Crucible

Abstract

The utility model provides a crucible, which is applied to a single crystal furnace and comprises a crucible body and a plurality of airflow acceleration components. The crucible body comprises a cylindrical crucible side with an upper end opening and a lower end opening and a crucible bottom arranged at the bottom of the crucible side to seal the lower end opening of the crucible side. A plurality of air flow acceleration assemblies are arranged on the outer side wall of the crucible side, each air flow acceleration assembly is of a hollow structure and comprises an air inlet and an air outlet, the air inlet is adjacent to an opening in the upper end of the crucible side, the air outlet is adjacent to the crucible bottom, and the caliber area of the air inlet is smaller than that of the air outlet. According to the utility model, the plurality of airflow acceleration components are arranged on the peripheral wall of the crucible side, so that the acceleration of airflow in the furnace body is realized, the circulation speed of gas on the surface of silicon liquid in the crucible body is improved, the oxygen content in a single crystal is effectively reduced, and the crystal pulling efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of single crystal furnaces, in particular to a crucible. Background Art

[0002] With the rapid increase in the volume of N-type cells, especially Tunnel Oxide Passivated Contact solar cells (TOPcon), the demand for N-type silicon wafers has increased significantly. However, N-type silicon wafers have high requirements for crystal quality and oxygen-carbon content, requiring a higher minority carrier lifetime and a lower oxygen content. However, in the process of pulling single crystals, the oxygen content often exceeds the standard, resulting in unqualified silicon wafers such as concentric circles and black core wafers, thereby reducing the conversion efficiency of the battery.

[0003] The oxygen in silicon wafers mainly comes from the reaction between the quartz crucible and the silicon liquid during the heating process, which causes the oxygen to be integrated into the silicon. Reducing the oxygen content in the single crystal can effectively improve the quality of the single crystal and the cell. However, the single crystals prepared by the carbon-carbon crucible currently used cannot meet the low oxygen requirements. Utility Model Content

[0004] In view of this, the utility model provides a crucible to solve the problem that the crucible cannot provide an oxygen reduction function, resulting in low efficiency in pulling single crystals.

[0005] In order to solve the above technical problems, the utility model provides a crucible, which is applied to a single crystal furnace. The crucible comprises:

[0006] The crucible body comprises a cylindrical crucible with an upper opening and a lower opening and a crucible bottom arranged at the bottom of the crucible to seal the lower opening of the crucible, and the crucible body is made of carbon-carbon material;

[0007] Multiple airflow acceleration components are arranged on the outer side wall of the crucible. The airflow acceleration components are hollow structures, including an air inlet, an air outlet and a longitudinal airflow channel connecting the air inlet and the air outlet. The air inlet is adjacent to the upper end opening of the crucible, and the air outlet is adjacent to the bottom of the crucible. The caliber area of ​​the air inlet is smaller than the caliber area of ​​the air outlet.

[0008] In one embodiment of the present invention, the airflow acceleration component comprises:

[0009] A straight tube portion, which is arranged longitudinally and has an upper end diameter equal to a lower end diameter, and an upper end of the straight tube portion forms an air inlet;

[0010] The expansion part is arranged longitudinally and the diameter of the upper end of the expansion part is smaller than the diameter of the lower end. The upper end of the expansion part is connected to the lower end of the straight tube part, and the lower end of the expansion part forms an air outlet.

[0011] In one embodiment of the present invention, the diameter of the expansion portion gradually increases from the upper end to the lower end.

[0012] In one embodiment of the present invention, the diameter change rate of the expansion portion remains equal or gradually increases from the upper end to the lower end.

[0013] In one embodiment of the present invention, a plurality of airflow acceleration components are evenly arranged on the outer circumference of the crucible along the circumference of the crucible.

[0014] In one embodiment of the utility model, the straight tube portion is attached to the outer side wall of the crucible, and the upper end is flush with the upper end opening of the crucible, and the lower end is flush with the lower end opening of the crucible.

[0015] In one embodiment of the present invention, the height of the expansion portion is smaller than the height of the crucible bottom.

