WO2023208156A1 - 一种降低单晶硅氧含量的方法及晶棒 - Google Patents

一种降低单晶硅氧含量的方法及晶棒 Download PDF

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WO2023208156A1
WO2023208156A1 PCT/CN2023/091407 CN2023091407W WO2023208156A1 WO 2023208156 A1 WO2023208156 A1 WO 2023208156A1 CN 2023091407 W CN2023091407 W CN 2023091407W WO 2023208156 A1 WO2023208156 A1 WO 2023208156A1
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rotation
shoulder
crucible
oxygen content
reducing
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PCT/CN2023/091407
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English (en)
French (fr)
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陈永亮
张文霞
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Tcl中环新能源科技股份有限公司
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Publication of WO2023208156A1 publication Critical patent/WO2023208156A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • C30B15/02—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • C30B15/20—Controlling or regulating
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/06—Silicon

Definitions

  • the present application belongs to the technical field of solar Czochralski silicon single crystal manufacturing and Czochralski semiconductor silicon single crystal manufacturing technology, and in particular relates to a method for reducing the oxygen content of single crystal silicon and a crystal rod.
  • Czochralski silicon Key product characteristics in Czochralski silicon include oxygen content, carbon content, minority carrier lifetime, resistivity, and defects.
  • the source of the oxygen content is the incorporation of SiO produced by the reaction between the quartz crucible and the silicon raw material. At high temperatures, most of the SiO volatilizes from the free surface of the melt, and after the decomposition of the SiO in the diffusion boundary layer at the front end of the solid-liquid interface, oxygen atoms will segregate. phenomenon into the crystal rod.
  • This application provides a method and crystal rod for reducing the oxygen content of single crystal silicon, which effectively solves the problems of the existing technology.
  • embodiments of the present application provide a method for reducing the oxygen content of single crystal silicon, including:
  • the rotation speed of the crucible is adjusted from the second crucible rotation to the third crucible rotation, and the temperature continues to be lowered until the end;
  • Argon gas needs to be introduced in any one or several steps of material mixing, re-injection, welding, seeding, shoulder expansion, shoulder rotation and equal diameter.
  • the introduction ratio of the hydrogen gas and the argon gas ranges from 1:9 to 5:5.
  • the flow rate of the mixed gas containing the hydrogen gas and the argon gas ranges from 85 to 120 slpm.
  • the introduction ratio of the hydrogen gas and the argon gas ranges from 1:9 to 2:5.
  • the flow rate of the mixed gas containing the hydrogen gas and argon gas ranges from 95 to 110 slpm.
  • the range of the first impeller rotation is 9 to 14 r/min.
  • the range of the second crucible is 7 to 12 r/min.
  • the third impeller rotation range is 6 to 10 r/min.
  • the second rotation is lower than the first rotation.
  • the third turn is lower than the second turn.
  • the difference speed between the second crucible rotation and the first crucible rotation is ⁇ 2 r/min.
  • the difference speed between the second crucible rotation and the third crucible rotation is ⁇ 3 r/min.
  • the third crucible rotation range is 7 to 9 r/min.
  • the first power of the heater is reduced in a range of 10 to 25 kw.
  • the first power of the heater is reduced during the shoulder expansion process; the reduction range of the first power is 15 to 20 kw.
  • the second power of the heater is reduced during the equal diameter process, and the reduction range of the second power is 1 to 5 kW.
  • a step of raising the temperature is further included, including:
  • H 1 is the crystal pulling length
  • H 2 is the total length of the target crystal rod.
  • the pulling speed ranges from 1.4 to 2.2 mm/min.
  • H 1 is the crystal pulling length
  • H 2 is the total length of the target crystal rod.
  • the first pulling speed is lower than the second pulling speed.
  • a mixed gas containing hydrogen and argon is introduced during the shoulder expansion, shoulder rotation and equal diameter steps.
  • a first crucible is used during the seeding process, and the first crucible is adjusted to the second crucible during the shoulder setting and shoulder turning processes.
  • the method for reducing the oxygen content of single crystal silicon described in this application includes:
  • the rotation speed of the crucible is adjusted from the second crucible rotation to the third crucible rotation, and the temperature continues to be lowered until the end.
  • embodiments of the present application also provide a crystal rod, which is prepared by the above preparation method.
  • this application provides a method and crystal rod for reducing the oxygen content of single crystal silicon.
  • the method of this application includes: introducing hydrogen in any one or several steps of material mixing, re-investment, welding, seeding, shoulder expansion, shoulder rotation and equal diameter; during the process of seeding, shoulder expansion, shoulder rotation Adjust the crucible rotation speed from the first crucible rotation to the second crucible rotation, reduce the temperature during the shoulder expansion process, and keep the temperature unchanged during the shoulder rotation process; adjust the crucible rotation speed from the second crucible rotation to the second crucible rotation during the equal diameter step. Turn the three crucibles, and continue to lower the temperature until the end.
  • Argon gas needs to be introduced in any one or several steps of material mixing, re-throwing, welding, seeding, shoulder expansion, shoulder rotation and equal diameter.
  • hydrogen can reduce the oxygen content in the single crystal through the hydrogen reduction method, reduce the destructive effect of oxygen precipitation on the mechanical strength of single crystal silicon, facilitate the growth of single crystal, reduce the production of defective products, and improve crystal quality. Great product quality.
  • Figure 1 is a schematic structural diagram of the crystal ingot preparation process according to the embodiment of the present application.
  • the main source of oxygen in the crystal rod is the incorporation of SiO produced by the reaction between the quartz crucible and the silicon raw material.
  • SiO produced by the reaction between the quartz crucible and the silicon raw material.
  • the silicon melt and quartz crucible undergo a chemical reaction: Si+SiO 2 ⁇ 2SiO SiO ⁇ Si+O
  • the oxygen content in single crystal silicon drawn in argon can reach 1017 ⁇ 1018 atoms/cm 3 , most of which is dissolved in the crystal in an interstitial state and forms non-electroactive SiO 2 groups.
  • the oxygen content is measured by infrared absorption. Due to the vibration of the Si-O bond of the SiO 2 group, a strong absorption band is produced at the infrared wavelength of 8.8 ⁇ m (1135.90 cm ⁇ 1 ).
  • Single crystal silicon will have an electrically active thermal donor effect after heat treatment at 400°C.
  • the thermal donor concentration is proportional to the third power of the interstitial oxygen concentration in Si, that is, n ⁇ N 3 .
  • the thermal donor effect is closely related to the growth history and oxygen content of single crystal silicon. Due to the existence of the thermal donor effect, the resistivity of N-type samples decreases and the resistivity of P-type samples increases. These changes in properties affect the uniformity of the radial resistivity of the silicon wafer, which has an important impact on the production of electronic devices.
