Regulation and control method of silicon single crystal rod preparation process based on rod-like silicon raw material grade

Abstract

The invention relates to the technical field of silicon single crystal rod preparation, in particular to a rod-shaped silicon raw material grade-based regulation and control method of a silicon single crystal rod preparation process, and the regulation and control method comprises the following steps: dividing the grades of rod-shaped silicon raw materials into multiple classes according to the matrix metal content, the surface metal content, the minority carrier lifetime mean value and the turbidity, one of the multiple classes is selected as a standard class, and the other classes are selected as non-standard classes; a monocrystalline silicon rod preparation process matched with the standard-grade rod-like silicon raw material is obtained and used as a reference process, crystal pulling end performance of the standard-grade rod-like silicon raw material is obtained, and the performance comprises at least one of the yield, the minority carrier resistivity, the oxygen content and the carbon content; with the crystal pulling end expression of the standard-grade rod-like silicon raw material as a contrast, the crystal pulling end expression change obtained by predicting the non-standard-grade rod-like silicon raw material by adopting the standard process is estimated; and adjusting the reference process according to the predicted crystal pulling end expression change of the non-standard-grade rod-like silicon raw material, so as to obtain the single crystal silicon rod preparation process of the non-standard-grade rod-like silicon raw material.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal silicon rod preparation, and in particular to a method for regulating a single crystal silicon rod preparation process based on the grade of a rod-shaped silicon raw material. Background Art

[0002] With the development of technology, solar energy equipment is being used more and more widely. Making single crystal silicon rods through a single crystal furnace is an important processing step for solar energy equipment.

[0003] Rod silicon is an important raw material for the preparation of single crystal silicon rods. Different grades of rod silicon have different effects on the crystal pulling end during the preparation of single crystal silicon rods, that is, different grades of rod silicon are suitable for different ideal crystal pulling processes. Existing rod silicon is divided into four grades according to relevant indicators: special grade, electronic grade 1, electronic grade 2 and electronic grade 3.

[0004] The existing rod-shaped silicon determination standards cannot predict the impact of different grades of rod-shaped silicon on the crystal pulling end, and technical personnel in this field cannot reasonably regulate the preparation process of single crystal silicon rods according to the determination grade of rod-shaped silicon, which is not conducive to improving the utilization rate of rod-shaped silicon raw materials and the quality of the produced single crystal silicon rods. Summary of the invention

[0005] The present application proposes a control method for a single crystal silicon preparation process based on the rod-shaped silicon grade, which is beneficial to improving the utilization rate of the rod-shaped silicon raw material in the single crystal silicon rod preparation process and the quality of the single crystal silicon rod products.

[0006] In a first aspect, the present application provides a method for regulating a single crystal silicon rod preparation process based on the grade of a rod-shaped silicon raw material, which comprises:

[0007] The grades of the rod-shaped silicon raw materials are divided into multiple categories according to the matrix metal content ω1, the surface metal content ω2, the minority carrier lifetime mean τ and the turbidity NTU, and one of the multiple categories is selected as the standard grade, and the other categories are selected as non-standard grades;

[0008] Obtaining a single crystal silicon rod preparation process matched with the standard-grade rod-shaped silicon raw material and using it as a benchmark process, and obtaining a performance of the crystal pulling end of the standard-grade rod-shaped silicon raw material, wherein the performance includes at least one of yield, minority carrier resistivity, oxygen content, and carbon content;

[0009] Taking the performance of the crystal pulling end of the standard-grade rod-shaped silicon raw material as a comparison, estimating the change in the crystal pulling end performance of the non-standard-grade rod-shaped silicon raw material that is expected to be achieved by using the benchmark process;

[0010] According to the estimated change in the crystal pulling end performance of the non-standard grade rod-shaped silicon raw material, the reference process is adjusted to obtain a single crystal silicon rod preparation process that matches the non-standard grade rod-shaped silicon raw material.

[0011] In some embodiments, the grades of the rod-shaped silicon raw materials are divided into at least Class I, Class II and Class III, and the grades of Class I, Class II and Class III are arranged in descending order; wherein,

[0012] In the type I rod-shaped silicon raw material, ω1≤0.3ng / g, ω2≤0.3ng / g, τ≥1800μs, NTU≤40;

[0013] In the II type rod-shaped silicon raw material, 0.3ng / g<ω1≤0.5ng / g, 0.3ng / g<ω2≤0.5ng / g, 1800μs>τ≥1500μs, 40<NTU≤50;

[0014] For Class III rod-shaped silicon raw materials, 0.5ng / g<ω1≤1ng / g, 0.5ng / g<ω2≤1ng / g, 1500μs>τ≥1200μs, 50<NTU≤60.

[0015] In some embodiments, the donor impurity concentration in the rod-shaped silicon raw material is ω3, the acceptor impurity concentration is ω4, the oxygen concentration is φ1, and the carbon concentration is φ2;

[0016] In the rod-shaped silicon raw materials of type I, type II and type III, ω3≤0.35ppba; and / or,

[0017] In the rod-shaped silicon raw materials of type I, type II and type III, ω4≤0.1ppba; and / or,

[0018] In the rod-shaped silicon raw materials of type I, type II and type III, φ1≤2*10 16 Atom / cm 3 and / or,

[0019] In the rod-shaped silicon raw materials of type I, type II and type III, φ2≤2*10 16 Atom / cm 3 .

