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 silicon single crystal rod contains hydrogen element, the silicon single crystal rod has a center and an edge along the radial direction of the silicon single crystal rod, and (CH1-CH2) / CH2 is more than or equal to 0 and less than or equal to 35%; 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%. According to the silicon single crystal rod provided by the invention, the hydrogen element is doped, and the distribution uniformity of the hydrogen element in the radial direction of the silicon single crystal rod is controlled, so that the recombination effect of defects such as dislocation and vacancy on carriers is effectively reduced in the radial range of the whole silicon single crystal rod, the minority carrier lifetime is prolonged, meanwhile, the stress distribution in the silicon single crystal rod is improved, and the service life of the silicon single crystal rod is prolonged. And the stress is more uniformly released on the cross section of the whole silicon single crystal rod, so that the mechanical property of the silicon rod is enhanced.

Description

Technical Field

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

[0002] In photovoltaic cells, monocrystalline silicon rods are the core material, and their performance directly affects the efficiency and stability of photovoltaic modules. However, in the current production process of monocrystalline silicon rods, due to the influence of crystal pulling and doping processes, growth defects will occur in the monocrystalline silicon rods during the growth process, which will seriously affect the performance of photovoltaic cells. Summary of the invention

[0003] One of the purposes of the present 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 the present application is to provide a method for preparing a single crystal silicon rod. Another object of the present application is to provide a silicon wafer and a solar cell.

[0005] A first embodiment of the present application provides a single crystal silicon rod, wherein the single crystal silicon rod contains hydrogen elements, and 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 ≤20%, more preferably 0≤(C H1 -C H2 ) / C H2 ≤15%; Among them, C H1 is the hydrogen concentration at the edge, C H2 is the hydrogen concentration at the center; 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.

[0006] In some embodiments, the dislocation density of the tail of the single crystal silicon rod is 1 4~3000atom / cm 2 ; The dislocation density ρ of the head of the single crystal silicon rod 2 4~3000atom / cm 2 .

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

[0008] In some embodiments, the single crystal silicon rod satisfies: 0.8≤s 1 / s 2 ≤2; Among them, s 1 The tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction, s 2 The head crystal of the single crystal silicon rod is in the crystal direction <100> The offset in direction.

[0009] In some embodiments, the tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 1 The head crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 2 0~±5°.

[0010] In some embodiments, the resistivity of the single crystal silicon rod is 6-32Ω·cm.

[0011] In some embodiments, the hydrogen concentration C of the edge H1 Meet: 0.0001cm -3 ≤C H1 ≤1E+17cm -3 , preferably 2E+13cm -3 ≤C H1 ≤7E+16cm -3 , and more preferably 1E+15cm -3 ≤C H1 ≤6E+16cm -3 .

[0012] In some embodiments, the central hydrogen element C H2Meet: 0.0001cm -3 ≤C H2 ≤1E+17cm -3 , preferably 2E+13cm -3 ≤C H2 ≤7E+16cm -3 , and more preferably 1E+15cm -3 ≤C H2 ≤6E+16cm -3 .

[0013] 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 content at 0.56R~0.78R from the center is 0.0001cm -3 ~1E+17cm -3 , preferably 2E+13cm -3 ~7E+16cm -3 , and more preferably 1E+15cm -3 ~6E+16cm -3 .

[0014] In some embodiments, the oxygen content in the single crystal silicon rod satisfies: (C Omax -C Omin ) / C Omax ≤10%, preferably (C Omax -C Omin ) / C Omax ≤5%, more preferably (C Omax -C Omin ) / C Omax ≤3%, more preferably (C Omax -C Omin ) / C Omax ≤2%; Among them, C Omax is the maximum oxygen content in the single crystal silicon rod, C Omin is the minimum oxygen content in the single crystal silicon rod.

[0015] In some embodiments, the maximum oxygen content C in the single crystal silicon rod is Omax Satisfy: 9ppma≤C Omax ≤11ppma.

[0016] In some embodiments, the minimum oxygen content C in the single crystal silicon rod is Omin Satisfy: 0.5ppma≤C Omin ≤3.1ppma.

[0017] In some embodiments, the oxygen precipitate content in the single crystal silicon rod is 0.5-15.5 ppma, preferably 0.5-10.5 ppma, more preferably 0.5-9.8 ppma, and further preferably 3.5-9.5 ppma.

[0018] In some embodiments, the interstitial oxygen content in the single crystal silicon rod is 0.5-11 ppma, preferably 0.5-9.5 ppma, further preferably 0.5-7 ppma, or preferably 3.1-9 ppma.

[0019] In some embodiments, the single crystal silicon rod further includes Group III-V elements, and the Group III-V elements include antimony and phosphorus.

[0020] In some embodiments, the doping concentration of the antimony element in the single crystal silicon rod is 7.5E+12~6E+14cm -3 .

[0021] In some embodiments, the doping concentration of the phosphorus element in the single crystal silicon rod is 1.25E+12~7E+14cm -3 .

[0022] A second embodiment of the present application provides a method for preparing a single crystal silicon rod, comprising: 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; Wherein, along the radial direction of the single crystal silicon rod, the single crystal silicon rod has a center and an edge, and before the growth of the single crystal silicon rod is completed, the hydrogen element doping concentration during the solidification process of the single crystal silicon rod is adjusted to control the hydrogen element in the single crystal silicon rod to meet a preset concentration relationship, so that the dislocation density of the single crystal silicon rod is 4-3000atom / cm 2 ; wherein the preset concentration relationship is: 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%; In the formula, C H1is the hydrogen concentration at the edge, C H2 is the hydrogen concentration at the center.

[0023] In some embodiments, the method for preparing a single crystal silicon rod further comprises: Before the step of equalizing the diameter, adding a metal single substance or alloy containing antimony and phosphorus to the silicon raw material; Before the growth of the single crystal silicon rod is completed, the doping concentration of antimony and phosphorus during the solidification process of the single crystal silicon rod is adjusted to control the doping concentration of antimony in the single crystal silicon rod to be 7.5E+12~6E+14cm -3 , and the doping concentration of the phosphorus element in the single crystal silicon rod is 1.25E+12~7E+14cm -3 .

[0024] In some embodiments, the time for introducing hydrogen into the silicon raw material satisfies: t 总 =t 1 +t 2 +t 3 +t 4 +t 5 +t 6 +t 7 , and 0.5h≤t 总 ≤82h; Among them, t 总 is the total time of hydrogen introduction, t 1 is the time for introducing hydrogen into the material stage, t 2 is the time of introducing hydrogen in the re-injection stage, t 3 is the time of hydrogen introduction in the temperature stabilization stage, t 4 is the time of hydrogen introduction in the seeding stage, t 5 is the time of introducing hydrogen during the shoulder release phase, t 6 is the time of introducing hydrogen in the isodiameter stage, t 7 It is the time of introducing hydrogen in the final stage.

[0025] In some embodiments, the time for 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).

[0026] In some embodiments, the method for preparing a single crystal silicon rod further comprises: after the re-injection step, introducing a protective gas into the silicon raw material; The hydrogen and the protective gas form a mixed gas, and the volume percentage of the hydrogen in the mixed gas is 1-90%, preferably 5-90%.

[0027] In some embodiments, the flow rate of hydrogen is 0.0001-180 slpm.

[0028] In some embodiments, the flow rate of the shielding gas is 40-200 slpm.

[0029] In some embodiments, between the end of the re-investment step and the start of the equal diameter step, the volatility η of the III-V group element is controlled to satisfy: η=(H 1 / 100mm)×100%-15%; Among them, H 1 is the liquid inlet distance in the single crystal furnace, unit: mm; the volatility η satisfies: 5%≤η≤25%; the liquid inlet distance H 1 Meet: 20mm≤H 1 ≤40mm.

[0030] In some embodiments, a guide tube is provided in the single crystal furnace, and the guide tube includes a first section and a second section connected to each other, and meets the following requirements: tanα=H 2 / W 1 , and 0≤tanα≤0.58; Wherein, α is the angle between the second segment and the first direction, in degrees; H 2 is the height of the projection of the second segment in the second direction, in mm; W 1 is the length of the projection of the second segment in the first direction, in mm; wherein the first direction and the second direction intersect.

