Silicon liquid resistivity measurement method and device and silicon rod resistivity control method and device

Abstract

The embodiment of the invention provides a silicon liquid resistivity measurement method and device and a silicon rod resistivity control method and device. The measuring method comprises the following steps: controlling a probe to extend into silicon liquid to form a resistance measuring loop; reading the total resistance measured by a resistance measuring instrument between the probes; calculating the melt resistance of the silicon liquid between the probes according to the total resistance; and determining the resistivity of the silicon liquid according to the melt resistance. In the embodiment of the invention, by measuring the resistivity of the silicon liquid, the doping proportion of charging can be adjusted, so that the resistivity of the silicon single crystal rod is controlled within a proper range. Therefore, the operation of measuring the resistivity of the silicon single crystal rod by lifting a cover can be avoided, the working hours are saved, the target rate of the resistivity of the silicon single crystal rod is improved, and the yield of the silicon single crystal rod can be improved.

Description

Technical Field

[0001] This application belongs to the technical field of photovoltaic processing, and particularly relates to a method for measuring the resistivity of silicon liquid, a device for measuring the resistivity of silicon liquid, a method for controlling the resistivity of a silicon rod, and a device for controlling the resistivity of a silicon rod. Background Art

[0002] The Czochralski method is currently a main method for preparing single-crystal silicon rods. The basic principle is to put high-purity polysilicon into a crucible and melt it into silicon liquid in a single-crystal furnace. Then, a seed crystal fixed on a seed crystal shaft is inserted into the surface of the silicon liquid. After the seed crystal is fused with the silicon liquid, the seed crystal is slowly lifted and rotated upward, and a crystal grows at the lower end of the seed crystal to form a single-crystal silicon rod. The resistivity of a single-crystal silicon rod without impurities is very high and it hardly conducts electricity. However, for a single-crystal silicon rod used in a photovoltaic cell, there are requirements for resistivity, and the polysilicon raw material must be doped. For example, the resistivity requirement for a gallium-doped P-type silicon rod is 0.4 - 1.1 Ω·cm, and the resistivity requirement for a phosphorus-doped N-type silicon rod is 0.3 - 2.1 Ω·cm. Due to the segregation effect of the doping element, the resistivity of the single-crystal silicon rod gradually decreases from the head to the tail. Therefore, the control of the resistivity of the single-crystal silicon rod is particularly important, and generally, the proportion of reaching the target resistivity at the head, that is, the hit rate, is used to represent the control accuracy.

[0003] In the existing technology, in order to ensure the resistivity of the single-crystal silicon rod, the traditional method is to measure by lifting the cover, that is, before each crystal growth, first lower the seed crystal to the surface of the silicon liquid, quickly lower the temperature to the crystallization temperature, lift a piece of crystal for resistivity measurement. However, because the temperature on the surface of the silicon liquid drops relatively low, it is necessary to re-adjust the temperature, wasting time, even exceeding 2 hours. That is, the existing method for controlling the resistivity of a single-crystal silicon rod is not only cumbersome in process, but also very time-consuming, reducing the production efficiency of the single-crystal silicon rod. Summary of the Invention

[0004] This application aims to provide a method for measuring the resistivity of silicon liquid, a device for measuring the resistivity of silicon liquid, a method for controlling the resistivity of a silicon rod, and a device for controlling the resistivity of a silicon rod to solve the problems of cumbersome process and time-consuming in the existing method for measuring the resistivity of a single-crystal silicon rod.

[0005] To solve the above technical problems, this application is implemented as follows:

[0006] In a first aspect, this application discloses a method for measuring the resistivity of silicon liquid, and the measuring method includes:

[0007] Controlling a probe to extend into the silicon liquid to form a resistance measurement circuit;

[0008] Reading the total resistance measured by a resistance measuring instrument between the probes;

[0009] Calculate the melt resistance of the silicon liquid between the probes according to the total resistance;

[0010] Determine the resistivity of the silicon liquid according to the melt resistance.

[0011] In the embodiments of the present application, by controlling two probes to extend into the silicon liquid to form a resistance measurement circuit; reading the total resistance measured by a resistance measuring instrument between the two probes; calculating the melt resistance of the silicon liquid between the two probes according to the total resistance value; and determining the resistivity of the silicon liquid according to the melt resistance, the resistivity of the silicon liquid can be measured. Since the resistivity of the silicon liquid corresponds to the resistivity of the single crystal silicon rod, by measuring the resistivity of the silicon liquid, the doping ratio of the added material can be adjusted to control the resistivity of the single crystal silicon rod within a suitable range. In this way, the operation of measuring the resistivity of the single crystal silicon rod by lifting the lid can be avoided, the working hours can be saved, the target hitting rate of the resistivity of the single crystal silicon rod can be improved, and the yield of the single crystal silicon rod can be increased.

[0012] In a second aspect, the present application also discloses a method for controlling the resistivity of a silicon rod, and the control method includes:

[0013] Before adding materials into the crucible in the single crystal furnace, measure the resistivity of the silicon liquid in the crucible;

[0014] Calculate the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid;

[0015] Determine the doping ratios of the dopant and the silicon-based raw material according to the impurity concentration of the silicon liquid, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal silicon rod, so as to control the resistivity of the single crystal silicon rod.

[0016] Optionally, the corresponding relationship between the silicon liquid impurities and resistivity is obtained by the method of measuring by lifting the lid multiple times, wherein, in each process of measuring by lifting the lid, the impurity concentration of the silicon liquid is different.

