Crystal growth method and crystal growth apparatus

Abstract

The present application relates to a kind of crystal bar growth methods, using single crystal furnace to grow crystal bar, single crystal furnace includes the crucible for containing silicon melt, including the following steps: seed crystal is immersed in silicon melt to carry out crystal bar formation and form crystal bar, and the horizontal magnetic field of magnetic field intensity is first preset value, in the axial direction of crystal bar, the strongest gausssurface of horizontal magnetic field and the first distance of the liquid level of silicon solution in the axial direction of crystal bar is less than second preset value;Crystal bar is carried out equal diameter growth, and the tip magnetic field of magnetic field intensity is third preset value, and the zero magnetic surface of tip magnetic field is located at the R arc part of crucible.The present application also relates to a kind of crystal bar growth device.Horizontal magnetic field is applied, and silicon melt convection is inhibited, to improve the uncertainty due to the convection of silicon melt, resulting in the problem that oxygen is precipitated in melt and the oxygen immersed in crystal bar has uncertainty.Tip magnetic field is applied, and the precipitation of oxygen is promoted, and tip magnetic field and horizontal magnetic field cooperate with each other, so that oxygen is effectively and uniformly immersed in crystal bar.

Description

Technical Field

[0001] This invention relates to the field of semiconductor product manufacturing technology, and in particular to a crystal rod growth method and a crystal rod growth apparatus. Background Technology

[0002] Oxygen is a crucial indicator in evaluating the quality of crystal pulling ingots. The radial oxygen gradient (ROG) significantly impacts downstream yield. Oxygen can also form bulk microdefects (BMDs) within the wafer. These BMDs have an internal gettering effect, effectively absorbing and capturing defects on the wafer surface, creating a defect-free region near the wafer surface. This is highly beneficial for chip circuit etching and can greatly improve downstream product yield. However, crystal pulling is an extremely complex directional solidification process, its complexity primarily stemming from uncertain convection in the melt. This significant uncertainty in convection leads to uncertainty in oxygen precipitation within the melt and its infiltration into the ingot. Furthermore, this uncertain convection results in an unstable solid-liquid interface, which can disrupt the crystal pulling process. Slight fluctuations can lead to crystal defects in the ingot, while large fluctuations can cause the ingot to lose its single-crystal properties, resulting in loss of crystal. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a crystal rod growth method and a crystal rod growth apparatus, which solve the problem that the uncertainty of silicon melt convection affects the uniformity of oxygen in the crystal rod.

[0004] To achieve the above objectives, the technical solution adopted in this embodiment of the invention is: a crystal rod growth method, which uses a single crystal furnace for crystal rod growth, the single crystal furnace including a crucible for containing molten silicon, and includes the following steps:

[0005] The seed crystal is immersed in molten silicon to form a crystal rod, and a horizontal magnetic field with a magnetic field strength of a first preset value is applied. In the axial direction of the crystal rod, the first distance between the strongest Gaussian surface of the horizontal magnetic field and the surface of the silicon solution is less than a second preset value.

[0006] The crystal rod is grown to the same diameter, and a sharp magnetic field with a magnetic field strength of a third preset value is applied. The zero magnetic surface of the sharp magnetic field is located at the R-arc part of the crucible.

[0007] Optionally, the ingot growth method further includes:

[0008] The crystal rod after crystallization is shouldered, and before entering the constant diameter growth process, the strength of the horizontal magnetic field is increased from the first preset value to the fourth preset value.

[0009] Optionally, the crystal rod after seeding is shouldered, and when the diameter of the crystal rod is greater than or equal to 80% of the target constant diameter, the horizontal magnetic field strength is increased to the fourth preset value.

[0010] Optionally, the crystal rod is grown in constant diameter, and a cusp magnetic field with a third preset value of magnetic field strength is applied, wherein in the step of growing the crystal rod in constant diameter:

[0011] The strength of the horizontal magnetic field is increased from the fourth preset value to a fifth preset value while the cusp magnetic field is applied.

[0012] Optionally, the first preset value is 1100-1300 Gauss, the fourth preset value is 1450-1550 Gauss, and the fifth preset value is 2100-2300 Guass.

[0013] Optionally, the third preset value is 1400-1600 Guass.

[0014] Optionally, the crystal rod growth method further comprises:

[0015] The position of the strongest Gauss surface is adjusted so that the first distance is always less than the first preset value during the crystal pulling process.

[0016] Optionally, the crystal rod growth method further comprises:

[0017] The position of the zero magnetic surface is adjusted so that the position of the zero magnetic surface is always located at the R-arc portion of the crucible during the crystal pulling process.

[0018] The embodiment of the present application also provides a crystal rod growth device, comprising:

[0019] a furnace body;

[0020] a crucible located in the furnace body, the crucible containing a silicon melt;

[0021] a horizontal magnetic field generating structure arranged at the periphery of the furnace body and used for outputting a horizontal magnetic field to the crucible;

[0022] a cusp magnetic field generating structure arranged at the periphery of the furnace body and used for outputting a cusp magnetic field to the crucible, the cusp magnetic field generating structure being located at a side of the horizontal magnetic field generating structure away from the top of the furnace body.

