JP2023170079A - Manufacturing method for display device - Google Patents

Abstract

To improve the performance of a display device.SOLUTION: A manufacturing method for a display device includes a step of alignment of a substrate SS1 (a first substrate) on which a plurality of LED elements 20 are arranged in a matrix and a substrate for transfer (a second substrate) TR1 including a surface TRt, which is a glass base material and on which an adhesive resin layer 50 is formed. A plurality of metal patterns MP, which can be visually recognized through the adhesive resin layer 50, is formed on the surface TRt of the substrate for transfer TR1. In the alignment step, the alignment of the substrate SS1 and the substrate for transfer TR1 is performed on the basis of position information on the plurality of metal patterns MP.SELECTED DRAWING: Figure 11

Description

The present invention relates to a technology for manufacturing display devices.

As a display device, there is an LED (Light Emitting Diode) display device in which light emitting diode elements, which are self-luminous elements, are arranged in a matrix on a substrate. For example, U.S. Patent Application Publication No. 2019/0096774 (Patent Document 1) discloses that alignment marks are formed on the template when transferring a plurality of microdevices (LEDs) from the template to the receiver substrate. Are listed. Japanese Patent Publication No. 2019-511838 (Patent Document 2) describes a method for transferring three types of LED elements from a growth substrate to a target substrate.

US Patent Application Publication No. 2019/0096774 Special table 2019-511838 publication

In the case of an LED display device, a large number of LED elements are mounted on an array substrate. In the process of mounting the LED elements from the sapphire substrate on which they are formed to the array substrate (sometimes called a backplane), the LED elements are transferred from the sapphire substrate to the transfer substrate, and then retransferred from the transfer substrate to the array substrate. There are ways to do this. In addition, in order to make the electrodes of the LED elements and the array substrate face each other when mounted on the array substrate, the LED elements are transferred from the sapphire substrate to the first transfer substrate and then to the second transfer substrate, and then to the second transfer substrate. A possible method is to re-transfer the image onto the array substrate. In this way, when transferring a plurality of LED elements, it is necessary to align the transfer source substrate and the transfer destination substrate. In particular, when multiple types of LED elements are mounted at high density, a technique for improving alignment accuracy is required.

An object of the present invention is to provide a technique for improving the performance of a display device.

A method for manufacturing a display device, which is one embodiment of the present invention, includes: (a) a first substrate having a first surface on which a plurality of first inorganic light emitting elements are arranged in a matrix; and a glass substrate. (b) aligning the first substrate and the second substrate; and (b) aligning the first substrate and the second substrate. and (c) after the step (b), attaching each of the plurality of first inorganic light emitting elements to the adhesive resin layer on the second substrate, and (d) after the step (c). , the step of separating each of the plurality of first inorganic light emitting elements from the first substrate by increasing the distance between the first substrate and the second substrate. A plurality of metal patterns that are visible through the adhesive resin layer are formed between the second surface of the second substrate and the adhesive resin layer. In the step (b), the first substrate and the second substrate are aligned based on the positional information of the plurality of metal patterns.

FIG. 1 is a plan view showing an example of the configuration of a display device according to an embodiment. FIG. 2 is a circuit diagram showing an example of a configuration of a circuit around a pixel shown in FIG. 1. FIG. 2 is an enlarged cross-sectional view showing an example of a peripheral structure of an LED element arranged in each of a plurality of pixels of the display device shown in FIG. 1. FIG. 4 is an enlarged sectional view showing a modification of the LED element shown in FIG. 3. FIG. FIG. 2 is an explanatory diagram showing a flow of the manufacturing process of the display device shown in FIG. 1. FIG. FIG. 6 is a plan view schematically showing a substrate prepared in the LED holding substrate preparation step shown in FIG. 5; 7 is an enlarged cross-sectional view of each of the plurality of substrates shown in FIG. 6. FIG. 6 is a plan view showing an example of a transfer substrate used in the first transfer step and the second transfer step shown in FIG. 5. FIG. 9 is a sectional view taken along line AA in FIG. 8. FIG. 6 is a cross-sectional view schematically showing an array substrate prepared in the array substrate preparation step shown in FIG. 5. FIG. 6 is a cross-sectional view schematically showing the first alignment step shown in FIG. 5. FIG. FIG. 6 is a cross-sectional view schematically showing the first pasting step shown in FIG. 5. FIG. 6 is a cross-sectional view schematically showing a state in which a plurality of first inorganic light emitting elements are irradiated with a laser in the first holding substrate peeling step shown in FIG. 5. FIG. 6 is a cross-sectional view schematically showing a state where the holding substrate is peeled off from a plurality of first inorganic light emitting elements in the first holding substrate peeling step shown in FIG. 5. FIG. FIG. 6 is a cross-sectional view schematically showing the second alignment step shown in FIG. 5. FIG. FIG. 6 is a cross-sectional view schematically showing the second pasting step shown in FIG. 5. FIG. 6 is a cross-sectional view schematically showing a state where the holding substrate is peeled off from a plurality of second inorganic light emitting elements in the second holding substrate peeling step shown in FIG. 5. FIG. FIG. 6 is a cross-sectional view schematically showing the third alignment step shown in FIG. 5. FIG. FIG. 6 is a cross-sectional view schematically showing the third pasting step shown in FIG. 5. FIG. 6 is a cross-sectional view schematically showing a state where the holding substrate is peeled off from a plurality of third inorganic light emitting elements in the third holding substrate peeling step shown in FIG. 5. FIG. FIG. 6 is a cross-sectional view showing an alignment step included in the second transfer step shown in FIG. 5. FIG. 6 is a cross-sectional view showing a pasting process included in the second transfer process shown in FIG. 5. FIG. 6 is a cross-sectional view showing a substrate peeling step included in the second transfer step shown in FIG. 5. FIG. 6 is a cross-sectional view showing an alignment process included in the array substrate mounting process shown in FIG. 5. FIG. 6 is a cross-sectional view showing a bonding process included in the array substrate mounting process shown in FIG. 5. FIG. 6 is a cross-sectional view showing a substrate peeling process included in the array substrate mounting process shown in FIG. 5. FIG. 7 is a plan view showing a modification of the substrate shown in FIG. 6. FIG. 9 is a plan view showing a modification to FIG. 8. FIG. FIG. 28 is an enlarged plan view schematically showing an image in an alignment process when the alignment mark formed on the substrate shown in FIG. 27 and the metal pattern formed on the transfer substrate shown in FIG. 8 have different shapes.

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the disclosure is merely an example, and any modifications that can be easily made by those skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention. In addition, in order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but these are only examples, and the interpretation of the present invention is It is not limited. In addition, in this specification and each figure, elements similar to those described above with respect to the existing figures are denoted by the same or related numerals, and detailed explanations may be omitted as appropriate.

In the following embodiments, a micro LED display device including a plurality of micro LED elements will be described as an example of a display device using a plurality of inorganic light emitting elements. Micro LED elements have a smaller element size (outer diameter) than general LED elements, so they have the advantage of being able to display high-definition images.

Note that an organic light-emitting diode (OLED) is an example of a light-emitting diode element that is a self-luminous element. The inorganic light emitting diode element (micro LED element) described in the following embodiments is distinguished from the organic light emitting diode element.

<Display device>
First, a configuration example of a micro LED display device, which is a display device of this embodiment, will be described. FIG. 1 is a plan view showing a configuration example of a display device according to an embodiment. In FIG. 1, the boundary between the display area DA and the peripheral area PFA, the control circuit 5, the drive circuit 6, and each of the plurality of pixels PIX are indicated by two-dot chain lines. FIG. 2 is a circuit diagram showing an example of the configuration of a circuit around the pixel shown in FIG.

As shown in FIG. 1, the display device DSP1 of the present embodiment includes a display area DA, a peripheral area PFA surrounding the display area DA in a frame shape, and a plurality of display areas arranged in a matrix within the display area DA. It has a pixel PIX. Further, the display device DSP1 includes a substrate 10, a control circuit 5 formed on the substrate 10, and a drive circuit 6 formed on the substrate 10.

