Low-temperature hybrid bonding method for preparing Micro-LED display device based on asymmetric structure

Abstract

The invention discloses a low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure, and relates to the technical field of display devices. According to the method, accurate alignment and efficient connection between a Micro-LED chip and a substrate or other components are realized through an asymmetric structure design and a hybrid bonding technology under a low-temperature condition; and large thermal stress and deformation generated in the working process of the Micro-LED due to different thermal expansion coefficients and Young moduli of all component materials in the Micro-LED device are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of display devices, and in particular to a low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure. Background Art

[0002] With the rapid development of display technology, Micro-LED, as the representative of the next generation of display technology, is gradually becoming a research hotspot in the display field due to its significant advantages such as high brightness, low power consumption, long life and high contrast. The high performance requirements of Micro-LED display devices pose more stringent challenges to their manufacturing process, especially in the bonding process between the chip and the substrate, which needs to solve the stress impact problem caused by the difference in thermal expansion coefficient to improve the structural strength and reliability of the device.

[0003] At present, the bonding processes of Micro-LED display devices mainly include traditional eutectic bonding, metal welding and emerging laser mass bonding. However, these technologies have limitations to varying degrees in practical applications. Although eutectic bonding can achieve higher bonding strength, it is easy to cause thermal stress mismatch between the chip and the substrate during the hot pressing process, affecting the long-term stability of the device; although metal welding can effectively reduce thermal stress, it is costly and the process is complex; although laser mass bonding has high precision and high efficiency, the requirements for equipment precision and cost are also relatively high.

[0004] In addition, the traditional bonding process often faces problems such as uneven interface and low alignment accuracy when dealing with the tiny size and high-density arrangement of Micro-LED chips, which directly affect the bonding quality and device performance. Therefore, developing a new bonding process to improve the flatness of the bonding interface, reduce thermal stress shock, and improve the structural strength and reliability of Micro-LED display devices has become a technical problem that needs to be solved urgently.

[0005] Photosensitive polymer materials, such as photosensitive benzocyclobutene (BCB) and photosensitive polyimide (PI), have been widely used in the field of microelectronic packaging due to their good optical properties, thermal stability and chemical stability. Although these materials can achieve precise patterning through photochemical reactions, the application of photosensitive polymer materials in the hybrid bonding process of Micro-LED display devices still faces problems such as uneven interfaces and insufficient bonding strength. Summary of the invention

[0006] The purpose of the present invention is to provide a low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure, which can improve the manufacturing efficiency of the Micro-LED display device through asymmetric structure design combined with hybrid bonding technology under low temperature conditions.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure, comprising:

[0009] Step 1: Fabricate Ti / Ni / Au metal electrodes on the surface of a silicon substrate using a Damascus process;

[0010] Step 2, coating a photosensitive polymer on the surface of the silicon substrate as a dielectric layer;

[0011] Step 3: To meet the requirements of the subsequent evaporation process, the polymer is patterned using a photolithography process;

[0012] Step 4: coating photoresist again on the dielectric layer to isolate and protect the polymer, and performing patterning again;

[0013] Step 5, using electron beam evaporation to deposit metal indium as a bump;

[0014] Step 6: Use the lift-off process to remove excess metal and photoresist to complete the substrate preparation;

[0015] Step 7: Use a flip-chip bonding machine to perform hybrid bonding on the substrate by applying pressure and temperature to obtain a Micro-LED display device with an asymmetric structure.

[0016] Optionally, the photosensitive polymer is photosensitive benzocyclobutene and / or photosensitive polyimide which is poorly soluble in reagents such as acetone.

[0017] Optionally, the position of the patterning process in step 4 is the same as the position of the patterning process in step 3.

[0018] Optionally, the flip chip bonding machine adopts a low temperature bonding method.

[0019] Optionally, the temperature of the low temperature bonding method is 140°C.

[0020] Optionally, the pressure in step 7 is 20 Kg.

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0022] The present invention discloses a low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure. The method realizes precise alignment and efficient connection between a Micro-LED chip and a substrate or other components through asymmetric structure design combined with hybrid bonding technology under low temperature conditions, thereby reducing the large thermal stress and deformation generated by the Micro-LED during operation due to the different thermal expansion coefficients and Young's modulus of the components of the Micro-LED device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is a flow chart of substrate preparation in this embodiment;

[0025] Figure 2 Schematic diagram of the cross-sectional structure of the device after hybrid bonding in this embodiment. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The purpose of the present invention is to provide a low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure, which can improve the manufacturing efficiency of the Micro-LED display device through asymmetric structure design combined with hybrid bonding technology under low temperature conditions.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 As shown, in order to improve the structural strength and reliability of Micro-LED micro-display and reduce the stress impact caused by the difference in thermal expansion coefficient between the chip and the substrate, the present invention provides a low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure, comprising:

[0030] Step 1: Fabricate Ti / Ni / Au metal electrodes on the surface of a silicon substrate using a Damascus process;

