LED display device and manufacturing method thereof

Abstract

According to an embodiment of the present specification, an LED display apparatus is provided, which simplifies a manufacturing process by including at least one light emitting diode arranged integrally with a common electrode layer. An LED display apparatus can be provided in which a common electrode layer, which is an n-type semiconductor, is grown on a first substrate, which is a semiconductor substrate, a first driving device is then formed, and a second driving device grown on another substrate is transferred onto the common electrode layer, thereby implementing a pixel that emits light of different wavelengths, and simplifying a manufacturing process thereof. The first substrate is bonded to a second substrate facing the first substrate and having a plurality of pixel driving devices, thereby forming an LED display apparatus. As such, an LED display apparatus can be provided, which has improved reliability and at least one unit pixel consisting of a plurality of pixels by using at least one light emitting diode arranged integrally with a common electrode layer and at least two separate light emitting diodes.

Description

TECHNICAL FIELD

[0001] The present application relates to an LED (Light Emitting Diode) display apparatus and a manufacturing method thereof, and more particularly to an LED display apparatus and a manufacturing method thereof that provide a minimization of a series of processes of growing LEDs on a semiconductor substrate and then transferring the LEDs to a display substrate. BACKGROUND

[0002] Display apparatuses are widely used as display screens of televisions, monitors, tablet computers, smart phones, portable display apparatuses, and portable information devices, etc.

[0003] Display apparatuses can be divided into reflective display apparatuses and light emitting display apparatuses, and in the reflective display apparatuses, information is displayed by reflecting natural light or light from an external lighting device of the display apparatus inside the display apparatus; a light emitting device or a light source is built in the display apparatus, and then light from the built-in light emitting device or the built-in light source is used to display information.

[0004] A light emitting device for emitting light of various wavelengths can be used as the built-in light emitting device, and a light emitting device for emitting white light or blue light and a color filter for changing the wavelength of the emitted light can be used.

[0005] In order to display an image in the display apparatus, a plurality of light emitting devices are disposed on a display substrate, and a driving device for applying a driving signal and a driving current is disposed on the display substrate to control each light emitting device to emit light individually, so that the plurality of light emitting devices disposed on the substrate are analyzed according to the arrangement of information to be displayed and displayed on the substrate.

[0006] The display apparatus includes a plurality of pixels and a driving device, for example, a thin film transistor as a switching device is disposed at each pixel, and an image is displayed in each pixel by driving the thin film transistor.

[0007] A representative display apparatus using a thin film transistor includes a liquid crystal display apparatus and an organic light emitting display apparatus. Since the liquid crystal display apparatus is not a self-light emitting device, a backlight unit that emits light to the liquid crystal display apparatus is required.

[0008] Due to the additional backlight unit, the thickness of the liquid crystal display increases. In addition, there is a limitation in implementing various types of display apparatuses such as a flexible or circular shape, and the brightness and response speed can be reduced.

[0009] On the other hand, a display apparatus having a self-light emitting device can implement a thin, flexible, and foldable display apparatus compared to a display apparatus including a light source.

[0010] Display apparatuses including self-emissive devices include organic light emitting display apparatuses using organic materials as light emitting devices and micro LED display apparatuses using micro light emitting diodes as light emitting devices. Since self-emissive display apparatuses such as organic light emitting display apparatuses or micro LED display apparatuses do not require a separate light source, the self-emissive display apparatuses can be used as thinner or various types of display apparatuses.

[0011] However, although the organic light emitting display apparatus has an advantage of not requiring a separate light source, there is a problem of generating a defective pixel due to moisture and oxygen. Therefore, various techniques for minimizing the penetration of oxygen and moisture are additionally required in the organic light emitting display apparatus.

[0012] To solve this problem, display apparatuses using micro light emitting diodes (micro LEDs) of a small size as light emitting devices are being researched and developed. Such light emitting display apparatuses have attracted attention as next-generation display apparatuses due to high image quality and high reliability.

[0013] Micro light emitting diodes of a small size are semiconductor light emitting devices that emit light when a current is supplied to a semiconductor, and are widely used for lamps, TVs, and various display apparatuses. The micro light emitting diode is composed of an n-type semiconductor layer, a p-type semiconductor layer, and an active layer therebetween. When a current is supplied, electrons are generated from the n-type semiconductor layer, holes are generated from the p-type semiconductor layer, and then the electrons and holes combine in the active layer to emit light.

[0014] There are several technical requirements for implementing a light emitting display apparatus in which a micro light emitting diode is used as a light emitting device of a unit pixel. First, the micro light emitting diode is crystallized on a semiconductor wafer substrate such as sapphire or silicon (Si), and a plurality of crystallized LED chips are moved to a substrate having a driving device. In this case, a complex transfer process of positioning the micro light emitting diode at an accurate position corresponding to each pixel is required.

[0015] The micro light emitting diode uses an inorganic material, but the inorganic material must be formed by crystallization, and when an inorganic material such as GaN is used, the inorganic material must be crystallized on a substrate that can induce crystallization. The substrate capable of effectively inducing crystallization of the inorganic material is a semiconductor substrate.

