Double-layer furnace tube structure

Abstract

The double-layer furnace tube structure is provided with a furnace mouth and a furnace tail which are oppositely arranged, the double-layer furnace tube structure comprises an inner tube and an outer tube, and the outer tube is arranged outside the inner tube in a sleeving mode; the inner pipe is hermetically connected with one end of the outer pipe at the furnace mouth, the inner pipe is partially hermetically connected with one end of the outer pipe at the furnace tail, and the pressure between the inner pipe and the outer pipe is lower than that of the inner pipe; at one end of the furnace mouth, a gas inlet is formed between the inner pipe and the outer pipe; and an auxiliary vacuumizing opening is formed between the inner pipe and the outer pipe at one end of the furnace tail. Gas can enter the position between the inner pipe and the outer pipe from the end close to the furnace tail, meanwhile, inert gas is blown through the gas inlet located at the furnace opening end, the auxiliary vacuumizing opening located at the furnace tail end is used for vacuumizing, and therefore the gas entering the position between the inner pipe and the outer pipe can be rapidly exhausted; further, the deposition speed of residual SiH4 in the gas on the inner tube and the outer tube can be reduced, the service life of the double-furnace tube structure is prolonged, and the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of manufacturing solar crystalline silicon cells, and in particular to a double-layer furnace tube structure. Background Art

[0002] Low-pressure chemical vapor deposition (LPCVD) technology is primarily used in the photovoltaic field for thin-film growth. It can be used for growing films such as intrinsic amorphous silicon, doped amorphous silicon, and silicon oxide, particularly in the manufacture of crystalline silicon solar cells. LPCVD technology relies on a heating device as a heat source to maintain the reaction. It offers excellent step coverage, precise control of composition and structure, high deposition rates and throughput, and significantly reduces particle contamination sources. These characteristics give LPCVD equipment significant advantages in photovoltaic manufacturing.

[0003] Conventional LPCVD tube furnace equipment has air intake at the furnace mouth and a vacuum pump connected to the furnace tail. During the gas flow, it will not be completely deposited on the boat and silicon wafer surface. The remaining SiH4 in the gas will deposit polysilicon film on the inner wall of the quartz tube. With the increase in the number of processes and gas uniformity issues, these films thicken and the rates at different positions are also different. The accumulated thickness over time is very considerable.

[0004] However, as the thickness of the polysilicon film deposited on the inner wall of the quartz tube increases, and due to the different thermal expansion coefficients of polysilicon and quartz, the quartz tube may break when the temperature is increased or decreased, thereby reducing its service life and increasing operating costs. Utility Model Content

[0005] Based on this, it is necessary to provide a double-layer furnace tube structure to address the problem of short life of quartz tubes during use.

[0006] A double-layer furnace tube structure, the double-layer furnace tube structure having a furnace mouth and a furnace tail arranged opposite to each other, the double-layer furnace tube structure comprising an inner tube and an outer tube, the outer tube being sleeved outside the inner tube;

[0007] The inner tube is sealedly connected to the outer tube at one end located at the furnace mouth, and the inner tube is sealedly connected to the outer tube at one end located at the furnace tail, and the pressure between the inner tube and the outer tube is lower than the pressure of the inner tube;

[0008] A gas inlet is provided between the inner tube and the outer tube at one end of the furnace mouth; an auxiliary vacuum port is provided between the inner tube and the outer tube at one end of the furnace tail.

[0009] In one embodiment, the inner tube has a silicon carbide layer, and the silicon carbide layer is located on a side away from the outer tube.

[0010] In one embodiment, the double-layer furnace tube structure includes a furnace tail end face flange, the outer tube is located at one end of the furnace tail and is sealedly connected to the furnace tail end face flange, and a support ring is provided between the inner tube at one end of the furnace tail and the furnace tail end face flange, and a notch is provided on the support ring.

[0011] In one embodiment, the opening angle of the notch is 15°-45°.

[0012] In one embodiment, the notch faces the auxiliary vacuum port.

[0013] In one embodiment, a groove is provided in the furnace tail end flange, one end of the inner tube located at the furnace tail extends into the groove, and the support ring is arranged between the inner wall of the groove and the outer wall of the inner tube.

[0014] In one embodiment, the gas inlet and the auxiliary vacuum port are arranged diagonally.

