Wafer reflow vacuum furnace

Abstract

The utility model relates to the technical field of semiconductor chip processing, a wafer reflow vacuum furnace, including plasma cleaning area, first formic acid cleaning area, welding area, a plurality of wafer tray, first plug -in board valve, second plug -in board valve, fourth plug -in board valve, fifth plug -in board valve, sixth plug -in board valve and first cooling area, according to work flow setting plasma cleaning area first formic acid cleaning area welding area and first cooling area. Multiple processes significantly improve surface cleanliness, reduce welding defects.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor chip processing technology, and in particular to a wafer reflow vacuum furnace. Background Technology

[0002] Reflow soldering is a crucial process in electronic manufacturing, primarily used for soldering tiny components. It's also employed in advanced semiconductor packaging to shape chip leads. Traditional reflow soldering uses flux, requiring pre-coating and subsequent flux removal, resulting in a complex and costly process. Advanced semiconductor packaging utilizes a more advanced formic acid reflow process, eliminating the need for spin coating and flux cleaning. This offers advantages such as simplicity, low cost, and high throughput. However, currently, similar equipment is scarce in the industry, leading to low surface cleanliness and a high rate of soldering defects. Summary of the Invention

[0003] This invention provides a wafer reflow vacuum furnace to solve the problems of low surface cleanliness and high welding defects in the existing technology during wafer reflow.

[0004] This utility model provides a wafer reflow vacuum furnace, including a plasma cleaning zone, a first formic acid cleaning zone, a welding zone, multiple wafer trays, a first insertion valve, a second insertion valve, a fourth insertion valve, a fifth insertion valve, a sixth insertion valve, and a first cooling zone. The plasma cleaning zone, the first formic acid cleaning zone, the welding zone, and the first cooling zone are arranged according to the workflow. The first insertion valve is located at the inlet end of the plasma cleaning zone, and the second insertion valve is located at the outlet end of the plasma cleaning zone. The second insertion valve is located at the inlet end of the first formic acid cleaning zone, and the fourth insertion valve is located at the outlet end of the first formic acid cleaning zone. The fourth insertion valve is located at the inlet end of the welding zone, and the fifth insertion valve is located at the outlet end of the welding zone. The fifth insertion valve is located at the inlet end of the first cooling zone, and the sixth insertion valve is located at the outlet end of the first cooling zone. The wafer trays are arranged inside the plasma cleaning zone, the first formic acid cleaning zone, the welding zone, and the first cooling zone, and the support legs of the wafer trays support the wafers.

[0005] According to the wafer reflow vacuum furnace of this utility model, the plasma cleaning zone includes a plasma cleaning zone upper cover and a plasma cleaning zone lower cavity; the plasma cleaning zone upper cover is disposed above the plasma cleaning zone lower cavity, the plasma cleaning zone upper cover and the plasma cleaning zone lower cavity form a vacuum cavity, an insulating groove fixing plate is disposed below the plasma cleaning zone upper cover, an electrode plate is disposed inside the insulating groove fixing plate, a vacuum electrode is disposed at the top of the plasma cleaning zone upper cover, and an inner liner is disposed inside the plasma cleaning zone lower cavity.

[0006] The wafer reflow vacuum furnace according to this utility model further includes a third gate valve and a second formic acid cleaning zone. The second formic acid cleaning zone is the previous station area of ​​the welding zone. The third gate valve is provided at the inlet end of the second formic acid cleaning zone, and a fourth gate valve is provided at the outlet end of the second formic acid cleaning zone.

[0007] The wafer reflow vacuum furnace according to this utility model further includes a seventh gate valve and a second cooling zone. The second cooling zone is the next station area after the first cooling zone. The sixth gate valve is provided at the inlet end of the second cooling zone, and the seventh gate valve is provided at the outlet end of the second cooling zone.

[0008] According to the wafer reflow vacuum furnace of this utility model, the first formic acid cleaning zone, the second formic acid cleaning zone, and the welding zone include a first mounting frame, an upper cover, an upper heating tube, a heating plate, a power wheel, a guide wheel, and a lower heating tube; the heating plate is disposed inside the first mounting frame, the power wheel and the guide wheel are disposed on both sides of the heating plate, the lower heating tube is disposed below the heating plate, the upper heating tube is disposed inside the upper cover, the upper cover is disposed above the first mounting frame, and the upper cover and the first mounting frame form a sealed cavity.

