An apparatus and method for preparing porous, opaque, high-purity quartz by CVD.

Abstract

This invention discloses an apparatus and method for preparing porous, opaque, high-purity quartz using CVD. The apparatus includes a reactor, a burner mounted at the top of the reactor, and a quartz substrate, a guide rod, and a drive mechanism sequentially connected below the burner. The burner comprises an inner shielding layer, an inner oxygen layer, and a hydrogen layer arranged sequentially outward from the central axis. The inner shielding layer is used to introduce a protective gas, the inner oxygen layer is used to introduce oxygen, and the hydrogen layer is used to introduce hydrogen. Within the inner shielding layer, a central layer is located along the central axis, and a raw material layer surrounds the central layer. The central layer is used to introduce a silane pore-forming agent, and the raw material layer is used to introduce a silicon source. An epoxy layer is disposed within the hydrogen layer, and the epoxy layer is used to introduce oxygen. This invention utilizes a multi-layered burner structure, introduces a silane pore-forming agent, and optimizes the introduction positions of the pore-forming agent, silicon source, and protective gas to achieve the preparation of porous, high-purity quartz, solving the problems of poor porosity controllability and susceptibility to impurities affecting purity.

Description

Technical Field

[0001] This invention relates to the field of opaque high-purity quartz preparation technology, specifically to an apparatus and method for preparing porous opaque high-purity quartz by CVD. Background Technology

[0002] High-purity quartz (purity ≥99.999%) is indispensable in semiconductor, optics, and aerospace fields due to its excellent high-temperature resistance, chemical stability, light transmittance, and low coefficient of thermal expansion. Traditional CVD methods for preparing high-purity quartz often use silicon tetrachloride (SiCl4) or octamethylcyclotetrasiloxane (D4) as silicon sources. However, SiCl4 is prone to hydrolysis, producing HCl, which corrodes equipment and easily introduces Cl⁻ impurities. Octamethylcyclotetrasiloxane (D4), as an organosilicon source, has advantages such as low toxicity, easy vaporization, and high purity of its pyrolysis products, and is gradually becoming an ideal silicon source to replace SiCl4.

[0003] Porous, opaque quartz has a high specific surface area and a large number of micron-sized bubbles that are uniformly dispersed inside. It appears milky white and can increase the scattering of thermal radiation inside the material, effectively preventing heat loss. In industry, it is often used as a heat insulation material for the reaction chamber in semiconductor, photovoltaic, and laser manufacturing equipment. It can save costs by reducing the heat loss from the reaction chamber to the outside and can also extend the life of heating components.

[0004] Existing methods for preparing porous opaque quartz mainly include the template method and the sol-gel method. However, the template method is prone to leaving template impurities, while the sol-gel method has a long preparation cycle and poor controllability of pore structure.

[0005] Patent CN117303719A discloses a method for preparing high-purity opaque quartz glass ingots and the same. It uses natural quartz sand or synthetic sand as raw materials, and synthetic silica particles and / or their aggregates as high-purity foaming agents. The opaque quartz glass is prepared through a specific heat treatment process under vacuum electrofusion combined with negative pressure and a protective atmosphere. However, using natural quartz sand as a raw material results in limited and fluctuating purity; while the cost of synthetic sand is greatly affected by the raw materials, production environment, and process complexity, and it is mainly supplied to high-end fields such as semiconductors, with market prices far exceeding those of high-purity natural quartz sand. Patent CN111233309A discloses a method for producing high-quality opaque quartz glass ingots, using an oxyhydrogen flame as a heat source, quartz sand as raw material, and vaporized organosilicon as a foaming agent. Although this method significantly improves product uniformity and yield, it still uses quartz sand as a raw material and suffers from the same problems.

[0006] Chemical vapor deposition (CVD) is a common method for preparing high-purity quartz materials. Its principle involves a chemical reaction of silicon-containing compounds at high temperatures to generate silicon dioxide, which is then deposited on the substrate surface. It offers advantages such as high production efficiency and high product purity. However, traditional CVD processes are mainly used to prepare dense quartz materials. Upgrading the technology to enable the preparation of porous, opaque quartz masses with controllable pore structures remains a key technical challenge in this field. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing an apparatus and method for preparing porous, opaque, high-purity quartz using CVD. It incorporates a multi-layered burner, introduces a silane pore-forming agent, and optimizes the entry points of the pore-forming agent, silicon source, and protective gas to achieve the preparation of porous, high-purity quartz. This solves the problems of poor porosity controllability and susceptibility to impurities affecting purity.

