Hybrid Bonded Structures and Their Formation Methods

Abstract

This application discloses a hybrid bonding structure and its formation method. The hybrid bonding structure includes: a first bonding layer disposed on the surface of a first wafer, comprising a first organic dielectric layer and a first metal layer; and a second bonding layer disposed on the surface of a second wafer, comprising a second organic dielectric layer and a second metal layer. The mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the grain size in the first metal layer is larger than that in the second metal layer. The second wafer is located on the first wafer, and the second bonding layer of the second wafer is bonded to the first bonding layer of the first wafer. Specifically, the second metal layer in the second bonding layer is bonded to a corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to a first organic dielectric layer in the first bonding layer. This improves the bonding reliability and bonding strength when using organic materials for hybrid bonding.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging, and more particularly to a hybrid bonding structure and a method for forming the same. Background Technology

[0002] Electronic devices are rapidly evolving towards higher integration, higher assembly density, and higher operating speeds. Hybrid bonding technology is a core technology in advanced semiconductor packaging, specifically 3D / 2.5D packaging. Hybrid bonding combines metal-to-metal bonding (e.g., Cu-Cu bonding) and dielectric-to-dielectric bonding in the same process step to achieve wafer-level or chip-level bonding. Eliminating the need for solder bumps, hybrid bonding directly integrates electrical interconnection, mechanical bonding, and thermal conduction between two wafers or chips, overcoming the connection density bottleneck of traditional bonding technologies and making it suitable for high-performance computing (HPC) and other high-end applications.

[0003] The media materials used in hybrid bonding include both inorganic and organic materials. Compared to hybrid bonding using inorganic materials, hybrid bonding using organic materials offers advantages such as stronger resistance to particulate contamination and lower temperature requirements. However, existing hybrid bonding structures obtained using organic materials still have issues with improved bonding reliability and bond strength. Summary of the Invention

[0004] The purpose of this application is to provide a hybrid bonding structure and a method for forming the same, which improves the bonding reliability and bonding strength when using organic materials for hybrid bonding.

[0005] To achieve the above objectives, in a first aspect, embodiments of this application provide a hybrid bonding structure, including:

[0006] A first wafer, wherein a first bonding layer is provided on the surface of the first wafer, the first bonding layer comprising: a first organic dielectric layer and a plurality of discrete first metal layers located in the first organic dielectric layer, wherein the surface of the first organic dielectric layer away from the first wafer exposes the surface of the first metal layer away from the first wafer. A second wafer has a second bonding layer on its surface. The second bonding layer includes a second organic dielectric layer and a plurality of discrete second metal layers located in the second organic dielectric layer. The surface of the second organic dielectric layer away from the second wafer exposes the surface of the second metal layer away from the second wafer. The mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the size of the grains in the first metal layer is larger than that in the second metal layer. The second wafer is located on the first wafer, and the second bonding layer of the second wafer is bonded to the first bonding layer of the first wafer. The second metal layer in the second bonding layer is bonded to the corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to the first organic dielectric layer in the first bonding layer.

[0007] In some embodiments of this application, the mechanical properties of the first organic medium layer being stronger than those of the second organic medium layer include: the tensile strength of the first organic medium layer being greater than that of the second organic medium layer, and the elastic modulus of the first organic medium layer being greater than that of the second organic medium layer.

[0008] In some embodiments of this application, the tensile strength of the first organic dielectric layer ranges from 100 MPa to 150 MPa, and the tensile strength of the second organic dielectric layer ranges from 60 MPa to 90 MPa. The elastic modulus of the first organic dielectric layer ranges from 2.5 GPa to 4.5 GPa, and the elastic modulus of the second organic dielectric layer ranges from 2.0 GPa to 2.8 GPa.

[0009] In some embodiments of this application, the material of the first organic dielectric layer is the same as or different from the material of the second organic dielectric layer; the dielectric constant of the first organic dielectric layer and the second organic dielectric layer is less than or equal to 3.5.

[0010] In some embodiments of this application, the material of the first organic dielectric layer includes polyimide resin, polybenzoxazole resin, or polyimide-imide resin; the material of the second organic dielectric layer includes benzocyclobutene resin, fluorinated polyimide resin, or fluorocarbon resin.

[0011] In some embodiments of this application, the thickness of the first organic dielectric layer is the same as the thickness of the first metal layer, and both are greater than the thickness of the second organic dielectric layer; the thickness of the second organic dielectric layer is the same as the thickness of the second metal layer.

[0012] In some embodiments of this application, the thickness of the first organic dielectric layer and the first metal layer ranges from 60 micrometers to 100 micrometers; the thickness of the second organic dielectric layer and the second metal layer ranges from 10 micrometers to 30 micrometers.

[0013] In some embodiments of this application, the materials of the first metal layer and the second metal layer include one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni.

[0014] In some embodiments of this application, the size of the grains in the first metal layer ranges from 1.6 micrometers to 2 micrometers.

[0015] In some embodiments of this application, the grain size in the second metal layer ranges from 150 nanometers to 200 nanometers.

[0016] In some embodiments of this application, the surface roughness of the first metal layer on the side away from the first wafer ranges from 3 nanometers to 4.7 nanometers.

[0017] Secondly, embodiments of this application also provide a method for forming a hybrid bonding structure, comprising: A first wafer is provided, and a first bonding layer is formed on the surface of the first wafer. The first bonding layer includes: a first organic dielectric layer and a plurality of discrete first metal layers located in the first organic dielectric layer, wherein the surface of the first organic dielectric layer away from the first wafer exposes the surface of the first metal layers away from the first wafer. A second wafer is provided, and a second bonding layer is formed on the surface of the second wafer. The second bonding layer includes: a second organic dielectric layer and a plurality of discrete second metal layers located in the second organic dielectric layer, wherein the surface of the second organic dielectric layer away from the second wafer exposes the surface of the second metal layer away from the second wafer; wherein the mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the size of the grains in the first metal layer is larger than the size of the grains in the second metal layer. The second wafer is placed above the first wafer and aligned and bonded to the first wafer, such that the second metal layer in the second bonding layer is bonded to the corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to the first organic dielectric layer in the first bonding layer.

[0018] In some embodiments of this application, the mechanical properties of the first organic medium layer being stronger than those of the second organic medium layer include: the tensile strength of the first organic medium layer being greater than that of the second organic medium layer, and the elastic modulus of the first organic medium layer being greater than that of the second organic medium layer.

[0019] In some embodiments of this application, the formation process of the first bonding layer includes: A plurality of discrete first metal layers are formed on the surface of the first wafer; A first organic dielectric layer is formed covering the first metal layer; The first organic dielectric layer is thinned using a chemical mechanical polishing process until the top surface of the first metal layer is exposed, and after the chemical mechanical polishing process, the top surface of the remaining first organic dielectric layer is lower than the top surface of the first metal layer.

[0020] In some embodiments of this application, the process of forming the first metal layer includes: A first seed layer is formed on the first wafer; A first photoresist layer is formed on the first seed layer, and the first photoresist layer has a plurality of discrete first openings that expose a portion of the top surface of the first seed layer. A first metal layer is formed in the first opening using a first electroplating process; Remove the first photoresist layer and remove the first seed layer on both sides of the first metal layer.

[0021] In some embodiments of this application, the material of the first metal layer includes one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni; The grain size in the first metal layer ranges from 1.6 micrometers to 2 micrometers.

