Packaging structure, preparation method of packaging structure and infrared detector

Abstract

The invention provides a packaging structure, a preparation method of the packaging structure and an infrared detector, relates to the field of integrated circuit packaging, and aims to improve the supporting force strength between two wafers. The packaging structure comprises a first to-be-bonded structure, a second to-be-bonded structure and a bonding body which are oppositely arranged; the bonding body is arranged between the first to-be-bonded structure and the second to-be-bonded structure and is connected with the first to-be-bonded structure and the second to-be-bonded structure; a cavity is formed between the first to-be-bonded structure and the second to-be-bonded structure, and the bonding body surrounds the cavity; wherein the bonding body comprises a base material layer and solid particles embedded in the base material layer, the material of the base material layer comprises welding flux, and the hardness of the solid particles is larger than that of the base material layer; the solid particles are added to the welding layer playing a connecting role, and the hardness of the solid particles is greater than that of the base material layer, so that the first to-be-bonded structure and the second to-be-bonded structure have good supporting performance.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit packaging, and in particular to a packaging structure, a method for preparing the packaging structure, and an infrared detector. Background Art

[0002] As a key link in microelectronics manufacturing, wafer bonding technology is becoming increasingly important. Wafer bonding is the process of closely combining two or more wafers together through physical or chemical methods to achieve device integration and performance improvement.

[0003] Traditional wafer bonding methods mainly rely on microscopic forces such as intermolecular forces, van der Waals forces or chemical bonds between the bonding interfaces to achieve tight bonding of wafers. However, when these microscopic forces are manifested as supporting forces on a macro scale, there are often problems such as insufficient strength and uneven distribution. This causes the wafer to be easily deformed, dislocated or even broken during subsequent processing, cutting or use, seriously affecting the performance and yield rate of the device. Summary of the invention

[0004] The embodiments of the present invention provide a packaging structure, a method for preparing the packaging structure, and an infrared detector, which are intended to improve the supporting strength between two wafers.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: In a first aspect, the present application provides a packaging structure, which includes a first structure to be bonded, a second structure to be bonded, and a bonding body that are relatively arranged. The bonding body is arranged between the first structure to be bonded and the second structure to be bonded, and is connected to the first structure to be bonded and the second structure to be bonded. A cavity is formed between the first structure to be bonded and the second structure to be bonded, and the bonding body surrounds the cavity. Among them, the bonding body includes a substrate layer and solid particles embedded in the substrate layer, the material of the substrate layer includes solder, and the hardness of the solid particles is greater than the hardness of the substrate layer.

[0006] The packaging structure provided in the present application realizes the bonding of the first structure to be bonded and the second structure to be bonded by a bonding body. The bonding body includes two parts, one part is a substrate layer, and the other part is solid particles. Since the welding layer that plays a connecting role increases the solid particles, and the hardness of the solid particles is greater than the hardness of the substrate layer, there is good support between the first structure to be bonded and the second structure to be bonded. In addition, the size of the solid particles can also affect the bonding height between the first structure to be bonded and the second structure to be bonded. When the solid particles are larger, the bonding height between the first structure to be bonded and the second structure to be bonded increases, and when the solid particles are smaller, the bonding height between the first structure to be bonded and the second structure to be bonded decreases. By controlling the size of the solid particles embedded in the substrate layer, the bonding height between the two wafers is changed, so that the flexibility of bonding is greatly improved.

[0007] As a possible implementation manner, the melting point of the solder is lower than the melting point of the solid particles.

[0008] As a possible implementation manner, the solid particles include non-metallic materials.

[0009] As a possible implementation manner, the material of the solid particles includes at least one of SiO2, Al2O3, AlN, and Si3N4.

[0010] As a possible implementation manner, the solder includes at least one of a Sn-based solder or an In-based solder.

[0011] As a possible implementation manner, the solid particles are in the shape of a sphere and / or an ellipsoid.

[0012] As a possible implementation manner, the diameter of the solid particles is greater than or equal to 10 μm and less than or equal to 1000 μm.

[0013] As a possible implementation manner, the difference in diameters of different solid particles in the bonded body is within a preset range.

[0014] As a possible implementation manner, the number of solid particles included in the bonding body along the thickness direction thereof is 1.

