JP2022007774A - Method for manufacturing display device - Google Patents

Abstract

To provide a through-put when an LED chip is equipped on a circuit board by using a laser irradiation technique.SOLUTION: The method for manufacturing a display device includes the steps of: preparing a first substrate for each pixel, the first substrate having a driving circuit for driving an LED chip and a connection electrode connected to the driving circuit; arranging a second substrate with a plurality of LED chips on the first substrate so that each connection electrode faces each LED chip; and integrally connecting the connection electrodes and the LED chips by applying a first laser light through a light shielding mask with a plurality of openings.SELECTED DRAWING: Figure 1

Description

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 on which an LED (Light Emitting Diode) chip is mounted.

In recent years, as a next-generation display device, the development of an LED display in which a minute LED chip is mounted on each pixel has been promoted. The LED display has a structure in which a plurality of LED chips are mounted on a circuit board 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. Each of these drive circuits is electrically connected to each LED chip.

There are various methods for mounting a plurality of LED chips on a circuit board. For example, a method is known in which an LED chip provided on a support substrate is bonded to a circuit board and then only the support substrate is removed. Patent Document 1 describes a technique of adhering an LED chip to an electrode on a circuit board and then removing only the support substrate by using a method called laser lift-off.

U.S. Pat. No. 10096740

Patent Document 1 describes a technique of performing selective laser irradiation by combining a laser beam having a large irradiation area and a light-shielding mask in order to improve the throughput of laser irradiation at the time of laser lift-off. However, in the technique described in Patent Document 1, only improving the throughput of the laser lift-off process is considered. Therefore, there is room for further improvement in processes other than the process of removing the support substrate.

One of the problems of the present invention is to improve the throughput when mounting the LED chip on the circuit board by using laser irradiation.

In the method of manufacturing a display device according to an embodiment of the present invention, a first substrate having a drive circuit for driving an LED chip and a connection electrode connected to the drive circuit is prepared for each pixel, and the first substrate is placed on the first substrate. A second substrate having a plurality of LED chips is arranged so that each connection electrode and each LED chip face each other, and the first laser beam is irradiated through a light-shielding mask having a plurality of openings. It includes joining each connection electrode and each LED chip together.

It is a flowchart which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is a top view which shows the schematic structure of the display device in 1st Embodiment of this invention. It is a block diagram which shows the circuit structure of the display device which concerns on 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the pixel circuit of the display device which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the structure of the pixel of the display device which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be carried out in various embodiments without departing from the gist thereof. The present invention is not construed as being limited to the description of the embodiments exemplified below. In order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment. However, the drawings are merely examples and do not limit the interpretation of the present invention.

In the description of the embodiment 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 "above" or "below" merely explain the upper limit of each element. For example, the expression that the LED chip is arranged on the circuit board includes the case where another member is interposed between the circuit board and the LED chip. Further, the expression "above" or "below" includes not only the case where the elements are superimposed in the plan view but also the case where the elements are not superimposed.

When the embodiment of the present invention is described, the same reference numerals or the same reference numerals with symbols such as alphabets may be added to the elements having the same functions as the elements already described, and the description thereof may be omitted. When it is necessary to explain a certain element separately for each color of RGB, a symbol of R, G or B is added after the symbol indicating the element to distinguish them. However, when it is not necessary to explain the element separately for each color of RGB, only the reference numeral indicating the element will be described.

<First Embodiment>
[Manufacturing method of display device]
FIG. 1 is a flowchart showing a manufacturing method of the display device 10 according to the embodiment of the present invention. 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 of manufacturing the display device 10 will be described with reference to FIG. At that time, the cross-sectional structure in each manufacturing process will be described with reference to FIGS. 2 to 12.

First, in step S11 of FIG. 1, a circuit board 100 having a drive circuit 102 for driving an LED chip and a connection electrode 103 connected to the drive circuit 102 is prepared for each pixel. The circuit board 100 has a region corresponding to a plurality of pixels. As shown in FIG. 2, the circuit board 100 has a drive circuit 102 that drives an LED chip corresponding to each pixel on a support board 101 having an insulating surface. As the support substrate 101, for example, a glass substrate, a resin substrate, a ceramics substrate, or a metal substrate can be used. Each drive circuit 102 is composed of a plurality of thin film transistors (TFTs). Each connection electrode 103 is arranged in each pixel and is connected to the drive circuit 102. The detailed structure of the circuit board 100 will be described later.

