Packaging structure and packaging method of GaN HEMT

Abstract

The invention provides a GaN HEMT packaging structure and packaging method, the structure comprises a GaN HEMT chip and a frame, the back surface of the chip is provided with a heat dissipation metal layer, a base island of the frame is provided with a groove, and the heat dissipation metal layer is embedded in the groove and penetrates out of the base island to contact with the external environment. The packaging method comprises the following steps: preparing a heat dissipation metal layer on the back surface of the chip and embedding the chip into the base island of the frame, so that the heat dissipation metal layer is embedded into the groove and penetrates out of the base island to be in contact with the external environment. According to the invention, the heat dissipation metal layer is embedded into the base island of the frame and penetrates out of the base island to be in contact with the external environment, so that the heat transfer path can be shortened, the heat resistance can be reduced, the heat dissipation efficiency and reliability can be improved, and meanwhile, the use of a connecting material between the back surface of the chip and the frame can be avoided; the GaN HEMT has the advantages of small thermal resistance, good heat dissipation performance, high reliability and the like, and is of great significance in giving full play to the excellent high-frequency performance of the GaN HEMT and promoting the wide application of the GaN HEMT.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor device packaging, and relates to a packaging structure and a packaging method of a GaN HEMT. Background Art

[0002] GaN HEMT (gallium nitride high electron mobility transistor) has the characteristics of high voltage resistance, low on-resistance, fast switching speed, etc. The use of surface mount packaging such as QFN (quad flat no leads) / DFN (double flat no leads) and other packaging types can effectively reduce the package stray inductance and package volume, and give full play to the excellent high-frequency performance of GaN HEMT. However, since GaNHEMT is a device with a lateral structure using heteroepitaxial growth, the two-dimensional electron gas channel on the surface of GaN HEMT will generate a lot of heat when it is working, which causes the temperature to rise and seriously damages the performance of the device. Therefore, there are high requirements for the heat dissipation performance of the package.

[0003] In order to improve the heat dissipation performance of GaN HEMT packaging, there are two main methods currently used: one method is to increase the heat dissipation efficiency of the upper surface of the chip, such as covering the surface of the chip with high thermal conductivity materials such as diamond, using copper sheets and copper clips with a large heat dissipation area to replace wire bonding, etc. The disadvantages are that it increases the difficulty of chip manufacturing and the complexity and cost of packaging, and cannot solve the problem of poor heat dissipation of heat through the lower surface of the chip. The other method is to improve the heat dissipation efficiency of the chip downward. Since the conductive channel is located on the surface of the chip, the heat needs to pass through the GaN epitaxial layer, substrate layer, connection material layer and frame of the chip to transfer downward. Although the heat dissipation efficiency can be improved by increasing the thermal conductivity of the epitaxial and substrate materials, thinning the thickness of the substrate layer, and completely removing the substrate layer, the disadvantage is that it is easily limited by the cost of the epitaxial and substrate, the substrate thinning technology and the thinning cost. In particular, the thickness of the substrate after thinning is usually still above 100um, which is not conducive to improving the heat dissipation efficiency. In addition, the thermal conductivity of the connection material layer is also limited by material properties and costs. At the same time, the quality of the connection interface is difficult to control, which may also cause reliability problems. In addition, in the existing packaging method, the GaN HEMT chip is placed on the surface of the packaging frame, and the bottom of the chip is connected to the frame through connecting materials such as thermal conductive glue. The heat generated by the chip when it is working is transferred outward through the packaging body, and the transfer channel passes through the gallium nitride epitaxial layer, substrate layer, connecting material layer and frame in sequence. However, due to the presence of multiple layers of materials and interfaces in the transfer path, there are defects such as large thermal resistance and low heat dissipation efficiency. In addition, in the existing packaging structure, the substrate is embedded in the frame, and although the heat dissipation path can be shortened, its heat transfer path still needs to pass through multiple layers of materials and interfaces, and there are still defects such as poor heat dissipation effect, and thermal conductive glue is also provided at the connection between the substrate and the frame, which also has defects such as poor reliability. Therefore, obtaining a packaging structure and packaging method with low thermal resistance, good heat dissipation and high reliability is of great significance for giving full play to the excellent high-frequency performance of GaN HEMT and promoting its widespread use. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a packaging structure and a packaging method for a GaN HEMT with low thermal resistance, good heat dissipation and high reliability.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A GaN HEMT packaging structure comprises a GaN HEMT chip and a frame, wherein a heat dissipation metal layer is provided on the back of the GaN HEMT chip, the frame comprises a base island, a groove is provided in the base island, the heat dissipation metal layer is embedded in the groove and passes through the base island to contact the external environment.

