阅读说明：本技术 亲疏水界面组装制备led显示器的方法 (Method for assembling and preparing LED display through hydrophilic and hydrophobic interfaces ) 是由 张小齐 刘政 李燕 彭益 胡友 于 2020-07-27 设计创作，主要内容包括：本发明公开了一种亲疏水界面组装制备LED显示器的方法。该方法包括提供第一衬底,第一衬底的顶表面上设置有多个驱动电极和导向机构,导向机构设置在所述驱动电极的周围；提供悬浮有LED芯片的LED芯片液体悬浮液；使LED芯片液体悬浮液流过第一衬底的顶表面；捕获LED芯片于所述多个驱动电极上；对第一衬底进行退火,以使得每个LED芯片和与其对应的驱动电极电性连接。LED芯片的焊盘电极所在区域与所述驱动电极所在区域的亲疏水性质一致；所述导向机构与所述LED芯片的焊盘电极所在区域的亲疏水性质相反。本发明其可以简洁快速且精准地转移巨量的微型发光二极管,并具有高良率。(The invention discloses a method for assembling and preparing an LED display through a hydrophilic-hydrophobic interface. The method includes providing a first substrate having a plurality of drive electrodes disposed on a top surface thereof and a guide mechanism disposed about the drive electrodes; providing an LED chip liquid suspension in which an LED chip is suspended; flowing an LED chip liquid suspension over a top surface of a first substrate; capturing the LED chips on the plurality of driving electrodes; and annealing the first substrate so that each LED chip is electrically connected with the corresponding driving electrode. The region where the pad electrode of the LED chip is located is consistent with the hydrophilic and hydrophobic properties of the region where the driving electrode is located; the guiding mechanism and the region where the pad electrode of the LED chip is located have opposite hydrophilic and hydrophobic properties. The invention can simply, quickly and accurately transfer a huge amount of micro light-emitting diodes and has high yield.)

1. A method for assembling and preparing an LED display through a hydrophilic-hydrophobic interface is characterized by comprising the following steps:

providing a first substrate having a plurality of drive electrodes disposed on a top surface thereof and a guide mechanism disposed around the drive electrodes;

providing an LED chip liquid suspension in which an LED chip is suspended;

flowing the LED chip liquid suspension across the top surface of the first substrate;

capturing the LED chips on the plurality of driving electrodes;

annealing the first substrate to electrically connect each LED chip with the corresponding driving electrode;

the region where the pad electrode of the LED chip is located is consistent with the hydrophilic and hydrophobic properties of the region where the driving electrode is located;

the guiding mechanism and the region where the pad electrode of the LED chip is located have opposite hydrophilic and hydrophobic properties.

2. The method for assembling the hydrophilic-hydrophobic interface to prepare the LED display according to claim 1, wherein the guiding mechanism is a convex structure or a concave structure.

3. The method for assembling the hydrophilic-hydrophobic interface to prepare the LED display as claimed in claim 2, wherein the guiding mechanism is an inwardly contracted funnel-shaped structure, and the driving electrode is located in a central region surrounded by the guiding mechanism.

4. The method for assembling the hydrophilic-hydrophobic interface of claim 3, wherein a plurality of the guiding mechanisms are integrally connected and detachably fixed on the top surface of the first substrate.

5. The method for assembling the hydrophilic-hydrophobic interface to manufacture the LED display according to claim 1, wherein the first substrate is annealed, the guiding mechanism undergoes a phase change, and the hydrophilic-hydrophobic properties of the guiding mechanism are reversed to reinforce the LED chip.

6. The method for assembling the hydrophilic-hydrophobic interface to prepare the LED display according to claim 1, wherein the driving electrodes are arranged on the top surface of the first substrate in a convex structure or a concave structure.

7. The method for preparing an LED display by assembling the hydrophilic-hydrophobic interface according to claim 1, further comprising:

forming a plurality of light conversion mechanisms and covering the exposed surfaces of the corresponding LED chips;

and forming a plurality of light diffusion mechanisms and covering the corresponding LED chips.

8. The method for assembling the hydrophilic-hydrophobic interface to prepare the LED display according to claim 1, wherein the method comprises the following steps: the liquid of the LED chip liquid suspension is at least one of ethanol, polyalcohol, ketone, halogenated hydrocarbon and water, and the method for removing the liquid comprises thermal evaporation, UV light evaporation or chemical cleaning.