[0008] To solve the above-mentioned technical problems, the present invention provides an apparatus for preparing porous, opaque, high-purity quartz by CVD method, including a reactor, a burner installed at the top of the reactor, and a quartz substrate, a guide rod, and a drive mechanism connected in sequence below the burner.

[0009] The burner includes an inner shielding layer, an inner oxygen layer, and a hydrogen layer arranged sequentially from the central axis outwards, wherein the inner shielding layer is used to introduce a protective gas, the inner oxygen layer is used to introduce oxygen gas, and the hydrogen layer is used to introduce hydrogen gas.

[0010] The inner shielding layer contains a central layer located on the central axis and a raw material layer surrounding the central layer. The central layer is used to introduce a silane pore-forming agent, and the raw material layer is used to introduce a silicon source.

[0011] An epoxy layer is disposed within the hydrogen layer, and the epoxy layer is used to introduce oxygen.

[0012] This invention employs a multi-layered burner structure. A central layer, through which a silane pore-forming agent is introduced, is placed at the center of the burner. This central layer, separated from the inner oxygen layer through which reactive oxygen is introduced, is separated by a raw material layer and an inner shielding layer. The reactive oxygen introduced into the inner oxygen layer reacts preferentially with the silicon source introduced into the raw material layer. The silicon source reacts completely with the oxygen to generate SiO2, which is the main reaction. After the pore-forming agent is introduced through the central layer, the oxygen required for its reaction is insufficient due to the obstruction of the gases introduced into the raw material layer and the inner shielding layer. The incomplete reaction of the pore-forming agent generates byproducts such as siloxane fragments, -CH3 free radicals, and small molecule compounds like CO2 and H2O, as well as SiO2. These byproducts adhere to the surface of the SiO2 in the main reaction and are deposited. After deposition, they are reduced by the protective gas constraint and continue to react at high temperatures, completely transforming into SiO2 and volatile gases such as H2O and CO2. These volatiles escape and form pores inside the silica. As deposition continues, these tiny pores are continuously covered by newly generated silica, remaining within the quartz product, resulting in porous, high-purity quartz.

[0013] Furthermore, the air inlets of the central layer and the raw material layer are respectively connected to corresponding feeding systems. These feeding systems include, in sequence, a storage tank, valves, a pressure valve, a mass flow controller, and an evaporator. The pore-forming agent and silicon source originate from their respective storage tanks, and through precise flow control via an MFC, enter the evaporator, where they transform from a liquid to a gaseous state before entering the burner. The temperature of the evaporator is 30-50°C higher than the boiling point of the corresponding pore-forming agent or silicon source.

[0014] Furthermore, an outer oxygen layer is provided outside the hydrogen layer for introducing oxygen, and the outer oxygen layer is used to control the flame shape.

[0015] Furthermore, the epoxy layer includes an inner epoxy layer and an outer epoxy layer surrounding the inner epoxy layer. It consists of multiple small gas tubes evenly distributed around the burner center; the inner epoxy layer, outer epoxy layer, and hydrogen layer provide the heat required for the main and side reactions through hydrogen-oxygen combustion.

[0016] Furthermore, the silane pore-forming agent does not contain any elements other than Si, O, C, and H, and preferably is selected from octamethylcyclotetrasiloxane (D4) or decamethylcyclopentasiloxane (D5).

[0017] Furthermore, the axis of the burner is aligned with the axis of the guide rod.

[0018] Furthermore, the drive mechanism is connected to the quartz substrate via a guide rod, and is used to control the lifting and rotation of the quartz substrate.

[0019] A second aspect of the present invention provides a method for preparing porous, opaque, high-purity quartz by CVD, using the apparatus for preparing porous, opaque, high-purity quartz by CVD as described in the first aspect, comprising the following steps:

[0020] S1. Oxygen is introduced into the inner oxygen layer, outer oxygen layer and epoxy layer, while protective gas and hydrogen are introduced into the inner shielding layer and hydrogen layer respectively, so that the reactor is heated to the deposition temperature.