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

In the present embodiment, an example in which nine connection electrodes 103 are arranged on the support substrate 101 is shown, but in the present embodiment, since the flip-chip type LED chip 202 is mounted, at least each pixel is actually mounted. Two connection electrodes 103 are formed. The flip-chip type LED chip has a terminal electrode connected to an N-type semiconductor and a terminal electrode connected to a P-type semiconductor. Therefore, in the present embodiment, in order to arrange one LED chip for each pixel, at least two connection electrodes 103 are arranged for each pixel. However, when the above-mentioned face-up type LED chip is used as the LED chip 202, it is sufficient that one connection electrode 103 is formed for each pixel on the support substrate 101.

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

Next, in step S12 of FIG. 1, an element substrate 200 having a plurality of LED chips 202R is arranged on the circuit board 100 so that each connection electrode 103 and each LED chip 202R face each other. In the present embodiment, the element substrate 200 is a substrate in which a plurality of LED chips 202R that emit red light are provided on the semiconductor substrate 201. In this embodiment, a sapphire substrate is used as the semiconductor substrate 201. The LED chip 202R is made 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 appropriately determined according to 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 arranged on the connection electrode 103 arranged in the pixel corresponding to the red color among the plurality of connection electrodes 103. Each LED chip 202 includes a terminal electrode 203R. Therefore, in the state where the element substrate 200 is arranged on the circuit board 100, each connection electrode 103 and each terminal electrode 203R face each other. 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 connection electrode 103 and the LED chip 202R are collectively joined by irradiation of the first laser beam 40 via the light-shielding mask 30. This process is a process of melting and joining the connection electrode 103 and the terminal electrode 203R by irradiating the first laser beam 40.

As the first laser light 40, a laser light that is not absorbed by the semiconductor substrate 201 and the LED chip 202R but is 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 first laser light 40. As the light source of the first laser beam 40, a solid-state laser such as a YAG laser or a YVO ₄ laser may be used. However, as the first laser light 40, it is possible to select a laser light having an appropriate wavelength according to the materials constituting the semiconductor substrate 201 and the LED chip 202R. For example, when a semiconductor material that absorbs laser light having a shorter wavelength than infrared light is used, a green laser (green light) can also be used.

By irradiation with the first 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 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 eutectic alloys 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 on the connection electrode 103.

In the present embodiment, when irradiating the first laser beam 40, a light-shielding mask 30 having a plurality of openings 30a is used. The plurality of openings 30a are arranged, for example, according to the pitches (intervals between pixels) of the pixels corresponding to red, the pixels corresponding to green, or the pixels corresponding to blue. In the example shown in FIG. 4, each opening 30a is arranged according 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 arranged.

In the present embodiment, as the first laser beam 40, a rectangular laser beam having an irradiation region having a size including a plurality of openings 30a is used. When the irradiation area of the first laser light 40 is narrower than that of the light-shielding mask 30, the laser light can be irradiated to the entire light-shielding mask 30 by irradiating the light-shielding mask 30 multiple times while moving the irradiation area of the laser light. can.

The first laser beam 40 irradiated to the light-shielding mask 30 passes only the portion where the opening 30a is located. That is, by using the light-shielding mask 30, it is possible to perform selective laser irradiation while using laser light having a wide irradiation area. In the present embodiment, the first laser beam 40 is selectively irradiated to the position where the LED chip 202R is arranged. That is, according to the present embodiment, it is possible to collectively join the plurality of connection electrodes 103 and the plurality of LED chips 202R.

Further, in a plan view, the size (area) of the opening 30a may be such a size that the connection electrode 103 and the terminal electrode 203R can be reliably joined. 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. Further, 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 having a rectangular irradiation region is used as the first laser beam 40 is shown, but the present invention is not limited to this example, and a laser beam having a linear (elongated shape) irradiation region is used. May be good. In this case, by scanning the linear laser light against the light-shielding mask 30, it is possible to irradiate the entire light-shielding mask 30 with the laser light.

