Crucible preparation method and crucible structure

Abstract

The invention provides a crucible preparation method and a crucible structure, and the crucible preparation method comprises the following steps: weighing quartz sand for pretreatment; the weighed quartz sand is poured into a rotating crucible mold for multiple times, and vacuumizing treatment is conducted at the same time, so that the side wall of a crucible is of a multi-layer structure; filling particles are poured into the rotating crucible mold, vacuumizing treatment is conducted at the same time, so that the filling particles are embedded in the inner wall of the crucible, and a concave-convex surface is formed on the inner wall of the crucible; and introducing current into an electrode above the crucible mold to form an electric arc in a high-temperature state, heating the quartz sand in the crucible mold for a preset time, closing the electric arc, cooling, and curing and forming to obtain a crucible body. In the crystal growth process, the embedded filling particles can reduce the direct contact area of molten silicon liquid and the inner wall of the crucible, so that the chemical reaction between the silicon liquid and the crucible is reduced, the service life of the crucible is prolonged, and the oxygen content in a silicon rod is reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of single crystal silicon manufacturing equipment, and in particular to a crucible preparation method and a crucible structure. Background Art

[0002] With the continuous development of the world economy, the demand for efficient energy in modernization construction is growing. Photovoltaic power generation, as a green energy and a major energy source for sustainable development of mankind, is increasingly valued and developed by countries around the world. As a basic material for photovoltaic power generation, monocrystalline silicon wafers have a wide market demand. However, due to the influence of European and American photovoltaic policies on China, China's photovoltaic industry faces unprecedented challenges. Therefore, reducing costs, increasing efficiency and improving product quality have become the only conditions for the survival of enterprises. Therefore, it is of great significance to study how to improve the life of crucibles and reduce the oxygen content of silicon rods.

[0003] During the crystal growth process, the inner wall of the crucible is in direct contact with the silicon liquid, and the crucible rotates during the crystal growth process, which accelerates the reaction between the crucible and the silicon liquid, causing bulging on the inner wall of the crucible, thereby reducing the service life of the crucible.

[0004] Therefore, how to provide a crucible preparation method and a crucible structure that can reduce the reaction rate between the crucible and silicon liquid is a problem that urgently needs to be solved. Summary of the invention

[0005] To solve the above technical problems, the embodiments of the present invention provide a method for preparing a crucible, comprising the following steps: weighing quartz sand for pretreatment; pouring the weighed quartz sand into a rotating crucible mold for multiple times, and simultaneously performing a vacuum treatment so that the side wall of the crucible has a multi-layer structure; pouring filling particles into the rotating crucible mold, and simultaneously performing a vacuum treatment so that the filling particles are embedded in the inner wall of the crucible, so that the inner wall of the crucible forms a concave and convex surface; passing an electric current through an electrode above the crucible mold to form an electric arc in a high-temperature state, heating the quartz sand in the crucible mold, and after heating for a preset time, turning off the electric arc and cooling it to solidify and form a crucible body.

[0006] In some embodiments, the filler particles are silicon carbide particles.

[0007] In some embodiments, filling particles are poured into the rotating crucible mold, specifically, filling particles with gradually increasing particle sizes are poured into the mold in sequence from the bottom of the side wall of the crucible mold to the top of the side wall.

[0008] In some embodiments, filling particles are poured into the rotating crucible mold, specifically, filling particles with gradually increasing densities are poured into the crucible mold in sequence from the bottom of the side wall of the crucible mold to the top of the side wall.

[0009] In some embodiments, the quartz sand in the crucible mold is heated, specifically: the quartz sand in the crucible mold is heated, and during the heating process, the crucible mold rotates synchronously, and the heating temperature is lower than the melting temperature of the filling particles and higher than the melting temperature of the quartz sand.

[0010] In some embodiments, quartz sand is weighed for pretreatment, and the weighed quartz sand is poured into a rotating crucible mold multiple times. Specifically, the quartz sand is weighed three times, and the weight of the quartz sand weighed each time is different. Then, the quartz sands of different weights are poured into the crucible mold three times in sequence to form an outer layer of sand, a middle layer of sand, and an inner layer of sand with gradually increasing thicknesses.

[0011] In some embodiments, the purity of the quartz sand weighed three times increases gradually to form an outer layer of sand, a middle layer of sand, and an inner layer of sand with gradually increasing purity.

