Micro LED mass bonding method based on triethyl aluminum
By using triethylaluminum as the sacrificial layer material and using laser irradiation to quickly decompose it, efficient bonding between the Micro LED chip and the target substrate is achieved, and the low adhesive force, high decomposition temperature and residues in the prior art are solved. The problem of difficulty in cleaning improves bonding quality and stability while reducing costs.
Patent Information
- Application Number
- CN202411610539.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-02-18
AI Technical Summary
In the existing Micro LED massive bonding method, the chip is low, the decomposition temperature is high, and the temporary bonding material is prone to residue.
Triethylaluminum is used as the sacrificial layer material, and by coating it on the target substrate, the triethylrhenium is rapidly decomposed and gas is generated by laser irradiation, thereby achieving accurate bonding between the Micro LED chip and the target substrate.
The bonding quality and efficiency are improved, the overall cost is reduced, the bonding stability is enhanced, and the decomposed residue is removed by cleaning inert gas or solvent.
Smart Images
Figure CN119486429A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of Micro LED display technology and relates to a Micro LED mass bonding method based on triethyl aluminum. Background Art
[0002] Micro LED display technology is considered to be an important development direction of the next generation of display technology due to its advantages such as high brightness, low power consumption and long life. In the Micro LED manufacturing process, mass transfer technology is a key step in transferring tiny LED chips from the growth substrate to the target substrate. In order to achieve efficient mass transfer, a temporary bonding material is required, which can firmly fix the chip during the transfer process and quickly decompose and release the chip through specific means after the transfer is completed. Existing temporary bonding materials have some problems, such as insufficient adhesion, too high decomposition temperature or difficult to clean residues after decomposition. Summary of the invention
[0003] The present invention overcomes the shortcomings of the prior art and proposes a Micro LED mass bonding method based on triethyl aluminum; the problems of low chip bonding force, high decomposition temperature and easy residue of temporary bonding materials in the existing Micro LED mass bonding method are solved. The present invention is achieved through the following technical solutions: A method for mass bonding of Micro LEDs based on triethylaluminum comprises the following steps: 1) coating a triethylaluminum solution on a target substrate to form a triethylaluminum film as a sacrificial layer; 2) Transfer the Micro LED chip to the target substrate coated with triethylaluminum film to align the chip electrodes with the substrate electrodes; 3) Laser irradiate the sacrificial layer to bond the Micro LED chip to the target substrate.
[0004] Preferably, the wavelength of the laser irradiation is 1064 nm, the power is 1 W, and the scanning speed is 10 mm / s.
[0005] Preferably, the bonding temperature is 80° C.-250° C., the pressure is 80-120 kPa, and the bonding time is 10 s-60 s.
[0006] Preferably, the concentration of the triethylaluminum solution is 10-15%.
[0007] Preferably, the preparation method of triethylaluminum is as follows: titanium-containing aluminum powder is continuously hydrogenated in a hydrogenation kettle under inert gas protection and a pressure of 10-12 MPa for 6-7 hours; ethylene is continuously introduced under a pressure of 0.5-3 MPa, and the reaction is completed within 5-6 hours to obtain crude triethylaluminum, and then impurities are separated by vaporization and distillation and ethylene conversion reaction is performed to obtain triethylaluminum.
[0008] Preferably, the thickness of the sacrificial layer is 5-15 μm.
[0009] Preferably, the coating is performed by using an ultrasonic spraying device to atomize the triethylaluminum solution into tiny particles, and then spraying the triethylaluminum solution uniformly onto the surface of the target substrate.
[0010] Preferably, the Micro LED chip is transferred to a target substrate coated with a triethylaluminum film by mass transfer.
[0011] Preferably, the electrodes of the Micro LED chip and the electrodes of the target substrate are both indium-plated electrodes.
[0012] Preferably, after bonding, an inert gas purge device or solvent cleaning is used to remove the decomposition residues.
[0013] The beneficial effects of the present invention compared with the prior art are as follows: 1. Improve bonding quality: Using triethylaluminum as the sacrificial layer material can quickly decompose and generate gas under laser irradiation, promote the precise bonding between the chip and the target substrate, and improve the bonding quality and efficiency.
