Display device and method of forming the same

Abstract

The present disclosure provides a display device. The display device includes a substrate and a light-emitting unit disposed on the substrate. The light-emitting unit includes a first conductor layer and a second conductor layer overlapping each other, a first semiconductor layer disposed between the first conductor layer and the second conductor layer, a second semiconductor layer disposed between the first semiconductor layer and the first conductor layer, a quantum well structure disposed between the first semiconductor layer and the second semiconductor layer, a through hole penetrating the first semiconductor layer and the quantum well structure, and a conductive material disposed in the through hole. The second conductor layer is electrically connected to the second semiconductor layer via the conductive material.

Description

[0001] This application is a divisional application of the invention patent application with application number "201711444797.4" and invention name "Display device and method for forming the same" filed by the applicant on December 27, 2017. Technical Field

[0002] The present disclosure relates to a display device, and in particular to a display device including a light emitting unit. Background Art

[0003] With the development of digital technology, display devices have been widely used in all aspects of daily life. For example, they have been widely used in modern information devices such as televisions, laptops, computers, mobile phones (e.g., smart phones), and these display devices are constantly developing in the direction of being light, thin, short and fashionable.

[0004] Among various types of display devices, light emitting diode (LED) display devices are becoming increasingly popular due to their advantages such as high performance and long service life.

[0005] However, existing LED display devices are not satisfactory in all aspects. Summary of the invention

[0006] Some embodiments of the present disclosure provide a display device. The display device includes a substrate and a light-emitting unit disposed on the substrate. The light-emitting unit includes a first conductor layer and a second conductor layer overlapping each other, a first semiconductor layer disposed between the first conductor layer and the second conductor layer, a second semiconductor layer disposed between the first semiconductor layer and the first conductor layer, a quantum well structure disposed between the first semiconductor layer and the second semiconductor layer, a through hole penetrating the first semiconductor layer and the quantum well structure, and a conductive material disposed in the through hole. The second conductor layer is electrically connected to the second semiconductor layer via the conductive material. In these embodiments, the light-emitting unit is provided with a conductive layer on both the upper and lower sides, so that both the upper and lower sides of the light-emitting unit can be used to connect to the substrate of the display device, which can increase the flexibility of the process of forming the display device.

[0007] Some embodiments of the present disclosure provide a method for forming a display device. The method for forming a display device includes providing a substrate. A plurality of bonding pads are disposed on the substrate. The method for forming a display device also includes forming an adhesive layer on the substrate and covering the bonding pads, forming a patterned adhesive layer using a photolithography process to correspond to the bonding pads, and bonding a light-emitting unit to at least one bonding pad via the patterned adhesive layer. In these embodiments, since the patterned adhesive layer of the display device is formed via a photolithography process, the pattern formed can have a smaller size and can be used to bond a small-sized light-emitting unit to the substrate of the display device.

[0008] Some embodiments of the present disclosure provide a display device. The display device includes a substrate, a first light-emitting unit and a second light-emitting unit disposed on the substrate. The first light-emitting unit is adjacent to the second light-emitting unit. In a first direction, the first light-emitting unit has a length P1, and the first light-emitting unit and the second light-emitting unit have a spacing Z1. The display device also includes a first adhesive layer disposed between the substrate and the first light-emitting unit, and a second adhesive layer disposed between the substrate and the second light-emitting unit. In the first direction, the first adhesive layer and the second adhesive layer have a spacing Z3, where Z1, Z3, and P1 satisfy the following formula: 0 < Z3 < (Z1 + P1), and Z1, Z3, and P1 are all greater than 0 micrometers (μm). In these embodiments, by setting and adjusting the length P1 of the first light-emitting unit, the spacing Z1 between adjacent light-emitting units, and the spacing Z3 between adjacent adhesive layers to satisfy the following formula 0 < Z3 < (Z1 + P1), the problem of poor electrical connection between the light-emitting unit and the display device substrate caused by insufficient adhesion due to too small an adhesion area between the adhesive layer and the light-emitting unit can be reduced.

[0009] Embodiments will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] When read in conjunction with the accompanying drawings, the present disclosure can be more fully understood from the following detailed description. It should be noted that, in accordance with standard industry practice, the various features are not drawn to scale. In fact, for clarity, the dimensions of the various features may be arbitrarily enlarged or reduced.

[0011] Figure 1A 、 1B 1C, 1D, 1F are a series of cross-sectional views illustrating a method for forming a light-emitting unit according to some embodiments of the present disclosure.

[0012] Figure 1E is a top view of a light-emitting unit illustrated according to some embodiments of the present disclosure.

[0013] Figure 1G is a cross-sectional view of a display device 10 illustrated according to some embodiments of the present disclosure.

[0014] Figure 1H is a cross-sectional view of a display device 10 illustrated according to some embodiments of the present disclosure.

[0015] Figure 2A 及 Figure 2B are a top view and a cross-sectional view of a display device 20 illustrated according to some embodiments of the present disclosure.

[0016] Figure 3A 及 Figure 3B are a top view and a cross-sectional view of a display device 30 illustrated according to some embodiments of the present disclosure.

[0017] Figure 4A and Figure 4B 1 is a top view and a cross-sectional view of a display device 40 according to some embodiments of the present disclosure.

[0018] Figure 5A and Figure 5B 1 is a top view and a cross-sectional view of a display device 50 according to some embodiments of the present disclosure.

[0019] Fig. 6A , 6B , 6C, 6D, and 6E are a series of cross-sectional views illustrating methods of forming a display device 60 according to some embodiments of the present disclosure.

[0020] Fig. 6F is a cross-sectional view of a display device 60 ′ according to some embodiments of the present disclosure.

[0021] Figure 6G , 6H 1 is a top view and a cross-sectional view of a display device 60 ” according to some embodiments of the present disclosure.

[0022] Fig.6I FIG. 6 is a top view of a display device 60 ” according to some embodiments of the present disclosure.

[0023] Figure 6J FIG. 1 is a top view of a display device 60 a according to some embodiments of the present disclosure.

[0024] Figure 6K FIG. 1 is a top view of a display device 60 a according to some embodiments of the present disclosure.

[0025] Figure 6L FIG. 1 is a top view of a display device 60 a according to some embodiments of the present disclosure.

[0026] Figure 6M FIG. 1 is a top view of a display device 60 a according to some embodiments of the present disclosure.

[0027] Figure 6N FIG. 1 is a top view of a display device 60 a according to some embodiments of the present disclosure.

[0028] Fig. 7A , 7B 7C, and 7D are a series of cross-sectional views illustrating methods of forming a display device 70 according to some embodiments of the present disclosure.

[0029] Fig. 8A , 8B , 8C, and 8D are a series of cross-sectional views illustrating methods of forming a display device 80 according to some embodiments of the present disclosure.

[0030] Fig. 9A , 9B , 9C, and 9D are a series of cross-sectional views illustrating a method of forming a display device 90 according to some embodiments of the present disclosure.

[0031] Explanation of symbols

[0032] 10, 20, 30, 40, 50, 60, 60', 60", 60a, 70, 80, 90~Display equipment

[0033] 100~Substrate

[0034] 102~First semiconductor layer

[0035] 102a~first side of the first semiconductor layer

[0036] 102b~Second side of the first semiconductor layer

[0037] 103~Light-emitting unit

[0038] 104~Quantum Well Structure

[0039] 106~Second semiconductor layer

[0040] 108a~first conductor layer

[0041] 110a~third conductor layer

[0042] 108b~Second conductor layer

[0043] 110b~Fourth conductor layer

[0044] 112a, 112b~protective layer

[0045] 114~Temporary substrate

[0046] 115~Second insulation layer

[0047] 116~Through hole

[0048] 116a~Conductive materials

[0049] 116b~first insulating layer

[0050] 118~Substrate

[0051] 120~Joint pad

[0052] 600~First substrate

[0053] 601~Grabbing head

[0054] 602~Adhesive layer

[0055] 602a, 602b, 602c, 602d, 602e, 602f, 602g, 602h, 602i, 602j - adhesive layer

[0056] 603~Conductive particles

[0057] 604~Light-emitting unit

[0058] 606~Light-emitting body of light-emitting unit

[0059] 608~First conductor layer or second conductor layer

[0060] 610~third conductor layer or fourth conductor layer

[0061] 612~Second substrate

[0062] 700~Substrate

[0063] 704~Adhesive layer

[0064] 704A~First Pattern

[0065] 704a~Sub-pattern of the first pattern

[0066] 704B~Second pattern

[0067] 704b~Sub-pattern of the second pattern

[0068] 706~Light-emitting unit

[0069] 708~Light-emitting body of light-emitting unit

[0070] 710~First conductor layer or second conductor layer

[0071] 712~third conductor layer or fourth conductor layer

[0072] C1, C2, C3, C4~bonding pads

[0073] S1, S2, S3, S4~spacing

[0074] O1, O2, O3, O4~Open

[0075] d1~diameter of conductive particles

[0076] d2~Distance

[0077] R1, R2 ~ Current path

[0078] W1, W2~Width

[0079] AA, BB~Hatch line

[0080] Y~First direction

[0081] X~Second direction

[0082] F1, F2~Center line

[0083] M~Dislocation

[0084] L1, L2, L3~row

[0085] P1, P2~length of the light emitting unit

[0086] Z1, Z2 ~ the distance between adjacent light-emitting units

[0087] Z3, Z4~the distance between adjacent bonding layers

[0088] V~Pixel DETAILED DESCRIPTION

[0089] The following disclosure provides many different embodiments or examples to implement the different features of the present invention. The following disclosure describes specific examples of various components and their arrangement to simplify the description. Of course, these specific examples are not intended to be limiting. For example, if the present disclosure describes a first feature formed on or above a second feature, it means that it may include an embodiment in which the first feature and the second feature are in direct contact, and it may also include an embodiment in which an additional feature is formed between the first feature and the second feature, so that the first feature and the second feature may not be in direct contact.