[0031] In some embodiments, the single crystal furnace includes a top cover, the top cover is provided with a first vent hole and a second vent hole, the first vent hole is arranged around the second vent hole, the first vent hole is used to introduce the hydrogen into the single crystal furnace, and the second vent hole is used to introduce the protective gas into the single crystal furnace, satisfying: D max ≥2D 1 >D 2 ; Among them, D max is the maximum diameter of the guide tube, D 1 is a first distance between the first vent hole and the center of the top cover, D 2is the diameter of the second vent hole.

[0032] A third embodiment of the present application provides a silicon wafer prepared from the single crystal silicon rod in any of the above embodiments.

[0033] In some embodiments, the silicon wafer contains hydrogen; the dislocation density of the silicon wafer is 4-500atom / cm 2 ; The resistivity of the silicon wafer is 6~32Ω·cm; The silicon wafer has a crystal orientation <100> The deviation in the direction is 0~±5°; the oxygen content in the silicon wafer is 0.5~11ppma.

[0034] A fourth embodiment of the present application provides a solar cell, including a silicon substrate, wherein the silicon substrate is prepared from the silicon wafer in the above embodiment; The resistivity of the silicon substrate is 6-32Ω•cm, and the thickness is 120-160μm.

[0035] In some embodiments, the silicon substrate includes a doped region, wherein the doped region is doped with hydrogen, antimony and phosphorus; The concentration of hydrogen in the doping region is 0.0001~1E+17cm -3 ; The antimony concentration in the doping region is 7.5E+12~6E+14cm -3 ; The phosphorus concentration in the doped region is 1.25E+12~7E+14cm -3 .

[0036] The present application provides a single crystal silicon rod, wherein the single crystal silicon rod contains hydrogen elements, and 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 ≤20%, more preferably 0≤(C H1 -C H2 ) / C H2 ≤15%; among which, C H1 is the hydrogen concentration at the edge, C H2 The hydrogen concentration at the center; the dislocation density of the single crystal silicon rod satisfies: -80%≤(ρ 1 -ρ 2 ) / ρ 1 ≤80%, preferably -70%≤(ρ1 -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%; where ρ 1 is the dislocation density at the tail of the single crystal silicon rod, ρ 2 The single crystal silicon rod provided by the present application is doped with hydrogen and the uniformity of the hydrogen distribution in the radial direction of the single crystal silicon rod is controlled, so that the composite effect of defects such as dislocations and vacancies on carriers is effectively reduced within the radial range of the entire single crystal silicon rod, thereby increasing the minority carrier lifetime, and at the same time helping to improve the stress distribution inside the single crystal silicon rod, so that the stress is released more evenly over the entire cross section of the single crystal silicon rod, thereby enhancing the mechanical properties of the silicon rod.

[0037] It should be noted that the silicon wafer, the method for preparing the single crystal silicon rod and the solar cell of the embodiments of the present application may include all the technical features and beneficial effects of the above-mentioned single crystal silicon rod, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0039] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0040] Figure 1 A schematic diagram of the structure of a single crystal furnace provided in an embodiment of the present application; Figure 2 for Figure 1 A partial enlarged view of part A; Figure 3 A schematic diagram of a top view of a single crystal furnace cover provided in an embodiment of the present application; Figure 4 A schematic diagram of the structure of a gas flow area in a single crystal furnace provided in an embodiment of the present application.

[0041] Description of reference numerals: 10-guide tube, 11-first section, 12-second section, 13-accommodating chamber, 14-through hole, 20-top cover, 21-first air vent, 22-second air vent, 30-crucible, 40-silicon liquid, 50-first gas flow area, 60-second gas flow area, 61-first area, 62-second area, 100-single crystal furnace. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0043] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" 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 can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or indirectly connected through a pipe or pipeline, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more features.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The first embodiment of the present application provides a single crystal silicon rod, wherein the single crystal silicon rod contains hydrogen elements, and 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 ≤20%, more preferably 0≤(C H1 -C H2 ) / C H2 ≤15%; Among them, C H1 is the hydrogen concentration at the edge, C H2 The concentration of hydrogen at the center; 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.

[0048] In the present application, the center of a single crystal silicon rod refers to the center point of any radial section figure of the single crystal silicon rod, and the edge of a single crystal silicon rod refers to the edge point of any radial section figure of the single crystal silicon rod. For example, the radial section of the single crystal silicon rod can be a circle, then the center of the single crystal silicon rod is the center of the radial section, and the edge of the single crystal silicon rod is any point on the circumference of the radial section.

[0049] It is understandable that (C H1 -C H2 ) / C H2 The value of can be any value among 0, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or the range between any two values. H1 -C H2 ) / C H2 When the above-mentioned value range is satisfied, the hydrogen element has an ideal radial concentration distribution in the single crystal silicon rod, which can effectively reduce the recombination effect of defects such as dislocations and vacancies on carriers within the radial range of the entire single crystal silicon rod, thereby increasing 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 over the entire cross section of the single crystal silicon rod, thereby enhancing the mechanical properties of the silicon rod.

[0050] In the present application, the head and tail of a single crystal silicon rod refer to the position of the equal-diameter head (the corresponding position is the head of the single crystal silicon rod) when the diameter of the single crystal silicon rod is led to the target diameter by the direct pulling method, and when the single crystal silicon rod is produced with 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 the present application refers to the radial cross section of the head of the single crystal silicon rod perpendicular to the length direction of the rod, and the tail end face of the single crystal silicon rod refers to the radial cross section of the tail of the single crystal silicon rod perpendicular to the length direction of the rod. In the present application, 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 tested and calculated from the cross section of the silicon rod.

[0051] It is understandable that in the process of doping along with the growth of single crystal silicon rods, 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, and controlling the resistivity ratio of the head and tail of the single crystal silicon rod within a reasonable range, ensuring that the electrical properties of different parts of the single crystal silicon rod are more consistent, thereby improving the electrical properties of the single crystal silicon rod; on the other hand, hydrogen can react with impurities in the silicon melt and discharge them, and regulate the diffusion and distribution of metal elements, reduce the dislocation density, and optimize the crystal growth process, so that the overall dislocation of the single crystal silicon rod is more evenly distributed in the axial direction, thereby avoiding the need to cut part of the single crystal silicon rod due to excessive local dislocations, thereby improving the yield of the single crystal silicon rod.

[0052] In some embodiments, the resistivity of the single crystal silicon rod is 6-32 Ω·cm.

[0053] It is understandable that the resistivity of the single crystal silicon rod (unit: Ω·cm) can be any value among 6, 10, 14, 20, 24, 28, 32 or a range between any two values. For high-voltage and high-power integrated circuit devices, they need to have a relatively high resistivity to withstand high voltage, reduce current leakage, and improve device performance and reliability. By controlling the resistivity of the single crystal silicon rod to meet the above value range, the device prepared from the single crystal silicon rod can have a strong withstand voltage, can withstand higher voltage without breakdown damage, and at the same time reduce the free carrier concentration inside the material, reduce leakage current, and enable the device to work normally under harsh conditions such as high voltage and high frequency.

[0054] In some embodiments, the dislocation density at the tail of the single crystal silicon rod is 1 4~3000atom / cm 2 ; Dislocation density ρ at the head of the single crystal silicon rod 2 4~3000atom / cm 2 .

[0055] It can be understood that the dislocation density ρ at the tail of the single crystal silicon rod 1 The value (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 a range between any two values. Dislocation density ρ at the head of the single crystal silicon rod 2 The value (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 a range between any two values.

[0056] In some embodiments, the dislocation density in the middle of the single crystal silicon rod is 4-500 atom / cm 2 .

[0057] It is understandable that the value of the dislocation density in the middle of the single crystal silicon rod (unit: atom / cm 2 ) can be any value of 4, 10, 20, 50, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500 or a range between any two values.

[0058] Single crystal silicon rods with high resistivity are more sensitive to defects in silicon crystals. For example, dislocations can affect the mobility of carriers, thereby affecting the resistivity and resistivity uniformity. 2 , the dislocation density ρ at the tail 1 When the dislocation density in the middle part meets the above value range, the single crystal silicon rod can further have good mechanical properties and electronic transmission properties.

[0059] In some embodiments, the single crystal silicon rod satisfies: 0.8≤s 1 / s 2 ≤2; Among them, s 1 The tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction, s 2 The head crystal of the single crystal silicon rod is in the crystal direction <100> The offset in direction.

