Method for preparing full-color micro-LED display device based on wafer bonding

Abstract

The invention belongs to the technical field of display devices, and relates to a full-color micro-LED display device preparation method based on wafer bonding, and the method comprises the steps: preparing at least one micro-LED wafer which comprises a micro-LED corresponding to the arrangement position of a part of or all pixels of a driving substrate; the color of the micro-LEDs on the same micro-LED wafer is the same as that of the micro-LEDs on the same micro-LED wafer; preparing a bonding structure on the electrode of the micro-LED and the electrode of the pixel, wherein the arrangement positions of the electrodes correspond to each other; and bonding the micro-LEDs on the micro-LED wafers with the pixels on the driving substrate, and stripping the micro-LEDs from the micro-LED wafers, so that the micro-LEDs on the micro-LED wafers and the pixels on the driving substrate are separated from each other. By preparing the chip matched with the pixel parameter of the driving substrate, the chip on the wafer can be directly bonded to the driving substrate, and a huge transfer process of COC (Chip On Chip) is not needed. Compared with the existing mass transfer and bonding process, the method has the advantages that the dependence on large-scale and high-cost equipment is reduced, the RGB three primary colors can be directly obtained, the intrinsic color conversion is carried out, and the production cost of the micro-LED is reduced.

Description

Technical Field

[0001] This disclosure belongs to the field of display device technology and relates to a method for fabricating a full-color micro-LED display device based on wafer bonding. Background Technology

[0002] As a crucial component of human-computer interaction and information presentation, display technology is constantly evolving and developing, driven by continuous technological advancements and ever-increasing demands. Currently, mainstream display technologies include liquid crystal display (LCD), organic light-emitting diode (OLED), micro-LED, and quantum dot technologies.

[0003] Among them, micro-LED display technology, as an emerging display technology, uses micron-sized LED chips and has outstanding characteristics such as high brightness, high contrast, and fast response. Compared with other display technologies, micro-LED display technology performs better in terms of pixel density and color gamut, boasting higher pixel density and a wider color gamut.

[0004] Despite the significant advantages of micro-LED display technology, its industrialization still faces numerous challenges, such as chip miniaturization and arraying, mass chip transfer, full-color realization, bonding processes, testing, and repair. Among these challenges, mass transfer, full-color realization, and bonding processes, as core technologies of micro-LED, have a crucial impact on product quality, production efficiency, and cost control.

[0005] In existing technologies, when constructing a display array that combines micro-LEDs with circuit drivers, multiple mass transfer operations of micro-LED chips are required using a center carrier board (COC). The number of chips transferred each time is extremely large, especially when achieving RGB full-color display, where red (R), green (G), and blue (B) chips need to be transferred multiple times separately. This not only significantly increases the complexity and difficulty of the transfer process but also leads to reduced transfer yield and decreased production efficiency. Summary of the Invention

[0006] To overcome the above problems, this disclosure provides a method for fabricating a full-color micro-LED display device based on wafer bonding.

[0007] The technical solution disclosed herein is as follows: A method for fabricating a full-color micro-LED display device based on wafer bonding, comprising: Prepare at least one micro-LED wafer, which contains micro-LEDs corresponding to the pixel arrangement positions of a portion or all of the driving substrate; The micro-LEDs on the same micro-LED wafer are of the same color; Bonding structures are fabricated on the electrodes of the micro-LEDs and pixels corresponding to their arrangement positions; The micro-LEDs on each of the micro-LED wafers are bonded to pixels on the driving substrate, and the micro-LEDs are peeled off from the micro-LED wafers.

[0008] Furthermore, the micro-LED wafer includes: A red micro-LED wafer on a GaAs substrate, which contains red micro-LEDs corresponding to the red pixel arrangement positions on the driving substrate; A green micro-LED wafer on a sapphire substrate, comprising green micro-LEDs corresponding to the green pixel arrangement positions on a driving substrate; and A blue micro-LED wafer on a sapphire substrate, which contains blue micro-LEDs corresponding to the blue pixel arrangement positions on the driving substrate; Further, the micro-LEDs on each of the micro-LED wafers are bonded to the pixels on the driving substrate, and the micro-LEDs are peeled off from the micro-LED wafers, specifically as follows: The red micro-LED wafer is bonded to the red pixel on the micro-LED and the driving substrate, and the red micro-LED is peeled off from the red micro-LED wafer; The green micro-LED wafer is bonded to the green pixels on the micro-LED and the driving substrate, and the green micro-LED is peeled off from the green micro-LED wafer; The blue micro-LED wafer is bonded to the blue pixels on the micro-LED and the driving substrate, and the blue micro-LED is peeled off from the blue micro-LED wafer.

