A crystal growth method and crystalline silicon

Abstract

This application provides a crystal growth method and crystalline silicon, relating to the field of solar photovoltaic technology. The method comprises: performing a leak test on a single crystal furnace under a first furnace pressure; adding a dopant to the single crystal furnace under a second furnace pressure; wherein the second furnace pressure is greater than the first furnace pressure; and performing a crystal pulling process after adding the dopant. This application can reduce axial concentration distribution differences of doping elements in doped single crystal silicon, improve axial resistivity uniformity of the single crystal silicon, and enhance production efficiency.

Description

Technical Field

[0001] The present application relates to the field of solar photovoltaic technology, and in particular to a crystal growth method and crystalline silicon. Background Art

[0002] At present, monocrystalline silicon is widely used in the solar photovoltaic industry.

[0003] Single crystal silicon used in the solar photovoltaic industry is typically produced using the Czochralski method. This method involves growing single crystals in a single crystal furnace through a series of steps, including melting silicon, seeding, shoulder placement, shoulder rotation, constant diameter growth, and finishing. To modify the energy level structure of silicon and improve its semiconductor properties, doping elements are typically added to the melted silicon to treat the single crystal.

[0004] However, the doped single-crystalline silicon prepared by the existing Czochralski method is prone to uneven distribution of doping elements during the growth process, resulting in a large difference in axial resistivity. As a result, the resistivity of the doped single-crystalline silicon finally grown cannot meet the requirements of actual use of photovoltaic products such as solar cells. Summary of the Invention

[0005] The present application provides a crystal growth method, which aims to improve the uniformity of doping element distribution in doped single-crystal silicon prepared by the Czochralski method and reduce the axial resistivity difference.

[0006] In a first aspect, an embodiment of the present application provides a crystal growth method, wherein the method comprises:

[0007] Conduct leak detection on the single crystal furnace under the first furnace pressure environment;

[0008] adding dopants into the single crystal furnace under a second furnace pressure environment; wherein the second furnace pressure is greater than the first furnace pressure;

[0009] After adding the dopant, the crystal pulling process is performed.

[0010] Optionally, in the crystal growth method, the first furnace pressure is less than 1 Torr.

[0011] Optionally, in the crystal growth method, the second furnace pressure is greater than 60 Torr.

[0012] Optionally, in the crystal growth method, adding a dopant into the single crystal furnace under the second furnace pressure environment includes:

[0013] Adding silicon material and dopant into the single crystal furnace under the second furnace pressure environment;

[0014] or

[0015] Adding silicon material into the single crystal furnace under the first furnace pressure environment;

[0016] After the melting is completed, dopants are added into the single crystal furnace under the second furnace pressure environment.

[0017] Optionally, in the crystal growth method, the crystal pulling step includes:

[0018] In the isodiameter growth stage, according to the actual isodiameter growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced starting from the second furnace pressure to perform Czochralski growth of the crystal.

[0019] Optionally, in the crystal growth method, according to the actual isodiametric growth length of the doped single crystal silicon, starting from the second furnace pressure, the crystal pulling furnace pressure is reduced to perform Czochralski growth of the crystal, comprising:

[0020] The pressure of the crystal pulling furnace is controlled to be 80-300 Torr at the head stage of the equal-diameter growth, and the pressure of the crystal pulling furnace is less than 100 mTorr at the tail stage of the equal-diameter growth.

[0021] Optionally, in the crystal growth method, the argon flow rate in the head stage of equal-diameter growth is greater than 200 L / min; and the argon flow rate in the tail stage of equal-diameter growth is less than 5 L / min.

[0022] Optionally, in the crystal growth method, the argon flow rate of the melt operation is 50 to 100 L / min, and the argon flow rate of the dopant addition, temperature adjustment operation, seeding, shoulder release, and shoulder rotation operations is 100 to 300 L / min.

[0023] Optionally, in the crystal growth method, before reducing the crystal pulling furnace pressure from the second furnace pressure according to the actual constant diameter growth length of the doped single crystal silicon to perform Czochralski growth, the method further comprises:

[0024] Determining a first correspondence between a crystal pulling furnace pressure and a constant-diameter growth length of the doped single silicon crystal; wherein, in the first correspondence, the crystal pulling furnace pressures corresponding to different constant-diameter growth lengths are at least partially different, so that during the constant-diameter growth stage, when the crystal is controlled by the crystal pulling furnace pressure determined by the first correspondence, the axial concentration of the doping element in the doped single silicon crystal tends to be uniform when the crystal is grown by direct pulling;

[0025] According to the actual constant diameter growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced from the second furnace pressure to perform Czochralski growth of the crystal, comprising:

[0026] When the doped single crystal silicon is in a constant diameter growth stage, obtaining an actual constant diameter growth length of the doped single crystal silicon;

[0027] determining a target crystal pulling furnace pressure corresponding to the actual constant-diameter growth length according to a first correspondence between a crystal pulling furnace pressure and a constant-diameter growth length of the doped single crystal silicon;

[0028] According to the target crystal pulling furnace pressure, the crystal Czochralski growth is controlled.

[0029] Optionally, in the crystal growth method, in the first corresponding relationship, the crystal pulling furnace pressure of the doped single crystal silicon is negatively correlated with the constant diameter growth length.

[0030] Optionally, in the crystal growth method, controlling the crystal Czochralski growth according to the target crystal pulling furnace pressure includes:

[0031] According to the target crystal pulling furnace pressure, crystal pulling process parameters are adjusted, wherein the crystal pulling process parameters include argon gas flow rate and dry pump frequency.

[0032] Optionally, before adjusting the crystal pulling process parameters according to the target crystal pulling furnace pressure, the method further includes:

[0033] Determining a second correspondence between a crystal pulling furnace pressure of the doped single crystal silicon and an argon flow rate and a dry pump frequency; wherein, when controlling Czochralski growth of the crystal according to the argon flow rate and the dry pump frequency determined by the second correspondence, the crystal pulling furnace pressure of the doped single crystal silicon is adjusted to a corresponding pressure value, and a crystal pulling rate of the doped single crystal silicon approaches a maximum value;

[0034] Adjusting crystal pulling process parameters according to the target crystal pulling furnace pressure includes:

[0035] determining a target argon flow rate and a target dry pump frequency corresponding to the target crystal pulling furnace pressure according to a second correspondence between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate and the dry pump frequency;

[0036] The Czochralski growth of the crystal is controlled according to the target argon flow rate and the target dry pump frequency.