[0012] In some embodiments, after weighing the quartz sand for pretreatment, the method further includes: adding titanium dioxide to the quartz sand, wherein the amount of titanium dioxide added is 1%-5% of the total weight of the quartz sand.

[0013] In some embodiments, the filler particles have a particle size larger than the particle size of the quartz sand.

[0014] A crucible structure is prepared by the crucible preparation method.

[0015] Through the above technical scheme, the present disclosure provides a crucible preparation method and crucible structure, by adding filling particles in the process of making the crucible, so that the inner wall of the crucible presents a concave-convex surface. During the crystal growth process, these embedded filling particles can reduce the area of ​​direct contact between the molten silicon liquid and the inner wall of the crucible, thereby reducing the chemical reaction between the silicon liquid and the crucible. In addition, after the filling particles are embedded in the inner wall of the crucible, a disturbance effect will be produced on the silicon liquid when the crucible rotates. This disturbance can break the original laminar state of the silicon liquid, promote the vortex flow inside the silicon liquid, reduce the relative speed between the silicon liquid and the crucible, reduce the friction between the silicon liquid and the crucible, thereby reducing the chemical reaction between the silicon liquid and the crucible, which helps to improve the service life of the crucible, reduce the oxygen content in the silicon rod, and the embedded filling particles form a whole with the inner wall of the crucible, and the filling particles are not easy to fall off. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 is a flowchart of the steps of a method for preparing a crucible disclosed in an embodiment of the present disclosure;

[0018] Figure 2 is a structural schematic diagram of a crucible structure disclosed in an embodiment of the present disclosure;

[0019] Figure 3 is a structural schematic diagram of another crucible structure disclosed in an embodiment of the present disclosure;

[0020] Figure 4 It is a structural schematic diagram of another crucible structure disclosed in an embodiment of the present disclosure.

[0021] Description of reference numerals:

[0022] 1. Crucible structure; 11. Outer layer of sand; 12. Middle layer of sand; 13. Inner layer of sand; 2. Filling particles; 3. Silicon liquid; 4. Gas-liquid interface. DETAILED DESCRIPTION

[0023] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0024] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0025] It should be noted that, in the description of the present disclosure, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0026] In addition, the words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0027] It should also be noted that in the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0028] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0029] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0030] During the crystal growth process, the inner wall of the quartz crucible is in contact with the silicon liquid 3, and the quartz crucible is always in a rotating state, which will accelerate the reaction between the quartz crucible and the silicon liquid 3 to produce oxygen, resulting in an increase in the oxygen content of the silicon rod, and bulging on the inner wall of the quartz crucible, reducing the service life of the quartz crucible. Therefore, the inventor wants to design a crucible preparation method and a crucible structure 1 that can reduce the reaction rate between the crucible and the silicon liquid 3.

[0031] Embodiment 1

[0032] The present disclosure provides a method for preparing a crucible, comprising the following steps:

[0033] S1, weigh quartz sand for pretreatment;

[0034] Specifically, if Figure 1As shown, impurities on the surface of quartz sand, such as dust, organic matter, etc., can be removed by water washing or acid washing. Quartz sand can be placed in a solution containing oxides, and then hydrochloric acid or nitric acid is added to the solution, and the solution is heated and cleaned with ultrasound.

[0035] S2, pouring the weighed quartz sand into a rotating crucible mold several times, and simultaneously performing a vacuum treatment so that the side wall of the crucible has a multi-layer structure;

[0036] Specifically, Figure 1 As shown, the weighed quartz sand is poured into the rotating crucible mold several times. The number of times is not specifically limited here, and can be selected according to the number of layers of the crucible side wall actually required. For example, if the number of layers of the crucible side wall is to be 3, the quartz sand is poured in three times. Each time the quartz sand is poured, the mold keeps rotating to ensure that the quartz sand is evenly distributed and tightly attached to the inner wall of the mold by using centrifugal force, and vacuum treatment is performed at the same time to increase the density of the quartz sand and prevent air from existing between the sand particles. By pouring quartz sand several times and performing vacuum treatment, the desired multi-layer structure is finally formed on the inner wall of the crucible.