[0007] As a further improvement of the above technical solution: the shape of the heat dissipation metal layer matches the notch shape of the groove.

[0008] As a further improvement of the above technical solution: the thickness of the heat dissipation metal layer is the same as the thickness of the groove.

[0009] As a further improvement of the above technical solution: the heat dissipation metal layer is in a boss shape on the back side of the HEMT chip, and the groove is in a step shape. When the heat dissipation metal layer is embedded in the groove, the GaN HEMT chip is partially embedded in the groove.

[0010] As a further improvement of the above technical solution: the heat dissipation metal layer is located below the active area of ​​the GaN HEMT chip.

[0011] As a further improvement of the above technical solution: the shape and area of ​​the heat dissipation metal layer match the active area of ​​the GaN HEMT chip.

[0012] As a further improvement of the above technical solution: the thickness of the heat dissipation metal layer is 1 μm to 600 μm; the material of the heat dissipation metal layer is at least one of Ti, Ni, Ag and Au.

[0013] As a further improvement of the above technical solution: the GaN HEMT chip includes a substrate, an epitaxial layer is provided on the substrate, the epitaxial layer includes a GaN layer, an AlGaN layer and a two-dimensional electron gas channel formed between the GaN layer and the AlGaN layer; the GaN layer is located on the substrate, a source electrode and a drain electrode are provided on an extension portion of the AlGaN layer, the source electrode and the drain electrode penetrate the AlGaN layer and are connected to the GaN layer; a gate electrode is also provided on the AlGaN layer; the material of the substrate is one of silicon, silicon carbide, sapphire, diamond and aluminum nitride.

[0014] As a further improvement of the above technical solution: the frame is a DFN packaging frame; the thickness of the frame is ≤0.6 mm; the material of the frame is Cu; the frame also includes pins located on both sides of the base island.

[0015] As a general technical concept, the present invention also provides a packaging method for a GaN HEMT, comprising the following steps:

[0016] S1. Provide GaN HEMT chips;

[0017] S2, thinning the substrate of the GaN HEMT chip;

[0018] S3, preparing a heat dissipation metal layer on the surface of the substrate to obtain a GaN HEMT chip with a heat dissipation metal layer prepared on the back side;

[0019] S4, etching the base island of the frame according to the shape and thickness of the heat dissipation metal layer, and forming a groove in the base island that matches the heat dissipation metal layer;

[0020] S5. Place the GaN HEMT chip into the groove of the base island, embed the heat dissipation metal layer into the groove and pass through the base island to contact the external environment, and complete the packaging of the GaN HEMT.

[0021] As a further improvement of the above technical solution: in step S2, the substrate of the GaN HEMT chip is thinned by grinding wheel grinding, chemical mechanical polishing (CMP) or polishing; the thickness of the thinned substrate is 50 μm to 300 μm.

[0022] As a further improvement of the above technical solution: in step S3, a heat dissipation metal layer is prepared on the surface of the substrate by metal sputtering, evaporation or electroplating; after the preparation of the heat dissipation metal layer, the following treatment is also included: etching the heat dissipation metal layer to remove the metal at the edge of the substrate, and forming a boss relative to the edge below the active area of ​​the GaN HEMT chip; the thickness of the heat dissipation metal layer is 1μm to 600μm; the material of the heat dissipation metal layer is at least one of Ti, Ni, Ag, and Au.

[0023] As a further improvement of the above technical solution: in step S4, the notch shape of the groove matches the shape of the heat dissipation metal layer; the thickness of the heat dissipation metal layer is the same as the thickness of the groove.