[0020] In some embodiments, if it is estimated that the yield of the non-standard grade rod-shaped silicon raw material at the pulling end is reduced by m kg, the method for adjusting the reference process includes:

[0021] Increase the amount of material in the crystal pulling process;

[0022] Increase the pulling rate during the crystal pulling process by v mm / h, v = (0.6 ~ 1.6) m.

[0023] In some embodiments, if it is estimated that the minority carrier resistivity of the non-standard grade rod-shaped silicon raw material at the crystal pulling end is reduced, the method for adjusting the baseline process includes increasing the feed amount during the crystal pulling process.

[0024] In some embodiments, if it is estimated that the minority carrier resistivity of the pulled end of the non-standard grade rod-shaped silicon raw material is reduced, the method for adjusting the reference process includes increasing the tail cutting length of the single crystal silicon rod obtained by pulling;

[0025] In some embodiments, if it is estimated that the minority carrier resistivity of the non-standard grade rod-shaped silicon raw material at the crystal pulling end is reduced, the method for adjusting the reference process includes increasing the pot retention rate of the silicon material after the crystal pulling is completed.

[0026] In some embodiments, if it is estimated that the minority carrier resistivity of the non-standard grade rod-shaped silicon raw material at the pulling end is reduced by A%, the method for adjusting the baseline process includes increasing the feed amount during the crystal pulling process.

[0027] In some embodiments, if it is estimated that the minority carrier resistivity of the pulled end of the non-standard grade silicon rod raw material decreases by A%, the method for adjusting the benchmark process includes increasing the tail cutting length of the single crystal silicon rod obtained by pulling by Lmm, 15A≤L≤25A.

[0028] In some embodiments, if it is estimated that the minority carrier resistivity of the non-standard grade rod-shaped silicon raw material at the pulling end is reduced by A%, the method for adjusting the reference process includes increasing the pot rate of the silicon material after the pulling is completed by A% to 1.25A%.

[0029] In some embodiments, if the estimated oxygen content at the pulling end of the non-standard grade silicon rod feedstock increases, the method of adjusting the baseline process includes reducing the rotation speed of the crucible of the crystal pulling furnace during the crystal pulling process.

[0030] In some embodiments, if the estimated oxygen content at the pulling end of the non-standard grade silicon rod feedstock increases, the method for adjusting the baseline process includes increasing the distance between the bottom of the heater of the crystal pulling furnace and the guard plate during the crystal pulling process.

[0031] In some embodiments, if the estimated oxygen content at the pulling end of the non-standard grade silicon rod feedstock increases, the method of adjusting the baseline process includes reducing the furnace pressure of the crystal pulling furnace during the crystal pulling process.

[0032] In some embodiments, if the estimated oxygen content at the pulling end of the non-standard grade silicon rod raw material increases, the method of adjusting the baseline process includes increasing the head cutting length of the pulled single crystal silicon rod.

[0033] In some embodiments, if the oxygen content of the non-standard grade silicon rod raw material at the pulling end is estimated to increase by Xng / g, the method for adjusting the reference process includes reducing the rotation speed of the crucible of the crystal pulling furnace during the crystal pulling process by Y1rpm, 2X≤Y1≤4X.

[0034] In some embodiments, if it is estimated that the oxygen content at the pulling end of the non-standard grade rod-shaped silicon raw material increases by Xng / g, the method for adjusting the baseline process includes increasing the distance between the bottom of the heater of the crystal pulling furnace and the guard plate press during the crystal pulling process by Y2 mm, 80X≤Y2≤105X.

[0035] In some embodiments, if the oxygen content at the pulling end of the non-standard grade silicon rod raw material is estimated to increase by X ppma, the method for adjusting the baseline process includes reducing the furnace pressure of the crystal pulling furnace by Y3 torr during the crystal pulling process, 1.3X≤Y3≤4.5X.

[0036] In some embodiments, the standard-grade rod-shaped silicon raw material is a Class I rod-shaped silicon raw material, and the estimated changes in the performance of the crystal pulling end of the non-standard-grade rod-shaped silicon raw material include: relative to Class I rod-shaped silicon raw material, the yield of the crystal pulling end of Class II rod-shaped silicon raw material is expected to decrease by 0.5kg to 1.5kg, and the yield of Class III rod-shaped silicon raw material is expected to decrease by 2.5 to 3.5kg.

[0037] In some embodiments, the estimated changes in the performance of the pulling end of the non-standard grade rod-shaped silicon raw material include: relative to Class I rod-shaped silicon raw material, the minority carrier resistance ratio of the pulling end of Class II rod-shaped silicon raw material is expected to decrease by 3.5% to 4.5%, and the minority carrier resistance ratio of Class III rod-shaped silicon raw material is expected to decrease by 7% to 9%.

[0038] In some embodiments, the estimated changes in the performance of the pulling end of the non-standard grade rod-shaped silicon raw material include: relative to Class I rod-shaped silicon raw material, the oxygen content of the pulling end of Class II rod-shaped silicon raw material is expected to increase by 0ppma~0.01ppma, and the oxygen content of the pulling end of Class III rod-shaped silicon raw material is expected to increase by 0.25ppma~0.45ppma.

[0039] In some embodiments, the estimated changes in the performance of the pulling end of the non-standard grade rod-shaped silicon raw material include: relative to Class I rod-shaped silicon raw material, the carbon content of the pulling end of Class II rod-shaped silicon raw material is expected to increase by 0.005ppma~0.015ppma, and the carbon content of the pulling end of Class III rod-shaped silicon raw material is expected to increase by 0.035ppma~0.045ppma.