[0009] According to the wafer reflow vacuum furnace of this utility model, the distance between the upper heating tube and the wafer tray is equal to the distance between the lower heating tube and the wafer tray.

[0010] According to the wafer reflow vacuum furnace of this utility model, the first cooling zone and the second cooling zone include a second mounting frame, a cooling plate, a boss notch and a boss; the cooling plate is disposed inside the second mounting frame, the boss is disposed above the cooling plate, and the boss has a boss notch at the support leg position of the wafer tray.

[0011] The wafer reflow vacuum furnace according to this utility model also includes a small wafer and a non-contact temperature sensor. The small wafer and the contact or non-contact temperature sensor are arranged in the first formic acid cleaning area, the second formic acid cleaning area and the welding area. The small wafer is located within the detection range of the non-contact temperature sensor.

[0012] According to the wafer reflow vacuum furnace of this utility model, the wafer tray further includes a tray frame and a notch; the notch is provided on both sides of the tray frame in the transmission direction, and the support legs are provided on both sides inside the tray frame.

[0013] This utility model has the following advantages:

[0014] The electrode plate is the positive electrode, and the inner liner is the negative electrode. The insulating tank fixing plate is made of high-temperature and high-pressure resistant insulating materials (such as ceramics and polytetrafluoroethylene), which not only isolates the electrode plate from the metal cover to prevent short circuits during discharge, but also ensures a tight seal with the cover through a precision sealing structure, guaranteeing no gas leakage in a vacuum environment and maintaining the vacuum level of the chamber. The electrode position is optimized to cover the discharge range and avoid partial discharge blind spots. Plasma cleaning can efficiently remove surface organic contaminants, oxides, and microparticles, activating the surface activity of the material. Formic acid cleaning further removes metal oxides, creating a reducing environment and providing a clean surface for welding. Multiple processes significantly improve surface cleanliness and reduce welding defects. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the main structure of a vacuum furnace;

[0017] Figure 2 This is a three-dimensional structural schematic diagram of a vacuum furnace;

[0018] Figure 3 This is a schematic diagram of the three-dimensional structure of the plasma cleaning zone;

[0019] Figure 4 This is a cross-sectional view of the plasma cleaning zone, along with a schematic diagram.

[0020] Figure 5 A three-dimensional structural diagram of the upper cover of the plasma cleaning zone;

[0021] Figure 6 This is a cross-sectional view of the welding area and a schematic diagram of its structure.

[0022] Figure 7 This is a schematic diagram of the lower cavity structure of the welding area;

[0023] Figure 8 This is a schematic diagram of the three-dimensional structure of a wafer tray;

[0024] Figure 9 This is a schematic diagram of the main view structure of a wafer tray;

[0025] Figure 10 This is a magnified view of the structure of part A;

[0026] Figure 11 This is a magnified view of the structure of part B;

[0027] Figure 12 This is a three-dimensional structural diagram of the lower cavity of the first cooling zone.

[0028] Figure 13 This is a three-dimensional structural diagram of the upper cover of the first cooling zone.

[0029] Figure 14 This is a schematic diagram of the cross-sectional structure of the upper cover of the first cooling zone;

[0030] Reference numerals: 1. Plasma cleaning zone; 2. First formic acid cleaning zone; 3. Second formic acid cleaning zone; 4. Welding zone; 5. First cooling zone; 6. Second cooling zone; 8. Lifting mechanism; 9. Wafer tray; 10. First gate valve; 20. Second gate valve; 30. Third gate valve; 40. Fourth gate valve; 50. Fifth gate valve; 60. Sixth gate valve; 70. Seventh gate valve; 11. Upper cover of plasma cleaning zone; 12. Lower cavity of plasma cleaning zone; 111. Upper cover frame of plasma cleaning zone; 112. Insulating tank fixing plate; 113. Electrode plate; 114. Vacuum electrode; 121. Plasma cleaning... 122. Lower cavity frame; 41. Inner liner; 42. Upper heating tube; 43. Lower heating tube; 44. First mounting frame; 45. Small wafer; 46. Heating plate; 47. Power wheel; 48. Guide wheel; 49. Power wheel spacing; 51. Second mounting frame; 52. Cooling plate; 53. Airbag; 54. Second nitrogen pipe; 55. Cooling zone upper cover frame; 56. Upper cover heat dissipation plate; 57. Motor; 91. Tray frame; 92. Support leg; 93. Notch length L; 94. Tray length; 95. Notch; 96. Material picking notch; 411. First nitrogen pipe; 412. First nitrogen pipe port. Detailed Implementation

[0031] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.

