A solid state transformer wafer passivation device and method of use thereof

Abstract

This invention belongs to the field of wafer processing technology, and specifically relates to a passivation device for solid-state transformer wafers and its usage method. It includes a lower semi-circular outer shell, an upper semi-circular outer shell, and a controller. Semi-annular heaters are installed on the inner walls of both the lower and upper semi-circular outer shells. A driving assembly for moving the upper semi-circular outer shell is installed on the lower semi-circular outer shell. The device also includes several sets of gas injection pipes, coaxially arranged between the lower and upper semi-circular outer shells. Each gas injection pipe is fixedly connected to a gas injection cylinder, and the gas injection cylinder is fixedly connected to a first connecting pipe. A sealed gas supply pipe is fixedly inserted into the end of the upper semi-circular outer shell, and the first connecting pipe is connected to the gas supply pipe. This invention can ensure uniform oxide layer thickness on the wafer surface, reduce interface defects, improve the stability and reliability of the passivation layer, and is suitable for use in solid-state transformer wafer processing. It also efficiently recovers and utilizes thermal energy, reducing energy waste.

Description

Technical Field

[0001] This invention belongs to the field of wafer processing technology, and in particular relates to a solid-state transformer wafer passivation device and its usage method. Background Technology

[0002] Solid-state transformers use SiC power wafers that operate under high voltage and high frequency conditions. Electric field concentration and leakage breakdown are prone to occur on the wafer surface. By forming a dense insulating protective layer through surface passivation treatment, edge electric field distortion can be suppressed, moisture and impurities can be blocked from entering, the withstand voltage and high temperature stability of the device can be improved, and the long-term reliable operation of solid-state transformers can be guaranteed.

[0003] Ordinary silicon wafers are passivated by directly depositing silicon nitride thin films using PECVD for basic insulation protection. However, the SiC power wafers used in solid-state transformers operate under extreme conditions of high voltage, high temperature, and high frequency, and the requirements for the passivation layer are much higher than those for ordinary silicon wafers. Before PECVD passivation, a dense SiO2 oxide layer must be grown through high-temperature thermal oxidation. This makes the wafer interface more tightly bonded, with very few defects and low interface states, which makes it more stable under the high voltage and high temperature of solid-state transformers and prevents leakage and breakdown. During high-temperature thermal oxidation, wafers are typically placed inside a quartz furnace tube. In a high-temperature, dry oxygen environment, the wafers undergo initial passivation through surface thermal oxidation. The heating device in the quartz furnace tube is usually installed in a ring on the outside of the tube. This results in stronger radiation heating and higher temperatures at the wafer edges, while the temperature at the wafer center remains relatively low. Consequently, the oxide layer thickness is thinner at the center and thicker at the edges, leading to poor uniformity. This is detrimental to the reliable operation of solid-state transformer wafers under high voltage and high temperature. Furthermore, since oxygen enters from one end of the furnace tube and exits from the other, there is a significant oxygen concentration gradient along the airflow direction. The oxygen content is sufficient at the front end, while the oxygen at the back end is continuously consumed, accompanied by the retention of reaction waste gas. This further exacerbates the unevenness of the oxide layer thickness and interface quality across the entire batch of wafers, making it difficult to meet the requirements of high uniformity and high stability of the passivation layer for solid-state transformer wafers. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a solid-state transformer wafer passivation device and its usage method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a solid-state transformer wafer passivation device, comprising a lower semi-circular shell, an upper semi-circular shell, and a controller, wherein a semi-annular heater is installed on the inner sidewall of both the lower and upper semi-circular shells, and a driving assembly for driving the upper semi-circular shell to move is installed on the lower semi-circular shell, and further comprising: Several sets of air injection tubes are coaxially arranged between the lower semicircular outer shell and the upper semicircular outer shell. Each air injection tube is fixedly connected to an air injection cylinder, and the air injection cylinder is fixedly connected to a first connecting tube. A sealed air supply tube is fixedly inserted into the end of the upper semicircular outer shell, and the first connecting tube is connected to the air supply tube. Several sets of symmetrically arranged disc baffles are coaxially arranged between the lower semicircular outer shell and the upper semicircular outer shell, and the sidewalls of the disc baffles are fixedly inserted into the corresponding air injection pipes. An edge exhaust unit is disposed between the lower semicircular outer shell and the upper semicircular outer shell, and the edge exhaust unit is used to exhaust the airflow discharged from the disc baffle. The heat exchange unit is installed at the end of the upper semi-circular outer shell, and the edge exhaust unit and the air supply pipe are both connected to the interior of the heat exchange unit; Two arc-shaped positioning strips are set on both sides of the inner side of the lower semi-circular shell, and the arc-shaped positioning strips are fixed to the inner side wall of the semi-circular heater on the same side; The edge exhaust unit includes a circular cover fitted on the outside of the disc baffle. An exhaust pipe is fixedly inserted into the side wall of the circular cover. Both the circular cover and the exhaust pipe are coaxial with the air injection pipe. The air injection pipe is fixed at the end of the exhaust pipe, and the air injection pipe passes through the exhaust pipe and communicates with the air injection pipe.

