A method and control system for controlling oxygen content in the center of a silicon single crystal

Abstract

The present application discloses a method and control system for controlling the central oxygen content of a silicon single crystal, which belongs to the field of semiconductor technology. In the control method of the present application, it includes: obtaining parameters for growing a silicon single crystal under a transverse magnetic field, the parameters include: the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate at the intersection of the central convection and the edge convection, the central convection is the melt convection at the center of the crucible, and the edge convection is the melt convection near the crucible wall inside the crucible; according to the parameters, the central oxygen content of the silicon single crystal is adjusted. By obtaining the four parameters of the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate, the generation, transmission and exchange of oxygen are analyzed, and the changing trend of oxygen in the silicon melt during the transmission process is more accurately analyzed to improve the product quality of the prepared silicon single crystal.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and specifically relates to a method and a control system for controlling the central oxygen content of a silicon single crystal. Background Art

[0002] Oxygen, as the most important impurity in silicon crystal besides dopants, has a great impact on the quality of silicon wafers. Appropriate oxygen concentration can increase the mechanical strength of silicon wafers, and the oxygen precipitates generated in the crystal can play the role of internal impurity absorption. The existing growth of silicon single crystals cannot effectively analyze which of the following factors is the main influencing factor: the change in the amount of dissolution on the inner wall of the quartz crucible, the change in melt convection, and the change in the diffusion degree of the gas-liquid two-phase SiO. Therefore, there are certain limitations in controlling the central oxygen content of silicon single crystals. Summary of the invention

[0003] Purpose of the invention: An embodiment of the present application provides a method for controlling the central oxygen content of a silicon single crystal, aiming to solve the technical problem of poor control of the central oxygen content of a silicon single crystal during the preparation of the silicon single crystal. Another purpose of the present application is to provide a control system for the central oxygen content of a silicon single crystal.

[0004] Technical solution: The embodiment of the present application provides a method for controlling the central oxygen content of a silicon single crystal, comprising:

[0005] Obtaining parameters for growing the silicon single crystal under a transverse magnetic field, the parameters including: oxygen content at the bottom of the crucible, oxygen content generated by the crucible wall, volatile oxygen content of the gas-liquid two-phase, and melt flow rate at the intersection of central convection and edge convection, wherein the central convection is the melt convection at the center of the crucible, and the edge convection is the melt convection at the inner wall of the crucible;

[0006] According to the parameters, the central oxygen content of the silicon single crystal is adjusted.

[0007] In some embodiments, adjusting the central oxygen content of the silicon single crystal according to the parameter includes:

[0008] Obtaining a reference value of the central oxygen content of the silicon single crystal according to the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate;

[0009] The central oxygen content of the silicon single crystal is adjusted according to the reference value.

[0010] In some embodiments, the reference value is obtained by the following formula:

[0011] ;

[0012] In the formula, M is the reference value; C(oxy) Central is the oxygen content at the bottom of the crucible; C(oxy) Edge is the oxygen content generated by the crucible wall; C(oxy) Free-melt is the volatile oxygen content of the gas-liquid two-phase; V(cj) is the value of the melt flow rate, the unit of oxygen content is ppma, and the unit of melt flow rate is m / s.

[0013] In some embodiments, the reference value satisfies: 6≤ M ≤14, the smaller the reference value is, the lower the central oxygen content of the silicon single crystal is.

[0014] In some embodiments, the oxygen content at the bottom of the crucible is the average oxygen content of the silicon melt in the area 10 mm to 13 mm from the bottom wall of the crucible, and the maximum size L of the selected area of ​​the silicon melt projected in the vertical direction is 1 The projection center of the selected area of ​​the silicon melt is located on the central axis of the crucible, satisfying 60mm≤L 1 ≤130mm.

[0015] In some embodiments, the oxygen content generated by the crucible wall is the average oxygen content of the silicon melt in the region 5 mm to 8 mm from the side wall of the crucible, and the vertical distance L between the top of the selected region of the silicon melt and the free melt surface is 2 , satisfying 10mm≤L 2 ≤15mm.