[0032] In the description of the embodiments of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model based on the specific circumstances.

[0034] In this embodiment of the utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0035] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0036] The following is combined with Figure 1-14A wafer reflow vacuum furnace according to an embodiment of the present invention includes a plasma cleaning zone 1, a first formic acid cleaning zone 2, a soldering zone 4, multiple wafer trays 9, a first insert valve 10, a second insert valve 20, a fourth insert valve 40, a fifth insert valve 50, a sixth insert valve 60, and a first cooling zone 5. The plasma cleaning zone 1, the first formic acid cleaning zone 2, the soldering zone 4, and the first cooling zone 5 are arranged according to the workflow. A first insert valve 10 is provided at the inlet end of the plasma cleaning zone 1, and a second insert valve is provided at the outlet end of the plasma cleaning zone 1. 20. A second gate valve 20 is installed at the inlet end of the first formic acid cleaning zone 2, and a fourth gate valve 40 is installed at the outlet end of the first formic acid cleaning zone 2. A fourth gate valve 40 is installed at the inlet end of the welding zone 4, and a fifth gate valve 50 is installed at the outlet end of the welding zone 4. A fifth gate valve 50 is installed at the inlet end of the first cooling zone 5, and a sixth gate valve 60 is installed at the outlet end of the first cooling zone 5. A wafer tray 9 is installed inside the plasma cleaning zone 1, the first formic acid cleaning zone 2, the welding zone 4, and the first cooling zone 5. The support legs of the wafer tray 9 support the wafer. The surface of the support leg 92 supporting the wafer has an arc structure to reduce the contact between the support leg 92 and the wafer and reduce the temperature influence of the support leg 92 on the wafer. The support leg 92 limits the wafer movement; the middle support leg 92 is short, and the two side support legs 92 are long. The positive pressure resistant vacuum gate valve and the furnace cavity sealing structure design have a locking device. The furnace cavity can withstand positive pressure, allowing for a larger amount of reducing gas to be filled, resulting in better reducing properties.

[0037] In some embodiments, the plasma cleaning zone 1 includes a plasma cleaning zone upper cover 11 and a plasma cleaning zone lower cavity 12. The plasma cleaning zone upper cover 11 is disposed above the plasma cleaning zone lower cavity 12, and the plasma cleaning zone upper cover 11 and the plasma cleaning zone lower cavity 12 form a vacuum cavity. An insulating groove fixing plate 112 is disposed below the plasma cleaning zone upper cover 11, that is, an insulating groove fixing plate 112 is disposed below the plasma cleaning zone upper cover frame 111. An electrode plate 113 is disposed inside the insulating groove fixing plate 112. A vacuum electrode 114 is disposed at the top of the plasma cleaning zone upper cover 11, and the vacuum electrode 114 is connected to the electrode plate 113. An inner liner 122 is disposed inside the plasma cleaning zone lower cavity 12, that is, an inner liner 122 is disposed inside the plasma cleaning zone lower cavity frame 121. The inner liner 122 is connected to the negative electrode.

[0038] Plasma cleaning zone 1 provides an inert gas environment or a reducing gas environment;

[0039] The first formic acid cleaning zone 2 provides a vacuum environment, an inert gas environment, or a reducing gas environment; the second formic acid cleaning zone 3 provides a vacuum environment, an inert gas environment, or a reducing gas environment.

[0040] Welding zone 4 provides a vacuum environment, an inert gas environment, or a reducing gas environment.

[0041] Nitrogen is preferred as the inert gas. Formic acid is preferred as the reducing gas.