[0090] In addition, the different examples disclosed below may repeatedly use the same reference symbols and / or marks. These repetitions are for the purpose of simplicity and clarity, and are not intended to limit the specific relationship between the different embodiments and / or structures discussed.

[0091] Some embodiments of the present disclosure will be described below. Additional operations may be provided before, between, and / or after the steps described in these embodiments. Some of the steps described may be replaced or omitted in different embodiments. In addition, although some embodiments of the present disclosure are described below with several steps in a specific order, these steps may also be performed in other reasonable orders.

[0092] [First embodiment]

[0093] The light-emitting unit of this embodiment has a conductor layer on both the upper and lower sides, so both the upper and lower sides can be used to connect to the substrate of the display device, which can increase the flexibility of the process of forming the display device. For example, the conductor layer can be the electrode of the light-emitting unit, and the substrate of the display device can be a thin film transistor substrate.

[0094] For example, when the light-emitting unit is transferred to the substrate by flowing or vibrating gas or liquid, the contact surface between the light-emitting unit and the substrate is randomly generated. If a light-emitting unit with a conductor layer formed on only one side is used, there may be no conductor layer on the side where the light-emitting unit contacts the substrate to electrically connect the light-emitting unit and the substrate, so that the light-emitting unit cannot be driven and cannot emit light.

[0095] The following will cooperate Figures 1A-1F The method for forming the light emitting unit of this embodiment is exemplarily described.

[0096] like Figure 1A As shown, a substrate 100 is provided. In one embodiment, the substrate 100 may be an epitaxial substrate, such as a sapphire substrate. In some other embodiments, the substrate 100 may also include a silicon carbide (SiC) substrate, a silicon (Si) substrate, a magnesium aluminate (MgAl2O4) substrate, a magnesium oxide (MgO) substrate, a lithium metaaluminate (LiAlO2) substrate, a lithium gallium oxide (LiGaO2) substrate, a gallium nitride (GaN) substrate, a gallium arsenide (GaAs) substrate, a gallium phosphide (GaP) substrate, a glass substrate, other appropriate substrates or combinations thereof, but the present disclosure is not limited thereto.

[0097] In some embodiments, the substrate 100 may include a buffer layer (not shown in the figure) to reduce defects caused by lattice mismatch between the substrate 100 and the semiconductor layer on the substrate 100. For example, the buffer layer may include aluminum nitride (AlN), aluminum gallium nitride (AlGaN), other appropriate materials or combinations thereof, but the present disclosure is not limited thereto.

[0098] Please continue to refer to Figure 1A , a light emitting unit 103 may be formed on the substrate 100. For example, the light emitting unit 103 may be a light emitting diode (eg, a blue light emitting diode, a red light emitting diode or a green light emitting diode). Figure 1A As shown, the light emitting unit 103 includes a first semiconductor layer 102 and a second semiconductor layer 106 which are vertically stacked, and a quantum well structure 104 disposed between the first semiconductor layer 102 and the second semiconductor layer 106 .

[0099] For example, the first semiconductor layer 102, the quantum well structure 104 and the second semiconductor layer 106 may be sequentially formed on the substrate 100 (e.g., a sapphire substrate) through an epitaxial process, but the present disclosure is not limited thereto. For example, the epitaxial process may include a molecular beam epitaxy (MBE), a metalorganic chemical vapor deposition (MOCVD), a hydride vapor phase epitaxy (HVPE), other appropriate epitaxial processes or a combination thereof. In some embodiments, the first semiconductor layer 102, the second semiconductor layer 106 and the quantum well structure 104 may be formed by the same process, and the difference between the three is that the doping substances (Dopants) are different, and the doping concentrations of the three may also be different.

[0100] In some embodiments, the first semiconductor layer 102, the quantum well structure 104, and the second semiconductor layer 106 may be patterned using an appropriate patterning process. For example, the patterning process may include a photolithography process, an etching process, other appropriate processes, or a combination thereof. In some embodiments, the photolithography process may include resist coating, soft baking, exposure, post-exposure baking, developing, other appropriate processes, or a combination thereof, and the etching process may include wet etching, dry etching, other appropriate processes, or a combination thereof.

[0101] For example, the first semiconductor layer 102, the second semiconductor layer 106, and the quantum well structure 104 may each include, for example, gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), gallium arsenide (GaAs), indium gallium phosphide (GaInP), aluminum gallium arsenide (AlGaAs), indium phosphide (InP), aluminum indium arsenide (InAlAs), indium gallium arsenide (InGaAs), aluminum indium gallium phosphide (AlGaInP), other appropriate III-V semiconductor materials, or combinations thereof, but the present disclosure is not limited thereto. In some embodiments, the first semiconductor layer 102 and the second semiconductor layer 106 may be doped with dopants of opposite conductivity types. For example, the first semiconductor layer 102 and the second semiconductor layer 106 may be doped by ion implantation or in-situ doping. For example, in the present embodiment, the first semiconductor layer 102 is formed of n-type GaN doped with a dopant such as silicon or oxygen, the second semiconductor layer 106 is formed of p-type GaN doped with a dopant such as magnesium, and the quantum well structure 104 may include a stacked structure formed by alternating layers of InGaN and GaN, and the recombination probability of electrons and holes in the stacked structure may be increased to improve the luminous efficiency.

[0102] Please continue to refer to Figure 1A The light emitting unit 103 further includes a first conductor layer 108a and a third conductor layer 110a disposed on one side of the light emitting unit 103. Specifically, the first conductor layer 108a and the third conductor layer 110a may be disposed on the first side 102a of the first semiconductor layer 102. Figure 1A As shown, the first conductive layer 108a can be electrically connected to the second semiconductor layer 106, and the third conductive layer 110a can be electrically connected to the first semiconductor layer 102. In some embodiments, the first conductive layer 108a directly contacts the second semiconductor layer 106, and the third conductive layer 110a directly contacts the first semiconductor layer 102.

[0103] In some embodiments, the material of the first conductor layer 108a and the third conductor layer 110a may include metal materials, other appropriate conductive materials, or combinations thereof, but the disclosure is not limited thereto. The metal material may include, for example, copper, tungsten, silver, tin, nickel, chromium, titanium, lead, gold, bismuth, antimony, zinc, zirconium, magnesium, indium, tellurium, gallium, other appropriate metal materials, alloys thereof, or combinations thereof. In some other embodiments, the material of the first conductor layer 108a and the third conductor layer 110a may be a transparent conductive material, and the transparent conductive material may include, for example, indium tin oxide (ITO), tin oxide (SnO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin zinc oxide (ITZO), antimony tin oxide (ATO), antimony zinc oxide (AZO), other appropriate transparent conductive materials, or combinations thereof, but the disclosure is not limited thereto.

[0104] In some embodiments, a metal blanket layer or a transparent conductive material blanket layer (not shown in the figure) may be formed on the first semiconductor layer 102 and the second semiconductor layer 106 by physical vapor deposition (e.g., evaporation or sputtering), electroplating, atomic layer deposition, other appropriate methods, or a combination thereof, and then the metal blanket layer or the transparent conductive material blanket layer may be patterned by a patterning process such as a photolithography process and an etching process to form the first conductor layer 108a and the third conductor layer 110a.

[0105] Please continue to refer to Figure 1A In some embodiments, a protective layer 112a may be formed on the first semiconductor layer 102 according to design requirements. The protective layer 112a may at least partially fill the gap between the first conductor layer 108a and the third conductor layer 110a, thereby improving the reliability of the light-emitting unit 103. For example, the protective layer 112a may include an organic material (e.g., including: acrylic-based material), an inorganic material (e.g., including: silicon oxide, silicon nitride), other appropriate materials, or a combination thereof. In some embodiments, the protective layer 112a may include a silicon-based material, but the present disclosure is not limited thereto. In some embodiments, the protective layer 112a may be formed by spin coating, chemical vapor deposition (e.g., plasma-enhanced chemical vapor deposition (PECVD)), other appropriate methods, or a combination thereof, but the present disclosure is not limited thereto.

[0106] Then, if Figure 1B As shown in FIG. 1 , the substrate 100 and the light emitting unit 103 are turned upside down, and the light emitting unit 103 is bonded to the temporary substrate 114. Figure 1BAs shown, the substrate 100 and the temporary substrate 114 are respectively disposed on opposite sides of the light emitting unit 103. For example, the temporary substrate 114 can be formed of silicon, glass, polyimide, polyethylene terephthalate, other appropriate materials or combinations thereof, but the present disclosure is not limited thereto. In some embodiments, the light emitting unit 103 and the temporary substrate 114 can be bonded via an adhesive layer (not shown in the figure). For example, the adhesive layer can include a heat curing material and / or a light curing material, but the present disclosure is not limited thereto.

[0107] Then, if Figure 1C As shown, the substrate 100 is removed. In the present embodiment, the substrate 100 is removed by a laser lift-off process. For example, the laser light source of the laser lift-off process may include an excimer laser, a pico laser, a femto laser, other appropriate laser light sources, or a combination thereof, but the present disclosure is not limited thereto. In some other embodiments, mechanical peeling, a grinding process, an etching process, other appropriate processes, or a combination thereof may also be used to remove the substrate 100, but the present disclosure is not limited thereto.

