Method for preparing single crystal silicon rod by Czochralski method and single crystal silicon rod

Abstract

The method for preparing the single crystal silicon rod through the Czochralski method comprises the steps that a silicon element and an antimony element are added into a furnace where a previous single crystal silicon rod is machined, the feeding mass of the antimony element is M1Sb = M2Sb + (t2 + 12) * bSb-M3Sb, M2Sb is the mass of the antimony element needed by the single crystal silicon rod to be prepared, and the unit is g; m3Sb is the mass of the residual antimony element in the furnace, and the unit is g; b Sb is the charging volatilization coefficient of the antimony element, and b Sb is 0.1 h / g to 15 h / g; t2 is the interval time between T3 and T4, and the unit is h; wherein T3 is the time for pulling out the broken line of the previous single crystal silicon rod, and T4 is the time for pulling out the charging barrel after the charging of the last barrel of silicon material is completed. The introduction of the charging volatilization coefficient is beneficial to avoiding the resistivity difference between different furnace stages or different silicon single crystal rods on the same furnace stage, and is beneficial to improving the process stability.

Description

Technical Field

[0001] The invention relates to the technical field of solar photovoltaic technology, and in particular to a method for preparing a single crystal silicon rod by a Czochralski method and a single crystal silicon rod. Background Art

[0002] Under the goal of carbon peak and carbon neutrality, new energy, especially solar power generation, has developed rapidly. The installed capacity of photovoltaic power generation is expected to reach 450GW in 2023. Monocrystalline silicon is the preferred material for photovoltaics due to its excellent performance and high conversion efficiency. The production capacity of monocrystalline silicon is expected to reach 800GW.

[0003] Monocrystalline silicon used for solar power generation is divided into P-type and N-type. Common dopants for P-type are boron and gallium. Boron-doped monocrystalline silicon has a large light decay due to the effect of boron-oxygen complexes. The full name is light-induced degradation (LID), and the decay in the first year is about 2%. In order to reduce the impact of attenuation, it is necessary to use technologies such as electrical injection and light injection, which increases the cost significantly and cannot be completely eliminated. After 2020, P-type monocrystalline silicon for solar power generation will gradually turn to gallium-doping. The segregation coefficient of gallium in silicon is 0.008, and the amount that can enter monocrystalline silicon is very small. Therefore, more dopants are needed to pull the same weight of monocrystalline silicon. The resistance range of gallium-doped single crystals suitable for solar cells is 0.4-1.1. The proportion of a complete crystal rod that meets the requirements is only about 60%, and the yield is extremely low, which also leads to an increase in the manufacturing cost of monocrystalline silicon.

[0004] The cell structures used for N-type monocrystalline silicon for solar energy include TOPcon, HJT, and IBC. N-type monocrystalline silicon has obvious advantages in conversion efficiency due to its higher minority carrier lifetime, and there is no attenuation caused by boron-oxygen complexes, so it has gradually become the mainstream of crystalline silicon cells. At present, the dopant used for N-type monocrystalline silicon is phosphorus silicon alloy, which needs to be produced by direct pulling to produce single crystal silicon with high phosphorus concentration. The production cost is high, and the distribution of resistivity of phosphorus-doped single crystal silicon has a deviation of 6-7 times from head to tail, and the adaptability of the battery is poor.

[0005] Patent CN202010723937.7 discloses a method for controlling the resistivity of an n-type single crystal. It uses the difference in the segregation coefficient of phosphorus gallium to increase the resistivity of the tail of the n-type single crystal, narrowing and compressing the resistivity range to the required state. At the same time, the method adds dopants such as gallium and phosphorus silicon alloy at one time, without causing crystal growth disturbances or destroying crystal growth. However, the overall resistivity of the single crystal silicon rod prepared by it is distributed between 1 and 2Ω·cm, and the resistivity deviation between the head and the tail is still large. The yield of the silicon wafer prepared by it is still low when used in battery preparation.

[0006] In view of this, a method for preparing a single crystal silicon rod with a small head-tail resistivity deviation is particularly necessary. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing a single crystal silicon rod by a Czochralski method and a single crystal silicon rod, which are beneficial to reducing the resistivity deviation between the head and tail of the single crystal silicon rod.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a method for preparing a single crystal silicon rod by a Czochralski method, comprising:

[0010] Add silicon and antimony elements to the furnace after the previous single crystal silicon rod is processed.

[0011] The added mass of antimony element is M 1Sb =M 2Sb +(t2+12)×b Sb -M 3Sb , where M 2Sb M is the mass of antimony element required to prepare the single crystal silicon rod, in g; 3Sb is the mass of the remaining antimony element in the furnace, in g; b Sb is the volatility coefficient of antimony element, b Sb It is 0.1h / g~15h / g; t2 is the interval time between T3 and T4, in h; T3 is the time when the previous single crystal silicon rod is removed after the wire is broken, and T4 is the time when the barrel is removed after the last barrel of silicon material is added.

[0012] In an optional embodiment, the M 2Sb It is calculated based on the resistivity of the single crystal silicon rod to be prepared, 3Sb Calculated based on the resistivity of the tail of the previous single crystal silicon rod.