[0016] The process of crystallizing the micro light emitting diode is also referred to as epitaxy, epitaxial growth, or an epitaxial process. The epitaxial process is a process of growing a crystal in a specific direction on the surface of a crystal. In order to form a micro light emitting diode, a GaN-based compound semiconductor must be stacked in the form of a pn junction diode on a substrate, and each layer is grown by inheriting the crystallinity of the lower layer.

[0017] At this time, defects in the crystal act as non-radiation centers in the electron-hole recombination process. Accordingly, in a micro light emitting diode using a photon, the crystallinity of the crystal forming each layer has a decisive influence on the device efficiency.

[0018] A sapphire substrate is mainly used as a substrate for a micro light emitting diode, and recently, GaN is also used as a substrate for a micro LED.

[0019] Compared to simple lighting or a light source for backlighting, a large number of LEDs are used in display devices, however, there is a problem in that the manufacturing cost of a display device using a large number of LEDs increases due to the high cost of a semiconductor substrate.

[0020] In addition, although a step of transferring a micro light emitting diode formed on a semiconductor substrate to a substrate of a display device is required, it is difficult to separate the micro light emitting diode formed on the semiconductor substrate in this process. In addition, there are many difficulties and problems in accurately transferring the separated micro light emitting diode into a desired position.

[0021] As a method of transferring a micro light emitting diode to a substrate of a display device, various transfer methods can be used, such as a method of using a transfer substrate using a polymer material (for example, PDMS), a transfer method using electromagnetism or electrostaticity, and a method of physically picking up and moving one element at a time, etc.

[0022] The transfer process is related to the productivity of the display device manufacturing process. For mass production, it is inefficient to move micro light emitting diodes one by one.

[0023] Accordingly, a complex transfer process or technology of separating a plurality of micro light emitting diodes from a semiconductor substrate and transferring the separated micro LEDs to an accurate position on a pad electrode connected to a driving device and a power supply electrode of a display device using a transfer substrate using a polymer material becomes necessary.

[0024] During the transfer process or during a subsequent process after the transfer process, defects such as the micro light emitting diode being transferred being flipped by external conditions such as vibration or heat when the micro light emitting diode is moved or transferred can occur. In addition, there are many difficulties in detecting and repairing such defects.

[0025] A general transfer process (e.g., a transfer process of micro light emitting diodes) will be described as follows. Micro light emitting diodes are formed on a semiconductor substrate, and electrodes are formed on the semiconductor layer to complete individual micro light emitting diodes. Thereafter, the semiconductor substrate and a PDMS substrate (hereinafter, referred to as a transfer substrate) are brought into contact with each other to move the micro light emitting diodes to the transfer substrate. Since the micro light emitting diodes must be transferred from the semiconductor substrate to the transfer substrate taking into account the pixel distance of the display device, protrusions for accommodating the micro light emitting diodes are provided on the transfer substrate.

[0026] A laser is irradiated to the micro light emitting diodes through the back surface of the semiconductor substrate to separate the micro light emitting diodes from the semiconductor substrate. At this time, when the laser is irradiated to separate the micro light emitting diodes from the semiconductor substrate, the GaN material of the semiconductor substrate is physically rapidly expanded due to the high energy concentration of the laser, which can cause an impact on the GaN material. (This is referred to as a primary transfer.)

[0027] Thereafter, the micro light emitting diodes transferred to the transfer substrate are transferred again to the substrate of the display device. At this time, a passivation layer for insulating / protecting the thin film transistors is formed on the substrate having the thin film transistors, and then an adhesive layer is formed on the passivation layer.

[0028] When the transfer substrate is brought into contact with the substrate of the display device and pressure is applied to the substrate of the display device, the micro light emitting diodes transferred to the transfer substrate are transferred to the substrate of the display device through the adhesive layer formed on the passivation layer.

[0029] At this time, by making the adhesive force between the transfer substrate and the micro light emitting diodes smaller than the adhesive force between the substrate of the display device and the micro light emitting diodes, the micro light emitting diodes on the transfer substrate are smoothly transferred to the substrate of the display device. (This is referred to as a secondary transfer)

[0030] The semiconductor substrate and the substrate of the display device are substantially different in size. Typically, the substrate of the display device is larger than the semiconductor substrate. Due to the difference in area and size, if the primary transfer and the secondary transfer described above are performed for each of a plurality of regions of the substrate of the display device, the micro light emitting diodes can be transferred to each of a plurality of pixels of the display device.

[0031] The micro light emitting diodes formed on the semiconductor substrate can include red micro light emitting diodes, blue micro light emitting diodes, and green micro light emitting diodes. The micro light emitting diodes can further include white micro light emitting diodes. Since the micro light emitting diodes emitting light of different wavelengths are transferred to the pixels of the display device, it is possible to further increase the number of primary transfers and secondary transfers.

[0032] Since the micro light emitting diode is composed of a compound semiconductor such as GaN, a high current can be injected due to the characteristics of inorganic materials, thereby achieving high brightness. In addition, since environmental influences such as heat, moisture, and oxygen are low, the micro light emitting diode has high reliability. In addition, since the micro light emitting diode has an internal quantum efficiency of 90% which is higher than that of an organic light emitting display apparatus, a high-brightness image can be displayed and a display apparatus with low power consumption can be implemented.

[0033] In addition, since the micro LED display apparatus uses inorganic materials, the influence of oxygen and moisture is very small. Therefore, since a separate encapsulation film or encapsulation substrate is not required to minimize the penetration of oxygen and moisture, a non-display area of the display apparatus, which is an edge area caused by the encapsulation film or encapsulation substrate, can be minimized.