[0015] As a possible implementation, the packaging structure further includes a first functional film layer and a second functional film layer. The first functional film layer is connected between the first structure to be bonded and the bonding body, and surrounds the cavity. The second functional film layer is connected between the second structure to be bonded and the bonding body, and surrounds the cavity.

[0016] As a possible implementation, along the direction from the first structure to be bonded to the second structure to be bonded, the first functional film layer includes a first adhesive layer, a first diffusion barrier layer and a first bonding layer in sequence. Along the direction from the second structure to be bonded to the first structure to be bonded, the second functional film layer includes a second adhesive layer, a second diffusion barrier layer and a second bonding layer.

[0017] In a second aspect, the present application also provides a method for preparing a packaging structure, comprising: forming a bonding body on a second structure to be bonded. Connecting the bonding body to the first structure to be bonded so that a cavity is formed between the first structure to be bonded and the second structure to be bonded, and the bonding body surrounds the cavity. The bonding body comprises a substrate layer and solid particles embedded in the substrate layer, the material of the substrate layer comprises solder, and the hardness of the solid particles is greater than the hardness of the substrate layer.

[0018] As a possible implementation, forming a bonding body on the second structure to be bonded includes: heating the solder to a molten state, mixing solid particles, and coating the mixture of the molten solder and the solid particles on the second structure to be bonded using a dispensing process to form a bonding body.

[0019] As a possible implementation manner, before mixing the solder and the solid particles, forming a bonding body on the second structure to be bonded further includes: performing surface wettability treatment on the solid particles.

[0020] As a possible implementation method, treating the surface wettability of the solid particles includes: using a silane coupling agent for treatment or using plasma treatment.

[0021] As a possible implementation manner, the ratio of the inner diameter of the needle used in the dispensing process to the diameter of the solid particles is greater than 1 and less than or equal to 2.

[0022] In a third aspect, the present application also provides an infrared detector, including the packaging structure mentioned in the first aspect and its possible implementation methods.

[0023] Among them, the beneficial effects of the second aspect, the third aspect and their specific implementation methods can refer to the beneficial effects of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a packaging structure provided in an embodiment of the present application; Figure 2 A schematic diagram of another packaging structure provided in an embodiment of the present application; Figure 3 A flowchart of a method for preparing a packaging structure provided in an embodiment of the present application; Figure 4 A flow chart of another method for preparing a packaging structure provided in an embodiment of the present application; Figure 5 A schematic diagram of preparing a packaging structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, when describing the pipeline, the "connected" and "connection" used in the present invention have the meaning of conduction. The specific meaning needs to be understood in conjunction with the context.

[0028] In the embodiments of the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0029] Wafer bonding is a wafer-level packaging technology used to manufacture MEMS, NEMS and optoelectronics devices by bonding two or more wafers together. Wafer bonding technology ensures the mechanical stability and hermetic sealing of the device, thereby protecting the internal structure from environmental influences such as temperature, humidity, high pressure and oxidizing substances.

[0030] Traditional wafer bonding uses evaporation, electroplating or magnetron sputtering to deposit a layer of eutectic alloy, such as gold-silicon alloy or gold-tin alloy, on each of the two wafers to be bonded. The bonding between the wafers is achieved by aligning the two wafers and heating them to the eutectic temperature, melting the metal layer and re-solidifying it.

[0031] Taking the infrared detector that requires the bonding of the light window wafer and the circuit wafer as an example, usually the metal bonding layer is prepared on the light window wafer and the circuit wafer by evaporation, electroplating or magnetron sputtering, and then the light window wafer and the circuit wafer are bonded by eutectic welding. Due to cost and process efficiency limitations, the metal bonding layer prepared on the light window wafer and the circuit wafer is usually thin, only a few microns, resulting in a relatively close distance between the light window wafer and the circuit wafer after bonding.

[0032] Since the distance between the optical window wafer and the circuit wafer is relatively close after bonding, the tiny particles on the optical window wafer will affect the focal plane array of the circuit wafer during the optical projection reflection process, thereby having a negative effect on the imaging of the infrared detector. Therefore, the bonding height between the two wafers will directly affect the performance of the produced product. In addition, the thin metal bonding layer will also make the support between the optical window wafer and the circuit wafer relatively weak, affecting the overall structural stability and strength after bonding.