[0014] 2. Reduce costs: As a sacrificial layer material, triethyl aluminum has a relatively simple preparation and spraying process and low cost, which helps to reduce the overall cost of Micro LED mass bonding.
[0015] 3. Enhanced stability: The gas generated during laser irradiation can be evenly distributed between the chip and the target substrate, forming a protective gas film to prevent external impurities from affecting the bonding process and enhance bonding stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 A schematic diagram of spraying a sacrificial layer material onto a target substrate according to the present invention; Figure 2 Schematic side view of the target substrate after the mass transfer of Micro LED chips of the present invention; Figure 3 A schematic diagram of laser decomposition of sacrificial materials according to the present invention; Figure 4 A schematic diagram of the process of purging residual sacrificial material according to the present invention; Figure 5This is a schematic diagram of the overall process of sacrificial layer materials based on mass bonding of Micro LEDs proposed by the present invention.
[0017] Markings in the figure: 1 is the target substrate, 2 is the sacrificial layer, 3 is the ultrasonic spraying device, 4 is the pad, 5 is the Micro LED chip, 6 is the laser irradiation device, and 7 is the inert gas purging device. DETAILED DESCRIPTION
[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail in conjunction with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The technical solutions of the present invention are described in detail below in conjunction with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.
[0019] Example 1 See also Figures 1 to 5 This embodiment proposes a Micro LED mass bonding method based on triethylaluminum, which specifically includes the following steps: First, the Micro LED chip 5 and the target substrate 1 are prepared according to conventional processes to ensure that the chip size, quantity and arrangement meet the design requirements. The electrodes of the Micro LED chip 5 are indium-plated electrodes, and the electrodes of the target substrate 1 are indium-plated electrodes.
[0020] S1. Preparation of sacrificial layer material: triethylaluminum (Al(C2H5)3) is selected as the sacrificial material. It is prepared by the following method: titanium-containing aluminum powder is continuously hydrogenated in a hydrogenation reactor under inert gas protection and 10MPa pressure for 6 hours; ethylene is continuously introduced under 2MPa pressure, and the reaction is completed within 5 hours to obtain crude triethylaluminum, which is then vaporized and distilled to separate impurities and ethylene conversion reaction to obtain triethylaluminum; the prepared triethylaluminum material is dissolved in an appropriate solvent (such as benzene) to obtain a triethylaluminum solution with a concentration of 10%.
[0021] S2, preparing a sacrificial layer: firstly, the target substrate 1 is plasma cleaned, on the one hand, to clean the target substrate 1, and on the other hand, to activate the surface of the target substrate 1, so that the target substrate 1 has better adhesion with triethylaluminum. A layer of triethylaluminum is coated on the substrate area for bonding the Micro LED chip 5 as the sacrificial layer 2; after spraying, it is dried at room temperature for 10 minutes to form a triethylaluminum film with a thickness of about 10 μm.
[0022] The spraying process uses an ultrasonic spraying device 3 to use the high-frequency vibration of ultrasound to atomize the liquid into tiny particles, and evenly spray the sacrificial layer material onto the surface of the target substrate. Dry at room temperature to form a uniform triethyl aluminum film; the coating thickness is precisely controlled to meet the needs of specific applications. The uniformity and integrity of the triethyl aluminum sacrificial material coating are guaranteed without defects such as cracks and bubbles. The spraying device and the spraying technology method belong to the prior art.
[0023] S3. Mass transfer: Triethylaluminum is easily decomposed by heat. Using the chemical activity of triethylaluminum, the Micro LED chip 5 is transferred to the target substrate 1 coated with triethylaluminum film by mass transfer to achieve the alignment of the chip electrode and the substrate electrode. Before using triethylaluminum for bonding, the chip electrode and the glass substrate surface need to be cleaned to remove surface pollutants and oxide layers to ensure surface activity. Common surface treatment methods include plasma cleaning.
