Multi-station efficient seed crystal bonding furnace

Abstract

The utility model discloses a multi-station efficient seed crystal bonding furnace which comprises a furnace body, a side wall heat preservation cylinder, a bottom heat preservation layer, a temperature regulator, a vapor chamber, a heating control unit and a pressure air bag, and the furnace body comprises an upper half furnace body, a lower half furnace body and a lifting driving device capable of driving the upper half furnace body to lift up and down relative to the lower half furnace body. An inflation inlet is formed in the center of the top of the upper half furnace body, and a vacuumizing opening and an air inlet are formed in the lower half furnace body. The upper half furnace body covers an opening in the upper end of the lower half furnace body to enable the upper cavity and the lower cavity to form a vacuum cavity, the side wall heat preservation barrel is arranged on the inner wall of the lower half furnace body, the bottom heat preservation layer is arranged at the bottom of the lower half furnace body, the temperature regulator is installed on the bottom heat preservation layer, the vapor chamber is installed on the temperature regulator, and a plurality of positioning grooves are formed in the vapor chamber. The pressure air bag is installed on the top of the upper half furnace body and covers the positioning grooves, and an air inlet pipe of the pressure air bag is arranged in the center of the top of the pressure air bag and located in the inflation opening.

Description

Technical Field

[0001] The utility model relates to the technical field of silicon carbide single crystal furnaces, in particular to a multi-station high-efficiency seed crystal bonding furnace. Background Art

[0002] In the efficient and fast-paced information society, high temperature, high pressure, high frequency and high power have become a threshold that we must overcome in our development. As the representative of the third-generation wide-bandgap semiconductor materials, silicon carbide, due to its material structural characteristics, can almost perfectly match the above advantages in application. Especially in recent years, the emerging new energy market has initially witnessed its highlight moment.

[0003] Since silicon carbide does not exist in a stoichiometric melt at room temperature and pressure, it cannot be prepared and produced using a mature and efficient Czochralski method. At present, the most commonly used and mature method for preparing silicon carbide single crystals at home and abroad is the physical vapor transport (PVT) method. It is under the protection of high-purity dynamic inert gas, in a suitable temperature field established by induction heating or graphite resistance heating, after the high-purity silicon carbide powder is decomposed and sublimated in the high-temperature source material area of ​​the growth cavity, it is transported to the low-temperature seed crystal guide area under the action of the thermal field temperature gradient and the material gas phase concentration gradient, and rearranged in an atomic-level regular manner in the low-temperature seed crystal guide area and crystallized and grown.

[0004] In addition to the selection of high-quality, low-defect wafers, the connection and placement of the top-guided seed crystal and the top cavity has also become an important factor in determining the success or failure of the process. Commonly used methods for bonding wafers of the same diameter are: 1. Directly bond the seed crystal to the graphite tray under the action of high-temperature glue. Even if a graphite cover with a similar thermal expansion coefficient is directly bonded to the wafer, it is difficult to achieve a good bonding effect due to the deviation in the processing of the wafer and the graphite tray; 2. Use flexible graphite paper to bond the seed crystal to the graphite tray twice. This two-time bonding method is cumbersome and complicated, and consumes a lot of time and energy.

[0005] For example, a utility model patent with authorization announcement number CN204530015 U and authorization announcement date August 5, 2015 discloses a sintering seed crystal crimping device, which uses an air bag to evenly disperse the contact, and then uses multiple pressure blocks above to adjust the pressure on the seed crystal. The operation is very cumbersome and laborious, and the air bag is prone to rupture during operation due to the lack of spatial positioning restrictions, which can easily cause exhaust obstruction during the subsequent seed crystal hot pressing process.

