Quartz crucible for producing single crystal silicon and method for manufacturing the same

Abstract

The application discloses a quartz crucible for single crystal silicon production and a preparation method thereof, relates to the technical field of crucibles, and contains a glass phase and a cristobalite phase, and the cristobalite phase is uniformly dispersed in the glass phase; the application adopts a mixture of amorphous synthetic quartz sand and cristobalite as a crucible preparation raw material, uniformly nucleates to form consistent phases inside and outside, significantly improves the stability of the crucible, effectively solves the problems of deformation such as bulging and wrinkling of the quartz crucible prepared from natural quartz sand in a high-temperature environment, and prolongs the service life of the crucible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crucible, in particular to a quartz crucible for single crystal silicon production and a preparation method thereof. BACKGROUND

[0002] In the production of single crystal silicon, quartz crucibles made of high-purity quartz sand play an irreplaceable role as a key device (as commonly used in the industry, high-purity quartz sand refers to natural quartz sand with a specific particle size (generally 80 μm or more), a specific crystal form (α-quartz), and a purity greater than 4N8). It not only serves to contain polycrystalline silicon raw materials, but also can be heated to melt under high temperature conditions to form a silicon solution, providing the possibility for subsequent processes such as crystal pulling, shoulder setting, constant diameter, and tailing.

[0003] Currently, the commonly used quartz crucible is designed with two layers (such as Figure 21 ), in which the inner layer (transparent layer) is transparent quartz glass, and the outer layer is a bubble composite layer. This design aims to improve the success rate of single crystal growth and the quality of the crystal bar. The presence of the transparent layer effectively reduces the bubble density in the contact area between the crucible and the molten silicon, while the bubble composite layer has excellent thermal uniformity and heat preservation effect.

[0004] However, the existing quartz crucible still faces some challenges. First, high-purity quartz sand is derived from nature, and inevitably contains impurities such as alkali metals, alkaline earth metals, and gas-liquid inclusions. In a high-temperature environment, impurities can cause the surface of the glassy silica in the inner layer (transparent layer) of the crucible to precipitate cristobalite particles during the melting of polycrystalline silicon and the growth of single crystal silicon rods. The precipitated cristobalite is prone to cracking and peeling, leading to behaviors such as bulging, devitrification, and deformation of the quartz crucible, affecting its service life. Second, the inner wall glassy silica of the quartz crucible will react with the silicon liquid to form silicon monoxide during long-term use, gradually eroding the silicon monoxide into the silicon liquid, resulting in a decrease in the quality of the silicon rod, which can generally only be used for 100-200 hours. Therefore, it is an industry consensus to inhibit the crystallization of quartz crucibles for crystal silicon and to improve the service life of the crucible.

[0005] To solve the above problems, researchers in the field have been exploring new technical solutions. For example, patent CN202411297908.3 discloses a preparation method of a quartz crucible and a quartz crucible. The preparation method of the quartz crucible comprises the following steps: preparing a crucible green body, the crucible green body comprising a first quartz sand layer and a second quartz sand layer arranged in sequence from the outside to the inside; wherein the second quartz sand layer comprises quartz sand and barium carbonate, the purity of the quartz sand in the first quartz sand layer is less than that of the quartz sand in the second quartz sand layer; firing the crucible green body to obtain a crucible body; spraying protective coating to the inner surface of the crucible body by using inert gas, then introducing carbon dioxide gas and performing gradient temperature heat treatment to obtain the quartz crucible, the quartz crucible comprising a crucible body and a protective layer on the inner surface of the crucible body, the protective layer comprising barium carbonate, nano silicon dioxide and barium borate. Although the method improves the adhesion of the coating, it still has some limitations, such as insufficient adhesion of the coating, easy peeling, introduction of impurities, and influence on the quality of crystal pulling, etc. Moreover, the cristobalite crystalline layer induced by barium will still peel off.

