KR20230085100A - Semiconductor light emitting device, bonding method thereof, and display device including semiconductor light emitting device - Google Patents

Abstract

A method of bonding a semiconductor light emitting device for a display pixel according to an embodiment includes the steps of: forming a plurality of semiconductor light emitting devices on a first substrate; forming an insulating layer on the first substrate and the plurality of semiconductor light emitting devices; etching an insulating layer formed between the plurality of semiconductor light emitting devices; compressing the first substrate and a second substrate to allow the plurality of semiconductor light emitting devices to correspond to bonding areas formed on the second substrate; and removing the first substrate. Therefore, it is possible to prevent the semiconductor light emitting device from leaving a transfer substrate.

Description

Semiconductor light emitting device for display pixel, bonding method thereof, and display device including semiconductor light emitting device

Embodiments relate to a semiconductor light emitting device for a display pixel, a bonding method thereof, and a display device including the semiconductor light emitting device.

Large-area displays include liquid crystal displays (LCDs), OLED displays, and micro-LED displays.

A micro-LED display is a display using a micro-LED, which is a semiconductor light emitting device having a diameter or cross-sectional area of 100 μm or less, as a display device.

Micro-LED display has excellent performance in many characteristics such as contrast ratio, response speed, color reproducibility, viewing angle, brightness, resolution, lifespan, luminous efficiency or luminance because it uses micro-LED, which is a semiconductor light emitting device, as a display element.

In particular, the micro-LED display has the advantage of being free to adjust the size or resolution as screens can be separated and combined in a modular manner, and can implement a flexible display.

However, since a large micro-LED display requires millions of micro-LEDs, there is a technical problem in that it is difficult to quickly and accurately transfer the micro-LEDs to the display panel.

Transfer technologies that have recently been developed include a pick and place process, a laser lift-off method, or a self-assembly method.

Among them, the self-assembly method is a method in which a semiconductor light emitting device finds an assembly position in a fluid by itself, and is advantageous for implementing a large-screen display device.

Recently, US Patent No. 9,825,202 has proposed a micro-LED structure suitable for self-assembly, but research on a technology for manufacturing a display through self-assembly of micro-LEDs is still insufficient.

In particular, in the case of rapidly transferring millions or more semiconductor light emitting devices to a large display in the prior art, the transfer speed can be improved, but the transfer error rate can be increased, resulting in a low transfer yield. There is a technical problem.

On the other hand, in related technologies, a self-assembly type transfer process using dielectrophoresis (DEP) has been attempted, but there is a problem in that the self-assembly rate is low due to non-uniformity of DEP force.

On the other hand, in the self-assembly method using the DEP force of internal technology, the step of first moving the LED chip to the assembly hole area with the magnetic force of the magnet, the step of assembling the LED chip in the assembly hole by applying AC to the assembly wiring and assembling the LED chip with the DEP force includes

However, since the upper and lower sides of the LED chip are composed of an n-type semiconductor layer and a p-type semiconductor layer, and an n-type electrode and a p-type electrode are disposed, respectively, it is very important to assemble the LED chip in the assembly hole while maintaining the vertical direction. . This is because electrical disconnection defects may occur in a subsequent wiring process when the direction of the LED chip is tilted or even reversely rotated by 180 degrees.

However, according to internal research, it has been studied as a difficult problem to directionally control LED chips during self-assembly moving in a fluid, and a solution to this problem is critically required.

In addition, in the internal technology, the problem of the separation of the LED chip from the transfer substrate and the decrease in the regular assembly rate of assembling the semiconductor light emitting device to the assembly substrate are being studied.

In addition, in the case of a semiconductor light emitting device emitting red color, there is a problem in that light efficiency is reduced due to material characteristics compared to a semiconductor light emitting device emitting blue or green color.

A technical problem of the embodiment is to provide a bonding method of a semiconductor light emitting device so that the semiconductor light emitting device does not separate from the transfer substrate.

In addition, a technical problem of the embodiment is to provide a bonding method of a semiconductor light emitting device with improved assembly ratio of the semiconductor light emitting device.

In addition, a technical problem of the embodiment is to provide a bonding method of semiconductor light emitting devices capable of preventing tension between semiconductor light emitting devices.

In addition, a technical problem of the embodiment is to provide a semiconductor light emitting device capable of electrical connection from the side of the semiconductor light emitting device and a display device including the same.

In addition, a technical problem of the embodiment is to provide a semiconductor light emitting device capable of controlling the directionality of the top and bottom of the semiconductor light emitting device during self-assembly, and a display device including the same.

In addition, a technical problem of the embodiment is to improve the luminance of a semiconductor light emitting device emitting red color.

The tasks of the embodiments are not limited to the tasks mentioned above, but include what can be grasped from the specification.

A bonding method of a semiconductor light emitting device according to an embodiment includes forming a plurality of semiconductor light emitting devices on a first substrate; forming an insulating layer on the first substrate and the plurality of semiconductor light emitting devices; etching an insulating layer formed between the plurality of semiconductor light emitting devices; pressing the first substrate and the second substrate so that the plurality of semiconductor light emitting devices correspond to a bonding area formed on a second substrate; and removing the first substrate.

In an embodiment, the etching of the insulating layer may include forming a mask pattern, for example, a PR mask, on the insulating layer except between the plurality of semiconductor light emitting devices.

Also, in the etching of the insulating layer in the embodiment, at least one of the insulating layers formed between the plurality of semiconductor light emitting devices may not be etched.

Also, in an embodiment, a photo active compound (PAC) may be applied to the bonding area.

