A gas intake and exhaust system for tubular CVD equipment

Abstract

The present application relates to the field of photovoltaic cell manufacturing equipment, and in particular to an air intake and exhaust system of a tubular CVD equipment, comprising an air intake pipe connected to a tubular furnace and used for supplying reaction gas and an exhaust pipe for extracting reaction products. The air intake pipe is located in the tubular furnace and is connected to a distribution pipe at one end. The length direction of the distribution pipe opening is consistent with the length direction of the graphite boat. Several distribution pipes are arranged along their own width direction. The air outlet of the distribution pipe faces the upper part of the graphite boat. The air inlet of the exhaust pipe is located above the air outlet of the distribution pipe, so that each distribution pipe can supply air more evenly to various parts of the graphite boat, thereby improving the sufficient contact between the silicon wafers and the reaction gas at various parts of the graphite boat to perform uniform amorphous silicon thin film deposition.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic cell manufacturing equipment, and in particular to an air intake and exhaust system of a tubular CVD equipment. Background Art

[0002] Heterojunction cells are currently an important development direction for photovoltaic cells, especially heterojunction and perovskite tandem cells. A unique step in the manufacture of heterojunction cells is the deposition of an amorphous silicon film on N-type monocrystalline silicon to achieve higher photoelectric conversion efficiency.

[0003] Existing amorphous silicon thin film deposition generally uses plate-type CVD equipment, but tubular CVD has the characteristics of deposited amorphous silicon thin films with good density and passivation properties and has a wider range of applications. Tubular CVD generally has multiple tubular furnaces, a graphite boat is placed at the end of the tubular furnace, and the silicon wafer to be deposited is placed on the graphite boat. The tubular furnace is vacuum and the graphite boat is heated. The heating method can be glow discharge. Reaction gases, namely silane, phosphine, diborane, hydrogen and methane, are fed into one end of the tubular furnace to deposit amorphous silicon thin films on the surface of crystalline silicon. At the same time, reaction waste gas is generated, namely a low-density mixed gas mainly composed of hydrogen. The reaction waste gas is extracted from the other end of the tubular furnace where the reaction gas is fed, and the vacuum degree in the tubular furnace can also be maintained.

[0004] Regarding the above-mentioned related technologies, the method of air intake at one end and air exhaust at the other end of the tube furnace makes it easy for the reaction gas in various places in the tube furnace to be uneven, which in turn makes the amorphous silicon film deposition thickness of silicon wafers located at different positions in the tube furnace inconsistent, affecting the overall deposition uniformity of the amorphous silicon film. Summary of the Invention

[0005] In order to improve the uniformity of the overall deposition of amorphous silicon thin films, the present application provides a gas intake and exhaust system for a tubular CVD device.

[0006] The present application provides a tubular CVD equipment gas intake and exhaust system that adopts the following technical solution.

[0007] A gas inlet and exhaust system for a tubular CVD device includes an air inlet pipe connected to the tubular furnace and used to feed in reaction gases, and an exhaust pipe used to extract reaction products. The air inlet pipe is located in the tubular furnace and is connected to a distribution pipe at one end. The length direction of the distribution pipe opening is consistent with the length direction of the graphite boat. Several distribution pipes are arranged along their own width direction. The air outlet of the distribution pipe faces the upper part of the graphite boat, and the air inlet of the exhaust pipe is located above the air outlet of the distribution pipe.

[0008] By adopting the above technical solution, the reaction gas fed into the tube furnace is sent toward the upper part of the graphite boat. The reaction gas automatically sinks to the bottom of the tube furnace due to the thrust of the initial introduction of the reaction gas and the low temperature of the reaction gas when it enters the tube furnace. As the subsequent reaction gas at room temperature is continuously fed into the tube furnace, the reaction gas previously fed into the tube furnace continuously moves upward in the tube furnace after being appropriately heated, so that good contact is achieved between the reaction gas and the silicon wafer. In addition, the setting of the distribution pipe can transport the reaction gas more evenly toward all parts of the length direction of the graphite boat, so that there is sufficient contact between the silicon wafer and the reaction gas, so that the amorphous silicon film deposited by the reaction of the reaction gas can be more evenly deposited on the surface of the silicon wafer.