[0006] At the same time, there is another problem in the industry. Although high-purity quartz sand (glass state) prepared by synthetic method has high purity and can meet the requirements, due to the low content of impurity elements, the prepared crucible is easy to soften at high temperature, and the temperature resistance is not as good as natural high-purity quartz sand. Moreover, since the synthetic high-purity quartz sand does not have a fixed melting point, it starts to soften at a relatively low temperature. Therefore, when the conventional arc method (2000℃) is used to prepare the crucible, the air is difficult to be removed, resulting in a small amount of air bubbles in the transparent layer, which is easy to break and enter the silicon liquid during use.

[0007] Therefore, how to use the high-purity quartz sand obtained by synthetic method to prepare a quartz crucible with good stability and long service life is of great significance to the development of the industry. SUMMARY

[0008] In view of the problems of quartz crucible in the prior art, such as easy crystallization deformation at high temperature, short service life, easy erosion of inner wall and containing impurities, the present application provides a quartz crucible for single crystal silicon production and a preparation method thereof.

[0009] The technical problem to be solved by the present application is solved by the following technical solution:

[0010] One of the objects of the present application is to provide a quartz crucible containing glass phase and cristobalite phase, and the cristobalite phase is uniformly dispersed in the glass phase.

[0011] Further, the quartz crucible is a single-layer structure.

[0012] Further, the cristobalite phase has a grain size of 5-15 μm and a content of more than 5%.

[0013] Further, the quartz crucible has a density of 2.2-2.6 g / cm 3 .

[0014] Further, the quartz crucible has a purity (SiO2 content) of no less than 4N8.

[0015] Further, the quartz crucible has a thickness of 12-16 cm and a diameter of 100-1000 mm.

[0016] Further, the quartz crucible is completely converted into the cristobalite phase by heat treatment at a temperature of 1200-1600 ℃. In the production of single crystal silicon, the heat generated in the process of melting silicon can be used to heat treat the quartz crucible, so that it is completely converted into the cristobalite phase, thereby saving the energy consumption and time input of separate heat treatment.

[0017] The second object of the present application is to provide a preparation method of the quartz crucible, comprising the following steps:

[0018] S1, uniformly mixing glassy synthetic quartz sand and cristobalite and then performing green body forming to obtain a crucible green body;

[0019] S2, sintering the crucible green body to obtain a quartz crucible.

[0020] Further, the cristobalite accounts for ≤5% of the total mass of the glassy synthetic quartz sand and cristobalite.

[0021] Further, the synthetic quartz sand has a D50 particle size of ≤100 μm and a purity of no less than 5N.

[0022] Further, the cristobalite has a D50 particle size of ≤10 μm and a purity of no less than 5N.

[0023] Further, the green body forming method includes but is not limited to one of centrifugal forming, slip casting, and press forming. When the slip casting method is used, a binder and water need to be added to prepare a slurry. The binder is one or more of polyvinyl alcohol (PVA), polyvinyl butyral (PVB), and other water-based binders; and the amount of the binder is 2-10% of the mass of the slurry.

[0024] Further, the sintering temperature is lower than the melting point of cristobalite. Preferably, the sintering temperature is 1200-1600 ℃ and the sintering time is 0.5-10 h.

[0025] Further, the sintering atmosphere is vacuum or a non-reactive atmosphere (e.g. argon).

[0026] A third object of the present application is to provide the use of the quartz crucible in the production of single crystal silicon.

[0027] The present application has the following advantages:

[0028] 1. The present application uses a mixture of amorphous synthetic quartz sand and cristobalite as the crucible preparation raw material, which forms a consistent phase inside and outside through uniform nucleation, significantly improves the stability of the crucible, effectively solves the problem of deformation such as bulging and wrinkling of the quartz crucible prepared from natural quartz sand in a high temperature environment, and prolongs the service life of the crucible.