The control circuit 5 is a control circuit that controls driving of the display function of the display device DSP1. For example, the control circuit 5 is a driver IC (Integrated Circuit) mounted on the substrate 10. In the example shown in FIG. 1, the control circuit 5 is arranged along one short side of the four sides of the substrate 10. Further, in the example of the present embodiment, the control circuit 5 includes a signal line drive circuit that drives a video signal line VL (see FIG. 2) connected to a plurality of pixels PIX. However, the position and configuration example of the control circuit 5 is not limited to the example shown in FIG. 1, and there are various modifications. For example, in FIG. 1, a circuit board such as a flexible board is connected to a position shown as the control circuit 5, and the above-described driver IC may be mounted on the circuit board. Further, for example, a signal line drive circuit that drives the video signal line VL may be formed separately from the control circuit 5.

The drive circuit 6 is a circuit that drives the scanning signal line GL among the plurality of pixels PIX. The drive circuit 6 drives the plurality of scanning signal lines GL based on control signals from the control circuit 5. In the example shown in FIG. 1, the drive circuit 6 is arranged along each of two long sides of the four sides of the substrate 10. However, the position and configuration example of the drive circuit 6 is not limited to the example shown in FIG. 1, and there are various modifications. For example, in FIG. 1, a circuit board such as a flexible board may be connected to the position shown as the control circuit 5, and the above-mentioned drive circuit 6 may be mounted on the circuit board.

Next, an example of the circuit configuration of the pixel PIX will be described using FIG. 2. Note that although one pixel PIX is representatively illustrated in FIG. 2, each of the plurality of pixels PIX shown in FIG. 1 includes the same circuit as the pixel PIX shown in FIG. Hereinafter, a circuit including a switch, a capacitor, and an LED element 20 included in the pixel PIX may be referred to as a pixel circuit. The pixel circuit is a voltage signal type circuit that controls the light emitting state of the LED element 20 according to the video signal Vsg supplied from the control circuit 5 (see FIG. 1).

As shown in FIG. 2, the pixel PIX includes an LED element 20. The LED element 20 is the above-mentioned micro light emitting diode. The LED element 20 has an anode electrode 20EA (see FIG. 3 described later) and a cathode electrode 20EK (see FIG. 3 described later). Each of the anode electrode 20EA and cathode electrode 20EK of the LED element 20 is electrically connected to the terminal 30 of the pixel PIX. In the example shown in FIG. 2, the cathode electrode 20EK of the LED element 20 is connected to the terminal 30L, and the anode electrode 20EA of the LED element 20 is connected to the terminal 30H. The terminal 30L is supplied with a potential PVS which is a relatively low fixed potential (low potential), and the terminal 30H is supplied with a potential PVD which is a fixed potential (high potential) higher than the potential supplied to the terminal 30L. Ru.

Pixel PIX includes an output switch BCT, a drive transistor DRT, and a pixel switch SST. The output switch BCT is a transistor that controls the light emission time of the LED element 20 in response to a control signal Gsb supplied from the drive circuit 6. The drive transistor DRT is a transistor that controls the amount of drive current supplied to the anode electrode of the LED element 20 according to the video signal Vsg. The pixel switch SST is a transistor that controls the connection state (on or off state) between the pixel circuit and the video signal line VL in response to the control signal Gss. Further, the drive circuit 6 includes a reset switch RST that controls input of a reset potential. Each of the output switch BCT, drive transistor DRT, pixel switch SST, and reset switch RST is, for example, a thin film transistor. When the pixel switch SST is on, a video signal Vsg is input to the pixel circuit from the video signal line VL.

The drive circuit 6 includes a shift register circuit, an output buffer circuit, etc. (not shown). The drive circuit 6 outputs a pulse based on the horizontal scanning start pulse transmitted from the control circuit 5 (see FIG. 1), and outputs a control signal Gss, a control signal Gsb, and a control signal Gsr.

The plurality of scanning signal lines GL include scanning signal lines GLA, GLB, and a reset wiring GLR. Each of the plurality of scanning signal lines GL extends in the X direction. The scanning signal line GLA is connected to the gate electrode of the output switch BCT. When the control signal Gsb is supplied to the scanning signal line GLA, the output switch BCT is turned on. The scanning signal line GLB is connected to the gate electrode of the pixel switch SST. When the control signal Gss is supplied to the scanning signal line GLB, the pixel switch SST is turned on. The reset wiring GLR is connected between the output switch BCT and the drive transistor DRT and to the drain electrode of the reset switch RST. When a control signal Gsr, which is a reset signal, is supplied to the gate electrode of the reset switch RST, a reset potential is supplied to the reset wiring GLR.

Pixel PIX has a storage capacitor Cs and an auxiliary capacitor Cad. The holding capacitor Cs and the auxiliary capacitor Cad are each capacitors. The holding capacitor Cs is connected between the gate electrode of the drive transistor DRT and the terminal 30H. The auxiliary capacitor Cad is connected between the source electrode of the output switch BCT and the terminal 30H. The auxiliary capacitor Cad is a capacitive element for adjusting the amount of light emitted current, and as a modification, the auxiliary capacitor Cad may not be arranged.

<Peripheral structure of LED element>
Next, the peripheral structure of the LED element arranged in the pixel PIX shown in FIG. 1 will be described. FIG. 3 is an enlarged cross-sectional view showing an example of a peripheral structure of an LED element arranged in each of a plurality of pixels of the display device shown in FIG. FIG. 4 is an enlarged sectional view showing a modification of the LED element shown in FIG. 3.

The array substrate SUB1 of the display device DSP1 shown in FIG. 3 is a substrate including a substrate 10 and a plurality of insulating layers stacked on the substrate 10. The plurality of insulating layers that the array substrate SUB1 has include an inorganic insulating layer 11, an organic insulating layer 12, and an organic insulating layer 13. Further, the array substrate SUB1 includes various circuits included in the pixel PIX described using FIG. 2. The substrate 10 has a surface 10f and a surface 10b opposite to the surface 10f. Each of the inorganic insulating layer 11, the organic insulating layer 12, and the organic insulating layer 13 is laminated on the surface 10f of the substrate 10.

Each of the inorganic insulating layer 11, the organic insulating layer 12, and the organic insulating layer 13 may be a laminated film consisting of a plurality of laminated insulating films. For example, semiconductor layers of thin film transistors forming the output switch BCT, drive transistor DRT, and pixel switch SST shown in FIG. 2 are formed within the inorganic insulating layer 11. Some of the plurality of inorganic insulating films forming the inorganic insulating layer 11 are used as a base layer for forming a thin film transistor, and the other part is used as a gate insulating film of the thin film transistor.

As shown in FIG. 3, the LED elements 20 are mounted on the array substrate SUB1. The LED element 20 includes a surface 20f and a surface 20b opposite to the surface 20f. Furthermore, the LED element 20 includes a plurality of (two in FIG. 3) electrodes 20E arranged on a surface 20f. The plurality of electrodes 20E include an anode electrode 20EA and a cathode electrode 20EK. Anode electrode 20EA is connected to terminal 30H via conductive bonding material 40. Cathode electrode 20EK is connected to terminal 30L via conductive bonding material 40. The conductive bonding material 40 is made of, for example, solder. Although one LED element is illustrated in FIG. 3, a plurality of LED elements are mounted in a matrix on the array substrate SUB1. The display device DSP1 displays images by driving a plurality of LED elements 20 mounted on the array substrate SUB1. The light emitted from the LED element 20 is emitted from, for example, the surface 20b side.

Note that FIG. 3 shows an example of the LED element 20 in which both the anode electrode 20EA and the cathode electrode 20EK are arranged on the surface 20f. However, there are various modifications to the structure of the LED element 20. For example, in the case of the LED element 20M1 shown in FIG. 4, a cathode electrode 20EK is provided on the surface 20b, and an anode electrode 20EA is provided on the surface 20f. When replacing the LED element 20 shown in FIG. 3 with the LED element 20M1 shown in FIG. 4, the terminal 30L (see FIG. 3) connected to the cathode electrode 20EK is provided on the surface 20b of the LED element 20M1.

<Display device manufacturing method>
Next, a method for manufacturing the display device DSP1 shown in FIG. 1 will be described. FIG. 5 is an explanatory diagram showing a flow of the manufacturing process of the display device shown in FIG. 1. In the flow illustrated in FIG. 5, for example, three types of LED elements for red, green, and blue are sequentially transferred onto a first transfer substrate, and then mounted on an array substrate via a second transfer substrate. Let's take up and explain. As shown in FIG. 5, the method for manufacturing a display device according to the present embodiment includes an LED holding substrate preparation step, a first transfer substrate preparation step, a second transfer substrate preparation step, an array substrate preparation step, and a first transfer step. , a second transfer step, and an array substrate mounting step. The details of each step will be explained below.

