Method for reducing oxygen content of monocrystalline silicon
By introducing hydrogen into the monocrystalline silicon production process to react with oxygen and generate water vapor, the problem of high oxygen content in monocrystalline silicon wafers is solved, resulting in reduced defects and lower costs.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- JIANGSU XIEXIN SILICON MATERIAL TECH DEV
- Filing Date
- 2025-06-30
- Publication Date
- 2026-07-09
AI Technical Summary
In existing technologies, the oxygen content in the production process of monocrystalline silicon is relatively high, which leads to defects such as concentric circles and black chips in monocrystalline silicon wafers, affecting efficiency and service life, and increasing manufacturing costs.
Hydrogen is introduced into the furnace at some stage of the crystal pulling, necking, shoulder formation, and shoulder turning processes. It neutralizes the oxygen in the furnace to generate water vapor, reducing the oxygen content. The hydrogen supply is stopped at a certain length to control the amount of hydrogen and reduce costs.
It effectively reduces concentric circle and black chip defects in monocrystalline silicon wafers, improves the efficiency and lifespan of monocrystalline silicon wafers, and reduces manufacturing costs.
Smart Images
Figure CN2025105338_09072026_PF_FP_ABST
Abstract
Description
Methods to reduce the silicon oxygen content of monocrystalline silicon
[0001] Cross-references to related applications
[0002] This application is based on and claims priority to Chinese Patent Application No. 202411977500.0, filed on December 30, 2024, the entire contents of which are incorporated herein by reference. Technical Field
[0003] This application relates primarily to the field of monocrystalline silicon preparation technology, and in particular to a method for reducing the oxygen content of monocrystalline silicon. Background Technology
[0004] In existing technologies, the oxygen content is high during the production of monocrystalline silicon, which makes monocrystalline silicon wafers prone to defects such as concentric circles and black chips, affecting the efficiency and lifespan of the monocrystalline silicon wafers.
[0005] Application content
[0006] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes a method for reducing the oxygen content in monocrystalline silicon. This method can reduce the oxygen content in the furnace, avoid the formation of defects such as concentric circles and black chips in the monocrystalline silicon wafers produced, avoid affecting the efficiency and service life of the monocrystalline silicon wafers, and reduce the manufacturing cost of monocrystalline silicon.
[0007] The method for reducing the silicon-oxygen content of single crystals according to embodiments of this application includes: introducing hydrogen gas into the furnace at one of the following stages: crystal pulling stage, necking stage, shoulder forming stage, and shoulder turning stage; confirming that the length of the constant diameter section of the crystal rod reaches L1; and stopping the introduction of hydrogen gas.
[0008] According to the method for reducing the oxygen content of monocrystalline silicon according to embodiments of this application, hydrogen gas is introduced into the furnace at one of the following stages: the crystal pulling stage, the necking stage, the shoulder formation stage, and the shoulder turning stage; and the hydrogen gas is stopped after confirming that the length of the constant diameter section of the crystal rod reaches L1. Hydrogen gas can neutralize the oxygen in the furnace and generate water vapor at high temperatures, reducing the oxygen content in the furnace and preventing defects such as concentric circles and black chips from forming in the monocrystalline silicon wafers produced, thus avoiding affecting the efficiency and lifespan of the monocrystalline silicon wafers. Furthermore, when the constant diameter section reaches L1, the oxygen content in the furnace is already low, and the hydrogen gas supply can be stopped, reducing the amount of hydrogen introduced and lowering the manufacturing cost of monocrystalline silicon.
[0009] In some embodiments of this application, the total length of the constant diameter segment of the crystal rod is L, and satisfies: 0.225≤L1 / L≤0.275.
[0010] In some embodiments of this application, L1 satisfies 900mm≤L1≤1100mm.
[0011] In some embodiments of this application, a first sensor is provided inside the furnace, and the distance between the first sensor and the crucible is L1. Confirming that the length of the constant diameter section of the crystal rod reaches L1 includes: determining the boundary point between the shoulder stage and the constant diameter stage identified by the first sensor.