[0029] 2. The crucible has excellent corrosion resistance to silicon liquid, effectively prevents the inner wall silicon dioxide from being eroded and peeled off, reduces the formation probability of dislocations in the single crystal silicon rod, maintains stable performance during use, can be used for 500 h, meets the needs of industrial production, and overcomes the shortcoming of short service life of the crucible in the prior art.

[0030] 3. The crucible has a single-layer structure, simple design, controllable preparation process, easy to mass production, good economic benefits, and ensures the consistency and stability of the product. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 XRD pattern of the crucible prepared in Example 1;

[0032] Figure 2 SEM pattern of the crucible prepared in Example 1;

[0033] Figure 3 XRD pattern of the crucible prepared in Example 2;

[0034] Figure 4 SEM pattern of the crucible prepared in Example 2;

[0035] Figure 5 XRD pattern of the crucible prepared in Example 3;

[0036] Figure 6 SEM pattern of the crucible prepared in Example 3;

[0037] Figure 7 XRD pattern of the crucible prepared in Example 4;

[0038] Figure 8 SEM pattern of the crucible prepared in Example 4;

[0039] Figure 9 XRD pattern of the crucible prepared in Comparative Example 1;

[0040] Figure 10 SEM image of the crucible prepared for Comparative Example 1;

[0041] Figure 11 XRD image of the crucible prepared for Comparative Example 2;

[0042] Figure 12 SEM image of the crucible prepared for Comparative Example 2;

[0043] Figure 13 XRD image of the crucible prepared for Comparative Example 3;

[0044] Figure 14 SEM image of the crucible prepared for Comparative Example 3;

[0045] Figure 15 XRD image of the crucible prepared for Comparative Example 4;

[0046] Figure 16 SEM image of the crucible prepared for Comparative Example 4;

[0047] Figure 17 XRD image of the crucible prepared for Comparative Example 8;

[0048] Figure 18 SEM image of the crucible prepared for Comparative Example 8;

[0049] Figure 19 XRD image of the crucible prepared for Comparative Example 12;

[0050] Figure 20 SEM image of the crucible prepared for Comparative Example 12;

[0051] Figure 21 Cross-sectional image (camera shot) of a conventional quartz crucible in the art;

[0052] Figure 22 Appearance image of the crucible prepared for Example 4 after heat treatment;

[0053] Figure 23 Appearance image of the crucible prepared for Comparative Example 4 after heat treatment. DETAILED DESCRIPTION

[0054] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below in combination with specific embodiments and drawings.

[0055] The following describes the sources of raw materials in the examples and comparative examples:

[0056] Glassy synthetic quartz sand was purchased from Mitsubishi Chemical, Japan, model PS400, and was ground into corresponding particle sizes as needed.

[0057] Cristobalite, obtained by heat treating the glassy synthetic quartz sand described above at 1200℃ for 50 h, and then crushing to the corresponding particle size as needed.

[0058] Binder, PVA, commercially available from Wuhan Meiqilin New Material Co., Ltd., model MQ-35.

[0059] Example 1

[0060] S1, the glassy synthetic quartz sand (purity of 5N, D50=100μm) and cristobalite (purity of 5N, D50=4μm) were mixed uniformly and then added into a tiltable forming mold, and centrifugal forming was performed to obtain a crucible green body. The mass ratio of cristobalite was 5%.

[0061] S2, the crucible green body was sintered at a temperature of 1550℃ and a vacuum degree of -0.1 MPa for 0.5 h, and then cooled to room temperature to obtain a quartz crucible.

[0062] The SiO2 purity of the quartz crucible prepared in this example was 4N8, the wall thickness was 14 mm, and the diameter was 100 mm.

[0063] Example 2

[0064] S1, the glassy synthetic quartz sand (purity of 5N, D50=80μm) and cristobalite (purity of 5N, D50=3μm) were mixed uniformly and then added into a tiltable forming mold, and centrifugal forming was performed to obtain a crucible green body. The mass ratio of cristobalite was 4%.

