Impurity source for CZ method-pulled silicon single crystal ingot, silicon single crystal ingot and pulling method thereof
By using a combination of initial and supplementary impurity sources in CZ Fadrazed n-type silicon single crystal ingots, the porous materials slowly release impurities, the problems of low phosphorus fractionation coefficient and impurity antimony volatility are solved, and the resistance of silicon single crystal ingots is achieved Improvement of rate uniformity and production efficiency.
Patent Information
- Application Number
- CN202411219918.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2044-09-02
AI Technical Summary
During the growth of the existing CZ Fadrail n-type silicon single crystal ingot, the resistivity is uneven due to the low coagulation coefficient of phosphorus, which limits the maximum length and single weight of the single crystal ingot, and the volatility of the impurity antimony. and toxicity problems are difficult to solve.
Using a combination of an initial impurity source and a supplementary impurity source, the initial impurity source includes phosphorus or antimony, and the supplementary impurity source includes boron, phosphorus or antimony compounds adsorbed in the porous material. The impurities are slowly released through the reduction reaction and the doping concentration of the molten silicon is adjusted. , realize uniform distribution of longitudinal resistivity.
It effectively improves the maximum drawing length and single weight of n-type silicon single crystal ingot, reduces the standard deviation of resistivity, improves product quality and production efficiency, reduces production costs, and reduces environmental risks.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor and photovoltaic technology, and in particular to an impurity source for CZ method pulling n-type silicon single crystal ingots, a method for pulling n-type silicon single crystal ingots using the impurity source, and an n-type silicon single crystal ingot made based on the pulling method. Background Art
[0002] The "Czochralski" method is abbreviated as the "CZ" method, which means the direct pulling method. It is one of the main methods for pulling silicon single crystal ingots. To pull n-conductivity type silicon single crystal ingots using the CZ method, it is necessary to add VA group n-type impurity elements such as phosphorus (P) or arsenic (As) or antimony (Sb) into the silicon material. Among them, the oxide of impurity arsenic is highly toxic and has a negative impact on the environment. On the one hand, the equilibrium segregation coefficient of impurity antimony is only 0.023, resulting in the addition amount of antimony increasing by more than ten times to ensure the design value of resistivity. On the other hand, the volatilization constant of impurity antimony is 14 times that of impurity arsenic and 700 times that of impurity phosphorus. There are large volatilization losses in the process of pulling silicon single crystals, unstable crystal pulling process, and large longitudinal resistivity gradient of silicon single crystal ingots, resulting in short length and small unit weight of single silicon single crystal ingots. Therefore, in the prior art, the dopant generally used in the CZ method to pull n-conductivity type silicon single crystal ingots is phosphorus, especially in the photovoltaic industry.
[0003] However, the equilibrium segregation coefficient of phosphorus is only 0.35, which is much smaller than 1. Therefore, as the silicon single crystal ingot is pulled, the concentration of phosphorus in the molten silicon in the crucible will gradually increase, making the resistivity of the pulled silicon single crystal ingot lower and lower. Finally, the resistivity index of the silicon single crystal ingot no longer meets the technical requirements of the product, and the growth of a larger silicon single crystal ingot has to be stopped. Therefore, the existing technology limits the maximum pulling length or crystal weight of the n-conductivity type silicon single crystal, which also limits the improvement of its production efficiency.
[0004] In order to solve the problem of limited unit weight of CZ method pulled silicon single crystal due to the low segregation coefficient of phosphorus, the existing technology has adopted technical measures of dual doping of phosphorus and arsenic impurities. The segregation coefficient of arsenic is 0.30, which is equivalent to phosphorus, and its volatilization constant is 5E-3 (cm / s), which is 50 times that of phosphorus. Therefore, by reasonably configuring the ratio of dual doped arsenic and phosphorus, part of the impure phosphorus is replaced by impurity arsenic, and the volatilization of impurity arsenic offsets the segregation of part of the impurity phosphorus, the longitudinal resistivity deviation of n-type silicon single crystal ingot is improved, and the purpose of obtaining a higher unit weight n-type silicon single crystal ingot is achieved.