[0009] Furthermore, the micro-LED wafer comprises multiple sets of chips, each set of chips containing multiple micro-LEDs, and the arrangement of the micro-LEDs in each set of chips is the same as the arrangement of a specific pixel on at least one driving substrate.

[0010] Furthermore, it also includes: After the micro-LED wafer is prepared, it is annealed to deposit an insulating or semiconductor film on the back side of the wafer substrate.

[0011] Furthermore, the bonding structure is a metal bump.

[0012] Furthermore, the material of the metal bump is one or more of ITO, graphene, copper, nickel, chromium, indium, tin, silver, gold, aluminum, tungsten, titanium, and platinum, or a mixture or alloy thereof.

[0013] Furthermore, the micro-LEDs are peeled off from the micro-LED wafer using lasers.

[0014] Furthermore, the driving substrate is one of TFT, CMOS, passive driving substrate, semi-active driving substrate, and two-dimensional transition metal sulfide TFT substrate.

[0015] Furthermore, the driving substrate and the micro-LED wafer are bonded using one or more of the following methods: thermo-press bonding, laser bonding, and chemical plating self-bonding.

[0016] This disclosure has the following beneficial effects: This disclosed method designs and fabricates chips that match the pixel parameters (size and spacing) of the driving substrate, enabling direct bonding of the chips from the wafer to the driving substrate without the need for a mass transfer process using a COC (intermediate carrier). Compared to existing mass transfer and bonding processes, the method provided in this disclosure is simpler, reduces reliance on large and costly equipment, and can directly obtain the RGB three primary colors and perform intrinsic color conversion, greatly improving display quality, reducing the production cost of micro-LEDs, and promoting industrialization.

[0017] The method disclosed herein utilizes a micro-LED wafer that is matched with a driving substrate. The micro-LED wafer can be bonded to different driving substrates multiple times, and the remaining chips can be used to repair defective chips on the driving substrate. This method greatly improves the utilization rate of micro-LEDs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the arrangement of red micro-LED wafer chips according to an embodiment of the present disclosure.

[0019] Figure 2 This is a schematic diagram of the green micro-LED wafer chip arrangement according to an embodiment of the present disclosure.

[0020] Figure 3 This is a schematic diagram of the blue micro-LED wafer chip arrangement according to an embodiment of the present disclosure.

[0021] Figure 4 This is a schematic diagram of the metal bumps on the driving substrate electrode according to an embodiment of this disclosure.

[0022] Figure 5This is a schematic diagram of the metal bumps on the red micro-LED electrode according to an embodiment of the present disclosure.

[0023] Figure 6 This is a schematic diagram of the metal bumps on the electrodes of blue and green micro-LEDs according to an embodiment of this disclosure.

[0024] Figure 7 This is a schematic diagram of the bonding method between the red micro-LED wafer and the driving substrate according to an embodiment of the present disclosure.

[0025] Figure 8 This is a schematic diagram of the bonding method between the green micro-LED wafer and the driving substrate according to an embodiment of the present disclosure.

[0026] Figure 9 This is a schematic diagram of the bonding method between the blue micro-LED wafer and the driving substrate according to an embodiment of the present disclosure.

[0027] Figure 10 This is a schematic diagram of the micro-LED wafer and the driving substrate after the first bonding according to an embodiment of the present disclosure.

[0028] Figure 11 This is a schematic diagram of the micro-LED wafer and the driving substrate after the second bonding according to an embodiment of the present disclosure.

[0029] Figure 12 This is a schematic diagram of the micro-LED wafer and the driving substrate after the third bonding according to an embodiment of the present disclosure.

[0030] Figure 13 This is a schematic diagram of the Nth bonding between the micro-LED wafer and the driving substrate according to an embodiment of this disclosure. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0032] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes. To keep the following description of the embodiments of this disclosure clear and concise, detailed descriptions of some known functions and components are omitted.

[0033] The present disclosure will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0034] This disclosure provides a method for fabricating a full-color micro-LED display device based on wafer bonding, including: Prepare at least one micro-LED wafer, which contains micro-LEDs corresponding to the pixel arrangement positions of a portion or all of the driving substrate; The micro-LEDs on the same micro-LED wafer are of the same color; Bonding structures are fabricated on the electrodes of the micro-LEDs and pixels corresponding to their arrangement positions; The micro-LEDs on each of the micro-LED wafers are bonded to pixels on the driving substrate, and the micro-LEDs are peeled off from the micro-LED wafers.

