Monocrystalline silicon rod and preparation method thereof, silicon wafer and solar cell

Abstract

The invention provides a silicon single crystal rod and a preparation method thereof, a silicon wafer and a solar cell. The invention provides a silicon single crystal rod. The silicon single crystal rod contains a hydrogen element. The ratio of the resistivity of the head of the monocrystalline silicon rod to the resistivity of the tail of the monocrystalline silicon rod is 0.8-2.0; and the dislocation density of the silicon single crystal rod meets the condition that (rho1-rho2) / rho1 is greater than or equal to-80% and less than or equal to 80%. The silicon single crystal rod provided by the invention is doped with the hydrogen element, so that the distribution uniformity of the doped element in the silicon single crystal rod is improved, the internal defects of the silicon single crystal rod in the growth process are reduced, and the overall mechanical property and electrical property of the silicon single crystal rod are improved by controlling the distribution of the dislocation density of the silicon single crystal rod within a reasonable interval.

Description

Technical Field

[0001] This application belongs to the field of semiconductor technology, and particularly relates to a single crystal silicon rod, a preparation method thereof, a silicon wafer, and a solar cell. Background Art

[0002] In photovoltaic cells, as the core material, the performance of a single crystal silicon rod directly affects the efficiency and stability of photovoltaic modules. However, in the current production process of single crystal silicon rods, due to the influence of raw materials and the crystal pulling process, the uniformity of the distribution of doped elements in different positions from the head to the tail of the formed single crystal silicon rod is poor. This makes the resistivity change degree inconsistent throughout the single crystal silicon rod, and due to the influence of the doping process, growth defects will occur during the growth of the single crystal silicon rod, seriously affecting the performance of photovoltaic cells in severe cases. Summary of the Invention

[0003] One object of this application is to provide a single crystal silicon rod, aiming to solve the problem of resistivity consistency of existing single crystal silicon rods.

[0004] Another object of this application is to provide a preparation method of a single crystal silicon rod. Another object of this application is to provide a silicon wafer and a solar cell.

[0005] The first embodiment of this application provides a single crystal silicon rod, which contains hydrogen element; the ratio of the resistivity of the head of the single crystal silicon rod to the resistivity of the tail of the single crystal silicon rod is 0.8 - 2.0; The dislocation density of the single crystal silicon rod satisfies: -80% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 80%, preferably -70% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 70%, further preferably -60% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 60%, further preferably -50% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 50%; Wherein, ρ 1 is the dislocation density of the tail of the single crystal silicon rod, and ρ 2 is the dislocation density of the head of the single crystal silicon rod.

[0006] In some embodiments, the dislocation density ρ 1 of the tail of the single crystal silicon rod is 4 - 3000 atom / cm 2 ; the dislocation density ρ 2is 4 to 3000 atom / cm 2 。

[0007] In some embodiments, the dislocation density in the middle of the single-crystal silicon rod is 4 to 500 atom / cm 2 。

[0008] In some embodiments, the resistivity of the head of the single-crystal silicon rod is 0.6 to 2.1 Ω·cm.

[0009] In some embodiments, the resistivity of the tail of the single-crystal silicon rod is 0.4 to 2.1 Ω·cm.

[0010] In some embodiments, the single-crystal silicon rod satisfies: 0.8 ≤ s 1 / s 2 ≤ 2; wherein, s 1 is the offset of the tail crystal of the single-crystal silicon rod in the <100> crystal orientation direction, and s 2 is the offset of the head crystal of the single-crystal silicon rod in the <100> crystal orientation direction.

[0011] In some embodiments, the offset s of the tail crystal of the single-crystal silicon rod in the <100> direction 1 is 0 to ±5°; the offset s of the head crystal of the single-crystal silicon rod in the <100> direction 2 is 0 to ±5°.

[0012] In some embodiments, along the radial direction of the single-crystal silicon rod, the single-crystal silicon rod has a center and an edge, and satisfies: 0 ≤ (C H1 - C H2 ) / C H2 ≤ 35%, preferably 0 ≤ (C H1 - C H2 ) / C H2 ≤ 30%, more preferably 0 ≤ (C H1 - C H2 ) / C H2 ≤ 25%, more preferably 0 ≤ (C H1 - C H2 ) / C H2 ≤ 20%; wherein, C H1 is the hydrogen element concentration at the edge, and C H2 is the hydrogen element concentration at the center.

[0013] In some embodiments, the hydrogen element concentration C at the edge H1 satisfies: 0.0001 cm -3 ≤ CH1 ≤ 1E+17 cm -3 , preferably 2E+13 cm -3 ≤ C H1 ≤ 7E+16 cm -3 , more preferably 1E+15 cm -3 ≤ C H1 ≤ 6E+16 cm -3 .

[0014] In some embodiments, the hydrogen element C at the center H2 satisfies: 0.0001 cm -3 ≤ C H2 ≤ 1E+17 cm -3 , preferably 2E+13 -3 ≤ C H2 ≤ 7E+16 cm-3, more preferably 1E+15 -3 ≤ C H2 ≤ 6E+16 cm -3 .

[0015] In some embodiments, along the radial direction of the single-crystal silicon rod, the distance between the center and the edge is R, and the hydrogen element content at a position 0.65R to 0.78R away from the center is 0.0001 to 1E+17 cm -3 , preferably 2E+13 to 7E+16 cm -3 , more preferably 1E+15 to 6E+16 cm -3 .

[0016] In some embodiments, the single-crystal silicon rod includes a head and a tail that are opposite to each other along the length direction. From the head to the tail, the single-crystal silicon rod is divided into N silicon rod units. The silicon rod unit has a first end and a second end that are opposite to each other along the length direction; the single-crystal silicon rod contains group III-V elements and hydrogen elements; the single-crystal silicon rod satisfies: K 1 = 1 - ((C n-1 - C H ) / (C n - C H ))), and 1E-3 ≤ |K 1 | ≤ 1E-2; wherein, C H represents the unit volume hydrogen element concentration of the single-crystal silicon rod; C n represents the unit volume group III-V element concentration at the second end of the nth silicon rod unit; C n-1 represents the unit volume group III-V element concentration at the first end of the nth silicon rod unit; n is an integer greater than or equal to 1; N is an integer greater than or equal to 1; K 1It represents the correction coefficient after the combined action of hydrogen element and group III-V elements, dimensionless.

[0017] In some embodiments, the concentration C of group III-V elements per unit volume of the silicon rod unit in the nth segment at the second end n satisfies: 1E+14 cm -3 ≤ C n ≤ 8E+15 cm -3 , preferably 2E+14 cm -3 ≤ C n ≤ 7E+15 cm -3 , more preferably 1E+15 cm -3 ≤ C n ≤ 7E+15 cm -3 .

[0018] In some embodiments, the concentration C of group III-V elements per unit volume of the silicon rod unit in the nth segment at the first end n-1 satisfies: 1E+14 cm -3 ≤ C n-1 ≤ 8E+15 cm -3 , preferably 2E+14 cm -3 ≤ C n-1 ≤ 7E+15 cm -3 , more preferably 1E+15 cm -3 ≤ C n-1 ≤ 7E+15 cm -3 .

[0019] In some embodiments, the group III-V elements include antimony element and phosphorus element, and the concentration ratio of the antimony element to the phosphorus element in the single-crystal silicon rod is 0.2 to 10, preferably 0.2 to 7, and more preferably 0.2 to 5.

[0020] The second embodiment of the present application provides a method for preparing a single-crystal silicon rod, including: Providing silicon raw materials, and obtaining a single-crystal silicon rod through steps of melting materials, recharging, stabilizing temperature, seeding, shoulder releasing, equal diameter, and ending; introducing hydrogen into the silicon raw materials in at least one of the steps of melting materials, recharging, stabilizing temperature, seeding, shoulder releasing, equal diameter, and ending; Wherein, before the single-crystal silicon rod is completely grown, the concentration of doping elements during the solidification process of the single-crystal silicon rod is adjusted to control the ratio of the resistivity of the head of the single-crystal silicon rod to the resistivity of the tail of the single-crystal silicon rod to satisfy 0.8 to 1.2, and the dislocation density of the single-crystal silicon rod satisfies 4 to 3000 atom / cm 2 .

[0021] In some embodiments, the method for preparing a single-crystal silicon rod further includes: Before the equal-diameter step, a metal element or alloy containing group III-V elements is added to the silicon raw material; Before the single-crystalline silicon rod is completely grown, the doping concentrations of hydrogen and group III-V elements during the solidification process of the single-crystalline silicon rod are adjusted to control the doping amount ratio of hydrogen and group III-V elements to satisfy: K 1 = 1 - ((C n-1 - C H ) / (C n - C H ))), and 1E-3 ≤ |K 1 | ≤ 1E-2; In the formula, C H represents the hydrogen element concentration per unit volume of the single-crystalline silicon rod; C n represents the group III-V element concentration per unit volume at the second end of the silicon rod unit of the nth segment; C n-1 represents the group III-V element concentration per unit volume at the first end of the silicon rod unit of the nth segment; n is an integer greater than or equal to 1.

[0022] In some embodiments, the time for introducing hydrogen into the silicon raw material is 0.5 to 82 h.

[0023] In some embodiments, the method for preparing a single-crystalline silicon rod further includes: after the recharging step, introducing a protective gas into the silicon raw material; wherein, the hydrogen and the protective gas form a mixed gas, and the volume percentage of hydrogen in the mixed gas is 1 to 90%, preferably 5 to 90%.

[0024] In some embodiments, the flow rate of hydrogen is 0.0001 to 180 slpm.

[0025] In some embodiments, the flow rate of the protective gas is 40 to 200 slpm.

[0026] In some embodiments, before the equal-diameter step starts after the recharging step ends, the volatilization rate η of the group III-V elements is controlled to satisfy: η = (H 1 / 100 mm) × 100% - 15%; wherein, H 1 is the liquid level distance in the single-crystal furnace, unit: mm; the volatilization rate η satisfies: 5% ≤ η ≤ 25%; the liquid level distance H 1 satisfies: 20 mm ≤ H 1 ≤ 40 mm.

[0027] In some embodiments, the single crystal furnace includes a top cover, the top cover is provided with a first ventilation hole and a second ventilation hole, the first ventilation hole is arranged around the second ventilation hole, the first ventilation hole is used to introduce the hydrogen gas into the single crystal furnace, and the second ventilation hole is used to introduce the protective gas into the single crystal furnace; wherein, the first ventilation hole has a first distance D from the center of the top cover 1 , and the second ventilation hole has a diameter D 2 , satisfying: 2D 1 >D 2 .

[0028] In some embodiments, a flow guide cylinder is arranged in the single crystal furnace, the flow guide cylinder has a maximum diameter D max , satisfying: D max ≥2D 1 ; the bottom of the flow guide cylinder has a third distance H from the top cover 3 , satisfying: 0.5m≤H 3 ≤1.5m.

[0029] The third embodiment of the present application provides a silicon wafer, which is prepared from the single crystal silicon rod in the above embodiment.

[0030] In some embodiments, the silicon wafer contains hydrogen element; the dislocation density of the silicon wafer is 4 - 500 atom / cm 2 ; the resistivity of the silicon wafer is 0.4 - 2.1 Ω·cm; the offset of the silicon wafer in the <100> crystal orientation direction is 0 - ±5°.