[0005] However, first of all, there is the toxicity problem of arsenic oxide. For the large-scale production of n-type silicon single crystals in the photovoltaic industry, the amount of impurity arsenic used will be huge, and the safety and environmental risks cannot be ignored at all times; secondly, all impurities are added at once during loading, ignoring the impurity volatilization and segregation deviations caused by time and airflow adjustments that may occur during the process, thereby leading to deviations in the resistivity of the silicon single crystal ingot. If the impurity source is added midway, it may cause a sudden change in the impurity concentration of the molten silicon. Typically, when the crystal silicon rod grows, its crystallization plane is a convex surface toward the crystal. Therefore, the silicon wafers cut from the silicon rod are not grown at the same time, which causes the resistivity of the silicon wafer to exceed the standard. Summary of the invention
[0006] To this end, the present invention aims to solve the problem in the prior art that the subsequent addition of impurity sources causes a sudden change in the impurity concentration of molten silicon, thereby causing uneven resistivity within and between silicon wafers, and provides an impurity source for CZ method pulling silicon n-type single crystal ingots, an n-type silicon single crystal ingot and a pulling method thereof, wherein a porous material adsorbed with a supplementary impurity source slowly releases supplementary doping impurities through a reduction reaction, thereby slowly adjusting the impurity doping concentration of the molten silicon, mitigating the impact on the electrical parameters of the growing n-type silicon single crystal ingot, and achieving uniform longitudinal resistivity distribution of the n-type silicon single crystal ingot and uniform resistivity distribution within silicon wafers.
[0007] In a first aspect, in order to solve the above-mentioned technical problems, the present invention provides an impurity source for CZ method pulled silicon single crystal ingot, wherein the impurity source comprises an initial impurity source and a supplementary impurity source, and the supplementary impurity source comprises a compound of at least one element selected from phosphorus, antimony and boron adsorbed on a porous material.
[0008] In one embodiment of the present invention, the impurities of the initial impurity source include phosphorus and / or antimony; the impurities of the supplementary impurity source include one or more of boron, antimony, and phosphorus; when the impurities of the supplementary impurity source include boron, the proportion of boron ions in the supplementary impurities exceeds 50% based on the total number of supplementary doping impurity ions.
[0009] In one embodiment of the present invention, the impurities of the initial impurity source include phosphorus and / or antimony; the impurities of the supplementary impurity source include antimony and / or phosphorus. When the impurities of the supplementary impurity source include antimony, the proportion of antimony ions in the supplementary impurities exceeds 50% based on the total number of supplementary doped impurity ions.
[0010] In one embodiment of the present invention, the porous material is selected from porous ceramics or porous glass-ceramics.
[0011] In a second aspect, in order to solve the above technical problems, the present invention also provides a method for pulling a silicon single crystal ingot based on the CZ method, wherein an initial impurity source is doped into molten silicon to pull an n-type silicon single crystal ingot;
[0012] After the preset conditions are reached, a portion of the porous material adsorbed with the supplementary impurity source is immersed in the molten silicon to continue pulling the n-type silicon single crystal ingot;
[0013] Wherein, after the porous material adsorbed with the supplementary impurity source is immersed in molten silicon, the supplementary impurities are released through a reduction reaction and doped into the molten silicon.
[0014] In one embodiment of the present invention, the doping rate of the supplementary doping is further adjusted by controlling the total surface area of the porous material adsorbed with the supplementary impurity source immersed in the molten silicon.
[0015] In one embodiment of the present invention, the total amount of supplementary doping is adjusted by controlling the integral of the surface area of the porous material adsorbed with the supplementary impurity source immersed in the molten silicon over time.
[0016] In one embodiment of the present invention, the impurities of the initial impurity source include phosphorus and / or antimony; the impurities of the supplementary impurity source include one or more of boron, antimony, and phosphorus; when the impurities of the supplementary impurity source include boron, the proportion of boron ions in the supplementary impurities exceeds 50% based on the total number of supplementary doping impurity ions.
[0017] In one embodiment of the present invention, the impurities of the initial impurity source include phosphorus and / or antimony; the impurities of the supplementary impurity source include one or more of boron, antimony, and phosphorus. When the impurities of the supplementary impurity source include antimony, the proportion of antimony ions in the supplementary impurities exceeds 50% based on the total number of supplementary doping impurity ions.
[0018] In a third aspect, in order to solve the above technical problems, the present invention further provides an n-type silicon single crystal ingot, which is produced using the n-type silicon single crystal ingot pulling method based on the CZ method.
