CN113851388A

CN113851388A - Method for manufacturing display device

Info

Publication number: CN113851388A
Application number: CN202110659144.8A
Authority: CN
Inventors: 山田一幸
Original assignee: Japan Display Inc
Current assignee: Japan Display Inc
Priority date: 2020-06-26
Filing date: 2021-06-15
Publication date: 2021-12-28
Also published as: JP2022007774A

Abstract

The purpose of the present invention is to increase the flux when an LED chip is mounted on a circuit board by laser irradiation. The manufacturing method of the display device includes the following processes: preparing a 1 st substrate, the 1 st substrate having, for each pixel, a drive circuit for driving an LED chip and a connection electrode connected to the drive circuit; a 2 nd substrate having a plurality of LED chips arranged on the 1 st substrate such that each connection electrode faces each LED chip; the 1 st laser beam is irradiated through a light-shielding mask having a plurality of openings, whereby the connection electrodes and the LED chips are collectively bonded.

Description

Method for manufacturing display device

Technical Field

One embodiment of the present invention relates to a method for manufacturing a display device. In particular, the present invention relates to a method for manufacturing a display device having an led (light Emitting diode) chip mounted thereon.

Background

In recent years, as a next-generation display device, development of an LED display in which a minute LED chip is mounted on each pixel has been advanced. An LED display has a structure in which a plurality of LED chips are mounted on a circuit substrate constituting a pixel array. The circuit board has a drive circuit for causing the LED to emit light at a position corresponding to each pixel. The driving circuits are electrically connected to the LED chips, respectively.

There are various methods for mounting a plurality of LED chips on a circuit substrate. For example, a method of removing only the support substrate after bonding the LED chip provided on the support substrate to the circuit substrate is known. Patent document 1 describes a technique of attaching an LED chip to an electrode on a circuit board and then removing only a supporting substrate by a method called laser lift-off.

[ patent document 1 ] specification of U.S. Pat. No. 10096740

The above-mentioned prior art describes a technique of selectively irradiating a laser beam by combining a laser beam having a large irradiation area with a light-shielding mask in order to increase the laser beam irradiation flux (through put) at the time of laser lift-off. However, the techniques described in the above-mentioned prior art only consider improving the throughput of the laser lift-off process. Therefore, there is room for improvement in a process other than the process of removing the support substrate.

Disclosure of Invention

One of the objects of the present invention is to improve the flux when an LED chip is mounted on a circuit board by laser irradiation.

A method for manufacturing a display device according to one embodiment of the present invention includes: preparing a 1 st substrate, the 1 st substrate having, for each pixel, a drive circuit for driving an LED chip and a connection electrode connected to the drive circuit; a 2 nd substrate having a plurality of LED chips arranged on the 1 st substrate such that each connection electrode faces each LED chip; the 1 st laser beam is irradiated through a light-shielding mask having a plurality of openings, whereby the connection electrodes and the LED chips are collectively bonded.

Drawings

Fig. 1 is a flowchart showing a method for manufacturing a display device according to embodiment 1 of the present invention.

Fig. 2 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 1 of the present invention.

Fig. 3 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 1 of the present invention.

Fig. 4 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 5 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 6 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 7 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 8 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 9 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 10 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 11 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 12 is a cross-sectional view showing a method of manufacturing a display device according to embodiment 1 of the present invention.

Fig. 13 is a plan view showing a schematic configuration of a display device according to embodiment 1 of the present invention.

Fig. 14 is a block diagram showing a circuit configuration of the display device according to embodiment 1 of the present invention.

Fig. 15 is a circuit diagram showing a configuration of a pixel circuit of a display device according to embodiment 1 of the present invention.

Fig. 16 is a cross-sectional view showing the structure of a pixel of the display device according to embodiment 1 of the present invention.

Fig. 17 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 18 is a sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 19 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 20 is a sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 21 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 22 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 23 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Fig. 24 is a cross-sectional view showing a method for manufacturing a display device according to embodiment 2 of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in various ways within a scope not departing from the gist thereof. The present invention is not limited to and is explained as the contents of the following exemplary embodiments. In order to make the description more clear, the drawings may schematically show the width, thickness, shape, and the like of each part as compared with the actual case. However, the drawings are only examples and do not limit the explanation of the present invention.

In the description of the embodiments of the present invention, the direction from the circuit board to the LED chip is referred to as "up" and the opposite direction is referred to as "down". However, the expressions "at … …" or "at … …" merely indicate the relationship between the elements. For example, the expression that the LED chip is disposed on the circuit board includes a case where other components are present between the circuit board and the LED chip. Further, the expression "at … …" or "at … …" includes not only a case where the elements overlap in a plan view, but also a case where the elements do not overlap.

In describing the embodiments of the present invention, the same reference numerals are given to elements having the same functions as those of the elements already described, or symbols such as latin letters are added to the same reference numerals, and the description thereof may be omitted. In the case where it is necessary to distinguish RGB colors for a certain element, R, G or a B symbol is added to the label indicating the element to distinguish the element. However, when the element is not described by distinguishing each color of RGB, only the reference numeral indicating the element is used for description.

