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

Abstract

The invention provides a preparation method of a semiconductor-grade large-size quartz crucible. According to the preparation method, an electric arc melting device used in a vacuum electric arc melting process comprises at least six electrodes; 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 port of the mold is 10-30 mm. According to the preparation method, the thickness of the R angle is reduced, and the heat transfer uniformity is improved, so that the whole rod rate and quality of the prepared monocrystalline silicon are improved; meanwhile, the residual number of microbubbles after vacuum arc melting is reduced, and the influence of microbubble breakage on monocrystalline silicon growth in the crystal pulling process is avoided.

Description

Technical Field

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

[0002] Single crystal silicon, the starting material for most semiconductor electronic component manufacturing, is typically produced using the so-called Czochralski ("CZ") method. Using the CZ method, crystal growth is most commonly performed in a crystal pulling furnace, where multicrystalline silicon ("polysilicon") is loaded into 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 a single crystal ingot is extracted by a crystal puller.

[0003] During crystal growth, the prolonged exposure of the crucible's inner sidewalls to high-temperature molten silicon causes the silicon melt to react with the quartz crucible, leading to dissolution of the inner surface of the crucible's sidewalls. This exposes bubbles in the crucible's sidewalls to the molten silicon, which continues to dissolve into the crucible's walls and, consequently, the bubbles themselves. At some point, the bubble walls collapse and may collapse, with gas released from the bubbles and quartz particles 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 grown. Furthermore, the presence of bubble cavities or voids along the crucible's inner surface can serve as sites for gas nucleation. When gas nucleates and grows into small bubbles, these bubbles can enter the growing silicon, resulting in crystals with voids that do not meet specifications. Reducing or eliminating bubbles in the crucible minimizes voids in the crystal, achieving acceptable crystal properties within specifications. Thermal field uniformity: The R-angle thickness has a significant impact on the heat transfer properties of the crucible.

[0004] The patented melting electrode device for large-diameter quartz crucibles (CN104926086A) proposes a melting device with six graphite electrodes. This device utilizes a linked design between a copper rod and a clamping jaw (opening and closing controlled by a screw nut) to achieve synchronous adjustment of the electrodes. Inserted into a graphite mold, these six graphite electrodes provide a large heat source, increasing the melting temperature and optimizing the shape and vitrification quality of large-diameter quartz crucibles. This device is suitable for manufacturing crucibles with diameters larger than 32 inches, addressing the limited heating range of traditional three-electrode systems.

[0005] A method for manufacturing quartz glass crucibles (JP2008-244521) describes a conventional three-phase, three-electrode structure that suffers from arc instability and uneven heating in large crucibles (e.g., larger than 32 inches). This patent explores a six-phase, six-electrode structure, but finds that the central region tends to overheat, resulting in poor uniformity. Arc discharge stability is optimized by adjusting the horizontal / vertical distance ratio (e.g., W / R, H / R) between the electrode tips and the surface of the quartz powder molded body. A ring-shaped electrode configuration is proposed to avoid central arc concentration, thereby improving heating uniformity in large-diameter crucibles.

[0006] In the existing technical methods, when the quartz crucible is prepared by the quartz crucible vacuum arc suction casting method, since the inner surface of the quartz crucible is in contact with the air, the bubbles cannot be completely removed by vacuum, so there are still certain microbubbles in the surface layer. These microbubbles will expand and rupture due to heat during the crystal pulling process. When ruptured, tiny quartz particles fall into the silicon liquid, causing the purity of the single crystal silicon to be reduced to a certain extent. The rupture of microbubbles on the inner surface of the quartz crucible also greatly causes the liquid level to fluctuate more during crystal pulling, making crystal pulling difficult and easy to break. In addition, the ruptured area is more likely to induce crystallization, and the shedding of the crystallized part will also affect the purity of the single crystal silicon. In order to solve the surface bubbles, most domestic manufacturers increase the current ablation, resulting in increased bottom movement and a very thick R angle. During use by customers, this leads to uneven thermal field distribution, which in turn affects the growth rate and morphology of the crystal. Summary of the Invention

[0007] To address the technical problems existing in the prior art, the present invention provides a semiconductor-grade large-size quartz crucible and a method for its preparation. This method reduces the thickness of the R-angle, improves heat transfer uniformity, and thereby enhances the yield and quality of single crystal silicon ingots. It also reduces the number of residual microbubbles after vacuum arc melting, preventing the impact of microbubble bursting on single crystal silicon growth during crystal pulling.