[0040] In some embodiments, if the estimated change in the pulling end performance of the non-standard grade silicon rod raw material is an increase in carbon content, the method for adjusting the baseline process includes: increasing the tail cutting length of the single crystal silicon rod obtained by pulling to reduce its carbon content to a preset value.

[0041] Compared with the prior art, this technical solution has at least the following technical effects:

[0042] The technical solution of the present application incorporates the important factors that affect the performance of the crystal pulling end into the grade classification conditions of the rod-shaped silicon raw material, so that the difference in the performance of the crystal pulling end between different grades of rod-shaped silicon raw materials can be estimated according to the grade judgment standard of the rod-shaped silicon raw material, and the preparation process of the single crystal silicon rod is appropriately adjusted according to the estimated difference in the performance of the crystal pulling end, so that the actual performance of the crystal pulling end of the rod-shaped silicon raw material can be close to its target performance of the crystal pulling end, which is beneficial to improve the utilization rate of the rod-shaped silicon raw material and the quality of the single crystal silicon rods produced from the rod-shaped silicon raw material. In the control method of the present application, since the change in the performance of the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the standard grade rod-shaped silicon raw material can be predicted, the reasonable control of the single crystal silicon rod preparation process corresponding to the non-standard grade rod-shaped silicon raw material can be achieved without experimental exploration, and the control speed is fast, saving a lot of manpower and material resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0044] Figure 1 Schematic diagram of the process flow of the single crystal silicon rod preparation method of the embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0046] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0048] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0049] The existing rod-shaped silicon determination standards cannot predict the impact of different grades of rod-shaped silicon on the crystal pulling end, and technical personnel in this field cannot reasonably regulate the preparation process of single crystal silicon rods according to the determination grade of rod-shaped silicon, which is not conducive to improving the utilization rate of rod-shaped silicon raw materials and the quality of the produced single crystal silicon rods.

[0050] In order to solve the above technical problems, the embodiments of the present application propose a method for regulating the single crystal silicon rod preparation process based on the grade of rod-shaped silicon raw materials.

[0051] In the embodiment of the present application, the rod-shaped silicon raw material may be N-type rod-shaped silicon or P-type rod-shaped silicon. The embodiment of the present application is described below by taking N-type rod-shaped silicon as an example.

[0052] See also Figure 1 In the embodiment of the present application, the control method comprises the following steps:

[0053] S10. The grades of the rod-shaped silicon raw materials are divided into multiple categories according to the matrix metal content ω1, the surface metal content ω2, the minority carrier lifetime mean τ and the turbidity NTU, and one of the multiple categories is selected as the standard grade, and the other categories are selected as non-standard grades;

[0054] S20. Obtaining a single crystal silicon rod preparation process matched with a standard-grade rod-shaped silicon raw material and using it as a reference process, and obtaining a crystal pulling end performance of the standard-grade rod-shaped silicon raw material, the performance including at least one of yield, minority carrier resistivity, oxygen content, and carbon content;

[0055] S30. Taking the performance of the crystal pulling end of the standard grade rod-shaped silicon raw material as a comparison, estimate the change in the crystal pulling end performance of the non-standard grade rod-shaped silicon raw material using the benchmark process;

[0056] S40. According to the estimated change in the crystal pulling end performance of the non-standard grade rod-shaped silicon raw material, the baseline process is adjusted to obtain a single crystal silicon rod preparation process that matches the non-standard grade rod-shaped silicon raw material.

[0057] The technical solution of the present application incorporates the important factors that affect the performance of the crystal pulling end into the grading conditions of the rod-shaped silicon raw materials, so that the difference in the performance of the crystal pulling end between different grades of rod-shaped silicon raw materials can be estimated according to the grade judgment standard of the rod-shaped silicon raw materials, and the preparation process of the single crystal silicon rod is appropriately adjusted according to the estimated difference in the performance of the crystal pulling end, so that the actual performance of the crystal pulling end of the rod-shaped silicon raw materials can be close to its target performance of the crystal pulling end, which is beneficial to improve the utilization rate of the rod-shaped silicon raw materials and the quality of the single crystal silicon rods produced from the rod-shaped silicon raw materials. In the control method of the present application, since the change in the performance of the crystal pulling end of the non-standard grade rod-shaped silicon raw materials relative to the standard grade rod-shaped silicon raw materials can be predicted, the reasonable control of the single crystal silicon rod preparation process corresponding to the non-standard grade rod-shaped silicon raw materials can be achieved without experimental exploration, saving a lot of manpower and material resources.

[0058] The following is a detailed description of the control method of the embodiment of the present application:

[0059] S10. The grades of the rod-shaped silicon raw materials are divided into multiple categories according to the matrix metal content ω1, the surface metal content ω2, the minority carrier lifetime mean τ and the turbidity NTU, and one of the multiple categories is selected as the standard grade, and the other categories are selected as non-standard grades.

[0060] In the embodiments of the present application, the test method of the matrix metal content ω1 is: spectral analysis method, etc. Generally speaking, the matrix metal content ω1 in the rod-shaped silicon raw material can be found from the COA test report issued by the manufacturer of the rod-shaped silicon raw material.

[0061] The test method for the metal content ω2 is as follows: acid leaching-inductively coupled plasma mass spectrometry, etc. Generally speaking, the matrix metal content ω2 in the rod-shaped silicon raw material can be found in the COA test report issued by the rod-shaped silicon raw material manufacturer.