[0031] The fourth embodiment of the present application provides a solar cell, including a silicon substrate, and the silicon substrate is prepared from the silicon wafer in the above embodiment; wherein, the resistivity of the silicon substrate is 0.5 - 3 Ω•cm, and the thickness is 120 - 160 μm.

[0032] In some embodiments, the silicon substrate includes a doping region, and the doping region is doped with hydrogen element and group III-V elements; the concentration of hydrogen element in the doping region is 0.0001 cm -3 ~1E+17 cm -3 ; the concentration of group III-V elements in the doping region is 1E+14 cm -3 ~8E+15 cm -3 .

[0033] The present application provides a single-crystal silicon rod containing hydrogen element; the ratio of the resistivity of the head of the single-crystal silicon rod to the resistivity of the tail of the single-crystal silicon rod is 0.8 to 1.2; the dislocation density of the single-crystal silicon rod satisfies: -80% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 80%, preferably -70% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 70%, more preferably -60% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 60%, further preferably -50% ≤ (ρ 1 - ρ 2 ) / ρ 1 ≤ 50%; wherein, ρ 1 is the dislocation density of the tail of the single-crystal silicon rod, and ρ 2 is the dislocation density of the head of the single-crystal silicon rod. Due to the doping of hydrogen element in the single-crystal silicon rod provided by the present application, through the interaction with other doping elements, the effective segregation coefficient of metal elements in crystalline silicon is improved. While improving the uniformity of the distribution of doping elements in the single-crystal silicon rod, the internal lattice structure of the silicon rod is adjusted, and internal defects during the growth of the single-crystal silicon rod are reduced. By controlling the distribution of the dislocation density of the single-crystal silicon rod within a reasonable range, on the one hand, the concentrated distribution of dislocations can be avoided, and the overall mechanical properties of the single-crystal silicon rod can be improved. On the other hand, the electrical properties of different parts of the single-crystal silicon rod are also made more consistent, thereby improving the electrical properties of the single-crystal silicon rod.

[0034] It should be noted that the preparation methods of the silicon wafers and single-crystal silicon rods and the solar cells in the embodiments of the present application may include all the technical features and beneficial effects of the above single-crystal silicon rod, which will not be elaborated herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following described drawings are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] In order to more completely understand the present application and its beneficial effects, the following will be described in conjunction with the drawings, where the same reference numerals represent the same parts in the following description.

[0037] Figure 1 is a schematic structural diagram of a single-crystal furnace provided by an embodiment of the present application; Figure 2 is Figure 1Partial enlarged view of part A; Figure 3 Top view structural schematic diagram of a top cover of a single crystal furnace provided by an embodiment of the present application; Figure 4 Structural schematic diagram of a gas flow region in a single crystal furnace provided by an embodiment of the present application; Figure 5 Structural schematic diagram of a single crystal silicon rod divided into N silicon rod units provided by an embodiment of the present application.

[0038] Explanation of reference numerals: 10 - Draft tube, 11 - First section, 12 - Second section, 13 - Accommodating cavity, 14 - Through hole, 20 - Top cover, 21 - First ventilation hole, 22 - Second ventilation hole, 30 - Crucible, 40 - Molten silicon, 50 - First gas flow region, 60 - Second gas flow region, 61 - First region, 62 - Second region, 100 - Single crystal furnace. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application.

[0040] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "connection" 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 with each other; it can be directly connected, or indirectly connected through an intermediate medium, or indirectly connected through a pipeline or a conduit. It can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations. In the description of the present application, "a plurality of" means two or more, unless otherwise clearly specifically limited. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0041] In the field of photovoltaic single crystals, the lattice structure of single crystal silicon rods has a direct impact on battery performance. Defects and distortions in the lattice will cause cracks to expand when the crystal is subjected to force, leading to crystal breakage. At the same time, it is also easy to interfere with the movement of carriers in the crystal, reducing the carrier mobility. Controlling and reducing the defects and distortions in the lattice structure of single crystal silicon rods can make the migration of carriers in single crystal silicon smoother, reduce scattering, thereby improving carrier mobility, and can enhance the mechanical strength of single crystal silicon rods, making them less likely to break or fracture during subsequent cutting, grinding, polishing and other processing processes, as well as when subjected to external forces in actual applications, thereby improving the processing yield and reliability of single crystal silicon rods.

[0042] During the single crystal pulling process, the silicon raw material is doped with elements for the purpose of improving resistivity. During the doping process, due to the difference in atomic size between the doping elements and silicon atoms, when the doping elements enter the silicon lattice, local stress is easily generated, causing lattice distortion. In addition, too high a concentration of doping elements may cause impurity agglomeration or precipitation, destroying the integrity of the lattice and causing dislocations.

[0043] Therefore, the inventors discovered through research that adding hydrogen to single crystal silicon during the drawing and doping processes of single crystal silicon rods can promote the migration and rearrangement of hydrogen atoms, while passivating defects such as dislocations and suspensions in the silicon crystal, thereby reducing the adverse effects of doping elements on the mechanical and electrical properties of single crystal silicon rods.

[0044] The first embodiment of the present application provides a single crystal silicon rod, wherein the single crystal silicon rod contains hydrogen; the resistivity ratio of the head of the single crystal silicon rod to the resistivity ratio of the tail of the single crystal silicon rod is 0.8-2.0; The dislocation density of the single crystal silicon rod satisfies: -80%≤(ρ 1 -ρ 2 ) / ρ 1 ≤80%, preferably -70%≤(ρ 1 -ρ 2 ) / ρ 1 ≤70%, more preferably -60%≤(ρ 1 -ρ 2 ) / ρ 1 ≤60%, more preferably -50%≤(ρ 1 -ρ 2 ) / ρ 1 ≤50%; Among them, ρ 1 is the dislocation density at the tail of the single crystal silicon rod, ρ 2 is the dislocation density at the head of the single crystal silicon rod.

[0045] In this application, the head and tail of a single-crystal silicon rod refer to the following: in the Czochralski crystal growth method, when the diameter of the single-crystal silicon rod is pulled to the target diameter, the corresponding position is the isodiameter head position (the corresponding position is the head of the single-crystal silicon rod); when the single-crystal silicon rod is produced at the target diameter and reaches the target length, the corresponding position is the tail of the single-crystal silicon rod, and the position corresponding to the midpoint between the head and the tail is the middle of the single-crystal silicon rod. The head end face of the single-crystal silicon rod in this application refers to the radial cross-section at the head perpendicular to the rod length direction of the single-crystal silicon rod, and the tail end face of the single-crystal silicon rod refers to the radial cross-section at the tail perpendicular to the rod length direction of the single-crystal silicon rod. In this application, parameters such as the concentration, resistivity, oxygen content, dislocation density, and crystal direction offset of the head, middle, tail, head end face, and tail end face are all measured and calculated from the cross-section of the silicon rod.

[0046] It can be understood that during the doping process accompanied by the growth of the single-crystal silicon rod, hydrogen elements can interact with other doping elements to improve the effective segregation coefficient of metal elements in crystalline silicon, thereby making the doping concentration of metal elements in the single-crystal silicon rod more uniform, controlling the resistivity ratio between the head and the tail of the single-crystal silicon rod within a reasonable range, ensuring more consistent electrical properties of different parts of the single-crystal silicon rod, and thus improving the electrical properties of the single-crystal silicon rod; on the other hand, hydrogen can react with impurities in the silicon melt and expel them, and regulate the diffusion and distribution of metal elements. While reducing the dislocation density, it optimizes the crystal growth process, making the overall dislocations of the single-crystal silicon rod more evenly distributed axially, thereby avoiding the need to cut part of the single-crystal silicon rod due to excessive local dislocations and improving the yield rate of the single-crystal silicon rod.

[0047] It can be understood that the value of the resistivity ratio between the head and the tail of the single-crystal silicon rod can be any value of 0.8, 1.0, 1.2, 1.4, 1.6, 2.0 or the range between any two values. When the resistivity ratio between the head and the tail of the single-crystal silicon rod satisfies the above value range, it can further adjust the axial distribution of resistivity in the single-crystal silicon rod, reduce the resistivity difference between the head and the tail of the single-crystal silicon rod, and improve the consistency of resistivity in the single-crystal silicon rod to obtain ideal electrical properties. The relationship between the dislocation density at the head and the dislocation density at the tail of the single-crystal silicon rod (ρ 1 -ρ 2 ) / ρ 1 can take any value of -80%, -70%, -60%, -50%, -40%, -30%, -20%, -10%, 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or the range between any two values. When the relationship between the dislocation density at the head and the dislocation density at the tail of the single-crystal silicon rod (ρ 1 -ρ 2 ) / ρ 1When the above value ranges are satisfied, the overall mass distribution of the single-crystal silicon rod in the axial direction is uniform, and it has an ideal yield rate.

[0048] In some embodiments, the dislocation density ρ at the tail of the single-crystal silicon rod 1 is 4 - 3000 atom / cm 2 ; the dislocation density ρ at the head of the single-crystal silicon rod 2 is 4 - 3000 atom / cm 2 .

[0049] It can be understood that the value of the dislocation density ρ at the tail of the single-crystal silicon rod 1 (unit: atom / cm 2 ) can be any value among 4, 10, 20, 50, 80, 100, 200, 300, 500, 800, 1000, 1200, 1500, 1800, 2000, 2200, 2500, 2700, 3000 or the range between any two values. The value of the dislocation density ρ at the head of the single-crystal silicon rod 2 (unit: atom / cm 2 ) can be any value among 4, 10, 20, 50, 80, 100, 200, 300, 500, 800, 1000, 1200, 1500, 1800, 2000, 2200, 2500, 2700, 3000 or the range between any two values.

[0050] In some embodiments, the dislocation density in the middle of the single-crystal silicon rod is 4 - 500 atom / cm 2 .

[0051] It can be understood that the value of the dislocation density in the middle of the single-crystal silicon rod (unit: atom / cm 2 ) can be any value among 4, 10, 20, 50, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500 or the range between any two values.

[0052] When the dislocation density ρ at the head of the single-crystal silicon rod 2 , the dislocation density ρ at the tail 1 and the dislocation density in the middle satisfy the above value ranges, the single-crystal silicon rod can further have good mechanical properties and electron transport properties.

[0053] In some embodiments, the resistivity of the head of the single-crystal silicon rod is 0.6 - 2.1 Ω·cm.

[0054] It is understandable that the resistivity value (unit: Ω·cm) at the head of the single-crystalline silicon rod can be any value among 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.1 or the range between any two values.

[0055] In some embodiments, the resistivity of the tail of the single-crystalline silicon rod is 0.4 - 2.1 Ω·cm.

[0056] It is understandable that the resistivity value (unit: Ω·cm) at the tail of the single-crystalline silicon rod can be any value among 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.1 or the range between any two values.

[0057] In some embodiments, as the single-crystalline silicon rod grows, the concentration of the doping element in the single-crystalline silicon rod gradually increases, or the concentration of the doping element in the single-crystalline silicon rod gradually decreases. Therefore, the resistivity of the single-crystalline silicon rod in the axial direction shows a similar linear increasing trend or decreasing trend. When the resistivity of the head of the single-crystalline silicon rod and the resistivity of the tail of the single-crystalline silicon rod satisfy the above value range, it is possible to control the overall single-crystalline silicon rod to have a lower resistivity on the basis of ensuring a relatively uniform resistivity distribution of the single-crystalline silicon rod, thereby improving the electrical conductivity of the single-crystalline silicon rod.

