A device for improving the production efficiency of quartz synthesized by CVD method

Abstract

The application discloses a device for improving production efficiency of quartz synthesized by a CVD method, which comprises a furnace body, a furnace cover installed on the top of the furnace body, a quartz burner installed in the furnace body, a support column oppositely arranged below the quartz burner, a water-cooled screen installed in the furnace body and sleeved on the outer periphery of the quartz rod, and a flow guide cylinder sleeved on the outer periphery of the water-cooled screen. The flow guide cylinder comprises an inner flow guide cylinder, a heat preservation layer and an outer flow guide cylinder which are sequentially sleeved from inside to outside, and the outer flow guide cylinder is in a bowl-shaped structure with an opening facing downwards and has an inner side surface connected with the heat preservation layer and the inner flow guide cylinder. The device can make the energy consumption in the CVD production process lower, the axial temperature gradient of the quartz rod higher and the radial temperature gradient of the quartz rod lower by adding the water-cooled screen, the flow guide cylinder and a CCD operation in the CVD synthesis furnace, so that the quartz rod can be rapidly produced, the temperature of a quartz growth interface is more stable, and the axial and radial uniformity of the finally produced quartz rod is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of synthetic quartz technology, and more specifically to an apparatus for improving the production efficiency of CVD synthetic quartz. Background Technology

[0002] The methods for preparing quartz glass can be divided into two main categories:

[0003] The first type is obtained by melting natural quartz crystals or silica, and is called natural quartz glass. Depending on the heat source and process, it can be further subdivided into electro-melting, gas refining, and plasma melting methods. Among these, electro-melting has a high yield and is economical, making it the most common process in China. The yield of electro-melting depends not only on the process but also, to a large extent, on the raw materials. While quartz glass prepared by oxyhydrogen flame can reduce impurity content, the finished product has an excessively high hydroxyl content. Plasma deposition can simultaneously address both impurities and hydroxyl content, but its high cost makes large-scale industrialization difficult.

[0004] The second type is synthesized from silicon-containing compounds (including silicon halides, silicon oxides, and organosilicones) through chemical reactions, and is called synthetic quartz glass. According to the different reaction principles, the second type of method can be divided into three types: (1) silicon-containing compounds undergo thermal oxidation in an anhydrous environment to generate SiO2, which is commonly known as plasma chemical vapor deposition (PCVD); (2) silicon-containing compounds undergo hydrolysis in an oxyhydrogen flame (often accompanied by oxidation), which is called flame hydrolysis deposition (FHD); (3) silicon-containing compounds undergo hydrolysis in an aqueous medium, which is called sol-gel method.

[0005] Chemical vapor deposition (CVD) is originally a general term for a class of methods. Strictly speaking, plasma-enhanced chemical vapor deposition (PCVD), external vapor deposition (OVD), and vapor-phase axial deposition (VAD) are all based on chemical vapor deposition (CVD). However, in industry, CVD often specifically refers to the technique of directly preparing quartz glass ingots using flame hydrolysis deposition. The principle of CVD is to feed a silicon-containing compound into an oxyhydrogen flame torch under the guidance of a carrier gas, where a chemical reaction occurs at high temperatures to generate SiO2 particles. Using CVD to prepare quartz glass inherently avoids the introduction of metallic impurities.

[0006] Currently, the CVD method for synthesizing quartz refers to the hydrolysis of silicon tetrachloride in an oxyhydrogen flame to produce high-purity quartz glass. This method has a long production cycle and requires high levels of environmental cleanliness and temperature stability. The quartz glass produced by this method contains almost no aluminum, sodium, or potassium elements, but has a high hydroxyl content, resulting in high production costs and low production efficiency. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a device to improve the production efficiency of CVD-synthesized quartz. By adding a water-cooled screen, a flow guide tube, and CCD operation to the CVD synthesis furnace, the energy consumption during the CVD production process can be reduced, the axial temperature gradient of the quartz rod can be increased, and the radial temperature gradient can be reduced. This allows for rapid production of quartz rods, more stable temperature at the quartz growth interface, and a significant improvement in the axial and radial uniformity of the final quartz rods.

[0008] To solve the above-mentioned technical problems, the present invention provides an apparatus for improving the production efficiency of CVD synthetic quartz, including a furnace body and a furnace cover installed on the top of the furnace body;

[0009] A quartz torch is installed inside the furnace, and a support column is set directly below the quartz torch to support the deposited quartz rod.

[0010] A water-cooled screen is also installed inside the furnace body. The water-cooled screen is sleeved on the outer periphery of the quartz rod and is circulated with cooling water.

