High-purity quartz flow diffuser and method for making same

Abstract

The application discloses a preparation method of a high-purity quartz flow distributor, which comprises the following steps: step 1, preparing a slurry; step 2, preparing a blank; step 3, blank forming; step 4, volatilizing and burning organic foam on the surface of the formed blank; step 5, high-temperature sintering of the blank; step 6, annealing of the sintered blank; and step 7, natural cooling of the annealed blank to room temperature in a vacuum sintering furnace. The method uses high-purity fumed silica, combines with a high-speed dispersion process of deionized water to prepare a high-purity siliceous dispersant, and then prepares the slurry by mixing the high-purity siliceous dispersant with high-purity nanoscale quartz particles, so that the purity of the raw material is ensured; after the blank is formed, a multi-temperature-stage long-heat-preserving process is adopted to effectively remove the organic foam and efficiently prevent the deformation of the blank; and the finished product rate can reach more than 80% by using the method provided by the application to prepare the flow distributor.

Description

Technical Field

[0001] This invention relates to the field of quartz device fabrication technology, and in particular to a high-purity quartz diffuser and its fabrication method. Background Technology

[0002] Wafer fabrication processes require multiple thin-film depositions within a reaction chamber. Currently, the most commonly used thin-film deposition process is chemical vapor deposition (CVD). In domestic and international CVD equipment for wafer fabrication, the ventilation components are typically perforated in the wall of a quartz glass tube, with a perforation diameter of 1.0 mm and a spacing of 10-12 mm. Gas is ejected through the small perforations under pressure and undergoes a gas-phase chemical reaction within the reaction chamber. Solid reactants are then uniformly deposited on the substrate surface to form a thin film. To ensure the requirements of the wafer fabrication process, the purity of the quartz glass tube must be above 99.99999%.

[0003] In CVD (Chemical Vapor Deposition), gas is injected through openings in the quartz tube wall, entering the reaction chamber as a stream. This stream has a certain directionality, and gaps exist between the gas streams. This injection method can easily lead to uneven gas dispersion within the reaction chamber, affecting the quality of the subsequent film.

[0004] Therefore, providing a high-purity quartz diffuser to ensure uniform gas dispersion within the aforementioned reaction chamber is a pressing issue. Existing methods suffer from the following problems: for example, the granulation process of particle pressing introduces large amounts of organic matter that cannot be removed later; the VAD deposition process is complex and difficult to control, making mass production challenging; and the photocuring molding method is prone to deformation during the later degreasing process, resulting in low yield. Summary of the Invention

[0005] In view of this, the present invention discloses a high-purity quartz diffuser and its preparation method;

[0006] The technical solution provided by this invention is specifically a method for preparing a high-purity quartz diffuser, comprising the following steps:

[0007] Step 1: Preparation of slurry: According to the weight parts, obtain 30-40 parts of high-purity fumed silica and 60-70 parts of deionized water, mix them under high-speed dispersion conditions to obtain a high-purity silica dispersant. After standing, obtain 35 parts of the high-purity silica dispersant and 65 parts of high-purity quartz micro powder, mix them under high-speed dispersion conditions to obtain a slurry.

[0008] Step 2: Preparing the blank: Immerse the pretreated reticulated polyurethane foam into the slurry, so that the slurry is fully and evenly coated on the polyurethane foam.

[0009] Step 3: Blank forming: Dry and form the obtained blank within 120 minutes;

[0010] Step 4: Volatilize the organic foam on the surface of the green body after sintering and molding;

[0011] Step 5: High-temperature sintering of the green body obtained in step 4;

[0012] Step 6: Anneal the sintered green body;

[0013] Step 7: Allow the annealed billet to cool naturally to room temperature in a vacuum sintering furnace.

[0014] Preferably, the total metal ion content in the high-purity fumed silica is less than 50 ppm; the conductivity of the deionized water is 16-18 MΩ·cm.

[0015] The process parameters for mixing high-purity fumed silica and deionized water under high-speed dispersion conditions are: high-speed disperser speed 1600-1800 r / min, dispersion time 120 min, and standing time after mixing 3-5 min.

[0016] The high-purity quartz micro powder has a purity of over 99.99999% and a particle size D. 50 200-250nm;

[0017] The process parameters for mixing the high-purity silica dispersant and high-purity quartz micro powder under high-speed dispersion conditions are: high-speed disperser speed 200-300 r / min, dispersion time 30 min.

