CN113964248B - Display device and method for manufacturing the same - Google Patents

Display device and method for manufacturing the same Download PDF

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Publication number
CN113964248B
CN113964248B CN202111191246.8A CN202111191246A CN113964248B CN 113964248 B CN113964248 B CN 113964248B CN 202111191246 A CN202111191246 A CN 202111191246A CN 113964248 B CN113964248 B CN 113964248B
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light
opening
emitting element
layer
display device
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CN113964248A (en
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刘仲展
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AU Optronics Corp
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AU Optronics Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/20—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/0665—Shaping the laser beam, e.g. by masks or multi-focusing by beam condensation on the workpiece, e.g. for focusing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
    • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
    • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0093—Wafer bonding; Removal of the growth substrate

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Computer Hardware Design (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Led Device Packages (AREA)
  • Led Devices (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Abstract

The invention discloses a display device and a manufacturing method thereof, wherein the display device comprises a circuit substrate and a light-emitting element. The light-emitting element is electrically connected with the circuit substrate and is provided with an opening, wherein the opening is positioned at one side of the light-emitting element, which is close to or far from the circuit substrate.

Description

Display device and method for manufacturing the same
Technical Field
The present invention relates to a display device and a method for manufacturing the same, and more particularly, to a micro light emitting diode display device and a method for manufacturing the same.
Background
Because of the extremely small size of the micro light emitting diode, the current method for manufacturing the micro light emitting diode display device adopts a Mass Transfer (Mass Transfer) technology, that is, a micro light emitting diode bare chip is taken and put by using a micro electro mechanical array technology, so that a large number of micro light emitting diode bare chips are carried onto a driving substrate with a pixel circuit at one time. Various new mass transfer techniques are being developed, and laser transfer techniques are favored for efficiency.
The laser transfer technology realizes the separation of the bare chips through the photo-substance reaction of the laser and the connecting material, and the impact force or driving force generated at the same time can separate the bare chips and push the bare chips to transfer towards the target substrate. However, when the photo-material reaction occurs, the direction in which the die is detached is not fixed due to uneven distribution of impact force or driving force, resulting in that the die cannot be accurately transferred onto the target substrate.
Disclosure of Invention
The invention provides a display device having a light emitting element that is accurately transferred.
The invention provides a manufacturing method of a display device, which can accurately transfer a light-emitting element.
An embodiment of the present invention proposes a display device including: a circuit substrate; and the light-emitting element is electrically connected with the circuit substrate and is provided with an opening, wherein the opening is positioned at one side of the light-emitting element, which is close to or far from the circuit substrate.
In an embodiment of the invention, the orthographic projection of the opening on the circuit substrate overlaps the orthographic projection of the center of gravity of the light emitting element on the circuit substrate.
In an embodiment of the invention, the light emitting element includes two electrodes, and the opening is at least partially located outside the two electrodes.
In an embodiment of the invention, the light emitting element includes two electrodes, and the opening is located between the two electrodes.
In an embodiment of the invention, the opening is located on a light emitting surface or a non-light emitting surface of the light emitting element.
In an embodiment of the invention, the opening penetrates through the light emitting element.
In an embodiment of the invention, a cross section of the opening has a positive trapezoid or an inverted trapezoid.
In an embodiment of the invention, the opening has a lateral blind hole therein.
In an embodiment of the invention, a caliber of the opening is less than 1/3 of a width of the light emitting element.
In an embodiment of the invention, a caliber of the opening is less than or equal to 3 μm.
In an embodiment of the invention, a depth of the opening is greater than or equal to 1 μm.
In an embodiment of the invention, the circuit substrate includes an active device array.
In an embodiment of the invention, the display device further includes a connection post, and the connection post is at least partially located in the opening.
In an embodiment of the invention, the connection post includes a plurality of layers, and the plurality of layers have different concentrations, light absorptivity or light transmissivity.
An embodiment of the present invention provides a method for manufacturing a display device, including: providing a light-emitting element, wherein the light-emitting element is positioned on a first carrier plate; forming an opening on the surface of the light-emitting element far away from the first carrier plate; forming a connecting layer on the surface, and filling the connecting layer into the opening; fixing the second carrier plate on the connecting layer, so that the light-emitting element is positioned between the first carrier plate and the second carrier plate; removing the first carrier plate; removing the connecting layer, and reserving the connecting layer between the opening and the second carrier to form connecting columns; providing a third carrier plate, and aligning the light-emitting element with the third carrier plate, wherein the light-emitting element is positioned between the second carrier plate and the third carrier plate; and focusing the laser beam on the connecting column to separate the light emitting element from the second carrier plate, so that the light emitting element is transferred to the third carrier plate.
