Wafer bonding structure and light-emitting device

Abstract

The utility model discloses a wafer bonding structure and a luminescent device. The wafer bonding structure comprises a first wafer, a second wafer and a conductive adhesive layer, wherein each of the first wafer and the second wafer comprises a bonding surface, the conductive adhesive layer comprises conductive particles, and the bonding surface of the first wafer and the bonding surface of the second wafer are bonded through the conductive adhesive layer. According to the utility model, the technical effect of improving the product yield when the first wafer and the second wafer are bonded is realized, and the problem that the product yield is not high due to the fact that wafers are easy to crack after being stacked and bonded through a hard metal layer in the prior art is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of wafer bonding, and in particular to a wafer bonding structure and a light-emitting device. Background Art

[0002] One existing technology approach for Micro-LED displays involves bonding Micro-LED wafers to silicon-based CMOS wafers using wafer bonding technology. After removing the sapphire, the wafers undergo photolithography, etching, and dicing to create individual light-emitting modules. Wafer bonding involves coating two wafers with nanometer-scale metals. The wafers, typically 4 to 8 inches in size, undergo surface activation and are then vacuum bonded using wafer bonding equipment. The Micro-LED wafer uses a sapphire substrate, while the CMOS wafer uses a silicon-based substrate. This bonding process, coupled through a hard metal layer, results in low yields. Utility Model Content

[0003] The main purpose of the present invention is to provide a wafer bonding structure and a light-emitting device to solve the problem of low yield of wafers after stacking and bonding in the related art.

[0004] In order to achieve the above-mentioned object, the present invention provides a wafer bonding structure, comprising: a first wafer, a second wafer and a conductive adhesive layer; wherein,

[0005] The first wafer and the second wafer both include bonding surfaces, the conductive adhesive layer includes conductive particles, and the bonding surface of the first wafer and the bonding surface of the second wafer are bonded via the conductive adhesive layer.

[0006] Furthermore, an exhaust hole is opened in the second wafer, and the exhaust hole extends to the bonding surface of the second wafer.

[0007] Furthermore, the exhaust holes are provided in plurality and distributed at intervals.

[0008] Furthermore, a trumpet-shaped opening end is provided on one end of the exhaust hole close to the bonding surface.

[0009] Furthermore, the axis of the exhaust hole is perpendicular to the bonding surface.

[0010] Furthermore, the first wafer is set to be a Micro-LED wafer, the second wafer is set to be a silicon-based CMOS wafer, and the exhaust hole is set in the second wafer.

[0011] Furthermore, the conductive adhesive layer is made of flexible material.

[0012] Furthermore, the conductive adhesive layer also includes an adhesive film, and the conductive particles are dispersed in the adhesive film.

[0013] Furthermore, the material of the adhesive film includes epoxy resin or rubber resin, and the material of the conductive particles includes gold or nickel.

[0014] According to another aspect of the present application, a light-emitting device is provided, comprising the above-mentioned wafer bonding structure.

[0015] In an embodiment of the present invention, a first wafer, a second wafer and a conductive adhesive layer are provided; wherein, the first wafer and the second wafer both include bonding surfaces, the conductive adhesive layer includes conductive particles, and the bonding surface of the first wafer and the bonding surface of the second wafer are bonded through the conductive adhesive layer, thereby achieving the goal of utilizing a flexible conductive adhesive layer as a bonding layer for the first wafer and the second wafer. When there are hard particles between the first wafer and the second wafer, the flexible adhesive film can wrap the hard particles, thereby avoiding the first wafer and the second wafer from cracking due to hard impurities during bonding, thereby achieving the technical effect of improving the product yield of the first wafer and the second wafer during bonding, and further solving the problem in the related art that the wafers are prone to cracking after being stacked and bonded through the hard metal layer, resulting in low product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention and to make the other features, purposes, and advantages of the present invention more apparent. The accompanying drawings and descriptions of the exemplary embodiments of the present invention are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0017] Figure 1 It is a schematic diagram of the structure of bonding MicroLED wafer and CMOS wafer in the prior art;

[0018] Figure 2 is a schematic diagram of a bonding structure of a wafer according to an embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of a wafer bonding structure according to an embodiment of the present invention;

[0020] Figure 4 is a schematic diagram of a wafer bonding structure according to another embodiment of the present invention;

[0021] Among them, 1 Micro-LED wafer, 2 CMOS wafer, 3 hard metal layer, 4 first wafer, 5 second wafer, 6 conductive adhesive layer, 60 conductive particles, 7 bonding surface, 8 exhaust holes, and 80 speaker opening ends. DETAILED DESCRIPTION

[0022] In order to help those skilled in the art better understand the present invention, 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 embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the purposes of describing the embodiments of the present invention.