[0108] Then, if Figure 1D As shown, a second insulating layer 115 is formed on the second side 102b of the first semiconductor layer 102. For example, the second insulating layer 115 may include an organic material (for example, including: acrylic-based material), an inorganic material (for example, including: silicon oxide, silicon nitride), other appropriate materials or a combination thereof, but the present disclosure is not limited thereto. In some embodiments, the second insulating layer 115 may be formed using a spin coating method, a chemical vapor deposition method (for example, a plasma-assisted chemical vapor deposition method), screen printing, other appropriate methods or a combination thereof, and the second insulating layer 115 may be patterned using a photolithography process and an etching process. For example, the photolithography process and the etching process described herein may be similar to or the same as the photolithography process and the etching process described above.

[0109] Next, please continue to refer to Figure 1D , forming a through hole (via) 116, and forming a first insulating layer 116b and a conductive material 116a in the through hole 116, and the first insulating layer 116b is between the through hole 116 and the conductive material 116a. In some embodiments, Figure 1DAs shown, the through hole 116 penetrates the second insulating layer 115, the first semiconductor layer 102 and the quantum well structure 104, and the conductive material 116a is electrically connected to the second semiconductor layer 106. For example, the conductive material 116a can directly contact the second semiconductor layer 106 or be electrically connected to the second semiconductor layer 106 through other conductive components.

[0110] like Figure 1D As shown, in some embodiments, the first insulating layer 116b may be disposed around the sidewall of the conductive material 116a. In some embodiments, the first insulating layer 116b may be disposed between the hole wall of the through hole 116 and the conductive material 116a. Figure 1D As shown, the first insulating layer 116b is disposed on the sidewall of the conductive material 116a but still exposes the top surface and / or bottom surface of the conductive material 116a. For example, the first insulating layer 116b can separate the conductive material 116a from the first semiconductor layer 102, and the first insulating layer 116b can separate the conductive material 116a from the quantum well structure 104. In other words, the first insulating layer 116b can be disposed between the conductive material 116a and the first semiconductor layer 102, and the first insulating layer 116b is disposed between the conductive material 116a and the quantum well structure 104. For example, a through hole 116 penetrating the second insulating layer 115, the first semiconductor layer 102 and the quantum well structure 104 may be formed by mechanical drilling, laser drilling, dry etching, wet etching, other appropriate methods or a combination thereof, and then an insulating layer may be formed on the wall and bottom of the through hole 116 by an atomic layer deposition process, a chemical vapor deposition process, other appropriate processes or a combination thereof, and then the insulating layer on the bottom of the through hole 116 is removed by an etching process, leaving the insulating layer on the wall of the through hole 116 as the first insulating layer 116b. For example, the first insulating layer 116b may include silicon oxide (SiO2), silicon nitride (SiNx), other appropriate insulating materials or a combination thereof. The chemical vapor deposition process may include, for example, a high-density plasma chemical vapor deposition process, a low-pressure chemical vapor deposition process, or a plasma-assisted chemical vapor deposition process. The etching process may include, for example, an anisotropic etching process, but the present disclosure is not limited thereto.

[0111] Next, copper, tungsten, silver, tin, nickel, chromium, titanium, lead, bismuth, antimony, zinc, zirconium, magnesium, indium, tellurium, gallium, alloys thereof, other appropriate conductive materials or combinations thereof may be deposited in the through hole 116 by physical vapor deposition (e.g., evaporation or sputtering), electroplating, atomic layer deposition, other appropriate methods or combinations thereof to form the conductive material 116a. In some embodiments, after the step of depositing the conductive material, a process such as chemical mechanical polishing or back etching may be performed to remove excess conductive material outside the through hole 116. In some embodiments, the conductive material 116a may include an acid-resistant metal (e.g., copper, silver, gold or platinum).

[0112] Then, if Figure 1E and Figure 1F As shown, a second conductor layer 108b and a fourth conductor layer 110b are formed on the second side 102b of the first semiconductor layer 102 to form a light emitting unit 103 having conductor layers on both sides. Figure 1E FIG. 1 is a top view of a process portion of a method for forming a light-emitting unit according to the present embodiment. Figure 1F For along Figure 1E It should be noted that for the sake of simplicity, Figure 1E The protective layer 112b is omitted.

[0113] Generally speaking, the second conductor layer 108b and the fourth conductor layer 110b on the second side 102b of the first semiconductor layer 102 correspond to the first conductor layer 108a and the third conductor layer 110a on the first side 102a of the first semiconductor layer 102 in terms of function and / or position and / or size. In some embodiments, the second conductor layer 108b may be electrically connected to the second semiconductor layer 106, and the fourth conductor layer 110b may be electrically connected to the first semiconductor layer 102. Further, in some embodiments, the second conductor layer 108b is electrically connected to the second semiconductor layer 106 via the conductive material 116a in the through hole 116, and the fourth conductor layer 110b directly contacts the first semiconductor layer 102.

[0114] In some embodiments, in the top view, the areas of the second conductor layer 108b and the fourth conductor layer 110b on the second side 102b of the first semiconductor layer 102 are respectively substantially equal to the areas of the first conductor layer 108a and the third conductor layer 110a on the first side 102a of the first semiconductor layer 102. In some embodiments, the second conductor layer 108b and the fourth conductor layer 110b on the second side 102b of the first semiconductor layer 102 and the first conductor layer 108a and the third conductor layer 110a on the first side 102a of the first semiconductor layer 102 are mirror-symmetrical.

[0115] It should be understood that, although the light-emitting unit 103 formed in the present embodiment includes three through holes 116, the present disclosure is not limited thereto. In some other embodiments, other numbers (e.g., 1 to 20) of through holes 116 may be formed according to design requirements, and the first insulating layer 116b and the conductive material 116a may be formed in the through holes 116. For example, in some embodiments, the light-emitting unit 103 may include one or two through holes 116.

[0116] Figure 1G Some embodiments of the present invention illustrate a partial cross-sectional view of a display device 10. Figure 1G As shown, the temporary substrate 114 in the display device 10 is removed, and the light-emitting unit 103 is disposed on the substrate 118. The display device 10 includes the light-emitting unit 103 including the through hole 116 of the aforementioned embodiment, and the light-emitting unit 103 is electrically connected to the substrate 118. For example, the substrate 118 may include one or more active components (not shown in the figure), such as transistors. For example, the substrate 118 may be a thin-film transistor (TFT) substrate, but the present disclosure is not limited thereto. In some embodiments, a driving circuit (not shown in the figure) may be disposed on the substrate 118, and the light-emitting unit 103 may be disposed on the driving circuit and electrically connected to the driving circuit.

[0117] The one or more active components may be electrically connected to the light emitting unit 103. In some embodiments, the one or more active components may control or adjust the driving signal (e.g., current signal) transmitted to the light emitting unit 103 to adjust the brightness of the light emitting unit 103. In some embodiments, the plurality of light emitting units 103 may be electrically connected to different active components. In other words, the driving signals transmitted to the plurality of light emitting units 103 may be separately controlled by the corresponding active components, so as to achieve the purpose of local dimming control.

[0118] like Figure 1G As shown, at least one bonding pad 120 may be disposed on the substrate 118 . In some embodiments, the first conductor layer 108 a and the third conductor layer 110 a of the light emitting unit 103 or the second conductor layer 108 b and the fourth conductor layer 110 b of the light emitting unit 103 are electrically connected to the substrate 118 via the bonding pad 120 .

[0119] In some embodiments, a bonding process such as eutectic bonding may be performed to bond the first conductor layer 108 a and the third conductor layer 110 a of the light emitting unit 103 or the second conductor layer 108 b and the fourth conductor layer 110 b of the light emitting unit 103 to the bonding pad 120 .

[0120] In some embodiments, the first conductor layer 108a and the third conductor layer 110a of the light emitting unit 103 or the second conductor layer 108b and the fourth conductor layer 110b of the light emitting unit 103 may be bonded to the bonding pad 120 via an adhesive layer (not shown in the figure) such as an anisotropic conductive film (ACF). For example, the anisotropic conductive film may include a plurality of conductive particles therein. In some embodiments, the conductive particles include a core portion formed of a polymer and a metal or metal alloy shell coated on the core portion.

[0121] like Figure 1G As shown, when the light emitting unit 103 is electrically connected to the bonding pad 120 by the first conductive layer 108a of the first side 102a of the first semiconductor layer 102 and the third conductive layer 110a (eg Figure 1G For the light emitting unit 103 on the right side, the current can flow through the first conductor layer 108a, the second semiconductor layer 106, the quantum well structure 104, the first semiconductor layer 102 and the third conductor layer 110a via the path R1, so that the light emitting unit 103 can achieve the function of emitting light.

[0122] Please continue to refer to Figure 1G When the light emitting unit 103 is electrically connected to the bonding pad 120 by the second conductor layer 108b and the fourth conductor layer 110b on the second side 102b of the first semiconductor layer 102 (eg Figure 1G The light emitting unit 103 on the left side can have a current flowing through the second conductor layer 108b, the conductive material 116a in the through hole 116, the second semiconductor layer 106, the quantum well structure 104, the first semiconductor layer 102 and the fourth conductor layer 110b via the path R2, so that the light emitting unit 103 can emit light.

