Method for producing single crystal silicon

Abstract

The present invention provides a method for producing single crystal silicon, comprising: forming a silicon liquid in a crucible, wherein the silicon liquid comprises a dopant phosphorus and a dopant antimony, wherein the mass concentration of the dopant phosphorus in the silicon liquid is A, and the mass concentration of the dopant antimony in the silicon liquid is B, and A and B satisfy B / A=50-250; and growing single crystal silicon by a Czochralski method. According to the method for producing single crystal silicon of the present invention, a scheme of co-doping with dopant phosphorus and dopant antimony is adopted, and the mass concentration ratio of dopant phosphorus and dopant antimony is limited to produce single crystal silicon, and the physical property of antimony being highly volatile at high temperature is utilized, so that the difference in resistance between the head and the tail of single crystal silicon can be effectively reduced, and the resistance concentration can be improved, thereby improving the product quality of single crystal silicon rods, and at the same time, the photoelectric conversion efficiency of the battery can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal silicon manufacturing methods, and in particular to a single crystal silicon manufacturing method. Background Art

[0002] The existing N-type single crystal silicon is mainly based on pure phosphorus doping, with a phosphorus segregation coefficient of 0.35. Since the phosphorus segregation coefficient is less than 1, the resistance difference between the head and tail of the crystal rod is too large and the resistance concentration of the crystal rod is poor. Studies have shown that the worse the resistivity concentration of the crystal rod, the worse the quality stability of the corresponding crystal rod, which ultimately affects the photoelectric conversion efficiency of the battery. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for manufacturing single crystal silicon, which can improve the product quality of single crystal silicon.

[0004] A method for manufacturing single crystal silicon according to an embodiment of the present invention includes: forming a silicon liquid in a crucible, wherein the silicon liquid includes a dopant phosphorus and a dopant antimony, the mass concentration of the dopant phosphorus in the silicon liquid is A, the mass concentration of the dopant antimony in the silicon liquid is B, and A and B satisfy B / A=50-250; and growing a single crystal silicon by a Czochralski method.

[0005] According to the method for manufacturing single crystal silicon of the present invention, a scheme of co-doping with dopant phosphorus and dopant antimony is adopted, and the mass concentration ratio of dopant phosphorus and dopant antimony is limited to produce single crystal silicon, and the physical property of antimony being highly volatile at high temperature is utilized to effectively reduce the resistance difference between the head and tail of single crystal silicon, thereby improving the resistance concentration, and at the same time, the product quality of single crystal silicon can be effectively improved, thereby improving the photoelectric conversion efficiency of the battery.

[0006] According to some embodiments of the present invention, the forming of silicon liquid in the crucible includes: S1, putting silicon material and the dopant phosphorus into the crucible and heating; S2, putting the dopant antimony into the silicon liquid.

[0007] According to some optional embodiments of the present invention, S1 includes: adding the silicon material to a crucible in multiple times, and S2 includes: putting the dopant antimony into the last bucket of re-feed material and adding it to the crucible.

[0008] According to some optional embodiments of the present invention, the dopant antimony is located at a feeding port of the feeding bucket.

[0009] According to some embodiments of the present invention, the mass concentration of the dopant phosphorus is in the range of 20 ppbw-150 ppbw, and / or the mass concentration of the dopant antimony is in the range of 6000 ppbw-13000 ppbw.

[0010] According to some embodiments of the present invention, the ratio of the mass concentration of the dopant antimony to the mass concentration of the dopant phosphorus is 190-210.

[0011] According to some embodiments of the present invention, the dopant phosphorus is a phosphorus master alloy, and / or the dopant antimony is high purity antimony.

[0012] According to some embodiments of the present invention, the single crystal silicon is formed into a crystal rod, and the difference in resistivity of the crystal rod is 0Ω·cm-0.3Ω·cm.

[0013] According to some optional embodiments of the present invention, in the growth of single crystal silicon by the Czochralski method, when the diameter of the crystal rod is in the range of 0mm-600mm, the instantaneous pulling speed of the crystal rod is 0.8mm / min-2.4mm / min, and when the diameter of the crystal rod is greater than 600mm, the instantaneous pulling speed of the crystal rod is 1.2mm / min-2.2mm / min.

[0014] According to some embodiments of the present invention, after the growth of the single crystal silicon formed by the Czochralski method is completed, the silicon liquid retention ratio is in the range of 10%-40%.

[0015] 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

[0016] Figure 1 is a schematic diagram comparing the resistivity of single crystal silicon co-doped with phosphorus and antimony according to an embodiment of the present invention and the resistivity of single crystal silicon doped with pure phosphorus;

[0017] Figure 2 yes Figure 1 Schematic diagram of the normal distribution of resistance of phosphorus-antimony co-doped single crystal silicon and pure phosphorus-doped single crystal silicon shown in . DETAILED DESCRIPTION

[0018] 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.

