Method and process for repairing high-purity quartz crucible

Abstract

The invention discloses a method and a process for repairing a high-purity quartz crucible, and relates to the field of high-purity quartz material processing. The method comprises the steps of box opening inspection and repairability judgment, cleaning treatment, defect grading judgment, defect removal, oxyhydrogen flame welding repair, dehydroxylation treatment, secondary cleaning and drying, quality detection and qualified product packaging. Reparability judgment has a clear standard, a grinding head with a specific particle size and a polishing solution are used for defect removal, a high-purity material with a matched thermal expansion coefficient is adopted for welding, dehydroxylation is carried out in two stages, and quality detection covers air tightness, roughness and impurity content. The method solves the problems of resource waste, poor repairing quality and the like in the prior art, can effectively recover the performance of the crucible and improve the qualification rate, and is suitable for repairing semiconductors and photovoltaic crucibles.

Description

Technical Field

[0001] This invention relates to the field of high-purity quartz material processing technology, specifically to a method and process for repairing high-purity quartz crucibles. It is applicable to the defect repair of high-purity quartz crucibles such as semiconductor-grade and photovoltaic-grade crucibles, and can effectively restore the performance of the crucibles, reduce production costs, and improve resource utilization. Background Technology

[0002] High-purity quartz crucibles are critical consumables in the semiconductor and photovoltaic industries. Their production process demands extremely high precision, inevitably leading to various defects such as black spots on the inner wall, bubbles, perforations, and uneven surfaces. These defects can severely impact the crucible's performance and even render the product unusable.

[0003] Currently, existing repair technologies have many shortcomings. Regarding repairability assessment, there is a lack of clear and unified standards, often relying on operator experience. This leads to some repairable crucibles being wrongly judged as unusable, resulting in resource waste. It also risks allowing crucibles that do not meet repair criteria to enter the repair process, ultimately leading to substandard product quality after repair. In the defect handling process, the selection of tool grit size is often inappropriate, and the transitions between coarse grinding, fine grinding, and polishing are not scientifically sound. This can easily leave new scratches or cause over-grinding at the repair site, affecting the surface quality of the crucible.

[0004] During welding repair, the purity of the welding materials used is not high, and the difference in thermal expansion coefficients between them and the base crucible is significant. This leads to problems such as cracking and detachment at the welded area during subsequent use, compromising the reliability of the repair. Inappropriate settings in the dehydroxylation process parameters result in either incomplete dehydroxylation, with residual hydroxyl groups being released during high-temperature use and affecting material growth within the crucible; or excessively high temperatures or prolonged treatment times, damaging the crucible base. Furthermore, the quality inspection process suffers from incomplete testing items and insufficient accuracy, making it difficult to accurately assess the performance of the repaired crucible. This could lead to substandard products entering the market and impacting downstream production. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems by providing a method and process for repairing high-purity quartz crucibles.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a method and process for repairing high-purity quartz crucibles, comprising the following steps: S1: Unpacking Inspection and Repairability Determination: Unpacking inspection is carried out on high-purity quartz crucibles that have defects in production to determine whether they meet the repair conditions. S2: Cleaning treatment: Surface cleaning of the repairable crucible; S3: Defect Classification: The crucible is classified into different repair levels according to the type and severity of the defect; S4: Defect removal: Use special tools to perform rough grinding, fine grinding and fine polishing on the defective areas in sequence; S5: Oxyhydrogen flame welding repair: Using an oxyhydrogen flame in conjunction with special quartz welding materials to fill perforated or deep pit defects by welding. S6: Dehydroxylation treatment: Place the repaired crucible in a vacuum or inert atmosphere for dehydroxylation; S7: Secondary cleaning and drying: Clean and dry the crucible after dehydroxylation; S8: Quality Inspection: Inspect the airtightness, flatness, and impurity content of the repaired area; S9: Packaging of qualified products: Pack and store crucibles that have passed the inspection.