[0123] In some embodiments, since the second insulating layer 115 is disposed between the first semiconductor layer 102 and the second conductor layer 108b of the light emitting unit 103, it is ensured that the current can flow through the second semiconductor layer 106 and the quantum well structure 104 via the conductive material 116a in the through hole 116, and will not flow directly from the second conductor layer 108b to the fourth conductor layer 110b via the first semiconductor layer 102. In some embodiments, the first insulating layer 116b can separate the conductive material 116a from the first semiconductor layer 102 and separate the conductive material 116a from the quantum well structure 104, thereby ensuring that the current can flow through the second semiconductor layer 106.

[0124] In some embodiments, the first conductor layer 108a and the third conductor layer 110a (or the second conductor layer 108b and the fourth conductor layer 110b) that are not bonded to the substrate 118 are formed of a transparent conductive material, so that the influence on the light emission of the light-emitting unit 103 can be reduced in the display device 10. For example, the transparent conductive material may include: indium tin oxide (ITO), tin oxide (SnO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin zinc oxide (ITZO), antimony tin oxide (ATO), antimony zinc oxide (AZO) and other transparent conductive materials, but the present disclosure is not limited thereto. For example, Figure 1G The first conductor layer 108a and the third conductor layer 110a of the first side 102a of the first semiconductor layer 102 of the light emitting unit 103 on the left side of the middle Figure 1G The second conductor layer 108b and the fourth conductor layer 110b of the second side 102b of the first semiconductor layer 102 of the light emitting unit 103 on the middle right are formed of transparent conductive materials, so no additional steps are required to remove them, thereby reducing the process steps and shortening the working time of the display device 10.

[0125] In some other embodiments, the first conductor layer 108a and the third conductor layer 110a (or the second conductor layer 108b and the fourth conductor layer 110b) not bonded to the substrate 118 are formed of an opaque conductive material (for example, including metal materials such as copper, tungsten, silver, tin, nickel, chromium, titanium, lead, gold, bismuth, antimony, zinc, zirconium, magnesium, indium, tellurium or gallium). If the first conductor layer 108a and the third conductor layer 110a (or the second conductor layer 108b and the fourth conductor layer 110b) not bonded to the substrate 118 are left in the display device 10, it may cause the light-emitting unit 103 to be unable to emit light normally. Therefore, in these embodiments, a process such as etching and / or grinding may be performed to remove the first conductor layer 108a and the third conductor layer 110a (or the second conductor layer 108b and the fourth conductor layer 110b) not bonded to the substrate 118. In other words, the first conductive layer 108a and the third conductive layer 110a (or the second conductive layer 108b and the fourth conductive layer 110b) that are not bonded to the substrate 118 will not remain in the final display device 10. For example ... Figure 1G The second conductor layer 108b and the fourth conductor layer 110b on the second side 102b of the first semiconductor layer 102 of the light emitting unit 103 on the right side of the middle Figure 1G The first conductor layer 108a and the third conductor layer 110a of the first side 102a of the first semiconductor layer 102 of the light emitting unit 103 on the left side of the middle are obtained. Figure 1H A display device 10 is shown.

[0126] In some embodiments, in order to reduce the possibility that the conductive material 116a in the through hole 116 is damaged by the etching process and further corrodes other components of the light-emitting unit 103, an acid-resistant metal (such as copper, silver, gold or platinum) can be used to form the conductive material 116a in the through hole 116. In addition, in some embodiments, the etching process also removes the protective layer (such as: Figure 1G The protective layer 112b of the light emitting unit 103 on the right side and Figure 1G The protective layer 112a of the light emitting unit 103 on the left side is also removed).

[0127] In summary, before being bonded to a substrate (e.g., a thin film transistor substrate), conductor layers (e.g., electrodes) are provided on opposite sides of the light-emitting unit of some embodiments of the present disclosure. Therefore, both opposite sides of the light-emitting unit can be used to connect to the substrate. In addition, in some embodiments, the light-emitting unit includes the aforementioned through-hole and the conductive material formed in the through-hole, and it can be ensured that when the light-emitting unit is bonded to the substrate on either side of the opposite sides, it can be electrically connected to the substrate to achieve the function of normal light emission.

[0128] Figure 2A , 2B , 3A, 3B, 4A, 4B, 5A, 5B are some variations of the display device 10 of the present embodiment. It should be noted that, unless otherwise specified, the same or similar components of these variations as those of the aforementioned embodiment will be represented by the same component symbols, and their formation methods may also be the same or similar to the formation methods of the aforementioned embodiment.

[0129] Figure 2A and Figure 2B FIG. 2 is a diagram illustrating a display device 20 of the present disclosure according to some embodiments. Specifically, Figure 2A is a partial top view of the display device 20, and Figure 2B Is for along Figure 2A It should be noted that for the sake of simplicity, not all components of the display device 20 are shown in FIG. Figure 2A and Figure 2B middle.

[0130] One difference between the display device 20 and the display device 10 is that the light emitting unit 103 of the display device 20 is designed to be circular or symmetrically polygonal (for example, in the top view). Figure 2A In the embodiment, the display device 20 is circular), which can overcome the light loss caused by left-right asymmetry.

[0131] Figure 3A and Figure 3BFIG. 3 is a diagram illustrating a display device 30 of the present disclosure according to some embodiments. Specifically, Figure 3A is a partial top view of the display device 30, and Figure 3B For along Figure 3A It should be noted that for the sake of simplicity, not all components of the display device 30 are shown in FIG. Figure 3A and Figure 3B middle.

[0132] One difference between the display device 30 and the display device 20 of the previous embodiment is that the light emitting unit 103 of the display device 30 includes a plurality of separate conductor layers. Figure 3A As shown, in some embodiments, the side of the light emitting unit 103 not bonded to the substrate 118 includes four separated third conductor layers 110a, and the side bonded to the substrate 118 also includes four separated fourth conductor layers 110b. Since the above conductor layers are separated from each other, the lateral light emitted from the quantum well structure 104 of the light emitting unit 103 can be reduced from being blocked, thereby improving the light emitting efficiency. It should be understood that although the example of one side of the light emitting unit 103 including four separated third conductor layers 110a or fourth conductor layers 110b is used for explanation, the present disclosure is not limited thereto, and one side of the light emitting unit 103 can also include other numbers of third conductor layers 110a or fourth conductor layers 110b according to design requirements.

[0133] Figure 4A and Figure 4B FIG. 4 is a diagram illustrating a display device 40 of the present disclosure according to some embodiments. Specifically, Figure 4A is a partial top view of the display device 40, and Figure 4B For along Figure 4A It should be noted that for the sake of simplicity, not all components of the display device 40 are shown in FIG. Figure 4A and Figure 4B middle.

[0134] like Figure 4A and Figure 4B As shown, one of the differences between the display device 40 and the display device of the aforementioned embodiment is that the quantum well structure 104 of the light emitting unit 103 of the display device 40 is disposed at the periphery of the light emitting unit 103, so that the lateral light emitted from the quantum well structure 104 of the light emitting unit 103 can be more effectively utilized to improve the light emitting efficiency. Figure 4B As shown in FIG. 1 , in this embodiment, the through hole 116 and the conductive material 116a may also partially penetrate into the second semiconductor layer 106 but do not contact the first conductive layer 110a. Figure 1DAs shown, the through hole 116 and the conductive material 116 a do not penetrate into the second semiconductor layer 106 , but the present disclosure is not limited thereto.

[0135] Figure 5A and Figure 5B FIG. 5 is a diagram illustrating a display device 50 of the present disclosure according to some embodiments. Specifically, Figure 5A is a partial top view of the display device 50, and Figure 5B For along Figure 5A It should be noted that for the sake of simplicity, not all components of the display device 50 are shown in FIG. Figure 5A and Figure 5B middle.

[0136] like Figure 5A and Figure 5B As shown, one of the differences between the display device 50 and the display device 40 of the aforementioned embodiment is that the light emitting unit 103 of the display device 50 includes a plurality of separated quantum well structures 104, which can improve the light extraction efficiency. It should be understood that although the light emitting unit 103 is described as including four separated quantum well structures 104, the present disclosure is not limited thereto, and the light emitting unit 103 may include other numbers of quantum well structures 104 according to design requirements.

[0137] It should be noted that, although not shown in the above figures, some other components (e.g., cover plate or optical film) may be formed on the display device of the above embodiments. For example, the cover plate may be formed of glass, indium tin oxide, polyimide, polyethylene terephthalate, other suitable materials or combinations thereof, but the present disclosure is not limited thereto. For example, the optical film may include a diffuser film, a focusing lens, other suitable optical films or combinations thereof, but the present disclosure is not limited thereto.

[0138] In addition, for the convenience of explanation, only one light emitting unit of the display device is shown in some of the above figures. However, a person skilled in the art should understand that the display device can include any appropriate number of light emitting units according to design requirements.

[0139] [Second embodiment]

[0140] The present embodiment provides a method for forming a display device by bonding a light-emitting unit (e.g., a light-emitting diode) to a substrate (e.g., a thin film transistor). In the above method, an adhesive layer is first provided on a first substrate, and then a portion of the adhesive layer is attached to the light-emitting unit and the light-emitting unit is bonded to a second substrate such as a thin film transistor substrate via the portion to form the display device of the present embodiment. Compared to the conventional bonding method of first bonding the entire adhesive layer to the second substrate and then bonding the light-emitting unit to the second substrate, the method for forming the display device of the present embodiment has greater process flexibility and can be used to repair defective components.

[0141] FIG. 6A to FIG. 6E is a series of process cross-sectional views, which illustrate the method of forming a display device according to this embodiment.