[0016] In some embodiments, the gas-liquid two-phase volatile oxygen content is an average value of the oxygen content of the silicon melt in a region of 2 mm to 5 mm from the free solution surface.

[0017] In some embodiments, the melt flow rate at the intersection of the central convection and the edge convection is the maximum value of the melt flow rate at the intersection of the central convection and the edge convection.

[0018] In some embodiments, before acquiring the parameters of growing the silicon single crystal under the transverse magnetic field, the method further includes:

[0019] The growth of silicon single crystals is simulated using simulation software, wherein the conditions for simulating the growth of silicon single crystals include one or more of the raw material feed amount, crystal pulling speed, crucible speed, the distance d between the bottom end of the guide tube and the free melt surface, the transverse magnetic field strength, the furnace pressure, and the protective gas flow rate.

[0020] Accordingly, the embodiment of the present application provides a silicon single crystal center oxygen content control system, including:

[0021] An acquisition module, the acquisition module is used to acquire parameters of the silicon single crystal grown under a transverse magnetic field, the parameters including: oxygen content at the bottom of the crucible, oxygen content generated by the crucible wall, gas-liquid two-phase volatile oxygen content, melt flow rate at the intersection of central convection and edge convection, the central convection is the melt convection at the center of the crucible, and the edge convection is the melt convection at the inner wall of the crucible;

[0022] An adjustment module is connected to the acquisition module signal and is used to adjust the central oxygen content of the silicon single crystal according to the parameter.

[0023] Beneficial effect: The method for controlling the central oxygen content of a silicon single crystal of an embodiment of the present application comprises: obtaining parameters for growing a silicon single crystal under a transverse magnetic field, the parameters comprising: the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate at the intersection of the central convection and the edge convection, the central convection being the melt convection at the center of the crucible, and the edge convection being the melt convection at the inner wall of the crucible; adjusting the central oxygen content of the silicon single crystal according to the parameters. In the method for controlling the central oxygen content of a silicon single crystal of the present application, by obtaining four parameters, namely, the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate, the generation, transmission, and exchange of oxygen are analyzed, and the changing trend of the melt oxygen during the transmission process is more accurately analyzed, thereby controlling the central oxygen content of the silicon single crystal to improve the product quality of the prepared silicon single crystal.

[0024] The silicon single crystal central oxygen content control system of the embodiment of the present application is used to implement a silicon single crystal central oxygen content control method. Therefore, the silicon single crystal central oxygen content control system can have all the technical features and beneficial effects of the above-mentioned silicon single crystal central oxygen content control method, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a schematic structural diagram of a silicon single crystal growth device in a method for controlling the central oxygen content of a silicon single crystal in an embodiment of the present application;

[0027] Figure 2 It is a schematic diagram of simulating the central convection and edge convection inside a silicon single crystal growth device in a method for controlling the central oxygen content of a silicon single crystal in an embodiment of the present application;

[0028] Figure 3Schematic diagram of the central oxygen content of the silicon single crystal at the growth interface of Examples 1 to 5 of the present application under simulation;

[0029] Figure 4 Schematic diagram of the central oxygen content of the silicon single crystal at the growth interface of Examples 1 to 5 of the present application under test;

[0030] Figure 5 It is a bar diagram of the reference value (M value) of the central oxygen content of the silicon single crystal under simulation in Examples 1 to 5 of the present application;

[0031] Figure 6 Schematic diagram of a control system for oxygen content in the center of a silicon single crystal according to an embodiment of the present application;

[0032] Figure numerals: 1. magnetic field generator; 2. quartz crucible; 3. silicon melt; 4. guide tube; 5. oxygen content value area at the bottom of the crucible; 6. oxygen content value area generated by the crucible wall; 7. gas-liquid two-phase volatile oxygen content value area; 8. position of the Gaussian surface with the strongest transverse magnetic field; 30. silicon single crystal; 31. free melt surface; 301. central convection; 302. edge convection. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0034] In the description of the present application, it should be understood that the terms "horizontal", "vertical", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application 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 therefore should not be understood as a limitation on the present application.