[0022] In some embodiments of this application, the electrolyte used in the first electroplating process includes a basic electrolyte and functional additives. The basic electrolytes include copper sulfate and sulfuric acid; The functional additives include one or more of chloride ions, polyethylene glycol, and sodium dithiodipropane sulfonate. The anode used in the first electroplating process is a phosphor bronze electrode, and the current is a direct current of 3.8-4.2 amperes per square decimeter.

[0023] In some embodiments of this application, the material of the first organic dielectric layer includes polyimide resin, polybenzoxazole resin, or polyimide-imide resin.

[0024] In some embodiments of this application, the first organic dielectric layer is formed using a spin coating process and a curing process.

[0025] In some embodiments of this application, the formation process of the second bonding layer includes: A plurality of discrete second metal layers are formed on the surface of the second wafer; A second organic dielectric layer is formed covering the second metal layer; The second organic dielectric layer is thinned using a chemical mechanical polishing process until the top surface of the second metal layer is exposed, and after the chemical mechanical polishing process, the top surface of the remaining second organic dielectric layer is lower than the top surface of the second metal layer.

[0026] In some embodiments of this application, the process of forming the second metal layer includes: A second seed layer is formed on the second wafer; A second photoresist layer is formed on the second seed layer, and the second photoresist layer has a plurality of discrete second openings that expose a portion of the top surface of the second seed layer. A second metal layer is formed in the second opening using a second electroplating process; Remove the second photoresist layer and remove the second seed layer on both sides of the second metal layer.

[0027] In some embodiments of this application, the material of the second metal layer includes one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni; The grain size in the second metal layer ranges from 150 nanometers to 200 nanometers.

[0028] In some embodiments of this application, the electrolyte used in the second electroplating process includes a basic electrolyte and functional additives; The basic electrolytes include copper sulfate and sulfuric acid; The functional additives include one or more of chloride ions, polydithiopropane sulfonic acid, polyetherimide, and benzimidazole; The anode used in the second electroplating process is a platinum electrode, and the current is a pulsed current of 4.8-5.2 amperes per square decimeter, with a pulse on-time range of 7 ms-9 ms and a pulse off-time range of 18 ms-22 ms.

[0029] In some embodiments of this application, the material of the second organic dielectric layer includes benzocyclobutene resin, fluorinated polyimide resin, or fluorocarbon resin.

[0030] In some embodiments of this application, the second organic dielectric layer is formed using a spin coating process and a curing process.

[0031] In some embodiments of this application, after removing the first photoresist layer and the first seed layers on both sides of the first metal layer, the process includes: The surface of the first bonding layer away from the first wafer is ground or polished to reduce the surface roughness of the first bonding layer away from the first wafer to 3-4.7 nanometers.

[0032] In some embodiments of this application, when the second wafer is placed above the first wafer and aligned and bonded to the first wafer, the second wafer is located directly above the first wafer; The bonding process employs a hot-press bonding process, with a time range of 0.9 hours to 1.2 hours, a temperature range of 240°C to 260°C, and a pressure range of 7 MPa to 9 MPa.

[0033] In some embodiments of this application, after bonding the first wafer and the second wafer, the method further includes: The bonded first wafer and the second wafer are subjected to annealing treatment. The annealing treatment temperature range is 270℃-290℃, and the treatment time range is 35 minutes-45 minutes.

[0034] The beneficial effects of this application are: The present application discloses a hybrid bonding structure and a method for forming the same. The method includes: providing a first wafer; forming a first bonding layer on the surface of the first wafer, the first bonding layer comprising: a first organic dielectric layer and a plurality of discrete first metal layers located within the first organic dielectric layer, wherein the surface of the first organic dielectric layer away from the first wafer exposes the surface of the first metal layers away from the first wafer; providing a second wafer; forming a second bonding layer on the surface of the second wafer, the second bonding layer comprising: a second organic dielectric layer and a plurality of discrete second metal layers located within the second organic dielectric layer, wherein the surface of the second organic dielectric layer away from the second wafer exposes the surface of the second metal layers away from the second wafer; wherein the mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the grain size in the first metal layer is larger than that in the second metal layer; placing the second wafer above the first wafer and aligning and bonding it with the first wafer, such that the second metal layer in the second bonding layer is bonded to a corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to a first organic dielectric layer in the first bonding layer.

[0035] In the method for forming the hybrid bonding structure described above in this application, firstly, during bonding, the second wafer is located above the first wafer and is pressed onto the first wafer. Since the mechanical properties of the first organic dielectric layer on the first wafer are stronger than those of the second organic dielectric layer on the second wafer, the first dielectric layer can better withstand the pressure from the second wafer to provide stronger mechanical support for the second wafer, and the first organic dielectric layer can better buffer the stress generated during the bonding process, thereby preventing the first organic dielectric layer from collapsing or breaking during the bonding process, thus preventing delamination defects in the first organic dielectric layer, and preventing poor contact defects caused by the inability to effectively contact between metals, thereby improving the reliability of the bonding. Secondly, since the first metal layer is located below the second metal layer, and since the size of the grains in the first metal layer is larger than the size of the grains in the second metal layer (the energy level of a metal with a larger grain size will be smaller than the energy level of the same metal with a smaller grain size, i.e., the energy level of the first metal layer is smaller than the energy level of the second metal layer), during the bonding process, the metal will migrate from the high energy level to the low energy level. That is, the small grains in the second metal layer will migrate into the first metal layer. Furthermore, since the high-energy second metal layer is located above the first metal layer, this is more conducive to the migration of the small grains in the second metal layer into the first metal layer, thereby achieving unidirectional cross-interface grain growth more quickly, effectively eliminating the original metal bonding interface and void generation, and thus improving the bonding strength between metals. Furthermore, during the bonding process, since the expansion of the first metal layer is greater than that of the second metal layer (for the same metal material, larger grain size makes it easier to expand when heated), in this application, the first metal layer with a larger grain size (larger than the grain size of the second metal layer) and the first organic dielectric layer with stronger mechanical properties (stronger mechanical properties than the second organic dielectric layer) are both disposed on the surface of the first wafer. Therefore, the first organic dielectric layer can also better suppress the lateral expansion of the first metal layer, reduce the lateral displacement of the first metal layer, improve the accuracy of the bonding position of the first metal layer and the second metal layer, and further improve the bonding strength. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In addition, in the following drawings, the components are not necessarily drawn to scale, and components with similar related characteristics or features may have the same or similar reference numerals.