[0034] However, in the primary transfer and secondary transfer processes of the micro LED display apparatus, many processes such as a process of arranging the micro light emitting diode and a process of connecting electrodes for providing a driving signal and a current to the micro light emitting diode are required, and the precision of these processes must be high.

[0035] Therefore, in a display apparatus using a micro light emitting diode as a light emitting device of a pixel, research on simplifying the transfer process of the micro light emitting diode has been actively conducted. SUMMARY

[0036] TECHNICAL PROBLEM

[0037] In an LED display apparatus in which a micro light emitting diode is used as a light emitting device, particularly in an LED display apparatus in which an inorganic-based micro-sized micro LED is used as a light emitting device, since an encapsulation layer or an encapsulation substrate is not required in a display apparatus using a micro light emitting diode as described above, a bezel area can be minimized, and a modular display apparatus using a plurality of display apparatuses can be easily manufactured. However, there is a problem in that a defect can occur in a process of growing a micro light emitting diode on a separate substrate and transferring the micro light emitting diode to a display apparatus, and another defect can occur in a process of connecting an electrode to the micro light emitting diode. Therefore, the inventors of the present application invented an LED display apparatus and a manufacturing method thereof capable of reducing defects and improving process reliability by simplifying a process of transferring a micro light emitting diode.

[0038] An object of an embodiment of the present specification is to provide an LED display apparatus and a manufacturing method thereof capable of minimizing transfer process errors by simplifying steps of transferring a micro light emitting diode.

[0039] Another object of the present application is to provide an LED display apparatus and a manufacturing method thereof, which can reduce connection errors of electrodes for providing current to micro light emitting diodes.

[0040] The problems to be solved by the embodiments of the present application are not limited to the above problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

[0041] Technical Solution

[0042] An LED display apparatus according to the embodiments of the present specification is provided. A first substrate having a common electrode layer and a second substrate having a first pixel driving device and a second pixel driving device are joined to each other to face each other. On the common electrode layer, a first light emitting device and a second light emitting device including LEDs as light emitting devices are disposed as at least two light emitting devices. The first light emitting device includes a first n-type semiconductor layer, a first active layer, and a first p-type semiconductor layer, and the second light emitting device includes a second n-type semiconductor layer, a second active layer, and a second p-type semiconductor layer. In the above structure, the first p-type semiconductor layer and the first pixel driving device are electrically connected by a first connection electrode, and the second p-type semiconductor layer and the second pixel driving device are electrically connected by a second connection electrode. The LED display apparatus can further include a third light emitting device and a third pixel driving device, and can be disposed similarly to the above structure. The common electrode layer and the first n-type semiconductor layer of the first light emitting device are respectively formed of substantially the same material to have a direct connection relationship as a whole structure rather than a joining structure, and the common electrode layer and the second n-type semiconductor layer are electrically connected by a third connection electrode. In this electrical connection relationship, by using the first light emitting device arranged integrally with the common electrode layer, a process of transferring micro light emitting diodes can be minimized, and process stability can be improved.

[0043] A manufacturing method of an LED display apparatus using micro light emitting diodes as light emitting devices according to an embodiment of the present specification is provided. A first substrate is a substrate such as sapphire on which a semiconductor can be grown, and a common electrode layer and a first n-type semiconductor layer are continuously grown on the first substrate. Thereafter, a first active layer and a first p-type semiconductor layer are grown and etched, leaving the common electrode layer on the first substrate to form a first light emitting device. Further, a first pixel driving device and a second pixel driving device are provided as at least two pixel driving devices on a second substrate. A second light emitting device is provided adjacent to the first light emitting device on the common electrode layer, the second light emitting device being a separately grown micro light emitting diode including a second n-type semiconductor layer, a second active layer, and a second p-type semiconductor layer. The first substrate and the second substrate are bonded to each other, and a first connection electrode and a second connection electrode are provided before bonding to connect the first p-type semiconductor layer and the second p-type semiconductor layer to the first pixel driving device and the second pixel driving device, respectively, whereby an LED display apparatus can be manufactured. As described above, by the process of connecting the first light emitting device grown on the first substrate and the second light emitting device transferred onto the common electrode layer to the pixel driving device, the manufacturing process is simplified, and process stability of the LED display apparatus using micro light emitting diodes as light emitting devices can be improved.

[0044] Effects of Invention

[0045] According to an embodiment of the present specification, by using at least one micro light emitting diode integrally formed with a common electrode layer as a light emitting device, there is an effect of reducing the process of transferring the micro light emitting diode, thereby minimizing process defects.

[0046] In addition, by using a common electrode layer made of substantially the same material as the semiconductor layer of the micro light emitting diode, the number of connection electrodes additionally connecting the micro light emitting diode and the common electrode layer can be reduced, thereby simplifying the process.

[0047] Effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

[0048] Since the contents of the invention described in the above-described problems to be solved, means for solving the problems, and effects do not specify the basic features of the claims, the scope of the claims is not limited by the matters described in the contents of the invention. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a diagram showing a schematic configuration of an LED display apparatus 100 according to an embodiment of the present specification.