[0021] S2, the central layer and the raw material layer are respectively introduced with silane pore-forming agent and silicon source, and porous quartz is deposited by reaction;

[0022] Among them, the raw material layer is close to the inner oxygen layer, and the introduced silicon source reacts completely with oxygen to generate SiO2.

[0023] The central layer is far from the inner oxygen layer, and the two are separated by a raw material layer and an inner shielding layer. There is insufficient oxygen to react with the introduced silane pore-forming agent. The silane pore-forming agent does not react completely to generate byproducts including siloxane fragments, -CH3 free radicals and SiO2, which are deposited together with the SiO2 generated by the silicon source on the quartz substrate.

[0024] After the by-products are deposited, they are constrained by the protective gas introduced into the inner shielding layer and continue to react at high temperature to transform into SiO2, H2O and CO2 gaseous volatiles. After the gaseous volatiles escape, they form pores inside the silicon dioxide.

[0025] Furthermore, the central layer is also circulated with oxygen and a carrier, wherein the ratio of the oxygen flow rate to the flow rate required for the complete reaction of the silane pore-forming agent is less than 1:15.

[0026] The raw material layer is also circulated with oxygen and a carrier. The oxygen is fully premixed with the silicon source circulated into the raw material layer to promote a full reaction between the silicon source and the oxygen.

[0027] The reaction in the central layer is a side reaction that creates porous, opaque quartz. In addition to the silane pore-forming agent, oxygen and a carrier gas that does not participate in the chemical reaction are also introduced into the central layer. By controlling the ratio of oxygen to the pore-forming agent, the degree of incomplete reaction can be controlled, thereby controlling the porosity and size. The pore-forming agent is placed in the central layer, far from the reacting oxygen, and its ratio with the mixed oxygen within the central tube is precisely controlled. Through precise delivery and controlled mixing, premature reaction that would cause the pore-forming agent to become ineffective is avoided.

[0028] Introducing oxygen into the feedstock layer ensures thorough mixing of the feedstock and oxygen, leading to a more complete main reaction. The carrier gas not only ensures more uniform premixing of the feedstock and oxygen but also allows for adjustment of feedstock concentration, flow rate, and reaction rate.

[0029] The oxygen introduced into the inner oxygen layer reacts with the raw materials and is the main gas in the main reaction.

[0030] The protective gas and carrier gas are selected from high-purity nitrogen or argon that do not participate in the chemical reaction.

[0031] Furthermore, the flow rates of each component introduced into the central layer are as follows: silane pore-forming agent 4-7 g / min, oxygen 0.01-0.6 L / min, and carrier gas 3.5-5 L / min;

[0032] The flow rates of each component introduced into the raw material layer are as follows: silicon source 15-25 g / min, oxygen 3-6 L / min, and carrier gas 10-14 L / min.

[0033] The flow rate of the protective gas introduced into the inner shielding layer is 12-19 L / min;

[0034] The oxygen flow rate introduced into the inner oxygen layer is 30-37 L / min;

[0035] The hydrogen gas flow rate is 350-450 L / min for the hydrogen layer, 56-85 L / min for the inner epoxy layer, and 85-140 L / min for the outer epoxy layer.

[0036] Furthermore, the initial deposition temperature is 1100~1200℃, and continues to rise until the stable deposition stage, where the temperature is 1400-1450℃.

[0037] Furthermore, during the S2 deposition process, the drive mechanism drives the quartz substrate to move downward (retract) at a rate of 0.02~0.04 mm / min.

[0038] The beneficial effects of this invention are:

[0039] This invention features a multi-layered burner, introduces a silane pore-forming agent, and optimizes the entry points of the pore-forming agent, silicon source, and protective gas to achieve the preparation of porous high-purity quartz. The quartz product purity can reach over 99.999%, meeting the needs of high-end fields such as semiconductors and optics.

[0040] By adjusting the concentration and flow rate of the silane pore-forming agent and the selection of the pore-forming agent, the porosity of the obtained porous quartz can be precisely adjusted within the range of 2%-10%, with a pore size of 10~200μm and uniform distribution.

