Wafer thermocompression bonding machine and wafer cooling method

Abstract

The invention discloses a wafer thermocompression bonding machine and a wafer cooling method. The wafer thermocompression bonding machine comprises a base assembly, a bonding base is arranged at the upper end of the base assembly, and a lower pressure plate assembly is installed on the inner side of the bonding base; comprising a bonding cover assembly, an upper pressure plate assembly is installed in a cover body of the bonding cover assembly, the cover body is hinged to the upper end of a base assembly and covers a bonding base in a sealing mode through the cover body, then a sealing cavity is formed between the bonding base and the cover body, and the upper pressure plate assembly directly faces a lower pressure plate assembly. According to the invention, the wafer cooling time is shortened, and the electric energy consumed in the cooling process is reduced.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology, specifically relating to a wafer hot-press bonding machine and a wafer cooling method. Background Technology

[0002] Wafer bonding is a key technology in semiconductor manufacturing and other fields. It is used to tightly bond two or more wafers through physical and chemical interactions. It is an indispensable and important step in the semiconductor manufacturing process. Due to the complexity of the process, various defects often occur, such as solder joint cracks, misalignment, and voids. These defects can significantly affect the performance and reliability of the chip. The main process of wafer bonding is as follows: the wafer is placed on the heating lower plate assembly, the bonding cover is closed → vacuum is drawn → heating is stopped after reaching the specified temperature (the temperature depends on the material, and before heating, the heating plate and cold screen of the heating upper plate assembly and the heating plate and cold screen of the heating lower plate assembly are separated by cylinders) → pressure is applied and held for half an hour to complete the bonding → the heating plates and cold screens of the heating upper plate assembly and the heating lower plate assembly are then bonded together by cylinders, and an external water chiller supplies cooling water to the cold screen until the wafer cools down to below 200°C → protective gas is injected into the vacuum chamber (vacuum breaking) → the bonding cover is opened, and the wafer is allowed to cool to room temperature.

[0003] The bonding process described above takes several hours to complete, with the cooling process being the longest. Therefore, the shortcomings of the above bonding process are: 1. During the cooling stage in a vacuum, the heat transfer path of the wafer is: heating plate → cold screen → cooling water. Obviously, the heat of the wafer needs to pass through the heating plate and cold screen, which is indirect heat dissipation and has low heat transfer efficiency. This is one of the reasons for the long cooling time in the bonding process.

[0004] 2. The cooling water's temperature rises after passing through the cold shield, then it is cooled by a water chiller before being circulated back into the cold shield for further cooling, thus forming a water-cooling cycle. A single wafer hot press bonding machine is typically equipped with multiple water chillers, the specific number depending on the bonding temperature. Taking a bonding temperature of 450℃ as an example, with each water chiller having a power of 450W, three water chillers are required, resulting in a total cooling power of 1350W for the wafer hot press bonding machine. After several hours of cooling, more than 10 kWh of electricity is consumed, which is one of the reasons for the high power consumption of existing wafer hot press bonding machines.

[0005] 3. During the vacuum breaking stage, room temperature nitrogen is introduced. Other inert gases can also be used, but nitrogen is inexpensive and is currently the conventional choice for vacuum breaking. If cryogenic nitrogen is introduced, its temperature is too low and difficult to control precisely, which can easily lead to a sudden temperature drop, causing wafer deformation or breakage. Therefore, conventional nitrogen is still used for vacuum breaking, and air cooling is not utilized at this stage to shorten the cooling time.

[0006] 4. During the natural cooling phase at room temperature after the bonding cap is opened, the temperature drops from 200°C to room temperature. The natural cooling time is too long, which is another reason for the long cooling time in the bonding process.