[0035] In the related art, the method of evaluating oxygen is mainly to evaluate it by the oxygen content in the center of the growth interface. This evaluation method can only describe the change of oxygen content in the center of the crystal growth interface in a single way, but it cannot effectively analyze which of the following factors is the main influencing factor: the change of dissolved amount in the inner wall of the quartz crucible, the change of melt convection, and the change of diffusion degree of gas-liquid two-phase SiO. Therefore, it has certain limitations in improving oxygen content. The transverse magnetic field can effectively suppress melt convection when pulling silicon single crystals by the CZ method (Czochralski Hermann Cai Zhong method), thereby improving oxygen transmission; at the same time, the magnetic field will cause the temperature of the inner wall of the quartz crucible to change, thereby affecting the generation of oxygen on the inner wall of the quartz crucible. Since the transverse magnetic field causes the change of convection morphology, the flow of silicon melt flowing through the gas-liquid two-phase may also change accordingly, which will also have a certain impact on the volatilization of SiO. When different convections intersect, oxygen transmission and exchange will also occur, which is also a major reason for the change of oxygen content in the center of the growth interface.

[0036] In view of this, an embodiment of the present application provides a method for controlling the central oxygen content of a silicon single crystal, aiming to solve at least one of the above-mentioned technical problems.

[0037] In conjunction with the accompanying drawings, a method for controlling the central oxygen content of a silicon single crystal of the present application is described in detail below. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0038] A method for controlling the central oxygen content of a silicon single crystal comprises: obtaining parameters of a silicon single crystal 30 grown under a transverse magnetic field, the parameters comprising: the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate at the intersection of the central convection 301 and the edge convection 302, wherein the central convection 301 is the melt convection at the center of the quartz crucible 2, and the edge convection 302 is the melt convection at the inner wall of the quartz crucible 2 (such as Figure 2 As shown); according to the parameters, adjust the central oxygen content of the silicon single crystal. By obtaining four parameters, namely, the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate at the intersection of the central convection 301 and the edge convection 302, the oxygen generation, transmission and exchange inside the quartz crucible 2 during the CZ method of pulling silicon single crystals 30 in the transverse magnetic field are analyzed, so as to more accurately analyze the changing trend of oxygen in the silicon melt 3 during the transmission process, thereby adjusting the central oxygen content of the silicon single crystal to improve the product quality of the prepared silicon single crystal 30. It should be understood that the transverse magnetic field is provided by a magnetic field generator 1 arranged outside the quartz crucible 2 (such as Figure 1 as shown).

[0039] In some embodiments, adjusting the central oxygen content of the silicon single crystal according to the parameters includes: obtaining a reference value of the central oxygen content of the silicon single crystal according to the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate; and adjusting the central oxygen content of the silicon single crystal according to the reference value. The reference value of the central oxygen content of the silicon single crystal is obtained through four parameters, and the reference value is used as an intermediate representation of the central oxygen content of the silicon single crystal, thereby achieving effective adjustment of the central oxygen content of the silicon single crystal, so as to ultimately improve the product quality of the prepared silicon single crystal 30.

[0040] In some embodiments, the reference value is obtained by the following formula:

[0041] ;

[0042] In the formula, M is the reference value; C(oxy) Central is the oxygen content at the bottom of the crucible; C(oxy) Edge is the oxygen content produced by the crucible wall; C(oxy) Free-melt is the volatile oxygen content of gas-liquid two-phase; V(cj) is the value of melt flow rate, the unit of oxygen content is ppma, and the unit of melt flow rate is m / s.