[0015] In one embodiment, the double-layer furnace tube structure includes a furnace mouth water-cooling flange and a furnace mouth support flange that are threaded together. The furnace mouth water-cooling flange is sleeved on the outside of the outer tube. A first sealing groove is provided on the outside of the end of the furnace mouth water-cooling flange away from the furnace tail. A first sealing component is provided in the first sealing groove. The furnace mouth support flange is located at the end of the outer tube away from the furnace tail. The furnace mouth support flange is used to press the first sealing component into the first sealing groove.

[0016] In one embodiment, a second sealing groove is provided on the inner wall of the center hole of the furnace mouth support flange, a second sealing member is provided in the second sealing groove, and the furnace mouth support flange is sealed to the outer wall of the inner tube through the second sealing member.

[0017] In one embodiment, the double-layer furnace tube structure includes a furnace tail water-cooling flange and a furnace tail end face flange that are threadedly connected. The furnace tail water-cooling flange is sleeved on the outside of the outer tube. A third sealing groove is opened on the outside of the end of the furnace tail water-cooling flange away from the furnace mouth. A third sealing component is arranged in the third sealing groove. The furnace tail end face flange is located at the end of the outer tube away from the furnace mouth. The furnace tail end face flange is used to press the third sealing component into the third sealing groove.

[0018] In the above-mentioned double-layer furnace tube structure, a silicon wafer is placed within an inner tube, and the furnace mouth end of the inner tube is used to introduce SiH4 gas to deposit a silicon thin film on the surface of the silicon wafer. The inner tube and the outer tube are partially sealed and connected at one end near the furnace tail. At the same time, the pressure between the inner and outer tubes is lower than that of the inner tube, that is, gas can enter between the inner and outer tubes from the end near the furnace tail. At the same time, the gas inlet located at one end of the furnace mouth is blown with inert gas, and the auxiliary vacuum port located at one end of the furnace tail is evacuated, thereby allowing the gas entering between the inner and outer tubes to be quickly discharged. Specifically, the present application first allows gas to be quickly discharged between the inner and outer tubes, and then quickly discharged from between the inner and outer tubes to the outside of the double-layer furnace tube structure. This further reduces the deposition rate of residual SiH4 in the gas on the inner and outer tubes, thereby extending the service life of the double-layer furnace tube structure and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the double-layer furnace tube structure in one embodiment.

[0020] Figure 2 Schematic diagram of the cross section of the furnace tail end face flange in one embodiment.

[0021] Figure markings: 110, inner tube; 120, outer tube; 210, furnace mouth; 220, furnace mouth water-cooling flange; 221, first seal; 230, furnace mouth support flange; 231, second seal; 232, gas inlet; 233, fourth seal; 310, furnace tail; 320, furnace tail water-cooling flange; 321, third seal; 330, furnace tail end face flange; 331, support ring; 3311, notch; 332, main vacuum port; 333, first film gauge; 334, auxiliary vacuum port; 335, second film gauge; 400, furnace door; 420, paddle. DETAILED DESCRIPTION

[0022] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0023] In the description of this application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0024] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0025] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc., should be interpreted broadly. For example, these terms may refer to fixed connections, removable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0026] In this application, unless otherwise expressly specified or limited, if a first feature is described as being "above" or "below" a second feature, or similar descriptions, this may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is described as being "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is described as being "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0027] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only embodiment.

[0028] See Figure 1 and Figure 2 A double-layer furnace tube structure is provided in one embodiment of the present application. The double-layer furnace tube structure has a furnace mouth 210 and a furnace tail 310 arranged opposite to each other. The double-layer furnace tube structure includes an inner tube 110 and an outer tube 120, and the outer tube 120 is sleeved outside the inner tube 110; the inner tube 110 and the outer tube 120 are sealed and connected at one end of the furnace mouth 210, and the inner tube 110 and the outer tube 120 are partially sealed and connected at one end of the furnace tail 310, and the pressure between the inner tube 110 and the outer tube 120 is lower than the pressure of the inner tube 110; a gas inlet 232 is opened between the inner tube 110 and the outer tube 120 at one end of the furnace mouth 210; and an auxiliary vacuum port 334 is opened between the inner tube 110 and the outer tube 120 at one end of the furnace tail 310.