[0033] In view of this, for example, Figure 1 As shown, the present application provides a packaging structure 100. The packaging structure 100 includes a first structure to be bonded 1, a second structure to be bonded 2 and a bonding body 3 which are relatively arranged. The bonding body 3 is arranged between the first structure to be bonded 1 and the second structure to be bonded 2, and is connected to the first structure to be bonded 1 and the second structure to be bonded 2. A chamber 4 is formed between the first structure to be bonded 1 and the second structure to be bonded 2, and the bonding body 3 surrounds the chamber 4. Among them, the bonding body 3 includes a substrate layer 31 and solid particles 32 embedded in the substrate layer 31, the material of the substrate layer 31 includes solder, and the hardness of the solid particles 32 is greater than the hardness of the substrate layer 31.

[0034] The packaging structure 100 provided in the present application realizes the bonding of the first structure to be bonded 1 and the second structure to be bonded 2 through a bonding body. The bonding body 3 includes two parts, one part is a substrate layer 31, and the other part is solid particles 32. Since the welding layer that plays a connecting role increases the solid particles, and the hardness of the solid particles 32 is greater than the hardness of the substrate layer 31, there is good support between the first structure to be bonded 1 and the second structure to be bonded 2, which can significantly improve the overall strength of the bonding body. In addition, the size of the solid particles 32 can also affect the bonding height between the first structure to be bonded 1 and the second structure to be bonded 2. When the solid particles 32 are large, the bonding height between the first structure to be bonded 1 and the second structure to be bonded 2 increases, and when the solid particles 32 are small, the bonding height between the first structure to be bonded 1 and the second structure to be bonded 2 decreases. By controlling the size of the solid particles 32 embedded in the substrate layer 31, the bonding height between the two wafers is changed, so that the flexibility of bonding is greatly improved.

[0035] In addition, due to the small spacing between the two wafers after the traditional wafer bonding, the volume of the chamber surrounded by the metal bonding layer is also small. Still taking the bonding of the light window wafer and the circuit wafer in the infrared detector as an example, under ideal conditions, the chamber after bonding should be a vacuum chamber, but in the traditional wafer bonding process, a large bonding pressure is required on the light window wafer and the circuit wafer. If the pressure is insufficient, it is easy to cause the consequence of cold welding, thereby causing air leakage. Since the chamber volume formed by the traditional bonding method is small, once the air leaks, it will have a greater impact on the air tightness. If the pressure is high, it is easy to damage the structure of the light window wafer and the circuit wafer. The packaging structure provided by the present application only needs to heat and melt the solder and perform the operation by the dispensing process, and due to the presence of solid particles, the volume of the formed chamber is relatively larger. Even if the influence of air leakage is difficult to avoid during the process, the gas in the chamber has less impact on the overall air tightness, so the prepared product is more precise.

[0036] It should be understood that the first structure to be bonded and the second structure to be bonded mentioned in the embodiments of the present application can be bonding between wafers, bonding between integrated circuit structures, bonding between power devices, bonding between optoelectronic devices, etc. The present application does not limit the type of structure to be bonded.

[0037] As a possible implementation method, the melting point of the solder is lower than the melting point of the solid particles. In some embodiments, the preparation of the substrate layer involves mixing the solder and the solid particles in a heating chamber for heating. The heating temperature of the heating chamber is higher than the melting point of the solder and lower than the melting point of the solid particles. Since the melting point of the solder is lower than the melting point of the solid particles, the solder is heated to a molten state, while the physical form of the solid particles does not change, thereby maintaining the supporting function.

[0038] In some embodiments, the solder includes a metal material, for example, the solder includes at least one of a Sn-based solder or an In-based solder, for example, the solder is SnAg, InAg, SAC305. The solid particles include a non-metallic material, for example, the solid particles include at least one of SiO2, Al2O3, AlN, and Si3N4.

[0039] In some embodiments, the solid particles are in the shape of a sphere and an ellipsoid; in other embodiments, the solid particles are in the shape of a sphere; in still other embodiments, the solid particles are in the shape of an ellipsoid.