[0024] S4, laser irradiation: Use a high-precision laser irradiation device 6 to irradiate the sacrificial layer 2 to bond the Micro LED chip 5 to the target substrate 1; during the bonding process, it is necessary to control the bonding pressure to avoid excessive pressure causing chip damage or rupture of the sacrificial layer 2; accurately control the bonding temperature to ensure that the triethylaluminum sacrificial material does not decompose or react prematurely during the bonding process. Adjust the bonding speed to ensure uniform contact and effective bonding between the chip and the substrate. Control the bonding time to avoid material performance degradation due to excessive time. In this embodiment, the bonding temperature is 150°C, the pressure is 100kPa, and the bonding time is 30s.
[0025] At the same time, through laser heating, triethylaluminum is rapidly decomposed in the temperature range of 100°C to 200°C to generate volatile compounds, thereby releasing the Micro LED chip 5. The wavelength of the laser is 1064nm, the power is 1W, and the scanning speed is 10mm / s. The thermal effect of the laser promotes the bonding of the Micro LED chip 5 with the target substrate 1, and triethylaluminum is decomposed.
[0026] S5, cleaning step: using an inert gas purge device 7 or a solvent for cleaning to remove the decomposed residues.
[0027] In this embodiment, the principle of laser irradiation bonding is: The triethylaluminum molecules are first adsorbed on the surface of the target substrate 1, and the adsorbed triethylaluminum molecules react chemically with the active sites on the surface of the target substrate 1 to form stable chemical bonds. For example, they react with hydroxyl groups to form compounds of water and aluminum. The generated new compounds further react with other molecules to form a cross-linked structure to enhance the bonding strength. The bonding force of triethylaluminum is used to bond the electrodes of the Micro LED chip 5 to the pads 4 of the target substrate 1. At the same time, the indium on the electrodes of the Micro LED chip 5 and the indium on the electrodes of the target substrate 1 are melted to achieve welding of the Micro LED chip 5 and the target substrate 1.
[0028] The decomposition of triethylaluminum is a stepwise process involving multiple intermediate steps. The main decomposition pathways include: Initial decomposition: Al( C 2 H 5)3→Al( C 2 H 5)2+ C 2 H 5 Triethylaluminum decomposes to form a diethylaluminum radical and an ethyl radical.
[0029] Further decomposition: Al( C 2 H 5)2→Al( C 2 H 5)+ C 2 H 5 The diethylaluminum radical further decomposes to form a monoethylaluminum radical and an ethyl radical.
[0030] Final decomposition: Al( C 2 H 5) →Al+ C 2 H 5 The monoethylaluminum radical eventually decomposes to form metallic aluminum and an ethyl radical.
[0031] Example 2 This embodiment discloses a Micro LED mass bonding method based on triethylaluminum, see Figures 1 to 5 , specifically the following steps: First, the Micro LED chip 5 and the target substrate 1 are prepared according to conventional processes to ensure that the chip size, quantity and arrangement meet the design requirements. The electrodes of the Micro LED chip 5 are indium-plated electrodes, and the electrodes of the target substrate 1 are indium-plated electrodes.
[0032] S1. Preparation of sacrificial layer material: triethylaluminum (Al(C2H5)3) is selected as the sacrificial material. It is prepared by the following method: titanium-containing aluminum powder is continuously hydrogenated in a hydrogenation reactor under inert gas protection and 12MPa pressure for 7 hours; ethylene is continuously introduced under 3MPa pressure, and the reaction is completed within 6 hours to obtain crude triethylaluminum, which is then vaporized and distilled to separate impurities and ethylene conversion reaction to obtain triethylaluminum; the prepared triethylaluminum material is dissolved in an appropriate solvent (such as benzene) to obtain a triethylaluminum solution with a concentration of 10%.
[0033] S2, preparing a sacrificial layer: first, the target substrate 1 is plasma cleaned to clean the target substrate 1 and activate the surface of the target substrate 1 so that the target substrate 1 has better adhesion with triethylaluminum. A layer of triethylaluminum is coated on the substrate area for bonding the Micro LED chip 5 as the sacrificial layer 2; after spraying, it is dried at room temperature for 10 minutes to form a triethylaluminum film with a thickness of about 15 μm.
