JP7681437B2 - Display device manufacturing method - Google Patents

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 that is equipped with an LED (Light Emitting Diode) chip.

In recent years, LED displays, in which tiny LED chips are mounted in each pixel, have been developed as the next generation of display devices. LED displays have a structure in which multiple LED chips are mounted on a circuit board that forms a pixel array. The circuit board has drive circuits for emitting light from the LEDs at positions corresponding to each pixel. These drive circuits are electrically connected to each LED chip.

There are various methods for mounting multiple LED chips on a circuit board. For example, a method is known in which LED chips mounted on a support substrate are attached to the circuit board, and then only the support substrate is removed. For example, Patent Document 1 describes a technology in which LED chips are selectively irradiated with laser light at high throughput by using a light-shielding mask.

U.S. Pat. No. 1,009,6740

As in the above-mentioned conventional technology, if there is a gap between the light-shielding mask and the object to be irradiated with the laser light, the laser light will be diffracted at the openings in the light-shielding mask, and there is a risk that the laser light will be irradiated onto the back side of the light-shielding mask. Diffraction of laser light becomes more pronounced as the wavelength of the laser light becomes longer.

One of the objectives of the present invention is to prevent diffraction of laser light in a manufacturing method for a display device that includes a laser light irradiation process using a light-shielding mask.

A manufacturing method for a display device in one embodiment of the present invention includes preparing a first substrate on which a plurality of LED chips are provided, arranging the plurality of LED chips on the second substrate such that the plurality of LED chips are positioned between the first substrate and the second substrate, and irradiating some of the plurality of LED chips with laser light through a light-shielding mask fixed to a holding member that holds the first substrate.

FIG. 4 is a flowchart showing a manufacturing method of the display device according to the first embodiment. 5A to 5C are cross-sectional views illustrating a manufacturing method of the display device in the first embodiment. 5A to 5C are cross-sectional views illustrating a manufacturing method of the display device in the first embodiment. 5A to 5C are cross-sectional views illustrating a manufacturing method of the display device in the first embodiment. 5A to 5C are cross-sectional views illustrating a manufacturing method of the display device in the first embodiment. 5A to 5C are cross-sectional views illustrating a manufacturing method of the display device in the first embodiment. 5A to 5C are cross-sectional views illustrating a manufacturing method of the display device in the first embodiment. 1 is a diagram showing a configuration of a laser processing device used in a manufacturing method of a display device according to a first embodiment; FIG. 1 is a diagram showing a state in which a laser light irradiation process is performed using a laser processing device. 4 is a diagram showing a configuration of a second work unit in a laser processing apparatus used in the manufacturing method of the display device of the first embodiment. FIG. 1 is a plan view showing a schematic configuration of a display device according to a first embodiment. 1 is a block diagram showing a circuit configuration of a display device according to a first embodiment. 1 is a circuit diagram showing a configuration of a pixel circuit of a display device according to a first embodiment. 1 is a cross-sectional view showing a configuration of a pixel of a display device according to a first embodiment. 13 is a diagram showing a configuration of a second work unit in a laser processing apparatus used in a manufacturing method of a display device according to a second embodiment. FIG.

The following describes an embodiment of the present invention with reference to the drawings. However, the present invention can be implemented in various forms without departing from the spirit of the invention. The present invention should not be interpreted as being limited to the description of the embodiments exemplified below. In order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual form. However, the drawings are merely examples and do not limit the interpretation of the present invention.

When describing the embodiments of the present invention, the direction from the substrate toward the LED chip is referred to as "upper", and the opposite direction is referred to as "lower". However, the expressions "upper" and "lower" merely describe the upper-level relationship of each element. For example, the expression that the LED chip is disposed on the substrate includes cases where other members are interposed between the substrate and the LED chip. Furthermore, the expressions "upper" and "lower" include not only cases where the elements overlap in a plan view, but also cases where they do not overlap.

When describing embodiments of the present invention, elements having similar functions to elements already described may be given the same reference numerals or the same reference numerals plus a symbol such as an alphabet, and the description may be omitted. Furthermore, when it is necessary to describe an element by distinguishing between the RGB colors, the reference numeral for that element is followed by the symbol R, G, or B to distinguish between them. However, when it is not necessary to describe an element by distinguishing between the RGB colors, the reference numeral for that element is used to describe it.

