Seed crystal, method for preparing single crystal silicon by Czochralski method and single crystal silicon

Abstract

The present invention discloses a method for preparing single crystal silicon by seed crystal and Czochralski method and single crystal silicon, wherein holes are provided on the seed crystal, and the holes can store dopants. Thus, the seed crystal can ensure that the dopants are completely added to the molten silicon, which not only effectively avoids the problem of low product yield caused by the dopants adhering to the wall of the quartz tube and the dopants being taken away by the argon gas in the furnace body, but also reduces the probability of arcing at the electrode pins for the bottom-drawing crystal growth furnace, and reduces the number of argon gas filling and extraction times, saving production time.

Description

Technical Field

[0001] The present invention belongs to the field of single crystal silicon, and specifically, the present invention relates to a seed crystal, a method for preparing single crystal silicon by a Czochralski method, and single crystal silicon. Background Art

[0002] During the growth of single crystals, various dopants need to be added, including III and V group dopants, quartz crucible improvers, silicides or nitrides, etc. In the traditional single crystal pulling process, dopants are generally placed in a quartz crucible together with raw materials for growth. With the development of RCZ (multiple charging crystal pulling) and CCZ (continuous straight crystal pulling) technologies, multiple feeding is required during the single crystal pulling process, and dopants need to be added again each time the feeding is re-added.

[0003] The current method of adding dopants is to add dopants into the melt by means of an external or internal quartz tube. However, the dopants are often too light, do not roll well or stick to the wall of the quartz tube, so that the dopants are not completely added to the melt, resulting in incorrect resistivity, quartz crucible modifier or nitrogen atomic concentration of the obtained single crystal silicon, which seriously affects the production yield. In addition, when changing to an internal feeding quartz tube, argon gas needs to be pumped out, and when changing back to a seed crystal, argon gas needs to be pumped out again, which increases production time.

[0004] In addition, regardless of whether external or internal quartz tubes are used to add various dopants, the dopants are easily blown away by the argon gas in the furnace. For crystal growth furnaces with downward exhaust, arcing often occurs near the heater electrode pins. In severe cases, the electrode pins may be damaged, causing the addition to end prematurely.

[0005] Therefore, the existing method of adding dopants in the process of preparing single crystal silicon needs to be improved. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present invention is to provide a method for preparing single crystal silicon by seed crystal and Czochralski method and single crystal silicon, wherein the seed crystal can ensure that dopants are completely added to the molten silicon, which not only effectively avoids the problem of low product yield caused by dopants adhering to the wall of the quartz tube and dopants being carried away by argon gas in the furnace body, but also reduces the probability of arcing at the electrode pins for the bottom-drawing crystal growth furnace, while reducing the number of argon gas filling and extraction times, saving production time.

[0007] In one aspect of the present invention, the present invention provides a seed crystal. According to an embodiment of the present invention, the seed crystal is provided with holes, and the holes can store dopants.

[0008] Therefore, the seed crystal of the embodiment of the present invention is provided with holes, and the holes can store dopants. In the process of preparing single crystal silicon by the Czochralski method, the seed crystal is immersed in molten silicon, and the dopants filled in the holes are mixed with the molten silicon. Then, the seed crystal is pulled directly to prepare doped single crystal silicon. Compared with the existing method of adding dopants by external or internal quartz tubes, the seed crystal of the present application can ensure that the dopants are completely added to the molten silicon, which not only effectively avoids the problem of low product yield caused by dopants adhering to the wall of the quartz tube and dopants being carried away by the argon gas in the furnace body, but also reduces the probability of arcing at the electrode feet for the bottom-drawn crystal growth furnace, while reducing the number of argon gas filling and extraction times, saving production time.

[0009] In addition, the seed crystal according to the above embodiment of the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, the holes are filled with silicon-based materials. Thus, in the process of preparing doped single-crystal silicon by pulling a seed crystal, the seed crystal is immersed in molten silicon, the silicon-based material melts and the holes on the seed crystal are opened, thereby mixing the dopant with the molten silicon.

[0011] In some embodiments of the present invention, the hole is located at the lower part of the seed crystal, so that the dopant and the molten silicon can be mixed by simply immersing the lower part of the seed crystal into the molten silicon.

[0012] In some embodiments of the present invention, the seed crystal includes a plurality of holes, and the plurality of holes are arranged at intervals along the length direction of the seed crystal, thereby ensuring that the dopant is uniformly mixed with the molten silicon.

[0013] In some embodiments of the present invention, the seed crystal includes 1 to 6 holes, thereby ensuring that the dopant and the molten silicon are uniformly mixed.