[0041] This invention employs chemical vapor deposition technology, resulting in products with good performance stability and repeatability. The manufacturing process is completed in one step, resulting in low production costs, and it can produce quartz products of different sizes. Attached Figure Description

[0042] 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.

[0043] Figure 1 This is a schematic diagram of the apparatus for preparing porous, opaque, high-purity quartz using the CVD method of the present invention.

[0044] Figure 2 This is a schematic diagram of the multi-layer structure of the burner of the present invention;

[0045] Figure 3 This is a schematic diagram of the feeding system structure of the present invention;

[0046] Figure 4 This is a photograph of the porous, opaque quartz prepared in Example 1 of this invention;

[0047] The following are the labels in the diagram: 1. Reactor; 2. Burner; 21. Inner shielding layer; 22. Inner oxygen layer; 23. Hydrogen layer; 24. Central layer; 25. Raw material layer; 26. Outer oxygen layer; 27. Inner epoxy layer; 28. Outer epoxy layer; 3. Quartz substrate; 4. Guide rod; 5. Drive mechanism; 6. Storage tank; 7. Valve; 8. Pressure valve; 9. Mass flow controller; 10. Evaporator. Detailed Implementation

[0048] 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.

[0049] 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.

[0050] refer to Figure 1As shown, this embodiment relates to an apparatus for preparing porous, opaque, high-purity quartz by CVD, including a reactor 1, a burner 2 mounted on top of the reactor 1, and a quartz substrate 3, a guide rod 4, and a drive mechanism 5 sequentially connected below the burner 2; Reference Figure 2 As shown, the burner 2 includes an inner shielding layer 21, an inner oxygen layer 22, and a hydrogen layer 23 arranged sequentially from the central axis outwards. The inner shielding layer 21 is used to introduce a protective gas, the inner oxygen layer 22 is used to introduce oxygen, and the hydrogen layer 23 is used to introduce hydrogen. The inner shielding layer 21 contains a central layer 24 located on the central axis and a raw material layer 25 surrounding the central layer 24. The central layer 24 is used to introduce a silane pore-forming agent, and the raw material layer 25 is used to introduce a silicon source. The hydrogen layer 23 contains an epoxy layer, which is used to introduce oxygen. This embodiment features a multi-layer burner 2. A central layer 24, through which the silane pore-forming agent is introduced, is positioned at the center. This central layer 24, through which the inner oxygen layer 22, through which reactive oxygen is introduced, is separated by a raw material layer 25 and an inner shielding layer 21. The reactive oxygen introduced into the inner oxygen layer 22 reacts preferentially with the silicon source introduced into the raw material layer 25. The silicon source reacts completely with the oxygen to generate SiO2, which is the primary reaction. After the pore-forming agent is introduced through the central layer 24, the oxygen required for its reaction is insufficient due to the obstruction of the gas introduced into the raw material layer 25 and the inner shielding layer 21. Therefore, it does not have enough time to fully react in the flame, thus failing to create pores. Incomplete reaction of the reagents generates byproducts such as siloxane fragments, -CH3 free radicals, and small molecule compounds like CO2, H2O, and SiO2, which adhere to and deposit on the surface of the SiO2 in the main reaction. After deposition, the confinement of the protective gas decreases, and the high-temperature reaction continues to completely transform them into SiO2 and volatile gases such as H2O and CO2. After the volatiles escape, they form pores inside the silica. As deposition continues, the tiny pores are continuously covered by newly generated silica, and the pores remain inside the quartz product, resulting in porous high-purity quartz.

[0051] As a preferred embodiment, refer to Figure 3 The air inlets of the central layer 24 and the raw material layer 25 are respectively connected to corresponding feeding systems. Each feeding system includes a storage tank 6, a valve 7, a pressure valve 8, a mass flow controller 9, and an evaporator 10 connected in sequence. The pore-forming agent and silicon source originate from their respective storage tanks 6, and through precise flow control via an MFC, enter the evaporator 10, where they change from liquid to gaseous state before entering the burner 2. The temperature of the evaporator 10 is 30-50°C higher than the boiling point of the corresponding pore-forming agent or silicon source.