First Embodiment
[Display Device Manufacturing Method]
Fig. 1 is a flow chart showing a method for manufacturing the display device 10 in the first embodiment. Specifically, Fig. 1 shows a process for transferring a plurality of LED chips 202 formed on an element substrate 200 to a circuit substrate 100. Figs. 2 to 5 are cross-sectional views showing the method for manufacturing the display device 10 in the first embodiment. Here, the process up to transferring the LED chips 202 of each color of RGB to the circuit substrate 100 will be described with reference to Fig. 1. In this regard, specific examples of each process will be described with reference to Figs. 2 to 5.

First, in step S11 of FIG. 1, an element substrate 200 having a plurality of LED chips 202R is prepared (see FIG. 2). The plurality of LED chips 202R are LED chips that emit red light. The LED chips 202R can be formed by growing a semiconductor layer on a semiconductor substrate 201. For example, a sapphire substrate can be used as the semiconductor substrate 201. For example, gallium nitride (GaN) can be grown as the semiconductor layer. However, this is not limited to this example, and the LED chips 202R may be formed using a semiconductor layer (for example, an InGaAlP layer) grown on another semiconductor substrate such as a gallium arsenide (GaAs) substrate. In this case, the other semiconductor substrate on which the LED chips 202R are formed may be bonded to the semiconductor substrate 201.

Next, in step S12 of FIG. 1, multiple LED chips 202R are placed on the circuit board 100 so that the multiple LED chips 202R are located between the element board 200 and the circuit board 100 (see FIG. 3). Specifically, the element board 200 is placed on the circuit board 100 so that the connection electrodes 103 face each LED chip 202R. At this time, the circuit board 100 and the element board 200 are aligned so that the terminal electrodes 203R of each LED chip 202R contact the connection electrodes 103. An adhesive substance may be provided between the terminal electrodes 203R and the connection electrodes 103.

The circuit board 100 has areas corresponding to a number of pixels. As shown in FIG. 3, the circuit board 100 has a driving circuit 102 for driving an LED chip corresponding to each pixel on a substrate 101 having an insulating surface. The substrate 101 may be, for example, a glass substrate, a resin substrate, a ceramic substrate, or a metal substrate. Each driving circuit 102 is composed of a number of thin film transistors (TFTs). The circuit board 100 is also called an array substrate or a TFT substrate. Each connection electrode 103 is disposed at each pixel and is connected to the driving circuit 102. The detailed structure of the circuit board 100 will be described later.

In this embodiment, an example is shown in which each driving circuit 102 and each connection electrode 103 are formed on the substrate 101 using thin film formation technology, but the present invention is not limited to this example. For example, a substrate (a so-called active matrix substrate) on which the driving circuit 102 is formed on the substrate 101 may be obtained as a ready-made product from a third party. In this case, the connection electrode 103 may be formed on the obtained substrate.

In addition, in this embodiment, a flip-chip type LED chip is described as an example of the LED chip 202R, but this is not limited to this example. For example, the LED chip 202R may have an anode electrode (or a cathode electrode) on the side closer to the circuit board 100 and a cathode electrode (or anode electrode) on the side farther from the circuit board 100. In other words, the LED chip 202R may be a face-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 case, it is sufficient that one connection electrode 103 is provided for each pixel.

The connection electrode 103 is made of, for example, a metal material having electrical conductivity. In this embodiment, tin (Sn) is used as the metal material. However, this is not the only example, and other metal materials that can form 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 to 5 μm (preferably 1 μm to 3 μm).

Next, in step S13 of FIG. 1, laser light 50 is irradiated onto some of the LED chips 202R through a light-shielding mask 40 fixed to a holding member 30 that holds the element substrate 200 (see FIG. 4). As shown in FIG. 4, in this embodiment, the connection electrode 103 and some of the LED chips 202R are bonded together by irradiating the laser light 50 through the light-shielding mask 40. This process is a process in which the connection electrode 103 and the terminal electrode 203R of the LED chip 202R are melted and bonded together by irradiating the laser light 50.

As the laser light 50, 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 203R is selected. In this embodiment, for example, near-infrared light can be used as the laser light 50. A solid-state laser such as a YAG laser or a _YVO4 laser may be used as a light source of the laser light 50. That is, the laser light 50 may be the fundamental wave of the above-mentioned solid-state laser. However, as the laser light 50, a laser light of an appropriate wavelength can be selected according to the material constituting the LED chip 202R. For example, when a semiconductor material that absorbs laser light with a wavelength shorter than that of near-infrared light is used, a green laser (green light) that is the second harmonic of the above-mentioned solid-state laser may be used.