[0060] It is understandable that the tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 1 The head crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction 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 a range between any two values. The crystal direction refers to the axis with a specific atomic arrangement direction in the crystal, representing the direction in which the atoms in the crystal structure are most regularly and symmetrically arranged. <100> In the crystal direction, atoms are arranged in a periodic and orderly manner, the interatomic distance is large, and the bonding method between atoms is relatively simple and highly symmetrical. Along this direction, the physical properties of the crystal, such as electrical properties and optical properties, can show specific regularity and consistency. Therefore, silicon wafers are usually arranged along the crystal direction. <100> Direction cutting makes the atomic arrangement in the silicon wafer conducive to subsequent semiconductor process processing. For example, during oxidation, photolithography, diffusion and other processes, more uniform film growth, more accurate pattern transfer and more stable impurity diffusion characteristics can be obtained, thereby improving the consistency and reliability of device performance. <100> The directional offset refers to the difference between the actual growth direction of the crystal and the target crystal direction. <100> The degree of deviation of the crystal direction. During the process of pulling a single crystal silicon rod, since the head is close to the seed crystal, the seed crystal can better guide the crystal growth, so the head of the single crystal silicon rod is in the target crystal direction. <100> The offset of the crystal direction is relatively small. However, as the single crystal silicon rod grows, the thermal field stability and melt convection of the single crystal silicon rod change. In addition, the concentration of impurities in the remaining melt increases, which interferes with the regular arrangement of atoms and increases the offset of the crystal direction. Therefore, the tail of the single crystal silicon rod is in the target crystal direction. <100> In addition, the inventors of the present application have found in other embodiments that there may be drastic temperature fluctuations in the early stage of the growth of the single crystal silicon rod, which interferes with the early growth of the crystal and causes a large deviation in the crystal direction 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 tail of the single crystal silicon rod is in the target crystal direction. <100> The offset of the crystal direction is relatively small. 1 / s 2 The value of is controlled within a certain range, which can ensure that the crystal direction of the single crystal silicon rod in the axial direction is in a uniform and orderly state as a whole, and ensure that the crystal direction at any position in the single crystal silicon rod is the target crystal direction. <100> The degree of deviation of the crystal orientation is within the ideal range, thus 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 with fewer defects, thereby improving the electrical and mechanical properties of the silicon wafers prepared in subsequent processes.

[0061] In the process of growing single crystal silicon rods, the seed crystal and thermal field optimization can be used to make the single crystal silicon crystal grow along the target crystal direction. <100> Direction growth, and controlled within the ideal offset. By regulating the heating power in the single crystal furnace 100 and the flow rate of the circulating gas (such as hydrogen and protective gas) in the single crystal furnace 100, the temperature gradient of the thermal field in the radial and axial directions is guaranteed to be stable. The stable thermal field keeps the solid-liquid interface of the single crystal silicon flat, inhibits the growth of impurities, ensures that the atoms are arranged in the established direction of the seed crystal, and avoids the deviation of the crystal growth direction caused by thermal stress, thereby achieving 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 silicon melt. Appropriately reducing the crystal pulling speed can make the crystal growth interface flatter, and the atoms have more time to arrange regularly on the interface, which is conducive to growth along the target direction; if the crystal pulling speed is too fast, the interface temperature gradient increases, which is easy to cause the crystal growth direction to deviate. The flow of silicon melt can be optimized by reasonably designing the rotation speed, temperature field and magnetic field strength of the crucible 30, and optimizing the melt convection mode, so as to obtain high-quality single crystal silicon.

[0062] In some embodiments, the tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 1 0~±5°; the head crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 2 0~±5°.

[0063] It is understandable that the tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 1 The value (unit: °) can be any value among -5, -3, -2, -1, 0, 1, 2, 3, 5 or a range between any two values; the head crystal of the single crystal silicon rod is in the crystal direction <100> The offset in the direction s 2 The value (unit: °) can be any value among -5, -3, -2, -1, 0, 1, 2, 3, 5 or a range between any two values. <100> The offset in the direction meets the above range of values, the stress distribution inside the single crystal silicon rod is more uniform, defects are less 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. <100> The deviation in the direction can be detected by X-ray diffraction. By measuring the position and intensity of the diffraction peak, the crystal orientation and interplanar spacing of the crystal can be determined, and then the deviation in the crystal orientation can be calculated. <100> The directional offset can also be detected by other detection methods, which will not be described here.

[0064] In some embodiments, the hydrogen concentration C at the edge H1 Meet: 0.0001cm-3 ≤C H1 ≤1E+17cm -3 , preferably 2E+13cm -3 ≤C H1 ≤7E+16cm -3 , and more preferably 1E+15cm -3 ≤C H1 ≤6E+16cm -3 .

[0065] It can be understood that the hydrogen concentration C at the edge H1 The value (unit: cm -3 ) 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 a range between any two values.

[0066] In some embodiments, the central hydrogen element C H2 Meet: 0.0001cm -3 ≤C H2 ≤1E+17cm -3 , preferably 2E+13cm -3 ≤C H2 ≤7E+16cm -3 , and more preferably 1E+15cm -3 ≤C H2 ≤6E+16cm -3 .

[0067] It is understandable that the central hydrogen element C H2 The value (unit: cm -3 ) 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 a range between any two values.

[0068] 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 content at 0.56R~0.78R from the center is 0.0001cm -3 ~1E+17cm -3 , preferably 2E+13cm -3~7E+16cm -3 , and more preferably 1E+15cm -3 ~6E+16cm -3 .

[0069] It can be understood that the value of the hydrogen content at 0.65R~0.78R from the center (unit: cm -3 ) 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 a range between any two values.

[0070] When the hydrogen concentration C H1 , the central hydrogen element C H2 , when the hydrogen content at 0.65R~0.78R from the center meets the above range, the interaction between hydrogen and other doping elements can be realized, and the effective segregation coefficient of metal elements in crystalline silicon after doping in silicon can be improved, so as to improve the distribution uniformity of single crystal silicon resistivity. Hydrogen can also interact with impurities or defects in silicon materials, reduce the interference of impurities or defects on electron transmission, and further improve the consistency of conductivity and resistivity. In addition, some hydrogen elements can also play a role in passivation and impurity absorption on impurities and defects in silicon crystals, which can increase the minority carrier lifetime of single crystal silicon rods and adjust the uniformity of radial and axial resistivity distribution of single crystal silicon rods. However, if too much hydrogen enters the lattice of single crystal silicon, it may also introduce additional impurity energy levels into the band structure of the crystal, causing the mode of electron transition to change, thereby affecting the generation and recombination process of carriers, and then changing the electrical properties of the crystal, resulting in a decrease in the conductivity of the single crystal silicon rod. Therefore, controlling the hydrogen concentration C at the edge H1 , the central hydrogen element C H2 , the hydrogen content at 0.65R~0.78R from the center is within the above-mentioned value range, which can further avoid the influence of excessive hydrogen doping concentration on the conductivity of the single crystal silicon rod.

[0071] In some embodiments, the oxygen content in the single crystal silicon rod satisfies: (C Omax -C Omin ) / C Omax ≤10%, preferably (C Omax -C Omin ) / C Omax ≤5%, more preferably (C Omax -C Omin ) / C Omax≤3%, more preferably (C Omax -C Omin ) / C Omax ≤2%; Among them, C Omax is the maximum oxygen content in the single crystal silicon rod, C Omin It is the minimum oxygen content in single crystal silicon rod.

[0072] It is understandable that the oxygen content will also affect the resistivity of single crystal silicon. At lower oxygen content, oxygen atoms will bind some carriers, resulting in a slight increase in resistivity. However, when the oxygen content is too high and oxygen precipitates are formed, lattice distortion and defects will occur around the oxygen precipitates, and the carrier concentration and mobility in these areas will change, which can easily lead to uneven resistivity within the single crystal silicon rod. When the maximum oxygen content and the minimum oxygen content in the single crystal silicon rod meet the above relationship, the fluctuation of the oxygen content in the single crystal silicon rod is controlled within the ideal range, so that the single crystal silicon rod has good oxygen content uniformity as a whole, thereby making the single crystal silicon rod have better electrical stability.

[0073] The total oxygen content in this application can be detected by secondary ion mass spectrometry (SIMS). The reference standards for the analysis method include "ASTM E1078-2009 Standard Guide for Sample Preparation and Installation Procedures for Surface Analysis", "ASTME1504-2011 Standard Specification for Reporting Mass Spectrometry Data in Secondary Ion Mass Spectrometry (SIMS) Measurements" and "ASTM E1829-2009 Standard Guide for Sample Handling Prior to Surface Analysis".