[0024] As a further improvement of the above technical solution: in step S5, the groove is stepped, and when the heat dissipation metal layer is embedded in the groove, the substrate part of the GaN HEMT chip is embedded in the groove.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] (1) In view of the shortcomings of the packaging structure, such as large thermal resistance, low heat dissipation efficiency, and poor reliability, the present invention creatively provides a packaging structure of GaN HEMT. By providing a heat dissipation metal layer on the back of the GaN HEMT chip, and embedding it into the base island of the frame and passing through the base island to contact the external environment, on the one hand, the heat dissipation metal layer can be used to protect the chip, which is beneficial to improving the reliability of the chip. On the other hand, the heat dissipation metal layer can be used to directly transfer the heat of the active area to the outside, with low thermal resistance and high heat dissipation efficiency, which can significantly enhance the heat dissipation performance. More importantly, the heat dissipation metal layer is embedded in the base island of the frame and passes through the base island, so that the chip can be directly mounted on the frame without setting a connecting material at the bottom of the chip, so that the support and protection function of the frame can be achieved, and the reliability of the chip can be enhanced while shortening the heat transfer distance. The packaging structure of GaN HEMT of the present invention has the advantages of low thermal resistance, good heat dissipation, high reliability, etc., and is of great significance for giving full play to the excellent high-frequency performance of GaN HEMT and promoting its widespread use.

[0027] (2) In the present invention, the heat dissipation metal layer is in the shape of a boss, and the groove is in the shape of a step. When the heat dissipation metal layer is embedded in the groove, the GaN HEMT chip is partially embedded in the groove. At this time, a semi-embedded connection structure is formed between the chip and the frame. Not only can the support and protection of the frame be used to avoid the use of connection materials between the chip and the frame, but also the reliability of the packaging structure can be enhanced while the heat dissipation metal layer is used to dissipate heat to the outside, which is beneficial to improving the service life of the chip.

[0028] (3) The packaging method of the GaN HEMT of the present invention has the advantages of simple process, convenient operation, low cost, etc. The heat dissipation area on the back of the GaN HEMT chip can be increased by patterns of different shapes and sizes, and can replace the high-cost solution of directly making a similar structure on the back of the chip, which is convenient for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0030] Figure 1 Schematic diagram of the packaging structure of the GaN HEMT in Example 1 of the present invention.

[0031] Figure 2 This is a top view of the frame in Example 1 of the present invention.

[0032] Figure 3 It is a schematic diagram of the cross-sectional structure of the GaN HEMT chip in Example 1 of the present invention.

[0033] Legend:

[0034] 1. Pin; 2. Base island; 3. Source; 4. Drain; 5. Gate; 6. AlGaN layer; 7. GaN layer; 8. Two-dimensional electron gas channel; 9. Substrate; 10. Heat dissipation metal layer; 11. Groove. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0036] Embodiment 1:

[0037] like Figures 1 to 3 As shown, the packaging structure of the GaN HEMT of this embodiment includes a GaN HEMT chip and a frame. The back side of the GaN HEMT chip is provided with a heat dissipation metal layer 10. The frame includes a base island 2. A groove 11 is provided in the base island 2. The heat dissipation metal layer 10 is embedded in the groove 11 and passes through the base island 2 to contact the external environment.

[0038] In this embodiment, the shape of the heat dissipation metal layer 10 matches the notch shape of the groove 11. Specifically, the shape of the heat dissipation metal layer 10 is the same as the notch shape of the groove 11. In other embodiments, the thickness of the heat dissipation metal layer 10 is the same as the thickness of the groove 11.

[0039] like Figure 1-Figure 3 As shown, in this embodiment, the heat dissipation metal layer 10 is in a boss shape on the back side of the HEMT chip, and the groove 11 is in a step shape. When the heat dissipation metal layer 10 is embedded in the groove 11, the GaN HEMT chip is partially embedded in the groove 11. Specifically, a portion of the substrate with a thickness of 100 μm is embedded in the guide groove 11.

[0040] like Figure 1 As shown, in this embodiment, the heat dissipation metal layer 10 is located below the active area of ​​the GaN HEMT chip, and the shape and area of ​​the heat dissipation metal layer 10 match the active area of ​​the GaN HEMT chip. For example, the shape and area of ​​the heat dissipation metal layer 10 are the same as the active area of ​​the GaN HEMT chip.

[0041] In this embodiment, the thickness of the heat dissipation metal layer 10 is 100 μm. In other embodiments, the thickness of the heat dissipation metal layer 10 is 1 μm, 10 μm, 30 μm, 50 μm, 200 μm, 300 μm, or 600 μm.

[0042] In this embodiment, the material of the heat dissipation metal layer 10 is Ag. In other embodiments, the material of the heat dissipation metal layer 10 is one of Ni, Ti, and Au.