[0014] In some embodiments of the present invention, the diameter of the hole is 8 to 15 mm. Thus, it can be ensured that the dopant and the molten silicon are evenly mixed.

[0015] In some embodiments of the present invention, the depth of the hole is 8 to 15 mm, thereby ensuring that the dopant and the molten silicon are uniformly mixed.

[0016] In some embodiments of the present invention, the distance between two adjacent holes is 10-20 mm, thereby ensuring that the dopant and the molten silicon are evenly mixed.

[0017] In some embodiments of the present invention, the seed crystal region between two adjacent holes is a narrow neck, thereby making it easier for operators to identify the position.

[0018] In some embodiments of the present invention, the hole is provided with threads, thereby facilitating the closing of the hole.

[0019] In some embodiments of the present invention, the silicon-based material is a silicon bolt, and the silicon bolt matches the thread, thereby facilitating the filling of the hole.

[0020] In some embodiments of the present invention, the dopant is a solid and powdery substance.

[0021] In some embodiments of the present invention, the dopant is at least one of a silicon-based master alloy, a group III element dopant, a group V element dopant, a quartz modifier, a silicide, and a nitride. Thus, the comprehensive performance of single crystal silicon can be significantly improved.

[0022] In some embodiments of the present invention, the III-group element dopant is at least one of pure boron, pure aluminum, pure gallium, pure indium, and pure thallium, or at least one of a compound of boron, aluminum, gallium, indium, thallium, and silicon or oxygen. Thus, the comprehensive performance of single crystal silicon can be significantly improved.

[0023] In some embodiments of the present invention, the group V element dopant is at least one of pure arsenic, pure phosphorus, pure antimony, pure bismuth, or at least one of compounds of arsenic, phosphorus, antimony, bismuth and silicon or oxygen. Thus, the comprehensive performance of single crystal silicon can be significantly improved.

[0024] In some embodiments of the present invention, the quartz modifier is at least one of strontium or barium compounds, thereby significantly improving the comprehensive performance of single crystal silicon.

[0025] In some embodiments of the present invention, the nitride is silicon nitride, thereby significantly improving the comprehensive performance of single crystal silicon.

[0026] In another aspect of the present invention, the present invention provides a method for preparing single crystal silicon by Czochralski method. According to an embodiment of the present invention, the method comprises:

[0027] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0028] (2) immersing the seed crystal described above into the molten silicon and allowing it to stand;

[0029] (3) CZ-pulling the seed crystal to grow a crystal from the molten silicon to obtain single crystal silicon.

[0030] According to the method for preparing single crystal silicon by the Czochralski method according to an embodiment of the present invention, the seed crystal provided with holes and capable of storing dopants in the holes is adopted, and the seed crystal is immersed in molten silicon during the process of preparing single crystal silicon by the Czochralski method, and the dopants in the holes are mixed with the molten silicon, and then the seed crystal is pulled by the Czochralski method to prepare doped single crystal silicon. Compared with the existing method of adding dopants by external or internal quartz tubes, the method of the present application can ensure that the dopants are completely added to the molten silicon, which not only effectively avoids the problem of low product yield caused by dopants adhering to the wall of the quartz tube and dopants being carried away by the argon gas in the furnace body, but also reduces the probability of arcing at the electrode feet for the bottom-drawn crystal growth furnace, while reducing the number of argon gas filling and extraction times, saving production time.

[0031] In some embodiments of the present invention, in step (2), the portion of the seed crystal having the hole is completely immersed in the molten silicon, thereby ensuring that the dopant is completely mixed with the molten silicon.

[0032] In some embodiments of the present invention, in step (2), the standing time is 1 to 10 minutes, thereby ensuring that the dopant and the molten silicon are completely mixed.

[0033] In a third aspect of the present invention, the present invention provides a single crystal silicon. According to an embodiment of the present invention, the single crystal silicon is prepared by the above-mentioned method. Therefore, the single crystal silicon has an accurate concentration of doping elements, thereby having excellent performance.