[0062] The test method for the minority carrier lifetime mean τ is as follows: Photoelectric method. Generally speaking, the minority carrier lifetime mean τ of the rod-shaped silicon raw material can be found in the COA test report issued by the rod-shaped silicon raw material manufacturer.

[0063] Turbidity NTU refers to the content of microsilica powder in rod-shaped silicon raw materials.

[0064] The test method for turbidity NTU is as follows: completely immerse the rod-shaped silicon raw material in water, dissolve the microsilica powder in the rod-shaped silicon raw material into the water, filter to obtain a solution, and use the turbidity method to determine the microsilica powder content in the solution.

[0065] In some embodiments, the base metal in the rod-shaped silicon raw material includes Fe, Cr, Ni, Cu, Zn, Na, etc.

[0066] In some embodiments, the surface metals in the rod-shaped silicon raw material include Fe, Cr, Ni, Cu, Zn, Al, K, Na, etc.

[0067] S30. Using the performance of the crystal pulling end of standard-grade rod-shaped silicon raw material as a control, estimate the change in the crystal pulling end performance of non-standard-grade rod-shaped silicon raw material using the benchmark process.

[0068] That is to say, under the grade determination standard of the rod-shaped silicon raw material provided in the embodiment of the present application, the performance of the crystal pulling end of the non-standard grade rod-shaped silicon raw material under the same single crystal silicon rod preparation process can be estimated based on the performance of the crystal pulling end of the standard grade rod-shaped silicon raw material.

[0069] S40. According to the estimated change in the crystal pulling end performance of the non-standard grade rod-shaped silicon raw material, the baseline process is adjusted to obtain a single crystal silicon rod preparation process that matches the non-standard grade rod-shaped silicon raw material.

[0070] Among them, when the estimated yield of the crystal pulling end of the non-standard grade rod-shaped silicon raw material is expected to exceed the target yield range, the relevant parameters affecting the yield of the crystal pulling end in the benchmark process are appropriately adjusted to reduce the deviation of the actual yield of the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target yield; when the estimated minority carrier resistivity of the crystal pulling end of the non-standard grade rod-shaped silicon raw material is expected to exceed the target minority carrier resistivity range, the relevant parameters affecting the minority carrier resistivity of the crystal pulling end in the benchmark process are appropriately adjusted to reduce the deviation of the actual minority carrier resistivity of the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target minority carrier resistivity. deviation; when the estimated oxygen content of the crystal pulling end of the non-standard grade rod-shaped silicon raw material is expected to exceed the target oxygen content range, the relevant parameters affecting the oxygen content of the crystal pulling end in the benchmark process are appropriately adjusted to reduce the deviation of the actual oxygen content of the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target oxygen content; when the estimated carbon content of the crystal pulling end of the non-standard grade rod-shaped silicon raw material is expected to exceed the target carbon content range, the relevant parameters affecting the carbon content of the crystal pulling end in the benchmark process are appropriately adjusted to reduce the deviation of the actual carbon content of the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target carbon content.

[0071] In the embodiment of the present application, if it is estimated that the yield of the crystal pulling end of the non-standard grade rod-shaped silicon raw material is reduced, the method for adjusting the reference process includes:

[0072] Increasing the amount of material fed during crystal pulling; and / or,

[0073] Increase the pulling rate during the crystal pulling process.

[0074] In some embodiments, if it is estimated that the yield of the non-standard grade rod-shaped silicon raw material at the crystal pulling end is lower than the target yield, the feed amount in the crystal pulling process is increased based on the benchmark process for regulation to correct the deviation of the yield of the non-standard grade rod-shaped silicon raw material at the crystal pulling end relative to the target yield, thereby facilitating the improvement of the utilization rate of the non-standard grade rod-shaped silicon raw material.

[0075] Generally speaking, in order to increase the feed amount during the crystal pulling process, the volume of the crucible of the crystal pulling furnace needs to be increased. Considering the limitation of the thermal field size, the height of the crucible is usually increased.

[0076] In some embodiments, the crystal pulling end yield of standard-grade rod-shaped silicon raw material is used as the target yield. If the crystal pulling end yield of non-standard-grade rod-shaped silicon raw material is estimated to be reduced by m kg, the height of the crucible of the crystal pulling furnace is increased by H based on the benchmark process, H≥2*(△m / (2*(1-crucible retention rate)*weight reduction coefficient)kg, △m=m.

[0077] In the above embodiment, Δm is the difference between the estimated and calculated actual crystal pulling end yield (using the benchmark process) of the non-standard grade rod-shaped silicon raw material and the target yield; it can be understood that when the target yield changes, the Δm value also changes accordingly.

[0078] In the above embodiment, the weight reduction coefficient refers to the ratio of the weight of the cylindrical rod-shaped silicon obtained by crystal pulling after being cut into squares to the weight before cutting.

[0079] In some embodiments, if it is estimated that the yield of the non-standard grade rod-shaped silicon raw material at the crystal pulling end is reduced by m kg, the pulling rate in the crystal pulling process is increased by v mm / h based on the benchmark process to correct the deviation of the oxygen yield at the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target yield, thereby facilitating the improvement of the utilization rate of the non-standard grade rod-shaped silicon raw material.

[0080] In a specific embodiment, the yield of the pulling end of the standard-grade rod-shaped silicon raw material is taken as the target yield, v = (0.6-1.6) m, specifically, v = 0.6 m, 0.9 m, 1.6 m or any value therebetween.

