Composite structure, preparation method therefor, packaging structure and electronic device

Abstract

The present application relates to the technical field of semiconductors. Provided in the embodiments of the present application are a composite structure, a preparation method therefor, a packaging structure and an electronic device. The composite structure comprises a diamond alloy layer and a first metal layer, the diamond alloy layer and the first metal layer being stacked, the diamond alloy layer and the first metal layer being of an integrated structure, the diamond alloy layer being used for connecting to a semiconductor device, and the first metal layer being used for connecting to a packaging substrate. The diamond alloy layer having a higher thermal conductivity can rapidly dissipate heat from the semiconductor device, thus rapidly reducing the junction temperature of the semiconductor device; moreover, the CTE of the diamond alloy layer is close to the CTE of the semiconductor device, and the CTE of the first metal layer is close to the CTE of a metal heat sink on the surface of the packaging substrate. Thus, when subsequently applied to packaging structures of semiconductor devices, the present application can reduce the delamination risk of the packaging structures.

Description

Composite structure and preparation method thereof, packaging structure and electronic device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on January 4, 2024, with application number 202410016340.7 and application name “A composite structure and its preparation method, packaging structure and electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of semiconductor technology, and in particular to a composite structure and a preparation method thereof, a packaging structure and an electronic device. Background Art

[0003] As RF power density continues to increase, the junction temperature of semiconductor devices within RF power amplifiers can reach over 200°C, approaching the derating standard. Therefore, derating design is necessary for semiconductor devices. Derating design can improve semiconductor device reliability by keeping the operating junction temperature below the maximum junction temperature they can withstand. This requires the rated operating parameters of semiconductor devices to be well below their upper limits, which in turn limits the performance of RF power amplifiers.

[0004] To reduce the junction temperature of semiconductor devices, some RF power amplifiers are equipped with internal thermal conductors. One end of the thermal conductor is used to connect to the semiconductor device, and the other end is used to connect to the metal heat sink. In this way, the thermal conductor can conduct heat from the semiconductor device to the packaging substrate, thereby reducing the junction temperature of the semiconductor device. The thermal conductor can be, for example, a diamond alloy flange. The diamond alloy flange includes an alloy composed of diamond particles and metal, and its coefficient of thermal expansion (CTE) is 3.8ppm / K to 5.8ppm / K. The thermal expansion coefficient of the above-mentioned diamond copper alloy flange is significantly different from that of the metal heat sink. Taking the copper heat sink as an example, its thermal expansion coefficient is approximately 17ppm / K. The difference between the thermal expansion coefficient of the diamond copper alloy flange and the thermal expansion coefficient of the copper heat sink exceeds 50% of the thermal expansion coefficient of the copper heat sink, resulting in a thermal expansion coefficient mismatch between the diamond copper alloy flange and the copper heat sink. When the thermal expansion coefficient is mismatched, if the temperature changes, the thermal deformation of the structures on both sides of the interface between the diamond copper alloy flange and the metal heat sink will differ significantly. This will cause high stress to be concentrated in the solder layer between the flange and the metal heat sink, thereby causing the risk of delamination between the diamond copper alloy flange and the metal heat sink.

[0005] Summary of the Invention

[0006] The present invention provides a composite structure and its preparation method, a packaging structure, and an electronic device. The composite structure of the present invention can quickly dissipate heat from semiconductor devices. Furthermore, the thermal expansion coefficient of the composite structure of the present invention can match the thermal expansion coefficient of the semiconductor device and the thermal expansion coefficient of the metal heat sink on the surface of the packaging substrate. Furthermore, when subsequently used in electronic devices, the composite structure of the present invention can reduce the junction temperature of the semiconductor device, reduce the risk of delamination of the packaging structure, improve the performance and service life of the semiconductor device, and enhance the energy efficiency of the electronic device.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, a composite structure is provided for connecting a semiconductor device and a packaging substrate. The composite structure includes a diamond alloy layer and a first metal layer, the diamond alloy layer and the first metal layer being stacked and integrally formed.

[0009] The diamond alloy layer is used to connect with the semiconductor device; and the first metal layer is used to connect with the packaging substrate.

[0010] On the one hand, the diamond alloy layer has higher thermal conductivity than the first metal layer. By connecting the diamond alloy layer to the semiconductor device, heat can be quickly dissipated from the semiconductor device and evenly distributed laterally. This can quickly reduce the junction temperature of the semiconductor device.

[0011] Furthermore, the thermal expansion coefficient of the diamond alloy layer is close to that of the semiconductor device, while the thermal expansion coefficient of the first metal layer is close to that of the metal heat sink on the surface of the package substrate. As a result, when the temperature changes, the difference in thermal deformation between the composite structure and the semiconductor device interface is small, and the difference in thermal deformation between the composite structure and the package substrate interface is also small. This results in reduced stress at both the composite structure and the semiconductor device interface and the package substrate interface.

[0012] In this way, when the composite structure provided by the embodiment of the present application is applied to the packaging structure of a semiconductor device, the interface subjected to high stress is the interface between the diamond alloy layer and the first metal layer. The interface between the diamond alloy layer and the first metal layer is located inside the composite structure, and the diamond alloy layer and the first metal layer are an integral structure, and there is no interface gap between the two layers. As a result, there can be mutual attraction between the adjacent metal atoms at the interface between the diamond alloy layer and the first metal layer, thereby giving the diamond alloy layer and the first metal layer a certain cohesive force. The presence of cohesive force makes the interface between the diamond alloy layer and the first metal layer have extremely high anti-delamination strength, and delamination is not easy to occur, thereby improving the structural stability of the composite structure. In addition, when the composite structure provided by the embodiment of the present application is applied to the packaging structure of a semiconductor device, it can significantly improve the structural stability of each interface in the packaging structure and reduce the delamination risk of the packaging structure.

[0013] In one possible implementation, the diamond alloy layer includes a metal matrix and diamond particles within the metal matrix, with the metal matrix and the first metal layer forming an integral structure. In this way, the metal matrix of the diamond alloy layer and the first metal layer can form a continuous, interface-free, integrated structure. This creates a strong mutual attraction between adjacent metal atoms in the metal matrix and the first metal layer, thereby enhancing the cohesive force between the diamond alloy layer and the first metal layer. This effectively reduces the risk of delamination between the diamond alloy layer and the first metal layer, improving the structural stability of the composite structure.

[0014] In one possible implementation, the thermal conductivity of the composite structure is 500 W / mK to 900 W / mK.

[0015] When the thermal conductivity of the composite structure is within the above-mentioned appropriate range, it facilitates the rapid transfer of heat from the semiconductor device to the packaging substrate. This not only effectively reduces the junction temperature of the semiconductor device, but also reduces the temperature of the composite structure itself during the operation of the semiconductor device, resulting in a smaller temperature variation of the composite structure. When the temperature variation of the composite structure is small, the temperatures of its internal components are closer, and the internal stress caused by thermal expansion and contraction is reduced. This helps to improve the structural stability of the composite structure.

[0016] In one possible implementation, the thermal conductivity of the diamond alloy layer is 600 W / mK to 1000 W / mK.

[0017] When the thermal conductivity of the diamond alloy layer is within the aforementioned suitable range, heat from the semiconductor device can be quickly dissipated and temperature equalization can be achieved in a direction perpendicular to the heat dissipation path. This can rapidly reduce the junction temperature of the semiconductor device. Furthermore, when the thermal conductivity of the diamond alloy layer is within the aforementioned suitable range, the composite structure can exhibit high thermal conductivity even with a relatively small thickness. This allows for a certain degree of adjustment in the thickness ratio of the diamond alloy layer to the first metal layer, making the composite structure suitable for packaging structures of various sizes. This can further enhance the applicability of the composite structure.

[0018] In a possible implementation, the thermal expansion coefficient CTE1 of the first metal layer is 17 ppm / K to 25 ppm / K.

[0019] The thermal expansion coefficient CTE1 of the first metal layer is close to that of the metal heat sink. In other words, CTE1 can match the thermal expansion coefficient of the metal heat sink. In this way, when the temperature changes, the thermal deformation of the first metal layer and the metal heat sink is also relatively close. This can reduce the pulling of the first metal layer and the metal heat sink on the contact interface between the composite structure and the packaging substrate, and reduce the stress on the contact interface between the composite structure and the packaging substrate. As a result, the risk of delamination between the composite structure and the packaging substrate can be reduced, thereby improving the stability of the packaging structure of the semiconductor device.

[0020] In a possible implementation, the thermal expansion coefficient CTE2 of the diamond alloy layer is 5 ppm / K to 10 ppm / K.

[0021] The coefficient of thermal expansion (CTE2) of the diamond alloy layer is close to that of the semiconductor device. In other words, CTE2 can match the thermal expansion coefficient of the semiconductor device. As a result, when the temperature changes, the difference in thermal deformation between the diamond alloy layer and the semiconductor device is also small. This can reduce the pull of the diamond alloy layer and the semiconductor device on the contact interface between the composite structure and the semiconductor device, reducing the stress on the contact interface between the composite structure and the semiconductor device. This can reduce the risk of delamination between the composite structure and the semiconductor device, thereby improving the stability of the semiconductor device packaging structure.

[0022] In one possible implementation, a coefficient of thermal expansion CTE0 of the composite structure is 8.5 ppm / K to 11.5 ppm / K.

[0023] When the composite structure's coefficient of thermal expansion (CTE0) is within the aforementioned range, the overall thermal deformation of the composite structure during temperature changes can be kept within an appropriate range. Consequently, the composite structure's overall coefficient of thermal expansion (CTE0) can be matched with the thermal expansion coefficients of both the semiconductor device and the metal heat sink, thereby reducing the risk of delamination between the layers within the semiconductor device's packaging structure. This helps improve the stability of the semiconductor device's packaging structure.

[0024] In a possible implementation, the ratio of the thickness of the diamond alloy layer to the thickness of the first metal layer is 1:9 to 9:1.

[0025] On the one hand, when the ratio of the thickness of the diamond alloy layer to the thickness of the first metal layer is within the above-mentioned suitable range, the composite structure can have a high thermal conductivity, thereby facilitating the rapid transfer of heat from the semiconductor device to the packaging substrate. This not only effectively reduces the junction temperature of the semiconductor device, but also reduces the temperature of the composite structure itself during the semiconductor device process, resulting in a smaller temperature variation in the composite structure. When the temperature variation of the composite structure is small, the temperatures of its internal components are closer, and the internal stress caused by thermal expansion and contraction is reduced. This helps to improve the structural stability of the composite structure.

[0026] On the other hand, when the ratio of the thickness of the diamond alloy layer to the thickness of the first metal layer is within the aforementioned suitable range, the coefficient of thermal expansion (CTE0) of the composite structure can also be controlled within a suitable range. This allows the overall thermal deformation of the composite structure to be kept within a suitable range when temperature changes occur. As a result, the overall coefficient of thermal expansion (CTE0) of the composite structure can be adapted to match the thermal expansion coefficients of the semiconductor device and the metal heat sink, thereby reducing the risk of delamination between the layers in the semiconductor device's packaging structure. This helps improve the stability of the semiconductor device's packaging structure.