[0037] Optionally, the crystal pulling process parameters further include heater power and crystal pulling rate;

[0038] Before adjusting the crystal pulling process parameters according to the target crystal pulling furnace pressure, the method further includes:

[0039] Determining a third correspondence between a crystal pulling furnace pressure of the doped single crystal silicon and an argon flow rate, a dry pump frequency, a heater power, and a crystal pulling rate; wherein, when controlling Czochralski growth of the crystal according to the argon flow rate, the dry pump frequency, the heater power, and the crystal pulling rate determined by the third correspondence, the crystal pulling furnace pressure of the doped single crystal silicon is adjusted to a corresponding pressure value, and the crystal pulling rate of the doped single crystal silicon approaches a maximum value;

[0040] Adjusting crystal pulling process parameters according to the target crystal pulling furnace pressure includes:

[0041] determining a target argon flow rate, a target dry pump frequency, a target heater power, and a target crystal pulling rate corresponding to the target crystal pulling furnace pressure according to a third correspondence between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate, the dry pump frequency, the heater power, and the crystal pulling rate;

[0042] The crystal Czochralski growth is controlled according to the target argon flow rate, target dry pump frequency, target heater power and target crystal pulling rate.

[0043] Optionally, in the crystal growth method, in the second corresponding relationship, the crystal pulling furnace pressure is positively correlated with the argon gas flow rate.

[0044] Optionally, in the crystal growth method, the crystal pulling step includes:

[0045] After the dopant is added and the melt is finished, a temperature adjustment operation is performed at a third furnace pressure; the third furnace pressure is less than or equal to 3 Torr;

[0046] After the temperature adjustment is completed, seeding, shoulder release, and shoulder rotation operations are performed under a fourth furnace pressure; the fourth furnace pressure is less than or equal to the third furnace pressure;

[0047] After the shoulder is turned, isodiametric growth is performed. During the isodiametric growth stage, the crystal pulling furnace pressure is lowered from the fourth furnace pressure according to the actual isodiametric growth length of the doped single crystal silicon to perform Czochralski growth.

[0048] In a second aspect, an embodiment of the present application provides crystalline silicon, which is prepared by the crystal growth method as described above.

[0049] In an embodiment of the present application, a single crystal furnace is leak-checked under a first furnace pressure environment, and dopants are added to the single crystal furnace under a second furnace pressure environment, and then the crystal pulling process can be carried out; wherein the second furnace pressure is greater than the first furnace pressure. By first performing leak-checking at a lower furnace pressure and then adding dopants at a higher furnace pressure, the higher furnace pressure can be used to prevent dopant volatilization, ensure the stability of the doping amount in the furnace, improve the head resistivity uniformity and head doping accuracy, and increase the head pulling speed. Therefore, the embodiment of the present application can reduce the difference in the axial concentration distribution of doping elements in the doped single crystal silicon, improve the axial resistivity uniformity of the single crystal silicon, and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0051] Figure 1 A flow chart showing the steps of a crystal growth method in Example 1 of the present application is shown;

[0052] Figure 2 A flow chart showing the steps of a crystal growth method in Example 2 of the present application is shown;

[0053] Figure 3 A flow chart showing the steps of a crystal growth method in Example 3 of the present application is shown;

[0054] Figure 4 A flow chart showing the steps of a crystal growth method in Example 4 of the present application is shown;

[0055] Figure 5 A schematic diagram showing a comparison of the average growth rate of a single crystal silicon rod prepared by using Example 1 of the present application and a conventional process is shown;

[0056] Figure 6 A schematic diagram showing the head resistance hit rate of the doped single crystal silicon rod grown in Example 1 of the present application and the single crystal silicon rod prepared by the conventional Czochralski method is shown. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0058] Before describing the embodiments of the present application in detail, the application scenarios of the embodiments of the present application are first introduced.

[0059] With the development of new high-efficiency solar cell structures such as PERC, the demand for P-type high-efficiency Czochralski monocrystalline silicon wafers in the crystalline silicon photovoltaic market has increased dramatically.

[0060] The existing Czochralski single crystal manufacturing method generally uses argon atmosphere reduced pressure crystal pulling. The introduction of argon gas combined with the suction force of the vacuum pump forms an argon flow reduced pressure atmosphere of approximately 10-20 Torr, which remains unchanged throughout the entire crystal pulling process.

[0061] Under these high, fixed furnace pressures, according to the principles of vacuum evaporation purification and segregation, the dopants and most impurity elements in the silicon material cannot volatilize within the furnace. As a result, the resistivity at the tail of the ingot decreases as its length increases during the crystal pulling process. This leads to significant variations in the axial resistivity of the growing ingot, limiting the length of the ingot within the effective resistivity range. Furthermore, due to the poor resistance hit rate at the head of the crystal, the rapid resistivity decay at the tail, and the short effective ingot length, this results in low single-furnace output and high overall crystal pulling costs.

[0062] Based on the above problems, an embodiment of the present application provides a crystal growth method, which aims to improve the uniformity of the distribution of doping elements in doped single crystal silicon prepared by the Czochralski method, reduce the axial resistivity difference, and avoid the problem that the axial resistivity of the doped single crystal silicon prepared by the Czochralski method is too different due to the uneven distribution of doping elements during the growth process, so that the resistivity of the doped single crystal silicon finally grown cannot meet the use requirements of actual photovoltaic products such as solar cells.

[0063] Example 1

[0064] Reference Figure 1 , Figure 1 A flow chart of the steps of a crystal growth method in Example 1 of the present application is shown. The method is applied to the Czochralski growth process of doped single crystal silicon. The method may include steps 101 to 103.

[0065] Step 101: Add silicon material into a single crystal furnace under a first furnace pressure environment.

[0066] In this step, the single crystal furnace is first vacuumed to check for leaks. Specifically, the single crystal furnace is vacuumed to a first furnace pressure, which is a relatively low furnace pressure value to ensure that the single crystal furnace can withstand the furnace pressure environment in the subsequent crystal pulling process.

[0067] Optionally, the first furnace pressure is less than 1 Torr. For example, the first furnace pressure is 0.7 Torr, 0.8 Torr or 0.9 Torr.

[0068] Step 102: Add dopants into the single crystal furnace under a second furnace pressure environment; wherein the first furnace pressure is lower than the second furnace pressure.

[0069] In this step, after the silicon material is melted, or when the silicon material is added, a dopant is added to the furnace, and the furnace pressure is controlled to be at the second furnace pressure state during the above process. The dopant can be phosphorus, arsenic, boron, gallium, etc.

