Low-temperature and high-pressure nano-silver sintering equipment and process

Abstract

The invention relates to low-temperature and high-pressure nano-silver sintering equipment and process, and relates to the technical field of semiconductor device preparation. The low-temperature high-pressure nano-silver sintering equipment comprises a rack, an upper die and a lower die are oppositely arranged on the rack up and down, and a driving part used for driving the lower die to reciprocate up and down is arranged below the lower die; the upper die is provided with a multi-mode pressure head assembly facing the lower die, and the multi-mode pressure head assembly comprises a plurality of pressing blocks and a hydraulic cylinder capable of independently controlling each pressing block; a heating platform is arranged on the lower die, a clamp is arranged on the heating platform, an upper cover plate is detachably arranged on the clamp, and a closed cavity for placing a semiconductor device to be sintered can be formed between the clamp and the upper cover plate; and a heating assembly and a cooling assembly are arranged in each of the heating platform and the multi-mode pressure head assembly. The invention further discloses a low-temperature and high-pressure nano-silver sintering process. The nano-silver sintering equipment and process are high in working efficiency, good in product quality and low in product reject ratio.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor device preparation, and in particular to a low-temperature and high-pressure nano-silver sintering device and process. Background Art

[0002] Nanosilver sintering is a low-temperature sintering technology developed in the late 1980s, that is, a method of interconnecting power semiconductor devices and substrates with nanosilver at a relatively low temperature by applying pressure or without applying pressure. Sintered silver is available in paste, dot coating, printing, and film forms, and different products and processes correspond to different sintered silver materials. Nanosilver particles diffuse between solids under a certain temperature and pressure, and finally form a microscopic porous structure. Nanosilver sintering can obtain a sintered silver chip connection interface with high temperature resistance (>700°C) and high thermal conductivity (about 240 W / m·K) under low temperature (<300°C) conditions. It is one of the most suitable interface connection technologies for wide bandgap semiconductor module packaging, a key technology in silicon carbide module packaging, and the most widely used technology at present.

[0003] When nanosilver is sintered, the nanosilver particles are heated to above their melting point, so that the surface of the nanosilver particles melts, and a solidification process occurs at the same time, so that the vertices are interconnected and merged. This can effectively eliminate the gaps between the nanoparticles and obtain a more dense and uniform silver film; the sintering technology can be used to obtain nanosilver in different forms, such as spherical, flat, chain, etc., which has a wider range of selectivity for different application fields, so as to better meet the needs of various application fields.

[0004] Compared with the traditional connection method, the connection layer formed by nano silver sintering is composed of silver, which has high density and excellent electrical conductivity, thermal conductivity, and photoelectric properties; good stability, high mechanical strength, and is not easy to oxidize and degrade after long-term use; the melting point of silver is as high as 961℃, and it will not produce the typical fatigue effect that occurs in the solder connection layer with a melting point of less than 300℃, and has extremely high reliability; the sintered material does not contain elements such as lead and cadmium, and is an environmentally friendly material. High-power devices have very high requirements for the packaging and sintering of IGBTs. Many companies are also committed to finding various reliable methods to improve their sintering conductivity, which easily leads to an increase in the cost of high-power device companies. The use of low-temperature sintering nano silver technology will greatly help reduce the comprehensive cost of high-power devices, which is mainly manifested in: the alloy layer formed by silver sintering has higher strength, significantly reduces the thermal resistance inside the IGBT module, and improves the power density and integration of the module; SiC chips and silver sintering technology help to reduce the product size of power devices and help to improve the power density of controllers.

[0005] Pressure is the core factor affecting the quality of nanosilver sintering. The magnitude of pressure directly affects the void rate, thermal conductivity, push-pull force and thickness of the silver layer after sintering. Therefore, how to provide accurate and stable sintering pressure is the key to the heat dissipation and reliability of automotive-grade power modules. There are three main types of press heads for existing nanosilver sintering equipment: 1. Integral press head, which is to press down with a whole plate, cover several AMBs at the same time, and press dozens of chips at the same time; due to the influence of the mold plate, the flatness of the product fixture and the thickness tolerance of the chip itself, using a whole steel plate to press at the same time, some chips will be subject to large force, and some chips will be subject to small force, that is, the chip pressure is uneven; high pressure may cause cracks or even breakage, and small force will result in insufficient sintering strength. 2. The combination of integral press head and soft die head, that is, adding a layer of soft rubber die head at the bottom of the integral press head. This structure can slightly reduce the influence of small force on some chips. However, the following problems still exist: the rubber die head is not durable and easy to damage; the force on the surfaces of different chips is still uneven. 3. Pneumatic multi-pressure head technology uses a customized high-pressure cylinder to drive a single pressure head to apply pressure to a single chip. The actual pressure is changed by changing the air pressure of the high-pressure cylinder. Although it can ensure the force on each chip, the gas is easily compressed and the air pressure is difficult to control under high pressure (above 10MPA). Moreover, the air source is the factory air source, and the overall air pressure fluctuation of the factory air source will affect the output air source, and then affect the pressure head pressure. In addition, the overall working efficiency of traditional processes and equipment is low, and the delivery time is long. Summary of the invention

[0006] In order to improve the efficiency and quality of nanosilver sintering, the present application provides a low-temperature and high-pressure nanosilver sintering device and process.