[0019] In one embodiment of the present invention, the conductivity type of the silicon single crystal ingot is n-type, containing two impurities, phosphorus and antimony, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.3.
[0020] Furthermore, in one embodiment of the present invention, the conductivity type of the silicon single crystal ingot is n-type, containing two impurities of phosphorus and antimony, and the ratio of the standard deviation of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.15.
[0021] Furthermore, in one embodiment of the present invention, the conductivity type of the silicon single crystal ingot is n-type, containing two impurities of phosphorus and antimony, and the ratio of the standard deviation of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.08.
[0022] In one embodiment of the present invention, the conductivity type of the silicon single crystal ingot is n-type, contains two impurities, phosphorus and boron, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.3.
[0023] Further, in one embodiment of the present invention, the conductivity type of the silicon single crystal ingot is n-type, contains two impurities of phosphorus and boron, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.15.
[0024] Furthermore, in one embodiment of the present invention, the conductivity type of the silicon single crystal ingot is n-type, contains two impurities of phosphorus and boron, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.08.
[0025] The above technical solution of the present invention has the following beneficial effects compared with the prior art:
[0026] The impurity source for pulling an n-type silicon single crystal ingot by the CZ method and the method for pulling a silicon single crystal ingot of the present invention include an initial impurity source and a supplementary impurity source, and the supplementary impurity source includes a compound of at least one element of phosphorus, antimony, and boron adsorbed on a porous material. The porous material adsorbed with the supplementary impurity source is immersed in molten silicon and slowly releases the supplementary impurities through a reduction reaction, which can be used to supplement the impurities required for doping during the crystal pulling process, while slowing down the impact on the electrical parameters of the growing n-type silicon single crystal ingot, and achieving uniform distribution of the longitudinal resistivity of the n-type silicon single crystal ingot and the resistivity within the silicon single crystal.
[0027] On the other hand, by slowly releasing the doping, the supplementary impurities make the maximum pulling length or crystal weight of the n-conductive type silicon single crystal no longer limited by the resistivity and its uniformity, thereby improving production efficiency and reducing production costs.
[0028] The silicon single crystal ingot described in the present invention reduces the standard deviation of the longitudinal resistivity index of a single n-type silicon single crystal ingot, and the longitudinal resistivity is evenly distributed, which is beneficial to improving the quality of the product and greatly increases its maximum drawing length and single weight. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.
[0030] Figure 1 A schematic diagram of a device for CZ method pulling n-type silicon single crystal ingots;
[0031] Figure 2 The figure is a flow chart of a method for pulling an n-type silicon single crystal ingot based on the CZ method in a preferred embodiment of the present invention.
[0032] Description of the accompanying drawings: 1-silicon single crystal ingot; 2-molten silicon; 3-supplementary impurity source; 4-crucible; DETAILED DESCRIPTION
[0033] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.
[0034] Commonly used doping impurities for pulling n-type silicon single crystal ingots are phosphorus and antimony. The equilibrium segregation coefficient of phosphorus is small. As the pulling process progresses, the concentration of phosphorus in the molten silicon in the crucible will gradually increase, making the resistivity of the pulled silicon single crystal ingot lower and lower. In order to balance the problem of reduced resistivity caused by the small equilibrium segregation coefficient of phosphorus, it is necessary to reduce the doping amount of phosphorus and supplement other impurities, preferably antimony. However, the volatility coefficient of antimony is 700 times that of phosphorus, resulting in a large initial antimony doping amount, large volatilization losses during the pulling process, insufficient impurity quality in the middle stage, and large resistivity fluctuations. In particular, the loss caused by the volatilization of the antimony impurity added once is greater, and the load of waste gas treatment increases accordingly.
[0035] In the first aspect, in order to solve the above problems, the embodiment of the present invention discloses an impurity source for pulling an n-type silicon single crystal ingot by the CZ method, wherein the impurity source includes an initial impurity source and a supplementary impurity source, wherein the supplementary impurity source includes a compound of at least one element of phosphorus (P), antimony (Sb), and boron (B) adsorbed in a porous material. The initial impurity source is added to the molten silicon at the beginning of crystal pulling, and after a period of crystal pulling, the supplementary impurity source is added to the molten silicon when a preset condition is met.