[0074] In some embodiments, the maximum oxygen content C in the single crystal silicon rod is Omax Satisfy: 9ppma≤C Omax ≤11ppma.

[0075] It is understandable that the maximum oxygen content C in the single crystal silicon rod Omax The value of (unit: ppma) can be any value among 9, 9.5, 10, 10.5, 11 or a range between any two values.

[0076] In some embodiments, the minimum oxygen content C in the single crystal silicon rod is Omin Satisfy: 0.5ppma≤C Omin ≤3.1ppma.

[0077] It is understandable that the minimum oxygen content C in the single crystal silicon rod Omin The value (unit: ppma) can be any value among 0.5, 1.0, 1.5, 2.0, 2.5, 3.1 or a range between any two values. Omax and minimum oxygen content C OminWhen the above value range is met, the single crystal silicon rod has better crystal quality.

[0078] In some embodiments, the oxygen precipitate content in the single crystal silicon rod is 0.5-15.5 ppma.

[0079] It can be understood that the value of the oxygen precipitation content in the single crystal silicon rod (unit: ppma) can be any value among 0.5, 2.0, 3.5, 5.0, 6.5, 8.0, 9.5, 11.0, 12.5, 14.0, 15.5 or a range between any two values.

[0080] In some embodiments, the oxygen precipitate content in the single crystal silicon rod is preferably 0.5-10.5 ppma.

[0081] It can be understood that the value of the oxygen precipitation content in the single crystal silicon rod (unit: ppma) can be any value among 0.5, 1.4, 2.3, 3.2, 4.1, 5.1, 6.0, 6.9, 7.8, 8.6, 10, 10.5 or a range between any two values.

[0082] In some embodiments, the oxygen precipitate content in the single crystal silicon rod is further preferably 0.5-9.8 ppma.

[0083] It can be understood that the value of the oxygen precipitation content in the single crystal silicon rod (unit: ppma) can be any value among 0.5, 0.5, 1.2, 1.9, 2.6, 3.3, 4.0, 4.7, 5.4, 6.1, 6.8, 7.5, 8.3, 9.8 or a range between any two values.

[0084] In some embodiments, the oxygen precipitate content in the single crystal silicon rod is further preferably 3.5-9.5 ppma.

[0085] It can be understood that the value of the oxygen precipitation content in the single crystal silicon rod (unit: ppma) can be any value of 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.5, 9.5 or a range between any two values.

[0086] In some embodiments, the interstitial oxygen content in the single crystal silicon rod is 0.5-11 ppma.

[0087] It can be understood that the value of the interstitial oxygen content in the single crystal silicon rod (unit: ppma) can be any value among 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5, 11 or a range between any two values.

[0088] In some embodiments, the interstitial oxygen content in the single crystal silicon rod is preferably 0.5-9.5 ppma.

[0089] It can be understood that the value of the interstitial oxygen content in the single crystal silicon rod (unit: ppma) can be any value among 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5 or a range between any two values.

[0090] In some embodiments, the interstitial oxygen content in the single crystal silicon rod is further preferably 0.5-7 ppma.

[0091] It can be understood that the value of the interstitial oxygen content in the single crystal silicon rod (unit: ppma) can be any value among 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7 or a range between any two values.

[0092] In other embodiments, the interstitial oxygen content in the single crystal silicon rod is preferably 3.1-9 ppma.

[0093] It can be understood that the value of the interstitial oxygen content in the single crystal silicon rod (unit: ppma) can be any value of 3.1, 3.7, 4.3, 4.9, 5.5, 6.1, 6.7, 7.3, 8.0, 8.6, 9.0 or a range between any two values.

[0094] It is understandable that in the lattice of single crystal silicon, oxygen atoms exist in the form of interstitial atoms, i.e., interstitial oxygen. In the process of preparing single crystal silicon rods, oxygen atoms enter the silicon lattice, but do not replace the position of silicon atoms, but are located in the interstitial position between silicon atoms, forming interstitial oxygen. The presence of interstitial oxygen in single crystal silicon will affect its electrical and optical properties. At lower concentrations, interstitial oxygen can interact with some impurities and play a certain passivation role, such as forming complexes with metal impurities, reducing the scattering and recombination centers of these impurities on carriers, thereby improving the electrical properties of single crystal silicon to a certain extent. However, if the interstitial oxygen concentration is too high, it will cause lattice strain, which will affect the crystal quality of single crystal silicon. This application uses infrared absorption measurement method (GB / T1557-2018) to detect the interstitial oxygen content in silicon crystals.

[0095] Oxygen precipitation refers to the precipitates formed by the aggregation of interstitial oxygen under certain conditions (such as heat treatment) in single crystal silicon. These precipitates are formed by the aggregation of multiple oxygen atoms, and usually interact with the silicon lattice to change the local crystal structure. Excessive or uneven distribution of oxygen precipitation will produce a large number of micro-defects, which will become recombination centers for carriers and reduce the electrical properties of single crystal silicon. This application uses the interstitial oxygen content reduction method (GB / T19444-2004) to measure the oxygen precipitation content in single crystal silicon rods.

[0096] In some embodiments, the single crystal silicon rod further contains Group III-V elements, and the Group III-V elements are preferably antimony and phosphorus.

[0097] In some embodiments, the doping concentration of antimony in the single crystal silicon rod is 7.5E+12~6E+14cm -3 .

[0098] It is understandable that the doping concentration of antimony in the single crystal silicon rod (unit: cm -3 ) can be any value among 7.5E+12, 1E+13, 2.5E+13, 5E+13, 7.5E+13, 1E+14, 2.5E+14, 6E+14, or a range between any two values. Since the segregation coefficient of antimony is smaller than that of phosphorus, the effect of antimony doping on the lattice structure of single crystal silicon is relatively small. Controlling the doping concentration of antimony element to meet the above range of values ​​can further reduce the resistivity of single crystal silicon.

[0099] In some embodiments, the doping concentration of phosphorus in the single crystal silicon rod is 1.25E+12~7E+14cm -3 .

[0100] It is understandable that the doping concentration of phosphorus in the single crystal silicon rod (unit: cm -3 ) can be any value among 1.25E+12, 5E+12, 1E+13, 5E+13, 1E+14, 5E+14, 7E+14, or a range between any two values. The doping of antimony and phosphorus can adjust the resistivity uniformity of the single crystal silicon rod, but excessive doping will significantly reduce the resistivity of the single crystal silicon rod. When the doping concentration of antimony and phosphorus meets the above range, the single crystal silicon rod can have the target resistivity and ideal resistivity uniformity.

[0101] A second embodiment of the present application provides a method for preparing a single crystal silicon rod, comprising: Providing silicon raw materials, and obtaining single crystal silicon rods through the steps of material quenching, re-dosing, temperature stabilization, seeding, shouldering, equalizing diameters and finishing; in at least one of the steps of material quenching, re-dosing, temperature stabilization, seeding, shouldering, equalizing diameters and finishing, introducing hydrogen into the silicon raw materials; The single crystal silicon rod has a center and an edge along the radial direction of the single crystal silicon rod. Before the single crystal silicon rod is grown, the hydrogen doping concentration during the solidification process of the single crystal silicon rod is adjusted to control the hydrogen element in the single crystal silicon rod to meet the preset concentration relationship, so that the dislocation density of the single crystal silicon rod is 4~3000atom / cm 2 ; The preset concentration relationship is: 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%; In the formula, C H1 is the hydrogen concentration at the edge, C H2 The concentration of hydrogen at the center.

[0102] It is understandable that the concentration of doping elements during the solidification process of the single crystal silicon rod can be adjusted by adjusting the time and flow rate of introducing hydrogen.

[0103] In some embodiments, the method for preparing a single crystal silicon rod further comprises: Before the equalizing step, adding a metal single substance or alloy containing antimony and phosphorus to the silicon raw material; Before the growth of the single crystal silicon rod is completed, the doping concentration of antimony and phosphorus during the solidification process of the single crystal silicon rod is adjusted to control the doping concentration of antimony in the single crystal silicon rod to 7.5E+12~6E+14cm -3 , and the doping concentration of phosphorus in the single crystal silicon rod is 1.25E+12~7E+14cm -3 .