[0027] In one possible implementation, the thickness d of the diamond alloy layer and the diameter d1 of the diamond particles satisfy the following relationship: d1 ≤ d < 2d1. When these conditions are met, the thickness of the diamond alloy layer and the diameter of the diamond particles approximate. This allows the diamond particles to form a uniformly distributed single-layer structure within the diamond alloy layer.

[0028] On the one hand, compared to a multi-layered particle layer structure, heat conduction in a single particle layer only requires a single pass from metal to diamond particles and then back to metal. This reduces the number of heat transfer interfaces within the diamond alloy layer, thereby lowering the interfacial thermal resistance within the diamond alloy layer. This significantly improves the thermal conductivity of the diamond alloy layer.

[0029] On the other hand, compared with the multi-layer particle layer structure, the risk of diamond particles being squeezed in the single-layer particle layer structure is greatly reduced, thereby improving the structural stability of the diamond alloy layer.

[0030] In a possible implementation, the volume of the diamond particles in the diamond alloy layer accounts for 30% to 80%.

[0031] On the one hand, the greater the volume fraction of diamond particles in the diamond alloy layer, the higher the thermal conductivity of the diamond alloy layer. When the volume fraction of diamond particles in the diamond alloy layer is within the aforementioned suitable range, the thermal conductivity of the diamond alloy layer can be controlled within a suitable range. This facilitates rapid heat dissipation from the semiconductor device, effectively reducing the junction temperature of the semiconductor device.

[0032] On the other hand, when the volume fraction of diamond particles in the diamond alloy layer is within the above range, the thermal expansion coefficient CTE2 of the diamond alloy layer can also be matched with the thermal expansion coefficient of the semiconductor device. In this way, when the temperature changes, the difference in thermal deformation between the diamond alloy layer and the semiconductor device is also small. This can reduce the stress on the contact interface between the composite structure and the semiconductor device. This can reduce the pulling force of the diamond alloy layer and the semiconductor device on the contact interface between the composite structure and the semiconductor device, reducing the risk of delamination between the composite structure and the semiconductor device. This can also improve the stability of the semiconductor device packaging structure.

[0033] In a possible implementation, the surface of the diamond particles is further coated with a carbide layer, and the carbide layer includes at least one of titanium carbide and chromium carbide.

[0034] The carbide layer has a strong bonding force with the diamond particles and the metal matrix, which can reduce the risk of delamination at the interface between the diamond particles and the metal matrix and improve the stability of the internal structure of the diamond alloy layer.

[0035] In addition, the carbide layer has a strong bonding strength with the metal matrix, so the metal matrix can be applied to the surface of the diamond particles by electroplating or chemical plating. This allows the thickness of the metal matrix on the surface of the diamond particles to be flexibly adjusted, thereby enabling the interparticle spacing of the diamond particles to be controlled through the metal matrix.

[0036] The diamond particles have an appropriate interparticle spacing. On the one hand, the diamond particles can be evenly distributed within the diamond alloy layer, reducing the risk of diamond particles contacting each other and breaking when squeezed. On the other hand, the volume ratio of the diamond particles in the diamond alloy layer can be kept within an appropriate range, thereby controlling the thermal conductivity and CTE2 of the diamond alloy layer within an appropriate range. In this way, not only can the heat dissipation efficiency of the composite structure be improved, effectively reducing the junction temperature of the semiconductor device, but also the stability of the semiconductor device packaging structure can be improved.

[0037] In a possible implementation, the metal matrix includes at least one of copper, aluminum, and silver.

[0038] On the one hand, the metal matrix has higher thermal conductivity than other metals, which helps improve the thermal conductivity of the diamond alloy layer. On the other hand, the metal matrix also has good machinability and can interact with diamond particles to form a diamond alloy, thereby forming a structurally stable diamond alloy layer.

[0039] In a possible implementation, the first metal layer includes at least one of copper, aluminum, and silver, and the first metal layer and the metal substrate are made of the same metal.

[0040] The metal matrix of the first metal layer and the diamond alloy layer is made of the same metal, which helps to improve the interfacial compatibility between the first metal layer and the diamond alloy layer, thereby improving the interfacial tensile strength between the first metal layer and the diamond alloy layer. In this way, the risk of delamination within the composite structure can be further reduced.

[0041] In addition, compared to other metals, the aforementioned metals have higher thermal conductivity, which helps to improve the thermal conductivity of the first metal layer and further improve the thermal conductivity of the composite structure.

[0042] In a possible implementation, the first metal layer includes a first surface and a second surface, the first surface is connected to the diamond alloy layer, and the second surface is away from the diamond alloy layer and is provided with a groove.

[0043] The grooves on the second surface act as stress relief grooves, altering the stress distribution within the composite structure, thereby alleviating stress concentration and distributing stress more evenly within the composite structure. This reduces the risk of warping and enhances the strength and stability of the composite structure.

[0044] In a possible implementation, the width of the groove is 1 mm to 1.5 mm, and the depth of the groove is equal to the thickness of the first metal layer.

[0045] When the size of the groove is within the above-mentioned appropriate range, the stress concentration of the composite structure can be effectively reduced, the risk of warping of the composite structure can be reduced, and the strength and stability of the composite structure can be improved.

[0046] In a possible implementation, the second surface is provided with a plurality of grooves, at least one groove extends along a first direction on the second surface, and at least one groove extends along a second direction on the second surface, and the first direction intersects the second direction.

[0047] This can further reduce the stress concentration of the composite structure, reduce the risk of warping of the composite structure, and improve the strength and stability of the composite structure.

[0048] In a possible implementation, a second metal layer is further provided on a surface of the diamond alloy layer away from the first metal layer, and the thickness of the second metal layer is less than or equal to 100 μm.

[0049] The relatively small thickness of the second metal layer shortens the distance between the semiconductor device's heat source and the diamond alloy layer, facilitating rapid heat transfer from the semiconductor device to the diamond alloy layer. This allows heat from the semiconductor device to be rapidly conducted through the diamond alloy layer, rapidly reducing the semiconductor device's junction temperature.

[0050] On the other hand, when the thickness of the second metal layer is relatively small, the thermal deformation of the second metal layer is almost negligible if a temperature change occurs. Thus, the thermal deformation on both sides of the contact interface between the composite structure and the semiconductor device is primarily affected by the thermal expansion coefficients of the diamond alloy layer and the semiconductor device. The thermal expansion coefficients of the diamond alloy layer and the semiconductor device are close, resulting in similar thermal deformation on both sides of the contact interface between the composite structure and the semiconductor device. This effectively reduces the stress on the contact interface between the composite structure and the semiconductor device, lowering the risk of delamination at the contact interface between the composite structure and the semiconductor device.

[0051] In a second aspect, an embodiment of the present application provides a method for preparing a composite structure, comprising:

[0052] preparing a diamond alloy layer;

[0053] forming a first metal layer on one side of the diamond alloy layer to obtain a composite structure;

[0054] The composite structure includes a diamond alloy layer and a first metal layer, which are stacked and form an integral structure. The diamond alloy layer is used to connect to the semiconductor device; the first metal layer is used to connect to the packaging substrate.

[0055] In a third aspect, an embodiment of the present application provides a packaging structure, comprising: a semiconductor device, a packaging substrate, and any one of the above composite structures.

[0056] The diamond alloy layer in the composite structure is used to connect with the semiconductor device; and the first metal layer in the composite structure is used to connect with the packaging substrate.

[0057] In a possible implementation, the composite structure is connected to the semiconductor device via an adhesive, wherein the adhesive comprises at least one of nanosilver and gold-tin.

[0058] On the one hand, nanosilver and gold-tin have high thermal conductivity, which helps reduce the thermal resistance of the path from the semiconductor device to the composite structure, thereby improving the heat dissipation efficiency from the semiconductor device to the composite structure. In this way, it helps to reduce the junction temperature of the semiconductor device.

[0059] On the other hand, nanosilver and gold-tin have good interfacial adhesion to the substrate and composite structure of semiconductor devices, which is beneficial to improving the stability of the packaging structure. In this way, it helps to improve the reliability of the packaging structure.

[0060] In a possible implementation, the composite structure and the packaging substrate are integrally formed.

[0061] When the composite structure and the package substrate are integrally formed, there is no interface gap between the composite structure and the metal heat sink of the package substrate. This can improve the anti-delamination strength of the composite structure and the package substrate, thereby reducing the risk of delamination of the package structure.

[0062] In one possible implementation, the package substrate includes a metal heat sink and heat dissipation teeth. A groove is defined on the surface of the metal heat sink, facing away from the heat dissipation teeth, and at least a portion of the composite structure is accommodated within the groove. This provides support and protection for the package substrate, enhancing the stability of the package structure.

[0063] In a fourth aspect, an embodiment of the present application provides an electronic device comprising any of the above-mentioned packaging structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG1 is a schematic diagram of a packaging structure of a semiconductor device provided in an embodiment of the present application;

[0065] FIG2 is a schematic diagram of another semiconductor device packaging structure provided in an embodiment of the present application;

[0066] FIG3 is a first schematic diagram of a packaging structure of a semiconductor device provided in an embodiment of the present application;

[0067] FIG4 is a second schematic diagram of a packaging structure of a semiconductor device provided in an embodiment of the present application;

[0068] FIG5 is a third schematic diagram of a packaging structure of a semiconductor device provided in an embodiment of the present application;

[0069] FIG6 is a schematic structural diagram of a composite structure provided in an embodiment of the present application;

[0070] FIG7 is a schematic diagram of a packaging structure of another semiconductor device provided in an embodiment of the present application;

[0071] FIG8 is a schematic diagram of the internal structure of a diamond alloy layer in a composite structure provided in an embodiment of the present application;

[0072] FIG9 is a top view of a composite structure provided in an embodiment of the present application;

[0073] FIG10 is a cross-sectional view of a composite structure provided in an embodiment of the present application;

[0074] FIG11 is a second top view of a composite structure provided in an embodiment of the present application;

[0075] FIG12 is a second cross-sectional view of a composite structure provided in an embodiment of the present application;

[0076] FIG13 is a third top view of a composite structure provided in an embodiment of the present application;

[0077] FIG14 is a third cross-sectional view of a composite structure provided in an embodiment of the present application;

[0078] FIG15 is a schematic structural diagram of another composite structure provided in an embodiment of the present application;

[0079] FIG16 is a cross-sectional view of another composite structure provided in an embodiment of the present application;

[0080] FIG17 is a bottom view 1 of a composite structure provided in an embodiment of the present application;

[0081] FIG18 is a second bottom view of a composite structure provided in an embodiment of the present application;

[0082] FIG19 is a third bottom view of a composite structure provided in an embodiment of the present application;

[0083] FIG20 is a bottom view 4 of a composite structure provided in an embodiment of the present application;

[0084] FIG21 is an ultrasonic scanning microscope test image of the package structure prepared in Example 1 of the present application;

[0085] FIG22 is an ultrasonic scanning microscope test image of the package structure prepared in Comparative Example 1 in the embodiments of the present application;

[0086] FIG23 is an ultrasonic scanning microscope test image of the package structure prepared in Example 2 of the present application;

[0087] FIG24 is an ultrasonic scanning microscope test image of the packaging structure prepared in Example 3 of the embodiments of the present application. DETAILED DESCRIPTION

[0088] The following describes the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. In the description of the present application, unless otherwise specified, " / " indicates that the objects associated with each other are in an "or" relationship. For example, A / B can represent A or B. "And / or" in the present application is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0089] Furthermore, in the description of this application, unless otherwise specified, "plurality" means two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural.