[0017] Optionally, the step of determining the doping ratios of the dopant and the silicon-based raw material according to the impurity concentration of the silicon liquid, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal silicon rod to control the resistivity of the single crystal silicon rod includes:

[0018] Convert the resistivity of the added dopant and silicon-based raw material into the impurity atom density;

[0019] Calculate the impurity concentrations of the dopant and the silicon-based raw material;

[0020] Calculate the target impurity concentration of the single crystal silicon rod according to the target resistivity of the single crystal silicon rod;

[0021] According to the impurity concentration target of the single crystal silicon rod, the impurity concentration of the silicon liquid after the feeding is completed and melted is obtained;

[0022] According to the impurity concentration of the silicon liquid after the feeding is completed and melted, the weights of the dopant and the silicon-based raw material during the feeding process are calculated to control the resistivity of the single crystal silicon rod.

[0023] In a third aspect, the present application also discloses a method for controlling the resistivity of a silicon rod, and the control method includes:

[0024] After the feeding is completed and completely melted into silicon liquid, the resistivity of the silicon liquid is measured;

[0025] According to the resistivity of the silicon liquid, the impurity concentration of the silicon liquid is calculated;

[0026] According to the impurity concentration of the silicon liquid, the amount of dopant to be added is determined to control the resistivity of the single crystal silicon rod.

[0027] In a fourth aspect, the present application also discloses a measuring device for the resistivity of silicon liquid, and the measuring device includes: a resistance measuring instrument, a telescopic mechanism, and two probes; wherein,

[0028] The probes are respectively electrically connected to both ends of the resistance measuring instrument;

[0029] The telescopic mechanism is connected to the two probes, and the telescopic mechanism is used to drive the two probes to extend into the silicon liquid to form a resistance measurement circuit;

[0030] The resistance measuring instrument is used to measure the total resistance value between the two probes, so as to calculate the melt resistance of the silicon liquid between the two probes according to the total resistance value, and determine the resistivity of the silicon liquid according to the melt resistance.

[0031] Optionally, the measuring device further includes: two electrical connecting rods; wherein,

[0032] One of the probes is connected to one of the electrical connecting rods, and the electrical connecting rod is electrically connected to the resistance measuring instrument through a wire;

[0033] The telescopic mechanism is connected to the electrical connecting rod.

[0034] Optionally, the measuring device further includes a dynamic seal, and the dynamic seal is arranged between the electrical connecting rod and the single crystal furnace for realizing the dynamic seal between the electrical connecting rod and the single crystal furnace.

[0035] Optionally, the dynamic seal is a bellows.

[0036] Optionally, the material of the probe is one of silicon seed crystal, high-purity graphite, metal tungsten molybdenum, and silicon carbide.

[0037] Fourthly, the present application also discloses a control device for the resistivity of a silicon rod. The control device includes: a main furnace body, a crucible, a heater, and the measuring device described in any one of the above; wherein,

[0038] The crucible and the heater are arranged in the main furnace body. The crucible is used for containing silicon materials, and the heater is used for melting the silicon materials into silicon liquid;

[0039] The probe of the measuring device extends into the silicon liquid. The measuring device is used for determining the resistivity of the silicon liquid, calculating the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid, and determining the doping ratio of the dopant and the silicon-based raw material according to the impurity concentration of the silicon liquid, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal silicon rod, so as to control the resistivity of the single crystal silicon rod.

[0040] In the embodiment of the present application, before adding materials into the crucible in the single crystal furnace, the resistivity of the silicon liquid in the crucible is measured; the impurity concentration of the silicon liquid is calculated according to the resistivity of the silicon liquid; the doping ratio of the materials added into the crucible is determined according to the impurity concentration of the silicon liquid, the resistivity of the added dopant and the silicon-based raw material, and the target resistivity of the single crystal silicon rod, so as to control the resistivity of the single crystal silicon rod. In this way, by measuring the resistance of the silicon liquid, the impurity concentration of the silicon liquid is obtained, so that the doping ratio can be determined, the resistivity of the single crystal silicon rod can be controlled, the purpose of improving the hitting rate of the resistivity of the single crystal head can be achieved, and the reverse cutting caused by unqualified resistivity can be reduced.

[0041] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0043] Figure 1 is a schematic structural diagram of a test device for the resistivity of a silicon liquid according to an embodiment of the present application;

[0044] Figure 2 is a flowchart of the steps of a method for measuring the resistivity of a silicon liquid according to an embodiment of the present application;

[0045] Figure 3 is a flowchart of the steps of a method for controlling the resistivity of a silicon rod according to an embodiment of the present application;

[0046] Figure 4 is a schematic diagram of the control process of the resistivity of a silicon rod according to an embodiment of the present application;

[0047] Figure 5 It is a flowchart of the steps of another method for controlling the resistivity of a silicon rod described in the embodiments of the present application.

[0048] Reference numerals: 10 - resistance measuring instrument, 11 - telescopic mechanism, 12 - probe, 13 - electric connecting rod, 14 - wire, 15 - dynamic seal, 20 - furnace cover, 21 - crucible, 22 - silicon liquid. Detailed implementation manners

[0049] Hereinafter, embodiments of the present invention will be described in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts belong to the scope of protection of the present application.

[0050] The terms "first" and "second" in the description and claims of the present application may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more. In addition, "and / or" in the description and claims means at least one of the connected objects. The character " / " generally means an "or" relationship between the associated objects before and after.