[0081] In the embodiment of the present application, if the estimated oxygen content of the pulling end of the non-standard grade rod-shaped silicon raw material increases, the method for adjusting the reference process includes a combination of one or more of the following methods:

[0082] (1) Reduce the rotation speed of the crucible of the crystal pulling furnace during the crystal pulling process: During the crystal pulling process, the faster the rotation speed, the more intense the reaction between the silicon liquid and the crucible wall, the easier it is for the oxygen in the quartz crucible to enter the silicon liquid, and the more oxygen the crystal rod absorbs.

[0083] (2) Increase the distance between the bottom of the heater of the crystal pulling furnace and the guard plate during the crystal pulling process: During the crystal pulling process, the larger the distance between the bottom of the heater of the crystal pulling furnace and the guard plate, the faster the evacuation rate, the less contact between the silicon liquid and the air, and the less oxygen absorbed by the crystal rod.

[0084] (3) Reduce the furnace pressure of the crystal pulling furnace during the crystal pulling process: During the crystal pulling process, the lower the furnace pressure, the faster the evacuation rate, the less contact between the silicon liquid and the air, and the less oxygen absorbed by the crystal rod.

[0085] (4) Increasing the head cutting length (reverse cutting) of the single crystal silicon rod obtained by crystal pulling: Through reverse cutting, the crystal rod with high oxygen content can be cut off.

[0086] In some embodiments, if it is estimated that the oxygen content at the crystal pulling end of the non-standard grade rod-shaped silicon raw material increases by X ppma, the rotation speed of the crucible of the crystal pulling furnace during the crystal pulling process is reduced by Y1 rpm based on the reference process to correct the deviation of the oxygen content at the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target oxygen content, thereby facilitating the improvement of the quality of single crystal silicon rods produced from the non-standard grade rod-shaped silicon raw material.

[0087] In a specific embodiment, the oxygen content at the pulling end of the standard-grade rod-shaped silicon raw material is used as the target oxygen content, and 2X≤Y1≤4X.

[0088] In some embodiments, if it is estimated that the oxygen content at the crystal pulling end of the non-standard grade rod-shaped silicon raw material increases by X ppma, the reference process is used as the basis for regulation, and the distance between the bottom of the heater of the crystal pulling furnace and the guard plate press is increased by Y2mm during the crystal pulling process to correct the deviation of the oxygen content at the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target oxygen content, thereby facilitating the improvement of the quality of the single crystal silicon rods produced from the non-standard grade rod-shaped silicon raw material.

[0089] In a specific embodiment, the oxygen content at the pulling end of the standard-grade rod-shaped silicon raw material is used as the target oxygen content, 80X≤Y2≤105X.

[0090] In some embodiments, if it is estimated that the oxygen content at the crystal pulling end of the non-standard grade rod-shaped silicon raw material increases by X ng / g, the furnace pressure of the crystal pulling furnace during the crystal pulling process is reduced by Y3 torr based on the reference process to correct the deviation of the oxygen content at the crystal pulling end of the non-standard grade rod-shaped silicon raw material relative to the target oxygen content, thereby facilitating the improvement of the quality of single crystal silicon rods produced from the non-standard grade rod-shaped silicon raw material.

[0091] In a specific embodiment, the oxygen content at the pulling end of the standard-grade rod-shaped silicon raw material is used as the target oxygen content, and 1.3X≤Y3≤4.5X.

[0092] In some embodiments, if it is estimated that the oxygen content at the pulling end of the non-standard-grade rod-shaped silicon raw material increases by X ppma, the head cutting length of the single crystal silicon rod obtained by pulling is increased to Y4 mm based on the reference process to correct the deviation of the oxygen content at the pulling end of the non-standard-grade rod-shaped silicon raw material relative to the target oxygen content, thereby facilitating the improvement of the quality of the single crystal silicon rod obtained from the non-standard-grade rod-shaped silicon raw material.

[0093] In the embodiment of the present application, if it is estimated that the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material is reduced, the method for adjusting the reference process includes one or more of the following methods:

[0094] (1) Increasing the feed amount during the crystal pulling process: The metal impurities in the silicon material will be enriched at the bottom of the crucible during the pulling process due to the segregation effect. By increasing the feed amount, the number of crystal rods pulled can be reduced, the metal content in the crystal rod can be reduced, and the minority carrier lifetime can be increased.

[0095] (2) Increasing the tail cutting (reverse cutting) length of the single crystal silicon rod obtained by crystal pulling: Through reverse cutting, the crystal rod with low minority carrier lifetime can be cut off.

[0096] (3) Increase the silicon material retention rate after crystal pulling: The metal impurities in the silicon material will be enriched in the silicon liquid due to the segregation effect during the pulling process. The smaller the retention rate, the longer the crystal rod, the higher the metal content, and the lower the minority carrier lifetime.

[0097] In some embodiments, if it is estimated that the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material is reduced by A%, the tail cutting length of the single crystal silicon rod obtained by pulling is increased by Lmm based on the benchmark process to correct the deviation of the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material relative to the target minority carrier resistivity, thereby facilitating improving the quality of the single crystal silicon rods produced from the non-standard grade rod-shaped silicon raw material.

[0098] In a specific embodiment, the minority carrier resistivity at the pulling end of the standard-grade rod-shaped silicon raw material is used as the target minority carrier resistivity, 15A≤L≤25A.

[0099] In some embodiments, if it is estimated that the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material is reduced by A%, the silicon material retention rate after the crystal pulling is increased based on the benchmark process to correct the deviation of the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material relative to the target minority carrier resistivity.

