1. A draft tube, comprising:

the outer guide cylinder is formed by connecting the upper part of the outer guide cylinder and the lower part of the outer guide cylinder at a first joint;

the inner guide cylinder is coaxially arranged with the outer guide cylinder and connected with the outer guide cylinder;

the guide cylinder sleeve is connected with the inner guide cylinder at a second joint and forms a gap with the lower part of the outer guide cylinder;

the first joint and/or the gap are/is arranged to avoid adhesion caused by splashing and filling of the polycrystalline silicon melt.

2. The draft tube of claim 1, wherein a spacer of a set height is disposed in the space of the first joint to increase the size of the space of the first joint.

3. The draft tube of claim 2, wherein the spacer blocks are used to fix the connection between the upper portion of the outer draft tube and the lower portion of the outer draft tube to prevent abrasion between the upper portion of the outer draft tube and the lower portion of the outer draft tube due to sliding.

4. The guide shell according to claim 1, wherein the size of the space at the gap is increased to avoid the adhesion at the gap caused by the splash filling of the polysilicon melt.

5. The pod of claim 4, wherein the pod sleeve is reduced in size to increase the size of the space at the gap.

6. The draft tube of claim 4, wherein the draft tube sleeve extends downwardly away from the lower portion of the outer draft tube to increase the size of the space at the gap.

7. The draft tube of claim 1, wherein said outer draft tube upper portion, said outer draft tube lower portion and said draft tube sleeve are of unitary construction to avoid said first joint and said gap.

8. The draft tube according to any one of claims 1 to 6, wherein a plurality of pairs of ear holes are oppositely formed at the top end of the upper part of the outer draft tube along the radially outward extending position of the draft tube; wherein each pair of ear holes are uniformly distributed at the extending part of the top end of the upper part of the outer guide cylinder.

9. A crystal pulling furnace comprising a draft tube according to any one of claims 1 to 8.

Background

Single crystal silicon rods are mostly produced by the Czochralski (Czochralski) process, otherwise known as the Czochralski process, and the production apparatus usually employed is a crystal puller apparatus.

During the pulling of the single crystal silicon rod, the guide shell parts in the crystal pulling furnace installation play a critical role in providing the temperature gradient required for crystal growth: on one hand, the guide cylinder can provide a higher thermal barrier effect for the crystal bar, so that the crystal heat dissipation is facilitated, and a temperature gradient required by crystal growth is formed to improve the crystal growth speed; on the other hand, the guide cylinder guides argon flow to concentrate near the growth liquid level in the single crystal furnace from top to bottom, so that the cleanliness of the argon flow is maintained, the heat dissipation of the crystal is facilitated, the temperature gradient required by the crystal growth is increased, and the crystal growth speed is improved.

However, in the current drawing process of the single crystal silicon rod, for example, when polycrystalline silicon melt is put into the polycrystalline silicon melt, the phenomenon that the molten polycrystalline silicon melt splashes onto the guide cylinder is very easy to occur, and the polycrystalline silicon melt splashed onto the guide cylinder is gradually increased along with the long-time use of the guide cylinder, so that the phenomenon that each component of the guide cylinder cannot be separated due to the adhesion of the melt is caused, and thus the components in the guide cylinder cannot be independently replaced, so that the use cost of the guide cylinder and the production cost of the single crystal silicon rod are increased, and the economic benefit is reduced.

Disclosure of Invention

In view of the above, embodiments of the present invention are directed to a draft tube and a crystal pulling furnace; the use cost of the guide shell and the production cost of the single crystal silicon rod can be reduced.

The technical scheme of the embodiment of the invention is realized as follows:

in a first aspect, an embodiment of the present invention provides a guide shell, where the guide shell includes:

the outer guide cylinder is formed by connecting the upper part of the outer guide cylinder and the lower part of the outer guide cylinder at a first joint;

the inner guide cylinder is coaxially arranged with the outer guide cylinder and connected with the outer guide cylinder;

the guide cylinder sleeve is connected with the inner guide cylinder at a second joint and forms a gap with the lower part of the outer guide cylinder;

the first joint and/or the gap are/is arranged to avoid adhesion caused by splashing and filling of the polycrystalline silicon melt.

In a second aspect, embodiments of the present invention provide a crystal pulling furnace, which includes the guide shell of the first aspect.

The embodiment of the invention provides a guide cylinder and a crystal pulling furnace; in order to reduce the problem that components of the guide cylinder cannot be separated due to adhesion formed by filling splashed polycrystalline silicon melt, the space size of a component combination position (such as a first joint and a gap position) where the components are easy to adhere in the combination process is set, so that the phenomenon that the polycrystalline silicon melt is splashed and filled to cause adhesion is avoided, the components of the guide cylinder can be easily separated to realize independent replacement, and the use cost of the guide cylinder and the production cost of a single crystal silicon rod are reduced.