[0070] The second furnace pressure is a relatively large furnace pressure value, so that the high furnace pressure can prevent the volatilization of the dopant and ensure the stability of the doping amount in the furnace.

[0071] Optionally, the second furnace pressure is greater than 60 Torr, and may be 60 to 300 Torr; for example, the second furnace pressure is 60 Torr, 100 Torr, or 300 Torr.

[0072] Optionally, during the dopant addition process, the argon flow rate is controlled to be 100-300 L / min, for example, 100 L / min, 200 L / min or 300 L / min.

[0073] Optionally, in one embodiment, the above step 102 includes step 1021 or steps 1022 to 1023:

[0074] Step 1021: Add silicon material and dopant into the single crystal furnace under a second furnace pressure environment.

[0075] In this embodiment, silicon material and dopant are added to the single crystal furnace at the same time, and the furnace pressure is controlled to be in the second furnace pressure state during the above process, which can shorten the process and material addition time.

[0076] Optionally, in another embodiment, the above step 102 includes steps 1022 to 1023:

[0077] Step 1022: Add silicon material into the single crystal furnace under the first furnace pressure environment.

[0078] In this step, after the single crystal furnace is evacuated and leak-checked, silicon material is added into the furnace, and then the material is heated, and the furnace pressure is controlled to be in the first furnace pressure state during the process.

[0079] The first furnace pressure is a relatively low furnace pressure value, so that the low furnace pressure can increase the volatilization of impurities in the furnace and improve the purity of the molten silicon.

[0080] Optionally, the argon flow rate for the melt operation is 50-100 L / min. This allows for creating a high argon flow and a low furnace pressure environment with a pressure of less than 1 Torr within the performance range of existing dry pumps. This high argon flow and low furnace pressure environment accelerates the volatilization and removal of impurities within the furnace, further improving the purity of the molten silicon. Specifically, the argon flow rate for the melt operation can be 50 L / min, 80 L / min, or 100 L / min.

[0081] Step 1023: After the melt is completed, dopants are added into the single crystal furnace under the second furnace pressure environment.

[0082] In this step, after the silicon material is added or after the silicon material is melted, dopant is added into the furnace, and the furnace pressure is controlled to be in the second furnace pressure state during the above process.

[0083] In this embodiment, silicon material is first added and melted at a lower furnace pressure of less than 1 Torr, which can increase the volatilization of impurities in the furnace and improve the purity of the molten silicon; when the dopant is added, a higher furnace pressure of more than 60 Torr is used, which can prevent the volatilization of the dopant and ensure the stability of the doping amount in the furnace, thereby improving the uniformity of the head resistivity and the accuracy of the head doping.

[0084] Optionally, during the dopant addition, temperature adjustment, seeding, shoulder release, and shoulder rotation operations, the argon flow rate is controlled to be 100-300 L / min, for example, 100 L / min, 200 L / min, or 300 L / min.

[0085] Step 103: After adding the dopant, a crystal pulling process is performed.

[0086] In this step, after the silicon material and dopant are completely melted, temperature adjustment, seeding, shoulder release, shoulder rotation and equal diameter growth operations are performed in sequence.

[0087] In an embodiment of the present application, a single crystal furnace is leak-checked under a first furnace pressure environment, and dopants are added to the single crystal furnace under a second furnace pressure environment, and then the crystal pulling process can be carried out; wherein the second furnace pressure is greater than the first furnace pressure. By first performing leak-checking at a lower furnace pressure and then adding dopants at a higher furnace pressure, the higher furnace pressure can be used to prevent dopant volatilization, ensure the stability of the doping amount in the furnace, and improve the head resistivity uniformity and head doping accuracy. At the same time, due to the high furnace pressure, the argon gas flow rate introduced is large, which can take away the crystallization latent heat of the growing crystal rod, thereby increasing the pulling speed. Therefore, the embodiment of the present application can reduce the difference in the axial concentration distribution of the doping element in the doped single crystal silicon, improve the axial resistivity uniformity of the single crystal silicon, and improve production efficiency.

[0088] An embodiment of the present application also provides crystalline silicon, which is prepared by the crystal growth method as described above.

[0089] In particular, when preparing the above-mentioned crystalline silicon, the single crystal furnace is leak-checked under a first furnace pressure environment, and dopants are added to the single crystal furnace under a second furnace pressure environment, and then the crystal pulling process can be carried out; wherein, the second furnace pressure is greater than the first furnace pressure. By first performing leak-checking at a lower furnace pressure and then adding dopants at a higher furnace pressure, the higher furnace pressure can be used to prevent dopant volatilization, ensure the stability of the doping amount in the furnace, and improve the head resistivity uniformity and head doping accuracy. At the same time, due to the high furnace pressure, the argon gas flow rate introduced is large, which can take away the crystallization latent heat of the growing crystal rod, thereby increasing the pulling speed, thereby reducing the difference in the axial concentration distribution of the doping element in the doped single crystal silicon, and making the axial resistivity uniformity of the above-mentioned doped single crystal silicon higher.

[0090] Example 2

[0091] Reference Figure 2 , Figure 2 A flow chart showing the steps of a crystal growth method in the second embodiment of the present application is shown. The method may include steps 201 to 205:

[0092] Step 201: Perform leak detection on a single crystal furnace under a first furnace pressure environment.

[0093] This step may be specifically referred to the above step 101 and will not be described in detail here.

[0094] Step 202: Add dopants into the single crystal furnace under a second furnace pressure environment; wherein the first furnace pressure is lower than the second furnace pressure.

[0095] This step may be specifically referred to the above step 102 and will not be described in detail here.

[0096] Step 203: After the shoulder is turned, isodiametric growth is performed. In the isodiametric growth stage, according to the actual isodiametric growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced from the second furnace pressure to perform Czochralski growth.

[0097] In this step, after adding the dopant, temperature adjustment, seeding, shoulder release, and shoulder rotation operations are first performed, and the furnace pressure during the temperature adjustment, seeding, shoulder release, and shoulder rotation operations in the crystal vertical pulling process is controlled to be in the second furnace pressure state; then, after the shoulder rotation is completed, equal-diameter growth is carried out, and in the equal-diameter generation stage, according to the actual equal-diameter growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced from the second furnace pressure to carry out crystal vertical pulling growth.

[0098] In this step, starting from the time when the doped single crystal silicon enters the isodiametric growth stage, the isodiametric growth length of the doped single crystal silicon is continuously monitored and obtained as the actual isodiametric growth length.

