembly substrate1510, and the assembly substrate includes a dielectric film1514surrounding the assembly electrodes1512and1513and the partition wall1515for the assembly groove1511. In addition, a wiring electrode1540electrically connected to the semiconductor light emitting element1550is located on the dielectric film1514. The wiring electrode1540may be composed of a base electrode1516and the low-melting-point junction portion1517formed on the base electrode1516. In addition, the low-melting-point junction portion1517may include a metal layer that is melted at a temperature in a range from 100 and 250 degrees. Accordingly, after assembling the semiconductor light emitting element onto the assembly substrate, the low-melting-point junction portion1517may be melted in the wiring process to be electrically connected to the semiconductor light emitting element1550. In addition, in order to apply a certain pressure to the semiconductor light emitting element1550in the wiring process, a height of the semiconductor light emitting element1550may be greater than a height of the partition wall1515.

FIG.16illustrates embodiments of an assembly substrate including a wiring electrode of the present disclosure.

InFIG.16, (a) and (b) are slightly different only in a structure of the low-melting-point junction portion and are the same in the remaining components. In addition, in order to more clearly observe structures and shapes of the assembly electrode and the wiring electrode, the dielectric film and the partition wall positioned between the assembly electrode and the wiring electrode are omitted.

As shown in (a) ofFIG.16, a pair of assembly electrodes1612and1613may be positioned on a substrate1610, and a wiring electrode may be positioned therebetween. The pair of assembly electrodes1612and1613are for applying the electric field, and are able to generate the dielectrophoretic force with the semiconductor light emitting element when applied with the alternating voltage. The assembly electrodes1612and1613may partially protrude to be positioned to overlap an assembly groove1611in which the semiconductor light emitting element is assembled as shown in (a) ofFIG.16. However, the present disclosure is not limited thereto, and it is also possible that the assembly electrodes1612and1613are arranged side by side in a straight line. In one example, the wiring electrode may be positioned between the assembly electrodes1612and1613. A base electrode1616may be directed in the same direction as the direction in which the assembly electrodes1612and1613are directed, and a low-melting-point junction portion1617may be positioned on a bottom surface of the assembly groove16111.

Specifically, the low-melting-point junction portion1617may be positioned on the base electrode1616and formed in a form of a plurality of intersecting bars. For example, the low-melting-point junction portion1617may include a first bar1617-1directed in a first direction and a second bar1617-2directed in a second direction intersecting the first direction. In addition, as shown in (a) ofFIG.16, the first direction may correspond to a long axis direction of the base electrode1616of the wiring electrode, and a length of the first bar1617-1may be larger than a diameter of the assembly groove1611. As the first bar1617-1is formed to be larger than the assembly groove1611, the semiconductor light emitting element that is primarily assembled into the assembly groove1611may be prevented from being inclined in the first direction.

In addition, certain regions of both ends of the second bar1617-2may be positioned to overlap the assembly electrodes1612and1613, respectively. As described above, the assembly electrodes1612and1613may partially overlap the assembly groove1611, so that, when a length of the second bar1617-2is similar to the diameter of the assembly groove1611, the certain regions of the both ends of the second bar1617-2may be positioned to overlap the assembly electrodes1612and1613, respectively. Therefore, the semiconductor light emitting element assembled into the assembly groove1611may be prevented from being inclined in the second direction. In the present disclosure, the semiconductor light emitting element is horizontally assembled onto the assembly substrate while minimizing an area of the low-melting-point junction portion through the intersection of the bars. As described above, when the area of the low-melting-point junction portion is similar to the area of the assembly groove, a degree of melting and deformation of the junction portion becomes great in the subsequent wiring process, which may cause the change in the position of the element or the short-circuit defect. Thus, the area of the low-melting-point junction portion should be considered in terms of efficiency.

In one example, (b) ofFIG.16is a view showing a case in which a low-melting-point junction portion1618on the base electrode1616is formed only in the assembly groove1611. The first bar1617-1of the low-melting-point junction portion1617is formed longer than the assembly groove1611in (a) ofFIG.16, but both a first bar1618-1and a second bar1618-2are formed in the assembly groove1611inFIG.16B(b) ofFIG.16. However, even in this case, the closer the lengths of the first bar1618-1and the second bar1618-2are to the diameter of the assembly groove1611, the more advantageous it is for the horizontal assembly of the semiconductor light emitting element.