Next, in step S14 of FIG. 1, as shown in FIG. 5, the semiconductor substrate 201 and the LED chip 202R are collectively separated by irradiation with the second laser beam 45 via the light-shielding mask 30. This process is the so-called laser lift-off process. Specifically, it is a process of denaturing the boundary portion between the semiconductor substrate 201 and the plurality of LED chips 202R by irradiation with the second laser beam 45, and separating the plurality of LED chips 202R from the semiconductor substrate 201.

As the second laser light 45, a laser light that is not absorbed by the semiconductor substrate 201 and is absorbed by the LED chip 202R is selected. In this embodiment, ultraviolet light is used as the second laser light 45. As the light source of the second laser beam 45, a solid-state laser such as a YAG laser or a YVO ₄ laser, or an excimer laser may be used. However, as the second laser light 45, it is possible to select a laser light having an appropriate wavelength according to the materials constituting the semiconductor substrate 201 and the LED chip 202R. For example, when a semiconductor material that absorbs a laser beam having a wavelength longer than that of ultraviolet light is used, a blue laser (blue light) or a green laser (green light) can also be used.

In the process shown in FIG. 5, similarly to the irradiation of the first laser beam 40 shown in FIG. 4, the second laser beam 45 is a rectangular laser beam having an irradiation region having a size including a plurality of openings 30a. Use. Also in this case, when the irradiation area of the second laser light 45 is narrower than that of the light-shielding mask 30, the irradiation area may be moved a plurality of times while moving the irradiation area of the laser light. Further, not limited to this example, a laser beam having a linear (elongated shape) irradiation region may be used as the second laser beam 45 to scan on the light-shielding mask 30.

The second laser beam 45 irradiated to the light-shielding mask 30 passes only the portion where the opening 30a is located. That is, by using the light-shielding mask 30, it is possible to perform selective laser irradiation while using laser light having a wide irradiation area. In the present embodiment, the second 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 and each LED chip 202R can be separated.

Further, in a plan view, the size (area) of the opening 30a may be such that the LED chip 202R and the semiconductor substrate 201 can be separated reliably. For example, the size of the opening 30a in a plan view may be smaller than the size of the LED chip 202R. Further, 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 irradiating the second laser beam 45, the semiconductor substrate 201 and each LED chip 202R are separated. Through the above process, the LED chip 202R can be mounted on the circuit board 100 as shown in FIG.

After obtaining the state shown in FIG. 6, steps S13 and S14 shown in FIG. 1 are repeated to sequentially mount the LED chip 202G that emits green light and the LED chip 202B that emits light in blue on the circuit board 100.

Specifically, as shown in FIG. 7, the connection electrode 103 and the LED chip 202G are collectively joined by irradiation of the first laser beam 40 through the light-shielding mask 30. The details of the process shown in FIG. 7 are the same as those shown in FIG. After that, as shown in FIG. 8, the semiconductor substrate 201 and the LED chip 202G are collectively separated by irradiation with the second laser beam 45 via the light-shielding mask 30. The details of the process shown in FIG. 8 are the same as those shown in FIG. Through these processes, the state shown in FIG. 9 is obtained. In the state shown in FIG. 9, the LED chip 202R that emits red light and the LED chip 202G that emits green light are mounted on the circuit board 100.

Further, as shown in FIG. 10, the connection electrode 103 and the LED chip 202B are collectively joined by irradiation with the first laser beam 40 via the light-shielding mask 30. The details of the process shown in FIG. 10 are the same as those shown in FIG. After that, as shown in FIG. 11, the semiconductor substrate 201 and the LED chip 202B are collectively separated by irradiation with the second laser beam 45 via the light-shielding mask 30. The details of the process shown in FIG. 11 are the same as those shown in FIG. Through these processes, the state shown in FIG. 12 is obtained. In the state shown in FIG. 12, 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 are mounted on the circuit board 100.

As described above, in the present embodiment, by using the light-shielding mask 30 and the first laser beam 40 having a relatively wide irradiation area, each connection electrode 103 on the circuit board 100 and each LED chip 202R, 202G and 202B are used. And can be joined together. Further, in the present embodiment, the semiconductor substrate 201 and the multiple LED chips 202R, 202G and 202B can be collectively separated by using the light-shielding mask 30 and the second laser beam 45 having a relatively wide irradiation area. It is possible. Therefore, according to this embodiment, it is possible to improve the throughput when mounting a plurality of LED chips on a circuit board by using laser irradiation.