[0051] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0052] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0053] Embodiments of the present application provide a device for measuring the resistivity of silicon liquid and a method for measuring the resistivity of silicon liquid. The device and method for measuring the resistivity of silicon liquid can be used to measure the resistivity of silicon liquid. In specific applications, by measuring the resistivity of silicon liquid, the actual impurity concentration of the silicon liquid can be further obtained. According to the target impurity concentration after feeding, the doping ratio of the feed can be determined. Here, the target impurity concentration is determined according to the target resistivity of the single crystal silicon rod and the segregation coefficient of doping, so that the resistivity of the single crystal silicon rod can be accurately controlled. In this way, the operation of frequently lifting the lid to measure the resistivity of the single crystal silicon rod can be avoided, saving working hours and improving the overall pulling speed of the single crystal silicon rod.

[0054] Referring to Figure 1 , a schematic structural diagram of a test device for measuring the resistivity of silicon liquid according to an embodiment of the present application is shown. As Figure 1 shown, the test device may specifically include: a resistance measuring instrument 10, a telescopic mechanism 11, and at least two probes 12; wherein, the probes 12 are respectively electrically connected to both ends of the resistance measuring instrument 10; the telescopic mechanism 11 is connected to the probes 12, and the telescopic mechanism 11 can be used to drive the probes 12 to extend into the silicon liquid 22 to form a resistance measurement circuit; the resistance measuring instrument 10 can be used to measure the total resistance value between the probes 12, calculate the melt resistance of the silicon liquid 22 between the two probes 12 according to the total resistance value, and determine the resistivity of the silicon liquid 22 according to the melt resistance.

[0055] In specific applications, since the resistivity of the silicon liquid 22 corresponds to the resistivity of the single crystal silicon rod, by measuring the resistivity of the silicon liquid 22, the doping ratio of the feed can be adjusted to control the resistivity of the single crystal silicon rod within a suitable range. In this way, the operation of lifting the lid to measure the resistivity of the single crystal silicon rod can be avoided, saving working hours, improving the hitting rate of the resistivity of the single crystal silicon rod, and improving the yield of the single crystal silicon rod.

[0056] It should be noted that generally, by measuring the resistivity of the silicon liquid 22 and adjusting the doping ratio of the feed, the resistivity of the head of the single crystal silicon rod can be directly controlled. By controlling the resistivity of the head of the single crystal silicon rod, the purpose of controlling the resistivity of the entire single crystal silicon rod can be achieved.

[0057] As Figure 1 shown, the measuring device further includes: at least two electrical connecting rods 13; wherein, one probe 12 is connected to one electrical connecting rod 13, and the electrical connecting rod 13 is electrically connected to the resistance measuring instrument 10 through a wire 14; the telescopic mechanism 11 is connected to the electrical connecting rod 13. The telescopic mechanism 11 can be used to drive the electrical connecting rod 13 to move, so as to drive the probe 12 to extend into the silicon liquid 22 through the movement of the electrical connecting rod 13 to form a resistance measurement circuit.

[0058] In practical applications, when it is necessary to measure the resistivity of the silicon liquid 22, the electric connecting rod 13 can be driven to descend so that the probe 12 at the lower end of the electric connecting rod 13 extends into the silicon liquid 22, and the upper end of the electric connecting rod 13 can be located outside the single crystal furnace and connected to the telescopic mechanism 11 and the wire 14.

[0059] It should be noted that in the drawings of the embodiments of the present application, only the case where the numbers of the probe 12 and the electric connecting rod 13 are both two is shown. In practical applications, the number of the probes 12 can also be 4. Correspondingly, the number of the electric connecting rods 13 can also be 4, and one electric connecting rod 13 is used to fix one probe. The embodiments of the present application are only described with the case where the number of the probes 12 is two, and the case where the number of the probes 12 is 4 can be referred to for implementation. And the electric connecting rod 13 can be a metal rod capable of conducting electricity such as a molybdenum rod or a copper rod, and the embodiments of the present application do not specifically limit the material of the electric connecting rod 13.

[0060] In a specific application, two openings can be provided on the furnace cover 20 of the single crystal furnace shown in Figure 1 The electric connecting rod 13 can extend into the single crystal furnace from the openings of the furnace cover 20. The telescopic mechanism 11 can be arranged close to the openings of the furnace cover 20 and connected to the electric connecting rod 13. The telescopic mechanism 11 can be used to drive the electric connecting rod 13 to move so as to drive the probe 12 to extend into the silicon liquid 22 in the crucible 21 through the movement of the electric connecting rod 13.

[0061] Optionally, the number of the telescopic mechanisms 11 can be one or two. When the number of the telescopic mechanisms 11 is one, the two electric connecting rods 13 can be connected to the same telescopic mechanism 11, and the telescopic mechanism 11 can drive the two electric connecting rods 13 to descend simultaneously so that the two probes 12 extend into the silicon liquid 22 simultaneously. Or, the number of the telescopic mechanisms 11 can also be two. One telescopic mechanism 11 can be connected to one electric connecting rod 13 to independently drive the electric connecting rod 13 to descend so that the probe 12 extends into the silicon liquid 22.

[0062] Specifically, the telescopic mechanism 11 can be at least one of an electric telescopic mechanism and a pneumatic telescopic mechanism. When the telescopic mechanism 11 is an electric telescopic mechanism, the telescopic mechanism 11 can include a motor, a lead screw and a nut to drive the electric connecting rod 13 to move linearly. When the telescopic mechanism 11 is a pneumatic telescopic mechanism, the telescopic mechanism 11 can include a cylinder.