[0058] In some embodiments, the single-crystalline silicon rod satisfies: 0.8 ≤ s 1 / s 2 ≤ 2; where s 1 is the offset of the tail crystal of the single-crystalline silicon rod in the <100> crystal orientation direction, and s 2 is the offset of the head crystal of the single-crystalline silicon rod in the <100> crystal orientation direction.

[0059] It is understandable that the offset s 1 of the tail crystal of the single-crystalline silicon rod in the <100> crystal orientation direction and the offset s 2The value of the ratio can be any value among 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 or the range between any two values. Among them, the crystal orientation refers to the axis with a specific atomic arrangement direction in the crystal, representing the direction with the most regular and symmetric atomic arrangement in the crystal structure. In the <100> crystal orientation direction, the atoms are arranged periodically and neatly, the atomic plane spacing is relatively large, the bonding mode between atoms is relatively simple and has high symmetry. Along this direction, the physical properties of the crystal, such as electrical properties, optical properties, etc., can show specific regularity and consistency. Therefore, silicon wafers are usually cut along the <100> crystal orientation direction, so that the atomic arrangement in the silicon wafers is beneficial to subsequent semiconductor process treatments. For example, when performing processes such as oxidation, lithography, and diffusion, more uniform thin film growth, more accurate pattern transfer, and more stable impurity diffusion characteristics can be obtained, thereby improving the consistency and reliability of device performance. The offset of the crystal in the <100> crystal orientation direction refers to the degree of deviation between the actual growth direction of the crystal and the target <100> crystal orientation. During the pulling process of the single crystal silicon rod, since the head is adjacent to the seed crystal and the seed crystal can better guide the crystal growth, the offset of the head of the single crystal silicon rod in the target <100> crystal orientation is relatively small. As the single crystal silicon rod grows, factors such as the thermal field stability and melt convection where the single crystal silicon rod is located change, and the increase in the impurity concentration of the remaining melt interferes with the regular arrangement of atoms, resulting in an increase in the crystal orientation offset. Therefore, there is a phenomenon that the offset of the tail of the single crystal silicon rod in the target <100> crystal orientation is relatively large. In addition, the inventors of the present application found in some other embodiments that there may be severe temperature fluctuations in the initial stage of the growth of the single crystal silicon rod, interfering with the early growth of the crystal, resulting in a large deviation in the crystal orientation of the head. As the single crystal silicon rod grows, the temperature in the single crystal furnace 100 tends to be stable. At this time, the offset of the tail of the single crystal silicon rod in the target <100> crystal orientation is relatively small. By controlling the value of s 1 / s 2 within a certain range, it can be ensured that the crystal direction of the single crystal silicon rod in the axial direction is in an overall uniform and orderly state, and it is ensured that the degree of deviation of the crystal direction of any position in the single crystal silicon rod from the target <100> crystal orientation is within the ideal range, thereby ensuring the consistency of the performance of each part of the single crystal silicon rod, making the crystal structure of the single crystal silicon rod more regular and having fewer defects, thereby improving the electrical properties and mechanical properties of the silicon wafers prepared by subsequent processes.

[0060] During the growth of a single-crystal silicon rod, with the help of a seed crystal and thermal field optimization, the crystal of the single-crystal silicon grows along the target crystal orientation <100> direction and is controlled within an ideal offset. By regulating the heating power in the single-crystal furnace 100 and the flow rate of the gas flowing in the single-crystal furnace 100 (such as hydrogen and protective gas), the temperature gradients in the radial and axial directions of the thermal field are ensured to be stable. The stable thermal field keeps the solid-liquid interface of the single-crystal silicon flat, inhibits the growth of polycrystals, ensures that atoms are arranged in the established direction of the seed crystal, avoids the deviation of the crystal growth direction due to thermal stress, and thus realizes the control of the crystal growth direction within the allowable offset. In addition, the growth direction of the crystal can also be optimized by adjusting the crystal pulling speed and optimizing the flow of the silicon melt. Appropriately reducing the crystal pulling speed can make the crystal growth interface flatter, and atoms have more sufficient time to be regularly arranged on the interface, which is beneficial to growth along the target direction; if the crystal pulling speed is too fast, the temperature gradient at the interface increases, which easily leads to the deviation of the crystal growth direction. The flow of the silicon melt can optimize the melt convection pattern by reasonably designing the rotation speed, temperature field, and magnetic field intensity of the crucible 30, thereby obtaining high-quality single-crystal silicon.

[0061] In some embodiments, the offset s of the tail crystal of the single-crystal silicon rod in the <100> crystal orientation direction 1 is 0 to ±5°; the offset s of the head crystal of the single-crystal silicon rod in the <100> crystal orientation direction 2 is 0 to ±5°.

[0062] It can be understood that the value of the offset s of the tail crystal of the single-crystal silicon rod in the <100> crystal orientation direction 1 (unit: °) can be any value in -5, -3, -2, -1, 0, 1, 2, 3, 5 or the range between any two values; the value of the offset s of the head crystal of the single-crystal silicon rod in the <100> crystal orientation direction 2 (unit: °) can be any value in -5, -3, -2, -1, 0, 1, 2, 3, 5 or the range between any two values. When the offsets of the head and tail crystals of the single-crystal silicon rod in the <100> crystal orientation direction satisfy the above value range, the stress distribution inside the single-crystal silicon rod is relatively uniform, defects are not likely to occur, the carrier mobility of the prepared silicon wafer is more stable, and it has good lithography accuracy, thereby improving the performance of semiconductor devices. The offset of the single-crystal silicon in the <100> crystal orientation direction can be detected by X-ray diffraction method. By measuring the position and intensity of the diffraction peak, the crystal orientation and crystal plane spacing of the crystal can be determined, and then the crystal orientation offset can be calculated. It should be noted that the offset of the single-crystal silicon mentioned in this application in the <100> crystal orientation direction can also be detected by other detection methods, which will not be elaborated here.

[0063] In some embodiments, along the radial direction of the single-crystal silicon rod, the single-crystal silicon rod has a center and an edge, satisfying: 0≤(CH1 -C H2 ) / C H2 ≤ 35%, preferably 0 ≤ (C H1 -C H2 ) / C H2 ≤ 30%, more preferably 0 ≤ (C H1 -C H2 ) / C H2 ≤ 25%, more preferably 0 ≤ (C H1 -C H2 ) / C H2 ≤ 20%; Wherein, C H1 is the hydrogen element concentration at the edge, and C H2 is the hydrogen element concentration at the center.

[0064] In this application, the center of the single crystal silicon rod refers to the center point of any radial cross-sectional pattern of the single crystal silicon rod, and the edge of the single crystal silicon rod refers to the edge point of any radial cross-sectional pattern of the single crystal silicon rod. For example, if the radial cross-section of the single crystal silicon rod is circular, the center of the single crystal silicon rod is the center of the radial cross-section, and the edge of the single crystal silicon rod is any point on the circumference of the radial cross-section.

[0065] It can be understood that the value of (C H1 -C H2 ) / C H2 can be any value among 0, 5%, 10%, 15%, 20%, 25%, 30%, 35% or the range between any two values. When (C H1 -C H2 ) / C H2 meets the above value range, the hydrogen element has an ideal radial concentration distribution in the single crystal silicon rod, which can effectively reduce the recombination effect of dislocations and vacancies and other defects on carriers in the entire radial range of the single crystal silicon rod, thereby improving the minority carrier lifetime. At the same time, it helps to improve the stress distribution inside the single crystal silicon rod, so that the stress is more evenly released on the entire cross-section of the single crystal silicon rod, thereby enhancing the mechanical properties of the silicon rod.

[0066] In some embodiments, the hydrogen element concentration C H1 at the edge satisfies: 0.0001 cm -3 ≤ C H1 ≤ 1E+17 cm -3 , preferably 2E+13 cm -3 ≤ C H1 ≤ 7E+16 cm -3 , more preferably 1E+15 cm -3 ≤ C H1 ≤ 6E+16 cm -3 .

[0067] It is understandable that the hydrogen element concentration C at the edge H1 can take values (unit: cm -3 ) which can be any value among 0.0001, 1, 1E+2, 1E+3, 1E+4, 1E+5, 1E+6, 1E+7, 1E+8, 1E+9, 1E+10, 1E+11, 1E+12, 5E+12, 2E+13, 7E+13, 3E+14, 8E+14, 1E+15, 5E+15, 1E+16, 6E+16, 1E+17 or the range between any two values.

[0068] In some embodiments, the hydrogen element C at the center H2 satisfies: 0.0001 cm -3 ≤ C H2 ≤ 1E+17 cm -3 , preferably 2E+13 cm -3 ≤ C H2 ≤ 7E+16 cm -3 , more preferably 1E+15 cm -3 ≤ C H2 ≤ 6E+16 cm -3 .

[0069] It is understandable that the hydrogen element C at the center H2 can take values (unit: cm -3 ) which can be any value among 0.0001, 1, 1E+2, 1E+3, 1E+4, 1E+5, 1E+6, 1E+7, 1E+8, 1E+9, 1E+10, 1E+11, 1E+12, 5E+12, 2E+13, 7E+13, 3E+14, 8E+14, 1E+15, 5E+15, 1E+16, 6E+16, 1E+17 or the range between any two values.

[0070] In some embodiments, along the radial direction of the single-crystal silicon rod, the distance between the center and the edge is R, and the hydrogen element content at a distance of 0.65R to 0.78R from the center is 0.0001 to 1E+17 cm -3 , preferably 2E+13 to 7E+16 cm -3 , more preferably 1E+15 to 6E+16 cm -3 .

[0071] It is understandable that the hydrogen element content at a distance of 0.65R to 0.78R from the center can take values (unit: cm -3) It can be any value among 0.0001, 1, 1E+2, 1E+3, 1E+4, 1E+5, 1E+6, 1E+7, 1E+8, 1E+9, 1E+10, 1E+11, 1E+12, 5E+12, 2E+13, 7E+13, 3E+14, 8E+14, 1E+15, 5E+15, 1E+16, 6E+16, 1E+17 or the range between any two values.

[0072] When the hydrogen element concentration C at the edge H1 , the hydrogen element C at the center H2 , and the hydrogen element content at a distance of 0.65R to 0.78R from the center satisfy the above range, the interaction between hydrogen and other doping elements can be realized, the effective segregation coefficient of metal elements doped in crystalline silicon in silicon can be improved, so as to enhance the distribution uniformity of the resistivity of monocrystalline silicon; at the same time, the doping of hydrogen in silicon can introduce additional electrons, form chemical bonds between hydrogen atoms and silicon, and these additional electrons can increase the conductivity of silicon materials, thereby reducing the resistivity. Hydrogen can also interact with impurities or defects in silicon materials, reduce the interference of impurities or defects on electron transport, and further improve the conductivity and resistivity consistency. In addition, part of the hydrogen element can also play a role in passivating and absorbing impurities and defects in the silicon crystal, which can improve the minority carrier lifetime of the single crystal rod silicon and at the same time adjust the distribution uniformity of the radial and axial resistivity of the single crystal silicon rod. However, if too much hydrogen element enters the lattice of monocrystalline silicon, it may also introduce additional impurity energy levels in the energy band structure of the crystal, change the way of electron transition, thus affecting the generation and recombination process of carriers, and further changing the electrical properties of the crystal, resulting in a decrease in the conductivity of the single crystal silicon rod. Therefore, controlling the hydrogen element concentration C at the edge H1 , the hydrogen element C at the center H2 , and the hydrogen element content at a distance of 0.65R to 0.78R from the center are within the above value range, which can further avoid the influence of too high hydrogen element doping concentration on the conductivity of the single crystal silicon rod.