[0023] Optionally, the crystal rod growth device further comprises:

[0024] a first adjusting structure used for controlling the movement of the horizontal magnetic field generating structure in the axial direction of the crystal rod, so that the distance between the strongest Gauss surface of the horizontal magnetic field and the liquid surface of the silicon melt is less than a first preset value during the crystal pulling process;

[0025] A second adjusting structure is used to control the movement of the cusp magnetic field generating structure in the axial direction of the crystal bar, so that the zero magnetic surface of the cusp magnetic field is always located at the R arc position of the crucible during the crystal pulling process.

[0026] The beneficial effects of the present application are that the horizontal magnetic field is applied in the seeding stage, and the distance between the strongest Gauss surface and the liquid surface of the silicon solution in the axial direction of the crystal bar is less than a second preset value, so as to inhibit the convection of the silicon melt, inhibit the volatilization of oxygen, improve the stability of the solid-liquid interface, and thus improve the quality of the crystal bar.

[0027] The cusp magnetic field is applied in the constant diameter stage, and the zero magnetic surface of the cusp magnetic field is located at the R arc position of the crucible, so as to promote the precipitation of oxygen, and the cusp magnetic field cooperates with the horizontal magnetic field to make the oxygen effectively and uniformly immersed into the crystal bar. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A flowchart of a crystal growth method in an embodiment of the present application is shown;

[0029] Figure 2 A schematic diagram of a crystal growth device in an embodiment of the present application is shown Figure 1 .

[0030] Figure 3 A schematic diagram of a crystal growth device in an embodiment of the present application is shown Figure 2 . DETAILED DESCRIPTION

[0031] To make the purposes, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without any creative effort belong to the scope of protection of the present disclosure.

[0032] Unless otherwise defined, technical terms or scientific terms used in the present disclosure shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first", "second", and similar terms do not denote any order, quantity, or importance, but are used to distinguish different components. Similarly, the terms "one", "a", or "the" do not denote a quantity of particular noun, but mean the existence of at least one. The terms "include", "comprise", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are used only to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0033] Reference Figures 1-3 The present embodiment provides a method for growing a crystal rod, using a single crystal furnace to grow the crystal rod, the single crystal furnace including a crucible for containing a silicon melt, comprising the following steps:

[0034] The seed crystal is immersed in the silicon melt to form a crystal rod 1, and a horizontal magnetic field with a magnetic field strength of a first preset value is applied, and in the axial direction of the crystal rod, the first distance between the strongest Gauss plane 5 of the horizontal magnetic field and the liquid surface of the silicon solution is less than a second preset value.

[0035] The crystal rod is subjected to equal diameter growth, and a cusp magnetic field with a magnetic field strength of a third preset value is applied, and the zero magnetic plane 7 of the cusp magnetic field is located at the R arc position of the crucible.

[0036] In the initial stage of crystal pulling, a horizontal magnetic field is applied, and the first distance between the strongest Gauss plane 5 (Maximum Gauss Plane, MGP) of the horizontal magnetic field and the liquid surface of the silicon solution in the axial direction of the crystal rod is less than a second preset value. The horizontal magnetic field suppresses the convection of the silicon melt and suppresses the volatilization of oxygen, thereby improving the uncertainty of the silicon melt convection, the problem of the oxygen precipitated in the melt and the oxygen immersed in the crystal rod having uncertainty, improving the stability of the solid-liquid interface, and avoiding the loss of single crystal characteristics of the crystal rod due to large fluctuations.

[0037] It should be noted that in an embodiment, the first preset value is 1100-1300 Gauss, for example, 1200 Gauss, which not only suppresses the convection of the silicon melt, but also avoids excessive magnetic field strength, which reduces the temperature in the furnace body, thereby affecting the pulling of the crystal rod, but is not limited thereto.

[0038] It should be noted that in some embodiments, the third preset value is 1400-1600 Guass, preferably, the third preset value is 1500 Guass, but not limited thereto.

[0039] It should be noted that the second preset value is 2-3 mm, but not limited thereto.

[0040] In some embodiments, in order to effectively suppress the convection of the silicon melt and improve the stability of the solid-liquid interface, the strongest Gaussian surface 5 coincides with the liquid surface of the silicon melt.

[0041] In an exemplary embodiment, the crystal bar growth method further comprises:

[0042] The shoulder of the crystal bar after seeding is performed, and before entering the constant diameter growth process, the strength of the horizontal magnetic field is increased from the first preset value to a fourth preset value.

[0043] Because the crystal pulling process conditions are different in different crystal pulling processes, the strength of the horizontal magnetic field can be adjusted according to actual needs to effectively suppress the convection of the silicon melt.

[0044] Before entering the constant diameter growth process, increasing the strength of the horizontal magnetic field from the first preset value to the fourth preset value can increase the stability of the solid-liquid interface, thereby improving the stability of the crystal bar.

[0045] In some embodiments, the fourth preset value is 1450-1550 Gauss, preferably, the fourth preset value is 1500 Guass, but not limited thereto.