[0035] Using the above method, when bonding the micro-LED wafer to the driving substrate, a pixel located at the same position as the micro-LED, and where both the micro-LED and the pixel contain bonding structures, can be bonded. After peeling, the micro-LED remains on the driving substrate.

[0036] Multiple micro-LED wafers can be used to bond micro-LEDs of different colors to pixels on a driving substrate.

[0037] like Figure 1-3 As shown, in one embodiment of this disclosure, the micro-LED wafer includes: A red micro-LED wafer on a GaAs substrate, which contains red micro-LEDs corresponding to the red pixel arrangement positions on the driving substrate; A green micro-LED wafer on a sapphire substrate, comprising green micro-LEDs corresponding to the green pixel arrangement positions on a driving substrate; and A blue micro-LED wafer on a sapphire substrate, which contains blue micro-LEDs corresponding to the blue pixel arrangement positions on the driving substrate.

[0038] The core material of red LEDs is aluminum indium gallium phosphide (AlGaInP), whose lattice constant matches that of gallium arsenide (GaAs). This reduces dislocations and defects during epitaxial growth, improves crystal quality, and ensures luminous efficiency.

[0039] Blue and green LEDs are based on gallium nitride (GaN) materials, whose lattice constant mismatch with sapphire is approximately 13%. Despite the high mismatch, stress can be effectively alleviated by introducing buffer layers (such as AlN or GaN) and optimizing growth conditions, resulting in high-quality epitaxy. Therefore, sapphire is currently widely used in the industry as the growth substrate for blue and green LEDs.

[0040] In one specific embodiment, on the driving substrate, the lateral spacing 'a' and vertical spacing 'b' between red pixels are both 222 micrometers. At this time, the red micro-LED wafer contains red micro-LEDs arranged in the same manner, with the lateral spacing 'a' and vertical spacing 'b' also being 222 micrometers. The green and blue micro-LED wafers also satisfy this arrangement.

[0041] See Figure 7-8 As shown, in one embodiment of this disclosure, the micro-LEDs on each of the micro-LED wafers are bonded to pixels on the driving substrate, and the micro-LEDs are peeled off from the micro-LED wafers, specifically as follows: The red micro-LED wafer is bonded to the red pixel on the micro-LED and the driving substrate, and the red micro-LED is peeled off from the red micro-LED wafer; The green micro-LED wafer is bonded to the green pixels on the micro-LED and the driving substrate, and the green micro-LED is peeled off from the green micro-LED wafer; The blue micro-LED wafer is bonded to the blue pixels on the micro-LED and the driving substrate, and the blue micro-LED is peeled off from the blue micro-LED wafer.

[0042] In one embodiment of this disclosure, the micro-LED wafer includes multiple sets of chips, each set of chips includes multiple micro-LEDs, and the arrangement of the micro-LEDs in each set of chips is the same as the arrangement of a specific pixel on at least one driving substrate.

[0043] like Figure 10-13 As shown, a micro-LED wafer contains multiple sets of chips, and each set of chips contains multiple micro-LEDs. After the first bonding, the first set of chips is peeled off from the micro-LED wafer. After the second bonding, the second set of chips is peeled off from the micro-LED wafer, and so on.

[0044] This method allows for the simultaneous fabrication of multiple sets of chips for different driving substrates on a single micro-LED wafer. For example, a single red micro-LED wafer can be configured with four sets of chips, satisfying the bonding requirements of red LED chips on four driving substrates.

[0045] In one embodiment of this disclosure, it further includes: After the micro-LED wafer is prepared, it is annealed to deposit an insulating or semiconductor film on the back side of the wafer substrate.

[0046] like Figure 4-6 As shown, in one embodiment of this disclosure, the bonding structure is a metal bump. Figure 4 This is a schematic diagram of the electrode metal bumps for driving the pixel on the substrate. Figure 5 This is a schematic diagram of a red micro LED (with metal bumps on the electrodes). Figure 6 This is a schematic diagram of blue and green micro LEDs (metal bumps are made on the electrodes). In one embodiment of this disclosure, the material of the metal bump is one or more of ITO, graphene, copper, nickel, chromium, indium, tin, silver, gold, aluminum, tungsten, titanium, and platinum, or a mixture or alloy thereof.

[0047] In one embodiment of this disclosure, micro-LEDs are peeled off from micro-LED wafers using a laser.