[0034] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0036] Figure 1 is a schematic structural diagram of a seed crystal according to an embodiment of the present invention;

[0037] Figure 2 is a schematic structural diagram of a seed crystal according to yet another embodiment of the present invention;

[0038] Figure 3 is a schematic structural diagram of a seed crystal according to yet another embodiment of the present invention;

[0039] Figure 4 is a schematic structural diagram of a seed crystal according to yet another embodiment of the present invention;

[0040] Figure 5 The figure is a schematic flow chart of a method for preparing single crystal silicon by the Czochralski method according to one embodiment of the present invention. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] In one aspect of the present invention, the present invention provides a seed crystal. According to an embodiment of the present invention, reference is made to Figure 1 , a hole 10 is provided on the seed crystal 100, and dopants can be stored in the hole 10. The inventors found that by providing a hole on the seed crystal, the hole can store dopants, and the seed crystal is immersed in molten silicon during the process of preparing single crystal silicon by the Czochralski method, the dopants filled in the hole are mixed with the molten silicon, and then the seed crystal is pulled to prepare doped single crystal silicon. Compared with the existing method of adding dopants by using an external or internal quartz tube, the seed crystal of the present application can ensure that the dopants are completely added to the molten silicon, which not only effectively avoids the problem of low product yield caused by dopants adhering to the wall of the quartz tube and the dopants being taken away by the argon gas in the furnace body, but also reduces the probability of arcing at the electrode pin for the bottom-drawing crystal growth furnace, while reducing the number of argon gas filling and extraction times, saving production time.

[0045] According to one embodiment of the present invention, referring to Figure 2, the hole 10 is filled with a silicon-based material 11. Specifically, when the silicon-based material contacts the molten silicon, the silicon-based material melts at the high temperature of the molten silicon, thereby opening the hole, so that the dopant stored in the hole is mixed with the molten silicon. According to a specific embodiment of the present invention, the dopant can be a solid and powdery substance, so that it can be loaded into the hole on the seed crystal to prevent the dopant from leaking out. Specifically, the dopant is at least one of a silicon-based master alloy, a group III element dopant, a group V element dopant, a quartz modifier, a silicide, and a nitride, wherein the group III element dopant is at least one of pure boron, pure aluminum, pure gallium, pure indium, and pure thallium, or at least one of a compound of boron, aluminum, gallium, indium, thallium and silicon or oxygen, the group V element dopant is at least one of pure arsenic, pure phosphorus, pure antimony, and pure bismuth, or at least one of a compound of arsenic, phosphorus, antimony, bismuth and silicon or oxygen, the quartz modifier is at least one of a compound of strontium or barium, and the nitride is silicon nitride. It should be noted that those skilled in the art can select dopants according to the requirements of single crystal silicon performance.

[0046] According to yet another embodiment of the present invention, Figure 1 , the hole 10 is located at the lower part of the seed crystal 100. Therefore, when adding dopants, only the lower part of the seed crystal needs to be immersed in molten silicon to achieve mixing of the dopants and the molten silicon. Figure 3 The seed crystal 100 may be provided with a plurality of holes 10, and the plurality of holes 10 are spaced apart along the length direction of the seed crystal 100, for example, spaced apart evenly. It should be noted that the plurality of holes 10 may contain the same dopant or different dopants, and those skilled in the art may select according to actual needs.

[0047] According to another embodiment of the present invention, the seed crystal 100 may be provided with 1 to 6 holes, and those skilled in the art may select according to actual needs. For example, 1, 2, 3, 4, 5 or 6 holes may be provided, and each hole may have a diameter of 8 to 15 mm and a depth of 8 to 15 mm.

[0048] According to another embodiment of the present invention, referring to Figure 3 , the spacing between two adjacent holes 10 is 10 to 20 mm. The inventors found that the use of this spacing range can avoid the cracking of seed crystals during processing and save silicon materials. For example, the spacing between two adjacent holes 10 can be 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm.

[0049] According to another embodiment of the present invention, in order to facilitate the operator to identify the hole position and ensure that the hole is completely immersed in the molten silicon, refer to Figure 4The region of the seed crystal 100 between two adjacent holes 10 is adopted as a narrow neck, that is, the diameter of the seed crystal in the narrow neck region is smaller than the diameter of the remaining portion of the seed crystal.

[0050] According to another embodiment of the present invention, the hole 10 may be provided with threads, and the silicon-based material 11 may be a silicon bolt, which matches the thread on the hole. Thus, after the hole is filled with dopants, the hole can be filled and blocked by matching the silicon bolt with the thread to avoid leakage of the dopants. When dopants need to be added, the portion of the seed crystal with the hole is immersed in molten silicon, and the silicon bolt melts under the action of high-temperature molten silicon, thereby opening the hole and allowing the dopants therein to mix with the molten silicon.

[0051] In another aspect of the present invention, the present invention provides a method for preparing single crystal silicon by Czochralski method. Figure 5 , the method comprising:

[0052] S100: Melting polysilicon raw materials

[0053] In this step, the polysilicon raw material is heated in a quartz crucible to be completely melted to obtain molten silicon.