9. The method for assembling the hydrophilic-hydrophobic interface to prepare the LED display according to claim 1, wherein the method comprises the following steps: and the upper surface and the lower surface of the LED chip are provided with pad electrodes.

10. The method for assembling the hydrophilic-hydrophobic interface of any one of claims 1-9 to manufacture the LED display, wherein the guiding mechanism is a hydrophobic material, and the hydrophobic surface thereof comprises at least one of polyolefin, polycarbonate, polyamide, polyacrylonitrile, polyester, non-fluorine-containing acrylate, polytetrafluoroethylene PTFE, fluorinated polyethylene and fluorocarbon wax.

Technical Field

The invention relates to semiconductor device manufacturing and optical systems, in particular to a method for assembling and preparing an LED display through a hydrophilic-hydrophobic interface.

Background

Micro light Emitting diodes (Micro-LEDs) are "Micro" LEDs, and Micro light Emitting Diode array Display is a new Display technology, and compared with other Display technologies, such as Liquid Crystal Display (LCD), organic light-Emitting Diode (OLED), and Plasma Display (PDP), the core difference is that inorganic LEDs are used as light Emitting pixels.

The manufactured tiny LED needs to be transferred to a substrate with a ready-made driving circuit. The number of pixels of a television or a mobile phone screen is quite large, for example, a 55-inch 4K television is taken as an example, the number of crystal grains to be transferred is up to 2400 ten thousand (calculated by 4000 x 2000 x RGB three colors), and even if 1 ten thousand are transferred at a time, 2400 times of repetition is needed, which is called bulk transfer. The huge transfer printing equipment is the key for realizing the integrated manufacturing of the three-primary-color Micro-LED chip. The 4K or 8K display pixels are small in size, the tolerance of a display product to pixel errors is low, and a display screen with "bright spots" or "dark spots" cannot meet the requirements of users, so that it is very difficult and complicated technology to reliably transfer the small pixels to a substrate with a well-made driving circuit and realize circuit connection. In fact, "mass transfer" is indeed a major bottleneck in the commercialization of Micro-LEDs today. The efficiency and success rate of the transfer determine the success of commercialization. How to improve the yield of the Micro-LED devices after mass transfer is a problem worthy of research. The LED crystal film is directly transported to the driving backboard without packaging, and millions or even tens of millions of micron-sized LED crystal grains are accurately and efficiently moved to a circuit substrate in the production of Micro-LEDs.

US20170133550a1 for the first time proposes a fluid assembly method for manufacturing a light emitting display by using a fluid suspension liquid as a medium during the assembly of a Micro LED, flowing the Micro LED suspension through a light emitting substrate with a plurality of wells disposed on the top surface so that the Micro LED is captured in the wells, and capturing and aligning the Micro LED to the solder joints by mechanically and electrically connecting the Micro LED electrodes at the interface of the capillaries of the wells with molten solder. Because the acting force of the capillary tube in the method is too large and uncontrollable, on one hand, the Micro LED is easy to damage and lose efficacy, and on the other hand, the Micro LED is easy to induce to be assembled and stacked in a staggered way, so that the transfer precision and yield are difficult to ensure, the huge transfer with high requirement on transverse precision cannot be met, the repair process is complicated and time-consuming, and the requirement on large-scale production is difficult to meet. US20180261570a1 proposes a way of directed self-assembly by dealing with bulk transfer Micro LEDs by diamagnetic levitation, which involves applying a vibratory force to a magnetic table comprising a plurality of magnets and spacers arranged in an array, depositing a plurality of ferromagnetic LED chips (each having a ferromagnetic strip) onto a magnetic platform, the vibratory force distributing the plurality of ferromagnetic LED chips substantially uniformly over the surface of the magnetic platform, and wherein the vibratory force aligns the plurality of ferromagnetic LED chips to a node having a maximum magnetic field strength, and removing a set of ferromagnetic LED chips that are not in the node of maximum magnetic field strength by physical reversal of the magnetic field. However, the preparation of ferromagnetic LED chips is complicated, and thus the technology of diamagnetic levitating fluid assembly is expensive, slow, and may lack flexibility and fragile structure and compatibility such as LED chips, which results in lack of resolution of LED chips and non-uniform LED chip density, which hinders multiplexing, miniaturization, and signal quantification. In addition, US20180053742a1 proposes to adhere the electronic device to a temporary fixing layer, which is expanded to change the LED pitch for transfer to a carrier substrate. In the method, the temporary fixing layer expands in the transverse direction and the longitudinal direction, so that the transverse transfer precision is difficult to ensure, huge transfer with high requirement on the transverse precision cannot be met, and the expansion multiple of the temporary fixing layer is limited, so that large transverse spacing cannot be met. The problems encountered with these techniques are: 1) the transferred Micro-LED chip has extremely small size (3-200 μm), and needs extremely high-precision operation technology; 2) tens of thousands or even hundreds of thousands of Micro-LED chips need to be moved for one transfer, and the number is huge; 3) how to improve the transfer yield to 99.99% or even higher.