[0008] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0009] One object of the present invention is to provide a method for preparing a semiconductor-grade large-sized quartz crucible, the method comprising: using an arc melting device in a vacuum arc melting process comprising at least 6 electrodes;

[0010] During the vacuum arc melting process, the current of the cover 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 arc melting device includes 6 electrodes, which are arranged in a ring with equal intervals.

[0012] As a preferred technical solution of the present invention, the spacing between the electrodes is 45-55 mm.

[0013] As a preferred technical solution of the present invention, the cover processing time is 8 to 12 seconds.

[0014] As a preferred technical solution of the present invention, the thickness of the cover layer obtained by the cover processing 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, 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] A second object of the present invention is to provide a semiconductor-grade large-sized quartz crucible, which is prepared by the preparation method of the semiconductor-grade large-sized quartz crucible provided in the first object.

[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 a preparation method thereof. The preparation method adopts an arc melting device with 6 electrodes and combines a low-position, low-current, rapid sealing method to effectively reduce the R-angle thickness of the quartz crucible, improve the uniformity of heat transfer, and improve the whole rod rate and quality of the prepared single crystal silicon.

[0021] (2) The present invention provides a semiconductor-grade large-size quartz crucible and a preparation method thereof. The preparation method reduces the amount of residual microbubbles after vacuum arc melting through a low-position, low-current, rapid sealing method, thereby avoiding the influence of microbubble rupture on the growth of single crystal silicon during the crystal pulling process.

[0022] (3) The present invention provides a semiconductor-grade large-size quartz crucible and a preparation method thereof. The low-position, low-current, rapid sealing method used in the preparation method helps to shorten the production cycle and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 A comparison chart of three-electrode and six-electrode arc melting devices.

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

[0026] The present invention is further described in detail below. However, the following examples 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 shall be subject to the claims. DETAILED DESCRIPTION

[0027] The technical solution of this application is further explained below through specific implementation methods.

[0028] A specific embodiment of the present invention provides a method for preparing a semiconductor-grade large-size quartz crucible, the method comprising: an arc melting apparatus used in a vacuum arc melting process comprising at least six electrodes;

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

[0030] Among them, the current of the cover treatment can be 2000A, 2100A, 2200A, 2300A, 2400A or 2500A, 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, but is not limited to the listed values. Other values ​​not listed within the above numerical ranges are also applicable.

[0031] In a specific embodiment of the present invention, the arc melting device includes 6 electrodes, which are arranged in a circular shape with equal intervals.

[0032] In the present invention, for semiconductor-grade large-sized quartz crucibles (over 32 inches), during the production process, due to the need to increase the current for ablation, a greater impact is caused on the bottom during the melting process, resulting in greater movement, making the thickness at the R corner very thick, and the large impact easily forms bubbles at the R corner. For three electrodes, increasing the opening and closing will increase the radiation area, but increasing the opening and closing will lead to poor arc stability and large fluctuations. Six electrodes can avoid the above-mentioned risks. However, the effect of thinning the R corner and reducing bubbles in the quartz crucible by only using a six-electrode system is still limited. Therefore, the present invention simultaneously achieves the best R corner thinning and bubble reduction effect by low-level small current rapid sealing. The reason is that:

[0033] 1. The heat field is more evenly distributed

[0034] Low-current, rapid sealing means lower heating power and the electrode position is closer to the bottom of the crucible. This configuration results in: 1) The R-corner area receives relatively less heat: Heat is concentrated in the center of the crucible bottom, while the edges and corners (R-corners) melt more slowly, reducing the material deposition rate and thus reducing localized excessive thickening. 2) The fluidity of the fused quartz is weakened: Under low current, the viscosity of fused quartz is higher, making it less likely to accumulate excessively at the R-corner due to gravity or centrifugal force, thus avoiding uneven thickness. 3) The "edge effect" is suppressed: High or large currents tend to cause heat to concentrate at the top or edge of the crucible, while low currents concentrate the heat field more at the bottom, reducing excessive material deposition at the R-corner due to thermal convection or radiation.