[0063] In some alternative embodiments of the present application, the measuring device may further include a dynamic seal 15, which is disposed between the electric connecting rod 13 and the single crystal furnace. The dynamic seal 15 can be used to achieve dynamic sealing between the electric connecting rod 13 and the single crystal furnace, so as to prevent external air or impurities from entering the single crystal furnace along with the movement of the electric connecting rod 13 and affecting the vacuum degree inside the single crystal furnace.

[0064] Optionally, the dynamic seal 15 can be a bellows. Since the bellows can be telescopically adjusted along with the electric connecting rod 13, reliable sealing between the electric connecting rod 13 and the single crystal furnace can be achieved during the descent or ascent of the electric connecting rod 13.

[0065] It should be noted that in practical applications, the dynamic seal 15 can also be in the form of packing seal or expansion ring seal, etc., and the embodiments of the present application do not limit this.

[0066] Optionally, the probe 12 is made of silicon crystal. When measuring the resistance of the silicon liquid 22, the probe 12 needs to be inserted into the silicon liquid 22. To avoid contaminating the silicon liquid 22, the probe 12 can be made of silicon crystal. Moreover, a heavily doped seed crystal with a smaller resistivity is preferably used to reduce the interference with the measurement of the resistance of the silicon liquid 22. In practical applications, when the probe 12 is inserted into the silicon liquid 22, the liquid surface temperature of the silicon liquid 22 needs to be lowered to near the melting point of silicon, i.e., 1420 °C for measurement.

[0067] It should be noted that in specific applications, the probe 12 can also be made of high-purity high-temperature-resistant materials such as tungsten and molybdenum, for example, one of carbon-carbon composites, metallic tungsten and molybdenum, and silicon carbide, but the insertion depth and time into the silicon liquid 22 need to be strictly controlled.

[0068] Refer to Figure 2 , which shows a step flowchart of a method for measuring the resistivity of silicon liquid according to an embodiment of the present application. As Figure 1 shown, the measuring method may specifically include the following steps:

[0069] Step 101: Control the probe to extend into the silicon liquid to form a resistance measurement circuit.

[0070] In the embodiments of the present application, the resistivity of the silicon liquid 22 can be measured by using the measuring device shown in Figure 1 . Specifically, when it is necessary to measure the resistivity of the silicon liquid, two probes 12 can be controlled to extend into the silicon liquid to form a resistance measurement circuit.

[0071] Specifically, the telescopic mechanism 11 can be started to drive the electric connecting rod 13 to descend, so that the two probes 12 can extend into the silicon liquid 22.

[0072] Step 102: Read the total resistance measured by the resistance measuring instrument between the two probes.

[0073] Specifically, after forming the resistance measurement circuit, the total resistance R measured by the resistance measuring instrument 10 can be directly read. X .

[0074] Step 103: Calculate the melt resistance of the silicon liquid between the probes according to the total resistance value.

[0075] In a specific application, taking the number of probes 12 as an example for illustration, the total resistance R X can be expressed by the following formula:

[0076] R X = R L + 2*R1 + 2*R2 + 2*R3 = R L + R0 (Formula 1)

[0077] Wherein, R L is the melt resistance of the silicon liquid 22 between the two probes 12, R0 is the total interference resistance, R1 is the resistance of the probe 12, R2 is the resistance of the electrical connecting rod 13, and R3 is the resistance of the wire 14. That is, the calculation formula for the total interference resistance is:

[0078] R0 = 2*R1 + 2*R2 + 2*R3 (Formula 2)

[0079] In actual applications, under the condition of consistent measurement conditions, R1, R2, and R3 remain unchanged, that is, R0 remains unchanged. If the dopant concentration changes, it will inevitably cause a change in R L to change, and correspondingly, R X to change. In order to make the change in R L make the change in R X more significant, R1, R2, and R3 need to be as small as possible.

[0080] In actual applications, the total interference resistance R0 between the two probes 12 in the resistance measurement circuit can be obtained first; then, subtracting the total interference resistance R0 from the total resistance R L can obtain the melt resistance R of the silicon liquid 22 between the two probes 12 L .

[0081] Step 104: Determine the resistivity of the silicon liquid according to the melt resistance.

[0082] In the embodiment of the present application, since the melt resistance R L of the silicon liquid 22 is positively correlated with the resistivity of the silicon liquid 22, after measuring the melt resistance R L , the melt resistance R L, determine the resistivity of the silicon liquid 22. Specifically, the resistivity ρ of the silicon liquid 22 L can be calculated by the following formula:

[0083]

[0084] where λ is the proportionality coefficient between resistance and resistivity. When the weight of the silicon liquid 22 is fixed, the distance of the measurement point is fixed, and the insertion depth of the probe 12 is fixed, that is, when the measurement conditions are fixed, λ is a constant.

[0085] In a specific application, since the resistivity of the silicon liquid 22 corresponds to the resistivity of the single crystal silicon rod, by measuring the resistivity of the silicon liquid 22, the doping ratio of the added material can be adjusted to control the resistivity of the single crystal silicon rod within a suitable range. In this way, the operation of measuring the resistivity of the single crystal silicon rod by lifting the lid can be avoided, saving working hours and improving the overall drawing speed of the single crystal silicon rod.