  • the experiment has been conducted for 400 years. After heat treatment at a temperature of ⁇ 780°C, the 8.8 ⁇ m absorption peak of dissolved oxygen weakens as the temperature increases.
  • the diameter is about 60nm.
  • the diameter of the precipitate on the right will increase with the increase of heat treatment temperature.
  • the diameter of the precipitate is 100 ⁇ 200nm; when the temperature reaches 930°C, the diameter of the precipitate is 250nm; when the temperature rises to 1000 At °C, these precipitates are in the form of flakes, with a diameter of up to 400nm; when the temperature is higher than 1200 °C, the precipitates will be re-dissolved, and oxygen precipitation will have a certain destructive effect on the mechanical strength of single crystal silicon.
  • This application provides a method for reducing the oxygen content of single crystal silicon, including:
  • the crucible rotation speed is adjusted from the second crucible rotation to the third crucible rotation, and the temperature continues to decrease until the end;
  • hydrogen gas should be introduced and argon gas should be introduced at the same time.
  • hydrogen gas is introduced into the single crystal furnace where the inert gas is introduced.
  • the hydrogen gas introduction method can be continuous ventilation with production, or it can be ventilated at intervals according to certain process steps, and other processes can not be ventilated.
  • This application adds hydrogen into the single crystal furnace and reduces the oxygen-containing compounds at the gas-liquid interface in the furnace into water vapor through a hydrogen reduction reaction, which can significantly reduce the oxygen content, hydrogen energy and dislocations at the solid-liquid interface and the liquid surface.
  • the dangling bonds are combined to achieve the purpose of removing the electrical activity of dislocations. Reducing the oxygen content in the single crystal will further eliminate the light attenuation of the single crystal.
  • a single silicon rod with a longer length can be prepared, improving the yield and quality of the product.
  • hydrogen-containing gas can reduce the oxygen content of single crystal silicon, especially for boron, gallium, and phosphorus-doped single crystals.
  • Hydrogen-doped silicon can be used to passivate impurities and defects. Activity, improve device performance; hydrogen can combine with deep-level metals such as cobalt, platinum, gold, nickel, etc. to remove or form other forms of deep-level complexes to increase product life.
  • changing the crucible in this application can weaken the reaction between the melt and the quartz crucible, and minimize the segregation of oxygen atoms into the crystal rod after the decomposition of SiO in the diffusion boundary layer at the front end of the solid-liquid interface.
  • the inert argon gas can promote the high oxygen content of the molten silicon.
  • the oxygen-containing compounds in the area volatilize and reduce the oxygen concentration at the solid-liquid interface to reduce the oxygen content of part of the single crystal silicon. Therefore, passing the mixed gas of the two is a better choice, and the oxygen content can be reduced through two aspects at the same time.
  • hydrogen gas is simultaneously introduced during the introduction of argon gas (hydrogen gas and argon gas are mixed and introduced), and the inert argon gas is discharged.
  • change the order in which the two gases are introduced for example, introduce hydrogen first and then argon to promote the volatilization of oxygen-containing compounds in the high-oxygen zone of the molten silicon and reduce the oxygen concentration at the solid-liquid interface to reduce the monocrystalline silicon. oxygen content.
  • the input ratio of hydrogen to argon ranges from 1:9 to 5:5, and the hydrogen content is lower than the argon content; such as the input ratio of hydrogen to argon (volume ratio: v/v) range For 1:9, 2:9, 3:9, 4:9, 5:9, 1:5, 2:5, 3:5, 4:5, Any value in 5:5 or a range of any two values.
  • the flow rate of the mixed gas formed by hydrogen and argon ranges from 85 to 120 slpm, such as any value among 85, 90, 95, 100, 105, 110, 115, and 120 or a range of any two values.
  • the introduction ratio of hydrogen gas and argon gas ranges from 1:9 to 2:5.
  • the flow rate of the mixed gas formed by hydrogen and argon ranges from 95 to 110 slpm, such as any value among 95, 100, 105, and 110 or a range of any two values.
  • the range of the first turning speed is 9 to 14 r/min, which is smaller and basically the same as the turning speed in the seeding, shoulder expansion, and shoulder turning steps of the prior art.
  • the first pot is converted to any value among 9, 10, 11, 12, 13, and 14 or a range composed of any two values.
  • the second impeller rotation range is 7 to 12 r/min.
  • the second pot is converted to any value among 7, 8, 9, 10, 11, 12 or a range of any two values.
  • the third impeller rotation range is 6 to 10 r/min.
  • the third pot is converted to any value among 6, 7, 8, 9, and 10 or a range of any two values.
  • the second rotation is lower than the first rotation.
  • the crucible rotation in the steps of seeding, shoulder expansion, and shoulder rotation is not changed.
  • changing the crucible rotation can weaken the reaction between the melt and the quartz crucible, and reduce the diffusion boundary layer at the front end of the solid-liquid interface as much as possible. After SiO is decomposed, oxygen atoms will enter the crystal rod through segregation.
  • the differential speed R 1 between the second crucible rotation and the first crucible rotation is ⁇ 2 r/min. In some embodiments, the differential speed R 1 of the second crucible and the first crucible is any value among 0.5 r/min, 1 r/min, 1.5 r/min or 2 r/min, or a range consisting of any two values. This application further reduces the segregation of oxygen atoms into the crystal rod after the decomposition of SiO in the diffusion boundary layer at the front end of the solid-liquid interface by controlling the differential speed between the second crucible and the first crucible.
  • the third turn is lower than the second turn.
  • the differential speed R 2 of the second crucible and the third crucible is ⁇ 3 r/min. In some embodiments, the differential speed R 2 of the second crucible and the third crucible is 3 to 5 r/min. min. In some embodiments, the differential speed R 2 of the second crucible and the third crucible is any value or any two values among 3r/min, 3.5r/min, 4.0r/min, 4.5r/min or 5r/min. range of composition.
  • the crucible rotation speed of this application is slightly lower in the equal diameter stage, which can weaken the reaction between the melt and the quartz crucible, and minimize the segregation of oxygen atoms into the crystal rod after the decomposition of SiO in the diffusion boundary layer at the front end of the solid-liquid interface.
  • the third impeller rotation range is 7 to 9 r/min.
  • the crucible rotation speed is the first crucible rotation in the material mixing, re-throwing, and welding stages, the crucible rotation speed is adjusted to the second crucible rotation in the seeding, shoulder expansion, and shoulder rotation stages, and the crucible rotation speed is adjusted in the equal diameter step.