[0142] First, if Fig. 6A As shown, an adhesive layer 602 is provided on the first substrate 600. In some embodiments, in subsequent processes, the adhesive layer 602 will be used to bond the light-emitting unit to another substrate.

[0143] In some embodiments, the adhesive layer 602 may be formed of a conductive material such as anisotropic conductive adhesive. For example, the adhesive layer 602 may include a plurality of conductive particles 603 substantially uniformly distributed therein. For example, any conductive particle 603 may be substantially circular or elliptical in cross-sectional view. For example, the diameter d1 of any conductive particle 603 may be 0.1 to 10 micrometers.

[0144] In some embodiments, the conductive particles 603 may be spacers, which can be used to control the distance between the light-emitting unit and the substrate after bonding. In some embodiments, the length (or diameter) of the spacer is less than the thickness of the conductor layer (e.g., the conductor layers 608 and 610 described below) of the light-emitting unit. For example, the surface of the spacer may be plated with a metal that can be eutectic bonded or low-temperature soldered, such as tin (Sn), silver (Ag), indium (In), copper (Cu), gold (Au), nickel (Ni), palladium (Pd), platinum (Pt), alloys thereof, or combinations thereof, but the present disclosure is not limited thereto.

[0145] In some embodiments, the adhesive layer 602 may also include an under fill film.

[0146] Please continue to refer to Fig. 6A, the light emitting unit 604 is moved onto the first substrate 600 and partially inserted into the adhesive layer 602. In some embodiments, a pick head 601 can be used to grab the light emitting unit 604 and move the light emitting unit 604 above the adhesive layer 602, and then the pick head 601 is lowered to imprint the light emitting unit 604 on the adhesive layer 602.

[0147] In this embodiment, before the grabbing head 601 grabs the light-emitting unit 604, the light-emitting unit motherboard (not shown in the figure) of the light-emitting unit 604 has been removed, but the present disclosure is not limited thereto. In some other embodiments, when the grabbing head 601 grabs the light-emitting unit 604, the light-emitting unit motherboard (for example, sapphire substrate) has not been removed, so the light-emitting unit motherboard can be located between the grabbing head 601 and the light-emitting unit 604, and the grabbing head 601 can control the movement of the light-emitting unit 604 by grabbing and moving the light-emitting unit motherboard. For example, after the light-emitting unit 604 is bonded to the second substrate described later, the light-emitting unit motherboard can be removed by a process such as laser lift-off.

[0148] like Fig. 6A As shown, the light-emitting unit 604 may include a light-emitting body 606, a conductor layer 608, and a conductor layer 610. In some embodiments, the conductor layer 608 and the conductor layer 610 may be the same as or similar to the first conductor layer 108a and the third conductor layer 110a of the aforementioned embodiment. In some other embodiments, the conductor layer 608 and the conductor layer 610 may be the same as or similar to the second conductor layer 108b and the fourth conductor layer 110b of the aforementioned embodiment. For example, the first conductor layer (or the second conductor layer) 608 and the third conductor layer (or the fourth conductor layer) 610 may be electrodes of the light-emitting unit 604 and electrically connected to the substrate of the display device.

[0149] Then, if Figure 6B As shown, the light emitting unit 604 can be lifted upward by the gripping head 601, so that a portion 602a of the adhesive layer 602 is attached to the light emitting unit 604 and separated from the first substrate 600. In detail, the portion 602a of the adhesive layer 602 separated from the first substrate 600 can be attached to the first conductor layer (or the second conductor layer) 608 and the third conductor layer (or the fourth conductor layer) 610 of the light emitting unit 604.

[0150] Then, if Figure 6CAs shown, in some embodiments, the light emitting unit 604 and the portion 602a of the adhesive layer 602 are moved onto the second substrate 612 by the grabbing head 601, and then the light emitting unit 604 is bonded to the second substrate 612 via the portion 602a of the adhesive layer 602 and the grabbing head 601 is removed from the light emitting unit 604. Specifically, in some embodiments, the first conductor layer (or the second conductor layer) 608 and the third conductor layer (or the fourth conductor layer) 610 of the light emitting unit 604 can be bonded to the bonding pads (not shown individually in the figure) of the second substrate 612 via the portion 602a of the adhesive layer 602. For example, the bonding pads can be formed of a conductive material such as metal.

[0151] For example, the second substrate 612 may include one or more active components (not shown in the figure), such as transistors. For example, the second substrate 612 may be a thin film transistor substrate. In some embodiments, the one or more active components may be electrically connected to the light emitting unit 604 via the bonding pads of the second substrate 612 and the first conductor layer (or second conductor layer) 608 and the third conductor layer (or fourth conductor layer) 610. In some embodiments, the one or more active components may control or adjust the driving signal (e.g., current signal) transmitted to the light emitting unit 604 to adjust the brightness of the light emitting unit 604.

[0152] In some embodiments, the step of bonding the light-emitting unit 604 to the second substrate 612 may include applying appropriate pressure (e.g., 1 to 100 MPa) and / or temperature (e.g., 100 to 300° C.) to portion 602a of the adhesive layer 602 to increase the adhesion of portion 602a of the adhesive layer 602, so that portion 602a of the adhesive layer 602 can bond the light-emitting unit 604 to the second substrate 612.

[0153] In some embodiments, the step of bonding the light-emitting unit 604 to the second substrate 612 may include a eutectic bonding process. The eutectic bonding process may require specific metal materials (such as tin alloys or silver-gold mixtures), and may occur if the process temperature is increased to a suitable temperature. For example, the eutectic bonding process may cause a eutectic reaction between the first conductor layer (or second conductor layer) 608, the third conductor layer (or fourth conductor layer) 610 and the conductive particles 603, and between the bonding pads of the substrate 118 and the conductive particles 603, so as to bond the light-emitting unit 604 to the second substrate 612.

[0154] As mentioned above, in some embodiments, the conductive particles 603 can be spacers, which can be used to control the distance d2 between the light emitting unit 604 and the substrate 612. In some embodiments where the conductive particles 603 can be spacers, the distance d2 between the light emitting unit 604 and the second substrate 612 is substantially equal to the diameter d1 of any conductive particle 603.

[0155] Then, if Fig.6D and Fig. 6E As shown, the above steps may be repeated to bond another light emitting unit 604 to the substrate 618 via the portion 602b of the adhesive layer 602 to form the display device 60 of the present disclosure. In some embodiments, the above steps may be repeated multiple times to bond a plurality of light emitting units 604 of different colors (e.g., red, blue, and green) to the substrate 612 via the adhesive layer 602.

[0156] In some embodiments, each light-emitting unit 604 has its corresponding bonding step. In other words, in these embodiments, after a light-emitting unit 604 and a portion of the adhesive layer attached thereto are moved to the corresponding bonding pad of the second substrate 612, a corresponding bonding step is performed to bond the light-emitting unit to the second substrate 612. However, in some other embodiments, a plurality of light-emitting units 604 and a portion of the adhesive layer attached thereto may be moved to the corresponding bonding pad of the second substrate 612 before a bonding step (e.g., applying the aforementioned appropriate pressure and / or temperature or performing a eutectic bonding process) is performed to bond several light-emitting units 604 to the second substrate 612 at the same time, thereby achieving the effect of reducing process steps and shortening working time.

[0157] In some embodiments, after the plurality of light-emitting units 604 are bonded to the second substrate 612, a quality test may be performed on the plurality of light-emitting units 604. For example, if the quality of any light-emitting unit 604 is abnormal, the light-emitting unit 604 and the corresponding part of the adhesive layer may be removed from the second substrate 612 (for example, by mechanically peeling it from the second substrate 612), and then the quality test may be performed. FIG. 6A to FIG. 6C The steps described herein bond another light emitting unit 604 to the second substrate 612 to replace the light emitting unit 604 with abnormal quality. In other words, compared to the conventional bonding method of bonding the entire adhesive layer to the second substrate, the method of this embodiment can partially replace the light emitting unit with abnormal quality, thereby increasing process flexibility and achieving the effect of reducing process steps and shortening working hours.

[0158] Some variations of the present embodiment are provided below. It should be noted that, unless otherwise specified, the same or similar components of these variations as those of the aforementioned embodiment will be represented by the same component symbols, and their formation methods may also be the same or similar to the formation methods of the aforementioned embodiment.

[0159] Fig. 6F A display device 60' of some embodiments of the present disclosure is shown. One difference between the display device 60' and the display device 60 is that the adhesive layer 602 of the display device 60' is formed of a non-conductive material. For example, the non-conductive material may include polyimide, epoxy-containing resin, silicon, photoresist, other appropriate materials, or a combination thereof. In some embodiments, since the adhesive layer 602 is non-conductive, the first conductor layer (or second conductor layer) 608 and the third conductor layer (or fourth conductor layer) 610 of the light-emitting unit 604 are directly in contact with the bonding pad (not shown in the figure) of the second substrate 612 to electrically connect the second substrate 612. In some embodiments, the first conductor layer (or second conductor layer) 608 and the third conductor layer (or fourth conductor layer) 610 may further be eutectic reacted with the bonding pad of the second substrate 612 to increase the bonding force between the two.

[0160] In some embodiments, the adhesive layer 602 may include a photocurable material and / or a thermal curable material. For example, the uncured adhesive layer 602 may be provided on the first substrate 600, and then the same or similar FIG. 6A to FIG. 6E The steps described above transfer the light-emitting unit 604 and its corresponding portion 602a and / or 602b of the adhesive layer to the second substrate 612, and then a photocuring and / or thermal curing process can be performed to cure the portions 602a and / or 602b of the adhesive layer 602 to increase their adhesion, so that the portions 602a and / or 602b of the adhesive layer 602 can be bonded to the light-emitting unit 604 and the second substrate 612.