[0065] S2, the crucible green body was sintered at a temperature of 1400℃ and a vacuum degree of -0.1 MPa for 3 h, and then cooled to room temperature to obtain a quartz crucible.

[0066] The SiO2 purity of the quartz crucible prepared in this example was 4N8, the wall thickness was 15 mm, and the diameter was 500 mm.

[0067] Example 3

[0068] S1, the glassy synthetic quartz sand (purity of 5N, D50=50μm) and cristobalite (purity of 5N, D50=1.5μm) were mixed uniformly and then added into a tiltable forming mold, and centrifugal forming was performed to obtain a crucible green body. The mass ratio of cristobalite was 0.1%.

[0069] S2, the crucible green body was sintered at a temperature of 1200℃ and a vacuum degree of -0.1 MPa for 8 h, and then cooled to room temperature to obtain a quartz crucible.

[0070] The SiO2 purity of the quartz crucible prepared in the embodiment is 4N8, the wall thickness is 16 mm, and the diameter is 1000 mm.

[0071] Embodiment 4

[0072] S1, after the glassy synthetic quartz sand (purity 5N, D50 = 80 μm) and cristobalite (purity 5N, D50 = 3 μm) are uniformly mixed, the mixture is added into a mold that can be arbitrarily tilted and molded, and a crucible green body is obtained by centrifugal molding. The mass ratio of the cristobalite is 4%.

[0073] S2, the crucible green body is sintered at a temperature of 1400℃ in an argon environment for 3 h, and then cooled to room temperature to obtain a quartz crucible.

[0074] The SiO2 purity of the quartz crucible prepared in the embodiment is 4N8, the wall thickness is 15 mm, and the diameter is 150 mm.

[0075] Embodiment 5

[0076] S1, the quartz sand, deionized water and binder MQ-35 are uniformly mixed at a mass ratio of 16:3:2 to obtain a slurry; wherein the quartz sand is composed of glassy synthetic quartz sand (purity 5N, D50 = 80 μm) and cristobalite (purity 5N, D50 = 2 μm), and the mass ratio of the cristobalite is 2%; the slurry is injected into a mold to form a crucible green body.

[0077] S2, the crucible green body is sintered at a temperature of 1500℃ in an environment with a vacuum degree of -0.1 MPa for 1.5 h, and then cooled to room temperature to obtain a quartz crucible.

[0078] The SiO2 purity of the quartz crucible prepared in the embodiment is 4N8, the wall thickness is 16 mm, and the diameter is 1000 mm.

[0079] Embodiment 6

[0080] S1, the quartz sand, deionized water and binder MQ-35 are uniformly mixed at a mass ratio of 16:3:1 to obtain a slurry; wherein the quartz sand is composed of glassy synthetic quartz sand (purity 5N, D50 = 80 μm) and cristobalite (purity 5N, D50 = 2 μm), and the mass ratio of the cristobalite is 5%; the slurry is injected into a mold to form a crucible green body.

[0081] S2, the crucible green body is sintered at a temperature of 1500℃ in an environment with a vacuum degree of -0.1 MPa for 1.5 h, and then cooled to room temperature to obtain a quartz crucible.

[0082] The SiO2 purity of the quartz crucible prepared in the embodiment is 4N8, the wall thickness is 16 mm, and the diameter is 1000 mm.

[0083] Example 7

[0084] S1, quartz sand, deionized water and binder MQ-35 were mixed uniformly at a mass ratio of 16:3:0.5 to obtain a slurry; wherein the quartz sand was composed of glassy synthetic quartz sand (purity of 5N, D50=80μm) and cristobalite (purity of 5N, D50=2μm), and the mass ratio of cristobalite was 0.1%; the slurry was injected into a mold to form a green body of a crucible.