< embodiment 1 >

[ method for manufacturing display device ]

Fig. 1 is a flowchart illustrating a method for manufacturing a display device 10 according to an embodiment of the present invention. Fig. 2 to 12 are cross-sectional views showing a method of manufacturing the display device 10 according to the embodiment of the present invention. Hereinafter, a method for manufacturing the display device 10 will be described with reference to fig. 1. At this time, the cross-sectional structure in each manufacturing step will be described with reference to fig. 2 to 12.

First, in step S11 of fig. 1, a circuit board 100 having a driving circuit 102 for driving an LED chip and a connection electrode 103 connected to the driving circuit 102 is prepared for each pixel. The circuit substrate 100 has a region corresponding to a plurality of pixels. As shown in fig. 2, the circuit board 100 includes a driving circuit 102 for driving an LED chip corresponding to each pixel on a supporting substrate 101 having an insulating surface. As the support substrate 101, for example, a glass substrate, a resin substrate, a ceramic substrate, or a metal substrate can be used. Each of the driving circuits 102 is formed of a plurality of Thin Film Transistors (TFTs). The connection electrodes 103 are disposed in the pixels and connected to the drive circuit 102. The detailed structure of the circuit board 100 will be described later.

In this embodiment, an example in which the driver circuits 102 and the connection electrodes 103 are formed on the support substrate 101 by a thin film formation technique is shown, but the present invention is not limited to this example. For example, a substrate (so-called active array substrate) in which the driver circuit 102 is formed on the support substrate 101 may be obtained as a finished product from a third party. In this case, the connection electrode 103 may be formed on the obtained substrate. In the present embodiment, a circuit board 100 on which a flip-chip type LED chip 202 (see fig. 16) is mounted will be described. The LED chip 202 is not limited to a flip chip type example having two electrodes on a surface facing the circuit board 100. For example, the LED chip 202 may have an anode electrode (or a cathode electrode) on a side close to the circuit board 100 and a cathode electrode (or an anode electrode) on a side far from the circuit board 100. That is, the LED chip 202 may be a surface up type LED chip having a structure in which a light-emitting layer is sandwiched between an anode electrode and a cathode electrode.

In this embodiment, an example in which nine connection electrodes 103 are arranged on the support substrate 101 is shown, but in this embodiment, since the flip-chip type LED chip 202 is mounted, at least two connection electrodes 103 are actually formed for each pixel. The flip-chip type LED chip has a terminal electrode connected to the N-type semiconductor and a terminal electrode connected to the P-type semiconductor. Therefore, in the present embodiment, since one LED chip is disposed for each pixel, at least two connection electrodes 103 are disposed for each pixel. However, when the above-described normal-type LED chip is used as the LED chip 202, one connection electrode 103 may be formed for each pixel on the support substrate 101.

The connection electrode 103 is made of, for example, a conductive metal material. In the present embodiment, tin (Sn) is used as the metal material. However, the present invention is not limited to this example, and other metal materials that can form a eutectic alloy with the terminal electrode on the LED chip side described later may be used. The thickness of the connection electrode 103 may be, for example, in the range of 0.2 μm to 5 μm (preferably 1 μm to 3 μm).

Next, in step S12 of fig. 1, the element substrate 200 having the plurality of LED chips 202R is disposed on the circuit substrate 100 such that the connection electrodes 103 face the LED chips 202R. In the present embodiment, the element substrate 200 is a substrate in which a plurality of LED chips 202R emitting red light are provided on a semiconductor substrate 201. In this embodiment, a sapphire substrate is used as the semiconductor substrate 201. The LED chip 202R is composed of a semiconductor material containing gallium nitride grown on a sapphire substrate. The combination of the material constituting the semiconductor substrate 201 and the material constituting the LED chip 202R may be determined as appropriate in accordance with the emission color.

In the present embodiment, an example in which each LED chip 202R is provided on the semiconductor substrate 201 is shown, but the present invention is not limited to this example, and each LED chip 202R may be provided on a glass substrate or a resin substrate. That is, each LED chip 202R may be transferred using a glass substrate or a resin substrate as a carrier substrate.

In the present embodiment, each LED chip 202R is disposed on the connection electrode 103 disposed in the pixel corresponding to red among the plurality of connection electrodes 103. Each LED chip 202 includes a terminal electrode 203R. Therefore, in a state where the element substrate 200 is disposed on the circuit substrate 100, the connection electrodes 103 face the terminal electrodes 203R. At this time, the element substrate 200 may be temporarily fixed by providing an adhesive layer (not shown) between each connection electrode 103 and each terminal electrode 203R.

Next, in step S13 of fig. 1, as shown in fig. 4, the plurality of connection electrodes 103 and the plurality of LED chips 202R are collectively bonded by irradiation of the 1 st laser beam 40 through the light-shielding mask 30. This step is a step of fusion-bonding the connection electrode 103 and the terminal electrode 203R by irradiation of the 1 st laser beam 40.