[0043] It should be understood that the oxygen in the silicon single crystal 30 is mainly composed of three parts: dissolution of the inner wall of the quartz crucible 2, convection transmission of the melt, and volatilization of SiO in the gas-liquid phase. The oxygen content in the silicon melt 3 mainly comes from the dissolution of the inner wall of the quartz crucible 2. The dissolution of the inner wall of the quartz crucible 2 is mainly affected by two factors: the temperature of the inner wall of the quartz crucible 2 and the laminar flow rate of the silicon melt 3 on the inner wall side. When the temperature of the inner wall of the quartz crucible 2 increases, the laminar flow rate of the silicon melt 3 on the inner wall side increases, which will cause the dissolution of the inner wall of the quartz crucible 2 to accelerate, thereby causing the oxygen content in the silicon melt 3 to increase.

[0044] The oxygen dissolved in the silicon melt 3 is also affected by the melt convection. The smaller the central vortex, the larger the edge convection 302, which means that more oxygen dissolved in the inner wall of the quartz crucible 2 will be transferred to the gas-liquid phase and volatilize into the gas phase in the form of SiO, thereby reducing the input of oxygen into the bottom of the growth interface.

[0045] The melt flow rate below the gas-liquid two phases also has a certain influence on the transmission and volatilization of oxygen. When the melt flow rate below the gas-liquid two phases is larger, it means that the oxygen content input to the growth interface will be reduced. At the same time, the volatilization rate of SiO in the gas-liquid two phases will also increase, which will lead to a decrease in the overall oxygen content at the growth interface and inside the silicon melt 3.

[0046] Ginseng Figure 1As shown, the melt convection of the present application is mainly divided into two parts: the central convection 301 and the edge convection 302. The central convection 301 presents a clockwise flow pattern, while the edge convection 302 presents a counterclockwise flow pattern. The central convection 301 mainly brings the oxygen at the bottom of the quartz crucible 2 into the central convection 301, so that part of the oxygen is transferred to the silicon single crystal 30 along with the flow of the central silicon melt 3; the edge convection 302 brings the oxygen generated by the crucible wall into the edge convection 302, and at the same time flows through the free surface of the gas-liquid two-phase melt, so that a large amount of gas-liquid two-phase volatile oxygen is volatilized in the form of SiO, and part of the oxygen that has not volatilized will continue to be transferred along with the edge convection 302 in a counterclockwise flow pattern. Oxygen in part of the edge convection 302 will undergo solute exchange and transport at the intersection of the central convection 301 and the edge convection 302. Therefore, when the melt flow rate (V(cj)) at the intersection of the central convection 301 and the edge convection 302 is greater, its solute exchange and transport capacity is stronger, which means that the central convection 301 will obtain more oxygen, thereby transporting oxygen to the silicon single crystal 30, thereby increasing the oxygen content in the silicon single crystal 30.

[0047] In some embodiments, the oxygen content at the bottom of the crucible is the average oxygen content of the silicon melt 3 in the region 10 mm to 13 mm from the bottom wall of the quartz crucible 2, and the maximum size L of the vertical projection of the selected region of the silicon melt 3 is 1 The projection center of the area selected by silicon melt 3 is located on the central axis of the crucible, satisfying 60mm≤L 1 ≤130mm. Specifically, 10mm to 13mm can be any value among 10mm, 11mm, 12mm, 13mm, or a range between any two values; L 1 It can be any value among 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm or a range between any two values. It should be understood that the oxygen content value region 5 of the crucible bottom in the silicon melt 3 is the silicon melt 3 within the interlayer of 10mm to 13mm from the bottom wall of the crucible, and the silicon melt 3 has a maximum length L in the projection plane along the vertical direction. 1 , through L 1 Further limit the value range 5 of the oxygen content at the bottom of the crucible (such as Figure 1 By limiting the oxygen content value region, the problem of a large oxygen content value at the bottom of the crucible caused by a saturated layer of dissolved oxygen on the inner wall of the quartz crucible 2 can be effectively avoided. At the same time, this region is the region where oxygen at the bottom of the crucible effectively enters the central convection 301. Therefore, the oxygen content at the bottom of the crucible can be effectively characterized.