[0090] At the same time, in the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner to facilitate understanding.

[0091] In the embodiment of the present application, simulation testing can be performed using simulation testing software known in the art. For example, comsol Multiphysics can be used for simulation testing.

[0092] In the embodiments of this application, thermal conductivity can be expressed as the amount of heat transferred per unit horizontal cross-sectional area per unit time when the vertical downward temperature gradient is 1°C / m. Specifically, it is defined as follows: if two parallel planes with an area of ​​1 square meter and a distance of 1 meter are taken perpendicular to the direction of heat conduction inside an object, and the temperature difference between the two planes is 1K, then the amount of heat transferred from one plane to the other in 1 second is defined as the thermal conductivity of the object, and its unit is watt-meter. -1 ·open -1 (W·m -1 ·K -1 ), can also be written as W / mK.

[0093] In the embodiment of the present application, thermal resistance may represent the ratio between the temperature difference at both ends of an object and the power of the heat source when heat is transferred on the object, and its unit is Kelvin per Watt (K / W) or degrees Celsius per Watt (℃ / W).

[0094] In the embodiment of the present application, the junction temperature may represent the actual operating temperature of a semiconductor device in an electronic device.

[0095] In an embodiment of the present application, a semiconductor device may include an electronic device having a conductivity between that of a good conductor and an insulator, and utilizing the special electrical properties of semiconductor materials to perform specific functions, and may be used to generate, control, receive, transform, amplify signals, and perform energy conversion. Specifically, the semiconductor device may include at least one of a logic chip, a memory chip, and a power chip. As an example, the semiconductor material of the semiconductor device may include, but is not limited to, at least one of silicon (Si), germanium (Ge), gallium arsenide (GaAs), silicon carbide (SiC), and gallium nitride (GaN).

[0096] As the junction temperature of the semiconductor device 10 increases, the performance of a radio frequency power amplifier using the semiconductor device 10 will be negatively affected.

[0097] Furthermore, as the junction temperature of the semiconductor device 10 rises, the power amplifier efficiency of the RF power amplifier and the energy efficiency of the remote radio unit (RRU) in the wireless base station will both decrease. Taking a gallium nitride (GaN) RF power amplifier as an example, for every 20°C increase in the junction temperature of the GaN chip inside it, the power amplifier efficiency of the GaN RF power amplifier will decrease by 1%, and the operating efficiency of the wireless base station's RRU will decrease by approximately 0.8%. Furthermore, excessively high junction temperatures can also cause degradation of the Schottky-Ohmic contact of the semiconductor device 10, seriously affecting the performance and service life of the semiconductor device 10.

[0098] In order to reduce the junction temperature of the semiconductor device 10, some RF power amplifiers are provided with a thermal conductor 30 inside. One end of the thermal conductor 30 is used to connect the semiconductor device 10, and the other end is used to connect the packaging substrate 50. In this way, the thermal conductor 30 can export the heat of the semiconductor device 10 to the packaging substrate 50, thereby reducing the junction temperature of the semiconductor device 10. Figure 1 is a schematic diagram of the packaging structure of the semiconductor device 10 provided in an embodiment of the present application. As shown in Figure 1, the substrate 11 of the semiconductor device 10 can be connected to the thermal conductor 30 through an adhesive 20, and the thermal conductor 30 is connected to the packaging substrate 50 through solder 40. By decomposing the heat dissipation path of the packaging structure, it can be found that: as shown by the arrow in Figure 1, in the heat dissipation path from the hot point 12 of the semiconductor device 10 through the substrate 11 and the adhesive 20 to the thermal conductor 30, the thermal resistance of the thermal conductor 30 accounts for a relatively high proportion in the thermal resistance of the path. In this way, when the thickness of the thermal conductor 30 is the same, improving the thermal conductivity of the thermal conductor 30 can reduce the thermal resistance of the thermal conductor 30. As the thermal resistance of the heat conductor 30 decreases, the total thermal resistance of the above-mentioned path also decreases. As a result, the heat of the semiconductor device 10 can be quickly transferred to the package substrate 50 via the above-mentioned heat dissipation path, thereby effectively reducing the junction temperature of the semiconductor device 10. Therefore, improving the thermal conductivity of the heat conductor 30 is of great significance for reducing the junction temperature of the semiconductor device 10.

[0099] A commonly used thermal conductor 30 in the related art is a copper-molybdenum copper-copper (CPC) flange. However, the maximum thermal conductivity of the CPC flange is only about 250 W / mK, which cannot effectively reduce the junction temperature of the semiconductor device 10.

[0100] A diamond alloy flange in the related art includes an alloy composed of diamond particles and metal, with a coefficient of thermal expansion (CTE) of 3.8 ppm / K to 5.8 ppm / K. The CTE of the diamond copper alloy flange differs significantly from that of the metal heat sink on the surface of the package substrate 50. For example, a copper heat sink has a CTE of approximately 17 ppm / K. The difference between the CTE of the diamond copper alloy flange and the copper heat sink exceeds 50% of the CTE of the copper heat sink, resulting in a CTE mismatch between the diamond copper alloy flange and the copper heat sink. When the CTE mismatch occurs, the thermal deformation of the structures on both sides of the interface between the diamond copper alloy flange and the metal heat sink differs significantly if the temperature changes. This results in high stress concentration in the solder layer between the flange and the metal heat sink. As shown in Figure 1, if the thermal deformation of the thermal conductor 30 and the metal heat sink on the surface of the package substrate 50 is large, high stress will be concentrated in the solder layer formed by the solder 40, causing excessive tension in the solder 40. This in turn leads to the risk of delamination between the diamond copper alloy flange and the metal heat sink.

[0101] In a copper-diamond copper alloy-copper flange of the related art, the thickness ratio of the copper layer on one side, the diamond copper alloy layer, and the copper layer on the other side is generally 1:8:1 to 3:4:3. However, under this structure, the copper layer connecting the copper-diamond copper alloy-copper flange to the semiconductor device 10 side will seriously reduce the heat dissipation efficiency. A simulation test was carried out using a diamond copper alloy with a thermal conductivity of 850W / mK and a thermal expansion coefficient of 5.3ppm / K to simulate the maximum junction temperature of the semiconductor device 10 in the RF power amplifier and the path thermal resistance of the heat dissipation path from the hot point 12 of the semiconductor device 10 through the substrate 11, the adhesive 20 to the heat conductor 30 under different copper layer thicknesses when the total thickness of the copper-diamond copper alloy-copper flange remains unchanged. The simulation results are shown in Table 1. As can be seen from Table 1, an increase in the copper layer thickness will significantly increase the maximum junction temperature and path thermal resistance of the semiconductor device 10, resulting in the copper-diamond copper alloy-copper flange being unable to meet the heat dissipation requirements of the semiconductor device 10.

[0102] Table 1

[0103] In order to solve the above technical problems, the embodiments of the present application provide a composite structure 60 and a preparation method thereof, a packaging structure using the composite structure 60 , and an electronic device.

[0104] In the embodiment of the present application, the electronic device may include a high-power electronic device, an optoelectronic device, a radio frequency device, a blue light LED, or other product including the semiconductor device 10 .

[0105] In some embodiments of the present application, the electronic device may include a radio frequency power amplifier. The radio frequency power amplifier may be applied to a wireless base station. Exemplarily, the radio frequency power amplifier may be applied to at least one of a remote radio unit (RRU) and a multiple-input multiple-output (MIMO) module of the wireless base station.

[0106] The radio frequency power amplifier may include a preamplifier, a driver amplifier, and a final power amplifier. The composite structure 60 of the embodiment of the present application may be applied to the final power amplifier. Specifically, the final power amplifier may include the packaging structure shown in FIG2 .

[0107] As shown in FIG2 , the package structure may include a semiconductor device 10, a package substrate 50, and a composite structure 60. Composite structure 60 may include a stacked diamond alloy layer 61 and a first metal layer 62. Diamond alloy layer 61 and first metal layer 62 form an integral structure. Diamond alloy layer 61 is used to connect to semiconductor device 10, and first metal layer 62 is used to connect to package substrate 50. Package substrate 50 may include, but is not limited to, a heat sink substrate and a printed circuit board (PCB) substrate.

[0108] On the one hand, compared to the first metal layer 62, the diamond alloy layer 61 has a higher thermal conductivity. By connecting the diamond alloy layer 61 to the semiconductor device 10, the heat of the semiconductor device 10 can be quickly dissipated and the temperature can be evenly distributed in the horizontal direction (perpendicular to the heat dissipation path described in Figure 1). In this way, the junction temperature of the semiconductor device 10 can be quickly reduced, thereby improving the power amplification efficiency of the RF power amplifier.

[0109] On the other hand, the thermal expansion coefficient of the diamond alloy layer 61 is close to that of the semiconductor device 10, and the thermal expansion coefficient of the first metal layer 62 is close to that of the metal heat sink 51 on the surface of the package substrate 50. As a result, when the temperature changes, the difference in thermal deformation between the two sides of the contact interface between the composite structure 60 and the semiconductor device 10 is small, and the difference in thermal deformation between the two sides of the contact interface between the composite structure 60 and the package substrate 50 is also small. This reduces the stress on the contact interfaces between the composite structure 60 and the semiconductor device 10, and between the composite structure 60 and the package substrate 50.

[0110] In this way, in the packaging structure of the semiconductor device 10, the interface that is subjected to high stress is the interface 612 between the diamond alloy layer 61 and the first metal layer 62. The interface 612 between the diamond alloy layer 61 and the first metal layer 62 is located inside the composite structure 60. The diamond alloy layer 61 and the first metal layer 62 are an integral structure, and there is no interface gap between the two layers. As a result, there can be mutual attraction between adjacent metal atoms at the interface 612 between the diamond alloy layer 61 and the first metal layer 62, thereby giving the diamond alloy layer 61 and the first metal layer 62 a certain cohesive force. The existence of cohesive force makes the interface between the diamond alloy layer 61 and the first metal layer 62 have extremely high anti-delamination strength, thereby improving the structural stability of the composite structure 60. In turn, it can significantly improve the structural stability of each interface in the packaging structure of the semiconductor device 10 and reduce the risk of delamination of the packaging structure.

[0111] In some embodiments of the present application, the diamond alloy layer 61 may be directly connected to the semiconductor device 10. In this way, the diamond alloy layer 61 can directly dissipate heat from the semiconductor device 10, thereby improving the heat dissipation efficiency of the composite structure 60 and further reducing the junction temperature of the semiconductor device 10.

[0112] FIG3 is a first schematic diagram of a package structure for a semiconductor device 10 according to another embodiment of the present application. As shown in FIG3 , in one possible implementation, the composite structure 60 may further include a second metal layer 63. The second metal layer 63 may be disposed on a surface of the diamond alloy layer 61 that is distal from the first metal layer 62. In this implementation, the diamond alloy layer 61 may be connected to the semiconductor device 10 via the second metal layer 63.