[0054] S200: Immerse the seed crystal in molten silicon and let it stand

[0055] In this step, the seed crystal with holes and dopants stored in the holes is fixed on the seed crystal chuck, and then the lower part of the seed crystal is immersed in molten silicon and left to stand. Under the high temperature of molten silicon, the silicon-based material on the hole melts to open the hole, so that the dopant in the hole is mixed with the molten silicon. Preferably, all the parts of the seed crystal with holes are immersed in molten silicon to ensure that all the dopants loaded in the holes are mixed with the molten silicon. According to a specific embodiment of the present invention, the standing time can be 1 to 10 minutes to ensure that the dopant is evenly mixed with the molten silicon. For example, the standing time is 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

[0056] S300: Czochralski seed crystals to grow crystals from molten silicon

[0057] In this step, a seed crystal is pulled directly by a seed crystal chuck to grow a crystal from the molten silicon, and a single crystal silicon is obtained after necking, shouldering and equal diameter growth stages. It should be noted that the process of pulling the seed crystal directly is a conventional operation in the art and will not be described in detail here.

[0058] According to the method for preparing single crystal silicon by the Czochralski method of the embodiment of the present invention, the seed crystal provided with holes and capable of storing dopants in the holes is used. During the process of preparing single crystal silicon by the Czochralski method, the seed crystal is immersed in molten silicon, the dopants in the holes are mixed with the molten silicon, and then the seed crystal is pulled to prepare doped single crystal silicon. Compared with the existing method of adding dopants by external or internal quartz tubes, the method of the present application can ensure that the dopants are completely added to the molten silicon, which not only effectively avoids the problem of low product yield caused by dopants adhering to the wall of the quartz tube and the dopants being carried away by the argon gas in the furnace body, but also reduces the probability of arcing at the electrode pins for the crystal growth furnace with downward exhaust, and at the same time reduces the number of argon gas filling and extraction, saving production time. It should be noted that the above-mentioned features and advantages described for the seed crystal are also applicable to the method for preparing single crystal silicon by the Czochralski method, and will not be repeated here.

[0059] In the third aspect of the present invention, the present invention provides a single crystal silicon. According to an embodiment of the present invention, the single crystal silicon is prepared by the method described above. As a result, the single crystal silicon has an accurate concentration of doping elements, thereby having excellent performance. It should be noted that the features and advantages described above for the method for preparing single crystal silicon by the Czochralski method are also applicable to the single crystal silicon, and will not be repeated here.

[0060] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0061] Example 1

[0062] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0063] (2) Immerse the seed crystal in molten silicon and let it stand for 1 minute. The seed crystal has 6 holes at the bottom, each of which stores B-Si master alloy. The holes are plugged with silicon bolts, and the distance between adjacent holes is 10 mm.

[0064] (3) Czochralski seed crystals are used to grow crystals from the molten silicon to obtain boron-doped single crystal silicon.

[0065] Example 2

[0066] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0067] (2) Immersing the seed crystal in molten silicon and allowing it to stand for 2 minutes, wherein the lower part of the seed crystal has a hole in which P-Si dopant is stored and the hole is plugged with silicon bolts;

[0068] (3) The seed crystal is directly pulled to grow a crystal from the molten silicon to obtain phosphorus-doped single crystal silicon.

[0069] Example 3

[0070] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0071] (2) immersing the seed crystal in molten silicon and allowing it to stand for 8 minutes, wherein the seed crystal has four holes at the bottom, each of which stores pure antimony dopant, and the holes are filled with silicon bolts, and the distance between adjacent holes is 16 mm;

[0072] (3) The seed crystal is directly pulled to grow a crystal from the molten silicon to obtain antimony-doped single crystal silicon.

[0073] Example 4

[0074] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0075] (2) immersing the seed crystal in molten silicon and allowing it to stand for 6 minutes, wherein the lower part of the seed crystal has three holes, each of which stores pure boron dopant, and the holes are filled with silicon bolts, and the distance between adjacent holes is 14 mm;

[0076] (3) Czochralski seed crystals are used to grow crystals from the molten silicon to obtain boron-doped single crystal silicon.

[0077] Example 5

[0078] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0079] (2) The seed crystal is immersed in molten silicon and allowed to stand for 10 minutes. The seed crystal has five holes at the bottom, each of which stores a quartz modifier (barium carbonate BaCO3) dopant. The holes are filled with silicon bolts, and the distance between adjacent holes is 20 mm.

[0080] (3) The seed crystal is directly pulled to grow a crystal from the molten silicon to obtain doped single crystal silicon.