Disclosure of Invention

The invention mainly solves the technical problem of providing a manufacturing method for assembling and preparing an LED display by a hydrophilic-hydrophobic interface, which can simply, quickly and accurately transfer a large amount of micro light-emitting diodes and has high yield.

In order to solve the technical problems, one technical scheme adopted by the invention is to provide a manufacturing method for assembling and preparing an LED display by a hydrophilic and hydrophobic interface, which comprises the following steps:

providing a first substrate having a plurality of drive electrodes disposed on a top surface thereof and a guide mechanism disposed around the drive electrodes;

providing an LED chip liquid suspension in which an LED chip is suspended;

flowing the LED chip liquid suspension across the top surface of the first substrate;

capturing the LED chips on the plurality of driving electrodes;

annealing the first substrate to electrically connect each LED chip with the corresponding driving electrode;

the region where the pad electrode of the LED chip is located is consistent with the hydrophilic and hydrophobic properties of the region where the driving electrode is located; the guiding mechanism and the region where the pad electrode of the LED chip is located have opposite hydrophilic and hydrophobic properties.

The manufacturing method for assembling the hydrophilic-hydrophobic interface to prepare the LED display applies the directional local stress on each LED chip. The guiding mechanism is opposite to the hydrophilic and hydrophobic properties of the region where the pad electrode of the LED chip is located, and the guiding mechanism generates a distance r between the guiding mechanism and the LED chip₁Associated repulsive force F_REPULSIONIn which F is_REPULSION∝1/(r₁)². The hydrophilic and hydrophobic properties of the LED chip and the area where the driving electrode is located are consistent, and the driving electrode generates a distance r between the driving electrode and a pad electrode of the LED chip₂Associated attractive force F_ATTRATIONIn which F is_ATTRATION∝ 1/(r₂)². Repulsive force F_REPULSIONGenerated repulsive potential energy U_REPULSION∝ 1/r₁And an attractive force F_ATTRATIONGenerated traction potential energy U_ATTRATION∝1/r₂The comprehensive action on the LED chip forms the potential energy difference UATTRATION-UREPULSION and competes to generate the local stress F with certain orientation_ATTRATIONAnd F_REPULSIONVector sum, thus acting as a range where the drive electrode capture area for capture and the capture speed of the LED chip exist. The position of each LED chip does not fall within the drive electrode capture area or the speed of each LED chip is not captured by the drive electrode if it is above a maximum threshold of the captured speed. The local stress with certain orientation is mainly Van der Waals force, coulomb force and hydrogen bond action, the action of the local stress with certain orientation on the LED chip is relatively weak under the microscopic size (5-500 mu m), the damage to the LED chip can be reduced, and the yield is improved. The capillary force generated by the capture structure design of the wells or grooves of the US20170133550a1 is too large and uncontrollable, so that the Micro LEDs are easily damaged and failed on one side and on the other side, the Micro LEDs are easily induced to be assembled and stacked in a staggered manner, and therefore, the transfer precision and yield are difficult to ensure, and the requirement of large transfer on high lateral precision cannot be met. A second benefit of providing the guide mechanism is that the components on the large (meter scale) substrate are arranged relatively fast. Once the LED chip is captured by the driving electrode, the mechanical stress between the driving electrode and the LED chip, and the close force of the guiding mechanism on the LED chip, cause the assembled LED chip not to be removed from the right direction, but the misaligned component is removed. This provides a low cost and high speed assembly method that achieves predicted assembly speeds of over 3000 tens of thousands of micro-assemblies per hour. The assembling method comprisesA general approach that can be applied to any number of substrates and is well suited for low fill factor and high area arrays with limited surface topography.