[0029] In this embodiment, a silicon wafer is placed within an inner tube 110. The furnace port 210 of the inner tube 110 is used to introduce SiH4 gas to deposit a silicon thin film on the surface of the silicon wafer. The inner tube 110 and the outer tube 120 are partially sealed and connected at one end located at the furnace tail 310. The pressure between the inner and outer tubes 110, 120, is lower than that of the inner tube 110 itself. This allows gas to enter the space between the inner and outer tubes 110, 120, from the end near the furnace tail 310. Simultaneously, an inert gas is blown through the gas inlet 232 located at one end of the furnace port 210, and a vacuum is drawn through the auxiliary vacuum port 334 located at one end of the furnace tail 310. This allows any gas that has entered the space between the inner and outer tubes 110, 120 to be quickly expelled. That is, the present application can firstly allow the gas to be quickly discharged into between the inner tube 110 and the outer tube 120, and then quickly discharged from between the inner tube 110 and the outer tube 120 to the outside of the double-layer furnace tube structure, thereby reducing the deposition rate of the remaining SiH4 in the gas on the inner tube 110 and the outer tube 120, extending the service life of the double-layer furnace tube structure, and reducing production costs.

[0030] In addition, the inner tube 110 and the outer tube 120 are partially sealed and connected at one end of the furnace tail 310, and the auxiliary vacuum port 334 is located at one end of the furnace tail 310, that is, the gas entering between the inner tube 110 and the outer tube 120 is close to the auxiliary vacuum port 334, which facilitates the rapid extraction of the gas through the auxiliary vacuum port 334, thereby reducing the residence time of the gas between the inner tube 110 and the outer tube 120 and reducing the movement path of the gas between the inner tube 110 and the outer tube 120, thereby reducing the deposition of the remaining SiH4 in the gas on the inner wall of the outer tube 120 or the outer wall of the inner tube 110.

[0031] Specifically, the inert gas may be nitrogen gas which is relatively cheap.

[0032] In some embodiments, the inner tube 110 has a silicon carbide layer, which is located on a side away from the outer tube 120 .

[0033] In this embodiment, the inner tube 110 can be made entirely of silicon carbide, or a silicon carbide layer can be provided on the side of the inner tube 110 away from the outer tube 120. Silicon carbide is chemically stable and has heat resistance, corrosion resistance, and wear resistance. In actual testing, the inner wall of a silicon carbide tube coated with a polysilicon film exhibits greater stress resistance than a quartz tube. Therefore, the silicon carbide layer located on the side away from the outer tube 120 can extend the service life of the inner tube 110, and thereby extend the service life of the entire double-layer furnace tube structure.

[0034] In some embodiments, the double-layer furnace tube structure includes a furnace tail end face flange 330, the outer tube 120 is located at one end of the furnace tail 310 and is sealedly connected to the furnace tail end face flange 330, and the inner tube 110 is located at one end of the furnace tail 310 and is provided with a support ring 331 between the furnace tail end face flange 330, and a notch 3311 is opened on the support ring 331.

[0035] In this embodiment, the end of the outer tube 120 located at the furnace tail 310 is sealed to the furnace tail end face flange 330, thereby preventing gas that has entered between the inner tube 110 and the outer tube 120 from leaking out of the outer tube 120. A support ring 331 is provided between the end of the inner tube 110 located at the furnace tail 310 and the furnace tail end face flange 330. The support ring 331 has a notch 3311, allowing the remaining gas in the inner tube 110 to enter between the inner tube 110 and the outer tube 120 through the notch 3311.

[0036] Specific, combined Figure 2 The opening angle α of the notch 3311 is 15°-45°.

[0037] In this embodiment, when the opening angle α of the notch 3311 is less than 15°, it is difficult for gas to be quickly discharged from the notch 3311 to the space between the inner tube 110 and the outer tube 120, which can easily cause gas to be deposited in the inner tube 110. In addition, it is also easy for gas to enter the space between the inner tube 110 and the outer tube 120 from the end near the furnace opening 210, extending the gas movement path between the inner tube 110 and the outer tube 120. When the opening angle α of the notch 3311 is greater than 45°, it is easy for unreacted gas to directly enter the space between the inner tube 110 and the outer tube 120 through the notch 3311, affecting the quality of thin film deposition.

[0038] In some embodiments, the notch 3311 faces the auxiliary vacuum port 334 .