[0040] As a possible implementation method, the diameter of the solid particles is greater than or equal to 10 μm and less than or equal to 1000 μm. The diameter of the solid particles is selected according to actual needs. When a higher bonding height is required, solid particles with a larger diameter are selected, and when a lower bonding height is required, solid particles with a smaller diameter are selected.

[0041] It should be understood that the difference in diameters of different solid particles in the bonding body is within a preset range, that is, under ideal conditions, the sizes of multiple solid particles in the substrate layer should be consistent, but due to the influence of the process, the sizes of the solid particles are difficult to be completely consistent. Therefore, within the allowable error range, for example, the error accuracy is between 0.5% and 1%, it is considered that the size of the solid particles is consistent, that is, the difference in diameters of different solid particles in the bonding body is within a preset range.

[0042] As a possible implementation, the number of solid particles included in the bonding body along its thickness direction is 1. Since the substrate layer in the packaging structure provided in the present application is coated on the first structure to be bonded or the second structure to be bonded by a dispensing process, a needle is used in the dispensing process, and the solid particles are mixed in the molten solder and discharged from the needle. Figure 1 In the direction from the first structure to be bonded 1 to the second structure to be bonded 2, when the number of solid particles included in the bonding body along its own thickness direction is 1, it means that the number of solid particles mixed in the molten solder discharged from the needle each time is also 1, avoiding the accumulation of particles and preventing the needle from being blocked, while making the substrate layer more uniform and having excellent flatness.

[0043] Exemplary, combined Figure 1 and Figure 2 The packaging structure further includes a first functional film layer 5 and a second functional film layer 6. The first functional film layer 5 is connected between the first structure to be bonded 1 and the bonding body 3, and surrounds the cavity 4. The second functional film layer 6 is connected between the second structure to be bonded 2 and the bonding body 3, and surrounds the cavity.

[0044] More specifically, along the direction from the first structure to be bonded 1 to the second structure to be bonded 2, the first functional film layer 5 sequentially includes a first adhesive layer 51, a first diffusion barrier layer 52, and a first bonding layer 53. Along the direction from the second structure to be bonded 2 to the first structure to be bonded 1, the second functional film layer 6 includes a second adhesive layer 61, a second diffusion barrier layer 62, and a second bonding layer 63.

[0045] In some embodiments, the first adhesive layer 51 and the second adhesive layer 61 are made of metal, such as Cr, Ti, W, etc., and are formed by evaporation and magnetron sputtering processes as seed layers to accelerate the deposition speed of other film layers.

[0046] In some embodiments, the first diffusion barrier layer 52 and the second diffusion barrier layer 62 are metals, such as Ni, TiW, Cr, etc., and are prepared by evaporation and magnetron sputtering processes. The first diffusion barrier layer 52 is used to prevent the metal atoms of the first bonding layer 53 from diffusing to the first structure to be bonded 1, and the second diffusion barrier layer 62 is used to prevent the metal atoms of the second bonding layer 63 from diffusing to the second structure to be bonded 2.

[0047] In some embodiments, the first bonding layer 53 and the second bonding layer 63 are metals that form intermetallic compounds with Sn-based or In-based solders, such as Cu, Ni, Au, etc., and are formed by evaporation or magnetron sputtering processes.

[0048] It should be noted that the present application does not limit the thickness of the first functional film layer 5 and the second functional film layer 6, and the thickness can be adjusted according to actual needs. For example, the thickness of the first adhesive layer 51, the first diffusion barrier layer 52, the first bonding layer 53, the second adhesive layer 61, the second diffusion barrier layer 62 and the second bonding layer 63 is 0.1~1μm.

[0049] The present application also provides a method for preparing a packaging structure, exemplarily, as Figure 3 The method for preparing the packaging structure includes: S1: forming a bonding body on a second structure to be bonded.

[0050] S2: connecting the bonding body to the first structure to be bonded, so that a cavity is formed between the first structure to be bonded and the second structure to be bonded, and the bonding body surrounds the cavity.