[0009] Optionally, a group of the air inlet pipes is arranged corresponding to each distribution pipe, and each group of air inlet pipes is evenly distributed along the length direction of the distribution pipe. A perforated plate is provided inside the distribution pipe, and a plurality of air holes are opened through the perforated plate for the reaction gas fed into the air inlet pipe to be discharged from the air outlet of the distribution pipe.

[0010] By adopting the above technical solution, the reaction gas sent out from the air inlet pipe first impacts the orifice plate, so that the reaction gas is dispersed along the surface of the orifice plate and passes through the orifice plate through the air holes, so that the reaction gas sent out from the distribution pipe is more uniform everywhere.

[0011] Optionally, several orifice plates are provided, and the air holes of two adjacent orifice plates are staggered. The orifice plates closer to the air outlet of the distribution pipe have smaller diameters of air holes, and the air holes on the orifice plates closer to the air outlet of the distribution pipe are denser.

[0012] By adopting the above technical solution, the uniformity of the reaction gas delivered from the gas outlet of the distribution pipe can be improved as much as possible under the joint action of several orifice plates.

[0013] Optionally, the distribution pipe outlet is provided with a group of several distribution leaves, and the distribution leaves in the same group close to the two ends of the distribution pipe in the width direction are inclined, and the distribution leaves in the same group located on both sides of the center point of the distribution pipe close to the side edges of the orifice plate are close to the distribution leaves in the middle position of the same group.

[0014] By adopting the above technical solution, the reaction gas delivered by the distribution pipe can diffuse to both ends of the distribution pipe in its width direction, so that the graphite boat corresponding to two adjacent distribution pipes can also contact with sufficient reaction gas.

[0015] Optionally, each of the air intake pipes includes a left branch pipe, a right branch pipe and a mixing pipe, the left branch pipe and the right branch pipe are connected to the mixing pipe, the mixing pipe is connected to the distribution pipe, and the mixing pipe, the left branch pipe and the right branch pipe are arranged in a Y shape.

[0016] By adopting the above technical solution, while the left branch pipe and the right branch pipe respectively feed the reaction gas into the mixing pipe, the reaction gas is preliminarily mixed due to the arrangement of the left branch pipe and the right branch pipe.

[0017] Optionally, a necking bucket is coaxially provided inside the mixing tube, and the closer the necking bucket is to the opening at one end of the distribution tube, the smaller the inner diameter of the necking bucket becomes.

[0018] By adopting the above technical solution, the flow rate of the reaction gas at the necking hopper is reduced, so that the reaction gas has more time to mix in the necking hopper.

[0019] Optionally, a group of bucket pieces are provided at the opening at one end with a larger inner diameter of the necking bucket, and several bucket pieces are evenly distributed around the axis of the necking bucket. The bucket pieces are inclined, and the side of one bucket piece away from the opening with a smaller inner diameter of the necking bucket is opposite to an adjacent bucket piece, and all bucket pieces are fixedly connected with a connecting block.

[0020] By adopting the above technical solution, the reaction gas will first flow along the inclined surface of the bucket piece, so that the reaction gas will rotate to a certain extent around the axis of the necking bucket after passing through the bucket piece, and as the inner diameter of the necking bucket continues to decrease, the reaction gas can be more fully mixed in the necking bucket, and the reaction gas can also smoothly pass through the end with a smaller inner diameter of the necking bucket during a certain degree of rotation.

[0021] Optionally, two groups of inclined plates are provided inside the mixing tube on the side with a larger inner diameter of the necking bucket. The two groups of inclined plates are staggered, and the side of the inclined plates away from the inner wall of the mixing tube is away from the necking bucket. The projections of the two groups of inclined plates on the necking bucket overlap.