[0043] like Figure 3As shown, in this embodiment, the GaN HEMT chip is a conventional chip, including a substrate 9, on which an epitaxial layer is provided, the epitaxial layer including a GaN layer 7, an AlGaN layer 6 and a two-dimensional electron gas channel 8 formed between the GaN layer 7 and the AlGaN layer 6; the GaN layer 7 is located on the substrate 9, and a source electrode 3 and a drain electrode 4 are provided on an extension portion of the AlGaN layer 6, and the source electrode 3 and the drain electrode 4 penetrate the AlGaN layer 6 and are connected to the GaN layer 7; and a gate electrode 5 is also provided on the AlGaN layer 6.

[0044] In this embodiment, the material of the substrate 9 is sapphire. In other embodiments, the material of the substrate 9 is one of silicon, silicon carbide, diamond, and aluminum nitride.

[0045] In this embodiment, the heat dissipation metal layer 10 is on the back side of the substrate 9 .

[0046] In this embodiment, the frame is a DFN packaging frame, the thickness of the frame is 0.2 mm, the material of the frame is Cu, and the frame further includes pins 1 located on both sides of the base island 2 .

[0047] The packaging method of the GaN HEMT of this embodiment includes the following steps:

[0048] S1. Provide GaN HEMT chips.

[0049] In this embodiment, a method for preparing a GaN HEMT chip is provided, comprising the following steps:

[0050] The nucleation layer, buffer layer, channel layer, barrier layer, etc. of the epitaxial layer are deposited on the substrate in sequence by methods such as metal oxide vapor phase epitaxy (MOCVD). The core basic structure is the heterojunction formed by the barrier layer / channel layer, which is usually the AlGaN / GaN heterojunction. A two-dimensional electron gas with high electron concentration and high electron mobility is formed at the AlGaN / GaN interface. After the epitaxial deposition is completed, the gate, source, drain, field plate, passivation layer and other device structures of the GaN HEMT are formed on the gallium nitride epitaxy through processes such as lithography, etching, injection, and coating, completing the front process of the GaN HEMT.

[0051] S2. Thinning the substrate of the GaN HEMT chip. Specifically, after the front process of the GaN HEMT is completed, the thickness of the substrate is thinned by grinding wheel grinding and other methods. The initial substrate thickness is generally 350μm to 1000μm, and the thickness after thinning is 200μm. The substrate mainly plays a supporting role, and after thinning, the heat dissipation performance of the GaN HEMT can be enhanced.

[0052] S3. Prepare a heat dissipation metal layer on the surface of the substrate. Specifically, after the substrate is thinned, a layer of metal is formed on the back of the substrate by metal sputtering, electroplating and other methods. The metal type is, for example, Ti / Ni / Ag / Au, and the thickness is several microns to several hundred microns. In this embodiment, the metal is Ag, and the thickness of the heat dissipation metal layer is 100μm. Further, the metal near the edge of the back of the chip is removed by etching and other methods, so that the metal portion in the middle of the back forms a convex platform relative to the edge, and a GaN HEMT chip with a heat dissipation metal layer prepared on the back is obtained. In this embodiment, the back metal is mainly used to enhance heat dissipation and protect the chip. The area of ​​the metal removed from the edge corresponding to the front of the chip is located outside the active area. When the chip is working, heat is mainly generated in the active area, so it has little effect on heat dissipation.

[0053] S4. According to the shape and thickness of the heat dissipation metal layer, the base island of the frame is etched to form a groove in the base island that matches the heat dissipation metal layer. Specifically, a patterned base corresponding to the chip size is formed on the base island by etching and other methods, corresponding to the shape and size of the GaN HEMT and the back metal. In this embodiment, the heat dissipation metal layer is sputtered on the substrate to form a stepped boss, and the base island is hollowed out to form a stepped groove.

[0054] S5, place the GaN HEMT chip into the groove of the base island, so that the heat dissipation metal layer is embedded in the groove and passes through the base island to contact the external environment, and the substrate part of the GaN HEMT chip is embedded in the groove to complete the packaging of the GaN HEMT. In this step, the complete packaging process generally also includes wire bonding, plastic sealing, electroplating, cutting and other steps. In the subsequent packaging process, the side of the chip and the frame can be fixed and sealed by connecting materials or welding. Specifically, in step S5, the GaN HEMT is placed in the graphic base of the base island, the side position of the chip is connected and fixed to the frame using materials such as thermal conductive glue, the metal on the back of the chip is directly exposed for heat dissipation, and the frame position at the bottom of the chip is hollow, and no connecting materials such as thermal conductive glue are required, so the heat dissipation performance of the GaN HEMT can be increased.

