Coating equipment

Abstract

A coating device comprises a furnace tube and a pair of boat foot electrodes. The furnace tube comprises a film coating cavity, and the film coating cavity is used for containing a graphite boat used for bearing a film coating workpiece. And the pair of boat foot electrodes are arranged in the coating cavity. Each boat foot electrode comprises a combination surface used for being in contact with a graphite boat. And the sealing ring is fixedly arranged on the combination surface and extends to form a closed ring shape. When the boat foot of the graphite boat abuts against the combination face, a closed space is formed between the boat foot and the sealing ring. The sealing ring can be made of graphite or other high-temperature-resistant materials with certain elasticity, reaction gas in the film coating cavity is prevented from entering a space formed by combining the boat foot electrode and the graphite boat, and a film layer is prevented from being deposited in the area, surrounded by the sealing ring, of the boat foot electrode.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic material processing, and more specifically to a coating device. Background Art

[0002] During the production and processing of solar cells, silicon wafers are often coated with plasma-enhanced chemical vapor deposition (PECVD). This coating process utilizes a graphite boat. Multiple silicon wafers are inserted into the boat and then pushed into the chamber of the PECVD vacuum coating equipment, where plasma chemical vapor deposition (PECVD) takes place, forming the desired film layer on the wafer surface. After coating, the boat is removed and the wafers are unloaded. Plasma generation is crucial in the PECVD coating process. Plasma is formed when a gas is ionized by an electric field. It possesses high energy and activity, promoting the decomposition of reactants and the progression of chemical reactions. A high-frequency alternating electric field or direct current (DC) is typically applied to the reaction chamber to ionize the gas and form the plasma.

[0003] In existing PECVD vacuum coating equipment, when two or more graphite boats are placed, a boat foot electrode is usually provided corresponding to the graphite boat near the furnace mouth. The boat foot electrode contacts the boat foot of the graphite boat, so that the graphite boat is energized to generate an electric field, thereby ionizing the gas to form plasma. The boat foot electrode has a surface that is in contact with the boat foot of the graphite boat. As the coating equipment is used for a longer time, the surface where the boat foot electrode contacts the boat foot is easily coated with unnecessary film layers, such as silicon nitride film. The insulating silicon nitride film causes the resistance of the boat foot electrode to increase, which easily generates high-voltage discharge and causes power fluctuations. Therefore, the service life of the boat foot electrode at the furnace mouth is short and generally needs to be replaced every half a month. Replacing the boat foot electrode requires cooling the PECVD vacuum coating. Frequent cooling and heating can easily cause the furnace tube to rupture and reduce the service life of the entire machine. Utility Model Content

[0004] In view of this, the present application provides a coating device having a boat foot electrode with a special structure to extend the service life of the boat foot electrode.

[0005] A coating device, comprising:

[0006] A furnace tube, comprising a coating cavity for accommodating a graphite boat for carrying a coating workpiece;

[0007] a pair of boat foot electrodes, disposed in the coating chamber, each of the boat foot electrodes comprising a bonding surface for contacting the graphite boat;

[0008] The sealing ring is fixedly arranged on the joint surface and extends into a closed ring shape.

[0009] When the boat foot rests against the mating surface, a sealed space is formed between the boat foot and the sealing ring. The sealing ring, which can be made of graphite or other high-temperature resistant materials, prevents reactive gases in the coating chamber from entering the space formed by the boat foot electrode and the graphite boat, thus preventing film deposition in the area surrounding the boat foot electrode and the sealing ring.

[0010] In some embodiments, the coating equipment further includes an air pipe, which extends from the outside of the furnace tube into the coating cavity, and a gas channel is provided in the boat foot electrode, the inlet of the gas channel is connected to the air pipe, and the exhaust port of the gas channel is provided on the joint surface and surrounded by the sealing ring.

[0011] In some embodiments, a conductive boss is provided on the bonding surface of the boat foot electrode, the boss is surrounded by the sealing ring and spaced apart from the sealing ring, and the boss is used to contact the graphite boat.

[0012] In some embodiments, a flange is provided at the furnace port of the furnace tube, and the gas pipe is led out from the flange and extends into the coating cavity.

[0013] In some embodiments, the sealing ring and the boss are protruded from the mating surface, and the thickness of the sealing ring is greater than the height of the boss, wherein the thickness of the sealing ring is the distance between the surface of the sealing ring facing away from the mating surface and the mating surface, and the height of the boss is the distance between the surface of the boss facing away from the mating surface and the mating surface.