[0073] In some embodiments, as Figure 5 shown, the single crystal silicon rod includes a head and a tail opposite to each other in the length direction. From the head to the tail, the single crystal silicon rod is divided into N silicon rod units, and the silicon rod unit has a first end and a second end opposite to each other in the length direction; the single crystal silicon rod contains group III-V elements and hydrogen elements; the single crystal silicon rod satisfies: K 1 = 1 - ((C n-1 - C H )) / (C n - C H ), and 1E-3 ≤ |K 1 | ≤ 1E-2; wherein, C Hrepresents the hydrogen element concentration per unit volume of the single-crystal silicon rod; C n represents the concentration of group III-V elements per unit volume at the second end of the silicon rod unit in the nth segment; C n-1 represents the concentration of group III-V elements per unit volume at the first end of the silicon rod unit in the nth segment; n is an integer greater than or equal to 1; N is an integer greater than or equal to 1; K 1 is the concentration ratio coefficient of hydrogen element to group III-V elements, dimensionless. It can be understood that n ≤ N.

[0074] It can be understood that in the single-crystal silicon rod provided in this embodiment, due to the simultaneous doping of group III-V elements and hydrogen, through the interaction between hydrogen and group III-V elements, the effective segregation coefficient of the group III-V element dopants in crystalline silicon is improved. When it satisfies the range of 1E-3 ≤ |K 1 | ≤ 1E-2, the oxygen content and lifetime of the single-crystal silicon rod can be improved and the resistivity can be accurately controlled, making the resistivity of the single-crystal silicon rod and its derivatives more uniformly concentrated, and realizing the improvement of the resistivity consistency of the silicon rod.

[0075] In some embodiments, the value of N is based on the actual length of the single-crystal silicon rod. For example, when N = 1, the single-crystal silicon rod is the entire one segment, that is, the first end corresponds to the head position and the second end corresponds to the tail position. Of course, when N takes an integer greater than 1, the single-crystal silicon rod is at least divided into two segments, that is, the head of each segment corresponds to the position of the first end and the tail of each segment corresponds to the position of the second end.

[0076] In some embodiments, the dimensions of any one of the N silicon rod units in the length direction are equal to each other. It can be understood that when the dimensions are equal to each other, each silicon rod unit can be regarded as the same unit structure. Therefore, through the value of K 1 the uniformity of the doped group III-V elements and hydrogen in each silicon rod unit can be determined.

[0077] In some embodiments, the size of any one of the N silicon rod units in the length direction is A mm, satisfying: 1 ≤ A ≤ 50. For example, A can be any value among 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, 36 mm, 37 mm, 38 mm, 39 mm, 40 mm, 41 mm, 42 mm, 43 mm, 44 mm, 45 mm, 46 mm, 47 mm, 48 mm, 49 mm, 50 mm or the range between any two values. The length of the silicon rod unit is jointly determined by the overall length of the single-crystal silicon rod and the number of segments to be separated.

[0078] Furthermore, the preferred size A mm can be in the range between 5 mm and 20 mm; the more preferred size A mm can be in the range between 10 mm and 15 mm.

[0079] In some embodiments, n is an integer greater than or equal to 1 and less than or equal to 6000, and N is an integer greater than or equal to 1 and less than or equal to 6000. In some other embodiments, n is an integer greater than or equal to 1 and less than or equal to 120, and N is an integer greater than or equal to 1 and less than or equal to 120. For example, taking the total length of the single-crystal silicon rod as 6000 mm as an example, when it needs to be divided into 1 segment, N takes 6000, and when it needs to be divided into 50 segments, N takes 120; similarly, the total length of the single-crystal silicon rod can also be any one of 5000 mm, 4000 mm, 3000 mm, 2000 mm, 1000 mm, 500 mm or the range between any two of them.

[0080] In some embodiments, more preferably, n is an integer greater than or equal to 5 and less than or equal to 1000, and N is an integer greater than or equal to 5 and less than or equal to 1000. In some other embodiments, n is an integer greater than or equal to 10 and less than or equal to 500, and N is an integer greater than or equal to 10 and less than or equal to 500.

[0081] In some embodiments, the concentration C of hydrogen element per unit volume in the single-crystal silicon rod H satisfies: 0.0001 cm -3 ≤ C H ≤ 1E+17 cm -3 . When C HWhen the above ranges are satisfied, the interaction with group III-V elements can be achieved, improving the effective segregation coefficient of group III-V elements doped in crystalline silicon in silicon, so as to enhance the resistivity consistency of monocrystalline silicon; at the same time, the doping of hydrogen in silicon can introduce additional electrons, forming chemical bonds between hydrogen atoms and silicon. These additional electrons can increase the conductivity of silicon materials, thereby reducing the resistivity. Hydrogen can also interact with impurities or defects in silicon materials, reducing the interference of impurities or defects on electron transport, and further improving the conductivity and resistivity consistency. In addition, some hydrogen elements can also passivate and absorb impurities and defects in silicon crystals, which can increase the minority carrier lifetime of monocrystalline silicon rods and at the same time adjust the uniformity of the radial and axial resistivity distributions of monocrystalline silicon rods.

[0082] In some embodiments, the concentration C of hydrogen elements per unit volume in the monocrystalline silicon rod H can be 2E+13 cm -3 、3E+13 cm -3 、4E+13 cm -3 、5E+13 cm -3 、8E+13 cm -3 、1E+14 cm -3 、2E+14 cm -3 、5E+14 cm -3 、8E+14 cm -3 、1E+15 cm -3 、2E+15 cm -3 、5E+15 cm -3 、8E+15 cm -3 、1E+16 cm -3 、5E+16 cm -3 、6E+16 cm -3 、7E+16 cm -3 、1E+17 cm -3 or any value within the range between any two of these values.

[0083] In some embodiments, the concentration C of group III-V elements per unit volume at the second end of the silicon rod unit in the nth segment n satisfies: 1E+14 cm -3 ≤ C n ≤ 8E+15 cm -3 . For example, it can be 1E+14 cm -3 、2E+14 cm -3 、3E+14 cm -3 、4E+14 cm -3 、5E+14 cm -3 、6E+14 cm -3 、7E+14 cm -3 、8E+14 cm-3 , 9E+14 cm -3 , 1E+15 cm -3 , 2E+15 cm -3 , 3E+15 cm -3 , 4E+15 cm -3 , 5E+15 cm -3 , 6E+15 cm -3 , 7E+15 cm -3 , 8E+15 cm -3 Any value within or range between any two values among

[0084] In some embodiments, the concentration C of group III-V elements per unit volume at the second end of the silicon rod unit of the nth segment n satisfies: 2E+14 cm -3 ≤ C n ≤ 7E+15 cm -3 .

[0085] In some embodiments, the concentration C of group III-V elements per unit volume at the second end of the silicon rod unit of the nth segment n satisfies: 1E+15 cm -3 ≤ C n ≤ 7E+15 cm -3 .

[0086] In some embodiments, the concentration C of group III-V elements per unit volume at the first end of the nth silicon rod unit n-1 satisfies: 1E+14 cm -3 ≤ C n ≤ 8E+15 cm -3 . For example, it can be 1E+14 cm -3 , 2E+14 cm -3 , 3E+14 cm -3 , 4E+14 cm -3 , 5E+14 cm -3 , 6E+14 cm -3 , 7E+14 cm -3 , 8E+14 cm -3 , 9E+14 cm -3 , 1E+15 cm -3 , 2E+15 cm -3 , 3E+15 cm -3 , 4E+15 cm -3 , 5E+15 cm -3 , 6E+15 cm -3 , 7E+15 cm -3 , 8E+15 cm -3 Any value within or range between any two values among

[0087] In some embodiments, the concentration C of group III-V elements per unit volume at the first end of the nth silicon rod unit n-1 satisfies: 2E+14 cm -3 ≤ C n-1 ≤ 7E+15 cm -3 .

[0088] In some embodiments, the concentration C of group III-V elements per unit volume at the first end of the nth silicon rod unit n-1 satisfies: 1E+15 cm -3 ≤ C n-1 ≤ 7E+15 cm -3 .

[0089] It can be understood that when C n satisfies 2E+14 cm -3 ≤ C n ≤ 7E+15 cm -3 , and C n-1 satisfies 1E+14 cm -3 ≤ C n ≤ 8E+15 cm -3 , the doping of group III-V elements in the silicon rod can introduce additional electrons or holes, changing the conductivity of the silicon material. These additional carriers can increase the conductivity of the silicon material, thereby reducing the resistivity. At the same time, the doping of group III-V elements can also interact with the hydrogen atoms in the silicon material to form a composite doping system, further adjusting the conductivity and resistivity of the silicon material.

[0090] In some embodiments, the concentration C of group III-V elements per unit volume at the second end of the nth silicon rod unit n satisfies: 1E+14 cm -3 ≤ C n ≤ 8E+15 cm -3 , preferably 2E+14 cm -3 ≤ C n ≤ 7E+15 cm -3 , more preferably 1E+15 cm -3 ≤ C n ≤ 7E+15 cm -3 .

[0091] In some embodiments, the concentration C of group III-V elements per unit volume at the first end of the nth silicon rod unit n-1 satisfies: 1E+14 cm -3 ≤ C n ≤ 8E+15 cm -3 , preferably 2E+14 cm -3 ≤ C n ≤ 7E+15 cm-3 , more preferably 1E+15 cm -3 ≤ C n ≤ 7E+15 cm -3 .

[0092] In some embodiments, the group III-V elements may be at least one element selected from antimony, phosphorus, gallium, boron, and arsenic, preferably antimony and phosphorus elements.

[0093] In some embodiments, the concentration ratio of antimony element to phosphorus element in the single crystal silicon rod is 0.2 to 10.

[0094] The N-type single crystal mainly controls the resistivity by doping elements of the fifth main group. The higher the doping concentration, the more free electrons in the single crystal silicon rod, the stronger its conductivity, and the lower the resistivity. Affected by the segregation of doping elements, during the single crystal preparation process, the concentration of doping elements in the melt continuously accumulates, and the concentration of doping elements gradually increases. More and more doping elements enter the single crystal along the axial direction, resulting in a gradual decrease in resistivity along the axial direction. The axial concentration of the resistivity of the single crystal silicon rod can be characterized by the ratio of the resistivity of the head and tail of the single crystal silicon rod. The closer the ratio of the resistivity of the head and tail is to 1, the better the axial uniformity of the single crystal silicon rod. Antimony and phosphorus belong to the fifth main group elements, and they have a combined effect on the resistivity of single crystal silicon through co-doping. Since the segregation coefficients of antimony and phosphorus are different, by controlling the doping amount ratio of antimony element to phosphorus element in the single crystal silicon rod, the doping concentration during the solidification process of the single crystal silicon rod can be adjusted, the element concentration ratio at different positions of the whole single crystal can be regulated, and then the distribution of resistivity along the axis of the single crystal silicon rod can be adjusted, reducing the difference in resistivity between the head and tail of the single crystal silicon rod, and improving the consistency of resistivity in the single crystal silicon rod to obtain ideal electrical properties.