[0022] By adopting the above technical solution, turbulence can be formed when the reaction gas flows through the inclined plate in the mixing tube, thereby further improving the mixing degree between the reaction gases.

[0023] Optionally, the exhaust pipe is connected to an upper pipe located above the distribution pipe, the length direction of the upper pipe is consistent with the length direction of the distribution pipe, and the air inlet of the upper pipe is away from the distribution pipe.

[0024] By adopting the above technical solution, since the reaction product is a mixed gas such as hydrogen and has a low density, it will flow to the upper part of the tubular furnace when it is produced. Therefore, the air inlet of the upper tube is facing away from the distribution tube, so that the upper tube can fully and timely extract the reaction product while not easily extracting the reaction gas.

[0025] Optionally, a sedimentation trough is formed inside the upper tube, and several inner slots connected to the exhaust pipe are opened on the side surface around the sedimentation trough. The part of the inner slot connected to the sedimentation trough is inclined, and the closer the inclined section of the inner slot is to the sedimentation trough, the lower the height is. An inclined section plate is provided on the inner wall of the inclined section of the inner slot, and the inclined section plate is perpendicular to the inclination direction of the inclined section of the inner slot. There is a distance between the inclined section plate and the upper surface of the inclined section of the inner slot.

[0026] By adopting the above technical solution, during the process of vacuuming the upper tube, amorphous silicon may be deposited at the air inlet of the upper tube and form larger particles that are sucked into the upper tube. The larger amorphous silicon particles will fall into the sedimentation tank, and the medium particles may be carried by the airflow into the inner slot. The inclined inner slot reduces the possibility of the medium particles being carried by the airflow to move synchronously, and the presence of the inclined section plate blocks the medium particles, thereby minimizing the possibility of amorphous silicon particles of a certain volume entering the external vacuum pump.

[0027] In summary, this application has at least one of the following beneficial effects:

[0028] 1. The reaction gas and the silicon wafer are in good contact, and the distribution pipe can evenly transport the reaction gas along the length of the graphite boat, so that the silicon wafer and the reaction gas have sufficient contact, and the amorphous silicon film deposited by the reaction of the reaction gas can be deposited evenly on the surface of the silicon wafer;

[0029] 2. The upper tube can fully and timely extract the reaction products while not easily extracting the reaction gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the main structure of this application;

[0031] Figure 2 It is a cross-sectional view at one end of a distribution pipe in the longitudinal direction, and a schematic structural diagram of a cross-sectional view of a mixing pipe;

[0032] Figure 3 It is a schematic diagram of the cross-sectional structure at one end of the upper tube in the length direction.

[0033] Explanation of the accompanying reference numerals: 1. Inlet pipe; 2. Exhaust pipe; 3. Distribution pipe; 31. Connecting block; 32. Sedimentation trough; 33. Inner notch; 34. Inclined plate; 35. Grid; 4. Orifice plate; 41. Air hole; 42. Distribution leaf; 43. Upper pipe; 44. Left branch pipe; 45. Right branch pipe; 46. Mixing pipe; 47. Narrowing bucket; 48. Inclined plate; 49. Bucket plate. DETAILED DESCRIPTION

[0034] The present application is further described in detail below with reference to the accompanying drawings.

[0035] The present application discloses a gas supply and exhaust system for a tubular CVD device. Figure 1 , including an air inlet pipe 1 connected to an external gas tank to feed reaction gas into the tubular furnace, the air inlet pipe 1 is located in the tubular furnace and is detachably connected at one end and is connected to a distribution pipe 3, the distribution pipe 3 is horizontal, and the length direction of the distribution pipe 3 is consistent with the length direction of the graphite boat, an air outlet is provided on the bottom surface of the distribution pipe 3 and faces the upper part of the graphite boat, the distribution pipe 3 is provided with a number of distribution pipes 3 along its own width direction and according to the width of the graphite boat and the inner diameter of the tubular furnace, and the distribution pipes 3 are preferably an even number, and two are provided in this embodiment, and an exhaust pipe 2 connected to an external vacuum pump is provided in the tubular furnace, the exhaust pipe 2 is connected to an upper pipe 43 located just above the space between the two distribution pipes 3, the air inlet of the upper pipe 43 faces upward, and the air inlet height of the upper pipe 43 is higher than the air outlet height of the distribution pipe 3.