[Display device configuration]
The configuration of the display device 10 according to the embodiment of the present invention will be described with reference to FIGS. 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 area 112, a peripheral area 114, and a terminal area 116.

The display area 112 is an area in which a plurality of pixels 110 including the LED chip 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 area 114 is an area around the display area 112. The peripheral region 114 is provided with a driver circuit (data driver circuit 130 and gate driver circuit 140 shown in FIG. 14) for controlling the pixel circuit (pixel circuit 120 shown in FIG. 14) provided in each pixel 110. It is an area.

The terminal area 116 is an area in which a plurality of wirings connected to the above-mentioned driver circuit are integrated. The flexible printed circuit board 160 is electrically connected to a plurality of wirings in the terminal area 116. The video signal (data signal) or control signal output from the external device (not shown) is input to the IC chip 170 via the wiring (not shown) provided on the flexible printed circuit board 160. The IC chip 170 performs various signal processing on the video signal and 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, the display area 112 is provided with a pixel circuit 120 corresponding to each pixel 110. In the present embodiment, the pixel circuit 120R, the pixel circuit 120G, and the pixel circuit 120B are provided corresponding to the pixel 110R, the pixel 110G, and the pixel 110B, respectively. That is, in the display area 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 the configuration of the pixel circuit 120 of the display device 10 according to the embodiment of the present invention. The pixel circuit 120 is arranged in an area surrounded by a data line 121, a gate line 122, an anode power supply line 123, and a cathode power supply line 124. The pixel circuit 120 of this embodiment includes a selection transistor 126, a drive transistor 127, a holding capacity 128, and an LED 129. The LED 129 corresponds to the LED chip 202 shown in FIG. In the pixel circuit 120, the circuit elements other than the LED 129 correspond to the drive circuit 102 provided on the circuit board 100. That is, the pixel circuit 120 is completed with the LED chip 202 mounted on the circuit board 100.

As shown in FIG. 15, the source electrode, gate electrode, and drain electrode of the selection transistor 126 are connected to the data line 121, the gate wire 122, and the gate electrode of the drive transistor 127, respectively. The source electrode, gate electrode and drain electrode of the drive transistor 127 are connected to the anode power supply line 123, the drain electrode of the selection transistor 126 and the LED 129, respectively. A holding capacity 128 is connected between the gate electrode and the drain electrode of the drive transistor 127. That is, the holding capacity 128 is connected to the drain electrode of the selection transistor 126. The anode and cathode of the LED 129 are connected to the drain electrode and the cathode power line 124 of the drive transistor 127, respectively.

A gradation signal that determines the emission intensity of the LED 129 is supplied to the data line 121. A gate signal for selecting the selection transistor 126 for writing the gradation signal is supplied to the gate line 122. When the selection transistor 126 is turned on, the gradation signal is accumulated in the holding capacity 128. After that, when the drive transistor 127 is turned on, a drive current corresponding to the gradation signal flows through the drive transistor 127. When the drive current output from the drive transistor 127 is input to the LED 129, the LED 129 emits light with a light emission intensity corresponding to the gradation signal.

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

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

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

A terminal portion 150 is arranged in the terminal region 116. The terminal portion 150 is connected to the data driver circuit 130 via the connection wiring 151. Similarly, the terminal portion 150 is connected to the gate driver circuit 140 via the 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 configuration of the pixel 110 of the display device 10 according to the embodiment of the present invention. The pixel 110 has a drive transistor 127 provided on the insulating substrate 11. As the insulating substrate 11, a substrate having an insulating layer provided on a glass substrate or a resin substrate can be used.

The drive transistor 127 includes a semiconductor layer 12, a gate insulating layer 13, and a gate electrode 14. A source electrode 16 and a drain electrode 17 are connected to the semiconductor layer 12 via 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.

