Vertical furnace tube

Abstract

The invention discloses a vertical furnace tube, which comprises a furnace body, which is a vertical heat insulation barrel with a sealed upper end and a furnace mouth at the lower end, and is provided with a heater; the heat-resisting sheet group comprises a plurality of groups of heat-resisting sheets which are arranged in parallel, and the adjacent heat-resisting sheets are connected through connecting bodies; the heat insulation sheets are perpendicular to the axial direction of the furnace body and are arranged in the axial direction of the furnace body, and part of the heat insulation sheets are located in the furnace body. The heat insulation sheets comprise a heat radiation heat insulation sheet and a heat conduction heat insulation sheet, and the heat radiation heat insulation sheet is located in the furnace body. According to the vertical furnace tube, the heat insulation effect on the furnace mouth is relatively good.

Description

Technical Field

[0001] The invention relates to a vertical furnace tube, which is also called a vertical tube furnace. Background Art

[0002] In the semiconductor manufacturing process, vertical furnace tubes are a very commonly used high-temperature (working temperature is usually between 427°C and 1200°C. With the development of technology, the maximum working temperature of some vertical furnace tubes has reached 2000°C, and the continuous working temperature can reach 1900°C) process equipment. They can perform important process steps such as alloy annealing, oxidation diffusion, LPCVD, ALD, high-temperature oxidation, annealing activation, etc. The process steps provided by the furnace equipment usually account for 25% of the total steps in chip production.

[0003] Compared with the horizontal structure, the vertical structure has the advantages of compact structure, high equipment integration, high degree of automation, and advanced process technology. Therefore, as a furnace tube equipment, thermal field design is the most important part of equipment manufacturing and process realization. The design of the furnace mouth insulation part and the insulation components involves the transmission and entry and exit of materials, and there will inevitably be temperature leakage. On the one hand, it is hoped that the furnace mouth can be as short as possible so that the equipment height can be reduced. On the other hand, it is hoped that the furnace mouth temperature can be maintained to obtain a better constant temperature zone. The structural design and material selection of this part are very critical.

[0004] The insulation methods of vertical furnace tubes mainly include two main forms: furnace body insulation and furnace mouth insulation. Among them, furnace body insulation is relatively easy to achieve because it is a completely static insulation, while the furnace mouth needs to consider the entry and exit of materials, and has higher insulation requirements. At present, the focus of vertical furnace tube insulation research is also mainly on furnace mouth insulation.

[0005] The traditional vertical furnace mouth insulation is relatively simple, mainly using ceramic fiber furnace plugs to support the process boat or furnace plugs with insulation cotton and aluminum silicate blocks around the edge to support the process boat. The process boat supported by the furnace plug is placed upward into the furnace tube, and the furnace plug and the furnace mouth of the furnace tube are sealed by mechanical cooperation. This method is a simple isolation insulation measure, which generally uses new materials or thickening to improve the overall insulation capacity, and is relatively bulky as a whole.

[0006] In order to improve the overall thermal insulation capacity of the furnace mouth, a multi-stage thermally insulated vertical furnace tube has emerged. This type of vertical furnace tube generally has multiple groups of thermal insulation sheets in the axial direction of the furnace tube, and each group has multiple thermal insulation sheets. The thermal insulation sheets are arranged parallel to each other, and the thermal insulation sheet at the top supports the process boat. The thermal insulation sheets are generally supported in sequence by support rods to form a thermal insulation sheet group. The thermal insulation sheets in the thermal insulation sheet group are evenly arranged, and thermal insulation boards of the same material are usually used. This type of vertical furnace tube is insulated step by step by means of heat transfer span, so it has a better thermal insulation effect than traditional furnace mouth insulation measures.

[0007] The inventors believe that regarding thermal insulation, the technical conception of traditional furnace mouth thermal insulation has certain limitations. Such traditional furnace mouth thermal insulation mainly considers thermal conductivity isolation. However, there are two other forms of heat exchange, namely thermal convection and thermal radiation. Only thermal conduction is considered without considering the other two forms, and the control of heat exchange is not targeted, thus affecting the overall thermal insulation effect. Summary of the invention

[0008] The object of the present invention is to provide a vertical furnace tube with relatively good heat insulation effect on the furnace mouth.