[0042] In some embodiments, a third gate valve 30 and a second formic acid cleaning zone 3 are also included. The second formic acid cleaning zone 3 is the previous station area of ​​the welding zone 4. The third gate valve 30 is provided at the inlet end of the second formic acid cleaning zone 3, and a fourth gate valve 40 is provided at the outlet end of the second formic acid cleaning zone 3.

[0043] In some embodiments, a seventh gate valve and a second cooling zone 6 are also included. The second cooling zone 6 is the next station after the first cooling zone 5. A sixth gate valve is provided at the inlet end of the second cooling zone 6, and a seventh gate valve is provided at the outlet end of the second cooling zone 6. Filtration is performed simultaneously in each of the above station zones during vacuuming.

[0044] In some embodiments, the first formic acid cleaning zone 2, the second formic acid cleaning zone 3, and the welding zone 4 include a first mounting frame 43, an upper cover, an upper heating pipe 41, a heating plate 45, a drive wheel 46, a guide wheel 47, and a lower heating pipe 42. The heating plate 45 is disposed inside the first mounting frame 43, with the drive wheel 46 and guide wheel 47 disposed on both sides of the heating plate 45. The lower heating pipe 42 is disposed below the heating plate 45, and the upper heating pipe 41 is disposed inside the upper cover. The upper cover is disposed above the first mounting frame 43, and the upper cover and the first mounting frame 43 form a sealed cavity. The lower cavity of the first formic acid cleaning zone 2, the second formic acid cleaning zone 3, and the welding zone 4 includes the first mounting frame 43, the heating plate 45, the drive wheel 46, the guide wheel 47, and the lower heating pipe 42. Nitrogen pipes 411 are arranged around the upper part of the first mounting frame 43. Multiple nitrogen ports 412 are provided in the nitrogen pipes 411. The nitrogen ports 412 are set with an upward-sloping outlet to reduce the impact of nitrogen on the cavity, that is, to reduce the impact of nitrogen on the wafer and improve the welding quality of the wafer.

[0045] In some embodiments, the distance between the upper heating tube 41 and the wafer tray 9 is equal to the distance between the lower heating tube 42 and the wafer tray 9. The wafer is placed on the wafer tray 9, thereby ensuring that the distance between the upper heating tube 41 and the wafer is equal to the distance between the lower heating tube 42 and the wafer, enabling non-contact heating or soldering. In other words, this improves the temperature uniformity and consistency of the heating on both the upper and lower surfaces of the wafer, thus enhancing the heating uniformity of the upper and lower surfaces of the wafer.

[0046] In some embodiments, the first cooling zone 5 and the second cooling zone 6 include a second mounting frame 51, a cooling zone cover, a cooling plate 52, a boss notch 54, and a boss 53. The cooling plate 52 is disposed inside the second mounting frame 51, and a boss 53 is disposed above the cooling plate. The boss 53 has a boss notch 54 at the support leg 92 position of the wafer tray 9. A lifting mechanism 8 is disposed below the first cooling zone 5 and the second cooling zone 6. During cooling, the lifting mechanism 8 lifts and lowers the cooling plate 52 and the boss 53, allowing the wafer to directly contact the boss 53, thus improving the wafer's cooling efficiency. The lower cavity of the first cooling zone 5 and the second cooling zone 6 includes the second mounting frame 51, the cooling zone cover, the cooling plate 52, the boss notch 54, and the boss 53. The cooling zone cover and the lower cavity of the first cooling zone 5 or the second cooling zone 6 form a vacuum-sealed cavity.

[0047] In some embodiments, the system further includes a small wafer 44 and a contact or non-contact temperature sensor. The small wafer 44 and the contact or non-contact temperature sensor are disposed in the first formic acid cleaning area 2, the second formic acid cleaning area 3, and the welding area 4. The small wafer 44 is positioned within the detection range of the contact or non-contact temperature sensor. The contact or non-contact temperature sensor is located above the top cover, i.e., outside the cavity, and has a temperature measurement window. Temperature control is achieved using the small wafer 44. The infrared sensor directly measures the temperature of the small wafer 44. Since the small wafer 44 and the wafer are made of the same material, they reach the same temperature, improving the accuracy of temperature control. The non-contact temperature sensor is preferably an infrared temperature sensor.