  • this application gradually reduces the crucible rotation speed and controls the differential speed between crucible rotations to maximize After the SiO that reduces the diffusion boundary layer at the front end of the solid-liquid interface is decomposed, oxygen atoms will enter the crystal rod through segregation.
  • the first crucible is used during the seeding process, and the first crucible is adjusted to the second crucible during the shoulder setting and shoulder turning processes.
  • the first power P 1 kW of the heater is reduced during the shoulder expansion process; the first power reduction amplitude W 1 ranges from 10 to 25 kW.
  • the first power reduction amplitude W 1 is any value of 15kW, 16kW, 17kW, 18kW, 19kW, 20kW or a range of any two values; for example, the first power reduction amplitude W 1 is 15 to 20kW.
  • the power of the heater is reduced during the shoulder expansion process, thereby cooling the temperature during the drawing process.
  • the decrease in the first power W 1 is the difference between the first power P 1 kW after the crystallization is completed and the shoulder expansion stage.
  • the difference between the second power P 2 kW, that is, W 1 P 1 ⁇ P 2 .
  • the first power P 1 ranges from 60 to 75 kW.
  • the value of P 1 is any value among 60kW, 65kW, 70kW, and 75kW or a range of any two values.
  • the range of the second power P 2 is 35 to 65 kW.
  • the value of P 2 is any value among 35 kW, 40 kW, 45 kW, 50 kW, 55 kW, 60 kW and 65 kW or a range consisting of any two values.
  • 1 ⁇ t 1 ⁇ 3 for example, the value of t 1 is any value among 1, 2, and 3 or a range consisting of any two values.
  • the temperature is continued to be lowered during the equal diameter process, also by reducing the power of the heater to reduce the temperature during the drawing process.
  • the power of the heater during the equal diameter process is reduced from the second power P 2 to the third power P 3 , where the range of the second power drop W 2 is 1 to 5kW.
  • a temperature increasing step is also included:
  • H 1 is the crystal pulling length
  • H 2 is the total length of the target crystal rod.
  • the third power increase W 3 is any value of 2kW, 2.5kW, 3kW or a range of any two values.
  • W 3 P 4 -P 3 .
  • the third power P 3 ranges from 30 to 64kW, for example, the value of P 3 is 30kW, 35kW, 40kW, Any value among 45kW, 50kW, 55kW, 60kW, 64kW or a range consisting of any two values.
  • the range of P 4 is 32 to 67 kW.
  • the value of P 2 is any value of 32 kW, 35 kW, 40 kW, 45 kW, 50 kW, 55 kW, 60 kW, 65 kW, 67 kW or a range consisting of any two values. .
  • the value of H 2 is any value among 3000mm, 3500mm, 4000mm, 4500mm or a range composed of any two values.
  • the length of the crystal rod is H 1 , excluding the shoulder length.
  • This application simultaneously adjusts the rotation speed of the crucible and the power of the heater to slow down the rotation speed and reduce the temperature, which can weaken the reaction between the melt and the quartz crucible, and minimize the oxygen decomposition of the SiO diffusion boundary layer at the front end of the solid-liquid interface. Atoms will enter the crystal rod through segregation.
  • the drawing speed ranges from 1.4 to 2.2 mm/min. Such as 1.4 ⁇ 2.0mm/min, 1.6 ⁇ 1.8mm/min.
  • the value of the pulling speed is any value among 1.4mm/min, 1.6mm/min, 1.8mm/min, 2.0mm/min, 2.2mm/min or a range consisting of any two values.
  • the crystal pulling length is H 1 and the target total length of the crystal rod is H 2 ;
  • the crystal pulling speed is the first pulling speed V 1
  • the first pulling speed V 1 ranges from 1.4 to 1.7mm/min; for example, the value of the first pulling speed V 1 is 1.4mm. /min, 1.5mm/min, 1.6mm/min, 1.7mm/min, or a range consisting of any two values.
  • the first pulling speed V 1 is 1.4 to 1.6mm/min.
  • the crystal pulling speed is the second pulling speed V 2
  • the second pulling speed V 2 ranges from 1.6 to 2.2mm/min.
  • the value of the second pulling speed V 2 is 1.6 Any value among mm/min, 1.7mm/min, 1.8mm/min, 1.9mm/min, 2.0mm/min, 2.1mm/min, 2.2mm/min or a range of any two values, such as the second pulling speed
  • the range of V2 is 1.6 ⁇ 2.0mm/min or 1.6 ⁇ 1.8mm/min or 1.6 ⁇ 1.7mm/min.
  • the first pulling speed when 0 ⁇ H 1 ⁇ 0.5H 2 , the first pulling speed is lower than the second pulling speed, the first pulling speed is 1.4 ⁇ 1.6mm/min, and the second pulling speed is 1.6 ⁇ 1.7mm/min.
  • argon gas is introduced in the later stage of equal diameter, which increases the heat exchange effect and improves the quality of the ingot.
  • This application controls the amplitude and rate of crucible rotation, heating and cooling, and combines the flow rate, composition and feeding time of the gas. time, improving the quality of the crystal ingot.
  • the present application provides methods for reducing the oxygen content of single crystal silicon, including:
  • the crucible rotation speed is adjusted from the second crucible rotation to the third crucible rotation, and the temperature continues to decrease until the end.
  • the hydrogen-containing gas in this application may be a mixture of hydrogen and argon or a mixture of hydrogen and nitrogen.
  • the introduction ratio of hydrogen to argon or nitrogen ranges from 1:9 to 5:5.
  • the injection ratio of hydrogen to argon or nitrogen (volume ratio: v/v) ranges from 1:9, 2:9, 3:9, 4:9, 5:9, 1:5, 2:5, 3 :5, 4:5, 5:5 any value or a range of any two values.
  • the present application maintains the furnace pressure at 5 to 8 Torr during the process of material mixing, re-throwing, welding, seeding, shoulder expansion, shoulder rotation and equal diameter processes.
  • the furnace pressure is 5 Torr. , 6Torr, 7Torr, 8Torr, or a range of any two values.
  • the mixed gas of hydrogen and argon that is passed in can also be a mixed gas of hydrogen and nitrogen.
  • the embodiments of the present application further provide crystal rods prepared by the above-mentioned method.
  • the crystal rod products prepared by the method of the present application are of high quality and can prepare single silicon rods with longer lengths, thereby improving the yield and quality of the products.
  • Material melting and re-investment Place the silicon block into a quartz crucible, pass in argon gas with a flow rate of 100slpm, heat and melt to form a uniform silicon melt, control the temperature of the single crystal furnace to 1600 ⁇ 1650°C, and control the power of the heater At 180 ⁇ 185kW.
  • welding and seeding After the welding is completed, cool down and control the power in the seeding stage to be the first power P 1 .
  • the first power P 1 is maintained at 70kW.