[0035] 2. Reasons for reducing microbubbles

[0036] 1) Slow gas release: Gases (such as H2O, CO2, etc.) in quartz sand are released at high temperatures. Small currents make the heating rate more gradual, and the gases have enough time to escape from the melt instead of being trapped and forming microbubbles. 2) Reduced risk of local overheating: Large currents may cause local instantaneous high temperatures, causing the quartz to melt quickly and encapsulate the gas; small currents avoid violent reactions and reduce bubble generation. 3) Improved melt uniformity: Low-position heating allows the melting process to proceed gradually from bottom to top, and bubbles are more easily discharged upward through the melt with lower viscosity, rather than being retained at the R corners and causing bubble belt problems. 4) Fast sealing: This also solves the problem of slow sealing speeds in some areas of large-sized crucibles when the sealing speed is slow, resulting in uneven sealing thickness, making it difficult to eliminate microbubbles in the later melting process, resulting in serious microbubble exceeding the standard.

[0037] 3. Balance of process optimization

[0038] Although fast sealing at low position and low current can improve R corner thickness and microbubbles, it should be noted that excessively reducing the current or position may lead to insufficient melting, making it impossible to effectively seal the crucible, and the vacuum cannot reach the limit value in a short time. There will be large differences in the thickness of the seal, resulting in extremely serious microbubbles. The optimal parameters need to be found through experiments.

[0039] In a 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 values ​​not listed within this numerical range are also applicable.

[0040] In a specific embodiment of the present invention, the cover processing 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 values ​​not listed within the numerical range are also applicable.

[0041] In a specific embodiment of the present invention, the thickness of the cover layer obtained by the cover processing 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 values ​​not listed within the numerical range are also applicable, and more preferably 0.5~1 mm.

[0042] In a specific embodiment of the present invention, the vacuum arc melting process includes exhaust treatment, transparent layer melting and bubble layer melting in addition to cover treatment, and the specific order is exhaust treatment, cover treatment, transparent layer melting and bubble layer melting.

[0043] In a specific embodiment of the present invention, the specific parameters of the exhaust 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 embodiment of the present invention, quartz sand mold forming is performed before vacuum arc melting.

[0045] In one 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-angle forming.

[0046] In a specific embodiment of the present invention, the process parameters of the mold forming, that is, the specific parameters of each forming stage, are conventional parameters in the field of quartz crucibles. They can be adjusted according to the production requirements of the quartz crucible and the type of material, and are not further limited here.

[0047] In a 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 embodiment of the present invention, the cooling method may be natural cooling, air cooling, water cooling, etc. The cooling rate may be adjusted according to the production requirements and the type of material of the quartz crucible, and is not further limited here.

[0049] In one 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 attachments.

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

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

[0052] Step 1: Weighing the materials: weigh the raw materials required for preparation according to the formula, select high-purity natural quartz sand, and use a grinder to grind it, add the required weight of quartz sand into the mold, and form the crucible blank through the mold;

[0053] Step 2: Mold forming: add the required weight of quartz sand into 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 into the mold in sequence, and form the functional layer through the mold;

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

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

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

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

[0058] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, 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-sized quartz crucible, the method comprising:

[0061] The arc melting device used in the vacuum arc melting process includes 6 electrodes, which are arranged in a ring with equal intervals. The electrode spacing is 50 mm, the current of the cover treatment is 2250 A, the distance from the bottom of the electrode to the mold port is 20 mm, the cover treatment time is 8 s, and the thickness of the cover layer obtained by the cover treatment is 0.5 mm.