[0104] In some embodiments, silicon raw materials are placed in the single crystal furnace 100 before being oxidized.

[0105] In some embodiments, after placing the silicon raw material in the single crystal furnace 100, at least one of the steps of chemical reaction, re-feeding, temperature stabilization, seeding, shoulder release, equalizing diameter and finishing is performed to obtain a single crystal silicon rod; before the equalizing diameter step, antimony and phosphorus are added to the silicon raw material, or the antimony and phosphorus elements can be added at the same time; before the equalizing diameter step, antimony and phosphorus elements are added to the silicon raw material, or the antimony and phosphorus elements can be added at different times.

[0106] In some embodiments, before the equal diameter step, antimony and phosphorus are added to the silicon raw material, which can be understood as adding antimony and phosphorus to the silicon raw material before seeding. Before seeding, antimony and phosphorus are added to the silicon raw material, which can be added at the same time; before seeding, antimony and phosphorus are added to the silicon raw material, which can be added at different times.

[0107] In some embodiments, antimony and phosphorus are added to the silicon raw material before seeding, and antimony and phosphorus are added to the silicon raw material at the same time after re-dosing and before seeding. Further, antimony and phosphorus are added to the silicon raw material at the same time after re-dosing and before seeding through a doping device.

[0108] When antimony and phosphorus are added at the same time, their doping effects are superimposed on each other, more significantly adjusting the uniformity of resistivity in the crystal.

[0109] In some embodiments, the time for introducing hydrogen into the silicon raw material satisfies: t 总 =t 1 +t 2 +t 3 +t 4 +t 5 +t 6 +t 7 , and 0.5h≤t 总 ≤82h; Among them, t 总 is the total time of hydrogen introduction, t 1 is the time of hydrogen introduction in the temperature stabilization stage, t 2 is the time of hydrogen introduction during the welding stage, t 3 is the time of hydrogen introduction in the seeding stage, t 4 is the time of introducing hydrogen during the shoulder release phase, t 5 It is the time of introducing hydrogen in the isodiametric stage.

[0110] It is understandable that the total time t for passing hydrogen is 总 Refers to the total time of hydrogen being introduced into each single crystal silicon during its growth into a single crystal silicon rod. 总 The value of (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 a range between any two values. By controlling the time of hydrogen introduction to meet the above value range, the doping concentration and doping uniformity of hydrogen are controlled to have an ideal level.

[0111] In some embodiments, the time for 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).

[0112] Specifically, t 1 ,t 2 ,t 3 ,t 4 ,t 5 ,t 6 ,t 7 are not 0 at the same time, for example, t 1 :t 2 :t 3 :t 4 :t 5 :t 6 :t 7 The ratio can be any value among 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 a range between any two values.

[0113] In some embodiments, the time for 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).

[0114] In some embodiments, it is preferred to introduce hydrogen into the silicon raw material after the re-dosing step is completed.

[0115] It is understandable that hydrogen is introduced during the temperature stabilization stage, and hydrogen can act as a heat transfer medium to make the ambient temperature of the silicon raw material more uniform and stable, prevent local overheating or overcooling of the silicon raw material due to temperature fluctuations, and generate stress, thereby reducing the probability of defects in the silicon crystal; hydrogen introduced during the crystal induction stage can inhibit the adsorption of impurities on the surface of the silicon melt and reduce the risk of impurities entering the growing crystal; hydrogen introduced during the shoulder release stage can regulate the supercooling of the silicon melt, so that the crystal grows at a specific angle and rate, and obtains crystals that meet the size requirements, further reducing dislocations and crystal orientation deviations, and ensuring the consistency of crystal growth; hydrogen introduced during the equal diameter stage helps maintain a stable growth environment and ensures that the hydrogen doping concentration in the silicon crystal is uniform in the radial direction. When the time for introducing hydrogen into the silicon raw material meets the above-mentioned ratio range, the doping concentration and doping uniformity of hydrogen in the single crystal silicon rod can be accurately regulated, thereby reducing dislocations and crystal orientation deviations in the single crystal silicon rod, and can also make the head-to-tail ratio of the dislocation head-to-tail and the crystal orientation deviation amount more inclined to 1, significantly improving the quality and production efficiency of single crystal silicon.

[0116] In some embodiments, the method for preparing a single crystal silicon rod further comprises: after the re-injection step, introducing a protective gas into the silicon raw material; The hydrogen and the protective gas form a mixed gas, and the volume percentage of the hydrogen in the mixed gas is 1-90%.

[0117] It is understandable that the volume percentage of hydrogen in the mixed gas can be any value of 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or a range between any two values. The protective gas can be argon. When the protective gas is introduced while the hydrogen is introduced, on the one hand, a certain gas flow environment can be formed in the single crystal furnace 100, which diffuses around the silicon crystal growth area, prompting the gas to form a stable convection, ensuring the consistency of the crystal growth environment, and avoiding crystal defects caused by local environmental differences; on the other hand, heat can be transferred to other areas outside the silicon crystal growth area through gas flow, thereby playing a cooling role, helping to adjust the temperature gradient, and at the same time, it can take away impurities volatilized from the surface of the silicon melt, which is conducive to the growth of the crystal in a specific direction, reducing the crystal orientation deviation, and improving the overall quality of the single crystal silicon rod. When the volume percentage of hydrogen in the mixed gas meets the above-mentioned value range, it can ensure the growth quality of the single crystal silicon rod while hydrogen doping the single crystal silicon, and avoid the risk of explosion caused by excessive hydrogen content.

[0118] In some embodiments, the volume percentage of hydrogen in the mixed gas is preferably 5-90%.

[0119] It can be understood that the volume percentage of hydrogen in the mixed gas can be any value of 5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, 90%, or a range between any two values.

[0120] In some embodiments, the volume percentage of hydrogen in the mixed gas is preferably 5-35%.

[0121] It is understandable that the volume percentage of hydrogen in the mixed gas can be any value of 5%, 10%, 15%, 20%, 25%, 30%, 35%, or a range between any two values. When the volume percentage of hydrogen in the mixed gas meets the above value range, it can further ensure that sufficient hydrogen is doped into the single crystal silicon.

[0122] In some embodiments, the flow rate of hydrogen is 0.0001-180 slpm.

[0123] It can be understood that the value of the hydrogen flow rate (unit: slpm) can be any value of 0.0001, 1, 30, 60, 90, 120, 150, 180 or a range between any two values.

[0124] In some embodiments, the flow rate of hydrogen is preferably 5-50 slpm.

[0125] It is understandable that the value of the hydrogen flow rate (unit: slpm) can be any value among 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or a range between any two values. When the hydrogen flow rate meets the above range, the hydrogen has an ideal doping concentration in the single crystal silicon rod, while avoiding uneven distribution caused by excessive real-time flow, so that the hydrogen concentration in the axial and radial directions of the single crystal silicon rod has good uniformity.

[0126] In some embodiments, the flow rate of the shielding gas is 40-200 slpm.

[0127] It can be understood that the flow rate of the shielding gas (unit: slpm) can be any value of 40, 60, 80, 100, 120, 140, 160, 180, 200 or a range between any two values.

[0128] In some embodiments, from the end of the re-investment step to the start of the equal diameter step, the volatility η of the III-V group elements is controlled to satisfy: η=(H 1 / 100mm)×100%-15%; Among them, H 1 is the liquid inlet distance in the single crystal furnace 100, unit: mm; volatility η satisfies: 5%≤η≤25%; liquid inlet distance H1 Meet: 20mm≤H 1 ≤40mm.

[0129] like Figure 1 and Figure 2 As shown, it can be understood that a guide tube 10 and a crucible 30 are provided in the single crystal furnace 100. The crucible 30 contains silicon raw materials, which are melted into liquid silicon materials after the material melting step. The guide tube 10 is arranged directly above the crucible 30 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 process of the single crystal silicon rod. 1 is the distance between the lower edge of the guide tube 10 and the liquid surface of the silicon liquid 40. The silicon liquid 40 is the liquid formed after the silicon raw material is melted. 1 The value of will affect the volatilization of doping elements and antimony elements. The larger the liquid-to-mouth distance, the smaller the volatilization rate η of the antimony element, and the smaller the liquid-to-mouth distance, the larger the volatilization rate η of the antimony element. The volatilization rate η of the antimony element affects the doping concentration of the single crystal silicon rod during the growth process, and further affects the resistivity in the single crystal silicon rod and the axial uniformity of the resistivity. Therefore, by controlling the volatilization rate η and the liquid-to-mouth distance H 1 Satisfying the above relationship can ensure that during the growth of the single crystal silicon rod, the volatilization rate η of the antimony element is always in a relatively stable state, thereby keeping the resistivity in the single crystal silicon rod stable, while also avoiding the cost of adding additional antimony raw materials due to excessive volatilization of the antimony element.