[0006] For example, a utility model patent with authorization announcement number CN210683993U and authorization announcement date June 5, 2020 discloses a three-station silicon carbide seed crystal bonding furnace for reducing crystal growth holes. It uses a cylinder to hard-press and bond the workpieces on three independent upper and lower heating plates between the upper and lower pressure plates. Although the upper pressure unit adopts a two-stage spherical active connection structure, the pressure is not easy to control, and the processing deviation of the seed crystal and the graphite support or the matching deviation between the two will also have a great impact on the bonding effect. At the same time, the plane hard pressing has very high requirements on the height of the three groups of workpieces, and it is difficult to achieve a good bonding effect. Utility Model Content

[0007] The problem to be solved by the utility model is to provide a multi-station high-efficiency seed crystal bonding furnace, which is easy to operate and can simultaneously perform high-efficiency and dense hot-press bonding on multiple graphite trays and seed crystal sheets, with good bonding effect.

[0008] In order to solve the above technical problems, the technical solutions adopted by the utility model are as follows:

[0009] A multi-station high-efficiency seed crystal bonding furnace comprises a furnace body, characterized in that it also comprises a side wall insulation tube, a bottom insulation layer, a temperature regulator, a heat soaking plate, a heating control unit and a pressure airbag, the furnace body comprises an upper furnace body, a lower furnace body and a lifting drive device capable of driving the upper furnace body to rise and fall relative to the lower furnace body, the upper furnace body is provided with an upper cavity, the lower furnace body is provided with a lower cavity, an air charging port is provided at the top center of the upper furnace body, and a vacuum port and an air inlet are provided on the lower furnace body; the upper furnace body covers the upper end opening of the lower furnace body so that The upper cavity and the lower cavity form a vacuum cavity, the side wall insulation tube is arranged on the inner wall of the lower furnace body, the bottom insulation layer is arranged on the bottom of the lower furnace body, the temperature regulator is installed on the bottom insulation layer, and the heating control unit is arranged on the outside of the furnace body and is electrically connected to the temperature regulator; the heat spreader is installed on the temperature regulator, and a plurality of positioning grooves are arranged on the heat spreader, the pressure airbag is installed on the top of the upper furnace body and covers the top of each positioning groove, the air inlet pipe of the pressure airbag is arranged at the center of the top of the pressure airbag, and the air inlet pipe of the pressure airbag is in the inflation port.

[0010] Typically, the workpieces placed on the above-mentioned heat spreader are a graphite tray, graphite paper and a seed wafer placed in sequence from bottom to top.

[0011] Typically, the above-mentioned multi-station high-efficiency seed crystal bonding furnace is also equipped with a vacuum pump, an inflation device and an inert gas adding device. The vacuum pump's exhaust port is connected to the vacuum exhaust port on the lower half of the furnace body, the inflation device's exhaust port is connected to the air inlet pipe of the pressure airbag, and the inert gas adding device's exhaust port is connected to the air inlet on the lower half of the furnace body.

[0012] Usually, the lifting drive device can be a cylinder, the piston rod of the cylinder is arranged downward, and the top of the upper furnace body is connected to the end of the piston rod of the cylinder. The lifting drive device can also be a motor, a driving sprocket, a driven sprocket and a transmission chain.

[0013] During operation, the upper furnace body is opened through the lifting drive device to expose the various positioning grooves in the lower furnace body, and the various workpieces are placed in the corresponding positioning grooves for positioning and fixing; the upper furnace body is then lowered by the lifting drive device to cover the upper end opening of the lower furnace body and form a vacuum chamber, and at the same time, the external inflation device is turned on to inflate the pressure airbag on the top of the upper furnace body through the air inlet pipe, so that the bottom surface of the pressure airbag dynamically and gradually covers the workpiece below from the center to the surroundings and applies pressure slowly, which will not have a big impact on the graphite tray or wafer crimping with large processing errors, making it easy to lift and lower. The volatile gas in the heating process is prevented from escaping; the external vacuum pump is turned on to evacuate and degas the entire vacuum chamber and to exchange air during the gas protection process, and the inert gas adding device is turned on to introduce inert gas into the vacuum chamber through the air inlet on the lower half of the furnace body; the temperature of the temperature regulator is adjusted by the heating control unit, and then the temperature is transferred to the workpiece on the heat spreader through the temperature regulator, which can ensure that the heat transferred by the temperature regulator is uniform and consistent, and the pressure of the pressure airbag can be evenly dispersed. In the vacuum environment and under the protection of inert gas, multiple graphite trays and seed wafers are hot-pressed and bonded.