Wiring 18 is provided on the same layer as the source electrode 16 and the drain electrode 17. The wiring 18 functions as the anode power supply line 123 shown in FIG. Therefore, the source electrode 16 and the wiring 18 are electrically connected by the connection wiring 20 provided on the flattening layer 19. The flattening 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. An anode electrode 22 and a cathode electrode 23 are provided on the insulating layer 21. 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 via the openings provided in the flattening 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 via the flattening layer 24, respectively. 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 composed of tin (Sn) are arranged as the connection electrodes 103a and 103b.

The terminal electrodes 203a and 203b of the LED chip 202 are bonded to the 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 alloy layer (alloy layer 105 shown in FIG. 12) (not shown) exists between the connection electrode 103a and the terminal electrode 203a.

The LED chip 202 corresponds to the LED 129 in the circuit diagram shown in FIG. 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 drive 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 the cathode power line 124 shown in FIG.

The display device 10 of the present embodiment having the above structure has an advantage that it has high resistance to impact and the like because the LED chip 202 is firmly mounted by melt bonding by laser irradiation.

<Second Embodiment>
In this embodiment, a method of manufacturing the display device 10 by a method different from that of the first embodiment will be described. Specifically, in the manufacturing method of the display device 10 of the present embodiment, the LED chips 202R, 202G, and 202B corresponding to each RGB color are all transferred to the same carrier substrate and then collectively transferred to the circuit board. ..

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

First, as shown in FIG. 17, an element substrate 200 having a plurality of LED chips 202R that emits red light is arranged on the first carrier substrate 300. The first 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. Since the detailed configuration of the element substrate 200 has already been described in the first embodiment, the description thereof will be omitted here. The element substrate 200 is arranged so that the terminal electrode 203R of each LED chip 202R faces the first carrier substrate 300. After that, the element substrate 200 and the first carrier substrate 300 are bonded together.

After the element substrate 200 and the first carrier substrate 300 are bonded together, the second laser beam 45 is applied to the entire semiconductor substrate 201. As described in the first embodiment, ultraviolet light can be used as the second laser light 45. That is, the semiconductor substrate 201 and each LED chip 202R are separated by irradiating the second laser beam 45 to perform laser lift-off.

Next, as shown in FIG. 18, the first carrier substrate 300 having each LED chip 202R is arranged on the second carrier substrate 310. The second 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 first carrier substrate 300 is arranged so that the terminal electrodes 203R of each LED chip 202R face the second carrier substrate 310. After that, the first carrier substrate 300 and the second carrier substrate 310 are bonded together.

After the first carrier substrate 300 and the second carrier substrate 310 are bonded together, the first carrier substrate 300 is selectively irradiated with the third laser beam 50 via the light-shielding mask 30. As described in the first embodiment, the light-shielding mask 30 has a plurality of openings 30a arranged according to the pitches of the pixels corresponding to red, the pixels corresponding to green, or the pixels corresponding to blue.

The third laser beam 50 is a laser beam that is not absorbed by the support substrate 301 but is absorbed by the separation layer 311. In this embodiment, ultraviolet light is used as the third laser light 50. In the process shown in FIG. 18, the separation layer 311 is denatured by irradiating the separation layer 311 with the third laser beam 50 to absorb the light. That is, the support substrate 301 and each LED chip 202R (strictly speaking, each terminal electrode 203R) are separated by the so-called laser lift-off.

In the process shown in FIG. 18, as the third laser beam 50, a rectangular laser beam having an irradiation region having a size including a plurality of openings 30a is used. That is, as in the first embodiment, in the present embodiment, by using the light-shielding mask 30, it is possible to perform selective laser irradiation while using the laser light having a wide irradiation region. In the present embodiment, among the plurality of LED chips 202R, some of the LED chips 202 are selectively irradiated with the third laser beam 50.

By the above-mentioned laser lift-off process, as shown in FIG. 19, a plurality of LED chips 202R can be collectively transferred to the second carrier substrate 310 according to the pitch of the pixels corresponding to red.

In this embodiment, an example is shown in which ultraviolet light is used as the third laser light 50 and the third laser light 50 is absorbed by the separation layer 311 to denature the separation layer 311. However, this example is not limited to this example. do not have. For example, it is also possible to use infrared light as the third laser light 50 and heat the separation layer 311 by irradiation with the third laser light 50 to denature the separation layer 311. Further, the third laser light 50 is not limited to infrared light and ultraviolet light, and if it is possible to modify the separation layer 311, light of another wavelength (for example, blue light or green light) is used. May be good.