[0007] Therefore, existing wafer hot-press bonding has the technical problem of long cooling time, resulting in low wafer bonding efficiency. Summary of the Invention

[0008] To address the shortcomings of existing technologies and shorten wafer cooling time while reducing the electrical energy consumed during the cooling process, this invention provides a wafer thermoforming bonding machine. The machine includes a base assembly with a bonding base at its upper end and a lower pressure plate assembly mounted inside the bonding base. It also includes a bonding cover assembly with an upper pressure plate assembly mounted within its cover body. The cover body is hinged to the upper end of the base assembly and seals against the bonding base, forming a sealed cavity between the bonding base and the cover body. The upper and lower pressure plate assemblies are directly opposite each other. The machine further includes a cooling system comprising a low-temperature gas source and a normal-temperature gas source. Both the low-temperature gas from the low-temperature gas source and the normal-temperature gas from the normal-temperature gas source pass through a first temperature-controlled pipeline to the upper pressure plate assembly. The mixed gas passing through the upper pressure plate assembly passes through a second temperature-controlled pipeline to the lower pressure plate assembly and the sealed cavity, respectively. The mixed gas passing through the lower pressure plate assembly and the sealed cavity is recovered.

[0009] A preferred embodiment of the wafer hot-press bonding machine in this invention includes a recovery hood for recovering the mixed gas; the recovery hood is mounted on the upper end of the base assembly via a robotic arm, and the lower opening of the recovery hood is adapted to the bonding base. The function of the recovery hood is to recover the mixed gas passing through the wafer after the bonding cover assembly is opened. The recovery hood replaces the vacuum chamber, preventing the leakage of cooling gas.

[0010] The preferred embodiment of the wafer hot press bonding machine in this invention is as follows: the upper pressure plate assembly includes an upper fixed plate, an upper cooling screen, an upper heating plate, and an upper pressure plate connected sequentially from top to bottom, wherein the two ends of the upper cooling screen are connected between a first temperature control pipeline and a second temperature control pipeline; the lower pressure plate assembly includes a lower pressure plate, a lower heating plate, a lower cooling screen, and a lower fixed plate connected sequentially from top to bottom, wherein the two ends of the lower cooling screen are connected between a second temperature control pipeline and a recovery pipeline; the bonding base is provided with an air inlet pipe, the cover is provided with an exhaust pipe, and the recovery cover is provided with an air inlet hole adapted to the air inlet pipe. An air inlet pipe is added to the existing lower pressure plate assembly structure, and an exhaust pipe is added to the cover. During the vacuum breaking stage, a cooling gas of suitable temperature is introduced to lower the temperature in the vacuum chamber. The air inlet pipe and the exhaust pipe can form a circulating cooling channel for the cooling gas, continuously cooling the wafer, thereby greatly shortening the time required for wafer cooling.

[0011] A preferred embodiment of the wafer hot-press bonding machine in this invention is as follows: The first temperature control pipeline includes a first regulating valve, a second regulating valve, a first shut-off valve, and a first deformable mixing container; the low-temperature gas source is connected to the first deformable mixing container through the first regulating valve, the ambient temperature gas source is connected to the first deformable mixing container through the second regulating valve, and the first deformable mixing container is connected to the upper cooling screen through the first shut-off valve; a temperature probe electrically connected to the first shut-off valve is provided inside the first deformable mixing container. The second temperature control pipeline includes a third regulating valve, a fourth regulating valve, a second shut-off valve, and a second deformable mixing container; the low-temperature gas source is connected to the second deformable mixing container through the third regulating valve, the upper cooling screen is connected to the second deformable mixing container through the fourth regulating valve, and the second deformable mixing container is connected to the lower cooling screen and the inlet pipe through the second shut-off valve; a temperature probe electrically connected to the second shut-off valve is provided inside the second deformable mixing container. In addition, a check valve and a third shut-off valve are sequentially connected between the cryogenic gas source and the first regulating valve, and a check valve and a fourth shut-off valve are sequentially connected between the ambient temperature gas source and the second regulating valve. The first and second temperature control pipelines have similar structures, both utilizing cryogenic gas mixed with other gases and temporarily stored in a deformable mixing container. As the amount of gas increases, the volume of the deformable mixing container increases accordingly, compensating for the problems of the temperature control pipeline being unable to flow due to "only inflow and no outflow" and the continuous increase in internal pressure. Each deformable mixing container is equipped with a high-precision temperature probe, and cooling can only be used after the temperature of the deformable mixing container reaches the set temperature. This improves the temperature control accuracy of the cooling gas and effectively solves the technical problem of uneven cooling leading to uncontrollable wafer quality in existing wafer bonding machines.