As the 1 st laser beam 40, a laser beam that is not absorbed by the semiconductor substrate 201 and the LED chip 202R but absorbed by the connection electrode 103 or the terminal electrode 203 is selected. In the present embodiment, for example, infrared light or near-infrared light can be used as the 1 st laser light 40. YAG laser or YVO may be used as the light source of the 1 st laser beam 40₄Solid state lasers such as laser. However, the 1 st laser light 40 may be a laser light having an appropriate wavelength selected according to the material constituting the semiconductor substrate 201 and the LED chip 202R. For example, in the case of using a semiconductor material that absorbs laser light having a shorter wavelength than infrared light, green laser light (green light) may be used.

By irradiation of the 1 st laser beam 40, an alloy layer 105 made of a eutectic alloy is formed between the connection electrode 103 and the terminal electrode 203R. As described above, in the present embodiment, the connection electrode 103 is made of tin (Sn). On the other hand, the terminal electrode 203R is made of gold (Au). That is, in the present embodiment, a layer made of an Sn — Au eutectic alloy is formed as the alloy layer 105. However, as the connection electrode 103 and the terminal electrode 203R, other metal materials may be used as long as they can form a eutectic alloy with each other.

By forming an alloy layer 105 made of a eutectic alloy between the connection electrode 103 and the terminal electrode 203R, the connection electrode 103 and the terminal electrode 203R are joined via the alloy layer 105. As a result, the LED chip 202R can be firmly mounted with respect to the connection electrode 103.

In the present embodiment, the light-shielding mask 30 having the plurality of openings 30a is used when the 1 st laser beam 40 is irradiated. The plurality of openings 30a are arranged in accordance with the pitch (the interval between pixels) of the pixel corresponding to red, the pixel corresponding to green, or the pixel corresponding to blue, for example. In the example shown in fig. 4, the openings 30a are arranged so as to correspond to the pitch of the pixels corresponding to red. That is, the position of each opening 30a corresponds to the position where the LED chip 202R is disposed.

In the present embodiment, as the 1 st laser beam 40, a rectangular laser beam having an irradiation area having a size including the plurality of openings 30a is used. In the case where the irradiation region of the 1 st laser beam 40 is narrower than the light-shielding mask 30, the entire light-shielding mask 30 can be irradiated with the laser beam by performing irradiation a plurality of times while moving the irradiation region of the laser beam.

The 1 st laser beam 40 irradiated to the light-shielding mask 30 passes through only the portion where the opening 30a is located. That is, by using the shadow mask 30, it is possible to use laser light having a wide irradiation area and to selectively irradiate the laser light. In the present embodiment, the 1 st laser beam 40 is selectively irradiated to the position where the LED chip 202R is disposed. That is, according to the present embodiment, the plurality of connection electrodes 103 and the plurality of LED chips 202R can be bonded together.

In addition, the size (area) of the opening 30a in a plan view may be set to a size that is sufficient to reliably bond the connection electrode 103 and the terminal electrode 203R. For example, the size of the opening 30a in a plan view may be smaller than the size of the LED chip 202R or the size of the connection electrode 103. The size of the opening 30a may be substantially the same as the size of the LED chip 202R, or may be slightly larger than the size of the LED chip 202R.

In the present embodiment, an example in which a laser beam whose irradiation region is rectangular is used as the 1 st laser beam 40 is shown, but the present invention is not limited to this example, and a laser beam whose irradiation region is linear (elongated) may be used. In this case, the light-shielding mask 30 is scanned with linear laser light, whereby the entire light-shielding mask 30 can be irradiated with laser light.

Next, in step S14 of fig. 1, as shown in fig. 5, the semiconductor substrate 201 is separated from the plurality of LED chips 202R by irradiation of the 2 nd laser beam 45 through the light-shielding mask 30. This step is a so-called laser lift-off step. Specifically, the step of irradiating the 2 nd laser beam 45 denatures the boundary portion between the semiconductor substrate 201 and the plurality of LED chips 202R and separates the plurality of LED chips 202R from the semiconductor substrate 201.

As the 2 nd laser light 45, a laser light that is not absorbed by the semiconductor substrate 201 and is absorbed by the semiconductor material constituting the LED chip 202R is selected. In the present embodiment, ultraviolet light is used as the 2 nd laser beam 45. YAG laser or YVO may be used as the light source of the 2 nd laser beam 45₄A solid laser such as a laser, or an excimer laser. However, as the 2 nd laser light 45, a laser light having an appropriate wavelength may be selected according to the materials constituting the semiconductor substrate 201 and the LED chip 202R. For example, in the case of using a semiconductor material that absorbs laser light of a longer wavelength than ultraviolet light, blue laser light (blue light) or green laser light (green light) may be used.

In the step shown in fig. 5, similarly to the irradiation of the 1 st laser beam 40 shown in fig. 4, a rectangular laser beam having an irradiation area having a size including the plurality of openings 30a is used as the 2 nd laser beam 45. In this case, when the irradiation area of the 2 nd laser beam 45 is narrower than the light-shielding mask 30, the irradiation may be performed a plurality of times while moving the irradiation area of the laser beam. In addition, not limited to this example, as the 2 nd laser beam 45, a laser beam whose irradiation region is linear (elongated shape) may be used, and the linear laser beam may be scanned on the light-shielding mask 30.