[0012] In some embodiments of this application, the method for reducing the silicon-oxygen content of single crystals further includes: confirming that the length of the constant diameter section of the crystal rod reaches L2; and restarting the introduction of hydrogen into the furnace.
[0013] In some embodiments of this application, the total length of the constant diameter segment of the crystal rod is L, and satisfies: 0.9≤L² / L≤0.95.
[0014] In some embodiments of this application, L2 satisfies 3800mm≤L2≤4000mm.
[0015] In some embodiments of this application, when the length of the equal-diameter section is less than L1, the crystal pulling speed of the equal-diameter section is V1; when the length of the equal-diameter section is greater than or equal to L1, the crystal pulling speed of the equal-diameter section is V2, and V1 is satisfied. <V2。
[0016] In some embodiments of this application, the crystal pulling speed during the crystal pulling stage is V, and satisfies: 2*V1≤V≤3*V1; 2*V2≤V≤3*V2.
[0017] In some embodiments of this application, a second sensor is provided inside the furnace, and the distance between the second sensor and the crucible is L2. Confirming that the length of the constant diameter section of the crystal rod reaches L2 includes: determining the boundary point between the shoulder stage and the constant diameter stage identified by the second sensor.
[0018] In some embodiments of this application, the method for reducing the silicon-oxygen content of single crystals further includes: confirming that the crystal rod has entered the final stage and the diameter of the crystal rod has begun to decrease; and stopping the introduction of hydrogen gas.
[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0021] Figure 1 is a flowchart of a method for reducing the silicon oxide content of monocrystalline silicon according to an embodiment of this application. Detailed Implementation
[0022] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0023] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.
[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0025] The method for reducing the silicon oxide content of monocrystalline silicon according to an embodiment of this application is described below with reference to FIG1.
[0026] As shown in Figure 1, the method for reducing the oxygen content of monocrystalline silicon according to an embodiment of this application is used to prepare monocrystalline silicon.
[0027] Specifically, hydrogen is introduced into the furnace at one of the following stages: crystal pulling, necking, shoulder formation, and shoulder turning. This hydrogen neutralizes the oxygen in the furnace and generates water vapor at high temperatures, reducing the oxygen content and preventing defects such as concentric circles and black chips from forming on the monocrystalline silicon wafers, thus avoiding affecting the efficiency and lifespan of the monocrystalline silicon wafers.
[0028] It is understood that the constant diameter section of the crystal rod reaches L1, which means that in the process of producing crystal rods by the Czochralski method, monocrystalline silicon enters the constant diameter section after the crystal pulling stage, necking stage, shoulder forming stage and shoulder turning stage. The constant diameter section is used to cut monocrystalline silicon wafers.
[0029] Stopping the supply of hydrogen means continuously supplying hydrogen until the length of the constant diameter section reaches L1. The hydrogen continuously combines with oxygen, reducing the oxygen content in the furnace. When the constant diameter section reaches L1, the oxygen content in the furnace is already low, and the supply of hydrogen can be stopped. This reduces the amount of hydrogen supplied and decreases the manufacturing cost of monocrystalline silicon.
[0030] According to the method for reducing the oxygen content of monocrystalline silicon according to embodiments of this application, hydrogen gas is introduced into the furnace at one of the following stages: the crystal pulling stage, the necking stage, the shoulder formation stage, and the shoulder turning stage; and the hydrogen gas is stopped after confirming that the length of the constant diameter section of the crystal rod reaches L1. Hydrogen gas can neutralize the oxygen in the furnace and generate water vapor at high temperatures, reducing the oxygen content in the furnace and preventing defects such as concentric circles and black chips from forming in the monocrystalline silicon wafers produced, thus avoiding affecting the efficiency and lifespan of the monocrystalline silicon wafers. Furthermore, when the constant diameter section reaches L1, the oxygen content in the furnace is already low, and the hydrogen gas supply can be stopped, reducing the amount of hydrogen introduced and lowering the manufacturing cost of monocrystalline silicon.