[0014] In the preferred embodiment, the effective crimping outer diameter of the pressure airbag is larger than the outer diameter surrounded by each positioning groove. This arrangement ensures that the pressure airbag can completely cover each positioning groove, thereby ensuring that each workpiece can be subjected to uniform pressure, thereby improving the quality and efficiency of bonding.

[0015] In the preferred embodiment, a crimping limit ring is provided on the inner wall of the lower half furnace body, and the outer edge of the bottom surface of the pressure airbag is engaged with the crimping limit ring. This arrangement can limit the position of the outer edge of the bottom surface of the pressure airbag, thereby ensuring that the pressure airbag can accurately crimp the workpiece below, avoiding displacement or deformation of the pressure airbag during the crimping process, and improving the accuracy and stability of crimping.

[0016] In a preferred embodiment, the positioning grooves are evenly placed on the heat spreader in a circumferential radial manner. This arrangement enables each workpiece to be evenly distributed on the heat spreader, thereby ensuring that each workpiece can receive even heat, thereby improving the efficiency and uniformity of heating.

[0017] In the preferred embodiment, a pressure regulating valve is provided at the air inlet pipe. Under the control of the pressure regulating valve, the pressure airbag can be continuously filled with compressed air in the range of 0atm-8atm, thereby applying an adjustable uniform pressure to the workpiece on the bottom of the pressure airbag, facilitating the escape of volatile gas during hot pressing, so that the differential graphite tray and the wafer can be densely bonded.

[0018] In the preferred embodiment, the vacuum port is arranged on the side wall of the lower furnace body, and the air inlet is arranged on the bottom of the lower furnace body. Of course, the vacuum port and the air inlet can be arranged on the side wall of the lower furnace body or on the bottom of the lower furnace body, but the vacuum port and the air inlet are arranged at both ends of the effective circulation path of the airflow in the lower furnace body, so that the system can operate reliably under the protection of vacuum and inert gas.

[0019] In a preferred embodiment, at least two guide posts are provided on the lower furnace body, and at least two guide holes corresponding to the guide posts are provided on the upper furnace body, and the guide posts are located in the corresponding guide holes. With this arrangement, the upper furnace body can be easily positioned and lifted and opened.

[0020] In a further preferred embodiment, at least two screw holes are provided on the edge of the lower furnace body, and positioning screws are installed in the screw holes. At least two positioning through holes corresponding to the screw holes are provided on the edge of the upper furnace body, and the rod of the positioning screw passes through the positioning through holes. The head of the positioning screw and the edge of the lower furnace body together clamp the upper furnace body. By matching the positioning screw, the positioning through hole, and the screw hole, the upper furnace body can be locked and installed under the lower furnace body, and the upper furnace body and the lower furnace body can be accurately positioned.

[0021] In a preferred embodiment, the temperature regulator is a metal resistance wire heater or a graphite resistance heater. Through this arrangement, after the temperature regulator is connected to an external heating control unit, the temperature of the workpiece on the workpiece can be controlled to increase or decrease in temperature through the temperature regulator.

[0022] In the preferred embodiment, the lower furnace body includes a middle sleeve and a furnace bottom plate, the lower end opening of the middle sleeve is tightly connected to the edge of the furnace bottom plate, the side wall insulation tube is arranged on the inner wall of the middle sleeve, and the bottom insulation layer is laid flat on the furnace bottom plate. Through this arrangement, the lower furnace body is divided into two parts, so that the entire furnace body is composed of the upper furnace body, the middle sleeve, and the furnace bottom plate, which is convenient for the later disassembly and maintenance of the entire furnace body.