  • the first crucible is turned during the seeding process.
  • the speed of the first crucible is 12r/min.
  • the second power P 2 is 50kW
  • the first power reduction W 1 is 20kW
  • the first cooling rate S in the shoulder expansion stage 1 W 1 /t 1 .
  • the mixed gas is composed of hydrogen and argon.
  • the volume ratio of hydrogen and argon is L 0 .
  • L 0 V hydrogen : V argon .
  • the rotation speed of the second crucible is 11 r/min.
  • the difference between the first crucible rotation and the second crucible rotation is R 1 r/min, and R 1 is 1 r/min.
  • Equal diameter During the equal diameter process, the crucible rotation speed is adjusted from the second crucible rotation 11r/min to the third crucible rotation 8r/min.
  • the difference between the second crucible rotation and the third crucible rotation is R 2 r/min.
  • R 2 is 3r/min;
  • the second power P 2 is reduced to the third power P 3 , the third power P 3 is 46kW, the reduction amplitude W 2 of the second power P 2 is 4kW, P 2
  • the second cooling rate S 2 to P 3 W 2 /(0.3H 2 /V 1 +0.1H 2 /V 2 );
  • Embodiments 2 to 4 The preparation method is the same as that of Embodiment 1, except that the rotation speed of the crucible is adjusted, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. The same below. The specific parameters are shown in Table 1. .
  • Embodiments 5 to 8 The preparation method is the same as in Embodiment 1, except that the heating power is adjusted, and the first cooling rate S 1 is adjusted according to the adjustment of W 1 , and the second cooling rate S 2 and S are adjusted according to the total length of the crystal rod. Heating rate S 3 , specific parameters are shown in Table 1.
  • Examples 9 to 11 The preparation method is the same as Example 1, except that the flow rate of the gas is adjusted, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. See Table 1 for details.
  • Examples 12-13 The preparation method is the same as Example 1, except that the ratio of the mixed gas is adjusted, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. See Table 1 for details.
  • Example 14 The preparation method is the same as Example 1, except that the proportion of the mixed gas and the flow rate of the gas are adjusted, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. See the table for details. 1.
  • Example 15 The preparation method is the same as Example 1, except that the pulling speed is adjusted, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. See Table 1 for details.
  • Example 16 The preparation method is the same as Example 1, except that the mixed gas is introduced throughout the equal diameter process, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. See Table 1 for details.
  • Example 17 The preparation method is the same as Example 1, except that the pulling speed is adjusted and the mixed gas is introduced throughout the equal diameter process, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. Details See Table 1.
  • Example 18 The preparation method is the same as Example 1, except that the first pulling speed and the second pulling speed are adjusted, and the second cooling rate S 2 and heating rate S 3 are adjusted according to the total length of the crystal rod. See Table 1 for details. .
  • Embodiment 19 The preparation method is the same as that of Embodiment 1. The difference is that the mixed gas is introduced into the chemical material, re-casting, welding, seeding, shoulder expansion, shoulder rotation and equal diameter stages, and the first step is adjusted according to the total length of the crystal ingot. 2. Cooling rate S 2 and heating rate S 3 .
  • Example 20 The preparation method is the same as Example 1, except that during the equal diameter process:
  • the second power P 2 is reduced to the third power P 3 , the third power P 2 is 46kW, the reduction amplitude W 2 of the second power P 2 is 4kW, P 2
  • the second cooling rate S 2 to P 3 W 2 /(0.4H 2 /V 1 );
  • Comparative Example 1 The preparation method is the same as Example 1, except that argon gas is introduced throughout the preparation step, and the second cooling rate S 2 and the heating rate S 3 are adjusted according to the total length of the crystal rod. See Table 1 for details.
  • Oxygen content measures the oxygen content of the ingot head.
  • test method please refer to GB/T 1557-2018.
  • Light attenuation test method The crystal rods prepared in Examples 1 to 20 and Comparative Example 1 were sampled and prepared into battery sheets. The light attenuation of the battery sheets was measured using battery illumination treatment. A hot spot durability test device was used for the battery illumination treatment. The battery performance parameters before and after illumination were measured using the German H.A.L.M high-precision I-V measurement system, and the FL-01 all-in-one machine from Zhonggui Optoelectronic Equipment Co., Ltd. was used to measure the photoluminescence (PL) of the silicon wafer and the electroluminescence (EL) of the battery.
  • PL photoluminescence
  • EL electroluminescence
  • this application can significantly reduce the oxygen content by controlling the speed of the crucible rotation.
  • this application does not introduce hydrogen during the preparation process of the crystal rod, the oxygen content will be higher.
  • this application can significantly reduce the oxygen content of the crystal rod and reduce the light decay rate of the crystal rod.