[0085] S2, the green body of the crucible was sintered at a temperature of 1500℃ and a vacuum degree of-0.1MPa for 1.5h, and then cooled to room temperature to obtain a quartz crucible.

[0086] The SiO2purity of the quartz crucible prepared in this example was 4N8, the wall thickness was 16mm, and the diameter was 1000mm.

[0087] Example 8

[0088] S1, quartz sand, deionized water and binder MQ-35 were mixed uniformly at a mass ratio of 16:3:0.5 to obtain a slurry; wherein the quartz sand was composed of glassy synthetic quartz sand (purity of 5N, D50=80μm) and cristobalite (purity of 5N, D50=2μm), and the mass ratio of cristobalite was 0.1%; the slurry was injected into a mold to form a green body of a crucible.

[0089] S2, the green body of the crucible was sintered at a temperature of 1500℃ and a vacuum degree of-0.1MPa for 1.5h, and then cooled to room temperature to obtain a quartz crucible.

[0090] The SiO2purity of the quartz crucible prepared in this example was 4N8, the wall thickness was 16mm, and the diameter was 1000mm.

[0091] Example 9

[0092] S1, glassy synthetic quartz sand (purity of 5N, D50=100μm) and cristobalite (purity of 5N, D50=4μm) were mixed uniformly and then added into a mold, and a pressure of 100MPa was applied for compression molding to obtain a green body of a crucible. The mass ratio of cristobalite was 5%.

[0093] S2, the green body of the crucible was sintered at a temperature of 1500℃ and a vacuum degree of-0.1MPa for 1.5h, and then cooled to room temperature to obtain a quartz crucible.

[0094] The SiO2purity of the quartz crucible prepared in this example was 4N8, the wall thickness was 16mm, and the diameter was 1000mm.

[0095] Example 10

[0096] S1, after the glassy synthetic quartz sand (purity 5N, D50 = 80 μm) and cristobalite (purity 5N, D50 = 3 μm) are mixed uniformly, they are added into a mold, a pressure of 300 MPa is applied for compression molding to obtain a crucible green body. The mass ratio of cristobalite is 4%.

[0097] S2, the crucible green body is sintered at a temperature of 1400℃ and a vacuum degree of -0.1 MPa for 3 h, and then is cooled to room temperature to obtain a quartz crucible.

[0098] The SiO2 purity of the quartz crucible prepared in this example is 4N8, the wall thickness is 12 mm, and the diameter is 200 mm.

[0099] Example 11

[0100] S1, after the glassy synthetic quartz sand (purity 5N, D50 = 80 μm) and cristobalite (purity 5N, D50 = 3 μm) are mixed uniformly, they are added into a mold, a pressure of 300 MPa is applied for compression molding to obtain a crucible green body. The mass ratio of cristobalite is 4%.

[0101] S2, the crucible green body is sintered at a temperature of 1400℃ and a vacuum degree of -0.1 MPa for 3 h, and then is cooled to room temperature to obtain a quartz crucible.

[0102] The SiO2 purity of the quartz crucible prepared in this example is 4N8, the wall thickness is 12 mm, and the diameter is 200 mm.

[0103] Comparative Example 1

[0104] According to the method of Example 4, except that the particle size D50 of the synthetic quartz sand is adjusted to 150 μm.

[0105] Comparative Example 2

[0106] According to the method of Example 4, except that the particle size D50 of the cristobalite is adjusted to 20 μm.

[0107] Comparative Example 3

[0108] According to the method of Example 4, except that the synthetic quartz sand is replaced by natural quartz sand.

[0109] Comparative Example 4

[0110] According to the method of Example 4, except that the sintering temperature is adjusted to 1750℃.

[0111] Comparative Example 5

[0112] The method of Example 6 was followed, except that the mass ratio of quartz sand, deionized water, and binder was adjusted to 16:5:7.

[0113] Comparative Example 6

[0114] The method of Example 6 was followed, except that the particle size D50 of the synthetic quartz sand was adjusted to 150 μm.