[0019] Please refer to the attached Figure 1-2 A method for manufacturing single crystal silicon according to an embodiment of the present invention is described.

[0020] According to the method for manufacturing single crystal silicon according to the embodiment of the present invention, refer to Figure 1 and Figure 2, including: forming silicon liquid in a crucible, the silicon liquid including dopant phosphorus and dopant antimony, the mass concentration of the dopant phosphorus in the silicon liquid is A, the mass concentration of the dopant antimony in the silicon liquid is B, A and B satisfy B / A=50-250; growing single crystal silicon by a Czochralski method.

[0021] The mass concentration is the mass of a substance in a unit volume of a mixture. For example, the mass concentration of the dopant antimony is the mass of the dopant antimony in a unit volume of silicon liquid. The ratio of B to A can be 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200.

[0022] The method for producing single crystal silicon of the present invention adopts a scheme of co-doping with dopant phosphorus and dopant antimony, and limits the mass concentration ratio of dopant phosphorus and dopant antimony to produce single crystal silicon. The combination of dopant phosphorus and dopant antimony utilizes the physical property of high volatility of antimony at high temperature, thereby effectively reducing the resistance difference between the head and tail of single crystal silicon, improving resistance concentration, effectively improving the stability of crystal rod quality, and further improving the photoelectric conversion efficiency of the battery. Explanation of the role of high volatility of antimony: During the growth of phosphorus-antimony co-doped single crystal silicon, according to our preset resistivity of the crystal rod head and the specified phosphorus-antimony concentration, the phosphorus concentration is relatively low at the beginning of equal diameter, and the antimony concentration has a greater influence on the resistivity. As the equal diameter continues, the phosphorus concentration of the silicon liquid continues to enrich and increase, the antimony element continues to volatilize, and the antimony concentration decreases with the reduction of the silicon liquid. It does not increase according to the segregation principle but is continuously reduced. Therefore, as the equal diameter length increases, the weight of the phosphorus concentration affecting the resistivity continues to increase, and as the crystal rod length increases, the resistivity of the tail of the crystal rod tends more to the base phosphorus resistivity. Since the amount of carriers enriched in the single crystal silicon can be guaranteed to be relatively equal, the crystal rod formed by the entire single crystal silicon can be guaranteed to have a relatively equal resistance, thereby reducing the resistance difference between the head and tail of the single crystal silicon, and effectively improving the product quality of single crystal silicon.

[0023] In addition, during the growth of single crystal silicon, antimony reacts with oxygen to form antimony oxide, which promotes the volatilization of oxygen on the surface of the silicon liquid and inhibits the oxygen in the silicon liquid from entering the single crystal silicon, thereby reducing the oxygen content in the single crystal silicon. The lower oxygen content can reduce the recombination effect of impurities on minority carriers and increase the minority carrier lifetime, thereby further ensuring the photoelectric conversion efficiency of the battery.

[0024] According to the method for manufacturing single crystal silicon of an embodiment of the present invention, a scheme of co-doping with dopant phosphorus and dopant antimony is adopted, and the mass concentration ratio of dopant phosphorus and dopant antimony is limited to produce single crystal silicon, and the physical property of antimony being highly volatile at high temperature can be utilized to effectively reduce the resistance difference between the head and tail of single crystal silicon, thereby improving the resistance concentration, and at the same time, can effectively improve the product quality of single crystal silicon, thereby improving the photoelectric conversion efficiency of the battery.

[0025] According to some embodiments of the present invention, referring to Figure 1 and Figure 2 , forming silicon liquid in the crucible includes: S1, putting silicon material and dopant phosphorus into the crucible and heating; S2, putting dopant antimony into the silicon liquid.

[0026] According to some optional embodiments of the present invention, referring to Figure 1 and Figure 2 , S1 includes: adding silicon material and dopant phosphorus to the crucible in multiple times. For example, the silicon material can be added to the crucible in batches of two, three, four or more times according to the re-feeding requirements. S2 includes: putting the dopant antimony into the last barrel of re-feeding material and adding it to the crucible. Therefore, the multiple additions of silicon material can bring in phosphorus master alloys in any barrel of silicon material (phosphorus is less volatile in silicon liquid, and phosphorus master alloys do not need to be specifically added to a certain barrel of material). Due to its highly volatile physical properties at high temperatures, the dopant antimony needs to be added to the last barrel of re-feeding material and added to the crucible silicon liquid, thereby reducing the time interval between the dopant antimony entering the silicon liquid and before crystal pulling, and thus avoiding the premature volatilization of the dopant antimony, so the mass concentration of the dopant antimony in the silicon liquid can be effectively guaranteed.