[0037] S3, pouring filling particles 2 into the rotating crucible mold, and simultaneously performing a vacuum treatment, so that the filling particles 2 are embedded in the inner wall of the crucible, so that the inner wall of the crucible forms a concave-convex surface;

[0038] Specifically, Figure 1-Figure 4 As shown, after the last pouring of quartz sand, the filling particles 2 are poured in, so that they are embedded in the inner wall of the crucible, so that the inner wall of the crucible forms a concave-convex surface, so as to reduce the contact area between the inner wall of the crucible and the silicon liquid 3, thereby reducing the reaction rate between the inner wall of the crucible and the silicon liquid 3. In the molten state of the quartz sand, the filling particles 2 are combined with the molten quartz sand, and the fluidity of the quartz sand is used to make the filling particles 2 embedded in the inner wall of the crucible. The shape and surface characteristics of the filling particles 2 combined with the molten quartz sand form a mechanical interlocking, which enhances the bonding force between the filling particles 2 and the quartz sand.

[0039] S4. Passing current through the electrode above the crucible mold to form an arc in a high-temperature state to heat the quartz sand in the crucible mold. After heating for a preset time, the arc is turned off and cooled to solidify and form the crucible to obtain a crucible body.

[0040] Specifically, Figure 1 As shown, after pouring the filling particles 2, the power is turned on to perform arc heating to heat the quartz sand to a molten state. During the arc heating process, the filling particles 2 are combined with the molten quartz sand, and the fluidity of the quartz sand is used to embed the filling particles 2 into the inner wall of the crucible. The vacuum treatment time and vacuum degree need to be properly controlled to ensure that the air inside the mold is effectively extracted.

[0041] In some embodiments, the filler particles 2 are silicon carbide particles.

[0042] Specifically, Figure 1 As shown, the filling particles 2 can be silicon carbide particles, the melting point of which is 2700°C, and the melting point and crystal growth temperature of quartz sand are both lower than 2700°C, so that silicon carbide can be embedded in the inner wall of the crucible in a solid form, so that the inner wall of the crucible always presents a concave-convex surface. In addition, the filling particles 2 can also be silicon nitride particles, aluminum nitride particles, etc.

[0043] In some embodiments, the filling particles 2 are poured into the rotating crucible mold, specifically, the filling particles 2 with gradually increasing particle sizes are poured into the mold from the bottom of the side wall of the crucible mold to the top of the side wall.

[0044] Specifically, Figure 3 As shown, the circle where the liquid surface of the silicon liquid 3 is located is in contact with the air layer, forming a gas-liquid interface 4. As the crucible rotates, the circle where the liquid surface of the silicon liquid 3 is located is constantly in contact with the inner wall of the quartz crucible, and is in contact with the oxygen in the air layer, which promotes the reaction between the inner wall of the crucible and the silicon liquid 3, so that the reaction of the circle where the gas-liquid interface 4 of the inner wall of the crucible is usually more intense. Filling particles 2 with gradually increasing particle sizes are poured into the mold from the bottom of the side wall of the crucible mold to the top of the side wall, and a concave-convex surface with different particle size distributions is formed at different heights of the crucible, so that the particle size of the filling particles 2 on the side wall of the circle at the crucible gas-liquid interface 4 is larger than the particle size of the filling particles 2 in other places, so that the area where the inner wall of the crucible where the gas-liquid interface 4 is located is smaller than the contact area in other places, so as to reduce the reaction rate.

[0045] In some embodiments, the filling particles 2 are poured into the rotating crucible mold, specifically, the filling particles 2 with gradually increasing density are poured into the crucible mold in sequence from the bottom of the side wall of the crucible mold to the top of the side wall.

[0046] Specifically, Figure 4 As shown, in order to reduce the reaction between the side wall of the crucible and the silicon liquid 3 in the circle where the gas-liquid interface 4 is located, the filling particles 2 with a lower density can be poured into the mold starting from the bottom of the side wall of the crucible mold, and then the filling particles 2 with a gradually increasing density can be gradually poured upwards, so that a concave-convex surface with different density distributions of the filling particles 2 can be formed at different heights of the crucible. The filling particles 2 with a higher density can more effectively reduce the contact area between the silicon liquid 3 and the inner wall of the crucible, thereby reducing the reaction speed of the silicon liquid 3 and the inner wall of the crucible, especially in the circle where the gas-liquid interface 4 is located.