[0036] Exemplarily, the porous material is selected from porous ceramics or porous glass-ceramics, wherein the porous ceramic is a porous ceramic material with an open pore size and a high open porosity prepared by forming and high-temperature sintering processes of metal oxides, silicon dioxide, silicon carbide, etc., and the open pores have an adsorption effect. The impurity source is sintered and adsorbed on the surface of the open pores through a sintering process on the porous ceramic after sintering and forming to form the supplementary impurity source. Among them, the open pores include micropores, mesopores and macropores; the pore size of the micropores is less than 2nm, the pore size of the mesopores is 2~50nm, and the pore size of the macropores is greater than 50nm; the pore size and porosity of the open pores are determined according to the demand for the total amount of adsorbed impurities (the total amount of adsorbed impurities is related to the total surface area of the open pores).
[0037] The supplementary impurity source is adsorbed on the surface of open pores through a sintering process. When used for pulling silicon single crystal ingots, the porous material is immersed in molten silicon. The supplementary impurity source undergoes a reduction reaction with the molten silicon to "release" impurities into the molten silicon. The release speed and amount of impurities are controlled by the immersion area and immersion time.
[0038] Specifically, the impurities of the supplementary impurity source are selected from one or more of boron-containing oxides, boron-containing nitrides, antimony-containing oxides, phosphorus-containing oxides, and phosphorus-containing nitrides. For example, P2O5, PN, Sb2O3, B2O3, BN;
[0039] Among them, the antimony-containing impurities preferably contain antimony oxides, and the antimony oxide reacts with molten silicon to form and elemental antimony, volatilizes, and elemental antimony enters the silicon single crystal ingot in the form of n-type impurities. Volatile in the form of , The situation is similar. PN , BN, Nitrogen is released in a high temperature environment, and elemental phosphorus and elemental boron enter the molten silicon.
[0040] The volatilization of oxides is beneficial to reduce the oxygen content of silicon single crystal ingots. When applied to photovoltaic cells, it is beneficial to improve the photoelectric conversion efficiency of photovoltaic cells and improve the stability of the cells. The nitrogen element in phosphorus nitrides and boron nitrides is beneficial to promote the precipitation of oxygen in silicon and reduce the density of oxidation-induced stacking faults. When applied to photovoltaic cells, it is beneficial to improve the quality of photovoltaic cells.
[0041] In the second aspect, in order to solve the above technical problems, the embodiment of the present invention also provides a method for pulling an n-type silicon single crystal ingot based on the CZ method, which requires the use of Figure 1 The drawing device shown.
[0042] Reference Figure 2 As shown, the method for pulling an n-type silicon single crystal ingot comprises the following steps:
[0043] Doping an initial impurity source into molten silicon to pull an n-type silicon single crystal ingot; illustratively, the initial impurity source contains phosphorus, or phosphorus and antimony, and is added to the crucible in the form of a silicon master alloy together with polycrystalline silicon raw materials, a seed crystal is added, and the polycrystalline silicon is melted and then pulled to form a silicon single crystal ingot;
[0044] When the resistivity of the pulled silicon single crystal ingot is as low as the minimum control line or as high as the maximum control line, a part of the porous material adsorbed with the supplementary impurity source is immersed in the molten silicon to continue to pull the n-type silicon single crystal ingot; wherein, after the porous material adsorbed with the supplementary impurity source is immersed in the molten silicon, the supplementary impurity element is released by the reduction reaction and doped into the molten silicon. In a preferred embodiment of the present invention, the supplementary impurity source contains one or more of phosphorus, antimony, or boron.
[0045] Exemplarily, the porous material is selected from porous ceramics or porous glass-ceramics, wherein the porous ceramic is a porous ceramic material with an open pore size and a high open porosity prepared by molding and high-temperature sintering processes of metal oxides, silicon dioxide, silicon carbide, etc., and the open pores have an adsorption effect. The supplementary impurities are sintered and adsorbed on the surface of the open pores through a sintering process on the porous ceramic after sintering and forming to form the supplementary impurity source. Among them, the open pores include micropores, mesopores and macropores; the pore size of the micropores is less than 2nm, the pore size of the mesopores is 2~50nm, and the pore size of the macropores is greater than 50nm; the pore size and porosity of the open pores are determined according to the demand for the total amount of adsorbed impurities (the total amount of adsorbed impurities is related to the total surface area of the open pores).