[0095] It can be understood that the value of the concentration ratio of antimony element to phosphorus element in the single crystal silicon rod can be any value among 0.2, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10 or the range between any two values. When the concentration ratio of antimony element to phosphorus element in the single crystal silicon rod satisfies the above value range, it can ensure an ideal ratio of resistivity between the head and tail in the single crystal silicon rod, thereby improving the axial uniformity of the single crystal silicon rod.

[0096] In some embodiments, the concentration ratio of antimony element to phosphorus element in the single crystal silicon rod is 0.2 to 7.

[0097] It is understandable that the value of the concentration ratio of antimony element to phosphorus element in the single-crystal silicon rod can be any value among 0.2, 0.8, 1.6, 2.4, 3.2, 4.1, 4.8, 5.6, 6.4, 7 or the range between any two values. When the concentration ratio of antimony element to phosphorus element in the single-crystal silicon rod satisfies the above value range, the resistivity ratio of the head and tail in the single-crystal silicon rod can be further optimized, thereby improving the axial uniformity of the single-crystal silicon rod.

[0098] In some embodiments, the concentration ratio of antimony element to phosphorus element in the single-crystal silicon rod is further preferably 0.2 - 5.

[0099] It is understandable that the value of the concentration ratio of antimony element to phosphorus element in the single-crystal silicon rod can be any value among 0.2, 0.5, 1.5, 2.5, 3.5, 4.5, 5 or the range between any two values. When the concentration ratio of antimony element to phosphorus element in the single-crystal silicon rod satisfies the above value range, the resistivity ratio of the head and tail in the single-crystal silicon rod can be further optimized, thereby improving the axial uniformity of the single-crystal silicon rod.

[0100] In some embodiments, the concentration of phosphorus element is 3.00E+14 cm -3 to 1.00E+16 cm -3 .

[0101] It is understandable that the value of the concentration of phosphorus element (unit: cm -3 ) can be any value among 3.00E+14, 6.00E+14, 1.00E+15, 1.50E+15, 3.00E+15, 4.50E+15, 6.00E+15, 7.50E+15, 9.00E+15, 1.00E+16 or the range between any two values. Doping with phosphorus element can significantly reduce the resistivity of single-crystal silicon. Controlling the doping concentration of phosphorus element to satisfy the above value range can maintain the integrity of the crystal lattice structure of single-crystal silicon while reducing the resistivity of single-crystal silicon.

[0102] In some embodiments, the concentration of antimony element is 6.00E+14 cm -3 to 1.60E+16 cm -3 .

[0103] It is understandable that the value of the concentration of antimony element (unit: cm -3It can be any value among 6.00E+14, 1.50E+15, 3.00E+15, 4.50E+15, 6.00E+15, 7.50E+15, 9.00E+15, 1.10E+16, 1.25E+16, 1.40E+16, 1.60E+16 or the range between any two values. Since the segregation coefficient of antimony is less than that of phosphorus, the influence of antimony doping on the lattice structure of single-crystalline silicon is relatively small. Controlling the doping concentration of antimony element to meet the above value range can further reduce the resistivity of single-crystalline silicon.

[0104] The second embodiment of the present application provides a method for preparing a single-crystalline silicon rod, including: Providing silicon raw materials, and obtaining a single-crystalline silicon rod through steps of material melting, recharging, temperature stabilization, crystal seeding, shoulder releasing, equal diameter, and tailing; during at least one of the steps of material melting, recharging, temperature stabilization, crystal seeding, shoulder releasing, equal diameter, and tailing, introducing hydrogen into the silicon raw materials; Among them, before the single-crystalline silicon rod is completely grown, adjusting the doping element concentration during the solidification process of the single-crystalline silicon rod to control the ratio of the resistivity of the head of the single-crystalline silicon rod to the resistivity of the tail of the single-crystalline silicon rod to meet 0.8~1.2, and the dislocation density of the single-crystalline silicon rod to meet 4~3000atom / cm 2 .

[0105] It can be understood that adjusting the doping element concentration during the solidification process of the single-crystalline silicon rod can be achieved by adjusting the time and flow rate of introducing hydrogen.

[0106] In some embodiments, the method for preparing a single-crystalline silicon rod further includes: Before the equal diameter step, adding a metal single substance or alloy containing group III-V elements to the silicon raw materials; Before the single-crystalline silicon rod is completely grown, adjusting the doping concentrations of hydrogen element and group III-V elements during the solidification process of the single-crystalline silicon rod to control the doping amount ratio of hydrogen element and group III-V elements to meet: K 1 =1-((C n-1 -C H ) / (C n -C 氢 ))), and 1E-3≤|K 1 |≤1E-2; In the formula, C H represents the hydrogen element concentration per unit volume of the single-crystalline silicon rod; C n represents the group III-V element concentration per unit volume at the second end of the nth silicon rod unit; C n-1 represents the group III-V element concentration per unit volume at the first end of the nth silicon rod unit; n is an integer greater than or equal to 1.

[0107] In some embodiments, before melting the materials, the silicon raw materials are placed in the single crystal furnace 100.

[0108] In some embodiments, after the silicon raw materials are placed in the single crystal furnace 100, at least one step of melting the materials, recharging, stabilizing the temperature, seeding, necking down, constant diameter, and ending is performed to obtain a single crystal ingot; before the constant diameter step, antimony element and phosphorus element are added to the silicon raw materials, and the antimony element and phosphorus element can be added simultaneously; before the constant diameter step, when adding antimony element and phosphorus element to the silicon raw materials, the antimony element and phosphorus element can also be added non-simultaneously.

[0109] In some embodiments, before the constant diameter step, adding antimony element and phosphorus element to the silicon raw materials can be understood as adding antimony element and phosphorus element to the silicon raw materials before seeding. Before seeding, when adding antimony element and phosphorus element to the silicon raw materials, the antimony element and phosphorus element can be added simultaneously; before seeding, when adding antimony element and phosphorus element to the silicon raw materials, the antimony element and phosphorus element can also be added non-simultaneously.

[0110] In some embodiments, before seeding, when adding antimony element and phosphorus element to the silicon raw materials, it can be to add antimony element and phosphorus element to the silicon raw materials simultaneously after recharging and before seeding. Further, after recharging and before seeding, the antimony element and phosphorus element are added to the silicon raw materials simultaneously through a doping device.

[0111] When adding antimony element and phosphorus element simultaneously, the doping effects of the two will be superimposed on each other, more significantly reducing the resistivity in the crystal.

[0112] In some embodiments, the time for introducing hydrogen into the silicon raw materials is 0.5 - 82 h.

[0113] It can be understood that the time for introducing hydrogen refers to the total time for introducing hydrogen during the growth of each single crystal into a single crystal ingot. The value of the time for introducing hydrogen into the silicon raw materials (unit: h) can be any value among 0.5, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 82 or the range between any two values. By controlling the time for introducing hydrogen to meet the above value range, the doping concentration and doping uniformity of hydrogen are at an ideal level.

[0114] In some embodiments, the time for introducing hydrogen into the silicon raw materials satisfies: t 总 =t 1 +t 2 +t 3 +t 4 +t 5 +t 6 +t 7 and 0.5 h ≤ t总 ≤82 h; Wherein, t 总 is the total time of introducing hydrogen, t 1 is the time of introducing hydrogen in the material preparation stage, t 2 is the time of introducing hydrogen in the re - feeding stage, t 3 is the time of introducing hydrogen in the temperature - stabilizing stage, t 4 is the time of introducing hydrogen in the seed - crystal pulling stage, t 5 is the time of introducing hydrogen in the shoulder - broadening stage, t 6 is the time of introducing hydrogen in the constant - diameter stage, t 7 is the time of introducing hydrogen in the finishing stage.

[0115] In some embodiments, the time of introducing hydrogen into the silicon raw material further satisfies: t 1 : t 2 : t 3 : t 4 : t 5 : t 6 : t 7 = (0 - 10):(0 - 8):(0 - 2):(0 - 1.5):(0 - 3):(0 - 55):(0 - 2).

[0116] Specifically, t 1 , t 2 , t 3 , t 4 , t 5 , t 6 , t 7 are not simultaneously 0. For example, the ratio of t 1 : t 2 : t 3 : t 4 : t 5 : t 6 : t 7 can be any value in 2:2:0:0:0:0:0, 0:2:1.5:1:3:50:2, 1:2:1:0:0:0:0, 0:0:1:1.5:2:55:0, 0:8:1:1.5:3:10:1 or the range between any two values.

[0117] In some embodiments, the time of introducing hydrogen into the silicon raw material further satisfies: t 1 : t 2 : t 3 : t 4 : t 5 : t 6 : t 7= (0.00001~10) : (0.00001~8) : (0.00001~2) : (0.00001~1.5) : (0.00001~3) : (0.00001~55) : (0.00001~2).

[0118] In some embodiments, it is preferred to introduce hydrogen gas into the silicon raw material after the recharging step is completed.

[0119] It can be understood that when hydrogen gas is introduced during the temperature stabilization stage, hydrogen gas can act as a heat transfer medium to make the temperature of the environment where the silicon raw material is located more uniform and stable, preventing local overheating or overcooling of the silicon raw material due to temperature fluctuations, which may cause stress and reduce the probability of defects in the silicon crystal; introducing hydrogen gas during the crystal seeding stage can inhibit the adsorption of impurities on the surface of the silicon melt and reduce the risk of impurities entering the growing crystal; introducing hydrogen gas during the shoulder broadening stage can regulate the supercooling degree of the silicon melt, enabling the crystal to grow at a specific angle and rate to obtain a crystal that meets the size requirements, further reducing dislocations and crystal orientation deviations, and ensuring the consistency of crystal growth; introducing hydrogen gas during the equal diameter stage helps to maintain a stable growth environment and ensure that the hydrogen doping concentration in the silicon crystal is uniform in the radial direction. When the time for introducing hydrogen gas into the silicon raw material satisfies the above proportional range, the doping concentration and doping uniformity of hydrogen gas in the single crystal rod can be accurately regulated, thereby reducing dislocations and crystal orientation offsets in the single crystal rod, and also making the ratio of the head and tail of the dislocations and the ratio of the head and tail of the crystal orientation offset more tend to 1, significantly improving the quality and production efficiency of the single crystal silicon.

[0120] In some embodiments, the method for preparing a single crystal rod further includes: after the recharging step, introducing a protective gas into the silicon raw material; wherein, hydrogen gas and the protective gas form a mixed gas, and the volume percentage of hydrogen gas in the mixed gas is 1~90%.