<LED holding substrate preparation process, first transfer substrate preparation process, second transfer substrate preparation process, and array substrate preparation process>
In the LED holding substrate preparation step shown in FIG. 5, the substrate SS1, the substrate SS2, and the substrate SS3 shown in FIG. 6 are prepared. FIG. 6 is a plan view schematically showing a substrate prepared in the LED holding substrate preparation step shown in FIG. 5. FIG. Each of the substrate SS1, the substrate SS2, and the substrate SS3 has an upper surface and a lower surface. Each of the LED holding substrates SS1, SS2, and SS3 has a plurality of LED elements arranged in a matrix on one of the top and bottom surfaces (in the example shown in FIG. 6, on the top surface). has been done.

Specifically, LED elements that emit light of different colors are arranged on the substrate SS1, the substrate SS2, and the substrate SS3, respectively. In other words, each of the substrate SS1, the substrate SS2, and the substrate SS3 is an LED holding substrate that holds a plurality of LED elements. For example, the first inorganic light emitting element 21, which is one of a red LED element, a green LED element, and a blue LED element, is arranged on the surface (element holding surface) SS1t of the substrate SS1. On the surface (element holding surface) SS2t of the substrate SS2, a second inorganic light emitting element 22 which is an LED element different from the first inorganic light emitting element 21 among a red LED element, a green LED element, and a blue LED element is disposed. are arranged. On the surface (element holding surface) SS3t of the substrate SS3, an LED element different from the first inorganic light emitting element 21 and the second inorganic light emitting element 22 among the red LED element, green LED element, and blue LED element is mounted. A certain third inorganic light emitting element 23 is arranged.

A plurality of first inorganic light emitting elements 21 are arranged in a matrix on the surface SS1t of the substrate SS1. The second inorganic light emitting element 22 and the third inorganic light emitting element 23 are not arranged on the surface SS1t of the substrate SS1. A plurality of second inorganic light emitting elements 22 are arranged in a matrix on the surface SS2t of the substrate SS2. The first inorganic light emitting element 21 and the third inorganic light emitting element 23 are not arranged on the surface SS2t of the substrate SS2. A plurality of third inorganic light emitting elements 23 are arranged in a matrix on the surface SS3t of the substrate SS3. The first inorganic light emitting element 21 and the second inorganic light emitting element 22 are not arranged on the surface SS3t of the substrate SS3. Each of the substrate SS1, the substrate SS2, and the substrate SS3 is, for example, a sapphire substrate. Each of the first inorganic light emitting element 21, the second inorganic light emitting element 22, and the third inorganic light emitting element 23 is formed by laminating, for example, a metal film, an insulating film, a semiconductor film, etc. on a sapphire substrate. . In other words, each of the substrate SS1, the substrate SS2, and the substrate SS3 is a substrate for manufacturing LEDs (LED wafer).

Note that although the planar shapes of the substrate SS1, the substrate SS2, and the substrate SS3 are illustrated as circular in FIG. 6, the planar shapes of the substrate SS1, the substrate SS2, and the substrate SS3 are not limited to the circular shape, and may be square, for example, etc. There are various variations.

FIG. 7 is an enlarged cross-sectional view of each of the plurality of substrates shown in FIG. 6. Note that since the cross-sectional structures of the substrate SS1, the substrate SS2, and the substrate SS3 are the same, one figure is shown as a representative, and the structure common to the substrate SS1, the substrate SS2, and the substrate SS3 is explained. Below, as a representative example, a substrate SS1 including a plurality of first inorganic light emitting elements 21 will be described. However, in the following description, the first inorganic light emitting element 21 is replaced with the second inorganic light emitting element 22 or the third inorganic light emitting element 23, the substrate SS1 is replaced with the substrate SS2 or the substrate SS3, and the surface SS1t is replaced with the surface SS2t or the surface SS3t. can be replaced with

Each of the plurality of first inorganic light emitting elements 21 arranged on the surface SS1t of the substrate SS1 shown in FIG. A P-type semiconductor layer 26 stacked on 25. The N-type semiconductor layer 24 is formed as a common base layer for the anode electrode 20EA and the cathode electrode 20EK, and the active layer 25 and the P-type semiconductor layer 26 are stacked on the anode electrode 20EA side. On the anode electrode 20EA side, a transparent electrode layer 27a is formed on the P-type semiconductor layer 26. The transparent electrode layer 27a on the anode electrode 20EA side and the N-type semiconductor layer 24 on the cathode electrode 20EK side are covered with a passivation film 28, which is an inorganic insulating film. Openings are formed in the passivation film 28 at locations where the anode electrode 20EA and the cathode electrode 20EK are to be formed. A metal electrode layer 27c is laminated in each opening with a seed layer 27b interposed therebetween. The anode electrode 20EA is a laminate of a transparent electrode layer 27a, a seed layer 27b, and a metal electrode layer 27c. On the other hand, the cathode electrode 20EK is a stack of a seed layer 27b and a metal electrode layer 27c stacked on the N-type semiconductor layer 24. A buffer layer 29 made of gallium nitride is formed between the N-type semiconductor layer 24 and the substrate SS1.

In the example shown in FIG. 7, the conductive bonding material 40 shown in FIG. 3 is not bonded to the electrode 20E of the first inorganic light emitting element 21, for example. However, as a modification, the conductive bonding material 40 shown in FIG. 3 may be bonded to the electrode 20E in advance.

Each of the substrate SS1, the substrate SS2, and the substrate SS3 is prepared, for example, before the first transfer step shown in FIG. 5. However, as a modified example, the substrate SS1, the substrate SS2, and the substrate SS3 may not all be prepared in advance before the first transfer step (specifically, the first alignment step of the first transfer step). For example, the substrate SS2 may be prepared at least before the second alignment step of the first transfer step shown in FIG. Further, it is sufficient that the substrate SS3 is prepared at least before the third alignment step of the first transfer step.

In the first transfer substrate preparation step and the second transfer substrate preparation step shown in FIG. 5, transfer substrates TR1 and TR2 shown in FIGS. 8 and 9 are prepared. FIG. 8 is a plan view showing an example of a transfer substrate used in the first transfer step and the second transfer step shown in FIG. 5. FIG. FIG. 9 is a sectional view taken along line AA in FIG. 8. Since the transfer substrate TR1 and the transfer substrate TR2 can have the same structure, one diagram is representatively shown in FIGS. 8 and 9 to explain the structure common to the transfer substrate TR1 and the transfer substrate TR2. ing. The transfer substrate TR1 used in the first transfer step shown in FIG. 5 will be described below as a representative example. However, in the following description, the portion described as transfer substrate TR1 can be replaced with transfer substrate TR2.

As shown in FIG. 8, the transfer substrate TR1 has a rectangular shape in plan view. The transfer substrate TR1 has a side TRs1 extending in the X direction, a side TRs2 on the opposite side of the side TRs1 in the Y direction intersecting the X direction, a side TRs3 extending in the Y direction, and a side TRs3 on the opposite side of the side TRs3 in the X direction. It has a certain side TRs4. Further, the transfer substrate TR1 includes an element placement area R1, which is a planned area for pasting the first inorganic light emitting element 21, the second inorganic light emitting element 22, and the third inorganic light emitting element 23 shown in FIG. It has a peripheral region R2 around the . Further, the transfer substrate TR1 has a plurality of (two in FIG. 8) metal patterns MP.

As shown in FIG. 9, the transfer substrate TR1 is a glass base material including a surface TRt on which the adhesive resin layer 50 is formed and a surface TRb located on the opposite side of the surface TRt. In other words, the transfer substrate TR1 is a base substrate that supports the adhesive resin layer 50, and in this embodiment, is made of a glass material. Each of the plurality of metal patterns MP is formed on the surface TRt of the transfer substrate TR1, which is a glass base material, and is covered with the adhesive resin layer 50. The plurality of metal patterns MP are patterns made of a metal material, and are used as alignment marks in each of the first alignment step, second alignment step, and third alignment step shown in FIG. 5. The type of metal material constituting the metal pattern MP is not particularly limited, but examples thereof include copper, titanium, and aluminum. Further, it is preferable that the metal pattern MP is placed at a position where it does not get in the way during the process of transferring the plurality of LED elements 20. In the example shown in FIG. 1, each of the plurality of metal patterns MP is formed in a peripheral region R2 around an element arrangement region R1. In the example shown in FIG. 8, in plan view, each of the plurality of metal patterns MP has a corner where each side (sides TRs1, TRs2, TRs3, and TRs4) of the transfer substrate TR1 intersects with a corner of the element arrangement area. It is located between the In this case, in the positioning process described later, positional information of two or more distant metal patterns MP is acquired, so that positioning accuracy can be improved.