[0051] Reference Figure 1 , wherein the bonding body 3 includes a substrate layer 31 and solid particles 32 embedded in the substrate layer 31, the material of the substrate layer 31 includes solder, and the hardness of the solid particles 32 is greater than the hardness of the substrate layer 31. The mixture of the molten substrate layer 31 and the solid particles 32 is cooled on the second structure to be bonded 2 to form a bonding body. As a possible implementation method, the bonding body is heated to a molten state again, contacts with the first structure to be bonded 1, and then cooled to achieve bonding between the first structure to be bonded 1 and the second structure to be bonded 2.

[0052] More specifically, see Figure 4 and Figure 5 , step S1: forming a bonding body on a second structure to be bonded, comprising: S11: The solder is heated to a molten state and the solid particles are mixed.

[0053] As a possible implementation, the physical form of the solder is also stored in the solder bin in the form of solid particles, and is stored independently from the solid particles 32. In some embodiments, the solder, such as SnAg, InAg, SnAgCu, In and SnBi, is placed in a heating bin and heated to a temperature above the melting point of the solder so that the solder is in a molten state, and then the solid particles are mixed, and the temperature is maintained to form a mixture of molten solder and solid particles. In this process, ultrasonic or mechanical stirring can make the distribution of solid particles in the molten solder more uniform. Heating the solder to a molten state first and then mixing the solid particles can further improve the uniformity of the solid particles in the molten solder. In other embodiments, the solder and the solid particles are mixed in the heating bin and heated to a temperature above the melting point of the solder and maintained at the temperature, so that multiple solid granular solders are melted and combined into one, showing a molten state, and the solid particles are mixed in the molten solder to form a mixture of liquid solder and solid particles. In this process, ultrasonic or mechanical stirring can make the distribution of solid particles in the re-melted solder more uniform.

[0054] S12: A dispensing process is used to coat a mixture of molten solder and solid particles on the second structure to be bonded to form a bonding body.

[0055] The mixture of solder and solid particles is coated on the second structure to be bonded 2 through a needle, the first structure to be bonded is aligned with the second structure to be bonded, the first bonding layer and the second bonding layer are in contact with the mixture of solder and solid particles, and a bonding body is formed after cooling.

[0056] As a possible implementation method, the ratio of the inner diameter of the needle 8 used in the dispensing process to the diameter of the solid particles is greater than 1 and less than or equal to 2. The size of the inner diameter of the needle 8 determines the number of solid particles embedded in the substrate layer 31 while discharging the substrate layer 31. For example, when the inner diameter of the needle 8 is greater than the diameter of one solid particle and less than the diameter of two solid particles, it means that the solid particles can only be discharged from the needle mouth one by one along with the solder. This ensures that the number of solid particles contained in each part of the substrate layer is the same, ensures the flatness of the bonding body, and avoids the situation where one part of the bonding body is higher and another part is lower.

[0057] Since the mixture of solder and solid particles provided in the present application does not contain an organic resin component, no volatile gas is generated during the heating process and the bonding process, and the vacuum degree of the chamber is not affected.

[0058] As a possible implementation method, before the solder and the solid particles are mixed, forming a bonding body on the second structure to be bonded further includes: performing surface wettability treatment on the solid particles. Further, the wettability treatment includes: using a silane coupling agent for treatment or using plasma treatment. The purpose of pre-treatment of the solid particles for wettability is to improve the affinity of the solid particle surface to the solder, avoid the formation of voids in the mixture of liquid solder and solid particles obtained later, and also help to improve the uniformity of the distribution of the solid particles in the liquid solder.

[0059] Exemplarily, the proportion of solid particles is between 1% and 50%, and the present application does not make any specific limitation thereto.

[0060] The embodiment of the present application also provides an infrared detector, including the packaging structure as described above. Since the wafer-level packaging of the infrared detector adopts the aforementioned packaging method, the light window wafer and the circuit wafer are bonded by a dispensing process, which is easy to operate. Since the hard solid particles have good support, the precision requirements for pressure control are low, which avoids solder overflow and cold soldering while improving efficiency. Traditional wafer bonding requires the deposition of Au or Sn solder. The present application adopts common solders such as SAC305 and SnAg, which are low in cost. In addition, due to the presence of solid particles, the height of the formed bonded body is positively correlated with the diameter of the solid particles. Since the size of the solid particles can be flexibly selected, the bonding height can also be flexibly changed. The volume of the vacuum chamber between the light window wafer and the circuit wafer of the infrared detector is larger, the influence of impurities on the focal plane array is smaller, and the imaging quality of the infrared detector is improved.