[0113] The thickness of the second metal layer 63 may be less than or equal to 100 μm. Specifically, the thickness of the second metal layer 63 may be 100 μm or any value between 0 and 100 μm, for example, 100 μm, 80 μm, 50 μm, 30 μm, 20 μm, 10 μm, 8 μm, 5 μm, 3 μm, 2 μm, 1 μm, 0.5 μm, 0.1 μm, 0.01 μm, etc. These values ​​are not listed here.

[0114] In the above implementation, the second metal layer 63 has a relatively small thickness. On the one hand, this can shorten the distance between the hot spot 12 of the semiconductor device 10 and the diamond alloy layer 61, facilitating rapid heat transfer from the semiconductor device 10 to the diamond alloy layer 61. In this way, heat from the semiconductor device 10 can be quickly conducted away through the diamond alloy layer 61, thereby rapidly reducing the junction temperature of the semiconductor device 10. On the other hand, when the thickness of the second metal layer 63 is relatively small, the thermal deformation of the second metal layer 63 is almost negligible if a temperature change occurs. Thus, the thermal deformation on both sides of the contact interface between the composite structure 60 and the semiconductor device 10 is primarily affected by the thermal expansion coefficients of the diamond alloy layer 61 and the semiconductor device 10. The thermal expansion coefficients of the diamond alloy layer 61 and the semiconductor device 10 are close, resulting in similar thermal deformation on both sides of the contact interface between the composite structure 60 and the semiconductor device 10. This effectively reduces the stress on the contact interface between the composite structure 60 and the semiconductor device 10, and reduces the risk of delamination at the contact interface between the composite structure 60 and the semiconductor device 10.

[0115] In a possible implementation, the composite structure 60 may be connected to the semiconductor device 10 via an adhesive 20. The adhesive 20 may include at least one of nanosilver and gold-tin.

[0116] On the one hand, nanosilver and gold-tin have high thermal conductivity, which helps reduce the thermal resistance of the path from semiconductor device 10 to composite structure 60, thereby improving the heat dissipation efficiency from semiconductor device 10 to composite structure 60. This helps reduce the junction temperature of semiconductor device 10. On the other hand, nanosilver and gold-tin have good interfacial adhesion to both the substrate 11 of semiconductor device 10 and composite structure 60, which helps improve the stability of the package structure and thus the reliability of the package structure.

[0117] In a possible implementation, the composite structure 60 may be connected to the package substrate 50 via a solder 40. The solder 40 may include, but is not limited to, solder.

[0118] For example, in some embodiments of the present application, a second schematic diagram of a package structure of a semiconductor device 10 may be shown in FIG4 . Referring to FIG4 , the diamond alloy layer 61 of the composite structure 60 may be connected to the semiconductor device 10 via an adhesive 20 . The first metal layer 62 of the composite structure 60 may be connected to the package substrate 50 via solder 40 .

[0119] FIG5 is a third schematic diagram of a semiconductor device 10 package structure according to another embodiment of the present application. As shown in FIG5 , the package substrate 50 may include a metal heat sink 51 and heat dissipation tines 52. The metal heat sink 51 and heat dissipation tines 52 may be stacked. The metal heat sink 51 may be located on a surface of the package substrate 50 proximal to the composite structure 60 and may be connected to the composite structure 60.

[0120] In a possible implementation, a groove is provided on the surface of the metal heat sink 51 away from the heat dissipation teeth 52 , and at least a portion of the composite structure 60 is accommodated in the groove.

[0121] 5 , in a possible implementation, the packaging structure may further include a housing 70. As an example, the housing 70 may be made of at least one of ceramic and plastic.

[0122] 5 , in one possible implementation, the package structure may further include a printed circuit board (PCB) 80 disposed on the surface of the metal heat sink 51 . The PCB 80 can play a certain supporting role and serve as a provider of electrical connections for the semiconductor device 10 .

[0123] In the package structure, the housing 70, the PCB 80, and the package substrate 50 can enclose a cavity 01, and the semiconductor device 10 can be encapsulated in the cavity 01. The composite structure 60 can include a diamond alloy layer 61 (not shown) and a first metal layer 62 (not shown). The diamond alloy layer 61 can be connected to the semiconductor device 10 via an adhesive 20. The first metal layer 62 can be connected to the metal heat sink 51 of the package substrate 50 via solder 40.

[0124] In a possible implementation, the first metal layer 62 of the composite structure 60 may be integrally formed with the packaging substrate 50 .

[0125] For example, the first metal layer 62 of the composite structure 60 can be integrally formed with the metal heat sink 51 of the package substrate 50. For example, the first metal layer 62 of the composite structure 60 can also be integrally formed with the metal heat sink 51 and the heat dissipation teeth 52 of the package substrate 50.

[0126] In the above implementation, integral molding may mean that a continuous integrated structure without interface gaps is formed between the components.

[0127] When the first metal layer 62 of the composite structure 60 is integrally formed with the package substrate 50, no interfacial gap exists between the composite structure 60 and the metal heat sink 51 of the package substrate 50. This improves the delamination resistance of the composite structure 60 and the package substrate 50, thereby reducing the delamination risk of the package structure.

[0128] In one possible implementation, the first metal layer 62 and the metal heat sink 51 of the package substrate 50 may comprise the same metal. This helps to improve the tensile strength of the integrated structure of the first metal layer 62 and the package substrate 50, thereby further improving the stability of the package structure.

[0129] FIG6 is a schematic diagram of a composite structure 60 according to an embodiment of the present application. As shown in FIG6 , the composite structure 60 may include a diamond alloy layer 61 and a first metal layer 62. The diamond alloy layer 61 and the first metal layer 62 are stacked and form an integral structure.

[0130] The diamond alloy layer 61 is used to connect to the semiconductor device 10 , and the first metal layer 62 is used to connect to the package substrate 50 .

[0131] On the one hand, the diamond alloy layer 61 has a higher thermal conductivity than the first metal layer 62. By connecting the diamond alloy layer 61 to the semiconductor device 10, heat from the semiconductor device 10 can be quickly dissipated and the temperature can be evenly distributed laterally. This can rapidly reduce the junction temperature of the semiconductor device 10.

[0132] On the other hand, the thermal expansion coefficient of the diamond alloy layer 61 is close to that of the semiconductor device 10, and the thermal expansion coefficient of the first metal layer 62 is close to that of the metal heat sink 51 on the surface of the package substrate 50. As a result, when the temperature changes, the difference in thermal deformation between the two sides of the contact interface between the composite structure 60 and the semiconductor device 10 is small, and the difference in thermal deformation between the two sides of the contact interface between the composite structure 60 and the package substrate 50 is also small. This results in reduced stress at the contact interface between the composite structure 60 and the semiconductor device 10, and at the contact interface between the composite structure 60 and the package substrate 50.

[0133] Therefore, unlike the diamond copper alloy flange in the related art, when the composite structure 60 provided in the embodiment of the present application is applied to the packaging structure of the semiconductor device 10 as shown in Figure 7, the interface subjected to high stress is no longer the solder 40, but the interface 612 between the diamond alloy layer 61 and the first metal layer 62. The interface 612 between the diamond alloy layer 61 and the first metal layer 62 is located inside the composite structure 60. The diamond alloy layer 61 and the first metal layer 62 are an integral structure, and there is no interface gap between the two layers. As a result, there can be mutual attraction between the adjacent metal atoms at the interface 612 between the diamond alloy layer 61 and the first metal layer 62, thereby giving the diamond alloy layer 61 and the first metal layer 62 a certain cohesive force. The existence of cohesive force makes the interface 612 between the diamond alloy layer 61 and the first metal layer 62 have extremely high anti-delamination strength, and delamination is not easy to occur, thereby improving the structural stability of the composite structure 60. Thus, when the composite structure 60 provided in the embodiment of the present application is applied to the packaging structure of the semiconductor device 10 , it can significantly improve the structural stability of each interface in the packaging structure and reduce the risk of delamination of the packaging structure.

[0134] In one possible implementation, the diamond alloy layer 61 may include a metal matrix 61c and diamond particles 61a within the metal matrix 61c. The metal matrix 61c and the first metal layer 62 may be an integral structure. Thus, the metal matrix 61c of the diamond alloy layer 61 may form a continuous, interface-free, integral structure with the first metal layer 62. Consequently, a strong mutual attraction may exist between adjacent metal atoms in the metal matrix 61c and the first metal layer 62, thereby enhancing the cohesive force between the diamond alloy layer 61 and the first metal layer 62. This can effectively reduce the risk of delamination between the diamond alloy layer 61 and the first metal layer 62, thereby improving the structural stability of the composite structure 60.

[0135] In one possible implementation, the thermal conductivity of the composite structure 60 may be 500 W / mK to 900 W / mK. Specifically, the thermal conductivity of the composite structure 60 may be 500 W / mK, 900 W / mK, or any value between 500 W / mK and 900 W / mK, such as 500 W / mK, 600 W / mK, 700 W / mK, 800 W / mK, 900 W / mK, etc. These values ​​are not listed here.

[0136] When the thermal conductivity of the composite structure 60 is within the above-mentioned appropriate range, it facilitates rapid transfer of heat from the semiconductor device 10 to the packaging substrate 50. This effectively reduces not only the junction temperature of the semiconductor device 10 but also the temperature of the composite structure 60 itself during operation, resulting in minimal temperature fluctuations within the composite structure 60. When the temperature fluctuations within the composite structure 60 are minimal, the temperatures of its various internal components are relatively close, reducing the internal stresses caused by thermal expansion and contraction. This improves the structural stability of the composite structure 60.

[0137] It should be noted that the thermal conductivity of the composite structure 60 can be controlled in a variety of ways. For example, the thermal conductivity of the composite structure 60 can be controlled by adjusting the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62, the volume ratio of the diamond particles 61a in the diamond alloy layer 61, the distribution of the diamond particles 61a, the type of metal matrix 61c in the diamond alloy layer 61, the type of metal in the first metal layer 62, etc. This embodiment of the present application is not limited in this regard.

[0138] In one possible implementation, the thermal conductivity of the diamond alloy layer 61 may be 600 W / mK to 1000 W / mK. Specifically, the thermal conductivity of the diamond alloy layer 61 may be 600 W / mK, 1000 W / mK, or any value between 600 W / mK and 1000 W / mK, such as 600 W / mK, 700 W / mK, 800 W / mK, 900 W / mK, 1000 W / mK, etc. A full list of these values ​​is omitted here.

[0139] When the thermal conductivity of the diamond alloy layer 61 is within the aforementioned suitable range, heat from the semiconductor device 10 can be quickly dissipated and the temperature can be evenly distributed laterally. This can rapidly reduce the junction temperature of the semiconductor device 10. Furthermore, when the thermal conductivity of the diamond alloy layer 61 is within the aforementioned suitable range, the composite structure 60 can have a high thermal conductivity even if the diamond alloy layer 61 has a relatively small thickness. This allows for a certain degree of adjustment in the thickness ratio between the diamond alloy layer 61 and the first metal layer 62, making the composite structure 60 suitable for packaging structures of various sizes. This, in turn, improves the applicability of the composite structure 60.

[0140] It should be noted that the thermal conductivity of the diamond alloy layer 61 can be controlled in a variety of ways. For example, the thermal conductivity of the diamond alloy layer 61 can be controlled by adjusting the volume ratio of the diamond particles 61a in the diamond alloy layer 61, the distribution of the diamond particles 61a, the type of the metal matrix 61c in the diamond alloy layer 61, etc. This embodiment of the present application is not limited in this regard.