[0048] In some embodiments, the oxygen content generated by the crucible wall is the average oxygen content of the silicon melt 3 in the region 5 mm to 8 mm from the side wall of the crucible, and the distance L between the top of the selected region and the free melt surface 31 in the vertical direction is 2 , satisfying 10mm≤L 2 ≤15mm. Specifically, 5mm to 8mm can be any value among 5mm, 6mm, 7mm, 8mm, or a range between any two values; L 2 It can be any value among 10mm, 11mm, 12mm, 13mm, 14mm, 15mm or a range value between any two values. It should be understood that the inner wall of the crucible is composed of the bottom wall of the crucible and the side wall of the crucible. In the embodiment, the side wall of the crucible is the inner wall area of ​​the crucible except the bottom wall of the crucible. The oxygen content value area 6 (such as Figure 1 The dotted line indicated by the arrow in the middle is a silicon melt 3 in the interlayer 5 mm to 8 mm away from the side wall of the crucible, and the top of the selected area of ​​the silicon melt 3 is spaced L from the free melt surface 31 in the vertical direction. 2 , through L 2 The value range 6 of the oxygen content generated by the crucible wall is further limited; the oxygen generated by the crucible wall is partially volatilized in the form of SiO in the area close to the free melt surface 31, so the range of the average value of the oxygen content generated by the crucible wall should meet the vertical distance L2 between the top of the selected area of ​​the silicon melt 3 and the free melt surface 31 to reduce the data deviation of the average value of the oxygen content. It should be understood that the free melt surface 31 is the gas-liquid interface of the silicon melt 3 in the quartz crucible 2.

[0049] In some embodiments, the gas-liquid two-phase volatile oxygen content is the average oxygen content of the silicon melt 3 in the region 2 mm to 5 mm from the free solution surface. It should be understood that the gas-liquid two-phase volatile oxygen content value range 7 (such as Figure 1 The dotted line indicated by the middle arrow is the silicon melt 3 in the interlayer 2mm to 5mm away from the free solution surface. Specifically, 2mm to 5mm can be any value among 2mm, 3mm, 4mm, 5mm or a range value between any two values.

[0050] The above average values ​​of the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, and the volatile oxygen content of the gas-liquid two-phase are all obtained by the multi-point averaging method, that is, multiple points are selected in the corresponding silicon melt 3 area to measure the oxygen content, and then the average calculation is performed. Specifically, by selecting a fixed reference point and selecting the point in the processing results after CGSim (crystal growth modeling software) simulation, the calculated oxygen content value of the point can be obtained.

[0051] In some embodiments, the melt flow rate at the intersection of the central convection 301 and the edge convection 302 is the maximum value of the melt flow rate at the intersection of the central convection 301 and the edge convection 302 .

[0052] In some embodiments, before obtaining the parameters for growing a silicon single crystal 30 under a transverse magnetic field, it also includes: using CGSim simulation software to simulate the growth of a silicon single crystal 30, simulating the use of a TDR135 furnace, a 32-inch thermal field component, and a 32-inch quartz crucible 2, and simulating the growth conditions of a silicon single crystal 30 including a raw material feed amount of 400 Kg, a crystal pulling speed of 8 rmp / min, a crucible speed of 0.1 rmp / min, a distance d between the bottom end of the guide tube 4 and the free melt surface 31 of 40 mm, a transverse magnetic field strength of 0.45 T, a furnace pressure of 30 Torr, and a protective gas flow rate of 130 slpm, one or more of which, and the protective gas may be argon.