In an embodiment of the invention, the opening is located on a light emitting surface or a non-light emitting surface of the light emitting element.
In an embodiment of the invention, the front projection of the opening on the surface overlaps the front projection of the center of gravity of the light emitting element on the surface.
In an embodiment of the invention, the opening penetrates through the light emitting element.
In an embodiment of the invention, the third carrier is a circuit substrate.
In an embodiment of the invention, the connection layer includes a plurality of layers, and the plurality of layers have different concentrations, light absorptivity or light transmissivity.
Drawings
In order to make the above features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 1A to 1I are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 10 according to an embodiment of the invention.
Fig. 2A to 2G are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 20 according to an embodiment of the invention.
Fig. 3A to 3H are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 30 according to an embodiment of the invention.
Fig. 4A to 4G are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 40 according to an embodiment of the invention.
Symbol description
10. 20, 30, 40: display device
110: source substrate
120. 220, 320, 420: light-emitting element
121. 321, 421: first type semiconductor layer
121a, 321a, 421a: electrode
121b: connecting pad
121c, 421c: connecting wire
121S: surface of the body
122. 322, 422: second type semiconductor layer
122a, 322a, 422a: electrode
122b: connecting pad
122c: connecting wire
123. 323, 423: light-emitting layer
130. 330, 340: adhesive layer
150. 350, 450: connection layer
150a, 350a, 450a: connecting column
170: circuit substrate
170a, 170b: connecting pad
171: bottom plate
172: element layer
180: laser device
351. 351a, 451a: first layer
352. 352a, 452a: second layer
353. 353a, 453a: third layer
454. 454a: fourth layer
B1, B2, B3, B4: lateral blind hole
BP: bottom part
C1, C2, C3, C4, C5, C6, C7: carrier plate
D1: spacing of
Da: caliber of
Dt: depth of
IS: insulating layer
LB: laser beam
NP: neck portion
O1, O2, O3, O4: an opening
T: active (active) element
W: width of (L)
Detailed Description
Fig. 1A to 1I are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 10 according to an embodiment of the invention. First, referring to fig. 1A, a light emitting device 120 is provided and grown on a source substrate 110, wherein the light emitting device 120 includes a first type semiconductor layer 121, a second type semiconductor layer 122, a light emitting layer 123 between the first type semiconductor layer 121 and the second type semiconductor layer 122, and a plurality of electrodes 121A and 122a electrically connected to the first type semiconductor layer 121 and the second type semiconductor layer 122, respectively. In the present embodiment, the plurality of electrodes 121a, 122a are located on the same side of the first type semiconductor layer 121. That is, the LED device 120 is a horizontal micro LED.
In this embodiment, the bonding pads 121b and 122b are formed on the electrodes 121a and 122a, respectively, wherein the bonding pad 121b is electrically connected to the electrode 121a, the bonding pad 122b is electrically connected to the electrode 122a, and the top surface of the bonding pad 121b is aligned with the top surface of the bonding pad 122b, but not limited thereto. The material of the pads 121b, 122b is metal, but the present invention is not limited thereto. In other embodiments, other conductive materials may be used for the pads 121b, 122b, such as: alloys, nitrides of metallic materials, oxides of metallic materials, oxynitrides of metallic materials, graphene, stacked layers of metallic materials, or stacked layers of other conductive materials.
Next, referring to fig. 1B, a carrier C1 coated with an adhesive layer 130 is provided, and the light emitting device 120 is attached to the adhesive layer 130, where the light emitting device 120 may be located between the source substrate 110 and the carrier C1. Subsequently, the source substrate 110 is removed, and the first type semiconductor layer 121 is exposed away from the surface 121S of the carrier C1. The source substrate 110 may be removed by, for example, a Laser Lift Off (Laser Lift Off) process, but the invention is not limited thereto.
Next, referring to fig. 1C, an opening O1 is formed on the surface 121S of the first type semiconductor layer 121. In this embodiment, the opening O1 may be completely located in the first type semiconductor layer 121 and may be located on the light emitting surface of the light emitting element 120. In addition, the front projection of the opening O1 on the surface 121S may overlap the front projection of the center of gravity of the light emitting element 120 on the surface 121S, but the invention is not limited thereto. In the present embodiment, the cross section of the opening O1 may take the shape of a right trapezoid with a narrow upper part and a wide lower part, but the present invention is not limited thereto. In some embodiments, the opening O1 may also extend downward to penetrate the first type semiconductor layer 121 or deeper. The opening O1 may be formed by a photolithographic etching process. For example, in the present embodiment, the opening O1 having a positive trapezoid cross section may be manufactured by a dry etching process in combination with a wet etching process.