[0046] Specifically, the porous material adsorbed with the supplementary impurity source is immersed in the molten silicon according to the required immersion area and entry time.
[0047] As mentioned above, the porous material can greatly reduce the volatilization loss of the dopant by immersing it in molten silicon and slowly releasing the dopant through a reduction reaction. At the same time, the dopant is slowly released, thereby achieving the purpose of alleviating the impact on the electrical parameters of the growing silicon single crystal ingot and achieving uniform longitudinal and radial resistivity distribution of the silicon single crystal ingot.
[0048] Specifically, the pulling method further includes adjusting the doping speed of the supplementary doping by controlling the total surface area of the porous material adsorbed with the supplementary impurity source immersed in the molten silicon, and also includes adjusting the total doping amount of the supplementary doping by controlling the time interval of the porous material adsorbed with the supplementary impurity source immersed in the molten silicon.
[0049] Furthermore, when the impurity of the supplementary impurity source is boron, the proportion of boron ions in the supplementary impurities exceeds 50% based on the total number of supplementary doped impurity ions, so as to achieve the purpose of mutual compensation of electrical properties between the impurity boron and the excess impurity phosphorus, thereby reducing the effective impurity phosphorus concentration.
[0050] Similarly, when the impurity of the supplementary impurity source is antimony, the proportion of antimony ions in the supplementary impurities exceeds 50% based on the total number of supplementary doping impurity ions, so as to compensate for the deficiency of the initial doping impurities antimony and phosphorus, and use the high volatility coefficient of the impurity antimony to control the effective n-type impurity concentration of the silicon single crystal ingot to be not too high.
[0051] In a third aspect, in order to solve the above technical problems, the present invention also provides an n-type silicon single crystal ingot, which is produced using the n-type silicon single crystal ingot pulling method based on the CZ method.
[0052] Specifically, the prepared n-type silicon single crystal ingot contains two impurities, phosphorus and antimony, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.3.
[0053] Preferably, the prepared n-type silicon single crystal ingot contains two impurities, phosphorus and antimony, and the ratio of the standard deviation of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.15.
[0054] Further preferably, the prepared n-type silicon single crystal ingot contains two impurities, phosphorus and antimony, and the ratio of the standard deviation of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.08.
[0055] In another embodiment, the prepared n-type silicon single crystal ingot contains two impurities, phosphorus and boron, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.3.
[0056] Preferably, the prepared n-type silicon single crystal ingot contains two impurities, phosphorus and boron, and the ratio of the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.15.
[0057] Further preferably, the prepared n-type silicon single crystal ingot contains two impurities, phosphorus and boron, and the ratio of the standard deviation of the longitudinal resistivity of the silicon single crystal ingot to its solidification percentage is less than 0.08. Embodiment 1
[0058] This embodiment provides a method for pulling an n-type silicon single crystal ingot based on the CZ method, comprising the following steps:
[0059] The required silicon polycrystalline material is placed in a crucible, and the required amount of n-type impurity phosphorus is calculated and doped with phosphorus according to the lower limit requirement of the resistivity of the tail of the silicon single crystal ingot and the effective equivalent segregation coefficient of phosphorus. The required amount of n-type impurities is calculated according to the intermediate value of the required silicon single crystal length and the head resistivity, and the influence of the existing dopant phosphorus is subtracted. The n-type impurity antimony is additionally doped and the silicon single crystal ingot is started to be pulled.
[0060] Since the volatilization effect of the impurity antimony is more effective than the segregation effect of the impurity phosphorus, the effective impurity concentration in the silicon single crystal ingot will gradually decrease and the resistivity will increase at the beginning of crystal pulling. When the resistivity of the silicon single crystal ingot rises to the upper control limit, the supplementary doped porous material is controlled to be immersed in the molten silicon to supplement the doping of antimony. The rate of supplementary doping of antimony is based on the resistivity index of the silicon single crystal ingot being within the control limit. As the concentration of impurity phosphorus gradually recovers due to the influence of the segregation coefficient, the amount of supplementary doping of antimony is reduced synchronously, and finally the supplementary doping is stopped. The supplementary doped porous material is controlled to separate from the surface of the molten silicon, and a silicon single crystal ingot is obtained by pulling.