[0009] In an embodiment of the present invention, a vertical furnace tube is provided, comprising: The furnace body is a vertical heat-insulating barrel body with a sealed upper end and a furnace mouth at the lower end, and is provided with a heater; The heat insulation sheet group is a plurality of heat insulation sheets arranged in parallel, and adjacent heat insulation sheets are connected by a connector; the heat insulation sheets are perpendicular to the axial direction of the furnace body and arranged in the axial direction of the furnace body, and some of the heat insulation sheets are located in the furnace body; The heat insulation sheet is divided into heat radiation heat insulation sheet and heat conduction heat insulation sheet, among which the heat radiation heat insulation sheet is located in the furnace body.

[0010] Optionally, a first spacing between adjacent thermal radiation insulation sheets is smaller than a second spacing between adjacent thermal conduction insulation sheets.

[0011] Optionally, the first spacing is 0.38 to 0.63 times the second spacing.

[0012] Optionally, the second spacing is 25-31 mm.

[0013] Optionally, some of the heat-conducting and heat-insulating sheets are located in the furnace body, and the number of the heat-conducting and heat-insulating sheets located in the furnace body is not less than one.

[0014] Optionally, the number of thermal radiation insulation sheets is not less than seven and not more than fifteen; The number of thermal conductive insulation sheets is 0.8 to 1.2 times the number of thermal radiation insulation sheets.

[0015] Optionally, the thermal radiation insulation sheet is a quartz sheet, a silicon carbide sheet, a graphite sheet or a graphite composite sheet; The heat-conducting and heat-insulating sheet is a quartz sheet, a variant quartz sheet, a bubble quartz sheet or a quartz wool sheet.

[0016] Optionally, it also includes an inner tube and an outer tube that are nested; The outer tube is partially exposed from the furnace mouth, and in the working state, the inner tube is partially exposed from the mouth of the outer tube; A fixing flange is provided for supporting the inner tube and the heat insulation sheet assembly; Accordingly, the heat insulation sheet group is located inside the inner tube.

[0017] Optionally, the fixed flange has a flange plate and a cylinder extending upward from the flange plate; A ring-shaped lower support for supporting the inner tube is provided in the middle of the cylinder; An upper support platform for engaging with the lower edge of the outer tube is provided at the upper end of the cylinder.

[0018] Optionally, the fixing flange is a metal flange; The flange has an upward convex portion, and a heat-conducting and heat-insulating plate with a given thickness is provided on the upper surface of the convex portion; The thickness of the heat-conducting insulation board is greater than the thickness of the heat-conducting insulation sheet.

[0019] According to the vertical furnace tube of the embodiment of the present invention, there are multiple groups of heat insulation plates used to close the furnace body and furnace mouth. The heat insulation plates in the heat insulation plate group are perpendicular to the axis of the furnace body and are arranged along the axis of the furnace body to form a thermal isolation zone at the furnace mouth. Some of the heat insulation plates are heat radiation heat insulation plates, and the remaining heat insulation plates are heat conductive heat insulation plates. The heat radiation heat insulation plates are located inside the furnace body, and all or most of the remaining heat insulation plates are located outside the furnace body. After research, the inventor found that by using the heat insulation plate group arranged as above, the heat radiation heat insulation plates located in the furnace can effectively suppress the heat radiation in the high temperature section (relative concept). Since there are multiple heat radiation heat insulation plates, the heat radiation can be reduced step by step. At the same time, it should be known that no matter what kind of thermal insulation sheet, it has conventional thermal conductivity and insulation capabilities. In other words, the thermal insulation sheet with thermal radiation isolation capability also has thermal conductivity and insulation capabilities. The temperature is gradually reduced from the inside to the outside, and then enters the low temperature zone (relative to the aforementioned high temperature section), and then directly uses a thermal insulation sheet with stronger thermal conductivity and insulation capabilities and no requirements for thermal radiation, mainly to enhance the thermal conductivity and insulation capabilities. Through the above configuration, different thermal insulation boards are adaptively configured according to the changes in the temperature field from the inside to the outside of the furnace mouth, and a better thermal insulation effect is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the vertical furnace tube structure in one embodiment.