Next, referring to fig. 1D, a connection layer 150 is formed on the light emitting device 120 and the adhesive layer 130, and the connection layer 150 is filled into the opening O1. The material of the connection layer 150 is a material that can be decomposed (e.g., ablated) by reaction with a laser. In the present embodiment, the connection layer 150 may have an adhesive property, but the present invention is not limited thereto. In some embodiments, when the connection layer 150 is not adhesive, an adhesive layer may be formed on the connection layer 150.
Next, referring to fig. 1E, a carrier C2 is attached to the connection layer 150, and the light emitting device 120 is located between the carrier C1 and the carrier C2. Afterwards, the carrier C1 is removed. The carrier C1 may be removed by heating, but the invention is not limited thereto.
Next, referring to fig. 1F, the adhesion layer 130 is removed to expose the pads 121b and 122b. The adhesion layer 130 may be removed by wet etching, but the invention is not limited thereto.
Next, referring to fig. 1G, most of the connection layer 150 is removed, but a portion of the connection layer 150 between the opening O1 and the carrier C2 remains, so as to form a connection pillar 150a, and the connection pillar 150a is at least partially located in the opening O1. The connection layer 150 may be removed by wet etching, but the invention is not limited thereto.
Next, referring to fig. 1H, a circuit substrate 170 is provided, and the circuit substrate 170 may include a plurality of pads 170a and 170b, and the light emitting device 120 is aligned with the circuit substrate 170, so that the light emitting device 120 is located between the carrier C2 and the circuit substrate 170. Specifically, in the present embodiment, the bonding pads 121b and 122b of the light emitting element 120 are aligned with the bonding pads 170a and 170b of the circuit substrate 170, but the present invention is not limited thereto, and other suitable alignment methods may be used.
After that, the laser beam LB from the laser 180 is focused on the connection post 150a. Specifically, the connection post 150a may include a neck portion NP located outside the opening O1 and a bottom portion BP located inside the opening O1. In the present embodiment, the laser beam LB can be focused on the neck portion NP of the connection post 150a, such that the neck portion NP of the connection post 150a reacts with the laser beam LB to be decomposed, and the bottom portion BP of the connection post 150a can remain in the opening O1. When the neck portion NP of the connection post 150a breaks down, the light emitting device 120 can drop vertically downward in a manner similar to a free fall, and is accurately transferred onto the circuit substrate 170, so that the pads 121b and 122b can contact the pads 170a and 170b, respectively, as shown in fig. 1I. At this time, in the formed display device 10, the electrodes 121a, 122a of the light emitting element 120 may be located between the first type semiconductor layer 121 and the circuit substrate 170.
In some embodiments, the laser beam LB may be focused on the bottom BP of the connection post 150a, such that the bottom BP of the connection post 150a reacts with the laser beam LB to generate an impact force or driving force. In detail, the lateral impact force or driving force generated by the reaction between the bottom BP of the connection post 150a and the laser beam LB may cancel each other out by acting on the sidewall of the opening O1, such that the net impact force or driving force is a resultant force of the longitudinal direction and the downward direction. The resultant downward force can accurately transfer the light emitting element 120 to the circuit board 170 by advancing the light emitting element directly downward, and the bonding pads 121b and 122b can be respectively bonded to the bonding pads 170a and 170b.
In some embodiments, the foregoing steps may be followed by electrically connecting the pad 121b of the light emitting device 120 with the pad 170a of the circuit substrate 170, and electrically connecting the pad 122b of the light emitting device 120 with the pad 170b of the circuit substrate 170. The method of electrically connecting the bonding pad 121b and the bonding pad 170a and the bonding pad 122b and the bonding pad 170b may be eutectic bonding or other similar methods, but the invention is not limited thereto.
Referring to fig. 1I, in the present embodiment, the display device 10 includes a circuit substrate 170 and a light emitting element 120. The light emitting element 120 is electrically connected to the circuit substrate 170, and has an opening O1, where the opening O1 is located at a side of the light emitting element 120 away from the circuit substrate 170. The opening O1 of the light emitting element 120 is used to adjust the action range of the laser beam during the laser transfer process, so that the light emitting element 120 can be accurately transferred onto the circuit substrate 170, and the display device 10 has an array of light emitting elements 120 with accurate mass transfer.
In some embodiments, the circuit substrate 170 may include a bottom plate 171, an element layer 172, and a plurality of pads 170a, 170b. A device layer 172 including an array of active devices T (e.g., a thin film transistor array) may be formed on the bottom plate 171 using a thin film deposition process, a photomask process, and an etching process. After the element layer 172 is formed, a thin film deposition process, a photomask process, and an etching process may be continuously used to form the plurality of electrodes 170a, 170b on the element layer 172.