[0036] Reference Figure 1 and Figure 2 Several intake pipes 1 are evenly spaced along the length of each distribution pipe 3. Each intake pipe 1 includes a left branch pipe 44, a right branch pipe 45, and a mixing pipe 46. The left branch pipe 44 and the right branch pipe 45 each input reactant gas into the intake pipe 1. The bottom ends of the left branch pipe 44 and the right branch pipe 45 are connected to opposite sides of the upper end of the mixing pipe 46. The left branch pipe 44, the right branch pipe 45, and the mixing pipe 46 are arranged in a Y-shape, allowing the reactant gases fed into the mixing pipe 46 by the left branch pipe 44 and the right branch pipe 45 to undergo preliminary mixing. The mixing pipe 46 is vertical and has a rectangular horizontal cross-section. Two sets of inclined blades 48 are fixedly connected to the inner wall of the mixing pipe 46. The two sets of inclined blades 48 are staggered, with the inclined upper ends of the inclined blades 48 close to the vertical centerline of the mixing pipe 46. The projections of the two sets of inclined blades 48 on the horizontal plane overlap, allowing the reactant gases to mix further as they pass through the inclined blades 48.

[0037] Reference Figure 2 A conical inner wall of the bottom end of the mixing tube 46 is fixedly connected to a conical inner wall of the conical bottom end of the mixing tube 46. The inner diameter of the bottom end of the conical bottom end of the mixing tube 46 is smaller than the inner diameter of the upper end of the conical bottom end of the mixing tube 46. At the same time, the difference in the inner diameters at both ends of the conical bottom end of the mixing tube 46 will not be too large to avoid affecting the normal circulation of the reaction gas. The inner wall of the upper end of the necking bucket 47 is evenly fixed with several bucket pieces 49 around the axis of its own inner wall. The bucket pieces 49 are inclined and the inclined side of the bucket piece 49 is connected to the inner wall of the necking bucket 47. The side of the bucket piece 49 with a higher height is located directly above the adjacent bucket piece 49. The similar inclined sides of all the bucket pieces 49 are fixedly connected with the same connecting piece 31. The axis of the connecting piece block 31 is consistent with the axis of the necking bucket 47. The radius of the connecting piece block 31 is less than or equal to half the inner diameter of the inner wall of the bottom end of the necking bucket 47. The reaction gas will first enter the necking bucket 47 along the inclined surface of the bucket piece 49 with a certain degree of rotation, so that the reaction gas can complete the final mixing before being sent out from the necking bucket 47.

[0038] Reference Figure 2 Several horizontal orifice plates 4 are fixedly connected to the inside of the distribution pipe 3 in the vertical direction. There are at least three orifice plates 4. All of the orifice plates 4 are penetrated by vertical air holes 41. The higher the orifice plate 4, the larger the inner diameter of the air holes 41 and the more sparse they are. The air holes 41 of two adjacent orifice plates 4 are staggered, so that the reaction gas is more uniform when it is delivered from the air holes 41 of the orifice plate 4 with the lowest height, which helps to make the amount of reaction gas delivered from each outlet of the distribution pipe 3 more uniform. The projections of the two ends of the graphite boat in the length direction on the distribution pipe 3 are located between the two ends of the gas outlet in the length direction of the distribution pipe 3. At the same time, a group of distribution leaves 42 can be detachably connected to the inner walls of the gas outlets of the two distribution pipes 3. Each group of distribution leaves 42 is evenly distributed in the width direction of the distribution pipe 3. The side surfaces of each group of distribution leaves 42 in the width direction are inclined, and the parts of each group of distribution leaves 42 on both sides of the center point of the distribution pipe 3 are mirrored with the vertical center plane in the length direction of the distribution pipe 3. The distance between the two farthest bottom ends of each group of distribution leaves 42 is the largest, and the inclination of each group of distribution leaves 42 is gradually changed along the width direction of the distribution pipe 3, so that the reaction gas sent out from the distribution pipe 3 can be diffused to the two sides of the length direction of the distribution pipe 3, thereby improving the uniformity of the reaction gas amount in various parts of the graphite boat.