[0021] Figure 2 for Figure 1 AA section view Figure 3 for Figure 2 A magnified view of part I.

[0022] In the figure: 1. fixed flange, 2. bottom insulation board, 3. outer tube, 4. inner tube, 5. process sheet boat, 6. connecting column, 7. furnace body, 8. inner cavity, 9. outer cavity, 10. furnace, 11. process sheet, 12. constant temperature section, 13. first insulation sheet, 14. second insulation sheet, 15. lower support platform, 16. surrounding shell, 17. upper support platform, 18. flange. DETAILED DESCRIPTION

[0023] It should be known that the furnace tube is usually a barrel-type structure. For the vertical furnace tube, the furnace mouth is at the lower end, and the upper end of the furnace body 7 of the corresponding furnace tube is equivalent to the bottom of the barrel. For the furnace body 7, its own thermal insulation is easy to achieve and is not the focus of current research. For the insulation of the vertical furnace tube, the current research focus is on the furnace mouth.

[0024] Based on the above structure, it can be known that the furnace body 7 has a definite top and bottom, and also because the furnace body 7 is basically a rotating body, it has a definite axial direction, which is the up and down direction of the furnace body 7.

[0025] When the axial direction is determined, the radial and circumferential directions are also determined.

[0026] In addition, for the furnace body 7, the space determined by it can be called a furnace chamber or furnace 10, which is a process space used to place, for example, wafers therein for, for example, heat treatment. As mentioned earlier, heat treatment has extremely high requirements on the fluctuation amplitude of process temperature, and the furnace body 7 itself has a relatively good thermal insulation effect, thereby placing very high requirements on the sealing of the furnace mouth.

[0027] exist Figure 2 In the illustrated structure, most of the space in the furnace 10 is Figure 2 The constant temperature section 12 shown in the figure is the process chamber section of the vertical furnace tube, and process sheets such as wafers are located in the process chamber section when the vertical furnace tube is in working state. The temperature of the process chamber section is relatively high, as mentioned above, usually greater than or equal to 427°C. Relatively speaking, the surface temperature of the fixed flange 1 in the figure is usually lower than 45°C. Obviously, the temperature drops from 427°C to 45°C gradually, rather than suddenly. In the embodiment of the present invention, the heat insulation sheet group is used as the heat insulation body to gradually reduce the temperature of the furnace mouth step by step.

[0028] It should be noted that, for heat exchange, the isolation or insulation measures of the furnace mouth, although they have the purpose of preventing burns to operators, their main purpose is to reduce the heat exchange inside and outside the furnace body 7, thereby Figure 2 The temperature fluctuation of the constant temperature section 12 shown in FIG. 1 is within the expected range.

[0029] In addition, from the perspective of the temperature field of cooling, it must be high inside and low outside, and gradually decreases outward in the axial direction of the furnace body 7 at the furnace mouth.

[0030] The vertical furnace tube generally includes four basic parts, namely the furnace body 7, the temperature control system, the gas control system and the heating element. Since these four basic parts do not involve the modification of the present invention, the four basic parts are briefly described below without detailed description.

[0031] The furnace body 7 is easy to achieve thermal insulation because it is a static structure. The outer shell of the furnace body is mostly a metal shell, and an insulation lining is arranged inside the outer shell. The insulation lining can be made of inorganic materials such as alumina fiber. The heating element is generally fixed inside the insulation lining. It should be known that the internal space of the furnace 10 is generally a cylindrical space. The heating elements are generally evenly distributed inside the furnace 10. Generally, alloy wire (resistance wire as a whole, and the corresponding heating element is an electric heating element) is used as the heating element, such as Cr 27 Al7Mo2.

[0032] Uniformly arranged heating elements are beneficial in Figure 2 The constant temperature section 12 shown forms a relatively balanced temperature field. What needs to be controlled is mainly the sealing of the furnace mouth and the control of the temperature field, so as to reduce the heat exchange between the furnace body 7 and the furnace mouth, and maintain a smaller fluctuation in the constant temperature section 12.