[0141] In one possible implementation, the coefficient of thermal expansion CTE1 of the first metal layer 62 may be 17 ppm / K to 25 ppm / K. Specifically, CTE1 may be 17 ppm / K, 25 ppm / K, or any value between 17 ppm / K and 25 ppm / K, such as 17 ppm / K, 19 ppm / K, 20 ppm / K, 22 ppm / K, 24 ppm / K, 25 ppm / K, etc. These values ​​are not listed here.

[0142] The thermal expansion coefficient CTE1 of the first metal layer 62 is close to that of the metal heat sink 51. In other words, CTE1 can match the thermal expansion coefficient of the metal heat sink 51. In this way, when the temperature changes, the thermal deformation of the first metal layer 62 and the metal heat sink 51 is also relatively close. In turn, it is possible to reduce the pulling of the first metal layer 62 and the metal heat sink 51 on the contact interface between the composite structure 60 and the packaging substrate 50, and reduce the stress on the contact interface between the composite structure 60 and the packaging substrate 50. As a result, the risk of delamination between the composite structure 60 and the packaging substrate 50 can be reduced. This in turn improves the stability of the packaging structure of the semiconductor device 10.

[0143] It should be noted that the thermal expansion coefficient CTE1 of the first metal layer 62 can be controlled in various ways. As an example, the thermal expansion coefficient CTE1 of the first metal layer 62 can be controlled by adjusting the type of metal in the first metal layer 62. This embodiment of the application is not limited to this.

[0144] In one possible implementation, the coefficient of thermal expansion CTE2 of the diamond alloy layer 61 may be 5 ppm / K to 10 ppm / K. Specifically, CTE2 may be 5 ppm / K, 10 ppm / K, or any value between 5 ppm / K and 10 ppm / K, such as 5 ppm / K, 6 ppm / K, 7 ppm / K, 8 ppm / K, 9 ppm / K, 10 ppm / K, etc. These values ​​are not listed here.

[0145] The coefficient of thermal expansion (CTE2) of the diamond alloy layer 61 is close to that of the semiconductor device 10. In other words, CTE2 can match the coefficient of thermal expansion of the semiconductor device 10. As a result, when the temperature changes, the difference in thermal deformation between the diamond alloy layer 61 and the semiconductor device 10 is also small. This can reduce the pulling force exerted by the diamond alloy layer 61 and the semiconductor device 10 on the contact interface between the composite structure 60 and the semiconductor device 10, thereby reducing the stress on the contact interface between the composite structure 60 and the semiconductor device 10. This can reduce the risk of delamination between the composite structure 60 and the semiconductor device 10, thereby improving the stability of the semiconductor device 10 packaging structure.

[0146] It should be noted that the thermal expansion coefficient CTE2 of the diamond alloy layer 61 can be controlled in a variety of ways. For example, the thermal expansion coefficient CTE2 of the diamond alloy layer 61 can be controlled by adjusting the type of the metal matrix 61c in the diamond alloy layer 61, the volume ratio of the diamond particles 61a in the diamond alloy layer 61, etc. This embodiment of the present application is not limited to this.

[0147] In one possible implementation, the coefficient of thermal expansion (CTE0) of the composite structure 60 may be 8.5 ppm / K to 11.5 ppm / K. Specifically, CTE0 may be 8.5 ppm / K, 11.5 ppm / K, or any value between 8.5 ppm / K and 11.5 ppm / K, such as 8.5 ppm / K, 9 ppm / K, 9.5 ppm / K, 10 ppm / K, 10.5 ppm / K, 11 ppm / K, 11.5 ppm / K, etc. These values ​​are not listed here.

[0148] When the coefficient of thermal expansion (CTE0) of the composite structure 60 is within the aforementioned range, the thermal deformation of the composite structure 60 as a whole can be kept within an appropriate range when temperature changes occur. As a result, the overall thermal expansion coefficient (CTE0) of the composite structure 60 can be matched with the thermal expansion coefficients of the semiconductor device 10 and the metal heat sink 51, thereby reducing the risk of delamination between the various layers in the semiconductor device 10 package structure. This helps improve the stability of the semiconductor device 10 package structure.

[0149] It should be noted that the thermal expansion coefficient CTE0 of the composite structure 60 can be controlled in a variety of ways. For example, the thermal expansion coefficient CTE0 of the composite structure 60 can be controlled by adjusting the thermal expansion coefficient CTE1 of the first metal layer 62, the thermal expansion coefficient CTE2 of the diamond alloy layer 61, the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62, the dimensions of the composite structure 60, etc. This embodiment of the present application is not limited in this regard.

[0150] In one possible implementation, the volume percentage of the diamond particles 61 a in the diamond alloy layer 61 is 30% to 80%. Specifically, the volume percentage of the diamond particles 61 a in the diamond alloy layer 61 can be 30%, 80%, or any value between 30% and 80%, such as 30%, 40%, 50%, 60%, 70%, 80%, etc. These values ​​are not listed here.

[0151] On the one hand, the greater the volume fraction of the diamond particles 61a in the diamond alloy layer 61, the higher the thermal conductivity of the diamond alloy layer 61. When the volume fraction of the diamond particles 61a in the diamond alloy layer 61 is within the aforementioned suitable range, the thermal conductivity of the diamond alloy layer 61 can be controlled within a suitable range. This facilitates rapid heat dissipation from the semiconductor device 10 and effectively reduces the junction temperature of the semiconductor device 10.

[0152] On the other hand, when the volume fraction of the diamond particles 61a in the diamond alloy layer 61 is within the above range, the thermal expansion coefficient CTE2 of the diamond alloy layer 61 can also be matched with the thermal expansion coefficient of the semiconductor device 10. In this way, when the temperature changes, the difference in thermal deformation between the diamond alloy layer 61 and the semiconductor device 10 is also small. This can reduce the stress on the contact interface between the composite structure 60 and the semiconductor device 10. As a result, the pulling of the diamond alloy layer 61 and the semiconductor device 10 on the contact interface between the composite structure 60 and the semiconductor device 10 can be reduced, reducing the risk of delamination between the composite structure 60 and the semiconductor device 10. This can improve the stability of the packaging structure of the semiconductor device 10.

[0153] In one possible implementation, the thickness d of the diamond alloy layer 61 and the particle size d1 of the diamond particles 61a may satisfy the following relationship: d1 ≤ d < 2d1. Specifically, the thickness d of the diamond alloy layer 61 may be d1 or any value between d1 and 2d1. For example, d may be d1, 1.1d1, 1.2d1, 1.3d1, 1.4d1, 1.5d1, 1.6d1, 1.7d1, 1.8d1, 1.9d1, 1.92d1, 1.95d1, 1.99d1, etc. These values ​​are not listed here.

[0154] When the thickness d of the diamond alloy layer 61 and the particle size d1 of the diamond particles 61a meet the above conditions, the thickness of the diamond alloy layer 61 is close to the particle size of the diamond particles 61a. In this way, the diamond particles 61a can form a uniformly distributed single-layer particle structure inside the diamond alloy layer 61.

[0155] If the diamond particles 61a form a multi-layered particle layer structure within the diamond alloy layer 61, during heat conduction, the heat needs to undergo a process of multiple transfers from the metal to the diamond particles 61a, and then from the diamond particles 61a to the metal matrix 61c. There is a large interfacial thermal resistance between the metal matrix 61c and the diamond particles 61a, thereby reducing the thermal conductivity of the diamond alloy layer 61. Furthermore, in a multi-layered particle layer structure, compression may occur between the diamond particle layers, causing the diamond particles 61a to break or the layer structure to be destroyed. This results in a decrease in the structural stability of the diamond alloy layer 61.

[0156] On the one hand, compared to a multi-layer particle layer structure, when heat conduction occurs, heat in a single-layer particle layer structure only needs to undergo a single process of transfer from the metal matrix 61c to the diamond particles 61a, and then from the diamond particles 61a to the metal matrix 61c. This can reduce the heat transfer interface within the diamond alloy layer 61, thereby reducing the interfacial thermal resistance within the diamond alloy layer 61. In this way, the thermal conductivity of the diamond alloy layer 61 can be significantly improved. On the other hand, compared to a multi-layer particle layer structure, the risk of extrusion of the diamond particles 61a in a single-layer particle layer structure is greatly reduced, thereby improving the structural stability of the diamond alloy layer 61.

[0157] In a possible implementation, the metal matrix 61 c of the diamond alloy layer 61 may include at least one of copper (Cu), aluminum (Al), and silver (Ag).

[0158] On the one hand, compared to other metals, the metal matrix 61c has higher thermal conductivity, which helps improve the thermal conductivity of the diamond alloy layer 61. On the other hand, the metal matrix 61c also has good machinability and can interact with the diamond particles 61a to form a diamond alloy, thereby forming a diamond alloy layer 61 with a stable structure.

[0159] In addition, the diamond alloy layer 61 formed by the metal matrix 61c and the diamond particles 61a has a suitable coefficient of thermal expansion CTE2, which facilitates matching of CTE2 with the coefficient of thermal expansion of the semiconductor device 10. As a result, when the temperature changes, the difference in thermal deformation between the diamond alloy layer 61 and the semiconductor device 10 is also small. This can reduce the pulling of the diamond alloy layer 61 and the semiconductor device 10 on the contact interface between the composite structure 60 and the semiconductor device 10, and reduce the stress on the contact interface between the composite structure 60 and the semiconductor device 10. As a result, the risk of delamination between the composite structure 60 and the semiconductor device 10 can be reduced, thereby improving the stability of the packaging structure of the semiconductor device 10.

[0160] In a possible implementation, the surface of the diamond particles 61a may be coated with a carbide layer 61b. The carbide layer 61b may include at least one of titanium carbide and chromium carbide.

[0161] Figure 8 is a schematic diagram of the internal structure of a diamond alloy layer 61 provided in an embodiment of the present application. As shown in Figure 8, the surface of diamond particles 61a may be coated with a carbide layer 61b, and the surface of carbide layer 61b may be coated with a metal matrix 61c. Exemplarily, carbide layer 61b may include at least one of titanium carbide and chromium carbide.

[0162] The carbide layer 61 b ​​has a strong bonding force with the diamond particles and the metal matrix 61 c , which can reduce the risk of delamination at the interface between the diamond particles 61 a and the metal matrix 61 c and improve the stability of the internal structure of the diamond alloy layer 61 .

[0163] In addition, the carbide layer 61b and the metal matrix 61c have a strong bonding force, so the metal matrix 61c can be coated on the surface of the diamond particles 61a by electroplating or chemical plating. As a result, the thickness of the metal matrix 61c on the surface of the diamond particles 61a can be flexibly adjusted, so that the particle spacing of the diamond particles 61a can be regulated by the metal matrix 61c. Specifically, the metal matrix 61c can be coated on the surface of the diamond particles 61a by electroplating or chemical plating to form a metal matrix 61c coating. In this way, the particle spacing of the diamond particles 61a is equal to the sum of twice the thickness of the carbide layer 61b and the thickness of the metal matrix 61c coating between the diamond particles 61a.