[0055] Comparative Example 1

[0056] A GaN HEMT chip is basically the same as the first embodiment, except that: no groove is provided in the base island of the frame, and specifically, the GaN HEMT chip is directly packaged on the frame by providing an epoxy resin layer with a thickness of 20 μm between the back metal layer and the base island.

[0057] Ansys software was used to perform thermal simulation tests on the GaN HEMT chips prepared in Example 1 and Comparative Example 1, wherein the chip area was 4 mm×2 mm and the heating power was 30 W.

[0058] The test results show that in comparative example 1, the temperature of the front side of the chip is 69.75°C, while in example 1, the temperature of the front side of the chip is 61.72°C. By comparison, it can be seen that the temperature of the front side of the chip in example 1 is reduced by 11.5% compared with that in comparative example 1, which indicates that the heat dissipation performance can be significantly enhanced by providing a heat dissipation metal layer on the back side of the GaN HEMT chip, embedding it into the base island of the frame, and penetrating from the base island to contact the external environment.

[0059] In addition, for GaN HEMT chips, the connection material layer and interface quality are important factors affecting the reliability of packaging. Due to the different thermal expansion coefficients of different materials, there are usually defects such as voids and cracks in the connection interface. Under the influence of factors such as water vapor and thermal stress, failure phenomena such as popcorn and delamination occur, and the device suffers from electrical performance degradation such as leakage and short circuit, which leads to chip failure. For example, epoxy resin and other connection materials have poor electrical and thermal conductivity. In order to improve the electrical and thermal conductivity, silver particles are usually added to epoxy resin and other connection materials. These silver particles may migrate to the chip surface under the influence of high electric fields, which may also cause device failure. Completely different from them, in the present invention, the metal layer made on the back of the chip by sputtering, evaporation, electroplating, etc., on the one hand, the metal has good electrical and thermal conductivity, which is conducive to improving the heat dissipation of the chip. On the other hand, the interface quality reliability of the metal and the chip is high, and there are no defects such as voids, which can greatly improve the reliability of packaging.

[0060] In addition, the packaging structure of the GaN HEMT in the embodiment of the present invention has the characteristics of low thermal resistance and good heat dissipation, specifically: the back metal is used for direct heat dissipation, and there is no need to set the connection material at the bottom of the chip. Through the thermal simulation calculation of Ansys software, under the same conditions such as the chip and frame materials, compared with the 20um, 10W / m·K connection material layer at the bottom of the chip, the chip temperature in this embodiment can be reduced by more than 10% during operation. According to the thermal resistance calculation formula, R=ΔT / q, where ΔT is the temperature difference and q is the heat flux density, the chip in this embodiment has a corresponding thermal resistance reduction of more than 10%. In the thermal simulation model, the thickness and thermal conductivity of the connection material layer are changed. The thermal simulation results show that the thickness and thermal conductivity of the connection material have a greater impact on the chip temperature. If the connection material layer has voids, stratification, etc., resulting in a decrease in thermal conductivity, the chip temperature will be greatly increased during operation, which not only affects the reliability of the device, but also easily causes the chip to accumulate heat and break down.

[0061] It can be seen from the above results that, compared with the conventional packaging structure, the packaging structure of the GaN HEMT of the present invention provides a heat dissipation metal layer on the back of the GaN HEMT chip, and embeds it into the base island of the frame and passes through the base island to contact the external environment. On the one hand, the heat dissipation metal layer can be used to protect the chip, which is beneficial to improving the reliability of the chip. On the other hand, the heat dissipation metal layer can be used to directly transfer the heat of the active area to the outside, with low thermal resistance and high heat dissipation efficiency, which can significantly enhance the heat dissipation performance. More importantly, the heat dissipation metal layer is embedded in the base island of the frame and passes through the base island, and the chip can be directly installed on the frame without setting a connecting material at the bottom of the chip, so that the support and protection of the frame can be achieved, and the reliability of the chip can be enhanced while shortening the heat transfer distance. The packaging structure of the GaN HEMT of the present invention has the advantages of low thermal resistance, good heat dissipation, high reliability, etc., which is of great significance for giving full play to the excellent high-frequency performance of GaN HEMT and promoting its widespread use.