[0011] The water-cooled screen is fitted with a flow guide tube on its outer periphery. The flow guide tube includes an inner flow guide tube, a heat insulation layer and an outer flow guide tube, which are fitted sequentially from the inside to the outside. The outer flow guide tube is a bowl-shaped structure with the opening facing downwards and its inner side is connected to the heat insulation layer and the inner flow guide tube.

[0012] The upper end face of the outer guide tube is 5-150 mm below the deposition surface of the quartz rod.

[0013] This invention incorporates a water-cooled screen and a flow guide tube within the furnace. The water-cooled screen creates a significant axial temperature gradient near the growth location of the quartz rod, facilitating high-temperature growth of the quartz at the growth interface (deposition surface). This effectively increases the volatilization of gases and reduces the number of hydroxyl groups in the quartz, further enhancing the purity of the quartz rod. The flow guide tube also serves as a thermal shielding system, providing conditions for uniform, directional, and stable flow of exhaust gas within the furnace. Simultaneously, it aids in the cooling effect of the water-cooled screen, allowing it to absorb more heat from the quartz rod. Furthermore, the presence of the thermal shielding system effectively reduces the energy consumption of the CVD process.

[0014] The present invention sets the growth interface of the quartz rod to extend beyond the uppermost edge of the outer guide tube to prevent the reduction of water cooling effect caused by the passage of fumed silica through the gap between the water cooling screen and the quartz rod, and to prevent production abnormalities caused by changes in the furnace atmosphere due to the deposition of fumed silica between the outer guide tube and the quartz rod.

[0015] Furthermore, the water-cooled screen comprises, from top to bottom, a small-diameter cylinder, a conical cylinder, and a large-diameter cylinder connected in sequence.

[0016] Furthermore, the distance between the inner wall of the small-diameter cylindrical part of the water-cooled screen and the quartz rod is 20-40mm.

[0017] Furthermore, the distance between the upper end face of the outer guide tube and the lower end face of the quartz torch is 150-450mm.

[0018] Furthermore, a heat insulation column is installed above the support column, a quartz substrate is installed above the heat insulation column, and a quartz rod is deposited and grown on the quartz substrate.

[0019] Furthermore, a main shaft is installed below the support column, the main shaft is mounted on a rotating motor, and the rotating motor is mounted on a lifting motor.

[0020] Furthermore, the water-cooled screen and the guide tube are each connected to their respective servo motors for driving lifting. The distance between the upper surface of the water-cooled screen and the outer guide tube is 2-20mm.

[0021] Furthermore, a heat insulation cover is installed inside the furnace, and an exhaust port is provided on the heat insulation cover. The exhaust port is located below the bottom plate of the guide tube, which supports the guide tube. This bottom exhaust mode reduces the deposition of fumed silica inside the furnace. Simultaneously, the airflow inside the furnace flows from top to bottom, and the guide tube further evens out the airflow, improving the stability of the temperature field inside the furnace and ultimately enhancing the stability of the product.

[0022] Furthermore, a CCD vision inspection and control system is installed on the furnace body to detect the growth of the quartz rod and to adjust the retraction rate of the quartz rod in real time.

[0023] Furthermore, a support frame is installed at the bottom of the furnace body.

[0024] Furthermore, the materials of the heat insulation cover and the flow guide tube are selected from high-temperature resistant materials such as silicon dioxide or alumina.

[0025] The beneficial effects of this invention are:

[0026] By using a water-cooled screen, the quartz rod will have a large axial temperature gradient near the growth location, which is conducive to the high-temperature growth of quartz at the growth interface (deposition surface), effectively improving the volatilization of gases and the reduction of hydroxyl groups in the quartz, and further improving the purity of the quartz rod.

[0027] The present invention incorporates a flow guide tube, which also serves as a heat shield system, providing conditions for the uniform, directional, and stable flow of exhaust gas within the furnace. It also aids in the cooling effect of the water-cooled screen, allowing the water-cooled screen to absorb more heat from the quartz rod. Furthermore, the presence of the heat shield system effectively reduces the energy consumption of the CVD process.

[0028] This invention employs a bottom-exhaust mode, which can reduce the deposition of fumed silica inside the furnace. Simultaneously, the airflow inside the furnace flows from top to bottom, and the airflow is further homogenized by the guide tube, which can improve the stability of the temperature field inside the furnace, ultimately enhancing the stability of the product. Attached Figure Description

[0029] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the apparatus for improving the production efficiency of CVD-synthesized quartz according to the present invention;

[0031] Figure 2 This is a schematic diagram of a portion of the device for improving the production efficiency of CVD-synthesized quartz according to the present invention.