[0100] In a specific embodiment, the minority carrier resistivity at the pulling end of the standard grade rod-shaped silicon raw material is taken as the target minority carrier resistivity, A% to 1.25A%.

[0101] In an embodiment of the present application, if the estimated change in the pulling end performance of the non-standard grade rod-shaped silicon raw material is an increase in carbon content, the method for adjusting the baseline process includes: increasing the tail cutting length of the single crystal silicon rod obtained by pulling to reduce its carbon content to a preset value.

[0102] Specifically, the preset value is determined according to the carbon inverse shear standard. In some embodiments, the preset value is ≤ 1.0E17 atoms / cm 3 .

[0103] In the embodiment of the present application, the precision of the classification of the rod-shaped silicon raw material grades can be adjusted as needed.

[0104] In some embodiments, the grades of the rod-shaped silicon raw materials are divided into Class I, Class II and Class III, and the grades of Class I, Class II and Class III are arranged from high to low; wherein,

[0105] In the type I rod-shaped silicon raw material, ω1≤0.3ng / g, ω2≤0.3ng / g, τ≥1800μs, NTU≤40;

[0106] In the II type rod-shaped silicon raw material, 0.3ng / g<ω1≤0.5ng / g, 0.3ng / g<ω2≤0.5ng / g, 1800μs>τ≥1500μs, 40<NTU≤50;

[0107] For Class III rod-shaped silicon raw materials, 0.5ng / g<ω1≤1ng / g, 0.5ng / g<ω2≤1ng / g, 1500μs>τ≥1200μs, 50<NTU≤60.

[0108] In the embodiment of the present application, the rod-shaped silicon raw material also contains donor impurities and acceptor impurities.

[0109] In some embodiments, the donor impurities in the rod-shaped silicon raw material include phosphorus, germanium, nitrogen, and the like.

[0110] In some embodiments, the acceptor impurities in the rod-shaped silicon raw material include boron, aluminum, magnesium, indium, and the like.

[0111] In some embodiments, the donor impurity concentration in the rod-shaped silicon raw material is ω3, the acceptor impurity concentration is ω4, the oxygen concentration is φ1, and the carbon concentration is φ2;

[0112] In the rod-shaped silicon raw materials of type I, type II and type III, ω3≤0.35ppba; and / or,

[0113] In the rod-shaped silicon raw materials of type I, type II and type III, ω4≤0.1ppba; and / or,

[0114] In the rod-shaped silicon raw materials of type I, type II and type III, φ1≤2*10 16 Atom / cm 3 and / or,

[0115] In the rod-shaped silicon raw materials of type I, type II and type III, φ2≤2*10 16 Atom / cm 3 .

[0116] In the above embodiment, the donor impurity concentration is tested by inductively coupled plasma emission spectroscopy. Generally speaking, the donor impurity concentration in the rod-shaped silicon raw material can be found in the COA test report issued by the manufacturer of the rod-shaped silicon raw material.

[0117] The test method for acceptor impurity concentration is: Inductively Coupled Plasma Optical Emission Spectrometry. Generally speaking, the acceptor impurity concentration in the rod-shaped silicon raw material can be found in the COA test report issued by the rod-shaped silicon raw material manufacturer.

[0118] The test methods for oxygen concentration include: mainly inert gas fusion infrared method and low temperature infrared detection method. Generally speaking, the oxygen concentration in the rod-shaped silicon raw material can be found in the COA test report issued by the rod-shaped silicon raw material manufacturer.

[0119] The test method for carbon concentration is infrared spectroscopy. Generally speaking, the carbon concentration in the rod-shaped silicon raw material can be found in the COA test report issued by the rod-shaped silicon raw material manufacturer.

[0120] In the above embodiment, the standard-grade rod-shaped silicon raw material is Class I rod-shaped silicon raw material. Those skilled in the art can estimate the changes in the crystal pulling end performance of Class II rod-shaped silicon raw materials and Class III rod-shaped silicon raw materials under the same preparation process based on Class I rod-shaped silicon raw materials.

[0121] In some embodiments, the estimated changes in the performance of the crystal pulling end of the non-standard grade rod-shaped silicon raw material are as follows: relative to Class I rod-shaped silicon raw material, the yield of the crystal pulling end of Class II rod-shaped silicon raw material is expected to decrease by 0.5kg to 1.5kg, specifically expected to decrease by 0.5kg, 0.8kg, 1kg, 1.2kg, 1.5kg or any value therebetween, and the yield of Class III rod-shaped silicon raw material is expected to decrease by 2.5 to 3.5kg, specifically expected to decrease by 2.5kg, 2.8kg, 3kg, 3.2kg, 3.5kg or any value therebetween.

[0122] In some embodiments, the estimated changes in the performance of the pulling end of the non-standard grade rod-shaped silicon raw material are as follows: relative to Class I rod-shaped silicon raw material, the minority carrier resistance ratio of the pulling end of Class II rod-shaped silicon raw material is expected to decrease by 3.5% to 4.5%, specifically expected to decrease by 3.5%, 3.8%, 4%, 4.2%, 4.5% or any value therebetween; the minority carrier resistance ratio of Class III rod-shaped silicon raw material is expected to decrease by 7% to 9%, specifically expected to decrease by 7%, 7.5%, 8%, 8.5%, 9% or any value therebetween.