[0099] In this step, as the actual isodiametric growth length increases, the furnace pressure is gradually reduced starting from the second furnace pressure to control the Czochralski growth of the crystal, that is, a higher furnace pressure is used in the early stage of isodiametric growth, while a lower furnace pressure is used in the later stage of isodiametric growth.

[0100] Among them, during the growth of silicon crystals, impurities will continue to accumulate in the melt, making the impurity concentration in the molten silicon higher and higher, the impurity concentration at the tail of the crystal also higher and higher, the resistivity becomes larger and larger, the smaller the segregation coefficient, the greater the resistance ratio between the head and tail.

[0101] According to the principle of segregation, high furnace pressure can suppress the volatilization of doping elements under local high temperatures within the furnace, thereby improving the accuracy and uniformity of the resistance hit rate. Therefore, during the crystal pulling process, such as seeding, shoulder release, shoulder rotation, and equalizing the head diameter, using a higher furnace pressure can improve the accuracy of the crystal head resistance hit rate.

[0102] According to the principles of vacuum evaporation purification, low furnace pressure promotes the volatilization of doping elements, thereby improving crystal resistivity. Therefore, in the middle and late stages of the isodiameter process, using a lower furnace pressure can promote the volatilization of doping elements and other impurities, thereby improving the resistivity of the tail end of the crystal, enhancing silicon wafer quality, and ultimately boosting battery conversion efficiency.

[0103] Optionally, in one embodiment, the step of reducing the crystal pulling furnace pressure from the second furnace pressure to perform Czochralski growth of the crystal according to the actual constant diameter growth length of the doped single crystal silicon includes:

[0104] The crystal pulling furnace pressure in the head stage of the equal-diameter growth is controlled to be 80 to 300 Torr; the crystal pulling furnace pressure in the tail stage of the equal-diameter growth is less than 100 mTorr.

[0105] In this embodiment, a high-furnace pressure crystal pulling process of 80 to 300 Torr is adopted in the head stage of equal-diameter growth, which reduces dopant volatilization and improves the accuracy of the head resistance hit rate; while a low-furnace pressure crystal pulling process with a crystal pulling furnace pressure of less than 100 mTorr in the tail stage of equal-diameter growth can greatly increase dopant volatilization, thereby improving the tail resistivity. At the same time, the low furnace pressure can reduce the equal-diameter power and improve the power consumption of the furnace.

[0106] Optionally, in a specific embodiment, the above-mentioned equal-diameter growth head stage refers to an equal-diameter growth stage that is less than 10% of the total length of the equal-diameter part, and the equal-diameter growth tail stage refers to an equal-diameter growth stage that is greater than or equal to 50% of the total length of the equal-diameter part.

[0107] Optionally, in one embodiment, the argon flow rate in the head stage of the equal-diameter growth is set to 200-300 L / min; the argon flow rate in the tail stage of the equal-diameter growth is less than 5 L / min.

[0108] In this embodiment, the equal-diameter head adopts blast furnace pressure pulling and large argon flow, which not only improves the accuracy of the head resistance hit rate, but also can use the large argon flow to quickly remove heat, thereby greatly improving the pulling speed of the first 50% of the equal-diameter.

[0109] In the embodiment of the present application, silicon material is first added and melted at a lower furnace pressure of less than 1 Torr, which can increase the volatilization of impurities in the furnace and improve the purity of the molten silicon; a higher furnace pressure of more than 60 Torr is used in dopant addition, temperature adjustment, crystal induction, shoulder release, shoulder rotation operations and the early stage of equal-diameter growth. The higher furnace pressure can be used to prevent dopant volatilization and ensure the stability of the doping amount in the furnace, which can not only improve the head resistivity uniformity and head doping accuracy, but also because of the high furnace pressure, the argon gas flow rate introduced is large, which can take away the crystallization latent heat of the crystal rod growth, thereby increasing the head pulling speed; and using a lower furnace pressure in the middle and late stages of equal-diameter growth can promote the volatilization of dopants in the furnace in the middle and late stages of equal-diameter growth, increase the tail resistivity, and increase the equal-diameter length of the crystal. Therefore, the embodiment of the present application can reduce the difference in axial concentration distribution of doping elements in doped single crystal silicon, improve the axial resistivity uniformity of single crystal silicon, and improve production efficiency at the same time.

[0110] In practical applications, the crystal growth method provided in this application has the following specific steps:

[0111] After the single crystal furnace is evacuated, silicon material is added to the furnace and heated by a heater. During the heating process, the argon flow rate is set to 50-100 L / min and the furnace pressure is kept below 1 Torr. This is to increase the volatilization of impurities in the furnace and improve the purity of the molten silicon by using the low furnace pressure.

[0112] After the silicon material is added and melted in the furnace, dopant is added into the furnace. At this time, the argon flow rate is set to 100-300 L / min, and the pressure in the furnace is increased to 60-100 Torr. This high furnace pressure prevents the volatilization of the dopant and ensures the stability of the doping amount in the furnace.

[0113] After the silicon material and dopant are completely melted, the temperature is adjusted and the pressure in the furnace is maintained at 60-100 Torr.

[0114] After the temperature adjustment and drawing are completed, the isodiameter growth stage begins. In the initial stage of isodiameter growth, the furnace pressure is controlled at 80-100 Torr and the argon flow rate is set at 200-300 L / min. This is to improve the uniformity of the head resistivity and the accuracy of the head doping under the high furnace pressure environment. At the same time, the large argon flow rate can remove more heat, thereby increasing the head pulling speed.

[0115] As the isodiametric growth length increases, the furnace pressure is controlled to decrease gradually. After the isodiametric growth length reaches 50% of the total length of the isodiametric part, the furnace pressure is controlled to drop to less than 100mTorr and the argon flow rate is reduced to less than 5L / min, so as to utilize the low furnace pressure to promote the accelerated volatilization of doping in the furnace in the middle and late stages of the isodiametric growth, improve the tail resistivity, and increase the isodiametric length of the crystal.

[0116] That is, in the embodiment of the present application, during the process of evacuating the single crystal furnace for leak detection, adding materials, melting materials, drawing out, equalizing diameters, and finishing, different furnace pressure changes are used to improve the resistivity of the crystal head and tail, and to improve the resistivity uniformity without affecting the crystal growth rate, thereby achieving the purpose of improving production efficiency.

[0117] An embodiment of the present application further provides a doped single crystal silicon, which is prepared by the crystal growth method as described above.