By irradiating the laser light 50, an alloy layer (not shown) made of a eutectic alloy is formed between the connection electrode 103 and the terminal electrode 203R. As described above, in this 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 this embodiment, a layer made of a Sn-Au eutectic alloy is formed as the alloy layer. By forming an alloy layer 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 firmly joined via the alloy layer.

The light-shielding mask 40 has a plurality of openings 40a. The plurality of openings 40a are arranged, for example, to match the pitch (the distance between pixels) of the pixels corresponding to red, green, or blue. In the example shown in FIG. 4, each opening 40a is arranged to match the pitch of the pixels corresponding to red. In other words, the position of each opening 40a corresponds to the position where the LED chip 202R is arranged.

As described above, the light-shielding mask 40 of this embodiment is fixed to the holding member 30 that holds the element substrate 200. Specifically, as shown in FIG. 4, the light-shielding mask 40 is adhered to the holding member 30. Therefore, the laser light 50 is irradiated to the element substrate 200 through the holding member 30 and the light-shielding mask 40. Therefore, in this embodiment, the material of the holding member 30 is a material that transmits the fundamental wave or second harmonic of the above-mentioned solid-state laser. For example, the holding member 30 may be made of glass, quartz, or sapphire. The holding member 30 and the light-shielding mask 40 will be described later.

In this embodiment, a rectangular laser beam having an irradiation area large enough to include multiple openings 40a is used as the laser beam 50. If the irradiation area of the laser beam 50 is narrower than the light-shielding mask 40, the entire light-shielding mask 40 can be irradiated with the laser beam 50 by irradiating the area with the laser beam multiple times while moving the irradiation area.

The laser light 50 irradiated to the light-shielding mask 40 passes only through the area where the openings 40a are located. In other words, by using the light-shielding mask 40, selective laser irradiation can be performed while using laser light with a wide irradiation area. In this embodiment, the laser light 50 is selectively irradiated to the position where the LED chip 202R is arranged. In other words, according to this embodiment, the joining of multiple connection electrodes 103 and multiple LED chips 202R can be performed in a batch.

The size (area) of the opening 40a may be large enough to ensure reliable bonding between the connection electrode 103 and the terminal electrode 203R in a plan view. For example, the size of the opening 40a in a plan view may be smaller than the size of the LED chip 202R. The size of the opening 40a may also be approximately the same as the size of the LED chip 202R or slightly larger than the size of the LED chip 202R.

In this embodiment, an example is shown in which laser light with a rectangular irradiation area is used as the laser light 50, but the present invention is not limited to this example, and laser light with a linear (elongated) irradiation area may also be used. In this case, by scanning the linear laser light over the light-shielding mask 40, the entire light-shielding mask 40 can be irradiated with the laser light.

After irradiating the laser light 50, as shown in FIG. 5, the laser light 60 is selectively irradiated to the LED chips 202R irradiated with the laser light 50. In this embodiment, an example is shown in which the holding member 30 and the light-shielding mask 40 described above are used as is, but this is not limited to this example, and a different light-shielding mask may be used, or no light-shielding mask may be used.

The process shown in FIG. 5 is a process for separating the semiconductor substrate 201 and the LED chip 202Ra by irradiation with a laser beam 60, and is called laser lift-off. As the laser beam 60, a laser beam that is not absorbed by the semiconductor substrate 201 and is absorbed by the LED chip 202Ra is selected. In this embodiment, ultraviolet light is used as the laser beam 60. As a light source for the laser beam 60, a solid-state laser such as a YAG laser or a _YVO4 laser, or an excimer laser may be used. For example, when a solid-state laser is used, a second harmonic or a third harmonic may be used. However, as the laser beam 60, a laser beam of an appropriate wavelength may be selected according to the materials constituting the semiconductor substrate 201 and the LED chip 202Ra. For example, when a semiconductor material that absorbs laser beams with a wavelength longer than ultraviolet light is used, a blue laser (blue light) or a green laser (green light) may be used.

In this embodiment, the LED chip 202R irradiated with the laser light 50 is selectively irradiated with the laser light 60. As a result, the surface portion of the LED chip 202Ra (the boundary portion with the semiconductor substrate 201) is modified, and the semiconductor substrate 201 and each LED chip 202Ra can be physically separated.

After irradiation with the laser light 60, the element substrate 200 is peeled off as shown in FIG. 6. The element substrate 200 may be physically peeled off. In this case, the LED chip 202R that was not irradiated with the laser light 60 in the process shown in FIG. 5 remains on the element substrate 200. On the other hand, the LED chip 202R that was irradiated with the laser light 60 in the process shown in FIG. 5 remains on the circuit substrate 100 because it is firmly bonded to the circuit substrate 100.