The adhesive resin layer 50 has a surface 50b facing the surface TRt of the transfer substrate TR1 and a surface 50t opposite to the surface 50b. The surface 50t has adhesiveness, and in each of the first pasting process, second pasting process, and third pasting process shown in FIG. element 21, second inorganic light emitting element 22, and third inorganic light emitting element 23). Furthermore, in the first alignment step, second alignment step, and third alignment step shown in FIG. 5, it is necessary to visually recognize the metal pattern MP through the adhesive resin layer 50. Therefore, the adhesive resin layer 50 is required to have transparency (visible light transmittance). As shown in FIG. 9, the adhesive resin layer 50 is formed to cover the entire surface TRt. Examples of the material constituting the adhesive resin layer 50 include silicone, polyimide, acrylic, and epoxy.

By using a metal pattern as the pattern used as the alignment mark as in this embodiment, the strength of the metal pattern MP, which is the alignment mark, can be improved. For example, when an alignment mark is formed using an organic material such as a resin, the shape of the mark may be deformed when heat is applied in a manufacturing process using the transfer substrate TR1. On the other hand, if a metallic pattern is used as an alignment mark as in this embodiment, deformation of the mark shape can be prevented even if heat is applied.

Further, from the viewpoint of visibility of the metal pattern MP, it is preferable that the metal pattern MP is exposed from the adhesive resin layer 50. Possible methods for exposing the metal pattern MP from the adhesive resin layer 50 include a method of forming the adhesive resin layer 50 while avoiding the metal pattern MP, or a method of forming the metal pattern MP on the adhesive resin layer 50.

However, if an attempt is made to expose the metal pattern MP from the adhesive resin layer 50, the following problems arise. For example, when forming the adhesive resin layer 50 after forming the metal pattern MP, the adhesive resin layer 50 is formed on the surface TRt using, for example, a casting method, a slit coating method, a spin coating method, or the like. At this time, if the metal pattern MP is to be exposed from the adhesive resin layer 50, a process for exposing the metal pattern MP (for example, a process of forming a mask covering the metal pattern MP and a process of removing the mask) is required. This makes the manufacturing process complicated. Further, when the metal pattern MP is formed on the adhesive resin layer 50, the position of the metal pattern MP may shift as the adhesive resin layer 50 deforms.

In the case of this embodiment, the metal pattern MP is covered with an adhesive resin layer 50. Therefore, there is no need to perform a process to expose the metal pattern MP (for example, a process to form a mask covering the metal pattern MP or a process to remove this mask), so that the manufacturing process can be made more efficient. Furthermore, in the case of the present embodiment, the metal pattern MP can be directly formed on the surface TRt of the transfer substrate TR1, so even if the adhesive resin layer 50 is deformed, the position of the metal pattern MP will not shift. can be prevented. Further, as the metal material constituting the metal pattern MP, it is preferable to use a material that has high visibility and is easy to process into a predetermined pattern shape. Examples of such materials include aluminum, copper, and titanium. Further, the material constituting the metal pattern MP is not limited to a single element, but may be an alloy containing the above-mentioned metal materials.

In addition, by using a glass substrate as the base material of the transfer substrates TR1 and TR2, it is possible to improve the handling properties in the first and second transfer steps described below. It can be formed on a glass substrate in any position and shape with high precision by film formation and etching.

Furthermore, in the array substrate preparation step, a transfer substrate TR1 shown in FIG. 10 is prepared. FIG. 10 is a cross-sectional view schematically showing an array substrate prepared in the array substrate preparation step shown in FIG. A large number of terminals 30 are arranged in a matrix in the display area DA of the array substrate SUB1, and FIG. 10 representatively shows some of them.

As shown in FIG. 10, the transfer substrate TR1 includes a surface SUBt and a surface SUBb on the opposite side of the surface SUBt. The surface SUBt is a mounting surface on which a plurality of LED elements 20 shown in FIG. 6 are planned to be mounted. The transfer substrate TR1 has a plurality of terminals 30. The plurality of terminals 30 include a terminal (first terminal) 31 that is scheduled to be electrically connected to the first inorganic light emitting element 21 (see FIG. 6). The plurality of terminals 30 include a terminal (second terminal) 32 that is to be electrically connected to the second inorganic light emitting element 22 (see FIG. 6). Further, the plurality of terminals 30 include a terminal (third terminal) 33 that is scheduled to be electrically connected to the third inorganic light emitting element 23 (see FIG. 6). Each of the terminals 31, 32, and 33 is arranged in a matrix corresponding to the position of the pixel PIX shown in FIG.

In the example shown in FIG. 10, a conductive bonding material 40 as a protruding electrode is formed on each of the plurality of terminals 30 in advance. However, as a modification, the conductive bonding material 40 may not be bonded to the terminal 30 in advance.

<First transfer step>
Next, the first transfer step shown in FIG. 5 will be explained. In the example shown in FIG. 5, the first transfer step includes a first alignment step, a first attachment step, a first holding substrate separation step, a second alignment step, a second attachment step, and a second holding substrate separation step. , a third alignment step, a third pasting step, and a third holding substrate peeling step. In the first transfer step, a plurality of first inorganic light emitting elements 21 on a substrate SS1, a plurality of second inorganic light emitting elements 22 on a substrate SS2, and a plurality of third inorganic light emitting elements 23 on a substrate SS3 shown in FIG. After aligning each with a preset arrangement interval, they are transferred to the element arrangement region R1 of the transfer substrate TR1. Hereinafter, details of the first transfer step will be explained in order.

<First alignment process>
FIG. 11 is a cross-sectional view schematically showing the first alignment step shown in FIG. 5. In the first alignment step shown in FIG. 5, as shown in FIG. 11, the surface SS1t of the substrate SS1 and the surface TRt of the transfer substrate TR1 are aligned. In the example shown in FIG. 11, the alignment mark is photographed by the image sensor 71 with the substrate SS1 held on the stage 61 and the transfer substrate TR1 held on the stage 62 facing each other, and the position of this alignment mark is Based on the information, the substrate SS1 and the transfer substrate TR1 are aligned. Specifically, the positions of each of the plurality of first inorganic light emitting elements 21 formed on the surface SS1t of the substrate SS1 and the element arrangement region R1 on the adhesive resin layer 50 formed on the surface TRt of the transfer substrate TR1. Adjust the relationship with position.

The stage 61 is a member capable of holding the substrate SS1. The back surface SS1b of the substrate SS1 is held by the holding surface 61h of the stage 61. The stage 62 is a member capable of holding the transfer substrate TR1. The surface TRb of the transfer substrate TR1, which is a glass base material, is held by the holding surface 62h of the stage 62. The method for the stage 61 to hold the substrate SS1 and the method for the stage 62 to hold the transfer substrate TR1 include, for example, a suction holding method, or a fixing jig (not shown) for fixing the peripheral edge of the substrate SS1 or the transfer substrate TR1. For example, a method of fixing with a chuck), etc. Further, each of the stage 61 and the stage 62 is connected to a control device 72, and can be moved independently of each other in a plane direction (XY plane direction) based on a command signal output from the control device. Equipped with a mechanism.

The image sensor 71 is arranged between the substrate SS1 and the transfer substrate TR1, and the control device 72 and the image sensor 71 are electrically connected. The image sensor 71 images, for example, one or more of the plurality of first inorganic light emitting elements 21 as an alignment mark on the substrate SS1 side, and outputs image data to the control device 72. Further, the image sensor 71 images a plurality of metal patterns MP as alignment marks on the transfer substrate TR1 side, and outputs image data to the control device 72. Note that in the case where four metal patterns MP exist on the transfer substrate TR1 as illustrated in FIG. 8, at least two or more metal patterns MP are imaged. The scope of the image sensor 71 may sometimes image two or more metal patterns MP at once, or may sequentially image two or more metal patterns MP.