[0039] Reference Figure 1 and Figure 3The length of the upper tube 43 is consistent with that of the distribution tube 3, and the air inlet of the upper tube 43 is directly opposite the highest point of the inner wall of the tube furnace. A sedimentation trough 32 is provided inside the upper tube 43. The sedimentation trough 32 penetrates the upper surface of the upper tube 43 to form the air inlet of the upper tube 43. A grid 35 is detachably connected to the upper opening of the sedimentation trough 32. Internal notches 33 are evenly provided on the four vertical inner walls of the sedimentation trough 32. Several internal notches 33 can be evenly provided on the inner wall along the length of the sedimentation trough 32 as needed, and only one internal notch 33 can be provided on the inner wall along the width of the sedimentation trough 32. The end of the internal notch 33 away from the sedimentation trough 32 is connected to the exhaust pipe 2. Corresponding exhaust pipes 2 are provided on the four vertical side surfaces of the upper tube 43. This prevents some larger amorphous silicon particles at the air inlet of the upper tube 43 from being carried into the sedimentation trough 32 by the airflow and then from entering the internal notch 33. The portion of the inner notch 33 near the sedimentation trough 32 is inclined, with the end of the inner notch 33 connected to the sedimentation trough 32 being the lowest point. The two vertical inner walls and the inclined bottom surface of the inner notch 33 are fixedly connected to a single inclined plate 34. The inclined plate 34 is perpendicular to the inclination direction of the inclined section of the inner notch 33. A large gap exists between the inclined plate 34 and the inclined inner upper surface of the inclined section of the inner notch 33, making it difficult for medium-sized amorphous silicon particles to be blocked as they flow along the inclined lower surface of the inclined section of the inner notch 33 with the gas. Furthermore, the portion of the inner notch 33 connected to the highest point of its own inclined section is vertical, further reducing the possibility of larger particles passing through the inner notch 33 and entering the exhaust pipe 2.

[0040] The implementation principle of the air intake and exhaust system of a tubular CVD device in an embodiment of the present application is as follows: the reaction gas is sent into the mixing tube 46 through the left branch pipe 44 and the right branch pipe 45 for layer-by-layer mixing, and then sent into the distribution pipe 3. Through several orifice plates 4 and distribution leaves 42, the distribution pipe 3 can first deliver uniform reaction gas to various places on the upper part of the graphite boat. When the reaction gas itself is at a lower temperature than the temperature in the tubular furnace, it first sinks through the silicon wafers on the graphite boat. Then, as the temperature rises and subsequent reaction gas is continuously fed in, the previous reaction gas continues to rise to contact the silicon wafers again, so that the reaction gas can fully contact the silicon wafers, and the reaction exhaust gas rises to the top of the tubular furnace, so that the upper tube 43 can extract the exhaust gas in time.