However, inFIG.16, the length of the first bar of the low-melting-point junction portion is expressed differently in consideration of a process level. As the assembly groove becomes smaller, the spacing between the assembly electrodes overlapping the assembly groove and the width of the first bar positioned between the assembly electrodes may decrease. When it is possible to form the first bar with a desired width in the assembly groove in consideration of the process level, it may be advantageous for all regions of the low-melting-point junction portion to be located in the assembly groove as shown in (b) ofFIG.16. However, realistically, when it is difficult to fine-tune the width of the low-melting-point junction portion corresponding to the spacing between the assembled electrodes, it is easy in the process to form some bars long and the remaining bars short. In this case, it may be advantageous that, rather than the second bar, the first bar formed in the same direction as the base electrode has the length greater than the diameter of the assembly groove.

In one example, inFIG.16, two bars may be expressed as intersecting, and a plurality of bars other than the two bars may constitute the low-melting-point junction portion. Even in this case, the area of the low-melting-point junction portion compared to the area of the assembly groove should be considered in terms of the efficiency.

FIG.17illustrates views of a general shape change before and after a wiring process of a wiring electrode of an assembly substrate.

InFIG.17, (a) may be a general shape of a low-melting-point junction portion1717formed on the base electrode of the wiring electrode. In addition, a center point F of the low-melting-point junction portion1717may coincide with a center point of an assembly groove1711. As shown in (a) ofFIG.17, when the low-melting-point junction portion1717is formed in a circular shape without a specific directionality, the semiconductor light emitting element to be in contact with the low-melting-point junction portion1717later may be directed horizontally. However, during the wiring process, the low-melting-point junction portion1717may flow in a random direction as shown by an arrow in (a) ofFIG.17.

InFIG.17, (b) is a simple illustration of a shape that a low-melting-point junction portion1718in the assembly groove1711after the wiring process may have. The low-melting-point junction portion1718is melted in the wiring process and is able to expand or flow, so that the low-melting-point junction portion1718may come into contact with one side surface of the assembly groove1711as shown in (B) OFFIG.17. In this case, a position change by ΔF may occur on a center point F′ of the low-melting-point junction portion1718from the center point F of the low-melting-point junction portion1717before the wiring process. Therefore, when the semiconductor light emitting element is assembled on the low-melting-point junction portion, after the wiring process, the structure of the semiconductor light emitting element may change from the existing horizontal structure to an inclined structure due to the position change ΔF.

In the vertical type semiconductor light emitting element, the wiring process for electrically connecting the assembly substrate with the conductivity-type electrode of the semiconductor light emitting element to be in contact with the substrate is essential. For example, an operation of placing the low-melting-point metal layer on the substrate and then melting the low-melting-point metal layer to be electrically connected to the element is performed. Therefore, even the semiconductor light emitting element assembled horizontally onto the substrate may become inclined due to the deformation of the low-melting-point metal layer after the wiring process. In order to prevent this, a structure capable of controlling the position change of the low-melting-point metal layer even when the wiring process is performed is required.

FIG.18illustrates views showing a shape change before and after a wiring process of a low-melting-point junction portion formed on a wiring electrode of an assembly substrate of the present disclosure.

InFIG.18, (a) is a view illustrating a shape in which a low-melting-point junction portion1817having a first bar1817-1and a second bar1817-2intersecting the first bar1817-1is located in an assembly groove1811. The first bar1817-1and the second bar1817-2may intersect each other at a center point G of the assembly groove1811. In addition, an intersection of the first bar1817-1and the second bar1817-2may have a flow blocking angle1817a. The flow blocking angle may be equal to or smaller than 90 degrees. The case in (a) ofFIG.18is a case in which the second bar1817-2vertically intersects the first bar1817-1. In this case, the flow blocking angle1817amay be 90 degrees. In one example, when the semiconductor light emitting element is assembled in the assembly groove1811in the future, the intersection at which the flow blocking angle1817ais formed may overlap one surface of the semiconductor light emitting element. That is, the intersection of the low-melting-point junction portion1817at which the flow blocking angle1817ais formed may be located in a region within the assembly area of the semiconductor light emitting element.