[0007] In the first aspect, the present application provides a low-temperature and high-pressure nanosilver sintering device that adopts the following technical solution: A low-temperature and high-pressure nano-silver sintering device comprises a frame, an upper die and a lower die are arranged on the frame in a relative manner, and a driving member for driving the lower die to move up and down is arranged below the lower die; The upper die is provided with a multi-modal pressing head assembly facing the lower die, and the multi-modal pressing head assembly includes a plurality of pressing blocks and a hydraulic cylinder capable of individually controlling each pressing block; The lower mold is provided with a heating platform, the heating platform is provided with a fixture, the fixture is detachably provided with an upper cover plate, and a closed cavity for placing the semiconductor device to be sintered can be formed between the fixture and the upper cover plate; The heating platform and the multi-modal press head assembly are both provided with a heating assembly and a cooling assembly.

[0008] The single-chip single-pressure-head structure adopted in this application can ensure the stress condition of each chip, and can take into account chips or clips of different heights; it realizes that each chip can obtain precise and controllable pressure during the sintering process, solves the problem of uneven chip pressure existing in the prior art, and improves the sintering quality and yield rate. By adopting the above technical scheme, this application allows chips of different sizes and stress requirements to be processed on the same substrate, enhancing the applicability and flexibility of the equipment. The integrated design of the heating component and the cooling component not only speeds up the temperature regulation speed and improves the production efficiency, but also ensures the precise control of the temperature during the sintering process, further ensuring the product quality. In addition, the design of the closed cavity cooperates with the vacuum pumping or nitrogen filling function to effectively isolate the outside air, prevent the occurrence of oxidation during the sintering process, and ensure the high quality of the sintering interface.

[0009] In this application, preheating, sintering and cooling are three-in-one. Human workers only need to load materials at the entrance and take materials out at the exit. The intermediate processes are fully automatic, which greatly saves manual workload and makes the quality more uniform.

[0010] In the present application, the preheating station and the sintering station are equipped with cooling circuits, which can quickly cool down and realize rapid changeover of the entire equipment.

[0011] Optionally, the fixture has an air channel for evacuating the closed cavity or a nitrogen channel for supplying nitrogen into the closed cavity, and the closed cavity is provided with a vacuum gauge for measuring the vacuum degree in the closed cavity and an oxygen analyzer for measuring the oxygen content in the closed cavity; the air channel is connected to a vacuum pump, and the nitrogen channel is connected to an air pump.

[0012] By adopting the above technical solution, an oxygen-free environment is effectively created and maintained during the sintering process, ensuring that the quality of nanosilver sintering is not affected by oxygen in the air, thereby improving the conductivity and thermal stability of the sintered layer. At the same time, through real-time monitoring of the vacuum degree and oxygen content in the closed chamber, the precise control of the sintering environment parameters is ensured, improving the sintering success rate and consistency of product quality.

[0013] Optionally, the heating component on the heating platform includes a heating rod disposed inside the heating platform, and the cooling component on the heating platform includes a water flow channel located inside the heating platform; The multimodal press head assembly further comprises a base plate, the press block slides through the base plate, a heating plate and a cooling plate are sequentially arranged on a side of the base plate away from the lower die, the heating assembly in the multimodal press head assembly comprises a heating rod arranged in the heating plate, and the cooling assembly in the multimodal press head assembly comprises a water flow channel located in the cooling plate; The water flow channel is connected with a water valve system; the heating platform and the heating plate are also provided with thermometers.

[0014] By adopting the above technical solutions, efficient heating and precise cooling of the heating platform and multi-modal pressure head assembly are achieved, ensuring the temperature uniformity and controllability during the sintering process. The design of the heating rod can quickly increase the temperature to meet the high temperature conditions required for nanosilver sintering, and the built-in water flow channel combined with the water valve system can quickly take away heat, accelerate the cooling process, reduce the overall operating time of the equipment, and improve production efficiency. The setting of the thermometer further improves the accuracy of temperature monitoring, ensuring the sintering quality while reducing energy consumption.

[0015] Optionally, the heating rod is an electric heating rod, and there are a plurality of heating rods which are embedded at intervals along the width direction of the heating platform and the heating plate.

