Patent Description:
Recently, liquid crystal displays (LCD), organic light-emitting diode (OLED) displays, and micro LED displays are competing to implement a large-area display in the field of display technology.

Meanwhile, if a semiconductor light emitting diode (micro LED) having a crosssectional area or diameter of <NUM> or less is used in the display, the display does not absorb light using a polarizing plate or the like, and thus, very high efficiency can be provided. However, since a large display requires millions of semiconductor light emitting diodes, it is difficult to transfer the elements, compared to other technologies.

Examples of a technology that is currently being developed as a transfer process include pick & place, laser lift-off (LLO), or self-assembly. Among them, the self-assembly is a method in which a semiconductor light emitting diode finds its own position in a fluid, and is the most advantageous method for realizing a large-screen display device.

The self-assembly includes a method of directly assembling a semiconductor light emitting diode on a final substrate to be used in a product, and a method of assembling a semiconductor light emitting diode on an assembly substrate and then transferring the semiconductor light emitting diode to a final substrate through an additional transfer process. The method of directly assembling on the final substrate is efficient in terms of process. The use of the assembly substrate has an advantage in that a structure for self-assembly can be added without limitation. Therefore, the two methods are selectively used.

Further related technologies are disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

One object of the present invention is to provide a display device having a structure (position selectivity) capable of self-assembling semiconductor light emitting diodes emitting different colors to a substrate at the same time. To this end, the semiconductor light emitting diode and the substrate each include a recessed portion and a solder portion corresponding thereto.

Another object of the present invention is to provide a display device having a structure in which a semiconductor light emitting diode can be electrically connected to a substrate while being assembled to the substrate. To this end, a recessed portion and a solder portion may include an ohmic electrode and a wiring electrode for electrical connection.

Another object of the present invention is to provide a display device having a structure capable of preventing separation of a semiconductor light emitting diode assembled on a substrate. To this end, a solder portion of the substrate may include a magnetic layer.

The invention provides a display device according to the independent claim.

According to an embodiment of the present invention, the display device can perform self-assembly by simultaneously inputting semiconductor light emitting diodes emitting different colors into a fluid chamber, thereby shortening the assembly time.

In addition, the semiconductor light emitting diode seated in the cell can be connected to the wiring electrode through bonding with the solder portion, and furthermore, there is an effect that it can be more stably fixed to the substrate by the magnetic force acting between the semiconductor light emitting diode and the solder portion.

Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings, and the same or similar elements are designated with the same numeral references regardless of the numerals in the drawings and their redundant description will be omitted. The suffixes "module" and "unit or portion" for components used in the following description are merely provided only for facilitation of preparing this specification, and thus they are not granted a specific meaning or function. In addition, when it is determined that the detailed description of the related known technology may obscure the gist of embodiments disclosed herein in describing the embodiments, a detailed description thereof will be omitted. Further, 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 scope disclosed in the present specification by the accompanying drawings. It is also understood that when an element, such as a layer, region, or substrate, it is referred to as being "on" another element, it may be directly present on the other element or intervening elements in between.

The display device described herein may include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDA), portable multimedia players (PMP), navigation systems, slate PCs, a Tablet PC, Ultra Books, digital TVs, digital signages, head mounted displays (HMDs), desktop computers, and the like. However, it will be readily apparent to those skilled in the art that the configuration according to the embodiments described in the present specification may be applied to a device capable of display having even a new product form to be developed later.

<FIG> is a conceptual diagram showing an embodiment of a display device using a semiconductor light emitting diode of the present invention, <FIG> is a partially enlarged view of portion A of the display device of <FIG>, <FIG> is an enlarged view of the semiconductor light emitting diode of <FIG>, and <FIG> is an enlarged view showing another embodiment of the semiconductor light emitting diode of <FIG>.

As shown, information processed by a controller of a display device <NUM> may be output from a display module <NUM>. A closed-loop-type case <NUM> surrounding edges of the display module may form a bezel of the display device.

The display module <NUM> may include a panel <NUM> on which images are displayed, and the panel <NUM> may include a micro-sized semiconductor light emitting diode <NUM> and a wiring board <NUM> on which the semiconductor light emitting diode <NUM> is mounted.

Wirings may be formed on the wiring board <NUM> to be connected to an n-type electrode <NUM> and a p-type electrode <NUM> of the semiconductor light emitting diode <NUM>. Through this, the semiconductor light emitting diode <NUM> may be provided on the wiring board <NUM> as an individual pixel that emits light itself.

An image displayed on the panel <NUM> is visual information, and is implemented by independently controlling light emission of sub-pixels arranged in a matrix form through the wirings.

In the present invention, a micro LED (Light Emitting Diode) is exemplified as a type of the semiconductor light emitting diode <NUM> that converts current into light. The micro LED may be a light emitting diode formed in a small size of <NUM> micro or less. In the semiconductor light emitting diode <NUM>, blue, red, and green colors are provided in light emitting regions, respectively, and a unit pixel may be realized by a combination thereof. That is, the unit pixel may mean a minimum unit for realizing one color, and at least three micro LEDs may be provided in the unit pixel.

More specifically, referring to <FIG>, the semiconductor light emitting diode <NUM> may have a vertical structure.

For example, the semiconductor light emitting diode <NUM> is mainly made of gallium nitride (GaN), and indium (In) and/or aluminum (Al) are added together to implement a high output light emitting diode that emits various lights including blue.

