Graphite crucible for Czochralski single crystal furnace

Abstract

A graphite crucible for a Czochralski single crystal furnace relates to the technical field of graphite crucibles and comprises a first crucible block and a second crucible block, the first crucible block and the second crucible block are spliced to form a circular crucible body with a closed bottom end and an open top end, and a crucible ring extending upwards is coaxially arranged at the top end of the crucible body; the graphite crucible comprises a crucible body, at least one exhaust hole is formed in the crucible body, a plurality of grooves distributed in the axial direction of the crucible body are formed in the inner wall of the crucible body in a surrounding mode, and the grooves are communicated with the exhaust hole, so that gas in the graphite crucible is guided to the exhaust hole through the grooves to flow out. Gas can be conveniently discharged out of the crucible body, the wall of the crucible is prevented from being thinned due to gas scouring, and the service life of the crucible is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to monocrystalline silicon production technical field, and specifically is a graphite crucible for straight pulling single crystal furnace. BACKGROUND

[0002] In the precision process of preparing monocrystalline silicon by CZ straight pulling method, the graphite crucible plays an important role, and in the crystal pulling process, the graphite crucible is used as a supporting structure, and the quartz crucible is placed in the graphite crucible, the polycrystalline silicon raw material is placed in the quartz crucible, the conversion of polycrystalline silicon to silicon melt is realized through the accurate control of the external heater, and finally the monocrystalline silicon is formed through the straight pulling technology.

[0003] In the high-temperature crystal pulling process, chemical reaction occurs between the graphite crucible and the quartz crucible to produce carbon monoxide and carbon dioxide gas, and these gases are discharged through the gap between the crucible petals, resulting in continuous erosion of these areas by the gas, especially the R corner position of the crucible, which in turn causes the rapid thinning of the crucible wall and the R corner position, shortening the service life of the crucible. At the same time, the gas accumulated at the bottom of the crucible and the R corner position cannot be discharged in time, which will cause the quartz crucible to deform, and thus interrupt the crystal pulling process. SUMMARY

[0004] In order to solve the problem of thinning of the crucible wall due to gas erosion in the prior art, the utility model provides a graphite crucible for a straight pulling single crystal furnace, which facilitates the discharge of gas outside the crucible body, prevents the thinning of the crucible wall due to gas erosion, and is beneficial to prolong the service life of the crucible.

[0005] In order to achieve the above-mentioned purpose, the utility model adopts the specific scheme that a graphite crucible for a straight pulling single crystal furnace, comprising a first crucible block and a second crucible block, the first crucible block and the second crucible block are spliced to form a circular crucible body with a closed bottom and an open top end, and a crucible ring extending upward is coaxially arranged at the top end of the crucible body; at least one exhaust hole is formed on the crucible body, a plurality of grooves are arranged on the inner wall of the crucible body in the axial direction of the crucible body, and the grooves are in communication with the exhaust hole, so that the gas in the graphite crucible is guided to the exhaust hole through the grooves.

[0006] As an optimization scheme of the above-mentioned graphite crucible for a straight pulling single crystal furnace, a first groove is formed on the splicing surface of the first crucible block, a second groove corresponding to the first groove is formed on the splicing surface of the second crucible block, and the first groove and the second groove can be spliced to form the exhaust hole.

[0007] As another optimization scheme of the above-mentioned graphite crucible for a straight pulling single crystal furnace, a flow guide groove corresponding to the exhaust hole is arranged on the inner wall of the crucible body; the flow guide groove extends in the axial direction of the crucible body, so that all the grooves are in communication with the flow guide groove, and the exhaust hole is located at the top end of the flow guide groove and is in communication with the flow guide groove.

[0008] As another optimized solution for the graphite crucible used in the Czochralski single crystal furnace mentioned above: the inner wall of the first crucible block is provided with a third groove, and the inner wall of the second crucible block is provided with a fourth groove corresponding to the third groove, and the third groove and the fourth groove can be spliced ​​together to form a flow guide groove.

[0009] As another optimized solution for the graphite crucible used in the Czochralski single crystal furnace mentioned above: a downwardly extending protrusion is provided around the bottom end of the crucible ring; a receiving groove for accommodating the protrusion is provided around the top end of the crucible body.

[0010] As another optimized solution for the graphite crucible used in the Czochralski single crystal furnace mentioned above: the top of the crucible ring is a convex arc surface pointing upwards.