Abstract

本申请提供一种降低单晶硅氧含量的方法及晶棒。本申请的方法包括：在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入氢气；在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变在等径步骤中坩埚转速从第二埚转调整至第三埚转，并继续降低温度，直至收尾结束；在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中还需通入氩气。本申请能够通过氢还原法来降低晶棒中的氧含量，有利于单晶生长，减少不良品产生，提高晶棒产品质量。

Description

一种降低单晶硅氧含量的方法及晶棒
本申请要求于2022年04月29日提交中国专利局、申请号为202210467204.0、发明名称为“一种降低单晶硅氧含量的方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请属于太阳能直拉硅单晶制造、直拉半导体硅单晶制造技术领域，尤其是涉及一种降低单晶硅氧含量的方法及晶棒。
背景技术
直拉单晶硅中的关键产品特性包括氧含量、碳含量、少子寿命、电阻率、缺陷。其中，氧含量的来源是石英坩埚与硅原料反应产生SiO融入，在高温中，大部分的SiO由熔体自由表面挥发，而在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
技术问题
本申请提供一种降低单晶硅氧含量的方法及晶棒，有效的解决现有技术的问题。
技术解决方案
第一方面，本申请实施例提供了一种降低单晶硅氧含量的方法，包括：
在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入氢气；
在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；
在等径步骤中所述坩埚转速从所述第二埚转调整至第三埚转，并继续降低温度，直至收尾结束；
在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中还需通入氩气。
在一些实施例中，所述氢气与所述氩气的通入比例范围为1:9～5:5。
在一些实施例中，含有所述氢气与所述氩气形成的混合气流量范围为85～120slpm。
在一些实施例中，所述氢气与所述氩气的通入比例范围为1:9～2:5。
在一些实施例中，含有所述氢气与氩气形成的混合气流量范围为95～110slpm。
在一些实施例中，所述第一埚转的范围为9～14r/min。
在一些实施例中，所述第二埚的范围为7～12r/min。
在一些实施例中，所述第三埚转的范围为6～10r/min。
在一些实施例中，所述第二埚转低于所述第一埚转。
在一些实施例中，所述第三埚转低于所述第二埚转。
在一些实施例中，所述第二埚转与所述第一埚转的差速≤2r/min。
在一些实施例中，所述第二埚转与所述第三埚转的差速≥3r/min。
在一些实施例中，所述第三埚转范围为7～9r/min。
在一些实施例中，所述扩肩过程中降低加热器的第一功率所述第一功率的降幅范围为10～25kw。
在一些实施例中，所述扩肩过程中降低加热器的第一功率；所述第一功率的降幅范围为15～20kw。
在一些实施例中，所述等径过程中降低加热器的第二功率，所述第二功率的降幅范围为1～5kW。
在一些实施例中，在所述等径步骤中，所述继续降低温度后，还包括升温步骤，包括：
当0＜H1≤0.4H2，降低加热器的第二功率，所述第二功率的降幅为1～5kW；
当0.4H2＜H1≤H2，增加加热器的第三功率，所述第三功率的增幅为2～3kW；
其中，H1为拉晶长度，H2为目标晶棒总长度。
在一些实施例中，所述等径过程中，拉速范围为1.4～2.2mm/min。
在一些实施例中，所述等径过程中：
当0＜H1≤0.3H2，拉速范围为1.4～1.7mm/min；
当0.3H2＜H1≤H2，拉速范围为1.6～2.2mm/min；
其中，H1为拉晶长度，H2为目标晶棒总长度。
在一些实施例中，所述等径过程中，当0＜H1≤0.5H2，所述第一拉速低于所述第二拉速。
在一些实施例中，在所述扩肩、转肩和等径步骤中通入含有氢气与氩气的混合气。
在一些实施例中，所述等径过程中，当0.3H2＜H1≤H2，仅通入所述氩气。
在一些实施例中，所述引晶过程中采用第一埚转，在所述放肩和所述转肩过程中，将所述第一埚转调整为所述第二埚转。
相应地，本申请所述的降低单晶硅氧含量的方法，包括：
在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入含氢气体；
在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；
在等径步骤中所述坩埚转速从所述第二埚转调整至第三埚转，并继续降低温度，直至收尾结束。
第二方面，本申请实施例还提供了一种晶棒，所述晶棒由上述的制备方法制备得到。
有益效果
与现有技术相比，本申请提供了一种降低单晶硅氧含量的方法及晶棒。本申请的方法包括：在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入氢气；在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；在等径步骤中坩埚转速从第二埚转调整至第三埚转，并继续降低温度，直至收尾结束，在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中还需通入氩气。本申请在生产单晶硅时，氢气能够通过氢还原法来降低单晶中的氧含量，减少氧沉淀对单晶硅的机械强度破坏作用，有利于单晶生长，减少不良品产生，提高晶棒产品质量。
附图说明
图1为本申请实施例晶棒制备过程结构示意图；
图中，100～晶棒。
本发明的实施方式
本申请提供一种降低单晶硅氧含量的方法及晶棒，为使本申请的目的、技术方案及效果更加清楚、明确，以下通过实施例对本申请进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本申请，并不用于限定本申请。
现有技术中，晶棒中氧的主要来源是石英坩埚与硅原料反应产生SiO融入。在1400℃高温下，硅熔体和石英坩埚进行化学反应：
Si+SiO2→2SiO SiO→Si+O
在高温中，大部分的SiO由熔体自由表面挥发，而在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中；晶体表面或界面最大的缺陷就是含有大量的悬挂键，这些悬挂键可以形成表面态或界面态，从而引入复合中心，降低少数载流子的寿命。
需要说明的是，在氩气中拉制的单晶硅中氧含量可达1017～1018atoms/cm3，大部分以间隙状态溶解在晶体中，并形成非电活性的SiO2群体，硅中的氧含量是用红外吸收的方式进行测量，由于SiO2群Si—O键振动，在红外光波长为8.8μm(1135.90cm～1)处产生较强的吸收带。
单晶硅经400℃的热处理会出现电活性的热施主效应，热施主浓度与Si内间隙氧浓度的3次幂成正比，即n∝N3。热施主效应与单晶硅生长的历史和氧含量有密切关系。由于热施主效应的存在使得N型样品电阻率下降和P型样品电阻率增加，而这些性质的变化影响硅片径向电阻率的均匀度，对电子器件的生产有着重要的影响，实验经400～780℃温度的热处理，溶解氧的8.8μm吸收峰会随温度增加而减弱，用透射电镜可观察到直径为60nm左 右的沉淀物，其直径会随热处理温度的增加而变大，当温度超过870℃时，沉淀物直径为100～200nm；当温度达到930℃时，沉淀物直径为250nm；当温度上升至1000℃时，这些沉淀物呈片状，直径可达400nm；而温度高于1200℃以后，沉淀物会重新溶解，而氧沉淀会对单晶硅的机械强度有一定的破坏作用。