[0012] The beneficial effects of the wafer hot-press bonding machine in this invention are as follows: 1. By actively absorbing the heat from the wafer, the upper pressure plate assembly, and the lower pressure plate assembly using cooling gas, the heat dissipation efficiency is greatly improved compared to the existing indirect heat dissipation structure, and the heat dissipation time is significantly reduced accordingly.

[0013] 2. Liquid nitrogen can be used for cryogenic gases, while room temperature nitrogen is used for ambient gases. Industrial liquid nitrogen costs several hundred yuan per ton, and one ton of liquid nitrogen can vaporize to obtain approximately 600 cubic meters of nitrogen gas, or 600,000 liters. Based on this calculation, the price of nitrogen gas after vaporization is less than 1 yuan per liter of liquid nitrogen, while the price of industrial nitrogen gas at ambient temperature is only a few cents per liter. The cooling system itself consumes very little power, with only the various solenoid valves and controllers consuming electricity, totaling tens of watts. Compared to water-cooled units of over 1 kilowatt, the energy consumption is significantly reduced, while the operating costs of liquid nitrogen and ambient temperature nitrogen gas are low. Therefore, using a cooling system instead of existing water-cooled units can greatly reduce cooling costs.

[0014] This invention also provides a wafer cooling method based on the aforementioned wafer hot-press bonding machine, comprising the following steps: After wafer bonding, the steps are as follows: First, the drive mechanism at the top of the bonding cover assembly raises the upper pressure plate assembly, separating it from the wafer. The upper cooling screen of the upper pressure plate assembly then attaches to the upper heating plate. The first temperature control pipeline mixes the low-temperature gas and the room-temperature gas to temperature T1. The first shut-off valve opens, lowering the temperature of the upper pressure plate assembly. The mixed gas passing through the upper cooling screen flows back to the second regulating valve through the first return pipeline, reducing the consumption of the room-temperature gas source. This cycle continues until the temperature of the upper pressure plate assembly drops to the set temperature.

[0015] Then, the drive mechanism inside the base assembly drives the lower cooling screen of the lower pressure plate assembly to fit against the lower heating plate. The second temperature control pipeline mixes the low-temperature gas with the mixed gas passing through the upper pressure plate assembly to a temperature T2. The second shut-off valve opens, breaking the vacuum and reducing the temperature of the lower pressure plate assembly and the wafer. Part of the mixed gas passing through the lower cooling screen and the sealed cavity flows back to the second regulating valve through the first branch pipeline, and another part of the mixed gas flows back to the fourth regulating valve through the second branch pipeline. The remaining mixed gas is recovered through the exhaust pipe, and the fifth shut-off valve is closed to reduce the consumption of room temperature gas source. This cycle continues until the wafer temperature drops to the set temperature.

[0016] Finally, the second shut-off valve is closed, the bonding cover assembly is opened, the robotic arm seals the recovery cover onto the bonding base, and the air inlet of the recovery cover is connected to the air inlet pipe. The second shut-off valve is opened, the recovery cover is connected to the recovery pipeline, and the mixed gas continues to cool the wafer to room temperature. When the cooling is finished, the cooling system is reset, and the robotic arm drives the recovery cover to reset. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the wafer hot-press bonding machine in this invention; Figure 2 for Figure 1 Diagram of the middle button lid assembly after opening Figure 1 ; Figure 3 for Figure 1 Diagram of the middle button lid assembly after opening Figure 2 ; Figure 4 for Figure 1 Diagram of the middle button lid assembly after opening Figure 3 ; Figure 5 This is a schematic diagram of the piping for the wafer cooling method in this invention.

[0019] Reference numerals: 1. Base assembly; 2. Bonding base; 3. Bonding cover assembly; 4. Cover body; 5. Upper pressure plate assembly; 6. Lower pressure plate assembly; 7. Recovery cover; 8. Robotic arm; 9. Inlet pipe; 10. Exhaust pipe; 11. Drive mechanism. Detailed Implementation

[0020] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution, its implementation process, and principles will be further explained below with reference to the accompanying drawings and specific implementation examples in the embodiments of this application.