[0033] As for gas control, it is basically irrelevant to the concept of the present invention and will not be described here. Since the initial temperature of the working gas is relatively low, PID technology is generally used to comprehensively adjust the working temperature of the constant temperature section 12, and the control accuracy can reach ±1°C, which is a very mature technology. In other words, temperature control is also mainly reflected at the furnace mouth.

[0034] As a conventional configuration, a furnace cover is provided at the furnace mouth of the vertical furnace tube, and the focus of the embodiment of the present invention is the improvement of the furnace cover.

[0035] In addition to being a furnace opening sealing component, the furnace cover is generally also used as a supporting component for supporting, for example, a process sheet boat 5 , which in turn is used to support a process sheet 11 .

[0036] In an embodiment of the present invention, the furnace cover includes a seat portion such as a fixed flange 1, and a heat insulation plate group is provided on the seat portion. Regarding the configuration of the seat portion and the furnace mouth, reference can be made to the furnace mouth configuration of a known vertical furnace tube, or the specific examples in the embodiment of the present invention can be used.

[0037] Since the problem of material loading and unloading at the furnace mouth needs to be considered, the furnace cover is often designed to be relatively long (the axial dimension of the furnace body 7) so that the cooperation between the furnace cover and the furnace mouth can achieve the desired insulation effect while meeting the conditions of material loading and unloading.

[0038] In the embodiment of the present invention, simply looking at Figure 2 In the illustrated structure, the furnace cover portion including the heat insulation sheet group is relatively large in the axial dimension of the furnace body 7. This is the price to pay for better heat insulation effect, which will be discussed in some embodiments below.

[0039] Figure 2 In the embodiment, the heat insulation sheet group includes a first heat insulation sheet 13, a second heat insulation sheet 14 and a bottom heat insulation board 2, and the total number of heat insulation sheets is Figure 2There are eighteen pieces in the illustrated structure, and they are arranged densely on top and sparsely on the bottom in the figure.

[0040] First, the basic arrangement of the heat insulation sheets in the heat insulation sheet group is parallel to each other, and the sheet structure has the characteristics of a surface, and can usually be directly described as a surface. In the embodiment of the present invention, the heat insulation sheet is perpendicular to the axial direction of the furnace body 7.

[0041] exist Figure 2 In the illustrated structure, the thermal insulation plates are connected in series using connecting columns 6. In order to reduce heat conduction, the thermal insulation plates can also be connected using pipes while ensuring the supporting stiffness. For example, quartz tubes and other tubes / columns with strong thermal insulation capabilities can be used for connection. Quartz also has a certain stiffness and can provide better support for the process boat 5.

[0042] For example, two to four quartz tubes / columns can be arranged to make the overall bearing capacity more stable and reduce the heat transfer area as much as possible. Under this condition, there is a certain span between the heat insulation sheets. Under the condition of the span, the heat transfer between them is mainly heat radiation. At the same time, due to the fact that the vertical furnace tube is hot on the top and cold on the bottom, heat convection is suppressed, or heat convection basically does not need to be considered. Therefore, in the embodiments of the present invention, heat radiation and heat conduction are mainly considered.

[0043] In this way, there is a span between adjacent insulation sheets, which is mainly used to reduce heat conduction. It should be known that air is a poor medium for heat conduction. Air, water, etc. will have heat convection. When heat convection is suppressed, the efficiency of air as a heat transfer medium is very low. Therefore, Figure 2 Although the spacing between the first heat insulating sheets 13 is relatively small, they still have heat conducting and heat insulating properties.

[0044] from Figure 2 As can be seen in the figure, the first heat insulation sheet 13 is located in the furnace 10. The first heat insulation sheet 13 is mainly used to suppress heat radiation and is referred to as the heat radiation heat insulation sheet hereinafter. Figure 2 As can be seen, the first heat-insulating sheet 13 has multiple sheets, and there is a certain distance between them. It is mainly made of opaque material to mainly suppress heat radiation.

[0045] In addition, according to analysis, the key factors affecting thermal radiation include transmittance, temperature difference, emissivity and distance. The worse the transmittance, the smaller the temperature difference and the smaller the emissivity. And the farther the distance, the worse the thermal radiation effect. Therefore, using multiple layers of low-transmittance or opaque materials to isolate radiated light can achieve better thermal insulation / heat preservation effects while suppressing thermal radiation.