[0007] Furthermore, the repairability determination criteria in step S1 include: The defect depth shall not exceed 30% of the crucible wall thickness; The diameter of the black spot impurities is ≤0.5mm and the distribution density is <5 spots / cm²; No penetrating cracks or structural damage.

[0008] Furthermore, the special tool in step S4 is a combination tool set including a diamond grinding head, wherein: Coarse grinding uses a grinding head with a particle size of 80-120 mesh; Fine grinding uses grinding heads with a particle size of 400-600 mesh; Fine polishing uses nano-grade silica polishing slurry.

[0009] Furthermore, the special quartz welding material in step S5 must meet the following requirements: SiO2 purity ≥ 99.995%; Hydroxyl content ≤ 5 ppm; The difference in thermal expansion coefficient between the base crucible and the base crucible is less than 5%.

[0010] Furthermore, the dehydroxylation treatment in step S6 is divided into two stages: First stage: Keep warm at 800-1000℃ and vacuum degree ≤10-³Pa for 2-4 hours; Second stage: Keep warm at 1200-1300℃ in an argon atmosphere for 1-2 hours.

[0011] Furthermore, the quality inspection in step S8 includes: Helium mass spectrometer leak detector for airtightness testing (leakage rate <1×10⁻) 9 Pa·m³ / s); Surface roughness (Ra≤0.1μm) is measured using a white light interferometer. GD-MS analysis showed that the total amount of metallic impurities in the repaired area was ≤50 ppb.

[0012] The advantages of this invention compared to existing technologies are: by clarifying repairability standards, misjudgment is avoided; by rationally selecting molds and welding materials, adopting scientific dehydroxylation processes and comprehensive and accurate testing, the defects of existing technologies such as resource waste, poor repair quality, and low reliability are solved, thereby improving repair efficiency and product qualification rate. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of a high-purity quartz crucible repair method and process according to the present invention. Detailed Implementation

[0014] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0015] Working principle of the invention: The high-purity quartz crucible repair method and process of the present invention achieves effective repair of defective crucibles through a series of orderly and precise steps, the principle of which is as follows: The first step is step S1: unpacking inspection and repairability assessment. Using visual inspection equipment and thickness measuring tools, a comprehensive inspection is conducted on the high-purity quartz crucibles that have defects during production. Based on the established repairability assessment criteria—defect depth not exceeding 30% of the crucible wall thickness, black spot impurities with a diameter ≤0.5mm and a distribution density <5 per cm², and no penetrating cracks or structural damage—the crucible is determined to meet the repair conditions. This step ensures that only crucibles with repair value proceed to subsequent processes, avoiding resource waste.

[0016] Next is step S2: cleaning. Deionized water and ultrasonic cleaning equipment are used to clean the surface of the repairable crucible, removing dust, oil and other impurities to provide a clean surface for subsequent defect handling and welding repair, and to prevent impurities from affecting the repair effect.

[0017] Step S3: Defect Classification and Determination. Based on the type of defect (such as black spots, bubbles, perforations, unevenness, etc.) and its severity, the crucible is classified into different repair levels using an image recognition system, so that targeted repair measures can be taken subsequently to improve repair efficiency and quality.

[0018] In step S4: Defect removal, a combination tool set including diamond grinding heads is used to treat the defective area in the order of coarse grinding, fine grinding, and fine polishing. Coarse grinding uses grinding head 1 with a grit of 80-120 mesh to quickly remove obvious defects; fine grinding uses grinding head 2 with a grit of 400-600 mesh to further refine the surface and reduce the traces left by coarse grinding; fine polishing uses nano-grade silica polishing slurry 3 to achieve a high degree of smoothness and gloss on the repaired area.

