Display device manufacturing method

Abstract

To improve yield in separating an LED chip and a semiconductor substrate from each other by using laser irradiation.SOLUTION: A method for manufacturing a display includes: preparing a first substrate having a plurality of LED chips that are arranged in M columns×N rows (M, N are an integer of 1 or more); bonding the first substrate to a second substrate with the plurality of LED chips therebetween; selectively irradiating a first group of LED chips of the plurality of LED chips with a laser beam to separate the first group of LED chips from the first substrate; and selectively irradiating a second group of LED chips of the plurality of LED chips with a laser beam to separate the second group of LED chips from the first substrate. When the positions of the first group of LED chips are represented by (Mx, Ny), the positions of the second group of LED chips are represented by (Mx±1, Ny) or (Mx, Ny±1).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method for manufacturing a display device, and more particularly to a method for manufacturing a display device mounted with an LED (Light Emitting Diode) chip. [Background technology]

[0002] 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.

[0003] 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 bonded to the circuit board, and then only the support substrate is removed. For example, Patent Document 1 describes a technique in which, after bonding the LED chips to the circuit board, the LED chips are separated from the support substrate using a method called laser lift-off (LLO). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 10,096,740 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to improve the yield when separating an LED chip from a semiconductor substrate using laser irradiation. [Means for solving the problem]

[0006] A method for manufacturing a display device according to one embodiment of the present invention includes the steps of preparing a first substrate having a plurality of LED chips arranged in M ​​rows by N columns (M and N are integers of 1 or more), bonding the first substrate to a second substrate via the plurality of LED chips, selectively irradiating a first group of LED chips among the plurality of LED chips with laser light to separate the first group of LED chips from the first substrate, and selectively irradiating a second group of LED chips among the plurality of LED chips with laser light to separate the second group of LED chips from the first substrate, wherein the positions of the LED chips in the first group are (M x ,N y ), each position of the second group of LED chips is expressed as (M x±1 ,N y ) or (M x ,N y±1 ) [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 3 is a flowchart showing a method for manufacturing the display device according to the first embodiment. [Figure 2] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 3] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 4] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 5] FIG. 3 is a plan view for explaining the arrangement of a first group of LEDs and a second group of LEDs in the first embodiment. [Figure 6] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 7] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 8A] 3 is a plan view showing a state of an LED chip bonded to a carrier substrate in the manufacturing method of the display device according to the first embodiment. FIG. [Figure 8B]10 is a plan view showing a state of an LED chip adhered to a carrier substrate in a manufacturing method of a display device in a comparative example. FIG. [Figure 9] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 10] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 11] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 12] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 13] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 14] 3A to 3C are cross-sectional views illustrating a method for manufacturing the display device according to the first embodiment. [Figure 15] FIG. 1 is a plan view showing a schematic configuration of a display device according to a first embodiment. [Figure 16] 1 is a block diagram showing a circuit configuration of a display device according to a first embodiment. [Figure 17] 1 is a circuit diagram showing a configuration of a pixel circuit of a display device according to a first embodiment. [Figure 18] 1 is a cross-sectional view showing the configuration of a pixel of a display device according to a first embodiment. [Figure 19] 10 is a plan view for explaining the arrangement of a first group of LEDs, a second group of LEDs, a third group of LEDs, and a fourth group of LEDs in a second embodiment. FIG. [Figure 20] FIG. 11 is a plan view for explaining the arrangement of the first group of LEDs and the second group of LEDs in the third embodiment. [Figure 21] FIG. 11 is a plan view for explaining the arrangement of the first group of LEDs and the second group of LEDs in the third embodiment. [Figure 22] 10A to 10C are cross-sectional views illustrating a method for manufacturing a display device according to a fifth embodiment. [Figure 23] 10A to 10C are cross-sectional views illustrating a method for manufacturing a display device according to a fifth embodiment. [Figure 24] 10A to 10C are cross-sectional views illustrating a method for manufacturing a display device according to a fifth embodiment. [Figure 25] 10A to 10C are cross-sectional views illustrating a method for manufacturing a display device according to a fifth embodiment. [Figure 26] 10A to 10C are cross-sectional views illustrating a method for manufacturing a display device according to a fifth embodiment. [Figure 27] 10A to 10C are cross-sectional views illustrating a method for manufacturing a display device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in various forms without departing from the spirit of the present 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 more schematically than the actual form. However, the drawings are merely examples and do not limit the interpretation of the present invention.

[0009] When describing 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 terms "upper" and "lower" merely describe the upper-level relationship of each element. For example, the term "LED chip is disposed on a substrate" also includes cases where other members are interposed between the substrate and the LED chip. Furthermore, the terms "upper" and "lower" include not only cases where elements overlap in a plan view, but also cases where they do not overlap.

