Semiconductor-grade large-size quartz crucible and preparation method thereof

Abstract

The application provides a preparation method of a semiconductor-grade large-size quartz crucible, and the preparation method comprises an arc melting device used in a vacuum arc melting process, wherein the arc melting device comprises at least six electrodes; and in the vacuum arc melting process, the current of the envelope treatment is 2000-2500 A, and the distance from the bottom of the electrode to the end of the mold is 10-30 mm. The preparation method reduces the R-angle thickness, improves the uniformity of heat transfer, and further improves the whole-bar rate and quality of the prepared single crystal silicon; meanwhile, the preparation method also reduces the residual number of micro-bubbles after the vacuum arc melting, and avoids the influence of the micro-bubble rupture on the single crystal silicon growth in the crystal pulling process.

Description

Technical Field

[0001] This invention belongs to the field of single-crystal silicon preparation and relates to a semiconductor-grade large-size quartz crucible and its preparation method. Background Technology

[0002] Single-crystal silicon, the starting material for most semiconductor electronic components, is typically prepared using the so-called Czochralski (“CZ”) method. Using the CZ method, crystal growth is most usually carried out in a crystal pulling furnace, where polycrystalline silicon (“polysilicon”) is placed in a crucible and melted by heaters surrounding the outer surface of the crucible's sidewalls. A seed crystal is brought into contact with the molten silicon, and the grown single-crystal ingot is extracted using a crystal pulling machine.

[0003] During crystal growth, prolonged exposure of the crucible's inner sidewall to the high-temperature molten silicon causes the molten silicon to react with the quartz crucible, leading to the dissolution of the inner surface of the crucible's sidewall. This exposes bubbles in the crucible's sidewall to the molten silicon, which continues to dissolve into the crucible wall and consequently into the bubble walls. At some point, the bubble walls may break down and become concave, while gas is released from within the bubbles and quartz particles are released from the crucible and / or bubble sidewalls into the melt. These particles can disrupt the single-crystal structure, limiting the yield of single crystals. Furthermore, the presence of bubble cavities or voids along the inner surface of the crucible can be sites of gas nucleation. When gas nucleates and grows into small bubbles, these bubbles may enter the growing silicon, resulting in voids in the crystal that do not meet specifications. Reducing or eliminating bubbles in the crucible will ensure that voids in the crystal are minimized to achieve acceptable crystal performance within specifications. Thermal field uniformity: The thickness of the radius (R-angle) has a significant impact on the thermal conductivity of the crucible.

[0004] This patent (CN104926086A) discloses a melting electrode device for large-diameter quartz crucibles, comprising six graphite electrodes. Through a linkage design between a copper rod and grippers (controlled by a lead screw and nut), synchronous adjustment of the electrodes is achieved. The six graphite electrodes, inserted into a graphite mold, provide a large-area heat source, increasing the melting temperature and thus optimizing the shape and vitrification quality of large-size quartz crucibles. It is suitable for manufacturing large-diameter crucibles of 32 inches and above, solving the problem of insufficient heating range in traditional three-electrode systems.

[0005] The manufacturing method of quartz glass crucibles (JP2008-244521) addresses the problems of unstable arc and uneven heating in traditional three-phase, three-electrode structures for large crucibles (e.g., over 32 inches). This patent attempts a six-phase, six-electrode structure, but finds that the central region is prone to overheating, leading to insufficient uniformity. By adjusting the horizontal / vertical distance ratio between the electrode tip and the surface of the quartz powder molding body (e.g., W / R, H / R parameters), the stability of the arc discharge is optimized; a ring-shaped electrode configuration is proposed to avoid central arc concentration, thereby improving the heating uniformity of large-diameter crucibles.