As described above, the LED chip 202R corresponding to red is mounted on the circuit board 100. The LED chip 202G corresponding to green and the LED chip 202B corresponding to blue can be mounted on the circuit board 100 using the same manufacturing method as the LED chip 202R corresponding to red, so detailed explanations will be omitted. In this embodiment, the LED chips of each color are arranged at the same pitch. Therefore, the aforementioned holding member 30 and light-shielding mask 40 can be used to irradiate the LED chips of each color with laser light 50 by adjusting the position of the circuit board 100.

Through the process described above, the LED chip 202R corresponding to red, the LED chip 202G corresponding to green, and the LED chip 202B corresponding to blue are each connected to the drive circuit 102 on the circuit board 100, as shown in FIG. 7.

[Configuration of laser processing device]
In this embodiment, the configuration of the laser processing device 300 used in step S13 of FIG. 1 will be described.

Figure 8 is a diagram showing the configuration of a laser processing device 300 used in the manufacturing method of the display device 10 of the first embodiment. As shown in Figure 8, the laser processing device 300 includes a laser oscillator 302, a reflecting mirror 304, a beam expander 306, a first work unit 308, and a second work unit 310. However, the configuration of the laser processing device 300 is not limited to this example, and the reflecting mirror 304 or the beam expander 306 may be omitted, or other elements may be added.

The laser oscillator 302 of this embodiment is an Nd:YAG laser that uses as its medium a solid material in which trivalent neodymium ions (Nd ³⁺ ) are added to YAG (Yttrium Aluminum Garnet: Y ₃ Al ₅ O ₂ ) crystal. The laser oscillator 302 outputs a fundamental wave (near-infrared light) having a wavelength of 1064 nm.

The optical path of the laser light 320a output from the laser oscillator 302 is changed by the reflecting mirror 304 and directed toward the beam expander 306. The beam expander 306 is composed of a lens system that expands the beam diameter of the input collimated light. By passing through the beam expander 306, the laser light 320a is output as laser light 320b with an expanded beam diameter (i.e., irradiation range). The laser light 320b corresponds to the laser light 50 shown in FIG. 4.

In this embodiment, a case will be described in which the irradiation range of the laser light 320b is narrower than the area of the second work unit 310. In this case, the irradiation range of the laser light 320b can be moved relative to the second work unit 310 to cover the area of the object to be processed that requires processing. To move the irradiation range of the laser light 320b, for example, an optical system consisting of the laser oscillator 302, the reflecting mirror 304, and the beam expander 306 may be moved. Conversely, the irradiation range of the laser light 320b may be moved relatively by moving the first work unit 308 and the second work unit 310.

The laser light 320b output from the beam expander 306 is irradiated via the second work unit 310 to an object to be processed (not shown) disposed between the first work unit 308 and the second work unit 310. In this embodiment, the LED chip 202 (for example, the LED chip 202R shown in FIG. 4) is the object to be processed.

The first work unit 308 includes a holding member 70, which holds a substrate or the like that supports an object to be processed. In this embodiment, the holding member 70 has a function of holding a substrate or the like by vacuum suction. There are no particular limitations on the material that constitutes the holding member 70, and for example, glass, quartz, ceramics, etc. can be used.

The second work unit 310 includes a holding member 30 and a light-shielding mask 40, and holds a substrate or the like that supports an object to be processed. Like the holding member 70, the holding member 30 has the function of holding a substrate or the like by vacuum suction. As described above, the light-shielding mask 40 is adhered to the holding member 30. In other words, the holding member 30 and the light-shielding mask 40 have an integrated structure.

In this embodiment, the holding member 30 is made of a material that transmits the laser light 320b. In this embodiment, near-infrared light is used as the laser light 320b, so it is desirable for the holding member 30 to have a function that transmits light with a wavelength of about 1.0 μm. For this reason, the material that constitutes the holding member 30 can be, for example, glass, quartz, or sapphire. However, this is not limited to this example, and the material that constitutes the holding member 30 can be appropriately selected depending on the wavelength of the laser light to be used.

The light-shielding mask 40 has a plurality of openings 40a, and can selectively transmit the laser light 320b through the plurality of openings 40a. The light-shielding mask 40 can be made of a metal material such as invar. If the holding member 30 is made of an insulating material such as glass, quartz, or sapphire, the light-shielding mask 40 can be adhered to the holding member 30 via an adhesive layer or the like.

Figure 9 is a diagram showing the irradiation process of laser light 320b performed using the laser processing device 300. The irradiation process shown in Figure 9 corresponds to the irradiation process of laser light 50 shown in Figure 4.