一种降低单晶硅氧含量的方法
本申请提供一种一种降低单晶硅氧含量的方法，包括：
在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入氢气；
在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；
在等径步骤中坩埚转速从第二埚转调整至第三埚转，并继续降低温度，直至收尾结束；
在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中在通入氢气的同时还通入氩气。
本申请在单晶炉通入惰性气体的位置通入氢气，通氢气的方式可以是随生产连续通气，也可以根据某些工序步骤间隔通气，其他工序不通气。本申请通过向单晶炉内加入氢气，通过氢还原反应将炉体中气液界面的含氧化合物还原变为水蒸气，能够大幅降低固液界面以及液体表面的氧含量，氢能和位错上的悬挂键结合，达到去除位错电活性的目的。单晶中的氧含量降低，还会进一步消除单晶光衰减，由于降低光衰减，能够制备长度更长的单根硅棒，提升产品的产量和品质。在生产单晶硅时，含氢气体能降低单晶硅的氧含量，尤其是对掺硼，镓，磷单晶的降氧效果更佳；硅中掺氢可以用来钝化杂质和缺陷的电活性，改善器件的性能；氢能和钴、铂、金、镍等深能级金属结合，去除或形成其它形式的深能级复合体，提高产品寿命。此外，本申请中改变埚转能够减弱熔体与石英坩埚的反应，尽可能的减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
氢气的含量越高，能够通过氢还原反应将炉体中气液界面的含氧化合物还原变为水蒸气而解决掉的氧含量越多，但是随着惰性氩气排出，能够促进熔硅高氧区的含氧化合物挥发，降低固液界面氧含量浓度来降低部分单晶硅氧含量，所以通入二者的混合气是一个较佳的选择，能够同时通过两方面来进行氧含量的降低。
在一些实施例中，在通入氩气的过程中同时通入氢气(氢气与氩气混合通入)，随着惰性氩气排出。或者是改变两种气体的通入顺序(例如：先通入氢气后在通入氩气)，来促进熔硅高氧区的含氧化合物挥发，降低固液界面氧含量浓度来降低单晶硅氧含量。
在一些实施例中，氢气与氩气的通入比例范围为1:9～5:5，氢气含量低于氩气含量；如氢气与氩气的通入比例(体积比：v/v)范围为1:9、2:9、3:9、4:9、5:9、1:5、2:5、3:5、4:5、 5:5中的任意值或者任意两值组成的范围。
在一些实施例中，氢气与氩气形成的混合气流量范围为85～120slpm，如85、90、95、100、105、110、115、120中的任意值或者任意两值组成的范围值。
在一些实施例中，氢气与氩气的通入比例范围为1:9～2:5。
在一些实施例中，氢气与氩气形成的混合气流量范围为95～110slpm，如95、100、105、110中的任意值或者任意两值组成的范围值。
在一些实施例中，第一埚转的范围为9～14r/min，相较于现有技术在引晶、扩肩、转肩步骤中的埚转相差较小，基本一致。如第一埚转为9、10、11、12、13、14中的任意值或者任意两值组成的范围。
在一些实施例中，第二埚转的范围为7～12r/min。如第二埚转为7、8、9、10、11、12中的任意值或者任意两值组成的范围。
在一些实施例中，第三埚转的范围为6～10r/min。如第三埚转为6、7、8、9、10中的任意值或者任意两值组成的范围。
在一些实施例中，第二埚转低于第一埚转。在现有技术中引晶、扩肩、转肩步骤中的埚转不进行改变，本申请改变埚转能够减弱熔体与石英坩埚的反应，尽可能的减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
在一些实施例中，第二埚转与第一埚转的差速R1≤2r/min。在一些实施例中，第二埚转和第一埚转的差速R1为0.5r/min、1r/min、1.5r/min或2r/min中的任意值或者任意两值组成的范围。本申请通过控制第二埚转和第一埚转之间的差速，进一步减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
在一些实施例中，第三埚转低于第二埚转。
在一些实施例中，第二埚转与第三埚转的差速R2≥3r/min，在一些实施例中，第二埚转与第三埚转的差速R2为3～5r/min。在一些实施例中，第二埚转和第三埚转的差速R2为3r/min、3.5r/min、4.0r/min 4.5r/min或5r/min中的任意值或者任意两值组成的范围。
本申请在等径阶段的坩埚转速略低，能够减弱熔体与石英坩埚的反应，尽可能的减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
在一些实施例中，第三埚转范围为7～9r/min。
本申请改变埚转能够减弱熔体与石英坩埚的反应，尽可能的减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。本申请在化料、复投、熔接阶段的坩埚转速为第一埚转，在引晶、扩肩、转肩阶段将坩埚转速调整为第二埚转，在等径步骤中将坩埚转速调整为第三埚转，本申请通过逐步降低坩埚转速并且控制埚转之间的差速，最大程度 上减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
在一些实施例中，引晶过程中采用第一埚转，在放肩和转肩过程中，将第一埚转调整为第二埚转。
在一些实施例中，扩肩过程中降低加热器的第一功率P1kW；第一功率降幅W1范围为10～25kW。
在一些实施例中，第一功率的降幅W1为15kW、16kW、17kW、18kW、19kW、20kW中的任意值或者任意两值组成的范围；如第一功率的降幅W1为15～20kW。
本申请在扩肩过程中通过降低加热器的功率，从而在拉制过程中进行降温，具体地，第一功率的降幅W1是指引晶结束后的第一功率P1kW与扩肩阶段的第二功率P2kW之间的差值，即W1＝P1～P2。
在一些实施例中，第一功率P1的范围为60～75kW。如P1的取值为60kW、65kW、70kW、75kW中的任意值或者任意两值组成的范围。
在一些实施例中，第二功率P2的范围为35～65kW，如P2的取值为35kW、40kW、45kW、50kW、55kW、60kW、65kW中的任意值或者任意两值组成的范围。
在一些实施例中，扩肩过程中的第一降温速率S1＝W1/t1，单位为kW/h，其中，W1为第一功率的降幅，单位为kW，t1为扩肩阶段持续时间，单位为h。
在一些实施例中，1≤t1≤3，如t1的取值为1、2、3中的任意值或者任意两值组成的范围。
在一些实施例中，在等径过程中继续降低温度，同样也是通过降低加热器的功率从而在拉制过程中进行降温，具体地，等径过程中加热器的功率从第二功率P2降低至第三功率P3，其中，第二功率的降幅W2范围为1～5kW，如第二功率的降幅W2为1kW、2kW、3kW、4kW或5kW中的任意值或者任意两值组成的范围。即W2＝P2～P3。
在一些实施例中，在等径步骤中降低温度后，还包括升温步骤：
当0＜H1≤0.4H2，降低加热器的第二功率P2kW，第二功率的降幅W2为1～5kW；
当0.4H2＜H1≤H2，增加加热器的第三功率P3kW至第四功率P4kW，第三功率的增幅W3为2～3kW；
其中，H1为拉晶长度，H2为目标晶棒总长度。
在一些实施例中，第二功率的降幅W2为1kW、2kW、3kW、4kW、5kW中的任意值或者任意两值组成的范围。具体地，W2＝P2～P3。
在一些实施例中，第三功率的增幅W3为2kW、2.5kW、3kW中的任意值或者任意两值的范围。W3＝P4-P3。