[0031] In this embodiment, silicon and a small amount of antimony are added to the crucible inside the furnace and melted together before Czochralski crystal pulling. This allows the antimony to be evenly distributed in the silicon melt, maintaining a stable resistivity and achieving precise resistivity control. This improves the quality of the monocrystalline silicon for use in the later stages of photovoltaic cell manufacturing. Furthermore, the combination of hydrogen and oxygen reduces the oxygen content in the furnace, thus reducing the production of toxic antimony oxides and lowering the risk of antimony oxide poisoning. At this point, the monocrystalline silicon is N-type, used to manufacture N-type monocrystalline silicon wafers.
[0032] In some embodiments of this application, the total length of the constant-diameter section of the crystal ingot is L, and satisfies: 0.225 ≤ L1 / L ≤ 0.275. It is understood that the ratio of L1 to L can be 0.225, 0.23, 0.235, 0.24, 0.245, 0.25, 0.255, 0.26, 0.265, 0.27, or 0.275. A ratio between the hydrogen inlet stop point L1 and the total length L of the constant-diameter section of the crystal ingot is not less than 0.225. This avoids the proportion of the hydrogen-introduced portion of the constant-diameter section being too small, preventing defects such as concentric circles and black chips in the produced monocrystalline silicon wafers. A ratio between the hydrogen inlet stop point L1 and the total length L of the constant-diameter section of the crystal ingot is not greater than 0.275. This avoids the hydrogen-introduced portion of the constant-diameter section being too long, reducing the amount of hydrogen introduced and lowering the manufacturing cost of monocrystalline silicon.
[0033] In some embodiments of this application, L1 satisfies 900mm ≤ L1 ≤ 1100mm. It is understood that L1 can be 900mm, 910mm, 920mm, 930mm, 940mm, 950mm, 960mm, 970mm, 980mm, 990mm, 1000mm, 1010mm, 1020mm, 1030mm, 1040mm, 1050mm, 1060mm, 1070mm, 1080mm, 1090mm, or 1100mm. A L1 not less than 900mm avoids the hydrogen-introducing portion of the equal-diameter section being too small, preventing defects such as concentric circles and black chips in the produced monocrystalline silicon wafers. A L1 not greater than 1100mm avoids the hydrogen-introducing portion of the equal-diameter section being too long, reducing the amount of hydrogen introduced and lowering the manufacturing cost of monocrystalline silicon.
[0034] In some embodiments of this application, a first sensor is installed inside the furnace, and the distance between the first sensor and the crucible is L1. Confirming that the length of the constant-diameter section of the crystal rod reaches L1 includes: determining the boundary point between the shoulder-turning stage and the constant-diameter stage identified by the first sensor. It is understood that when the first sensor identifies the boundary point between the shoulder-turning stage and the constant-diameter stage, the distance between the boundary point and the crucible is L1, and the length of the constant-diameter section reaches L1. At this point, it is relatively convenient to confirm that the length of the constant-diameter section of the crystal rod has reached L1, facilitating the operation of stopping the hydrogen gas supply and increasing the reliability of the method for reducing the silicon-oxygen content of the single crystal.
[0035] In some embodiments of this application, as shown in Figure 1, the method for reducing the oxygen content of monocrystalline silicon further includes: confirming that the length of the constant diameter section of the crystal rod reaches L2, and then restarting the introduction of hydrogen into the furnace. When the length of the constant diameter section of the crystal rod reaches L2 from L1, the oxygen content in the furnace rises again. By restarting the introduction of hydrogen into the furnace, the oxygen content in the furnace can be reduced, avoiding a high oxygen content. Hydrogen can neutralize the oxygen in the furnace and generate water vapor at high temperatures, reducing the oxygen content in the furnace and preventing defects such as concentric circles and black chips from being produced in the monocrystalline silicon wafers, which would affect the efficiency and lifespan of the monocrystalline silicon wafers.