[0021] Example 1; like Figure 1 and Figure 4 As shown, Embodiment 1 provides a wafer hot press bonding machine, including a base assembly 1, a bonding base 2 at the upper end of the base assembly 1, and a lower pressure plate assembly 6 installed inside the bonding base 2; and a bonding cover assembly 3, with an upper pressure plate assembly 5 installed inside the cover body 4 of the bonding cover assembly 3. The cover body 4 is hinged to the upper end of the base assembly 1 and seals the bonding base 2, thereby forming a sealed cavity between the bonding base 2 and the cover body 4, with the upper pressure plate assembly 5 and the lower pressure plate assembly 6 facing each other. The specific structures of the upper pressure plate assembly 5 and the lower pressure plate assembly 6 adopt existing structures. Specifically, the upper pressure plate assembly 5 includes an upper fixed plate, an upper cold screen, an upper heating plate, and an upper pressure plate connected sequentially from top to bottom, and the lower pressure plate assembly 6 includes a lower pressure plate, a lower heating plate, a lower cold screen, and a lower fixed plate connected sequentially from top to bottom.

[0022] This embodiment also includes a cooling system, which comprises a cryogenic gas source and a normal temperature gas source. The cryogenic gas source uses a liquid nitrogen storage cylinder, and the normal temperature gas source uses a normal temperature nitrogen cylinder. Both the cryogenic gas from the cryogenic gas source and the normal temperature gas from the normal temperature gas source pass through a first temperature-controlled pipeline to the upper pressure plate assembly 5. The mixed gas passing through the upper pressure plate assembly 5 passes through a second temperature-controlled pipeline to the lower pressure plate assembly 6 and the sealing cavity, respectively. The mixed gas passing through the lower pressure plate assembly 6 and the sealing cavity is recovered.

[0023] like Figure 2 and Figure 3As shown, in terms of structure, this embodiment also includes a recovery hood 7 for recovering the mixed gas. The recovery hood 7 is mounted on the upper end of the base assembly 1 via a robotic arm 8, and the lower opening of the recovery hood 7 is adapted to the bonding base 2. The bonding base 2 is provided with an inlet pipe 9, the cover 4 is provided with an exhaust pipe 10, and the recovery hood 7 is provided with an inlet hole adapted to the inlet pipe 9. When the recovery hood 7 is sealed and closed on the bonding base 2, the inlet hole of the recovery hood 7 is connected to the inlet pipe 9. The function of the recovery hood 7 is to recover the mixed gas that has passed through the wafer after the bonding cover assembly 3 is opened. The recovery hood 7 replaces the vacuum chamber to prevent the leakage of nitrogen gas used for cooling, which could cause local oxygen deficiency and lead to accidents.

[0024] The specific structure of the first temperature control pipeline mentioned above is as follows: The first temperature control pipeline includes a first regulating valve, a second regulating valve, a first shut-off valve, and a first deformable mixing container; the low-temperature gas source is connected to the first deformable mixing container through the first regulating valve, the normal temperature gas source is connected to the first deformable mixing container through the second regulating valve, and the first deformable mixing container is connected to the upper cooling screen through the first shut-off valve, and a temperature probe electrically connected to the first shut-off valve is provided inside the first deformable mixing container.

[0025] The specific structure of the aforementioned second temperature control pipeline is as follows: The second temperature control pipeline includes a third regulating valve, a fourth regulating valve, a second shut-off valve, and a second deformable mixing container. The low-temperature gas source is connected to the second deformable mixing container via the third regulating valve. The upper cooling screen is connected to the second deformable mixing container via the fourth regulating valve. The second deformable mixing container is connected to the lower cooling screen and the inlet pipe 9 via the second shut-off valve. A temperature probe electrically connected to the second shut-off valve is installed inside the second deformable mixing container. Additionally, a check valve and a third shut-off valve are sequentially connected between the low-temperature gas source and the first regulating valve, and a check valve and a fourth shut-off valve are sequentially connected between the ambient temperature gas source and the second regulating valve.

[0026] In this embodiment, both the first and second deformable mixing containers are annular pipes. The annular pipe includes an expandable pipe and a fixed pipe, with a circulating fan installed on the fixed pipe. The expandable pipe can change its volume to meet the temperature control requirements of the nitrogen mixing stage and serves as a temporary storage space. The circulating fan can quickly mix low-temperature nitrogen and room-temperature nitrogen, causing the temperature of the mixed nitrogen to quickly stabilize, thus significantly improving the mixing effect.