[0041] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A gas supply and exhaust system for a tubular CVD device, comprising an inlet pipe (1) connected to a tubular furnace and used for feeding reaction gas and an exhaust pipe (2) for extracting reaction products, characterized in that: The air inlet pipe (1) is located in the tube furnace and is connected to a distribution pipe (3) at one end. The length direction of the opening of the distribution pipe (3) is consistent with the length direction of the graphite boat. Several distribution pipes (3) are set along their own width direction. The air outlet of the distribution pipe (3) faces the upper part of the graphite boat. The air inlet of the exhaust pipe (2) is located above the air outlet of the distribution pipe (3). The air outlet of the distribution pipe (3) is provided with a group of several distribution leaves (42). The distribution leaves (42) close to the two ends of the width direction of the distribution pipe (3) in the same group are inclined. The distribution leaves (42) located on both sides of the center point of the distribution pipe (3) in the same group are close to the sides of the orifice plate (4) and the distribution leaves (42) at the middle position of the same group. The exhaust pipe (2) is connected to the distribution pipe (3). ), the length direction of the upper tube (43) is consistent with the length direction of the distribution tube (3), the air inlet of the upper tube (43) is away from the distribution tube (3), a sedimentation trough (32) is formed inside the upper tube (43), and a plurality of inner notches (33) connected to the exhaust pipe (2) are provided on the peripheral side of the sedimentation trough (32), and the portion of the inner notch (33) connected to the sedimentation trough (32) is inclined, and the closer the inclined section of the inner notch (33) is to the sedimentation trough (32), the lower the height is, and the inner wall of the inclined section of the inner notch (33) is provided with an inclined section plate (34), which is perpendicular to the inclined direction of the inclined section of the inner notch (33), and there is a distance between the inclined section plate (34) and the upper surface of the inclined section of the inner notch (33).

2. The gas supply and exhaust system of a tubular CVD device according to claim 1, characterized in that: A group of the air inlet pipes (1) is provided corresponding to each distribution pipe (3), and each group of the air inlet pipes (1) is evenly distributed along the length direction of the distribution pipe (3). A perforated plate (4) is provided inside the distribution pipe (3), and a plurality of air holes (41) are opened through the perforated plate (4) to allow the reaction gas fed by the air inlet pipe (1) to be discharged from the air outlet of the distribution pipe (3).

3. The gas supply and exhaust system of a tubular CVD device according to claim 2, characterized in that: The orifice plates (4) are provided in plurality, and the air holes (41) of two adjacent orifice plates (4) are staggered. The orifice plates (4) closer to the air outlet of the distribution pipe (3) have smaller diameters of the air holes (41), and the air holes (41) on the orifice plates (4) closer to the air outlet of the distribution pipe (3) are denser.

4. The gas supply and exhaust system of a tubular CVD device according to claim 2, characterized in that: Each of the air inlet pipes (1) comprises a left branch pipe (44), a right branch pipe (45) and a mixing pipe (46); the left branch pipe (44) and the right branch pipe (45) are connected to the mixing pipe (46); the mixing pipe (46) is connected to the distribution pipe (3); and the mixing pipe (46), the left branch pipe (44) and the right branch pipe (45) are arranged in a Y shape.

5. The gas supply and exhaust system of a tubular CVD device according to claim 4, characterized in that: A constriction bucket (47) is coaxially provided inside the mixing tube (46), and the closer the constriction bucket (47) is to the opening at one end of the distribution tube (3), the smaller the inner diameter of the constriction bucket (47) becomes.

6. The gas supply and exhaust system of a tubular CVD device according to claim 5, characterized in that: A group of bucket pieces (49) are provided at the opening of one end with a larger inner diameter of the shrinking bucket (47). Several bucket pieces (49) are evenly distributed around the axis of the shrinking bucket (47). The bucket pieces (49) are inclined. The side of one bucket piece (49) away from the opening with a smaller inner diameter of the shrinking bucket (47) is directly opposite to an adjacent bucket piece (49). All bucket pieces (49) are fixedly connected to a connecting block (31).

7. The gas supply and exhaust system of a tubular CVD device according to claim 5, characterized in that: Two groups of inclined plates (48) are provided inside the mixing tube (46) at the side with a larger inner diameter of the constricting bucket (47). The two groups of inclined plates (48) are staggered. The side of the inclined plates (48) away from the inner wall of the mixing tube (46) is away from the constricting bucket (47), and the projections of the two groups of inclined plates (48) on the constricting bucket (47) overlap.

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