As shown in FIG. 9, the circuit board 100 is held by vacuum suction on the holding member 70 of the first work unit 308. The element substrate 200 is held by vacuum suction on the holding member 30 of the second work unit 310 via the light-shielding mask 40. Therefore, there is no gap between the light-shielding mask 40 and the element substrate 200, and the element substrate 200 is in close contact with the light-shielding mask 40.

The circuit board 100 is held on the holding member 70, and the element board 200 is held on the holding member 30 (strictly speaking, the light-shielding mask 30), and the circuit board 100 and the element board 200 are aligned with each other. That is, as shown in FIG. 3, the circuit board 100 and the element board 200 are positioned so that the connection electrode 103 of the circuit board 100 and the terminal electrode 203R of the LED chip 202R are in contact with each other.

After the circuit board 100 and the element substrate 200 are aligned, the laser light 320b is irradiated as shown in FIG. 9. At this time, since the light-shielding mask 40 and the element substrate 200 are in close contact with each other, the laser light 320b that passes through the multiple openings 40a is incident on the element substrate 200 without being diffracted. Therefore, according to this embodiment, the laser light 320b can be selectively irradiated to the LED chip 202R while preventing the diffraction of the laser light 320b.

Here, the structure of the second work unit 310 that holds the element substrate 200 will be described. Specifically, the structures of the holding member 30 and the light-shielding mask 40 that constitute the second work unit 310 will be described.

Figure 10 is a diagram showing the configuration of the second work unit 310 in the laser processing device 300 used in the manufacturing method of the display device 10 of the first embodiment. Specifically, Figure 10 corresponds to a view of the second work unit 310 as seen from the side holding the object to be processed. Note that in Figure 10, a light-shielding mask 40 is placed on the forefront of the second work unit 310. Therefore, for ease of explanation, part of the light-shielding mask 40 is not shown.

As shown in FIG. 10, the holding surface 30a of the holding member 30 has a processing area 31 and an adsorption area 32. The processing area 31 is an area for irradiating the element substrate 200, which is the object to be processed, with laser light 320b. The holding member 30 holds the element substrate 200 by vacuum adsorbing the semiconductor substrate 201 of the element substrate 200 to the holding surface 30a. At this time, the multiple LED chips 202 provided on the element substrate 200 are all configured to fit inside the processing area 31. In other words, when the element substrate 200 is held by the holding member 30, the multiple LED chips 202 are positioned so as to overlap the processing area 31.

The suction region 32 is a region for vacuum-adsorbing the element substrate 200. As shown in FIG. 10, the holding member 30 has a plurality of suction holes 32a in the suction region 32. That is, the suction region 32 uses the plurality of suction holes 32a to adsorb the element substrate 200. The suction region 32 is provided so as to surround the processing region 31. In other words, when the element substrate 200 is held by the holding member 30, the plurality of LED chips 202 do not overlap the suction region 32.

As described above, the light-shielding mask 40 has a plurality of openings 40a. As shown in FIG. 10, the plurality of openings 40a are arranged inside the processing region 31. The light-shielding mask 40 also has a plurality of suction holes 40b. The plurality of suction holes 40b are provided so as to overlap with the suction region 32. That is, the plurality of suction holes 40b are provided so as to surround the plurality of openings 40a. At this time, the plurality of suction holes 32a provided in the holding member 30 and the plurality of suction holes 40b provided in the light-shielding mask 40 at least partially overlap. Preferably, each suction hole 32a and each suction hole 40b approximately coincide with each other. In this way, by providing the suction holes 40b in the light-shielding mask 40 as well, the holding member 30 can suction the element substrate 200 through the light-shielding mask 40.

In this embodiment, the outer shape of the suction holes 32a and 40b is circular, but this is not limited to the example. The outer shape of the suction holes 32a and 40b may be polygonal or elliptical. Furthermore, the suction holes 32a and 40b do not have to be holes, and may be grooves. For example, the suction holes 32a and 40b may be grooves that run along concentric circles of the holding member 30.

As described above, the laser processing device 300 of this embodiment includes a second work unit 310 in which the holding member 30 and the light-shielding mask 40 are integrally configured, and is configured to irradiate the object to be processed with laser light 320b via the holding member 30. When the laser processing device 300 of this embodiment is used, no gap is generated between the light-shielding mask 40 and the object to be processed (in this embodiment, the element substrate 200), so it is possible to prevent diffraction of the laser light that passes through the opening 40a of the light-shielding mask 40.