[0027] Furthermore, this embodiment also reduces the consumption of ambient temperature gas source through a reflux pipeline. Specifically, a first reflux pipeline connects the upper cooling screen and the fourth regulating valve to the ambient temperature gas source and the fourth regulating valve, and the first reflux pipeline is equipped with a check valve and a fifth shut-off valve. A first branch of the second reflux pipeline connects the lower cooling screen and the recovery pipeline to the ambient temperature gas source and the fourth regulating valve, and a second branch of the second reflux pipeline connects the upper cooling screen and the fourth regulating valve; the first branch pipeline is equipped with a check valve and a sixth shut-off valve, and the second branch pipeline is equipped with a check valve and a seventh shut-off valve.

[0028] In this embodiment, all shut-off valves and all regulating valves are solenoid valves. The cooling system is equipped with a controller, which automatically controls the opening and closing of each solenoid valve according to the set program to automatically complete the wafer cooling process.

[0029] Example 2; Example 2 provides a wafer cooling method. Example 2 is based on the wafer hot-press bonding machine of Example 1, and the method is as follows: First, the drive mechanism 11 at the upper end of the bonding cover assembly 3 drives the upper pressure plate assembly 5 to rise, separating the upper pressure plate assembly 5 from the wafer, and the upper cooling screen of the upper pressure plate assembly 5 is attached to the upper heating plate. The first temperature control pipeline mixes the low-temperature gas and the room temperature gas to temperature T1, and the first shut-off valve opens to reduce the temperature of the upper pressure plate assembly 5; the mixed gas passing through the upper cooling screen flows back to the second regulating valve through the first return pipeline to reduce the consumption of the room temperature gas source, and so on, until the temperature of the upper pressure plate assembly 5 drops to the set temperature.

[0030] Then, the drive mechanism 11 inside the base assembly 1 drives the lower cooling screen of the lower pressure plate assembly 6 to fit against the lower heating plate. The second temperature control pipeline mixes the low-temperature gas with the mixed gas passing through the upper pressure plate assembly 5 to a temperature T2. The second shut-off valve opens, breaking the vacuum and reducing the temperature of the lower pressure plate assembly 6 and the wafer. Part of the mixed gas passing through the lower cooling screen and the sealed cavity flows back to the second regulating valve through the first branch pipeline, and another part of the mixed gas flows back to the fourth regulating valve through the second branch pipeline. The remaining mixed gas is recovered through the exhaust pipe 10, and the fifth shut-off valve is closed to reduce the consumption of room temperature gas source. This cycle continues until the wafer temperature drops to the set temperature.

[0031] Finally, the second shut-off valve is closed, the bonding cover assembly 3 is opened, the robotic arm 8 seals the recovery cover 7 on the bonding base 2, and the air inlet of the recovery cover 7 is connected to the air inlet pipe 9. The second shut-off valve is opened, the recovery cover 7 is connected to the recovery pipeline, and the mixed gas continues to cool the wafer to room temperature. When the cooling ends, the cooling system is reset, and the robotic arm 8 drives the recovery cover 7 to reset.

[0032] The wafer cooling method in this embodiment is divided into three cooling stages. After the wafer bonding step is completed, in the first stage, the first regulating valve and the second regulating valve in the first temperature control pipeline release cryogenic liquid nitrogen and room temperature nitrogen according to the ratio set by the controller, and rapidly mix them in the first deformable mixing container. The first deformable mixing container increases in size accordingly. During the mixing process, the temperature is captured in real time by the temperature probe. When the temperature reaches T1, both the first regulating valve and the second regulating valve are closed, and the first shut-off valve is opened. The internal pressure of the first deformable mixing container is used to introduce precisely temperature-controlled nitrogen into the upper cooling screen. The nitrogen temperature rises and the heated nitrogen is stored in a temporary gas storage bottle between the upper cooling screen and the fifth shut-off valve. This part of the nitrogen will enter the next temperature control step. When the temperature of the upper pressure plate assembly 5 drops to the set temperature, or the gas pressure of the first deformable mixing container drops to the point where it is no longer possible to fill the temporary gas storage bottle, the first shut-off valve is closed, and the first regulating valve and the second regulating valve are opened. The above temperature control steps are repeated, but the nitrogen in the temporary gas storage bottle participates in the temperature control. The temperature of this part of the nitrogen is higher than that of room temperature nitrogen. For example, if T1 is set to 10℃, the nitrogen temperature in the temporary gas storage cylinder is 50-70℃. After mixing the higher temperature nitrogen with liquid nitrogen, the consumption of room temperature nitrogen can be reduced. Then, the upper pressure plate assembly 5 is cooled down until it drops to the set temperature.