[0006] Preferably, the drive assembly includes a support block fixed to the end of the lower semi-circular outer shell, an electric push rod fixed to the top of the support block, a lifting block fixed to the end of the upper semi-circular outer shell, and the movable end of the electric push rod is fixedly connected to the lifting block. The electric push rod is electrically connected to the controller.

[0007] Preferably, the edge exhaust unit further includes an exhaust pipe fixedly inserted into the end of the upper semi-circular outer shell, and one end of the exhaust pipe is sealed. A second connecting pipe is fixedly inserted into the side wall of the exhaust cylinder, and the second connecting pipe is connected to the exhaust pipe.

[0008] Preferably, the heat exchange unit includes a heat insulation box fixed to the end of the upper semi-circular outer shell. Two partitions are fixed inside the heat insulation box. The inlet end of the air supply pipe is located between the two partitions, and the outlet end of the exhaust pipe is located outside the two partitions. An oxygen supply pipe and a nitrogen supply pipe are fixedly inserted into the side wall of the heat insulation box located between the two partitions. A tailpipe is fixedly inserted into the side wall of the heat insulation box away from the exhaust pipe. Several evenly distributed heat exchange tubes are fixedly inserted between the two partitions.

[0009] Preferably, a diverter pipe is fixedly inserted into the wall of the nitrogen supply pipe, and the diverter pipe is connected to the interior of the upper semi-circular shell. An outlet pipe is fixedly inserted into the end of the lower semi-circular shell away from the diverter pipe. A first control valve is installed inside the outlet pipe and the diverter pipe. A second control valve is installed inside the outlet end of the nitrogen supply pipe and the tail gas pipe. A third control valve is installed inside the oxygen supply pipe. The first control valve, the second control valve, and the third control valve are all electrically connected to the controller.

[0010] Preferably, a nitrogen concentration detection sensor is fixedly inserted into the wall of the outlet pipe, and the nitrogen concentration detection sensor is electrically connected to the controller.

[0011] A method of using a solid-state transformer wafer passivation device, which is applied to the solid-state transformer wafer passivation device as described above, includes the following steps: Step 1: Select a solid-state transformer wafer and clean it sequentially with acetone, anhydrous ethanol, and deionized water using ultrasonic cleaning to remove surface oil, impurities, and oxide layers. After cleaning, place it in a drying oven at 120-150℃ for 1-2 hours to obtain a clean and impurity-free wafer to be passivated. Step 2: Place the wafer to be passivated, processed in Step 1, vertically in the quartz boat and place the quartz boat inside the lower semi-circular shell. Then start the controller. The controller controls the drive assembly to close the upper and lower semi-circular shells. Then, it controls the first control valve in the gas outlet pipe and the shunt pipe to open, and controls the second control valve in the nitrogen supply pipe and the exhaust pipe to close. Then, nitrogen is supplied through the nitrogen supply pipe. When the nitrogen concentration detection sensor feeds back an electrical signal, the controller controls the first control valve to close and the second control valve to open. Step 3: The controller controls the two semi-annular heaters to operate, raising the temperature to 1150-1200℃ at a rate of 5-8℃ / min. During the heating process, nitrogen is continuously introduced through the nitrogen supply pipe. Step 4: After the temperature reaches the set value, the controller controls the second control valve in the nitrogen supply pipe to close and controls the third control valve in the oxygen supply pipe to open, and supplies oxygen through the oxygen supply pipe to carry out a thermal oxidation reaction for 2-3 hours. After the thermal oxidation reaction in step four is completed, the controller closes the third control valve in the oxygen supply pipe and stops the oxygen supply. At the same time, the controller reopens the second control valve in the nitrogen supply pipe and supplies nitrogen. Annealing is carried out at a temperature of 1150-1200℃ for 30 minutes. Then, the heating temperature of the semi-circular heater is controlled to decrease to below 100℃ at a rate of 3-5℃ / min. After the temperature is reduced, the upper and lower semi-circular shells are opened and the quartz boat is removed.