在一些实施例中，第三功率P3的范围为30～64kW，如P3的取值为30kW、35kW、40kW、 45kW、50kW、55kW、60kW、64kW中的任意值或者任意两值组成的范围。
在一些实施例中，P4的范围为32～67kW，如P2的取值为32kW、35kW、40kW、45kW、50kW、55kW、60kW、65kW、67kW中的任意值或者任意两值组成的范围。
在一些实施例中，3000mm≤H2≤4500mm。如H2的取值为3000mm、3500mm、4000mm、4500mm中的任意值或者任意两值组成的范围。如图1所示，拉晶过程中，晶棒长度(拉晶长度)为H1，不包括肩膀长度。
本申请同时通过调节坩埚的转速与加热器的功率，使转速变慢以及温度的降低，能够减弱熔体与石英坩埚的反应，尽可能地减少在固液界面前端扩散边界层的SiO分解后氧原子会由偏析现象进入晶棒中。
在一些实施例中，等径过程中，拉速范围为1.4～2.2mm/min。如1.4～2.0mm/min，1.6～1.8mm/min。在一些实施例中，拉速的取值为1.4mm/min、1.6mm/min、1.8mm/min、2.0mm/min、2.2mm/min中的任意值或者任意两值组成的范围。
在一些实施例中，等径过程中，拉晶长度为H1，目标晶棒总长度为H2；
当0＜H1≤0.3H2，拉晶的速度为第一拉速V1，第一拉速V1范围为1.4～1.7mm/min；如第一拉速V1的取值为1.4mm/min、1.5mm/min、1.6mm/min、1.7mm/min中的任意值或者任意两值组成的范围，例如第一拉速V1为1.4～1.6mm/min。
当0.3H2＜H1≤H2，拉晶的速度为第二拉速V2，第二拉速V2范围为1.6～2.2mm/min，如第二拉速V2的取值为1.6mm/min、1.7mm/min、1.8mm/min、1.9mm/min、2.0mm/min、2.1mm/min、2.2mm/min中的任意值或者任意两值组成的范围，如第二拉速V2范围为1.6～2.0mm/min或1.6～1.8mm/min或1.6～1.7mm/min。
在一些实施例中，等径过程中：
当0＜H1≤0.4H2，第二降温速率为S2，S2＝W2/(0.3H2/V1+0.1H2/V2)，其中，W2为第二功率的降幅，单位为kW，H2为目标晶棒总长，单位为mm，V1为第一拉速，单位为mm/min，V2为第二拉速，单位为mm/min。
当0.4H2＜H1≤H2，升温速率为S3，S3＝W3/(0.6H2/V2)，其中，W3为第三功率的增幅，单位为kW，H2为目标晶棒总长度，单位为mm，V2为第二拉速，单位为mm/min。
在一些实施例中，等径过程中，当0＜H1≤0.5H2，第一拉速低于第二拉速，第一拉速为1.4～1.6mm/min，第二拉速为1.6～1.7mm/min。
在一些实施例中，等径过程中，当0.3H2＜H1≤H2，仅通入氩气。本申请在等径阶段，通过在等径后期通入氩气，增加了换热效果，提升晶棒品质。
本申请通过控制埚转、升降温的幅度和速率，并且结合通入气体的流量、组成和通入时 间，提升了晶棒的品质。
在一些实施例中，本申请提供了降低单晶硅氧含量的方法，包括：
在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入含氢气体；
在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；
在等径步骤中坩埚转速从第二埚转调整至第三埚转，并继续降低温度，直至收尾结束。
本申请中的含氢气体可以是氢气与氩气的混合气或者是氢气和氮气的混合气。
在一些实施例中，氢气与氩气或氮气的通入比例范围为1:9～5:5。如氢气与氩气或氮气的通入比例(体积比：v/v)范围为1:9、2:9、3:9、4:9、5:9、1:5、2:5、3:5、4:5、5:5中的任意值或者任意两值组成的范围。
在一些实施例中，本申请在晶棒制备过程中，在化料、复投、熔接、引晶、扩肩、转肩以及等径过程中维持炉压为5～8Torr，如炉压为5Torr、6Torr、7Torr、8Torr中的任意值或者任意两值组成的范围。
在本申请的描述中，通入的氢气和氩气的混合气还可以是氢气和氮气的混合气。
晶棒
本申请的实施例进一步提供了上述的方法制备的晶棒，通过本申请方法制备的晶棒产品质量高，能够制备长度更长单根硅棒，提升产品的产量和品质。
实施例1
化料和复投：将硅块放置到石英坩埚中，通入氩气，流量为100slpm，加热融化形成均一的硅熔体，控制单晶炉的温度为1600～1650℃，加热器的功率控制在180～185kW。
熔接和引晶：熔接完成后，降温，控制引晶阶段的功率为第一功率P1，第一功率P1维持在70kW，引晶过程中为第一埚转，第一埚转的转速为12r/min。
扩肩：在2h(t1)内将第一功率P1降至第二功率P2，第二功率P2为50kW，第一功率的降幅W1为20kW，扩肩阶段第一降温速率S1＝W1/t1。将氩气更换为混合气，混合气由氢气和氩气组成，氢气和氩气的体积比为L0，L0＝V氢气：V氩气，维持气体流量不变；扩肩过程中埚转的转速为第二埚转，第二埚转的转速为11r/min，第一埚转和第二埚转的差值为R1r/min，R1为1r/min。
转肩：转肩过程中维持主加热器的功率为50kW，维持第二埚转转速不变。
等径：在等径过程中，坩埚转速从第二埚转11r/min调整至第三埚转8r/min，第二埚转和第三埚转之间的差值为R2r/min，R2为3r/min；
在拉晶长度0＜H1≤0.4H2阶段，将第二功率P2降低至第三功率P3，第三功率P3为46kW，第二功率P2的降幅W2为4kW，P2至P3的第二降温速率S2＝W2/(0.3H2/V1+0.1H2/V2)；
在拉晶长度0.4H2＜H1≤H2阶段，将第三功率P3提升至第四功率P4，第四功率P4为49kW，第三功率的增幅W3为3kW，P3至P4的升温速率S3＝W3/(0.6H2/V2)；
在拉晶长度0＜H1≤0.3H2阶段，拉速为第一拉速V1，V1＝1.5mm/min；
在拉晶长度0.3H2＜H1≤H2阶段，拉速为第二拉速V2，V2＝1.7mm/min；同时在该阶段，将混合气换为氩气，直至收尾结束。
实施例2～4：制备方法同实施例1，不同之处在于调整埚转转速，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，下同，具体参数详见表1。
实施例5～8：制备方法同实施例1，不同之处在于调整加热功率，并且根据W1的调整进而调整第一降温速率S1，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，具体参数详见表1。
实施例9～11：制备方法同实施例1，不同之处在于，调整气体通入的流量，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例12～13：制备方法同实施例1，不同之处在于，调整混合气的比例，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例14：制备方法同实施例1，不同之处在于，调整混合气的比例和气体通入的流量，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例15：制备方法同实施例1，不同之处在于，调整拉速，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例16：制备方法同实施例1，不同之处在于，等径过程中全程通入混合气，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例17：制备方法同实施例1，不同之处在于，调整拉速且等径过程中全程通入混合气，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例18：制备方法同实施例1，不同之处在于，调整第一拉速和第二拉速，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