The control device 72 that has acquired the image data from the image sensor 71 determines the position of the metal pattern MP based on the position information of the stage 62 when the image sensor 71 imaged the metal pattern MP and the analysis result of the image data of the metal pattern MP. calculate. Similarly, the control device 72 determines whether the first inorganic light emitting element 21 is the first inorganic light emitting element 21 or Calculate the position of Then, based on the positional information of the metal pattern MP and the positional information of the first inorganic light emitting element 21, at least one of the stage 61 and the stage 62 is moved along the XY plane to place it on a preset transfer position. Adjustments are made so that each of the plurality of first inorganic light emitting elements 21 is positioned.

<First pasting process>
FIG. 12 is a cross-sectional view schematically showing the first pasting step shown in FIG. 5. In the first attachment step, as shown in FIG. 12, each of the plurality of first inorganic light emitting elements 21 is attached to the adhesive resin layer 50 on the transfer substrate TR1.

In the first alignment process described above, when the distance between the stage 61 and the stage 62 is brought closer after alignment in the direction along the XY plane, the positions are placed on the surface SS1t of the substrate SS1. Each of the plurality of first inorganic light emitting elements 21 approaches the transfer substrate TR1. When the distance between the substrate SS1 and the transfer substrate TR1 is further reduced, a portion of each of the plurality of first inorganic light emitting elements 21 is adhered to the adhesive resin layer 50. At this time, a portion of the electrode 20E shown in FIG. 7 (or a portion of the conductive bonding material 40 shown in FIG. 3) of the LED element 20 is adhered to the adhesive resin layer.

<First holding substrate peeling process>
Next, the first holding substrate peeling process shown in FIG. 5 will be described. FIG. 13 is a cross-sectional view schematically showing a state in which a plurality of first inorganic light emitting elements are irradiated with a laser in the first holding substrate peeling step shown in FIG. FIG. 14 is a cross-sectional view schematically showing a state in which the holding substrate is peeled off from a plurality of first inorganic light emitting elements in the first holding substrate peeling step shown in FIG. In the first holding substrate peeling step, as shown in FIG. 14, after the first holding substrate pressing step, the substrate SS1 and the plurality of first inorganic light emitting elements 21 are peeled off.

For example, a technique called laser lift-off can be used as a method for peeling off the close contact interface between the surface SS1t of the substrate SS1, which is the holding substrate, and the plurality of first inorganic light emitting elements 21. When using a technique called laser lift-off, as schematically shown in FIG. Irradiate UVL light. As shown in FIG. 7, a buffer layer 29 made of gallium nitride is formed between the N-type semiconductor layer 24 of the first inorganic light emitting element 21 and the surface SS1t of the substrate SS1. When the buffer layer 29 is irradiated with the laser beam, the surface layer (a portion on the surface SS1t side) of the buffer layer 29 is modified, and it becomes possible to separate the substrate SS1 and the first inorganic light emitting element 21. After the modification of the buffer layer 29 is completed, as shown in FIG. 14, the distance between the substrate SS1 and the transfer substrate TR1 is separated. At this time, each of the plurality of first inorganic light emitting elements 21 is attached to the adhesive resin layer 50. Therefore, each of the plurality of first inorganic light emitting elements 21 is peeled off from the substrate SS1, and a structure in which the plurality of first inorganic light emitting elements 21 are pasted on the transfer substrate TR1 is obtained.

Although the example shown in FIG. 13 shows an example in which all the first inorganic light emitting elements 21 are irradiated with ultraviolet laser light UVL at once, as a modified example, only one of the plurality of first inorganic light emitting elements 21 A portion may be selectively irradiated with ultraviolet laser light UVL. In this case, among the plurality of first inorganic light emitting elements 21 formed on the substrate SS1, the first inorganic light emitting elements 21 irradiated with the ultraviolet laser light UVL can be selectively transferred to the transfer substrate TR1.

<Second alignment process>
FIG. 15 is a cross-sectional view schematically showing the second alignment step shown in FIG. 5. In the second alignment step shown in FIG. 5, as shown in FIG. 15, the substrate SS2 and the transfer substrate TR1 are aligned. At the start of this process, a plurality of first inorganic light emitting elements 21 are already attached on the adhesive resin layer 50 of the transfer substrate TR1. In the example shown in FIG. 15, the alignment mark is photographed by the image sensor 71 with the substrate SS2 held on the stage 61 and the transfer substrate TR1 held on the stage 62 facing each other, and the position of this alignment mark is Based on the information, the substrate SS2 and the transfer substrate TR1 are aligned. Specifically, the respective positions of the plurality of second inorganic light emitting elements 22 formed on the surface SS2t of the substrate SS2 and the element arrangement region R1 on the adhesive resin layer 50 formed on the surface TRt of the transfer substrate TR1. The relationship with the position (in other words, the position of the plurality of first inorganic light emitting elements 21) is adjusted.

The functions of the stage 61, the stage 62, the image sensor 71, and the control device 72 have already been explained, so a redundant explanation will be omitted. In this step, the image sensor 71 images, for example, one or more of the plurality of second inorganic light emitting elements 22 as an alignment mark on the substrate SS2 side, and outputs image data to the control device 72. Further, the image sensor 71 images a plurality of metal patterns MP as alignment marks on the transfer substrate TR1 side, and outputs image data to the control device 72. The control device 72 that has acquired the image data from the image sensor 71 determines the position of the metal pattern MP based on the position information of the stage 62 when the image sensor 71 imaged the metal pattern MP and the analysis result of the image data of the metal pattern MP. calculate. Similarly, the control device 72 determines whether the second inorganic light emitting element 22 is suitable for the second inorganic light emitting element 22 based on the position information of the stage 61 when the image sensor 71 images the second inorganic light emitting element 22 and the analysis result of the image data of the second inorganic light emitting element 22. Calculate the position of Then, based on the positional information of the metal pattern MP and the positional information of the second inorganic light emitting element 22, at least one of the stage 61 and the stage 62 is moved along the XY plane to place it on a preset transfer position. Adjustment is made so that each of the plurality of second inorganic light emitting elements 22 is positioned.

In this step, if there is no metal pattern MP as an alignment mark on the transfer substrate TR1, in the second alignment step, one of the plurality of first inorganic light emitting elements 21 already pasted on the adhesive resin layer 50 can be used as an alignment mark. However, in this case, since the positional accuracy in the process of pasting the first inorganic light emitting element 21 is affected, the positioning accuracy is lowered compared to the first positioning process.

On the other hand, in the case of this embodiment, since the plurality of metal patterns MP are used as alignment marks in the second alignment process, the second alignment process can be performed with the same accuracy as the first alignment process. As described above, according to the present embodiment, multiple types of LED elements 20 can be individually attached to the adhesive resin layer 50 with high precision, so that high-density mounting in which the distance between adjacent LED elements 20 is narrow is possible. can be accommodated. High-density mounting of the LED elements 20 contributes to improving the resolution of the display device or reducing the size of the display device.

<Second pasting process>
FIG. 16 is a cross-sectional view schematically showing the second pasting step shown in FIG. 5. In the second attachment step, as shown in FIG. 16, each of the plurality of second inorganic light emitting elements 22 is attached to the adhesive resin layer 50 on the transfer substrate TR1.

In the second alignment process described above, when the distance between the stage 61 and the stage 62 is brought closer after alignment in the direction along the XY plane, the positions are placed on the surface SS2t of the substrate SS2. Each of the plurality of second inorganic light emitting elements 22 approaches the transfer substrate TR1. When the distance between the substrate SS2 and the transfer substrate TR1 is further reduced, a portion of each of the plurality of second inorganic light emitting elements 22 is adhered to the adhesive resin layer 50.

<Second holding substrate peeling process>
Next, the second holding substrate peeling process shown in FIG. 5 will be explained. FIG. 17 is a cross-sectional view schematically showing a state in which the holding substrate is peeled off from a plurality of second inorganic light emitting elements in the second holding substrate peeling step shown in FIG. In the second holding substrate peeling step, as shown in FIG. 17, after the second holding substrate pressing step, the substrate SS2 and the plurality of second inorganic light emitting elements 22 are peeled off.