The 2 nd laser light 45 irradiated to the light-shielding mask 30 passes through only the portion where the opening 30a is located. That is, by using the shadow mask 30, selective laser irradiation can be performed while using laser light having a wide irradiation area. In the present embodiment, the 2 nd laser beam 45 is selectively irradiated to the position where the LED chip 202R is arranged. As a result, the surface layer portion (boundary portion with the semiconductor substrate 201) of the LED chip 202R is denatured, and the semiconductor substrate 201 can be separated from each LED chip 202R.

In addition, the size (area) of the opening 30a may be as large as the LED chip 202R can be reliably separated from the semiconductor substrate 201 in a plan view. For example, the size of the opening 30a in a plan view may be smaller than the size of the LED chip 202R. The size of the opening 30a may be substantially the same as the size of the LED chip 202R, or may be slightly larger than the size of the LED chip 202R.

After the irradiation of the 2 nd laser light 45, the semiconductor substrate 201 is separated from each LED chip 202R. Through the above steps, as shown in fig. 6, the LED chip 202R can be mounted on the circuit board 100.

After the state shown in fig. 6 is obtained, step S13 and step S14 shown in fig. 1 are repeated, and the LED chip 202G that emits light in green and the LED chip 202B that emits light in blue are mounted on the circuit board 100 in this order.

Specifically, as shown in fig. 7, the plurality of connection electrodes 103 and the plurality of LED chips 202G are collectively bonded by irradiation of the 1 st laser beam 40 through the light-shielding mask 30. The details of the process shown in fig. 7 are the same as those of the process shown in fig. 4. Then, as shown in fig. 8, the semiconductor substrate 201 is separated from the plurality of LED chips 202G by irradiation of the 2 nd laser beam 45 through the light-shielding mask 30. The details of the process shown in fig. 8 are the same as those of the process shown in fig. 5. Through these steps, the state shown in fig. 9 is obtained. In the state shown in fig. 9, an LED chip 202R emitting light in red and an LED chip 202G emitting light in green are mounted on the circuit board 100.

Further, as shown in fig. 10, the plurality of connection electrodes 103 and the plurality of LED chips 202B are collectively bonded by irradiation of the 1 st laser beam 40 through the light-shielding mask 30. The details of the process shown in fig. 10 are the same as those of the process shown in fig. 4. Then, as shown in fig. 11, the semiconductor substrate 201 is separated from the plurality of LED chips 202B by irradiation of the 2 nd laser beam 45 through the light-shielding mask 30. The details of the process shown in fig. 11 are the same as those of the process shown in fig. 5. Through these steps, the state shown in fig. 12 is obtained. In the state shown in fig. 12, an LED chip 202R emitting light in red, an LED chip 202G emitting light in green, and an LED chip 202B emitting light in blue are mounted on the circuit substrate 100.

As described above, in the present embodiment, the connection electrodes 103 on the circuit board 100 can be bonded to the LED chips 202R, 202G, and 202B together by using the light-shielding mask 30 and the 1 st laser beam 40 having a relatively wide irradiation area. Further, in the present embodiment, the light-shielding mask 30 and the 2 nd laser beam 45 having a relatively wide irradiation area are used, whereby the semiconductor substrate 201 can be separated together with the LED chips 202R, 202G, and 202B. Therefore, according to the present embodiment, the flux when the plurality of LED chips are mounted on the circuit board using laser irradiation can be increased.

[ constitution of display device ]

The structure of the display device 10 according to one embodiment of the present invention will be described with reference to fig. 13 to 16.

Fig. 13 is a plan view showing a schematic configuration of the display device 10 according to the embodiment of the present invention. As shown in fig. 13, the display device 10 includes a circuit board 100, a flexible printed circuit board 160(FPC160), and an IC chip 170. The display device 10 is divided into a display region 112, a peripheral region 114, and a terminal region 116.

The display region 112 is a region in which a plurality of pixels 110 including the LED chips 202 are arranged in the row direction (D1 direction) and the column direction (D2 direction). Specifically, in the present embodiment, the pixel 110R including the LED chip 202R, the pixel 110G including the LED chip 202G, and the pixel 110B including the LED chip 202B are arranged. The display area 112 functions as an area for displaying an image corresponding to a video signal.

The peripheral region 114 is a region around the display region 112. The peripheral region 114 is a region where a driving circuit (a data driving circuit 130 and a gate driving circuit 140 shown in fig. 14) for controlling a pixel circuit (a pixel circuit 120 shown in fig. 14) provided in each pixel 110 is provided.

The terminal region 116 is a region in which a plurality of wirings connected to the above-described drive circuit are concentrated. The flexible printed circuit board 160 is electrically connected to the plurality of wirings in the terminal region 116. A video signal (data signal) or a control signal output from an external device (not shown) is input to the IC chip 170 via a wiring (not shown) provided on the flexible printed circuit board 160. The IC chip 170 performs various signal processes on the image signal or generates a control signal necessary for display control. The video signal and the control signal output from the IC chip 170 are input to the display device 10 via the flexible printed circuit board 160.