[0121] It can be understood that the volume percentage of hydrogen in the mixed gas can take any value among 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or a range between any two values. The protective gas can be argon. While introducing hydrogen, introducing the protective gas can, on the one hand, form a certain gas flow environment in the single crystal furnace 100, diffuse around the silicon crystal growth region, promote the formation of stable convection of the gas, ensure the consistency of the crystal growth environment, and avoid crystal defects caused by local environmental differences; on the other hand, it can transfer heat to other regions outside the silicon crystal growth region through gas flow, thereby playing a cooling role, helping to adjust the temperature gradient, and at the same time being able to carry away the impurities volatilized from the surface of the silicon melt, which is beneficial to the growth of the crystal along a specific direction, reduce the crystal orientation deviation, and improve the overall quality of the single crystal rod. When the volume percentage of hydrogen in the mixed gas satisfies the above-mentioned value range, it can ensure the growth quality of the single crystal rod while doping the single crystal with hydrogen, and avoid the explosion risk caused by too high hydrogen content.

[0122] In some embodiments, the volume percentage of hydrogen in the mixed gas is preferably 5 - 90%.

[0123] It can be understood that the volume percentage of hydrogen in the mixed gas can take any value among 5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, 90% or a range between any two values.

[0124] In some embodiments, the volume percentage of hydrogen in the mixed gas is preferably 5 - 35%.

[0125] It can be understood that the volume percentage of hydrogen in the mixed gas can take any value among 5%, 10%, 15%, 20%, 25%, 30%, 35% or a range between any two values. When the volume percentage of hydrogen in the mixed gas satisfies the above-mentioned value range, it can further ensure that sufficient hydrogen is used to dope the single crystal.

[0126] In some embodiments, the flow rate of hydrogen is 0.0001 - 180 slpm.

[0127] It can be understood that the value of the flow rate of hydrogen (unit: slpm) can take any value among 0.0001, 1, 30, 60, 90, 120, 150, 180 or a range between any two values.

[0128] In some embodiments, the flow rate of hydrogen is preferably 5 - 50 slpm.

[0129] It is understandable that the value of the flow rate of hydrogen (unit: slpm) can be any value among 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or the range between any two values. When the flow rate of hydrogen satisfies the above value range, hydrogen has an ideal doping concentration in the single crystal silicon rod, and at the same time, uneven distribution caused by excessive real-time flow rate is avoided, so that the hydrogen concentration in the axial and radial directions of the single crystal silicon rod has good uniformity.

[0130] In some embodiments, the flow rate of the protective gas is 40 - 200 slpm.

[0131] It is understandable that the value of the flow rate of the protective gas (unit: slpm) can be any value among 40, 60, 80, 100, 120, 140, 160, 180, 200 or the range between any two values.

[0132] In some embodiments, before the start of the isodiameter step after the end of the re - charge step, the volatilization rate η of the group III - V elements is controlled to satisfy: η=(H 1 / 100mm)×100% - 15%; wherein, H 1 is the liquid level distance in the single crystal furnace 100, unit: mm; the volatilization rate η satisfies: 5% ≤ η ≤ 25%; the liquid level distance H 1 satisfies: 20mm ≤ H 1 ≤ 40mm.

[0133] As Figure 1 and Figure 2 shown, it is understandable that a guiding cylinder 10 and a crucible 30 are provided in the single crystal furnace 100. The crucible 30 contains silicon raw materials, and the silicon raw materials are melted into liquid silicon materials after the material melting step. The guiding cylinder 10 is arranged directly above the crucible 30 and is used to guide the protective gas flow, form a stable gas flow field, regulate the temperature field, and assist in forming a temperature gradient during the preparation of the single crystal silicon rod. Among them, the liquid level distance H 1 is the distance formed between the lower edge of the guiding cylinder 10 and the liquid surface of the silicon liquid 40. The silicon liquid 40 is the liquid formed after the silicon raw materials are melted. On the one hand, the value of the liquid level distance affects the volatilization of the doping element and the antimony element. The larger the liquid level distance, the smaller the volatilization rate of the antimony element, and the smaller the liquid level distance, the larger the volatilization rate of the antimony element. The volatilization rate of the antimony element affects the doping concentration during the growth of the single crystal silicon rod, and further affects the resistivity in the single crystal silicon rod and the axial uniformity of the resistivity. Therefore, by controlling the volatilization rate and the liquid level distance H 1 to satisfy the above relationship, it can be ensured that during the growth of the single crystal silicon rod, the volatilization rate of the antimony element is always in a relatively stable state, so that the resistivity in the single crystal silicon rod is in a stable state, and at the same time, the cost of additional addition of antimony raw materials due to excessive volatilization of the antimony element is avoided.

[0134] It is understandable that the evaporation rate of group III-V elements also affects the doping of hydrogen in the crystal. When the evaporation rate of group III-V elements is relatively high, it will reduce the surface tension of the silicon melt, making it easier for hydrogen to form bubbles on the surface of the silicon melt and escape. The solubility of hydrogen in the silicon melt decreases, resulting in a decrease in the doping amount of hydrogen in the crystal. Therefore, by controlling the distance H from the liquid outlet 1 and controlling the evaporation rate η of group III-V elements within an ideal range, the doping concentration of hydrogen in the single crystal silicon rod can be further controlled to be ideal.

[0135] It is understandable that the height of the crucible 30 in the single crystal furnace 100 can be adjusted in real time. During the growth of the single crystal silicon rod, the liquid level of the silicon liquid 40 in the crucible 30 will decrease as the length of the single crystal silicon rod increases. By detecting the distance H from the liquid outlet in the single crystal furnace 100 in real time 1 and adjusting the height of the crucible 30, it is ensured that the distance H from the liquid outlet 1 remains basically constant after the silicon raw material melts to form the silicon liquid 40. Among them, keeping the distance H from the liquid outlet 1 basically constant means that during the process of maintaining the distance H from the liquid outlet by adjusting the height of the crucible 30 1 , the error between the actual distance from the liquid outlet and the preset distance from the liquid outlet does not exceed ±5% (about ±1 - 2 mm). The height of the crucible 30 can be adjusted by a screw jack or a hydraulic lifting device, or can be assisted by an automated control system, or can be adjusted by other height adjustment devices, which will not be elaborated here.

[0136] The distance H from the liquid outlet 1 is detected by a CCD (Charge-Coupled Device) infrared measurement device, and can be specifically realized in the following ways: 1) Install the CCD infrared measurement device at a position where the liquid level of the silicon liquid 40 in the single crystal furnace 100 can be clearly observed. For example, it can be near the observation window on the side or top of the furnace body. Ensure that the device is firmly installed and can withstand the high temperature and possible vibration of the working environment of the single crystal furnace 100, and at the same time ensure that the optical path is not blocked by other structures or components in the furnace; 2) Use optical elements such as infrared lenses and mirrors (such as infrared lenses and mirrors) to construct an optical path so that the infrared radiation emitted by the liquid level of the silicon liquid 40 can be focused on the CCD detector; 3) After the charge melting is completed, perform temperature calibration and spatial calibration on the CCD detector, and record the signal intensity curve corresponding to the temperature and position of the silicon liquid 40; 4) In the steps of recharging, crystal seeding, shoulder release, shoulder turning, and equal diameter, process the collected infrared images, calculate the height of the liquid level through the temperature characteristics of the silicon liquid 40, and then calculate the distance H from the liquid outlet 1。

[0137] By maintaining a relatively constant liquid orifice distance H 1 , a stable temperature field and gas flow field can be formed within the single crystal furnace 100. On the one hand, it maintains an appropriate temperature gradient at the solid-liquid interface, ensures a uniform temperature distribution of the silicon liquid 40, avoids abnormal growth and defect generation of the silicon crystal, and on the other hand, controls the convection of the silicon liquid 40, ensures a uniform distribution of doping elements, further improves the uniformity of doping concentration, and at the same time enables the single crystal silicon rod to grow uniformly, reduces crystal defects, and improves the overall quality of the single crystal silicon rod.

[0138] In some embodiments, the evaporation rate η satisfies: 5% ≤ η ≤ 25%.

[0139] It can be understood that the value of the evaporation rate η can be any value among 5%, 10%, 15%, 20%, 25% or the range between any two values. When the value of the evaporation rate η satisfies the above value range, it can effectively regulate the doping concentration of group III-V elements and hydrogen elements during the growth of the crystal rod, thereby ensuring that the single crystal silicon rod has a uniform resistivity in the axial direction and a uniform hydrogen element concentration in the radial direction.

[0140] In some embodiments, the liquid orifice distance H 1 satisfies: 20 mm ≤ H 1 ≤ 40 mm.

[0141] It can be understood that the value of the liquid orifice distance H 1 (unit: mm) can be any value among 20, 25, 30, 35, 40 or the range between any two values. An overly small liquid orifice distance will lead to an increase in the wire breakage rate of the single crystal silicon rod, affect the crystal formation quality, and abnormal situations such as silicon spraying and silicon sticking will occur, while an overly large liquid orifice distance will make the crystal formation too difficult.

[0142] As Figure 1 shown, in some embodiments, a flow guide cylinder 10 is provided inside the single crystal furnace 100. The flow guide cylinder 10 includes a first section 11 and a second section 12 connected to each other, and satisfies: tanα = H 2 / W 1 , and 0 ≤ tanα ≤ 0.58.

[0143] Wherein, the included angle α is the included angle formed by the second section 12 and the first direction X, in units of °; H 2 is the height of the projection of the second section 12 in the second direction Y, in units of mm; W 1 is the length of the projection of the second section 12 in the first direction X, in units of mm; As Figure 1 shown, the first direction X is the horizontal direction, the second direction Y is the vertical direction, and the first direction X intersects with the second direction Y. In some embodiments, the first direction X and the second direction Y are perpendicular to each other.

[0144] In some embodiments, the included angle α may be the included angle formed by the line connecting the starting end and the ending end of the second section 12 and the first direction X.

[0145] It can be understood that the first section 11 of the flow guide tube 10 encloses a closed side wall, which is usually a cylindrical structure, in the shape of an upright cylinder, surrounding the crucible 30 above, providing a vertical flow guide channel for hydrogen, protective gas, etc., enabling the gas to flow along a specific direction, thereby ensuring the formation of a stable convection near the single crystal rod and the crucible 30, and ensuring the consistency of the crystal growth environment; the second section 12 of the flow guide tube 10 is connected to the first section 11 and forms the bottom. The second section 12 extends from the connection with the first section 11 towards the inside of the flow guide tube 10, and at the same time inclines towards the side close to the silicon liquid 40, so that the extending direction of the second section 12 forms an included angle α with the first direction X. When tanα = 0, the second section 12 is parallel to the first direction X.

[0146] In some embodiments, the value of tanα is preferably 0.0001 ≤ tanα ≤ 0.58, that is, the second section 12 forms an acute angle α with the first direction X.

[0147] It can be understood that the value of tanα can be any value among 0.0001, 0.1, 0.2, 0.3, 0.4, 0.5, 0.58 or the range between any two values. During the process of guiding the gas in the single crystal furnace 100, the included angle α will also affect the volatilization of doping elements. The larger the included angle α, the smaller the real-time volatilization rate of group III-V elements, and at the same time, more oxygen will enter the single crystal rod. The smaller the included angle α, the larger the real-time volatilization rate of group III-V elements. Therefore, controlling the value of tanα to satisfy the above value range can ensure that both group III-V elements and hydrogen in the single crystal rod have reasonable contents.