[0012] Compared with existing technologies, the advantages of a solid-state transformer wafer passivation device and its application method are as follows: By coordinating the lower semi-circular outer shell, upper semi-circular outer shell, controller, semi-annular heater, drive assembly, gas injection pipe, gas injection cylinder, first connecting pipe, gas supply pipe, and disc baffle, high-purity oxygen can be precisely delivered to the center region of the wafer via the gas injection cylinder and gas injection pipe through the center gas injection method. Then, the oxygen is uniformly diffused by the guiding effect of the disc baffle, effectively compensating for the temperature gradient between the center and edge of the wafer, improving the uneven oxide layer thickness phenomenon in traditional oxidation processes, and helping to improve the wafer passivation effect. It is suitable for use in solid-state transformer wafer processing.

[0013] By setting up an edge exhaust unit, the reaction gas flow can be quickly discharged from the outer edge of the wafer, avoiding the accumulation and retention of reaction waste gas in the wafer edge area. This eliminates the risk of carbon residue caused by long-term contact between waste gas and wafer surface at high temperature, ensuring that the passivation layer surface is as clean and free of impurities as possible. At the same time, it can stabilize the radial airflow field in the furnace, avoid uneven oxygen concentration distribution caused by airflow turbulence, and help improve the passivation quality of the wafer.

[0014] By using the heat exchange unit, the high-temperature exhaust gas can be used to preheat the oxygen, thereby improving the thermal energy utilization rate of the equipment and reducing heating energy consumption. At the same time, it avoids the temperature drop inside the upper and lower semi-circular shells caused by room-temperature oxygen, which helps to maintain the stability of the reaction zone.

[0015] By annealing at 1150-1200℃ for 30 minutes after the thermal oxidation reaction, and by directly annealing under a nitrogen atmosphere at high temperature, the dangling bonds and stress defects at the SiC / SiO2 interface can be eliminated in situ, which greatly improves the pressure resistance and long-term stability of the passivation layer. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of a solid-state transformer wafer passivation device provided by the present invention; Figure 2 This is a schematic diagram of the internal structure of the lower semicircular outer shell of a solid-state transformer wafer passivation device provided by the present invention; Figure 3 This is a schematic diagram of the internal structure of the upper semi-circular outer shell of a solid-state transformer wafer passivation device provided by the present invention; Figure 4 This is a schematic diagram of the connection structure between the disc baffle and the gas injection pipe of a solid-state transformer wafer passivation device provided by the present invention. Figure 5 This is a schematic diagram of the connection structure between the gas injection cylinder and the exhaust cylinder of a solid-state transformer wafer passivation device provided by the present invention; Figure 6This is a schematic diagram of the connection structure between the gas injection pipe and the exhaust pipe of a solid-state transformer wafer passivation device provided by the present invention; Figure 7 This is a side view of the heat insulation box of a solid-state transformer wafer passivation device provided by the present invention; Figure 8 This is a schematic diagram of the internal structure of the heat insulation box of a solid-state transformer wafer passivation device provided by the present invention; Figure 9 This is a bottom view of the heat insulation box of a solid-state transformer wafer passivation device provided by the present invention.