[0024] In this utility model, the terms "upper," "lower," "inner," and the like indicate positions or locations based on those shown in the accompanying drawings. These terms are intended to better describe the utility model and its embodiments and are not intended to limit the devices, elements, or components indicated to specific positions, or to their construction or operation in a specific position.

[0025] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0026] Furthermore, the terms "disposed," "provided with," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a removable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediary, or an internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0027] Additionally, the term "plurality" shall mean two or more.

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] like Figure 1As shown, in Micro-LED, since both the Micro-LED wafer 1 and the CMOS wafer 2 are made of hard and brittle materials, when bonding through the hard metal layer 3, it is often easy for the hard and brittle materials to produce dark cracks due to the presence of fine hard particles between the two wafers or the uneven warping themselves.

[0030] In order to solve the above technical problems, Figure 2 As shown, the embodiment of the present invention provides a wafer bonding structure, comprising: a first wafer 4, a second wafer 5 and a conductive adhesive layer 6; wherein,

[0031] The first wafer 4 and the second wafer 5 both include a bonding surface 7 . The conductive adhesive layer 6 includes conductive particles 60 . The bonding surface 7 of the first wafer 4 and the bonding surface 7 of the second wafer 5 are bonded via the conductive adhesive layer 6 .

[0032] In this embodiment, the first wafer 4 and the second wafer 5 are bonded in a stacked manner. When the second wafer 5 is stacked on the first wafer 4, the lower surface of the first wafer 4 and the upper surface of the second wafer 5 serve as bonding surfaces 7. The bonding surfaces 7 of the two wafers need to be bonded through a bonding layer. In this embodiment, the bonding layer is a conductive adhesive layer 6. The conductive adhesive layer 6 is flexible as a whole. Conductive particles 60 are dispersed in the conductive adhesive layer 6. The conductive particles 60 serve as a conductive material for the first wafer 4 and the second wafer 5 to maintain electrical contact after bonding. After using the flexible conductive adhesive layer 6 as the bonding layer, when there are hard particles between the bonding surfaces 7 of the first wafer 4 and the second wafer 5, the flexible conductive adhesive can wrap the hard particles, thereby avoiding problems such as cracking of the first wafer 4 and the second wafer 5 due to hard particles during bonding, thereby improving product yield.

[0033] Specifically, during bonding, a qualified first wafer 4 and second wafer 5 can be prepared first, and the first wafer 4 and second wafer 5 can be pre-treated, such as cleaning, plasma activation of the surface and other treatments. Then, a flexible conductive adhesive material is spin-coated or printed on the bonding surface 7 of the first wafer 4 or the second wafer 5 so that it is evenly coated on the bonding surface 7. The coating thickness can be adjusted according to the process requirements. After uniform coating, the residual adhesive on the edge of the wafer is cleaned, and pre-cured by heating to shape the flexible conductive adhesive material to form a conductive adhesive layer 6. Then, through a wafer bonding machine, under certain vacuum, temperature and pressure conditions, the first wafer 4 and the second wafer 5 are bonded, and the conductive adhesive layer 6 is cured, so that the first wafer 4 and the second wafer 5 are electrically contacted and conductive, and a permanent bond is achieved.

[0034] In this embodiment, the first wafer 4 may be a Micro-LED wafer, and the second wafer 5 may be a silicon-based CMOS wafer.

[0035] This embodiment achieves the goal of utilizing the flexible conductive adhesive layer 6 as the bonding layer for the first wafer 4 and the second wafer 5. When there are hard particles between the first wafer 4 and the second wafer 5, the flexible adhesive film in the conductive adhesive layer 6 can wrap the hard particles, thereby avoiding the first wafer 4 and the second wafer 5 from cracking due to hard impurities during bonding, thereby achieving the technical effect of improving the product yield of the first wafer 4 and the second wafer 5 during bonding, and further solving the problem in the related art that the wafers are prone to cracking after being stacked and bonded through the hard metal layer 3, resulting in low product yield.

[0036] When the conductive adhesive layer 6 is used as the bonding layer, bubbles may be present during the curing process of the conductive adhesive layer 6, resulting in uneven bonding between the two wafers. Figure 3 As shown, in this embodiment, an exhaust hole 8 is provided in at least one of the first wafer 4 and the second wafer 5 , and the exhaust hole 8 extends to the bonding surface 7 of the corresponding wafer.

[0037] Specifically, a conductive adhesive can be pre-coated on the bonding surface 7 of the first wafer 4 and pre-cured by heating to form a conductive adhesive layer 6. A vent 8 can be provided on the second wafer 5. During the curing process of the conductive adhesive layer 6 during bonding, air between the conductive adhesive layer 6 and the bonding surface 7 of the second wafer 5 due to curing can be discharged through the vent 8, allowing the conductive adhesive layer 6 to be completely adhered to the bonding surface 7 of the second wafer 5, thereby ensuring uniform bonding between the first wafer 4 and the second wafer 5, further improving product yield.