[0148] In some embodiments, the flow guide tube 10 has a maximum diameter D max , satisfying: D max ≥2W 1 +W 2 ; It can be understood that when the first section 11 of the flow guide tube 10 encloses a cylindrical structure, the diameter of the flow guide tube 10 can gradually decrease along the vertical direction towards the crucible 30, or remain unchanged. Controlling the maximum diameter D max to satisfy the above relationship can further adjust the flow direction and speed of the protective gas in the single crystal furnace 100, and improve the stability of the crystal structure of the single crystal rod during the crystal pulling process.

[0149] In some embodiments, one end of the accommodation cavity 13 close to the silicon liquid 40 has a through hole 14, W 2is the maximum size of the through hole 14, in mm. It can be understood that W 2 is greater than or equal to the target diameter of the single crystal silicon rod.

[0150] In some embodiments, the maximum diameter D max satisfies: 700mm ≤ D max ≤ 1200mm.

[0151] In some embodiments, the length W 1 satisfies: 155mm ≤ W 1 ≤ 455mm.

[0152] In some embodiments, the maximum size W 2 satisfies: 290mm ≤ W 2 ≤ 390mm.

[0153] In some embodiments, the height H 2 satisfies: 0 ≤ H 2 ≤ 300mm.

[0154] It can be understood that the value of the maximum diameter D max (unit: mm) can be any value among 700, 800, 900, 1000, 1100, 1200 or the range between any two values; the value of the length W 1 (unit: mm) can be any value among 155, 200, 250, 300, 350, 400, 455 or the range between any two values; the value of the maximum size W 2 (unit: mm) can be any value among 290, 310, 330, 350, 370, 390 or the range between any two values; the value of the height H 2 (unit: mm) can be any value among 0, 50, 100, 150, 200, 250, 300 or the range between any two values. When W 1 、W 2 、H 2 and D max satisfy the above value ranges, the volume Vs of the gas flow region can be in an ideal range, thereby further optimizing the guiding effect of the guiding cylinder 10 during the growth of the single crystal silicon rod, so that the resistivity, oxygen content and hydrogen content of the prepared single crystal silicon rod all have ideal uniformity.

[0155] In some embodiments, such as Figure 1 and Figure 3As shown, the single crystal furnace 100 includes a top cover 20. The top cover 20 is provided with a first ventilation hole 21 and a second ventilation hole 22. The first ventilation hole 21 is arranged around the second ventilation hole 22. The first ventilation hole 21 is used to introduce hydrogen into the single crystal furnace 100, and the second ventilation hole 22 is used to introduce a protective gas into the single crystal furnace 100. Among them, the first ventilation hole 21 has a first distance D from the center of the top cover 20 1 , and the second ventilation hole 22 has a diameter D 2 , satisfying: 2D 1 > D 2 .

[0156] As Figures 1 to 3 shown, the second ventilation hole 22 is a through hole in the top cover 20. There are several first ventilation holes 21, which are arranged around the outer periphery of the second ventilation hole 22. The number of the first ventilation holes 21 is preferably 8 - 10. During the crystal pulling process, hydrogen enters the guide cylinder 10 through the first ventilation hole 21 and contacts the silicon liquid 40 in the crucible 30 to achieve doping. The protective gas enters the guide cylinder 10 through the second ventilation hole 22 and flows in the areas inside and outside the guide cylinder 10 to protect the single crystal rod. It can be understood that the protective gas can directly enter the guide cylinder 10 through the second ventilation hole 22, or can enter through devices such as the furnace cylinder and then flow through the second ventilation hole 22 into the guide cylinder 10. When the first distance D 1 and the diameter D of the second ventilation hole 2 satisfy 2D 1 > D 2 , hydrogen can have a large flow space in the guide cylinder 10 and be fully mixed and homogenized with the protective gas, thereby improving the uniformity during the doping process.

[0157] In some embodiments, the first distance D 1 satisfies: 350mm ≤ D 1 ≤ 500mm.

[0158] In some embodiments, the diameter D of the second ventilation hole 22 2 satisfies: 500mm ≤ D 2 ≤ 800mm.

[0159] It can be understood that the value of the first distance D 1 (unit: mm) can be any value among 350, 380, 410, 440, 470, 500 or the range between any two values. The value of the diameter D of the second ventilation hole 22 2 (unit: mm) can be any value among 500, 550, 600, 650, 700, 750, 800 or the range between any two values.

[0160] In some embodiments, a flow guide cylinder 10 is provided inside the single crystal furnace 100, and the flow guide cylinder 10 has a maximum diameter D max , satisfying: D max ≥2D 1 ; The bottom of the flow guide cylinder 10 and the top cover 20 have a third spacing H 3 , satisfying: 0.5m ≤ H 3 ≤ 1.5m.

[0161] It can be understood that the value of the third spacing H 3 (unit: m) can be any value among 0.5, 0.7, 0.9, 1.1, 1.3, 1.5 or the range between any two values. When the third spacing H 3 satisfies the above value range, the hydrogen and protective gas introduced into the single crystal furnace 100 have sufficient flow space to form convection, ensuring a stable gas field and temperature field inside the flow guide cylinder 10, thereby guaranteeing the growth quality of the single crystal rod.

[0162] Based on the above embodiments, as shown by the shaded part in Figure 4 , the first section 11 and the second section 12 enclose a receiving cavity 13, and a first gas flow region 50 is provided inside the receiving cavity 13; between the outer wall of the flow guide cylinder 10 and the inner wall of the single crystal furnace 100 and between the growing single crystal rod and the inner wall of the single crystal furnace 100, there is a second gas flow region 60. It can be understood that the second gas flow region 60 is located inside the single crystal furnace 100, and the gas flow region is above the liquid level of the silicon liquid 40. Further, the second gas flow region 60 surrounds the flow guide cylinder 10 (and of course also surrounds the growing single crystal rod). It can be understood that the second gas flow region 60 includes a first region 61 and a second region 62, where the first region 61 is the region for gas flow between the flow guide cylinder 10 and the inner wall of the single crystal furnace 100, and the second region 62 is the region for gas flow above the liquid level of the silicon liquid 40 and excluding the volume of the single crystal itself.

[0163] In some embodiments, the volume Vs of the second gas flow region 60 satisfies: Vs = V 1 +V 2 . Among them, V 1 is the first volume of the first region 61, and V 2 is the second volume of the second region 62.

[0164] It can be understood that the value of the first volume V 1 of the first region 61 is affected by the included angle maximum diameter D max and the third spacing H 3 , and the value of the second volume V 2 of the second region 62 is affected by the liquid outlet distance H1 and the maximum diameter D max The influence. By regulating the first volume V 1 and the second volume V 2 , the flow direction and speed of the protective gas in the single crystal furnace 100 can be changed, so that the gas is shunted after reaching the crystal growth interface. Therefore, controlling the volume Vs of the second gas flow region 60 to have a reasonable size can adjust the blowing force of the protective gas on the growth interface of the single crystal silicon rod and improve the stability of the crystal structure of the single crystal silicon rod during the crystal pulling process.

[0165] The third embodiment of the present application provides a silicon wafer, which is prepared from the single crystal silicon rod in the above embodiment.

[0166] In some embodiments, the silicon wafer contains hydrogen elements; the dislocation density of the silicon wafer is 4 - 500 atom / cm 2 ; the resistivity of the silicon wafer is 0.4 - 2.1 Ω·cm; the offset of the silicon wafer in the <100> crystal orientation direction is 0 - ±5°.

[0167] The fourth embodiment of the present application provides a solar cell, including a silicon substrate, and the silicon substrate is prepared from the silicon wafer in the above embodiment; wherein, the resistivity of the silicon substrate is 0.5 - 3 Ω•cm, and the thickness is 120 - 160 μm.

[0168] In some embodiments, the silicon substrate includes a doping region, and the doping region is doped with hydrogen elements and group III-V elements; The concentration of hydrogen elements in the doping region is 0.0001 cm -3 ~1E+17 cm -3 ; The concentration of group III-V elements in the doping region is 1E+14 cm -3 ~8E+15 cm -3 .

[0169] The following is an illustration of the single crystal silicon rod and the preparation method provided by the present application in combination with specific embodiments: Example 1 Load polycrystalline silicon ingots or recycled materials into the quartz crucible 30. For example, first stack the solid silicon raw materials into the quartz crucible 30, and then place the quartz crucible 30 filled with silicon materials into the single crystal furnace 100.

[0170] Vacuum the inside of the single crystal furnace 100, and use the bottom heater and the main heater with 90KW to melt the solid silicon in the quartz crucible 30 into a molten state.

[0171] Since the solid silicon materials in the quartz crucible 30 are stacked and placed, after being heated and melted, the actual volume occupied in the quartz crucible 30 decreases, and the melted silicon materials do not reach the maximum loading capacity of the quartz crucible 30. Therefore, it is necessary to refill the quartz crucible 30 with silicon materials through a re-feeder. During the filling process, the heater simultaneously melts the silicon materials in the quartz crucible 30.

[0172] After the re-feeding is completed, an antimony (Sb) dopant is loaded into the doping spoon pre-installed in the single crystal furnace 100. After all the silicon materials in the quartz crucible 30 are melted, it turns to the temperature adjustment stage. Before the seed crystal is lowered for melting and welding, the Sb dopant in the doping spoon is poured into the silicon melt 40, the seed crystal is inserted into the liquid surface, and the critical crystallization temperature of the liquid surface temperature is achieved by controlling power parameters, etc. The doping amount is calculated by segregation according to the target resistivity. Taking 1000 kg of full crucible material as an example, for single-feed virgin polycrystal, the total amount of antimony (Sb) dopant is 20 g.

[0173] After the seed crystal and the liquid surface reach the crystallization temperature point, the seed crystal is lifted upward. By adjusting parameters such as power and pulling speed, the actual single crystal diameter is adjusted to the range of 275 - 285 mm round bar diameter; after the shoulder is formed, it enters the equal-diameter process of the silicon rod through the shoulder transition process.

[0174] During the equal-diameter process, the furnace pressure is adjusted to 8 - 15 torr, the gas flow rate is 100 slpm, the crystal rotation speed is 9 - 6 rpm, the crucible rotation speed is 6 - 9 rpm, and the power (50 KW) is adjusted to volatilize antimony. When the equal-diameter length reaches 4800 mm, the silicon rod drawing is completed through the finishing process.

[0175] In other processes except the equal-diameter process, to reduce the volatilization of antimony, a large furnace pressure is mainly used to suppress the volatilization of antimony, and the furnace pressure is between 15 - 30 torr.

[0176] In each of the above stages, hydrogen and the protective gas argon need to be introduced, and the volume ratio of hydrogen / argon is 50%; the flow rate of hydrogen is 100 slpm, and the flow rate of argon is 120 slpm.

[0177] The prepared single crystal silicon rod is subjected to steps such as cutting, chamfering, grinding, polishing, cleaning, and detection to obtain single crystal silicon wafers.

[0178] The prepared silicon wafers are detected for doping concentration, dislocations, and crystal orientation offset. The detection method is the same as that for the single crystal silicon rod. The dislocation density of the silicon wafers is obtained as 480 atom / cm 2 , the resistivity is 0.4 - 2.1 Ω·cm, and the offset in the <100> crystal orientation direction is 5°.