[0018] Preferably, the slurry coating on the polyurethane foam includes the following steps: after immersing the pretreated reticulated polyurethane foam into the slurry, repeatedly squeezing the reticulated polyurethane foam 8-10 times with a PP material pressure head applying a pressure of 5N; then placing the reticulated polyurethane foam and slurry in a centrifuge at 500-600r / min for 3-4min; removing the reticulated polyurethane foam and placing it on a PP material filter screen to remove excess slurry using pure compressed air.

[0019] Preferably, the process of removing excess slurry from the reticulated polyurethane foam using pure compressed air has the following parameters: the air nozzle is positioned 5-10 cm from the surface of the blank and perpendicular to the surface of the blank, and the air is circulated for 2-3 minutes, with the nozzle being at least 1 cm from the edge of the reticulated polyurethane foam on the blank, and the air pressure is 2.5 MPa.

[0020] Preferably, the pre-treated reticulated polyurethane foam is prepared by placing the reticulated polyurethane foam in an ultrasonic cleaning tank for 30 seconds to remove excess particles adhering to the surface, washing it with deionized water, placing it in an oven, and baking it for 30 minutes at an oven temperature of 50-55°C.

[0021] Preferably, the drying and shaping of the obtained blank includes: drying in a ventilated drying oven at a temperature of 100-150°C for 60 minutes, with pure air ventilating upwards perpendicular to the lower surface of the blank.

[0022] Preferably, the heating procedure for the volatile burning organic foam is as follows: in a vacuum sintering furnace, the temperature is raised from room temperature to 500°C at a heating rate of 5°C / min and held for 1 hour; the temperature is raised from 500°C to 800°C at a heating rate of 5°C / min and held for 1 hour; and the temperature is raised from 800°C to 1200°C at a heating rate of 5°C / min and held for 1 hour.

[0023] Preferably, the high-temperature sintering is carried out in a vacuum sintering furnace, with a heating rate of 10℃ / min, from 1200℃ to 1750℃, and the temperature is held at 1750℃ for 30 minutes.

[0024] Preferably, the annealing process involves natural cooling to 500°C in a vacuum sintering furnace and holding at that temperature for 30-40 minutes.

[0025] The present invention also provides a high-purity quartz diffuser, which can be machined to the required shape and is installed at the top and wall of the vent pipe in a CVD chemical vapor deposition equipment.

[0026] This invention provides a high-purity quartz diffuser and its preparation method. The method uses high-purity fumed silica, combined with a high-speed dispersion process with deionized water to prepare a high-purity silica dispersant. The high-purity silica dispersant is then combined with high-purity nano-sized quartz particles to prepare a slurry, ensuring the purity of the raw materials. After the green body is formed, a multi-temperature-section long-heat preservation process is used to effectively remove organic foam while efficiently preventing the deformation of the green body. The diffuser prepared using the method provided by this invention can achieve a yield of over 80%.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of the present invention. Detailed Implementation

[0028] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with some aspects of the invention as detailed in the appended claims.

[0029] The preparation method provided in this embodiment yields a high-purity quartz diffuser, which allows gas to diffuse uniformly within the reaction chamber after passing through. This feature can significantly improve the deposition uniformity within the CVD reaction chamber in wafer fabrication processes.

[0030] This embodiment discloses a method for preparing a high-purity quartz diffuser, comprising the following steps:

[0031] Step 1: Prepare the slurry:

[0032] A high-purity silica dispersant is prepared by high-speed dispersion of high-purity fumed silica and deionized water. The total metal ion content of the high-purity fumed silica should be below 50 ppm, and the conductivity of the deionized water should be 16-18 MΩ·cm. The components are: 30-40 parts high-purity fumed silica and 60-70 parts deionized water by weight. The high-speed disperser operates at 1600-1800 r / min for 50-60 min. The shear force generated by the high speed causes the van der Waals forces between molecules to recombine and form a colloidal material mSiO2·nH2O·SiO2, which is a stabilizer-free silica sol. Then, quartz micropowder with a purity of 99.99999% or higher and a particle size D50 of 200-250 nm is added. The components are: 35 parts high-purity silica dispersant and 65 parts high-purity quartz micropowder by weight. The high-speed disperser operates at 200-300 r / min for 8-10 min.

[0033] Step 2: Preparing the blank: Immerse the pretreated reticulated polyurethane foam into the slurry, so that the slurry is fully and evenly coated on the polyurethane foam.