[0053] In order to obtain different oxygen contents, simulations and experiments were performed by changing the position of the strongest Gaussian surface. Among them, in Example 1, the position 8 of the strongest Gaussian surface of the transverse magnetic field is 50 mm above the surface of the free solution; in Example 2, the position 8 of the strongest Gaussian surface of the transverse magnetic field is flush with the surface of the free solution; in Example 3, the position 8 of the strongest Gaussian surface of the transverse magnetic field is 50 mm below the surface of the free solution; in Example 4, the position 8 of the strongest Gaussian surface of the transverse magnetic field is 100 mm below the surface of the free solution; in Example 5, the position 8 of the strongest Gaussian surface of the transverse magnetic field is 180 mm below the surface of the free solution. Figure 2 As shown, according to the simulation-central oxygen content results, it can be seen that: Example 2> Example 5> Example 3> Example 1> Example 4.

[0054] The growth conditions of the silicon single crystal 30 used in the experiment are consistent with those in the simulation. Figure 3 and Figure 4 As shown, the experimental-central oxygen content results are consistent with the simulated-central oxygen content results, which can prove the accuracy of the simulated-central oxygen content results.

[0055] Specifically, in Examples 1 to 5, the oxygen content C(oxy)Central at the bottom of the quartz crucible 2, the oxygen content C(oxy)Edge generated by the wall of the quartz crucible 2, the gas-liquid two-phase volatile oxygen content C(oxy)Free-melt, and the melt flow rate V(cj) at the intersection of the central convection 301 and the edge convection 302 are shown in the following table:

[0056]

[0057] According to the above table, the initial dissolved oxygen content of the inner wall of the quartz crucible 2 (the oxygen content C(oxy)Central at the bottom of the quartz crucible 2 + the oxygen content C(oxy)Edge generated by the wall of the quartz crucible 2) is calculated. It can be seen that Example 5> Example 2> Example 3> Example 1> Example 4 (such as Figure 5 As shown). It can be clearly seen from the analysis of the M value that the V(cj) of Example 2 is significantly greater than that of Example 5, so the exchange and transmission capacity of solute oxygen at the intersection of the center and edge convection 302 is stronger, so that more oxygen will enter the center convection 301, and finally be brought into the crystal by the center convection 301, so that the oxygen content in the center of the growth interface is significantly increased and greater than that in Example 5. At the same time, it can be clearly analyzed that the main reason for the low oxygen content in Examples 3, 4 and 1 is the generation of oxygen and the low dissolved oxygen content of the inner wall of the quartz crucible 2, which leads to a relatively low oxygen content in the overall silicon melt 3, and thus a low oxygen content in the center of the growth interface.

[0058] From the comparison between the reference value M and the simulation and experimental-growth interface center oxygen content, it can be seen that when 6≤M≤14, the smaller the M value, the smaller the oxygen content in the growth interface center.

[0059] Accordingly, the embodiment of the present application provides a silicon single crystal center oxygen content control system, Figure 6 As shown, the control system includes an acquisition module and an adjustment module. The acquisition module is used to acquire parameters of growing a silicon single crystal 30 under a transverse magnetic field, and the parameters include: oxygen content at the bottom of the crucible, oxygen content generated by the crucible wall, volatile oxygen content of the gas-liquid two-phase, and melt flow rate at the intersection of the central convection 301 and the edge convection 302. The central convection 301 is the melt convection at the center of the crucible, and the edge convection 302 is the melt convection near the crucible wall inside the crucible; the adjustment module is connected to the acquisition module signal, and is used to adjust the central oxygen content of the silicon single crystal according to the parameters.

[0060] Accordingly, an embodiment of the present application provides a silicon single crystal central oxygen content control system, which is used to implement the control method of the above embodiment. Therefore, the silicon single crystal central oxygen content control system can have all the technical features and beneficial effects of the above silicon single crystal central oxygen content control method, which will not be repeated here.