[0033] The second stage involves releasing cryogenic liquid nitrogen and nitrogen gas passing through the upper cooling screen using the third and fourth regulating valves in the second temperature control pipeline according to the ratio set by the controller. To protect the wafer, the wafer cooling temperature is controlled at T2=20℃ to avoid excessive temperature differences that could cause wafer defects. T1 and T2 can be selected based on actual conditions; this embodiment does not impose any restrictions. The temperature control method of the second temperature control pipeline is the same as that of the first temperature control pipeline, but the difference is that the refluxed nitrogen gas is divided into three parts: one part participates in the temperature control of the first temperature control pipeline, another part is used for the temperature control of the second temperature control pipeline, and since there is no temporary gas storage cylinder after the second temperature control pipeline, the remaining nitrogen gas is recovered through the exhaust pipe 10 of the cover 4. The second step simultaneously satisfies both the vacuum breaking and direct cooling requirements.

[0034] The third stage is when the wafer is at room temperature and pressure. The robotic arm 8 seals the recovery cover 7 on the wafer and the pressure plate assembly 6. The wafer is then cooled further using 20°C nitrogen. During this process, the recovery cover 7 is connected to the recovery pipeline, and the remaining nitrogen is recovered through the recovery cover 7.

[0035] All three cooling stages mentioned above employ precise temperature control with direct contact nitrogen for cooling. Compared to existing water cooling and natural cooling methods, this significantly reduces the cooling time, thereby improving wafer bonding efficiency.

[0036] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A wafer hot press bonding machine, comprising a base assembly, wherein a bonding base is provided at the upper end of the base assembly and a lower pressure plate assembly is installed inside the bonding base; The assembly includes a bonding cover assembly, an upper pressure plate assembly installed inside the cover body of the bonding cover assembly, and a cover body hinged to the upper end of the base assembly. The cover body seals and covers the bonding base, thereby forming a sealed cavity between the bonding base and the cover body, with the upper pressure plate assembly and the lower pressure plate assembly facing each other. Its features are: It also includes a cooling system, which includes a low-temperature gas source and a normal-temperature gas source; the low-temperature gas from the low-temperature gas source and the normal-temperature gas from the normal-temperature gas source both pass through the first temperature control pipeline and then to the upper pressure plate assembly. The mixed gas passing through the upper pressure plate assembly passes through the second temperature control pipeline and then to the lower pressure plate assembly and the sealing cavity respectively. The mixed gas passing through the lower pressure plate assembly and the sealing cavity is recovered.

2. The wafer hot-press bonding machine according to claim 1, characterized in that: It includes a recovery hood for recovering mixed gases; the recovery hood is mounted on the upper end of a base assembly via a robotic arm, and the lower opening of the recovery hood is adapted to the bonding base.

3. A wafer hot-press bonding machine according to claim 2, characterized in that: The upper pressure plate assembly includes an upper fixed plate, an upper cooling plate, an upper heating plate, and an upper pressure plate connected in sequence from top to bottom, wherein the two ends of the upper cooling plate are connected between the first temperature control pipeline and the second temperature control pipeline; the lower pressure plate assembly includes a lower pressure plate, a lower heating plate, a lower cooling plate, and a lower fixed plate connected in sequence from top to bottom, wherein the two ends of the lower cooling plate are connected between the second temperature control pipeline and the recovery pipeline; the bonding base is provided with an air inlet pipe, the cover is provided with an exhaust pipe, and the recovery cover is provided with an air inlet hole adapted to the air inlet pipe.