[0118] Among them, because the melting is carried out at a furnace pressure of less than 1 Torr when preparing the above-mentioned doped single crystal silicon, the volatilization of impurities in the furnace can be increased and the purity of the molten silicon can be improved; a higher furnace pressure of 60 to 300 Torr is used in dopant addition, seeding, shoulder release, shoulder rotation operations and the early stage of equal-diameter growth. The higher furnace pressure can be used to prevent dopant volatilization and ensure the stability of the doping amount in the furnace; as the crystal vertical pulling growth proceeds, the furnace pressure is gradually lowered to control the saturated vapor pressure to change continuously with the equal-diameter growth length. A higher furnace pressure can be used to prevent dopant volatilization in the early stage of equal-diameter growth, and a lower furnace pressure can be used in the middle and late stages of equal-diameter growth to promote the volatilization of doping elements in the furnace, thereby reducing the difference in axial concentration distribution of doping elements in the doped single crystal silicon, so that the axial resistivity uniformity of the above-mentioned doped single crystal silicon is higher.

[0119] Example 3

[0120] Reference Figure 3, Figure 3 A flow chart of the steps of a crystal growth method in Example 3 of the present application is shown. The method may include steps 301 to 306:

[0121] Step 301, determining a first correspondence between the crystal pulling furnace pressure and the constant-diameter growth length of the doped single crystal silicon; wherein, in the first correspondence, the crystal pulling furnace pressures corresponding to different constant-diameter growth lengths are at least partially different, so that during the constant-diameter growth stage, the crystal pulling furnace pressure determined by the first correspondence controls the vertical pulling growth of the crystal, and the axial concentration of the doping element in the doped single crystal silicon tends to be uniform.

[0122] In this step, based on the law that the axial concentration distribution of the doping elements in the single crystal silicon is uneven due to the crystal pulling furnace pressure at different equal-diameter growth lengths, the crystal pulling furnace pressure that can make the saturated vapor pressure of the doping elements in the doped single crystal silicon in the equal-diameter growth stage continuously change with the equal-diameter growth of the silicon single crystal and control the axial concentration of the doping elements to be uniform is calculated in advance, that is, the above-mentioned first corresponding relationship is determined.

[0123] Optionally, in the first correspondence, the pulling furnace pressure of the doped single-crystal silicon is negatively correlated with the constant-diameter growth length. That is, in the first correspondence, the pulling furnace pressure decreases smoothly with increasing constant-diameter growth length. Adjusting the pulling furnace pressure according to the first correspondence not only achieves a uniform axial concentration of the doping element but also further improves the quality of the pulled crystal.

[0124] Optionally, in the first corresponding relationship described above, the crystal pulling furnace pressure of the doped single crystal silicon may be linearly negatively correlated, curved negatively correlated, or gradient negatively correlated to the constant diameter growth length, that is, as the constant diameter growth length increases, the crystal pulling furnace pressure gradually decreases.

[0125] Step 302: Perform leak detection on the single crystal furnace under a first furnace pressure environment.

[0126] This step may be specifically referred to the above step 101 and will not be described in detail here.

[0127] Step 303 , adding dopants into the single crystal furnace under a second furnace pressure environment; wherein the first furnace pressure is lower than the second furnace pressure.

[0128] This step may be specifically referred to the above step 102 and will not be described in detail here.

[0129] Step 304 : performing isodiametric growth after the shoulder rotation is completed, and obtaining the actual isodiametric growth length of the doped single crystal silicon when the doped single crystal silicon is in the isodiametric growth stage.

[0130] In this step, after the dopant is added, temperature adjustment, crystal induction, shoulder release, and shoulder rotation operations are performed. Then, starting from the doped single crystal silicon entering the equal-diameter growth stage, the equal-diameter growth length of the doped single crystal silicon is continuously monitored and obtained as the above-mentioned actual equal-diameter growth length.

[0131] Step 305 : determining a target crystal pulling furnace pressure corresponding to the actual constant-diameter growth length based on a first correspondence between the crystal pulling furnace pressure and the constant-diameter growth length of the doped single crystal silicon.

[0132] In this step, the first corresponding relationship specifies the crystal pulling furnace pressures corresponding to different constant diameter growth lengths. Therefore, after obtaining the actual constant diameter growth length, the corresponding crystal pulling furnace pressure, ie, the target crystal pulling furnace pressure, can be determined.

[0133] Step 306 , controlling the Czochralski growth of the crystal according to the target crystal pulling furnace pressure.

[0134] In this step, because the saturated vapor pressure of the doping element in the doped single crystal silicon continuously changes when the crystal is directly pulled and grown according to the crystal pulling furnace pressure determined by the first corresponding relationship in the equal-diameter growth stage, the axial concentration of the doping element tends to be uniform. Therefore, when the crystal is directly pulled and grown according to the above-mentioned target crystal pulling process parameters, the concentration distribution of the doping element in the single crystal silicon is less different, and the axial resistivity of the silicon crystal becomes more uniform.

[0135] Optionally, in one embodiment, the above step 306 specifically includes step 361:

[0136] Step 361 : adjusting crystal pulling process parameters according to the target crystal pulling furnace pressure, wherein the crystal pulling process parameters include argon gas flow rate and dry pump frequency.

[0137] In this embodiment, since the high argon flow rate can take away more heat, the crystal pulling rate of single crystal silicon is increased. However, due to the performance limitation of the dry pump, when it reaches the upper frequency limit, it is necessary to reduce the argon flow rate to continue to reduce the crystal pulling furnace pressure. Therefore, by adjusting the argon flow rate and the dry pump frequency, the required crystal pulling furnace pressure can be achieved within the performance range of the dry pump.

[0138] Optionally, in a specific implementation, step 3610 is included before the above step 306 , and the above step 361 includes steps 3611 to 3612 .

[0139] Step 3610, determine the second corresponding relationship between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate and the dry pump frequency; wherein, when the crystal vertical pulling growth is controlled according to the argon flow rate and the dry pump frequency determined by the second corresponding relationship, the crystal pulling furnace pressure of the doped single crystal silicon is adjusted to the corresponding pressure value, and the crystal pulling rate of the doped single crystal silicon tends to a maximum value.

[0140] In this step, a high argon flow rate removes more heat and increases the crystal pulling rate. However, when the furnace pressure remains constant, the higher the argon flow rate, the higher the required dry pump frequency. Dry pumps have an upper frequency limit due to performance limitations. That is, when the furnace pressure remains constant, the single crystal silicon pulling rate is determined by both the argon flow rate and the dry pump frequency. Therefore, based on the principle that a high argon flow rate removes more heat and increases the crystal pulling rate, combined with the dry pump's operating performance, the maximum argon flow rate for each crystal pulling furnace pressure within the dry pump's operating frequency range is determined, which is the second correspondence described above.