[0086] In summary, the method for measuring the resistivity of the silicon liquid described in the embodiments of the present application has at least the following advantages:

[0087] In the embodiments of the present application, by controlling the probe to extend into the silicon liquid to form a resistance measurement circuit; reading the total resistance measured by the resistance measuring instrument between the probes; calculating the melt resistance of the silicon liquid between the probes according to the total resistance value; and determining the resistivity of the silicon liquid according to the melt resistance, the resistivity of the silicon liquid can be measured. Since the resistivity of the silicon liquid corresponds to the resistivity of the single crystal silicon rod, by measuring the resistivity of the silicon liquid, the doping ratio of the added material can be adjusted to control the resistivity of the single crystal silicon rod within a suitable range. In this way, the operation of measuring the resistivity of the single crystal silicon rod by lifting the lid can be avoided, saving working hours, increasing the hitting rate of the resistivity of the single crystal silicon rod, and improving the overall drawing speed and yield rate of the single crystal silicon rod.

[0088] Referring to Figure 3 , a step flowchart of a method for controlling the resistivity of a silicon rod described in the embodiments of the present application is shown. As Figure 3 shown, the control method may specifically include the following steps:

[0089] Step 301: Before adding material to the crucible in the single crystal furnace, measure the resistivity of the silicon liquid in the crucible.

[0090] In the embodiments of the present application, as Figure 4 shown in a, before adding material to the crucible 21 in the single crystal furnace, the melt resistance Rn-1 can be measured first, so as to determine the resistivity ρ of the silicon liquid before adding material n-1 .

[0091] It should be noted that the specific measurement method of the resistivity ρ n-1 can be asFigure 2 As shown in the method embodiments described above, details are not elaborated herein.

[0092] In practical applications, in cases where multiple feedings are required, the resistivity of the silicon liquid can be measured before each feeding, or the resistivity of the silicon liquid can be measured before the last feeding. Since the result of the last feeding has the greatest impact on the resistivity of the finally drawn single crystal silicon rod, preferably, the resistivity of the silicon liquid can be measured before the last feeding, and the doping ratio of the last feeding can be controlled according to the resistivity of the silicon liquid, so as to achieve the purpose of controlling the resistivity of the single crystal silicon rod.

[0093] Step 302: Calculate the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid.

[0094] In the embodiments of the present application, the impurity concentration of the silicon liquid 22 before the last feeding can be calculated according to the resistivity ρ of the silicon liquid, and the specific process is as follows. n-1 As shown in

[0095] As shown in Figure 4 b, before feeding, the total weight of the melt in the crucible is M n-1 . Among the added materials, the impurity concentrations of the dopant and the silicon-based raw material are Ca and Cb respectively, which are known. The weight of the dopant M a and the weight of the silicon-based raw material M b in the feeding are parameters to be determined. Figure 4 As shown in n c, after the feeding is completed and melted, the total weight of the silicon liquid in the crucible 21 is M n , after the feeding is completed, the impurity concentration of the silicon liquid in the crucible is C n , and the resistivity is ρ

[0096] M a +M b +M n-1 =M n (Formula Four)

[0097] M a ×C a +M b ×C b +M n-1 ×C n-1 =M n ×C n (Formula Five)

[0098] It should be noted that in the embodiments of the present application, the dopant may be a pure dopant, for example, pure phosphorus. The dopant may also be a master alloy including the dopant, for example, a master alloy of silicon and phosphorus doped in a certain proportion. The embodiments of the present application may not limit the specific content of the dopant. Similarly, the silicon-based raw material may be single-crystalline silicon, polycrystalline silicon, or even pulled-back material, etc., and the embodiments of the present application may not limit the specific content of the silicon-based raw material.

[0099] Figure 4 As shown in d, the resistivity of the single-crystalline silicon rod is ρ s , and the impurity concentration is C s , and the relationship between the two is expressed by the following formula:

[0100]

[0101] where both e and μ are constants, e = 1.6×10−19 C (Coulomb), for N-type semiconductors, μ = 1500 cm / V·S; NVS is the atomic density of the impurity, with the unit of atoms / cm 3 , NVi is the atomic density of the silicon crystal, 4.996×1022 atoms / cm 3 , P is the atomic weight of phosphorus, with a value of 28.09, and Si is the atomic weight of silicon, with a value of 30.97.

[0102] It should be noted that this embodiment only illustrates phosphorus doping. For other dopings such as boron doping, for P-type semiconductors, the above constants are also known.

[0103] According to the definition of the impurity segregation coefficient K, we can obtain:

[0104]

[0105] Here, K refers to the effective segregation coefficient, which includes factors such as the dopant volatilization coefficient and impurity diffusion during the melting and crystallization process. The effective segregation coefficient is between the equilibrium segregation coefficient and 1. Taking phosphorus as an example, 0.35 ≤ K ≤ 1; it should be noted that this effective segregation coefficient is the corrected segregation coefficient.

[0106] Assuming the target resistivity of the single-crystalline silicon rod is ρs, then according to (Equation Six), the target impurity concentration of the single-crystalline silicon rod can be calculated:

[0107]

[0108] According to (Equation Seven) and (Equation Eight), the impurity concentration Cn after the feeding is completed and the material is melted is calculated:

[0109]

[0110] In (Equation Four) and (Equation Five), the only unknown is Ma , M b and C n-1 , while C n-1 is obtained by measuring the melt resistance R L as follows:

[0111] The melt resistance between the measurement points is R n-1 , and the total interference resistance is R0, then there is

[0112] R n-1 = R x - R0 (Equation Ten)

[0113] R n-1 = R × ρ n-1 (Equation Eleven)

[0114] where λ is the proportionality coefficient between resistance and resistivity. When the weight of the silicon liquid is fixed, the distance between the measurement points is fixed, and the insertion depth of the probe is fixed, that is, when the measurement conditions are fixed, λ is a constant.