The vertical semiconductor light emitting diode may include a p-type electrode <NUM>, a p-type semiconductor layer <NUM> formed on the p-type electrode <NUM>, an active layer <NUM> formed on the p-type semiconductor layer <NUM>, an n-type semiconductor layer <NUM> formed on the active layer <NUM>, and an n-type electrode <NUM> formed on the n-type semiconductor layer <NUM>. In this case, the p-type electrode <NUM> positioned in a lower portion may be electrically connected to the p-electrode of the wiring board, and the n-type electrode <NUM> positioned in an upper portion may be electrically connected to the n-electrode at the upper side of the semiconductor light emitting diode. The vertical semiconductor light emitting diode <NUM> has a great advantage in that it is possible to reduce the chip size because electrodes are arranged up and down.

As another example, referring to <FIG>, the semiconductor light emitting diode may be a flip chip type light emitting diode.

For this example, the semiconductor light emitting diode <NUM> may include a p-type electrode <NUM>, a p-type semiconductor layer <NUM> on which the p-type electrode <NUM> is formed, an active layer <NUM> formed on the p-type semiconductor layer <NUM>, an n-type semiconductor layer <NUM> formed on the active layer <NUM>, and an n-type electrode <NUM> spaced apart from the p-type electrode <NUM> in the horizontal direction on the n-type semiconductor layer <NUM>. In this case, both the p-type electrode <NUM> and the n-type electrode <NUM> may be electrically connected to the p-electrode and n-electrode of the wiring board under the semiconductor light emitting diode.

The vertical semiconductor light emitting diode and the horizontal semiconductor light emitting diode may be a green semiconductor light emitting diode, a blue semiconductor light emitting diode, or a red semiconductor light emitting diode, respectively. In the case of the green semiconductor light emitting diode and the blue semiconductor light emitting diode, gallium nitride (GaN) is mainly used, and indium (In) and/or aluminum (Al) are added together to implement a high output light emitting diode that emits green or blue light. For this example, the semiconductor light emitting diode may be a gallium nitride thin film formed in various layers such as n-Gan, p-Gan, AlGaN, InGan, etc. Specifically, the p-type semiconductor layer may be P-type GaN, and the n-type semiconductor layer may be N-type GaN. However, in the case of the red semiconductor light emitting diode, the p-type semiconductor layer may be P-type GaAs, and the n-type semiconductor layer may be N-type GaAs.

In addition, the p-type semiconductor layer may be P-type GaN doped with Mg on the p-electrode side, and the n-type semiconductor layer may be N-type GaN doped with Si on the n-electrode side. In this case, the above-described semiconductor light emitting diodes may be semiconductor light emitting diodes having no active layer.

Meanwhile, referring to <FIG>, since the light emitting diodes are very small, unit pixels that emit light themselves may be arranged in a high definition in the display panel, thereby realizing a high-definition display device.

In the display device using the semiconductor light emitting diode of the present invention described above, the semiconductor light emitting diode grown on a wafer and formed through mesa and isolation is used as an individual pixel. In this case, the micro-sized semiconductor light emitting diode <NUM> needs to be transferred to the wafer at a predetermined position on a substrate of the display panel. There is a pick and place technique as such a transfer technique, but the success rate is low and a lot of time is required. As another example, there is a technique of transferring several devices at a time using a stamp or a roll, but it is not suitable for a large screen display due to a limitation in yield. The present invention proposes a new manufacturing method and manufacturing apparatus for a display device that can solve these problems.

To this end, a new method of manufacturing a display device will be described below. <FIG> are conceptual views for describing a new process of manufacturing the semiconductor light emitting diode.

In the present specification, a display device using a passive matrix (PM) type semiconductor light emitting diode is taken as an example. However, the examples described below are also applicable to an active matrix (AM) type semiconductor light emitting diode. In addition, although a method of self-assembling a horizontal semiconductor light emitting diode is described as an example, it is also applicable to a method of self-assembling a vertical semiconductor light emitting diode.

First, according to the manufacturing method, a first conductivity type semiconductor layer <NUM>, an active layer <NUM>, and a second conductivity type semiconductor layer <NUM> are individually grown on a growth substrate <NUM> (<FIG>).

After the first conductivity type semiconductor layer <NUM> is grown, the active layer <NUM> is grown on the first conductivity type semiconductor layer <NUM>, and then the second conductivity type semiconductor layer <NUM> is grown on the active layer <NUM>. In this way, when the first conductivity type semiconductor layer <NUM>, the active layer <NUM>, and the second conductivity type semiconductor layer <NUM> are sequentially grown, as shown in <FIG>, the first conductivity type semiconductor layer <NUM>, the active layer <NUM> and the second conductive semiconductor layer <NUM> form a stacked structure.

In this case, the first conductivity type semiconductor layer <NUM> may be a p-type semiconductor layer, and the second conductivity type semiconductor layer <NUM> may be an n-type semiconductor layer. However, the present disclosure is not necessarily limited thereto, and the first conductivity type may be n-type and the second conductivity type may be p-type.

In addition, although the present embodiment exemplifies the case in which the active layer is present, a structure in which the active layer is not present is also possible in some cases as described above. As an example, the p-type semiconductor layer may be P-type GaN doped with Mg, and the n-type semiconductor layer may be N-type GaN doped with Si on the n-electrode side.

The growth substrate <NUM> (wafer) may be formed of a material having a light-transmitting property, for example, any one of sapphire (Al2O3), GaN, ZnO, and AlO, but is not limited thereto. In addition, the growth substrate <NUM> may be formed of a material suitable for semiconductor material growth, a carrier wafer. The growth substrate <NUM> may be formed of a material having excellent thermal conductivity, and may include a conductive board or an insulating board, for example, a SiC board having higher thermal conductivity than a sapphire (Al2O3) board, or use at least one of Si, GaAs, GaP, InP, and Ga2O3.