[0141] Step 3611: Determine a target argon flow rate and a target dry pump frequency corresponding to the target crystal pulling furnace pressure according to a second correspondence between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate and the dry pump frequency.

[0142] In this step, because the second correspondence determines the argon flow rate and dry pump frequency under each crystal pulling furnace pressure, when the target crystal pulling furnace pressure is obtained, the corresponding argon flow rate and dry pump frequency, that is, the above-mentioned target argon flow rate and target dry pump frequency, can be determined through the above-mentioned second correspondence.

[0143] Step 3612: Control the Czochralski growth of the crystal according to the target argon flow rate and target dry pump frequency.

[0144] In this step, because the second corresponding relationship determines the maximum argon flow rate that can achieve each crystal pulling furnace pressure within the dry pump operating frequency range, controlling the crystal direct pulling growth under the above-mentioned target argon flow rate and target dry pump frequency can not only achieve the target crystal pulling furnace pressure, but also perform crystal pulling at the maximum value of the crystal pulling rate, thereby improving the overall crystal pulling rate.

[0145] Optionally, in a specific embodiment, in the above second corresponding relationship, the crystal pulling furnace pressure is positively correlated with the argon flow rate, that is, as the crystal pulling furnace pressure decreases, the argon flow rate also decreases continuously, thereby effectively improving the crystal pulling rate of the crystal head.

[0146] In the above embodiment, when the doped single crystal silicon is in the isodiametric growth stage, the corresponding target crystal pulling furnace pressure is first determined according to the actual isodiametric growth length, and then the corresponding argon flow rate and dry pump frequency are determined according to the target crystal pulling furnace pressure to control the crystal direct pulling growth. This can not only achieve a smoothly reduced target crystal pulling furnace pressure to slow down the axial resistivity difference of the single crystal silicon, but also perform crystal pulling according to the maximum value of the crystal pulling rate, thereby improving the overall crystal pulling rate.

[0147] Optionally, in another embodiment, the crystal pulling process parameters further include heater power and crystal pulling rate, and step 3630 is included before step 361 , and step 361 includes steps 3621 to 3622 .

[0148] Step 3630, determining a third correspondence between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate, dry pump frequency, heater power and crystal pulling rate; wherein, when controlling the vertical pulling growth of the crystal according to the argon flow rate, dry pump frequency, heater power and crystal pulling rate determined by the third correspondence, the crystal pulling furnace pressure of the doped single crystal silicon is adjusted to a corresponding pressure value, and the crystal pulling rate of the doped single crystal silicon tends to a maximum value.

[0149] In this step, a large argon flow rate can remove more heat and increase the crystal pulling rate; while a reduced heater power can reduce heat generation, further increasing the crystal pulling rate. However, when the furnace pressure remains unchanged, the larger the argon flow rate, the higher the required dry pump frequency. The dry pump has an upper frequency limit due to performance limitations. At the same time, too low a heater power will affect the molten silicon state and the crystal pulling quality. In other words, when the furnace pressure remains unchanged, the crystal pulling rate of single crystal silicon is determined by the argon flow rate, dry pump frequency, and heater power. Therefore, based on the rule that a large argon flow rate can remove more heat and a low heater power can increase the crystal pulling rate, combined with the working performance of the dry pump, the maximum argon flow rate and minimum heater power for each crystal pulling furnace pressure within the dry pump operating frequency range are determined, which is the third corresponding relationship mentioned above.

[0150] Step 3621, based on the third correspondence between the crystal pulling furnace pressure of doped single crystal silicon and the argon flow rate, dry pump frequency, heater power and crystal pulling rate, determine the target argon flow rate, target dry pump frequency, target heater power and target crystal pulling rate corresponding to the target crystal pulling furnace pressure.

[0151] In this step, because the third correspondence determines the argon flow rate, dry pump frequency and heater power under each crystal pulling furnace pressure, when the target crystal pulling furnace pressure is obtained, the corresponding argon flow rate, dry pump frequency and heater power can be determined through the above third correspondence, that is, the above target argon flow rate, target dry pump frequency and target heater power.

[0152] Step 3622, controlling the Czochralski growth of the crystal according to the target argon flow rate, target dry pump frequency, target heater power and target crystal pulling rate.

[0153] In this step, because the third corresponding relationship determines the maximum argon flow rate and minimum heater power for each crystal pulling furnace pressure within the dry pump operating frequency range, the crystal vertical pulling growth is controlled under the above-mentioned target argon flow rate, target dry pump frequency and target heater power. Not only can the target crystal pulling furnace pressure be achieved, but crystal pulling can also be performed at the maximum value of the crystal pulling rate, thereby improving the overall crystal pulling rate.

[0154] In the above embodiment, when the doped single crystal silicon is in the isodiametric growth stage, the corresponding target crystal pulling furnace pressure is first determined according to the actual isodiametric growth length, and then the corresponding argon flow rate, dry pump frequency, heater power and crystal pulling rate are determined according to the target crystal pulling furnace pressure to control the direct pulling growth of the crystal. This can not only achieve a continuously decreasing target crystal pulling furnace pressure to slow down the axial resistivity difference of the single crystal silicon, but also perform crystal pulling according to the maximum value of the crystal pulling rate, thereby improving the overall crystal pulling rate.

[0155] Example 4

[0156] Reference Figure 4 , Figure 4 A flow chart showing the steps of a crystal growth method in the fourth embodiment of the present application is shown. The method may include steps 401 to 405:

[0157] Step 401: Perform leak detection on a single crystal furnace under a first furnace pressure environment.

[0158] This step may be specifically referred to the above step 101 and will not be described in detail here.

[0159] Step 402: Add dopants into the single crystal furnace under a second furnace pressure environment; wherein the first furnace pressure is lower than the second furnace pressure.

[0160] This step may be specifically referred to the above step 102 and will not be described in detail here.

[0161] Step 403: After the dopant is added and the melt is finished, a temperature adjustment operation is performed at a third furnace pressure; the third furnace pressure is less than or equal to 5 Torr.

[0162] In this step, by observing the melting rate of the material block in the quartz crucible in the single crystal furnace, after the silicon material and dopant are completely melted, the temperature adjustment operation is completed through seed crystal temperature testing, welding and temperature stabilization. The furnace pressure in the above process is controlled to be less than or equal to 5Torr.