[0130] It is understandable that the volatility of group III and V elements will also affect the doping of hydrogen in the crystal. When the volatility of group III and V elements is high, the surface tension of the silicon melt will be reduced, and hydrogen will be more likely to form bubbles on the surface of the silicon melt and escape. The solubility of hydrogen in the silicon melt will decrease, resulting in a decrease in the doping amount of hydrogen in the crystal. Therefore, by controlling the liquid inlet distance H 1 The value of controls the volatility η of the III-V group elements to be within an ideal range, and can also further control the ideal doping concentration of hydrogen elements in the single crystal silicon rod.

[0131] 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. 1 , and adjust the height of the crucible 30 to ensure that the liquid port is at a distance of H 1 After the silicon raw material is melted to form silicon liquid 40, it remains basically constant. 1 Keeping it substantially constant means that the liquid inlet distance H is maintained by adjusting the height of the crucible 30. 1 In the process, the actual liquid port distance H 1The error between the preset liquid port distance and the height of the crucible 30 is no more than ±5% (±1-2 mm). The height of the crucible 30 can be adjusted by a screw lift or a hydraulic lift, or by an automatic control system, or by other height adjustment devices, which will not be described in detail.

[0132] Liquid port distance H 1 The detection is carried out by CCD (Charge-Coupled Device) infrared measuring equipment, which can be realized in the following ways: 1) Install the CCD infrared measuring 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, near an observation window on the side or top of the furnace body, and 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 ensure that the optical path is not blocked by other structures or components in the furnace; 2) constructing an optical path using optical elements such as infrared lenses and reflectors, so that infrared radiation emitted from the surface of the silicon liquid 40 can be focused onto the CCD detector; 3) After the material is oxidized, the CCD detector is calibrated in temperature and space, and the signal intensity curve corresponding to the temperature and position of the silicon liquid 40 is recorded; 4) In the steps of re-casting, seeding, shoulder release, shoulder rotation and equal diameter, the collected infrared images are processed to calculate the height of the liquid surface through the temperature characteristics of the silicon liquid 40, and then the liquid inlet distance H is calculated. 1 .

[0133] By maintaining a relatively constant liquid port distance H 1 , which can form a stable temperature field and airflow field in the single crystal furnace 100. On the one hand, it maintains a suitable temperature gradient at the solid-liquid interface to ensure uniform temperature distribution of the silicon liquid 40 and avoid abnormal growth and defects of silicon crystals. On the other hand, it controls the convection of the silicon liquid 40 to ensure uniform distribution of doping elements and further improve the uniformity of doping concentration. At the same time, it can also make the single crystal silicon rod grow uniformly, reduce crystal defects, and improve the overall quality of the single crystal silicon rod.

[0134] In some embodiments, the volatility η satisfies: 5%≤η≤25%.

[0135] It is understandable that the volatility η can be any value of 5%, 10%, 15%, 20%, 25%, or a range between any two values. When the volatility η satisfies the above range, the doping concentration of the III-V group elements and the hydrogen element as the crystal rod grows can be effectively regulated, 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.

[0136] In some embodiments, the liquid port distance H 1Meet: 20mm≤H 1 ≤40mm.

[0137] It can be understood that the liquid port distance H 1 The value (unit: mm) can be any value among 20, 25, 30, 35, 40 or a range between any two values. Too small liquid nozzle distance will increase the wire breakage rate of single crystal silicon rods, affect the quality of crystal formation, and cause abnormal conditions such as silicon spraying and silicon sticking, while too large liquid nozzle distance will make crystal formation too difficult.

[0138] In some embodiments, a guide tube 10 is provided in the single crystal furnace 100. The guide tube 10 includes a first section 11 and a second section 12 connected to each other, and meets the following conditions: tanα=H 2 / W 1 , and 0≤tanα≤0.58; Wherein, α is the angle between the second section 12 and the first direction X, in degrees; H 2 is the height of the projection of the second segment 12 in the second direction, in mm; W 1 is the length of the projection of the second segment 12 in the first direction, in mm; wherein the first direction intersects the second direction.

[0139] The angle α is the angle between the second section 12 and the first direction X, in degrees; H 2 is the height of the projection of the second segment 12 in the second direction Y, in mm; W 1 is the length of the projection of the second segment 12 in the first direction X, in mm; Figure 1 As shown, the first direction X is a horizontal direction, the second direction Y is a vertical direction, and the first direction X intersects the second direction Y. In some embodiments, the first direction X and the second direction Y are perpendicular to each other.

[0140] In some embodiments, the angle α may be an angle formed by a line connecting the starting end and the ending end of the second segment 12 and the first direction X.

[0141] It can be understood that the first section 11 of the guide tube 10 is enclosed to form a closed side wall, which is usually a cylindrical structure, in an upright cylindrical shape, surrounding the crucible 30, and providing a vertical guide channel for hydrogen and protective gas, etc., so that the gas can flow in a specific direction, thereby ensuring the formation of stable convection near the single crystal silicon rod and the crucible 30, and ensuring the consistency of the crystal growth environment; the second section 12 of the guide tube 10 is connected to the first section 11 and forms a bottom, and the second section 12 extends from the connection with the first section 11 to the inside of the guide tube 10, and at the same time tilts toward the side close to the silicon liquid 40, so that the extension direction of the second section 12 forms an angle α with the first direction X. When tanα=0, the second section 12 is parallel to the first direction X.

[0142] In some embodiments, the value of tanα is preferably 0.0001≤tanα≤0.58, that is, the second segment 12 forms an acute angle α with the extension direction and the horizontal direction.

[0143] It is understandable 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 a range between any two values. In the process of guiding the gas in the single crystal furnace 100, the angle α will also affect the volatilization of the doping elements. The larger the angle α, the smaller the volatilization rate of the III-V elements. At the same time, more oxygen will enter the single crystal silicon rod. The smaller the angle α, the greater the volatilization rate of the III-V elements. Therefore, controlling the value of tanα to meet the above range of values ​​can ensure that the III-V elements and hydrogen in the single crystal silicon rod have a reasonable content.

[0144] In some embodiments, Figure 1 and Figure 3 As shown, the single crystal furnace 100 includes a top cover 20, and the top cover 20 is provided with a first vent hole 21 and a second vent hole 22. The first vent hole 21 is arranged around the second vent hole 22. The first vent hole 21 is used to introduce hydrogen into the single crystal furnace 100, and the second vent hole 22 is used to introduce protective gas into the single crystal furnace 100, satisfying: D max ≥2D 1 >D 2 ; Among them, D max is the maximum diameter of the guide tube 10, D 1 is the first distance between the first vent hole 21 and the center of the top cover 20, D 2 is the diameter of the second vent hole 22 .

[0145] In some embodiments, the first distance D 1 Meet: 350mm≤D 1 ≤500mm.

[0146] In some embodiments, the diameter D of the second vent hole 22 is 2 Meet: 500mm≤D 2 ≤800mm.

[0147] It can be understood that the first distance D 1 The value of (unit: mm) can be any value among 350, 380, 410, 440, 470, 500 or a range between any two values. The diameter D of the second vent hole 22 2 The value (unit: mm) can be any value among 500, 550, 600, 650, 700, 750, 800 or a range between any two values.

[0148] In some embodiments, the maximum diameter D max satisfy: D max ≥2W 1 +W 2 ; It is understandable that when the first section 11 of the guide tube 10 is enclosed to form a cylindrical structure, the diameter of the guide tube 10 can be gradually reduced in the vertical direction toward the crucible 30, or can remain unchanged, and the maximum diameter D max By satisfying the above relationship, the flow direction and speed of the protective gas in the single crystal furnace 100 can be further adjusted, thereby improving the stability of the crystal structure of the single crystal silicon rod during the crystal pulling process.