[0006] In existing techniques, when preparing quartz crucibles using the vacuum arc casting method, the inner surface of the crucible is in contact with air, making it impossible to completely remove air bubbles through vacuum. Therefore, microbubbles remain on the surface. These microbubbles expand and burst during crystal pulling, causing tiny quartz particles to fall into the molten silicon, thus reducing the purity of the single-crystal silicon. The bursting of these microbubbles on the inner surface of the crucible also significantly increases surface fluctuations during crystal pulling, leading to difficulties and increased wire breakage. Furthermore, the bursting areas are more prone to crystallization, and the shedding of these crystals also affects the purity of the single-crystal silicon. Moreover, most domestic manufacturers increase current ablation to address surface bubbles, resulting in increased bottom movement and thicker radius corners. This leads to uneven thermal distribution during customer use, affecting the crystal growth rate and morphology. Summary of the Invention

[0007] To address the technical problems existing in the prior art, this invention provides a semiconductor-grade large-size quartz crucible and its preparation method. This preparation method reduces the thickness of the radius (R-angle), improves the uniformity of heat transfer, and thus improves the overall yield and quality of single-crystal silicon ingots. Simultaneously, it reduces the number of residual microbubbles after vacuum arc melting, avoiding the impact of microbubble rupture during crystal pulling on single-crystal silicon growth.

[0008] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0009] One objective of this invention is to provide a method for preparing a semiconductor-grade large-size quartz crucible, the method comprising an arc melting device using at least six electrodes during a vacuum arc melting process;

[0010] During the vacuum arc melting process, the current for the sealing treatment is 2000~2500 A, and the distance from the bottom of the electrode to the mold port is 10~30 mm.

[0011] As a preferred technical solution of the present invention, the electric arc melting device includes 6 electrodes, which are arranged in a ring at equal intervals.

[0012] As a preferred embodiment of the present invention, the electrode spacing is 45~55 mm.

[0013] As a preferred technical solution of the present invention, the sealing treatment time is 8~12 s.

[0014] As a preferred technical solution of the present invention, the thickness of the cover layer obtained by the cover treatment is 0.5~2 mm.

[0015] As a preferred technical solution of the present invention, quartz sand mold forming is performed before vacuum arc melting.

[0016] As a preferred technical solution of the present invention, the quartz sand mold forming includes: pouring quartz sand into the mold, and sequentially performing outer surface forming, straight wall forming, and bottom and R-angle forming.

[0017] The second objective of this invention is to provide a semiconductor-grade large-size quartz crucible, which is prepared by the method for preparing a semiconductor-grade large-size quartz crucible provided in the first objective.

[0018] As a preferred technical solution of the present invention, the size of the semiconductor-grade large-size quartz crucible is not less than 32 inches.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] (1) The present invention provides a semiconductor-grade large-size quartz crucible and its preparation method. The preparation method uses an arc melting device with 6 electrodes and a low-current fast sealing method to effectively reduce the thickness of the R-angle of the quartz crucible, improve the uniformity of heat transfer, and improve the overall efficiency and quality of the preparation of single crystal silicon rods.

[0021] (2) The present invention provides a semiconductor-grade large-size quartz crucible and its preparation method. The preparation method reduces the number of microbubbles remaining after vacuum arc melting by using a low-current rapid sealing method, thereby avoiding the impact of microbubble rupture on single-crystal silicon growth during crystal pulling.

[0022] (3) The present invention provides a semiconductor-grade large-size quartz crucible and its preparation method. The low-current rapid sealing method used in the preparation method helps to shorten the production cycle and improve production efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the vacuum arc melting structure in the method for preparing a semiconductor-grade large-size quartz crucible provided by the present invention.

[0024] Figure 2 This is a comparison diagram of three-electrode and six-electrode arc melting devices.

[0025] In the diagram: 1 is the sealing layer - port; 2 is the mold vacuum extraction hole; 3 is the steel mold; 4 is the sealing layer - straight wall; 5 is the quartz crucible bubble layer; 6 is the transparent surface layer of the quartz crucible; 7 is the sealing layer - R-corner; 8 is the sealing layer - bottom.

[0026] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0027] The technical solution of this application will be further described below through specific implementation methods.