[0050] Figure 2is a schematic diagram for explaining a circuit structure of a pixel arranged in the LED display apparatus 100 according to an embodiment of the present specification.

[0051] Figure 3 is a schematic cross-sectional view for explaining a configuration of a pixel of the LED display apparatus 100 according to an embodiment of the present specification.

[0052] Figure 4 is a schematic flowchart for explaining a method of manufacturing the LED display apparatus 100 according to an embodiment of the present specification. DETAILED DESCRIPTION

[0053] Hereinafter, exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be understood that the present application is not limited to the following embodiments and can be implemented in various ways, and the embodiments are given to provide a complete disclosure of the present application and to provide those skilled in the art with a thorough understanding of the present application. The scope of the present application is only limited by the appended claims and their equivalents.

[0054] In the drawings, the shape, size, ratio, angle, and number of components are provided only for illustration and do not limit the scope of the present application. Throughout the specification, the same components will be denoted by the same reference numerals. Detailed descriptions of known functions and configurations that can unnecessarily obscure the subject matter of the present application will be omitted. The words "comprise", "contain" and / or "include" when used in this specification specify the presence of the stated features, integers, steps, operations, elements, components and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0055] Unless otherwise stated, error margins are considered in the analysis of components.

[0056] In the description of spatial relative terms, for example, when an element is referred to as being "on", "above", "below", or "next to" another element or layer, the element can be directly on, above, below, or next to the other element or layer, or an intermediate element can exist, unless otherwise stated.

[0057] In describing operations with temporal terms, such as "after", "subsequently", "before", or "before", the operations can be performed continuously or discontinuously, unless otherwise stated.

[0058] In the description of signal flow relationships, for example, even in the case of "a signal is transmitted from node A to node B", unless "directly" or "directly" is used, a case in which the signal is transmitted from node A to node B via another node can be included.

[0059] Although the terms "first", "second", "A", "B", and the like can be used herein to describe various elements, components, and / or regions, these elements, components, and / or regions should not be limited by these terms. These terms are only used to distinguish one element, component, or region from another element, component, or region. Therefore, the "first" element or component discussed below can also be referred to as the "second" element or component, or the "second" element or component can also be referred to as the "first" element or component, without departing from the scope of the present application.

[0060] Features of various embodiments of the present application can be partially or wholly coupled or combined with each other to achieve various technical associations and operations, and can be implemented independently of or in association with each other.

[0061] Hereinafter, various embodiments will be described with reference to the accompanying drawings.

[0062] Referring to Figure 1 , the LED display apparatus 100 according to an embodiment of the present application can include a display panel 101 in which a plurality of sub-pixels SP including micro light emitting diodes μLEDs are arranged, a gate driving circuit 120 that drives the display panel 101, a data driving circuit 130, and a controller 140.

[0063] In the display panel 101, a plurality of gate lines GL and a plurality of data lines DL are provided, and the sub-pixels SP are provided in regions where the gate lines GL and the data lines DL cross. Each of these sub-pixels SP can include a micro light emitting diode μLED, and one pixel P can include two or more sub-pixels SP.

[0064] The gate driving circuit 120 is controlled by the controller 140, and a scan signal is sequentially output to the plurality of gate lines GL in the display panel 101 to control the driving timing of the plurality of sub-pixels.

[0065] The gate driving circuit 120 can include one or more gate driver integrated circuits (GDICs), and can be located on only one side or both sides of the display panel 101 according to the driving method. Alternatively, the gate driving circuit 120 can be located on the rear surface of the display panel 101.

[0066] The data driving circuit 130 receives image data from the controller 140 and converts the image data into an analog data voltage. Further, the data voltage is output to each data line DL according to the timing at which a scan signal is applied through the gate line GL, so that each sub-pixel SP displays luminance according to the image data.

[0067] The data driving circuit 130 can include one or more source driver integrated circuits SDIC.

[0068] The controller 140 provides various signals to the gate driving circuit 120 and the data driving circuit 130 and controls the operation of the gate driving circuit 120 and the data driving circuit 130.

[0069] The controller 140 causes the gate driving circuit 120 to output a scan signal according to the timing implemented in each frame and converts image data received externally to match a data signal format used by the data driving circuit 130 and outputs the converted image data to the data driving circuit 130.

[0070] Various timing signals including image data, a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), an input data enable signal (DE, Data Enable), and a clock signal (CLK) are applied to the controller 140 from the outside (e.g., a host system).

[0071] The controller 140 can generate various control signals using the various timing signals received from the outside and output the various control signals to the gate driving circuit 120 and the data driving circuit 130.

[0072] For example, the controller 140 outputs various gate control signals including a gate start pulse (GSP), a gate shift clock (GSC), and a gate output enable signal (GOE), etc., in order to control the gate driving circuit 120.

[0073] Here, the gate start pulse (GSP) controls the driving start timing of one or more gate driver integrated circuits of the gate driving circuit 120. The gate shift clock (GSC), which is a clock signal commonly input to the one or more gate driver integrated circuits, controls the shift timing of the scan signal. The gate output enable signal (GOE) specifies timing information of the one or more gate driver integrated circuits.

[0074] Further, the controller 140 outputs various data control signals including a source start pulse (SSP), a source sampling clock (SSC), and a source output enable (SOE), etc., in order to control the data driving circuit 130.