Drawings

FIG. 1 is a schematic view of an exemplary crystal puller used to produce a single crystal silicon ingot using the Czochralski method;

fig. 2 is a cross-sectional view of a structure of a guide shell according to an embodiment of the present invention;

FIG. 3 is an enlarged schematic view of a first joint provided by an embodiment of the present invention;

fig. 4 is a schematic top view of an outer baffle according to an embodiment of the present invention;

FIG. 5 is an enlarged view of a gap provided in an embodiment of the present invention;

FIG. 6 is a schematic diagram of an integrated structure according to an embodiment of the present invention;

fig. 7 is a schematic top view of an upper portion of an outer guide shell according to an embodiment of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Referring to FIG. 1, there is shown a schematic view of an exemplary crystal pulling furnace 1 used for producing a single crystal silicon ingot by the Czochralski method, in the crystal pulling furnace 1 shown in FIG. 1, at least: a furnace body 10, a guide cylinder 11, a quartz crucible 12 for holding polysilicon raw material (or referred to as polysilicon melt), and a mechanical part 13 for driving the quartz crucible 12 to move and rotate, and further, a heater 14 for heating the polysilicon raw material to form a polysilicon melt 2, a bottom heat insulating material 15 disposed at the bottom end of the furnace body 10, and an exhaust port pipe 16, wherein the exhaust direction of the exhaust port pipe 16 is indicated by an arrow in fig. 1; it should be noted that the structure of the single crystal furnace 1 shown in fig. 1 is not particularly limited, and other parts of the crystal pulling furnace 1, such as a central heat insulating material shown as a cross-fill block around the heater 14, are not marked for clarity of explanation of the embodiments of the present invention and are therefore omitted.

The process for producing single crystal silicon by the crystal pulling furnace 1 shown in FIG. 1 may include charging a polycrystalline silicon feedstock through a draft tube 11 within a quartz crucible 12; then heating the polycrystalline silicon raw material 2 in the quartz crucible 12 by a heater 14 to melt the polycrystalline silicon raw material to form polycrystalline silicon melt; when the temperature of the polysilicon melt 2 is stable, the polysilicon rod grows into a single crystal silicon rod by contacting the seed crystal with the polysilicon melt.

In the process of producing the single crystal silicon rod, a polycrystalline silicon melt is generally added to the polycrystalline silicon melt 2 in the quartz crucible 12, and at this time, the polycrystalline silicon melt dropped into the quartz crucible 12 is likely to cause splashing of the polycrystalline silicon melt 2, and is likely to splash onto the guide cylinder 11 in the crystal pulling furnace 1 which is closest to the quartz crucible 12. Generally speaking, the draft tube 11 usually comprises a plurality of components, and along with the long-time use of draft tube, the polycrystalline silicon melt that splashes to on the draft tube 11 increases gradually, leads to appearing the melt adhesion and can't separate each subassembly of draft tube to can't change alone the subassembly in the draft tube, cause draft tube use cost and the manufacturing cost of monocrystalline silicon rod to increase, economic benefits reduces.

In order to avoid the phenomenon of melt adhesion, the embodiment of the invention is expected to improve the structure of the guide shell 11 in the crystal pulling furnace 1 shown in FIG. 1. As shown in fig. 2, which is a structural cross-sectional view of the guide shell 11, the guide shell 11 may include: an outer diaphragm 21 formed by joining an outer diaphragm upper part 211 and an outer diaphragm lower part 212 at a first joint 3 as shown by a solid coil;

an inner guide cylinder 22 coaxially arranged with the outer guide cylinder 21 and connected thereto;

a guide shell sleeve 23 joined to the inner guide shell 22 at a second junction 4 and forming a gap 5 with the outer guide shell lower portion 212 as indicated by the dashed circle;

the space size of the first joint 3 and/or the gap 5 is set to avoid the adhesion caused by the splashing filling of the polysilicon melt.

In some examples, outer guide shell 21 and inner guide shell 22 form a cavity via the connection, and the cavity is filled with insulation material 24.

For the structure of the guide cylinder 11 shown in fig. 2, in order to reduce the problem that the components of the guide cylinder 11 in fig. 2 cannot be separated due to adhesion caused by the fact that the splashed polysilicon melt 2 is filled up and adhered, the spatial size of the component combination positions (such as the first joint 3 and the gap 5) where the components are easy to adhere in the combination process is set, so that adhesion caused by splashing and filling of the polysilicon melt is avoided, the components of the guide cylinder 11 can be easily separated to realize individual replacement, and the use cost of the guide cylinder and the production cost of the single crystal silicon rod are reduced.