In addition, a semiconductor light emitting device according to an embodiment includes a light emitting structure including a first semiconductor layer, an active layer disposed under the first semiconductor layer, and a second semiconductor layer disposed under the active layer; a first metal layer disposed below the second semiconductor layer and in contact with the second semiconductor layer; a magnetic layer disposed under the first metal layer; and a second metal layer disposed below the magnetic layer, wherein the second metal layer extends to a side surface of the light emitting structure.

Also, in an embodiment, a width of the second metal layer may be greater than a width of the light emitting structure.

In addition, in the embodiment, the second metal layer includes a 2-1 metal layer disposed on a lower surface of the magnetic layer and a 2-2 metal layer disposed on a side surface of the magnetic layer, wherein the 2-2 metal layer is the first metal layer. side contact.

In addition, a display device including a semiconductor light emitting device according to an embodiment includes a substrate; assembly wiring disposed on the substrate; a barrier rib disposed on the assembled wiring and having an opening; and the semiconductor light emitting device according to any one of claims 5 to 7.

Also, in an embodiment, the second metal layer may be electrically connected to the assembly wiring.

In addition, in an embodiment, a panel wiring electrically connected to an upper surface of the semiconductor light emitting device may be included.

The semiconductor light emitting device and its bonding method according to the embodiment and the display device including the same have a technical effect of preventing the semiconductor light emitting device from being separated from the transfer substrate.

The semiconductor light emitting device according to the embodiment, the bonding method thereof, and the display device including the same have a technical effect of improving the assembly rate of the semiconductor light emitting device during self-assembly.

A semiconductor light emitting device and a bonding method thereof according to an embodiment and a display device including the same have technical effects capable of preventing tension between semiconductor light emitting devices during a transfer process.

A semiconductor light emitting device and a bonding method thereof according to an embodiment and a display device including the same have technical effects capable of electrical connection to the side of the semiconductor light emitting device.

A semiconductor light emitting device according to an embodiment, a bonding method thereof, and a display device including the same have technical effects capable of controlling upward and downward directions of the semiconductor light emitting device during self-assembly.

A semiconductor light emitting device according to an embodiment, a bonding method thereof, and a display device including the same have technical effects capable of improving the luminance of a semiconductor light emitting device emitting red color to be equal to the luminance of a semiconductor light emitting device emitting blue or green color. there is

The technical effects of the embodiments are not limited to those described in this section, and include those that can be grasped throughout the specification.

1 is an exemplary view of a living room of a house in which a display device according to an embodiment is disposed.
2 is a schematic block diagram of a display device according to an exemplary embodiment.
3 is a circuit diagram illustrating an example of a pixel of FIG. 2 .
FIG. 4 is an enlarged view of a first panel area in the display device of FIG. 1 .
FIG. 5 is a cross-sectional view taken along line B1-B2 of area A2 of FIG. 4 .
6 is an exemplary view in which a light emitting device according to an embodiment is assembled to a substrate by a self-assembly method.
7 is a diagram showing a phenomenon of separation of an LED chip during transfer in an internal technology.
8A to 11 are process charts explaining a method of bonding the semiconductor light emitting device of the semiconductor light emitting device according to the first embodiment.
12 is a cross-sectional view of a semiconductor light emitting device according to a second embodiment.
13 to 15 are process charts of a semiconductor light emitting device according to a second embodiment.
16 is a cross-sectional view showing a portion of a display device including a semiconductor light emitting device according to a third embodiment.

Hereinafter, embodiments disclosed herein will be described in detail with reference to the accompanying drawings. The suffixes 'module' and 'unit' for the components used in the following description are given or used interchangeably in consideration of ease of writing the specification, and do not themselves have a meaning or role that is distinct from each other. In addition, the accompanying drawings are for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the accompanying drawings. Also, when an element such as a layer, region or substrate is referred to as being 'on' another element, this includes being directly on the other element or other intervening elements may be present therebetween. do.

Display devices described in this specification include digital TVs, mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, and slates. ) PC, tablet PC, ultra-book, desktop computer, etc. may be included. However, the configuration according to the embodiment described in this specification can be applied to a device capable of displaying even a new product type to be developed in the future.

Hereinafter, a semiconductor light emitting device according to an embodiment, a bonding method thereof, and a display device including the semiconductor light emitting device will be described.

1 illustrates a living room of a house in which a display device 100 according to an exemplary embodiment is disposed.

The display device 100 of the embodiment can display the status of various electronic products such as the washing machine 101, the robot cleaner 102, and the air purifier 103, can communicate with each electronic product based on IOT, and can provide user It is also possible to control each electronic product based on the setting data of the .

The display device 100 according to the embodiment may include a flexible display fabricated on a thin and flexible substrate. A flexible display can be bent or rolled like paper while maintaining characteristics of a conventional flat panel display.

In a flexible display, visual information can be implemented by independently controlling light emission of unit pixels arranged in a matrix form. A unit pixel means a minimum unit for implementing one color. A unit pixel of the flexible display may be implemented by a light emitting device. In the embodiment, the light emitting device may be a Micro-LED or a Nano-LED, but is not limited thereto.

FIG. 2 is a block diagram schematically illustrating a display device according to an exemplary embodiment, and FIG. 3 is a circuit diagram illustrating an example of a pixel of FIG. 2 .

Referring to FIGS. 2 and 3 , a display device according to an embodiment may include a display panel 10 , a driving circuit 20 , a scan driving unit 30 and a power supply circuit.

The display device 100 of the embodiment may drive a light emitting element in an active matrix (AM) method or a passive matrix (PM) method.

The driving circuit 20 may include a data driver 21 and a timing controller 22 .