[0010] When describing embodiments of the present invention, elements having the same functions as elements already described may be designated by the same reference numeral or the same reference numeral with an alphabet or other symbol, and the description thereof may be omitted. Furthermore, when it is necessary to describe a certain element separately for each of the RGB colors, the reference numeral for that element is followed by an R, G, or B symbol to distinguish between them. However, when it is not necessary to describe a certain element separately for each of the RGB colors, the element will be described using only the reference numeral for that element.

[0011] First Embodiment [Display device manufacturing method] FIG. 1 is a flowchart 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 202R formed on an element substrate 200 to a carrier substrate 301. FIGS. 2 to 4, 6, and 7 are cross-sectional views showing the method for manufacturing the display device 10 in the first embodiment. FIG. 5 is a plan view for explaining the arrangement of the first group of LEDs and the second group of LEDs in the first embodiment. First, the process up to transferring each LED chip 202R to the carrier substrate 301 will be described using FIG. 1. Specific examples of each process will be described using FIGS. 2 to 7.

[0012] First, in step S11 of FIG. 1, an element substrate 200 is prepared having a plurality of LED chips 202R arranged in M ​​rows and N columns (M and N are integers equal to or greater than 1) (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. The semiconductor substrate 201 can be, for example, a sapphire substrate. The semiconductor layer can be, for example, gallium nitride (GaN). However, this is not limiting, and the LED chips 202R may be formed using a semiconductor layer (e.g., 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.

[0013] Next, in step S12 of FIG. 1, the element substrate 200 is bonded to a carrier substrate 301 via the plurality of LED chips 202R (see FIG. 3). The carrier substrate 301 is a sheet member made of silicon or acrylic and has adhesive properties. The adhesive strength of the carrier substrate 301 can be adjusted by irradiation with laser light, etc. A known carrier substrate can be used as such a carrier substrate 301.

[0014] 1, laser light 40 is selectively applied to the first group of LED chips 202Ra among the plurality of LED chips 202R, thereby separating the first group of LED chips 202Ra from the element substrate 200 (see FIG. 4). Specifically, as shown in FIG. 4, the LED chips 202Ra are separated from the semiconductor substrate 201 by applying laser light 40 through a light-shielding mask 30. This process is known as laser lift-off.

[0015] 4, laser light 40 is irradiated only onto the first group of LED chips 202Ra among the plurality of LED chips 202R included in the element substrate 200. Specifically, laser light 40 is irradiated selectively onto the first group of LED chips 202Ra from among the plurality of LED chips 202R including the first group of LED chips 202Ra and the second group of LED chips 202Rb.

[0016] The arrangement of the first group of LED chips 202Ra and the second group of LEDs 202Rb is as shown in FIG. 5. As shown in FIG. 5, the first group of LED chips 202Ra and the second group of LED chips 202Rb are arranged in a staggered pattern. That is, in each row and each column, the first group of LED chips 202Ra and the second group of LED chips 202Rb are arranged alternately. When divided as shown in FIG. 5, the number of LED chips 202Ra in the first group and the number of LED chips 202Rb in the second group are approximately the same. Here, "approximately the same" includes not only cases where they are exactly the same, but also cases where there is a difference within a range that can be considered to be substantially the same.

[0017] 4 has a plurality of openings 30a arranged in a staggered pattern in plan view in accordance with the arrangement of the LED chips 202R described above. As described above, the number of the first group of LED chips 202Ra is half of the total number of LED chips 202R included in the element substrate 200, and therefore the pitch between the plurality of openings 30a is twice the pitch between the plurality of LED chips 202R. However, this is not the only example, and if the number of LED chips to be processed is even smaller, the pitch between the plurality of openings 30a may be more than twice as large.

[0018] The laser light 40 is selected to be one that is not absorbed by the semiconductor substrate 201 and is absorbed by the LED chip 202Ra. In this embodiment, ultraviolet light is used as the laser light 40. A solid-state laser such as a YAG laser or a YVO4 laser, or an excimer laser may be used as the light source of the laser light 40. However, it is possible to select laser light of an appropriate wavelength for the laser light 40 depending on the materials constituting the semiconductor substrate 201 and the LED chip 202Ra. For example, when using a semiconductor material that absorbs laser light with a wavelength longer than ultraviolet light, a blue laser (blue light) or a green laser (green light) may be used.

[0019] 4, a rectangular laser beam having an irradiation area large enough to encompass the plurality of openings 30a is used as the laser beam 40. If the irradiation area of ​​the laser beam 40 is narrower than the light-shielding mask 30, the laser beam may be irradiated multiple times while moving the irradiation area. Furthermore, without being limited to this example, the laser beam 40 may be a laser beam having a linear (long, thin) irradiation area, which is used to scan the light-shielding mask 30.