The position of the opening O1 in the light emitting element 120 is not particularly limited. In the display device 10, the front projection of the opening O1 on the circuit substrate 170 may overlap the front projection of the center of gravity of the light emitting element 120 on the circuit substrate 170, but the invention is not limited thereto. Specifically, the center of gravity position of the light emitting element 120 can be obtained by calculating the area and density distribution of each layer of the light emitting element 120. By overlapping the orthographic projection of the opening O1 on the circuit substrate 170 with the orthographic projection of the center of gravity of the light emitting element 120 on the circuit substrate 170, the light emitting element 120 can be kept in a desired balance when the light emitting element 120 is suspended on the carrier C2 by the connection post 150a, as shown in fig. 1H.
The shape of the opening O1 is not particularly limited. In the present embodiment, the cross section of the opening O1 has a regular trapezoid shape with a narrow top and a wide bottom, but the present invention is not limited thereto. In some embodiments, the cross section of the opening O1 may also have an inverted trapezoid with a wider upper portion and a narrower lower portion. In other embodiments, the cross-section of the opening O1 may be given a spike-like profile by further forming lateral blind holes in the opening O1.
The size of the opening O1 may be as small as possible so as not to affect the optical properties and the electrical properties of the light emitting device 120, but the invention is not limited thereto. In the present embodiment, the aperture Da of the opening O1 may be smaller than 1/3 of the width W of the light emitting device 120, i.e., da <1/3W. In some embodiments, the aperture Da of the opening O1 may be less than or equal to 3 μm, e.g., 3 μm, 2 μm, or 1.5 μm, with an appropriate aperture Da being selected as desired.
The opening O1 may have a sufficient depth to, for example, ensure that the net impact force or driving force generated by the reaction of the connecting post 150a with the laser beam LB is a downward directed force. In some embodiments, the depth Dt of the opening O1 may be greater than or equal to 1 μm, for example, the depth Dt is 1 μm, 2 μm or 3 μm or more, but the invention is not limited thereto. In some embodiments, a portion of the connection post 150a may remain in the opening O1.
Fig. 2A to 2G are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 20 according to an embodiment of the invention. The reference numerals and the related contents of the elements of the embodiment of fig. 1A to 1I are used hereinafter, wherein the same reference numerals are used to designate the same or similar elements, and the description of the same technical contents is omitted. Regarding the description of the omitted parts, reference may be made to the embodiments of fig. 1A to 1I, and the description will not be repeated.
First, referring to fig. 2A, a light emitting device 220 is provided and grown on a source substrate 110, wherein the light emitting device 220 includes a first type semiconductor layer 121, a second type semiconductor layer 122, a light emitting layer 123 disposed between the first type semiconductor layer 121 and the second type semiconductor layer 122, and a plurality of electrodes 121a and 122A electrically connected to the first type semiconductor layer 121 and the second type semiconductor layer 122, respectively.
Next, referring to fig. 2B, an opening O2 is formed in the electrode 122a and the second type semiconductor layer 122. In the present embodiment, the opening O2 is located in the electrode 122a and the second type semiconductor layer 122, but the invention is not limited thereto. In some embodiments, the opening O2 may also penetrate through the light emitting layer 123 and extend to the first type semiconductor layer 121.
In this embodiment, at least 2 lateral blind holes may be further formed in the opening O2, so that the opening O2 has a burr-like shape, thereby improving the supporting force of the connection post 150a formed in the opening O2, and further improving the stability of the connection post 150a when the light-emitting element 220 is suspended. For example, lateral blind holes B1, B2, B3, B4 may be formed in the opening O2, but the invention is not limited thereto.
The formation of the burr-like opening O2 may be achieved using a multi-pass etching process. For example, in the present embodiment, two etching processes may be first used to form the main portion of the opening O2, wherein the two etching processes respectively use etchants capable of selectively etching the electrode 122a and the second semiconductor layer 122. Thereafter, the lateral blind holes B1, B2 may be formed using an etchant having selectivity to a specific lattice orientation of the electrode 122a, and then the lateral blind holes B3, B4 may be formed using an etchant having selectivity to a specific lattice orientation of the second type semiconductor layer 122. In other embodiments, an etchant selective to a specific material may be sequentially selected to form the openings O2 with various shapes according to practical requirements.
Next, referring to fig. 2C, a connection layer 150 is formed on the light emitting device 220 and the source substrate 110, and the connection layer 150 is filled into the opening O2.
Next, referring to fig. 2D, a carrier C3 is attached to the connection layer 150, and the light emitting device 220 is located between the source substrate 110 and the carrier C3, and then the source substrate 110 is removed. The source substrate 110 may be removed by laser lift-off, but the invention is not limited thereto.