[0031] Step 2: coating a photosensitive polymer as a dielectric layer on the surface of the silicon substrate, such as photosensitive benzocyclobutene (BCB) and photosensitive polyimide (PI), which are difficult to dissolve in reagents such as acetone;

[0032] Step 3: To meet the requirements of the subsequent evaporation process, the polymer is patterned using a photolithography process;

[0033] Step 4: coating the polymer layer with photoresist again to isolate and protect the polymer, and patterning the same position as in the previous step;

[0034] Step 5, electron beam evaporation of metal indium (In) as a bump;

[0035] Step 6: Lift-off process to remove excess metal and photoresist. The above steps of substrate preparation flow chart is as follows Figure 1 As shown;

[0036] Step 7: Use a flip-chip bonding machine to achieve hybrid bonding of Micro-LEDs by applying pressure and temperature. The schematic diagram of the cross-sectional structure of the device after hybrid bonding is shown in the figure below. Figure 2 shown.

[0037] The above-mentioned low-temperature hybrid bonding process based on asymmetric structure design aims to improve the manufacturing efficiency of Micro-LED display devices, reduce costs, and optimize the mechanical properties and reliability of the devices. Therefore, it has the following beneficial effects:

[0038] Due to the small size of Micro LED, during the manufacturing process, traditional dispensing processes may encounter problems with accuracy and uniformity when dealing with such a small size, while spin coating technology can more accurately control the distribution of glue. However, there are still many problems with spin coating of Micro LED chips, such as: (1) Micro LED has extremely high requirements for the light efficiency and wavelength consistency of LED grains. During the glue coating process, if the control is not proper, it may cause the light emission wavelength of the LED grains to deviate, affecting the display effect; (2) The grain size of Micro LED is tiny, and the glue coating process requires extremely high precision to control the thickness and uniformity of the coating. Once the control is improper, it may cause uneven coating thickness, affecting the display effect and device performance. Although etching after glue coating on existing chips and substrates can be considered in Micro LED hybrid bonding, the etching selectivity for materials is poor, the glue on the etched surface is often uneven in thickness, and plasma may also cause damage to the device surface.

[0039] Therefore, the present invention uses an asymmetric structure, with glue only on the substrate side, first coating the photosensitive polymer, then using photoresist to protect the photosensitive polymer, and then evaporating the bumps after photolithography, eliminating the dry etching step. At the same time, low-temperature bonding (140°C) is used in this embodiment to improve the structural strength and reliability of the Micro-LED display device by optimizing the bonding interface and reducing thermal stress shock.

[0040] Furthermore, the bonding process of this embodiment is an effective method to solve the problems of thermal stress shock and interface unevenness in the bonding process of the Micro-LED chip and the substrate in the prior art, which is specifically manifested as follows:

[0041] (1) Improving bonding quality: By using photosensitive polymer materials as the dielectric layer, using photolithography to achieve precise patterning, and using a low-temperature hybrid bonding process, the present invention significantly improves the flatness of the bonding interface and reduces bonding defects caused by uneven interfaces.

[0042] (2) Enhanced structural strength: Photosensitive polymer materials have good mechanical support properties and can form a stable connection between the Micro-LED chip and the substrate, thereby enhancing the structural strength of the device.

[0043] (3) Prolonging service life: Under long-term working conditions, the hybrid bonding process of the present invention can reduce performance degradation caused by thermal stress, reduce the generation of bad pixels, and extend the service life of Micro-LED display devices.

[0044] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0045] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure, characterized in that: include: Step 1: Fabricate Ti / Ni / Au metal electrodes on the surface of a silicon substrate using a Damascus process; Step 2, coating a photosensitive polymer on the surface of the silicon substrate as a dielectric layer; Step 3: To meet the requirements of the subsequent evaporation process, the polymer is patterned using a photolithography process; Step 4: coating photoresist again on the dielectric layer to isolate and protect the polymer, and performing patterning again; Step 5, using electron beam evaporation to deposit metal indium as a bump; Step 6: Use the lift-off process to remove excess metal and photoresist to complete the substrate preparation; Step 7: Use a flip-chip bonding machine to perform hybrid bonding on the substrate by applying pressure and temperature to obtain a Micro-LED display device with an asymmetric structure.

2. The low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure according to claim 1, characterized in that: The photosensitive polymer is photosensitive benzocyclobutene and / or photosensitive polyimide which is insoluble in reagents such as acetone.

3. The low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure according to claim 1, characterized in that: The position of the patterning process in step 4 is the same as the position of the patterning process in step 3.

4. The low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure according to claim 1, characterized in that: The flip chip bonding machine adopts a low temperature bonding method.

5. The low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure according to claim 4, characterized in that: The temperature of the low temperature bonding method is 140°C.

6. The low-temperature hybrid bonding method for preparing a Micro-LED display device based on an asymmetric structure according to claim 1, characterized in that: The pressure in step 7 is 20 Kg.

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