[0028] The present invention provides a method for preparing a semiconductor-grade large-size quartz crucible, the method comprising an arc melting device used in a vacuum arc melting process including at least 6 electrodes;

[0029] During the vacuum arc melting process, the current for the sealing treatment is 2000~2500 A, and the distance from the bottom of the electrode to the mold port is 10~30 mm.

[0030] The current for the sealing process can be 2000A, 2100A, 2200A, 2300A, 2400A, or 2500A, etc., and the distance from the bottom of the electrode to the mold port can be 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm, 28 mm, or 30 mm, etc., but is not limited to the listed values. Other unlisted values ​​within the above ranges are also applicable.

[0031] In one specific embodiment of the present invention, the electric arc melting device includes six electrodes arranged in a ring at equal intervals.

[0032] In this invention, for large-size semiconductor-grade quartz crucibles (32 inches and above), the increased current required for ablation during production leads to significant impact on the bottom during melting, resulting in substantial movement and thicker radius (R-corner). This large impact easily causes bubble accumulation at the R-corner. For three-electrode systems, increasing the opening and closing angle increases the radiation area, but this also leads to poor arc stability and large fluctuations. Six-electrode systems can avoid these risks. However, using only a six-electrode system still has limited effectiveness in reducing the R-corner thickness and bubble reduction in quartz crucibles. Therefore, this invention combines low-current, rapid sealing to achieve optimal R-corner thinning and bubble reduction. The reason for this is:

[0033] 1. More uniform heat distribution

[0034] Low-current, rapid sealing means lower heating power and electrodes positioned close to the bottom of the crucible. This configuration results in: 1) Less heating in the radius (R-corner) area: Heat is concentrated at the center of the crucible bottom, with slower melting rates at the edges and corners (R-corners), reducing material deposition rates and minimizing localized over-thickening. 2) Reduced fluidity of fused silica: At low currents, the viscosity of fused silica is higher, making it less prone to excessive accumulation at the R-corners due to gravity or centrifugal force, thus avoiding uneven thickness. 3) Suppression of the "edge effect": High currents or high currents tend to concentrate heat at the top or edges of the crucible, while low currents concentrate the heat field at the bottom, reducing excessive material deposition at the R-corners due to heat convection or radiation.

[0035] 2. Reasons for reducing microbubbles

[0036] 1) Slow gas release: Gases (such as H2O and CO2) in the quartz sand are released at high temperatures. A smaller current allows for a more gradual heating rate, giving the gas sufficient time to escape from the melt instead of becoming trapped and forming microbubbles. 2) Reduced risk of localized overheating: High current can cause localized instantaneous high temperatures, leading to rapid melting of the quartz and the encapsulation of gas; a smaller current avoids violent reactions and reduces bubble formation. 3) Improved melt uniformity: Low-level heating allows the melting process to proceed gradually from bottom to top, making it easier for bubbles to escape upwards through the lower viscosity melt, rather than accumulating at corners and causing bubble traps. 4) Rapid sealing: This also solves the problem of uneven sealing thickness in large crucibles due to slow sealing speeds, which makes it difficult to eliminate microbubbles during later melting processes, resulting in excessive microbubbles.

[0037] 3. Balancing process optimization

[0038] While low-current, rapid sealing can improve the thickness of the radius corner and reduce microbubbles, it is important to note that excessively reducing the current or position may lead to insufficient melting, resulting in ineffective sealing inside the crucible, failure to reach the vacuum limit in a short time, and significant variations in sealing thickness, causing severe microbubbles. Optimal parameters need to be determined experimentally.

[0039] In one specific embodiment of the present invention, the spacing between the electrodes is 45~55 mm, such as 45 mm, 46 mm, 47 mm, 48 mm, 49 mm, 50 mm, 51 mm, 52 mm, 53 mm, 54 mm or 55 mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] In one specific embodiment of the present invention, the sealing treatment time is 8 to 12 s, such as 8 s, 8.5 s, 9 s, 9.5 s, 10 s, 10.5 s, 11 s, 11.5 s or 12 s, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] In one specific embodiment of the present invention, the thickness of the cover layer obtained by the cover treatment is 0.5~2 mm, such as 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm or 2 mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and 0.5~1 mm is more preferably used.