[0048] Laser Lift-Off (LLO) technology uses high-energy pulsed lasers to penetrate substrates such as sapphire, causing the material at the interface between the epitaxial layer (such as GaN) and the substrate to absorb laser energy and decompose, thus achieving non-destructive peeling. It is a key process in Micro-LED manufacturing.

[0049] Laser lift-off technology utilizes a high-energy pulsed laser beam to penetrate transparent substrates such as sapphire and focus at the interface between the substrate and the epitaxially grown GaN material. Since the photon energy is between the band gaps of sapphire and GaN, sapphire does not absorb photons, but the GaN at the interface absorbs a large amount of photon energy and decomposes to form liquid Ga and nitrogen gas. The release of nitrogen gas and the thermal stress generated by the laser work together to allow the GaN functional layer to be peeled off from the sapphire substrate and transferred to the terminal substrate.

[0050] In one embodiment of this disclosure, the driving substrate is one of TFT, CMOS, passive driving substrate, semi-active driving substrate, and two-dimensional transition metal sulfide TFT substrate.

[0051] In one embodiment of this disclosure, the driving substrate and the micro-LED wafer are bonded using one or more of the following methods: thermo-press bonding, laser bonding, and chemical plating self-bonding.

[0052] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0053] The units described in the embodiments of this disclosure can be implemented in software or hardware. The names of the units are not, in some cases, intended to limit the specific unit.

[0054] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), and so on.

[0055] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0056] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0057] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

[0058] The following points should be noted regarding this disclosure: (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0059] (2) Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0060] The above description is merely an embodiment of this disclosure and does not limit the patent scope of this disclosure. Any equivalent structure made using the content of this disclosure and its drawings, or directly or indirectly applied to other related technical fields, is similarly included within the patent protection scope of this disclosure.

Claims

1. A method for fabricating a full-color micro-LED display device based on wafer bonding, characterized in that, include: At least one micro-LED wafer is prepared, which includes micro-LEDs corresponding to the pixel arrangement positions of a portion or all of the driving substrate; the micro-LEDs on the same micro-LED wafer are of the same color; bonding structures are prepared on the electrodes of the micro-LEDs and pixels corresponding to the arrangement positions; the micro-LEDs on each micro-LED wafer are bonded to the pixels on the driving substrate, and the micro-LEDs are peeled off from the micro-LED wafer.

2. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, The micro-LED wafer includes: a red micro-LED wafer on a GaAs substrate, which contains red micro-LEDs corresponding to the red pixel arrangement positions on the driving substrate; a green micro-LED wafer on a sapphire substrate, which contains green micro-LEDs corresponding to the green pixel arrangement positions on the driving substrate; and a blue micro-LED wafer on a sapphire substrate, which contains blue micro-LEDs corresponding to the blue pixel arrangement positions on the driving substrate.

3. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 2, characterized in that, The micro-LEDs on each micro-LED wafer are bonded to pixels on the driving substrate, and the micro-LEDs are then peeled off from the micro-LED wafers. Specifically: the red micro-LED wafer is bonded to the red pixels on the driving substrate, and the red micro-LEDs are then peeled off from the red micro-LED wafer; the green micro-LED wafer is bonded to the green pixels on the driving substrate, and the green micro-LEDs are then peeled off from the green micro-LED wafer; the blue micro-LED wafer is bonded to the blue pixels on the driving substrate, and the blue micro-LEDs are then peeled off from the blue micro-LED wafer.

4. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, The micro-LED wafer contains multiple sets of chips, and each set of chips contains multiple micro-LEDs. The arrangement of the micro-LEDs in each set of chips is the same as the arrangement of a specific pixel on at least one driving substrate.

5. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, Also includes: After the micro-LED wafer is prepared, it is annealed to deposit an insulating or semiconductor film on the back side of the wafer substrate.

6. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, The bonding structure is a metal bump.

7. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, The material of the metal bump is one or more of ITO, graphene, copper, nickel, chromium, indium, tin, silver, gold, aluminum, tungsten, titanium, and platinum, or a mixture or alloy thereof.

8. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, Micro-LEDs are peeled off from micro-LED wafers using lasers.

9. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, The driving substrate is one of TFT, CMOS, passive driving substrate, semi-active driving substrate, or two-dimensional transition metal sulfide TFT substrate.

10. The method for fabricating a full-color micro-LED display device based on wafer bonding according to claim 1, characterized in that, The driving substrate is bonded to the micro-LED wafer using one or more of the following methods: thermo-press bonding, laser bonding, and chemical plating self-bonding.

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