[0013] In an optional embodiment, the antimony element is added into the furnace 1 min to 60 min before the seed crystal is melted.

[0014] In an optional embodiment, when the crystal pulling wire breaks, the furnace is temperature-adjusted and released 1 to 3 times to compensate for the doped antimony element. The mass of the compensatory doped antimony element each time is M0 = (t1+5)×a, wherein a is the temperature adjustment volatility coefficient of the antimony element, and a is 0.1h / g to 15h / g; t1 is the interval time between T1 and T2, in units of h; wherein T1 is the start time of welding, and T2 is the time when the crystal pulling wire breaks.

[0015] In an optional embodiment, the compensatory doping of antimony element is performed by using a supplementary doping device, the supplementary doping device comprises a sleeve and a push rod capable of moving along the inner cavity of the sleeve, one end of the push rod passes through the sleeve and is provided with a hopper;

[0016] The sleeve is provided with a guide groove, which includes a push-pull groove arranged along the axial direction of the push rod and a steering groove arranged along the circumference of the push rod. A sliding block capable of sliding along the guide groove is fixed to one side of the push rod located in the sleeve.

[0017] In an optional embodiment, in the temperature-adjusting welding step, the furnace pressure is 1 torr to 100 torr, preferably 7 torr to 25 torr.

[0018] In an optional embodiment, in the seeding step, the argon flow rate is 60 slpm to 200 slpm, the furnace pressure is 1 torr to 100 torr, and the crucible speed is 3.5 r / min to 5 r / min;

[0019] Preferably, the argon flow rate is 80slpm to 120slpm, the furnace pressure is 2torr to 10torr, and the crucible speed is 3.5r / min to 5r / min;

[0020] In an optional embodiment, in the shoulder release step, the argon flow rate is 60 slpm to 200 slpm, the furnace pressure is 1 torr to 100 torr, and the crucible speed is 1 r / min to 10 r / min;

[0021] Preferably, the argon flow rate is 80 slpm to 120 slpm, the furnace pressure is 2 torr to 10 torr, and the crucible rotation speed is 5 r / min to 9 r / min.

[0022] In an optional embodiment, the equalizing step includes an early equalizing stage, a middle equalizing stage, and a late equalizing stage;

[0023] In the early stage of equal diameter, the argon flow rate is 60slpm~200slpm, the furnace pressure is 3torr~20torr, and the crucible speed is 5r / min~9r / min;

[0024] In the middle stage of equal diameter, after the crystal is pulled to 500mm, adjust the argon flow rate to 60slpm~90slpm, the furnace pressure to 10torr~15torr, and the crucible speed to 1r / min~7r / min;

[0025] In the later stage of equal diameter, after the crystal is pulled to 1000mm, the argon flow rate is adjusted to 80slpm, the furnace pressure is 12torr, and the crucible speed is 5r / min.

[0026] In a second aspect, the present invention provides a single crystal silicon rod prepared by the method of any one of the aforementioned embodiments, wherein the resistivity is 0.2 Ω.cm to 28 Ω.cm; and / or the antimony doping concentration is 2.3×10 16 atoms / cm 3 ~1.17×10 14 atoms / cm 3; and / or, the resistivity difference between the head and tail of the single single crystal silicon rod is less than 0.02Ω.cm.

[0027] The present invention has the following beneficial effects:

[0028] Compared with phosphorus doping, antimony doping in the single crystal silicon rod in the present application is more conducive to reducing the resistivity deviation between the head and tail of the single crystal silicon rod. Since antimony is extremely volatile, on the one hand, the controllability of antimony doping in the preparation process is relatively low. On the other hand, antimony will also volatilize between the time when the previous single crystal silicon rod is broken and the time when the last bucket of silicon material is added, resulting in a low antimony content in the material in the furnace. Therefore, in the present application, when determining the charging quality of the antimony element, the charging volatilization coefficient of the antimony element is introduced. The charging volatilization coefficient is an empirical coefficient. Its introduction is conducive to avoiding the resistivity difference between different furnaces or different single crystal silicon rods on the same furnace, and is conducive to improving the process stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram of the structure of the supplementary doping device from one perspective;

[0031] Figure 2 This is a schematic structural diagram of the supplementary doping device from another perspective.

[0032] Illustration: 100-sleeve; 200-push rod; 300-hopper; 410-push-pull groove; 420-turning groove; 700-slider. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0034] The embodiment of the present invention provides a method for preparing a single crystal silicon rod by a Czochralski method, comprising:

[0035] Add silicon and antimony elements to the furnace after the previous single crystal silicon rod is processed.

[0036] The added mass of antimony element is M 1Sb =M 2Sb+(t2+12)×b Sb -M 3Sb , where M 2Sb M is the mass of antimony element required to prepare the single crystal silicon rod, in g; 3Sb is the mass of the remaining antimony element in the furnace, in g; b Sb is the volatility coefficient of antimony element, b Sb It is 0.1h / g~15h / g; t2 is the interval time between T3 and T4, in h; T3 is the time when the previous single crystal silicon rod is removed after the wire is broken, and T4 is the time when the barrel is removed after the last barrel of silicon material is added.