[0020] The laser light 40 irradiated onto the light-shielding mask 30 passes only through the portions where the openings 30a are located. In other words, by using the light-shielding mask 30, it is possible to perform selective laser irradiation while using laser light with a wide irradiation area. In this embodiment, the laser light 40 is selectively irradiated onto the positions where the LED chips 202R are arranged. As a result, the surface portion of the LED chips 202Ra (the boundary portion with the semiconductor substrate 201) is modified, making it possible to separate the semiconductor substrate 201 and each LED chip 202Ra.

[0021] The size (area) of the opening 30a may be large enough to reliably separate the LED chip 202Ra from the semiconductor substrate 201 in a plan view. For example, the size of the opening 30a in a plan view may be smaller than the size of the LED chip 202Ra. Alternatively, the size of the opening 30a may be approximately the same as or slightly larger than the size of the LED chip 202Ra.

[0022] 1, laser light 40 is selectively applied to the second group of LED chips 202Rb among the plurality of LED chips 202R, thereby separating the second group of LED chips 202Rb from the element substrate 200 (see FIG. 6). Specifically, as shown in FIG. 6, the semiconductor substrate 201 and the LED chips 202Rb are separated collectively by irradiation with laser light 40 via a light-shielding mask 30. This process is laser lift-off, similar to the process shown in FIG. 4.

[0023] In the process shown in FIG. 6, of the multiple LED chips 202R included in the element substrate 200, only the second group of LED chips 202Rb are irradiated with laser light 40. As described above, the second group of LED chips 202Rb are arranged in a staggered pattern, similar to the first group of LED chips 202Ra. Therefore, the process shown in FIG. 6 can use the same light-shielding mask 30 as in the process shown in FIG. 4. Therefore, in this embodiment, after performing the process shown in FIG. 4, the process shown in FIG. 6 can be performed consecutively by simply shifting the position of the light-shielding mask 30. Details of the process shown in FIG. 6 are the same as those of the process shown in FIG. 4, and therefore will not be described here.

[0024] 4 and 6, the semiconductor substrate 201 and each LED chip 202R are separated. Specifically, the semiconductor substrate 201 is physically peeled off from the carrier substrate 301. At this time, each LED chip 202R remains on the carrier substrate 301 because it is adhered to the carrier substrate 301. This allows multiple LED chips 202R to be transferred onto the carrier substrate 301, as shown in FIG. 7.

[0025] As described above, in this embodiment, the separation of the LED chips R by laser lift-off is performed in two separate steps. In this case, the separation is not simply performed in two separate steps, but also, as shown in FIG. 5, the density of the LED chips 202R that are the processing targets in one lift-off process is reduced. The reason for this will be explained below. Furthermore, as will be described later, the separation of the LED chips R may be performed in more than two separate steps.

[0026] As described above, the laser light 40 (here, ultraviolet light) irradiated from the semiconductor substrate 201 side passes through the semiconductor substrate 201 made of sapphire and is absorbed by the semiconductor layer (e.g., GaN layer). In this embodiment, the laser light 40 has a short wavelength and high energy density, so the semiconductor layer absorbs the energy rapidly and instantaneously sublimes, generating gas. At this time, if the density of the LED chips 202R to be processed is high, the amount of gas generated also increases. Therefore, the shock caused by the large amount of gas generated may cause the position of the LED chips 202R bonded to the carrier substrate 301 to shift.

[0027] Fig. 8A is a plan view showing a state of the LED chips 202 bonded to the carrier substrate 301 in the manufacturing method of the display device 10 in the first embodiment. Fig. 8B is a plan view showing a state of the LED chips bonded to the carrier substrate in the manufacturing method of the display device in the comparative example. Specifically, Fig. 8B shows an example in which the lift-off process is performed collectively on the LED chips 202 included in the element substrate 200.

[0028] As shown in FIG. 8A, according to this embodiment, the arrangement of the multiple LED chips 202 on the carrier substrate 301 is not disordered, and each LED chip 202 is arranged orderly in the row and column directions. This is because, according to this embodiment, the number of LED chips to be processed in each lift-off process is half of the total, thereby reducing the amount of gas generated. Furthermore, as shown in FIG. 5, the LED chips 202 to be processed are arranged in a staggered pattern, so there are no adjacent LED chips 202 in the row and column directions. Therefore, each LED chip 202 is less susceptible to the influence of gas generated by adjacent LED chips.

[0029] 8B, in the comparative example, the arrangement of the multiple LED chips 202 on the carrier substrate 301 is significantly disrupted. This is because the comparative example generates twice as much gas as the present embodiment, and the distance between adjacent LED chips 202 is short, making them more susceptible to mutual influence.