[0036] In some embodiments of the present application, the total length of the equal-diameter section of the ingot is L, and it satisfies: 0.9 ≤ L2 / L ≤ 0.95. It can be understood that the ratio of L2 to L can be 0.9, 0.905, 0.91, 0.915, 0.92, 0.925, 0.93, 0.935, 0.94, 0.945, or 0.95. The ratio between the position L2 where hydrogen is re-introduced into the furnace and the total length L of the equal-diameter section of the ingot is not less than 0.9, which can avoid an excessive length of the part of the equal-diameter section where hydrogen is introduced, reduce the amount of hydrogen introduced, and reduce the manufacturing cost of monocrystalline silicon; the ratio between the position L2 where hydrogen is re-introduced into the furnace and the total length L of the equal-diameter section of the ingot is not greater than 0.95, which can avoid an excessively small proportion of the part of the equal-diameter section where hydrogen is re-introduced in the equal-diameter section, and avoid defects such as concentric circles and black chips in the monocrystalline silicon wafers produced from monocrystalline silicon.
[0037] In some embodiments of the present application, L2 satisfies 3800mm ≤ L2 ≤ 4000mm. It can be understood that L2 can be 3800mm, 3810mm, 3820mm, 3830mm, 3840mm, 3850mm, 3860mm, 3870mm, 3880mm, 3890mm, 3900mm, 3910mm, 3920mm, 3930mm, 3940mm, 3950mm, 3960mm, 3970mm, 3980mm, 3990mm, or 4000mm. L2 not being less than 3800mm can avoid an excessive length of the part of the equal-diameter section where hydrogen is introduced, reduce the amount of hydrogen introduced, and reduce the manufacturing cost of monocrystalline silicon; L2 not being greater than 4000mm can avoid an excessively small part of the equal-diameter section where hydrogen is re-introduced, and avoid defects such as concentric circles and black chips in the monocrystalline silicon wafers produced from monocrystalline silicon.
[0038] In some embodiments of the present application, when the length of the equal-diameter section is less than L1, the crystal pulling speed of the equal-diameter section is V1, and when the length of the equal-diameter section is greater than or equal to L1, the crystal pulling speed of the equal-diameter section is V2, and it satisfies V1 < V2. It can be understood that the crystal pulling speed V1 of the equal-diameter section when the length of the equal-diameter section is less than L1 is less than the crystal pulling speed V2 of the equal-diameter section when the length of the equal-diameter section is greater than or equal to L1. When the crystal pulling just enters the equal-diameter section, the diameter of the monocrystalline silicon reaches the maximum, and the crystal pulling speed decreases, making the growth of the crystal more uniform and making the manufacturing process of the ingot more reliable.
[0039] In some embodiments of the present application, the crystal pulling speed in the seed crystal stage is V, and it satisfies: 2*V1 ≤ V ≤ 3*V1; 2*V2 ≤ V ≤ 3*V = 2. It can be understood that the crystal pulling speed in the seed crystal stage is 2 to 3 times the crystal pulling speed of the equal-diameter section. The diameter of the ingot in the seed crystal stage is smaller, and the crystal pulling speed in the seed crystal stage is faster, which can accelerate the process of ingot manufacturing and reduce the manufacturing cost of crystal pulling.
[0040] In addition, under normal circumstances, the heating power inside the furnace continuously decreases, and the heating power may be adjusted according to the conditions inside the furnace to meet the processing requirements of the crystal rods.
[0041] In some embodiments of this application, a second sensor is installed inside the furnace, with a distance of L2 between the second sensor and the crucible. Confirming that the length of the constant-diameter section of the crystal rod reaches L2 includes determining the boundary point between the shoulder-turning stage and the constant-diameter stage identified by the second sensor. It is understood that when the second sensor identifies the boundary point between the shoulder-turning stage and the constant-diameter stage, the distance between the boundary point and the crucible is L2, and the length of the constant-diameter section reaches L2. At this point, it is relatively convenient to confirm that the length of the constant-diameter section of the crystal rod has reached L2, facilitating the re-introduction of hydrogen gas and increasing the reliability of the method for reducing the silicon-oxygen content of single crystals.