[0052] In a preferred embodiment, an outer oxygen layer 26 for introducing oxygen is provided outside the hydrogen layer 23, and the outer oxygen layer 26 is used to control the flame shape. The epoxy layer includes an inner epoxy layer 27 and an outer epoxy layer 28 surrounding the inner epoxy layer 27. It consists of multiple small gas tubes, which are evenly distributed around the center of the burner 2; the inner epoxy layer 27, outer epoxy layer 28, and hydrogen layer 23 provide the heat required for the main and side reactions through hydrogen-oxygen combustion.

[0053] In a preferred embodiment, the silane pore-forming agent does not contain any elements other than Si, O, C, and H, and preferably is selected from octamethylcyclotetrasiloxane (D4) or decamethylcyclopentasiloxane (D5).

[0054] In a preferred embodiment, the axis of the burner 2 is aligned with the axis of the guide rod 4; the drive mechanism 5 is connected to the quartz substrate 3 via the guide rod 4 and is used to control the lifting and rotation of the quartz substrate 3.

[0055] Another embodiment relates to a method for preparing porous, opaque, high-purity quartz using CVD, and the apparatus for preparing porous, opaque, high-purity quartz using CVD as described in the above embodiment includes the following steps:

[0056] S1, inner oxygen layer 22, outer oxygen layer 26 and epoxy layer are introduced with oxygen, while the inner shielding layer 21 and hydrogen layer 23 are introduced with protective gas and hydrogen respectively, so that the reactor 1 is heated to the deposition temperature.

[0057] S2, the central layer 24 and the raw material layer 25 are respectively introduced with silane pore-forming agent and silicon source to react and deposit porous quartz.

[0058] Among them, the raw material layer 25 is close to the inner oxygen layer 22, and the introduced silicon source reacts completely with oxygen to generate SiO2.

[0059] The central layer 24 is far from the inner oxygen layer 22, and the two are separated by the raw material layer 25 and the inner shielding layer 21. The oxygen for the reaction with the introduced silane pore-forming agent is insufficient, and the silane pore-forming agent does not react completely to generate byproducts including siloxane fragments, -CH3 free radicals and SiO2, which are deposited together with the SiO2 generated by the silicon source on the quartz substrate 3.

[0060] After the by-products are deposited, they are constrained by the protective gas introduced by the inner shielding layer 21 and continue to react at high temperature to transform into SiO2, H2O and CO2 gaseous volatiles. After the gaseous volatiles escape, they form pores inside the silicon dioxide.

[0061] In a preferred embodiment, the central layer 24 is further circulated with oxygen and a carrier, wherein the ratio of the oxygen flow rate to the flow rate required for complete reaction of the silane pore-forming agent is less than 1:15. The raw material layer 25 is also circulated with oxygen and a carrier, where the oxygen is fully premixed with the silicon source introduced into the raw material layer 25 to promote a complete reaction between the silicon source and oxygen. The reaction in the central layer 24 is a side reaction for manufacturing porous, opaque quartz. In addition to the silane pore-forming agent, the central layer 24 is also circulated with oxygen and a carrier gas that does not participate in the chemical reaction. By controlling the ratio of oxygen to the pore-forming agent, the degree of incomplete reaction can be controlled, thereby controlling the porosity and size. The pore-forming agent is positioned in the central layer 24, away from the reacting oxygen, and its ratio with the mixed oxygen in the central tube is precisely controlled. Through precise delivery and controllable mixing, premature reaction that could lead to pore-forming agent failure is avoided. The oxygen circulated into the raw material layer 25 is to ensure thorough mixing of the raw material and oxygen, making the main reaction more complete. The carrier gas, while ensuring more uniform premixing of the raw material and oxygen, allows for adjustment of the raw material concentration, flow rate, and reaction rate. The oxygen introduced into the inner oxygen layer 22 reacts with the raw materials and is the main gas in the main reaction. The protective gas and carrier gas are selected from high-purity nitrogen or high-purity argon that do not participate in the chemical reaction.