Next, at least a portion of the first conductivity type semiconductor layer <NUM>, the active layer <NUM>, and the second conductivity type semiconductor layer <NUM> are removed to form a plurality of semiconductor light emitting diodes (<FIG>).

More specifically, isolation is performed such that the plurality of light emitting diodes form a light emitting diode array. That is, the first conductivity type semiconductor layer <NUM>, the active layer <NUM>, and the second conductivity type semiconductor layer <NUM> are vertically etched to form a plurality of semiconductor light emitting diodes.

In the case of forming a horizontal type semiconductor light emitting diode, a mesa process in which the active layer <NUM> and the second conductivity type semiconductor layer <NUM> are partially removed in the vertical direction and the first conductivity type semiconductor layer <NUM> is exposed to the outside and thereafter, isolation in which the first conductivity type semiconductor layer is etched to form a plurality of semiconductor light emitting diode arrays may be performed.

Next, second conductivity type electrodes <NUM> (or p-type electrodes) are formed on one surface of the second conductivity type semiconductor layer <NUM> (<FIG>). The second conductivity type electrode <NUM> may be formed by a deposition method such as sputtering, but the present invention is not limited thereto. However, when the first conductive semiconductor layer and the second conductive semiconductor layer are an n-type semiconductor layer and a p-type semiconductor layer, respectively, the second conductivity type electrode <NUM> may be an n-type electrode.

Then, the growth substrate <NUM> is removed to provide a plurality of semiconductor light emitting diodes. For example, the growth substrate <NUM> may be removed using a laser lift-off (LLO) method or a chemical lift-off (CLO) method (<FIG>).

Thereafter, the semiconductor light emitting diodes <NUM> are seated on a board in a chamber filled with a fluid (<FIG>).

For example, the semiconductor light emitting diodes <NUM> and the board are put in the chamber filled with a fluid, and the semiconductor light emitting diodes are self-assembled onto the board <NUM> using flow, gravity, surface tension, and the like. In this case, the board may be an assembled board <NUM>.

As another example, it is also possible to put the wiring board in a fluid chamber instead of the assembly board <NUM> so that the semiconductor light emitting diodes <NUM> are directly seated on the wiring board. In this case, the board may be a wiring board. However, for convenience of description, in the present invention, the board is provided as, for example, the assembly board <NUM> on which the semiconductor light emitting diodes <NUM> are seated.

Cells (not shown) in which the semiconductor light emitting diodes <NUM> are inserted may be provided in the assembly board <NUM> to facilitate mounting of the semiconductor light emitting diodes <NUM> on the assembly board <NUM>. Specifically, cells in which the semiconductor light emitting diodes <NUM> are seated are formed in the assembly board <NUM> at positions where the semiconductor light emitting diodes <NUM> are to be aligned with wiring electrodes. The semiconductor light emitting diodes <NUM> are assembled to the cells while moving in the fluid.

After a plurality of semiconductor light emitting diodes are arrayed on the assembly board <NUM>, the semiconductor light emitting diodes of the assembly board <NUM> are transferred to a wiring board, enabling large-area transfer. Accordingly, the assembly board <NUM> may be referred to as a temporary board.

On the other hand, in order to apply the self-assembly method described above to the manufacture of a large-screen display, it is necessary to increase transfer yield.

The present disclosure proposes a method and apparatus for minimizing the influence of gravity or frictional force and preventing non-specific binding in order to increase the transfer yield.

In this case, in the display device according to the present disclosure, a magnetic material is disposed on the semiconductor light emitting diode to move the semiconductor light emitting diode using magnetic force, and the semiconductor light emitting diode is seated at a predetermined position by using an electric field during movement. Hereinafter, the transfer method and apparatus will be described in more detail with the accompanying drawings.

<FIG> is a conceptual diagram showing an example of a self-assembly apparatus of a semiconductor light emitting diode according to the present invention, and <FIG> is a block diagram of the self-assembly apparatus of <FIG>. <FIG> are conceptual views showing a process of self-assembling a semiconductor light emitting diode using the self-assembly apparatus of <FIG>, and <FIG> is a conceptual diagram for describing the semiconductor light emitting diode of <FIG>.

Referring to <FIG> and <FIG>, a self-assembly apparatus <NUM> of the present invention may include a fluid chamber <NUM>, a magnet <NUM> and a position control unit <NUM>.

The fluid chamber <NUM> has a space for accommodating a plurality of semiconductor light emitting diodes. The space may be filled with a fluid, and the fluid may include water or the like as an assembly solution. Accordingly, the fluid chamber <NUM> may be a water tank and may be configured in an open type. However, the present disclosure is not limited thereto, and the fluid chamber <NUM> may be of a closed type in which the space is a closed space.

The board <NUM> may be disposed in the fluid chamber <NUM> such that an assembly surface on which the semiconductor light emitting diodes <NUM> are assembled faces downward. For example, the board <NUM> may be transferred to an assembly position by a transfer device, and the transfer device may include a stage <NUM> on which the board is mounted. The position of the stage <NUM> is controlled by the control unit, and through this, the board <NUM> may be transferred to the assembly position.

In this case, in the assembly position, the assembly surface of the board <NUM> faces the bottom of the fluid chamber <NUM>. As shown, the assembly surface of the board <NUM> is disposed to be immersed in the fluid in the fluid chamber <NUM>. Accordingly, the semiconductor light emitting diode <NUM> moves to the assembly surface in the fluid.