[0061] In this embodiment, the ratio of the standard deviation of the longitudinal resistivity of the entire silicon single crystal ingot measured to its solidification percentage is less than 0.15. Embodiment 2
[0062] This embodiment provides a method for pulling an n-type silicon single crystal ingot based on the CZ method, comprising the following steps:
[0063] The required silicon polycrystalline material is placed in a crucible, and phosphorus-containing dopants are added according to the maximum allowable head resistivity value of the silicon single crystal ingot, and the pulling of the silicon single crystal ingot begins.
[0064] Due to the influence of the effective converted segregation coefficient of impurity phosphorus, the resistivity of the pulled silicon single crystal ingot will gradually decrease. When the resistivity of the pulled silicon single crystal ingot is reduced to the control lower limit, the supplementary doped porous material is controlled to be immersed in the molten silicon. The porous material adsorbs a supplementary impurity source containing boron element. According to the resistivity requirement of the pulled silicon single crystal ingot and the effective converted segregation coefficient of impurity phosphorus and impurity boron, the immersion amount and immersion time of the supplementary doped porous material are adjusted until the crystal pulling is completed. The supplementary doped porous material is controlled to separate from the surface of the molten silicon to obtain the silicon single crystal ingot by pulling.
[0065] In this embodiment, the ratio of the standard deviation of the longitudinal resistivity of the entire silicon single crystal ingot measured to its solidification percentage is less than 0.08.
[0066] The standard deviation of the longitudinal resistivity of the silicon single crystal ingot refers to the standard deviation of the longitudinal resistivity distribution of the silicon single crystal ingot. The ratio of its longitudinal resistivity to the mean value E(X), where It is calculated as follows:
[0067] The silicon single crystal ingot has end faces a and b at both ends of the pulling direction. The resistivity of the silicon single crystal ingot at end face a is , the resistivity at the end surface b is , and the resistivity of the silicon single crystal ingot between end face a and end face b is linearly monotonically distributed, then .
[0068] The average longitudinal resistivity E(X) is the average resistivity of all slices after the silicon single crystal ingot is sliced between the end face a and the end face b.
[0069] The solidification percentage of the silicon single crystal ingot refers to the ratio of the weight of the section after the head and tail of the silicon single crystal ingot are cut off to the total weight of the polycrystalline material in the crucible.
[0070] The longitudinal resistivity of the silicon single crystal ingot is collected by the method specified in standard GB / T 1551. As a supplement, it is necessary to find the extreme value points of resistivity (if any) in the longitudinal "measurement track" of the silicon single crystal ingot, and calculate the standard deviation rate of the longitudinal resistivity of the silicon single crystal ingot and the solidification percentage of the silicon single crystal ingot by measuring between the extreme value points.
[0071] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.
Claims
1. A method for pulling an n-type silicon single crystal ingot based on a CZ method, characterized in that: include, doping an initial impurity source into molten silicon to pull an n-type silicon single crystal ingot; After reaching the preset condition, immersing a portion of the porous material adsorbed with the supplementary impurity source into the molten silicon, and continuing to pull the n-type silicon single crystal ingot; the preset condition is when the resistivity of the pulled silicon single crystal ingot is as low as the lowest control line or as high as the highest control line; The supplementary impurity source includes a compound of at least one element among phosphorus, antimony and boron adsorbed on the porous material; Wherein, after the porous material adsorbed with the supplementary impurity source is immersed in molten silicon, the supplementary impurities are released through a reduction reaction and doped into the molten silicon; The impurity source is sintered and adsorbed on the surface of the open pores through a sintering process to form the supplementary impurity source, and the pore size and porosity of the open pores are determined according to the total amount of impurities adsorbed.
2. The method for pulling an n-type silicon single crystal ingot based on the CZ method according to claim 1, characterized in that: The method also includes adjusting the doping rate of the supplementary doping by controlling the total surface area of the porous material adsorbed with the supplementary impurity source immersed in the molten silicon.
3. The method for pulling an n-type silicon single crystal ingot based on the CZ method according to claim 2, characterized in that: The method also includes adjusting the total doping amount of the supplementary doping by controlling the integral of the surface area of the porous material adsorbed with the supplementary impurity source immersed in the molten silicon over time.