[0030] As described above, in this embodiment, when transferring the multiple LED chips 202 from the element substrate 200 to the carrier substrate 301, the separation process by laser lift-off is performed multiple times. This reduces the amount of gas generated in each process and makes it less susceptible to the influence of gas generated by adjacent LED chips. As a result, it is possible to prevent the positional deviation of each LED chip 202 bonded to the carrier substrate 301, and improve the yield when separating the LED chips 202 from the semiconductor substrate using laser irradiation.

[0031] Next, the process after transferring the LED chips 202R to the carrier substrate 301 will be described.

[0032] As shown in Fig. 9, the carrier substrate 301 is bonded to the carrier substrate 401 via the plurality of LED chips 202R. The carrier substrate 401 is a sheet member made of silicon or acrylic, similar to the carrier substrate 301, and has adhesive properties. The adhesive strength of the carrier substrate 401 can be adjusted by irradiation with laser light, etc. A known carrier substrate can be used as the carrier substrate 401.

[0033] 10, the carrier substrate 301 is peeled off from the carrier substrate 401. There are no particular limitations on the method for peeling off the carrier substrate 301. For example, the carrier substrate 301 can be physically peeled off by setting the adhesive force for fixing each LED chip 202 to the carrier substrate 401 to be greater than the adhesive force for fixing each LED chip 202 to the carrier substrate 301. Alternatively, ultraviolet light may be irradiated from the carrier substrate 301 side to modify the interface between the carrier substrate 301 and each LED chip 202 (specifically, the terminal electrodes of each LED chip 202), and then the carrier substrate 301 may be physically peeled off.

[0034] 11 , the carrier substrate 401 is placed on the circuit substrate 100 so that the connection electrodes 103 face each LED chip 202R. Specifically, the circuit substrate 100 and the carrier substrate 401 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.

[0035] The circuit board 100 has regions corresponding to a plurality of pixels. As shown in FIG. 11, the circuit board 100 has, on a substrate 101 having an insulating surface, a driving circuit 102 that drives an LED chip corresponding to each pixel. 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 plurality of thin film transistors (TFTs). Each connection electrode 103 is disposed in each pixel and is connected to the driving circuit 102. The detailed structure of the circuit board 100 will be described later.

[0036] In this embodiment, an example is shown in which the driving circuits 102 and the connecting electrodes 103 are formed on the substrate 101 using a thin film formation technique, but the present invention is not limited to this example. For example, a substrate (a so-called active matrix substrate) on which the driving circuits 102 are formed on the substrate 101 may be obtained as a ready-made product from a third party. In this case, the connecting electrodes 103 may be formed on the obtained substrate.

[0037] Furthermore, in this embodiment, a flip-chip type LED chip is described as an example of the LED chip 202, but the LED chip 202 is not limited to this example. For example, the LED chip 202 may have an anode electrode (or 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 202 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.

[0038] 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 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 a range of 0.2 μm to 5 μm (preferably, 1 μm to 3 μm).

[0039] 12, the connection electrodes 103 and the LED chip 202R are bonded together by irradiation with laser light 50 through a light-shielding mask 35. This process involves melting and bonding the connection electrodes 103 and the terminal electrodes 203R of the LED chip 202R by irradiation with laser light 50.

[0040] The laser light 50 is selected to be one that is not absorbed by the carrier substrate 401 and the LED chip 202R, but is absorbed by the connection electrode 103 or the terminal electrode 203R. In this embodiment, for example, infrared light or 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 the light source of the laser light 50. However, it is possible to select laser light of an appropriate wavelength for the laser light 50 depending on the material constituting the LED chip 202R. For example, when a semiconductor material that absorbs laser light with a shorter wavelength than infrared light is used, a green laser (green light) can also be used.

[0041] By irradiating the laser beam 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.

[0042] In this embodiment, a light-shielding mask 35 having a plurality of openings 35a is used when irradiating the laser light 50. The plurality of openings 35a are arranged, for example, to match the pitch (inter-pixel spacing) of pixels corresponding to red, green, or blue. In the example shown in FIG. 12, the openings 35a are arranged to match the pitch of the pixels corresponding to red. That is, the position of each opening 35a corresponds to the position where the LED chip 202R is arranged.

[0043] In this embodiment, a rectangular laser beam having an irradiation area large enough to include the plurality of openings 35a is used as the laser beam 50. When the irradiation area of ​​the laser beam 50 is narrower than the light-shielding mask 35, the entire light-shielding mask 35 can be irradiated with the laser beam 50 by irradiating the laser beam multiple times while moving the irradiation area.

[0044] The laser light 50 irradiated onto the light-shielding mask 35 passes only through the portions where the openings 35a are located. In other words, by using the light-shielding mask 35, it is possible to perform selective laser irradiation while using laser light with a wide irradiation area. In this embodiment, the laser light 50 is selectively irradiated onto the positions where the LED chips 202R are arranged. In other words, according to this embodiment, multiple connection electrodes 103 and multiple LED chips 202R can be bonded together at the same time.