[0027] According to some optional embodiments of the present invention, referring to Figure 1 and Figure 2 , the dopant antimony is located at the feeding port of the feeding bucket. Therefore, in the last bucket of re-feeding, the dopant antimony can be directly added to the silicon liquid, thereby effectively preventing the dopant antimony from volatilizing prematurely.

[0028] According to some embodiments of the present invention, referring to Figure 1 and Figure 2 , the mass concentration of the dopant phosphorus is in the range of 20ppbw-150ppbw, and / or the mass concentration of the dopant antimony is in the range of 6000ppbw-13000ppbw. Thus, a crystal rod with a specific resistivity can be grown according to actual needs, so that the method for manufacturing single crystal silicon of the present application can be applicable to crystal rods of various specifications.

[0029] For example, the mass concentration of the dopant phosphorus can be 20ppbw, 40ppbw, 60ppbw, 80ppbw, 100ppbw, 120ppbw, 140ppbw or 150ppbw, and the mass concentration of the dopant antimony can be 6000ppbw, 7000ppbw, 8000ppbw, 9000ppbw, 10000ppbw, 11000ppbw, 12000ppbw or 13000ppbw.

[0030] According to some embodiments of the present invention, referring to Figure 1 and Figure 2, the ratio of the mass concentration of the dopant antimony to the mass concentration of the dopant phosphorus is 190-210. Therefore, the high volatility physical properties of antimony can ensure a relatively stable resistivity, improve the resistance concentration of the crystal rod, and reduce the resistance difference between the head and tail of the single crystal silicon rod. Under the premise of ensuring that the tail resistance meets the demand, the crucible retention ratio can be effectively reduced, the utilization rate of silicon materials can be improved, the length of the crystal rod can be increased, and the single crystal pulling yield can be increased.

[0031] For example, the ratio of the mass concentration of the dopant antimony to the mass concentration of the dopant phosphorus may be 190, 192, 194, 196, 198, 200, 202, 204, 206, 208 or 210.

[0032] According to some optional embodiments of the present invention, referring to Figure 1 and Figure 2 , the dopant phosphorus is a phosphorus master alloy, and / or the dopant antimony is high-purity antimony. Thus, the phosphorus master alloy can provide a stable phosphorus source, making the introduction of phosphorus into the silicon liquid more controllable and uniform, which helps to ensure that the final single crystal silicon material has the expected resistivity. At the same time, high-purity antimony helps to reduce the introduction of impurities and the occurrence rate of unexpected defects, thereby ensuring the quality of the single crystal silicon.

[0033] According to some embodiments of the present invention, referring to Figure 1 and Figure 2 , the single crystal silicon is formed into a crystal rod, and the difference in the resistivity of the crystal rod is 0Ω·cm-0.3Ω·cm. As a result, the difference in the resistivity of the crystal rod is maintained in a low range, which can ensure that each silicon wafer cut from the same crystal rod has similar electrical properties, thereby ensuring the product quality of the single crystal silicon and meeting the use requirements.

[0034] For example, the difference in resistivity of the crystal rods may be 0 Ω·cm, 0.1 Ω·cm, 0.2 Ω·cm, or 0.3 Ω·cm.

[0035] According to some optional embodiments of the present invention, referring to Figure 1 and Figure 2 In the growth of single crystal silicon by the direct pulling method, when the diameter of the crystal rod is in the range of 0mm-600mm, the instantaneous pulling speed of the crystal rod is 0.8mm / min-2.4mm / min, and when the diameter of the crystal rod is greater than 600mm, the instantaneous pulling speed of the crystal rod is 1.2mm / min-2.2mm / min.

[0036] In this way, the instantaneous pulling speed of the crystal rod is closely related to the diameter of the crystal rod. A higher pulling speed may cause the diameter of the crystal rod to become smaller, while a lower pulling speed may cause the diameter of the crystal rod to increase. Therefore, by precisely controlling the pulling speed, the expected crystal rod size can be achieved.

[0037] For example, when the diameter of the crystal rod is in the range of 0mm-600mm, the instantaneous pulling speed of the crystal rod can be 0.8mm / min, 1mm / min, 1.2mm / min, 1.4mm / min, 1.6mm / min, 1.8mm / min, 2mm / min, 2.2mm / min or 2.4mm / min; when the diameter of the crystal rod is greater than 600mm, the instantaneous pulling speed of the crystal rod is 1.2mm / min, 1.4mm / min, 1.6mm / min, 1.8mm / min, 2mm / min or 2.2mm / min.

[0038] According to some embodiments of the present invention, referring to Figure 1 and Figure 2 After the growth of single crystal silicon is completed by the Czochralski method, the silicon liquid retention ratio is in the range of 10%-40%. This can improve the utilization rate of raw materials and reduce the production cost per unit product. At the same time, under the premise of the same feed amount, the number of silicon material re-feeds can be reduced, saving the production time of crystal rods.