[0017] In the diagram: 1 Lower semicircular shell, 2 Upper semicircular shell, 3 Controller, 4 Semi-annular heater, 5 Drive assembly, 51 Support block, 52 Electric push rod, 53 Lifting block, 6 Gas injection pipe, 7 Gas injection cylinder, 8 First connecting pipe, 9 Gas supply pipe, 10 Disc baffle, 11 Edge exhaust unit, 111 Circular cover, 112 Exhaust cylinder, 113 Exhaust pipe, 114 Second connecting pipe, 12 Heat exchange unit, 121 Insulation box, 122 Partition, 123 Oxygen supply pipe, 124 Nitrogen supply pipe, 125 Tail gas pipe, 126 Heat exchange pipe, 13 Diverter pipe, 14 Gas outlet pipe, 15 First control valve, 16 Second control valve, 17 Third control valve, 18 Nitrogen concentration detection sensor, 19 Arc-shaped positioning strip. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] like Figures 1-9 As shown, a solid-state transformer wafer passivation device includes a lower semi-circular shell 1, an upper semi-circular shell 2, and a controller 3. Semi-annular heaters 4 are installed on the inner walls of both the lower and upper semi-circular shells 1 and 2. A drive assembly 5 for moving the upper semi-circular shell 2 is installed on the lower semi-circular shell 1. The drive assembly 5 includes a support block 51 fixed to the end of the lower semi-circular shell 1, an electric push rod 52 fixed to the top of the support block 51, and a lifting block 53 fixed to the end of the upper semi-circular shell 2. The movable end of the electric push rod 52 is fixedly connected to the lifting block 53. The electric push rod 52 and the controller 3... The controller 3 is electrically connected, wherein the mating surface between the lower semicircular outer shell 1 and the upper semicircular outer shell 2 is provided with a high-temperature resistant sealing structure, such as a ceramic fiber sealing gasket or a flexible graphite metal reinforced sealing ring. Four sets of thermocouples are symmetrically arranged on the inner wall of the semi-annular heater 4. The thermocouples are close to the inner wall of the semi-annular heater 4 and horizontally aligned with the edge of the wafer. Each set of thermocouples is evenly distributed within a 180° range about the central axis of the wafer. There are four thermocouples in each set. The controller 3 collects thermocouple data through PID closed-loop logic and automatically adjusts the power of the semi-annular heater 4 when the temperature deviation exceeds ±5℃.

[0020] The device further includes: several sets of air injection pipes 6, which are coaxially arranged between the lower semicircular outer shell 1 and the upper semicircular outer shell 2. Each air injection pipe 6 is fixedly connected to an air injection cylinder 7, and the air injection cylinder 7 is fixedly connected to a first connecting pipe 8. An air supply pipe 9 with one end sealed is fixedly inserted into the end of the upper semicircular outer shell 2, and the first connecting pipe 8 is connected to the air supply pipe 9. Several sets of symmetrically arranged disc baffles 10 are coaxially arranged between the lower semicircular outer shell 1 and the upper semicircular outer shell 2. The side wall of the disc baffle 10 is fixedly inserted into the corresponding air injection pipe 6. An edge exhaust unit 11 is arranged between the lower semicircular outer shell 1 and the upper semicircular outer shell 2, and the edge exhaust unit 11 is used to exhaust the airflow discharged from the disc baffle 10. The edge exhaust unit 11 includes a circular cover 111 sleeved on the outside of the disc baffle 10. An exhaust cylinder 112 is fixedly inserted into the side wall of the circular cover 111. The circular cover 111 and the exhaust cylinder 112 are coaxial with the air injection pipe 6. The air injection cylinder 7 is fixed to the upper semicircular outer shell 2. The exhaust pipe 112 has an air injection pipe 6 that passes through it and connects to the air injection cylinder 7. An exhaust pipe 113 with a sealed end is fixedly inserted into the end of the upper semi-circular outer shell 2. A second connecting pipe 114 is fixedly inserted into the side wall of the exhaust pipe 112 and connects to the exhaust pipe 113. The air injection pipe 6, air injection cylinder 7, first connecting pipe 8, air supply pipe 9, circular cover 111, exhaust pipe 112, exhaust pipe 113, and second connecting pipe 114 are all... Made of high-temperature resistant materials, such as high-temperature resistant ceramics and 310S stainless steel, the gas injection pipe 6 is a circular pipe with an inner diameter of 8mm. The end face of the gas injection pipe 6 outlet is flush with the side wall of the disc baffle 10. The distance between the disc baffle 10 and the side wall of the wafer is 2mm. The opening face of the circular cover 111 is flush with the side wall of the disc baffle 10 near the wafer. The diameter of the disc baffle 10 is 2mm smaller than the inner diameter of the circular cover 111. The inner diameter of the circular cover 111 is the same as the diameter of the wafer.