Next, referring to fig. 2E, most of the connection layer 150 is removed, but a portion of the connection layer 150 between the opening O2 and the carrier C3 remains, so as to form a connection pillar 150a, and the connection pillar 150a fills the opening O2 to have a spike-shaped cross-section. In this way, the burr-shaped connection post 150a can have an increased supporting force to stably suspend the light emitting element 220. In the present embodiment, the connection layer 150 is removed by, for example, wet etching, but the invention is not limited thereto.
Next, referring to fig. 2F, a circuit substrate 170 is provided, and the circuit substrate 170 may include a plurality of pads 170a, 170b on a surface thereof. The light emitting element 220 is aligned with the circuit substrate 170 such that the light emitting element 220 is located between the carrier C3 and the circuit substrate 170, and the orthographic projection of the light emitting element 220 on the circuit substrate 170 is located between the pads 170a, 170b of the circuit substrate 170. Then, the laser beam LB emitted from the laser 180 is focused on the bottom BP of the connection post 150a, so that the light emitting element 220 is precisely transferred onto the circuit substrate 170 while advancing directly downward.
Next, referring to fig. 2G, connection wires 121c and 122c are formed, wherein the connection wire 121c connects the electrode 121a of the light emitting element 220 and the pad 170a of the circuit substrate 170, and the connection wire 122c connects the electrode 122a of the light emitting element 220 and the pad 170b of the circuit substrate 170, so as to complete the display device 20 of the embodiment.
The display device 20 shown in fig. 2G is different from the display device 10 shown in fig. 1I in that: in the display device 20, the opening O2 has a burr-like shape and is located on the non-light-emitting surface of the light-emitting element 220, the first semiconductor layer 121 of the light-emitting element 220 is located between the electrodes 121a and 122a and the circuit substrate 170, and the electrodes 121a and 122a of the light-emitting element 220 are connected to the pads 170a and 170b of the circuit substrate 170 through the connection wires 121c and 122c, respectively.
Fig. 3A to 3H are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 30 according to an embodiment of the invention. The reference numerals and the related contents of the elements of the embodiment of fig. 1A to 1I are used hereinafter, wherein the same reference numerals are used to designate the same or similar elements, and the description of the same technical contents is omitted. Regarding the description of the omitted parts, reference may be made to the embodiments of fig. 1A to 1I, and the description will not be repeated.
First, referring to fig. 3A, a light emitting device 320 is provided and grown on a source substrate 110, wherein the light emitting device 320 includes a first type semiconductor layer 321, a second type semiconductor layer 322, a light emitting layer 323 between the first type semiconductor layer 321 and the second type semiconductor layer 322, and a plurality of electrodes 321a and 322a electrically connected to the first type semiconductor layer 321 and the second type semiconductor layer 322, respectively. In this embodiment, the light emitting diode element 320 may be a Flip-chip (Flip-chip) micro light emitting diode.
Next, referring to fig. 3B, a carrier C4 coated with an adhesive layer 330 is provided, and the first type semiconductor layer 321 of the light emitting device 320 is attached to the adhesive layer 330, where the light emitting device 320 may be located between the source substrate 110 and the carrier C4. Subsequently, the source substrate 110 is removed to expose the electrodes 321a, 322a of the light emitting element 320, and the electrodes 321a, 322a have an opening O3 therebetween. The source substrate 110 may be removed by, for example, a Laser Lift Off (Laser Lift Off) process, but the invention is not limited thereto.
Next, referring to fig. 3C, a connection layer 350 is formed on the light emitting element 320 and the adhesive layer 330, and the connection layer 350 fills the opening O3 between the electrodes 321a and 322a. In this embodiment, the connection layer 350 may include a plurality of layers. For example, the connection layer 350 may include a first layer 351, a second layer 352 and a third layer 353, wherein the second layer 352 is located between the first layer 351 and the third layer 353, but the invention is not limited thereto. In this embodiment, the first layer 351, the second layer 352 and the third layer 353 may have sequentially increasing light transmittance with respect to the laser beam LB used subsequently. In some embodiments, the first layer 351, the second layer 352, and the third layer 353 may have sequentially decreasing light transmittance relative to the subsequently used laser beam LB. In some embodiments, the first layer 351, the second layer 352, and the third layer 353 may have light absorptances that are sequentially increased and decreased relative to the subsequently used laser beam LB. In some embodiments, the first layer 351, the second layer 352, and the third layer 353 may have light absorptances that decrease first and then increase with respect to the subsequently used laser beam LB. In some embodiments, the first layer 351, the second layer 352, and the third layer 353 may also include a laser absorbing material, and the concentration of the laser absorbing material in the first layer 351, the second layer 352, and the third layer 353 may be sequentially increased, sequentially decreased, or sequentially decreased.