[0039] For example, the silicon liquid retention ratio can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38% or 40%.

[0040] Furthermore, when growing single crystal silicon by the Czochralski method, the melting temperature of the silicon material is within the range of 1420-1450°C, the crucible speed is within the range of 5r / min-10r / min, the furnace pressure in the single crystal furnace is within the range of 5torr-10torr, and the argon flow rate is within the range of 70L / min-140L / min. Thus, the product quality of single crystal silicon can be guaranteed.

[0041] Furthermore, if Figure 1 As shown, in an N-type crystal rod, when the conventional pure phosphorus-doped scheme is used to produce the crystal rod, and the head resistivity of the crystal rod is controlled at 1.3Ω·cm, as the pull-out ratio increases, the resistivity of the crystal rod decreases from 1.3Ω·cm to 0.7Ω·cm at the tail of the crystal rod. When the phosphorus-antimony co-doped scheme is used to produce the crystal rod, and the head resistivity of the crystal rod is controlled at 1.1Ω·cm, as the pull-out ratio increases, the resistivity of the tail of the crystal rod gradually decreases to 0.95Ω·cm. Therefore, when the phosphorus-antimony co-doped scheme is used to produce the crystal rod, the resistivity of the crystal rod is smaller than that of the pure phosphorus-doped crystal rod.

[0042] In addition, if Figure 1 As shown, when the phosphorus-antimony co-doping scheme is used to produce crystal rods, the pull-out ratio of the crystal rod can reach 90%, that is, the silicon liquid retention ratio is 10%, thereby improving the utilization rate of raw materials and reducing the production cost per unit product.

[0043] Furthermore, if Figure 2 As shown, in the N-type crystal rod, when the conventional pure phosphorus doping scheme is used to produce the crystal rod, the density of the resistance value of the crystal rod in the range of 0.96Ω·cm-1.08Ω·cm is 2, and when the phosphorus-antimony co-doping scheme is used to produce the crystal rod, the density of the resistance value of the crystal rod in the range of 0.96Ω·cm-1.08Ω·cm is 9. Therefore, the phosphorus-antimony co-doping scheme is used to significantly improve the resistance concentration compared with pure phosphorus doping. Studies have shown that the higher the resistivity concentration, the higher the silicon wafer to battery conversion efficiency.

[0044] 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.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] 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.

[0048] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for producing single crystal silicon, characterized in that: include: Forming silicon liquid in a crucible, wherein the silicon liquid includes a dopant phosphorus and a dopant antimony, wherein the mass concentration of the dopant phosphorus in the silicon liquid is A, the mass concentration of the dopant antimony in the silicon liquid is B, and A and B satisfy B / A=50-250; Single crystal silicon is grown by the Czochralski method.

2. The method for producing single crystal silicon according to claim 1, characterized in that: The forming of silicon liquid in the crucible comprises: S1, putting silicon material and the dopant phosphorus into the crucible and heating; S2, adding antimony as a dopant into the silicon liquid.

3. The method for producing single crystal silicon according to claim 2, characterized in that: The step S1 comprises: adding the silicon material to the crucible in multiple times, The step S2 includes: placing the dopant antimony into the last barrel of re-feed material and feeding the re-feed into the crucible.

4. The method for producing single crystal silicon according to claim 3, characterized in that: The dopant antimony is located at the feeding port of the feeding bucket.

5. The method for producing single crystal silicon according to claim 1, characterized in that: The mass concentration of the dopant phosphorus is in the range of 20 ppbw-150 ppbw, and / or the mass concentration of the dopant antimony is in the range of 6000 ppbw-13000 ppbw.

6. The method for producing single crystal silicon according to claim 1, characterized in that: The ratio of the mass concentration of the dopant antimony to the mass concentration of the dopant phosphorus is 190-210.

7. The method for producing single crystal silicon according to claim 1, characterized in that: The dopant phosphorus is a phosphorus master alloy, and / or the dopant antimony is high-purity antimony.

8. The method for producing single crystal silicon according to claim 1, characterized in that: The single crystal silicon is formed into a crystal rod, and the difference in resistivity of the crystal rod is 0Ω·cm-0.3Ω·cm.

9. The method for producing single crystal silicon according to claim 8, characterized in that: In the single crystal silicon grown by the Czochralski method, when the diameter of the crystal rod is in the range of 0 mm-600 mm, the instantaneous pulling speed of the crystal rod is 0.8 mm / min-2.4 mm / min, and when the diameter of the crystal rod is greater than 600 mm, the instantaneous pulling speed of the crystal rod is 1.2 mm / min-2.2 mm / min.

10. The method for producing single crystal silicon according to claim 1, characterized in that: After the growth of the single crystal silicon formed by the Czochralski method is completed, the silicon liquid remaining ratio is in the range of 10%-40%.

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