The display panel 10 may be divided into a display area DA and a non-display area NDA disposed around the display area DA. The display area DA is an area where the pixels PX are formed to display an image. The display panel 10 includes data lines (D1 to Dm, where m is an integer greater than or equal to 2), scan lines (S1 to Sn, where n is an integer greater than or equal to 2) crossing the data lines (D1 to Dm), and a high potential voltage. It may include pixels PXs connected to a high-potential voltage line supplied thereto, a low-potential voltage line supplied with a low-potential voltage, data lines D1 to Dm, and scan lines S1 to Sn.

Each of the pixels PX may include a first sub-pixel PX1 , a second sub-pixel PX2 , and a third sub-pixel PX3 . The first sub-pixel PX1 emits light of a first color of a first wavelength, the second sub-pixel PX2 emits light of a second color of a second wavelength, and the third sub-pixel PX3 emits light of a third color. A third color light of a wavelength may be emitted. The first color light may be red light, the second color light may be green light, and the third color light may be blue light, but are not limited thereto. In addition, in FIG. 2, it is illustrated that each of the pixels PX includes three sub-pixels, but is not limited thereto. That is, each of the pixels PX may include four or more sub-pixels.

Each of the first sub-pixel PX1 , the second sub-pixel PX2 , and the third sub-pixel PX3 includes at least one of the data lines D1 to Dm, at least one of the scan lines S1 to Sn, and a high voltage signal. It can be connected to the above voltage line. As shown in FIG. 3 , the first sub-pixel PX1 may include light emitting elements LDs, a plurality of transistors for supplying current to the light emitting elements LDs, and at least one capacitor Cst.

Although not shown in the drawings, each of the first sub-pixel PX1 , the second sub-pixel PX2 , and the third sub-pixel PX3 may include only one light emitting element LD and at least one capacitor Cst. may be

Each of the light emitting elements LD may be a semiconductor light emitting diode including a first electrode, a plurality of conductive semiconductor layers, and a second electrode. Here, the first electrode may be an anode electrode and the second electrode may be a cathode electrode, but is not limited thereto.

Referring to FIG. 3 , the plurality of transistors may include a driving transistor DT supplying current to the light emitting elements LD and a scan transistor ST supplying a data voltage to a gate electrode of the driving transistor DT. . The driving transistor DT has a gate electrode connected to the source electrode of the scan transistor ST, a source electrode connected to a high potential voltage line to which a high potential voltage is applied, and a drain connected to the first electrodes of the light emitting devices LD. electrodes may be included. The scan transistor ST has a gate electrode connected to the scan line (Sk, k is an integer satisfying 1≤k≤n), a source electrode connected to the gate electrode of the driving transistor DT, and data lines Dj, j an integer that satisfies 1≤j≤m).

The capacitor Cst is formed between the gate electrode and the source electrode of the driving transistor DT. The storage capacitor Cst may charge a difference between the gate voltage and the source voltage of the driving transistor DT.

The driving transistor DT and the scan transistor ST may be formed of thin film transistors. In addition, in FIG. 3, the driving transistor DT and the scan transistor ST have been mainly described as being formed of P-type MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), but the present invention is not limited thereto. The driving transistor DT and the scan transistor ST may be formed of N-type MOSFETs. In this case, positions of the source and drain electrodes of the driving transistor DT and the scan transistor ST may be changed.

In addition, in FIG. 3 , each of the first sub-pixel PX1 , the second sub-pixel PX2 , and the third sub-pixel PX3 includes one driving transistor DT, one scan transistor ST, and one capacitor ( 2T1C (2 Transistor - 1 capacitor) having Cst) is illustrated, but the present invention is not limited thereto. Each of the first sub-pixel PX1 , the second sub-pixel PX2 , and the third sub-pixel PX3 may include a plurality of scan transistors ST and a plurality of capacitors Cst.

Referring back to FIG. 2 , the driving circuit 20 outputs signals and voltages for driving the display panel 10 . To this end, the driving circuit 20 may include a data driver 21 and a timing controller 22 .

The data driver 21 receives digital video data DATA and a source control signal DCS from the timing controller 22 . The data driver 21 converts the digital video data DATA into analog data voltages according to the source control signal DCS and supplies them to the data lines D1 to Dm of the display panel 10 .

The timing controller 22 receives digital video data DATA and timing signals from the host system. The timing signals may include a vertical sync signal, a horizontal sync signal, a data enable signal, and a dot clock. The host system may be an application processor of a smart phone or tablet PC, a monitor, a system on chip of a TV, and the like.

The scan driver 30 receives the scan control signal SCS from the timing controller 22 . The scan driver 30 generates scan signals according to the scan control signal SCS and supplies them to the scan lines S1 to Sn of the display panel 10 . The scan driver 30 may include a plurality of transistors and be formed in the non-display area NDA of the display panel 10 . Alternatively, the scan driver 30 may be formed as an integrated circuit, and in this case, it may be mounted on a gate flexible film attached to the other side of the display panel 10 .

The power supply circuit generates a high-potential voltage (VDD) and a low-potential voltage (VSS) for driving the light emitting elements (LD) of the display panel 10 from the main power supply to generate a high-potential voltage line and a low-potential voltage line of the display panel 10. It can be supplied to potential voltage lines. Also, the power supply circuit may generate and supply driving voltages for driving the driving circuit 20 and the scan driving unit 30 from the main power supply.

FIG. 4 is an enlarged view of the first panel area A1 in the display device of FIG. 1 .

Referring to FIG. 4 , the display device 100 of the embodiment may be manufactured by mechanically and electrically connecting a plurality of panel areas such as the first panel area A1 by tiling.

The first panel area A1 may include a plurality of light emitting devices 150 disposed for each unit pixel (PX in FIG. 2 ).