[ Circuit configuration of display device 10 ]

Fig. 14 is a block diagram showing a circuit configuration of the display device 10 according to the embodiment of the present invention. As shown in fig. 14, in the display region 112, a pixel circuit 120 is provided corresponding to each pixel 110. In this embodiment, a pixel circuit 120R, a pixel circuit 120G, and a pixel circuit 120B are provided corresponding to the pixel 110R, the pixel 110G, and the pixel 110B, respectively. That is, in the display region 112, a plurality of pixel circuits 120 are arranged in the row direction (D1 direction) and the column direction (D2 direction).

Fig. 15 is a circuit diagram showing a configuration of a pixel circuit 120 of a display device 10 according to an embodiment of the present invention. The pixel circuit 120 is disposed in a region surrounded by the data line 121, the gate line 122, the anode power line 123, and the cathode power line 124. The pixel circuit 120 of this embodiment mode includes a selection transistor 126, a drive transistor 127, a holding capacitor 128, and an LED 129. The LED129 corresponds to the LED chip 202 shown in fig. 13. Circuit elements other than the LED129 in the pixel circuit 120 correspond to the driver circuit 102 provided on the circuit substrate 100. That is, in a state where the LED chip 202 is mounted to the circuit substrate 100, the pixel circuit 120 is completed.

As shown in fig. 15, the source electrode, the gate electrode, and the drain electrode of the selection transistor 126 are connected to the data line 121, the gate line 122, and the gate electrode of the driving transistor 127, respectively. The source electrode, the gate electrode, and the drain electrode of the driving transistor 127 are connected to the anode power supply line 123, the drain electrode of the selection transistor 126, and the LED129, respectively. A storage capacitor 128 is connected between the gate electrode and the drain electrode of the driving transistor 127. That is, the holding capacitor 128 is connected to the drain electrode of the selection transistor 126. The anode and cathode of the LED129 are connected to the drain electrode of the driving transistor 127 and the cathode power supply line 124, respectively.

A gray scale signal that determines the emission intensity of the LED129 is supplied to the data line 121. A gate signal of a selection transistor 126 for selecting writing of a gray-scale signal is supplied to the gate line 122. When the selection transistor 126 is turned on, a gray-scale signal is accumulated in the storage capacitor 128. Then, if the driving transistor 127 is turned on, a driving current corresponding to a gray-scale signal flows into the driving transistor 127. If the driving current output from the driving transistor 127 is input to the LED129, the LED129 emits light with a light emission intensity corresponding to the gray-scale signal.

Referring again to fig. 14, the data driving circuit 130 is disposed at a position adjacent to the display area 112 in the column direction (D2 direction). Further, the gate driver circuit 140 is disposed at a position adjacent to the display region 112 in the row direction (D1 direction). In this embodiment, the gate driver circuits 140 are provided on both sides of the display region 112, but only one of them may be used.

The data driving circuit 130 and the gate driving circuit 140 are disposed in the peripheral region 114. However, the area where the data driving circuit 130 is disposed is not limited to the peripheral area 114. For example, the data driving circuit 130 may be disposed on the flexible printed circuit board 160.

The data line 121 shown in fig. 15 extends from the data driving circuit 130 in the direction D2, and is connected to the source electrode of the selection transistor 126 in each pixel circuit 120. The gate line 122 extends from the gate driver circuit 140 in the direction D1, and is connected to the gate electrode of the selection transistor 126 in each pixel circuit 120.

Terminal portion 150 is disposed in terminal region 116. The terminal portion 150 is connected to the data driving circuit 130 via a connection wiring 151. Similarly, the terminal portion 150 is connected to the gate driver circuit 140 via a connection wiring 152. Further, the terminal portion 150 is connected to the flexible printed circuit board 160.

[ Cross-sectional Structure of display device 10 ]

Fig. 16 is a cross-sectional view showing the structure of a pixel 110 of a display device 10 according to an embodiment of the present invention. The pixel 110 has a driving transistor 127 disposed over an insulating substrate 11. As the insulating substrate 11, a substrate in which an insulating layer is provided over a glass substrate or a resin substrate can be used.

The driving transistor 127 includes a semiconductor layer 12, a gate insulating layer 13, and a gate electrode 14. The source electrode 16 and the drain electrode 17 are connected to the semiconductor layer 12 through an insulating layer 15. Although not shown, the gate electrode 14 is connected to the drain electrode of the selection transistor 126 shown in fig. 15.

The wiring 18 is provided on the same layer as the source electrode 16 and the drain electrode 17. The wiring 18 functions as an anode power supply line 123 shown in fig. 15. Therefore, the source electrode 16 and the wiring 18 are electrically connected by the connection wiring 20 provided over the planarization layer 19. The planarizing layer 19 is a transparent resin layer using a resin material such as polyimide or acrylic. The connection wiring 20 is a transparent conductive layer using a metal oxide material such as ITO. However, the present invention is not limited to this example, and other metal materials may be used as the connection wiring 20.