[0037] Figure 1 This is a schematic diagram of the structure after a photoresist layer is coated on the surface of the first seed layer of the first wafer in some embodiments of the present application for forming a hybrid bonding structure. Figure 2 This is a schematic diagram of the structure after the first opening is formed in the method for forming a hybrid bonding structure provided in some embodiments of this application; Figure 3 This is a schematic diagram of the structure after the formation of the first metal layer in the method for forming the hybrid bonding structure provided in some embodiments of this application; Figure 4This is a schematic diagram of the structure after removing the first seed layer in the method for forming a hybrid bonding structure provided in some embodiments of this application; Figure 5 This is a schematic diagram of the structure after the formation of the first organic dielectric layer in the method for forming the hybrid bonding structure provided in some embodiments of this application; Figure 6 This is a schematic diagram of the structure after thinning the first organic dielectric layer and the first metal layer in the method for forming the hybrid bonding structure provided in some embodiments of this application; Figure 7 This is a schematic diagram of the structure after a photoresist layer is coated on the surface of the first seed layer of the second wafer in the method for forming a hybrid bonding structure provided in some embodiments of this application. Figure 8 This is a schematic diagram of the structure after the second opening is formed in the method for forming a hybrid bonding structure provided in some embodiments of this application; Figure 9 This is a schematic diagram of the structure after the formation of the second metal layer in the method for forming the hybrid bonding structure provided in some embodiments of this application; Figure 10 This is a schematic diagram of the structure after removing the second seed layer in the method for forming a hybrid bonding structure provided in some embodiments of this application; Figure 11 This is a schematic diagram of the structure after the formation of the second organic dielectric layer in the method for forming the hybrid bonding structure provided in some embodiments of this application; Figure 12 This is a schematic diagram of the structure after thinning the second organic dielectric layer and the second metal layer in the method for forming the hybrid bonding structure provided in some embodiments of this application; Figure 13 This is a schematic diagram of the structure after aligning the first wafer and the second wafer in the method for forming a hybrid bonding structure provided in some embodiments of this application; Figure 14 This is a schematic diagram of the structure after bonding the first wafer and the second wafer in the method for forming a hybrid bonding structure provided in some embodiments of this application; Figure 15 This is a schematic diagram of the process for forming a hybrid bonding structure provided in some embodiments of this application.

[0038] Explanation of reference numerals in the attached figures: 1: First wafer; 11: First bonding layer; 12: First organic dielectric layer; 13: First metal layer; 14: First seed layer; 15: First photoresist layer; 16: First opening; 2: Second wafer; 21: Second bonding layer; 22: Second organic dielectric layer; 23: Second metal layer; 24: Second seed layer; 25: Second photoresist layer; 26: Second opening. Detailed Implementation

[0039] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] In the description of this application, it should be noted that the use of terms such as "first" and "second" to define objects (such as elements, components, regions, layers, doping types and / or parts) is merely for the purpose of distinguishing different objects, and is not necessarily used to describe a specific order or sequence, unless the context clearly indicates otherwise.

[0042] In the description of this application, it should be understood that the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “compose” and / or “comprise” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0043] In the description of this application, it should also be noted that when a component is referred to as "on another component," "connected to another component," or "in contact with another component," it can mean not only that a component is directly on, directly connected to, or directly in contact with the other component, but also that an intermediate component can be inserted between the two components. Furthermore, "connection" includes not only fixed connections but also detachable connections or integral connections. Similarly, when an element is referred to as "electrically connected," "electrically contacted," "electrically coupled," or "electrically coupled to" another element, the two elements can be in direct electrical contact or electrical coupling, or they can be in electrical contact or electrical coupling through an intermediate component.

[0044] In the description of this application, it should also be noted that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0045] Furthermore, in the description of this application, spatial relation terms such as "below," "under," "below," "below," "below," "above," "on the upper surface of," "above," etc., can be used to describe the spatial positional relationship between one element or feature shown in the figures and other elements or features. It should be understood that spatial relation terms, in addition to the orientation shown in the figures, also include different orientations of elements or features in use and operation. For example, if an element or feature in the figures is flipped or inverted, an element or feature described as "below" or "below" other elements or features will be oriented "above" other elements or features. Furthermore, elements may also include other orientations (e.g., rotated by an angle or other orientations).

[0046] The structure of the embodiments of this application should not be limited to the specific shape shown in the accompanying drawings, but includes shape deviations due to, for example, manufacturing techniques.

[0047] It is understood that in some of the accompanying drawings of this application, adjacent films with the same processing material are drawn as connected to make them resemble the actual structure.

[0048] In current methods of hybrid bonding using organic materials, the organic materials are typically PI (polyimide) resin or BCB (benzocyclobutene) resin. Furthermore, during bonding, the organic materials on both bonding objects are of the same or homogeneous material and properties (PI with the same properties is bonded to PI, and BCB with the same properties is bonded to BCB). Research has found that, on the one hand, during bonding with homogeneous organic materials, the lower organic material experiences greater pressure than the upper organic material, making it more prone to collapse or fracture. This can lead to delamination defects in the lower organic material and poor contact defects due to ineffective metal-to-metal contact, thus affecting the reliability of the bond. On the other hand, when bonding metals to metal, since both use the same grain size, an original metal-to-metal bonding interface still exists after bonding, thus affecting the bond strength.

[0049] Therefore, this application provides a hybrid bonding structure in one embodiment. Please refer to... Figure 14 The wafer comprises: a first wafer 1, on the surface of which a first bonding layer 11 is disposed, the first bonding layer 11 comprising: a first organic dielectric layer 12 and a plurality of discrete first metal layers 13 located within the first organic dielectric layer 12, wherein the surface of the first organic dielectric layer 12 away from the first wafer 1 exposes the surface of the first metal layers 13 away from the first wafer 1; and a second wafer 2, on the surface of which a second bonding layer 21 is disposed, the second bonding layer 21 comprising: a second organic dielectric layer 22 and a plurality of discrete second metal layers 23 located within the second organic dielectric layer 22, wherein the surface of the second organic dielectric layer 22 away from the second wafer 2 exposes the surface of the first metal layers 13 away from the first wafer 1; and a second wafer 2, on the surface of which a second bonding layer 21 is disposed, the second bonding layer 22 comprising: a second organic dielectric layer 22 and a plurality of discrete second metal layers 23 located within the second organic dielectric layer 22, wherein the surface of the second organic dielectric layer 22 away from the second wafer 2 exposes the surface of the first metal layers 13 away from the first wafer 1. The second metal layer 23 is located on the surface of the second wafer 2 away from the second wafer 1; wherein the mechanical properties of the first organic dielectric layer 12 are stronger than those of the second organic dielectric layer 22, and the size of the grains in the first metal layer 13 is larger than that in the second metal layer 23; the second wafer 2 is located on the first wafer 1, and the second bonding layer 21 of the second wafer 2 is bonded to the first bonding layer 11 of the first wafer 1, wherein the second metal layer 23 in the second bonding layer 21 is bonded to the corresponding first metal layer 13 in the first bonding layer 11, and the second organic dielectric layer 22 in the second bonding layer 21 is bonded to the first organic dielectric layer 12 in the first bonding layer 11.

[0050] In the hybrid bonding structure described above in this application, firstly, the second wafer 2 is located above the first wafer 1. The first wafer 1 and the second wafer 2 are bonded together through the first bonding layer 11 and the second bonding layer 21. Since the mechanical properties of the first organic dielectric layer 12 on the first wafer 1 are stronger than those of the second organic dielectric layer 22 on the second wafer 2, the first dielectric layer can better withstand the pressure from the second wafer 2 to provide stronger mechanical support for the second wafer 2. The first organic dielectric layer 12 can also better buffer the stress generated during the bonding process, thereby preventing the first organic dielectric layer 12 from collapsing or breaking during the bonding process. This avoids delamination defects in the first organic dielectric layer 12 and poor contact defects caused by ineffective contact between metals, thus improving the reliability of the bonding. Secondly, since the first metal layer 13 is located below the second metal layer 23, and since the size of the grains in the first metal layer 13 is larger than the size of the grains in the second metal layer 23 (the energy level of a metal with a larger grain size will be smaller than the energy level of the same metal with a smaller grain size, i.e., the energy level of the first metal layer 13 is smaller than the energy level of the second metal layer 23), during the bonding process, the metal will migrate from the high energy level to the low energy level. That is, the small grains in the second metal layer 23 will migrate into the first metal layer 13. Furthermore, since the high-energy second metal layer 23 is located above the first metal layer 13, this is more conducive to the migration of the small grains in the second metal layer 23 into the first metal layer 13, thereby achieving unidirectional cross-interface grain growth more quickly, effectively eliminating the generation of the original metal bonding interface and voids, and thus improving the bonding strength between metals.