The method of peeling off the close contact interface between the surface SS2t of the substrate SS2, which is the holding substrate, and the plurality of second inorganic light emitting elements 22 is the same as the first holding substrate peeling process explained using FIG. 13, for example, by laser lift-off. A technique called can be used. Since the details of the laser lift-off have already been explained, illustration and redundant explanation will be omitted. Through this step, as shown in FIG. 17, each of the plurality of second inorganic light emitting elements 22 is peeled off from the substrate SS2, and the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements are placed on the transfer substrate TR1. A structure to which 22 is attached is obtained.

<Third alignment process>
FIG. 18 is a cross-sectional view schematically showing the third alignment step shown in FIG. 5. In the third alignment step shown in FIG. 5, as shown in FIG. 18, the substrate SS3 and the transfer substrate TR1 are aligned. At the start of this process, a plurality of first inorganic light emitting elements 21 and a plurality of second inorganic light emitting elements 22 have already been pasted on the adhesive resin layer 50 of the transfer substrate TR1. In the example shown in FIG. 18, the alignment mark is photographed by the image sensor 71 with the substrate SS3 held on the stage 61 and the transfer substrate TR1 held on the stage 62 facing each other, and the position of this alignment mark is Based on the information, the substrate SS3 and the transfer substrate TR1 are aligned. Specifically, the positions of each of the plurality of third inorganic light emitting elements 23 formed on the surface SS3t of the substrate SS3 and the element arrangement region R1 on the adhesive resin layer 50 formed on the surface TRt of the transfer substrate TR1. The relationship with the position (in other words, the position of the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements 22) is adjusted.

The functions of the stage 61, the stage 62, the image sensor 71, and the control device 72 have already been explained, so a redundant explanation will be omitted. In this step, the image sensor 71 images, for example, one or more of the plurality of third inorganic light emitting elements 23 as an alignment mark on the substrate SS3 side, and outputs image data to the control device 72. Further, the image sensor 71 images a plurality of metal patterns MP as alignment marks on the transfer substrate TR1 side, and outputs image data to the control device 72. The control device 72 that has acquired the image data from the image sensor 71 determines the position of the metal pattern MP based on the position information of the stage 62 when the image sensor 71 imaged the metal pattern MP and the analysis result of the image data of the metal pattern MP. calculate. Similarly, the control device 72 determines whether or not the third inorganic light emitting element 23 is the third inorganic light emitting element 23 based on the position information of the stage 61 when the image sensor 71 images the third inorganic light emitting element 23 and the analysis result of the image data of the third inorganic light emitting element 23. Calculate the position of Then, based on the position information of the metal pattern MP and the position information of the third inorganic light emitting element 23, at least one of the stage 61 and the stage 62 is moved along the XY plane to place it on a preset transfer position. Adjustment is made so that each of the plurality of third inorganic light emitting elements 23 is positioned.

As described in the explanation of the second alignment process, in this embodiment, the plurality of metal patterns MP are used as alignment marks in the third alignment process, so Three alignment steps can be performed. According to the present embodiment, multiple types of LED elements 20 can be individually attached to the adhesive resin layer 50 with high precision, so it is possible to support high-density mounting in which the distance between adjacent LED elements 20 is narrow. can. High-density mounting of the LED elements 20 contributes to improving the resolution of the display device or reducing the size of the display device.

<Third pasting process>
FIG. 19 is a cross-sectional view schematically showing the third pasting step shown in FIG. 5. In the third attachment step, as shown in FIG. 19, each of the plurality of third inorganic light emitting elements 23 is attached to the adhesive resin layer 50 on the transfer substrate TR1.

In the third alignment process described above, when the distance between the stage 61 and the stage 62 is brought closer after alignment in the direction along the X-Y plane, the positions are placed on the surface SS3t of the substrate SS3. Each of the plurality of third inorganic light emitting elements 23 approaches the transfer substrate TR1. When the distance between the substrate SS3 and the transfer substrate TR1 is further reduced, a portion of each of the plurality of third inorganic light emitting elements 23 is adhered to the adhesive resin layer 50.

<Third holding substrate peeling process>
Next, the third holding substrate peeling process shown in FIG. 5 will be explained. FIG. 20 is a cross-sectional view schematically showing a state in which the holding substrate is peeled off from a plurality of third inorganic light emitting elements in the third holding substrate peeling step shown in FIG. In the third holding substrate peeling step, as shown in FIG. 20, after the third holding substrate pressing step, the substrate SS3 and the plurality of third inorganic light emitting elements 23 are peeled off.

The method of peeling off the close contact interface between the surface SS3t of the substrate SS3, which is the holding substrate, and the plurality of third inorganic light emitting elements 23 is the same as the first holding substrate peeling step explained using FIG. 13, such as laser lift-off. A technique called can be used. Since the details of the laser lift-off have already been explained, illustration and redundant explanation will be omitted. Through this step, as shown in FIG. 20, each of the plurality of third inorganic light emitting elements 23 is peeled off from the substrate SS3, and the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements are placed on the transfer substrate TR1. 22 and a structure to which a plurality of third inorganic light emitting elements 23 are attached is obtained.

<Second transfer process>
Next, the second transfer process shown in FIG. 5 will be explained. 21 to 23 are cross-sectional views showing each step included in the second transfer step shown in FIG. 5. In the second transfer step, first, as shown in FIG. 21, the transfer substrate TR1 and the transfer substrate TR2 are aligned. The transfer substrate TR2 shown in FIG. 21 has the same structure as the transfer substrate TR1, except that the adhesive force of the adhesive resin layer 51 is higher than the adhesive force of the adhesive resin layer 50 of the transfer substrate TR1. For example, metal pattern MP and metal pattern MP2 shown in FIG. 21 are made of the same metal material and have the same shape.

In the second transfer step, each of the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are collectively transferred onto the transfer substrate TR2. Therefore, if the positioning of the plurality of LED elements 20 has already been performed with high precision in the first transfer process, the position of the plurality of LED elements 20 can be adjusted in the second transfer process without performing high-precision positioning. The relationship is maintained. However, in order to reliably mount each of the plurality of LED elements 20 onto the terminals of the array board in the next array board mounting process, the first alignment process, the second alignment process, and the third alignment process are also performed in this process. It is preferable to perform highly accurate positioning in the same way as in the positioning step, and maintain the positional relationship between the plurality of LED elements 20 attached to the transfer substrate TR2 and the plurality of metal patterns MP2 as alignment marks with high precision. .

Therefore, in the case of this embodiment, the second transfer step includes an alignment step of aligning the transfer substrate TR1 and the transfer substrate TR2. As shown in FIG. 21, in the alignment process, the image sensor 71 images a plurality of metal patterns MP as alignment marks on the transfer substrate TR1 side held on the stage 61, and outputs image data to the control device 72. do. Further, the image sensor 71 images the plurality of metal patterns MP2 as alignment marks on the transfer substrate TR2 side, and outputs image data to the control device 72. The control device 72 that has acquired the image data from the image sensor 71 determines the position of the metal pattern MP2 based on the position information of the stage 62 when the image sensor 71 imaged the metal pattern MP2 and the analysis result of the image data of the metal pattern MP2. calculate. Similarly, the control device 72 calculates the position of the metal pattern MP from the position information of the stage 61 when the image sensor 71 images the metal pattern MP and the analysis result of the image data of the metal pattern MP. Then, based on the positional information of the metal pattern MP and the positional information of the plurality of LED elements 20, at least one of the stage 61 and the stage 62 is moved along the XY plane, and a plurality of Adjust so that each of the LED elements 20 is positioned.

In addition, as shown in FIG. 22, the second transfer process is performed after the alignment process, in which each of the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are It includes a pasting step of pasting a portion (the N-type semiconductor layer 24 or the modified buffer layer 29 described using FIG. 7) to the adhesive resin layer 51 pasted onto the surface TRt of the transfer substrate TR2. In addition, as shown in FIG. 23, the second transfer process is performed after the pasting process, in which each of the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are This includes a peeling step of peeling off the adhesive resin layer 50 of the transfer substrate TR1. The adhesive strength (in other words, adhesive strength) of the adhesive resin layer 51 is higher than the adhesive strength of the adhesive resin layer 50. Therefore, as shown in FIG. 23, when the distance between the transfer substrate TR1 and the transfer substrate TR2 is increased, the LED element 20 is peeled off from the adhesive resin layer 50, which has relatively low adhesive strength. Through this step, as shown in FIG. 23, a structure in which a plurality of first inorganic light emitting elements 21, a plurality of second inorganic light emitting elements 22, and a plurality of third inorganic light emitting elements 23 are pasted on the transfer substrate TR2. You can get things. The plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 mounted on the transfer substrate TR2 are mounted on the transfer substrate TR1 before the start of the second transfer process. The plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 pasted on are upside down. In the case of this embodiment, the electrode 20E of the LED element 20 shown in FIG. 7 is arranged on the opposite side to the surface facing the adhesive resin layer 51 shown in FIG. 23.