[0037] The monocrystalline silicon rod in the embodiment of the present application is doped with antimony. Since antimony is very volatile, on the one hand, the controllability of antimony doping in the preparation process is relatively low. On the other hand, the time between the last monocrystalline silicon rod being broken and the last bucket of silicon material being added is accompanied by the volatilization of antimony, resulting in a low antimony content in the furnace material. Therefore, in the present application, when determining the quality of the antimony element, the addition volatility coefficient of the antimony element is introduced. The addition volatility coefficient is an empirical coefficient. In some embodiments, the addition volatility coefficient of the antimony element b Sb It can be 0.1h / g to 15h / g, specifically 0.1h / g, 0.3h / g, 0.5h / g, 1h / g, 3h / g, 5h / g, 7h / g, 9h / g, 11h / g, 13h / g, 15h / g. Generally, the volatilization coefficient of the feed is closely related to the temperature in the furnace between T3 and T4. The higher the temperature in the furnace during this period, the higher the volatilization coefficient of the feed. Sb The value of will be larger.

[0038] Compared with phosphorus doping, antimony is doped in the single crystal silicon rod in the present application, which is more conducive to reducing the resistivity deviation between the head and tail of the single crystal silicon rod. Further adding antimony in the above manner is conducive to avoiding the resistivity difference between different furnaces or different single crystal silicon rods in the same furnace, and is conducive to improving the process stability. At the same time, compared with the prior art that utilizes the difference in phosphorus gallium segregation coefficient, the resistivity of the tail of the n-type single crystal is increased, and the resistivity range is narrowed and compressed to the required state. The resistivity difference between the head and tail of the single crystal silicon rod obtained by the method of the present application can be controlled within 0.02Ω.cm. Compared with co-doping with gallium and phosphorus, the resistivity distribution of the single crystal silicon rod is narrower, which is more conducive to improving the yield of the battery prepared thereby.

[0039] In an optional embodiment, the M 2Sb It is calculated based on the resistivity of the single crystal silicon rod to be prepared, 3Sb Calculated based on the resistivity of the tail of the previous single crystal silicon rod.

[0040] Specifically, M 2Sb and M 3SbThe calculation of can refer to GB / T 13389-92; because phosphorus and antimony belong to the same family, the outermost structure of atoms in the same family is the same, and a free electron is formed during the doping process, and the electrical properties are the same. Therefore, the resistivity calculation can be calculated according to the phosphorus alloy concentration, but the atomic mass is different, resulting in different doping concentrations. Specifically, M 2Sb and M 3Sb The calculation of can refer to the resistivity of phosphorus alloys, just replace the atomic mass of phosphorus with the atomic mass of antimony.

[0041] In an optional embodiment, the antimony element is added into the furnace 1 min to 60 min before the seed crystal is melted.

[0042] Since antimony is easily volatile, it is not added together with silicon, but added to the furnace 1 minute to 60 minutes before the seed crystal is melted to ensure that the added material can be melted while reducing volatilization.

[0043] In an optional embodiment, when the crystal pulling wire breaks, the furnace is temperature-adjusted and released 1 to 3 times to compensate for the doped antimony element. The mass of the compensatory doped antimony element each time is M0 = (t1+5)×a, wherein a is the temperature adjustment volatility coefficient of the antimony element, and a is 0.1h / g to 15h / g; t1 is the interval time between T1 and T2, in units of h; wherein T1 is the start time of welding, and T2 is the time when the crystal pulling wire breaks.

[0044] Due to the influence of inaccurate furnace power, crucible position, pulling speed or impurity factors, crystal pulling wire breakage is inevitable. When the crystal pulling wire breakage occurs, it will affect the preparation process of the single crystal silicon rod, and the volatilization of the antimony element will increase, which may cause the doping concentration of antimony in different furnaces or different single crystal silicon rods in the same furnace to deviate, so it is necessary to compensate for the doped antimony element. In this application, when compensating for the doped antimony element, the temperature adjustment volatility coefficient of the antimony element is introduced. The temperature adjustment volatility coefficient is an empirical coefficient. In some embodiments, the temperature adjustment volatility coefficient a of the antimony element can be 0.1h / g~15h / g, specifically 0.1h / g, 0.3h / g, 0.5h / g, 1h / g, 3h / g, 5h / g, 7h / g, 9h / g, 11h / g, 13h / g, 15h / g. Generally, the temperature adjustment volatility coefficient is closely related to the furnace temperature between T1 and T2. The higher the furnace temperature during this time period, the greater the value of a.

[0045] In an optional embodiment, the compensatory doping of antimony element is performed using a doping device, such as Figure 1 and Figure 2 As shown, the supplementary doping device comprises a sleeve 100 and a push rod 200 that can move along the inner cavity of the sleeve 100, and one end of the push rod 200 passes through the sleeve 100 and is provided with a hopper 300;

[0046] The sleeve 100 is provided with a guide groove, which includes a push-pull groove 410 arranged along the axial direction of the push rod 200 and a steering groove 420 arranged along the circumference of the push rod 200. A slider 700 that can slide along the guide groove is fixed to one side of the push rod 200 located in the sleeve 100.