[0115]

[0116] According to the relationship between the impurity concentration of the silicon liquid and the resistivity, it can be obtained that:

[0117]

[0118] where NV j is the atomic density of the silicon melt, 2.50 / 2.33 * 4.996 × 10 22 = 5.361 × 10 22 atoms / cm 3 .

[0119] The above determines the relationship between the impurity concentration C n-1 and the total measurement resistance R x . The coefficients A and the total interference resistance R0 are constants, but they are not easily obtained directly and need to be determined by the two-time lid-lifting measurement comparison method. As Figure 4 shown in a, the resistivity of the single crystal measured by lid-lifting is [ρ s n-1 , and thus the impurity concentration of the lid-lifting single crystal can be obtained:

[0120]

[0121] The impurity concentration of the silicon liquid is obtained according to the segregation coefficient.

[0122]

[0123] ​Two - time lid - lifting measurement comparison method: Feed materials twice to obtain silicon liquids with two different impurity contents. Measure the resistance twice to obtain two Rx values, and correspondingly lift the lid and measure twice to obtain two C n-1 values. According to (Formula XIII), obtain a system of equations about A and R0, then the values of A and R0 can be calculated. Substitute them into (Formula XIII) to determine the impurity concentration C of the silicon liquid n-1 and the corresponding relationship with the measured total resistance R x .

[0124] In practical applications, after determining the corresponding relationship between the impurity concentration C of the silicon liquid n-1 and the measured total resistance R x , from the system of binary linear equations composed of (Formula IV) and (Formula V), the unknowns M a and M b can be easily obtained. That is to say, by measuring the resistance of the silicon liquid, the impurity concentration of the silicon liquid is obtained, so that the doping ratio can be determined, and finally the target resistivity of the single - crystal silicon rod can be controlled.

[0125] Step 303: Determine the doping ratios of the dopant and the silicon - based raw material according to the impurity concentration of the silicon liquid, the resistivities of the dopant and the silicon - based raw material, and the target resistivity of the single - crystal silicon rod, so as to control the resistivity of the single - crystal silicon rod.

[0126] In the embodiments of the present application, after calculating the impurity concentration of the silicon liquid, according to the impurity concentration of the silicon liquid, the resistivities of the added dopant and the silicon - based raw material, and the target resistivity of the single - crystal silicon rod, the doping ratios of the added dopant and the silicon - based raw material can be determined to control the resistivity of the single - crystal silicon rod, which may specifically include the following sub - steps.

[0127] Sub - step S11: Convert the resistivities of the dopant and the silicon - based raw material in the last feeding into impurity atom densities.

[0128] Sub - step S11: Calculate the impurity concentrations of the dopant and the silicon - based raw material.

[0129] Sub - step S11: Calculate the target impurity concentration of the single - crystal silicon rod according to the target resistivity of the single - crystal silicon rod.

[0130] Sub - step S11: Calculate the impurity concentration of the silicon liquid after the feeding is completed and melted according to the target impurity concentration of the single - crystal silicon rod.

[0131] Sub - step S11: Calculate the weights of the dopant and the silicon - based raw material during the feeding process according to the impurity concentration of the silicon liquid after the feeding is completed and melted, so as to control the resistivity of the single - crystal silicon rod.

[0132] The following provides a specific embodiment:

[0133] 1. The probe 12 is made of a high-purity molybdenum rod with a purity of 99.99%, and its size is φ16 * 50; the electrical connecting rod 13 has a size of φ20 * 1400; the wire 14 is made of copper, with a cross-sectional area of 2.5 mm 2 , and a length of 2 m; the distance between the two measurement points of the silicon liquid 22 is 150 mm; the resistance measuring instrument 10 has a measurement accuracy of 0.1%.

[0134] 2. The target resistivity of the single-crystal silicon rod is ρ s = 1.25 Ω·cm, the total feeding amount M n = 980 Kg, 42 Kg is fed, M n－1 = 980 - 42 = 938 Kg, the resistivity of the phosphorus-doped dopant is ρ a = 0.016 Ω·cm, and the resistivity of the silicon-based raw material added is ρ b = 0.809 Ω·cm.

[0135] It should be noted that when the dopant is a pure dopant, the resistivity of the dopant is the resistivity of the dopant itself. When the dopant is a master alloy containing the dopant, the resistivity of the dopant is the resistivity of the master alloy. When the silicon-based raw material is one of single-crystal silicon, polycrystalline silicon or re-drawn material, the resistivity of the silicon-based material is the resistivity of the single-crystal silicon, polycrystalline silicon or re-drawn material. When the silicon-based raw material is two or more of single-crystal silicon, polycrystalline silicon or re-drawn material, the resistivity of the silicon-based material is the average resistivity of these two or more raw materials.

[0136] 3. First, convert the resistivity of the dopant and the silicon-based raw material into impurity atom density:

[0137]

[0138]

[0139] 4. Then calculate the impurity weight concentration of the dopant and the silicon-based raw material.

[0140]

[0141]

[0142] 5. According to the target resistivity of the single-crystal silicon rod, find the target impurity concentration of the single-crystal silicon rod according to (Formula VIII).

[0143]

[0144] 6. Take the segregation coefficient K = 0.37, and find the impurity concentration after the feeding is completed and melted according to (Formula IX).