<Array board mounting process>
Next, the array substrate mounting process shown in FIG. 5 will be described. 24 to 26 are cross-sectional views showing each process included in the array substrate mounting process shown in FIG. 5. In the array substrate mounting process, first, as shown in FIG. 24, the transfer substrate TR2 and the array substrate SUB1 are aligned.

In the array substrate mounting step, each of the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are collectively mounted on the array substrate SUB1 shown in FIG. 10. At this time, it is necessary to ensure that the plurality of electrodes 20E shown in FIG. 7 and the plurality of terminals 30 shown in FIG. 10 face each other, so it is necessary to perform highly accurate positioning. Therefore, in this embodiment, a metal pattern MP3 is formed on the surface SUBt of the array substrate SUB1. The metal pattern MP3 is a pattern used as an alignment mark in the array substrate mounting process. The metal pattern MP3 is made of the same metal material and has the same shape as the metal pattern MP2 of the transfer substrate TR2, for example. Further, the metal pattern MP3 is arranged at a position facing the metal pattern MP2, for example, in the alignment process described below.

In the case of this embodiment, the array substrate mounting step includes an alignment step of aligning the transfer substrate TR2 and the array substrate SUB1. As shown in FIG. 24, in the alignment step, the image sensor 71 images a plurality of metal patterns MP2 as alignment marks on the transfer substrate TR2 side held on the stage 61, and outputs image data to the control device 72. do. Further, the image sensor 71 images a plurality of metal patterns MP3 as alignment marks on the array substrate SUB1 side, and outputs image data to the control device 72. The control device 72 that has acquired the image data from the image sensor 71 determines the position of the metal pattern MP3 based on the position information of the stage 62 when the image sensor 71 imaged the metal pattern MP3 and the analysis result of the image data of the metal pattern MP3. calculate. Similarly, the control device 72 calculates the position of the metal pattern MP2 from the position information of the stage 61 when the image sensor 71 images the metal pattern MP2 and the analysis result of the image data of the metal pattern MP2. Then, based on the position information of the metal pattern MP2 and the position information of the plurality of LED elements 20, at least one of the stage 61 and the stage 62 is moved along the The LED elements 20 are adjusted so that each of the plurality of LED elements 20 is located at a position facing the terminal 30 of.

In the array substrate mounting process, after the alignment process, as shown in FIG. This includes a bonding process for electrically connecting through the wire. In the bonding step, the electrodes 20E (see FIG. 7) of the LED elements 20 and the terminals 30 of the array substrate SUB1 are electrically connected via the conductive bonding material 40. In this step, the conductive bonding material 40 is melted by applying heat, and the electrode 20E and the terminal 30 are bonded via the conductive bonding material 40. As a heat source for heating the conductive bonding material 40, for example, a method of irradiating laser light can be exemplified. As described above, when a heating process is included, there is a concern that the resin alignment mark may be deformed. On the other hand, in the case of this embodiment, each of the metal pattern MP2 of the transfer substrate TR2 and the metal pattern MP3 of the array substrate SUB1 is made of metal, and is formed on a glass base material (glass substrate) that is less thermally deformed than resin. Since the metal patterns MP2 and MP3 are film-formed, deformation can be prevented even if a heating process is included.

Further, as shown in FIG. 26, in the array substrate mounting process, after the bonding process, each of the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are transferred. This includes a peeling step of peeling off the adhesive resin layer 51 of the substrate TR2. At the start of this process, each of the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 have already been joined to the terminals 30 of the array substrate SUB1. Therefore, as shown in FIG. 26, when the distance between the transfer substrate TR2 and the array substrate SUB1 is increased, the LED element 20 is peeled off from the adhesive resin layer 51. Through this step, as shown in FIG. 26, a structure in which a plurality of first inorganic light emitting elements 21, a plurality of second inorganic light emitting elements 22, and a plurality of third inorganic light emitting elements 23 are mounted on the array substrate SUB1 is created. can get.

Note that in the example shown in FIG. 5, an embodiment has been described in which three types of LED elements are sequentially mounted, but the types of LED elements to be mounted are not limited to three types. For example, if it is sufficient to mount one type of LED elements all at once, it is possible to omit the first transfer step and second transfer step shown in FIG. 5 and mount them directly from the LED holding substrate to the array substrate. can. Further, for example, in the case of a method of manufacturing a display device of a type in which two types of LED elements are mounted, the steps from the third alignment step to the third holding substrate peeling step shown in FIG. 5 can be omitted. In addition, in the case of a method for manufacturing a display device in which four or more types of LED elements are mounted, after the third holding substrate peeling step shown in FIG. This can be obtained by repeatedly performing the alignment process for mounting the LED elements, the pasting process, and the holding substrate peeling process.

<Modified example of alignment>
Next, a modification of the above alignment process will be described. FIG. 27 is a plan view showing a modification of the substrate shown in FIG. 6. In each of the first alignment process explained using FIG. 11, the second alignment process explained using FIG. 15, and the third alignment process explained using FIG. A method has been described in which an alignment mark is not formed on each of the SS3 and a part of the plurality of LED elements 20 is used as an alignment mark. However, from the viewpoint of further improving alignment accuracy, it is preferable that alignment marks are also formed on each of the substrates SS1, SS2, and SS3.

In the example shown in FIG. 27, an alignment mark AM1 is formed on the surface SS1t of the substrate SS1. The alignment mark AM1 is formed around a region where a plurality of LED elements 20 are arranged. Although the example shown in FIG. 27 shows an example in which two alignment marks AM1 are formed, the number of alignment marks AM1 is not limited to two, and may be one. However, preferably two or more alignment marks AM1 are formed. The alignment mark AM1 is, for example, a metal pattern made of metal. Similarly, an alignment mark AM2 is formed on the surface SS2t of the substrate SS2. An alignment mark AM3 is formed on the surface SS3t of the substrate SS3. The material, shape, formation position, and number of formation marks of alignment mark AM2 and alignment mark AM3 are the same as those of alignment mark AM1, so a redundant explanation will be omitted.

In the case of this modification, the first alignment step, the second alignment step, and the third alignment step shown in FIG. 5 are different from the above-described embodiment. In the first alignment step, the substrate SS1 and the transfer substrate TR1 are aligned based on the positional information of the plurality of metal patterns MP shown in FIG. 11 and the positional information of the alignment mark AM1 of the substrate SS1 shown in FIG. 27. Similarly, in the second alignment step, the substrate SS2 and the transfer substrate TR1 are aligned based on the positional information of the plurality of metal patterns MP shown in FIG. 15 and the positional information of the alignment mark AM2 of the substrate SS2 shown in FIG. I do. Similarly, in the third alignment step, the substrate SS3 and the transfer substrate TR1 are aligned based on the position information of the plurality of metal patterns MP shown in FIG. 18 and the position information of the alignment mark AM3 of the substrate SS3 shown in FIG. I do.

In the case of this modification, by providing an alignment mark separately from the LED element 20, alignment accuracy can be improved.

<Modified example of alignment mark>
Next, the shape of the pattern used as an alignment mark in the above-described alignment process will be explained. FIG. 28 is a plan view showing a modification to FIG. 8. In the modification shown in FIG. 28, the transfer substrate TR1 is similar to FIG. Different from the example shown.