[0051] The structure of the aforementioned hybrid bonding structure will be described in detail below with reference to the accompanying drawings.

[0052] Continue to refer to Figure 14 The first wafer 1 serves as the structural substrate supporting the hybrid bonding structure. A first bonding layer 11 is disposed on the surface of the first wafer 1. The first bonding layer 11 includes a first organic dielectric layer 12 and a plurality of discrete first metal layers 13 located within the first organic dielectric layer 12. The first organic dielectric layer 12 electrically isolates adjacent first metal layers 13, preventing short circuits and signal crosstalk, while simultaneously providing mechanical support for the second wafer 2, ensuring the stability of the hybrid bonding structure. The first metal layers 13 serve as conductive interconnect units, bonded to the second metal layer 23 to form an electrical path, enabling electrical signal transmission between the first wafer 1 and the second wafer 2.

[0053] In this application, the mechanical properties of the first organic dielectric layer 12 are stronger than those of the second organic dielectric layer 22, which enables the first organic dielectric layer 12 to have a stronger stress buffering effect and provide stronger mechanical support for the second wafer 2. This avoids the first organic dielectric layer 12 from collapsing or breaking during the bonding process, thereby avoiding delamination defects in the first organic dielectric layer 12 and poor contact defects caused by ineffective contact between metals, thus improving the reliability of bonding.

[0054] In some embodiments, the mechanical properties of the first organic dielectric layer 12 being stronger than those of the second organic dielectric layer 22 include: the tensile strength of the first organic dielectric layer 12 being greater than that of the second organic dielectric layer 22, and the elastic modulus of the first organic dielectric layer 12 being greater than that of the second organic dielectric layer 22.

[0055] In a specific example, the tensile strength of the first organic dielectric layer 12 ranges from 100 MPa to 150 MPa, and the tensile strength of the second organic dielectric layer 22 ranges from 60 MPa to 90 MPa; the elastic modulus of the first organic dielectric layer 12 ranges from 2.5 GPa to 4.5 GPa, and the elastic modulus of the second organic dielectric layer 22 ranges from 2.0 GPa to 2.8 GPa. That is, the first organic dielectric layer 12 has high tensile strength and elastic modulus, giving it strong toughness, enabling it to withstand greater pressure and buffer greater stress. In some embodiments, when the mechanical properties of the first organic dielectric layer 12 are stronger than those of the second organic dielectric layer 22, the material of the first organic dielectric layer 12 may be the same as or different from that of the second organic dielectric layer 22, and the dielectric constants of the first organic dielectric layer 12 and the second organic dielectric layer 22 are less than or equal to 3.5. Specifically, the dielectric constant of the first organic dielectric layer 12 may be greater than, equal to, or less than the dielectric constant of the second organic dielectric layer 22, and all of them are less than or equal to 3.5. That is, the dielectric constants of the first organic dielectric layer 12 and the second organic dielectric layer 22 are both low, which can reduce signal loss and improve the electrical performance of the hybrid bonding structure.

[0056] In some embodiments, when the mechanical properties of the first organic dielectric layer 12 are stronger than those of the second organic dielectric layer 22, the tensile strength of the first organic dielectric layer 12 ranges from 100 MPa to 150 MPa, and the tensile strength of the second organic dielectric layer 22 ranges from 60 MPa to 90 MPa. The material of the first organic dielectric layer 12 is the same as or different from that of the second organic dielectric layer 22, and the dielectric constants of the first organic dielectric layer 12 and the second organic dielectric layer 22 are less than or equal to 3.5. Therefore, the hybrid bonding structure of this application not only has the aforementioned effect of improving bonding reliability, but also takes into account both mechanical and electrical properties.

[0057] In some specific embodiments, the material of the first organic dielectric layer 12 that satisfies the aforementioned characteristic requirements includes polyimide resin, polybenzoxazole resin, or polyimide-imide resin. The material of the second organic dielectric layer 22 that satisfies the aforementioned characteristic requirements includes benzocyclobutene resin, fluorinated polyimide resin, or fluorocarbon resin.

[0058] In a specific example, the first organic dielectric layer 12 is made of polyimide resin, with a tensile strength ranging from 100 MPa to 150 MPa, an elastic modulus ranging from 2.5 GPa to 4.5 GPa, and a dielectric constant K ranging from 2.5 to 3.5. The second organic dielectric layer 22 is made of benzocyclobutene resin, with a tensile strength ranging from 60 MPa to 90 MPa, an elastic modulus ranging from 2.0 GPa to 2.8 GPa, and a dielectric constant K ranging from 1.8 to 2.5. When using organic materials with the aforementioned two properties, the first organic dielectric layer 12 has the advantages of high mechanical properties and good thermal stability, while the second organic dielectric layer 22, benzocyclobutene resin, has the characteristics of low dielectric constant and low loss. Therefore, the hybrid bonding structure of this application not only has the aforementioned effect of improving bonding reliability, but also takes into account both mechanical and electrical properties. That is, while improving the mechanical stability of the bonding structure, it reduces signal loss (in existing bonding, since organic materials with the same properties are used, it is impossible to take into account both mechanical and electrical properties).

[0059] In some embodiments, continue to refer to Figure 14The thickness of the first organic dielectric layer 12 is the same as the thickness of the first metal layer 13, and both are greater than the thickness of the second organic dielectric layer 22; the thickness of the second organic dielectric layer 22 is the same as the thickness of the second metal layer 23, that is, the first organic dielectric layer 12, the first metal layer 13, the second organic dielectric layer 22, and the second metal layer 23, which are far from the surface of the first wafer 1, are all on the same plane after bonding.

[0060] On the one hand, when the thickness of the first organic dielectric layer 12 is greater than the thickness of the second organic dielectric layer 22, the mechanical properties of the first organic dielectric layer 12 can be further enhanced; on the other hand, when the thickness of the first organic dielectric layer 12 is the same as the thickness of the first metal layer 13, and the thickness of the second organic dielectric layer 22 is the same as the thickness of the second metal layer 23, the bonding surface is a continuous plane, which further improves the bonding strength.

[0061] In one specific example, the thickness of the first organic dielectric layer 12 and the first metal layer 13 ranges from 60 micrometers to 100 micrometers. The thickness of the second organic dielectric layer 22 and the second metal layer 23 ranges from 10 micrometers to 30 micrometers.

[0062] Continue to refer to Figure 14 In the first bonding layer 11, the size of the grains in the first metal layer 13 is larger than the size of the grains in the second metal layer 23. During the formation of the hybrid bonding structure of this application, when bonding is performed, since the first metal layer 13 is located below the second metal layer 23, and since the size of the grains in the first metal layer 13 is larger than the size of the grains in the second metal layer 23 (the energy level of the metal with larger grain size will be smaller than the energy level of the same metal with smaller grain size, that is, the energy level of the first metal layer 13 is smaller than the energy level of the second metal layer 23), during the bonding process, the metal will migrate from the high energy level to the low energy level. That is, the small-sized grains in the second metal layer 23 will migrate into the first metal layer 13. And since the high-energy second metal layer 23 is located above the first metal layer 13, this is more conducive to the migration of the small-sized grains in the second metal layer 23 into the first metal layer 13, thereby achieving unidirectional cross-interface grain growth more quickly, effectively eliminating the generation of the original metal bonding interface and voids, and thus improving the bonding strength between metals.