[0163] Optionally, in the method provided herein, the melting operation is performed at an argon flow rate of 50 to 120 L / min and a furnace pressure of 1 Torr or less. This facilitates the high argon flow rate and low furnace pressure to accelerate the volatilization and removal of impurities in the furnace, thereby improving the purity of the molten silicon. Specifically, the argon flow rate during the melting process can be 50 L / min, 100 L / min, or 120 L / min, and the furnace pressure can be 1 Torr or 0.5 Torr.

[0164] Step 404: After the temperature adjustment is completed, seeding, shoulder release, and shoulder rotation operations are performed under a fourth furnace pressure; the fourth furnace pressure is less than or equal to the third furnace pressure.

[0165] In this step, after the temperature adjustment is completed, the crystal seeding, shoulder release and shoulder rotation operations are performed in sequence, and the furnace pressure in the above processes is controlled to be in the fourth furnace pressure state.

[0166] Among them, the fourth furnace pressure is less than or equal to the third furnace pressure, and the third furnace pressure is less than or equal to 3Torr, that is, the fourth furnace pressure is also a smaller furnace pressure value. It can not only provide an adjustable time interval for the crystallization and melting of the silicon material to prevent line breakage and increase unit yield, but also quickly enter the target low furnace pressure state in the equal diameter stage while ensuring the quality of seeding and shoulder release.

[0167] Optionally, the argon flow rate during the temperature adjustment operation and the seeding, shoulder release and shoulder rotation operations is 50 to 200 L / min.

[0168] Step 405: After the shoulder is turned, isodiametric growth is performed. During the isodiametric growth stage, the crystal pulling furnace pressure is lowered from the fourth furnace pressure according to the actual isodiametric growth length of the doped single crystal silicon to perform Czochralski growth.

[0169] In this step, starting from the time when the doped single crystal silicon enters the isodiametric growth stage, the isodiametric growth length of the doped single crystal silicon is continuously monitored and obtained as the actual isodiametric growth length.

[0170] In this step, as the actual isodiametric growth length increases, the furnace pressure is gradually reduced starting from the fourth furnace pressure to control the Czochralski growth of the crystal, that is, a lower furnace pressure is used in the early stage of isodiametric growth, and an even lower furnace pressure is used in the later stage of isodiametric growth.

[0171] Among them, during the growth of silicon crystals, impurities will continue to accumulate in the melt, making the impurity concentration in the molten silicon higher and higher, the impurity concentration at the tail of the crystal also higher and higher, the resistivity becomes larger and larger, the smaller the segregation coefficient, the greater the resistance ratio between the head and tail.

[0172] According to the principle of segregation, high furnace pressure can suppress the volatilization of doping elements at locally high temperatures within the furnace, thereby improving the accuracy and uniformity of the resistance hit rate. Therefore, during the crystal pulling process, such as seeding, shoulder release, shoulder rotation, and equalizing the head diameter, using a relatively high furnace pressure can improve the accuracy of the crystal head resistance hit rate.

[0173] In the embodiment of the present application, a low furnace pressure of less than or equal to 3 Torr is used in the temperature adjustment, crystal seeding, shoulder release, and shoulder rotation operations, so that the low furnace pressure state of equal-diameter growth can be quickly reached under stable crystal seeding-shoulder release quality; at the same time, by continuing to lower the crystal pulling furnace pressure as the equal-diameter growth length increases, the dopant volatilization can be prevented in the early stage of equal-diameter growth, and the stability of the doping amount in the furnace can be ensured, which can not only improve the head resistivity uniformity and the head doping accuracy, but also increase the head pulling speed; and using a lower furnace pressure in the middle and late stages of equal-diameter growth can promote the volatilization of dopants in the furnace in the middle and late stages of equal-diameter growth, increase the tail resistivity, and increase the equal-diameter length of the crystal. Therefore, the embodiment of the present application can reduce the difference in the axial concentration distribution of doping elements in doped single crystal silicon, improve the axial resistivity uniformity of single crystal silicon, and improve production efficiency.

[0174] The present application is described in detail below through examples.

[0175] Example 1

[0176] (1) After the single crystal furnace is evacuated, silicon material is added into the single crystal furnace and heated. The argon flow rate is set to 80 L / min, the furnace pressure is maintained at 0.8 Torr, the dry pump frequency is 50 Hz, and the heater power is 250 kW.

[0177] (2) After the silicon material is added and melted in the furnace, add the dopant gallium into the furnace, set the argon flow rate to 80L / min, maintain the furnace pressure at 80Torr, the dry pump frequency to 50Hz, and the heater power to 250Kw;

[0178] (3) After the silicon material and dopant are completely melted, start temperature adjustment and release, set the argon flow rate to 300L / min, the furnace pressure to 100Torr, the dry pump frequency to 30Hz, and the heater power to 70Kw;

[0179] (4) After the temperature adjustment and drawing are completed, the process enters the equal diameter growth stage and the crystal pulling process parameters are adjusted according to Table 1 to obtain doped single crystal silicon.

[0180] Table 1

[0181]

[0182] Under a 26-inch hot field, the single crystal silicon rod A was prepared by using Example 1 of the present application, and the single crystal silicon rod B was prepared by using the existing conventional Czochralski method. The average growth pulling speed and single equal diameter pulling ratio of the single crystal silicon rod A and the single crystal silicon rod B were statistically analyzed. The results are as follows: Figure 5 and as shown in Table 2.

[0183] pass Figure 5It can be seen that since a large argon flow rate is used in the head, a large amount of heat in the furnace can be taken away. The pulling speed of the single crystal completed in Example 1 of the present application is increased by 5 mm / h compared with the single crystal pulled by the ordinary process.

[0184] Table 2

[0185]

[0186] It can be seen from Table 2 that since a low furnace pressure is used at the tail end, the volatilization of the dopant can be promoted. Compared with the single crystal pulled by the conventional process, the pull-out ratio of the single crystal completed in Example 1 of the present application can be increased by about 18%.

[0187] The head of single crystal silicon A and the head of single crystal silicon B prepared by conventional Czochralski method were sampled and the head resistance hit rate was calculated. The results are as follows: Figure 6 shown.

[0188] pass Figure 6 It can be seen that since the head reduces doping volatilization, the head resistance hit rate accuracy of the single crystal completed in Example 1 of the present application can be improved by more than 7% compared with the single crystal pulled by the ordinary process.

[0189] It should be noted that, for the sake of simplicity, the method embodiments are described as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present application are not limited by the order of the actions described, because according to the embodiments of the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present application.

[0190] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0191] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0192] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are protected by this application.