[0016] By adopting the above technical solution, the uniform distribution of heating rods in the heating platform and heating plate is achieved, the temperature consistency of the heating area is ensured, and the stability and reliability of the sintering process are improved. The design of the electric heating rod is not only easy to install and maintain, but also has a fast response speed, which can quickly reach the required heating temperature, which is conducive to improving the sintering efficiency. At the same time, the method of embedding multiple heating rods at intervals also helps to reduce local overheating and extend the service life of the equipment.

[0017] Optionally, the driving member is a gas-liquid booster cylinder or a servo electric cylinder; a guide rod is provided on the frame, the lower mold is slidably arranged on the guide rod, and the output shaft of the driving member is vertically arranged upward and connected to the middle position of the bottom of the lower mold.

[0018] By adopting the above technical solution, the precise linkage between the drive and the lower die is achieved, and the stability and accuracy of the pressure applied during the sintering process are improved. The design of the guide rod further enhances the directionality and linearity of the lower die movement, reduces the stress concentration caused by offset, ensures the sintering quality and prolongs the service life of the equipment.

[0019] Optionally, a high temperature resistant sealing ring is further provided between the clamp and the upper cover plate; and a through hole corresponding to the pressing block is opened on the upper cover plate.

[0020] By adopting the above technical solution, the sealing performance between the clamp and the upper cover plate is improved, which effectively prevents external impurities and oxygen from entering the closed cavity, ensures a pollution-free and oxygen-free environment during the nanosilver sintering process, and improves the sintering efficiency and quality.

[0021] Optionally, the rack cover is provided with a chassis, the upper mold and the lower mold are both located in the chassis, a door that can be opened and closed is provided on one side of the chassis, and transparent windows are provided on multiple sides of the chassis and the door; an air inlet is provided on one side of the chassis, and an air suction port is provided on the top of the chassis.

[0022] By adopting the above technical solutions, not only the overall aesthetics and operational safety of the equipment are improved, but also the changes in the sintering process can be observed in real time. Specifically, the openable and closable design of the box door facilitates operators to load and unload products, improving work efficiency. The setting of the transparent window allows the operator to monitor the internal conditions without interfering with the sintering process and detect abnormal conditions in time. The configuration of the air inlet and air suction port helps to maintain air circulation inside and outside the chassis, optimizes the ventilation and heat dissipation conditions of the equipment, further ensures the stability of the sintering process and the quality of the product, and at the same time extracts the exhaust gas generated during the sintering process through the air suction port, purifies it, and protects the atmospheric environment.

[0023] Optionally, the low-temperature and high-pressure nano-silver sintering equipment also includes a control box, which is connected to one side of the chassis and is provided with a display screen and control buttons; the chassis is also provided with an electronic pressure gauge, a hydraulic instrument and a temperature control instrument; and a warning light is also provided on the top of the chassis.

[0024] By adopting the above technical solutions, intelligent control of low-temperature and high-pressure nanosilver sintering equipment has been realized. Specifically, the control box integrates operation interfaces such as display screens and control buttons, which are convenient for users to intuitively monitor and adjust equipment operating parameters. The configuration of electronic barometers, hydraulic instruments and temperature control instruments further improves the monitoring capability and control accuracy of the equipment, ensuring that the air pressure, hydraulic pressure and temperature can be maintained at the optimal level throughout the sintering process, effectively improving the sintering quality. The warning light design on the top can promptly remind operators in abnormal conditions, enhancing the safety and reliability of the equipment.

[0025] In the second aspect, the present application provides a low-temperature and high-pressure nano-silver sintering process using the following technical solutions: A low-temperature and high-pressure nano-silver sintering process, using the above-mentioned low-temperature and high-pressure nano-silver sintering equipment to sinter nano-silver, adopts the following steps: S1. Place the AMB substrate after the patch is completed in the fixture, and the fixture is covered with an upper cover plate, and the fixture and the upper cover plate are sealed and connected to form a closed cavity between the two, so that the semiconductor device to be sintered is located in the closed cavity; S2. Place the fixture on the heating platform, and use the sensor to sense that the fixture is in place; S3. Start the vacuum pump to evacuate the closed cavity so that the closed cavity reaches a predetermined vacuum degree; or fill the closed cavity with nitrogen so that the closed cavity is filled with inert gas, start the driving member to drive the heating platform and the fixture to rise to the position, and the lower mold and the upper mold and the multi-modal pressure head assembly are molded; S4. Open the reversing valve of the precision hydraulic system to supply oil to the hydraulic cylinder of the multi-modal pressure head assembly, accurately control the oil pressure, and control multiple different oil pressures according to actual conditions, thereby driving the telescopic rod inside the multi-modal pressure head assembly to extend, and the pressure blocks on the telescopic rod press the corresponding chips respectively; S5. The heating platform and the pressing block in the multi-modal pressing head assembly are heated and heated respectively, and after reaching the set temperature, the pressure and temperature are maintained for a predetermined time; S6. The multi-modal pressure head assembly and the heating platform stop heating, and the water valve system is used to supply cooling water to the cooling assembly, thereby cooling the multi-modal pressure head assembly and the heating platform; S7. After the temperature drops to the preset temperature, the water valve system stops passing water, stops vacuuming or filling with nitrogen, and the driving component drives the heating platform and the product fixture to descend; S8. Remove the fixture, open the upper cover, remove the sintered semiconductor device product, and sintering is completed.