In some possible implementations, the embodiment of the present invention is expected to reduce the probability of being filled with the splashed polysilicon melt 2 to avoid the occurrence of the adhesion by increasing the size of the space where the components of the guide shell 11 are combined.

Based on this, in some examples, a spacer 6 with a set height is arranged in the space 31 of the first joint 3 to increase the size of the space 31 of the first joint 3. For this example, referring to the enlarged schematic view of the first joint 3 shown in fig. 3, generally speaking, in a conventional guide cylinder structure, the upper outer guide cylinder part 211 and the lower outer guide cylinder part 212 are generally joined in a close fit manner, but at this time, the space 31 of the first joint 3 is small in size and is easily filled with splashed polysilicon melt 2 to cause adhesion between the upper outer guide cylinder part 211 and the lower outer guide cylinder part 212; in order to avoid this phenomenon, the embodiment of the present invention adopts the spacer 6 with a certain height in the space 31 to increase the size of the space 31 properly, so that the space 31 is less likely to be filled with the polysilicon melt 2 to form adhesion. Furthermore, for this example, the spacer 6 may function like a snap in addition to increasing the size of the space 31, i.e. the spacer 6 may also be used to fix the connection between the outer guide shell upper part 211 and the outer guide shell lower part 212 to avoid wear between the outer guide shell upper part 211 and the outer guide shell lower part 212 due to sliding. It can be understood that, as shown in fig. 4, which is a schematic top view of the outer guide shell 21, in the embodiment of the present invention, preferably, a spacer block 6 is respectively disposed at four positions of the bottom of the outer guide shell 21, and an included angle between adjacent spacer blocks 6 is 90 degrees, so as to achieve a fixed connection between the outer guide shell upper portion 211 and the outer guide shell lower portion 212.

In other examples, embodiments of the present invention increase the spatial dimension of the gap 5 to increase the spatial dimension of the assembly of the guide shell 11. For this example, referring to the enlarged schematic view of the gap 5 shown in fig. 5, the size of the space 51 of the gap 5 may be increased to a degree that prevents the polycrystalline silicon melt 2 from being splashed and filled to cause adhesion at the gap 5.

For the above example, the guide shell sleeve 23 may preferably be reduced in size to increase the size of the space 51 at the gap.

For the above example, the guide shell sleeve 23 may be extended downward away from the outer guide shell lower portion 212 to increase the size of the space 52 at the gap, preferably as indicated by the solid black arrows in fig. 2.

In addition to the above-described embodiments and the examples thereof, in some possible embodiments, the adhesion can be avoided by avoiding the creation of a space at the combination of the components of the guide shell 11, which can be filled with the splashed polysilicon melt 2. Based on this, as shown in fig. 6, in some examples, the outer guide shell upper portion 211, the outer guide shell lower portion 212, and the guide shell sleeve 23 may be formed as an integral structure to avoid forming the first joint 3 and the gap 5; it is thus possible to avoid spaces on the guide shell 11 which are filled with the splashed polycrystalline silicon melt 2. However, in this example, since the outer guide tube upper portion 211, the outer guide tube lower portion 212, and the guide tube sleeve 23 are formed as an integral structure, even if the formed integral structure can be easily replaced, the cost of the integral structure is slightly higher than that of each component of the integral structure.

In the structure of the guide shell 11 explained in the foregoing implementation manner and examples, the guide shell 11 needs to be suspended through ear holes when in use, and in the conventional guide shell structure, two opposite ear holes are usually arranged at the top end of the upper portion of the outer guide shell 211, but if a certain ear hole is damaged, the guide shell 11 cannot be suspended integrally, so that the guide shell can be used only by replacing the upper portion 211 of the outer guide shell, thereby increasing the use cost. Based on this, in some examples, as shown in fig. 1, a plurality of pairs of ear holes 7 may be oppositely formed at the top end of the upper outer guide shell 211 extending outward in the radial direction of the guide shell 11; wherein each pair of ear holes 7 is uniformly distributed at the extending position of the top end of the upper part of the outer guide cylinder. For example, as shown in the schematic top view of the upper part 211 of the outer guide shell in fig. 7, preferably, four pairs of ear holes may be formed at the extending position of the upper part 211 of the outer guide shell, and the included angle between each pair of ear holes is 90 °; when a certain ear hole is damaged, the other two ear holes are replaced to hang the guide shell 11, the preferred scheme is easy to operate and can be realized, the positive effect on the production of the silicon single crystal rod is achieved, the production cost and the manufacturing cost are saved, and the economic benefit is improved.

It should be noted that: the technical schemes described in the embodiments of the present invention can be combined arbitrarily without conflict.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.