[0062] In a preferred embodiment, the flow rates of each component introduced into the central layer 24 are as follows: silane pore-forming agent 4-7 g / min, oxygen 0.01-0.6 L / min, and carrier gas 3.5-5 L / min; the flow rates of each component introduced into the raw material layer 25 are as follows: silicon source 15-25 g / min, oxygen 3-6 L / min, and carrier gas 10-14 L / min; the flow rate of the protective gas introduced into the inner shielding layer 21 is 12-19 L / min; and the flow rate of oxygen introduced into the inner oxygen layer 22 is 30-37 L / min.

[0063] In a preferred embodiment, the initial deposition temperature is 1100~1200℃, and continues to rise until the stable deposition stage, where the temperature is 1400-1450℃. During the S2 deposition process, the drive mechanism 5 drives the quartz substrate 3 to move downward (retract) at a rate of 0.02~0.04 mm / min.

[0064] Example 1

[0065] This embodiment relates to a method for preparing porous, opaque, high-purity quartz by CVD, comprising the following steps:

[0066] (1) Oxygen is introduced into the inner oxygen layer 22, the outer oxygen layer 26 and the epoxy layer (inner epoxy layer 27 and outer epoxy layer 28), while protective gas and hydrogen are introduced into the inner shielding layer 21 and the hydrogen layer 23 respectively, and the reactor 1 is heated to the deposition reaction temperature.

[0067] (2) Silane pore-forming agent and silicon source, as well as oxygen and carrier gas, are introduced into the central layer 24 and the raw material layer 25 respectively, and porous quartz is deposited by reaction. The photograph is shown below. Figure 4 As shown;

[0068] The flow rates of each component introduced into the central layer 24 are as follows: silane pore-forming agent D5 5 g / min, oxygen 0.4 L / min, and nitrogen 4 L / min; the flow rates of each component introduced into the raw material layer 25 are as follows: silicon source D4 20 g / min, oxygen 4 L / min, and nitrogen 12 L / min; the flow rate of nitrogen introduced into the inner shielding layer 21 is 14 L / min; the flow rate of oxygen introduced into the inner oxygen layer 22 is 35 L / min; the flow rate of hydrogen introduced into the hydrogen layer 23 is 400 L / min; the flow rate of hydrogen introduced into the inner epoxy layer 27 is 80 L / min; and the flow rate of hydrogen introduced into the outer epoxy layer 28 is 120 L / min; the temperature during the stable deposition stage is 1430℃; and the retraction rate during the deposition process is 0.02 mm / min.

[0069] Example 2

[0070] The difference between this embodiment and Embodiment 1 lies in the parameters, specifically:

[0071] The flow rates of each component introduced into the central layer 24 are as follows: silane pore-forming agent D5 6.5 g / min, oxygen 0.32 L / min, and nitrogen 4 L / min; the flow rates of each component introduced into the raw material layer 25 are as follows: silicon source D4 20 g / min, oxygen 4 L / min, and nitrogen 12 L / min; the flow rate of nitrogen introduced into the inner shielding layer 21 is 14 L / min; the flow rate of oxygen introduced into the inner oxygen layer 22 is 35 L / min; the flow rate of hydrogen introduced into the hydrogen layer 23 is 380 L / min; the flow rate of hydrogen introduced into the inner epoxy layer 27 is 76 L / min; and the flow rate of hydrogen introduced into the outer epoxy layer 28 is 114 L / min; the temperature during the stable deposition stage is 1415℃; and the retraction rate during the deposition process is 0.028 mm / min.

[0072] The technical specifications of the porous quartz obtained in Examples 1-2 are shown in Table 1.

[0073] Table 1

[0074]

[0075] As can be seen, compared with Example 1, Example 2 increases the flow rate of the pore-forming agent in the central layer, reduces the oxygen concentration ratio in the central layer, reduces the flow rates of the hydrogen layer, inner epoxy layer, and outer epoxy layer, lowers the temperature, and slows down the escape velocity of small molecule gases, thereby increasing the porosity and pore diameter. By adjusting the flow rate of the burner components, the porosity and pore diameter of the porous high-purity quartz can be adjusted.