[0045] The size (area) of the opening 35a may be large enough to reliably bond the connection electrode 103 and the terminal electrode 203R in a plan view. For example, the size of the opening 35a in a plan view may be smaller than the size of the LED chip 202R. Alternatively, the size of the opening 35a may be approximately the same as the size of the LED chip 202R or slightly larger than the size of the LED chip 202R.

[0046] In this embodiment, an example in which laser light having a rectangular irradiation area is used as the laser light 50 has been described, but the present invention is not limited to this example, and laser light having a linear (elongated) irradiation area may also be used. In this case, by scanning the linear laser light over the light-shielding mask 35, the entire light-shielding mask 35 can be irradiated with the laser light.

[0047] After irradiation with the laser beam 50, the carrier substrate 401 is peeled off as shown in Fig. 13. The carrier substrate 401 may be physically peeled off. In this case, the LED chip 202R that is not irradiated with the laser beam 50 is not bonded to the circuit board 100 and therefore remains on the carrier substrate 401. On the other hand, the LED chip 202R that is irradiated with the laser beam 50 in the process shown in Fig. 12 is firmly bonded to the circuit board 100 and therefore remains on the circuit board 100.

[0048] Through the process 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 by the same manufacturing method as the LED chip 202R corresponding to red, and therefore detailed description thereof will be omitted. As shown in Fig. 14, 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.

[0049] [Display device configuration] The configuration of a display device 10 according to a first embodiment of the present invention will be described with reference to FIGS.

[0050] Fig. 15 is a plan view showing a schematic configuration of a display device 10 according to the first embodiment. As shown in Fig. 15, 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.

[0051] The display area 112 is an area in which a plurality of pixels 110, each including an LED chip 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 in response to a video signal.

[0052] The peripheral region 114 is a region surrounding the display region 112. The peripheral region 114 is a region where driver circuits (the data driver circuit 130 and the gate driver circuit 140 shown in FIG. 16) for controlling pixel circuits (the pixel circuits 120 shown in FIG. 17) provided in each pixel 110 are provided.

[0053] The terminal area 116 is an area where a plurality of wirings connected to the driver circuit described above are aggregated. The flexible printed circuit board 160 is electrically connected to the plurality of 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.

[0054] [Circuit configuration of display device 10] Fig. 16 is a block diagram showing the circuit configuration of the display device 10 according to the first embodiment. As shown in Fig. 16, a pixel circuit 120 is provided in the display region 112 corresponding to each pixel 110. In this embodiment, a pixel circuit 120R, a pixel circuit 120G, and a pixel circuit 120B are provided corresponding to the pixel 110R, the pixel 110G, and the pixel 110B, respectively. That is, in the display region 112, a plurality of pixel circuits 120 are arranged in the row direction (direction D1) and the column direction (direction D2).

[0055] 17 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 data lines 121, gate lines 122, anode power lines 123, and cathode power lines 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 FIG. 15. 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 when the LED chip 202 is mounted on the circuit board 100.

[0056] 17, the source electrode, gate electrode, and drain electrode of the selection transistor 126 are connected to the data line 121, gate line 122, and 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 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 supply line 124, respectively.

[0057] A grayscale signal that determines the light emission intensity of the LED 129 is supplied to the data line 121. A gate signal that selects a selection transistor 126 to which the grayscale signal is written is supplied to the gate line 122. When the selection transistor 126 is turned on, the grayscale signal is stored in a storage capacitor 128. After that, when the drive transistor 127 is turned on, a drive current corresponding to the grayscale 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 at a light emission intensity corresponding to the grayscale signal.

[0058] 16 again, 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.

[0059] 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.

[0060] 17 extends in the direction D2 from the data driver circuit 130 and is connected to the source electrode of the selection transistor 126 in each pixel circuit 120. The gate line 122 extends in the direction D1 from the gate driver circuit 140 and is connected to the gate electrode of the selection transistor 126 in each pixel circuit 120.

[0061] A terminal section 150 is arranged 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.

[0062] [Cross-sectional structure of the display device 10] 18 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. The insulating substrate 11 can be a glass substrate or a resin substrate having an insulating layer provided on the substrate.

[0063] 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 select transistor 126 shown in FIG.

[0064] 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 line 123 shown in FIG. 17. Therefore, the source electrode 16 and the 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 made of a resin material such as polyimide or acrylic. The connection wiring 20 is a transparent conductive layer made of a metal oxide material such as ITO. However, this is not limiting, and other metal materials can also be used for the connection wiring 20.

[0065] 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 made of a metal oxide material such as ITO. The anode electrode 22 is connected to the drain electrode 17 through an opening provided in the planarizing layer 19 and the insulating layer 21.

[0066] 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. 11. That is, in this embodiment, electrodes made of tin (Sn) are disposed as the connection electrodes 103a and 103b.