[0034] Specifically, the reticulated polyurethane foam is placed in an ultrasonic cleaning tank and cleaned for 30 seconds to remove excess particles adhering to the surface. It is then rinsed with deionized water and placed in an oven at 50-55℃ for 30 minutes. The reticulated polyurethane foam is then immersed in the prepared slurry and repeatedly squeezed 8-10 times using a PP pressure head at 5N. It is then placed in a centrifuge at 500-600 rpm for 3-4 minutes to remove excess slurry. Finally, it is placed on a PP filter screen and clean compressed air is used to remove excess slurry at a pressure of 2.5 MPa, blowing perpendicularly to the surface of the preform at a distance of 5-10 cm for 2-3 minutes to ensure the slurry is fully and evenly coated onto the foam mesh. Since no stabilizer is added in this method, the slurry removal and subsequent blowing in the centrifuge quickly removes excess slurry and prevents it from coagulating and clogging the pores of the polyurethane foam.

[0035] Step 3: Blank forming: Dry and form the obtained blank within 120 minutes;

[0036] Specifically, the material is dried in a ventilation drying oven at a temperature of 100-150℃ for 60 minutes, with pure air ventilating upwards perpendicular to the lower surface of the billet.

[0037] Step 4: Volatilize the organic foam on the surface of the green body after sintering and molding;

[0038] Specifically, in a vacuum sintering furnace, the temperature is raised from room temperature to 500°C at a heating rate of 5°C / min and held for 1 hour, then raised from 500°C to 800°C at a heating rate of 5°C / min and held for 1 hour, and finally raised from 800°C to 1200°C at a heating rate of 5°C / min and held for 1 hour.

[0039] Step 5: High-temperature sintering of the green body obtained in step 4;

[0040] Specifically, in a vacuum sintering furnace, the temperature is raised from 1200℃ to 1750℃ at a heating rate of 10℃ / min, and held at 1750℃ for 30 minutes.

[0041] Step 6: Anneal the sintered green body;

[0042] Specifically, the temperature is naturally cooled to 500°C in a vacuum sintering furnace and held for 30-40 minutes.

[0043] Step 7: Allow the annealed billet to cool naturally to room temperature in a vacuum sintering furnace.

[0044] In addition, this embodiment also provides a high-purity quartz diffuser. The high-purity quartz diffuser prepared according to the above method has a K+ content of <3.0ppm; a Na+ content of <2.5ppm; a compressive strength of 800-1000MPa; and an air flow rate of 1.2-1.5L / min for a 50mm×50mm×50mm sample.

[0045] The high-speed disperser used in the preparation of the slurry dispersant was operated at a speed of 1600-1800 r / min. The shear force generated by the high speed allowed the van der Waals forces between molecules to recombine and form the colloidal material mSiO2·nH2O·SiO2. If the speed was insufficient, the silica particles would only remain suspended in deionized water and would not form a colloidal structure. This would affect the subsequent preparation of the preform. During centrifuge operation, the particulate matter in the slurry would detach from the polyurethane foam, failing to achieve a uniform coating effect. For example, if the high-speed disperser speed during the preparation of the high-purity silica dispersant in step 1 was adjusted to 1400 r / min, and after adding high-purity quartz powder, the slurry was continuously dispersed in the high-speed disperser for 15 minutes, and after extrusion in step 2, the centrifuge speed was 300 r / min for 6 minutes, the compressive strength of the prepared product was measured to be 300 MPa, while the air flow rate was only 0.4 L / min. In step 1, during the preparation of the colloidal dispersant, the high-speed disperser speed was adjusted to 2000 r / min. After adding high-purity quartz powder to the slurry, the disperser was continuously operated for 5 minutes. After extrusion in step 2, the slurry was centrifuged at 300 r / min for 10 minutes, resulting in a finished product with a compressive strength of 200 MPa and an air flow rate of only 0.7 L / min. Alternatively, in step 1, during the preparation of the colloidal dispersant, the high-speed disperser speed was adjusted to 2000 r / min. After adding high-purity quartz powder to the slurry, the disperser was continuously operated for 3 minutes. In step 2, the slurry was centrifuged at 800 r / min for 2 minutes, resulting in a finished product with a compressive strength of 500 MPa and an air flow rate of only 1.0 L / min.

[0046] In summary, only by setting reasonable rotation speed and time during the preparation of the colloidal dispersant, and by combining the dispersant's fluidity with the stirring speed and time for adding quartz powder, as well as the rotation speed and time for operation in the centrifuge, can the ideal sintering strength and air permeability be achieved.