Under the condition of the same site density, a plurality of guide mechanisms are arranged on the top surface of the first substrate, the surface energy of the driving electrode is higher, and is vital at a micro scale, so that the capture efficiency of the driving electrode is higher, and the driving electrode is more stable.

Surface Gibbs free energy of the drive electrode and first substrate system:

△G = △H －△S·T。

the change in surface Gibbs free energy of the capture LED chip, the drive electrode and the first substrate system is a measure of the balance between the two driving forces enthalpy and entropy to determine if the reaction is spontaneous.

And the process△HIs < 0, and△S> 0, therefore△G< 0, thereby facilitating the driving electrode capture LED chip process, rendering the process spontaneous.

In a preferred embodiment, the guiding mechanism is a convex structure or a concave structure.

In a preferred embodiment, the guide mechanism is an inwardly contracted funnel-shaped structure, and the driving electrode is located in a central region surrounded by the guide mechanism.

In a preferred embodiment, a plurality of the guide mechanisms are integrally connected and detachably fixed to the top surface of the first substrate.

In a preferred embodiment, the first substrate is annealed, the guiding mechanism is subjected to phase change, and the hydrophilic and hydrophobic properties of the guiding mechanism are reversed, so that the LED chip is reinforced.

In a preferred embodiment, the driving electrodes are disposed on the top surface of the first substrate in a convex structure or in a concave structure.

In a preferred embodiment, the method for manufacturing the LED display by assembling the hydrophilic-hydrophobic interface further comprises:

forming a plurality of light conversion mechanisms and covering the exposed surfaces of the corresponding LED chips;

and forming a plurality of light diffusion mechanisms and covering the corresponding LED chips.

In a preferred embodiment, the liquid of the liquid suspension of the LED chip is selected from at least one of ethanol, polyol, ketone, halogenated hydrocarbon and water, and the method for removing the liquid comprises thermal evaporation, UV light evaporation or chemical cleaning.

In a preferred embodiment, the upper and lower surfaces of the LED chip are provided with pad electrodes.

In a preferred embodiment, the guide mechanism is a hydrophobic material, and the hydrophobic surface thereof comprises at least one of polyolefin, polycarbonate, polyamide, polyacrylonitrile, polyester, fluorine-free acrylate, polytetrafluoroethylene, PTFE, fluorinated polyethylene and fluorocarbon wax.

According to the manufacturing method for manufacturing the LED display by assembling the hydrophilic and hydrophobic interfaces, the huge amount of micro light-emitting diodes are transferred onto the target substrate in a highly ordered and controllable manner, so that the method for transferring the huge amount of micro light-emitting diodes in the embodiment of the invention can quickly and accurately transfer the huge amount of micro light-emitting diodes onto the target substrate, and therefore the manufacturing cost of the micro light-emitting diode display device manufactured by the huge amount of micro light-emitting diodes in the embodiment of the invention is low, and the yield is high.

Drawings

The invention and its advantages will be better understood by studying the following detailed description of specific embodiments, given by way of non-limiting example, and illustrated in the accompanying drawings, in which:

fig. 1 is a top view of a first substrate of a manufacturing method for fabricating an LED display by assembling a hydrophilic-hydrophobic interface according to embodiment 1 of the present invention.

Fig. 2 is a partial cross-sectional view showing the function of directional capture of the LED chip of embodiment 1 of the present invention on the first substrate surface.

Fig. 3 is a partial cross-sectional view showing the function of directional capture of the LED chip of embodiment 2 of the present invention on the first substrate surface.

Fig. 4 is a cross-sectional view of an LED chip presenting embodiment 4 of the present invention.

Fig. 5 is a cross-sectional view of an LED chip presenting embodiment 5 of the present invention.

Detailed Description

Referring to the drawings, wherein like reference numbers refer to like elements throughout, the principles of the present invention are illustrated in an appropriate environment. The following description is based on illustrated embodiments of the invention and should not be taken as limiting the invention with regard to other embodiments that are not detailed herein.

The word "embodiment" is used herein to mean serving as an example, instance, or illustration. In addition, the articles "a" and "an" as used in this specification and the appended claims may generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Further, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise direct contact of the first and second features through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.