[0075] Here, a source start pulse (SSP) controls data sampling start timing of one or more source driver integrated circuits of the data driving circuit 130. A source sampling clock (SSC) is a clock signal that controls sampling timing of data in each of the source driver integrated circuits. A source output enable signal (SOE) controls output timing of the data driving circuit 130.

[0076] The LED display apparatus 100 can further include a power management integrated circuit for providing various voltages or currents to the display panel 101, the gate driving circuit 120, and the data driving circuit 130 and controlling the voltages or currents.

[0077] In addition to the gate line GL and the data line DL, voltage lines for providing various signals or voltages can be disposed in the display panel 101, and a micro light emitting diode μLED and a transistor for driving the micro light emitting diode μLED can be disposed in each sub-pixel SP.

[0078] Figure 2 An example of a circuit structure of a sub-pixel SP of the LED display apparatus 100 according to an embodiment of the present application is illustrated, in which one pixel P includes three sub-pixels SP.

[0079] Referring to Figure 2 , in addition to the gate line GL for providing a scan signal and the data line DL for providing a data voltage Vdata, a driving voltage line DVL for providing a driving voltage Vdd and a common voltage line CVL for providing a common voltage Vcom can be disposed in the display panel 101.

[0080] Further, sub-pixels SP displaying red (R), green (G), and blue (B) are disposed in an intersection region of the gate line GL and the data line DL.

[0081] In each sub-pixel SP, a micro light emitting diode μLED, one or more transistors for driving the micro light emitting diode μLED, and a capacitor can be disposed.

[0082] For example, a micro light emitting diode μLED for emitting red light, a first driving transistor DRT1 for driving the micro light emitting diode μLED, and a first switching transistor SWT1 for controlling driving timing of the first driving transistor DRT1 can be disposed in a red sub-pixel SP (R) at an intersection region of a first data line DL1 and a gate line GL.

[0083] Here, the first driving transistor DRT1 can be connected to an anode of the micro light emitting diode μLED as Figure 2 illustred, but can also be connected to a cathode of the micro light emitting diode μLED.

[0084] Also, a storage capacitor for maintaining the data voltage Vdata within one image frame can be further provided between the gate and the source (or the drain) of the first driving transistor DRT1.

[0085] When a scan signal Scan is applied through the gate line GL, the first switching transistor SWT1 is turned on, and then a first data voltage Vdata1 provided through the first data line DL is applied to the gate of the first driving transistor DRT1. Further, a driving voltage Vdd is applied to the anode of the micro light emitting diode μLED according to the first data voltage Vdata1, and a common voltage Vcom is applied to the cathode of the micro light emitting diode μLED. The micro light emitting diode (μLED) emits light according to a voltage difference applied to the anode and the cathode to represent brightness.

[0086] The micro light emitting diodes μLED provided in the green sub-pixel SP(G) and the blue sub-pixel SP(B) are driven in the same manner to display green (G) and blue (B) in the corresponding sub-pixels SP.

[0087] Further, each of the micro light emitting diodes μLED provided in the red sub-pixel SP(R), the green sub-pixel SP(G), and the blue sub-pixel SP(B) is grown on a separate wafer substrate corresponding thereto, and then the grown micro light emitting diodes μLED are transferred and positioned on the display panel 101.

[0088] Hereinafter, a configuration of a micro light emitting diode μLED arranged integrally with a common electrode layer according to an embodiment of the present specification will be described in detail, in which the number of micro light emitting diodes μLED grown on separate wafer substrates is minimized.

[0089] Figure 3 is a schematic cross-sectional view for explaining a structure of a pixel of the LED display apparatus 100 according to an embodiment of the present specification. Referring to Figure 3 , the display panel 101 of the LED display apparatus 100 can include a first substrate 110a and a second substrate 110b.

[0090] The first substrate 110a includes a first light emitting device 160 and a second light emitting device 170 as micro light emitting diodes μLED. The first light emitting device 160 is arranged integrally with a common electrode layer 160a, and one unit pixel P can include at least one first light emitting device 160. Further, the second light emitting device 170 is a micro light emitting diode grown on a separate semiconductor substrate, and then transferred onto the common electrode layer 160a through a transfer process, and one unit pixel P can include at least one second light emitting device 170.

[0091] The second substrate 110b facing the first substrate 110a on which the micro light emitting diodes are provided includes a first pixel driving device 150a and a second pixel driving device 150b as driving transistors.

[0092] The first substrate 110a and the second substrate 110b can be separately manufactured and bonded to each other, and an adhesive layer of, for example, resin can be filled between the first substrate 110a and the second substrate 110b to bond the first substrate 110a and the second substrate 110b.

[0093] Hereinafter, each structure provided on the first substrate 110a and the second substrate 110b will be described in more detail.

[0094] The common electrode layer 160a is provided on the first substrate 110a. The first substrate 110a is a substrate of, for example, sapphire on which a semiconductor layer can be substantially grown, and can further include a buffer layer for growing a semiconductor layer.

[0095] Further, the buffer layer is a low-temperature buffer layer that can be formed of a material such as AlN or low-temperature GaN. The common electrode layer 160a on the first substrate 110a is an n-type semiconductor layer in which silicon (Si) is doped. As described above, the n-type semiconductor layer in which silicon is doped can form the common electrode layer 160a as a conductor.