[0011] As another optimized solution for the graphite crucible used in the Czochralski single crystal furnace mentioned above: the outer side of the top of the crucible ring has a conical surface, with the large diameter end facing down and the small diameter end facing up.

[0012] As another optimized solution for the graphite crucible used in the Czochralski single crystal furnace mentioned above: both the bottom ends of the first crucible block and the second crucible block are provided with downwardly extending mounting blocks, and the two mounting blocks can be spliced ​​together to form a cylindrical plug.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1) This utility model provides a graphite crucible for a Czochralski single crystal furnace. The crucible body has at least one vent hole, and multiple grooves distributed along the axial direction of the crucible body are arranged around the inner wall of the crucible body. The grooves are connected to the vent hole, so that the gas in the graphite crucible is guided through the grooves to the vent hole and flows out, preventing the crucible wall from thinning due to gas erosion and extending the service life of the graphite crucible. At the same time, it avoids the deformation of the quartz crucible caused by the accumulation of gas in the graphite crucible, ensuring the smooth progress of the crystal pulling process.

[0015] 2) In this utility model, the inner wall of the crucible is provided with guide grooves corresponding to the vent holes one by one; the guide grooves extend along the axial direction of the crucible so that all grooves are connected to the guide grooves, and the vent holes are located at the top of the guide grooves and are connected to the guide grooves. That is, all grooves are connected to the vent holes through the guide grooves, reducing the number of vent holes on the graphite crucible and allowing the gas inside the graphite crucible to be discharged smoothly without reducing the heat preservation performance of the graphite crucible.

[0016] 3) In this utility model, the top of the crucible ring is a convex arc surface; the outer side of the top of the crucible ring has a conical surface, with the large diameter end facing down and the small diameter end facing up; this makes the top of the crucible ring form rounded corners and bevels, reducing stress concentration at the top of the graphite crucible; at the same time, it is beneficial to guide the airflow at the top of the graphite crucible, thereby reducing the phenomenon of edge chipping and peeling of the graphite crucible. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a graphite crucible;

[0018] Figure 2 This is a magnified view of a portion of the graphite crucible;

[0019] Figure 3 This is a cross-sectional view of a graphite crucible;

[0020] Figure 4 This is the front view of the graphite crucible;

[0021] Figure 5 This is a schematic diagram of the crucible body;

[0022] Figure 6 This is a schematic diagram of the crucible ring;

[0023] Figure 7 This is a schematic diagram showing the first and second crucible blocks not being joined together;

[0024] Reference numerals: 1. Crucible ring; 101. Protrusion; 2. Crucible body; 201. First crucible block; 2011. First groove; 2012. Third groove; 202. Second crucible block; 2021. Second groove; 2022. Fourth groove; 203. Vent hole; 204. Guide groove; 205. Receiving groove; 3. Groove; 4. Cylindrical plug; 401. Mounting block. Detailed Implementation

[0025] The technical solution of this utility model will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of this utility model should be understood as prior art known or should be known by those skilled in the art.

[0026] Example 1

[0027] like Figure 1As shown, a graphite crucible for a Czochralski single crystal furnace includes a first crucible block 201 and a second crucible block 202. The first crucible block 201 and the second crucible block 202 have identical structures, and both the first crucible block 201 and the second crucible block 202 have a semi-circular structure. The first crucible block 201 and the second crucible block 202 form a circular crucible body 2 with a closed bottom and an open top. The splicing surface of the first crucible block 201 and the splicing surface of the second crucible block 202 can fit together. In this invention, the R-angle is located at the connection between the side wall and the bottom of the crucible body 2. The thickness at the R-angle is slightly greater than the thickness at other locations in the graphite crucible. Because the R-angle is subjected to gas erosion for a long time, the crucible wall at the R-angle rapidly thins. Therefore, increasing the thickness at the R-angle further increases the service life of the graphite crucible. At the same time, during the process of splicing the first crucible block 201 and the second crucible block 202 to form the crucible body 2, the two are in planar contact and there are no sharp corners at the splice, avoiding sharp corner collisions between the two, thereby improving the durability of the graphite crucible.