The material of the connection layer 350 is a material that can be decomposed by a reaction with laser light. The connection layer 350 may have an adhesive property, but the present invention is not limited thereto. In some embodiments, when the third layer 353 of the connection layer 350 is not adhesive, an adhesive layer may be formed on the third layer 353.
Next, referring to fig. 3D, a carrier C5 is attached to the connection layer 350, and the light emitting device 320 is located between the carrier C5 and the carrier C4, and then the carrier C4 is removed. In some embodiments, the carrier C4 is removed and the adhesive layer 330 is removed. The carrier C4 and the adhesive layer 330 may be removed by heating, but the invention is not limited thereto.
Next, referring to fig. 3E, most of the connection layer 350 is removed, but a portion of the connection layer 350 between the opening O3 and the carrier C5 remains, so as to form a connection post 350a, wherein the connection post 350a includes a first layer 351a, a second layer 352a and a third layer 353a, and the connection post 350a is at least partially located in the opening O3. In this embodiment, the first layer 351a, the second layer 352a, and the third layer 353a may have sequentially increasing light transmittance with respect to the laser beam LB.
In some embodiments, the first layer 351a, the second layer 352a, and the third layer 353a may have sequentially decreasing light transmittance relative to the laser beam LB. In some embodiments, the first layer 351a, the second layer 352a, and the third layer 353a may have an increasing and decreasing light absorption relative to the laser beam LB. In some embodiments, the first layer 351a, the second layer 352a, and the third layer 353a may have progressively decreasing light absorption relative to the laser beam LB. In some embodiments, the first layer 351a, the second layer 352a, and the third layer 353a may also include a laser absorbing material, and the concentration of the laser absorbing material in the first layer 351a, the second layer 352a, and the third layer 353a may be sequentially increased, sequentially decreased, or sequentially decreased. By the increasing or decreasing light transmittance, light absorptivity or laser absorbing material concentration, the breaking position of the connecting post 350a after the reaction with the laser beam LB can be controlled, so as to optimize the mass transfer of the light emitting element 320.
In some embodiments, when viewing the light emitting element 320 from the carrier plate C5 toward the direction of the light emitting element 320, the distance D1 between the electrodes 321a, 322a may be smaller than the length of the electrodes 321a, 322a in the direction perpendicular to the distance D1, at this time, the opening O3 may be a long groove between the electrodes 321a, 322a, so that the connection post 350a has an elongated shape in plan view, in which case, the connection post 350a in the middle of the opening O3 may be left, and the connection post 350a in the remaining part of the opening O3 may be completely removed, so that the connection post 350a has an approximately cylindrical shape.
Next, referring to fig. 3F, a carrier C6 is provided, and an adhesive layer 340 is coated on one surface of the carrier C6, and the light emitting element 320 is disposed above the adhesive layer 340, such that the light emitting element 320 is located between the carrier C6 and the carrier C5. Then, the laser beam LB emitted by the laser 180 is focused on the first layer 351a of the connection post 350a, so that the first layer 351a of the connection post 350a reacts with the laser beam LB to generate a downward net impact force or driving force, and the light emitting element 320 is moved directly downward to the carrier C6, as shown in fig. 3G. In the present embodiment, since the third layer 353a and the second layer 352a have a higher light transmittance than the first layer 351a, a relatively larger portion of the laser beam LB can penetrate the third layer 353a and the second layer 352a to reach the first layer 351a, thereby improving the light utilization of the laser beam LB on the first layer 351 a.
Next, referring to fig. 3H, a circuit substrate 170 is provided, and the circuit substrate 170 may include a plurality of pads 170a, 170b. Then, the light emitting element 320 is disposed on the circuit substrate 170, and the electrodes 321a and 322a of the light emitting element 320 are respectively abutted against the pads 170a and 170b of the circuit substrate 170.
In some embodiments, the foregoing steps may be followed by connecting the electrode 321a of the light emitting device 320 with the pad 170a of the circuit substrate 170, and electrically connecting the electrode 322a of the light emitting device 320 with the pad 170b of the circuit substrate 170. The method of electrically connecting the electrode 321a and the pad 170a and the method of electrically connecting the electrode 322a and the pad 170b include eutectic bonding or other similar methods, but the invention is not limited thereto.
The display device 30 shown in fig. 3H is different from the display device 10 shown in fig. 1I in that: in the display device 30, the opening O3 is located at a side of the light emitting element 320 adjacent to the circuit substrate 170, the opening O3 is a space between the electrodes 321a and 322a, so that the opening O3 is formed without using a photolithography process, and the opening O3 is located on a non-light-emitting surface of the light emitting element 320.