[0179] Example 2 - 25 The specific preparation process is the same as that of Example 1, except that the size of the single crystal furnace 100, the flow rate of hydrogen, and the introduction time are adjusted.

[0180] Comparative Examples 1-3 The specific preparation process is the same as that of Example 1, except that the size of the single crystal furnace 100 is adjusted.

[0181] The specific hydrogen introduction parameters of Examples 1-25 are shown in Tables 1 and 2.

[0182] Table 1

[0183]

[0184]

[0185] The single crystal furnace parameters in Examples 1-7 and Comparative Examples 1-3 are shown in Table 2.

[0186] Table 2

[0187] The doping element content, oxygen content, and resistivity in Examples 1-7 and Comparative Examples 1-3 are detected, and the detection methods are as follows: Measurement of resistivity: The resistivity of the ingot is measured using a KDY-1A resistivity tester.

[0188] The test method for oxygen content is: Measure the oxygen content at the head of the ingot. The test method refers to GB / T 1557-2018, and a Nicolet 6700 Fourier transform infrared spectrometer is used to measure the oxygen content in the ingot; By cutting test samples with a thickness ≥2 mm at the head and tail of the single crystal, the interstitial oxygen content at the set position in the silicon single crystal sample is measured by infrared spectroscopy, and it is carried out in accordance with the national standard GB / T 1557; According to the thermal cycle process of manufacturing integrated circuits, the silicon wafer is subjected to simulated heat treatment, and the interstitial oxygen content before and after heat treatment of the silicon wafer is measured by infrared absorption method, and the difference is regarded as the amount of interstitial oxygen precipitation.

[0189] Measurement of antimony content and phosphorus content: The content of trace elements in silicon is measured by GDMS (glow discharge mass spectrometry), and it is carried out in accordance with the national standard GB / T 32651.

[0190] Measurement of hydrogen element content: Using the inert gas fusion technique, the sample is heated in a pulse furnace to over 3000 °C, and the hydrogen content is determined by thermal conductivity method. The detection results are shown in Table 3.

[0191] Table 3

[0192] As can be seen from the above examples and comparative examples, the single-crystalline silicon rods and wafers provided by the present application, as well as the single-crystalline silicon rods and wafers prepared by the preparation method provided by the present application, have relatively ideal performances in terms of resistivity uniformity, dislocation density, crystal growth direction, etc.

[0193] The above has introduced in detail the single-crystalline silicon rod and its preparation method, wafer, and solar cell provided by the embodiments of the present application. Specific examples are used in the present application to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A single crystal silicon rod, characterized in that: The single crystal silicon rod contains hydrogen element; the resistivity ratio of the head of the single crystal silicon rod to the resistivity ratio of the tail of the single crystal silicon rod is 0.8-2.0; The dislocation density of the single crystal silicon rod satisfies: -80%≤(ρ1-ρ2) / ρ1≤80%; Wherein, ρ1 is the dislocation density at the tail of the single crystal silicon rod, and ρ2 is the dislocation density at the head of the single crystal silicon rod.

2. A single crystal silicon rod according to claim 1, characterized in that: The dislocation density ρ1 of the tail of the single crystal silicon rod is 4-3000atom / cm 2 The dislocation density ρ2 of the single crystal silicon rod head is 4~3000atom / cm 2 and / or, The dislocation density in the middle of the single crystal silicon rod is 4-500atom / cm 2 .

3. The single crystal silicon rod according to claim 1, characterized in that: The resistivity of the single crystal silicon rod head is 0.6-2.1Ω·cm; and / or, The resistivity of the tail of the single crystal silicon rod is 0.4-2.1Ω·cm.

4. The single crystal silicon rod according to claim 1, characterized in that: The single crystal silicon rod meets the following requirements: 0.8≤s1 / s2≤2; Wherein, s1 is the tail crystal of the single crystal silicon rod in the crystal direction <100> The offset in the direction, s2 is the offset of the head crystal of the single crystal silicon rod in the crystal direction <100> The offset in direction.

5. A single crystal silicon rod according to claim 4, characterized in that: The tail crystal of the single crystal silicon rod is <100> The offset s1 in the direction is 0~±5°; the head crystal of the single crystal silicon rod is <100> The directional offset s2 is 0~±5°.

6. The single crystal silicon rod according to claim 1, characterized in that: Along the radial direction of the single crystal silicon rod, the single crystal silicon rod has a center and an edge, satisfying: 0≤(C H1 -C H2 ) / C H2 ≤35%; Among them, C H1 is the hydrogen concentration at the edge, C H2 is the hydrogen concentration at the center.

7. The single crystal silicon rod according to claim 6, characterized in that: The hydrogen concentration C at the edge H1 Meet: 0.0001cm -3 ≤C H1 ≤1E+17cm -3 and / or, The central hydrogen element C H2 Meet: 0.0001cm -3 ≤C H2 ≤1E+17cm -3 and / or, Along the radial direction of the single crystal silicon rod, the distance between the center and the edge is R, and the hydrogen content at 0.65R~0.78R from the center is 0.0001~1E+17cm -3 .

8. The single crystal silicon rod according to claim 1, characterized in that: The single crystal silicon rod comprises a head and a tail opposite to each other along the length direction, and the single crystal silicon rod is divided into N segments of silicon rod units from the head to the tail, and the silicon rod units have a first end and a second end opposite to each other along the length direction; the single crystal silicon rod contains III-V group elements and hydrogen element; the single crystal silicon rod satisfies: K1=1-((C n-1 -C H ) / (C n -C H )), and 1E-3≤|K1|≤1E-2; Among them, C H represents the hydrogen concentration per unit volume of the single crystal silicon rod; C n represents the concentration of Group III and V elements per unit volume of the silicon rod unit of the nth segment at the second end; C n-1 represents the concentration of Group III-V elements per unit volume of the nth silicon rod unit at the first end; n is an integer greater than or equal to 1, and N is an integer greater than or equal to 1.

9. The single crystal silicon rod according to claim 8, characterized in that: The concentration C of the III-V group elements per unit volume of the silicon rod unit of the nth section at the second end n Satisfy: 1E+14cm -3 ≤C n ≤8E+15cm -3 and / or, The concentration C of Group III and V elements per unit volume of the nth segment silicon rod unit at the first end n-1 Satisfy: 1E+14cm -3 ≤C n ≤8E+15cm -3 .

10. The single crystal silicon rod according to claim 8, characterized in that: The group III-V elements include antimony and phosphorus, and the concentration ratio of the antimony to the phosphorus in the single crystal silicon rod is 0.2-10.

11. A method for preparing a single crystal silicon rod, characterized in that: include: Providing silicon raw materials, and obtaining single crystal silicon rods through the steps of material chemistry, re-dosing, temperature stabilization, seeding, shouldering, equalizing diameters and finishing; in at least one of the steps of material chemistry, re-dosing, temperature stabilization, seeding, shouldering, equalizing diameters and finishing, introducing hydrogen into the silicon raw materials; Before the growth of the single crystal silicon rod is completed, the concentration of doping elements in the solidification process of the single crystal silicon rod is adjusted to control the resistivity ratio of the head of the single crystal silicon rod to the resistivity ratio of the tail of the single crystal silicon rod to meet 0.8-1.2, and the dislocation density of the single crystal silicon rod to meet 4-3000atom / cm 2 .

12. The method for preparing a single crystal silicon rod according to claim 11, characterized in that: Also includes: Before the equalizing step, adding a metal single substance or alloy containing Group III and V elements to the silicon raw material; Before the growth of the single crystal silicon rod is completed, the doping concentrations of hydrogen and group III-V elements are adjusted during the solidification process of the single crystal silicon rod to control the doping amount ratio of the hydrogen and group III-V elements to meet the following conditions: K1=1-((C n-1 -C H ) / (C n -C H )), and 1E-3≤|K1|≤1E-2; In the formula, C H represents the hydrogen concentration per unit volume of the single crystal silicon rod; C n represents the concentration of Group III and V elements per unit volume of the silicon rod unit of the nth segment at the second end; C n-1 It represents the concentration of Group III-V elements per unit volume of the n-th silicon rod unit at the first end; n is an integer greater than or equal to 1.

13. The method for preparing a single crystal silicon rod according to claim 11, characterized in that: The time for introducing hydrogen into the silicon raw material is 0.5 to 82 hours.

14. The method for preparing a single crystal silicon rod according to claim 12, characterized in that: Also includes: After the re-injection step, a protective gas is introduced into the silicon raw material; Wherein, the hydrogen and the protective gas form a mixed gas, and the volume percentage of the hydrogen in the mixed gas is 1-90%; and / or, The flow rate of the hydrogen is 0.0001-180 slpm; and / or, The flow rate of the protective gas is 40-200 slpm.

15. The method for preparing a single crystal silicon rod according to claim 14, characterized in that: Between the end of the re-investment step and the start of the equal diameter step, the volatilization rate η of the III-V group element is controlled to satisfy: η=(H1 / 100mm)×100%-15%; Wherein, H1 is the liquid inlet distance in the single crystal furnace (100), unit: mm; the volatility η satisfies: 5%≤η≤25%; the liquid inlet distance H1 satisfies: 20mm≤H1≤40mm.

16. The method for preparing a single crystal silicon rod according to claim 15, characterized in that: The single crystal furnace (100) comprises a top cover (20), the top cover (20) being provided with a first vent hole (21) and a second vent hole (22), the first vent hole (21) being arranged around the second vent hole (22), the first vent hole (21) being used to introduce the hydrogen into the single crystal furnace (100), and the second vent hole (22) being used to introduce the protective gas into the single crystal furnace (100); There is a first distance D1 between the first vent hole (21) and the center of the top cover (20), and the second vent hole (22) has a diameter D2, satisfying: 2D1>D2.

17. The method for preparing a single crystal silicon rod according to claim 16, characterized in that: A guide tube (10) is arranged in the single crystal furnace (100), and the guide tube (10) has a maximum diameter D max , satisfied: D max ≥2D1; There is a third distance H3 between the bottom of the guide tube (10) and the top cover, satisfying: 0.5m≤H3≤1.5m.

18. A silicon wafer, characterized in that: The method is prepared by using the single crystal silicon rod described in any one of claims 1 to 10 or the single crystal silicon rod prepared by the preparation method described in any one of claims 11 to 17.

19. The silicon wafer according to claim 18, characterized in that: The silicon wafer contains hydrogen; the dislocation density of the silicon wafer is 4-500atom / cm 2 ; The resistivity of the silicon wafer is 0.4~2.1Ω·cm; The silicon wafer has a crystal orientation <100> The directional offset is 0~±5°.

20. A solar cell, characterized in that: Comprising a silicon substrate, wherein the silicon substrate is prepared from the silicon wafer according to claim 18 or 19; The resistivity of the silicon substrate is 0.5-3Ω•cm, and the thickness is 120-160μm.

21. A solar cell according to claim 20, characterized in that: The silicon substrate comprises a doped region, wherein the doped region is doped with hydrogen and group III-V elements; The concentration of hydrogen in the doped region is 0.0001 cm -3 ~1E+17cm -3 ; The concentration of Group III and V elements in the doping region is 1E+14cm -3 ~8E+15cm -3 .

Images