The board <NUM> is an assembly board in which an electric field is able to be formed, and may include a base portion 161a, a dielectric layer 161b, and a plurality of electrodes 161c.

The base portion 161a may be formed of an insulating material, and the plurality of electrodes 161c may be a thin or thick bi-planar electrode patterned on one surface of the base portion 161a. The electrode 161c may be formed of, for example, a stack of Ti/Cu/Ti, Ag paste, and ITO.

The dielectric layer 161b may be formed of an inorganic material such as SiO2, SiNx, SiON, Al2O3, TiO2, HfO2, or the like. Alternatively, the dielectric layer 161b may be comprised of a single layer or a multi-layer as an organic insulator. The dielectric layer 161b may have a thickness of several tens of nm to several µm.

Furthermore, the board <NUM> according to the present invention includes a plurality of cells 161d separated by barrier ribs. The cells 161d are sequentially arranged in one direction and may be made of a polymer material. Also, the barrier ribs 161e defining the cells 161d are shared with the neighboring cells 161d. The barrier ribs 161e may protrude from the base portion 161a, and the cells 161d may be sequentially arranged along one direction by the barrier ribs 161e. More specifically, the cells 161d are sequentially arranged in the column and row directions, respectively, and may have a matrix structure.

As shown, the cell 161d may have a groove for accommodating the semiconductor light emitting diode <NUM> and the groove may be a space defined by the barrier ribs 161e. The shape of the groove may be the same as or similar to that of the semiconductor light emitting diode. For example, when the semiconductor light emitting diode has a rectangular shape, the groove may have a rectangular shape. Also, although not shown, when the semiconductor light emitting diode has a circular shape, the groove formed in the cells may have a circular shape. Furthermore, each of the cells is configured to accommodate a single semiconductor light emitting diode. That is, one semiconductor light emitting diode is accommodated in one cell.

Meanwhile, the plurality of electrodes 161c may include a plurality of electrode lines disposed at the bottom of each of the cells 161d, and the plurality of electrode lines may extend to adjacent cells.

The plurality of electrodes 161c are disposed below the cells 161d, and different polarities are applied to the electrodes 161c to generate an electric field in the cells 161d. To form the electric field, the dielectric layer may form the bottom of the cells 161d while the dielectric layer is covering the plurality of electrodes 161c. In this structure, when different polarities are applied to the pair of electrodes 161c under the cells 161d, an electric field is formed, and the semiconductor light emitting diodes may be inserted into the cells 161d due to the electric field.

In the assembly position, the electrodes of the board <NUM> are electrically connected to a power supply device <NUM>. The power supply device <NUM> may apply power to the plurality of electrodes to generate the electric field.

As shown, the self-assembly apparatus may include a magnet <NUM> for applying a magnetic force to the semiconductor light emitting diodes. The magnet <NUM> is spaced apart from the fluid chamber <NUM> to apply a magnetic force to the semiconductor light emitting diodes <NUM>. The magnet <NUM> may be disposed to face the opposite surface of the assembly surface of the board <NUM>, and the position of the magnet is controlled by the position control unit <NUM> connected to the magnet <NUM>.

The semiconductor light emitting diode <NUM> may include a magnetic material to move in the fluid due to the magnetic field of the magnet <NUM>.

Referring to <FIG>, a semiconductor light emitting diode including a magnetic material may include a first conductivity type electrode <NUM>, a second conductivity type electrode <NUM>, a first conductivity type semiconductor layer <NUM> on which the first conductivity type electrode <NUM> is disposed, a second conductivity type semiconductor layer <NUM> on which the second conductivity type electrode <NUM> is disposed, the second conductivity type semiconductor layer <NUM> overlapping the first conductivity type semiconductor layer <NUM> and an active layer <NUM> disposed between the first and second conductivity type semiconductor layers <NUM> and <NUM>.

Here, the first conductivity type may be p-type, the second conductivity type may be n-type, and vice versa. In addition, as described above, the semiconductor light emitting diode having no active layer may be used.

Meanwhile, in the present invention, the first conductivity type electrode <NUM> may be generated after the semiconductor light emitting diode is assembled to the wiring board through self-assembly of the semiconductor light emitting diode. Also, in the present invention, the second conductivity type electrode <NUM> may include the magnetic material. The magnetic material may mean a magnetic metal. The magnetic material may be Ni, SmCo, or the like, and as another example, may include a material corresponding to at least one of Gd-based, La-based, and Mn-based materials.

The magnetic material may be provided in the second conductivity type electrode <NUM> in the form of particles. Alternatively, the conductivity type electrode including a magnetic material may have one layer formed of a magnetic material. For this example, as shown in <FIG>, the second conductivity type electrode <NUM> of the semiconductor light emitting diode <NUM> may include a first layer 1056a and a second layer 1056b. Here, the first layer 1056a may include a magnetic material, and the second layer 1056b may include a metal material rather than a magnetic material.

As shown, in this example, the first layer 1056a including a magnetic material may be disposed to contact the second conductivity type semiconductor layer <NUM>. In this case, the first layer 1056a is disposed between the second layer 1056b and the second conductivity type semiconductor layer <NUM>. The second layer 1056b may be a contact metal connected to the second electrode of the wiring board. However, the present disclosure is not necessarily limited thereto, and the magnetic material may be disposed on one surface of the first conductivity type semiconductor layer.

Referring back to <FIG> and <FIG>, more specifically, the self-assembly apparatus is provided with a magnet handler that is movable automatically or manually in the x, y, and z axes on the upper portion of the fluid chamber, or a motor capable of rotating the magnet <NUM>. The magnet handler and the motor may constitute the position control unit <NUM>. Through this, the magnet <NUM> may rotate in a horizontal direction with the board <NUM>, clockwise or counterclockwise direction.