[0032] The following are the labels in the diagram: 1. Furnace body, 2. Furnace cover, 3. Quartz torch, 4. Support column, 5. Quartz rod, 6. Water-cooled screen, 7. Inner guide tube, 8. Insulation layer, 9. Outer guide tube, 10. Heat insulation column, 11. Quartz substrate, 12. Main shaft, 13. Rotary motor, 14. Lifting motor, 15. Insulation cover, 16. Exhaust port, 17. Guide tube bottom plate, 18. CCD vision inspection and control system, 19. Support frame. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In this invention, unless otherwise stated, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this patent can be understood according to the specific circumstances.

[0035] Reference Figure 1-2 As shown, this embodiment provides an apparatus for improving the production efficiency of CVD-synthesized quartz, including a furnace body 1 and a furnace cover 2 installed on top of the furnace body 1; a quartz torch 3 is installed inside the furnace body 1, and a support column 4 is arranged directly below the quartz torch 3 to support the deposited quartz rod 5; a water-cooled screen 6 is also installed inside the furnace body 1, the water-cooled screen 6 is sleeved on the outer periphery of the quartz rod 5 and cooling water is circulated inside it; a guide tube is sleeved on the outer periphery of the water-cooled screen 6, the guide tube including an inner guide tube 7, a heat insulation layer 8 and an outer guide tube 9 arranged sequentially from the inside to the outside, the outer guide tube 9 is a bowl-shaped structure with the opening facing downwards and its inner side is connected to the heat insulation layer 8 and the inner guide tube 7; the upper end surface of the outer guide tube 9 is 5-150mm below the deposition surface of the quartz rod 5. The furnace cover 2 provides protection for the quartz torch 3 and prevents heat from escaping from the furnace. The quartz torch 3 is a combustion device for silicon tetrachloride or silane, oxygen, and hydrogen. The growth of the quartz rod 5 takes place inside the furnace body 1. The support column 4 provides a balanced and safe environment for the quartz rod 5.

[0036] In this embodiment, a water-cooled screen 6 and a flow guide tube are installed inside the furnace body 1. The water-cooled screen 6 creates a large axial temperature gradient near the growth position of the quartz rod 5, which is beneficial for the high-temperature growth of quartz at the growth interface (deposition surface), effectively increasing the volatilization of gases and reducing hydroxyl groups in the quartz, thus further improving the purity of the quartz rod 5. The flow guide tube also serves as a heat shield system, providing conditions for the uniform, directional, and stable flow of exhaust gas within the furnace, while also aiding in the cooling effect of the water-cooled screen 6, allowing it to absorb more heat from the quartz rod 5. Furthermore, the presence of the heat shield system effectively reduces the energy consumption of the CVD process. The growth interface of the quartz rod 5 is positioned beyond the uppermost edge of the outer flow guide tube 9 to prevent the fumed silica from passing through the gap between the water-cooled screen 6 and the quartz rod 5, thus preventing a reduction in the water-cooling effect and production abnormalities caused by changes in the furnace atmosphere due to fumed silica deposition between the outer flow guide tube 9 and the quartz rod 5.

[0037] In a preferred embodiment, the water-cooled screen 6 comprises a small-diameter cylinder, a conical cylinder, and a large-diameter cylinder connected sequentially from top to bottom; the distance between the inner wall of the small-diameter cylinder of the water-cooled screen 6 and the quartz rod 5 is 20-40mm; the distance between the upper end face of the outer guide tube 9 and the lower end face of the quartz torch 3 is 150-450mm.

[0038] In a preferred embodiment, a heat insulation column 10 is installed above the support column 4. The heat insulation column 10 effectively prevents heat conduction from the furnace into the workshop through the quartz rod 5. A quartz substrate 11 is installed above the heat insulation column 10, and the quartz rod 5 is deposited and grown on the quartz substrate 11. A main shaft 12 is installed below the support column 4. The main shaft 12 is mounted on a rotary motor 13, which is mounted on a lifting motor 14. The main shaft 12 provides support and rotation for the entire production of the quartz rod 5, and can also descend as the quartz rod 5 is produced, thus aiding in the production of the quartz rod 5 within the furnace. The rotary motor 13 provides conditions for uniform production and cooling of the quartz rod 5, and the lifting motor 14 provides conditions for stable and continuous production of the quartz rod 5.

[0039] In a preferred embodiment, the water-cooled screen 6 and the guide tube are each connected to their respective servo motors for driving lifting. The distance between the upper surface of the water-cooled screen 6 and the outer guide tube 9 is 2-20mm.

[0040] In a preferred embodiment, a heat insulation cover 15 is installed inside the furnace body 1, and an exhaust port 16 is provided on the heat insulation cover 15. The exhaust port 16 is located below the bottom plate 17 of the guide tube, which supports the guide tube. This bottom exhaust mode reduces the deposition of fumed silica inside the furnace. Simultaneously, the downward flow of air within the furnace, further uniformized by the guide tube, improves the stability of the temperature field inside the furnace, ultimately enhancing product stability.