[0047] When the supplementary doping device in the present application is used for supplementary doping, the material to be supplemented is added into the hopper 300, and the slider 700 is pushed to move along the push-pull groove 410 to withdraw the push rod 200 from the sleeve 100, and the hopper 300 then reaches the position above the single crystal furnace; then the slider 700 is pushed to rotate along the turning groove 420, and the push rod 200 rotates along the axis of the push rod 200 driven by the push block, thereby driving the hopper 300 to flip, and the material in the hopper 300 is poured into the single crystal furnace, and then the slider 700 moves along the turning groove 420 and the push-pull groove 410 in turn, returns to the initial position, and completes the compensatory doping of antimony elements.

[0048] In an optional embodiment, in the temperature adjustment welding step, the furnace pressure is 1 torr to 100 torr, such as 1 torr, 5 torr, 7 torr, 10 torr, 15 torr, 20 torr, 25 torr, 30 torr, 41 torr, 51 torr, 61 torr, 71 torr, 81 torr, 91 torr, 100 torr; preferably 7 torr to 25 torr.

[0049] In the temperature-controlled welding step, the volatilization of antimony is affected by time, temperature and furnace pressure. Properly increasing the furnace pressure is beneficial to reducing the volatilization of antimony, shortening the difference in the amount of antimony volatilization in different furnaces, and ensuring the consistency of the resistivity of different single crystal silicon rods.

[0050] In an optional embodiment, in the seeding step, the argon flow rate is 60 slpm to 200 slpm, such as 60 slpm, 80 slpm, 90 slpm, 100 slpm, 110 slpm, 120 slpm, 140 slpm, 160 slpm, 180 slpm, 200 slpm; the furnace pressure is 1 torr to 100 torr, such as 1 torr, 2 torr, 3 torr, 4 torr, 5 torr, 6 torr, 7 torr, 8 torr, 9 torr, 10 torr, 11 torr, 21 torr, 31 torr, 41 torr, 51 torr, 61 torr, 71 torr, 81 torr, 91 torr, 100 torr; the crucible rotation is 3.5 r / min to 5 r / min, such as 3.5 r / min, 4 r / min, 4.5 r / min, 5 r / min;

[0051] Preferably, the argon flow rate is 80 slpm to 120 slpm, the furnace pressure is 2 torr to 10 torr, and the crucible rotation speed is 3.5 r / min to 5 r / min.

[0052] Properly increasing the argon flow rate and reducing the furnace pressure can accelerate the volatilization of antimony elements, which is beneficial to increasing the resistivity of the crystal rod head, thereby reducing the difference in resistivity between the head and tail of the single crystal silicon rod; in addition, a lower furnace pressure is beneficial to the escape of oxygen in the silicon liquid, thereby helping to reduce the oxygen content in the single crystal silicon rod.

[0053] In an optional embodiment, in the shoulder release step, the argon flow rate is 60 slpm to 200 slpm, such as 60 slpm, 80 slpm, 90 slpm, 100 slpm, 110 slpm, 120 slpm, 140 slpm, 160 slpm, 180 slpm, 200 slpm; the furnace pressure is 1 torr to 100 torr, such as 1 torr, 2 torr, 3 torr, 4 torr, 5 torr, 6 torr, 7 torr, 8 torr, 9 torr, 10 torr, 110 torr, 120 torr, 140 torr, 160 torr, 180 torr, 200 torr, torr, 8torr, 9torr, 10torr, 11torr, 21torr, 31torr, 41torr, 51torr, 61torr, 71torr, 81torr, 91torr r, 100torr; crucible rotation 1r / min~10r / min, such as 1r / min, 3r / min, 5r / min, 6r / min, 7r / min, 8r / min, 9r / min, 10r / min;

[0054] Preferably, the argon flow rate is 80 slpm to 120 slpm, the furnace pressure is 2 torr to 10 torr, and the crucible rotation speed is 5 r / min to 9 r / min.

[0055] Properly increasing the argon flow rate and reducing the furnace pressure can accelerate the volatilization of antimony elements, which is beneficial to increasing the resistivity of the crystal rod head, thereby reducing the difference in resistivity between the head and tail of the single crystal silicon rod; in addition, a lower furnace pressure is conducive to the escape of oxygen in the silicon liquid, thereby reducing the oxygen content in the single crystal silicon rod. At the same time, the shoulder release step has an increased crucible rotation compared to the seeding step, which is beneficial to ensure crystallization and improve the controllability of oxygen content.