[0042] In one specific embodiment of the present invention, the vacuum arc melting process includes, in addition to the sealing treatment, venting treatment, transparent layer melting and bubble layer melting, in the following order: venting treatment, sealing treatment, transparent layer melting and bubble layer melting.

[0043] In one specific embodiment of the present invention, the specific parameters for venting treatment, transparent layer melting, and bubble layer melting can be adjusted according to the production requirements of the quartz crucible and the type of material, and are not further limited here.

[0044] In one specific embodiment of the present invention, a quartz sand mold is formed before vacuum arc melting.

[0045] In one specific embodiment of the present invention, the quartz sand mold forming includes: pouring quartz sand into the mold, and sequentially performing outer surface forming, straight wall forming, and bottom and R-corner forming.

[0046] In one specific embodiment of the present invention, the process parameters for mold forming, i.e. the parameters for each specific forming stage, are all conventional parameters in the field of quartz crucibles. They can be adjusted according to the production needs of quartz crucibles and the type of materials, and are not further limited here.

[0047] In one specific embodiment of the present invention, the method for preparing a semiconductor-grade large-size quartz crucible may further include cooling treatment, sandblasting treatment, and demolding treatment after vacuum arc melting.

[0048] In one specific embodiment of the present invention, the cooling method can be natural cooling, air cooling, or water cooling, etc. The cooling rate can be adjusted according to the production requirements of the quartz crucible and the type of material, and is not further limited here.

[0049] In one specific embodiment of the present invention, sandblasting refers to spraying quartz sand onto the surface of the crucible blank with a spray gun to remove surface deposits.

[0050] In one specific embodiment of the present invention, demolding can be performed using any common demolding method, such as tapping the outer surface of the mold to remove the quartz crucible blank from the mold.

[0051] In one specific embodiment of the present invention, the method for preparing a semiconductor-grade large-size quartz crucible includes the following steps:

[0052] Step 1: Weighing the raw materials required for preparation according to the formula, select high-purity natural quartz sand, and polish it using a polishing machine. Add the required weight of quartz sand to the mold and form the crucible blank through the mold.

[0053] Step 2: Mold forming: Add the required weight of quartz sand to the mold and form the base through the mold; add the required weight of bubble layer quartz sand, intermediate composite layer additive powder, and transparent layer quartz sand to the mold in sequence and form the functional layer through the mold.

[0054] Step 3 Vacuum Arc Melting: The mold is transferred into the arc melting furnace, and a high-temperature arc is released through the graphite electrode to melt the quartz sand. The arc melting device used in the vacuum arc melting process includes at least 6 electrodes, and the low-current rapid sealing process is carried out during the vacuum arc melting process.

[0055] Step 4: Cooling: Cool the mold to form a quartz crucible blank;

[0056] Step 5: Sandblasting: Use a spray gun to spray quartz sand onto the surface of the crucible blank to remove surface deposits;

[0057] Step 6: Demolding: Tap the outer surface of the mold to remove the crucible blank from the mold.

[0058] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0059] Example 1

[0060] This embodiment provides a method for preparing a semiconductor-grade large-size quartz crucible, the method comprising:

[0061] The arc melting device used in the vacuum arc melting process includes 6 electrodes arranged in a ring with equal spacing of 50 mm. The current for the sealing process is 2250 A. The distance from the bottom of the electrode to the mold port is 20 mm. The sealing process takes 8 s and the thickness of the sealing layer is 0.5 mm.

[0062] Example 2

[0063] Except for the electrode spacing being 45 mm, all other conditions in this embodiment are the same as in Embodiment 1.

[0064] Example 3

[0065] Except for the electrode spacing being 55 mm, all other conditions in this embodiment are the same as in Embodiment 1.

[0066] Example 4

[0067] Except for the current of 2000 A used for the sealing treatment, all other conditions in this embodiment are the same as in Embodiment 1.