[0039] The notch 3311 faces the auxiliary vacuum port 334 , thereby facilitating rapid discharge of gas entering between the inner tube 110 and the outer tube 120 from the auxiliary vacuum port 334 .

[0040] In some other embodiments, there are multiple notches 3311, which are spaced apart. Each notch 3311 faces the corresponding auxiliary vacuum port 334, and the total opening angle of the multiple notches 3311 is 15°-45°.

[0041] In some other embodiments, two adjacent notches 3311 may face one auxiliary vacuum port 334 at the same time, and the total opening angle of the plurality of notches 3311 may be 15°-45°.

[0042] In some embodiments, a groove is defined in the furnace tail end flange 330 , one end of the inner tube 110 located at the furnace tail 310 extends into the groove, and the support ring 331 is disposed between the inner wall of the groove and the outer wall of the inner tube 110 .

[0043] In this embodiment, the support ring 331 provides a sealing function. It is positioned between the outer wall of the inner tube 110 and the inner wall of the groove, sealing a portion of the inner tube 110 and the inner wall of the groove. A notch 3311 is defined on one side of the support ring 331. The support ring 331 is positioned within the groove, allowing gas within the inner tube 110 to flow through the notch 3311 within the groove to the space between the inner tube 110 and the outer tube 120.

[0044] In some embodiments, the gas inlet 232 and the auxiliary vacuum port 334 are disposed diagonally.

[0045] In this embodiment, the gas inlet 232 and the auxiliary vacuum port 334 are arranged diagonally, which facilitates blowing all the gas diffused between the inner tube 110 and the outer tube 120 toward the auxiliary vacuum port 334, which is beneficial for blowing the gas between the inner tube 110 and the outer tube 120 clean.

[0046] In some embodiments, the double-layer furnace tube structure includes a furnace mouth water-cooling flange 220 and a furnace mouth support flange 230 that are threaded together. The furnace mouth water-cooling flange 220 is sleeved on the outside of the outer tube 120. A first sealing groove is opened on the outside of the end of the furnace mouth water-cooling flange 220 away from the furnace tail 310. A first sealing member 221 is arranged in the first sealing groove. The furnace mouth support flange 230 is located at the end of the outer tube 120 away from the furnace tail 310. The furnace mouth support flange 230 is used to press the first sealing member 221 into the first sealing groove.

[0047] In this embodiment, the first sealing ring is provided to simultaneously achieve sealing between the outer tube 120 and the furnace mouth water-cooling flange 220 and the furnace mouth support flange 230, thereby preventing the gas entering between the inner tube 110 and the outer tube 120 from leaking from between the outer tube 120 and the furnace mouth water-cooling flange 220 or the furnace mouth support flange 230.

[0048] Furthermore, a second sealing groove is opened on the inner wall of the center hole of the furnace mouth support flange 230 , and a second sealing member 231 is provided in the second sealing groove. The furnace mouth support flange 230 is sealedly connected to the outer wall of the inner tube 110 through the second sealing member 231 .

[0049] By providing the second sealing member 231 , a sealed connection between the inner tube 110 and the furnace opening support flange 230 can be achieved.

[0050] A furnace door 400 is provided at one end of the inner tube 110 close to the furnace mouth 210, and a paddle 420 is fixedly installed on the furnace door 400. The paddle 420 is used as a supporting fixture for the silicon wafer, and is used to accommodate the silicon wafer in the inner tube 110 for the deposition process. At the same time, the furnace door 400 is connected to an automated mechanism, which can realize the linear movement of the furnace door 400 and the paddle 420, driving the silicon wafer in and out of the reaction chamber.

[0051] A fourth sealing groove is formed at one end of the furnace mouth support flange 230 away from the furnace tail 310 , in which a fourth sealing member 233 is provided. When the furnace door 400 is closed, the fourth sealing member 233 can be compressed to seal the inner tube 110 .

[0052] In some embodiments, the double-layer furnace tube structure includes a threaded furnace tail water-cooling flange 320 and a furnace tail end face flange 330. The furnace tail water-cooling flange 320 is sleeved on the outside of the outer tube 120. A third sealing groove is opened on the outside of the end of the furnace tail water-cooling flange 320 away from the furnace mouth 210. A third sealing member 321 is arranged in the third sealing groove. The furnace tail end face flange 330 is located at the end of the outer tube 120 away from the furnace mouth 210. The furnace tail end face flange 330 is used to press the third sealing member 321 into the third sealing groove.