Meanwhile, a bottom plate <NUM> having a light-transmitting property may be formed in the fluid chamber <NUM>, and the semiconductor light emitting diodes may be disposed between the bottom plate <NUM> and the board <NUM>. An image sensor <NUM> may be disposed to face the bottom plate <NUM> to monitor the inside of the fluid chamber <NUM> through the bottom plate <NUM>. The image sensor <NUM> is controlled by the control unit <NUM> and may include an inverted type lens, a CCD and the like to observe the assembly surface of the board <NUM>.

The self-assembly apparatus described above is configured to use a combination of a magnetic field and an electric field, and when using this, the semiconductor light emitting diodes may be seated at predetermined positions on the board due to an electric field while moving by a change in the position of the magnet.

Hereinafter, an assembly process using the self-assembly apparatus described above will be described in more detail.

First, a plurality of semiconductor light emitting diodes <NUM> including a magnetic material are formed through the process described with reference to <FIG>. In this case, in the process of forming the second conductivity type electrode of <FIG>, a magnetic material may be deposited on the semiconductor light emitting diode.

Next, the board <NUM> is transferred to an assembly position, and the semiconductor light emitting diodes <NUM> are put into the fluid chamber <NUM> (<FIG>).

As described above, the assembly position of the board <NUM> may be a position in which the board <NUM> is to be disposed in the fluid chamber <NUM> such that the assembly surface of the board <NUM> on which the semiconductor light emitting diodes <NUM> are to be assembled faces downward.

In this case, some of the semiconductor light emitting diodes <NUM> may sink to the bottom of the fluid chamber <NUM> and some may float in the fluid. The bottom plate <NUM> having a light-transmitting property is provided in the fluid chamber <NUM>, and some of the semiconductor light emitting diodes <NUM> may sink to the bottom plate <NUM>.

Next, a magnetic force is applied to the semiconductor light emitting diodes <NUM> such that the semiconductor light emitting diodes <NUM> vertically float in the fluid chamber <NUM> (<FIG>).

When the magnet <NUM> of the self-assembly apparatus moves from its original position to the opposite surface of the assembly surface of the board <NUM>, the semiconductor light emitting diodes <NUM> may float toward the board <NUM> in the fluid. The original position may be a position deviated from the fluid chamber <NUM>. As another example, the magnet <NUM> may be made of an electromagnet. In this case, electricity is supplied to the electromagnet to generate an initial magnetic force.

Meanwhile, in this example, when the magnitude of the magnetic force is adjusted, the separation distance between the assembly surface of the board <NUM> and the semiconductor light emitting diodes <NUM> may be controlled. For example, the separation distance is controlled using the weight, buoyancy, and magnetic force of the semiconductor light emitting diodes <NUM>. The separation distance may be several millimeters to several tens of micrometers from the outermost edge of the board.

Next, a magnetic force is applied to the semiconductor light emitting diodes <NUM> such that the semiconductor light emitting diodes <NUM> move in one direction in the fluid chamber <NUM>. For example, it is possible to move the magnet <NUM> in a direction horizontal to the board, clockwise or counterclockwise (<FIG>). In this case, the semiconductor light emitting diodes <NUM> move in a direction parallel to the board <NUM> from positions spaced apart from the board <NUM> due to the magnetic force.

Next, an electric field is applied to guide the semiconductor light emitting diodes <NUM> to preset positions such that the semiconductor light emitting diodes <NUM> are seated in the preset positions of the board <NUM> while the semiconductor light emitting diodes <NUM> are moving (<FIG>). For example, while the semiconductor light emitting diodes <NUM> are moving in a direction horizontal to the board <NUM>, the semiconductor light emitting diodes <NUM> may move in a direction perpendicular to the board <NUM> due to the electric field, and be then seated in the preset positions of the board <NUM>.

More specifically, an electric field is generated by supplying power to the bi-planar electrode of the board <NUM> to enable assembly to be made only at preset positions. That is, the semiconductor light emitting diodes <NUM> are self-assembled at assembly positions of the board <NUM> by using the selectively generated electric field. To this end, cells in which the semiconductor light emitting diodes <NUM> are inserted may be provided in the board <NUM>.

Thereafter, a process of unloading the board <NUM> is performed, and the assembly process is finished. When the board <NUM> is an assembly board, a postprocess for realizing a display device by transferring the semiconductor light emitting diodes arranged as described above to a wiring board may be performed.

Meanwhile, after guiding the semiconductor light emitting diodes <NUM> to the preset positions, the magnet <NUM> may be moved in a direction away from the board <NUM> such that the semiconductor light emitting diodes <NUM> remaining in the fluid chamber <NUM> fall to the bottom of the fluid chamber <NUM> (<FIG>). As another example, when power supply is stopped in a case where the magnet <NUM> is an electromagnet, the semiconductor light emitting diodes <NUM> remaining in the fluid chamber <NUM> may fall to the bottom of the fluid chamber <NUM>.

Thereafter, when the semiconductor light emitting diodes <NUM> at the bottom of the fluid chamber <NUM> are recovered, the recovered semiconductor light emitting diodes <NUM> may be reused.