[0061] In addition, the addition of solid particles can reduce the thermal expansion coefficient of the substrate layer, making the thermal expansion coefficients of the substrate layer and the functional film layer and wafer more matched, reducing stress and strain, and improving the stability and reliability of bonding.

[0062] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application.

[0063] Finally, it should be noted that the above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A packaging structure, characterized in that: include: A first structure to be bonded and a second structure to be bonded arranged opposite to each other; a bonding body, disposed between the first structure to be bonded and the second structure to be bonded, and connected to the first structure to be bonded and the second structure to be bonded; a cavity is formed between the first structure to be bonded and the second structure to be bonded, and the bonding body surrounds the cavity; The bonding body comprises a substrate layer and solid particles embedded in the substrate layer. The material of the substrate layer comprises solder, and the hardness of the solid particles is greater than the hardness of the substrate layer.

2. The packaging structure according to claim 1, characterized in that: The melting point of the solder is lower than the melting point of the solid particles.

3. The packaging structure according to claim 1, characterized in that: The solid particles include non-metallic materials.

4. The packaging structure according to claim 3, characterized in that: The material of the solid particles includes at least one of SiO2, Al2O3, AlN, and Si3N4.

5. The packaging structure according to claim 1, characterized in that: The solder includes at least one of a Sn-based solder or an In-based solder.

6. The packaging structure according to claim 1, characterized in that: The solid particles are in the shape of a sphere and / or an ellipsoid.

7. The packaging structure according to claim 6, characterized in that: The diameter of the solid particles is greater than or equal to 10 μm and less than or equal to 1000 μm.

8. The packaging structure according to claim 6, characterized in that: The difference in diameters of different solid particles in the bonded body is within a preset range.

9. The packaging structure according to claim 1, characterized in that: The number of solid particles included in the bonded body along its thickness direction is 1.

10. The packaging structure according to claim 1, characterized in that: The packaging structure further includes: A first functional film layer connected between the first structure to be bonded and the bonding body and surrounding the chamber; The second functional film layer is connected between the second structure to be bonded and the bonding body and surrounds the chamber.

11. The packaging structure according to claim 10, characterized in that: Along the direction from the first structure to be bonded to the second structure to be bonded, the first functional film layer sequentially includes a first adhesive layer, a first diffusion barrier layer and a first bonding layer; Along the direction from the second structure to be bonded to the first structure to be bonded, the second functional film layer includes a second adhesive layer, a second diffusion barrier layer and a second bonding layer.

12. A method for preparing a packaging structure, characterized in that: include: forming a bonding body on the second structure to be bonded; Connecting the bonding body to a first structure to be bonded, so that a cavity is formed between the first structure to be bonded and the second structure to be bonded, and the bonding body surrounds the cavity; Wherein, the bonding body comprises a substrate layer and solid particles embedded in the substrate layer, the material of the substrate layer comprises solder, and the hardness of the solid particles is greater than the hardness of the substrate layer.

13. The method for preparing a packaging structure according to claim 12, characterized in that: The step of forming a bonding body on the second structure to be bonded comprises: The solder is heated to a molten state and then mixed with solid particles; A dispensing process is used to coat a mixture of the molten solder and the solid particles on the second structure to be bonded to form the bonding body.

14. The method for preparing a packaging structure according to claim 13, characterized in that: Before mixing the solder and the solid particles, forming a bonding body on the second structure to be bonded further comprises: The solid particles are subjected to a surface wettability treatment.

15. The method for preparing a packaging structure according to claim 14, characterized in that: The treating of the surface wettability of the solid particles includes: treating with a silane coupling agent or using plasma.

16. The method for preparing a packaging structure according to claim 13, characterized in that: The ratio of the inner diameter of the needle used in the dispensing process to the diameter of the solid particles is greater than 1 and less than or equal to 2.

17. An infrared detector, characterized in that: Comprising the packaging structure as described in any one of claims 1 to 11.

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