[0115] Comparative Example 7

[0116] The method of Example 6 was followed, except that the synthetic quartz sand was replaced with natural quartz sand.

[0117] Comparative Example 8

[0118] The method of Example 6 was followed, except that the sintering temperature was adjusted to 1750°C.

[0119] Comparative Example 9

[0120] The method of Example 10 was followed, except that the particle size D50 of the synthetic quartz sand was adjusted to 150 μm.

[0121] Comparative Example 10

[0122] The method of Example 10 was followed, except that the particle size D50 of the cristobalite was adjusted to 20 μm.

[0123] Comparative Example 11

[0124] The method of Example 10 was followed, except that the synthetic quartz sand was replaced with natural quartz sand.

[0125] Comparative Example 12

[0126] The method of Example 10 was followed, except that the sintering temperature was adjusted to 1750°C.

[0127] Comparative Example 13

[0128] The method of Example 2 was followed, except that only glassy synthetic quartz sand (purity 5N, D50 = 80 μm) was used as the raw material.

[0129] Comparative Example 14

[0130] The method of Example 2 was followed, except that only cristobalite (purity 5N, D50 = 80 μm) was used as the raw material and the calcination temperature was 1750°C.

[0131] The crucibles prepared in Examples 1-11 and Comparative Examples 1-14 were tested for structure and performance, and the results are shown in Tables 1-3.

[0132] Density was tested by Archimedes method; the grain size and content of cristobalite phase were tested by X-ray diffractometer; the crucible was used for the production of single crystal silicon pulling rod to test its service life (a silicon rod with a length of 2000 mm was prepared according to the method of patent CN 202411135978.9 embodiment 1).

[0133] Table 1

[0134]

[0135] As can be seen from Table 1: Examples 1-4, by using glassy synthetic quartz sand and cristobalite with a specific particle size range as raw materials, a crucible with a certain size of cristobalite grain was obtained, because uniform nucleation occurred, and no internal stress that would cause the crucible to break was generated. Comparative Examples 1-2 used glassy synthetic quartz sand or cristobalite with a larger particle size as raw materials, and the obtained crucible also had a larger grain size, which led to the cracking of the crucible; Comparative Example 3 used natural quartz sand (α-quartz), and because the natural quartz sand contained gas-liquid inclusions, impurities in the gas-liquid inclusions during the preparation process made the crystals in the crucible too large, which led to the cracking of the crucible. Comparative Example 4 had a sintering temperature higher than the melting point of cristobalite, and the cristobalite melted, so that a glassy quartz crucible was obtained, which could not uniformly crystallize and contained a certain amount of bubbles.

[0136] Table 2

[0137]

[0138] As can be seen from Table 2: Comparative Example 5 had a higher content of binder, and during the sintering process, the binder was removed, forming more pores, which led to the penetration of silicon liquid; Comparative Example 6 used synthetic quartz sand with a larger particle size, which led to non-uniform nucleation, and the obtained crucible also had a larger grain size of cristobalite, which led to the cracking of the crucible. Comparative Example 7 used natural quartz sand (α-quartz), and because the natural quartz sand contained gas-liquid inclusions, impurities in the gas-liquid inclusions during the preparation process made the crucible non-uniformly nucleate, and the crystals were too large, which led to the cracking of the crucible. Comparative Example 8 had a sintering temperature higher than the melting point of cristobalite, and a glassy quartz crucible was obtained, which contained more bubbles.