Claims

1. A crystal growth method, characterized in that: The method comprises: Performing leak detection on the single crystal furnace under a first furnace pressure environment; wherein the first furnace pressure is less than 1 Torr; adding a dopant into the single crystal furnace under a second furnace pressure environment, wherein the second furnace pressure is greater than 60 Torr; After adding the dopant, the crystal pulling process is carried out, and the crystal pulling furnace pressure at the tail stage of the equal-diameter growth is controlled to be less than 100 mTorr.

2. The crystal growth method according to claim 1, wherein Adding dopants into the single crystal furnace under the second furnace pressure environment includes: Adding silicon material and dopant into the single crystal furnace under the second furnace pressure environment; or Adding silicon material into the single crystal furnace under the first furnace pressure environment; After the melting is completed, dopants are added into the single crystal furnace under the second furnace pressure environment.

3. The crystal growth method according to claim 1, wherein The crystal pulling process includes: After the shoulder is turned, isodiametric growth is carried out. In the isodiametric growth stage, according to the actual isodiametric growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced from the second furnace pressure to carry out direct pulling growth of the crystal.

4. The crystal growth method according to claim 3, wherein In the isodiameter growth stage, according to the actual isodiameter growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced from the second furnace pressure to perform Czochralski growth of the crystal, including: The crystal pulling furnace pressure in the head stage of equal-diameter growth is controlled to be 80 to 300 Torr.

5. The crystal growth method according to claim 4, characterized in that The argon flow rate in the head stage of the equal-diameter growth is greater than 200 L / min; the argon flow rate in the tail stage of the equal-diameter growth is less than 5 L / min.

6. The crystal growth method according to claim 3, wherein: In the isodiameter growth stage, according to the actual isodiameter growth length of the doped single crystal silicon, before starting to reduce the crystal pulling furnace pressure from the second furnace pressure to perform Czochralski growth of the crystal, the method further includes: Determining a first correspondence between a crystal pulling furnace pressure and a constant-diameter growth length of the doped single silicon crystal; wherein, in the first correspondence, the crystal pulling furnace pressures corresponding to different constant-diameter growth lengths are at least partially different, so that during the constant-diameter growth stage, when the crystal is controlled by the crystal pulling furnace pressure determined by the first correspondence, the axial concentration of the doping element in the doped single silicon crystal tends to be uniform when the crystal is grown by direct pulling; In the isodiameter growth stage, according to the actual isodiameter growth length of the doped single crystal silicon, the crystal pulling furnace pressure is reduced from the second furnace pressure to perform Czochralski growth of the crystal, including: When the doped single crystal silicon is in a constant diameter growth stage, obtaining an actual constant diameter growth length of the doped single crystal silicon; determining a target crystal pulling furnace pressure corresponding to the actual constant-diameter growth length according to a first correspondence between a crystal pulling furnace pressure and a constant-diameter growth length of the doped single crystal silicon; According to the target crystal pulling furnace pressure, the crystal Czochralski growth is controlled.

7. The crystal growth method according to claim 6, wherein: In the first corresponding relationship, the crystal pulling furnace pressure of doped single crystal silicon is negatively correlated with the constant diameter growth length.

8. The crystal growth method according to claim 6, wherein The controlling the Czochralski growth of the crystal according to the target crystal pulling furnace pressure comprises: According to the target crystal pulling furnace pressure, crystal pulling process parameters are adjusted, wherein the crystal pulling process parameters include argon gas flow rate and dry pump frequency.

9. The crystal growth method according to claim 8, wherein Before adjusting the crystal pulling process parameters according to the target crystal pulling furnace pressure, the method further includes: Determining a second correspondence between a crystal pulling furnace pressure of the doped single crystal silicon and an argon flow rate and a dry pump frequency; wherein, when controlling Czochralski growth of the crystal according to the argon flow rate and the dry pump frequency determined by the second correspondence, the crystal pulling furnace pressure of the doped single crystal silicon is adjusted to a corresponding pressure value, and a crystal pulling rate of the doped single crystal silicon approaches a maximum value; Adjusting crystal pulling process parameters according to the target crystal pulling furnace pressure includes: determining a target argon flow rate and a target dry pump frequency corresponding to the target crystal pulling furnace pressure according to a second correspondence between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate and the dry pump frequency; The Czochralski growth of the crystal is controlled according to the target argon flow rate and the target dry pump frequency.

10. The crystal growth method according to claim 8, wherein The crystal pulling process parameters also include heater power and crystal pulling rate; Before adjusting the crystal pulling process parameters according to the target crystal pulling furnace pressure, the method further includes: Determining a third correspondence between a crystal pulling furnace pressure of the doped single crystal silicon and an argon flow rate, a dry pump frequency, a heater power, and a crystal pulling rate; wherein, when controlling Czochralski growth of the crystal according to the argon flow rate, the dry pump frequency, the heater power, and the crystal pulling rate determined by the third correspondence, the crystal pulling furnace pressure of the doped single crystal silicon is adjusted to a corresponding pressure value, and the crystal pulling rate of the doped single crystal silicon approaches a maximum value; Adjusting crystal pulling process parameters according to the target crystal pulling furnace pressure includes: determining a target argon flow rate, a target dry pump frequency, a target heater power, and a target crystal pulling rate corresponding to the target crystal pulling furnace pressure according to a third correspondence between the crystal pulling furnace pressure of the doped single crystal silicon and the argon flow rate, the dry pump frequency, the heater power, and the crystal pulling rate; The crystal Czochralski growth is controlled according to the target argon flow rate, target dry pump frequency, target heater power and target crystal pulling rate.

11. The crystal growth method according to claim 9, wherein In the second corresponding relationship, the crystal pulling furnace pressure is positively correlated with the argon gas flow rate.

12. The crystal growth method according to claim 1, wherein The crystal pulling process includes: After the dopant is added and the melt is finished, a temperature adjustment operation is performed at a third furnace pressure; the third furnace pressure is less than or equal to 5 Torr; After the temperature adjustment is completed, seeding, shoulder release, and shoulder rotation operations are performed under a fourth furnace pressure; the fourth furnace pressure is less than or equal to the third furnace pressure; After the shoulder is turned, isodiametric growth is performed. During the isodiametric growth stage, the crystal pulling furnace pressure is lowered from the fourth furnace pressure according to the actual isodiametric growth length of the doped single crystal silicon to perform Czochralski growth.

13. A crystalline silicon, characterized in that: Prepared by the crystal growth method according to any one of claims 1 to 12.

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