[0023] Compared with the prior art, the utility model has the following advantages:

[0024] (1) The utility model has a simple structure and low cost. It can simultaneously perform efficient and dense hot-pressing bonding on multiple graphite trays and seed wafers, and can avoid the risk of easy falling off caused by thickness deviation, thereby ensuring the smooth progress of the entire hot-pressing bonding process.

[0025] (2) The cooperation between the positioning grooves and the pressure airbags of the utility model can not only fix and accurately position multiple groups of multi-layer workpieces to prevent uneven force deviation during the heating, exhaust and pressure airbag progressive crimping process, but also limit the volume of the upper airbag to prevent it from over-expanding and rupturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a specific embodiment of the utility model;

[0027] Figure 2 It is a three-dimensional diagram of a multi-station high-efficiency seed crystal bonding furnace in a specific embodiment of the utility model;

[0028] Figure 3 It is a schematic diagram of placing workpieces in a specific embodiment of the utility model. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1-3 As shown, the multi-station high-efficiency seed crystal bonding furnace in this embodiment includes a furnace body 1, a side wall insulation tube 2, a bottom insulation layer 3, a temperature regulator 4, a heat plate 5, a heating control unit (not shown in the figure) and a pressure airbag 6. The furnace body 1 includes an upper furnace body 11, a lower furnace body 12 and a lifting drive device 7 that can drive the upper furnace body 11 to move up and down relative to the lower furnace body 12. The upper furnace body 11 is provided with an upper cavity 111, and the lower furnace body 12 is provided with a lower cavity 121. An air charging port 112 is provided at the top center of the upper furnace body 11, and a vacuum port 122 and an air inlet 123 are provided on the lower furnace body 12; the upper furnace body 11 covers the upper part of the lower furnace body 12. The upper cavity 111 and the lower cavity 121 form a vacuum chamber 124 at the end opening, the side wall insulation tube 2 is arranged on the inner wall of the lower furnace body 12, the bottom insulation layer 3 is arranged at the bottom of the lower furnace body 12, the temperature regulator 4 is installed on the bottom insulation layer 3, the heating control unit is arranged on the outside of the furnace body 1 and is electrically connected to the temperature regulator 4; the heat spreader 5 is installed on the temperature regulator 4, and a plurality of positioning grooves 51 are provided on the heat spreader 5, the pressure airbag 6 is installed on the top of the upper furnace body 11 and covers the top of each positioning groove 51, the air inlet pipe 61 of the pressure airbag 6 is arranged at the center of the top of the pressure airbag 6, and the air inlet pipe 61 of the pressure airbag 6 is in the inflation port 112.

[0031] Typically, the workpiece 8 placed on the above-mentioned heat spreader 5 is a graphite holder 81, a graphite paper 82 and a seed wafer 83 placed in sequence from bottom to top.

[0032] Typically, the above-mentioned multi-station high-efficiency seed crystal bonding furnace is also externally provided with a vacuum pump, an inflation device and an inert gas adding device. The vacuum pump's exhaust port is connected to the vacuum exhaust port 122 on the lower furnace body 12, the exhaust port of the inflation device is connected to the air inlet pipe 61 of the pressure airbag 6, and the exhaust port of the inert gas adding device is connected to the air inlet 123 on the lower furnace body 12.

[0033] During operation, the upper furnace body 11 is opened by the lifting drive device 7 to expose the positioning grooves 51 in the lower furnace body 12, and the workpieces 8 are placed in the corresponding positioning grooves 51 for positioning and fixing; the upper furnace body 11 is then lowered by the lifting drive device 7 to cover the upper end opening of the lower furnace body 12 and form a vacuum chamber 124, and at the same time, the external inflation device is turned on to inflate the pressure airbag 6 on the top of the upper furnace body 11 through the air inlet pipe 61, so that the bottom surface of the pressure airbag 6 is dynamically and gradually covered from the center to the surroundings to flexibly and fully cover the workpieces 8 below and apply pressure slowly, which will not have a significant impact on the graphite tray 81 or wafer crimping with large processing errors. It is convenient for volatile gases to escape during the heating process; then the external vacuum pump is turned on to evacuate and degas the entire vacuum chamber 124 and ventilate during the gas protection process, and the inert gas adding device is turned on to introduce inert gas into the vacuum chamber 124 through the air inlet 123 on the lower half of the furnace body 12; the temperature of the temperature regulator 4 is adjusted by the heating control unit, and then the temperature is transferred to the workpiece 8 on the heat plate 5 through the temperature regulator 4, which can not only ensure that the heat transferred by the temperature regulator 4 is uniform, but also uniformly disperse the pressure of the pressure airbag 6, and in the vacuum environment and under the protection of the inert gas, a plurality of graphite trays 81 and seed wafers 83 are hot-pressed and bonded.