[0139] Table 3

[0140]

[0141] As can be seen from Table 3, the comparative examples 9 and 10 cracked because of the use of glassy synthetic quartz sand or cristobalite with large particle size, which caused non-uniform nucleation and large grain size. The comparative example 11 used natural quartz sand (a-quartz), which contained gas-liquid inclusions. The impurities in the gas-liquid inclusions caused non-uniform nucleation and large grain size, resulting in cracking of the crucible. The comparative example 12 used sintering temperature higher than the melting point of cristobalite, resulting in a glassy quartz crucible containing many bubbles. The comparative example 13 used glassy synthetic quartz sand without a fixed melting point. At a low temperature, the particles would soften and bond. Without cristobalite as an aggregate, the air in the gaps was encapsulated by the softened quartz sand during sintering, which was difficult to remove, resulting in many bubbles. The comparative example 14 used cristobalite only, which was sintered at 1750°C (higher than the melting point of cristobalite). The cristobalite was completely melted, resulting in a transparent quartz crucible (all glass phase).

[0142] The crucibles prepared in Examples 1-11 and Comparative Examples 4, 5, 8, 12 and 13 were heat treated at 1600°C for 10h to completely cristobalitize, and whether they cracked was observed. The results are shown in Table 4.

[0143] Table 4

[0144]

[0145] As can be seen from Table 4, the crucibles obtained in Examples 1-11 did not crack after further heat treatment to completely cristobalitize (similar to Figure 22 ), indicating that the crucible can still be used stably during use, because the nucleation of cristobalite is uniform. The crucibles obtained in Comparative Examples 4, 5, 8 and 12 cracked during heat treatment (similar to Figure 23 ), indicating that the crystallization process may not be uniform, resulting in stress cracking. The comparative example 13 contained many bubbles (similar to the bubble layer of conventional crucibles), and the strength of the crucible was low. At high temperatures, the bubbles expanded, the crystallization was not uniform, and the crucible cracked. The crucible obtained in Comparative Example 14 was glassy, had poor heat resistance, low strength at high temperatures, was easy to deform, and contained bubbles. Because the sintering temperature must be higher than the melting point of cristobalite, the energy consumption is higher than that of conventional crucibles, and cristobalite is hard to process.

[0146] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A quartz crucible, characterized in that: The quartz crucible has a single-layer structure, containing a glass phase and a cristobalite phase, and the cristobalite phase is uniformly dispersed in the glass phase; The grain size of the cristobalite phase is 5-15 μm, and the content is greater than 5%.

2. The quartz crucible according to claim 1, characterized in that: The density of the quartz crucible is 2.2~2.6 g / cm 3 ; The purity of the quartz crucible is greater than 4N8; The thickness of the quartz crucible is 12-16 mm, and the diameter is 100-1000 mm.

3. The quartz crucible according to claim 1, characterized in that: The quartz crucible is completely transformed into a cristobalite phase by heat treatment; The temperature of the heat treatment is 1200-1600°C.

4. The method for preparing a quartz crucible according to any one of claims 1 to 3, wherein: The following steps are involved: S1, mixing glassy synthetic quartz sand and cristobalite uniformly and then forming a green body to obtain a crucible green body; S2, sintering the crucible green body to obtain a quartz crucible; The proportion of the cristobalite is ≤5%, calculated based on the total mass of the glassy synthetic quartz sand and cristobalite; The D50 particle size of the synthetic quartz sand is ≤100 μm; The D50 particle size of the cristobalite is ≤10 μm; The green body forming method is one of centrifugal forming, slip casting and compression forming; When using the grouting method, it is also necessary to add a binder and water to prepare a slurry; The binder is one or more of polyvinyl alcohol and polyvinyl butyral; The amount of the binder used is 2-10% of the slurry mass.

5. The preparation method according to claim 4, characterized in that: The purity of the synthetic quartz sand is not less than 5N; The purity of the cristobalite is not less than 5N.

6. The preparation method according to claim 4, characterized in that: The sintering temperature is lower than the melting point of cristobalite; The sintering atmosphere is a vacuum or non-reactive atmosphere.

7. Use of the quartz crucible according to any one of claims 1 to 3 or the quartz crucible prepared by the preparation method according to any one of claims 4 to 6 in single crystal silicon production.

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