[0048] In some embodiments, the wafer tray 9 further includes a tray frame 91 and notches 95; notches 95 are provided on both sides of the tray frame 91 in the transmission direction, and support legs 92 are provided on both sides inside the tray frame. The support legs 92 support the wafer. The support legs 92 are made of quartz, which does not absorb heat and does not affect the temperature of the wafer, thus improving the wafer reflow quality. The drive wheel 46 supports transmission within the notches 95. An upper baffle is provided below the upper heating tube 41, so that the upper heating tube 41 can only heat the upper surface of the wafer after the upper baffle is blocked. A lower baffle is provided above the lower heating tube 42, so that the lower heating tube 42 can only heat the lower surface of the wafer after the lower baffle is blocked. The upper baffle reduces the temperature influence of the upper heating tube 41 on the lower surface of the wafer, and the lower baffle reduces the temperature influence of the lower heating tube 42 on the upper surface of the wafer, realizing non-contact heating or welding, that is, realizing simultaneous heating or welding of the upper and lower surfaces of the wafer. A pick-up notch 96 is provided in the in-and-out transport direction of the tray frame 91, which facilitates the robotic arm to pick up the wafers.

[0049] In some embodiments, the notch length L93 of the notch 95 is greater than the width 48 of the drive wheel, and the notch length L93 of the notch 95 is less than 1.5 times the width 48 of the drive wheel. This is to prevent the wafer tray from tilting during transport. The distance between the edge of the notch 95 and the edge of the drive wheel 46 is less than 0.5 times the width 48 of the drive wheel, and the spacing 49 between the drive wheels is less than or equal to 1 / 4 of the wafer tray length 94. This is to prevent adjustment before the wafer tray tilts and jams, thus preventing jamming.

[0050] In some embodiments, the system further includes an inner liner 50, which is disposed within the first formic acid cleaning zone 2, the second formic acid cleaning zone 3, and the welding zone 4. An upper heating element 41 and a lower heating element 42 are disposed inside the inner liner 50. The inner liner 50 is a cuboid shape and is fixed to the upper cover or the first mounting frame 43. The inner liner 50 uses a single-sided mirror panel, which provides good heat reflection and insulation, reducing heating time and improving wafer reflow efficiency.

[0051] The workflow of a wafer reflow vacuum furnace is as follows:

[0052] The wafer robotic arm picks up the first wafer, the plasma cleaning zone 1 opens, and the transmission mechanism of the plasma cleaning zone 1 drives the power wheel 46 to transmit the first wafer into the plasma cleaning zone 1. The inlet valve 7 of the plasma cleaning zone 1 closes, and after the plasma cleaning zone 1 is evacuated, it is filled with a mixture of nitrogen and formic acid.

[0053] After evacuating the first formic acid cleaning zone 2, the second formic acid cleaning zone 3, the welding zone 4, the first cooling zone 5, and the second cooling zone 6, a mixture of nitrogen and formic acid gas is introduced.

[0054] Open the inlet valve 7 of the first formic acid cleaning zone 2, and the first wafer enters the first formic acid cleaning zone 2.

[0055] After the first wafer reaches the preheating standard, the second formic acid cleaning zone 3 opens, and the transmission mechanism drives the power wheel 46 to transmit the first wafer into the second formic acid cleaning zone 3; the second formic acid cleaning zone 3 closes, and nitrogen is replenished and replaced and formic acid is introduced as needed, and the heater starts to work.

[0056] After the first wafer reaches the heating standard, the second formic acid cleaning zone 3 opens, and the transmission mechanism drives the power wheel 46 to transmit the first wafer into the welding zone 4. The welding zone 4 closes, and nitrogen is replenished and replaced, and formic acid is introduced as needed before welding.

[0057] After the first wafer is processed, the soldering zone 4 opens, and the transfer mechanism drives the power wheel 46 to transfer the first wafer into the first cooling zone 5. The first cooling zone 5 closes, and the cooling device starts working. After pre-cooling reaches the required standard, it enters the second cooling zone 6, with the same process as the pre-cooling zone, until the temperature reaches room temperature.