[0021] The heat exchange unit 12 is installed at the end of the upper semi-circular shell 2, and the edge exhaust unit 11 and the air supply pipe 9 are both connected to the interior of the heat exchange unit 12. The heat exchange unit 12 includes an insulation box 121 fixed at the end of the upper semi-circular shell 2. Two partitions 122 are fixed inside the insulation box 121. The air inlet end of the air supply pipe 9 is located between the two partitions 122, and the air outlet end of the exhaust pipe 113 is located outside the two partitions 122. An oxygen supply pipe 123 and a nitrogen supply pipe 124 are fixedly inserted into the side wall of the insulation box 121 located between the two partitions 122. A tail gas pipe 125 is fixedly inserted into the side wall of the insulation box 121 away from the exhaust pipe 113. Several evenly distributed heat exchange pipes 126 are fixedly inserted between the two partitions 122. This can improve the thermal energy utilization rate of the equipment, reduce heating energy consumption, and at the same time avoid the temperature drop inside the upper semi-circular shell 2 and the lower semi-circular shell 1 caused by room temperature oxygen, which is conducive to maintaining the stability of the reaction zone.

[0022] A diverter pipe 13 is fixedly inserted into the wall of the nitrogen supply pipe 124, and the diverter pipe 13 is connected to the interior of the upper semi-circular outer shell 2. An outlet pipe 14 is fixedly inserted into the end of the lower semi-circular outer shell 1 away from the diverter pipe 13. A first control valve 15 is installed inside both the outlet pipe 14 and the diverter pipe 13. A second control valve 16 is installed inside the outlet ends of both the nitrogen supply pipe 124 and the tail gas pipe 125. A third control valve 17 is installed inside the oxygen supply pipe 123. The first control valve 15, the second control valve 16, and the third control valve 17 are all electrically connected to the controller 3 to facilitate the discharge of air, water vapor, etc. from the upper semi-circular outer shell 2 and the lower semi-circular outer shell 1. A water-cooling structure is required at the tail gas pipe 125 and other locations to prevent the airflow temperature from being too high and affecting components such as the second control valve 16. The first control valve 15, the second control valve 16, and the third control valve 17 can also be manually operated high-temperature resistant valves. When it is necessary to open the valve, the controller 3 issues a prompt message, and the operator opens it manually.

[0023] A nitrogen concentration detection sensor 18 is fixedly inserted into the wall of the outlet pipe 14, and the nitrogen concentration detection sensor 18 is electrically connected to the controller 3. The nitrogen concentration detection sensor 18 can monitor the nitrogen concentration in real time and send an electrical signal back to the controller 3 after the nitrogen concentration reaches the set threshold.

[0024] Both sides of the lower semi-circular outer shell 1 are provided with arc-shaped positioning strips 19, and the arc-shaped positioning strips 19 are fixed to the inner wall of the semi-circular heater 4 on the same side. The arc-shaped positioning strips 19 can facilitate the positioning and placement of the quartz boat. The arc-shaped positioning strips 19 can ensure that the center of the wafer is coaxial with the gas injection tube 6, and avoid uneven oxide layer caused by the center gas injection shift.