[0046] The first heat insulation sheet 13 can be made of high-temperature resistant materials with poor transmittance or completely opaque, such as quartz sheets, silicon carbide sheets, graphite sheets, graphite composite sheets, etc. It should be known that the high-temperature resistance here depends on the temperature at the furnace mouth. The so-called high-temperature resistance must be the temperature at the furnace mouth, which is certain.

[0047] It should be noted that quartz sheets and silicon carbide sheets are materials with relatively small thermal conductivity, while graphite sheets, graphite composite sheets, etc. are materials with relatively large thermal conductivity. Based on the above content, it can be seen that the main function of the first thermal insulation sheet 13 is to suppress thermal radiation, rather than heat conduction. First, the temperature of the next step from top to bottom at the furnace mouth is reduced by suppressing thermal radiation, and then the second thermal insulation sheet 14 is introduced, which is conducive to the selection of the second thermal insulation sheet 14. It should be noted that there are currently vertical furnace tubes with an operating temperature of up to 2000°C. Quartz is already difficult to maintain a solid state at this operating temperature, but graphite is different. The melting point of graphite is extremely high, which will be described in more detail below.

[0048] In addition, the design of the number of layers and the spacing between sheets can provide better heat insulation and light blocking effects. Figure 2 In the illustrated structure, the first heat insulating sheets 13 have a first spacing, and are integrated into an assembly based on the connecting column 6 shown in the figure. The heat conducting part of the assembly, namely the connecting column 6, has a relatively small cross section, and the connecting column 6 can be made of, for example, a quartz rod, etc., which has poor thermal conductivity, so it can have a good thermal insulation effect as a whole. Even if it is made of a graphite rod, it can also suppress heat conduction due to its relatively small cross section.

[0049] In addition, a high temperature reflective coating is provided on the surface of the first heat insulation sheet 13 to obtain an ideal heat insulation and light shielding effect. Obviously, the high temperature here is still applicable to the content described above, that is, it is necessary to withstand the temperature at the furnace mouth.

[0050] For a relatively low temperature vertical furnace tube, the high temperature reflective coating may be, for example, a silver coating, which may be suitable for a vertical furnace tube with an operating temperature below 900°C.

[0051] If there are higher requirements for the working temperature, high-temperature heat-reflective insulation coatings such as ZS-233 (infrared reflectivity greater than 67%) can be used to make the reflective coating of the first insulation sheet 13. The working temperature of ZS-233 high-temperature heat-reflective insulation coating can reach 1800°C.

[0052] It can be seen that when a plurality of stacked first thermal insulation sheets 13 are used, heat radiation can be effectively suppressed based on high-temperature heat-reflective thermal insulation coatings such as ZS233.

[0053] At present, more and more high-temperature heat-reflective insulation coatings are appearing. Based on the above ideas, technicians in this field can make adaptive selections, which will not be elaborated here.

[0054] about Figure 2 The second thermal insulation sheet 14 shown in the figure is already in a relatively low temperature zone due to the presence of, for example, eight first thermal insulation sheets 13. However, the influence of thermal radiation can still be considered. Therefore, a reflective coating can also be provided on the surface of the second thermal insulation sheet 14.

[0055] include Figure 2 The second thermal insulation sheet 14 and the bottom thermal insulation board 2 shown in the example are both heat-conducting thermal insulation sheets. As mentioned above, under low temperature conditions, infrared rays are relatively weak, but it does not rule out providing a reflective coating or plating on the second thermal insulation sheet 14 to obtain a better thermal insulation effect.

[0056] However, it should be noted that the second heat insulating sheet 14 is exposed to a relatively low heat radiation in the working environment, and the emphasis is placed on suppressing heat conduction.

[0057] Heat conduction is also called heat transfer. The key factors of heat conduction include thermal conductivity, which is determined by the material, heat conduction path length / cross-sectional area, which is determined by the structure of the insulation component, and interface temperature difference, which is determined by the boundary conditions (i.e., temperature step). The smaller the thermal conductivity, the longer the heat conduction distance, the smaller the cross-sectional area, and the smaller the interface temperature difference, the smaller the heat exchange through heat conduction. Based on this principle, a multi-layer insulation sheet structure is constructed, such as Figure 2 The example in the figure shows a heat insulation sheet group with a certain heat conduction distance (i.e. the aforementioned span) formed by stacking multiple second heat insulation sheets 14. From the material aspect, the second heat insulation sheet 14 is mainly made of low thermal conductivity materials such as quartz, variant quartz, bubble quartz, high-purity quartz wool, etc.