[0014] In some embodiments, a groove that is recessed relative to the joint surface is formed on the joint surface, and the sealing ring and the boss are both disposed in the groove.

[0015] In some embodiments, the groove includes a bottom wall and a side wall connected to the bottom wall, the side wall is connected between the bottom wall and the joint surface; the sealing ring is arranged on the bottom wall, and the sealing ring extends along the side wall; the boss is protruding from the bottom wall.

[0016] In some embodiments, the depth of the groove relative to the mating surface is less than the thickness of the sealing ring, and the thickness of the sealing ring is greater than the height of the boss, wherein the thickness of the sealing ring is the distance between the surface of the sealing ring facing away from the bottom wall and the bottom wall, and the height of the boss is the distance between the surface of the boss facing away from the bottom wall and the bottom wall.

[0017] In some embodiments, two support rods are further provided in the coating chamber, and the two support rods are used to support the graphite boat. The pair of boat foot electrodes are fixedly provided on the two support rods, and each support rod is provided with one boat foot electrode.

[0018] In some embodiments, the boat foot electrode is provided with a through hole, and the support rod passes through the through hole so that the boat foot electrode is sleeved on the support rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a coating device according to an embodiment of the present application.

[0020] Figure 2 This is a schematic diagram of the coating equipment according to an embodiment of the present application without the furnace tube.

[0021] Figure 3 for Figure 2 A partially enlarged schematic diagram of the coating equipment.

[0022] Figure 4 Schematic diagram of the boat foot electrode of the coating equipment.

[0023] Description of main component symbols:

[0024] 100. Coating equipment; 10. Furnace tube; 20. Graphite boat; 101. Coating chamber; 11. Support rod; 30. Boat foot electrode; 31. Joint surface; 40. Sealing ring; 21. Boat foot; 50. Air pipe; 501. Exhaust port; 60. Boss; 301. Through hole; 302. Groove; 60. Boss; 70. Cable; 80. Flange. DETAILED DESCRIPTION

[0025] The coating equipment of the present application prevents the reaction gas in the coating chamber from entering the bonding area between the boat foot electrode and the graphite boat by arranging a conductive sealing ring on the surface where the boat foot electrode and the graphite boat are bonded, and by arranging an air pipe to introduce nitrogen and other gases into the boat foot electrode area, thereby effectively avoiding the deposition of unnecessary film layers, such as insulating films, in the bonding area between the upper boat foot electrode and the graphite boat, thereby effectively extending the service life of the boat foot electrode and avoiding frequent replacement of the boat foot electrode.

[0026] The coating equipment of this application is a PECVD vacuum coating equipment. Figure 1As shown, the coating apparatus 100 includes a furnace tube 10. The furnace tube 10 is hollow and tubular, forming a tubular coating chamber 101. The coating chamber 101 is used to accommodate at least one graphite boat 20, each of which is used to carry multiple coating workpieces (e.g., silicon wafers). This application uses the example of a coating chamber 101 that can accommodate two graphite boats 20. The two graphite boats 20 are spaced apart along the length of the furnace tube 10. The furnace tube 10 has two opposing ends along its length, forming a furnace opening and a furnace tail, respectively, and the graphite boats 20 enter through the furnace opening. Figure 1 Only the positions of some components in the coating chamber 101 are schematically presented, without involving the specific structures of some components.

[0027] like Figure 1 and Figure 2 As shown, two support rods 11 are installed in the coating chamber 101 to support the graphite boat 20. The two support rods 11 are parallel and spaced apart. Each support rod 11 extends along the length of the furnace tube 10 from the furnace entrance to the furnace tail. The graphite boat 20 is pushed into the coating chamber 101 and positioned on the two support rods 11. The two support rods 11 cooperate to support the graphite boat 20. The bottom of the graphite boat 20 includes boat feet 21.

[0028] like Figure 1 and Figure 2 As shown, the coating apparatus 100 further includes a pair of boat electrodes 30 disposed in the coating chamber 101. The two boat electrodes 30 of the pair of boat electrodes 30 are spaced apart from each other. One of the two boat electrodes 30 acts as a positive electrode and the other acts as a negative electrode. In addition, the positive and negative electrodes can be switched to each other to form a radio frequency alternating electric field.