[0063] In some embodiments, the materials of the first metal layer 13 and the second metal layer 23 include one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni, and the grain size range of the first metal layer 13 is 1.6 micrometers to 2 micrometers, and the grain size range of the second metal layer 23 is 150 nanometers to 200 nanometers.

[0064] In a specific example, the materials of the first metal layer 13 and the second metal layer 23 include Cu, and the grain size in the first metal layer 13 made of Cu ranges from 1.6 micrometers to 2 micrometers, while the grain size in the second metal layer 23 made of Cu ranges from 150 nanometers to 200 nanometers. The grain size in the second metal layer 23 is smaller than that in the first metal layer 13, and within the aforementioned specific range, the surface activity of the second metal layer 23 is greater than that of the first metal layer 13. This facilitates the migration of smaller grains from the second metal layer 23 into the first metal layer 13, thereby achieving faster unidirectional cross-interface grain growth.

[0065] In some embodiments, the surface roughness of the first metal layer 13 on the side away from the first wafer 1 ranges from 3 nanometers to 4.7 nanometers.

[0066] Because the first metal layer 13 has a large thickness and large grain size, the surface roughness of the first metal layer 13 will be too large during the formation of the hybrid bonding structure. In order to reduce the surface roughness and improve the surface flatness to improve the bonding strength, it is necessary to mechanically grind and polish the surface of the first metal layer 13 away from the first wafer 1, so that the surface roughness of the surface of the first metal layer 13 away from the first wafer 1 is in the range of 3 nanometers to 4.7 nanometers, making the surface of the first metal layer 13 away from the first wafer 1 flatter and improving the bonding strength and stability.

[0067] Continue to refer to Figure 14 The second wafer 2 is used to bond with the first wafer 1 to form a stacked packaging structure, thereby increasing the device integration density and information interconnection density. The surface of the second wafer 2 is provided with a second bonding layer 21, which includes a second organic dielectric layer 22 and a plurality of discrete second metal layers 23 located in the second organic dielectric layer 22. The second organic dielectric layer 22 covers and separates each of the second metal layers 23, thereby achieving electrical isolation between adjacent second metal layers 23 and preventing short circuits and signal crosstalk. The second metal layer 23 serves as a conductive interconnection unit and is precisely aligned and bonded with the first metal layer 13 to form a stable and low-resistance conductive connection, thereby improving interconnection reliability and signal transmission performance and forming the complete hybrid bonding structure.

[0068] In a specific embodiment, the material of the second organic dielectric layer 22 includes benzocyclobutene resin, fluorinated polyimide resin or fluorocarbon resin. These materials have the characteristics of low dielectric constant, low loss and low hygroscopicity, which can reduce signal delay and loss in high-speed / high-frequency circuits.

[0069] Secondly, embodiments of this application provide a method for forming a hybrid bonding structure. Figure 15 This is a flowchart illustrating the method for forming hybrid bonding structures provided in some embodiments of this application. (Refer to...) Figure 15 The method for forming the hybrid bonding structure includes the following steps: Step S101: Provide a first wafer and form a first bonding layer on the surface of the first wafer. The first bonding layer includes: a first organic dielectric layer and a plurality of discrete first metal layers located in the first organic dielectric layer. The surface of the first organic dielectric layer away from the first wafer exposes the surface of the first metal layer away from the first wafer. Step S102: A second wafer is provided, and a second bonding layer is formed on the surface of the second wafer. The second bonding layer includes: a second organic dielectric layer and a plurality of discrete second metal layers located in the second organic dielectric layer. The surface of the second organic dielectric layer away from the second wafer exposes the surface of the second metal layer away from the second wafer. The mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the size of the grains in the first metal layer is larger than the size of the grains in the second metal layer. Step S103: Place the second wafer above the first wafer and align and bond it with the first wafer, such that the second metal layer in the second bonding layer is bonded to the corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to the first organic dielectric layer in the first bonding layer.

[0070] The method for forming the packaging structure is described in detail below with reference to the accompanying drawings in some embodiments.

[0071] First, refer to Figure 15 In conjunction with references Figure 6 In step S101, a first wafer 1 is provided, and a first bonding layer 11 is formed on the surface of the first wafer 1. The first bonding layer 11 includes a first organic dielectric layer 12 and a plurality of discrete first metal layers 13 located in the first organic dielectric layer 12. The surface of the first organic dielectric layer 12 away from the first wafer 1 exposes the surface of the first metal layers 13 away from the first wafer 1.

[0072] In some embodiments, reference Figures 4 to 6 The formation process of the first bonding layer 11 includes: A plurality of discrete first metal layers 13 are formed on the surface of the first wafer 1; A first organic dielectric layer 12 is formed covering the first metal layer 13; The first organic dielectric layer 12 is thinned using a chemical mechanical polishing process until the top surface of the first metal layer 13 is exposed, and after the chemical mechanical polishing process, the top surface of the remaining first organic dielectric layer 12 is lower than the top surface of the first metal layer 13.

[0073] The purpose of ensuring that the top surface of the remaining first organic dielectric layer 12 is lower than the top surface of the first metal layer 13 after the chemical mechanical polishing process is as follows: Since the coefficient of thermal expansion of the first organic dielectric layer 12 is greater than that of the first metal layer 13, the expansion rate and amount of the first organic dielectric layer 12 will be greater than those of the first metal layer 13 during thermocompression bonding. If the top surfaces of both are flush or the top surface of the first organic dielectric layer 12 is higher than that of the first metal layer 13, this will prevent the first metal layer 13 from bonding with the opposite metal layer 13 during the bonding process. The second metal layer 23 cannot effectively contact and bond, which will lead to the failure or ineffectiveness of the bonding between the metals. When the top surface of the remaining first organic dielectric layer 12 is lower than the top surface of the first metal layer 13, during the bonding process, the sum of the expansion of the first metal layer 13 and the protrusion of the first organic dielectric layer 12 is generally consistent with or the same as the expansion of the first organic dielectric layer 12. Therefore, when the first organic dielectric layer 12 contacts and bonds with the second organic dielectric layer 22, the first metal layer 13 can also contact and bond with the second metal layer 23, thereby improving the bonding strength.

[0074] In some embodiments, reference Figures 1 to 3 The process of forming the first metal layer 13 includes: A first seed layer 14 is formed on the first wafer 1; A first photoresist layer 15 is formed on the first seed layer 14, and the first photoresist layer 15 has a plurality of discrete first openings 16 that expose a portion of the top surface of the first seed layer 14. A first metal layer 13 is formed in the first opening 16 using a first electroplating process; Remove the first photoresist layer 15 and remove the first seed layer 14 on both sides of the first metal layer 13.

[0075] In one example, the material of the first seed layer 14 includes titanium; the thickness of the first seed layer 14 is 250-300 nanometers.

[0076] In one example, the material of the first seed layer 14 includes copper; the thickness of the first seed layer 14 is 30-50 nanometers.