[0056] In an optional embodiment, the equalizing step includes an early equalizing stage, a middle equalizing stage, and a late equalizing stage;

[0057] In the early stage of equal diameter, the argon flow rate is 60slpm to 200slpm, such as 60slpm, 80slpm, 90slpm, 100slpm, 110slpm, 120slpm, 140slpm, 160slpm, 180slpm, 200slpm; the furnace pressure is 3torr to 20torr, such as 3torr, 5torr, 10torr, 15torr, 20torr; the crucible speed is 5r / min to 9r / min, such as 5r / min, 6r / min, 7r / min, 8r / min, 9r / min;

[0058] In the middle stage of equal diameter, after the crystal is pulled to 500mm, adjust the argon flow rate to 60slpm~90slpm, the furnace pressure to 10torr~15torr, and the crucible speed to 1r / min~7r / min;

[0059] In the later stage of equal diameter, after the crystal is pulled to 1000mm (usually not more than 4000mm), adjust the argon flow rate to 80slpm, the furnace pressure to 12torr, and the crucible speed to 5r / min.

[0060] The parameters of the equal diameter step are within the above range, which is conducive to ensuring crystallization. In some embodiments, the argon flow rate, furnace pressure and crucible rotation in the middle stage of equal diameter are all slowly changed from the corresponding parameters of the early stage of equal diameter to the late stage of equal diameter, and the furnace pressure in the early stage of equal diameter is lower than that in the late stage of equal diameter, and the argon flow rate in the early stage of equal diameter is greater than that in the late stage of equal diameter, so as to suppress the volatilization of antimony elements in the late stage of equal diameter, which is conducive to reducing the difference in resistivity between the head and tail of the single crystal silicon rod, and reducing the volatilization of oxygen content; the crucible rotation in the early stage of equal diameter is greater than that in the late stage of equal diameter, which is conducive to improving the controllability of oxygen content.

[0061] In a second aspect, the present invention provides a single crystal silicon rod prepared by the method of any one of the aforementioned embodiments, wherein the resistivity is 0.2 Ω.cm to 28 Ω.cm; and / or the antimony doping concentration is 2.3×10 16 atoms / cm 3 ~1.17×10 14 atoms / cm 3 ; and / or, the resistivity difference between the head and tail of the single single crystal silicon rod is less than 0.02Ω.cm.

[0062] The resistivity difference between the head and tail of the single crystal silicon rod prepared by the method of the present invention can be maintained within 0.02Ω.cm, and the resistivity difference of the whole furnace of single crystal silicon rods can be maintained within 2 times. The single crystal silicon rods are prepared into silicon wafers, and TOPcon cells and modules made from the silicon wafers have a cell and module efficiency that is 0.05% higher than that of TOPcon cells and modules produced using conventional phosphorus-doped silicon wafers.

[0063] The resistivity of the single crystal silicon rod in the present invention is 0.2 Ω.cm to 28 Ω.cm, specifically 0.2 Ω.cm, 0.5 Ω.cm, 1 Ω.cm, 2 Ω.cm, 5 Ω.cm, 10 Ω.cm, 15 Ω.cm, 20 Ω.cm, 25 Ω.cm, 28 Ω.cm; the antimony doping concentration of the single crystal silicon rod in the present invention is 2.3×10 16 atoms / cm 3 ~1.17×10 14 atoms / cm 3 , specifically 2.3×10 16 atoms / cm 3 , 2×10 16 atoms / cm 3 , 1×10 16 atoms / cm 3 , 5×10 15 atoms / cm 3 , 2×10 15 atoms / cm 3 , 1×10 15 atoms / cm 3 , 5×10 14 atoms / cm 3 , 2×10 14 atoms / cm 3 , 1.17×10 14 atoms / cm 3 The resistivity of the single crystal silicon rod is within this range, which is beneficial to improving the efficiency of the battery using the single crystal silicon rod.

[0064] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0065] Example 1

[0066] A method for preparing a single crystal silicon rod by a Czochralski method (36-inch thermal field), comprising: the resistivity of the single crystal silicon rod to be prepared is 1.0 Ω.cm, the antimony doping concentration is 2.3*10 16 atoms / cm 3 , specifically including the following steps:

[0067] 1. After the production is finished, the material is reported. After the processing of the last single crystal silicon rod is completed, there are 360Kg of melt left in the furnace. Add another 600kg of silicon material into the furnace. The last single crystal silicon rod is cut off at 12:00.

[0068] 2. Prepare materials and receive reports from on-site personnel, load the materials, and send them to the site after loading is completed.

[0069] 3. During normal production, silicon material is added to the furnace. After the last barrel is taken out, the preparation of materials for calculating antimony alloy is notified. The time is 16:24.

[0070] 4. Prepare the materials by calculating the total weight of antimony alloy M2=15g and the weight of the remaining antimony alloy M3=5g using the following national standard formula. The weight of the antimony alloy to be added is M2+(T3-T4+12)*b-M3=15+(16:24-12:00+12)*0.15-5=15+(4.4+12)*0.15-5=12.46g.

[0071] M=(W·CT·A) / (d·K0·N0)

[0072] Where: W—weight of polysilicon, g.

[0073] d—Specific gravity of silicon, 2.33 g / cm 3 .

[0074] CT—impurity concentration corresponding to the target resistivity of the single crystal head, atom / cm 3 .

[0075] M—weight of doping element, g.