4. A wafer hot-press bonding machine according to claim 3, characterized in that: The first temperature control pipeline includes a first regulating valve, a second regulating valve, a first shut-off valve, and a first deformable mixing container; the low-temperature gas source is connected to the first deformable mixing container through the first regulating valve, the normal temperature gas source is connected to the first deformable mixing container through the second regulating valve, and the first deformable mixing container is connected to the upper cooling screen through the first shut-off valve, and a temperature probe electrically connected to the first shut-off valve is provided inside the first deformable mixing container.

5. A wafer hot-press bonding machine according to claim 4, characterized in that: The second temperature control pipeline includes a third regulating valve, a fourth regulating valve, a second shut-off valve, and a second deformable mixing container; the low-temperature gas source is connected to the second deformable mixing container through the third regulating valve, the upper cooling screen is connected to the second deformable mixing container through the fourth regulating valve, and the second deformable mixing container is connected to the lower cooling screen and the air inlet pipe through the second shut-off valve, and a temperature probe electrically connected to the second shut-off valve is provided inside the second deformable mixing container.

6. A wafer hot-press bonding machine according to claim 5, characterized in that: The low-temperature gas source is connected to the first regulating valve by a check valve and a third shut-off valve in sequence, and the normal-temperature gas source is connected to the second regulating valve by a check valve and a fourth shut-off valve in sequence.

7. A wafer hot-press bonding machine according to claim 6, characterized in that: The upper cooling screen and the fourth regulating valve are connected through a first return pipeline to the ambient temperature gas source and the fourth regulating valve, and the first return pipeline is equipped with a check valve and a fifth shut-off valve; the lower cooling screen and the recovery pipeline are connected through a first branch of the second return pipeline to the ambient temperature gas source and the fourth regulating valve, and through a second branch of the second return pipeline to the upper cooling screen and the fourth regulating valve; the first branch pipeline is equipped with a check valve and a sixth shut-off valve, and the second branch pipeline is equipped with a check valve and a seventh shut-off valve.

8. A wafer hot-press bonding machine according to claim 7, characterized in that: Both the first deformable mixing container and the second deformable mixing container are annular pipes. The annular pipes include an expandable pipe and a fixed pipe, and the fixed pipe is equipped with a circulating fan.

9. A wafer cooling method, characterized in that: Applied to the wafer hot-press bonding machine of claim 8, after wafer bonding, the steps are as follows: S1. The drive mechanism at the top of the bonding cover assembly drives the upper pressure plate assembly to rise, the upper pressure plate assembly separates from the wafer, and the upper cold screen of the upper pressure plate assembly is attached to the upper heating plate. S2. The first temperature control pipeline mixes the low-temperature gas and the normal-temperature gas to temperature T1. The first shut-off valve opens to reduce the temperature of the upper pressure plate assembly. The mixed gas that has passed through the upper cooling screen flows back to the second regulating valve through the first return pipeline to reduce the consumption of the normal-temperature gas source. This cycle continues until the temperature of the upper pressure plate assembly drops to the set temperature. S3. The drive mechanism inside the base assembly drives the lower cooling screen of the lower pressure plate assembly to fit against the lower heating plate; S4. The second temperature control pipeline mixes the low-temperature gas with the mixed gas passing through the upper pressure plate assembly to a temperature of T2. The second shut-off valve opens, breaking the vacuum and reducing the temperature of the lower pressure plate assembly and the wafer. Part of the mixed gas passing through the lower cooling screen and the sealing cavity flows back to the second regulating valve through the first branch pipeline, and another part of the mixed gas flows back to the fourth regulating valve through the second branch pipeline. The remaining mixed gas is recovered through the exhaust pipe. The fifth shut-off valve is closed to reduce the consumption of room temperature gas source. This cycle continues until the wafer temperature drops to the set temperature. S5. Close the second shut-off valve, open the bonding cover assembly, and the robotic arm seals the recovery cover onto the bonding base. The air inlet of the recovery cover is connected to the air inlet pipe. Open the second shut-off valve, and the recovery cover is connected to the recovery pipeline. The mixed gas continues to cool the wafer to room temperature. When the cooling ends, the cooling system is reset, and the robotic arm drives the recovery cover to reset.

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