For example, the unit pixel PX may include a first sub-pixel PX1 , a second sub-pixel PX2 , and a third sub-pixel PX3 . For example, a plurality of red light emitting elements 150R are disposed in the first sub-pixel PX1, a plurality of green light emitting elements 150G are disposed in the second sub-pixel PX2, and a plurality of blue light emitting elements 150B. may be disposed in the third sub-pixel PX3. The unit pixel PX may further include a fourth sub-pixel in which no light emitting element is disposed, but is not limited thereto. Meanwhile, the light emitting device 150 may be a semiconductor light emitting device.

Next, FIG. 5 is a cross-sectional view taken along line B1-B2 of region A2 of FIG. 4 .

Referring to FIG. 5 , the display device 100 of the embodiment includes a substrate 200, assembled wires 201 and 202, a first insulating layer 211a, a second insulating layer 211b, and a third insulating layer 206. And it may include a plurality of light emitting devices (150).

The assembly line may include a first assembly line 201 and a second assembly line 202 spaced apart from each other. The first assembling wire 201 and the second assembling wire 202 may be provided to generate dielectrophoretic force for assembling the light emitting device 150 . In addition, the first assembly line 201 and the second assembly line 202 may be electrically connected to the electrode of the light emitting device to function as electrodes of a display panel.

The assembled wires 201 and 202 may be formed of light-transmitting electrodes (ITO) or may include a metal material having excellent electrical conductivity. For example, the assembled wires 201 and 202 may be titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), tungsten (W), molybdenum (Mo) ) It may be formed of at least one or an alloy thereof.

A first insulating layer 211a may be disposed between the first assembly wire 201 and the second assembly wire 202 , and a first insulating layer 211a may be disposed on the first assembly wire 201 and the second assembly wire 202 . 2 insulating layers 211b may be disposed. The first insulating layer 211a and the second insulating layer 211b may be an oxide film or a nitride film, but are not limited thereto.

The light emitting device 150 may include a red light emitting device 150R, a green light emitting device 150G, and a blue light emitting device 150B to form a sub-pixel, but is not limited thereto, and is a red phosphor. It is also possible to implement red and green, respectively, by providing a green phosphor and the like.

The substrate 200 may be formed of glass or polyimide. In addition, the substrate 200 may include a flexible material such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET). In addition, the substrate 200 may be a light-transmitting material, but is not limited thereto.

The third insulating layer 206 may include an insulating and flexible material such as polyimide, PEN, PET, or the like, and may be integrally formed with the substrate 200 to form a single substrate.

The third insulating layer 206 may be a conductive adhesive layer having adhesiveness and conductivity, and the conductive adhesive layer may be flexible and thus enable a flexible function of the display device. For example, the third insulating layer 206 may be an anisotropy conductive film (ACF) or a conductive adhesive layer such as an anisotropic conductive medium or a solution containing conductive particles. The conductive adhesive layer may be a layer that is electrically conductive in a direction perpendicular to the thickness but electrically insulating in a direction horizontal to the thickness.

The third insulating layer 206 may include an assembly hole 203 into which the light emitting device 150 is inserted (see FIG. 6 ). Accordingly, during self-assembly, the light emitting device 150 can be easily inserted into the assembly hole 203 of the third insulating layer 206 . The assembly hole 203 may be called an insertion hole, a fixing hole, an alignment hole, or the like.

The distance between the assembly lines 201 and 202 is smaller than the width of the light emitting element 150 and the width of the assembly hole 203, so that the assembly position of the light emitting element 150 using an electric field can be more precisely fixed.

A third insulating layer 206 is formed on the assembly wires 201 and 202 to protect the assembly wires 201 and 202 from the fluid 1200 and prevent leakage of current flowing through the assembly wires 201 and 202. can The third insulating layer 206 may be formed of a single layer or multiple layers of an inorganic insulator such as silica or alumina or an organic insulator.

In addition, the third insulating layer 206 may include an insulating and flexible material such as polyimide, PEN, PET, or the like, and may be integrally formed with the substrate 200 to form a single substrate.

The third insulating layer 206 may be an adhesive insulating layer or a conductive adhesive layer having conductivity. The third insulating layer 206 is ductile and can enable a flexible function of the display device.

The third insulating layer 206 has a barrier rib, and an assembly hole 203 may be formed by the barrier rib. For example, when the substrate 200 is formed, a portion of the third insulating layer 206 is removed, so that each of the light emitting devices 150 may be assembled into the assembly hole 203 of the third insulating layer 206 .

An assembly hole 203 to which the light emitting devices 150 are coupled is formed in the substrate 200 , and a surface on which the assembly hole 203 is formed may contact the fluid 1200 . The assembly hole 203 may guide an accurate assembly position of the light emitting device 150 .

Meanwhile, the assembly hole 203 may have a shape and size corresponding to the shape of the light emitting element 150 to be assembled at the corresponding position. Accordingly, it is possible to prevent assembly of another light emitting element or a plurality of light emitting elements into the assembly hole 203 .

6 is a view showing an example in which a light emitting device according to an embodiment is assembled to a substrate by a self-assembly method, and the self-assembly method of the light emitting device will be described with reference to the drawings.

The substrate 200 may be a panel substrate of a display device. In the following description, the substrate 200 will be described as a panel substrate of a display device, but the embodiment is not limited thereto.

Referring to FIG. 6 , a plurality of light emitting devices 150 may be put into a chamber 1300 filled with a fluid 1200 . The fluid 1200 may be water such as ultrapure water, but is not limited thereto. A chamber may also be called a water bath, container, vessel, or the like.

After that, the substrate 200 may be disposed on the chamber 1300 . Depending on the embodiment, the substrate 200 may be introduced into the chamber 1300 .

As shown in FIG. 5 , a pair of assembly wires 201 and 202 corresponding to each of the light emitting devices 150 to be assembled may be disposed on the substrate 200 .