The self-assembly apparatus and method described above may use a magnetic field to enable distant parts to congregate near a predetermined assembly site and apply a separate electric field to the assembly site such that the parts are selectively assembled only to the assembly site in order to increase the assembly yield in fluidic assembly. In this case, the assembly board is placed on the upper portion of the water tank and the assembly surface is directed downward to minimize the effect of gravity due to the weight of the parts and prevent non-specific binding to eliminate defects. That is, to increase the transfer yield, the assembly board is placed on the upper portion to minimize the effect of gravity or frictional force, and to prevent non-specific binding.

As described above, according to the present invention having the above configuration, in a display device in which individual pixels are formed of semiconductor light emitting diodes, a large number of semiconductor light emitting diodes may be assembled at once.

As described above, according to the present invention, it is possible to pixelate a large amount of semiconductor light emitting diodes on a small-sized wafer and then transfer the semiconductor light emitting diodes to a large-area substrate. Through this, it is possible to manufacture a large-area display device at a low cost.

Hereinafter, a display device using a semiconductor light emitting diode having a novel structure according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In order to clarify the features of the present invention, some components not related to the features of the present invention may not be included in the drawings.

The display apparatus <NUM> described in this specification may be implemented in a passive matrix method (hereinafter, PM method) or an active matrix method (hereinafter referred to as AM method).

<FIG> is a conceptual diagram showing a display device according to an embodiment of the present invention.

The display device <NUM> according to the present invention includes assembled electrodes <NUM>, a dielectric layer <NUM>, a semiconductor light emitting diode <NUM> assembled in a cell <NUM>, and a partition wall portion <NUM>, a solder portion <NUM>, a first wiring electrode <NUM>, and the like, on a base portion <NUM>.

As an embodiment, the base portion <NUM> may be a rigid substrate such as glass, sapphire, silicon, or the like. In another embodiment, the base portion <NUM> may be a flexible substrate including a polymer material.

As the polymer material, for example, a material including flexible and insulating PI (polyimide), PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or the like may be used.

Assembled electrodes <NUM> extending in one direction may be formed on the base portion <NUM>. The assembled electrodes <NUM> may be formed to a thickness of several hundred nm.

The assembled electrodes <NUM> may be configured to form an electric field during self-assembly. Specifically, a voltage signal may be applied to the assembled electrodes <NUM> and transmitted in the extension direction.

The assembled electrodes <NUM> may be formed of a non-resistive metal corresponding to any one of Al, Mo, Cu, Ag, and Ti, or an alloy selected from these.

However, the metal forming the assembled electrodes <NUM> is not limited to those described above.

A dielectric layer <NUM> may be formed on the base portion <NUM> to cover the assembled electrodes <NUM>. For example, the dielectric layer <NUM> may be made of an inorganic insulating material such as SiO<NUM>, SiNx, SiON, Al<NUM>O<NUM>, TiO<NUM>, HfO<NUM>, or the like.

In addition, the dielectric layer <NUM> may be formed as a single layer or as a multi-layer. For example, when the wiring electrode is disposed under the semiconductor light emitting diode <NUM>, the dielectric layer <NUM> may be formed as a multi-layer including a first dielectric layer covering the wiring electrode and the second dielectric layer covering the assembled electrode <NUM> to electrically insulate the assembled electrode <NUM> and the wiring electrode.

A partition wall portion <NUM> may be stacked on the dielectric layer <NUM> while forming a plurality of cells <NUM>. The plurality of cells <NUM> may be formed in a matrix arrangement, and the semiconductor light emitting diodes <NUM> may be seated inside the cells <NUM> through self-assembly.

The semiconductor light emitting diodes <NUM> transferred to the substrate by the self-assembly method may be formed in a symmetrical structure, for example, may be formed in a circular shape.

The partition wall portion <NUM> may be formed of an organic insulating material (for example, PAC) made of a polymer material or an inorganic insulating material such as SiO<NUM> or SiNx.

In addition, although not shown in the drawings, a planarization layer (not shown) for electrically insulating the semiconductor light emitting diode <NUM> from the wiring electrode while planarizing the upper surface of the semiconductor light emitting diode <NUM> seated in the cell <NUM> may be included.

According to the present invention, the display device <NUM> includes semiconductor light emitting diodes <NUM> that emit light of different colors. For example, the display device <NUM> may include semiconductor light emitting diodes <NUM> emitting blue, green, and red light.

According to the present invention, the display device <NUM> is characterized in that it has a structure capable of simultaneously self-assembling the semiconductor light emitting diodes <NUM> that emit light of different colors to a substrate.

To this end, the semiconductor light emitting diodes <NUM> that emit light of different colors includes recessed portions 2050R having different shapes on one surface. In addition, the substrate includes a solder portion <NUM> protruding from the bottom surface of the cell <NUM> to correspond to the recessed portion 2050R of the semiconductor light emitting diode <NUM> which is seated (or which will be seated) on the cell <NUM>.

First, the semiconductor light emitting diode <NUM> according to the embodiment of the present invention may be a vertical semiconductor light emitting diode <NUM>.

The vertical semiconductor light emitting diode <NUM> can form the active layer <NUM> wider than that of the horizontal semiconductor light emitting diode, and thus has an excellent advantage in terms of luminous efficiency. In addition, it is advantageous for miniaturization of the semiconductor light emitting diode <NUM>.

<FIG> is a conceptual diagram showing a semiconductor light emitting diode according to an embodiment of the present invention.

According to an embodiment of the present invention, the semiconductor light emitting diode <NUM> may include a first conductivity type electrode <NUM>, a first conductivity type semiconductor layer <NUM> formed on the first conductivity type electrode <NUM>, an active layer <NUM> formed on the first conductivity type semiconductor layer <NUM>, a second conductivity type semiconductor layer <NUM> formed on the active layer <NUM>, a second conductivity type electrode <NUM> formed on the second conductivity type semiconductor layer <NUM>, and an undoped semiconductor layer <NUM>.