[0047] The high-purity quartz diffuser can be machined to the required shape and is installed at the top and on the wall of the vent pipe in the CVD chemical vapor deposition equipment.

[0048] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

Claims

1. A method for preparing a high-purity quartz diffuser, characterized in that, Includes the following steps: Step 1: Preparation of slurry: According to the weight parts, obtain 30-40 parts of high-purity fumed silica and 60-70 parts of deionized water, mix them under high-speed dispersion conditions to obtain a high-purity silica dispersant. After standing, obtain 35 parts of the high-purity silica dispersant and 65 parts of high-purity quartz micro powder, mix them under high-speed dispersion conditions to obtain a slurry. Step 2: Preparing the blank: Immerse the pretreated reticulated polyurethane foam into the slurry, so that the slurry is fully and evenly coated on the polyurethane foam; Step 3: Blank forming: Dry and form the obtained blank within 120 minutes; Step 4: Volatilize the organic foam on the surface of the green body after sintering and molding; Step 5: High-temperature sintering of the green body obtained in step 4; Step 6: Anneal the sintered green body; Step 7: Allow the annealed billet to cool naturally to room temperature in a vacuum sintering furnace; The total metal ion content in the high-purity fumed silica is less than 50 ppm; the conductivity of the deionized water is 16-18 MΩ·cm. The process parameters for mixing high-purity fumed silica and deionized water under high-speed dispersion conditions are: high-speed disperser speed 1600-1800 r / min, dispersion time 120 min, and standing time after mixing 3-5 min. The high-purity quartz micro powder has a purity of over 99.99999% and a particle size D. 50 200-250nm; The process parameters for mixing the high-purity silica dispersant and high-purity quartz micro powder under high-speed dispersion conditions are: high-speed disperser speed 200-300 r / min, dispersion time 30 min; The slurry is coated onto the polyurethane foam, comprising the following steps: immersing the pretreated reticulated polyurethane foam into the slurry, repeatedly squeezing the reticulated polyurethane foam 8-10 times with a PP material pressure head applying a pressure of 5N, then placing the reticulated polyurethane foam and slurry in a centrifuge at 500-600r / min for 3-4min; removing the reticulated polyurethane foam and placing it on a PP material filter screen to remove excess slurry using pure compressed air.

2. The method for preparing a high-purity quartz diffuser according to claim 1, characterized in that, The process of removing excess slurry from the reticulated polyurethane foam using pure compressed air involves the following parameters: the air nozzle is positioned 5-10 cm from the surface of the blank and perpendicular to the surface for 2-3 minutes, with the nozzle at least 1 cm from the edge of the reticulated polyurethane foam, and the air pressure is 2.5 MPa.

3. The method for preparing a high-purity quartz diffuser according to claim 1, characterized in that, The pretreated reticulated polyurethane foam is placed in an ultrasonic cleaning tank and cleaned for 30 seconds to remove excess particles adhering to the surface. It is then washed with deionized water, placed in an oven, and baked for 30 minutes at an oven temperature of 50-55°C.

4. The method for preparing a high-purity quartz diffuser according to claim 1, characterized in that, The process of drying and shaping the obtained blank includes: drying in a ventilated drying oven at a temperature of 100-150℃ for 60 minutes, with pure air ventilating upwards perpendicular to the lower surface of the blank.

5. The method for preparing a high-purity quartz diffuser according to claim 1, characterized in that, The heating procedure for the volatile ignition organic foam is as follows: in a vacuum sintering furnace, the temperature is raised from room temperature to 500°C at a heating rate of 5°C / min and held for 1 hour; the temperature is raised from 500°C to 800°C at a heating rate of 5°C / min and held for 1 hour; and the temperature is raised from 800°C to 1200°C at a heating rate of 5°C / min and held for 1 hour.

6. The method for preparing a high-purity quartz diffuser according to claim 1, characterized in that, The high-temperature sintering is carried out in a vacuum sintering furnace, where the temperature is increased from 1200°C to 1750°C at a heating rate of 10°C / min, and then held at 1750°C for 30 minutes.

7. The method for preparing a high-purity quartz diffuser according to claim 1, characterized in that, The annealing process involves naturally cooling the material to 500°C in a vacuum sintering furnace and holding it there for 30-40 minutes.

8. A high-purity quartz diffuser prepared according to any one of claims 1-7, characterized in that, The high-purity quartz diffuser can be machined to the required shape and is installed at the top and on the wall of the vent pipe in the CVD chemical vapor deposition equipment.