[0062] Example 2

[0063] Except that the spacing between the electrodes is 45 mm, the other conditions in this embodiment are the same as those in embodiment 1.

[0064] Example 3

[0065] Except that the spacing between the electrodes is 55 mm, the other conditions in this embodiment are the same as those in Example 1.

[0066] Example 4

[0067] In this embodiment, except that the current for the cover treatment is 2000 A, the other conditions are the same as those in Example 1.

[0068] Example 5

[0069] In this embodiment, except that the current for the cover treatment is 2500 A, the other conditions are the same as those in embodiment 1.

[0070] Example 6

[0071] In this embodiment, except that the distance from the bottom of the electrode to the mold port is 10 mm, all other conditions are the same as those in Example 1.

[0072] Example 7

[0073] In this embodiment, except that the distance from the bottom of the electrode to the mold port is 30 mm, all other conditions are the same as those in Example 1.

[0074] Example 8

[0075] In this embodiment, except that the cover treatment time is 10 s and the cover layer thickness is 1 mm, other conditions are the same as those in Example 1.

[0076] Example 9

[0077] In this embodiment, except that the cover treatment time is 12 s and the cover layer thickness is 2 mm, other conditions are the same as those in Example 1.

[0078] Comparative Example 1

[0079] In this comparative example, except that the number of arcs in the arc melting device is 3, other conditions are the same as those in Example 1.

[0080] Comparative Example 2

[0081] In this comparative example, except that the distance from the bottom of the electrode to the mold port is 80 mm, all other conditions are the same as those in Example 1.

[0082] Comparative Example 3

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

[0084] Comparative Example 4

[0085] In this comparative example, except that the current for the cover treatment is 4000 A, all other conditions are the same as those in Example 1.

[0086] Comparative Example 5

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

[0088] Comparative Example 6

[0089] In this comparative example, except that the current for the cover treatment is 4000 A and the distance from the bottom of the electrode to the mold port is -20 mm, the other conditions are the same as those in Example 1.

[0090] Comparative Example 7

[0091] In this comparative example, except that the current for the cover treatment was 1000 A, all other conditions were the same as those in Example 1.

[0092] In Examples 1-9 and Comparative Examples 1-7, the method for preparing the quartz crucible blank includes mold forming, vacuum arc melting forming, cooling, sandblasting, and demolding performed in sequence.

[0093] The steps of mold forming include:

[0094] Step 1: Rotate the melt rotating mold 45-56 degrees, rotate at 65-70rpm, pour the outer surface natural quartz sand into the mold, and then use a forming rod to form straight-walled natural high-purity quartz sand;

[0095] Step 2: Rotate the melt rotating mold to 0°, rotate at 65-70 rpm, and use a forming rod to scrape the natural high-purity quartz sand on the straight wall to make it fall to the bottom until the entire outer surface of the crucible is formed;

[0096] Step 3: Use a molding machine to shape some high-purity natural quartz sand into straight walls until the straight wall is formed;

[0097] Step 4: Finally, use the remaining high-purity natural quartz sand to artificially shape the bottom and R corner parts until the final shaping is completed.

[0098] Vacuum arc melting molding includes exhaust treatment, cover treatment, transparent layer melting and bubble layer melting in sequence. 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 vacuumed. The density of the single gas is less than that of air.

[0100] During the cover processing, the graphite electrode starts arcing, keeps the mixed gas flowing and vacuum is drawn;

[0101] During the melting of the transparent layer, keep the mixed gas flowing and vacuuming;

[0102] During the melting of the bubble layer, stop introducing the mixed gas and evacuating the air;

[0103] After the bubble layer is melted, the graphite arc is turned off and the quartz crucible is quickly cooled; after cooling is completed, it is taken out of the furnace and the melting is completed.

[0104] The conditions of each step of vacuum arc melting and cooling are shown in Table 1.