[0161] Figure 6G , 6H 2 are partial top views and cross-sectional views each illustrating a display device 60" according to some embodiments of the present disclosure. In detail, Figure 6H For along Figure 6G In these embodiments, the grabbing head 601 grabs a plurality of (e.g., three, six, eight, hundreds, hundreds or more, or other appropriate number) light emitting units 604 at a time, and attaches the grabbed light emitting units 604 to the adhesive layer 602 through a portion (e.g., Figure 6G The light emitting units 604 are bonded to the second substrate 612 by the gripping head 601. The gripping head 601 can then be used to grip a plurality of other light emitting units 604 and to attach the gripped light emitting units 604 to another portion of the adhesive layer 602 (e.g., Figure 6G The other of the illustrated portions 602a-602i) is bonded to the second substrate 612. In other words, Figure 6GIn the illustrated embodiment, the grabbing head 601 repeatedly grabs a plurality of light emitting units 604 at a time and bonds the grabbed light emitting units 604 to the second substrate 612 via a portion of the adhesive layer 602 (e.g., any one of the portions 602a-602i). Figure 6G As shown, any of the multiple separated parts 602a-602i of the adhesive layer 602 may correspond to eight light-emitting units 604, but the present disclosure is not limited thereto. It should be understood that any of the multiple separated parts of the adhesive layer 602 (for example, any of the parts 602a-602i) is to bond the corresponding light-emitting unit 604 to the second substrate 612, and in the top view, any of the multiple separated parts of the adhesive layer 602 overlaps or partially overlaps with the corresponding light-emitting unit 604. For example, Figure 6G As shown, any one of the plurality of separated portions 602 a - 602 i of the adhesive layer 602 overlaps with eight light emitting units 604 and bonds the corresponding eight light emitting units 604 to the second substrate 612 .

[0162] like Figure 6G As shown, in some embodiments, multiple portions of the adhesive layer 602 of the display device 60" are aligned with each other in the first direction Y and the second direction X (the second direction X may be substantially perpendicular to the first direction Y), but the present disclosure is not limited thereto. In some other embodiments, multiple portions of the adhesive layer 602 may have a misalignment in at least one of the first direction Y and the second direction X. For example, in Fig.6I In the illustrated embodiment, when viewed from the first direction Y, there is a misalignment between two adjacent rows of the adhesive layer 602. Fig.6I In the illustrated embodiment, there is a misalignment between the first row L1 (including portions 602a, 602b, and 602c) and the second row L2 (including portions 602d, 602e, 602f, and 602g) of the adhesive layer 602, and there is also a misalignment between the second row L2 and the third row L3 (including portions 602h, 602i, and 602j). In some embodiments, the misalignment can be defined as the distance between the center lines of two adjacent portions of the adhesive layer 602 (the two portions are each located on two adjacent rows) (for example, the distance M between the center line F1 of the portion 602b of the first row L1 and the center line F2 of the portion 602f of the second row L2).

[0163] Other variations of the present embodiment are provided below. It should be noted that, unless otherwise specified, the same or similar components of these variations as those of the aforementioned embodiment will be represented by the same component symbols, and their formation methods may also be the same or similar to the formation methods of the aforementioned embodiment.

[0164] Figure 6JFIG. 6 is a partial top view of a display device 60a of some embodiments of the present disclosure. Figure 6J Only a few light-emitting units 604 of the display device 60a and a few parts (eg, parts 602a-602d) of the adhesive layer 602 corresponding to these light-emitting units 604 are shown. Figure 6J As shown, the adhesive layer 602 includes a plurality of substantially adjacent portions (e.g., portions 602a-602d). For the sake of convenience in the following description, portion 602a, portion 602b, portion 602c, and portion 602d may also be referred to as the first adhesive layer 602a, the second adhesive layer 602b, the third adhesive layer 602c, and the fourth adhesive layer 602d, respectively.

[0165] In some embodiments, the display device 60a may have a plurality of pixels V. For example, in some embodiments, one pixel V may correspond to (or include) at least one light emitting unit 604 (eg, Figure 6J ) and corresponds to (or includes) a portion of the adhesive layer 602 corresponding to the light emitting unit 604, but the present disclosure is not limited thereto. It should be understood that although Figure 6J Only four pixels V are shown in the figure, but the present disclosure is not limited thereto, and the display device 60a may have any appropriate number of pixels V according to design requirements.

[0166] like Figure 6J As shown, one of the plurality of light emitting units 604 may have a length P1 (e.g., 1 to 100 microns) in the first direction Y and a length P2 (e.g., 1 to 100 microns) in the second direction X (the second direction X may be substantially perpendicular to the first direction Y). In some embodiments, the length P1 may be less than the length P2, but the disclosure is not limited thereto. In some other embodiments, the length P1 may also be greater than or equal to the length P2. Figure 6J As shown, two adjacent light emitting units 604 may have a spacing Z1 in the first direction Y and a spacing Z2 in the second direction X. In some embodiments, the spacing Z1 may be 1 to 1000 microns, and the spacing Z2 may be 1 to 1000 microns.

[0167] like Figure 6J As shown, one of the plurality of adhesive layers of the display device 60a (for example, one of the first adhesive layer 602a, the second adhesive layer 602b, the third adhesive layer 602c and the fourth adhesive layer 602d) at least partially overlaps with the corresponding light emitting unit 604. Figure 6JAs shown, in some embodiments, the first adhesive layer 602a, the second adhesive layer 602b, the third adhesive layer 602c, and the fourth adhesive layer 602d each partially overlap with a light-emitting unit 604. In some embodiments, as shown in FIG. 6J, there may be a spacing Z3 between adjacent adhesive layers in the first direction Y (e.g., the first adhesive layer 602a and the second adhesive layer 602b), and there may be a spacing Z4 between adjacent adhesive layers in the second direction X (e.g., the first adhesive layer 602a and the third adhesive layer 602c). In some embodiments, 0 < Z3 < (Z1 + P1) and / or 0 < Z4 < (Z2 + P2), which can reduce the problem of poor electrical connection between the light-emitting unit 604 and the second substrate 612 caused by insufficient adhesion due to too small an adhesion area between the adhesive layer and the light-emitting unit 604.

[0168] In some embodiments, as Figure 6K shown, one pixel V may correspond to three light-emitting units 604 and the adhesive layers corresponding to these three light-emitting units. For example, the three light-emitting units 604 corresponding to one of the several adhesive layers of the display device 60a (e.g., one of the first adhesive layer 602a, the second adhesive layer 602b, the third adhesive layer 602c, and the fourth adhesive layer 602d) may include a red light-emitting unit, a blue light-emitting unit, and a green light-emitting unit, but the present disclosure is not limited thereto. In some other embodiments, the three light-emitting units 604 corresponding to one of the several adhesive layers of the display device 60a may also be light-emitting units of the same color.

[0169] Similarly, in some Figure 6K illustrated embodiments, 0 < Z3 < (Z1 + P1) and / or 0 < Z4 < (Z2 + P2), which can reduce the problem of poor electrical connection between the light-emitting unit 604 and the second substrate 612 caused by insufficient adhesion due to too small an adhesion area between the adhesive layer 602 and the light-emitting unit 604. It should be understood that although in the foregoing embodiments, one pixel V corresponds to three light-emitting units 604, and the three light-emitting units 604 corresponding to one of the several adhesive layers of the display device 60a (e.g., one of the first adhesive layer 602a, the second adhesive layer 602b, the third adhesive layer 602c, and the fourth adhesive layer 602d) are arranged in a column (or a row), the present disclosure is not limited thereto. In some other embodiments, the three light-emitting units 604 corresponding to one of the several adhesive layers of the display device 60a may also be arranged in a triangle (as Figure 6L 、 6M shown).

[0170] Similarly, in some Figure 6LIn the embodiment illustrated in FIG. 6M, 0 < Z3 < (Z1 + P1) and / or 0 < Z4 < (Z2 + P2), which can reduce the problem of poor electrical connection between the light-emitting unit 604 and the second substrate 612 caused by insufficient adhesion due to too small an adhesion area between the adhesive layer 602 and the light-emitting unit 604.

[0171] In some other embodiments, one of the plurality of adhesive layers of the display device 60a (for example, one of the first adhesive layer 602a, the second adhesive layer 602b, the third adhesive layer 602c, and the fourth adhesive layer 602d) is disposed corresponding to six light-emitting units 604 (as Figure 6N shown). In these embodiments, the six light-emitting units 604 corresponding to one of the plurality of adhesive layers of the display device 60a may all be light-emitting units of the same color or include light-emitting units of different colors.

[0172] Similarly, in some Figure 6N In the embodiment illustrated in FIG. 6M, 0 < Z3 < (Z1 + P1) and / or 0 < Z4 < (Z2 + P2), which can reduce the problem of poor electrical connection between the light-emitting unit 604 and the second substrate 612 caused by insufficient adhesion due to too small an adhesion area between the adhesive layer 602 and the light-emitting unit 604.

[0173] It should be understood that in some other embodiments, one pixel V may correspond to any other appropriate number of light-emitting units 604 according to the design requirements.

[0174] The light-emitting unit 604 of this embodiment may also include the light-emitting unit 103 described in the foregoing first embodiment. In other words, the method described in this embodiment can be used to bond the light-emitting unit 103 to a substrate such as a thin-film transistor substrate.