In addition, in this embodiment, the laser light 320a output from the laser oscillator 302 is expanded and irradiated by the beam expander 306, making it possible to irradiate a wide range of laser light at once. Therefore, according to this embodiment, it is possible to carry out a laser light irradiation process with high throughput while preventing diffraction of the laser light.

[Configuration of the display device]
The configuration of a display device 10 according to a first embodiment of the present invention will be described with reference to FIGS.

Figure 11 is a plan view showing a schematic configuration of a display device 10 in the first embodiment. As shown in Figure 11, the display device 10 has a circuit board 100, a flexible printed circuit board 160 (FPC 160), 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 LED chips 202 are arranged in the row direction (D1 direction) and column direction (D2 direction). Specifically, in this embodiment, a pixel 110R including an LED chip 202R, a pixel 110G including an LED chip 202G, and a pixel 110B including an LED chip 202B are arranged. The display area 112 functions as an area for displaying an image according to a video signal.

The peripheral region 114 is the region surrounding the display region 112. The peripheral region 114 is a region in which driver circuits (the data driver circuit 130 and the gate driver circuit 140 shown in FIG. 16) for controlling the pixel circuits (the pixel circuits 120 shown in FIG. 17) provided in each pixel 110 are provided.

The terminal area 116 is an area where multiple wirings connected to the driver circuit described above are aggregated. The flexible printed circuit board 160 is electrically connected to the multiple wirings in the terminal area 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 wirings (not shown) provided on the flexible printed circuit board 160. The IC chip 170 performs various signal processing on the video signal and generates control signals required for display control. The video signal and 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. 12 is a block diagram showing a circuit configuration of the display device 10 according to the first embodiment. As shown in Fig. 12, a pixel circuit 120 is provided in the display region 112 in correspondence with each pixel 110. In this embodiment, a pixel circuit 120R, a pixel circuit 120G, and a pixel circuit 120B are provided in correspondence with the pixel 110R, the pixel 110G, and the pixel 110B, respectively. That is, a plurality of pixel circuits 120 are arranged in the row direction (D1 direction) and the column direction (D2 direction) in the display region 112.

Figure 13 is a circuit diagram showing the configuration of a pixel circuit 120 of the display device 10 according to the first embodiment. The pixel circuit 120 is arranged in an area surrounded by a data line 121, a gate line 122, an anode power line 123, and a cathode power line 124. The pixel circuit 120 of this embodiment includes a selection transistor 126, a drive transistor 127, a storage capacitor 128, and an LED 129. The LED 129 corresponds to each LED chip 202 shown in Figure 11. Of the pixel circuit 120, the circuit elements other than the LED 129 correspond to the drive circuit 102 provided on the circuit board 100. In other words, the pixel circuit 120 is completed in a state where the LED chip 202 is mounted on the circuit board 100.

As shown in FIG. 13, the source electrode, gate electrode, and drain electrode of the selection transistor 126 are connected to the data line 121, the gate line 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 line 123, the drain electrode of the selection transistor 126, and the LED 129, respectively. A storage capacitor 128 is connected between the gate electrode and drain electrode of the drive transistor 127. That is, the storage capacitor 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 of the drive transistor 127 and the cathode power line 124, respectively.

A gradation signal that determines the light emission intensity of the LED 129 is supplied to the data line 121. A gate signal for selecting the selection transistor 126 to which the gradation signal is written is supplied to the gate line 122. When the selection transistor 126 is turned on, the gradation signal is stored in the holding capacitance 128. When the drive transistor 127 is then 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 again to FIG. 12, a data driver circuit 130 is disposed adjacent to the display area 112 in the column direction (direction D2). A gate driver circuit 140 is disposed adjacent to the display area 112 in the row direction (direction D1). In this embodiment, two gate driver circuits 140 are provided on both sides of the display area 112, but only one of them may be provided.

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

The data line 121 shown in FIG. 13 extends from the data driver 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.

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

[Cross-sectional structure of display device 10]
14 is a cross-sectional view showing the configuration of a pixel 110 of the display device 10 according to the first embodiment. The pixel 110 has a drive transistor 127 provided on an 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 driving 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. 13.

Wiring 18 is provided in the same layer as the source electrode 16 and the drain electrode 17. Wiring 18 functions as the anode power line 123 shown in FIG. 13. Therefore, the source electrode 16 and wiring 18 are electrically connected by a connection wiring 20 provided on a planarization layer 19. The planarization 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, this is not limiting, and other metal materials can also 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 this 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 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 mounting pads 25a and 25b, respectively, via a 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 electrode 103 shown in FIG. 3. That is, in this embodiment, electrodes made of tin (Sn) are arranged as the connection electrodes 103a and 103b.