[0077] In some embodiments, the material of the first metal layer 13 includes one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni; The size range of the grains in the first metal layer 13 is 1.6 micrometers to 2 micrometers.

[0078] In some embodiments, the electrolyte used in the first electroplating process includes a basic electrolyte and functional additives. The basic electrolytes include copper sulfate and sulfuric acid; The functional additives include one or more of chloride ions, polyethylene glycol, and sodium dithiodipropane sulfonate. The anode used in the first electroplating process is a phosphor bronze electrode, and the current is a direct current of 3.8-4.2 amperes per square decimeter.

[0079] The basic electrolyte includes copper sulfate and sulfuric acid. Copper ions from copper sulfate serve as the basic raw material for metal deposition in the first metal layer 13. Sulfuric acid is used to maintain an appropriate ion concentration and improve the conductivity of the electrolyte, ensuring deposition continuity and rate, and improving the purity of the first metal layer 13. The functional additives include one or more of chloride ions, polyethylene glycol, and sodium polydithiopropane sulfonate. Chloride ions, in conjunction with polyethylene glycol, act as crystallization inhibitors, selectively adsorbing and controlling crystal growth, promoting grain formation, inhibiting rapid deposition in high current density regions, and improving the uniformity of the first metal layer 13. The anode used in the first electroplating process is a phosphorus copper electrode to maintain a stable copper ion concentration, avoid anode passivation, reduce impurity introduction, and improve process stability. Direct current is used to provide precise electrochemical drive, control crystallization quality, optimize metal deposition efficiency, and ensure process stability.

[0080] In some embodiments, the material of the first organic dielectric layer 12 includes polyimide resin, polybenzoxazole resin, or polyimide-imide resin.

[0081] In some embodiments, the first organic dielectric layer 12 is formed by spin coating and curing processes.

[0082] In one example, the curing process is performed at a temperature of 200°C-230°C.

[0083] Because the first metal layer 13 has a large thickness and large grain size, the surface roughness of the first metal layer 13 formed by the first electroplating process will be too large. Therefore, in some embodiments, after forming the first metal layer 13 by the first electroplating process, it is also necessary to mechanically grind and polish the surface of the first metal layer 13 away from the first wafer 1, so that the surface roughness of the surface of the first metal layer 13 away from the first wafer 1 is in the range of 3 nanometers to 4.7 nanometers, so as to reduce the surface roughness of the first metal layer 13, make the surface of the first metal layer 13 away from the first wafer 1 flatter, thereby improving the bonding strength and stability.

[0084] Secondly, refer to Figure 15 In conjunction with references Figure 12 In step S102, a second wafer 2 is provided, and a second bonding layer 21 is formed on the surface of the second wafer 2. The second bonding layer 21 includes a second organic dielectric layer 22 and a plurality of discrete second metal layers 23 located in the second organic dielectric layer 22. The surface of the second organic dielectric layer 22 away from the second wafer 2 exposes the surface of the second metal layers 23 away from the second wafer 2. The mechanical properties of the first organic dielectric layer 12 are stronger than those of the second organic dielectric layer 22, and the size of the grains in the first metal layer 13 is larger than the size of the grains in the second metal layer 23.

[0085] In some embodiments, reference Figures 10 to 12 The formation process of the second bonding layer 21 includes: A plurality of discrete second metal layers 23 are formed on the surface of the second wafer 2; A second organic dielectric layer 22 is formed covering the second metal layer 23; The second organic dielectric layer 22 is thinned using a chemical mechanical polishing process until the top surface of the second metal layer 23 is exposed, and after the chemical mechanical polishing process, the top surface of the remaining second organic dielectric layer 22 is lower than the top surface of the second metal layer 23.

[0086] The purpose of having the top surface of the remaining second organic dielectric layer 22 lower than the top surface of the second metal layer 23 after the chemical mechanical polishing process is as follows: Because the coefficient of thermal expansion of the second organic dielectric layer 22 is greater than that of the second metal layer 23, the expansion rate and amount of the second organic dielectric layer 22 will be greater than those of the second metal layer 23 during hot pressing bonding. If the top surfaces of both are flush or the top surface of the second organic dielectric layer 22 is higher than that of the second metal layer 23, this will make the bonding process more efficient. If layer 13 cannot effectively contact and bond, it will lead to failure or ineffective bonding between metals. In this application, when the top surface of the remaining second organic dielectric layer 22 is lower than the top surface of the second metal layer 23, during the bonding process, the sum of the expansion amount of the second metal layer 23 and the protrusion amount protruding from the top surface of the second organic dielectric layer 22 is generally consistent with or the same as the expansion amount of the second organic dielectric layer 22. Therefore, when the second organic dielectric layer 22 contacts and bonds with the first organic dielectric layer 12, the second metal layer 23 can also contact and bond with the first metal layer 13, thereby improving the bonding strength.

[0087] In some embodiments, reference Figures 7 to 9 The process of forming the second metal layer 23 includes: A second seed layer 24 is formed on the second wafer 2; A second photoresist layer 25 is formed on the second seed layer 24, and the second photoresist layer 25 has a plurality of discrete second openings 26 that expose a portion of the top surface of the second seed layer 24. A second metal layer 23 is formed in the second opening 26 using a second electroplating process; Remove the second photoresist layer 25 and remove the second seed layer 24 on both sides of the second metal layer 23.

[0088] In one example, the material of the second seed layer 24 includes titanium; the thickness of the second seed layer 24 is 250-300 nanometers.

[0089] In one example, the material of the second seed layer 24 includes copper; the thickness of the second seed layer 24 is 30-50 nanometers.

[0090] In some embodiments, the material of the second metal layer 23 includes one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni; The grain size range of the second metal layer 23 is 150 nanometers to 200 nanometers.

[0091] In some embodiments, the electrolyte used in the second electroplating process includes a basic electrolyte and functional additives. The basic electrolytes include copper sulfate and sulfuric acid; The functional additives include one or more of chloride ions, polydithiopropane sulfonic acid, polyetherimide, and benzimidazole; The anode used in the second electroplating process is a platinum electrode, and the current is a pulsed current of 4.8-5.2 amperes per square decimeter, with a pulse on-time range of 7 ms-9 ms and a pulse off-time range of 18 ms-22 ms.

[0092] The basic electrolyte includes copper sulfate and sulfuric acid. Copper ions from copper sulfate serve as the basic raw material for metal deposition in the second metal layer 23. Sulfuric acid is used to maintain an appropriate ion concentration and improve the conductivity of the electrolyte, ensuring deposition continuity and rate, and improving the purity of the second metal layer 23. The functional additives include one or more of chloride ions, polyethylene glycol, and sodium didithiopropane sulfonate. Chloride ions, in conjunction with sodium didithiopropane sulfonate, act as crystallization inhibitors, selectively adsorbing and controlling crystal growth, promoting grain formation, inhibiting rapid deposition in high current density regions, and improving the uniformity of the second metal layer 23. A platinum electrode is used as the anode in the second electroplating process to maintain electric field stability, avoid anode passivation, reduce impurity introduction, and improve process stability. Alternating current is used, and the crystallization process is controlled by intermittent power supply to increase nucleation density, optimize metal deposition efficiency, and ensure process stability.

[0093] In some embodiments, the material of the second organic dielectric layer 22 includes benzocyclobutene resin, fluorinated polyimide resin, or fluorocarbon resin.

[0094] In some embodiments, the second organic dielectric layer 22 is formed by spin coating and curing processes.