[0175] [Third Embodiment].

[0176] This embodiment provides a method of bonding a light-emitting unit (for example, a light-emitting diode) to a substrate (for example, a thin-film transistor) to form a display device. In the above method, an adhesive layer is provided on a substrate such as a thin-film transistor substrate, and then the above adhesive layer is patterned by a photolithography process. Since the patterned adhesive layer is formed by a photolithography process, the formed pattern can have a smaller size and can be applied to bond small-sized light-emitting units to a substrate (for example, a thin-film transistor substrate) of a display device.

[0177] FIG. 7A to FIG. 7D FIGS. 22A-22F are a series of process cross-sectional views illustrating the method of forming a display device according to this embodiment.

[0178] As Fig. 7AAs shown, a substrate 700 is provided. In some embodiments, the substrate 700 may include one or more bonding pads disposed thereon. Fig. 7A In the illustrated embodiment, the substrate 700 includes four bonding pads C1, C2, C3 and C4, but the present disclosure is not limited thereto, and the substrate 700 may include any appropriate number of bonding pads according to design requirements (e.g., the number of light-emitting units bonded to the substrate 700). In some embodiments, the bonding pads (e.g., C1, C2, C3 and C4) may be formed of a conductive material such as metal.

[0179] In some embodiments, two adjacent bonding pads C1, C2 and bonding pads C3, C4 may each correspond to a different light emitting unit. Fig. 7A As shown, there may be a spacing S1 between adjacent bonding pads corresponding to the same light-emitting unit (e.g., the spacing between bonding pads C1 and C2 or the spacing between bonding pads C3 and C4). In some embodiments, the spacing S1 is substantially equal to the spacing between the conductor layers (e.g., electrodes) of the light-emitting unit to be bonded to the substrate 700. For example, the spacing S1 may be 2 to 200 microns.

[0180] In some embodiments, there may be a spacing S2 between adjacent bonding pads corresponding to different light-emitting units (for example, the spacing between bonding pads C2 and C3). For example, when used in a large display device, the spacing S2 can reach 50 millimeters (mm). However, as the display device is miniaturized, the spacing S2 is gradually reduced. In some embodiments, the spacing S2 can be as small as 2 microns (for example, 2 microns to 500 microns). It should be understood that the present process method can be applied to both micro devices and large display devices.

[0181] Then, if Figure 7B As shown, an adhesive layer 704 is formed on the substrate 700, and the adhesive layer 704 can cover the bonding pads C1, C2 and the bonding pads C3, C4. In some embodiments, the adhesive layer 704 is formed of a non-conductive material. In some embodiments, the adhesive layer 704 is a photoresist material that can be patterned through a photolithography process. For example, the photoresist material may include, for example: polymethyl methacrylate (Acrylic), siloxane (Siloxane) or polyimide (Polyimide), but the present disclosure is not limited to this. In some embodiments, the adhesive layer 704 may include a photocurable material and / or a thermosetting material that has not yet been cured. For example, a slit nozzle (Slit Nozzle) can be used to apply the adhesive layer 704 on the substrate 700.

[0182] In some embodiments, a soft baking process may be performed after coating the adhesive layer 704 on the substrate 700 to increase the adhesion of the adhesive layer 704 to the surface of the substrate 700 .

[0183] Then, if Figure 7C As shown, the adhesive layer 704 is patterned to form a patterned adhesive layer 704. For example, the patterning step may include exposure, post-exposure baking, developing, other appropriate processes or a combination thereof.

[0184] In some embodiments, after the patterning step, the patterned adhesive layer 704 may have a plurality of mutually separated patterns (eg, a first pattern 704A and a second pattern 704B) corresponding to different light-emitting units. Figure 7C As shown, the first pattern 704A corresponds to the light emitting units corresponding to the bonding pads C1 and C2, and the second pattern 704B corresponds to the light emitting units corresponding to the bonding pads C3 and C4.

[0185] As mentioned above, as the display device is miniaturized, the spacing S2 may gradually decrease, so the spacing S3 between the first pattern 704A and the second pattern 704B is also gradually reduced (for example, the spacing S3 can be reduced from the traditional 50 mm to 2 microns). Therefore, if the patterned adhesive layer 704 is formed by a traditional method such as screen printing, the spacing S3 will be too large and not conducive to the miniaturization of the display device. In contrast, the method described in this embodiment forms the patterned adhesive layer 704 by a photolithography process, so it has a smaller spacing S3 (for example, the spacing S3 can be reduced to about 2 microns to 200 microns).

[0186] In addition, as the size of the light-emitting unit is reduced (e.g., the width), the width W1 of the first pattern 704A and the second pattern 704B corresponding to the light-emitting unit also needs to be reduced accordingly. Therefore, if the patterned adhesive layer 704 is formed by a conventional method such as screen printing, the width W1 will be too large and not suitable for bonding small-sized light-emitting units. In contrast, the method described in this embodiment forms the patterned adhesive layer 704 by a photolithography process, so the first pattern 704A and the second pattern 704B can have a smaller width W1. In some embodiments, the width W1 of the first pattern 704A and the second pattern 704B can be reduced to about 8 microns (e.g., about 8 microns to 240 microns).

[0187] In some embodiments, Figure 7CAs shown, after the above patterning step, the patterned adhesive layer 704 still covers the bonding pads C1, C2, C3 and C4 without exposing the top surfaces of the bonding pads C1, C2, C3 and C4. Further, in some embodiments, the pattern 704A covers the corresponding bonding pads C1 and C2, while the pattern 704B covers the corresponding bonding pads C3 and C4.

[0188] Then, if Fig.7D As shown, the light emitting unit 706 is inserted into the pattern 704A and the pattern 704B of the patterned adhesive layer 704 .

[0189] In some embodiments, Fig.7D As shown in FIG. 1 , since the light emitting unit 706 is inserted into the first pattern 704A and the second pattern 704B of the patterned adhesive layer 704 before the patterned adhesive layer 704 is cured, the materials of the first pattern 704A and the second pattern 704B may be squeezed by the light emitting unit 706 and flow outward. Fig.7D As shown, after the step of inserting the light emitting unit 706 into the first pattern 704A and the second pattern 704B of the patterned adhesive layer 704, the first pattern 704A and the second pattern 704B may have a curved sidewall profile.

[0190] Then, still Fig.7D As shown, a curing process (e.g., a thermal curing process and / or a photocuring process) is performed to cure the patterned adhesive layer 704 to increase the adhesion of the patterned adhesive layer 704 so that the patterned adhesive layer 704 can be bonded to the light-emitting unit 706 and the substrate 700 to form the display device 70 of the present disclosure. In some embodiments, since the cured patterned adhesive layer 704 can bond the light-emitting unit 706 and the substrate 700, no additional bonding process is required (for example, a eutectic bonding process that causes the first conductor layer (or second conductor layer) 710, the third conductor layer (or fourth conductor layer) 712 of the light-emitting unit 706 to undergo a eutectic reaction with the bonding pads C1, C2, C3, C4 of the substrate 700) to bond the first conductor layer (or second conductor layer) 710, the third conductor layer (or fourth conductor layer) 712 of the light-emitting unit 706 to the bonding pads C1, C2, C3, C4 of the substrate 700, so as to electrically connect the substrate 700 and the light-emitting unit 706 via the bonding pads C1, C2, C3, C4 of the substrate 700.

[0191] like Fig.7DAs shown, the adjacent light-emitting units 706 of the display device 70 may have a spacing S4. In some embodiments, since the patterned adhesive layer 704 is formed by a photolithography process, the first pattern 704A and the second pattern 704B may have a smaller spacing S2, so that the adjacent light-emitting units 706 may also have a smaller spacing S4, thereby increasing the number of light-emitting units 706 per unit area and facilitating the miniaturization of the display device. For example, in some embodiments, the spacing S4 may be reduced to about 2 microns (e.g., about 2 microns to 200 microns).

[0192] As mentioned above, in some embodiments, since the patterned adhesive layer 704 is formed by a photolithography process, the first pattern 704A and the second pattern 704B may have a smaller width W1 (e.g., 8 microns to 240 microns). In other words, in these embodiments, the first pattern 704A and the second pattern 704B are suitable for bonding a small-sized light-emitting unit 706 to the substrate 700. For example, in some embodiments, the first pattern 704A and the second pattern 704B may be used to bond a light-emitting unit 706 having a width W2 of 8 microns to 240 microns to the substrate 700.

[0193] In some embodiments, Fig.7D As shown, the first pattern 704A and the second pattern 704B can fill or partially fill the gap between the conductor layers 710 and 712 of the light emitting unit 706, thereby increasing the strength of fixing the light emitting unit 706 on the substrate 700. In some embodiments, since the first pattern 704A and the second pattern 704B surround the conductor layers 710, 712 of the light emitting unit 706 and the bonding pads C1, C2, C3, C4 of the substrate 700, the conductor layers 710, 712 of the light emitting unit 706 and the bonding pads C1, C2, C3, C4 of the substrate 700 can be protected from damage such as moisture.

[0194] FIG. 8A to FIG. 8D It should be noted that, unless otherwise specified, the same or similar components in these variations as those in the above-mentioned embodiment will be represented by the same component symbols, and their formation methods may also be the same or similar to those in the above-mentioned embodiment.

[0195] Fig. 8A , Figure 8B , Figure 8C and Fig.8D The steps are the same or similar to Fig. 7A , Figure 7B , Figure 7C and Fig.7D The steps described above are similar to those described above, so only the differences are described below.