[0029] The boat foot electrode 30 is in block shape and is made of conductive material as a whole to play a conductive role. Figure 3 As shown, the boat foot electrode 30 is used to contact and connect with the graphite boat 20. Specifically, the boat foot electrode 30 is used to contact and connect with the boat foot 21 of the graphite boat 20 to energize the graphite boat 20. Generally, the boat foot electrode 30 is installed on the graphite boat 20 near the furnace mouth, while the graphite boats 20 in other areas are not equipped with boat foot electrodes 30. Instead, other methods are used to energize the graphite boat 20 to form an electric field, such as pin electrodes.

[0030] like Figure 4As shown, the boat foot electrode 30 includes a surface facing the graphite boat 20, which is used to contact and connect with the graphite boat 20 (boat foot 21), defined as a bonding surface 31. In the present application, a sealing ring 40 is fixedly mounted on the bonding surface 31, extending to form a closed ring. The sealing ring 40 is used to connect and seal between the boat foot 21 and the boat foot electrode 30. When the graphite boat 20 is supported on the support rod 11, the boat foot 21 abuts against the bonding surface 31, forming a closed space between the boat foot 21 and the sealing ring 40.

[0031] The material of the sealing ring 40 is high temperature resistant and has a certain elasticity, for example, it can be graphite, which prevents the reaction gas in the coating chamber 101 from entering the closed space formed by the boat foot electrode 30 and the graphite boat 20, thereby preventing the film from being deposited in the area surrounded by the sealing ring 40. The boat foot electrode 30 is fixed on the support rod 11. A boat foot electrode 30 is provided on each support rod 11. The boat foot electrodes 30 on the two support rods 11 are arranged at relative intervals. In the embodiment of the present application, Figure 4 As shown, the boat electrode 30 is provided with a through hole 301, and the support rod 11 passes through the through hole 301 so that the boat electrode 30 is sleeved on the support rod 11. It is understandable that the way of fixing the boat electrode 30 on the support rod 11 is not limited to this, and other fixing methods can also be used.

[0032] Although not shown, the graphite boat 20 comprises a first portion and a second portion, which are joined together to form the graphite boat 20. Boat legs 21 are formed on each of the first and second portions. One of the two boat leg electrodes 30 is connected to the first portion, while the other of the two boat leg electrodes 30 is connected to the second portion. An insulating material, such as insulating ceramic, may be placed between the first and second portions to prevent electrical conduction between the two portions. This allows different potentials to be applied to the first and second portions of the graphite boat 20 via the pair of boat leg electrodes 30, thereby forming an electric field.

[0033] like Figure 3 and Figure 4 As shown, the coating equipment 100 further includes an air pipe 50. The air pipe 50 extends from the furnace port into the coating chamber 101 and is connected to the boat foot electrode 30. The air pipe 50 is used to introduce nitrogen or other inert gases.

[0034] In some embodiments, a gas channel (not shown) is defined within the boat foot electrode 30 and communicates with the gas tube 50. The inlet of the gas channel communicates with the gas tube 50, and the outlet of the gas channel serves as an exhaust port 501. The exhaust port 501 is located within the joint surface 31 and is surrounded by the sealing ring 40. A portion of the gas tube 50 may be inserted into the boat foot electrode 30, but this is not a limitation.

[0035] When the graphite boat 20 is pressed onto the boat foot electrode 30, nitrogen is introduced through the gas pipe 50 to fill the enclosed space surrounded by the sealing ring 40 and the boat foot 21 with nitrogen. This can effectively prevent the external reaction gas from penetrating into the enclosed space surrounded by the sealing ring 40 and the boat foot 21, thereby preventing the area of ​​the boat foot electrode 30 surrounded by the sealing ring 40 from being coated with a film layer, such as an insulating silicon nitride film.

[0036] In the embodiment of the present application, the air inlet of the gas pipe 50 is located at the furnace mouth. The gas pipe 50 is positioned adjacent to the support rod 11, and at least the portion of the gas pipe 50 that exposes the boat electrode 30 extends along the length of the furnace tube 10. In other words, a portion of the gas pipe 50 is positioned parallel to the support rod 11. In some embodiments, the gas pipe 50 may be made of, but is not limited to, stainless steel.