[0105] Table 1

[0106] After cooling, use a spray gun to spray quartz sand on the surface of the crucible blank to remove surface attachments, and knock the outer surface of the mold to separate the crucible blank from the mold.

[0107] The base quartz sand is high-purity natural quartz sand with a purity of more than 99.99% of silicon dioxide, the bubble layer uses natural high-purity quartz sand NC4A, and the transparent layer uses synthetic quartz sand.

[0108] The number of microbubbles on the straight wall, R corner, and bottom of the quartz crucibles prepared in Examples 1-9 and Comparative Examples 1-7 was counted, and the thickness of the R corner was tested. The results are shown in Table 2.

[0109] The method for testing the number of bubbles uses a combination of optical microscopy and image processing. The specific steps are as follows:

[0110] 1. Sample preparation: slice or polish the surface to ensure that the bubbles are exposed to the observation surface;

[0111] 2. Microscopic imaging: Use an optical microscope to capture high-resolution images (calibration of the scale is required);

[0112] 3. Image processing:

[0113] (1) Perform threshold segmentation using software (such as ImageJ, MATLAB) to extract bubble outlines;

[0114] (2) Automatically count the number of bubbles;

[0115] 4. Result output: number of bubbles per unit area ( / mm²) and distribution histogram.

[0116] The R angle thickness is tested using an ultrasonic thickness gauge.

[0117] Table 2

[0118] The test results in Table 2 show that the R-angle thickness of the quartz crucibles prepared by the preparation methods of semiconductor-grade large-size quartz crucibles provided in Examples 1-9 is significantly thinner, and the number of bubbles at the R is small. Comparative Example 1 adopts a 3-electrode system. Compared with Example 1, the R-angle is significantly thickened and the number of bubbles at the R-angle is greatly increased. In Comparative Examples 2 and 3, the electrodes are heated by high-position and extended into the mold, respectively. Although the R thickness in Comparative Example 2 is further thinned compared with Example 1, the number of R bubbles increases significantly. Compared with Example 1, the R-angle thickness and the number of R bubbles in Comparative Example 3 are both increased. Comparative Example 4 adopts a high-current envelope treatment. Compared with Example 1, the R-angle thickness and the number of R bubbles are both increased. Comparative Example 5 adopts a high-position high-current envelope treatment. Although the R-angle thickness is thinner than that in Example 1, the number of R-angle bubbles increases significantly. Comparative Example 6 adopts an envelope treatment with a high current extending into the mold. Compared with Example 1, the R-angle thickness and the number of R bubbles are both significantly increased. Compared with Example 1, the cover processing current of Comparative Example 7 is further reduced, and the number of R-corner bubbles is greatly increased compared with Example 1.

[0119] The applicant declares that the present invention is intended to illustrate the detailed structural features of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed structural features. This does not mean that the present invention must rely on the above-described detailed structural features in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

[0120] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within 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 scope of protection of the present invention.

[0121] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0122] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents 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 using an arc melting device in a vacuum arc melting process including at least 6 electrodes; During the vacuum arc melting process, the current of the cover treatment is 2000-2500 A, and the distance from the bottom of the electrode to the mold port is 10-30 mm.

2. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 1, characterized in that: The arc melting device includes 6 electrodes, which are arranged in a circular shape with equal intervals.

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

4. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 1, wherein: The time for the cover processing is 8 to 12 seconds.

5. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 1, characterized in that: The thickness of the cover layer obtained by the cover treatment is 0.5-1.0 mm.

6. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 1, characterized in that: Quartz sand mold forming is performed before the vacuum arc melting.

7. The method for preparing a semiconductor-grade large-size quartz crucible according to claim 6, characterized in that: 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.

8. A semiconductor-grade large-size quartz crucible, characterized in that: The semiconductor-grade large-sized quartz crucible is prepared by the method for preparing a semiconductor-grade large-sized quartz crucible according to any one of claims 1 to 7.

9. The semiconductor-grade large-size quartz crucible according to claim 8, characterized in that: The size of the semiconductor-grade large-size quartz crucible is not less than 32 inches.

Images