[0164] The diamond particles 61a have an appropriate interparticle spacing. This, on the one hand, allows the diamond particles 61a to be evenly distributed within the diamond alloy layer 61, reducing the risk of the diamond particles 61a contacting each other and thus breaking when squeezed. On the other hand, it also allows the volume fraction of the diamond particles 61a in the diamond alloy layer 61 to be within an appropriate range, thereby controlling the thermal conductivity and CTE2 of the diamond alloy layer 61 within a suitable range. This not only improves the heat dissipation efficiency of the composite structure 60 and effectively reduces the junction temperature of the semiconductor device 10, but also enhances the stability of the packaging structure of the semiconductor device 10.

[0165] In one possible implementation, the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62 may be 1:9 to 9:1. Specifically, the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62 may be 1:9, 9:1, or any value between 1:9 and 9:1, such as 1:9, 1:4, 3:7, 2:3, 1:1, 3:2, 7:3, 4:1, 9:1, etc. A full list of these ratios is omitted here.

[0166] On the one hand, when the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62 is within the above-mentioned suitable range, the composite structure 60 can have a high thermal conductivity, thereby facilitating the rapid transfer of heat from the semiconductor device 10 to the packaging substrate 50. This not only effectively reduces the junction temperature of the semiconductor device 10, but also reduces the temperature of the composite structure 60 itself during the process of the semiconductor device 10, resulting in a smaller temperature variation in the composite structure 60. When the temperature variation of the composite structure 60 is small, the temperatures of its internal components are relatively close, and the internal stress generated by thermal expansion and contraction is reduced. This helps to improve the structural stability of the composite structure 60.

[0167] On the other hand, when the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62 is within the aforementioned suitable range, the coefficient of thermal expansion (CTE0) of the composite structure 60 can also be controlled within a suitable range. In this way, when temperature changes occur, the thermal deformation of the composite structure 60 as a whole can be kept within a suitable range. As a result, the overall coefficient of thermal expansion (CTE0) of the composite structure 60 can meet the requirements for matching the coefficients of thermal expansion of the semiconductor device 10 and the metal heat sink 51, thereby reducing the risk of delamination between the various layers in the semiconductor device 10 packaging structure. This helps improve the stability of the semiconductor device 10 packaging structure.

[0168] Furthermore, simulation tests were conducted using a composite structure 60 consisting of a diamond alloy layer 61 (diamond-copper alloy) with a thermal conductivity of 850 W / mK and a thermal expansion coefficient of 5.3 ppm / K and a first metal layer 62 (copper layer). The simulations examined the thermal resistance of the heat dissipation path within the RF power amplifier, from the heat source 12 of the semiconductor device 10 through the substrate 11 and adhesive 20 to the composite structure 60, while maintaining the same thickness of the composite structure 60 and varying the thickness ratio of the diamond alloy layer 61 to the first metal layer 62. The simulation results are shown in Table 2.

[0169] Table 2

[0170] It can be seen from Table 2 that when the thickness of the composite structure 60 remains unchanged, the reduction in the proportion of the thickness of the diamond alloy layer 61 does not cause a significant increase in the path thermal resistance. It can be seen that in the composite structure 60 of the embodiment of the present application, the diamond alloy layer 61 connected to the semiconductor device 10 can quickly extract the heat of the semiconductor device 10 and evenly distribute the temperature in the lateral direction. Therefore, the structure of the composite structure 60 is significantly superior to the copper-diamond copper alloy-copper flange of the related art in reducing the path thermal resistance. It can be seen that from the perspective of heat dissipation requirements, the diamond alloy layer 61 is not required to be too thick, so the thickness of the first metal layer 62 has a certain adjustment space. As a result, the composite structure 60 can be applied to packaging structures of various sizes. This can further improve the applicability of the composite structure 60.

[0171] In a possible implementation, the length of the composite structure 60 may be 5 mm to 50 mm, the width of the composite structure 60 may be 5 mm to 50 mm, and the thickness of the composite structure 60 may be 1 mm to 3 mm.

[0172] For example, the area (ie, length×width) of the composite structure 60 may be between 5 mm×5 mm and 50 mm×50 mm.

[0173] Specifically, the length of the composite structure 60 can be 5 mm, 50 mm, or any value between 5 mm and 50 mm, such as 5 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, etc. These values ​​are not listed here.

[0174] Specifically, the width of the composite structure 60 can be 5 mm, 50 mm, or any value between 5 mm and 50 mm, such as 5 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, etc. These values ​​are not listed here.

[0175] Specifically, the thickness of the composite structure 60 can be 1 mm, 3 mm, or any value between 1 mm and 3 mm, for example, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, etc. These values ​​are not listed here.

[0176] As the size of the composite structure 60 changes, the stress at the interface between the composite structure 60 and the metal heat sink 51 also changes. For different sizes of the composite structure 60, the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62 and the particle size of the diamond particles 61a can be adjusted to adjust the thermal conductivity and CTE0 of the composite structure 60. This improves the heat dissipation efficiency of the composite structure 60 and reduces the risk of delamination between the composite structure 60 and the packaging substrate 50.

[0177] Specifically, when the thickness of each layer in the composite structure 60 remains unchanged, as the product of the length and width of the composite structure 60 increases, the CTE0 of the composite structure 60 decreases, thereby reducing the degree of thermal expansion coefficient matching with the metal heat sink. Therefore, without changing the thickness of the composite structure 60, the CTE0 of the composite structure 60 can be controlled by adjusting the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62. For example, the thickness ratio of the first metal layer 62 can be increased to increase the CTE0. Furthermore, to maintain the thermal conductivity of the composite structure 60, diamond particles 61a of an appropriate particle size can be selected based on the adjusted thickness of the diamond alloy layer 61.

[0178] Figure 9 is a top view of the composite structure 60 provided in an embodiment of the present application. As shown in Figure 9, the length of the composite structure 60 can be 10 mm and the width can be 6 mm. Figure 10 is a cross-sectional view of the composite structure 60 shown in Figure 9 taken along the AA direction. As shown in Figure 10, the thickness of the composite structure 60 can be 1 mm. The diamond particles 61a can be evenly distributed in the diamond alloy layer 61 to form a single-layer structure. For example, in the composite structure 60 shown in Figures 9 and 10, the thickness of the diamond alloy layer 61 can be 600 μm, and the thickness of the first metal layer 62 can be 400 μm. The particle size d1 of the diamond particles 61a in the diamond alloy layer 61 can satisfy: 300 μm<d1≤600 μm.

[0179] Figure 11 is a second top view of the composite structure 60 provided in an embodiment of the present application. As shown in Figure 11, the length of the composite structure 60 can be 20 mm and the width can be 10 mm. Figure 12 is a cross-sectional view of the composite structure 60 shown in Figure 11 taken along the BB direction. As shown in Figure 12, the thickness of the composite structure 60 can be 1 mm. The diamond particles 61a can be evenly distributed in the diamond alloy layer 61 to form a single-layer structure. For example, in the composite structure 60 shown in Figures 11 and 12, the thickness of the diamond alloy layer 61 can be 500 μm, and the thickness of the first metal layer 62 can be 500 μm. The particle size d1 of the diamond particles 61a in the diamond alloy layer 61 can satisfy: 250 μm<d1≤500 μm.

[0180] Figure 13 is a top view three of the composite structure 60 provided in an embodiment of the present application. As shown in Figure 13, the length of the composite structure 60 can be 32 mm and the width can be 10 mm. Figure 14 is a cross-sectional view of the composite structure 60 shown in Figure 13 taken along the CC direction. As shown in Figure 14, the thickness of the composite structure 60 can be 1 mm. The diamond particles 61a can be evenly distributed in the diamond alloy layer 61 to form a single-layer structure. For example, in the composite structure 60 shown in Figures 13 and 14, the thickness of the diamond alloy layer 61 can be 400 μm, and the thickness of the first metal layer 62 can be 600 μm. The particle size d1 of the diamond particles 61a in the diamond alloy layer 61 can satisfy: 200 μm<d1≤400 μm.

[0181] In one possible implementation, the first metal layer 62 may include at least one of copper (Cu), aluminum (Al), and silver (Ag). The first metal layer 62 and the metal substrate 61c may be made of the same metal. For example, the metal substrate 61c may be Cu, and the first metal layer 62 may be a Cu layer. For example, the metal substrate 61c may be Al, and the first metal layer 62 may be an Al layer. For example, the metal substrate 61c may be Ag, and the first metal layer 62 may be an Ag layer.

[0182] The first metal layer 62 and the metal matrix 61c of the diamond alloy layer 61 are made of the same metal, which helps improve the interfacial compatibility between the first metal layer 62 and the diamond alloy layer 61, thereby increasing the tensile strength of the interface 612 between the first metal layer 62 and the diamond alloy layer 61. This can further reduce the risk of delamination within the composite structure 60. Furthermore, compared to other metals, the aforementioned types of metals have higher thermal conductivity. This helps improve the thermal conductivity of the first metal layer 62, and thus the thermal conductivity of the composite structure 60.

[0183] In one possible implementation, as shown in FIG15 , the first metal layer 62 may include a first surface 62a and a second surface 62b , wherein the first surface 62a is connected to the diamond alloy layer 61 , and the second surface 62b is away from the diamond alloy layer 61 and is provided with a groove 60a (not shown in the figure).

[0184] When the composite structure 60 is subjected to external force or high temperature, stress tends to be concentrated in certain local areas, resulting in stress concentration, which in turn causes the risk of warping of the composite structure 60 .

[0185] The grooves 60a provided on the second surface 62b can change the stress distribution of the composite structure 60, thereby reducing the degree of stress concentration and making the stress more evenly distributed in the composite structure 60. In this way, the risk of warping of the composite structure 60 can be reduced and the strength and stability of the composite structure 60 can be improved.

[0186] The embodiment of the present application does not limit the number and size of the grooves 60 a , and those skilled in the art can select a suitable number and size based on the processing conditions, working conditions, size, etc. of the composite structure 60 .

[0187] In one possible implementation, the second surface 62b may be provided with multiple grooves 60a. At least one groove 60a extends along a first direction on the second surface 62b, and at least one groove 60a extends along a second direction on the second surface 62b. The first direction and the second direction intersect. This can further reduce stress concentration in the composite structure 60, lower the risk of warping of the composite structure 60, and improve the strength and stability of the composite structure 60.

[0188] In one possible implementation, the width of the groove 60a may be 1 mm to 1.5 mm, and the depth of the groove 60a may be equal to the thickness of the first metal layer 62. Specifically, the width of the groove 60a may be 1 mm, 1.5 mm, or any value between 1 mm and 1.5 mm, for example, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc. These values ​​are not listed here.

[0189] When the size of the groove 60 a is within the above-mentioned appropriate range, the stress concentration of the composite structure 60 can be effectively reduced, the risk of warping of the composite structure 60 can be reduced, and the strength and stability of the composite structure 60 can be improved.

[0190] In some embodiments of the present application, the grooves 60a can divide the surface of the first metal layer 62 into multiple regions of substantially equal area. The number of grooves 60a can be one or more. When there are multiple grooves 60a, the multiple grooves 60a can extend in multiple directions, and any two of the multiple directions can intersect or be parallel. The embodiments of the present application do not impose specific restrictions on the number and distribution of the grooves 60a, as long as they can reduce the stress concentration of the composite structure 60.