[0067] The connection electrodes 103a and 103b are respectively joined to the terminal electrodes 203a and 203b of the LED chip 202. As described above, in this embodiment, the terminal electrodes 203a and 203b are electrodes made of gold (Au).

[0068] The LED chip 202 corresponds to the LED 129 in the circuit diagram shown in Fig. 17. That is, the terminal electrode 203a of the LED chip 202 is connected to the anode electrode 22 which 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. 17.

[0069] The display device 10 of this embodiment having the above structure has the advantage of being highly resistant to impacts and the like, since the LED chips 202 are firmly mounted by fusion bonding using laser irradiation.

[0070] Second Embodiment In this embodiment, a method for manufacturing the display device 10 using a method different from that of the first embodiment will be described. Specifically, in this embodiment, an example will be shown in which, when separating the LED chips 202R from the element substrate 200, the LED chips 202R are divided into four groups for processing. While the LED chips 202R corresponding to red will be taken as an example, the same applies to the LED chips 202G corresponding to green and the LED chips 202B corresponding to blue. Note that, except for dividing the LED chips 202R into four groups, this embodiment is the same as the first embodiment, and therefore a duplicated description will be omitted.

[0071] 19 is a plan view illustrating the arrangement of the first group of LEDs 202Ra, the second group of LEDs 202Rb, the third group of LEDs 202Rc, and the fourth group of LEDs 202Rd in the second embodiment. As shown in FIG. 19, the first group of LED chips 202Ra, the second group of LED chips 202Rb, the third group of LED chips 202Rc, and the fourth group of LED chips 202Rd are arranged every other LED chip in the row and column directions. That is, for each of the LED chips 202R in the first to fourth groups, when focusing on a certain LED chip 202R, all of the adjacent eight LED chips 202R belong to other groups.

[0072] In this embodiment, the number of LED chips R to be processed in one lift-off process (the process of irradiating the laser light 40 shown in FIG. 4) is ¼ of the number of LED chips 202R included in the element substrate 200. Therefore, in this embodiment, the lift-off process is performed a total of four times. However, the four processes can be performed consecutively by shifting the position of the light-shielding mask 30, so that the throughput does not decrease significantly.

[0073] According to this embodiment, the amount of gas generated is half that of the first embodiment (one-fourth that of the comparative example), and there is an advantage that the distance between adjacent LED chips 202R is long, so they are less likely to affect each other.

[0074] <Third embodiment> In this embodiment, a method for manufacturing the display device 10 using a method different from that of the first embodiment will be described. Specifically, in this embodiment, an example will be shown in which, when separating the LED chips 202R from the element substrate 200, the LED chips 202R are divided into two groups and processed in a manner different from that of the first embodiment. While the LED chips 202R corresponding to red will be taken as an example, the same applies to the LED chips 202G corresponding to green and the LED chips 202B corresponding to blue. Note that, except for dividing the LED chips 202R into four groups, this embodiment is the same as the first embodiment, and therefore a duplicated description will be omitted.

[0075] 20 and 21 are plan views illustrating the arrangement of the first group of LEDs 202Ra and the second group of LEDs 202Rb in the third embodiment. In the example shown in Fig. 20, the first group of LED chips 202Ra and the second group of LED chips 202Rb are arranged consecutively in the row direction and alternately in the column direction. That is, in each of the first group of LED chips 202Ra and the second group of LED chips 202Rb, when focusing on a certain LED chip 202R, the two LED chips 202R adjacent to it in the column direction both belong to different groups.

[0076] 21, the first group of LED chips 202Ra and the second group of LED chips 202Rb are arranged consecutively in the column direction and alternately in the row direction. That is, in each of the first group of LED chips 202Ra and the second group of LED chips 202Rb, when focusing on a certain LED chip 202R, the two LED chips 202R adjacent to it in the row direction both belong to different groups.

[0077] In this embodiment, the number of LED chips R to be processed in one lift-off process is half the number of LED chips 202R included in the element substrate 200, as in the first embodiment. Therefore, according to this embodiment, the amount of gas generated is the same as in the first embodiment (half that of the comparative example).

[0078] <Fourth embodiment> The common point among the above-described first, second and third embodiments is that when focusing on an LED chip 202 in an arbitrary group, the LED chip 202 adjacent in the row direction and / or column direction belongs to another group. That is, among a plurality of LED chips arranged in M ​​rows x N columns (M and N are integers of 1 or more), each position of the LED chip in the first group is (M x ,N y ), each position of the second group of LED chips is expressed as (M x±1 ,N y ) or (M x ,N y±1) In particular, in the second embodiment, each position of the first group of LED chips is expressed as (M x ,N y ), each position of the second group of LED chips is expressed as (M x±1 ,N y ), and each position of the LED chip in the third group is represented by (M x ,N y±1 ), and each position of the fourth group of LED chips is represented by (M x±1 ,N y±1 )

[0079] As described above, as long as the conditions of this embodiment are met, the yield when separating the LED chips from the semiconductor substrate by laser irradiation can be improved regardless of how the LED chips 202 are divided into groups. For example, the LED chips 202 included in the element substrate 200 may be divided into four or more groups for processing.