[0081] Comparative Example 1

[0082] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0083] (2) adding B-Si master alloy into molten silicon through a quartz tube;

[0084] (3) Czochralski seed crystals are used to grow crystals from the molten silicon to obtain boron-doped single crystal silicon.

[0085] Comparative Example 2

[0086] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0087] (2) by adding P-Si dopants into molten silicon;

[0088] (3) The seed crystal is directly pulled to grow a crystal from the molten silicon to obtain phosphorus-doped single crystal silicon.

[0089] Comparative Example 3

[0090] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0091] (2) adding pure antimony dopant to molten silicon through a quartz tube;

[0092] (3) The seed crystal is directly pulled to grow a crystal from the molten silicon to obtain antimony-doped single crystal silicon.

[0093] Comparative Example 4

[0094] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0095] (2) adding pure boron dopant to molten silicon through a quartz tube;

[0096] (3) Czochralski seed crystals are used to grow crystals from the molten silicon to obtain boron-doped single crystal silicon.

[0097] Comparative Example 5

[0098] (1) melting polycrystalline silicon raw materials to obtain molten silicon;

[0099] (2) adding a quartz modifier (barium carbonate BaCO3) dopant to the molten silicon through a quartz tube;

[0100] (3) The seed crystal is directly pulled to grow a crystal from the molten silicon to obtain doped single crystal silicon.

[0101] evaluate:

[0102] The abnormal resistivity rate and arcing percentage of the head end of the single crystal silicon obtained in Examples 1-5 and Comparative Examples 1-5 were evaluated respectively.

[0103] 1. The abnormal rate of the head end resistivity is tested with four probes, referring to GB / T 1551-2009 silicon single crystal resistivity test method. The head end resistivity is normal if it falls within the range of + / -5% of the target resistance value, and the percentage exceeding it is the abnormal rate.

[0104] 2. Arcing percentage: The probability is calculated based on the percentage of heater arcing occurring in one hundred furnaces.

[0105] Table 1 Comparison of single crystal silicon obtained in Examples 1-5 and Comparative Examples 1-5

[0106] Head end resistivity abnormality rate Ignition percentage Example 1 0.53％ --- Example 2 0％ --- Example 3 0.79％ --- Example 4 0.625％ --- Example 5 --- 0％ Comparative Example 1 1.09％ --- Comparative Example 2 1.63％ --- Comparative Example 3 0.97％ --- Comparative Example 4 1.16％ --- Comparative Example 5 --- 48％

[0107] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0108] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A seed crystal, characterized in that: The seed crystal is provided with a hole, in which a dopant is stored, the hole is filled with a silicon-based material, the hole is provided with a thread, the silicon-based material is a silicon bolt, the silicon bolt matches the thread, and the dopant is a solid and powdery substance. The dopant is at least one of the following dopants: silicon-based master alloy, pure boron, pure aluminum, pure gallium, pure indium, pure thallium, compounds of boron, aluminum, gallium, indium, thallium and silicon or oxygen, pure arsenic, pure phosphorus, pure antimony, pure bismuth, compounds of arsenic, phosphorus, antimony, bismuth and silicon or oxygen, compounds of strontium or barium, silicide, silicon nitride.

2. The seed crystal according to claim 1, characterized in that: The hole is located at the lower part of the seed crystal.

3. The seed crystal according to claim 1 or 2, characterized in that: The invention comprises a plurality of holes, wherein the plurality of holes are arranged at intervals on the seed crystal along the length direction thereof.

4. The seed crystal according to claim 3, characterized in that: The invention comprises 1 to 6 holes.

5. The seed crystal according to claim 1, characterized in that: The diameter of the hole is 8 to 15 mm.

6. The seed crystal according to claim 1, characterized in that: The depth of the hole is 8 to 15 mm.

7. The seed crystal according to claim 3, characterized in that: The distance between two adjacent holes is 10 to 20 mm.

8. The seed crystal according to claim 3, characterized in that: The seed crystal region between two adjacent holes is a narrow neck.

9. A method for preparing single crystal silicon by Czochralski method, characterized in that: include: (1) melting polycrystalline silicon raw materials to obtain molten silicon; (2) immersing the seed crystal according to any one of claims 1 to 8 into the molten silicon and allowing it to stand; (3) CZ-pulling the seed crystal to grow a crystal from the molten silicon to obtain single crystal silicon.

10. The method according to claim 9, characterized in that In step (2), the portion of the seed crystal having the holes is completely immersed in the molten silicon.

11. The method according to claim 9 or 10, characterized in that: In step (2), the standing time is 1 to 10 minutes.

12. A single crystal silicon, characterized in that: The single crystal silicon is prepared by the method according to any one of claims 9 to 11.

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