[0016] In one embodiment of the present invention, the straight tube portion and the expansion portion are integrally formed.

[0017] In one embodiment of the present invention, the airflow acceleration component is made of carbon-carbon material.

[0018] In one embodiment of the present invention, the airflow acceleration component and the crucible body are integrally formed.

[0019] The beneficial effects of the above technical solution of the utility model are as follows:

[0020] The crucible of the utility model embodiment is provided with a plurality of airflow acceleration components on the outer peripheral wall of the crucible, and the diameter area of ​​the air inlet of the airflow acceleration component is smaller than the diameter area of ​​the air outlet, so as to accelerate the airflow velocity at the air inlet position. The air inlet is adjacent to the upper end opening of the crucible, and the airflow acceleration component can accelerate the airflow near the surface of the molten silicon liquid at the upper end opening of the crucible, thereby reducing the oxygen content on the surface of the molten silicon liquid, thereby achieving the oxygen reduction function for the pulled single crystal silicon. Compared with the traditional carbon-carbon crucible that cannot provide the oxygen reduction function, resulting in low efficiency in pulling single crystals, the utility model can increase the circulation speed of the gas on the surface of the silicon liquid in the crucible when the crucible is heated, effectively reduce the oxygen content in the single crystal, and further improve the crystal pulling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a carbon-carbon crucible when being heated in the prior art;

[0022] Figure 2 This is a structural schematic diagram of a carbon-carbon crucible according to an embodiment of the utility model;

[0023] Figure 3 This is a schematic structural diagram of a carbon-carbon crucible when being heated according to an embodiment of the utility model;

[0024] Figure 4 This is a schematic structural diagram of an airflow acceleration component according to an embodiment of the utility model;

[0025] Figure 5 It is a cross-sectional view of the expansion portion of an embodiment of the utility model.

[0026] Reference numerals:

[0027] 100, crucible; 10, crucible body; 11, crucible top; 12, crucible bottom; 13, silicon liquid; 20, air flow acceleration assembly; 21, straight tube; 211, air inlet; 22, extension part; 221, air outlet; 30, guide tube; 40, single crystal furnace; 41, exhaust port. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the utility model.

[0029] In order to facilitate the understanding of the technical solution of the embodiment of the utility model, the technical problem to be solved by the present application is described below with reference to the accompanying drawings.

[0030] refer to Figure 1 , Figure 1 FIG. 2 shows a schematic diagram of the structure of a crucible 100 in the prior art when heated. Figure 1 As shown, when the silicon liquid 13 in the crucible 10 is heated, argon gas is blown from the top of the crucible 10 through the guide tube 30 onto the silicon liquid 13 in the crucible 10, and the oxygen released from the silicon liquid 13 is taken out. Since the gas flow rate at the surface of the silicon liquid 13 is low, the oxygen partial pressure at the contact point between the silicon liquid 13 surface and the gas is high. The efficiency of oxygen release in the silicon liquid 13 is directly related to the oxygen partial pressure at the surface of the silicon liquid 13. The higher the oxygen partial pressure, the lower the oxygen release efficiency in the silicon liquid 13. The crucible 11 cannot effectively reduce the oxygen content in the silicon liquid 13, resulting in a high or even excessive oxygen content in the pulled single crystal, which affects the efficiency of the single crystal furnace 40 in pulling single crystals.

[0031] In order to solve the above technical problems, the present application provides a crucible 100, which can quickly extract oxygen from the surface of the silicon liquid 13 in the crucible 100, thereby effectively reducing the oxygen content in the pulled single crystal.

[0032] The crucible 100 according to the embodiment of the utility model is first described in detail below with reference to the drawings.

[0033] refer to Figure 2 and Figure 3 , Figure 2 A schematic structural diagram of a crucible 100 according to an embodiment of the present invention is shown. Figure 3 The schematic diagram of the structure of the crucible 100 when heated according to the embodiment of the present invention is shown.