[0058] Among them, the multi-layer stacking structure can increase the contact thermal resistance, and the second thermal insulation sheets 14 are connected by tubes / columns, which has a smaller heat conduction area and a smaller heat conduction amount; the thermal conductivity coefficient can be designed according to actual needs.

[0059] Regarding heat conduction, as mentioned above, the connection between the heat insulation sheets is, for example, a connecting column 6 or a connecting pipe, and the selection of the second heat insulation sheet 14 is also referred to above. It should be known that both quartz and variant quartz have relatively high strength, although different quartz properties may vary, for example, high-temperature quartz (β-quartz, milky white) and coesite still maintain high rigidity at 1713°C.

[0060] If the vertical furnace tube has a higher operating temperature, graphite rods or tubes can be used. Graphite is one of the most thermally stable solids in nature (3850±50℃). Even at a high temperature of 3000℃, graphite can still maintain a good shape, so it can be used in the production of refractory materials.

[0061] Relatively speaking, graphite has a relatively strong thermal conductivity. If graphite is used to make, for example, the connecting column 6, it can be used to connect the upper insulation sheets, and the connecting columns 6 between different insulation sheets are staggered.

[0062] Accordingly, as the temperature decreases from the inside to the outside, the connecting pillars 6 can be made of a material with a relatively low thermal conductivity but a relatively low temperature resistance, such as the aforementioned quartz.

[0063] Therefore, regarding the connecting column 6, it can be a multi-stage connecting column 6 made of different materials in the serial direction of the heat insulation sheet. Obviously, the connecting column 6 closer to the inside has a higher temperature tolerance requirement, and as mentioned above, the first heat insulation sheet 13 mainly considers the suppression of heat radiation, so the selection of the connecting column 6 requires a relatively low thermal conductivity. Even so, the connecting columns 6 used for connecting between the first heat insulation sheets 13 can also be staggered to minimize heat conduction.

[0064] As mentioned above, based on different considerations, the first spacing between adjacent thermal radiation insulation sheets is smaller than the second spacing between adjacent thermal conduction insulation sheets.

[0065] The first spacing mainly considers the suppression of heat radiation while taking into account heat conduction. At the same time, as mentioned above, the furnace cover should be as short as possible to make the vertical furnace tube more compact in height. Under this condition, the first spacing can be relatively small.

[0066] As for the second spacing, its design basis is mainly used to consider heat conduction, and there are higher requirements for the aforementioned span or heat conduction distance, taking into account heat radiation. Under this condition, the second spacing can be slightly larger.

[0067] In order to achieve both compactness and thermal insulation performance, the first spacing is 0.38 to 0.63 times the second spacing, preferably 0.54 times.

[0068] Furthermore, taking into account the effects of compactness and thermal insulation performance, the second spacing is 25-31 mm, preferably 28 mm.

[0069] Regarding the thickness of the thermal insulation sheet, both thermal insulation performance and strength can be taken into consideration. The thickness of the thermal insulation sheet is generally about 5 mm, generally not more than 10 mm, but generally not less than 4 mm.

[0070] As mentioned above, the first heat insulation sheet 13 is mainly used to suppress heat radiation and is entirely located inside the furnace mouth. As the temperature gradually decreases from the inside to the outside, the heat-conducting heat insulation sheet can be partially located outside the furnace body. Figure 2 It can be seen from the illustrated structure that most of the second heat insulating sheet 14 is located outside the furnace opening.

[0071] The second heat insulation sheet 14 located in the furnace mouth is mainly used to generate initial heat conduction. Based on the above description, it can be seen that although the main function of the first heat insulation sheet 13 is to suppress heat radiation, it also has a heat insulation effect. The main function of the second heat insulation sheet 14 is heat insulation. Arranging at least one second heat insulation sheet 14 in the furnace mouth helps to provide preliminary isolation for relatively high temperatures.