[0080] Fifth Embodiment In this embodiment, a method for manufacturing the display device 10 using a method different from that of the first embodiment will be described. Specifically, in this embodiment, an example will be described in which the LED chip 202R is mounted directly onto the circuit board 100 from the carrier substrate 301. While the LED chip 202R corresponding to red will be taken as an example, the same applies to the LED chip 202G corresponding to green and the LED chip 202B corresponding to blue. In the description using the drawings, common reference numerals will be used to designate matters common to the first embodiment, and duplicated description will be omitted.

[0081] 22 to 27 are cross-sectional views showing a manufacturing method of the display device 10 in the fifth embodiment. A plurality of LED chips 202R are transferred onto the carrier substrate 301 shown in Fig. 22. The process of transferring the plurality of LED chips 202R onto the carrier substrate 301 may follow the process described in the first embodiment with reference to Figs. 1 to 7.

[0082] The transfer member 410 includes a support member 411 and an elastic member 412. The support member 411 is a member that supports the elastic member 412. The support member 411 can be made of a material that has higher rigidity than the elastic member 412, such as glass, quartz, sapphire, silicon, or stainless steel.

[0083] The elastic member 412 has a function of picking up or releasing an element such as an LED chip, and at that time, the elastic member 412 has a function of absorbing the repulsive force from the element. The elastic member 412 can be made of a material such as natural rubber or synthetic rubber.

[0084] As shown in FIG. 22, the elastic member 412 has protrusions 412a. The cross-sectional size of the protrusions 412a corresponds to the size of elements such as LED chips. That is, the transfer member 410 is configured to be able to pick up or release each element individually using the protrusions 412a. In this embodiment, the pitch of the protrusions 412a (the distance between two adjacent protrusions 412a) is greater than the pitch of each LED chip 202R (the distance between two adjacent LED chips 202). That is, as shown in FIG. 22, the protrusions 412a can selectively pick up LED chips 202R at a predetermined interval. In the example shown in FIG. 23, the pitch of the protrusions 412a is three times the pitch of each LED chip 202R.

[0085] 22, the transfer member 410 is disposed so that the tip of the protrusion 412a faces the LED chip 202a on the carrier substrate 301. When the transfer member 410 is brought close to the carrier substrate 301 in this state, the protrusion 412a comes into contact with the LED chip 202R.

[0086] Fig. 23 shows a state in which the protrusions 412a are in contact with the LED chip 202R. As shown in Fig. 23, every third protrusion 412a is in contact with the LED chip 202R. At this time, the transfer member 410 is pressed against the carrier substrate 301 with a predetermined pressure, so that the protrusions 412a are brought into sufficient contact with the LED chip 202R. Because the protrusions 412a are elastic, they contract to absorb the repulsive force from the LED chip 202R.

[0087] 24, when the transfer member 410 is moved away from the carrier substrate 301, the LED chip 202R in contact with the protrusion 412a is picked up. At this time, the adhesive force between the protrusion 412a and the LED chip 202R is set to be greater than the adhesive force between the LED chip 202R and the carrier substrate 301. The adhesive force between the protrusion 412a and the carrier substrate 301 can be adjusted by the type of adhesive used or the type of surface treatment of the protrusion 412a and the carrier substrate 301.

[0088] After the LED chip 202R is selectively picked up using the transfer member 410 as described above, the transfer member 410 is then placed on the circuit board 100, as shown in Fig. 25. The transfer member 410 is placed so that the tip of the protrusion 412a (strictly speaking, the terminal electrode 203R of the LED chip 202R) faces the connection electrode 103 on the circuit board 100.

[0089] In this state, when the transfer member 410 is brought close to the circuit board 100, the terminal electrode 203 and the connection electrode 103 come into contact with each other, as shown in FIG. 26. Although not shown, a conductive adhesive (e.g., an anisotropic conductive film) is provided on the connection electrode 103. Therefore, the terminal electrode 203 and the connection electrode 103 are bonded via the conductive adhesive. With the terminal electrode 203 and the connection electrode 103 bonded together, the conductive adhesive can be hardened by applying heat or irradiating it with light. However, this is not limiting, and instead of the connection electrode 103, a bump made of a conductive adhesive may be provided, and the bump and the terminal electrode 203R may be directly bonded. Furthermore, the terminal electrode 203R and the connection electrode 103 may be temporarily bonded together with an adhesive, and then the terminal electrode 203R and the connection electrode 103 may be melt-bonded together by irradiating them with laser light.