Referring to FIG. 6 , after the substrate 200 is disposed, an assembly device 1100 including a magnetic material may move along the substrate 200 . As the magnetic material, for example, a magnet or an electromagnet may be used. The assembly device 1100 may move while in contact with the substrate 200 in order to maximize the area of the magnetic field into the fluid 1200 . Depending on the embodiment, the assembly device 1100 may include a plurality of magnetic bodies or may include a magnetic body having a size corresponding to that of the substrate 200 . In this case, the moving distance of the assembling device 1100 may be limited within a predetermined range.

The light emitting device 150 in the chamber 1300 may move toward the assembly device 1100 by the magnetic field generated by the assembly device 1100 .

While moving toward the assembly device 1100 , the light emitting device 150 may enter the assembly hole 203 by a dielectrophoretic force (DEP force) and come into contact with the substrate 200 .

In detail, the assembled wires 201 and 202 form an electric field by an externally supplied power, and dielectrophoretic force can be formed between the assembled wires 201 and 202 by the electric field. The light emitting element 150 can be fixed to the assembly hole 203 on the substrate 200 by this dielectrophoretic force.

The light emitting element 150 in contact with the substrate 200 may be prevented from being separated by the movement of the assembly device 1100 by the electric field applied by the assembly wires 201 and 202 formed on the substrate 200 . . According to the embodiment, since the time required to assemble each of the light emitting devices 150 to the substrate 200 can be drastically reduced by the above-described self-assembly method using the electromagnetic field, a large-area high-pixel display can be made more quickly and can be implemented economically.

At this time, a predetermined solder layer (not shown) may be formed between the assembled electrode and the light emitting device 150 assembled on the assembly hole 203 of the substrate 200 to improve the bonding strength of the light emitting device 150 .

Next, a molding layer (not shown) may be formed in the assembly hole 203 of the substrate 200 . The molding layer may be a light-transmissive resin or a resin containing a reflective material or a scattering material.

Hereinafter, a semiconductor light emitting device and a bonding method thereof according to embodiments for solving technical problems and a display device including the semiconductor light emitting device will be described with reference to drawings.

[Example]

Meanwhile, FIG. 7 is a view according to an internal technology related to bonding of a semiconductor light emitting device.

As shown in FIG. 7, in the bonding technology of the semiconductor light emitting device according to the internal technology, the semiconductor light emitting device 50 is grown on the growth substrate 10, the oxide layer 40 is formed, and a chemical lift-off (CLO) process is performed. When the growth substrate 10 is removed, tension is generated between the LED chips 50 due to the tension of the oxide layer 40, and the LED chip 50 is detached from the bonding area. Therefore, there is a problem in that the transfer rate decreases, and then, when the LED chip 50 is transferred to the assembly substrate 11 provided with the bonding area 12, the normal assembly rate decreases. In addition, particles are generated when the insulating layer is removed after the chemical lift-off (CLO) process that separates the semiconductor light emitting device from the growth substrate in the primary transfer process. When self-assembling in a fluid, the particles act as powder. Thus, there is a problem in that the self-assembly transfer rate is significantly reduced.

Accordingly, one of the technical problems of the embodiment is to solve the problem of the semiconductor light emitting device being separated from the bonding area in the process of transferring the semiconductor light emitting device.

8A to 11 are process charts illustrating a bonding method of a semiconductor light emitting device. (In the following description, 'first embodiment' will be abbreviated as 'embodiment')

Referring to FIG. 8A , a plurality of semiconductor light emitting devices 150 may be grown on the first substrate 110 . The first substrate 110 may be a Group 3-5 compound semiconductor material or a Group 2-6 compound semiconductor material constituting a semiconductor light emitting device. For example, the first substrate 110 may include GaN, InGaN, AlN, AlInN, AlGaN, AlInGaN, InP, GaAs, GaP, GaInP, etc., and may be used as a growth substrate for the semiconductor light emitting device 150. there is.

In addition, a first electrode (not shown) may be formed on a surface opposite to the first substrate 110 in the plurality of semiconductor light emitting devices 150 . The first electrode may be formed as a light-transmitting electrode (not shown) to improve the light extraction efficiency of the semiconductor light emitting device. The light-transmitting electrode layer includes indium tin oxide (ITO), indium aluminum zinc oxide (IAZO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO) to include at least one of may be, but is not limited to these materials.

Referring to FIG. 8B , an insulating layer 140 may be formed on the plurality of semiconductor light emitting devices 150 grown on the substrate 110 . The insulating layer 140 may be formed to cover the plurality of semiconductor light emitting devices 150 and the substrate 110 . The insulating layer 140 may be formed of SiO ₂ , but is not limited thereto.

Referring to FIG. 8C , a PR mask 140 may be formed on the insulating layer 140 . The PR mask 140 is formed only on an insulating layer overlapping the plurality of semiconductor light emitting devices 150 on the substrate 110, and can be used in a subsequent etching process.

On the other hand, in the case of a mini LED with a size of 100um or more in internally researched technology, the growth substrate was separated through a laser lift off (LLO) process or a chemical lift off (CLO) process without removing the insulating layer. On the other hand, in the case of a micro LED with a size of about 10um, when the CLO process was performed after bonding to the transfer substrate, bonding defects occurred in about 80% or more of the total area, which is due to the presence of stress between the semiconductor epitaxial layer and the insulating layer. confirmed to be Therefore, there is a need for a technique for preventing stress between the semiconductor epitaxial layer and the insulating layer by isolating the insulating layer before separating the growth substrate.

Subsequently, referring to FIG. 9A , a process of etching the insulating layer 140 not covered by the PR mask 160 as a mask pattern is performed. The etching process may include dry etching and wet etching. The mask pattern 160 is located between the plurality of semiconductor light emitting devices 150, and the insulating layer 140 not covered by the PR mask 160 is etched and the insulating layer 140 formed integrally is isolated. can be separated Insulation layer isolation may be performed between each of the plurality of semiconductor light emitting devices.