[0026] By adopting the above technical scheme, efficient and precise nanosilver sintering of semiconductor devices is achieved. Specifically, the process applies independently controlled pressure to each chip through a multi-modal press head assembly, ensuring that each chip is evenly stressed during the sintering process and improving the sintering quality. The integrated design of preheating, sintering, and cooling reduces the operating steps and improves production efficiency. The built-in vacuum and nitrogen circuits of the equipment effectively isolate oxygen, prevent the occurrence of oxidation reactions, and ensure the quality and reliability of the sintered layer. The independent temperature control system of the heating platform and the multi-modal press head assembly ensures precise temperature control and further improves the sintering effect. In summary, this technical solution not only solves the problems of uneven pressure and oxidation in the prior art, but also reduces production costs and improves product yield and production efficiency through optimized process flow.

[0027] Optionally, during the pressure-maintaining and heat-maintaining process in the above-mentioned step S5, the oil pump pressure and the servo proportional valve PID control the oil pressure, and the upper and lower mold temperatures and their respective PT100 sensor PID control the temperatures.

[0028] By adopting the above technical solution, the oil pump pressure and servo proportional valve can be accurately controlled during the sintering process, ensuring the stability and accuracy of the pressure and avoiding poor sintering caused by pressure fluctuations. At the same time, the upper and lower mold temperatures are PID-controlled by their respective PT100 sensors, ensuring the uniformity and stability of the temperature, improving the sintering quality, reducing energy consumption, and improving the overall performance and reliability of the equipment.

[0029] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application adopts a single-chip single-pressure head structure to ensure the stress condition of each chip, taking into account chips of different heights, so that each chip can obtain precise and controllable pressure during the sintering process, solving the problem of uneven chip pressure in the prior art and improving the sintering quality and yield rate.

[0030] 2. This application allows chips of different sizes and force requirements to be processed on the same substrate, which enhances the applicability and flexibility of the equipment.

[0031] 3. The integrated design of the heating component and the cooling component in this application not only speeds up the temperature adjustment and improves the production efficiency, but also ensures the precise control of the temperature during the sintering process, further ensuring the product quality.

[0032] 4. The design of the closed chamber in this application cooperates with the vacuum pumping or nitrogen filling function to effectively isolate the outside air, prevent the occurrence of oxidation during the sintering process, and ensure the high quality of the sintering interface.

[0033] 5. In this application, preheating, sintering and cooling are three-in-one. Human labor only needs to load materials at the entrance and take materials out at the exit. The intermediate process is fully automatic, which greatly saves labor workload and makes the quality more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the three-dimensional structure of the nanosilver sintering equipment in this application.

[0035] Figure 2 It is a front view structural schematic diagram of the nanosilver sintering device in this application.

[0036] Figure 3 It is a left-side structural schematic diagram of the nanosilver sintering device in this application.

[0037] Figure 4 It is a schematic diagram of the top view of the structure of the nanosilver sintering device in this application.

[0038] Figure 5 It is a schematic diagram of the internal three-dimensional structure of the nanosilver sintering equipment in this application.

[0039] Figure 6 It is a schematic diagram of the internal front view structure of the nanosilver sintering equipment in this application.

[0040] Figure 7 It is a schematic diagram of the internal left view of the nanosilver sintering equipment in this application.

[0041] Figure 8 It is a schematic diagram of the internal top view structure of the nanosilver sintering equipment in this application.

[0042] Fig. 9It is a schematic diagram of the partial three-dimensional structure of the nanosilver sintering equipment in this application.

[0043] Fig.10 It is a partial front view structural schematic diagram of the nanosilver sintering equipment in this application.

[0044] Fig.11 It is a partial left-view structural schematic diagram of the nanosilver sintering equipment in this application.

[0045] Fig.12 It is a partial top view structural schematic diagram of the nanosilver sintering device in this application.