[0145]

[0146] 7. Two lid-lifting measurements: The feeding amount M n－1 = 938 Kg for two times, obtaining two silicon liquids with different dopings. For the first measurement, the total resistance R x1 = 131.1 mΩ, and the measured crystal resistivity ρ1 = 0.93 Ω·cm during lid-lifting; for the second measurement, the total resistance R x2 = 174.6 mΩ, and the measured crystal resistivity ρ2 = 1.37 Ω·cm during lid-lifting;

[0147] According to (Formula XV), calculate the impurity concentration of the silicon liquid during the first measurement

[0148]

[0149] Similarly, calculate the impurity concentration of the silicon liquid during the second measurement

[0150]

[0151] Substitute into (Formula XIII) to obtain the system of equations:

[0152]

[0153] Solve the equations to obtain:

[0154]

[0155] Thus, the impurity concentration C of the silicon liquid is determined n－1 and the corresponding relationship with the measured total resistance R x is:

[0156]

[0157] 8. Measure the resistance R of the silicon liquid before the last feeding for a certain furnace of feeding x = 162.8 mΩ, and calculate the impurity concentration of the silicon liquid by (Formula XVI) as:

[0158]

[0159] 9. Substitute the above data into (Formula IV) and (Formula V) to obtain the system of equations

[0160]

[0161] Solve to obtain

[0162]

[0163] 10. According to the calculated doping ratio, the dopant Ma = 637 g, and 41.4 Kg of polycrystalline material is added for the last time. The resistivity of the single crystal silicon rod measured during crystal pulling is 1.27 Ω·cm, and the deviation from the target is 1.25 - 1.27 = -0.02 Ω·cm, which is within the acceptable range.

[0164] It should be noted that the method for controlling the resistivity of the single crystal silicon rod described in the embodiments of the present application can be used in, but not limited to, the following application scenarios:

[0165] Application scenario 1: Before the last addition of materials, measure the melt resistance to obtain the resistivity and impurity concentration of the silicon liquid. Convert the target resistivity of the single crystal silicon rod into the target impurity concentration of the silicon liquid required after adding materials, and then determine the doping ratio of the added materials based on the impurity concentrations of the added materials and the dopant, so as to accurately control the resistivity of the single crystal silicon rod.

[0166] Application scenario 2: Before crystal growth, test the resistance of the silicon liquid to obtain the resistivity and impurity concentration of the silicon liquid, and select whether to separately add a dopant to control the resistivity of the single crystal silicon rod within a suitable range.

[0167] Application scenario 3: Before crystal growth, test the melt resistance to obtain the resistivity and impurity concentration of the melt. Without adding a dopant, pull the crystal rod to a suitable length to avoid waste caused by reverse cutting.

[0168] In the embodiments of the present application, before adding materials into the crucible in the single crystal furnace, measure the resistivity of the silicon liquid in the crucible; calculate the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid; determine the doping ratio of the materials added into the crucible based on the impurity concentration of the silicon liquid, the resistivity of the dopant and the silicon-based raw materials for the next addition of materials, and the target resistivity of the single crystal silicon rod, so as to control the resistivity of the single crystal silicon rod. In this way, by measuring the resistance of the silicon liquid, the impurity concentration of the silicon liquid is obtained, so that the doping ratio can be determined, the resistivity of the single crystal silicon rod can be controlled, the purpose of improving the hitting rate of the resistivity of the single crystal head can be achieved, and the reverse cutting caused by unqualified resistivity can be reduced.

[0169] Refer to Figure 5 , which shows the step flow chart of another method for controlling the resistivity of the silicon rod described in the embodiments of the present application. As Figure 5 shown, the control method may specifically include the following steps.

[0170] Step 501: After the addition of materials is completed and completely melted into silicon liquid, measure the resistivity of the silicon liquid.

[0171] In the embodiments of the present application, after all the silicon-based raw materials are added into the crucible and the silicon-based raw materials are completely melted into silicon liquid, the melt resistance of the silicon liquid can be measured first, so as to determine the resistivity of the silicon liquid before adding the dopant.

[0172] It should be noted that the specific measurement method of the resistivity of the silicon liquid can be as shown in the method embodiments shown below, and will not be elaborated here. Figure 2 as shown below, and will not be elaborated here.

[0173] Step 502: Calculate the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid.

[0174] In the embodiments of the present application, the impurity concentration of the silicon liquid can be calculated with reference to step 302 in the above embodiments, and will not be elaborated here.

[0175] Step 503: Determine the amount of dopant to be added according to the impurity concentration of the silicon liquid to control the resistivity of the single crystal silicon rod.

[0176] Specifically, after calculating the impurity concentration of the silicon liquid, the weight of the dopant to be increased can be determined according to the impurity concentration of the silicon liquid, the resistivity of the dopant, and the target resistivity of the single crystal silicon rod to control the resistivity of the single crystal silicon rod. The specific calculation process can refer to step 303 in the foregoing embodiments and will not be elaborated here.

[0177] In the embodiments of the present application, by measuring the resistance of the silicon liquid, the impurity concentration of the silicon liquid is obtained, so that the mass of the dopant to be doped can be determined to control the resistivity of the single crystal silicon rod, achieving the purpose of improving the hitting rate of the resistivity of the single crystal head and reducing the back cutting caused by unqualified resistivity.

[0178] The embodiments of the present application further provide a control device for the resistivity of a silicon rod. The control device may specifically include: a main furnace body, a crucible, a heater, and the measuring device described in any one of the above embodiments; wherein, the crucible and the heater are arranged in the main furnace body, the crucible is used for containing silicon materials, and the heater is used for melting the silicon materials into silicon liquid; the probe of the measuring device extends into the silicon liquid, and the measuring device is used for determining the resistivity of the silicon liquid, calculating the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid, and determining the doping ratio of the dopant and the silicon-based raw material according to the impurity concentration of the silicon liquid, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal silicon rod to control the resistivity of the single crystal silicon rod.