[0095] Finally, refer to Figure 15 In conjunction with references Figure 13 and Figure 14 In step S103, the second wafer 2 is placed above the first wafer 1 and aligned and bonded to the first wafer 1, such that the second metal layer 23 in the second bonding layer 21 is bonded to the corresponding first metal layer 13 in the first bonding layer 11, and the second organic dielectric layer 22 in the second bonding layer 21 is bonded to the first organic dielectric layer 12 in the first bonding layer 11.

[0096] When forming a hybrid bonding structure using the steps described above in this application, firstly, during bonding, the second wafer 2 is located above the first wafer 1, and the second wafer 2 is pressed onto the first wafer 1. Since the mechanical properties of the first organic dielectric layer 12 on the first wafer 1 are stronger than those of the second organic dielectric layer 22 on the second wafer 2, the first organic dielectric layer 12 can better withstand the pressure from the second wafer 2 to provide stronger mechanical support for the second wafer 2, and can better buffer the stress generated during the bonding process, thereby preventing the first organic dielectric layer 12 from collapsing or breaking during the bonding process, thus avoiding delamination defects in the first organic dielectric layer 12, and avoiding poor contact defects caused by ineffective contact between metals, thereby improving the reliability of the bonding.

[0097] Furthermore, since the first metal layer 13 is located below the second metal layer 23, and since the size of the grains in the first metal layer 13 is larger than the size of the grains in the second metal layer 23 (the energy level of a metal with a larger grain size will be smaller than the energy level of the same metal with a smaller grain size, i.e., the energy level of the first metal layer 13 is smaller than the energy level of the second metal layer 23), during the bonding process, the metal will migrate from the high energy level to the low energy level. That is, the small-sized grains in the second metal layer 23 will migrate into the first metal layer 13. And since the high-energy second metal layer 23 is located above the first metal layer 13, this is more conducive to the migration of the small-sized grains in the second metal layer 23 into the first metal layer 13, thereby achieving unidirectional cross-interface grain growth more quickly, effectively eliminating the generation of the original metal bonding interface and voids, and thus improving the bonding strength between metals.

[0098] Secondly, during the bonding process, since the expansion of the first metal layer 13 is greater than that of the second metal layer 23 (for the same metal material, larger grain size makes it easier to expand when heated), in this application, the first metal layer 13 with a larger grain size (larger than the grain size of the second metal layer 23) and the first organic dielectric layer 12 with stronger mechanical properties (stronger mechanical properties than the second organic dielectric layer 22) are both disposed on the surface of the first wafer 1. Therefore, the first organic dielectric layer 12 can also better suppress the lateral expansion of the first metal layer 13, reduce the lateral displacement of the first metal layer 13, improve the accuracy of the bonding position of the first metal layer 13 and the second metal layer 23, and further improve the bonding strength.

[0099] In some embodiments, the dielectric constant of the first organic dielectric layer 12 is less than the dielectric constant of the second organic dielectric layer 22.

[0100] In some embodiments, after removing the first photoresist layer 15 and the first seed layers 14 on both sides of the first metal layer 13, the process includes: The surface of the first bonding layer 11 away from the first wafer 1 is ground or polished to reduce the surface roughness of the first bonding layer 11 away from the first wafer 1 to 3 nanometers-4.7 nanometers.

[0101] In some embodiments, when the second wafer 2 is placed above the first wafer 1 and aligned and bonded to the first wafer 1, the second wafer 2 is located directly above the first wafer 1; The bonding process employs a hot-press bonding process, with a time range of 0.9 hours to 1.2 hours, a temperature range of 240°C to 260°C, and a pressure range of 7 MPa to 9 MPa.

[0102] In some embodiments, after bonding the first wafer 1 and the second wafer 2, the method further includes: The bonded first wafer 1 and second wafer 2 are subjected to annealing treatment. The annealing treatment temperature range is 270℃-290℃, and the treatment time range is 35 minutes-45 minutes.

[0103] In one example, the first wafer 1 and the second wafer 2 may include logic chips and / or memory chips. In one example, the logic chip may include, but is not limited to, gate arrays, cell substrate arrays, embedded arrays, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), graphics processing units (GPUs), central processing units (CPUs), microprocessor units (MPUs), microcontroller units (MCUs), logic integrated circuits (ICs), application processors (APs), display driver ICs (DDIs), radio frequency (RF) chips, power supply chips, or complementary metal-oxide-semiconductor (CMOS) image sensors. In one example, the memory chip may include, but is not limited to, dynamic random access memory (DRAM), static random access memory (SRAM), magnetoresistive random access memory (MRAM), phase-change memory (PRAM), resistive random access memory (RRAM), or non-volatile memory chips (such as flash memory).

[0104] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0105] It should be noted that, where there is no conflict, the features in the different embodiments of this application described above can be combined with each other. Furthermore, in each of the above embodiments, the focus is on describing the differences from other embodiments; other specific descriptions of the same / similar parts between the embodiments can be referred to (or referenced) interchangeably. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this application.

[0106] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A hybrid bonding structure, characterized in that, include: A first wafer, wherein a first bonding layer is provided on the surface of the first wafer, the first bonding layer comprising: a first organic dielectric layer and a plurality of discrete first metal layers located in the first organic dielectric layer, wherein the surface of the first organic dielectric layer away from the first wafer exposes the surface of the first metal layer away from the first wafer. A second wafer has a second bonding layer on its surface. The second bonding layer includes a second organic dielectric layer and a plurality of discrete second metal layers located in the second organic dielectric layer. The surface of the second organic dielectric layer away from the second wafer exposes the surface of the second metal layer away from the second wafer. The mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the size of the grains in the first metal layer is larger than that in the second metal layer. The second wafer is located on the first wafer, and the second bonding layer of the second wafer is bonded to the first bonding layer of the first wafer. The second metal layer in the second bonding layer is bonded to the corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to the first organic dielectric layer in the first bonding layer.

2. The hybrid bonding structure according to claim 1, characterized in that, The mechanical properties of the first organic medium layer being stronger than those of the second organic medium layer include: the tensile strength of the first organic medium layer being greater than that of the second organic medium layer, and the elastic modulus of the first organic medium layer being greater than that of the second organic medium layer.

3. The hybrid bonding structure according to claim 2, characterized in that, The tensile strength of the first organic dielectric layer ranges from 100 MPa to 150 MPa, and the tensile strength of the second organic dielectric layer ranges from 60 MPa to 90 MPa. The elastic modulus of the first organic dielectric layer ranges from 2.5 GPa to 4.5 GPa, and the elastic modulus of the second organic dielectric layer ranges from 2.0 GPa to 2.8 GPa.

4. The hybrid bonding structure according to claim 1 or 3, characterized in that, The material of the first organic dielectric layer may be the same as or different from the material of the second organic dielectric layer; The dielectric constants of the first organic dielectric layer and the second organic dielectric layer are less than or equal to 3.

5.

5. The hybrid bonding structure according to claim 4, characterized in that, The material of the first organic dielectric layer includes polyimide resin, polybenzoxazole resin, or polyimide-imide resin; The material of the second organic dielectric layer includes benzocyclobutene resin, fluorinated polyimide resin, or fluorocarbon resin.

6. The hybrid bonding structure according to claim 1, characterized in that, The thickness of the first organic dielectric layer is the same as the thickness of the first metal layer, and both are greater than the thickness of the second organic dielectric layer; The thickness of the second organic dielectric layer is the same as the thickness of the second metal layer.