[0034] The spraying process uses an ultrasonic spraying device 3 to use the high-frequency vibration of ultrasound to atomize the liquid into tiny particles, and evenly spray the sacrificial layer material onto the surface of the target substrate. Dry at room temperature to form a uniform triethyl aluminum film; the coating thickness is precisely controlled to meet the needs of specific applications. The uniformity and integrity of the triethyl aluminum sacrificial material coating are guaranteed without defects such as cracks and bubbles. The spraying device and the spraying technology method belong to the prior art.
[0035] S3. Mass transfer: Triethylaluminum is easily decomposed by heat. Using the chemical activity of triethylaluminum, the Micro LED chip 5 is transferred to the target substrate 1 coated with triethylaluminum film by mass transfer to achieve the alignment of the chip electrode and the substrate electrode. Before using triethylaluminum for bonding, the chip electrode and the glass substrate surface need to be cleaned to remove surface pollutants and oxide layers to ensure surface activity. Common surface treatment methods include plasma cleaning.
[0036] S4, laser irradiation: Use a high-precision laser irradiation device 6 to irradiate the sacrificial layer 2 to bond the Micro LED chip 5 to the target substrate 1; during the bonding process, it is necessary to control the bonding pressure to avoid excessive pressure causing chip damage or rupture of the sacrificial layer 2; accurately control the bonding temperature to ensure that the triethylaluminum sacrificial material does not decompose or react prematurely during the bonding process. Adjust the bonding speed to ensure uniform contact and effective bonding between the chip and the substrate. Control the bonding time to avoid material performance degradation due to too long a time. In this embodiment, the bonding temperature is 200°C, the pressure is 100kPa, and the bonding time is 50s.
[0037] At the same time, through laser heating, triethylaluminum is rapidly decomposed in the temperature range of 100°C to 200°C to generate volatile compounds, thereby releasing the Micro LED chip 5. The wavelength of the laser is 1064nm, the power is 1W, and the scanning speed is 10mm / s. The thermal effect of the laser promotes the bonding of the Micro LED chip 5 with the target substrate 1, and triethylaluminum is decomposed.
[0038] S5, cleaning step: using an inert gas purge device 7 or a solvent for cleaning to remove the decomposed residues.
[0039] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.
Claims
1. A Micro LED mass bonding method based on triethylaluminum, characterized in that: The following steps are involved: 1) coating a triethylaluminum solution on a target substrate (1) to form a triethylaluminum thin film as a sacrificial layer (2); 2) transferring the Micro LED chip (5) to a target substrate (1) coated with a triethylaluminum film to achieve alignment between the chip electrode and the substrate electrode; 3) Laser irradiating the sacrificial layer (2) to bond the Micro LED chip (5) to the target substrate (1).
2. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The wavelength of the laser irradiation is 1064 nm, the power is 1 W, and the scanning speed is 10 mm / s.
3. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The bonding temperature is 80°C-250°C, the pressure is 80-120kPa, and the bonding time is 10s-60s.
4. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The concentration of triethylaluminum solution is 10-15%.
5. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The preparation method of triethylaluminum is as follows: titanium-containing aluminum powder is continuously hydrogenated in a hydrogenation kettle under the protection of inert gas and a pressure of 10-12MPa for 6-7 hours; ethylene is continuously introduced under a pressure of 0.5-3MPa, the reaction is completed within 5-6 hours to obtain crude triethylaluminum, and then impurities are separated by vaporization and distillation and ethylene conversion reaction is performed to obtain triethylaluminum.
6. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The thickness of the sacrificial layer (2) is 5-15 μm.
7. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The coating is performed by using an ultrasonic spraying device (3) to atomize the triethylaluminum solution into tiny particles, and then spraying the triethylaluminum solution uniformly onto the surface of the target substrate (1).
8. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The Micro LED chip (5) is transferred to a target substrate (1) coated with a triethylaluminum film by means of mass transfer.
9. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: The electrodes of the Micro LED chip (5) and the electrodes of the target substrate (1) are both indium-plated electrodes.
10. The method for mass bonding of Micro LEDs based on triethylaluminum according to claim 1, characterized in that: After bonding, an inert gas purge (7) or solvent cleaning is used to remove decomposition residues.