[0042] In some embodiments of this application, as shown in Figure 1, the method for reducing the silicon oxygen content of monocrystalline silicon further includes: confirming that the crystal rod has entered the finishing stage and the diameter of the crystal rod begins to decrease; and stopping the introduction of hydrogen gas. The crystal rod in the finishing stage does not need to be cut into monocrystalline silicon wafers. Stopping the introduction of hydrogen gas at this time avoids the formation of defects such as concentric circles and black chips in the monocrystalline silicon wafers, thus avoiding affecting the efficiency and service life of the monocrystalline silicon wafers.
[0043] In this embodiment, the hydrogen flow rate is 2-10 L / min, which avoids excessive hydrogen flow and waste, and also reduces the oxygen content of monocrystalline silicon, thus preventing defects such as concentric circles and black chips from being produced in monocrystalline silicon wafers, and avoiding affecting the efficiency and lifespan of monocrystalline silicon wafers.
[0044] Other configurations and operations of the method for reducing the silicon oxide content of monocrystalline silicon according to the embodiments of this application are known to those skilled in the art and will not be described in detail here.
[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0046] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.
Claims
1. A method for reducing the silicon-oxygen content of single-crystal silicon, wherein, include: Hydrogen gas is introduced into the furnace at one of the following stages: crystal development stage, necking stage, shoulder formation stage, and shoulder turning stage. Confirm that the length of the constant diameter section of the crystal rod reaches L1; Stop the flow of hydrogen gas.
2. The method for reducing the silicon-oxygen content of monocrystalline silicon according to claim 1, wherein, The total length of the constant diameter section of the crystal rod is L, and satisfies: 0.225≤L1 / L≤0.
275.
3. The method for reducing the silicon-oxygen content of monocrystalline silicon according to any one of claims 1-2, wherein, L1 satisfies 900mm≤L1≤1100mm.
4. The method for reducing the silicon-oxygen content of monocrystalline silicon according to any one of claims 1-3, wherein, A first sensor is installed inside the furnace, and the distance between the first sensor and the crucible is L1. Confirming that the length of the constant-diameter section of the crystal rod reaches L1 includes: The boundary point between the shoulder turning stage and the constant diameter stage is determined by the first sensor.
5. The method for reducing the silicon-oxygen content of monocrystalline silicon according to any one of claims 1-4, wherein, Also includes: Confirm that the length of the constant diameter section of the crystal rod reaches L2; Hydrogen gas was introduced into the furnace again.
6. The method for reducing the silicon-oxygen content of monocrystalline silicon according to claim 5, wherein, The total length of the constant diameter section of the crystal rod is L, and satisfies: 0.9≤L² / L≤0.
95.
7. The method for reducing the silicon-oxygen content of single crystals according to claim 5, wherein, L2 satisfies 3800mm≤L2≤4000mm.
8. The method for reducing the silicon-oxygen content of monocrystalline silicon according to claim 5, wherein, When the length of the constant-diameter section is less than L1, the crystal pulling speed of the constant-diameter section is V1. When the length of the constant-diameter section is greater than or equal to L1, the crystal pulling speed of the constant-diameter section is V2, and V1 is satisfied. <V2。 9. The method for reducing the silicon-oxygen content of single crystals according to claim 8, wherein, The crystal pulling speed during the crystal pulling stage is V, and satisfies: 2*V1≤V≤3*V1; 2*V2≤V≤3*V2.
10. The method for reducing the silicon-oxygen content of monocrystalline silicon according to claim 5, wherein, A second sensor is installed inside the furnace, and the distance between the second sensor and the crucible is L2. Confirming that the length of the constant-diameter section of the crystal rod reaches L2 includes: Determine the boundary point between the shoulder turning stage and the constant diameter stage identified by the second sensor.
11. The method for reducing the silicon-oxygen content of monocrystalline silicon according to claim 5, wherein, Also includes: Once the crystal rod has entered the final stage, its diameter begins to decrease. Stop the flow of hydrogen gas.