[0037] The pressure of the gas ejected from the exhaust port 501 does not exceed the pre-tightening force between the sealing ring 40 and the boat leg 21. The incoming gas (nitrogen) fills the narrow space between the sealing ring 40 and the boat leg 21, preventing trace amounts of reactive gas from leaking in from outside the sealing ring 40. This significantly extends the service life of the furnace port boat leg electrode 30.

[0038] like Figure 4 As shown, the boat electrodes 30 are also connected to cables 70 to power the boat electrodes 30. Each boat electrode 30 is connected to a different cable 70. The cables 70 extend from the furnace opening into the coating chamber 101 and are located on the side of the gas pipe 50 away from the support rod 11, but the specific location can be adjusted according to needs.

[0039] like Figure 4 As shown, a boss 60 is provided on the mating surface 31 of the boat foot electrode 30. The boss 60 is surrounded by the sealing ring 40 and spaced apart from the sealing ring 40. The exhaust port 501 is located between the boss 60 and the sealing ring 40. The boss 60 is made of a conductive material. In some embodiments, the boss 60 and the boat foot electrode 30 are integrally formed of a conductive material, but this is not limited to this. The boss 60 is used to contact and connect with the boat foot 21 of the graphite boat 20 to conduct electricity. The boss 60 can effectively enhance the contact between the graphite boat 20 and the boat foot electrode 30.

[0040] like Figure 4 As shown in the embodiment of the present application, a groove 302 is provided on the bonding surface 31 of the boat foot electrode 30, which is recessed relative to the bonding surface 31. The sealing ring 40 and the boss 60 are both disposed in the groove 302. Figure 4As shown, groove 302 includes a bottom wall (not shown) and side walls (not shown) connected to the bottom wall. The side walls are connected between the bottom wall and the joint surface 31. A sealing ring 40 is disposed on the bottom wall and extends along the side walls of groove 302. In this embodiment, the sealing ring 40 extends in contact with the side walls. Therefore, the shape of the sealing ring 40 remains the same as the shape enclosed by the side walls. In this embodiment, the groove 302 is rectangular, corresponding to the extension of the sealing ring 40 into a rectangular ring. A boss 60 is provided protruding from the bottom wall.

[0041] The exhaust port 501 is provided on the bottom wall of the groove 302 and is located between the boss 60 and the sealing ring 40. The boss 60 is also provided in the groove 302. Specifically, the boss 60 is provided protrudingly on the bottom wall.

[0042] In some embodiments, the depth of the recessed groove 302 relative to the mating surface 31 is slightly less than the thickness of the sealing ring 40. Specifically, the sealing ring 40 slightly protrudes from the recessed groove 302 in a direction perpendicular to the mating surface 31, allowing the graphite boat 20 to press against the sealing ring 40 within the recessed groove 302. Furthermore, the thickness of the sealing ring 40 is slightly greater than the height of the boss 60. The thickness of the sealing ring 40 is defined as the distance between the surface of the sealing ring 40 facing away from the bottom wall and the bottom wall, while the height of the boss 60 is defined as the distance between the surface of the boss 60 facing away from the bottom wall and the bottom wall. Because the sealing ring 40 is made of a softer material than the boss 60, when the graphite boat 20 presses against the boat foot electrode 30, the sealing ring 40 is squeezed and compressed to a certain extent, reducing its thickness. This allows the graphite boat 20 to precisely abut against the boss 60, thereby increasing the contact area between the boat foot 21 of the graphite boat 20 and the boat foot electrode 30. In some embodiments, the height of the boss 60 is consistent with the depth of the recessed groove 302, and the top surface of the boss 60 is flush with the mating surface 31.

[0043] In other embodiments, the bonding surface 31 may be a flat surface without the groove 302, and the sealing ring 40 and the boss 60 are both protruded from the bonding surface 31. The thickness of the sealing ring 40 is slightly greater than the height of the boss 60, where the thickness of the sealing ring 40 is the distance between the surface of the sealing ring 40 facing away from the bonding surface 31 and the bonding surface 31, and the height of the boss 60 is the distance between the surface of the boss 60 facing away from the bonding surface 31 and the bonding surface 31. Because the material of the sealing ring 40 is softer than that of the boss 60, when the graphite boat 20 is pressed against the boat foot electrode 30, the sealing ring 40 is squeezed and compressed to a certain extent, reducing its thickness. In this way, the graphite boat 20 just abuts against the boss 60, thereby increasing the contact area between the boat foot 21 of the graphite boat 20 and the boat foot electrode 30.