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

[0150] like Figure 1~Figure 3 As shown, the second vent 22 is a channel that passes through the top cover 20, and there are a plurality of first vents 21, which are arranged around the outer periphery of the second vent 22; the number of the first vents 21 is preferably 8 to 10. During the crystal pulling process, hydrogen enters the guide tube 10 through the first vent 21, and contacts with the silicon liquid 40 in the crucible 30 to achieve doping, and the protective gas enters the guide tube 10 through the second vent 22, and flows in the area inside and outside the guide tube 10 to protect the single crystal silicon rod. It can be understood that the protective gas can be directly introduced into the guide tube 10 through the second vent 22, or it can be introduced through a furnace tube or other device, and then flow through the second vent 22 into the guide tube 10. When the first spacing D 1 The diameter D of the second vent hole 2 Meet 2D 1 >D 2 , the hydrogen can have a larger flow space in the guide tube 10 and be fully mixed with the protective gas, thereby improving the uniformity of the doping process.

[0151] In some embodiments, the maximum diameter D max Meet: 700mm≤D max ≤1200mm.

[0152] In some embodiments, the length W 1 Meet: 155mm≤W 1 ≤455mm.

[0153] In some embodiments, the maximum size W 2 Meet: 290mm≤W2 ≤390mm.

[0154] In some embodiments, the height H 2 Satisfy: 0≤H 2 ≤300mm.

[0155] It is understood that the maximum diameter D max The value of (unit: mm) can be any value among 700, 800, 900, 1000, 1100, 1200 or the range between any two values; the length W 1 The value (unit: mm) can be any value among 155, 200, 250, 300, 350, 400, 455 or the range between any two values; the maximum size W 2 The value (unit: mm) can be any value among 290, 310, 330, 350, 370, 390 or the range between any two values; the height H 2 The value of (unit: mm) can be any value among 0, 50, 100, 150, 200, 250, 300 or a range between any two values. 1 , W 2 , H 2 and D max When the above value range is met, the volume Vs of the gas flow area can be in an ideal range, thereby further optimizing the guiding effect of the guide tube 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 have ideal uniformity.

[0156] The bottom of the guide tube 10 and the top cover 20 have a third distance H 3 , satisfying: 0.5m≤H 3 ≤1.5m.

[0157] It can be understood that the third spacing H 3 The value (unit: m) can be any value among 0.5, 0.7, 0.9, 1.1, 1.3, 1.5 or a range between any two values. 3 When the above value range is met, the hydrogen and protective gas introduced into the single crystal furnace 100 have enough flow space to form convection, ensuring a stable gas field and temperature field in the guide tube 10, thereby ensuring the growth quality of the single crystal silicon rod.

[0158] Based on the above embodiments, Figure 4As shown by the shadow in the figure, the first section 11 and the second section 12 enclose a receiving chamber 13, and the receiving chamber 13 has a first gas flow area 50; between the outer wall of the guide tube 10 and the inner wall of the single crystal furnace 100 and between the growing single crystal silicon rod and the inner wall of the single crystal furnace 100, there is a second gas flow area 60. It can be understood that the second gas flow area 60 is located in the single crystal furnace 100, and the gas flow area is above the liquid surface of the silicon liquid 40. Further, the second gas flow area 60 surrounds the guide tube 10 (of course, it also surrounds the growing single crystal silicon rod). It can be understood that the second gas flow area 60 includes a first area 61 and a second area 62, wherein the first area 61 is an area for gas flow between the guide tube 10 and the inner wall of the single crystal furnace 100, and the second area 62 is an area for gas flow located above the liquid surface of the silicon liquid 40 and after removing the volume of the single crystal silicon itself.

[0159] 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, V 2 is the second volume of the second region 62 .

[0160] It can be understood that the first volume V of the first region 61 1 The value of the angle is affected by the maximum diameter D max and the third spacing H 3 The second volume V of the second region 62 is affected by 2 The value of is affected by the liquid port distance H 1 and maximum diameter D max By adjusting 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 diverted after reaching the crystal growth interface. Therefore, the volume Vs of the second gas flow area 60 is controlled to have a reasonable size, which 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.

[0161] A third embodiment of the present application provides a silicon wafer prepared from the single crystal silicon rod in any of the above embodiments.

[0162] In some embodiments, the silicon wafer contains hydrogen, and the content of hydrogen is 0.0001cm -3 ≤C H1 ≤1E+17cm -3 ; The dislocation density of silicon wafers is 4~500atom / cm 2; The resistivity of silicon wafer is 6~32Ω·cm; The silicon wafer has a <100> The directional offset is 0~±5°; the oxygen content in the silicon wafer is 0.5~11ppma.

[0163] A fourth embodiment of the present application provides a solar cell, including a silicon substrate, wherein the silicon substrate is prepared from the silicon wafer in the above embodiment; Among them, the resistivity of the silicon substrate is 6~32Ω•cm and the thickness is 120~160μm.

[0164] In some embodiments, the silicon substrate includes a doped region, and the doped region is doped with hydrogen, antimony, and phosphorus; The concentration of hydrogen in the doped region is 0.0001~1E+17cm -3 ; The concentration of antimony in the doped region is 7.5E+12~6E+14cm -3 ; The phosphorus concentration in the doped region is 1.25E+12~7E+14cm -3 .

[0165] The following is a description of the single crystal silicon rod and the preparation method thereof provided by the present application in conjunction with specific embodiments: Example 1 The quartz crucible 30 is loaded with polycrystalline silicon blocks or recycled materials. For example, solid silicon raw materials are first piled into the quartz crucible 30 , and then the quartz crucible 30 filled with silicon materials is placed in the single crystal furnace 100 .

[0166] The single crystal furnace 100 is evacuated, and the solid silicon in the quartz crucible 30 is gradually melted into a molten state using a bottom heater and a main heater with a power of 90 kW.

[0167] Because the solid silicon material in the quartz crucible 30 is stacked and placed, after being heated and melted, the actual volume occupied by the silicon material in the quartz crucible 30 is reduced, and the melted silicon material does not reach the maximum loading capacity of the quartz crucible 30. Therefore, it is necessary to use a re-feeder to fill the quartz crucible 30 with silicon material for a second time. During the filling process, the heater simultaneously melts the silicon material in the quartz crucible 30.

[0168] After the re-dosing is completed, the antimony (Sb) dopant is loaded into the doping spoon installed in advance in the single crystal furnace 100. After the silicon material in the quartz crucible 30 is completely melted, the temperature adjustment stage is turned to the temperature adjustment stage. Before the seed crystal is melted, the Sb dopant in the doping spoon is poured into the silicon liquid 40, and the seed crystal is inserted into the liquid surface. The critical crystallization temperature of the liquid surface temperature is reached by controlling the power parameters. The doping amount is calculated by segregation according to the target resistivity. Taking 1000kg of full crucible material as an example, a single shot of primary polycrystalline contains 20g of antimony (Sb) dopant.

[0169] After the seed crystal and the liquid level reach the crystallization temperature, the seed crystal is pulled upwards, and the actual single crystal diameter is adjusted to within the range of 275-285mm round rod diameter by adjusting parameters such as power and pulling speed; after the shoulder is released, the shoulder rotation process is used to enter the silicon rod equal diameter process.

[0170] During the equal-diameter process, the furnace pressure was adjusted to 8-15 torr, the gas flow rate to 100 slpm, the crystal rotation to 9-6 rpm, the crucible rotation to 6-9 rpm, and the power (50KW) was adjusted to volatilize antimony. When the equal-diameter length was 4800mm, the silicon rod drawing was completed by finishing.

[0171] In addition to other processes of the equal diameter process, in order to reduce the volatilization of antimony, a high furnace pressure is mainly used to suppress the volatilization of antimony, and the furnace pressure is between 15-30torr.

[0172] Hydrogen and protective gas argon need to be introduced in each of the above stages, with a volume ratio of hydrogen to argon of 50%; the flow rate of hydrogen is 100 slpm, and the flow rate of argon is 120 slpm.

[0173] The single crystal silicon rod is cut into silicon wafers in the following steps: The prepared single crystal silicon rod is subjected to the steps of cutting, chamfering, grinding, polishing, cleaning, testing, etc. to obtain a single crystal silicon wafer.

[0174] The doping concentration, dislocation and crystal orientation deviation of the prepared silicon wafer were tested in the same way as the single crystal silicon rod. The dislocation density of the silicon wafer was 480atom / cm 2 , oxygen content is 8.44ppma, resistivity is 0.4~2.1Ω·cm, in the crystal direction <100> The offset in direction is 5°.