[0061] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0062] The above is a detailed introduction to a silicon single crystal central oxygen content control method and control system provided in the embodiments of the present application, and the principles and implementation methods of the present application are explained using specific examples. The description of the above embodiments is only used to help understand the technical solution and core idea of ​​the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A method for controlling the central oxygen content of a silicon single crystal, characterized in that: include: Obtaining parameters for growing the silicon single crystal under a transverse magnetic field, the parameters including: oxygen content at the bottom of the crucible, oxygen content generated by the crucible wall, volatile oxygen content of the gas-liquid two-phase, and melt flow rate at the intersection of central convection and edge convection, wherein the central convection is the melt convection at the center of the crucible, and the edge convection is the melt convection at the inner wall of the crucible; According to the parameter, adjusting the central oxygen content of the silicon single crystal comprises: Obtaining a reference value of the central oxygen content of the silicon single crystal according to the oxygen content at the bottom of the crucible, the oxygen content generated by the crucible wall, the volatile oxygen content of the gas-liquid two-phase, and the melt flow rate; adjusting the central oxygen content of the silicon single crystal according to the reference value; The reference value is obtained by the following formula: Wherein, M is the reference value; C(oxy) Central is the oxygen content at the bottom of the crucible; C(oxy) Edge is the oxygen content generated by the crucible wall; C(oxy) Free-melt is the volatile oxygen content of the gas-liquid two-phase; V(cj) is the value of the melt flow rate, the unit of oxygen content is ppma, and the unit of melt flow rate is m / s; The oxygen content at the bottom of the crucible is the average oxygen content of the silicon melt in the area 10 mm to 13 mm away from the bottom wall of the crucible; The oxygen content generated by the crucible wall is the average oxygen content of the silicon melt in the area 5mm to 8mm away from the side wall of the crucible; The gas-liquid two-phase volatile oxygen content is the average oxygen content of the silicon melt in the area 2 mm to 5 mm away from the free solution surface; The average values ​​of oxygen content at the bottom of the crucible, oxygen content generated by the crucible wall, and volatile oxygen content in the gas-liquid two-phase are all calculated using the multi-point averaging method. By selecting a fixed reference point and selecting the point in the processing results after CGSim simulation, the calculated value of the oxygen content at that point can be obtained.

2. The method for controlling the central oxygen content of a silicon single crystal according to claim 1, characterized in that: The reference value satisfies: 6≤M≤14, and the smaller the reference value is, the lower the central oxygen content of the silicon single crystal is.

3. The method for controlling the central oxygen content of a silicon single crystal according to claim 1, characterized in that: The maximum size L1 of the region selected by the silicon melt projected in the vertical direction, and the projection center of the region selected by the silicon melt is located on the central axis of the crucible, satisfying 60mm≤L1≤130mm.

4. The method for controlling the central oxygen content of a silicon single crystal according to claim 1, characterized in that: A distance L2 between the top of the silicon melt selection area and the free melt surface in the vertical direction satisfies 10 mm ≤ L2 ≤ 15 mm.

5. The method for controlling the central oxygen content of a silicon single crystal according to claim 1, characterized in that: The melt flow rate at the intersection of the central convection and the edge convection is the maximum value of the melt flow rate at the intersection of the central convection and the edge convection.

6. The method for controlling the central oxygen content of a silicon single crystal according to claim 1, characterized in that: Before acquiring the parameters for growing the silicon single crystal under the transverse magnetic field, the method further includes: The growth of silicon single crystals is simulated using simulation software, wherein the conditions for simulating the growth of silicon single crystals include one or more of the raw material feed amount, crystal pulling speed, crucible speed, the distance d between the bottom end of the guide tube and the free melt surface, the transverse magnetic field strength, the furnace pressure, and the protective gas flow rate.

7. A silicon single crystal center oxygen content control system, used to implement the silicon single crystal center oxygen content control method according to any one of claims 1 to 6, characterized in that: include: An acquisition module, the acquisition module is used to acquire parameters of the silicon single crystal grown under a transverse magnetic field, the parameters including: oxygen content at the bottom of the crucible, oxygen content generated by the crucible wall, gas-liquid two-phase volatile oxygen content, melt flow rate at the intersection of central convection and edge convection, the central convection is the melt convection at the center of the crucible, and the edge convection is the melt convection at the inner wall of the crucible; An adjustment module is connected to the acquisition module signal and is used to adjust the central oxygen content of the silicon single crystal according to the parameter.

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