Thereafter, the isolated insulating layer does not generate tension between the insulating layers, so that the semiconductor light emitting device can be stably fixed to the bonding area of the transfer substrate.

Also, referring to FIG. 9B , multi-isolation of the insulating layer 140 may be performed by grouping a plurality of semiconductor light emitting devices. Multi-isolation also groups a plurality of semiconductor light emitting devices so that the groups are etched and the tension between the insulating layers is reduced, so the same effect as single-isolation can be obtained.

Subsequently, referring to FIG. 10 , the plurality of semiconductor light emitting devices 150 in a state in which the insulating layer 140 is isolated on the first substrate 110 are transferred to the second substrate 111 . The second substrate 111 may be a sapphire substrate, but is not limited thereto. In this case, the connection between the plurality of semiconductor light emitting devices and the second substrate may be performed by applying a photo active compound (PAC), then compressing and curing the first substrate and the second substrate to bond, but is not limited thereto. .

Referring to FIG. 11 , a process of removing the first substrate is performed while the plurality of semiconductor light emitting devices 150 are bonded to the second substrate. When the semiconductor light emitting device 150 emits blue or green color, a laser lift-off (LLO) process or the like may be used, and when the semiconductor light emitting device 150 emits red color, a chemical lift-off (CLO) process, etc. This may be used, but is not limited thereto. The chemical solution used in the chemical lift-off (CLO) process may be ammonia, hydrogen peroxide, or a mixture thereof, but is not limited thereto.

The first substrate 110 may be removed by a chemical solution, and the plurality of semiconductor light emitting devices 150 may be bonded to the second substrate. Since the insulating layers 140 surrounding the plurality of semiconductor light emitting devices 150 are isolated from each other, they do not have tension. Accordingly, in the bonding method of the semiconductor light emitting devices 150 according to the embodiment, tension is applied even between the plurality of semiconductor light emitting devices. It does not work, and there is a technical effect that can be stably fixed to the bonding area. As a result, there is a technical effect in that the transfer rate from the growth substrate to the transfer substrate is improved, and the regular assembly rate of the semiconductor light emitting device that proceeds thereafter is improved.

In addition, the semiconductor light emitting device and its bonding method according to the embodiment have technical effects of preventing particle issues and improving self-assembly transfer rate in a fluid by separating the first substrate after removing the insulating layer.

Subsequently, metal layers may be sequentially deposited on the plurality of semiconductor light emitting devices bonded to the second substrate as will be described later. For example, an ohmic layer heat treatment may be performed, and a magnetic layer may be formed.

Thereafter, the semiconductor light emitting device may be dispersed into a fluid and assembled into a display panel substrate to be used in a display device.

12 is a cross-sectional view of a semiconductor light emitting device 150 according to a second embodiment.

The semiconductor light emitting device 150 according to the second embodiment may be formed and transferred through the bonding method of the semiconductor light emitting device according to the first embodiment. For example, metal layers may be sequentially deposited on the plurality of semiconductor light emitting devices 150 bonded to the second substrate 111 as shown in FIG. 11 as will be described later. For example, an ohmic layer heat treatment may be performed, and a magnetic layer may be formed. Thereafter, the semiconductor light emitting device may be dispersed into a fluid and transferred to a display panel substrate to be used in a display device.

The semiconductor light emitting device according to the second embodiment includes a first conductivity-type semiconductor layer 153, an active layer 154 disposed under the first conductivity-type semiconductor layer 153, and a second conductivity-type semiconductor layer disposed under the active layer 154. A light emitting structure including a conductive semiconductor layer 155 is provided.

The first conductivity-type semiconductor layer 153, the active layer 154, and the second conductivity-type semiconductor layer 155 may be made of a compound semiconductor material. For example, the compound semiconductor material may be a Group 3-5 compound semiconductor material, a Group 2-6 compound material, or the like. For example, the compound semiconductor material may include GaN, InGaN, AlN, AlInN, AlGaN, AlInGaN, InP, GaAs, GaP, GaInP, and the like, but is not limited thereto.

For example, the first conductivity type semiconductor layer 153 may include a first conductivity type dopant, and the second conductivity type semiconductor layer 155 may include a second conductivity type dopant. For example, the first conductivity type dopant may be an n-type dopant, and the second conductivity type dopant may be a p-type dopant, but is not limited thereto.

The active layer 154 is a region that generates light, and can generate light having a specific wavelength band according to material properties of the compound semiconductor. That is, the wavelength band may be determined by the energy band gap of the compound semiconductor included in the active layer 154 . Accordingly, the semiconductor light emitting device 150 of the embodiment may generate UV light, blue light, green light, and red light according to the energy band gap of the compound semiconductor included in the active layer 154 . In addition, the active layer 154 may be MQW (Multi Quantum Wells) in which the active layer is formed in multiple layers.

A first electrode 151 for electrical connection of the semiconductor light emitting device may be disposed on the light emitting structure. The first electrode 151 may be formed in advance for each semiconductor light emitting device in a state of being disposed on the first substrate 110, but is not limited thereto (see FIG. 8A).

The semiconductor light emitting device 150 shown in FIG. 12 shows a state in which the insulating layer on the first electrode 151 is removed after being transferred to the panel substrate.

The first electrode 151 disposed on the upper surface of the semiconductor light emitting device may be formed of a light-transmitting electrode to improve light extraction efficiency, and the light-transmitting electrode may be indium tin oxide (ITO) or indium aluminum zinc oxide (IAZO). ), IZO (indium zinc oxide), IZTO (indium zinc tin oxide), IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), and IGZO (In-Ga ZnO).