[0047] The present disclosure provides a method for preparing a crucible and a crucible structure 1. In the process of making the crucible, filling particles 2 are added and embedded on the inner wall surface of the crucible, so that the inner wall of the crucible presents a concave-convex surface. During the crystal growth process, these embedded filling particles 2 can reduce the area of ​​direct contact between the molten silicon liquid 3 and the inner wall of the crucible, thereby reducing the chemical reaction between the silicon liquid 3 and the crucible. In addition, after the filling particles 2 are embedded in the inner wall of the crucible, a disturbance effect will be produced on the silicon liquid 3 when the crucible rotates. This disturbance can break the original laminar state of the silicon liquid 3, promote the vortex flow inside the silicon liquid 3, reduce the relative speed between the silicon liquid 3 and the crucible, reduce the friction between the silicon liquid 3 and the crucible, thereby reducing the chemical reaction between the silicon liquid 3 and the crucible, which helps to improve the service life of the crucible, reduce the oxygen content in the silicon rod, and the embedded filling particles 2 form a whole with the inner wall of the crucible, and the filling particles 2 are not easy to fall off.

[0048] In some embodiments, the quartz sand in the crucible mold is heated, specifically: the quartz sand in the crucible mold is heated, and during the heating process, the crucible mold rotates synchronously, and the heating temperature is lower than the melting temperature of the filling particles 2 and higher than the melting temperature of the quartz sand.

[0049] Specifically, Figure 1 As shown, the quartz sand is heated by electric arc heating, and the heating temperature is greater than the melting temperature of the quartz sand and less than the temperature of the filling particles 2. For example, when the filling particles 2 are silicon carbide particles, the heating temperature can be 1700° C. During the heating process, the crucible mold is rotated synchronously to ensure that the quartz sand is evenly melted and to help the filling particles 2 embed into the molten quartz sand to form a stable structure.

[0050] In some embodiments, quartz sand is weighed for pretreatment, and the weighed quartz sand is poured into a rotating crucible mold several times. Specifically, the quartz sand is weighed three times, and the weight of the quartz sand weighed each time is different. Then, the quartz sands of different weights are poured into the crucible mold three times in sequence to form an outer layer of sand 11, a middle layer of sand 12, and an inner layer of sand 13 with gradually increasing thicknesses.

[0051] Specifically, as shown in the figure, since the inner layer of the crucible is in contact with the silicon liquid 3 and reacts, the thickness of the crucible will decrease as the crucible is used for an increasing period of time, so a heavier quartz sand is filled in the inner layer of the crucible to maximize the thickness of the inner layer. Weigh less quartz sand as the outer layer sand 11, weigh more quartz sand than the first time as the middle layer sand 12, and weigh the most quartz sand as the inner layer sand 13. Pour the quartz sand weighed for the first, second, and third times into the crucible mold in turn, and by pouring the weighed quartz sand into the rotating crucible mold three times, the outer layer sand 11, the middle layer sand 12, and the inner layer sand 13 with gradually increasing thickness can be formed. In order to ensure that the quartz sand is evenly distributed, the rotation speed range of the crucible mold can be between 200RPM-800RPM.

[0052] In some embodiments, the purity of the quartz sand weighed three times gradually increases to form an outer layer of sand 11, a middle layer of sand 12, and an inner layer of sand 13 with gradually increasing purity.

[0053] Specifically, if Figure 1 As shown, in order to save costs and make full use of high-purity quartz sand, the quartz sand can be weighed three times according to the principle of gradually increasing purity to form an outer layer of sand 11, a middle layer of sand 12 and an inner layer of sand 13 with gradually increasing purity.

[0054] In some embodiments, after weighing the quartz sand for pretreatment, the method further includes: adding titanium dioxide to the quartz sand, wherein the amount of titanium dioxide added is 1%-5% of the total weight of the quartz sand.

[0055] Specifically, if Figure 1 As shown, titanium dioxide is added to the quartz sand poured into the crucible mold each time and mixed evenly. Titanium dioxide can reduce the reaction between the inner wall of the crucible and the silicon liquid 3, reduce the oxidation of the inner wall of the crucible, and improve the thermal stability, chemical stability and mechanical strength of the crucible. The addition amount of titanium dioxide is 1%-5% of the total weight of the quartz sand.

[0056] In some embodiments, the particle size of the filling particles 2 is larger than the particle size of the quartz sand.