In the present embodiment, the first conductivity type electrode <NUM> may be formed as a transparent electrode as a side from which light generated in the active layer <NUM> is emitted. For example, the first conductivity type electrode <NUM> may be formed of indium tin oxide (ITO), Al-doped zinc oxide (AZO), F-doped tin oxide (FTO), or the like.

The undoped semiconductor layer <NUM> may be a layer that is not removed when the semiconductor light emitting diodes <NUM> grown on the growth substrate are separated from the growth substrate during the manufacturing process of the semiconductor light emitting diode <NUM>.

In general, semiconductor light emitting diodes <NUM> from which the undoped semiconductor layer <NUM> is removed are used for self-assembly. However, when the semiconductor light emitting diode <NUM> including the undoped semiconductor layer <NUM> is used as in the present disclosure, the weight of the semiconductor light emitting diode <NUM> itself increases, thereby increasing the assembly speed.

The undoped semiconductor layer <NUM> may include a recessed portion 2050R.

In other words, the recessed portion 2050R may be formed to pass through the undoped semiconductor layer <NUM>, and the recessed portion 2050R included in the semiconductor light emitting diodes <NUM> emitting light of different colors from each other may be formed by etching different regions of the undoped semiconductor layer <NUM>.

In addition, the recessed portion 2050R may be formed by etching up to a portion of the second conductivity type semiconductor layer <NUM> to form an ohmic.

Meanwhile, the second conductivity type electrode <NUM> and the undoped semiconductor layer <NUM> may be formed in different regions on the second conductivity type semiconductor layer <NUM>.

The second conductivity type electrode <NUM> may be formed on the region of the second semiconductor layer <NUM> overlapping the bottom surface of the recessed portion 2050R. Specifically, the second conductivity type electrode <NUM> may be formed along the pattern of the recessed portion 2050R.

The second conductivity type electrode <NUM> may further include a magnetic layer 2055b to be induced by a magnetic force during self-assembly. In other words, the second conductivity type electrode <NUM> may include a metal layer 2055a and a magnetic layer 2055b for ohmic contact.

The magnetic layer 2055b may be formed of a metal material such as Cr, Ti, or the like in order to improve adhesion to the metal layer 2055a.

Meanwhile, the solder portion <NUM> formed on the base portion <NUM> and coupled to the recessed portion 2050R can be formed of an element selected from Sn, In, Pb, Bi, Cd, and Zn, an element having a similar melting point to that of the element, or composite of elements.

In addition, the solder portion <NUM> may be formed to have a thickness greater than that of the undoped semiconductor layer <NUM> based on the stacking direction of the semiconductor light emitting diode <NUM>.

In addition, although not shown in the drawings, the solder portion <NUM> may further include a magnetic layer. In a case where the solder portion <NUM> includes a magnetic layer, when a magnetic force acts between the solder portion <NUM> and the semiconductor light emitting diode <NUM> to remove the fluid contained in the chamber after self-assembly, it is possible to prevent the semiconductor light emitting diode <NUM> from being separated from the cell <NUM> by the flow of the fluid.

Meanwhile, the base portion <NUM> may further include a wiring electrode (hereinafter, a first wiring electrode <NUM>) formed on the dielectric layer <NUM>.

The first wiring electrode <NUM> may be formed to contact the solder portion <NUM> under the solder portion <NUM>, and thus the second conductivity type electrode <NUM> and the first wiring electrode <NUM> may be electrically connected to each other by coupling the recessed portion 2050R and the solder portion <NUM>. Meanwhile, a separate heat treatment step for electrical connection between the second conductivity type electrode <NUM> and the first wiring electrode <NUM> may be performed.

In addition, the first wiring electrode <NUM> may be disposed on the dielectric layer <NUM> so as not to overlap the assembled electrodes <NUM>.

In addition, although not shown in the drawings, a second wiring electrode (not shown) electrically connected to the first conductivity type electrode <NUM> of the semiconductor light emitting diode <NUM> may be further included. The second wiring electrode may be formed under the semiconductor light emitting diode <NUM> like the first wiring electrode <NUM> or formed above the semiconductor light emitting diode <NUM>.

<FIG> is a diagram showing a recessed portion of a semiconductor light emitting diode and a pattern of a solder portion of a substrate according to the embodiment of <FIG>, <FIG> is a view showing a comparison of a state where a semiconductor light emitting diode is normally assembled on a substrate and a state where a semiconductor light emitting diode is incorrectly assembled on a substrate, and <FIG> are views showing a recessed portion of a semiconductor light emitting diode and a pattern of a solder portion of a substrate according to another embodiment of the present invention.

As shown in <FIG>, the semiconductor light emitting diode <NUM> emitting different colors includes recessed portions 2050R having different shapes.

In an embodiment, as shown in <FIG> and <FIG>, the semiconductor light emitting diode <NUM> includes recessed portions 2050R formed at different positions on one surface, and in a bottom surface of the cell <NUM>, a solder portion <NUM> having a shape corresponding to this, respectively is formed.

In another embodiment, as shown in <FIG>, the semiconductor light emitting diode <NUM> may include a patterned recessed portion 2050R having different aspect ratios on one surface, and in the bottom surface of the cell 2040a, a solder portion <NUM> having a shape corresponding to this, respectively may be formed.

The semiconductor light emitting diode <NUM> is seated in the cell <NUM> including the solder portion <NUM> that corresponds to the recessed portion 2050R to be capable of being strongly fixed inside the cell <NUM> by the electric field formed by the assembled electrodes <NUM>.