[0068] Example 5

[0069] Except for the current of 2500 A used for the sealing treatment, all other conditions in this embodiment are the same as in Embodiment 1.

[0070] Example 6

[0071] Except for the distance from the bottom of the electrode to the mold port being 10 mm, all other conditions in this embodiment are the same as in Embodiment 1.

[0072] Example 7

[0073] Except for the distance from the bottom of the electrode to the mold port being 30 mm, all other conditions in this embodiment are the same as in Embodiment 1.

[0074] Example 8

[0075] Except for the sealing treatment time of 10 s and the sealing layer thickness of 1 mm, all other conditions in this embodiment are the same as in Embodiment 1.

[0076] Example 9

[0077] Except for the sealing treatment time of 12 seconds and the sealing layer thickness of 2 mm, all other conditions in this embodiment are the same as in Embodiment 1.

[0078] Comparative Example 1

[0079] Except for the number of electric arcs in the electric arc melting device, the conditions in this comparative example are the same as those in Example 1.

[0080] Comparative Example 2

[0081] Except for the distance from the bottom of the electrode to the mold port being 80 mm, the conditions in this comparative example are the same as those in Example 1.

[0082] Comparative Example 3

[0083] Except for the distance from the bottom of the electrode to the mold port being -30 mm (the electrode is inserted deep into the mold), the conditions in this comparative example are the same as in Example 1.

[0084] Comparative Example 4

[0085] Except for the current of 4000 A used for the sealing treatment, the conditions in this comparative example are the same as those in Example 1.

[0086] Comparative Example 5

[0087] Except for the current of 4000 A for the sealing treatment and the distance from the bottom of the electrode to the mold port of 80 mm, the conditions in this comparative example are the same as those in Example 1.

[0088] Comparative Example 6

[0089] Except for the current of 4000 A for the sealing treatment and the distance from the bottom of the electrode to the mold port of -20 mm, the conditions of this comparative example are the same as those of Example 1.

[0090] Comparative Example 7

[0091] Except for the current of 1000 A used for the sealing treatment, the conditions in this comparative example are the same as those in Example 1.

[0092] In Examples 1-9 and Comparative Examples 1-7, the preparation method of the quartz crucible blank includes sequential molding, vacuum arc melting molding, cooling, sandblasting, and demolding.

[0093] The steps involved in mold forming include:

[0094] Step 1: Rotate the melting and rotating mold 45-56° and rotate it 65-70 rpm. Pour the natural quartz sand from the outer surface into the mold, and then use a forming rod to form straight-walled natural high-purity quartz sand.

[0095] Part Two: Rotate the melting rotary mold to 0°, rotate the speed to 65~70 rpm, and use the forming rod to scrape off the natural high-purity quartz sand from the straight wall part so that it falls to the bottom until the entire outer surface of the crucible is formed.

[0096] Step 3: Use a molding machine to form a straight wall from a portion of the high-purity natural quartz sand until the straight wall is formed;

[0097] Step 4: Finally, use the remaining high-purity natural quartz sand for the bottom and rounded corners to complete the final shaping.

[0098] Vacuum arc melting molding includes sequential processes of venting, sealing, transparent layer melting, and bubble layer melting. The specific steps are as follows:

[0099] During the exhaust process, a mixture of helium (85% by volume) and oxygen (15% by volume) is introduced and a vacuum is drawn. The density of the elemental gas is less than that of air.

[0100] During the encapsulation process, the graphite electrode is arc-initiated to maintain the flow of mixed gas and the vacuum process.

[0101] During the melting of the transparent layer, a mixed gas is continuously introduced while a vacuum is maintained.

[0102] During the melting of the bubble layer, the introduction of mixed gas is stopped and a vacuum is drawn.

[0103] After the bubble layer melts, the graphite arc is turned off, and the quartz crucible is rapidly cooled; after cooling, it is removed from the furnace, and the melting is complete.

[0104] The steps and cooling conditions for vacuum arc melting are shown in Table 1.