[0191] Figure 16 is a schematic cross-sectional view of another composite structure 60 provided in an embodiment of the present application. As shown in Figure 16 , in one possible implementation, a groove 60a can penetrate the first metal layer 62 along the thickness direction of the first metal layer 62. The depth of the groove 60a is equal to the thickness of the first metal layer 62.

[0192] Figure 17 is a bottom view of the composite structure 60 shown in Figure 16 . As shown in Figure 17 , the groove 60a divides the first metal layer 62 into two regions of equal area. This helps evenly distribute stress within the composite structure 60, thereby reducing stress concentration within the composite structure 60. This, in turn, reduces the risk of warping in the composite structure 60 and enhances its strength and stability.

[0193] Figure 18 is a second bottom view of a composite structure 60 provided in an embodiment of the present application. As shown in Figure 18 , in one possible implementation, two grooves 60a extending perpendicularly to each other can penetrate the first metal layer 62 along its thickness, dividing the first metal layer 62 into four regions of equal area. This facilitates uniform stress distribution within the composite structure 60, thereby reducing stress concentration within the composite structure 60. This, in turn, reduces the risk of warping of the composite structure 60 and enhances its strength and stability.

[0194] Figure 19 is a third bottom view of a composite structure 60 provided in an embodiment of the present application. As shown in Figure 19 , in one possible implementation, two intersecting grooves 60a can penetrate the first metal layer 62 along its thickness, dividing the first metal layer 62 into four regions of equal area. This facilitates uniform stress distribution within the composite structure 60, thereby reducing stress concentration within the composite structure 60. This, in turn, reduces the risk of warping of the composite structure 60 and enhances its strength and stability.

[0195] FIG20 is a bottom view 4 of another composite structure 60 provided in an embodiment of the present application. As shown in FIG20 , in one possible implementation, the composite structure 60 may be provided with a plurality of grooves 60a that are recessed from the surface of the first metal layer 62 away from the diamond alloy layer 61, and the extension directions of at least two of the plurality of grooves 60a intersect. The plurality of grooves 60a may penetrate the first metal layer 62 along the thickness direction of the first metal layer 62 and divide the first metal layer 62 into a plurality of regions of equal area. In this way, when the size of the composite structure 60 is large, the plurality of grooves 60a can disperse the stress more evenly within the composite structure 60, thereby reducing the stress concentration of the composite structure 60. This reduces the risk of warping of the composite structure 60 and improves the strength and stability of the composite structure 60.

[0196] The embodiment of the present application further provides a method for preparing a composite structure 60, which is used to prepare any of the above composite structures 60. The method may specifically include the following steps S10 to S20.

[0197] S10, preparing a diamond alloy layer 61.

[0198] S20 , forming a first metal layer 62 on one side of the diamond alloy layer 61 to obtain a composite structure 60 .

[0199] The diamond alloy layer 61 may include two surfaces facing each other in the thickness direction, and the first metal layer 62 may be provided on one of the two surfaces, thereby obtaining a composite structure 60 .

[0200] The first metal layer 62 can be formed on one side of the diamond alloy layer 61 in a variety of ways, as long as the first metal layer 62 and the diamond alloy layer 61 are integrally formed. This is not a limitation of the present invention. For example, the first metal layer 62 can be formed on one side of the diamond alloy layer 61 by one or more methods including a single infiltration process, hot pressing, welding, and electroplating.

[0201] In a possible implementation, S10 may specifically include the following steps S11 to S12.

[0202] S11, titanium or chromium is plated on the surface of the diamond particles 61a.

[0203] S12 , plating metal on the surface of the titanium-plated or chromium-plated diamond particles 61 a to obtain a diamond alloy layer 61 .

[0204] For example, titanium or chromium can be plated on the surface of the diamond particles 61a by physical vapor deposition. For example, metal can be plated on the surface of the diamond particles 61a after titanium or chromium plating by electroplating or chemical plating.

[0205] In the above implementation, after the surface of the diamond particles 61 a is plated with titanium or chromium, the titanium layer or the chromium layer reacts with the diamond particles 61 a to form a titanium carbide layer or a chromium carbide layer.

[0206] On the one hand, the titanium carbide layer or the chromium carbide layer has a strong bonding force with the diamond particles 61a and the metal, which can reduce the risk of delamination at the interface between the diamond particles 61a and the metal matrix 61c and improve the stability of the internal structure of the diamond alloy layer 61.

[0207] On the other hand, the titanium carbide layer or the chromium carbide layer has a greater bonding force with the metal, which is conducive to the smooth formation of the metal base 61c coating on the surface of the diamond particles 61a. In this way, the thickness of the metal base 61c coating in step S12 can be flexibly controlled, and the particle spacing of the diamond particles 61a can be controlled by the metal base 61c coating. The diamond particles 61a have a suitable particle spacing. On the one hand, the diamond particles 61a can be evenly distributed inside the diamond alloy layer 61, reducing the risk of the diamond particles 61a contacting each other and breaking when squeezed. On the other hand, the volume ratio of the diamond particles 61a in the diamond alloy layer 61 can be controlled within a suitable range, thereby controlling the thermal conductivity and CTE2 of the diamond alloy layer 61 within a suitable range. In this way, not only can the heat dissipation efficiency of the composite structure 60 be improved, the junction temperature of the semiconductor device 10 can be effectively reduced, but also the stability of the packaging structure of the semiconductor device 10 can be improved.

[0208] In this way, during mass production, the particle spacing of the diamond particles 61a can be controlled by adjusting the thickness of the metal base 61c coating in step S12, and the volume ratio of the diamond particles 61a in the diamond alloy layer 61 of each batch of composite structures 60 can be strictly controlled, thereby strictly controlling the thermal conductivity of the diamond alloy layer 61 and improving the specification consistency of each batch of composite structures 60.

[0209] In one possible implementation, the first metal layer 62 may be formed on one side of the diamond alloy layer 61 through a single infiltration process. Specifically, molten metal may be brought into contact with one surface of the diamond alloy layer 61 to form the first metal layer 62 upon solidification.

[0210] During a single infiltration process, the molten metal can penetrate into the small pores or cracks on the surface of the diamond alloy layer 61, diffuse, and solidify within the surface layer of the diamond alloy layer 61. This creates a high interfacial bonding strength between the diamond alloy layer 61 and the first metal layer 62, thereby increasing the anti-delamination strength of the interface between the diamond alloy layer 61 and the first metal layer 62 and thereby improving the structural stability of the composite structure 60. Consequently, when subsequently applied to the packaging structure of the semiconductor device 10, the structural stability of each interface within the packaging structure can be significantly improved, reducing the risk of delamination within the packaging structure.

[0211] In one possible implementation, after forming the first metal layer 62 on one side of the diamond alloy layer 61, the first metal layer 62 may be thickened or thinned. In this way, the ratio of the thickness of the diamond alloy layer 61 to the thickness of the first metal layer 62 in the composite structure 60 can be flexibly controlled.

[0212] The present embodiment does not impose any specific restrictions on the method of thickening or thinning. For example, the first metal layer 62 can be thickened by one or more methods such as hot pressing, electroplating, and welding. For example, the first metal layer 62 can be thinned by one or more methods such as milling and grinding.

[0213] In a possible implementation, the first metal layer 62 may be further machined or laser processed to provide a groove 60 a on the second surface 62 b of the first metal layer 62 .

[0214] The embodiment of the present application does not limit the number and size of the grooves 60a. Those skilled in the art can select an appropriate number and size based on the processing conditions, working conditions, and size of the composite structure 60. The specific number and size can be selected with reference to the implementation method of the composite structure 60 described above, and will not be described in detail here.

[0215] In a possible implementation, a second metal layer 63 may be formed on a surface of the diamond alloy layer 61 away from the first metal layer 62 .

[0216] The second metal layer 63 can be formed on the surface of the diamond alloy layer 61 away from the first metal layer 62 by various methods, which are not limited in this embodiment of the present application. As an example, the second metal layer 63 can be formed on the surface of the diamond alloy layer 61 away from the first metal layer 62 by one or more methods including a single infiltration process, hot pressing, welding, and electroplating.

[0217] It should be noted that the composite structure 60 provided in the embodiment of the present application can also be prepared by other methods. The above methods are only some examples of the preparation methods of the composite structure 60 provided in the embodiment of the present application and do not constitute a limitation on the composite structure 60 provided in the embodiment of the present application.

[0218] The composite structure 60 and the packaging structure of the semiconductor device 10 including the composite structure 60 are introduced below through specific embodiments, and the stability of the packaging structure is tested.

[0219] Example 1

[0220] In Example 1, the composite structure 60 and the packaging structure of the semiconductor device 10 are prepared according to the following steps.

[0221] Step 11: Prepare a composite structure. Specifically, hot press the diamond alloy layer 61 (diamond-copper alloy layer) and the first metal layer 62 (copper layer) to form a composite structure 60. The volume fraction of diamond particles 61a in the diamond alloy layer 61 is 60%, the coefficient of thermal expansion (CTE2) of the diamond alloy layer 61 is 5 ppm / K, and the thickness of the diamond alloy layer 61 is 0.5 mm. The coefficient of thermal expansion (CTE1) of the first metal layer 62 is 5 ppm / K, and the thickness is 0.5 mm. The length × width × thickness of the composite structure 60 is 20 mm × 10 mm × 1 mm.

[0222] Step 12: Prepare a package structure of the semiconductor device 10. The package structure of the semiconductor device 10 can be seen in FIG5 .

[0223] For example, during specific operations, the diamond alloy layer 61 can be connected to the semiconductor device 10 (GaN chip) using an adhesive 20 (sintered silver). The first metal layer 62 can be soldered to a metal heat sink 51 (copper heat sink) on the surface of the package substrate 50 connected to the PCB 80 using solder 40 (solder), thereby obtaining the package structure of the semiconductor device 10. During specific operations, the soldering process can be used.

[0224] Comparative Example 1

[0225] In Comparative Example 1, a diamond copper alloy flange and a packaging structure of a semiconductor device 10 were prepared according to the following steps.

[0226] Step 21: Provide a diamond-copper alloy flange. Specifically, a diamond-copper alloy flange is used in which the diamond particles 61a account for 60% of the volume, the coefficient of thermal expansion (CTE) of the diamond-copper alloy flange is 5 ppm / K, and the thickness of the diamond-copper alloy flange is 1 mm. The length × width × thickness of the diamond-copper alloy flange is 20 mm × 10 mm × 1 mm.

[0227] Step 22: Prepare the packaging structure of the semiconductor device 10. The packaging structure of the semiconductor device 10 can refer to FIG. 5 , except that the composite structure 60 is replaced by a diamond copper alloy flange.

[0228] For example, during specific operations, the diamond-copper alloy flange can be connected to the semiconductor device 10 (GaN chip) using adhesive 20 (sintered silver). The diamond-copper alloy flange can be soldered to a metal heat sink 51 (copper heat sink) on the surface of the package substrate 50 connected to the PCB 80 using solder 40 (tin), thereby obtaining the package structure of the semiconductor device 10. During specific operations, the soldering process can be used.

[0229] Example 2

[0230] In Example 2, the composite structure 60 and the packaging structure of the semiconductor device 10 are prepared according to the following steps.