[0057] Specifically, if Figure 1 As shown, the particle size of the filling particles 2 is larger than that of the quartz sand, and the larger filling particles 2 can be embedded more deeply into the molten quartz sand to form a more protruding structure. This can effectively increase the protrusion of the inner wall surface of the crucible, reduce the direct contact area between the silicon liquid 3 and the inner wall of the crucible, and reduce the friction between the silicon liquid 3 and the inner wall of the crucible.

[0058] Embodiment 2

[0059] A crucible structure 1 is prepared by the above crucible preparation method.

[0060] Specifically, if Figure 2-Figure 4 As shown, the crucible structure 1 has a multi-layer structure, and the number of layers of the crucible structure 1 can be set according to actual needs. The sand layer of the crucible structure 1 gradually increases from the outer peripheral surface to the inner peripheral surface, and the sand layer in the crucible is embedded with filling particles 2, so that the inner surface of the crucible structure 1 forms a concave and convex surface. The bottom of the crucible is thicker and not easily damaged. In order to reduce costs, filling particles 2 can be set only on the inner side wall of the crucible structure 1, and no filling particles 2 are set on the bottom of the crucible. According to the different heights of the side wall of the crucible structure 1, the degree of reaction with the silicon liquid 3 is different, such as Figure 3 As shown, the particle size of the particles 2 filled on the side wall of the crucible can gradually increase from the bottom to the top of the crucible, such as Figure 4As shown, the density of the filling particles 2 on the side wall of the crucible may gradually increase from the bottom to the top of the crucible.

[0061] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0062] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A method for preparing a crucible, characterized in that: The steps include: Weigh quartz sand for pretreatment; Pour the weighed quartz sand into a rotating crucible mold several times, and simultaneously perform a vacuum treatment so that the side wall of the crucible has a multi-layer structure; Pour filling particles (2) into the rotating crucible mold, and simultaneously perform a vacuum treatment so that the filling particles (2) are embedded in the inner wall of the crucible, so that the inner wall of the crucible forms a concave-convex surface; Current is passed through the electrode above the crucible mold to form an arc in a high-temperature state to heat the quartz sand in the crucible mold. After heating for a preset time, the arc is turned off and cooled to solidify and form a crucible body.

2. The method for preparing a crucible according to claim 1, characterized in that: The filling particles (2) are silicon carbide particles.

3. The method for preparing a crucible according to claim 1, characterized in that: The step of pouring the filling particles (2) into the rotating crucible mold comprises: Filling particles (2) with gradually increasing particle sizes are poured into the mold in sequence from the bottom of the side wall of the crucible mold to the top of the side wall.

4. The method for preparing a crucible according to claim 1, characterized in that: The step of pouring the filling particles (2) into the rotating crucible mold comprises: Filling particles (2) with gradually increasing density are poured into the crucible mold in sequence from the bottom of the side wall of the crucible mold to the top of the side wall.

5. The method for preparing a crucible according to claim 1, characterized in that: The step of heating the quartz sand in the crucible mold comprises: The quartz sand in the crucible mold is heated. During the heating process, the crucible mold rotates synchronously. The heating temperature is lower than the melting temperature of the filling particles (2) and higher than the melting temperature of the quartz sand.

6. The method for preparing a crucible according to claim 1, characterized in that: The weighed quartz sand is pre-treated, and the weighed quartz sand is poured into a rotating crucible mold in multiple times, specifically: The quartz sand is weighed three times, and the weight of the quartz sand weighed each time is different. The quartz sands of different weights are poured into the crucible mold three times in sequence to form an outer layer of sand (11), a middle layer of sand (12) and an inner layer of sand (13) with gradually increasing thicknesses.

7. The method for preparing a crucible according to claim 6, characterized in that: The purity of the quartz sand weighed three times gradually increases to form an outer layer of sand (11), a middle layer of sand (12) and an inner layer of sand (13) with gradually increasing purity.

8. The method for preparing a crucible according to claim 1, characterized in that: After the quartz sand is weighed and pre-treated, the method further comprises: Titanium dioxide is added to the quartz sand, and the added amount of titanium dioxide is 1%-5% of the total weight of the quartz sand.

9. The method for preparing a crucible according to claim 1, characterized in that: The particle size of the filling particles (2) is larger than the particle size of the quartz sand.

10. A crucible structure, characterized in that: The crucible is prepared by the crucible preparation method according to any one of claims 1 to 9.

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