In addition, a first metal layer 156 may be disposed below the light emitting structure. The first metal layer 156 may include, but is not limited to, AuGe and Au, or AuGe, Ni, Au, Ti, etc. capable of making Ohmic contact with the light emitting structure.

A process of forming the first metal layer 156 may be performed after removing a portion of the insulating layer 140 shown in FIG. 11 extending to the side of the semiconductor light emitting device 150 .

Subsequently, a magnetic layer 157 may be disposed under the first metal layer. The magnetic layer 157 may play a role of helping the bonding of the metal layer, and then, when the semiconductor light emitting device 150 is dispersed in a fluid, it may be positioned in an assembly hole of an assembly substrate by the assembly device 1100. It has magnetism so that The magnetic layer may include materials such as Ti and Ni, and may be formed by alternately depositing a single layer or multiple layers, but is not limited thereto.

Next, a second metal layer 158 may be disposed below the magnetic layer 157 . The second metal layer 158 may include materials such as Ti and Mo, and may be formed by alternately stacking a single layer or multiple layers, but is not limited thereto. The second metal layer 158 may serve as a bonding layer to electrically connect the semiconductor light emitting device 150 to other wires.

In addition, the second metal layer 158 extends from the 2-1st metal layer 158a disposed on the lower surface of the second metal layer and from the side surface of the 2-1st metal layer 158a to the side surface of the passivation layer 152. A 2-2 metal layer 158b may be included. The 2-2nd metal layer 158b has a technical effect of serving as a side electrode capable of making an electrical connection on the side of the semiconductor light emitting device.

On the other hand, in the case of a semiconductor light emitting device that emits blue or green color, it is possible to emit light without performing heat treatment. On the other hand, in the case of a semiconductor light emitting device emitting red color, the existing light efficiency is low due to the difference in materials used for the semiconductor epitaxial layer, and high-temperature heat treatment is required with the metal layer to form an ohmic contact. Accordingly, there is a need for a technology for improving the luminance of a semiconductor light emitting device emitting red color to the same level as that of a semiconductor light emitting device emitting blue or green color. Hereinafter, a solution to the above problem will be described through the manufacturing process of the second embodiment.

13 to 15 are process charts showing manufacturing processes of the semiconductor light emitting device according to the second embodiment.

Referring to FIG. 13 , a first metal layer 156 is formed under the light emitting structure. In particular, in the case of a semiconductor light emitting device emitting red color, the first metal layer 156 may include, but is not limited to, AuGe and Au, or AuGe, Ni, Au, Ti, etc. capable of Ohmic contact with the light emitting structure. The first metal layer 156 may be deposited by E-beam, but is not limited thereto.

In addition, a passivation layer 152 may be disposed on a side surface of the light emitting structure. When the semiconductor light emitting device is a semiconductor light emitting device that emits red color, long-term exposure of the semiconductor epitaxial layer may cause deformation of the chip. A side surface of the second conductive semiconductor layer 155 may be covered.

13 to 15 show a process in which the insulating layer on the first electrode 151 of the semiconductor light emitting device 150 is removed, but in the state in which the insulating layer is present on the first electrode 151, FIGS. The process of 15 may proceed.

Next, referring to FIG. 14 , after forming the first metal layer 156 , an annealing heat treatment may be performed on the semiconductor light emitting device 150 at about 350° C. to 400° C.

Referring to FIG. 15 , a magnetic layer 157 may be formed under the first metal layer 156 . The magnetic layer may include materials such as Ti and Ni, and may be formed by alternately depositing a single layer or multiple layers, but is not limited thereto.

Afterwards, as shown in FIG. 12 , a second metal layer 158 may be formed under the magnetic layer 157 . The second metal layer 158 may include materials such as Ti and Mo, and may be formed by alternately stacking a single layer or multiple layers, but is not limited thereto. The second metal layer 158 extends from the 2-1st metal layer 158a disposed on the lower surface of the magnetic layer 157 and the 2-1st metal layer 158a to the side surface of the passivation layer 152. It may be formed to include the 2-2nd metal layer 158b. The second metal layer 158 may be formed by a sputter process with good step coverage. The 2-1st metal layer 158a may function as a bonding layer, but is not limited thereto.

In detail, when the semiconductor light emitting device 150 emits red color, a first metal layer 156 for ohmic contact is formed using AuGe or Au material on the rear surface of the semiconductor light emitting device 150, and the magnetic layer 157 ), the second metal layer 158 may be deposited without removing the side passivation layer 152 through a sputtering process. Accordingly, there is a technical effect of increasing luminance by reducing resistance when wiring is connected.

Next, FIG. 16 is a cross-sectional view of a display device including a semiconductor light emitting device according to a third embodiment.

Referring to FIG. 16 , the display device including the semiconductor light emitting device according to the third embodiment includes an assembly board 210 and a first assembly line 221 disposed spaced apart from each other on the assembly board 210, and a second assembly board 210 . It includes an assembly wire 222 and a predetermined assembly hole 237H, and is disposed within the assembly partition 230 disposed on the first and second assembly wires 221 and 222 and the assembly hole 237H, A semiconductor light emitting device 150 electrically connected to the first assembly line 221 and the second assembly line 222 may be included.

In addition, the third embodiment may include an insulating layer 235 formed of a light-transmitting resin filling the assembly hole 237H and a panel wiring 225 electrically connected to the semiconductor light emitting device 150 . The panel wiring 225 is a light-transmitting member through which light is transmitted, and may include, for example, ITO.

When the semiconductor light emitting device 150 is self-assembled, different powers are applied as alternating current to the first assembly wiring 221 and the second assembly wiring 222 so that the semiconductor light emitting device 150 can be assembled in the assembly hole 237H. .