[0034] The effective crimping outer diameter of the pressure airbag 6 is larger than the outer diameter surrounded by each positioning groove 51. This arrangement ensures that the pressure airbag 6 can completely cover each positioning groove 51, thereby ensuring that each workpiece 8 can be subjected to uniform pressure, thereby improving the quality and efficiency of bonding.

[0035] A plurality of crimping limit convex points 125 are arranged on the inner wall of the lower furnace body 12, and each crimping limit convex point 125 is distributed in a ring shape, and the outer edge of the bottom surface of the pressure airbag 6 is engaged with the crimping limit convex point 125. Through this arrangement, the position of the outer edge of the bottom surface of the pressure airbag 6 can be limited, thereby ensuring that the pressure airbag 6 can accurately crimp the workpiece 8 below, avoiding the pressure airbag 6 from deflecting or deforming during the crimping process, and improving the accuracy and stability of the crimping.

[0036] The positioning grooves 51 are evenly placed in a circumferential radial direction on the heat soaking plate 5. Through this arrangement, the workpieces 8 can be evenly distributed on the heat soaking plate 5, thereby ensuring that each workpiece 8 can receive uniform heat, thereby improving the efficiency and uniformity of heating.

[0037] A pressure regulating valve 62 is provided at the air inlet pipe 61. Under the control of the pressure regulating valve 62, compressed air in the range of 0atm-8atm can be continuously filled into the pressure airbag 6, so as to apply an adjustable uniform pressure to the workpiece 8 on the bottom surface of the pressure airbag 6, which is convenient for the escape of volatile gas during the hot pressing process, so that the differential graphite holder 81 and the wafer can be densely bonded.

[0038] The vacuum port 122 is arranged on the side wall of the lower furnace body 12, and the air inlet 123 is arranged on the bottom of the lower furnace body 12. Of course, the vacuum port 122 and the air inlet 123 can be arranged on the side wall of the lower furnace body 12, or on the bottom of the lower furnace body 12, but the vacuum port 122 and the air inlet 123 are distributed at both ends of the effective circulation path of the airflow in the lower furnace body 12, and the system can operate reliably under the protection of vacuum and inert gas.

[0039] The lower furnace body 12 is provided with at least two guide posts 126, and the upper furnace body 11 is provided with at least two guide holes 113 corresponding to the guide posts 126, and the guide posts 126 are located in the corresponding guide holes 113. With this arrangement, the upper furnace body 11 can be easily positioned and lifted and opened.

[0040] At least two screw holes 127 are provided on the edge of the lower furnace body 12, and positioning screws 128 are installed in the screw holes 127. At least two positioning through holes 114 corresponding to the screw holes 127 are provided on the edge of the upper furnace body 11, and the rod of the positioning screw 128 passes through the positioning through holes 114. The head of the positioning screw 128 and the edge of the lower furnace body 12 jointly clamp the upper furnace body 11. By matching the positioning screws 128, the positioning through holes 114, and the screw holes 127, the upper furnace body 11 can be locked and installed under the lower furnace body 12, and the upper furnace body 11 and the lower furnace body 12 can be accurately positioned.

[0041] The temperature regulator 4 is a metal resistance wire heater. Through this arrangement, after the temperature regulator 4 is connected to an external heating control unit, the temperature regulator 4 can be used to controllably increase or decrease the temperature of the workpiece 8 thereon.