[0196] like Figure 8CAs shown, in some embodiments, the first pattern 704A and the second pattern 704B of the patterned adhesive layer 704 expose the top surface of the bonding pads C1, C2 and the bonding pads C3, C4. Specifically, in some embodiments, the first pattern 704A includes openings O1, O2 exposing the bonding pads C1, C2, and the second pattern 704B includes openings O3, O4 exposing the bonding pads C3, C4.

[0197] Next, as shown in FIG. 8D , the light emitting unit 706 is bonded to the substrate 700 via the first pattern 704A and the second pattern 704B to form the display device 80 of the present disclosure. In some embodiments, as shown in FIG. 8D , since the first pattern 704A and the second pattern 704B include openings O1, O2, O3, and O4, and the conductor layers 710 and 712 are inserted into the openings O1, O2, O3, and O4, the materials of the first pattern 704A and the second pattern 704B can be substantially reduced from being squeezed by the light emitting unit 706 and flowing outward, so that the first pattern 704A and the second pattern 704B can have substantially straight sidewalls after the above bonding process.

[0198] In some embodiments, since the first pattern 704A and the second pattern 704B include the openings O1 , O2 and O3 , O4 , when the light emitting unit 706 is bonded to the substrate 700 , the situation where the materials of the first pattern 704A and the second pattern 704B overflow outward in large quantities can be improved.

[0199] In addition, the light emitting unit 706 of this embodiment may also include the light emitting unit 103 described in the first embodiment. In other words, the light emitting unit 103 may be bonded to a substrate such as a thin film transistor substrate using the method described in this embodiment.

[0200] [Fourth embodiment].

[0201] This embodiment also provides a method for bonding a light-emitting unit (e.g., a light-emitting diode) to a substrate (e.g., a thin film transistor) to form a display device. One difference between this embodiment and the third embodiment is that the adhesive layer used in this embodiment includes a conductive material. In other words, the light-emitting unit can be electrically connected to the substrate of the display device via the adhesive layer.

[0202] It should be noted that, unless otherwise specified, the same or similar components in this embodiment and the aforementioned embodiment will be represented by the same component symbols, and the formation methods thereof may also be the same or similar to the formation methods in the aforementioned embodiment.

[0203] Fig. 9A , Fig. 9B , Fig. 9C and Fig.9D The steps are the same or similar to Fig. 7A , Figure 7B , Figure 7C and Fig.7D The steps described above are similar to those described above, so only the differences are described below.

[0204] like Fig. 9B As shown, in some embodiments, the adhesive layer 704 may be formed of a photoresist material (e.g., acrylic, siloxane, or polyimide (PI, Polyimide), etc.) and a conductive material added to the photoresist material. In some embodiments, the adhesive layer 704 may include a photocurable material and / or a thermal curable material that has not yet been cured. For example, the conductive material may be an electrocarbon molecule (graphite, graphene, carbon nanotubes), a metal particle (copper, tungsten, silver, tin, nickel, chromium, titanium, lead, gold, bismuth, antimony, zinc, zirconium, magnesium, indium, tellurium, gallium) or its alloy particles, a conductive metal oxide particle (indium tin oxide (ITO), tin oxide (SnO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin zinc oxide (ITZO), antimony tin oxide (ATO), antimony zinc oxide (AZO)), or other appropriate conductive materials, but the present disclosure is not limited thereto.

[0205] Then, if Fig. 9C As shown, the adhesive layer 704 is patterned. In some embodiments, the patterned adhesive layer 704 may include a first pattern 704A and a second pattern 704B, and the first pattern 704A may include two sub-patterns 704a and the second pattern 704B may include two sub-patterns 704b. In some embodiments, the two sub-patterns 704a of the first pattern 704A are separated from each other (the two sub-patterns 704b of the second pattern 704B are also separated from each other), so as to reduce the short circuit between the first conductor layer (or the second conductor layer) 710 and the third conductor layer (or the fourth conductor layer) 712 of the light emitting unit 706 bonded to the substrate 700 via the first pattern 704A and / or the second pattern 704B.

[0206] Then, if Fig.9DAs shown, the light emitting unit 706 is disposed on the patterned adhesive layer 704 and a process such as photocuring and / or thermal curing is performed to cure the patterned adhesive layer 704 to increase the adhesion of the patterned adhesive layer 704, so that the light emitting unit 706 can be bonded to the substrate 700 via the first pattern 704A and the second pattern 704B to form the display device 90 of the present disclosure. In detail, in some embodiments, the two sub-patterns 704a of the first pattern 704A are respectively connected to the first conductor layer (or second conductor layer) 710 and the third conductor layer (or fourth conductor layer) 712 of one light emitting unit 706, and the two sub-patterns 704b of the second pattern 704B are respectively connected to the first conductor layer (or second conductor layer) 710 and the third conductor layer (or fourth conductor layer) 712 of another light emitting unit 706.

[0207] In some embodiments, since the patterned adhesive layer 704 has a conductive property, the first conductor layer (or the second conductor layer) 710 and the third conductor layer (or the fourth conductor layer) 712 can be electrically connected to the bonding pads C1, C2, C3, and C4 of the substrate 700 via the patterned adhesive layer 704. In other words, in these embodiments, the first conductor layer (or the second conductor layer) 710 and the third conductor layer (or the fourth conductor layer) 712 do not need to directly contact the bonding pads C1, C2, C3, and C4.

[0208] In addition, the light emitting unit 706 of this embodiment may also include the light emitting unit 103 described in the first embodiment. In other words, the light emitting unit 103 may be bonded to a substrate such as a thin film transistor substrate using the method described in this embodiment.

[0209] It should be understood that the method of this embodiment can be applied to light-emitting units of various sizes (for example, light-emitting diodes of various sizes). In some embodiments, the light-emitting unit is a light-emitting diode, and the chip size of the light-emitting diode is about 300 microns (μm) to 10 millimeters (mm), but the present disclosure is not limited to this. In some embodiments, the light-emitting unit is a sub-millimeter light-emitting diode (mini LED), and the chip size of the sub-millimeter light-emitting diode is about 100 microns (μm) to 300 microns (μm), but the present disclosure is not limited to this. In some embodiments, the light-emitting unit is a micro light-emitting diode (micro LED), and the chip size of the micro light-emitting diode is about 1 micron (μm) to 100 microns (μm), but the present disclosure is not limited to this.

[0210] The foregoing summarizes the features of several embodiments so that those with ordinary knowledge in the art can better understand the various aspects of the present disclosure. Those with ordinary knowledge in the art should understand and can easily design or modify other processes and structures based on the present disclosure to achieve the same purpose and / or achieve the same advantages as the embodiments introduced herein. Those with ordinary knowledge in the art should also understand that these equivalent structures do not deviate from the spirit and scope of the present disclosure. Various changes, substitutions or modifications may be made to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure.

Claims

1. A display device, comprising: a substrate; a first light-emitting unit and a second light-emitting unit, disposed on the substrate, the first light-emitting unit adjacent to the second light-emitting unit, wherein, in a first direction, the first light-emitting unit has a length P1, and the first light-emitting unit and the second light-emitting unit have a spacing Z1, and the first light-emitting unit includes: a first conductor layer and a second conductor layer overlapping each other; a first semiconductor layer, disposed between the first conductor layer and the second conductor layer; a second semiconductor layer, disposed between the first semiconductor layer and the first conductor layer; a quantum well structure, disposed between the first semiconductor layer and the second semiconductor layer; a through hole, penetrating through the first semiconductor layer and the quantum well structure; and a conductive material, disposed in the through hole, wherein the second conductor layer is electrically connected to the second semiconductor layer via the conductive material; a first adhesive layer is disposed between the substrate and the first light-emitting unit, and a second adhesive layer is disposed between the substrate and the second light-emitting unit, wherein, in the first direction, the first adhesive layer and the second adhesive layer have a spacing Z3, wherein, Z1, Z3 and P1 satisfy the following formula: 0 < Z3 < (Z1 + P1), and Z1, Z3 and P1 are all greater than 0 microns.

2. The display device according to claim 1, further comprising a pixel, and the first light-emitting unit and the first adhesive layer are disposed corresponding to the pixel.

3. The display device according to claim 2, further comprising: a third light-emitting unit and a fourth light-emitting unit, wherein the third light-emitting unit and the fourth light-emitting unit are disposed corresponding to the pixel.

4. A method for forming a display device according to claim 1, comprising: providing a substrate, wherein a plurality of bonding pads are disposed on the substrate; forming an adhesive layer on the substrate and covering the plurality of bonding pads; forming a patterned adhesive layer corresponding to the plurality of bonding pads by a photolithography process; bonding a light-emitting unit to at least one bonding pad via the patterned adhesive layer.

5. The method for forming a display device according to claim 4, wherein: The step of bonding the light-emitting unit to at least one bonding pad includes performing a curing process to cure the patterned adhesive layer.

6. The method for forming a display device according to claim 4, wherein: The light-emitting unit includes: a first conductor layer and a second conductor layer overlapping each other; a first semiconductor layer, disposed between the first conductor layer and the second conductor layer; a second semiconductor layer, disposed between the first semiconductor layer and the first conductor layer; a quantum well structure, disposed between the first semiconductor layer and the second semiconductor layer; a through hole, penetrating through the first semiconductor layer and the quantum well structure; and a conductive material, disposed in the through hole, wherein the second conductor layer is electrically connected to the second semiconductor layer via the conductive material.

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