[0123] In some embodiments, the estimated changes in the performance of the crystal pulling end of the non-standard grade rod-shaped silicon raw material are as follows: relative to Class I rod-shaped silicon raw material, the oxygen content at the crystal pulling end of Class II rod-shaped silicon raw material is expected to increase by 0ppma~0.01ppma, specifically expected to increase by 0ppma, 0.005ppma, 0.01ppma or any value therebetween; the oxygen content at the crystal pulling end of Class III rod-shaped silicon raw material is expected to increase by 0.25ppma~0.45ppma, specifically expected to increase by 0.25ppma, 0.3ppma, 0.35ppma, 0.4ppma, 0.45ppma or any value therebetween.

[0124] In some embodiments, the estimated changes in the performance of the crystal pulling end of the non-standard grade rod-shaped silicon raw material are as follows: relative to Class I rod-shaped silicon raw material, the carbon content at the crystal pulling end of Class II rod-shaped silicon raw material is expected to increase by 0.005ppma~0.015ppma, specifically expected to increase by 0.005ppma, 0.008ppma, 0.01ppma, 0.012ppma, 0.015ppma or any value therebetween; the carbon content at the crystal pulling end of Class III rod-shaped silicon raw material is expected to increase by 0.035ppma~0.045ppma, specifically expected to increase by 0.035ppma, 0.038ppma, 0.04ppma, 0.042ppma, 0.045ppma or any value therebetween.

[0125] The following specific examples are provided to further illustrate the embodiments of the present application. The embodiments of the present application are not limited to the following specific examples, and can be appropriately modified and implemented without changing the scope of the rights claimed in the present application.

[0126] Example 1

[0127] The classification of rod-shaped silicon raw materials is shown in Table 1 below:

[0128] Table 1

[0129]

[0130] The estimated performance of the crystal pulling end corresponding to different grades of rod-shaped silicon raw materials is shown in Table 2 below:

[0131] Table 2

[0132]

[0133] In the above Table 2, BSL means reference standard, that is, Table 2 presents the changes in the crystal pulling end performance of Class II and Class III silicon rod raw materials relative to Class I silicon rod raw materials under the same preparation process.

[0134] The preparation process conditions of the single crystal silicon rod corresponding to the type I rod-shaped silicon raw material are as follows:

[0135] The crucible height of the crystal pulling furnace is 680 mm, the distance between the bottom of the crucible heater and the guard plate is 30 mm, the crucible rotation speed is 8 rpm, the crystal pulling rate is 105 mm / h, the furnace pressure is 8 Torr, and the crucible retention rate is 30%.

[0136] The target crystal pulling end performance of the single crystal silicon rods of type II and type III rod-shaped silicon raw materials is shown in Table 3 below:

[0137] Table 3

[0138]

[0139] In the above Table 3, the performance of the crystal pulling end of the type II and type III rod-shaped silicon raw materials is based on the performance of the crystal pulling end of the type I rod-shaped silicon raw material as a reference standard.

[0140] The control method of the single crystal silicon rod preparation process of type II and type III rod-shaped silicon raw materials is shown in Table 4 below:

[0141] Table 4

[0142]

[0143]

[0144] In the above Table 4, the preparation process of single crystal silicon rods corresponding to Class 1 rod-shaped silicon raw materials is used as the basis for regulation, and the preparation process of single crystal silicon rods of Class II and Class III rod-shaped silicon raw materials is regulated, so as to reduce the deviation between the actual crystal pulling end performance and the target crystal pulling end performance of Class II and Class III rod-shaped silicon raw materials.

[0145] In Example 1, by combining Table 1 and Table 2, the difference between the actual crystal pulling end performance (using the benchmark process) of Class II and Class III rod-shaped silicon raw materials and the target crystal pulling end performance is first calculated, and then the benchmark process is adjusted according to the difference. The specific control methods and the effects of each control method on the crystal pulling end performance (shown in brackets in Table 4) are shown in Table 4.

[0146] By comparing Table 4 with Table 3, it can be seen that the crystal pulling end performance of the single crystal silicon rods obtained from Class II and Class III rod-shaped silicon raw materials using the regulated preparation process (the contents shown in brackets in Table 4) is close to the target crystal pulling end performance, or better than the target crystal pulling end performance, which also proves the reliability of the regulation method provided in the present application.

[0147] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for regulating the single crystal silicon rod preparation process based on the grade of rod-shaped silicon raw materials, characterized in that: include: The grades of the rod-shaped silicon raw materials are divided into multiple categories according to the matrix metal content ω1, the surface metal content ω2, the minority carrier lifetime mean τ and the turbidity NTU, and one of the multiple categories is selected as the standard grade, and the other categories are selected as non-standard grades; Obtaining a single crystal silicon rod preparation process matched with the standard-grade rod-shaped silicon raw material and using it as a benchmark process, and obtaining a crystal pulling end performance of the standard-grade rod-shaped silicon raw material, wherein the performance includes at least one of yield, minority carrier resistivity, oxygen content, and carbon content; Taking the performance of the crystal pulling end of the standard-grade rod-shaped silicon raw material as a comparison, estimating the change in the crystal pulling end performance of the non-standard-grade rod-shaped silicon raw material that is expected to be achieved by using the benchmark process; According to the estimated change in the crystal pulling end performance of the non-standard grade rod-shaped silicon raw material, the reference process is adjusted to obtain a single crystal silicon rod preparation process that matches the non-standard grade rod-shaped silicon raw material.