[0046] In the figure: 10. Frame; 20. Upper die; 30. Lower die; 40. Driving part; 50. Multimodal press head assembly; 51. Press block; 52. Base plate; 60. Heating platform; 70. Heating assembly; 71. Heating rod; 80. Cooling assembly; 81. Water flow channel; 90. Air channel; 100. Nitrogen channel; 110. Water valve system; 120. Guide rod; 130. Upper cover plate; 131. Through hole; 140. Fixture; 150. Chassis; 151. Box door; 152. Transparent window; 153. Air inlet; 154. Air inlet; 160. Control box; 161. Display screen; 162. Control button; 170. Electronic barometer; 180. Hydraulic instrument; 190. Temperature control instrument; 200. Warning light; 210. Fomar wheel; 220. Precision hydraulic system; 230. Thermometer. DETAILED DESCRIPTION

[0047] The following will be combined with the attached Figure 1 -Attached Fig.12 , the technical solutions in the embodiments of the present invention are clearly and completely described. The described embodiments are only possible technical implementations of the present invention, not all possible implementations. Those skilled in the art can completely combine the embodiments of the present invention to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of the present invention.

[0048] Reference Figure 1 , Figure 2 and Figure 3 As shown, a low-temperature and high-pressure nanosilver sintering device provided in this embodiment includes a frame 10 and a chassis 150. The chassis 150 is covered outside the frame 10. Four Forma wheels 210 are installed at the bottom of the chassis 150. The four Forma wheels 210 are respectively installed at the four corners of the bottom of the chassis 150. In this way, the rollers of the Forma wheels 210 can be used to conveniently move the entire device, and the support feet of the Forma wheels 210 can be used to ensure the stability and reliability of the installation and placement of the entire device. The height of the support feet can also be adjusted by the adjustment structure of each Forma wheel 210, thereby adjusting the horizontality of the entire device, and further ensuring the stability and reliability of the placement of the entire device.

[0049] Reference Figure 1 , Figure 3 and Figure 4 As shown, a door 151 that can be opened and closed is provided on one side of the chassis 150, and transparent windows 152 are provided on multiple sides of the chassis 150 and the door 151; an air inlet 153 is provided on one side of the chassis 150, and a blocking grid is provided at the air inlet 153 to prevent larger foreign objects from entering the chassis 150, and an air suction port 154 is provided on the top of the chassis 150, and the air suction port 154 is connected to the exhaust gas treatment system through a ventilation pipe, and an exhaust fan is provided in the ventilation pipe, so as to purify the exhaust gas in the chassis 150 and protect the atmospheric environment. The above structure improves the overall aesthetics and operational safety of the equipment, and is also convenient for real-time observation of changes in the internal working process of the chassis 150.

[0050] Reference Figure 1 , Figure 5 and Figure 6 As shown, an upper mold 20 and a lower mold 30 are provided on the frame 10, and both the upper mold 20 and the lower mold 30 are located in the chassis 150. The upper mold 20 and the lower mold 30 are arranged opposite to each other up and down. Four guide rods 120 are provided on the frame 10, and the four corners of the lower mold 30 are slidably sleeved on the guide rods 120. Therefore, the lower mold 30 can reciprocate on the guide rods 120 toward the upper mold 20; a driving member 40 is provided below the lower mold 30 in the chassis 150, and the output shaft of the driving member 40 is vertically arranged upward and connected to the middle position of the bottom of the lower mold 30. The driving member 40 is used to drive the lower mold 30 to reciprocate up and down. In the present application, the driving component 40 can be a gas-liquid booster cylinder, a servo electric cylinder, or a combined driving component formed by a servo electric cylinder and a force-multiplying mechanism. The driving component 40 drives the lower mold 30 to move, thereby realizing rapid mold opening and closing of the lower mold 30 and the upper mold 20. In the present application, it can ensure that the mold closing pressure reaches 40MPA, which is lighter and more compact than traditional bulky large hydraulic cylinders, and it moves quickly and efficiently.

[0051] Reference Figure 7 , Figure 8 and Fig. 9As shown, the upper mold 20 is provided with a multi-modal pressing head assembly 50 facing the lower mold 30, and the multi-modal pressing head assembly 50 includes a plurality of pressing blocks 51 and a hydraulic cylinder capable of individually controlling each pressing block 51; the lower mold 30 is provided with a heating platform 60, and the heating platform 60 is provided with a fixture 140, and the fixture 140 is detachably provided with an upper cover plate 130, and a high temperature resistant sealing ring is also provided between the fixture 140 and the upper cover plate 130; the upper cover plate 130 is provided with a through hole 131 corresponding to the pressing block 51; a closed cavity for placing the semiconductor device to be sintered can be formed between the fixture 140 and the upper cover plate 130. The fixture 140 in this application can be customized according to SIC products, and different specifications such as 2-pack or 4-pack can be customized according to needs.