实施例19：制备方法同实施例1，不同之处在于，化料、复投、熔接、引晶、扩肩、转肩以及等径阶段均通入混合气，并且根据晶棒总长度调整第二降温速率S2和升温速率S3。
实施例20：制备方法同实施例1，不同之处在于，等径过程中：
在拉晶长度0＜H1≤0.4H2阶段，将第二功率P2降低至第三功率P3，第三功率P2为46kW，第二功率P2的降幅W2为4kW，P2至P3的第二降温速率S2＝W2/(0.4H2/V1)；
在拉晶长度0.4H2＜H1≤H2阶段，将第三功率P3提升至第四功率P4，第四功率P4为49kW，第三功率的增幅W3为3kW，P3至P4升温速率S3＝W3/(0.1H2/V1+0.5H2/V2)；
控制拉速:在拉晶长度0＜H1≤0.5H2阶段，拉速为第一拉速V1，V1＝1.5mm/min；
在拉晶长度0.5H2＜H1≤H2，拉速为第二拉速V2，V2＝1.7mm/min。
对比例1：制备方法同实施例1，不同之处在于，制备步骤中全程通入氩气，并且根据晶棒总长度调整第二降温速率S2和升温速率S3，详见表1。
测试方法：
氧含量测量晶棒头氧含量，测试方法参见GB/T 1557-2018。
光衰减测试方法：将实施例1～20和对比例1制备的晶棒取样制备成电池片，采用电池光照处理测量电池片的光衰减，电池光照处理采用热斑耐久试验装置。光照前后的电池性能参数测量采用德国H.A.L.M高精度I-V测量系统，采用中导光电设备有限公司的FL-01一体机测量硅片的光致发光(PL)和电池的电致发光(EL)。
表1本申请实施例1～20以及对比例1的制备参数

表2本申请实施例1～20以及对比例1的制备的晶棒的性能测试结果
从本申请的结果可以看出，本申请通过控制埚转的速度，可以显著的降低氧含量。当本申请在晶棒制备过程中不通入氢气，则氧含量较高。本申请通过制备工艺的控制，可以显著降低晶棒的氧含量，并且降低晶棒的光衰速率。
以上对本申请实施例所提供的一种降低单晶硅氧含量的方法及晶棒备进行了详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想；同时，对于本领域的技术人员，依据本申请的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (19)

  1. 一种降低单晶硅氧含量的方法，其特征在于，包括：
    在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入氢气；
    在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；
    在等径步骤中所述坩埚转速从所述第二埚转调整至第三埚转，并继续降低温度，直至收尾结束；
    在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中还需通入氩气。
  2. 根据权利要求1所述的降低单晶硅氧含量的方法，其特征在于，所述氢气与所述氩气的通入比例范围为1:9～5:5；
    和/或，含有所述氢气与所述氩气的混合气流量范围为85～120slpm。
  3. 根据权利要求1～2任一项所述的降低单晶硅氧含量的方法，其特征在于，所述氢气与所述氩气的通入比例范围为1:9～2:5；
    和/或，含有所述氢气与所述氩气的混合气流量范围为95～110slpm。
  4. 根据权利要求1～3任一项所述的降低单晶硅氧含量的方法，其特征在于，所述第一埚转的范围为9～14r/min；
    和/或，所述第二埚转的范围为7～12r/min；
    和/或，所述第三埚转的范围为6～10r/min。
  5. 根据权利要求1～4任一项所述的降低单晶硅氧含量的方法，其特征在于，所述第二埚转低于所述第一埚转。
  6. 根据权利要求1～5任一项所述的降低单晶硅氧含量的方法，其特征在于，所述第三埚转低于所述第二埚转。
  7. 根据权利要求1～6任一项所述的降低单晶硅氧含量的方法，其特征在于，所述第二埚转与所述第一埚转的差速≤2r/min；
    和/或，所述第二埚转与所述第三埚转的差速≥3r/min。
  8. 根据权利要求1～7任一项所述的降低单晶硅氧含量的方法，其特征在于，所述第三埚转范围为7～9r/min。
  9. 根据权利要求1～8任一项所述的降低单晶硅氧含量的方法，其特征在于，所述扩肩过程中降低加热器的第一功率；所述第一功率的降幅范围为10～25kW；
    或者，所述扩肩过程中降低加热器的第一功率；所述第一功率的降幅范围为15～20kW。
  10. 根据权利要求1～9任一项所述的降低单晶硅氧含量的方法，其特征在于，所述等径过程中降低加热器的第二功率，所述第二功率的降幅范围为1～5kW。
  11. 根据权利要求1～10任一项所述的降低单晶硅氧含量的方法，其特征在于，在所述等径步骤中，所述继续降低温度后，还包括升温步骤，包括：
    当0＜H1≤0.4H2，降低加热器的第二功率，所述第二功率的降幅为1～5kW；
    当0.4H2＜H1≤H2，增加加热器的第三功率，所述第三功率的增幅为2～3kW；
    其中，H1为拉晶长度，H2为目标晶棒总长度。
  12. 根据权利要求1～11任一项所述的降低单晶硅氧含量的方法，其特征在于，所述等径过程中，拉速范围为1.4～2.2mm/min。
  13. 根据权利要求1～12任一项所述的降低单晶硅氧含量的方法，其特征在于，所述等径过程中：
    当0＜H1≤0.3H2，第一拉速范围为1.4～1.7mm/min；
    当0.3H2＜H1≤H2，第二拉速范围为1.6～2.2mm/min；
    其中，H1为拉晶长度，H2为目标晶棒总长度。
  14. 根据权利要求1～13任一项所述的降低单晶硅氧含量的方法，其特征在于，所述等径过程中，当0＜H1≤0.5H2，所述第一拉速低于所述第二拉速。
  15. 根据权利要求1～14任一项所述的降低单晶硅氧含量的方法，其特征在于，在所述扩肩、转肩和等径步骤中通入含有氢气与氩气的混合气。
  16. 根据权利要求1～15任一项所述的降低单晶硅氧含量的方法，其特征在于，所述等径过程中，当0.3H2＜H1≤H2，仅通入所述氩气。
  17. 根据权利要求1～16任一项所述的降低单晶硅氧含量的方法，其特征在于，所述引晶过程中采用所述第一埚转，在所述放肩和所述转肩过程中，将所述第一埚转调整为所述第二埚转。
  18. 一种降低单晶硅氧含量的方法，其特征在于，包括：
    在化料、复投、熔接、引晶、扩肩、转肩以及等径的任意一个或几个步骤中通入含氢气体；
    在引晶、扩肩、转肩的过程中将坩埚转速从第一埚转调整至第二埚转，并在扩肩过程中降低温度，在转肩过程中保持该温度不变；
    在等径步骤中所述坩埚转速从所述第二埚转调整至第三埚转，并继续降低温度，直至收尾结束。
  19. 一种晶棒，其特征在于，所述晶棒由如权利要求1～17任一项所述的方法，或，如权 利要求18所述的方法制备得到。
PCT/CN2023/091407 2022-04-29 2023-04-27 一种降低单晶硅氧含量的方法及晶棒 WO2023208156A1 (zh)

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