[0090] After each LED chip 202R is bonded to the connection electrode 103 on the circuit board 100 by the process shown in FIG. 26, the transfer member 410 is moved away from the circuit board 100 as shown in FIG. 27. When the transfer member 410 is moved away from the circuit board 100, the LED chip 202R that abuts against the protrusion 412a is released. The adhesive force between the protrusion 412a and the LED chip 202R is smaller than the adhesive force between the terminal electrode 203R of the LED chip 202R and the connection electrode 103. Therefore, the LED chip 202R can be easily released by simply moving the transfer member 410 away from the circuit board 100.

[0091] Through the processes 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. Through these processes, the LED chip 202R corresponding to red, the LED chip 202G corresponding to green and the LED chip 202B corresponding to blue can be mounted on the circuit board 100, as shown in FIG.

[0092] In this embodiment, an example has been shown in which the LED chips 202R are picked up and released using the adhesive force of the elastic member 412 (specifically, the protrusions 412a) of the transfer member 410, but the present invention is not limited to this example. For example, it is also possible to pick up and release the LED chips 202R using an adsorption force such as vacuum adsorption. Furthermore, in this embodiment, an example has been shown in which multiple LED chips 202R are transferred at once, but the present invention is not limited to this example and they can also be transferred individually.

[0093] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. A product in which a person skilled in the art appropriately adds or deletes components or modifies designs, or adds or omits steps or modifies conditions, based on each embodiment, is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0094] 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. [Explanation of symbols]

[0095] 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, 30, 35...light-shielding mask, 30a, 3 5a...opening, 40, 50...laser light, 100...circuit board, 101...substrate, 102...drive circuit, 103, 103a, 103b...connection electrodes, 110, 110R, 110G, 110B...pixels, 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...drive transistor, 128...storage capacitor, 130...data driver circuit, 140...gate driver circuit, 150...terminal portion, 151, 152...connection wiring, 160...flexible printed circuit board, 170...IC chip, 200...element substrate, 201...semiconductor substrate, 202, 202R, 202G, 202B...LED chip, 202Ra...first group of LED chips, 202Rb...second group of LED chips, 202Rc...third group of LED chips, 202Rd...fourth group of LED chips, 203a, 203b, 203R...terminal electrodes, 301, 401...carrier substrate, 410...transfer member, 411...support member, 412...elastic member, 412a...protrusion

Claims

1. A first substrate is provided having a plurality of LED chips arranged in M ​​rows and N columns (M and N are integers of 1 or greater); bonding the first substrate to a second substrate via the plurality of LED chips; performing a lift-off process in which, with the first substrate bonded to the second substrate, a first group of LED chips among the plurality of LED chips is selectively irradiated with laser light; and, with the first substrate bonded to the second substrate, a second group of LED chips among the plurality of LED chips is selectively irradiated with laser light; separating the first group of LED chips from the first substrate and the second group of LED chips after the lift-off process; When the position of each of the LED chips in the first group is represented by (Mx, Ny), the position of each of the LED chips in the second group is represented by (Mx±1, Ny) or (Mx, Ny±1), the first group of LED chips and the second group of LED chips are arranged in a staggered arrangement; A method for manufacturing a display device.

2. A first substrate is provided having a plurality of LED chips arranged in M ​​rows and N columns (M and N are integers of 1 or greater); bonding the first substrate to a second substrate via the plurality of LED chips; performing a lift-off process in which, with the first substrate bonded to the second substrate, a first group of LED chips among the plurality of LED chips is selectively irradiated with laser light; and, with the first substrate bonded to the second substrate, a second group of LED chips among the plurality of LED chips is selectively irradiated with laser light; separating the first group of LED chips from the first substrate and the second group of LED chips after the lift-off process; When the position of each of the LED chips in the first group is represented by (Mx, Ny), the position of each of the LED chips in the second group is represented by (Mx±1, Ny) or (Mx, Ny±1), the first substrate is an element substrate, the second substrate is a carrier substrate; A method for manufacturing a display device.

3. 3. The method for manufacturing a display device according to claim 1, wherein the number of LED chips in the first group is the same as the number of LED chips in the second group.

4. 3. The method for manufacturing a display device according to claim 1, wherein the selective irradiation of the laser light includes irradiating the first substrate with the laser light through a light-shielding mask having a plurality of openings.

5. The method for manufacturing a display device according to claim 4 , wherein the pitch of the plurality of openings is at least twice the pitch of the plurality of LED chips.

6. The method for manufacturing a display device according to claim 4 , wherein the selective irradiation with laser light includes scanning the laser light onto the light-shielding mask.

7. The method for manufacturing a display device according to claim 1 , wherein the laser light is ultraviolet light.

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