[0052] Reference Fig.10 , Fig.11 and Fig.12 As shown, the fixture 140 has an air channel 90 for evacuating the closed cavity or a nitrogen channel 100 for supplying nitrogen into the closed cavity, and the closed cavity is provided with a vacuum gauge for measuring the vacuum degree in the closed cavity and an oxygen analyzer for measuring the oxygen content in the closed cavity; the air channel 90 is connected to a vacuum pump, and the nitrogen channel 100 is connected to an air pump.

[0053] Further, combined with Figure 1 , Figure 7 and Fig. 9 As shown, a heating assembly 70 and a cooling assembly 80 are both provided in the heating platform 60 and the multimodal press head assembly 50. The heating assembly 70 on the heating platform 60 includes a heating rod 71 provided in the heating platform 60, and the cooling assembly 80 on the heating platform 60 includes a water flow channel 81 located in the heating platform 60; the multimodal press head assembly 50 also includes a substrate 52, and the pressing block 51 slides through the substrate 52, and a heating plate and a cooling plate are sequentially provided on the side of the substrate 52 away from the lower mold 30, the heating assembly 70 in the multimodal press head assembly 50 includes a heating rod 71 provided in the heating plate, and the cooling assembly 80 in the multimodal press head assembly 50 includes a water flow channel 81 located in the cooling plate; the water flow channel 81 is connected to a water valve system 110; a thermometer 230 is also provided in the heating platform 60 and the heating plate, and the thermometer 230 can adopt a PT100 sensor.

[0054] The heating rod 71 in the present application may be an electric heating rod 71 , and there are a plurality of heating rods 71 ​​which are embedded at intervals along the width direction of the heating platform 60 and the heating plate.

[0055] Reference Figure 1As shown, one side of the chassis 150 is also connected to the control box 160, and the control box 160 is provided with a display screen 161 and a control button 162; the chassis 150 is also provided with an electronic barometer 170, a hydraulic instrument 180 and a temperature control instrument 190; the electronic barometer 170 is used to display the air supply pressure of the equipment and the negative pressure of the vacuum pumping, and the hydraulic instrument 180 is used to display the pressure of the hydraulic system; the temperature control instrument 190 can be a six-link meter, which is used to control the temperature of the multi-modal pressure head assembly 50 and the heating platform 60; the top of the chassis 150 is also provided with a warning light 200, which is used to display the equipment in different states such as working, waiting, and emergency stop. The control box 160 can adopt an HMI control box 160, and the above-mentioned display screen 161 is a touch screen. The display screen 161 can include manual interface, automatic interface, alarm interface, recipe management, curve display and other functional options, and the entire device can be automatically controlled by a PLC controller.

[0056] This embodiment also provides a low-temperature and high-pressure nano-silver sintering process, which uses the above-mentioned low-temperature and high-pressure nano-silver sintering equipment to perform nano-silver sintering, and specifically includes the following steps: S1. The AMB substrate 52 after the chip bonding is placed in the fixture 140, and the upper cover plate 130 is placed on the fixture 140. The fixture 140 and the upper cover plate 130 are sealed and connected to form a closed cavity between the two, so that the semiconductor device to be sintered is located in the closed cavity; S2. The fixture 140 is placed on the heating platform 60, and the sensor senses that the fixture 140 is in place; S3. Start the vacuum pump to evacuate the closed cavity so that the closed cavity reaches a predetermined vacuum degree; or fill the closed cavity with nitrogen so that the closed cavity is filled with inert gas, start the drive member 40 to drive the heating platform 60 and the fixture 140 to rise to the position, and the lower mold 30 and the upper mold 20 and the multi-modal pressure head assembly 50 are molded; S4. By opening the reversing valve of the precision hydraulic system 220 to supply oil to the hydraulic cylinder of the multi-modal pressure head assembly 50, the oil pressure is accurately controlled, and multiple different oil pressures are controlled according to actual conditions, thereby driving the telescopic rod inside the multi-modal pressure head assembly 50 to extend, and the pressure blocks 51 on the telescopic rods respectively press the corresponding chips; S5. The heating platform 60 and the pressing block 51 in the multi-modal pressing head assembly 50 are heated and heated respectively. After reaching the set temperature, the pressure and temperature are maintained for a predetermined time. During this process, the oil pump pressure and the servo proportional valve PID control the oil pressure, and the upper and lower molds 30 are controlled by the respective PT100 sensors PID to achieve a temperature control of 25 to 320°C ± 1°C; S6. The multi-modal pressure head assembly 50 and the heating platform 60 stop heating, and the water valve system 110 supplies cooling water to the cooling assembly 80, thereby cooling the multi-modal pressure head assembly 50 and the heating platform 60; S7. After the temperature reaches a predetermined temperature, the water valve system 110 stops the water flow, stops the vacuum or nitrogen filling, and the drive member 40 drives the heating platform 60 and the product fixture 140 to drop; S8. Remove the fixture 140, open the upper cover 130, remove the sintered semiconductor device product, and the sintering is completed.