[0034] like Figure 2 and Figure 3 As shown, the crucible 100 includes a crucible body 10 and a plurality of airflow acceleration components 20. The crucible body 10 includes a cylindrical crucible 11 having an upper opening and a lower opening, and a crucible bottom 12 arranged at the bottom of the crucible 11 to seal the lower opening of the crucible, and the crucible body 10 is made of carbon-carbon material. The plurality of airflow acceleration components 20 are arranged on the outer wall of the crucible 11, and the airflow acceleration components 20 are hollow structures, including an air inlet 211, an air outlet 221, and a longitudinal airflow channel connecting the air inlet 211 and the air outlet 221. The air inlet 211 is adjacent to the upper opening of the crucible 11, and the air outlet is adjacent to the crucible bottom 12. The caliber area of ​​the air inlet 211 is smaller than the caliber area of ​​the air outlet 221. The crucible 100 is applied to a single crystal furnace 40.

[0035] In the embodiments of the present invention, Figure 2 and Figure 3 As shown, the crucible 10 is used to contain silicon liquid 13 in the single crystal furnace 40. A guide tube 30 is provided above the crucible 10 to guide argon gas to the liquid level of the silicon liquid 13 in the crucible 10. The open end of the crucible 10 is arranged opposite to the guide tube 30. An exhaust port 41 is provided at the bottom of the single crystal furnace 40 to discharge the gas in the crucible 10. Argon gas flows from the guide tube 30 above the crucible 11 to the silicon liquid 13 in the crucible 10, and is used to bring out oxygen in the silicon liquid 13. After the oxygen flows upward from the top of the silicon liquid 13 along the inner peripheral wall of the crucible 11, it flows along the air inlet 211 and the air outlet 221 of the airflow acceleration component 20 on the outer peripheral wall of the crucible 11 to the exhaust port 41 at the bottom of the single crystal furnace 40, thereby realizing the flow of gas in the single crystal furnace 40. The caliber of the air inlet 211 is smaller than that of the air outlet 221. According to the Bernoulli principle, the same volume of fluid per unit time has different flow rates through pipes of different diameters. The caliber of the air inlet 211 is smaller than that of the air outlet 221. Therefore, the gas flow rate of the air inlet 211 will be sharply accelerated. The faster the flow rate, the smaller the surrounding pressure, so that the pressure near the surface of the silicon liquid 13 at the upper end opening of the crucible 11 is smaller, and the oxygen partial pressure is smaller. The efficiency of oxygen escaping from the silicon liquid 13 is directly related to the oxygen partial pressure at the contact point between the liquid surface of the silicon liquid 13 and the gas. When the oxygen partial pressure at the liquid surface is smaller, the more oxygen will escape from the silicon liquid 13. The air inlet 211 is close to the liquid surface of the silicon liquid 13. The gas flow rate of the air inlet 211 is accelerated, so that the gas flow rate at the liquid surface of the silicon liquid 13 is accelerated, which effectively reduces the oxygen partial pressure at the liquid surface of the silicon liquid 13, is more conducive to the escape and discharge of oxygen, and realizes the efficient oxygen reduction of the crucible 100.

[0036] Compared with the crucible 100 in the prior art, the outer wall of the crucible body 10 is not provided with an airflow acceleration component, the gas flow rate at the liquid surface of the silicon liquid 13 in the crucible body 10 is low, the oxygen partial pressure is high, and the oxygen content in the silicon liquid 13 cannot be effectively reduced, resulting in a high oxygen content in the pulled single crystal, which affects the crystal pulling efficiency of the single crystal furnace. In the embodiment of the utility model, by providing a plurality of airflow acceleration components 20 on the outer peripheral wall of the crucible body 11, the flow rate of the gas on the surface of the silicon liquid 13 can be increased when the crucible body 10 is heated, effectively reducing the oxygen content in the single crystal, and further improving the crystal pulling efficiency.