[0076] 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 producing porous, non-transparent, high-purity quartz by the CVD method, characterized in that, The device comprises a reaction furnace, a burner installed at the top end of the reaction furnace, and a quartz substrate, a guide rod and a driving mechanism connected in sequence below the burner; The burner comprises an inner shielding layer, an inner oxygen layer and a hydrogen layer arranged outwardly from the center axis in sequence, wherein the inner shielding layer is used for passing in a protective gas, the inner oxygen layer is used for passing in oxygen, and the hydrogen layer is used for passing in hydrogen; The inner shielding layer is provided with a center layer located at the center axis and a raw material layer surrounding the center layer, wherein the center layer is used for passing in a silane pore-forming agent, and the raw material layer is used for passing in a silicon source; The hydrogen layer is provided with an epoxy layer used for passing in oxygen.

2. The apparatus for producing porous non-transparent high-purity quartz by the CVD method according to claim 1, wherein The gas inlet ends of the center layer and the raw material layer are respectively connected to corresponding feeding systems, and the feeding systems comprise a storage tank, a valve, a pressure valve, a mass flow controller and an evaporation tank connected in sequence.

3. The apparatus for producing porous non-transparent high-purity quartz by CVD method according to claim 1, wherein The hydrogen layer is provided with an outer oxygen layer used for passing in oxygen, and the outer oxygen layer is used for controlling the shape of the flame.

4. The apparatus for making porous non- transparent high purity quartz by CVD method according to claim 1, wherein The epoxy layer comprises an inner epoxy layer and an outer epoxy layer surrounding the inner epoxy layer.

5. The apparatus for making porous non- transparent high purity quartz by CVD method as claimed in claim 1, wherein, The silane pore-forming agent does not contain other elements except Si, O, C and H.

6. The apparatus for making porous non- transparent high purity quartz by CVD method as claimed in claim 1, wherein, The center axis of the burner coincides with the center axis of the guide rod.

7. The apparatus for making porous, non- transparent, high purity quartz by CVD method as claimed in claim 1, wherein The driving mechanism is connected to the quartz substrate through the guide rod and is used for controlling the lifting and rotation of the quartz substrate.

8. A method for producing porous, non-transparent high-purity quartz by the CVD method, characterized by, The device for preparing porous opaque high-purity quartz by the CVD method according to any one of claims 1-7 comprises the following steps: S1, oxygen is passed into the inner oxygen layer, the outer oxygen layer and the epoxy layer, while the inner shielding layer and the hydrogen layer pass in a protective gas and hydrogen respectively, so as to heat the reaction furnace to a deposition temperature; S2, the center layer and the raw material layer pass in a silane pore-forming agent and a silicon source respectively, and porous quartz is deposited by reaction; The raw material layer is close to the inner oxygen layer, and the silicon source passed in reacts completely with oxygen to generate SiO2; The center layer is far away from the inner oxygen layer, and the two are separated by the raw material layer and the inner shielding layer, and the oxygen reacted with the silane pore-forming agent is insufficient, so that the silane pore-forming agent does not react completely to generate by-products including siloxane fragments and -CH3 free radicals and SiO2, which is deposited on the quartz substrate together with the SiO2 generated by the silicon source; After the by-products are deposited, they are reduced by the protective gas passed into the inner shielding layer, and continue to react at high temperature to be converted into SiO2 and H2O and CO2 gas volatiles, and after the gas volatiles escape, pores are formed in the silica.

9. The method of claim 8, wherein the CVD method of producing porous, non- transparent, high purity quartz is characterized by, The center layer also passes in oxygen and a carrier, and the flow rate ratio of the oxygen to the flow rate required for complete reaction of the silane pore-forming agent is less than 1:15; The raw material layer also passes in oxygen and a carrier, and the oxygen is fully premixed with the silicon source passed into the raw material layer to promote the complete reaction of the silicon source with oxygen.

10. The method of claim 9, wherein the CVD method of producing porous, non- transparent, high purity quartz is characterized by, The flow rates of the components passed into the center layer are respectively: 4-7 g / min of silane pore-forming agent, 0.01-0.6 L / min of oxygen and 3.5-5 L / min of carrier gas; The flow rates of the components passed into the raw material layer are respectively: 15-25 g / min of silicon source, 3-6 L / min of oxygen and 10-14 L / min of carrier gas; The protective gas passed into the inner shielding layer has a flow rate of 12-19 L / min; The oxygen passed into the inner oxygen layer has a flow rate of 30-37 L / min.

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