[0041] In a preferred embodiment, a CCD vision detection and control system 18 is installed on the furnace body 1 to detect the growth of the quartz rod 5 and to adjust the retraction rate of the quartz rod 5 in real time; a support frame 19 is installed at the bottom of the furnace body 1, which provides conditions for the growth and removal of the quartz rod 5; the materials of the heat insulation cover 15 and the guide tube are selected from high-temperature resistant materials such as silicon dioxide or alumina.

[0042] The working method of the apparatus for improving the production efficiency of CVD-synthesized quartz in this embodiment is as follows:

[0043] (1) Adjust the distance between the upper end face of the outer guide tube 9 and the lower end face of the quartz torch 3 to between 150-450mm, and adjust the distance between the quartz substrate 11 (the deposition surface of the quartz rod 5) and the lower end face of the quartz torch 3 to between 145-440mm. At the same time, the upper end face of the outer guide tube 9 is 5-150mm below the deposition surface of the quartz rod 5. Slowly raise the water-cooled screen 6 so that the distance between the upper end face of the water-cooled screen 6 and the outer guide tube 9 is between 2-20mm, and the distance between the inner wall of the small-diameter cylinder of the water-cooled screen 6 and the quartz rod 5 is 20-40mm.

[0044] (2) Start the device, rotate motor 13 at a speed of 1-30 revolutions per minute, and start supplying gas and igniting.

[0045] (3) Calibrate the diameter of the quartz rod 5 of the CCD vision inspection and control system 18. Based on the diameter displayed by the CCD vision inspection and control system 18 and the growth of the quartz rod 5, adjust the lifting motor 14 to move backward until the quartz rod 5 has grown.

[0046] (4) After the quartz rod 5 has been cooled for 2-5 hours, the quartz rod 5 prepared by CVD method is removed by a rod removal vehicle.

[0047] (6) After cleaning and inspecting the furnace, the production of the next quartz rod 5 can begin.

[0048] Based on the working method of the device for improving the production efficiency of CVD synthesized quartz, Examples 1-7 adjust the relevant parameters to prepare quartz rods. The specific production parameters and quartz rod parameters are shown in Table 1. In Comparative Example 1, the device does not have a water-cooled screen and a flow guide tube, while the other device components remain unchanged.

[0049] Table 1

[0050]

[0051] As shown in Table 1, by incorporating a flow guide tube and a water-cooled screen within the furnace, the production efficiency of quartz rods in this invention is almost doubled. Example 4 represents the optimal state, where, while production efficiency is improved, the hydroxyl content is reduced by more than 20%, and the bubble rate is reduced by more than 50%.

[0052] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. An apparatus for improving the production efficiency of CVD-synthesized quartz, characterized in that, This includes the furnace body and the furnace cover mounted on top of the furnace body; A quartz torch is installed inside the furnace, and a support column is set directly below the quartz torch to support the deposited quartz rod. A water-cooled screen is also installed inside the furnace body. The water-cooled screen is sleeved on the outer periphery of the quartz rod and is circulated with cooling water. The water-cooled screen is fitted with a flow guide tube on its outer periphery. The flow guide tube includes an inner flow guide tube, a heat insulation layer and an outer flow guide tube, which are fitted sequentially from the inside to the outside. The outer flow guide tube is a bowl-shaped structure with the opening facing downwards and its inner side is connected to the heat insulation layer and the inner flow guide tube. The upper end face of the outer guide tube is 5-150 mm below the deposition surface of the quartz rod.

2. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, The water-cooled screen comprises, from top to bottom, a small-diameter cylinder, a conical cylinder, and a large-diameter cylinder connected in sequence.

3. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 2, characterized in that, The distance between the inner wall of the small-diameter cylindrical part of the water-cooled screen and the quartz rod is 20-40mm.

4. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, The distance between the upper end face of the outer guide tube and the lower end face of the quartz torch is 150-450mm.

5. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, A heat insulation column is installed above the support column, a quartz substrate is installed above the heat insulation column, and a quartz rod is deposited and grown on the quartz substrate.

6. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, A main shaft is installed below the support column, the main shaft is mounted on a rotating motor, and the rotating motor is mounted on a lifting motor.

7. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, The water-cooled screen and the guide tube are each connected to their respective servo motors for driving lifting.

8. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, An insulation cover is installed inside the furnace body, and an exhaust port is provided on the insulation cover. The exhaust port is located below the bottom plate of the guide tube, which is used to support the guide tube.

9. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, The furnace body is equipped with a CCD vision inspection and control system, which is used to detect the growth of the quartz rod and adjust the retraction rate of the quartz rod in real time.

10. The apparatus for improving the production efficiency of CVD-synthesized quartz as described in claim 1, characterized in that, A support frame is installed at the bottom of the furnace body.

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