[0096] The first light emitting device 160 is provided on the common electrode layer 160a. The first light emitting device 160 has a structure in which a GaN-based compound semiconductor is grown in the form of a pn junction diode, each layer is a layer grown by inheriting the crystallinity of the underlying layer, and the first light emitting device 160 includes a first n-type semiconductor layer 161, a first active layer 162, a first p-type semiconductor layer 163, and a first device electrode 164a on the first p-type semiconductor layer 163.

[0097] As described above, since the first light emitting device 160 is sequentially grown (epitaxially grown) from the common electrode layer 160a on the first substrate 110a, a separate transfer process to the common electrode layer 160a is not required.

[0098] Further, the second light emitting device 170 is provided on the common electrode layer 160a. The unit pixel P is composed of at least one sub-pixel SP, and each sub-pixel SP is configured to emit light of a different wavelength.

[0099] The second light emitting device 170 is a light emitting device that emits light of a wavelength different from the wavelength of light emitted by the first light emitting device 160, and is grown on a separate semiconductor growth substrate (for example, a semiconductor substrate) and then provided on the common electrode layer 160a by a transfer process.

[0100] However, in another embodiment of the present application, a method of configuring a unit pixel P using only a plurality of first light emitting devices 160 can be used without the second light emitting device 170 grown on a separate semiconductor growth substrate, and in this case, a color conversion layer corresponding to each of the first light emitting devices 160 can also be included. If a light emitting device grown on a separate semiconductor growth substrate is not used, a transfer process for transferring a light emitting device can not be needed at all.

[0101] The first light emitting device 160 can be a light emitting device grown according to a lattice constant of the first substrate 110a based on a sapphire substrate, and the second light emitting device 170 can be a light emitting device grown on a separate semiconductor growth substrate based on a gallium arsenide (GaAs) substrate.

[0102] The second light emitting device 170 includes a second n-type semiconductor layer 171, a second active layer 172, a second p-type semiconductor layer 173, and a second device electrode 174a on the second p-type semiconductor layer 173, a third device electrode 175a can be formed on the first n-type semiconductor layer 171 to electrically connect the second light emitting device 170 to the common electrode layer 160a, and the second light emitting device 170 can be fixed on the common electrode layer 160a by an adhesive layer adh.

[0103] The second light emitting device 170 is electrically connected to the common electrode layer 160a by a third connection electrode 175, and the third connection electrode 175 can include a third device electrode 175a disposed on the first n-type semiconductor layer 171 and a third bonding electrode 175b including a conductive ball.

[0104] Further, the common electrode layer 160a can further include a light guide 180 to prevent color mixing of light emitted from each of the first light emitting device 160 and the second light emitting device 170. The light guide 180 can be formed of an opaque conductive metal or the like for reflecting light, and can be formed by etching a surface of the common electrode layer 160a and then disposing the above metal in the etched surface.

[0105] In addition, a black matrix BM can be disposed between the first light emitting device 160 and the second light emitting device 170 to further prevent color mixing.

[0106] In the above configuration, although each of the first n-type semiconductor layer 161, the second n-type semiconductor layer 171, the first p-type semiconductor layer 163, and the second p-type semiconductor layer 173 is formed with an n-type semiconductor layer and a p-type semiconductor layer, these layers can be formed with a p-type semiconductor layer and an n-type semiconductor layer.

[0107] A first p-type semiconductor layer 163 and a second p-type semiconductor layer 173 are provided on the first active layer 162 and the second active layer 172, respectively, to supply holes to the first active layer 162 and the second active layer 172, respectively. The first p-type semiconductor layer 163 and the second p-type semiconductor layer 173 according to the embodiment of the present specification can be formed of a p-GaN-based semiconductor material, and the p-GaN-based semiconductor material includes GaN and AlGaN, InGaN, or AlInGaN. Here, as an impurity for doping the first p-type semiconductor layer 163 and the second p-type semiconductor layer 173, Mg, Zn, Be, or the like can be used.

[0108] A first n-type semiconductor layer 161 and a second n-type semiconductor layer 171 are provided on the first active layer 162 and the second active layer 172, respectively, to supply electrons to the first active layer 162 and the second active layer 172, respectively. The first n-type semiconductor layer 161 and the second n-type semiconductor layer 171 according to the embodiment of the present specification can be formed of an n-GaN-based semiconductor material, and the n-GaN-based semiconductor material includes GaN and AlGaN, InGaN, or AlInGaN. Here, as an impurity for doping the first n-type semiconductor layer 161 and the second n-type semiconductor layer 171, Si, Ge, Se, Te, C, or the like can be used.

[0109] The first active layer 162 and the second active layer 172 are provided on the first n-type semiconductor layer 161 and the second n-type semiconductor layer 171. The light emitting layer of the first active layer 162 and the second active layer 172 includes a multiple quantum well (MQW) structure having a well layer and a barrier layer having a band gap higher than that of the well layer. The first active layer 162 and the second active layer 172 according to the embodiment of the present invention can include a multiple quantum well structure, for example, InGaN / GaN.

[0110] Each of the first device electrode 164a, the second device electrode 174a, and the third device electrode 175a according to the embodiment of the present invention can be made of a metal such as Au, W, Pt, Si, Ir, Ag, Cu, Ni, Ti, or Cr, and an alloy including one or more of these metals, but is not limited thereto.