An insulating layer 21 made of silicon nitride or the like is provided on the connection wiring 20. On the insulating layer 21, an anode electrode 22 and a cathode electrode 23 are provided. In the present embodiment, the anode electrode 22 and the cathode electrode 23 are transparent conductive layers using a metal oxide material such as ITO. The anode electrode 22 is connected to the drain electrode 17 through an opening provided in the planarization layer 19 and the insulating layer 21.

The anode electrode 22 and the cathode electrode 23 are connected to the mounting

pads

25a and 25b, respectively, via the planarization layer 24. The mounting

pads

25a and 25b are made of a metal material such as tantalum or tungsten.

Connection electrodes

103a and 103b are provided on the mounting

pads

25a and 25b, respectively. The

connection electrodes

103a and 103b correspond to the connection electrodes 103 shown in fig. 12, respectively. That is, in the present embodiment, electrodes made of tin (Sn) are disposed as the

connection electrodes

103a and 103 b.

Terminal electrodes

203a and 203b of LED chip 202 are bonded to

connection electrodes

103a and 103b, respectively. As described above, in the present embodiment, the

terminal electrodes

203a and 203b are electrodes made of gold (Au). As described with reference to fig. 4, an unillustrated alloy layer (alloy layer 105 shown in fig. 12) is present between the connection electrode 103a and the terminal electrode 203 a. Here, the description has been given with the connection electrode 103a and the terminal electrode 203a being focused on, but the same applies to the connection electrode 103b and the terminal electrode 203 b.

The LED chip 202 corresponds to the LED129 in the circuit diagram shown in fig. 15. That is, the terminal electrode 203a of the LED chip 202 is connected to the anode electrode 22 connected to the drain electrode 17 of the driving transistor 127. The terminal electrode 203b of the LED chip 202 is connected to the cathode electrode 23. The cathode electrode 23 is electrically connected to a cathode power supply line 124 shown in fig. 15.

In the display device 10 of the present embodiment having the above-described configuration, the LED chip 202 is firmly mounted by fusion bonding by laser irradiation, and therefore has an advantage of high resistance to impact or the like.

< embodiment 2 >

In this embodiment, a method for manufacturing the display device 10 by a method different from that of embodiment 1 will be described. Specifically, in the method of manufacturing the display device 10 according to the present embodiment, all of the LED chips 202R, 202G, and 202B corresponding to the respective RGB colors are transferred to the same carrier substrate and then collectively transferred to the circuit substrate.

Fig. 17 to 24 are cross-sectional views showing a method of manufacturing the display device 10 according to embodiment 2 of the present invention. Hereinafter, a method for manufacturing the display device 10 will be described with reference to fig. 17 to 24.

First, as shown in fig. 17, an element substrate 200 having a plurality of LED chips 202R emitting light in red is disposed on a 1 st carrier substrate 300. The 1 st carrier substrate 300 includes a support substrate 301 and a separation layer 311. As the support substrate 301, a glass substrate or a resin substrate can be used. In this embodiment, a glass substrate is used as the support substrate 301. As the separation layer 311, a layer made of a resin material can be used. In this embodiment, a resin layer made of polyimide is used as the separation layer 311. However, the present invention is not limited to this example, and other resin materials may be used.

The element substrate 200 includes a semiconductor substrate 201 and a plurality of LED chips 202R. The detailed structure of the element substrate 200 has already been described in embodiment 1, and therefore the description thereof is omitted here. The element substrate 200 is arranged such that the terminal electrode 203R of each LED chip 202R faces the 1 st carrier substrate 300. Then, the element substrate 200 is bonded to the 1 st carrier substrate 300.

When the element substrate 200 is bonded to the 1 st carrier substrate 300, the 2 nd laser beam 45 is irradiated to the entire semiconductor substrate 201. As described in embodiment 1, ultraviolet light can be used as the 2 nd laser beam 45. That is, the semiconductor substrate 201 and each LED chip 202R are separated by performing the laser lift-off process by irradiating the 2 nd laser beam 45.

Next, as shown in fig. 18, the 1 st carrier substrate 300 having the LED chips 202R is disposed on the 2 nd carrier substrate 310. The 2 nd carrier substrate 310 includes a support substrate 302 and a separation layer 312. As the support substrate 302, a glass substrate or a resin substrate can be used. As the separation layer 312, a layer made of a resin material can be used. In this embodiment, a resin layer made of polyimide is used as the separation layer 312. However, the present invention is not limited to this example, and other resin materials may be used.

The 1 st carrier substrate 300 is disposed such that the terminal electrode 203R of each LED chip 202R faces the 2 nd carrier substrate 310. Then, the 1 st carrier substrate 300 and the 2 nd carrier substrate 310 are bonded.

When the 1 st carrier substrate 300 and the 2 nd carrier substrate 310 are bonded, the 1 st carrier substrate 300 is selectively irradiated with the 3 rd laser beam 50 through the light-shielding mask 30. As described in embodiment 1, the light-shielding mask 30 has a plurality of openings 30a arranged in accordance with the pitch of each of the pixels corresponding to red, green, or blue.