[0072] It should be known that the surface of the first second thermal insulation sheet 14 facing the furnace that is subjected to the impact of heat conduction often has the strongest thermal shock and the largest temperature gradient relative to the other surface. At the same time, under the comprehensive influence of the furnace wall, it can help reduce the overall temperature of the exposed part of the furnace cover.

[0073] It should be noted that since the main function of the first thermal insulation sheet 13 is to suppress thermal radiation, it can be made of a material with relatively high thermal conductivity, such as graphite, a material with good thermal conductivity but high temperature resistance, so as to directly withstand the erosion of the working temperature in the furnace chamber 10. For example, the current vertical furnace tube has an operating temperature of up to 2000°C, which quartz can no longer withstand. Graphite, a material with a melting point of up to 3850±50°C, is used to withstand high-temperature erosion. As thermal radiation is gradually suppressed, the second thermal insulation sheet 14 can be made of quartz or other materials with good thermal insulation properties but relatively low temperature resistance.

[0074] Considering that in some applications, such as those with an operating temperature higher than 1700°C, it is often necessary to use materials with relatively good thermal conductivity, such as the aforementioned graphite. The heat conduction between graphite sheets is mainly suppressed by a certain span. Under this condition, the number of the first heat insulation sheets 13 used as heat radiation insulation sheets is not less than seven. Under the condition of suppressing heat radiation, even if graphite with relatively good thermal conductivity is used, it has a certain ability to suppress heat conduction due to a certain span, so that the second heat insulation sheet 14 at the top is less susceptible to thermal erosion.

[0075] At the same time, considering the overall compactness, the number of the first heat-insulating sheets 13 should not be too many, preferably no more than fifteen.

[0076] exist Figure 2 In the illustrated structure, the number of first insulation sheets 13 and second insulation sheets 14 is roughly equal, and can be slightly more or slightly less. The number of second insulation sheets 14 used as heat-conducting insulation sheets is 0.8 to 1.2 times the number of first insulation sheets 13 used as thermal radiation insulation.

[0077] See also Figure 2 and Figure 3In the illustrated structure, in order to better construct the temperature field at the furnace mouth, in addition to the furnace body 7, two tubes are further provided, namely the inner tube 3 and the outer tube 4 shown in the figure. The inner tube 3 and the outer tube 4 can be made of different materials or the same material. The inner tube 3 and the outer tube 4 can be made of quartz, silicon carbide or graphite. Among them, as a process tube, the quartz tube can withstand an operating temperature of 1150°C, the silicon carbide tube can withstand an operating temperature of 1500°C, and the graphite tube can withstand an operating temperature of 2400°C.

[0078] The outer tube 3 may be fixedly arranged, and the inner tube 3 may be supported together with the heat insulation sheet assembly on, for example, a fixed flange 1 , so as to better construct the constant temperature section 12 .

[0079] exist Figure 2 and Figure 3 In the illustrated structure, the outer tube 3 is partially exposed from the furnace mouth, and in the working state, the inner tube 4 is partially exposed from the mouth of the outer tube 3; and a fixing flange 1 is provided for supporting the inner tube 4 and the insulation sheet assembly.

[0080] The sealing between the inner tube 4 and the outer tube 3 and the fixed flange 1 can be a joint seal, for example, the inner tube 4 is made of quartz, and its lower end surface is frosted, based on the fixed flange 1 made of metal, for example Figure 3 The table surface of the lower support platform 15 shown in the figure is joined to form a joint seal. This sealing method generates a joint force by means of the gravity of the inner tube 4 itself.

[0081] In addition, in order to expand the joint surface area between the lower end of the inner tube 4 and the surface of the lower support 15 , the lower end of the inner tube 4 has a flange 18 , and the lower end surface of the flange 18 is supported on the surface of the lower support 15 .

[0082] For the outer tube 3, the sealing structure can also be constructed in a substantially similar manner. Figure 3 In the illustrated structure, an upper support 17 is provided at the upper end of the fixed flange 1 for engaging with the outer tube 3. As mentioned above, the outer tube 3 can be fixedly disposed in the furnace body 7, and the engaging force between the upper support 17 and the outer tube 3 mainly comes from the upward supporting force applied to the fixed flange 1 from the bottom to the top.