The terminal electrodes 203a and 203b of the LED chip 202 are joined to the connection electrodes 103a and 103b, respectively. As described above, in this embodiment, the terminal electrodes 203a and 203b are electrodes made of gold (Au).

The LED chip 202 corresponds to the LED 129 in the circuit diagram shown in FIG. 13. That is, the terminal electrode 203a of the LED chip 202 is connected to the anode electrode 22 that is 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. 13.

The display device 10 of this embodiment, which has the above structure, has the advantage of being highly resistant to impacts, etc., because the LED chips 202 are firmly mounted by fusion bonding using laser irradiation.

Second Embodiment
In this embodiment, an example will be described in which a laser processing device 300 having a structure different from that of the first embodiment is used. Specifically, the laser processing device 300 of this embodiment includes a second work unit 320 that holds the element substrate 200 by electrostatic adsorption. In the drawings, the same elements as those in the first embodiment are denoted by the same reference numerals, and duplicated explanations will be omitted.

Figure 15 is a diagram showing the configuration of the second work unit 320 in the laser processing device 300 used in the manufacturing method of the display device 10 of the second embodiment. Specifically, Figure 15 corresponds to a view of the second work unit 320 seen from the side holding the object to be processed. Note that in Figure 10, a light-shielding mask 42 is placed on the front side of the second work unit 320. Therefore, for ease of explanation, part of the light-shielding mask 42 is not shown.

As shown in FIG. 15, the holding member 35 has a processing region 36 and an adsorption region 37. The processing region 36 is an area for irradiating the element substrate 200, which is the object to be processed, with laser light 320b (see FIG. 8). The holding member 35 holds the element substrate 200 by electrostatically adsorbing the semiconductor substrate 201 of the element substrate 200 to the holding surface 35a. At this time, similar to the first embodiment, the multiple LED chips 202 provided on the element substrate 200 are all configured to fit inside the processing region 36. Also, similar to the first embodiment, the holding member 35 is made of, for example, glass, quartz, or sapphire.

The adsorption region 37 is a region for electrostatically adsorbing the element substrate 200. As shown in FIG. 15, internal electrodes 37a and 37b are provided inside the holding member 35. That is, in a plan view, the region of the holding surface 35a that overlaps with the internal electrodes 37a and 37b corresponds to the adsorption region 37. The adsorption region 37 is provided so as to surround the processing region 36. That is, when the element substrate 200 is held by the holding member 35, the multiple LED chips 202 do not overlap with the internal electrodes 37a and 37b, and therefore the internal electrodes 37a and 37b do not block the optical path of the laser light 320b.

In this embodiment, for example, a positive voltage is applied to the internal electrode 37a, and a negative voltage is applied to the internal electrode 37b. This polarizes the internal charge of the object to be processed, and the object is attracted to the holding member 35. That is, the second work unit 320 in this embodiment holds the object to be processed (e.g., the element substrate 200) by the electrostatic force generated between the holding member 35 and the object to be processed.

As shown in FIG. 15, the multiple openings 42a of the light-shielding mask 42 are positioned inside the processing area 36. That is, the portion of the light-shielding mask 42 that is effectively used as a mask is located inside the processing area 36. In this embodiment, the light-shielding mask 42 is made of a metal film. In this case, if the thickness of the light-shielding mask 42 is sufficiently thin, it has almost no effect on the electrostatic force generated between the holding member 35 and the object to be processed. In this embodiment, the thickness of the light-shielding mask 42 is set to about several microns, making it possible to perform electrostatic adsorption via the light-shielding mask 42.

In this embodiment, the internal electrodes 37a and 37b are semicircular in plan view, but the shape is not limited to this example. The internal electrodes 37a and 37b may be polygonal or elliptical in plan view. The number of electrodes provided inside the holding member 35 is not limited to two, and may be three or more.

As described above, the laser processing device 300 of this embodiment includes a second work unit 320 in which the holding member 35 and the light-shielding mask 42 are integrally configured, and is configured to irradiate the object to be processed with laser light 320b via the holding member 35. When the laser processing device 300 of this embodiment is used, no gap is generated between the light-shielding mask 42 and the object to be processed (in this embodiment, the element substrate 200), so that it is possible to prevent diffraction of the laser light that passes through the opening 42a of the light-shielding mask 42.