[0019] For perforated or deep pit defects, proceed to step S5: oxyhydrogen flame welding repair. Use an oxyhydrogen flame torch 4, along with a dedicated quartz welding material 5, for overlay welding and filling. The dedicated quartz welding material 5 must meet the following requirements: SiO2 purity ≥ 99.995%, hydroxyl content ≤ 5 ppm, and thermal expansion coefficient difference < 5% between it and the substrate crucible, to ensure good bonding between the welded area and the substrate and avoid cracking and other problems caused by material differences.

[0020] Step S6: The dehydroxylation treatment is divided into two stages. In the first stage, the repaired crucible is placed in a vacuum furnace 6 and kept at 800-1000℃ and a vacuum degree ≤10-³Pa for 2-4 hours to remove most of the hydroxyl groups. In the second stage, it is kept in a high-temperature furnace 7 at 1200-1300℃ and an argon atmosphere for 1-2 hours to further and thoroughly remove the hydroxyl groups, while eliminating the internal stress generated during the repair process.

[0021] Step S7: Secondary cleaning and drying. The crucible after dehydroxylation is cleaned again with deionized water to remove any impurities that may remain on the surface. Then, it is placed in a clean drying oven 8 to air dry to prevent secondary contamination.

[0022] Finally, there are steps S8: quality inspection and S9: packaging of qualified products. The airtightness of the repaired area is tested using a helium mass spectrometer leak detector 9, requiring a leakage rate <1×10⁻ 9 Pa·m³ / s; Surface roughness is measured using a white light interferometer 10 to ensure Ra ≤ 0.1 μm; The total amount of metallic impurities in the repair area is analyzed using a GD-MS analyzer 11, and must be ≤ 50 ppb. Crucibles that pass the tests are then packed and stored, completing the entire repair process.

[0023] The following describes in detail the high-purity quartz crucible repair method and process of the present invention with reference to specific operations: In step S1, the operator uses a dedicated thickness measuring instrument to measure the defects in the crucible, and at the same time observes the diameter and distribution density of black spot impurities under a microscope. Combined with visual inspection, the operator judges whether there are penetrating cracks or structural damage. The operator strictly selects repairable crucibles according to the criteria that the defect depth does not exceed 30% of the crucible wall thickness, the diameter of black spot impurities is ≤0.5mm and the distribution density is <5 pieces / cm², and there are no penetrating cracks or structural damage.

[0024] In step S2, the repairable crucible is placed in an ultrasonic cleaning tank, deionized water is added, the ultrasonic frequency is set to 40kHz, and the cleaning time is 15 minutes. After cleaning, the crucible is removed and the surface moisture is drained.

[0025] In step S3, the surface of the crucible is photographed using an image acquisition device, and the defect type and severity are analyzed using image recognition software. The crucible is classified into three levels: minor defects (such as a few small black spots), moderate defects (such as small areas of unevenness), and severe defects (such as small areas of perforation).

[0026] In step S4, for crucibles with minor defects, rough grinding is first performed using a 100-mesh diamond grinding head 1 to remove surface black spots, with the grinding depth controlled at 0.1-0.2 mm; then fine grinding is performed using a 500-mesh diamond grinding head 2, with a grinding depth of 0.05-0.1 mm; finally, nano-grade silica polishing slurry 3 is applied, and fine polishing is performed using a polishing cloth for 5 minutes. For crucibles with moderate defects, rough grinding is performed using an 80-mesh grinding head 1, fine grinding is performed using a 400-mesh grinding head 2, and the fine polishing time is extended to 8 minutes.

[0027] Step S5 targets perforations or deep pits in severe defects. First, adjust the flame temperature of the oxyhydrogen flame torch 4 to about 2000°C. Then, heat the special quartz welding material 5 (SiO2 purity 99.996%, hydroxyl content 4ppm, thermal expansion coefficient difference from the substrate 3%) to a molten state and fill the defect area with weld. During the filling process, ensure that the welding material and the substrate are fully fused. After the weld is completed, allow it to cool naturally to room temperature.