[0044] A flange 80 is provided at the furnace mouth of the furnace tube 10 , and the starting ends of components such as the support rod 11 , the air pipe 50 , and the cable 70 are all provided on the flange 80 , thereby extending from the furnace mouth toward the coating cavity 101 .

[0045] With the use of coating equipment, although some film layers will be deposited on the surfaces of the boat foot electrode 30 other than the bonding surface 31, as long as there is no film layer deposition in the area where the boat foot electrode 30 is bonded to the boat foot 21, it will not affect the power supply of the boat foot electrode 30 to the graphite boat 20.

[0046] The coating equipment of the present application prevents gas from entering the surface where the boat foot 21 of the graphite boat 20 contacts the boat foot electrode 30 by providing a sealing ring 40 on the boat foot electrode 30 at the furnace mouth. In addition, a conductive boss 60 is provided in the middle of the sealing ring 40 to enhance the contact connection between the graphite boat 20 and the boat foot electrode 30. In addition, the boat foot electrode 30 is connected to the air pipe 50, and the exhaust port 501 is provided in the area surrounded by the sealing ring 40. Nitrogen and other gases are introduced through the air pipe 50. Nitrogen can fill the narrow space between the sealing ring 40 and the boat foot 21, preventing trace amounts of reaction gas from penetrating from the outside of the sealing ring 40 and forming a film layer on the boat foot electrode 30. In this way, the service life of the boat foot electrode 30 can be effectively extended, and frequent replacement of the boat foot electrode 30 can be avoided.

[0047] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application should not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A coating device, characterized in that: include: A furnace tube, comprising a coating cavity for accommodating a graphite boat for carrying a coating workpiece; a pair of boat foot electrodes, disposed in the coating chamber, each of the boat foot electrodes comprising a bonding surface for contacting the graphite boat; A sealing ring, fixedly arranged on the joint surface and extending into a closed ring shape; When the boat foot of the graphite boat is pressed against the joint surface, a closed space is formed between the boat foot and the sealing ring.

2. The coating equipment according to claim 1, characterized in that: The coating equipment also includes an air pipe, which extends from the outside of the furnace tube into the coating cavity. A gas channel is provided in the boat foot electrode, the inlet of the gas channel is connected to the air pipe, and the exhaust port of the gas channel is provided on the joint surface and surrounded by the sealing ring.

3. The coating equipment according to claim 1, characterized in that: A conductive boss is provided on the joint surface of the boat foot electrode. The boss is surrounded by the sealing ring and spaced apart from the sealing ring. The boss is used to contact the graphite boat.

4. The coating equipment according to claim 2, characterized in that: A flange is provided at the furnace port of the furnace tube, and the air pipe is led out from the flange and extends in the coating cavity.

5. The coating equipment according to claim 3, characterized in that: The sealing ring and the boss are protruding from the mating surface, and the thickness of the sealing ring is greater than the height of the boss, wherein the thickness of the sealing ring is the distance between the surface of the sealing ring facing away from the mating surface and the mating surface, and the height of the boss is the distance between the surface of the boss facing away from the mating surface and the mating surface.

6. The coating equipment according to claim 3, characterized in that: A groove that is recessed relative to the joint surface is formed on the joint surface, and the sealing ring and the boss are both arranged in the groove.

7. The coating equipment according to claim 6, characterized in that: The groove includes a bottom wall and a side wall connected to the bottom wall, wherein the side wall is connected between the bottom wall and the joint surface; the sealing ring is arranged on the bottom wall and extends along the side wall; the boss is convexly arranged on the bottom wall.

8. The coating equipment according to claim 7, characterized in that: The depth of the groove relative to the mating surface is less than the thickness of the sealing ring, and the thickness of the sealing ring is greater than the height of the boss, wherein the thickness of the sealing ring is the distance between the surface of the sealing ring away from the bottom wall and the bottom wall, and the height of the boss is the distance between the surface of the boss away from the bottom wall and the bottom wall.

9. The coating equipment according to claim 1, characterized in that: Two support rods are further provided in the coating chamber, and the two support rods are used to support the graphite boat. The pair of boat foot electrodes are fixedly provided on the two support rods, and one boat foot electrode is provided on each support rod.

10. The coating equipment according to claim 9, characterized in that: The boat foot electrode is provided with a through hole, and the support rod passes through the through hole so that the boat foot electrode is sleeved on the support rod.

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