Third Embodiment
In the first and second embodiments, an example in which the LED chips 202 are directly transferred from the element substrate 200 to the circuit substrate 100 has been shown, but the present invention is not limited to this example. Specifically, the LED chips 202 of the element substrate 200 may be temporarily transferred to a carrier substrate, and then transferred from the carrier substrate to the circuit substrate 100. Even in this case, the laser processing device 300 described in the first and second embodiments can be used when melting and joining the terminal electrodes 203 of the LED chips 202 and the connection electrodes 103 of the circuit substrate 100.

Fourth Embodiment
In the first and second embodiments, an example is shown in which the object to be processed (the element substrate 200) is held by using the suction force of the holding member, but the present invention is not limited to this example. For example, instead of suction, a method of mechanically holding the object by a claw or a method of holding the object by adhesion using an adhesive or an adhesive sheet may be used. In other words, the holding member may hold the object to be processed by any method as long as it does not interfere with the laser light irradiation process.

Fifth Embodiment
In the first and second embodiments, the holding member and the light-shielding mask are separate members, but the present invention is not limited to this example. For example, a structure in which the holding member and the light-shielding mask are integrally formed may be used as the second work unit. For example, a region that functions as a light-shielding mask may be formed by adding a black substance such as a black pigment or carbon black to the holding surface of a holding member made of glass, quartz, sapphire, or the like.

The above-described embodiments of the present invention may be combined as appropriate to the extent that they are not mutually inconsistent. Those in which a person skilled in the art has appropriately added or removed components or modified designs, or added or omitted steps or modified conditions based on the embodiments, are also included in the scope of the present invention as long as they include the gist of the present invention.

Furthermore, even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, if they are clear from the description in this specification or can be easily predicted by a person skilled in the art, they are naturally understood to be brought about by the present invention.

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...planarizing layer, 20...connecting wiring, 21...insulating layer, 22...anode electrode, 23...cathode electrode, 24...planarizing layer, 25a, 25b...mounting pad, 40, 42...light-shielding mask, 40a, 42a...opening, 30, 35...retention Holding member, 30a, 35a...holding surface, 31, 36...processing area, 32, 37...suction area, 32a, 40b...suction hole, 37a, 37b...internal electrode, 50, 60...laser light, 70...holding member, 100...circuit board, 101...substrate, 102...drive circuit, 103, 103a, 103b...connection electrode, 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 line, 124... cathode power line, 126... selection transistor, 127... driving transistor, 128... storage capacitor, 130... data driver circuit, 140... gate driver circuit, 150... terminal portion, 151, 152... connection wiring, 160... flexible printed circuit Substrate, 170...IC chip, 200...element substrate, 201...semiconductor substrate, 202, 202R, 202G, 202B...LED chips, 203a, 203b, 203R...terminal electrodes, 300...laser processing device, 302...laser oscillator, 304...reflection mirror, 306...beam expander, 308...first work unit, 310...second work unit, 320a, 320b...laser light,

Claims (7)

A first substrate having a plurality of LED chips is provided;
disposing the plurality of LED chips on the second substrate such that the plurality of LED chips are located between the first substrate and the second substrate;
irradiating a part of the plurality of LED chips with laser light through a light-shielding mask fixed to a holding member that holds the first substrate;
the light-shielding mask is disposed on the first substrate side of the holding member and in close contact with the first substrate;
the holding member has a plurality of first suction holes,
the light-shielding mask has a plurality of openings and a plurality of second suction holes disposed so as to surround the plurality of openings;
A portion of the first suction hole overlaps with the second suction hole,
the holding member holds the first substrate by vacuum suction via the first suction hole and the second suction hole;
the laser light passes through the holding member and the plurality of openings formed in the light-shielding mask;
A method for manufacturing a display device. The method for manufacturing a display device according to claim 1, wherein the laser light is irradiated onto some of the LED chips via the holding member. The method for manufacturing a display device according to claim 1 , wherein when the first substrate is held by the holding member, the plurality of LED chips do not overlap suction holes formed in the holding member in a plan view. The method for manufacturing a display device according to claim 1 , wherein the irradiation of the laser light includes scanning the light-shielding mask with a linear laser light. The method for manufacturing a display device according to claim 1 , wherein the laser light is a fundamental wave or a second harmonic wave of a solid-state laser. the laser light is near-infrared light,
The method for manufacturing a display device according to claim 1 , wherein the holding member is made of glass, quartz, or sapphire. The method for manufacturing a display device according to claim 6 , wherein the laser light is irradiated to bond connection electrodes on the second substrate to terminal electrodes of some of the plurality of LED chips.

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