[0028] During the crystal pulling process, the gaps at the joints of the graphite crucibles gradually widen, especially at the top of the graphite crucibles. Therefore, a crucible ring 1 extending upwards is coaxially arranged at the top of the crucible body 2. The inner diameter of the crucible ring 1 is equal to the inner diameter of the crucible body 2, and the outer diameter of the crucible ring 1 is equal to the outer diameter of the crucible body 2. After the crucible ring 1 is placed at the top of the crucible body 2, the outer wall of the crucible ring 1 is flush with the outer wall of the crucible body 2, and the inner wall of the crucible ring 1 is flush with the inner wall of the crucible body 2. A downwardly extending protrusion 101 is arranged around the bottom of the crucible ring 1. In this embodiment, the protrusion 101 and the crucible ring 1 are connected integrally. The protrusion 101 has a ring-shaped structure, the inner diameter of the protrusion 101 is equal to the inner diameter of the crucible ring 1, and the outer diameter of the protrusion 101 is smaller than the outer diameter of the crucible ring 1, so that the protrusion 101 and the bottom of the crucible ring 1 form a stepped surface. A receiving groove 205 for accommodating the protrusion 101 is provided around the top of the crucible body 2. The receiving groove 205 is located inside the top of the crucible body 2 and forms a stepped surface at the top of the crucible body 2. After the protrusion 101 extends into the receiving groove 205, the two stepped surfaces fit together to achieve connection.

[0029] The graphite crucible is divided into two layers: the upper layer is the crucible ring 1, and the lower layer is the crucible body 2. The crucible body 2 is tightly connected to the crucible ring 1. When the graphite crucible is used for a long time, it can prevent the graphite crucible from cracking and widening, thereby improving the crystal pulling quality and maintaining the stability of the process.

[0030] At least one vent hole 203 is provided on the crucible body 2. The vent holes 203 are located on the side wall of the crucible body 2. There are two vent holes 203, which are symmetrically arranged along the axis of the crucible body 2. The two vent holes 203 can be respectively opened on the first crucible block 201 and the second crucible block 202. In this utility model, the vent holes are arranged as follows: the splicing surface of the first crucible block 201 has a first groove 2011, which is located near the top of the crucible body 2. The splicing surface of the second crucible block 202 has a second groove 2021 corresponding to the first groove 2011, which is also located near the top of the crucible body 2. The first groove 2011 and the second groove 2021 are both semi-circular. The first groove 2011 and the second groove 2021 can be spliced ​​to form the vent hole 203, which is used for the gas inside the crucible body 2 to flow out of the crucible body 2.

[0031] Multiple grooves 3 are provided on the inner wall of the crucible body 2 along the axial direction of the crucible body 2. In this utility model, there are four grooves 3, which are semi-circular in shape, and the distance between each pair of adjacent grooves 3 is equal. From the top to the bottom of the crucible body 2, the circumference of the four grooves 3 decreases sequentially. In this embodiment, two exhaust holes 203 are opened in the uppermost groove 3. The groove 3 can first guide the gas generated by the reaction between the graphite crucible and the quartz crucible, and finally guide it to the exhaust hole 203 on the crucible body 2 for discharge, thereby reducing the wear of the R-angle by the reaction gas and increasing the service life of the graphite crucible.

[0032] The above are the basic embodiments of this utility model invention. Further improvements, optimizations, and limitations can be made based on the above to obtain the following embodiments:

[0033] Example 2

[0034] This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 5 , Figure 7 As shown, the inner wall of the crucible body 2 is provided with guide grooves 204 corresponding to the vent holes 203 one-to-one; that is, there are two guide grooves, and the guide grooves 204 are elongated grooves that extend along the axial direction of the crucible body 2, so that all grooves 3 are connected to the guide grooves 204. The vent holes 203 are located at the top of the guide grooves 204 and are connected to the guide grooves 203. Gas flows along the grooves 3 into the guide grooves 204, and is guided by the guide grooves 204 to the vent holes 203 for discharge. The design of the guide grooves 204 avoids the need to open vent holes 203 on each groove 3, reduces the number of vent holes 203, and allows the gas inside the graphite crucible to be discharged smoothly without reducing the heat preservation performance of the graphite crucible.

[0035] In this embodiment, the guide groove 204 is configured as follows: a third groove 2012 is formed on the inner wall of the first crucible block 201, and the third groove 2012 is located at the splicing point of the first crucible block 201; a fourth groove 2022 corresponding to the third groove 2012 is formed on the inner wall of the second crucible block 202, and the fourth groove 2022 is located at the splicing point of the second crucible block 202; the cross-section of the third groove 2012 and the fourth groove 2022 are both L-shaped, and the third groove 2012 and the fourth groove 2022 can be spliced ​​to form a guide groove 204 corresponding one-to-one with the exhaust hole 203.