The 3 rd laser light 50 is not absorbed in the support substrate 301 but absorbed in the separation layer 311. In the present embodiment, ultraviolet light is used as the 3 rd laser light 50. In the step shown in fig. 18, the separation layer 311 is denatured by irradiating the 3 rd laser beam 50 and absorbing the separation layer 311. That is, the support substrate 301 and the LED chips 202R (strictly, the terminal electrodes 203R) are separated from each other by a so-called laser lift-off process.

In the step shown in fig. 18, a rectangular laser beam having an irradiation area having a size including the plurality of openings 30a is used as the 3 rd laser beam 50. That is, in the present embodiment, as in embodiment 1, by using the light-shielding mask 30, selective laser irradiation can be performed while using a laser beam having a wide irradiation area. In the present embodiment, the 3 rd laser light 50 is selectively irradiated to some of the LED chips 202 among the plurality of LED chips 202R.

Through the laser lift-off process described above, as shown in fig. 19, the plurality of LED chips 202R can be collectively transferred to the 2 nd carrier substrate 310 in accordance with the pitch of the pixels corresponding to red.

In this embodiment, an example is shown in which ultraviolet light is used as the 3 rd laser light 50, and the 3 rd laser light 50 is absorbed by the separation layer 311 to denature the separation layer 311, but the present invention is not limited to this example. For example, infrared light may be used as the 3 rd laser beam 50, and the separation layer 311 may be heated by irradiation with the 3 rd laser beam 50 to denature the separation layer 311. The 3 rd laser beam 50 is not limited to infrared light and ultraviolet light, and light having another wavelength (for example, blue light or green light) may be used as long as the separation layer 311 can be modified.

Each step described with reference to fig. 17 to 19 is performed for each of the LED chip 202R that emits light in red, the LED chip 202G that emits light in green, and the LED chip 202B that emits light in blue. Finally, each

LED chip

202R, 202G, and 202B is transferred to the same 2 nd carrier substrate 310. Thus, as shown in fig. 20, the LED chips 202R, 202G, and 202R are arranged on the 2 nd carrier substrate 310 in accordance with the pitches of the pixels of red, green, and blue.

Next, as shown in fig. 21, a 2 nd carrier substrate 310 having LED

chips

202R, 202G, and 202B is disposed on the circuit substrate 100. The configuration of the circuit board 100 has already been described in embodiment 1, and therefore the description thereof is omitted here. When the 2 nd carrier substrate 310 is disposed on the circuit substrate 100, the 2 nd carrier substrate 310 is disposed so that the connection electrodes 103 face the LED chips 202R, 202G, and 202B.

Next, as shown in fig. 22, the connection electrodes 103 are bonded to the LED chips 202R, 202G, and 202B by irradiation of the 1 st laser beam 40 through the light-shielding mask 31. This step is a step of fusion-bonding the connection electrodes 103 and the

terminal electrodes

203R, 203G, and 203B by irradiation of the 1 st laser beam 40, as in the step described in embodiment 1 with reference to fig. 4. The point different from embodiment 1 is that a light-shielding mask 31 is used instead of the light-shielding mask 30.

The light-shielding mask 31 has a plurality of openings 31a arranged in accordance with the positions of the pixels corresponding to red, green, or blue. That is, the light-shielding mask 31 functions as a mask for preventing the 1 st laser beam 40 from reaching the portion other than the pixels of the circuit board 100. Therefore, in the present embodiment, by using the light-shielding mask 31, the circuit elements (for example, thin film transistors, wirings, and the like) disposed in the portion other than the pixels of the circuit substrate 100 are not damaged by the irradiation of the laser light.

In the present embodiment, as in embodiment 1, a rectangular laser beam having an irradiation region with a size including the plurality of openings 31a is used as the 1 st laser beam 40. That is, in the present embodiment, as in embodiment 1, by using the light-shielding mask 31, selective laser irradiation can be performed while using a laser beam having a wide irradiation area. Through the process shown in fig. 22, the connection electrodes 103 can be bonded to the LED chips 202R, 202G, and 202B together while preventing damage to portions of the circuit board 100 other than the pixels.

Next, as shown in fig. 23, the 2 nd carrier substrate 310 is selectively irradiated with the 3 rd laser beam 50 through the light-shielding mask 31. In the step shown in fig. 23, a rectangular laser beam having an irradiation area having a size including the plurality of openings 31a is used as the 3 rd laser beam 50. That is, by using the light-shielding mask 31, laser light having a wide irradiation area is used, and selective laser light irradiation is performed. In the present embodiment, the 3 rd laser light 50 is selectively irradiated to the LED chips 202R, 202G, and 202B.

In the step shown in fig. 23, the 3 rd laser beam 50 is irradiated to denature the separation layer 312. That is, the support substrate 302 is separated from the LED chips 202R, 202G, and 202B (strictly, the

terminal electrodes

203R, 203G, and 203B) by a so-called laser lift-off process. By this laser lift-off process, as shown in fig. 24, the LED chips 202R, LED, 202G, and 202B can be collectively transferred to the circuit board 100 in accordance with the pixels corresponding to red, green, and blue.