[0083] In addition, the outer tube 3 and the fixed flange 1 can also be threadedly sealed, such as Figure 3 The outer edge of the middle upper support 17 extends upward to form a shell 16. While facilitating the positioning of the fixed flange 1 relative to the fixed outer tube 3, an internal thread can be set in the shell 16, while the outer tube 3 is set with an external thread. The two can be connected by threads to form a threaded seal.

[0084] In addition, the heat insulation sheet group is located in the inner tube 4 , and the process sheets 11 can be placed one by one on the process sheet boat 5 outside, and then covered with the inner tube 4 to form an assembly, and then placed together in the outer tube 3 .

[0085] In addition, if Figure 2 The fixed flange shown may be a water-cooled flange so that its surface temperature is relatively low to avoid accidents such as burns.

[0086] Figure 2 In the embodiment, the flange plate of the fixed flange has an upward convex portion, and a heat-conducting insulation plate with a given thickness is provided on the upper surface of the convex portion, such as Figure 2 The bottom insulation board 2 shown in the figure has a thickness greater than that of the heat-conducting insulation sheet, so as to provide relatively good basic isolation.

Claims

1. A vertical furnace tube, characterized in that: include: The furnace body is a vertical heat-insulating barrel body with a sealed upper end and a furnace mouth at the lower end, and is provided with a heater; The heat insulation sheet group is a plurality of heat insulation sheets arranged in parallel, and adjacent heat insulation sheets are connected by a connector; the heat insulation sheets are perpendicular to the axial direction of the furnace body and arranged in the axial direction of the furnace body, and some of the heat insulation sheets are located in the furnace body; The heat insulation sheet is divided into heat radiation heat insulation sheet and heat conduction heat insulation sheet, among which the heat radiation heat insulation sheet is located in the furnace body.

2. The vertical furnace tube according to claim 1, characterized in that: The first spacing between adjacent heat radiation insulation sheets is smaller than the second spacing between adjacent heat conduction insulation sheets.

3. The vertical furnace tube according to claim 2, characterized in that: The first spacing is 0.38 to 0.63 times the second spacing.

4. The vertical furnace tube according to claim 3, characterized in that: The second spacing is 25-31 mm.

5. The vertical furnace tube according to any one of claims 1 to 4, characterized in that: Some of the heat-conducting and heat-insulating sheets are located in the furnace body, and the number of the heat-conducting and heat-insulating sheets located in the furnace body is not less than one.

6. The vertical furnace tube according to any one of claims 1 to 4, characterized in that: The number of thermal radiation insulation sheets shall be no less than seven and no more than fifteen; The number of thermal conductive insulation sheets is 0.8 to 1.2 times the number of thermal radiation insulation sheets.

7. The vertical furnace tube according to claim 1, characterized in that: The thermal radiation insulation sheet is a quartz sheet, a silicon carbide sheet, a graphite sheet or a graphite composite material sheet; The heat-conducting and heat-insulating sheet is a quartz sheet, a variant quartz sheet, a bubble quartz sheet or a quartz wool sheet.

8. The vertical furnace tube according to claim 1, characterized in that: Also included are an inner tube and an outer tube arranged in a nested manner; The outer tube is partially exposed from the furnace mouth, and in the working state, the inner tube is partially exposed from the mouth of the outer tube; A fixing flange is provided for supporting the inner tube and the heat insulation sheet assembly; Accordingly, the heat insulation sheet group is located inside the inner tube.

9. The vertical furnace tube according to claim 8, characterized in that: The fixed flange comprises a flange plate and a cylinder extending upward from the flange plate; A ring-shaped lower support for supporting the inner tube is provided in the middle of the cylinder; An upper support platform for engaging with the lower edge of the outer tube is provided at the upper end of the cylinder.

10. The vertical furnace tube according to claim 9, characterized in that: The fixed flange is a metal flange; The flange has an upward convex portion, and a heat-conducting and heat-insulating plate with a given thickness is provided on the upper surface of the convex portion; The thickness of the heat-conducting insulation board is greater than the thickness of the heat-conducting insulation sheet.

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