[0111] As described above, according to the exemplary embodiment of the present specification, the second substrate 110b includes the first pixel driving device 150a and the second pixel driving device 150b as driving transistors.

[0112] Each of the first pixel driving device 150a and the second pixel driving device 150b includes an active layer 151, a gate 152, a source 153, and a drain 154. Each of the first pixel driving device 150a and the second pixel driving device 150b according to the embodiment of the present specification is a thin film transistor using a polysilicon material as the active layer 151, that is, a low temperature polysilicon (LTPS) thin film transistor using low temperature polysilicon.

[0113] Since the polysilicon material has high mobility, energy consumption is low and reliability is excellent. The active layer 151 of the LTPS thin film transistor (hereinafter, thin film transistor, first pixel driving device 150a, and second pixel driving device 150b) includes a channel region 151a in which a channel is formed when the thin film transistor is driven, and a source region 151b and a drain region 151c on both sides of the channel region 151a.

[0114] The channel region 151a, the source region 151b, and the drain region 151c are defined by ion doping (impurity doping). A gate insulating layer 111 is disposed on the active layer 151, and the gate insulating layer 111 can be composed of a single layer such as silicon nitride (SiNx) or silicon oxide (SiOx) or a plurality of layers including silicon nitride (SiNx) and silicon oxide (SiOx).

[0115] On the gate insulating layer 111, the gate 152 is disposed to overlap the channel region 151a of the active layer 151. The gate 152 can be formed in a single layer structure made of any one of aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, molybdenum (Mo), and molybdenum titanium alloy (MoTi) having low resistance characteristics, the gate 152 can be formed in a double layer structure or a triple layer structure composed of two or more layers.

[0116] Further, the first insulating layer 112 is disposed on the gate 152, and since the first insulating layer 112 is made of silicon nitride (SiNx), hydrogen contained in the first insulating layer 112 made of silicon nitride (SiNx) diffuses into the active layer 151 during a hydrogenation process for stabilizing the active layer 151.

[0117] A passivation layer 113 is disposed on the first insulating layer 112, and the passivation layer 113 can be made of the same material as the first insulating layer 112 or can be made of an organic insulating material for planarization.

[0118] For example, the passivation layer 113 can be made of one or more of materials such as polyacrylate resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene ether resin, polyphenylene sulfide resin, and benzocyclobutene, but is not limited thereto. The passivation layer 117 can be formed as a single layer, a double layer, or a multi-layer.

[0119] A source 153 and a drain 154 connected to the source region 151b and the drain region 151c, respectively, are disposed on the first insulating layer 112. The source 153 and the drain 154 are made of any one or two or more materials having a low resistance characteristic, such as aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, molybdenum (Mo), molybdenum titanium alloy (MoTi), chromium (Cr), and titanium (Ti).

[0120] A first pixel electrode 155a and a second pixel electrode 155b are disposed on the passivation layer 113. The first pixel electrode 155a and the second pixel electrode 155b can be formed of a metal having a high reflectance, such as a layered structure of aluminum (Ti) and titanium (Ti) (Ti / Al / Ti), a layered structure of aluminum (Al) and ITO (ITO / Al / ITO), an APC alloy (Ag / Pd / Cu), and a layered structure of an APC alloy and ITO (ITO / APC / ITO).

[0121] In the above description, a first connection electrode 164 can be disposed on the first light emitting device 160 for electrical connection with the first pixel driving device 150a. The first connection electrode 164 can include a first device electrode 164a and a first bonding electrode 164b including a conductive ball, and is electrically connected to the first pixel electrode 155a so as to be electrically connected to the first pixel driving device 150a.

[0122] In the above description, a second connection electrode 174 can be disposed on the second light emitting device 170 for electrical connection with the second pixel driving device 150b. The second connection electrode 174 can include a second device electrode 174a and a second bonding electrode 174b including a conductive ball, and is electrically connected to the second pixel electrode 155b so as to be electrically connected to the first pixel driving device 150a.

[0123] Figure 4 is a schematic flowchart for explaining a manufacturing method of the LED display apparatus 100 according to an embodiment of the present specification.

[0124] The first substrate can be a sapphire wafer substrate on which a semiconductor can be grown. After forming the nGaN-based common electrode layer on the first substrate, a first light emitting device including a first n-type semiconductor layer, a first active layer, and a first p-type semiconductor layer is continuously epitaxially grown on the first substrate (S110). The first light emitting device can be configured as a separate light emitting device by etching the epitaxially grown semiconductor layer. In this case, a buffer layer for buffering a lattice constant can also be formed on the first substrate.

[0125] Further, a first pixel driving device and a second pixel driving device are provided on the second substrate (S120). The first pixel driving device and the second pixel driving device are thin film transistors and are provided to be electrically connected to a driving circuit for driving a pixel.

[0126] Subsequently, a second light emitting device including a second n-type semiconductor layer, a second active layer, and a second p-type semiconductor layer is transferred onto the common electrode layer on the first substrate (S130). The second light emitting device is provided on the common electrode layer through a transfer process, and the second light emitting device can be a light emitting device grown on a separate semiconductor growth substrate, and in this case, can further include a step of providing and bonding a bonding layer and a connection electrode.