[0028] In step S6, the dehydroxylation process is carried out in the following stages: First, the crucible is placed in vacuum furnace 6, the furnace door is closed, the vacuum is drawn to 10⁻³ Pa, the temperature is raised to 900℃, and the temperature is held for 3 hours; then argon gas is introduced to raise the temperature inside the furnace to 1250℃ and the temperature is held for 1.5 hours to complete the dehydroxylation.

[0029] In step S7, the dehydroxylated crucible is placed back into the ultrasonic cleaning tank, cleaned with deionized water for 10 minutes, and then placed in the drying oven 8, with the temperature set at 80℃, and dried for 2 hours.

[0030] In step S8, a quality inspection is performed using a helium mass spectrometer leak detector 9 to check the repaired area, ensuring a leakage rate of <1×10⁻. 9 Pa・m³ / s; Surface roughness is measured using a white light interferometer 10, requiring Ra≤0.1μm; The total amount of metallic impurities in the repair area is detected by a GD-MS analyzer 11, requiring ≤50ppb.

[0031] In step S9, the crucibles that have passed the test are placed in a special anti-static packaging box, labeled, and stored in a clean warehouse.

[0032] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method and process for repairing a high-purity quartz crucible, characterized in that: Includes the following steps: S1: Unpacking Inspection and Repairability Determination: Unpacking inspection is carried out on high-purity quartz crucibles that have defects in production to determine whether they meet the repair conditions. S2: Cleaning treatment: Surface cleaning of the repairable crucible; S3: Defect Classification: The crucible is classified into different repair levels according to the type and severity of the defect; S4: Defect removal: Use special tools to perform rough grinding, fine grinding and fine polishing on the defective areas in sequence; S5: Oxyhydrogen flame welding repair: Using an oxyhydrogen flame in conjunction with special quartz welding materials to fill perforated or deep pit defects by welding. S6: Dehydroxylation treatment: Place the repaired crucible in a vacuum or inert atmosphere for dehydroxylation; S7: Secondary cleaning and drying: Clean and dry the crucible after dehydroxylation; S8: Quality Inspection: Inspect the airtightness, flatness, and impurity content of the repaired area; S9: Packaging of qualified products: Pack and store crucibles that have passed the inspection.

2. The method and process for repairing a high-purity quartz crucible according to claim 1, characterized in that: The repairability determination criteria in step S1 include: The defect depth shall not exceed 30% of the crucible wall thickness; The diameter of the black spot impurities is ≤0.5mm and the distribution density is <5 spots / cm²; No penetrating cracks or structural damage.

3. The method and process for repairing a high-purity quartz crucible according to claim 1, characterized in that: The special tool in step S4 is a combination tool set including a diamond grinding head, wherein: Coarse grinding uses a grinding head with a particle size of 80-120 mesh; Fine grinding uses grinding heads with a particle size of 400-600 mesh; Fine polishing uses nano-grade silica polishing slurry.

4. The method and process for repairing a high-purity quartz crucible according to claim 1, characterized in that: The special quartz welding material used in step S5 must meet the following requirements: SiO2 purity ≥ 99.995%; Hydroxyl content ≤ 5 ppm; The difference in thermal expansion coefficient between the base crucible and the base crucible is less than 5%.

5. The method and process for repairing a high-purity quartz crucible according to claim 1, characterized in that: The dehydroxylation treatment in step S6 is divided into two stages: Phase 1: At 800-1000℃ and a vacuum degree ≤10 - Insulate at ³Pa for 2-4 hours; Second stage: Keep warm at 1200-1300℃ in an argon atmosphere for 1-2 hours.

6. The method and process for repairing a high-purity quartz crucible according to claim 1, characterized in that: The quality inspection in step S8 includes: Helium mass spectrometer leak detector for airtightness testing (leakage rate <1×10⁻) 9 Pa·m³ / s); Surface roughness (Ra≤0.1μm) is measured using a white light interferometer. GD-MS analysis showed that the total amount of metallic impurities in the repaired area was ≤50 ppb.

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