On the other hand, in a case where the semiconductor light emitting diode <NUM> is seated in the cell <NUM> including the solder portion <NUM> having a pattern that does not correspond to the recessed portion 2050R, the bonding force (surface energy acting between the semiconductor light emitting diode <NUM> and the solder portion <NUM>) is relatively weak, so that the semiconductor light emitting diode cannot be strongly fixed to the cell <NUM> and may be easily detached from the cell <NUM>.

Accordingly, by forming patterns (the recessed portion 2050R and the solder portion <NUM>) on the semiconductor light emitting diode <NUM> and the substrate, respectively, there is an effect in that self-assembly of the semiconductor light emitting diodes <NUM> of different colors can be simultaneously performed.

In particular, according to an embodiment of the present invention, there is no need to manufacture so that sizes or shapes of the semiconductor light emitting diodes <NUM> are different from each other to assemble the semiconductor light emitting diodes that emit light of different colors from each other at the same time.

According to an embodiment of the present invention, the semiconductor light emitting diode <NUM> may have vertical selectivity when assembling the cell <NUM>. Hereinafter, the structure of the semiconductor light emitting diode <NUM> for this will be described.

<FIG> are diagrams showing a semiconductor light emitting diode according to another embodiment of the present invention.

First, the semiconductor light emitting diode <NUM> may further include a passivation layer <NUM> formed on the surface. The passivation layer <NUM> may be formed to cover a portion of the surface of the semiconductor light emitting diode including the first conductivity type electrode <NUM> on the other surface side of the semiconductor light emitting diode <NUM>, and, preferably, may be formed to extend from the top surface of the first conductivity type electrode <NUM> to the side surface of the semiconductor light emitting diode <NUM>.

In addition, the passivation layer <NUM> may include an open hole for electrically connecting the first conductivity type electrode <NUM> to the second wiring electrode.

According to an embodiment of the present invention, in the semiconductor light emitting diode <NUM>, the area of one surface of the semiconductor light emitting diode <NUM> including the recessed portion 2050R such that the recessed portion 2050R faces the bottom surface of the cell <NUM> and the area of the other surface of the semiconductor light emitting diode <NUM> on which the passivation layer <NUM> is formed may be formed to be different from each other.

Specifically, in the semiconductor light emitting diode <NUM>, the area of the passivation layer <NUM> on the other side of the semiconductor light emitting diode <NUM> may be patterned to be smaller than the area of the undoped semiconductor layer <NUM> which is substantially in contact with the bottom surface of the cell <NUM> on the one side of the semiconductor light emitting diode <NUM>.

In one embodiment, as shown in <FIG>, the area of the other surface of the semiconductor light emitting diode <NUM> may be formed to be smaller than the area of one surface of the semiconductor light emitting diode <NUM> by etching the circumferential portion except for the central region of the passivation layer <NUM> formed on the other side of the semiconductor light emitting diode <NUM>.

In another embodiment, as shown in <FIG>, the area of the other surface of the semiconductor light emitting diode <NUM> may be adjusted by etching a portion of the first conductivity type semiconductor layer <NUM> and the first conductivity type electrode <NUM> to form a mesa.

In addition, the semiconductor light emitting diode <NUM> may further include a metal film <NUM> formed along an undoped semiconductor layer <NUM> and a recessed portion 2050R on one side of the semiconductor light emitting diode <NUM> such that the recessed portion 2050R faces the bottom surface of the cell <NUM>. The metal film <NUM> may be formed of, for example, Ti, but is not limited thereto. Since the semiconductor light emitting diode <NUM> includes the metal film <NUM>, the semiconductor light emitting diode <NUM> can be easily guided into the assembly position, that is, into the cell <NUM>.

As described above, the display device <NUM> according to the embodiment of the present invention has the effect of being able to perform self-assembly by simultaneously putting the semiconductor light emitting diodes <NUM> emitting light of different colors into the fluid chamber.

In particular, since the semiconductor light emitting diodes <NUM> are seated at positions where the solder portions <NUM> having a pattern corresponding to the recessed parts 2050R formed on one surface are formed, in order to self-assemble the semiconductor light emitting diodes <NUM> at the same time. , there is no need to manufacture different sizes or shapes of the semiconductor light emitting diodes <NUM> that emit light of different colors.

In addition, there is an effect that the semiconductor light emitting diode <NUM> may be connected to a wiring electrode through a bonding of the recessed portion 2050R and the solder portion <NUM>, and the semiconductor light emitting diode <NUM> seated in the cell <NUM> is stably fixed to the substrate by the magnetic layer included in the solder portion <NUM>.

Claim 1:
A display device comprising:
a base portion (<NUM>);
assembled electrodes (<NUM>) extending along one direction on the base portion (<NUM>);
a dielectric layer (<NUM>) to cover the assembled electrodes (<NUM>);
a partition wall portion (<NUM>) on the dielectric layer (<NUM>) while forming a plurality of cells (<NUM>); and
a plurality of semiconductor light emitting diodes (<NUM>) seated in the plurality of cells (<NUM>), respectively, and to emit light of different colors,
wherein the plurality of semiconductor light emitting diodes (<NUM>) emitting different colors include recessed portions (2050R) having different shapes on one surface thereof, and
wherein a bottom surface of the plurality of cells (<NUM>) includes a solder portion (<NUM>) protruding to correspond to the recessed portions (2050R) of the plurality of semiconductor light emitting diodes (<NUM>) seated in the plurality of cells (<NUM>), respectively.