[0127] Subsequently, the first substrate and the second substrate are bonded to each other (S140); when the first substrate and the second substrate are bonded to each other, the first p-type semiconductor layer and the first pixel driving device are electrically connected by providing a first connection electrode, and the second p-type semiconductor layer and the second pixel driving device are electrically connected by providing a second connection electrode (S150); thereby manufacturing an LED display apparatus. As described above, a method of manufacturing an LED display apparatus can be provided in which a transfer process for transferring a light emitting device is minimized by using a method in which a common electrode layer and a first light emitting device are grown on a first substrate to be used as a light emitting device.

[0128] Although embodiments of the present application have been described in detail with reference to the accompanying drawings, the present application is not necessarily limited to these embodiments and various modifications can be made within the scope of the present application without departing from the technical spirit of the present application. Therefore, the embodiments disclosed in the present application are not intended to limit the technical spirit of the present application, but to explain, and the scope of the technical spirit of the present application is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and are not restrictive. The scope of protection of the present application should be interpreted by the claims and all technical ideas within the equivalent scope thereof should be interpreted as being included in the scope of the present application.

Claims

1. A light-emitting diode (LED) display device, the LED display device comprising: A common electrode layer, wherein the common electrode layer is located on a first substrate; The second substrate includes a first pixel driving device and a second pixel driving device. A first light-emitting device is located on the common electrode layer, and the first light-emitting device includes a first n-type semiconductor layer, a first active layer, and a first p-type semiconductor layer; The second light-emitting device is located on the common electrode layer and includes a second n-type semiconductor layer, a second active layer, and a second p-type semiconductor layer. A first connection electrode connects the first p-type semiconductor layer to the first pixel driving device; as well as The second connection electrode connects the second p-type semiconductor layer to the second pixel driving device. The common electrode layer is made of the same material as the first n-type semiconductor layer and is directly connected to the first n-type semiconductor layer. The LED display device further includes a third connecting electrode, which connects the common electrode layer to the second n-type semiconductor layer.

2. The LED display device according to claim 1, wherein, The common electrode layer is disposed over the entire area of ​​the first substrate.

3. The LED display device according to claim 1, wherein, The first active layer and the second active layer are configured to emit light of different wavelengths.

4. The LED display device according to claim 1, wherein, The first active layer is configured to emit light of blue or green wavelengths.

5. The LED display device according to claim 1, further comprising a buffer layer, the buffer layer buffering the lattice constant between the first substrate and the common electrode layer. in, The common electrode layer is grown on the first substrate through an epitaxial process.

6. The LED display device according to claim 1, wherein, The first substrate is a sapphire substrate.

7. The LED display device according to claim 1, wherein, The common electrode layer is an nGaN layer doped with Si.

8. The LED display device according to claim 1, wherein the LED display device further comprises a black matrix, the black matrix being filled between the first light-emitting device and the second light-emitting device.

9. The LED display device according to claim 1, wherein the common electrode layer further comprises a light mixing prevention layer between the first light-emitting device and the second light-emitting device.

10. The LED display device according to claim 9, wherein, The light-mixing prevention layer is a light-conducting layer made of a conductive material used for reflecting light.

11. The LED display device according to claim 1, further comprising a third light-emitting device, the third light-emitting device being located on the common electrode layer. in, The first light-emitting device, the second light-emitting device, and the third light-emitting device emit light of different wavelengths.

12. A method for manufacturing a light-emitting diode (LED) display device, the method comprising the following steps: A common electrode layer is formed on a first substrate, and a first light-emitting device comprising a first n-type semiconductor layer, a first active layer and a first p-type semiconductor layer is subsequently grown. A first pixel driving device and a second pixel driving device are disposed on a second substrate; The second light-emitting device, comprising a second n-type semiconductor layer, a second active layer, and a second p-type semiconductor layer, is transferred onto the common electrode layer; as well as The first substrate and the second substrate are joined together; A first connection electrode is provided to connect the first p-type semiconductor layer to the first pixel driving device; as well as A second connection electrode is provided to connect the second p-type semiconductor layer to the second pixel driving device.

13. The method according to claim 12, wherein, The steps of forming the common electrode layer on the first substrate and growing the first light-emitting device include continuously growing a semiconductor layer and etching the semiconductor layer to form the first light-emitting device.

14. The method according to claim 12, wherein, The step of forming the common electrode layer on the first substrate further includes forming a buffer layer on the first substrate for buffering the lattice constant.

15. The method according to claim 12, wherein, The step of transferring the second light-emitting device onto the common electrode layer further includes: Provides a second light-emitting device grown on a third substrate; and An adhesive layer is provided on the common electrode layer to bond the second light-emitting device to the common electrode layer.

16. The method according to claim 12, wherein, The step of transferring the second light-emitting device onto the common electrode layer includes providing a third connection electrode on the common electrode layer to connect the second light-emitting device to the common electrode layer.

17. The method according to claim 12, wherein, The common electrode layer is an nGaN layer doped with Si.

18. The method according to claim 12, further comprising the step of: A black matrix is ​​formed between the first light-emitting device and the second light-emitting device.

19. The method of claim 12, further comprising the step of: A light mixing prevention layer is formed between the first light-emitting device and the second light-emitting device.

20. The method according to claim 19, wherein, The light-mixing prevention layer is a light-conducting layer made of a conductive material used for reflecting light.

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