[0076] A—Atomic weight of the doping element.

[0077] N0—Avogadro constant, 6.023*10 23 .

[0078] 5. Send the calculated antimony alloy to the production line. Add the antimony alloy into the supplementary doping device 2 minutes before the seed crystal melting temperature adjustment, and use the supplementary doping device to complete the alloy doping.

[0079] 6. When production starts, the temperature is adjusted, the furnace pressure is controlled at 15 torr, the argon flow rate is 80 slpm, and the crucible speed is 5 r / min.

[0080] 7. After the crystal seeding starts, the furnace pressure is controlled at 5 torr, the argon flow rate is 100 slpm, and the crucible speed is 5 r / min.

[0081] 8. After shoulder release begins, the furnace pressure is controlled at 5 torr, the argon flow rate is 100 slpm, and the crucible speed is 7 r / min.

[0082] 9. In the early stage of equal diameter (0-500), the furnace pressure is controlled at 5 torr, the argon flow rate is 100 slpm, and the crucible speed is 7 r / min.

[0083] 10. In the middle stage of equal diameter (500-1000), the furnace pressure is controlled at 5-12 torr, the argon flow rate is 100-80 slpm, and the crucible speed is 7-5 r / min. The furnace pressure, argon and crucible speed gradually change from the early stage of equal diameter to the corresponding parameters in the late stage of equal diameter.

[0084] 11. In the later stage of equal diameter (>1000), the furnace pressure is 12torr, the argon flow rate is 80slpm, and the crucible speed is 5r / min.

[0085] 12. After the equal diameter is completed, finishing is performed to produce single crystal silicon rod A and finishing is performed, and the above steps 1-11 are repeated to continue producing antimony-doped single crystal silicon rods.

[0086] 13. If equal diameter wire breakage occurs when preparing single crystal silicon rods, perform the following operations.

[0087] 14. To produce equal-diameter wire breaks, click on the wire break proposal and notify the material preparation department to add antimony alloy. The wire break time is 13:00.

[0088] 15. After receiving the report from the site, we checked the start time of the last welding and found that the remaining material was 906 kg at 1:00. The weight of antimony alloy to be added was calculated by the formula: M0 = (T1-T2+5)*a = (12+5)*0.2 = 3.4 g.

[0089] 16. Send the calculated antimony alloy to production and repeat the above steps 1-11.

[0090] 17. After the equal diameter is completed, finishing is performed to produce the single crystal silicon rod B and finishing is performed, and the above steps 1-11 are repeated to continue the production of antimony-doped single crystal silicon rods.

[0091] Comparative Example 1

[0092] A method for preparing single crystal silicon rods by Czochralski method (36-inch hot field), which is different from Example 1 only in that the volatility coefficient b of the added antimony element in step 4 is 0, and M0=0 in step 15.

[0093] Comparative Example 2

[0094] A method for preparing a single crystal silicon rod by Czochralski method (36-inch hot field), which differs from Example 1 only in that the parameters of steps 6-11 are different:

[0095] 6. When production starts, the temperature is adjusted, the furnace pressure is controlled at 6 torr, the argon flow rate is 80 slpm, and the crucible speed is 5 r / min.

[0096] 7. After the seeding starts, the furnace pressure is controlled at 20 torr, the argon flow rate is 70 slpm, and the crucible speed is 5 r / min.

[0097] 8. After shoulder release begins, the furnace pressure is controlled at 20 torr, the argon flow rate is 70 slpm, and the crucible speed is 4 r / min.

[0098] 9. Constant diameter, furnace pressure controlled at 5 torr, argon flow rate 100 slpm, crucible speed 7 r / min.

[0099] Comparative Example 3

[0100] A method for preparing phosphorus single crystal silicon rods by Czochralski method (36-inch hot field), which differs from Example 1 in that the antimony element is replaced by the phosphorus element and the volatility coefficient b of the added material is 0.

[0101] Example 2

[0102] This embodiment provides a method for preparing a single crystal silicon rod by a Czochralski method (36-inch thermal field). The difference from the embodiment 1 is that the antimony doping concentration in the single crystal silicon rod to be prepared is preset to 1.17*10 14 atoms / cm 3 .

[0103] Example 3

[0104] This embodiment provides a method for preparing single crystal silicon rods by the Czochralski method (36-inch hot field), which is different from Embodiment 1 only in that the volatility coefficient of the added antimony element is 0.1h / g, and the temperature-adjusted volatility coefficient of the antimony element is 15h / g.

[0105] Example 4

[0106] This embodiment provides a method for preparing single crystal silicon rods by the Czochralski method (36-inch hot field), which is different from Embodiment 1 only in that the volatility coefficient of the added antimony element is 15h / g and the temperature-adjusted volatility coefficient of the antimony element is 0.1h / g.

[0107] Example 5

[0108] This embodiment provides a method for preparing a single crystal silicon rod by a Czochralski method (36-inch hot field), which is different from Embodiment 1 only in that the parameters of steps 6-11 are different:

[0109] 6. Production starts with temperature adjustment, furnace pressure is controlled at 7 torr, argon flow rate is 120 slpm, and crucible speed is 5 r / min.