Each process described with reference to FIGS. 17 to 19 is performed on the LED chip 202R that emits red light, the LED chip 202G that emits green light, and the LED chip 202B that emits light in blue, respectively. Finally, the LED chips 202R, 202G and 202B are transferred to the same second carrier substrate 310. As a result, as shown in FIG. 20, the LED chips 202R, 202G, and 202R are arranged on the second carrier substrate 310 according to the pitch of the red, green, and blue pixels.

Next, as shown in FIG. 21, a second carrier board 310 having the LED chips 202R, 202G, and 202B is arranged on the circuit board 100. Since the configuration of the circuit board 100 has already been described in the first embodiment, the description thereof will be omitted here. When arranging the second carrier substrate 310 on the circuit board 100, the second carrier substrate 310 is arranged so that each connection electrode 103 and each LED chip 202R, 202G, and 202B face each other.

Next, as shown in FIG. 22, each connection electrode 103 and each LED chip 202R, 202G, and 202B are collectively joined by irradiation with the first laser beam 40 via the light-shielding mask 31. This process is a process of melt-bonding each connection electrode 103 and each terminal electrode 203R, 203G, and 203B by irradiation with the first laser beam 40, similar to the process described with reference to FIG. 4 in the first embodiment. be. The difference from the first embodiment is that the 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 according to the positions of the pixels corresponding to red, the pixels corresponding to green, or the pixels corresponding to blue. That is, the light-shielding mask 31 functions as a mask for preventing the first 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, wiring, etc.) arranged in the portion other than the pixels of the circuit board 100 are damaged due to the irradiation of the laser beam. Never give.

In the present embodiment, as in the first embodiment, as the first laser beam 40, a rectangular laser beam having an irradiation region having a size including a plurality of openings 31a is used. That is, as in the first embodiment, in the present embodiment, by using the light-shielding mask 31, it is possible to perform selective laser irradiation while using the laser light having a wide irradiation region. By the process shown in FIG. 22, each connection electrode 103 and each LED chip 202R, 202G, and 202B can be collectively joined while preventing damage to a portion other than the pixels of the circuit board 100.

Next, as shown in FIG. 23, the second carrier substrate 310 is selectively irradiated with the third laser beam 50 via the light-shielding mask 31. In the process shown in FIG. 23, as the third laser beam 50, a rectangular laser beam having an irradiation region having a size including a plurality of openings 31a is used. That is, by using the light-shielding mask 31, selective laser irradiation is performed while using laser light having a wide irradiation area. In the present embodiment, the third laser beam 50 is selectively irradiated to each of the LED chips 202R, 202G and 202B.

In the process shown in FIG. 23, the separation layer 312 is denatured by irradiating the third laser beam 50. That is, the support substrate 302 and the LED chips 202R, 202G and 202B (strictly speaking, the terminal electrodes 203R, 203G and 203B) are separated from each other by the so-called laser lift-off process. By this laser lift-off process, as shown in FIG. 24, the LED chip 202R, the LED chip 202G, and the LED are used for the circuit board 100 according to the pixels corresponding to red, the pixels corresponding to green, and the pixels corresponding to blue, respectively. Chip 202B can be transferred all at once.

In this embodiment, an example in which the light-shielding mask 31 is used in the process shown in FIG. 23 is shown, but the present invention is not limited to this example. For example, in the process shown in FIG. 23, the third laser beam 50 may be applied to the entire second carrier substrate 310 without using the light shielding mask 31.

As described above, in the present embodiment, by using a light-shielding mask and a laser beam having a relatively wide irradiation area, it is possible to collectively irradiate a desired LED chip with the laser beam. Therefore, according to this embodiment, it is possible to improve the throughput when mounting a plurality of LED chips on a circuit board by using laser irradiation.

Further, according to the present embodiment, since each LED chip corresponding to each color of RGB is integrated on the same carrier board and then collectively transferred to the circuit board, when a plurality of LED chips are mounted on the circuit board. Throughput can be improved. Furthermore, by actually hitting the LED chip on the circuit board and using a light-shielding mask to prevent the laser light from being irradiated to the parts other than the pixels (that is, the parts that do not want to be irradiated with the laser light), the reliability is improved. High display devices can be manufactured.