[0025] The operating principle of this invention is explained as follows: Select a solid-state transformer wafer and ultrasonically clean it sequentially with acetone, anhydrous ethanol, and deionized water to remove surface oil, impurities, and oxide layers. Specifically, use acetone at 40-60W power for 5-8 minutes to remove surface oil, use anhydrous ethanol at 40-60W power for 5-8 minutes to dissolve residual acetone, and use deionized water at 40-60W power for 8-10 minutes to remove residual organic matter. After cleaning, place it in a drying oven at 120-150℃ for 1-2 hours to dry, and obtain a clean and impurity-free wafer to be passivated. The processed wafer to be passivated is then placed vertically in a quartz boat, which is then positioned inside the lower semi-circular outer shell 1. Two arc-shaped positioning strips 19 are used to position the quartz boat, ensuring precise wafer placement. The controller 3 is then activated, controlling the electric push rod 52 to operate according to the program, sealing the upper semi-circular outer shell 2 and the lower semi-circular outer shell 1. Subsequently, the controller 3 opens the first control valve 15 in the outlet pipe 14 and the diversion pipe 13, and closes the second control valve 16 in the nitrogen supply pipe 124 and the exhaust pipe 125. Nitrogen is then supplied through the nitrogen supply pipe 124. Nitrogen gas enters the upper semi-circular outer shell 2 and the lower semi-circular outer shell 1 through the nitrogen supply pipe 124 and the diversion pipe 13. Under the action of nitrogen gas pressure, the air and water vapor inside the upper semi-circular outer shell 2 and the lower semi-circular outer shell 1 are discharged from the gas outlet pipe 14. As nitrogen gas continues to enter, the air and water vapor are completely discharged. The nitrogen gas concentration at the gas outlet pipe 14 gradually increases. When the nitrogen gas concentration detection sensor 18 detects that the nitrogen gas concentration has reached the set threshold, it will send an electrical signal to the controller 3. At this time, the controller 3 controls the first control valve 15 to close and controls the second control valve 16 to open. Subsequently, controller 3 controls the two semi-annular heaters 4 to operate. The semi-annular heaters 4 heat up to 1150-1200℃ at a rate of 5-8℃ / min. During the heating process, nitrogen is continuously supplied through nitrogen supply pipe 124. After the temperature reaches the set value (several thermocouples are installed inside the semi-annular heaters 4 to monitor the heating temperature), controller 3 controls the second control valve 16 in nitrogen supply pipe 124 to close and controls the third control valve 17 in oxygen supply pipe 123 to open, supplying oxygen through oxygen supply pipe 123. The oxygen enters the gas supply pipe 9 through the heat insulation box 121, and then the oxygen passes through the first connection. The tube 8 and the gas injection cylinder 7 spray oxygen from the gas injection tube 6 to the surface of the wafer center. Under the guidance of the disk baffle 10, the oxygen diffuses from the wafer center to the edge. Since the temperature of the wafer center is slightly lower than that of the edge (the distance between the wafer edge and the semi-circular heater 4 is closer, so the temperature of the edge is higher due to radiation heating), by contacting the wafer center with high-purity oxygen first, the wafer center with lower temperature can preferentially obtain sufficient oxygen supply, thereby increasing the thermal oxidation reaction rate in the central region. The edge, due to its higher temperature, can also ensure the thermal oxidation reaction rate, thereby improving the uniformity of the overall oxide layer thickness of the wafer. Since the first control valve 15 in the exhaust pipe 14 is closed at this time, and there are no exhaust ports on the side walls of the upper semicircular shell 2 and the lower semicircular shell 1, the airflow flowing to the outer edge of the wafer will immediately enter the circular cover 111 and eventually be discharged into the heat insulation box 121 through the exhaust pipe 112, the second connecting pipe 114 and the exhaust pipe 113. By quickly discharging the airflow after the reaction, it is possible to effectively prevent the accumulation