As shown in FIG. 28, the plurality of metal patterns MP include a first metal pattern MPP1 and a second metal pattern MPP2 having a planar shape different from that of the first metal pattern MPP1. In the example shown in FIG. 28, the first metal pattern MPP1 is circular, and the second metal pattern MPP2 is L-shaped. When a plurality of metal patterns MP having different shapes are provided in this way, the orientations of the electrodes of the plurality of LED elements can be recognized in the alignment process. For example, if a rule is set in advance that an anode electrode is placed on the first metal pattern MPP1 side and a cathode electrode is placed on the second metal pattern MPP2 side, image data of a plurality of metal patterns MP is acquired in the alignment process. Thus, for example, the control device 72 shown in FIG. 11 can adjust the orientation of the electrodes so that they are oriented in the correct direction. Note that the orientation of the electrodes formed on each of the substrate SS1, the substrate SS2, and the substrate SS3 shown in FIG. 6 can be identified by a direction identification section called an oriental flat (OF).

FIG. 29 is an enlarged plan view schematically showing an image in the alignment process when the alignment mark formed on the substrate shown in FIG. 27 and the metal pattern formed on the transfer substrate shown in FIG. 8 have different shapes. It is a diagram. In the case of the modification shown in FIG. 29, a plurality of metal patterns MP formed on the transfer substrate TR1 (see FIG. 8), alignment marks AM1, and AM2 and AM3 have mutually different shapes. Note that "different shapes" include not only cases where the shapes themselves are different, such as a circle and a square, but also cases where the sizes of the patterns are different, as shown in FIG.

In the case of this modification, the image of the metal pattern MP and the mark of the alignment mark AM1 are captured at the same timing by the image sensor 71 shown in FIG. 11, for example. At this time, alignment is performed at a position where the metal pattern MP and the alignment mark AM1 overlap each other as shown in FIG. 29. In the case of this modification, alignment can be performed even when a plurality of metal patterns MP are arranged close to each other. However, from the viewpoint of improving alignment accuracy, as in the examples shown in FIGS. 8 and 28, by arranging a plurality of metal patterns MP at the corners of the peripheral region R2, the distance between the metal patterns MP can be reduced. It is preferable to make it large.

Although the embodiment and typical modified examples have been described above, the above-described technology is applicable to various modified examples other than the illustrated modified examples. For example, the above-described modifications may be combined.

Further, for example, in the manufacturing process shown in FIG. 5, a method has been described in which a plurality of LED elements are sequentially mounted on one transfer substrate TR1 from a sapphire substrate. However, if the arrangement pitch of the LED elements 20 formed on the sapphire substrate is different from the arrangement pitch of the LED elements 20 when mounted on the array substrate, in the first transfer step, the first inorganic light emitting element 21, the first The second inorganic light emitting element 22 and the third inorganic light emitting element 23 may be transferred to independent transfer substrates. In the case of this modification, in the second transfer process, by performing each process from the first alignment process to the third holding substrate peeling process shown in FIG. A structure to which the light emitting element 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are attached is obtained. The transfer substrate used in this modification may be the same as the transfer substrate shown in FIGS. 8 and 9. However, the adhesive force of the adhesive resin layer needs to be lower than the adhesive force of the adhesive resin layer 50 shown in FIG.

It is understood that those skilled in the art will be able to come up with various changes and modifications within the scope of the idea of the present invention, and these changes and modifications will also fall within the scope of the present invention. For example, the gist of the present invention may be obtained by adding, deleting, or changing the design of components, or adding, omitting, or changing conditions to the above-mentioned embodiments as appropriate by a person skilled in the art. It is within the scope of the present invention as long as it has the following.

INDUSTRIAL APPLICATION This invention can be utilized for a display device and an electronic device in which a display device is incorporated.

5 Control circuit 6 Drive circuit 10 Substrate 10b, 10f Surface 11 Inorganic insulating layer 12, 13 Organic insulating layer 20, 20M1 LED element 20b, 20f Surface 20E Electrode 20EA Anode electrode 20EK Cathode electrode 21 First inorganic light emitting element 22 Second inorganic light emitting element Element 23 Third inorganic light emitting element 24 N-type semiconductor layer 25 Active layer 26 P-type semiconductor layer 27a Transparent electrode layer 27b Seed layer 27c Metal electrode layer 28 Passivation film 29 Buffer layer 30, 30H, 30L, 31, 32, 33 Terminal 40 Conductive bonding material 50, 51 Adhesive resin layer 50b, 50t Surfaces 61, 62 Stages 61h, 62h Holding surface 71 Image sensor 72 Control device AM1, AM2, AM3 Alignment mark BCT Output switch Cad Auxiliary capacitor Cs Holding capacitor DA Display area DRT Drive Transistor DSP1 Display device GL Scanning signal line GLA Scanning signal line GLB Scanning signal line GLR Reset wiring Gsb Control signal Gsr Control signal Gss Control signal MP, MP2, MP3 Metal pattern MPP1 First metal pattern MPP2 Second metal pattern OF Oriental flat PFA Periphery Area PIX Pixel PVD Potential PVS Potential R1 Element placement area R2 Peripheral area RST Reset switch SS1, SS2, SS3 Substrate SS1b Back surface SS1t, SS2t, SS3t Surface (element holding surface)
SST Pixel switch SUB1 Array substrate SUBb, SUBt Surfaces TR1, TR2 Transfer substrates TRb, TRt Surfaces TRs1, TRs2, TRs3, TRs4 Side UVL Ultraviolet laser light VL Video signal line Vsg Video signal

Claims (9)

(a) A first substrate having a first surface, on which a plurality of first inorganic light emitting elements are arranged in a matrix, and a glass substrate, on which an adhesive resin layer is formed. a second substrate having a second surface;
(b) aligning the first substrate and the second substrate;
(c) after the step (b), attaching each of the plurality of first inorganic light emitting elements to the adhesive resin layer on the second substrate;
(d) After the step (c), separating each of the plurality of first inorganic light emitting elements from the first substrate by increasing the distance between the first substrate and the second substrate;
including;
A plurality of metal patterns that are visible through the adhesive resin layer are formed between the second surface of the second substrate and the adhesive resin layer,
In the step (b), the first substrate and the second substrate are aligned based on position information of the plurality of metal patterns. In claim 1,
alignment marks are formed on the first surface of the first substrate;
In the step (b), the first substrate and the second substrate are aligned based on the positional information of the plurality of metal patterns and the positional information of the alignment mark of the first substrate. . In claim 2,
The method for manufacturing a display device, wherein the plurality of metal patterns formed on the second substrate and the alignment mark formed on the first substrate have mutually different shapes. In claim 1,
(e) preparing a third substrate having a third surface, on which a plurality of second inorganic light emitting elements are arranged in a matrix;
(f) after the step (d), aligning the third substrate with the second substrate to which the plurality of first inorganic light emitting elements are attached;
(g) after the step (f), attaching each of the plurality of second inorganic light emitting elements to the adhesive resin layer on the second substrate;
(h) After the step (g), separating each of the plurality of second inorganic light emitting elements from the third substrate by increasing the distance between the third substrate and the second substrate;
further including;
In the step (f), the third substrate and the second substrate are aligned based on position information of the plurality of metal patterns. In claim 4,
alignment marks are formed on the third surface of the third substrate;
In the step (f), the third substrate and the second substrate are aligned based on the positional information of the plurality of metal patterns and the positional information of the alignment mark of the third substrate. . In claim 4,
(j) preparing a fourth substrate having a fourth surface on which a plurality of third inorganic light emitting elements are arranged in a matrix;
(k) After the step (h), the fourth substrate is aligned with the second substrate to which the plurality of first inorganic light emitting elements and the plurality of second inorganic light emitting elements are attached. The process of doing
(m) after the step (k), attaching each of the plurality of third inorganic light emitting elements to the adhesive resin layer on the second substrate;
(n) After the step (m), separating each of the plurality of third inorganic light emitting elements from the fourth substrate by increasing the distance between the fourth substrate and the second substrate;
further including;
In the step (k), the fourth substrate and the second substrate are aligned based on position information of the plurality of metal patterns. In claim 6,
alignment marks are formed on the fourth surface of the fourth substrate;
In the step (k), the fourth substrate and the second substrate are aligned based on the positional information of the plurality of metal patterns and the positional information of the alignment mark of the fourth substrate. . 2. The method of manufacturing a display device according to claim 1, wherein the plurality of metal patterns include a first metal pattern and a second metal pattern having a planar shape different from that of the first metal pattern. In any one of claims 1 to 8,
In plan view, the second substrate is
an element placement area where the plurality of first inorganic light emitting elements are pasted;
a peripheral area around the element placement area;
has
The method for manufacturing a display device, wherein the plurality of metal patterns are arranged in the peripheral region.

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