[0105] Table 1

[0106]

[0107] After cooling, use a spray gun to spray quartz sand onto the surface of the crucible blank to remove surface deposits, and tap the outer surface of the mold to remove the crucible blank from the mold.

[0108] The base quartz sand is high-purity natural quartz sand with a purity of over 99.99% silica. The bubble layer uses natural high-purity quartz sand NC4A, and the transparent layer uses synthetic quartz sand.

[0109] The number of straight walls, radius (R-angle), and bottom microbubbles of the quartz crucibles prepared in Examples 1-9 and Comparative Examples 1-7 were statistically analyzed, and the thickness of the radius (R-angle) was tested. The results are shown in Table 2.

[0110] The method for testing the number of bubbles combines optical microscopy with image processing. The specific steps are as follows:

[0111] 1. Sample preparation: Slice or polish the surface to ensure air bubbles are exposed on the observation surface;

[0112] 2. Microscopic imaging: High-resolution images are captured using an optical microscope (scale bar needs to be calibrated);

[0113] 3. Image Processing:

[0114] (1) Use software (such as ImageJ, MATLAB) to perform threshold segmentation and extract the bubble contour;

[0115] (2) Automatically count the number of bubbles;

[0116] 4. Results output: number of bubbles per unit area (bubbles / mm²) and distribution histogram.

[0117] The thickness of the radius (R-angle) was tested using an ultrasonic thickness gauge.

[0118] Table 2

[0119]

[0120] The test results in Table 2 show that the quartz crucibles prepared by the methods provided in Examples 1-9 all exhibit significantly reduced R-corner thickness and a smaller number of bubbles at the R-corner. Comparative Example 1, using a 3-electrode system, shows a significantly thicker R-corner and a substantial increase in the number of bubbles at the R-corner compared to Example 1. Comparative Examples 2 and 3 employ high-position and insertion-in-mold heating methods, respectively. While the R-corner thickness in Comparative Example 2 is further reduced compared to Example 1, the number of bubbles at the R-corner increases significantly. Comparative Example 3 shows an increase in both R-corner thickness and the number of bubbles at the R-corner compared to Example 1. Comparative Example 4 uses a high-current sealing treatment, resulting in an increase in both R-corner thickness and the number of bubbles at the R-corner compared to Example 1. Comparative Example 5 uses a high-position high-current sealing treatment; although the R-corner thickness is reduced compared to Example 1, the number of bubbles at the R-corner increases significantly. Comparative Example 6 uses a high-current insertion-in-mold sealing treatment, resulting in a significant increase in both R-corner thickness and the number of bubbles at the R-corner compared to Example 1. Comparative Example 7 further reduced the sealing current compared to Example 1, and significantly increased the number of bubbles in the R-corner compared to Example 1.

[0121] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0122] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0123] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0124] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a semiconductor-grade large-size quartz crucible, characterized in that, The preparation method includes an arc melting device used in the vacuum arc melting process comprising at least 6 electrodes; During the vacuum arc melting process, the current for the sealing treatment is 2000~2500 A, the sealing treatment time is 8~12 s, the distance from the bottom of the electrode to the mold port is 10~30 mm, and the thickness of the sealing layer obtained by the sealing treatment is 0.5~1.0 mm.

2. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 1, characterized in that, The electric arc melting device includes six electrodes arranged in a ring at equal intervals.

3. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 2, characterized in that, The spacing between the electrodes is 45~55 mm.

4. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 1, characterized in that, Quartz sand molds are formed before the vacuum arc melting.

5. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 4, characterized in that, The quartz sand mold forming process includes: pouring quartz sand into the mold, and sequentially forming the outer surface, the straight wall, and the bottom and R-angle.

6. A semiconductor-grade large-size quartz crucible, characterized in that, The semiconductor-grade large-size quartz crucible is prepared by the method for preparing a semiconductor-grade large-size quartz crucible according to any one of claims 1-5.

7. The semiconductor-grade large-size quartz crucible according to claim 6, characterized in that, The semiconductor-grade large-size quartz crucible has a size of not less than 32 inches.

Images