[0110] 7. After the crystal seeding starts, the furnace pressure is controlled at 2 torr, the argon flow rate is 100 slpm, and the crucible speed is 5 r / min.

[0111] 8. After shoulder release begins, the furnace pressure is controlled at 2 torr, the argon flow rate is 120 slpm, and the crucible speed is 5 r / min.

[0112] 9. In the early stage of equal diameter (0-500), the furnace pressure is controlled at 20 torr, the argon flow rate is 200 slpm, and the crucible speed is 5 r / min.

[0113] 10. In the middle stage of equal diameter (500-1000), the furnace pressure, argon gas and crucible speed gradually change from the early stage of equal diameter to the corresponding parameters in the late stage of equal diameter.

[0114] 11. In the later stage of equal diameter (>1000), the furnace pressure is 12torr, the argon flow rate is 80slpm, and the crucible speed is 5r / min.

[0115] Example 6

[0116] This embodiment provides a method for preparing a single crystal silicon rod by a Czochralski method (36-inch hot field), which is different from Embodiment 1 only in that the parameters of steps 6-11 are different:

[0117] 6. Production begins with temperature adjustment, furnace pressure controlled at 25 torr, argon flow rate at 80 slpm, and crucible speed at 3.5 r / min.

[0118] 7. After the crystal seeding starts, the furnace pressure is controlled at 10 torr, the argon flow rate is 80 slpm, and the crucible speed is 5 r / min.

[0119] 8. After shoulder release begins, the furnace pressure is controlled at 10 torr, the argon flow rate is 80 slpm, and the crucible speed is 9 r / min.

[0120] 9. In the early stage of equal diameter (0-500), the furnace pressure is controlled at 3 torr, the argon flow rate is 60 slpm, and the crucible speed is 9 r / min.

[0121] 10. In the middle stage of equal diameter (500-1000), the furnace pressure, argon gas and crucible speed gradually change from the early stage of equal diameter to the corresponding parameters in the late stage of equal diameter.

[0122] 11. In the later stage of equal diameter (>1000), the furnace pressure is 12torr, the argon flow rate is 80slpm, and the crucible speed is 5r / min.

[0123] Test Example 1:

[0124] Ten single crystal silicon rods A and ten single crystal silicon rods B in each of Example 1 and Comparative Example were randomly collected, and the resistance of the collected single crystal silicon rods was tested. The results are shown in Table 1.

[0125] Table 1

[0126] Head resistance Ω·m Tail resistance Ω·m Head-tail difference Ω·m Example 1 1.01 1.03 0.02 Comparative Example 1 1.12 1.15 0.03 Comparative Example 2 1.02 1.2 0.18 Comparative Example 3 1.2 0.7 0.5 Example 2 4.1 4.5 0.4 Example 3 0.94 0.96 0.02 Example 4 0.97 0.96 0.01 Example 5 1.02 1.32 0.3 Example 6 1.03 1.17 0.14

[0127] Test Example 2:

[0128] The single crystal silicon rods prepared in the above examples and comparative examples were processed and TOPcon cells were manufactured according to the following steps:

[0129] 1. Texturing: The single crystal silicon rods prepared in the above embodiments and comparative examples are cut into N-type raw silicon wafers of corresponding sizes through a slicing process, and the N-type raw silicon wafers are placed in a texturing tank with a NaOH volume concentration of 10%, a temperature of 60°C, and 10L of additives. Subsequently, the wafers are washed with water, acid washed (HF volume concentration of 15%), washed with water, slowly pulled, and dried at a temperature of 90°C.

[0130] 2. Boron expansion: Place the silicon wafer after texturing in a boron expansion tube, with the source temperature at 800°C for 200s and the junction temperature at 1000°C for 1000s.

[0131] 3. Remove BSG + alkali polishing: Etch the boron-expanded silicon wafer on a chain acid etching machine, and the HF volume concentration in the acid tank is 10%.

[0132] 4. Tunneling layer + making amorphous silicon level doping process:

[0133] E-poly in-situ doped amorphous silicon: using PH3 and SiH4 mixed gas, process temperature 400℃.

[0134] 5. RCA de-winding: Silicon oxide is grown on the back of the silicon wafer, and the silicon oxide is washed off the front winding area with HF (volume concentration 20%), and then placed in an alkaline polishing tank (NaOH volume concentration 10%, temperature 70°C, alkaline polishing additive 150L) for alkaline polishing to remove the front polysilicon winding, and obtain a doped polysilicon layer on the tunneling oxide layer on the back;

[0135] 6. The ALO deposition method uses single atomic layer deposition (ALD). The process conditions of the single atomic layer deposition method are: temperature of 230°C, process: TMA, 4 8s purge 7 10s H2O, 4 8s purge 710s, the treatment method of each cycle is to first introduce TMA for 4 8s, purge 7 10s, then introduce water vapor for 4 8s, purge 710s, and the number of cycles is 22 51 times. Among them, TMA is Al(CH3)3, and TMA and water form an aluminum oxide film together. A front silicon nitride layer is formed on the front aluminum oxide layer;

[0136] The front and back SiN layers are deposited by plasma chemical vapor deposition, and the process conditions are: temperature 470°C and pressure 250Pa.