InFIG.18, (b) is a view illustrating a shape of the low-melting-point junction portion1817in (a) ofFIG.18after performing the wiring process. A low-melting-point junction portion1818after the wiring process may expand or flow in the assembly groove1811, so that a shape thereof may be deformed. However, as a flow blocking angle1818ais defined in an intersection region of the plurality of bars, the deformation of the low-melting-point junction portion1818in the region may be minimized. This is because, when the low-melting-point junction portion is melted, a thermal flow amount of the intersection region with the flow blocking angle is smaller than that of an end of the bar of the low-melting-point junction portion. Therefore, as shown in (b) ofFIG.18, even when the wiring process is performed, an amount of deformation of the region with the flow blocking angle1818ais small. In addition, because the low-melting-point junction portion1818has the symmetrical flow blocking angles1818aas indicated by arrows, even after the wiring process, a center of the low-melting-point junction portion1818may be located at the center point G of the assembly groove1811in the same manner. That is, even when the semiconductor light emitting element is positioned on the low-melting-point junction portion1818, the position change before and after the wiring process may be minimized. Therefore, the semiconductor light emitting element horizontally assembled onto the substrate may still be directed horizontally on the substrate even when the wiring process is performed. Therefore, in the present disclosure, the flow blocking angle was formed by intersecting the plurality of bars with each other to minimize the position change of the low-melting-point junction portion in the wiring process. In addition, the flow blocking angles are symmetrical within the low-melting-point junction portion, so that it is possible to more effectively suppress the position change of the low-melting-point junction portion.

FIG.19illustrates embodiments of a low-melting-point junction portion of various shapes.

InFIG.19, (a) is a view illustrating a low-melting-point junction portion1917in which a polygonal structure is coupled to one straight bar shape within an assembly groove1911. As shown in (a) ofFIG.19, flow blocking angles1917aformed through the shape may be symmetrical in the low-melting-point junction portion1917, and may also be smaller than 90 degrees.

In addition, (b) ofFIG.19is a view illustrating a low-melting-point junction portion2017formed by intersecting three straight bars in an assembly groove2011. As shown in (b) ofFIG.19, flow blocking angles2017aformed through the shape may be symmetrical in the low-melting-point junction portion2017and may also be smaller than 90 degrees.

As such, one of the technical features of the present disclosure is that the low-melting-point junction portion having the flow blocking angle is included, but the present disclosure is not specifically limited by the number and the shape of the bars.

FIG.20is a flowchart illustrating a process of manufacturing an assembly substrate of the present disclosure.

First, the assembly electrodes are formed on the substrate (S1421). The assembly electrodes may include a pair of assembly electrodes. The alternating voltage having a constant voltage difference is applied to each electrode in the future to generate the electric field.

Thereafter, the dielectric film surrounding the assembly electrodes is formed (S1422). The dielectric film serves to protect the assembly electrodes.

Thereafter, the wiring electrode is formed on the dielectric film (S1423). As described above, the wiring electrode of the present disclosure may be composed of the base electrode of a basic shape and the low-melting-point junction portion. Accordingly, the base electrode is formed on the dielectric film (S1423a), and the low-melting-point junction portion is formed on the base electrode (S1423b). In one example, the low-melting-point junction portion may be located inside the assembly groove to be defined in the future.

Finally, the partition wall is formed to define the assembly groove (S1424). A partial region of the partition wall may overlap the wiring electrode. For example, the partition wall may be formed on a region of the wiring electrode except for the base electrode and the low-melting-point junction portion located inside the assembly groove.

In view of the entire gist of the present specification, at a level that may be understood by those skilled in the art, deleting and changing some operations of the flowchart shown inFIG.20also fall within the scope of the present disclosure.

FIG.21illustrates cross-sectional views illustrating a manufacturing process according to a flowchart inFIG.20.