[0175] 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 and the flow rate and introduction time of hydrogen are adjusted.

[0176] 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.

[0177] The specific hydrogenation parameters of Examples 1-25 are shown in Table 1.

[0178] Table 1

[0179]

[0180]

[0181] The single crystal furnace parameters in Examples 1-7 and Comparative Examples 1-3 are shown in Table 2.

[0182] Table 2

[0183] The doping element content, oxygen content and resistivity of Examples 1-7 and Comparative Examples 1-3 were tested by the following method: Resistivity test: Use KDY~1A resistivity tester to test the resistivity of the crystal rod.

[0184] The test method for oxygen content is as follows: oxygen content measures the oxygen content of the crystal rod head. The test method refers to GB / T 1557~2018. Nicolet 6700 Fourier transform infrared spectrometer is used to test the oxygen content in the crystal rod. By cutting test samples with a thickness of ≥2mm at the head and tail of the single crystal, the interstitial oxygen content at the set position in the silicon single crystal sample is determined by infrared spectroscopy in accordance with GB / T 1557 national standard; According to the thermal cycle process of manufacturing integrated circuits, the silicon wafer is subjected to simulated heat treatment, and the interstitial oxygen content of the silicon wafer before and after heat treatment is measured by infrared absorption method. The difference is regarded as the amount of interstitial oxygen precipitation.

[0185] Antimony and phosphorus content test: GDMS (glow discharge mass spectrometry) is used to measure the content of trace elements in silicon in accordance with the national standard GB / T 32651.

[0186] Test of hydrogen content: The inert gas fusion technique was used to heat the sample to over 3000°C in a pulse furnace, and the hydrogen content was determined by the thermal conductivity method.

[0187] The test results are shown in Table 3.

[0188] Table 3

[0189] According to the above embodiments and comparative examples, it can be seen that the single crystal silicon rods and silicon wafers provided in the present application, as well as the single crystal silicon rods and silicon wafers prepared by the preparation method provided in the present application, have relatively ideal performance in terms of resistivity uniformity, dislocation density, crystal growth direction, etc.

[0190] The above is a detailed introduction to the single crystal silicon rod and its preparation method, and the silicon wafer provided in the embodiments of the present application. Specific examples are used in the present application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and core idea of ​​the present application; ordinary technicians in this field should understand that: they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A single crystal silicon rod, characterized in that: The single crystal silicon rod contains hydrogen elements, and 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; 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 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.

4. A single crystal silicon rod according to claim 3, characterized in that: The tail crystal of the single crystal silicon rod is in the crystal direction <100> The offset s1 in the direction is 0~±5°; the head crystal of the single crystal silicon rod is in the crystal direction <100> The directional offset s2 is 0~±5°.

5. The single crystal silicon rod according to claim 1, characterized in that: The resistivity of the single crystal silicon rod is 6-32Ω·cm.

6. The single crystal silicon rod according to claim 1, 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 0.56R~0.78R from the center is 0.0001cm -3 ~1E+17cm -3 .

7. The single crystal silicon rod according to claim 1, characterized in that: The oxygen content in the single crystal silicon rod satisfies: (C Omax -C Omin ) / C Omax ≤10%; Among them, C Omax is the maximum oxygen content in the single crystal silicon rod, C Omin is the minimum oxygen content in the single crystal silicon rod.

8. The single crystal silicon rod according to claim 7, characterized in that: The maximum oxygen content C in the single crystal silicon rod Omax Satisfy: 9ppma≤C Omax ≤11ppma; and / or, The minimum oxygen content C in the single crystal silicon rod Omin Satisfy: 0.5ppma≤C Omin ≤3.1ppma.

9. The single crystal silicon rod according to claim 1, characterized in that: The oxygen precipitate content in the single crystal silicon rod is 0.5-15.5 ppma; and / or, The interstitial oxygen content in the single crystal silicon rod is 0.5-11 ppma.

10. The single crystal silicon rod according to claim 1, characterized in that: The single crystal silicon rod further comprises Group III-V elements, and the Group III-V elements include antimony and phosphorus; The doping concentration of the antimony element in the single crystal silicon rod is 7.5E+12~6E+14cm -3 and / or, The doping concentration of the phosphorus element in the single crystal silicon rod is 1.25E+12~7E+14cm -3 .

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; Wherein, along the radial direction of the single crystal silicon rod, the single crystal silicon rod has a center and an edge, and before the growth of the single crystal silicon rod is completed, the hydrogen element doping concentration during the solidification process of the single crystal silicon rod is adjusted to control the hydrogen element in the single crystal silicon rod to meet a preset concentration relationship, so that the dislocation density of the single crystal silicon rod is 4-3000atom / cm 2 ; wherein the preset concentration relationship is: 0≤(C H1 -C H2 ) / C H2 ≤35%; In the formula, C H1 is the hydrogen concentration at the edge, C H2 is the hydrogen concentration at the center.

12. The method for preparing a single crystal silicon rod according to claim 11, characterized in that: Also includes: Before the step of equalizing the diameter, adding a metal single substance or alloy containing antimony and phosphorus to the silicon raw material; Before the growth of the single crystal silicon rod is completed, the doping concentrations of antimony and phosphorus during the solidification of the single crystal silicon rod are adjusted to control the doping concentration of antimony in the single crystal silicon rod to be 7.5E+12~6E+14cm -3 , and the doping concentration of the phosphorus element in the single crystal silicon rod is 1.25E+12~7E+14cm -3 .

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 satisfies: t 总 =t1+t2+t3+t4+t5+t6+t7, and 0.5h≤t 总 ≤82h; Among them, t 总 is the total time of hydrogen introduction, t1 is the time of hydrogen introduction in the material chemical stage, t2 is the time of hydrogen introduction in the re-investment stage, t3 is the time of hydrogen introduction in the temperature stabilization stage, t4 is the time of hydrogen introduction in the crystal induction stage, t5 is the time of hydrogen introduction in the shoulder release stage, t6 is the time of hydrogen introduction in the equal diameter stage, and t7 is the time of hydrogen introduction in the finishing stage.

14. The method for preparing a single crystal silicon rod according to claim 13, characterized in that: The time for introducing hydrogen into the silicon raw material also satisfies: t1:t2:t3:t4:t5:t6:t7=(0~10):(0~8):(0~2):(0~1.5):(0~3):(0~55):(0~2).

15. 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%; or, The flow rate of the hydrogen is 0.0001~180slpm; or, The flow rate of the protective gas is 40-200 slpm.

16. The method for preparing a single crystal silicon rod according to claim 15, characterized in that: From the end of the re-investment step to the start of the equal diameter step, the volatility η of the III-V group elements 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.

17. The method for preparing a single crystal silicon rod according to claim 16, characterized in that: The single crystal furnace (100) is provided with a guide tube (10), wherein the guide tube (10) comprises a first section (11) and a second section (12) connected to each other, and meets the following requirements: tanα=H2 / W1, and 0≤tanα≤0.58; Wherein, α is the angle formed by the second section (12) and the first direction (X), in degrees; H2 is the height of the projection of the second section (12) in the second direction (Y), in millimeters; W1 is the length of the projection of the second section (12) in the first direction (X), in millimeters; wherein the first direction (X) and the second direction (Y) intersect.

18. The method for preparing a single crystal silicon rod according to claim 17, 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), satisfying: D max ≥2D1>D2; Among them, D max is the maximum diameter of the guide tube (10), D1 is a first distance between the first ventilation hole (21) and the center of the top cover (20), and D2 is the diameter of the second ventilation hole (22).

19. 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 18.

20. The silicon wafer according to claim 19, 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 6~32Ω·cm; The silicon wafer has a crystal orientation <100> The deviation in the direction is 0~±5°; the oxygen content in the silicon wafer is 0.5~11ppma.

21. A solar cell, characterized in that: Comprising a silicon substrate, wherein the silicon substrate is prepared from the silicon wafer according to claim 19 or 20; The resistivity of the silicon substrate is 6-32Ω•cm, and the thickness is 120-160μm.

22. A solar cell according to claim 21, characterized in that: The silicon substrate comprises a doped region, wherein the doped region is doped with hydrogen, antimony and phosphorus; The concentration of hydrogen in the doping region is 0.0001~1E+17cm -3 ; The antimony concentration in the doping region is 7.5E+12~6E+14cm -3 ; The phosphorus concentration in the doped region is 1.25E+12~7E+14cm -3 .

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