In the present embodiment, an example in which the light-shielding mask 31 is used in the step shown in fig. 23 is shown, but the present invention is not limited to this example. For example, in the step shown in fig. 23, the 3 rd laser beam 50 may be irradiated to the entire 2 nd carrier substrate 310 without using the light-shielding mask 31.

As described above, in the present embodiment, the desired LED chip can be collectively irradiated with the laser light by using the light-shielding mask and the laser light having a relatively wide irradiation area. Therefore, according to the present embodiment, the flux when the plurality of LED chips are mounted on the circuit board by laser irradiation can be increased.

Further, according to the present embodiment, since the LED chips corresponding to the respective RGB colors are integrated on the same carrier substrate and then collectively transferred to the circuit board, the flux when mounting the plurality of LED chips on the circuit board can be increased. Further, when the LED chip is mounted on the circuit board, the light-shielding mask is used so that the laser light is not irradiated to a portion other than the pixel (that is, a portion not to be irradiated with the laser light), whereby a highly reliable display device can be manufactured.

As embodiments of the present invention, the above-described embodiments can be combined and implemented as appropriate as long as they are not contradictory to each other. In the present invention, the configuration in which a person skilled in the art appropriately adds, deletes, or changes the design of a component or adds, omits, or changes the conditions of a process is included in the scope of the present invention as long as the person is in the scope of the present invention.

It is to be understood that the present invention is not limited to the above-described embodiments, and various modifications, alterations, modifications, and equivalents may be made without departing from the spirit and scope of the invention.

[ description of reference ]

10 … … display device, 11 … … insulating substrate, 12 … … semiconductor layer, 13 … … gate insulating layer, 14 … … gate electrode, 15 … … insulating layer, 16 … … source electrode, 17 … … drain electrode, 18 … … wiring, 19 … … planarization layer, 20 … … connection wiring, 21 … … insulating layer, 22 … … anode electrode, 23 … … cathode electrode, 24 … … planarization layer, 25a, 25B … … mounting pad, 30, 31 … … light shielding mask, 30a, 31a … … opening, 40 … … th 1 st laser, 45 … … nd 2 nd laser, 50 … … rd 3 rd laser, 100 … … circuit substrate, 101 … … supporting substrate, 102 … … driving circuit, 103 … … connection electrode, 103a, 103B … … connection electrode, 105 … … alloy layer, 110R, 110G, 110B … … pixel, 112 … … display area, 114 … … peripheral area, 116 … … terminal area, 120. 120R, 120G, 120B … … pixel circuits, 121 … … data lines, 122 … … gate lines, 123 … … anode power lines, 124 … … cathode power lines, 126 … … selection transistors, 127 … … driving transistors, 128 … … holding capacitances, 130 … … data driving circuits, 140 … … gate driving circuits, 150 … … terminal portions, 151, 152 … … connection wirings, 160 … … flexible printed circuit substrates, 170 … … IC chips, 200 … … element substrates, 201 … … semiconductor substrates, 202R, 202G, 202B … … LED chips, 203a, 203B, 203R, 203G, 203B … … terminal electrodes, 300 … … 1 st carrier substrate, 301 … … support substrate, 302 … … support substrate, 310 … … 2 nd carrier substrate, 311, 312 separation layers 312 … ….

Claims

1. A method of manufacturing a display device, comprising:

preparing a 1 st substrate, the 1 st substrate having, for each pixel, a drive circuit for driving an LED chip and a connection electrode connected to the drive circuit;

disposing a 2 nd substrate having a plurality of LED chips on the 1 st substrate such that each connection electrode faces each LED chip;

the 1 st laser beam is irradiated through a light-shielding mask having a plurality of openings, whereby the connection electrodes and the LED chips are collectively bonded.

2. The method of manufacturing a display device according to claim 1,

the process of collectively bonding the connection electrodes and the LED chips includes:

an alloy layer containing constituent materials of the connection electrode and the terminal electrode of the LED chip is formed between the connection electrode and the terminal electrode.

3. The method of manufacturing a display device according to claim 1 or 2,

the irradiation with the 1 st laser beam includes: the light-shielding mask is scanned with a linear 1 st laser beam.

4. The method of manufacturing a display device according to claim 1 or 2,

the 1 st laser beam is infrared light or near-infrared light.

5. The method of manufacturing a display device according to claim 1 or 2,

further comprising: after the irradiation of the 1 st laser beam, a 2 nd laser beam having a wavelength different from that of the 1 st laser beam is irradiated.

6. The method of manufacturing a display device according to claim 5,

the 2 nd substrate is composed of a support substrate and the plurality of LED chips provided on the support substrate,

the manufacturing method further includes: after the 2 nd laser beam is irradiated, the plurality of LED chips and the support substrate are separated from each other.

7. The method of manufacturing a display device according to claim 5,

the irradiation with the 2 nd laser beam includes: the linear 2 nd laser beam is scanned over the light-shielding mask.

8. The method of manufacturing a display device according to claim 5,

the 2 nd laser is ultraviolet light.

9. The method of manufacturing a display device according to claim 1 or 2,

the pixels include pixels corresponding to respective colors of RGB,

the pitch of the openings is equal to the pitch of pixels corresponding to the same color.