Meanwhile, after assembly, the 2-1st metal layer 158a disposed on the lower side and the 2-2nd metal layer 158b disposed on the side of the semiconductor light emitting device are electrically connected to the first and second assembly lines 221 and 222. can At this time, the same power is applied to the first and second assembly lines 221 and 222, and power is supplied to the semiconductor light emitting device 150 through the 2-2 metal layer 158b to use the assembly lines as pixel electrodes. There are possible technical effects.

Therefore, in the display device including the semiconductor light emitting device according to the third embodiment, the assembled wiring can be used not only for assembling the semiconductor light emitting device 150, but also as a pixel electrode that transmits an electrical signal to the semiconductor light emitting device 150. There is a technical effect.

In addition, the width of the lower part of the semiconductor light emitting device 150 may be greater than that of the upper part due to the 2-2 metal layer 158b disposed on the side surface. Since the metal layer is disposed on the lower part and the area of the lower part is larger than that of the upper part, therefore, when the semiconductor light emitting device dispersed in the fluid is self-assembled into the assembly hole of the panel substrate by the DEP force, the lower part is disposed to be in contact with the assembly wiring to emit semiconductor light. There is a technical effect of controlling the directionality of the upper and lower parts of the device.

The semiconductor light emitting device and its bonding method according to the embodiment and the display device including the same have a technical effect of preventing the semiconductor light emitting device from being separated from the transfer substrate.

The semiconductor light emitting device according to the embodiment, the bonding method thereof, and the display device including the same have a technical effect of improving the assembly rate of the semiconductor light emitting device during self-assembly.

A semiconductor light emitting device and a bonding method thereof according to an embodiment and a display device including the same have technical effects capable of preventing tension between semiconductor light emitting devices during a transfer process.

A semiconductor light emitting device and a bonding method thereof according to an embodiment and a display device including the same have technical effects capable of electrical connection to the side of the semiconductor light emitting device.

A semiconductor light emitting device according to an embodiment, a bonding method thereof, and a display device including the same have technical effects capable of controlling upward and downward directions of the semiconductor light emitting device during self-assembly.

A semiconductor light emitting device according to an embodiment, a bonding method thereof, and a display device including the same have technical effects capable of improving the luminance of a semiconductor light emitting device emitting red color to be equal to the luminance of a semiconductor light emitting device emitting blue or green color. there is

The above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the embodiments should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent range of the embodiments are included in the scope of the embodiments.

20: drive circuit
21: data driving unit
22: timing control unit
100: display device
PX: pixels
PX1: first sub-pixel
PX2: second sub-pixel
PX3: third sub-pixel
Cst: capacitor
DT: drive transistor
A1: first panel area
200: substrate
201, 202: assembly wiring
211a: first insulating layer
211b: second insulating layer
206: third insulating layer
10, 110: first substrate
11, 111: second substrate
12, 112: bonding area
40, 140: insulating layer
150: semiconductor light emitting element
151: first electrode
152: passivation layer
153: first conductivity type semiconductor layer
154: active layer
155: second conductivity type semiconductor layer
156: first metal layer
157: magnetic layer
158: second metal layer
158a: 2-1st metal layer
158b: 2-2nd metal layer
160: PR mask
210: assembly board:
221: first assembly wiring
222: second assembly wiring
225: panel wiring
230: bulkhead
235: insulating layer
237H: assembly hole

Claims (10)

Forming a plurality of semiconductor light emitting devices on a first substrate;
forming an insulating layer on the first substrate and the plurality of semiconductor light emitting devices;
etching an insulating layer formed between the plurality of semiconductor light emitting elements among the insulating layers;
pressing the first substrate and the second substrate so that the plurality of semiconductor light emitting devices correspond to a second substrate having a bonding region; and
A method of bonding a semiconductor light emitting device for a display pixel, comprising: removing the first substrate. According to claim 1,
The etching of the insulating layer comprises forming a mask pattern on the insulating layer so as not to overlap with the plurality of semiconductor light emitting elements. According to claim 1,
In the etching of the insulating layer, at least one of the insulating layers formed between the plurality of semiconductor light emitting elements is not etched. According to claim 1,
A method of bonding a semiconductor light emitting device for a display pixel, characterized in that a photo active compound (PAC) is applied to the bonding area. a light emitting structure including a first semiconductor layer, an active layer disposed below the first semiconductor layer, and a second semiconductor layer disposed below the active layer;
a first metal layer disposed below the second semiconductor layer and in contact with the second semiconductor layer;
a magnetic layer disposed under the first metal layer; and
A second metal layer disposed under the magnetic layer; includes,
The second metal layer is a semiconductor light emitting device for a display pixel, characterized in that disposed extending to the side surface of the light emitting structure. According to claim 5,
A semiconductor light emitting device for a display pixel, characterized in that the width of the second metal layer is greater than the width of the light emitting structure. According to claim 5,
The second metal layer includes a 2-1 metal layer disposed on a lower surface of the magnetic layer and a 2-2 metal layer disposed on a side surface of the magnetic layer,
The 2-2nd metal layer is a semiconductor light emitting device for a display pixel, characterized in that in contact with the side surface of the first metal layer. Board;
assembly wiring disposed on the board;
a barrier rib disposed on the assembled wiring and having an opening; and
A display device comprising a semiconductor light emitting element comprising: a semiconductor light emitting element for a display pixel according to any one of claims 5 to 7 disposed within the barrier rib. According to claim 8,
The second metal layer of claim 7 is characterized in that electrically connected to the assembled wiring, a display device including a semiconductor light emitting element. According to claim 8,
A display device including a semiconductor light emitting element, comprising a panel wiring electrically connected to an upper surface of the semiconductor light emitting element.

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