[0037] In the embodiment of the utility model, the airflow acceleration component 20 is made of carbon-carbon material, the crucible body 10 and the airflow acceleration component 20 are integrally formed, and the specific preparation process of the crucible 100 is: firstly, a preform is prepared with carbon fiber, and then the structure is stabilized through processes such as shaping, and then graphite is deposited and attached to the preform through processes such as impregnation and deposition to form a carbon-carbon material, and then the shape specifications are processed using turning tools such as lathes. In other words, the crucible body 10 and the airflow acceleration component 20 of the utility model are used as a whole in the preparation process, and this overall structure is prepared during the preparation process of the preform, and after the deposition is completed, the structure with a small upper opening and a large lower opening can be dredged.

[0038] In one embodiment of the present invention, Figure 2 , Figure 3 , and refer to Figure 4 , Figure 4 FIG. 2 shows a schematic diagram of the structure of the airflow acceleration component of an embodiment of the utility model. Figure 2 , Figure 3 and Figure 4 As shown, the airflow acceleration assembly 20 includes a straight tube portion 21 and an extension portion 22. The straight tube portion 21 is arranged longitudinally and the upper end diameter is equal to the lower end diameter, and the upper end of the straight tube portion 21 forms an air inlet 211. The extension portion 22 is arranged longitudinally and the upper end diameter is smaller than the lower end diameter. The upper end of the extension portion 22 is connected to the lower end of the straight tube portion 21, and the lower end of the extension portion 22 forms an air outlet 221. The straight tube portion 21 is attached to the outer wall of the crucible 11, and the extension portion 22 is attached to the outer wall of the crucible bottom 12. The air inlet 211 is used to transport the gas on the surface of the silicon liquid 13 in the crucible 11 to the straight tube portion 21. The air outlet 221 is used to transport the gas in the straight tube portion 21 to the exhaust port 41 at the bottom of the single crystal furnace 40.

[0039] The specific parameters of the airflow acceleration component 20 are as follows: the height of the straight tube 21 is 350 mm, the outer diameter is 10 mm, and the inner diameter is 5 mm. The height of the extension part 22 is 260 mm, the outer diameter of the lower opening of the extension part is 140 mm, and the inner diameter of the lower opening is 130 mm. The unit of single crystal oxygen content is parts per million (ppm). In the prior art, the single crystal oxygen content ranges from 9 to 15 ppm. By arranging the airflow acceleration component 20 outside the crucible 10, the single crystal oxygen content can be reduced by 2 to 5 ppm, which effectively reduces the oxygen content and facilitates improving the crystal pulling efficiency.

[0040] In one embodiment of the present invention, Figure 4 As shown, the diameter of the expansion portion 22 gradually increases from the upper end to the lower end, which is beneficial for the gas from the straight tube portion 21 to accelerate through the expansion portion 22.

[0041] In one embodiment of the present invention, reference Figure 5 , Figure 5 1 shows a cross-sectional view of the expansion portion of an embodiment of the utility model. Figure 5 As shown in FIG. 1 , the diameter change rate of the expansion portion 22 remains the same or gradually increases from the upper end to the lower end. When the diameter change rate of the expansion portion 22 remains the same, as shown in FIG. Figure 5 As shown in FIG. (a) of FIG. 1 , the cross section of the expansion portion 22 is in the shape of a truncated cone. When the diameter change rate of the expansion portion 22 increases, as shown in FIG. Figure 5 As shown in FIG. 2( b ), the cross section of the extension portion 22 is trumpet-shaped.

[0042] In one embodiment of the present invention, Figure 2 and Figure 3 As shown, a plurality of airflow acceleration components 20 are evenly arranged on the outer periphery of the crucible body 11 along the circumference of the crucible body 11 , so that the gas above the silicon liquid 13 in the crucible body 10 can smoothly flow through the airflow acceleration components 20 .

[0043] In one embodiment of the present invention, Figure 2 As shown, the straight tube portion 21 is attached to the outer wall of the crucible 11 and the upper end is flush with the upper opening of the crucible 11 , and the lower end is flush with the lower opening of the crucible 11 .

[0044] In one embodiment of the present invention, Figure 2 and Figure 3 As shown, the height of the extension part 22 is less than the height of the crucible bottom 12. The upper end of the extension part 22 is flush with the lower end opening of the crucible 11, and the arc length of the side wall of the extension part 22 is less than the arc length of the side wall of the crucible bottom 12.