[0057] The implementation principle of this embodiment is as follows: the low-temperature and high-pressure nanosilver sintering equipment in this embodiment adopts a single-chip single-pressure head structure, which can output multiple pressures, for example, it can output four different pressures at the same time to adapt to chips of different sizes and different force requirements on the same AMB substrate 52; independent hydraulic cylinders drive independent pressure blocks 51, and cooperate with the precision hydraulic system 220 to provide power. The precision hydraulic system 220 provides multi-channel hydraulic pressure and can accurately control the size of the hydraulic pressure, so as to achieve a pressure accuracy of each pressure block 51±0.5% (full range); and the pressure servo is adjustable, and only the required pressure needs to be input on the HMI control box 160, and the system will automatically change, with a response speed of less than 5s, which is convenient for process debugging; its conventional pressure can reach 30MPA, and with a specially customized high-pressure oil pump system, it can also achieve an ultra-high pressure of 50MPA.

[0058] In the present application, the stress condition of each chip can be guaranteed, thereby taking into account the requirements of chips of different heights; each chip can obtain precise and controllable pressure during the sintering process, solves the problem of uneven chip pressure in the prior art, and improves the quality and yield rate of nanosilver sintering in the process of semiconductor device manufacturing. In the present application, chips of different sizes and stress requirements can be processed on the same substrate 52, which enhances the applicability and flexibility of the equipment. The integrated design of the heating component 70 and the cooling component 80 not only speeds up the temperature regulation speed and improves the production efficiency, but also ensures the precise control of the temperature during the sintering process, further ensuring the product quality. In addition, the design of the closed cavity cooperates with the vacuum or nitrogen filling function to effectively isolate the outside air, realize the effective creation and maintenance of an oxygen-free environment during the sintering process, ensure that the quality of nanosilver sintering is not affected by oxygen in the air, and prevent the occurrence of oxidation during the sintering process, thereby improving the conductivity and thermal stability of the sintered layer, and ensuring the high quality of the sintering interface.

[0059] In this application, by designing a cooling circuit structure, the temperature can be quickly reduced, and the entire equipment can be quickly changed, which improves the production efficiency and quality of the product. In addition, in this application, preheating, sintering, and cooling are three-in-one, and the only thing that needs to be done is to load the material at the entrance and take the material out at the exit. The intermediate process is fully automatic, which greatly saves the workload of manual labor and makes the quality more uniform.

[0060] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low-temperature and high-pressure nano-silver sintering device, comprising a frame (10), an upper mold (20) and a lower mold (30) being arranged on the frame (10) in a relative manner, and a driving member (40) for driving the lower mold (30) to move up and down is arranged below the lower mold (30); It is characterized in that The upper die (20) is provided with a multi-modal pressing head assembly (50) facing the lower die (30), and the multi-modal pressing head assembly (50) comprises a plurality of pressing blocks (51) and a hydraulic cylinder capable of individually controlling each pressing block (51); The lower mold (30) is provided with a heating platform (60), the heating platform (60) is provided with a fixture (140), the fixture (140) is detachably provided with an upper cover plate (130), and a closed cavity for placing a semiconductor device to be sintered can be formed between the fixture (140) and the upper cover plate (130); The heating platform (60) and the multi-modal press head assembly (50) are both provided with a heating assembly (70) and a cooling assembly (80).

2. The low-temperature and high-pressure nanosilver sintering equipment according to claim 1, characterized in that: The clamp (140) is provided with an air channel (90) for evacuating the sealed chamber or a nitrogen channel (100) for supplying nitrogen into the sealed chamber; the sealed chamber is provided with a vacuum gauge for measuring the vacuum degree in the sealed chamber and an oxygen analyzer for measuring the oxygen content in the sealed chamber; the air channel (90) is connected to a vacuum pump, and the nitrogen channel (100) is connected to an air pump.

3. The low-temperature and high-pressure nanosilver sintering equipment according to claim 1 or 2, characterized in that: The heating component (70) on the heating platform (60) comprises a heating rod (71) arranged inside the heating platform (60), and the cooling component (80) on the heating platform (60) comprises a water flow channel (81) located inside the heating platform (60); The multimodal press head assembly (50) further comprises a base plate (52), the press block (51) slides through the base plate (52), a heating plate and a cooling plate are sequentially arranged on a side of the base plate (52) away from the lower mold (30), the heating assembly (70) in the multimodal press head assembly (50) comprises a heating rod (71) arranged in the heating plate, and the cooling assembly (80) in the multimodal press head assembly (50) comprises a water flow channel (81) located in the cooling plate; The water flow channel (81) is connected to a water valve system (110); a thermometer (230) is also provided in the heating platform (60) and the heating plate.