7. The hybrid bonding structure according to claim 6, characterized in that, The thickness of the first organic dielectric layer and the first metal layer ranges from 60 micrometers to 100 micrometers; The thickness of the second organic dielectric layer and the second metal layer ranges from 10 micrometers to 30 micrometers.

8. The hybrid bonding structure according to claim 1, characterized in that, The materials of the first metal layer and the second metal layer include one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni.

9. The hybrid bonding structure according to claim 8, characterized in that, The grain size in the first metal layer ranges from 1.6 micrometers to 2 micrometers.

10. The hybrid bonding structure according to claim 8, characterized in that, The grain size in the second metal layer ranges from 150 nanometers to 200 nanometers.

11. The hybrid bonding structure according to claim 1, characterized in that, The surface roughness of the first metal layer on the side away from the first wafer ranges from 3 nanometers to 4.7 nanometers.

12. A method for forming a hybrid bonding structure, characterized in that, include: A first wafer is provided, and a first bonding layer is formed on the surface of the first wafer. The first bonding layer includes: a first organic dielectric layer and a plurality of discrete first metal layers located in the first organic dielectric layer, wherein the surface of the first organic dielectric layer away from the first wafer exposes the surface of the first metal layers away from the first wafer. A second wafer is provided, and a second bonding layer is formed on the surface of the second wafer. The second bonding layer includes: a second organic dielectric layer and a plurality of discrete second metal layers located in the second organic dielectric layer, wherein the surface of the second organic dielectric layer away from the second wafer exposes the surface of the second metal layer away from the second wafer; wherein the mechanical properties of the first organic dielectric layer are stronger than those of the second organic dielectric layer, and the size of the grains in the first metal layer is larger than the size of the grains in the second metal layer. The second wafer is placed above the first wafer and aligned and bonded to the first wafer, such that the second metal layer in the second bonding layer is bonded to the corresponding first metal layer in the first bonding layer, and the second organic dielectric layer in the second bonding layer is bonded to the first organic dielectric layer in the first bonding layer.

13. The method for forming a hybrid bonding structure according to claim 12, characterized in that, The mechanical properties of the first organic medium layer being stronger than those of the second organic medium layer include: the tensile strength of the first organic medium layer being greater than that of the second organic medium layer, and the elastic modulus of the first organic medium layer being greater than that of the second organic medium layer.

14. The method for forming a hybrid bonding structure according to claim 12 or 13, characterized in that, The formation process of the first bonding layer includes: A plurality of discrete first metal layers are formed on the surface of the first wafer; A first organic dielectric layer is formed covering the first metal layer; The first organic dielectric layer is thinned using a chemical mechanical polishing process until the top surface of the first metal layer is exposed, and after the chemical mechanical polishing process, the top surface of the remaining first organic dielectric layer is lower than the top surface of the first metal layer.

15. The method for forming a hybrid bonding structure according to claim 14, characterized in that, The process of forming the first metal layer includes: A first seed layer is formed on the first wafer; A first photoresist layer is formed on the first seed layer, and the first photoresist layer has a plurality of discrete first openings that expose a portion of the top surface of the first seed layer. A first metal layer is formed in the first opening using a first electroplating process; Remove the first photoresist layer and remove the first seed layer on both sides of the first metal layer.

16. The method for forming a hybrid bonding structure according to claim 15, characterized in that, The material of the first metal layer includes one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni; The grain size in the first metal layer ranges from 1.6 micrometers to 2 micrometers.

17. The method for forming a hybrid bonding structure according to claim 16, characterized in that, The electrolyte used in the first electroplating process includes a basic electrolyte and functional additives. The basic electrolytes include copper sulfate and sulfuric acid; The functional additives include one or more of chloride ions, polyethylene glycol, and sodium dithiodipropane sulfonate. The anode used in the first electroplating process is a phosphor bronze electrode, and the current is a direct current of 3.8-4.2 amperes per square decimeter.

18. The method for forming a hybrid bonding structure according to claim 14, characterized in that, The material of the first organic dielectric layer includes polyimide resin, polybenzoxazole resin, or polyimide-imide resin.

19. The method for forming a hybrid bonding structure according to claim 18, characterized in that, The first organic dielectric layer is formed by spin coating and curing processes.

20. The method for forming a hybrid bonding structure according to claim 12 or 13, characterized in that, The formation process of the second bonding layer includes: A plurality of discrete second metal layers are formed on the surface of the second wafer; A second organic dielectric layer is formed covering the second metal layer; The second organic dielectric layer is thinned using a chemical mechanical polishing process until the top surface of the second metal layer is exposed, and after the chemical mechanical polishing process, the top surface of the remaining second organic dielectric layer is lower than the top surface of the second metal layer.

21. The method for forming a hybrid bonding structure according to claim 20, characterized in that, The process of forming the second metal layer includes: A second seed layer is formed on the second wafer; A second photoresist layer is formed on the second seed layer, and the second photoresist layer has a plurality of discrete second openings that expose a portion of the top surface of the second seed layer. A second metal layer is formed in the second opening using a second electroplating process; Remove the second photoresist layer and remove the second seed layer on both sides of the second metal layer.

22. The method for forming a hybrid bonding structure according to claim 21, characterized in that, The material of the second metal layer includes one or more of Cu, Au, Al, Ag, Ti, W, Pt, and Ni; The grain size in the second metal layer ranges from 150 nanometers to 200 nanometers.

23. The method for forming a hybrid bonding structure according to claim 22, characterized in that, The electrolyte used in the second electroplating process includes a basic electrolyte and functional additives. The basic electrolytes include copper sulfate and sulfuric acid; The functional additives include one or more of chloride ions, polydithiopropane sulfonic acid, polyetherimide, and benzimidazole; The anode used in the second electroplating process is a platinum electrode, and the current is a pulsed current of 4.8-5.2 amperes per square decimeter, with a pulse on-time range of 7 ms-9 ms and a pulse off-time range of 18 ms-22 ms.

24. The method for forming a hybrid bonding structure according to claim 20, characterized in that, The material of the second organic dielectric layer includes benzocyclobutene resin, fluorinated polyimide resin, or fluorocarbon resin.

25. The method for forming a hybrid bonding structure according to claim 24, characterized in that, The second organic dielectric layer is formed using a spin coating process and a curing process.

26. The method for forming a hybrid bonding structure according to claim 15, characterized in that, After removing the first photoresist layer and the first seed layers on both sides of the first metal layer, the process includes: The surface of the first bonding layer away from the first wafer is ground or polished to reduce the surface roughness of the first bonding layer away from the first wafer to 3-4.7 nanometers.

27. The method for forming a hybrid bonding structure according to claim 12, characterized in that, When the second wafer is placed above the first wafer and aligned and bonded to the first wafer, the second wafer is located directly above the first wafer; The bonding process employs a hot-press bonding process, with a time range of 0.9 hours to 1.2 hours, a temperature range of 240°C to 260°C, and a pressure range of 7 MPa to 9 MPa.

28. The method for forming a hybrid bonding structure according to claim 27, characterized in that, After bonding the first wafer and the second wafer, the process also includes: The bonded first wafer and the second wafer are subjected to annealing treatment. The annealing treatment temperature range is 270℃-290℃, and the treatment time range is 35 minutes-45 minutes.

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