[0053] Furthermore, the provision of the third sealing member 321 enables a sealed connection between the outer tube 120 and the furnace tail end flange 330. A main vacuum port 332 is provided within the furnace tail water-cooling flange 320. The main vacuum port 332 is connected to a vacuum system for extracting gas from the inner tube 110 to reduce the process pressure within the inner tube 110.

[0054] The main vacuum port 332 is provided with a first butterfly valve and a first diaphragm gauge 333. The first diaphragm gauge 333 is used to detect the pressure of the inner tube 110 and thereby control the opening of the first butterfly valve. The auxiliary vacuum port 334 is provided with a second butterfly valve and a second diaphragm gauge 335. The second diaphragm gauge 335 is used to detect the pressure between the inner tube 110 and the outer tube 120 and thereby control the opening of the second butterfly valve.

[0055] The support ring 331, the first sealing member 221, the second sealing member 231, the third sealing member 321 and the fourth sealing member 233 are all sealing rings, metal sealing gaskets or liquid silicone. A heating wire and a heat-insulating layer are provided on the outer surface of the outer tube 120.

[0056] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A double-layer furnace tube structure, characterized in that: The double-layer furnace tube structure has a furnace mouth and a furnace tail arranged opposite to each other, and the double-layer furnace tube structure includes an inner tube and an outer tube, and the outer tube is sleeved outside the inner tube; The inner tube is sealedly connected to the outer tube at one end located at the furnace mouth, and the inner tube is sealedly connected to the outer tube at one end located at the furnace tail, and the pressure between the inner tube and the outer tube is lower than the pressure of the inner tube; A gas inlet is provided between the inner tube and the outer tube at one end of the furnace mouth; an auxiliary vacuum port is provided between the inner tube and the outer tube at one end of the furnace tail.

2. The double-layer furnace tube structure according to claim 1, characterized in that: The inner tube has a silicon carbide layer located on a side remote from the outer tube.

3. The double-layer furnace tube structure according to claim 1, characterized in that: The double-layer furnace tube structure includes a furnace tail end face flange, one end of the outer tube located at the furnace tail is sealedly connected to the furnace tail end face flange, and a support ring is provided between one end of the inner tube located at the furnace tail and the furnace tail end face flange, and a notch is opened on the support ring.

4. The double-layer furnace tube structure according to claim 3, characterized in that: The opening angle of the notch is 15°-45°.

5. The double-layer furnace tube structure according to claim 3, characterized in that: The notch faces the auxiliary vacuum port.

6. The double-layer furnace tube structure according to claim 3, characterized in that: A groove is provided in the furnace tail end flange, one end of the inner tube located at the furnace tail extends into the groove, and the support ring is arranged between the inner wall of the groove and the outer wall of the inner tube.

7. The double-layer furnace tube structure according to claim 1, characterized in that: The gas inlet and the auxiliary vacuum port are arranged diagonally.

8. The double-layer furnace tube structure according to claim 1, characterized in that: The double-layer furnace tube structure includes a furnace mouth water-cooling flange and a furnace mouth supporting flange that are threaded together. The furnace mouth water-cooling flange is sleeved on the outside of the outer tube. A first sealing groove is provided on the outside of the end of the furnace mouth water-cooling flange away from the furnace tail. A first sealing member is provided in the first sealing groove. The furnace mouth supporting flange is located at the end of the outer tube away from the furnace tail. The furnace mouth supporting flange is used to press the first sealing member into the first sealing groove.

9. The double-layer furnace tube structure according to claim 8, characterized in that: A second sealing groove is provided on the inner wall of the center hole of the furnace port support flange. A second sealing member is provided in the second sealing groove. The furnace port support flange is sealed and connected to the outer wall of the inner tube via the second sealing member.

10. The double-layer furnace tube structure according to claim 1, characterized in that: The double-layer furnace tube structure includes a furnace tail water-cooling flange and a furnace tail end face flange that are threadedly connected. The furnace tail water-cooling flange is sleeved on the outside of the outer tube. A third sealing groove is opened on the outside of the end of the furnace tail water-cooling flange away from the furnace mouth. A third sealing component is arranged in the third sealing groove. The furnace tail end face flange is located at the end of the outer tube away from the furnace mouth. The furnace tail end face flange is used to press the third sealing component into the third sealing groove.

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