Fig. 4A to 4G are schematic cross-sectional views illustrating a step flow of a method for manufacturing a display device 40 according to an embodiment of the invention. The reference numerals and the related contents of the elements of the embodiment of fig. 2A to 2G are used hereinafter, wherein the same reference numerals are used to designate the same or similar elements, and the description of the same technical contents is omitted. Regarding the description of the omitted parts, reference may be made to the embodiments of fig. 2A to 2G, and the description will not be repeated.
First, referring to fig. 4A, a light emitting device 420 grown on a source substrate 110 is provided, wherein the light emitting device 420 includes a first type semiconductor layer 421, a second type semiconductor layer 422, a light emitting layer 423 located between the first type semiconductor layer 421 and the second type semiconductor layer 422, and a plurality of electrodes 421a and 422a electrically connected to the first type semiconductor layer 421 and the second type semiconductor layer 422, respectively. In this embodiment, the plurality of electrodes 421a and 422a are respectively located on opposite sides of the light emitting layer 423. That is, the light emitting element 420 is a Vertical micro light emitting diode.
Next, referring to fig. 4B, an opening O4 is formed in the electrode 421a, the first type semiconductor layer 421, the light-emitting layer 423, the second type semiconductor layer 422, and the electrode 422a. In the present embodiment, the opening O4 penetrates the respective layers of the light emitting element 420 to have a deeper depth. In this way, the supporting force of the connecting post 450a formed in the opening O4 to the light emitting device 420 can be increased, so as to improve the stability of the connecting post 450a when suspending the light emitting device 420. The opening O4 may be formed by a multi-etching process, and an etchant selective to each layer of the light emitting element 420 may be sequentially selected to form the opening O4 according to actual requirements.
Next, referring to fig. 4C, a connection layer 450 is formed on the light emitting device 420 and the source substrate 110, and the connection layer 450 is filled into the opening O4. In this embodiment, the connection layer 450 may be formed by sequentially forming the first layer 451, the second layer 452, the third layer 453, and the fourth layer 454, wherein the light absorption rate of the third layer 453 is greater than the light absorption rate of the fourth layer 454, the light absorption rate of the fourth layer 454 is greater than the light absorption rate of the second layer 452, and the light absorption rate of the second layer 452 is greater than the light absorption rate of the first layer 451. At least the third layer 453 or the fourth layer 454 in the connection layer 450 is a material that can be decomposed by a reaction with laser light.
In the present embodiment, the connection layer 450 may completely fill the opening O4, but the invention is not limited thereto. In some embodiments, the connection layer 450 may also fill in the partial opening O4. The fourth layer 454 of the connection layer 450 may have an adhesive property, but the present invention is not limited thereto. In some embodiments, when the fourth layer 454 of the connection layer 450 is not tacky, an adhesive layer may be formed on the fourth layer 454.
Next, referring to fig. 4D, a carrier C7 is attached to the connection layer 450, and the light emitting device 420 is located between the source substrate 110 and the carrier C7, and then the source substrate 110 is removed.
Next, referring to fig. 4E, most of the connection layer 450 is removed, but a portion of the connection layer 450 between the opening O4 and the carrier C7 remains, so as to form a connection post 450a, wherein the connection post 450a includes a first layer 451a, a second layer 452a, a third layer 453a, and a fourth layer 454a.
Next, referring to fig. 4F, a circuit substrate 170 is provided, and the circuit substrate 170 may include a plurality of pads 170a, 170b on a surface thereof. Then, the light emitting element 420 is aligned with the circuit substrate 170, such that the light emitting element 420 is located between the carrier C7 and the circuit substrate 170, and the front projection of the light emitting element 420 on the circuit substrate 170 overlaps the pad 170b of the circuit substrate 170. After that, the laser beam LB emitted from the laser 180 is focused on the third layer 453a of the connection post 450a, so that the third layer 453a is burned, for example, so that the light emitting element 420 can drop down directly to be transferred onto the circuit substrate 170, and the electrode 422a of the light emitting element 420 is brought into direct contact with the pad 170b. Since the third layer 453a of the connection column 450a has the maximum light absorption rate in the connection column 450a, the laser beam LB may easily decompose the third layer 453a by reaction with the third layer 453a.
In some embodiments, the foregoing steps may be followed by electrically connecting the electrode 422a of the light emitting device 420 and the pad 170b of the circuit substrate 170. The method of electrically connecting the electrode 422a of the light emitting device 420 and the pad 170b of the circuit substrate 170 includes, for example, eutectic bonding or other similar methods, but the invention is not limited thereto.
Next, referring to fig. 4G, an insulating layer IS may be formed on a side of the electrode 422a and the pad 170b near the pad 170a, and then a connection wire 421c IS formed, so as to complete the display device 40 of the embodiment. In the present embodiment, the connection wire 421c connects the electrode 421a of the light emitting device 420 and the pad 170a of the circuit substrate 170, and the insulating layer IS can prevent the short circuit between the electrode 421c and the electrode 422a or the pad 170b.