[0137] 7. Carry out printing, sintering, metallization and testing in sequence.

[0138] The efficiency and qualified rate of the TOPCon cells prepared in the above manner were tested, and the results are shown in Table 2.

[0139] Table 2

[0140]

[0141]

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a single crystal silicon rod by a Czochralski method, characterized in that: include: Add silicon and antimony elements to the furnace after the previous single crystal silicon rod is processed. The added mass of antimony element is M 1Sb =M 2Sb +(t2+12)×b Sb -M 3Sb , where M 2Sb M is the mass of antimony element required to prepare the single crystal silicon rod, in g; 3Sb is the mass of the remaining antimony element in the furnace, in g; b Sb is the volatility coefficient of antimony element, b Sb It is 0.1h / g~15h / g; t2 is the interval time between T3 and T4, in h; T3 is the time when the previous single crystal silicon rod is removed after the wire is broken, and T4 is the time when the barrel is removed after the last barrel of silicon material is added.

2. The method for preparing a single crystal silicon rod by the Czochralski method according to claim 1, characterized in that: The M 2Sb It is calculated based on the resistivity of the single crystal silicon rod to be prepared, 3Sb Calculated based on the resistivity of the tail of the previous single crystal silicon rod.

3. The method for preparing a single crystal silicon rod by the Czochralski method according to claim 1, characterized in that: The antimony element is added into the furnace 1 to 60 minutes before the seed crystal is melted.

4. The method for preparing a single crystal silicon rod by the Czochralski method according to claim 1, characterized in that: When the crystal pulling wire breaks, the furnace is temperature-adjusted and released 1 to 3 times to compensate for the doped antimony element. The mass of the doped antimony element M0 each time is compensated = (t1+5)×a, where a is the temperature adjustment volatility coefficient of the antimony element, and a is 0.1h / g~15h / g; t1 is the interval time between T1 and T2, in h; T1 is the start time of welding, and T2 is the time when the crystal pulling wire breaks.

5. The method for preparing a single crystal silicon rod by the Czochralski method according to claim 1, characterized in that: The compensatory doping of antimony element is performed by using a supplementary doping device, which comprises a sleeve and a push rod capable of moving along the inner cavity of the sleeve, one end of the push rod passes through the sleeve and is provided with a hopper; The sleeve is provided with a guide groove, which includes a push-pull groove arranged along the axial direction of the push rod and a steering groove arranged along the circumference of the push rod. A sliding block capable of sliding along the guide groove is fixed to one side of the push rod located in the sleeve.

6. The method for preparing a single crystal silicon rod by the Czochralski method according to claim 1, characterized in that: In the temperature-adjusting welding step, the furnace pressure is 1 torr to 100 torr, preferably 7 torr to 25 torr.

7. The method for preparing a single crystal silicon rod by Czochralski method according to claim 1, characterized in that: In the seeding step, the argon flow rate is 60slpm to 200slpm, the furnace pressure is 1torr to 100torr, and the crucible speed is 3.5r / min to 5r / min; Preferably, the argon flow rate is 80 slpm to 120 slpm, the furnace pressure is 2 torr to 10 torr, and the crucible rotation speed is 3.5 r / min to 5 r / min.

8. The method for preparing a single crystal silicon rod by the Czochralski method according to claim 1, characterized in that: In the shoulder release step, the argon flow rate is 60slpm to 200slpm, the furnace pressure is 1torr to 100torr, and the crucible speed is 1r / min to 10r / min; Preferably, the argon flow rate is 80 slpm to 120 slpm, the furnace pressure is 2 torr to 10 torr, and the crucible rotation speed is 5 r / min to 9 r / min.

9. The method for preparing a single crystal silicon rod by Czochralski method according to claim 1, characterized in that: The isodiametric step includes the early isodiametric stage, the middle isodiametric stage and the late isodiametric stage; In the early stage of equal diameter, the argon flow rate is 60slpm~200slpm, the furnace pressure is 3torr~20torr, and the crucible speed is 5r / min~9r / min; In the middle stage of equal diameter, after the crystal is pulled to 500mm, adjust the argon flow rate to 60slpm~90slpm, the furnace pressure to 10torr~15torr, and the crucible speed to 1r / min~7r / min; After the crystal is pulled to 1000mm in the later stage of equal diameter, the argon flow rate is adjusted to 80slpm, the furnace pressure is 12torr, and the crucible speed is 5r / min.

10. A single crystal silicon rod prepared by the method according to any one of claims 1 to 9, characterized in that: The resistivity is 0.2Ω.cm to 28Ω.cm; and / or the antimony doping concentration is 2.3×10 16 atoms / cm 3 ~1.17×10 14 atoms / cm 3 ; and / or, the resistivity difference between the head and tail of a single single crystal silicon rod is less than 0.02Ω.cm.

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