[0179] In the embodiments of the present application, before adding materials into the crucible in the single crystal furnace, or after all the silicon-based raw materials are added into the crucible and the silicon-based raw materials are completely melted into silicon liquid, the resistivity of the silicon liquid in the crucible can be measured; according to the resistivity of the silicon liquid, the impurity concentration of the silicon liquid can be calculated; according to the impurity concentration of the silicon liquid, the doping agent added during material addition, the resistivity of the silicon-based raw materials, and the target resistivity of the single crystal rod, the doping ratio of the materials added into the crucible can be determined to control the resistivity of the single crystal rod. In this way, by measuring the resistance of the silicon liquid, the impurity concentration of the silicon liquid is obtained, so that the doping ratio can be determined, the resistivity of the single crystal rod can be controlled, the purpose of improving the hitting rate of the resistivity of the single crystal head can be achieved, and the reverse cutting caused by unqualified resistivity can be reduced.

[0180] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0181] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for measuring the resistivity of silicon liquid, characterized in that, The measurement method includes: Controlling the probe to extend into the silicon melt to form a resistance measurement circuit; Reading the total resistance measured by the resistance measuring instrument between the probes; Calculating the melt resistance of the silicon melt between the probes according to the total resistance; Determining the resistivity of the silicon melt according to the melt resistance.

2. A method for controlling the resistivity of silicon rod, characterized in that, The control method includes: Before adding materials into the crucible in the single crystal furnace, measuring the resistivity of the silicon melt in the crucible; Calculating the impurity concentration of the silicon melt according to the resistivity of the silicon melt; Determining the doping ratios of the dopant and the silicon-based raw material according to the impurity concentration of the silicon melt, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal rod, so as to control the resistivity of the single crystal rod.

3. The control method according to claim 2, characterized in that, Obtaining the corresponding relationship between the silicon melt impurities and resistivity through multiple lid-lifting measurement methods, wherein, in each lid-lifting measurement process, the impurity concentration of the silicon melt is different.

4. The control method according to claim 2, characterized in that, The step of determining the doping ratios of the dopant and the silicon-based raw material according to the impurity concentration of the silicon melt, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal rod, so as to control the resistivity of the single crystal rod, includes: Converting the resistivity of the added dopant and silicon-based raw material into the impurity atom density; Calculating the impurity concentrations of the dopant and the silicon-based raw material; Calculating the target impurity concentration of the single crystal rod according to the target resistivity of the single crystal rod; Calculating the impurity concentration of the silicon melt after the feeding is completed and melted according to the target impurity concentration of the single crystal rod; Calculating the weights of the dopant and the silicon-based raw material during the feeding process according to the impurity concentration of the silicon melt after the feeding is completed and melted, so as to control the resistivity of the single crystal rod.

5. A method for controlling the resistivity of silicon rod, characterized in that, The control method includes: After the feeding is completed and completely melted into silicon melt, measuring the resistivity of the silicon melt; Calculating the impurity concentration of the silicon melt according to the resistivity of the silicon melt; Determining the amount of dopant to be added according to the impurity concentration of the silicon melt, so as to control the resistivity of the single crystal rod.

6. A measuring device for the resistivity of silicon liquid, characterized in that, The measurement device includes: a resistance measuring instrument, a telescopic mechanism, and at least two probes; wherein, At least two of the probes are respectively electrically connected to both ends of the resistance measuring instrument; The telescopic mechanism is connected to the probe, and the telescopic mechanism is used to drive the probe to extend into the silicon melt to form a resistance measurement circuit; The resistance measuring instrument is used to measure the total resistance value between the probes, so as to calculate the melt resistance of the silicon melt between the probes according to the total resistance value, and determine the resistivity of the silicon melt according to the melt resistance.

7. The measuring device according to claim 6, characterized in that, The measurement device further includes: at least two electrical connecting rods; wherein, One of the probes is connected to one of the electrical connecting rods, and the electrical connecting rod is electrically connected to the resistance measuring instrument through a wire; The telescopic mechanism is connected to the electrical connecting rod.

8. The measuring device according to claim 6, characterized in that, The measurement device further includes a dynamic seal, and the dynamic seal is arranged between the electrical connecting rod and the single crystal furnace for realizing the dynamic seal between the electrical connecting rod and the single crystal furnace.

9. The measuring device according to claim 6, characterized in that, The dynamic seal is a bellows.

10. The measuring device according to claim 6, characterized in that, The material of the probe is one of silicon crystal, graphite, carbon-carbon composite material, metal tungsten molybdenum, and silicon carbide.

11. A control device for the resistivity of a silicon rod, characterized in that, The control device includes: a main furnace body, a crucible, a heater, and the measuring device according to any one of claims 6 to 10; wherein, the crucible and the heater are arranged in the main furnace body, the crucible is used for containing silicon material, and the heater is used for melting the silicon material into silicon liquid; the probe of the measuring device extends into the silicon liquid, and the measuring device is used for determining the resistivity of the silicon liquid, calculating the impurity concentration of the silicon liquid according to the resistivity of the silicon liquid, and determining the doping ratio of the dopant and the silicon-based raw material according to the impurity concentration of the silicon liquid, the resistivity of the dopant and the silicon-based raw material, and the target resistivity of the single crystal silicon rod, so as to control the resistivity of the single crystal silicon rod.

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