[0045] In one embodiment of the present invention, Figure 2As shown, the straight tube portion 21 and the extension portion 22 are integrally formed to ensure that the gas flowing through the airflow acceleration component 20 is not dispersed.

[0046] In one embodiment of the present invention, the material of the airflow acceleration component 20 is a composite carbon-carbon material.

[0047] The working principle of the crucible 100 according to the embodiment of the present invention will be described below in conjunction with its structure.

[0048] When the crucible 100 is heated, the exhaust device of the single crystal furnace 40 continues to exhaust gas below the crucible body 10, and argon gas is blown from the top of the crucible body 10 through the guide tube 30 onto the silicon liquid 13 in the crucible body 10, taking out the oxygen that escapes from the silicon liquid 13, and the oxygen above the silicon liquid 13 flows through the air inlet 211 and the air outlet 221 of the air flow acceleration component 20, and flows to the exhaust port 41 at the bottom of the single crystal furnace 40. The air flow at the air inlet 211 is accelerated, which increases the gas flow rate at the liquid surface of the silicon liquid 13 in the crucible body 10, reduces the oxygen partial pressure at the liquid surface of the silicon liquid 13, and realizes the oxygen reduction of the carbon-carbon crucible 100.

[0049] In summary, the crucible 100 of the utility model embodiment, by arranging multiple airflow acceleration components 20 on the outer peripheral wall of the crucible body 11, can increase the circulation speed of the gas on the surface of the silicon liquid 13 in the crucible body 10 when the crucible body 10 is heated, thereby reducing the oxygen partial pressure at the liquid surface of the silicon liquid 13, further reducing the oxygen content in the single crystal, and improving the crystal pulling efficiency of the single crystal furnace.

[0050] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. The words "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0051] The above is a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A crucible used in a single crystal furnace, characterized in that: include: The crucible body comprises a cylindrical crucible having an upper opening and a lower opening and a crucible bottom arranged at the bottom of the crucible to seal the lower opening of the crucible, and the crucible body is made of carbon-carbon material; A plurality of airflow acceleration components are arranged on the outer side wall of the crucible. The airflow acceleration components are hollow structures, including an air inlet, an air outlet and a longitudinal airflow channel connecting the air inlet and the air outlet. The air inlet is adjacent to the upper end opening of the crucible, and the air outlet is adjacent to the bottom of the crucible. The caliber area of ​​the air inlet is smaller than the caliber area of ​​the air outlet.

2. The crucible according to claim 1, characterized in that The airflow acceleration component comprises: A straight tube portion, the straight tube portion is arranged longitudinally and the diameter of the upper end is equal to the diameter of the lower end, and the upper end of the straight tube portion forms the air inlet; The expansion part is arranged longitudinally and has an upper end diameter smaller than a lower end diameter. The upper end of the expansion part is connected to the lower end of the straight tube part, and the lower end of the expansion part forms the air outlet.

3. The crucible according to claim 2, characterized in that The diameter of the expansion portion gradually increases from the upper end to the lower end.

4. The crucible according to claim 3, characterized in that The diameter change rate of the expansion portion remains equal or gradually increases from the upper end to the lower end.

5. The crucible according to any one of claims 2 to 4, characterized in that: A plurality of airflow acceleration components are evenly arranged on the outer periphery of the crucible along the circumference of the crucible.

6. The crucible according to claim 5, characterized in that The straight tube portion is attached to the outer side wall of the crucible, and the upper end is flush with the upper end opening of the crucible, and the lower end is flush with the lower end opening of the crucible.

7. The crucible according to claim 6, characterized in that The height of the expansion portion is smaller than the height of the crucible bottom.

8. The crucible according to claim 2, characterized in that The straight tube portion and the extension portion are integrally formed.

9. The crucible according to claim 1, characterized in that The airflow acceleration component is made of carbon-carbon material.

10. The crucible according to claim 1, characterized in that The airflow acceleration component is integrally formed with the crucible body.

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