As shown in (a) ofFIG.21, a pair of assembly electrodes2112and2113are formed on a substrate2110.

Thereafter, as shown in (b) ofFIG.21, a dielectric film2114is formed to surround the assembly electrodes2112and2113. The dielectric film2114may be formed by spin coating, bar coating, chemical vapor deposition, or the like.

Thereafter, as shown in (c) ofFIG.21, a base electrode2116is formed on the dielectric film2114. The base electrode2116may partially overlap with the assembly electrodes2112and2113.

Thereafter, as shown in (d) ofFIG.21, a low-melting-point junction portion2117is formed on the base electrode2116. The base electrode2116and the low-melting-point junction portion2117serve as the wiring electrode electrically connected to one surface of the semiconductor light emitting element. In addition, the low-melting-point junction portion may be positioned in a form in which a plurality of bars intersect. For example, although not clearly distinguished in the cross-sectional view of (d) ofFIG.21, the low-melting-point junction portion2117may be composed of a first bar2117-1directed in the first direction and a second bar2117-2directed in the second direction. In addition, a flow blocking angle may be formed at an intersection of the bars as described above.

Finally, as shown in (e) ofFIG.21, a partition wall2115defining an assembly groove2111in which the semiconductor light emitting element is assembled may be formed on the dielectric film2114.

FIG.22illustrates views illustrating a process of performing a wiring process for electrically connecting a semiconductor light emitting element to an assembly substrate.

InFIG.22, (a) illustrates a shape in which a semiconductor light emitting element2250is assembled into an assembly groove2211of an assembly substrate. In the assembly substrate, the assembly groove2211is defined by a partition wall2215formed on the substrate2210, and a base electrode2216and a low-melting-point junction portion2217are located on a bottom surface of the assembly groove2211. In addition, the semiconductor light emitting element2250is in contact with a top surface of the low-melting-point junction portion2217.

InFIG.22, (b) is a view illustrating a wiring process of the semiconductor light emitting element2250in (a) ofFIG.22. The semiconductor light emitting element2250, which is the vertical type semiconductor light emitting element, may have the conductivity-type electrodes respectively positioned on both surfaces thereof. Through the wiring process, the conductivity-type electrode formed on one surface of the semiconductor light emitting element2250and the low-melting-point junction portion2217positioned on the substrate2210may be electrically connected to each other. The wiring process may include an operation of applying a pressure from above the semiconductor light emitting element2250and an operation of heating and melting the low-melting-point junction portion2217.

As described above, the low-melting-point junction portion2217includes the metal layer with the low melting point, which is melted in the temperature range from about 100 degrees to 250 degrees. Thus, the wiring process may be performed in, for example, a chamber having a temperature of 200 degrees.

FIG.23is a cross-sectional view of a semiconductor light emitting element inFIG.22after performing an additional wiring process.

Specifically, in the case of the semiconductor light emitting element2250inFIG.22, one surface of the element in contact with the low-melting-point junction portion2217is electrically connected. In one example, in the case inFIG.23, an opposite surface of the semiconductor light emitting element2250, which is not in contact with the low-melting-point junction portion2217, is electrically connected to another wiring electrode2230. To this end, an interlayer insulating film2220for covering a top of the semiconductor light emitting element2250assembled onto the assembly substrate may be formed. Thereafter, the wiring electrode2230electrically connected to the semiconductor light emitting element2250may be formed through an etching process and a deposition process. In the assembly substrate, assembling electrodes2212and2213for generating the electric field, a dielectric film2214for protecting the assembly electrodes2212and2213, and the partition wall2215for defining the assembly groove is located on the substrate2210. In addition, the base electrode2216and the low-melting-point junction portion2217are located inside the assembly groove.

The above description is merely illustrative of the technical idea of the present disclosure. Those of ordinary skill in the art to which the present disclosure pertains will be able to make various modifications and variations without departing from the essential characteristics of the present disclosure.

Therefore, embodiments disclosed in the present disclosure are not intended to limit the technical idea of the present disclosure, but to describe, and the scope of the technical idea of the present disclosure is not limited by such embodiments.

The scope of protection of the present disclosure should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.