The display device 40 shown in fig. 4G is different from the display device 20 shown in fig. 2G in that: in the display device 40, the light emitting element 420 is a vertical micro light emitting diode; the opening O4 penetrates the electrode 421a of the light emitting element 420, the first type semiconductor layer 421, the light emitting layer 423, the second type semiconductor layer 422, and the electrode 422a without a lateral blind hole; and the connection post 450a includes multiple layers. In addition, the electrode 421a of the light emitting element 420 is connected to the pad 170a of the circuit substrate 170 through the connection wire 421c, and the electrode 422a of the light emitting element 420 is directly connected to the pad 170b of the circuit substrate 170.
In summary, in the display device according to the embodiment of the invention, the opening in the light emitting element is used to adjust the action range of the laser beam in the laser transfer process, so that the light emitting element can be accurately transferred onto the circuit substrate, and the display device has an accurate light emitting element array with a large transfer amount.
Although the present invention has been described with reference to the above embodiments, it should be understood by those skilled in the art that the present invention is not limited thereto, and that various changes and modifications can be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (19)

1. A display device, comprising:
a circuit substrate;
the light-emitting element is electrically connected with the circuit substrate and is provided with an opening, wherein the opening is positioned at one side of the light-emitting element, which is close to or far from the circuit substrate; and
and a connection portion in the opening, wherein a material of the connection portion is a material that can be decomposed by a reaction with a laser, and the connection portion is a portion remaining in the opening after a connection post reacts with a laser beam during a laser transfer, the connection post has a first sidewall located outside the opening and a second sidewall located inside the opening, the first sidewall is not parallel to the side of the light emitting element adjacent to or away from the circuit substrate, and the first sidewall and the second sidewall are aligned with and directly connected to each other at the side of the light emitting element adjacent to or away from the circuit substrate.
2. The display device of claim 1, wherein a front projection of the opening to the circuit substrate overlaps a front projection of a center of gravity of the light emitting element to the circuit substrate.
3. The display device according to claim 1, wherein the light-emitting element includes two electrodes, and the opening is located at least partially outside the two electrodes.
4. The display device according to claim 1, wherein the light-emitting element includes two electrodes, and wherein the opening is located between the two electrodes.
5. The display device of claim 1, wherein the opening is located on a light-emitting surface or a non-light-emitting surface of the light-emitting element.
6. The display device of claim 1, wherein the opening extends through the light emitting element.
7. The display device of claim 1, wherein a cross section of the opening has a positive trapezoid or an inverted trapezoid.
8. The display device of claim 1, wherein the opening has a lateral blind hole therein.
9. The display device according to claim 1, wherein a caliber of the opening is smaller than 1/3 of a width of the light emitting element.
10. The display device according to claim 1, wherein the aperture is less than or equal to 3 μm in diameter.
11. The display device according to claim 1, wherein a depth of the opening is greater than or equal to 1 μm.
12. The display device of claim 1, wherein the circuit substrate comprises an array of active elements.
13. The display device of claim 1, wherein the connection post comprises a plurality of layers, and the plurality of layers have different concentrations, light absorptivity, or light transmissivity.
14. A method of manufacturing a display device, comprising:
providing a light-emitting element, wherein the light-emitting element is positioned on a first carrier plate;
forming an opening on a surface of the light-emitting element away from the first carrier plate;
forming a connection layer on the surface, wherein the connection layer is filled into the opening;
fixing a second carrier plate on the connecting layer, so that the light-emitting element is positioned between the first carrier plate and the second carrier plate;
removing the first carrier plate;
removing the connecting layer, and reserving the connecting layer between the opening and the second carrier plate to form connecting columns;
providing a third carrier plate, and aligning the light-emitting element with the third carrier plate, wherein the light-emitting element is positioned between the second carrier plate and the third carrier plate; and
focusing the laser beam on the connecting column to separate the light-emitting element from the second carrier, so that the light-emitting element is transferred to the third carrier.
15. The method of claim 14, wherein the opening is located on a light-emitting surface or a non-light-emitting surface of the light-emitting element.
16. The method of claim 14, wherein the orthographic projection of the opening on the surface overlaps the orthographic projection of the center of gravity of the light emitting element on the surface.
17. The manufacturing method of a display device according to claim 14, wherein the opening penetrates the light-emitting element.
18. The method of claim 14, wherein the third carrier is a circuit substrate.
19. The method for manufacturing a display device according to claim 14, wherein the connection layer comprises a plurality of layers, and wherein the plurality of layers have different concentrations, light absorptivity, or light transmissivity.
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