Each of the above-described embodiments of the present invention can be appropriately combined and implemented as long as they do not contradict each other. Based on each embodiment, those skilled in the art who have added, deleted, or changed the design of components as appropriate, or those who have added, omitted, or changed the conditions of processes also have the gist of the present invention. To the extent, it is included in the scope of the present invention.

Further, even if the action / effect is different from the action / effect brought about by the embodiment of each of the above-mentioned embodiments, those which are clear from the description of the present specification or which can be easily predicted by those skilled in the art are referred to. Naturally, it is understood that it is brought about by the present invention.

10 ... Display device, 11 ... Insulated substrate, 12 ... Semiconductor layer, 13 ... Gate insulating layer, 14 ... Gate electrode, 15 ... Insulated layer, 16 ... Source electrode, 17 ... Drain electrode, 18 ... Wiring, 19 ... Flattening layer , 20 ... connection wiring, 21 ... insulating layer, 22 ... anode electrode, 23 ... cathode electrode, 24 ... flattening layer, 25a, 25b ... mounting pad, 30, 31 ... shading mask, 30a, 31a ... opening, 40 ... 1st laser beam, 45 ... 2nd laser beam, 50 ... 3rd laser beam, 100 ... circuit board, 101 ... support board, 102 ... drive circuit, 103 ... connection electrode, 103a, 103b ... connection electrode, 105 ... alloy layer , 110, 110R, 110G, 110B ... pixel, 112 ... display area, 114 ... peripheral area, 116 ... terminal area, 120, 120R, 120G, 120B ... pixel circuit, 121 ... data line, 122 ... gate line, 123 ... anode Power supply line, 124 ... cathode power supply line, 126 ... selection transistor, 127 ... drive transistor, 128 ... holding capacity, 130 ... data driver circuit, 140 ... gate driver circuit, 150 ... terminal part, 151, 152 ... connection wiring, 160 ... Flexible printed circuit board, 170 ... IC chip, 200 ... element board, 201 ... semiconductor board, 202, 202R, 202G, 202B ... LED chip, 203, 203a, 203b, 203R, 203G, 203B ... terminal electrode, 300 ... first Carrier substrate, 301 ... Support substrate, 302 ... Support substrate, 310 ... Second carrier substrate, 311 and 312 ... Separation layer

Claims (9)

A first substrate having a drive circuit for driving the LED chip and a connection electrode connected to the drive circuit is prepared for each pixel.
A second substrate having a plurality of LED chips is arranged on the first substrate so that each connection electrode and each LED chip face each other.
The present invention comprises joining the connection electrodes and the LED chips together by irradiating the first laser beam through a light-shielding mask having a plurality of openings.
How to manufacture a display device. The collective joining of each of the connection electrodes and the LED chips includes forming an alloy layer containing the constituent materials of both between the connection electrodes and the terminal electrodes of the LED chips. Item 1. The method for manufacturing a display device according to Item 1. The method for manufacturing a display device according to claim 1 or 2, wherein the irradiation of the first laser beam comprises scanning a linear first laser beam against the light-shielding mask. The method for manufacturing a display device according to any one of claims 1 to 3, wherein the first laser light is infrared light or near infrared light. The method for manufacturing a display device according to any one of claims 1 to 4, further comprising irradiating the first laser beam with a second laser beam having a wavelength different from that of the first laser beam. .. The second substrate is composed of a support substrate and the plurality of LED chips provided on the support substrate.
The method for manufacturing a display device according to claim 5, further comprising separating the plurality of LED chips and the support substrate after irradiating the second laser beam. The method for manufacturing a display device according to claim 5, wherein the irradiation of the second laser beam comprises scanning a linear second laser beam against the light-shielding mask. The method for manufacturing a display device according to any one of claims 5 to 7, wherein the second laser beam is ultraviolet light. Each of the pixels includes pixels corresponding to each color of RGB.
The method for manufacturing a display device according to any one of claims 1 to 8, wherein the pitch of the openings is equal to the pitch of pixels corresponding to the same color.

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