4. The low-temperature and high-pressure nanosilver sintering equipment according to claim 3, characterized in that: The heating rod (71) is an electric heating rod (71), and there are a plurality of heating rods (71) which are embedded at intervals along the width direction of the heating platform (60) and the heating plate.

5. The low-temperature and high-pressure nano-silver sintering equipment according to claim 1 or 2, characterized in that: The driving member (40) is a gas-liquid booster cylinder or a servo electric cylinder; a guide rod (120) is arranged on the frame (10), the lower mold (30) is slidably arranged on the guide rod (120), and the output shaft of the driving member (40) is arranged vertically upward and connected to the middle position of the bottom of the lower mold (30).

6. The low-temperature and high-pressure nanosilver sintering equipment according to claim 1 or 2, characterized in that: A high temperature resistant sealing ring is also provided between the clamp (140) and the upper cover plate (130); and a through hole (131) corresponding to the pressing block (51) is provided on the upper cover plate (130).

7. The low-temperature and high-pressure nanosilver sintering equipment according to claim 1 or 2, characterized in that: The outer cover of the frame (10) is provided with a chassis (150), the upper mold (20) and the lower mold (30) are both located in the chassis (150), a door (151) that can be opened and closed is provided on one side of the chassis (150), and transparent windows (152) are provided on multiple side surfaces of the chassis (150) and on the door (151); an air inlet (153) is provided on one side of the chassis (150), and an air suction port (154) is provided on the top of the chassis (150).

8. The low-temperature and high-pressure nanosilver sintering equipment according to claim 7, characterized in that: The low-temperature and high-pressure nano-silver sintering equipment further comprises a control box (160), the control box (160) being connected to one side of the chassis (150), the control box (160) being provided with a display screen (161) and control buttons (162); the chassis (150) is also provided with an electronic barometer (170), a hydraulic instrument (180) and a temperature control instrument (190); and a warning light (200) is also provided on the top of the chassis (150).

9. A low-temperature and high-pressure nano-silver sintering process, using the low-temperature and high-pressure nano-silver sintering equipment according to any one of claims 1 to 8 to carry out nano-silver sintering, the nano-silver sintering process comprising the following steps: S1. The AMB substrate after the patch is placed in the fixture (140), and the upper cover plate (130) is placed on the fixture (140). The fixture (140) and the upper cover plate (130) are sealed and connected to form a closed cavity between the two, so that the semiconductor device to be sintered is located in the closed cavity; S2. The fixture (140) is placed on the heating platform (60), and the sensor senses that the fixture (140) is in place; S3. Start the vacuum pump to evacuate the sealed cavity so that the sealed cavity reaches a predetermined vacuum degree; or fill the sealed cavity with nitrogen so that the sealed cavity is filled with inert gas, start the driving member (40) to drive the heating platform (60) and the clamp (140) to rise to the position, and the lower mold (30) and the upper mold (20) and the multi-modal pressure head assembly (50) are molded; S4. By opening the reversing valve of the precision hydraulic system (220) to supply oil to the hydraulic cylinder of the multi-modal pressure head assembly (50), the oil pressure is accurately controlled, and multiple different oil pressures are controlled according to actual conditions, thereby driving the telescopic rod inside the multi-modal pressure head assembly (50) to extend, and the pressure blocks (51) on the telescopic rods respectively press the corresponding chips; S5. The heating platform (60) and the pressing block (51) in the multi-modal pressing head assembly (50) are heated and heated respectively, and after reaching the set temperature, the pressure and temperature are maintained for a predetermined time; S6. The multi-modal pressure head assembly (50) and the heating platform (60) stop heating, and the water valve system (110) supplies cooling water to the cooling assembly (80), thereby cooling the multi-modal pressure head assembly (50) and the heating platform (60); S7. After the temperature drops to a predetermined temperature, the water valve system (110) stops passing water, stops vacuuming or filling with nitrogen, and the drive member (40) drives the heating platform (60) and the product fixture (140) to descend; S8. Remove the fixture (140), open the upper cover (130), remove the sintered semiconductor device product, and sintering is completed.

10. The low-temperature and high-pressure nanosilver sintering process according to claim 9, characterized in that: During the pressure and temperature holding process in the above step S5, the oil pump pressure and the servo proportional valve PID control the oil pressure, and the upper and lower mold temperatures and their respective PT100 sensor PID control the temperatures.

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