[0038] It is understandable that a conductive adhesive may be pre-coated on the bonding surface 7 of the second wafer 5 and pre-cured by heating to form a conductive adhesive layer 6 , and accordingly, an exhaust hole 8 may be opened on the first wafer 4 .

[0039] In one embodiment, when the first wafer is a 4LED wafer and the second wafer 5 is a CMOS wafer, it is preferred to open an exhaust hole 8 on the second wafer 5 .

[0040] like Figure 3 As shown, in one embodiment of the vent hole 8, the axis of the vent hole 8 is perpendicular to the bonding surface 7 of the corresponding wafer and passes through the wafer, that is, the openings at both ends of the vent hole 8 are respectively located on the bonding surface 7 of the wafer and the surface opposite to the bonding surface 7. In another embodiment of the vent hole 8, the vent hole 8 can be configured as an L-shape, that is, one end of the vent hole 8 is located on the bonding surface 7 of the wafer, and the other end is located on the side of the wafer. To facilitate processing and minimize the length of the vent hole 8, in this embodiment, it is preferred that the axis of the vent hole 8 is perpendicular to the bonding surface 7 of the corresponding wafer and passes through the wafer.

[0041] To maximize air removal during the curing process of the conductive adhesive layer 6, multiple vent holes 8 are provided in this embodiment, spaced apart. The spacing, diameter, and arrangement of adjacent vent holes 8 can be designed based on actual needs and are not limited in this embodiment. Furthermore, the vent holes 8 should be positioned to avoid electronic circuitry within the corresponding wafer. If the wafer contains electronic devices, these should also be avoided.

[0042] To further facilitate the discharge of air, Figure 4 As shown, in this embodiment, a trumpet-shaped opening end is provided on one end of the exhaust hole 8 close to the bonding surface 7. During bonding, the trumpet-shaped opening end is conducive to the convergence of air, thereby making it easier for air to be discharged through the exhaust hole 8.

[0043] Because the first wafer 4 and the second wafer 5 are stacked and bonded, the conductive adhesive layer 6 in this embodiment has unidirectional conductivity, with the conductive direction perpendicular to the bonding surface 7. When the first wafer 4 is bonded above the second wafer 5, and the first wafer 4 is an LED wafer and the second wafer 5 is a CMOS wafer, the conductive adhesive layer 6 conducts from the second wafer 5 to the first wafer 4.

[0044] Furthermore, the conductive adhesive layer is made of a flexible material. In one embodiment, the conductive adhesive layer 6 further comprises an adhesive film in which the conductive particles 60 are dispersed. The adhesive film is made of epoxy resin or rubber resin, and the conductive particles are made of gold or nickel.

[0045] According to another aspect of the present application, a light-emitting device is provided, comprising the above-mentioned wafer bonding structure.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A wafer bonding structure, characterized in that: include: A first wafer, a second wafer and a conductive adhesive layer; wherein, The first wafer and the second wafer both include bonding surfaces, the conductive adhesive layer includes conductive particles, and the bonding surface of the first wafer and the bonding surface of the second wafer are bonded via the conductive adhesive layer.

2. The wafer bonding structure according to claim 1, wherein: An exhaust hole is formed in the second wafer, and the exhaust hole extends to the bonding surface of the second wafer.

3. The wafer bonding structure according to claim 2, wherein: The exhaust holes are arranged in a plurality and distributed at intervals.

4. The wafer bonding structure according to claim 2, wherein: A trumpet-shaped opening end is provided on one end of the exhaust hole close to the bonding surface.

5. The wafer bonding structure according to claim 2, wherein: The axis of the exhaust hole is perpendicular to the bonding surface.

6. The wafer bonding structure according to any one of claims 2 to 5, characterized in that: The first wafer is configured as a Micro-LED wafer, the second wafer is configured as a silicon-based CMOS wafer, and the exhaust hole is provided in the second wafer.

7. The wafer bonding structure according to claim 1, wherein: The conductive adhesive layer is made of flexible material.

8. The wafer bonding structure according to claim 7, wherein: The conductive adhesive layer further includes an adhesive film, and the conductive particles are dispersed in the adhesive film.

9. The wafer bonding structure according to claim 8, wherein: The material of the adhesive film includes epoxy resin or rubber resin, and the material of the conductive particles includes gold or nickel.

10. A light emitting device, characterized in that: The wafer bonding structure comprises the wafer bonding structure according to any one of claims 1 to 9.

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