of waste gases such as CO and CO2 generated by the reaction at the edge of the wafer, eliminate interface impurity defects caused by waste gas residue, stabilize the radial airflow distribution, and, in conjunction with the central gas injection, avoid excessive oxidation in the edge area and ensure that the oxide layer is uniform and dense. The high-temperature exhaust gas entering the heat insulation box 121 will be discharged to the tail gas pipe 125 through the heat exchange tube 126 at the partition 122, and finally discharged through the tail gas pipe 125. When the oxygen passes through the heat insulation box 121, it can exchange heat with the heat exchange tube 126, so that the high-temperature exhaust gas can be used to preheat the oxygen, improve the thermal energy utilization rate of the equipment, reduce heating energy consumption, and avoid the temperature drop inside the upper semi-circular shell 2 and the lower semi-circular shell 1 caused by room temperature oxygen, which is conducive to maintaining the stability of the reaction area. After a 2-3 hour thermal oxidation reaction, controller 3 controls the third control valve 17 in oxygen supply pipe 123 to close and stop oxygen supply. At the same time, it controls the second control valve 16 in nitrogen supply pipe 124 to open again and supply nitrogen. Annealing is carried out at a temperature of 1150-1200℃ for 30 minutes. Annealing in a nitrogen atmosphere at high temperature can eliminate dangling bonds and stress defects at the SiC / SiO2 interface in situ, and significantly improve the pressure resistance and long-term stability of the passivation layer. Then, the heating temperature of the semi-circular heater 4 is controlled to be cooled down to below 100℃ at a rate of 3-5℃ / min. After cooling is completed, the upper semi-circular shell 2 and the lower semi-circular shell 1 are opened and the quartz boat is taken out.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solid-state transformer wafer passivation device, comprising a lower semi-circular shell (1), an upper semi-circular shell (2), and a controller (3), wherein a semi-annular heater (4) is installed on the inner sidewall of both the lower semi-circular shell (1) and the upper semi-circular shell (2), and a driving assembly (5) for driving the upper semi-circular shell (2) to move is installed on the lower semi-circular shell (1), characterized in that, Also includes: Several sets of air injection pipes (6) are coaxially arranged between the lower semicircular shell (1) and the upper semicircular shell (2). Each air injection pipe (6) is fixedly connected to an air injection cylinder (7), and the air injection cylinder (7) is fixedly connected to a first connecting pipe (8). A sealed air supply pipe (9) is fixedly inserted into the end of the upper semicircular shell (2), and the first connecting pipe (8) is connected to the air supply pipe (9). Several sets of symmetrically arranged disc baffles (10) are coaxially arranged between the lower semicircular shell (1) and the upper semicircular shell (2), and the side wall of the disc baffle (10) is fixedly inserted into the corresponding air injection pipe (6); An edge exhaust unit (11) is disposed between the lower semicircular outer shell (1) and the upper semicircular outer shell (2), and the edge exhaust unit (11) is used to exhaust the airflow discharged from the disc baffle (10); The heat exchange unit (12) is installed at the end of the upper semi-circular shell (2), and the edge exhaust unit (11) and the air supply pipe (9) are both connected to the interior of the heat exchange unit (12); Two arc-shaped positioning strips (19) are provided on both sides inside the lower semi-circular outer shell (1), and the arc-shaped positioning strips (19) are fixed to the inner wall of the semi-circular heater (4) on the same side; The edge exhaust unit (11) includes a circular cover (111) sleeved on the outside of the circular baffle (10). An exhaust pipe (112) is fixedly inserted into the side wall of the circular cover (111). The circular cover (111) and the exhaust pipe (112) are both coaxial with the air injection pipe (6). The air injection pipe (7) is fixed at the end of the exhaust pipe (112), and the air injection pipe (6) passes through the exhaust pipe (112) and communicates with the air injection pipe (7).