[0042] The lower furnace body 12 includes a middle sleeve 13 and a furnace bottom plate 14. The lower end opening of the middle sleeve 13 is tightly connected to the edge of the furnace bottom plate 14. The side wall insulation tube 2 is arranged on the inner wall of the middle sleeve 13, and the bottom insulation layer 3 is laid flat on the furnace bottom plate 14. Through this arrangement, the lower furnace body 12 is divided into two parts, so that the entire furnace body 1 is composed of the upper furnace body 11, the middle sleeve 13, and the furnace bottom plate 14, which is convenient for the disassembly and maintenance of the entire furnace body 1 in the later stage.

[0043] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different, and any equivalent or simple changes made based on the structure, features and principles described in the utility model patent concept are included in the protection scope of the utility model patent. The technical personnel of the technical field to which the utility model belongs can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the protection scope of the utility model.

Claims

1. A multi-station high-efficiency seed crystal bonding furnace, comprising a furnace body, characterized in that: The furnace body also includes a side wall insulation tube, a bottom insulation layer, a temperature regulator, a heat soaking plate, a heating control unit and a pressure airbag. The furnace body includes an upper furnace body, a lower furnace body and a lifting drive device capable of driving the upper furnace body to rise and fall relative to the lower furnace body. The upper furnace body is provided with an upper cavity, the lower furnace body is provided with a lower cavity, an air filling port is provided at the top center of the upper furnace body, and a vacuum port and an air inlet are provided on the lower furnace body; the upper furnace body covers the upper end opening of the lower furnace body so that the upper cavity and the lower cavity form a vacuum cavity, the side wall insulation tube is arranged on the inner wall of the lower furnace body, the bottom insulation layer is arranged at the bottom of the lower furnace body, the temperature regulator is arranged on the bottom insulation layer, the heating control unit is arranged on the outside of the furnace body and is electrically connected to the temperature regulator; the heat soaking plate is arranged on the temperature regulator, a plurality of positioning grooves are arranged on the heat soaking plate, the pressure airbag is arranged on the top of the upper furnace body and covers the top of each positioning groove, the air inlet pipe of the pressure airbag is arranged at the center of the top of the pressure airbag, and the air inlet pipe of the pressure airbag is in the air filling port.

2. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: The effective crimping outer diameter of the pressure airbag is larger than the outer diameter surrounded by each of the positioning grooves.

3. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: A crimping limit ring is arranged on the inner wall of the lower half furnace body, and the outer edge of the bottom surface of the pressure airbag is snap-fitted with the crimping limit ring.

4. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: Each of the positioning grooves is evenly placed on the heat spreader in a circumferential radial manner.

5. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: A pressure regulating valve is arranged at the air inlet pipe.

6. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: The vacuum port is arranged on the side wall of the lower furnace body, and the air inlet is arranged on the bottom of the lower furnace body.

7. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: The lower half furnace body is provided with at least two guide posts, and the upper half furnace body is provided with at least two guide holes corresponding to the guide posts, and the guide posts are located in the corresponding guide holes.

8. The multi-station high-efficiency seed crystal bonding furnace according to claim 7, characterized in that: The edge of the lower furnace body is provided with at least two screw holes, in which positioning screws are installed, and the edge of the upper furnace body is provided with at least two positioning through holes corresponding to the screw holes, the rod of the positioning screw passes through the positioning through holes, and the head of the positioning screw and the edge of the lower furnace body jointly clamp the upper furnace body.

9. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: The temperature regulator is a metal resistance wire heater or a graphite resistance heater.

10. The multi-station high-efficiency seed crystal bonding furnace according to claim 1, characterized in that: The lower half furnace body comprises a middle sleeve and a furnace bottom plate, the lower end opening of the middle sleeve is tightly connected to the edge of the furnace bottom plate, the side wall insulation tube is arranged on the inner wall of the middle sleeve, and the bottom insulation layer is laid flat on the furnace bottom plate.

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