[0036] Example 3

[0037] This embodiment is an improvement on Embodiment 1. Its main structure is the same as Embodiment 1, but the improvement lies in the following: During the pulling process of heavily doped crystal rods, the top edge of the graphite crucible is prone to chipping and peeling, which can cause the carbon content of the entire batch of crystal rods to exceed the standard, ultimately leading to the scrapping of the crystal rods. Therefore, if... Figure 3 , Figure 6 As shown, the top of the crucible ring 1 is a convex arc surface, which can reduce stress concentration and airflow erosion at the top and prevent the top edge of the crucible ring 1 from chipping and peeling.

[0038] Example 4

[0039] This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 3 , Figure 6 As shown, the outer side of the top of the crucible ring 1 has a conical surface, with the large diameter end facing down and the small diameter end facing up. This can reduce stress concentration at the top and airflow erosion, and prevent the top edge of the crucible ring 1 from chipping and peeling.

[0040] Example 5

[0041] This example is an improvement on Example 1. Its main structure is the same as Example 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 4 As shown, the bottom ends of the first crucible block 201 and the second crucible block 202 are both provided with downwardly extending mounting blocks 401. The maximum width of the mounting blocks 401 is less than the inner diameter of the crucible body 2. When the splicing surfaces of the first crucible block 201 and the second crucible block 202 are aligned and fitted together, the two mounting blocks 401 are also joined together to form a cylindrical plug 4. By setting the cylindrical plug 4, the graphite crucible is installed.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A graphite crucible for a Czochralski single crystal furnace, characterized in that: The system includes a first crucible block (201) and a second crucible block (202). The first crucible block (201) and the second crucible block (202) are spliced ​​together to form a circular crucible body (2) with a closed bottom and an open top. A crucible ring (1) extending upward is coaxially provided at the top of the crucible body (2). At least one vent hole (203) is provided on the crucible body (2). Multiple grooves (3) are provided on the inner wall of the crucible body (2) along the axial direction of the crucible body (2). The grooves (3) are connected to the vent hole (203) so that the gas in the graphite crucible is guided through the grooves (3) to the vent hole (203) and flows out.

2. The graphite crucible for a Czochralski single crystal furnace as described in claim 1, characterized in that: The first crucible block (201) has a first groove (2011) on its splicing surface, and the second crucible block (202) has a second groove (2021) corresponding to the first groove (2011) on its splicing surface. The first groove (2011) and the second groove (2021) can be spliced ​​together to form an exhaust hole (203).

3. The graphite crucible for a Czochralski single crystal furnace as described in claim 1, characterized in that: The inner wall of the crucible body (2) is provided with guide grooves (204) that correspond one-to-one with the exhaust holes (203); the guide grooves (204) extend along the axial direction of the crucible body (2) so that all grooves (3) are connected to the guide grooves (204), and the exhaust holes (203) are located at the top of the guide grooves (204) and are connected to the guide grooves (204).

4. The graphite crucible for a Czochralski single crystal furnace as described in claim 3, characterized in that: The inner wall of the first crucible block (201) is provided with a third groove (2012), and the inner wall of the second crucible block (202) is provided with a fourth groove (2022) corresponding to the third groove (2012). The third groove (2012) and the fourth groove (2022) can be spliced ​​together to form a guide channel (204).

5. The graphite crucible for a Czochralski single crystal furnace as described in claim 1, characterized in that: A downwardly extending protrusion (101) is provided around the bottom end of the crucible ring (1); a receiving groove (205) for accommodating the protrusion (101) is provided around the top end of the crucible body (2).

6. The graphite crucible for a Czochralski single crystal furnace as described in claim 1, characterized in that: The top of the crucible ring (1) is a circular arc surface that convexes upwards.

7. The graphite crucible for a Czochralski single crystal furnace as described in claim 1, characterized in that: The outer side of the top of the crucible ring (1) has a conical surface, with the larger diameter end facing down and the smaller diameter end facing up.

8. The graphite crucible for a Czochralski single crystal furnace as described in claim 1, characterized in that: The bottom ends of the first crucible block (201) and the second crucible block (202) are provided with downwardly extending mounting blocks (401), and the two mounting blocks (401) can be spliced ​​together to form a cylindrical plug (4).

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