2. The solid-state transformer wafer passivation device according to claim 1, characterized in that, The drive assembly (5) includes a support block (51) fixed to the end of the lower semi-circular shell (1), an electric push rod (52) fixed to the top of the support block (51), a lifting block (53) fixed to the end of the upper semi-circular shell (2), and the movable end of the electric push rod (52) is fixedly connected to the lifting block (53). The electric push rod (52) is electrically connected to the controller (3).

3. The solid-state transformer wafer passivation device according to claim 2, characterized in that, The edge exhaust unit (11) also includes an exhaust pipe (113) fixedly inserted into the end of the upper semi-circular shell (2), and one end of the exhaust pipe (113) is sealed. The side wall of the exhaust cylinder (112) is fixedly inserted with a second connecting pipe (114), and the second connecting pipe (114) is connected to the exhaust pipe (113).

4. The solid-state transformer wafer passivation device according to claim 3, characterized in that, The heat exchange unit (12) includes a heat insulation box (121) fixed to the end of the upper semi-circular outer shell (2). The heat insulation box (121) has two partitions (122) fixed inside. The air inlet of the air supply pipe (9) is located between the two partitions (122). The air outlet of the exhaust pipe (113) is located outside the two partitions (122). An oxygen supply pipe (123) and a nitrogen supply pipe (124) are fixedly inserted into the side wall of the heat insulation box (121) located between the two partitions (122). A tail gas pipe (125) is fixedly inserted into the side wall of the heat insulation box (121) away from the exhaust pipe (113). Several evenly distributed heat exchange pipes (126) are fixedly inserted between the two partitions (122).

5. The solid-state transformer wafer passivation device according to claim 4, characterized in that, A diverter pipe (13) is fixedly inserted into the wall of the nitrogen supply pipe (124), and the diverter pipe (13) is connected to the interior of the upper semi-circular shell (2). An outlet pipe (14) is fixedly inserted into the end of the lower semi-circular shell (1) away from the diverter pipe (13). A first control valve (15) is installed inside the outlet pipe (14) and the diverter pipe (13). A second control valve (16) is installed inside the outlet end of the nitrogen supply pipe (124) and the tail gas pipe (125). A third control valve (17) is installed inside the oxygen supply pipe (123). The first control valve (15), the second control valve (16) and the third control valve (17) are all electrically connected to the controller (3).

6. The solid-state transformer wafer passivation device according to claim 5, characterized in that, A nitrogen concentration detection sensor (18) is fixedly inserted into the wall of the gas outlet pipe (14), and the nitrogen concentration detection sensor (18) is electrically connected to the controller (3).

7. A method of using a solid-state transformer wafer passivation device, which is applied to the solid-state transformer wafer passivation device as described in claim 6, characterized in that, The usage method includes the following steps: Step 1: Select a solid-state transformer wafer and clean it sequentially with acetone, anhydrous ethanol, and deionized water using ultrasonic cleaning to remove surface oil, impurities, and oxide layers. After cleaning, place it in a drying oven at 120-150℃ for 1-2 hours to obtain a clean and impurity-free wafer to be passivated. Step 2: Place the wafer to be passivated after step 1 vertically in the quartz boat and place the quartz boat inside the lower semi-circular shell (1). Then start the controller (3). The controller (3) controls the drive assembly (5) to close the upper semi-circular shell (2) and the lower semi-circular shell (1). Then, it controls the first control valve (15) in the outlet pipe (14) and the diversion pipe (13) to open, and controls the second control valve (16) in the nitrogen supply pipe (124) and the tail gas pipe (125) to close. Then, nitrogen is supplied through the nitrogen supply pipe (124). When the nitrogen concentration detection sensor (18) feeds back an electrical signal, the controller (3) controls the first control valve (15) to close and controls the second control valve (16) to open. Step 3: The controller (3) controls the two semi-annular heaters (4) to work, raising the temperature to 1150-1200℃ at a rate of 5-8℃ / min. During the heating process, nitrogen is continuously introduced through the nitrogen supply pipe (124). Step 4: After the temperature reaches the set value, the controller (3) controls the second control valve (16) in the nitrogen supply pipe (124) to close and controls the third control valve (17) in the oxygen supply pipe (123) to open, and supplies oxygen through the oxygen supply pipe (123) to carry out a thermal oxidation reaction for 2-3 hours. After the thermal oxidation reaction in step five and step four is completed, the controller (3) controls the third control valve (17) in the oxygen supply pipe (123) to close and stop the oxygen supply. At the same time, it controls the second control valve (16) in the nitrogen supply pipe (124) to open again and supply nitrogen. It maintains the temperature at 1150-1200℃ for annealing for 30 minutes. Then, it controls the heating temperature of the semi-circular heater (4) to be cooled down to below 100℃ at a rate of 3-5℃ / min. After the cooling is completed, the upper semi-circular shell (2) and the lower semi-circular shell (1) are opened and the quartz boat is taken out.

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