[0231] Step 31: Prepare composite structure 60. Specifically, a diamond alloy layer 61 (diamond-copper alloy layer) and a first metal layer 62 (copper layer) are hot-pressed to form composite structure 60. The volume fraction of diamond particles in diamond alloy layer 61 is 60%, the coefficient of thermal expansion (CTE2) of diamond alloy layer 61 is 5 ppm / K, and the thickness of diamond alloy layer 61 is 0.6 mm. The coefficient of thermal expansion (CTE1) of first metal layer 62 is 5 ppm / K, and the thickness is 0.4 mm. The length × width × thickness of composite structure 60 is 5 mm × 4 mm × 1 mm.

[0232] Step 32: Prepare a package structure of the semiconductor device 10. The package structure of the semiconductor device 10 can be seen in FIG5 .

[0233] For example, during specific operations, the diamond alloy layer 61 can be connected to the semiconductor device 10 (GaN chip) using an adhesive 20 (sintered silver). The first metal layer 62 can be soldered to a metal heat sink 51 (copper heat sink) on the surface of the package substrate 50 connected to the PCB 80 using solder 40 (solder), thereby obtaining the package structure of the semiconductor device 10. During specific operations, the soldering process can be used.

[0234] Example 3

[0235] In Example 3, the composite structure 60 and the packaging structure of the semiconductor device 10 are prepared according to the following steps.

[0236] Step 41: Prepare composite structure 60. Specifically, a diamond alloy layer 61 (diamond-copper alloy layer) and a first metal layer 62 (copper layer) are hot-pressed to form composite structure 60. The volume fraction of diamond particles in diamond alloy layer 61 is 60%, the coefficient of thermal expansion (CTE2) of diamond alloy layer 61 is 5 ppm / K, and the thickness of diamond alloy layer 61 is 0.4 mm. The coefficient of thermal expansion (CTE1) of first metal layer 62 is 5 ppm / K, and the thickness is 0.6 mm. The length × width × thickness of composite structure 60 is 40 mm × 10 mm × 1 mm.

[0237] Step 42: Prepare a package structure of the semiconductor device 10. The package structure of the semiconductor device 10 can be seen in FIG5 .

[0238] For example, during specific operations, the diamond alloy layer 61 can be connected to the semiconductor device 10 (GaN chip) via an adhesive 20 (sintered silver). The first metal layer 62 can be soldered to a metal heat sink 51 (copper heat sink) on the surface of the package substrate 50 connected to the PCB 80 using solder (tin), thereby obtaining the package structure of the semiconductor device 10. During specific operations, the soldering process can be used.

[0239] Performance tests were performed on the packaging structures of the semiconductor devices 10 prepared in the above-mentioned embodiments 1-3 and comparative example 1.

[0240] Specifically, a temperature cycling test was performed on the package structures of the semiconductor devices 10 prepared in Examples 1-3 and Comparative Example 1. The test temperature ranged from -45°C to 125°C, with a high-temperature hold time of 30 minutes at a cooling rate of 10°C / min, and a low-temperature hold time of 30 minutes at a heating rate of 10°C / min. The delamination of the solder layer between the composite structure 60 and the interface between the diamond-copper alloy flange and the metal heat sink 51 was examined using an ultrasonic scanning microscope after every 100 cycles.

[0241] Figure 21 shows an ultrasonic scanning microscopy image of the package structure prepared in Example 1. Specifically, it shows an ultrasonic scanning microscopy image of the solder layer at the interface between the composite structure 60 and the metal heat sink 51 after the package structure of the semiconductor device 10 prepared in Example 1 was subjected to 800 temperature cycles. As shown in Figure 21 , after 800 temperature cycles, the solder layer at the interface between the composite structure 60 and the metal heat sink 51 was intact, and no delamination was observed between the composite structure 60 and the metal heat sink 51.

[0242] Figure 22 shows an ultrasonic scanning microscopy image of the package structure prepared in Comparative Example 1. Specifically, it shows an ultrasonic scanning microscopy image of the solder layer between the diamond-copper alloy flange and the metal heat sink 51 after the package structure of the semiconductor device 10 prepared in Comparative Example 1 was subjected to 300 temperature cycles. As shown in Figure 22, after 300 temperature cycles, the solder layer between the diamond-copper alloy flange and the metal heat sink 51 has been completely destroyed, and delamination has occurred between the interfaces.

[0243] Comparing FIG21 and FIG22 , it can be seen that, given the same dimensions, the composite structure 60 of the embodiment of the present application can significantly reduce the risk of delamination between the composite structure 60 and the metal heat sink 51 , thereby improving the stability of the packaging structure of the semiconductor device 10 .

[0244] Furthermore, referring to FIG23 , after the package structure of the semiconductor device 10 in Example 2 was subjected to 800 temperature cycles, the solder layer at the interface between the composite structure 60 and the metal heat sink 51 was not damaged, and no delamination was observed between the composite structure 60 and the metal heat sink 51. Similarly, referring to FIG24 , after the package structure of the semiconductor device 10 in Example 3 was subjected to 800 temperature cycles, the solder layer at the interface between the composite structure 60 and the metal heat sink 51 was not damaged, and no delamination was observed between the composite structure 60 and the metal heat sink 51.

[0245] Based on the test results of Examples 1 to 3, it can be found that the composite structure 60 of the embodiment of the present application can be applied to the packaging structure of semiconductor devices 10 of different sizes, effectively reducing the risk of delamination between the interface of the composite structure 60 and the metal heat sink 51, and improving the stability of the packaging structure of the semiconductor device 10.

[0246] The above-described embodiments of the present application do not constitute a limitation on the scope of protection of the present invention.

[0247] In some embodiments, multiple embodiments of the present application may be combined and the combined embodiments may be implemented. Optionally, some operations in the processes of the various method embodiments may be optionally combined, and / or the order of some operations may be optionally changed. Furthermore, the execution order between the steps of each process is merely exemplary and does not constitute a limitation on the execution order between the steps. Other execution orders may also be used between the steps. This is not intended to indicate that the execution order is the only order in which these operations may be performed.

[0248] Those skilled in the art will appreciate various ways to reorder the operations described in the embodiments of the present application. In addition, it should be noted that the process details involved in a certain embodiment of the present application are also applicable to other embodiments in a similar manner, or different embodiments can be used in combination.

[0249] Furthermore, some steps in the method embodiments may be equivalently replaced with other possible steps. Alternatively, some steps in the method embodiments may be optional and may be deleted in certain usage scenarios. Alternatively, other possible steps may be added to the method embodiments.

[0250] Furthermore, each method embodiment can be implemented separately or in combination. The above content is only a specific implementation method of this application, but the scope of protection of this application is not limited thereto. Any changes or replacements within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A composite structure for connecting a semiconductor device and a packaging substrate, characterized in that, Comprising: A diamond alloy layer and a first metal layer, the diamond alloy layer and the first metal layer being stacked, and the diamond alloy layer and the first metal layer being an integral structure; Wherein, the diamond alloy layer is used to connect with the semiconductor device; the first metal layer is used to connect with the packaging substrate.

2. The composite structure according to claim 1, wherein The diamond alloy layer includes a metal matrix and diamond particles located within the metal matrix, and the metal matrix and the first metal layer are an integral structure.

3. The composite structure according to claim 1 or 2, characterized in that The thermal conductivity of the composite structure is 500 W / mK to 900 W / mK.

4. The composite structure according to any one of claims 1-3, characterized in that, The thermal conductivity of the diamond alloy layer is 600 W / mK to 1000 W / mK.

5. The composite structure according to any one of claims 1-4, characterized in that, The coefficient of thermal expansion CTE1 of the first metal layer is 17 ppm / K to 25 ppm / K.

6. The composite structure according to any one of claims 1-5, characterized in that, The coefficient of thermal expansion CTE2 of the diamond alloy layer is 5 ppm / K to 10 ppm / K.

7. The composite structure according to any one of claims 1-6, characterized in that, The coefficient of thermal expansion CTE0 of the composite structure is 8.5 ppm / K to 11.5 ppm / K.

8. The composite structure according to any one of claims 1-7, characterized in that, The ratio of the thickness of the diamond alloy layer to the thickness of the first metal layer is 1:9 to 9:

1.

9. The composite structure according to claim 2, wherein The thickness d of the diamond alloy layer and the particle size d1 of the diamond particles satisfy: d1 ≤ d < 2d1.

10. The composite structure according to claim 9, characterized in that, The volume ratio of the diamond particles in the diamond alloy layer is 30% to 80%.

11. The composite structure according to claim 9 or 10, characterized in that, The surface of the diamond particles is further coated with a carbide layer, and the carbide layer includes at least one of titanium carbide and chromium carbide.

12. The composite structure according to claim 2, wherein The metal matrix includes at least one of copper, aluminum, and silver.

13. The composite structure according to claim 12, characterized in that, The first metal layer includes at least one of copper, aluminum, and silver, and the first metal layer and the metal matrix are the same metal.

14. The composite structure according to any one of claims 1-13, characterized in that, The first metal layer includes a first surface and a second surface, the first surface is connected to the diamond alloy layer, and the second surface is away from the diamond alloy layer and is provided with a groove.

15. The composite structure according to claim 14, wherein The width of the groove is 1 mm to 1.5 mm, and the depth of the groove is equal to the thickness of the first metal layer.

16. The composite structure according to claim 14 or 15, characterized in that, The second surface is provided with a plurality of grooves, at least one groove extends along a first direction on the second surface, and at least one groove extends along a second direction on the second surface, and the first direction intersects with the second direction.

17. The composite structure according to any one of claims 1-16, characterized in that, A second metal layer is further provided on the surface of the diamond alloy layer away from the first metal layer, and the thickness of the second metal layer is less than or equal to 100 μm.

18. A method for preparing a composite structure, characterized in that, Comprising: Preparing a diamond alloy layer; Forming a first metal layer on one side of the diamond alloy layer to obtain a composite structure; The composite structure includes a diamond alloy layer and a first metal layer, the diamond alloy layer and the first metal layer are stacked, and the diamond alloy layer and the first metal layer are an integral structure; wherein, the diamond alloy layer is used to connect with the semiconductor device; the first metal layer is used to connect with the packaging substrate.

19. An encapsulation structure, characterized in that, Comprising: A semiconductor device, a packaging substrate, and the composite structure according to any one of claims 1-17; Wherein, the diamond alloy layer in the composite structure is used to connect with the semiconductor device; the first metal layer in the composite structure is used to connect with the packaging substrate.

20. The encapsulation structure according to claim 19, wherein The composite structure is connected to the semiconductor device through an adhesive; The adhesive includes at least one of silver nanoparticles and gold tin.

21. The encapsulation structure according to claim 19 or 20, characterized in that, The composite structure is integrally formed with the encapsulation substrate.

22. The encapsulation structure according to any one of claims 19-21, characterized in that, The encapsulation substrate includes a metal heat sink and heat dissipation teeth, and the metal heat sink and the heat dissipation teeth are stacked; a groove is provided on a surface of the metal heat sink away from the heat dissipation teeth, and at least a part of the composite structure is accommodated in the groove.

23. An electronic device, characterized in that, The electronic device includes the encapsulation structure according to any one of claims 19-22.

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