[0058] After cooling, the wafer is transferred to the exit area and removed by a robotic arm. Then the cycle begins.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A wafer reflow vacuum furnace, characterized in that, The system includes a plasma cleaning zone, a first formic acid cleaning zone, a welding zone, multiple wafer trays, a first insertion valve, a second insertion valve, a fourth insertion valve, a fifth insertion valve, a sixth insertion valve, and a first cooling zone. The plasma cleaning zone, the first formic acid cleaning zone, the welding zone, and the first cooling zone are configured according to the workflow. The first insertion valve is located at the inlet of the plasma cleaning zone, and the second insertion valve is located at the outlet of the plasma cleaning zone. The second insertion valve is located at the inlet of the first formic acid cleaning zone, and the fourth insertion valve is located at the outlet of the first formic acid cleaning zone. The fourth insertion valve is located at the inlet of the welding zone, and the fifth insertion valve is located at the outlet of the welding zone. The fifth insertion valve is located at the inlet of the first cooling zone, and the sixth insertion valve is located at the outlet of the first cooling zone. Wafer trays are located inside the plasma cleaning zone, the first formic acid cleaning zone, the welding zone, and the first cooling zone, and the wafer trays have supporting legs that support the wafers.

2. The wafer reflow vacuum furnace according to claim 1, characterized in that, The plasma cleaning zone includes a plasma cleaning zone upper cover and a plasma cleaning zone lower cavity; the plasma cleaning zone upper cover is disposed above the plasma cleaning zone lower cavity, the plasma cleaning zone upper cover and the plasma cleaning zone lower cavity form a vacuum cavity, an insulating groove fixing plate is disposed below the plasma cleaning zone upper cover, an electrode plate is disposed inside the insulating groove fixing plate, a vacuum electrode is disposed at the top of the plasma cleaning zone upper cover, and an inner liner is disposed inside the plasma cleaning zone lower cavity.

3. The wafer reflow vacuum furnace according to claim 1, characterized in that, It also includes a third gate valve and a second formic acid cleaning zone, the second formic acid cleaning zone being the previous station of the welding zone, the third gate valve being installed at the inlet end of the second formic acid cleaning zone, and a fourth gate valve being installed at the outlet end of the second formic acid cleaning zone.

4. The wafer reflow vacuum furnace according to claim 3, characterized in that, It also includes a seventh gate valve and a second cooling zone. The second cooling zone is the next working zone after the first cooling zone. The sixth gate valve is installed at the inlet end of the second cooling zone, and the seventh gate valve is installed at the outlet end of the second cooling zone.

5. The wafer reflow vacuum furnace according to claim 4, characterized in that, The first formic acid cleaning area, the second formic acid cleaning area, and the welding area include a first mounting frame, an upper cover, an upper heating pipe, a heating plate, a drive wheel, a guide wheel, and a lower heating pipe; the heating plate is disposed inside the first mounting frame, the drive wheel and the guide wheel are disposed on both sides of the heating plate, the lower heating pipe is disposed below the heating plate, the upper heating pipe is disposed inside the upper cover, the upper cover is disposed above the first mounting frame, and the upper cover and the first mounting frame form a sealed cavity.

6. The wafer reflow vacuum furnace according to claim 5, characterized in that, The distance between the upper heating tube and the wafer tray is equal to the distance between the lower heating tube and the wafer tray.

7. The wafer reflow vacuum furnace according to claim 4, characterized in that, The first cooling zone and the second cooling zone include a second mounting frame, a cooling plate, a boss notch, and a boss; the cooling plate is disposed inside the second mounting frame, the boss is disposed above the cooling plate, and the boss has a boss notch at the support leg position of the wafer tray.

8. The wafer reflow vacuum furnace according to claim 4, characterized in that, It also includes a small wafer and a non-contact temperature sensor. The small wafer and the contact or non-contact temperature sensor are arranged in the first formic acid cleaning area, the second formic acid cleaning area and the welding area. The small wafer is located within the detection range of the non-contact temperature sensor.

9. The wafer reflow vacuum furnace according to claim 4, characterized in that, The wafer tray also includes a tray frame and a notch; the notch is provided on both sides of the tray frame in the transmission direction, and the support legs are provided on both sides inside the tray frame.

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