[0062] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A packaging structure of a GaN HEMT, characterized in that: The invention comprises a GaN HEMT chip and a frame, wherein a heat dissipation metal layer (10) is provided on the back of the GaN HEMT chip, and the frame comprises a base island (2), wherein a groove (11) is provided in the base island (2), and the heat dissipation metal layer (10) is embedded in the groove (11) and passes through the base island (2) to contact the external environment.

2. The packaging structure of GaN HEMT according to claim 1, characterized in that: The shape of the heat dissipation metal layer (10) matches the notch shape of the groove (11); the thickness of the heat dissipation metal layer (10) is the same as the thickness of the groove (11).

3. The packaging structure of GaN HEMT according to claim 2, characterized in that: The heat dissipation metal layer (10) is in the shape of a boss on the back side of the HEMT chip, and the groove (11) is in the shape of a step; when the heat dissipation metal layer (10) is embedded in the groove (11), the GaN HEMT chip is partially embedded in the groove (11).

4. The packaging structure of GaN HEMT according to claim 3, characterized in that: The heat dissipation metal layer (10) is located below the active area of ​​the GaN HEMT chip; the shape and area of ​​the heat dissipation metal layer (10) match the active area of ​​the GaN HEMT chip.

5. The packaging structure of GaN HEMT according to claim 4, characterized in that: The thickness of the heat dissipation metal layer (10) is 1 μm to 600 μm; the material of the heat dissipation metal layer (10) is at least one of Ti, Ni, Ag and Au.

6. The packaging structure of the GaN HEMT according to any one of claims 1 to 5, characterized in that: The GaN HEMT chip comprises a substrate (9), an epitaxial layer is provided on the substrate (9), the epitaxial layer comprises a GaN layer (7), an AlGaN layer (6), and a two-dimensional electron gas channel (8) formed between the GaN layer (7) and the AlGaN layer (6); the GaN layer (7) is located on the substrate (9), a source electrode (3) and a drain electrode (4) are provided on an extension portion of the AlGaN layer (6), the source electrode (3) and the drain electrode (4) penetrate the AlGaN layer (6) and are connected to the GaN layer (7); a gate electrode (5) is also provided on the AlGaN layer (6); the material of the substrate (9) is one of silicon, silicon carbide, sapphire, diamond, and aluminum nitride.

7. The packaging structure of the GaN HEMT according to any one of claims 1 to 5, characterized in that: The frame is a DFN packaging frame; the thickness of the frame is ≤0.6 mm; the material of the frame is Cu; the frame also includes pins (1) located on both sides of the base island (2).

8. A packaging method for a GaN HEMT, characterized in that: The following steps are involved: S1. Provide GaN HEMT chips; S2, thinning the substrate of the GaN HEMT chip; S3, preparing a heat dissipation metal layer on the surface of the substrate to obtain a GaN HEMT chip with a heat dissipation metal layer prepared on the back side; S4, etching the base island of the frame according to the shape and thickness of the heat dissipation metal layer, and forming a groove in the base island that matches the heat dissipation metal layer; S5. Place the GaN HEMT chip into the groove of the base island, embed the heat dissipation metal layer into the groove and pass through the base island to contact the external environment, and complete the packaging of the GaN HEMT.

9. The packaging method according to claim 8, characterized in that: In step S2, the substrate of the GaN HEMT chip is thinned by grinding wheel grinding, chemical mechanical grinding or polishing; the thickness of the substrate after thinning is 50 μm to 300 μm; In step S3, a heat dissipation metal layer is prepared on the surface of the substrate by metal sputtering, evaporation or electroplating; after the preparation of the heat dissipation metal layer, the following treatment is also included: etching the heat dissipation metal layer to remove the metal at the edge of the substrate, and forming a boss relative to the edge below the active area of ​​the GaN HEMT chip; the thickness of the heat dissipation metal layer is 1 μm to 600 μm; the material of the heat dissipation metal layer is at least one of Ti, Ni, Ag and Au; In step S4, the notch shape of the groove matches the shape of the heat dissipation metal layer; the thickness of the heat dissipation metal layer is the same as the thickness of the groove.

10. The packaging method according to claim 9, characterized in that: In step S5, the groove is stepped, and after the heat dissipation metal layer is embedded in the groove, the substrate portion of the GaN HEMT chip is embedded in the groove.

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