2. The control method according to claim 1, characterized in that: The grades of rod-shaped silicon raw materials are divided into at least Class I, Class II and Class III, and the grades of Class I, Class II and Class III are arranged from high to low; among them, In the type I rod-shaped silicon raw material, ω1≤0.3ng / g, ω2≤0.3ng / g, τ≥1800μs, NTU≤40; In the II type rod-shaped silicon raw material, 0.3ng / g<ω1≤0.5ng / g, 0.3ng / g<ω2≤0.5ng / g, 1800μs>τ≥1500μs, 40<NTU≤50; In the Class III rod-shaped silicon raw material, 0.5ng / g<ω1≤1ng / g, 0.5ng / g<ω2≤1ng / g, 1500μs>τ≥1200μs, 50<NTU≤60.

3. The control method according to claim 2, characterized in that: The donor impurity concentration in the rod-shaped silicon raw material is ω3, the acceptor impurity concentration is ω4, the oxygen concentration is φ1, and the carbon concentration is φ2; In the rod-shaped silicon raw materials of type I, type II and type III, ω3≤0.35ppba; and / or, In the rod-shaped silicon raw materials of type I, type II and type III, ω4≤0.1ppba; and / or, In the rod-shaped silicon raw materials of type I, type II and type III, φ1≤2*10 16 Atom / cm 3 and / or, In the rod-shaped silicon raw materials of type I, type II and type III, φ2≤2*10 16 Atom / cm 3 .

4. The control method according to claim 2, characterized in that: If it is estimated that the yield of the non-standard grade silicon rod-shaped raw material at the pulling end is reduced by m1 kg, the method for adjusting the reference process includes at least one of the following (1)-(2): (1) Increasing the amount of material fed during the crystal pulling process; (2) Increase the pulling rate during the crystal pulling process by v mm / h, v = (0.6 ~ 1.6) m.

5. The control method according to claim 2, characterized in that: If it is estimated that the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material is reduced, the method for adjusting the reference process includes at least one of the following (1)-(3): (1) Increase the amount of material fed during the crystal pulling process; (2) increasing the tail cutting length of the single crystal silicon rod obtained by crystal pulling; (3) Increase the silicon material retention rate after crystal pulling.

6. The control method according to claim 5, characterized in that: If it is estimated that the minority carrier resistivity at the pulling end of the non-standard grade rod-shaped silicon raw material is reduced by A%, the method for adjusting the reference process includes at least one of the following (1)-(3): (1) Increase the amount of material fed during the crystal pulling process; (2) increasing the length of the tail of the single crystal silicon rod obtained by pulling by L mm, 15A≤L≤25A; (3) The silicon material retention rate after crystal pulling is increased by A% to 1.25A%.

7. The control method according to claim 2, characterized in that: If the estimated oxygen content at the pulling end of the non-standard grade silicon rod raw material increases, the method for adjusting the baseline process includes at least one of the following (1)-(4): (1) reducing the speed of the crucible of the crystal pulling furnace during the crystal pulling process; (2) Increase the distance between the bottom of the heater of the crystal pulling furnace and the retaining plate during the crystal pulling process; (3) reducing the furnace pressure of the crystal pulling furnace during the crystal pulling process; (4) Increase the head cutting length of the single crystal silicon rod obtained by crystal pulling.

8. The control method according to claim 7, characterized in that: If it is estimated that the oxygen content at the pulling end of the non-standard grade silicon rod raw material increases by X ppma, the method for adjusting the baseline process includes at least one of the following (1)-(4): (1) increasing the rotation speed of the crucible of the crystal pulling furnace during the crystal pulling process by Y1 rpm, 2X≤Y1≤4X; (2) During the crystal pulling process, the distance between the bottom of the heater of the crystal pulling furnace and the protective plate pressing plate is increased by Y2 mm, 80X≤Y2≤105X; (3) The furnace pressure of the crystal pulling furnace is reduced by Y3 torr during the crystal pulling process, 1.3X≤Y3≤4.5X.

9. The control method according to claim 2, characterized in that: The standard-grade rod-shaped silicon raw material is a Class I rod-shaped silicon raw material, and the estimated change in the performance of the crystal pulling end of the non-standard-grade rod-shaped silicon raw material includes at least one of the following (1)-(4): (1) Compared with Class I rod-shaped silicon raw materials, the yield of Class II rod-shaped silicon raw materials at the crystal pulling end is expected to decrease by 0.5 to 1.5 kg, and the yield of Class III rod-shaped silicon raw materials is expected to decrease by 2.5 to 3.5 kg; (2) Compared with the type I silicon rod raw material, the minority carrier resistance ratio of the pulling end of the type II silicon rod raw material is expected to be reduced by 3.5% to 4.5%, and the minority carrier resistance ratio of the type III silicon rod raw material is expected to be reduced by 7% to 9%; (3) Compared with the Class I silicon rod raw material, the oxygen content of the crystal pulling end of the Class II silicon rod raw material is expected to increase by 0 ppma to 0.01 ppma, and the oxygen content of the crystal pulling end of the Class III silicon rod raw material is expected to increase by 0.25 ppma to 0.45 ppma; (4) Compared with Class I silicon rod raw material, the carbon content at the pulling end of Class II silicon rod raw material is expected to increase by 0.005 ppma to 0.015 ppma, and the carbon content at the pulling end of Class III silicon rod raw material is expected to increase by 0.035 ppma to 0.045 ppma.

10. The control method according to any one of claims 1 to 9, characterized in that: If the estimated change in the pulling end performance of the non-standard grade silicon rod raw material is an increase in carbon content, the method for adjusting the baseline process includes: increasing the tail cutting length of the single crystal silicon rod obtained by pulling to reduce its carbon content to a preset value.

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