[0046] It should be noted that in the above steps, as long as the strength of the horizontal magnetic field is increased from the first preset value to the fourth preset value before entering the constant diameter growth process, the specific time point at which the strength of the horizontal magnetic field is increased from the first preset value to the fourth preset value can be set according to actual needs.

[0047] In an exemplary embodiment, the shoulder of the crystal bar after seeding is performed, and when the diameter of the crystal bar is greater than or equal to 80% of the target constant diameter length, the strength of the horizontal magnetic field is increased to the fourth preset value, but not limited thereto.

[0048] In an exemplary embodiment, the constant diameter growth of the crystal bar is performed, and a cusp magnetic field with a magnetic field strength of a third preset value is applied, and in the step:

[0049] While the cusp magnetic field is applied, the strength of the horizontal magnetic field is increased from the fourth preset value to a fifth preset value.

[0050] In order to effectively inhibit the convection, the magnetic field strength of the horizontal magnetic field needs to be further increased when entering the constant diameter growth stage.

[0051] For example, the fifth preset value is 2100-2300 Guass, preferably, the fifth preset value is 2200 Guass, but not limited thereto.

[0052] In a specific embodiment, the crystal growth method comprises the following steps:

[0053] The seed crystal is immersed into the silicon melt to form a crystal rod, and a horizontal magnetic field with a magnetic field strength of 1200 Guass is applied, and the strongest Gauss surface 5 of the horizontal magnetic field coincides with the liquid surface of the silicon melt.

[0054] The crystal rod after seeding is subjected to shoulder forming, and when the diameter of the crystal rod is greater than or equal to 80% of the target constant diameter length, the horizontal magnetic field strength is increased to 1500 Guass.

[0055] The crystal rod is subjected to constant diameter growth, and a cusp magnetic field (CUSP magnetic field) with a magnetic field strength of 1500 Guass is applied, the zero magnetic surface 7 (i.e. Zero Gauss Plane, ZGP) of the cusp magnetic field is located at the R-arc position of the crucible, and the strength of the horizontal magnetic field is increased to 2200 Guass.

[0056] It should be noted that the horizontal magnetic field and the cusp magnetic field do not interfere with each other, so as to avoid affecting the positions of the strongest Gauss surface 5 and the zero magnetic surface 7, thereby avoiding affecting the oxygen uniformity of the crystal rod.

[0057] In an exemplary embodiment, the crystal rod growth method further comprises:

[0058] The position of the strongest Gauss surface 5 is adjusted so that the first distance is always less than the first preset value during the crystal pulling process.

[0059] In order to ensure the inhibitory effect of the horizontal magnetic field on the convection of the silicon melt, the distance between the strongest Gauss surface 5 of the horizontal magnetic field and the liquid surface of the silicon melt in the axial direction of the crystal rod needs to be always less than the first preset value during the crystal pulling process, preferably, the distance between the strongest Gauss surface 5 of the horizontal magnetic field and the liquid surface of the silicon melt in the axial direction of the crystal rod needs to be always zero, i.e. the strongest Gauss surface 5 of the horizontal magnetic field coincides with the liquid surface of the silicon melt.

[0060] In order to ensure that the strongest Gauss surface 5 coincides with the liquid surface of the silicon melt, it is necessary to determine the distance between the strongest Gauss surface 5 and the liquid surface of the silicon melt, and the process of adjusting the relative position relationship between the strongest Gauss surface 5 and the liquid surface of the silicon melt is described below.

[0061] Reference Figure 3 determining a first position of the furnace body and a second distance b of the liquid surface of the silicon solution in the axial direction of the crystal bar;

[0062] According to the second distance b, the first distance (i.e. the distance of the strongest Gauss surface 5 and the liquid surface of the silicon solution in the axial direction of the crystal bar) c is determined, c=a+d-b, a is the distance between the first end surface of the horizontal magnetic field generating structure in the axial direction of the crystal bar (the horizontal magnetic field generating structure is located at the periphery of the furnace body, and is used to provide a horizontal magnetic field to the crucible, and the end surface of the horizontal magnetic field generating structure away from the silicon solution is the first end surface) and the first position, and d is the distance between the first end surface and the strongest Gauss surface 5 in the axial direction of the crystal bar.

[0063] When c is not zero, the horizontal magnetic field generating structure is controlled to move in the axial direction of the crystal bar so that the strongest Gauss surface 5 coincides with the liquid surface of the silicon solution.

[0064] For example, when c is greater than zero, it means that the strongest Gauss surface 5 is located above the liquid surface of the silicon solution, and the horizontal magnetic field generating structure can be controlled to move in the axial direction of the crystal bar towards the silicon solution; when c is less than zero, it means that the strongest Gauss surface 5 is located below the liquid surface of the silicon solution, and the horizontal magnetic field generating structure can be controlled to move in the axial direction of the crystal bar away from the silicon solution; or, when c is greater than zero, it means that the strongest Gauss surface 5 is located below the liquid surface of the silicon solution, and the horizontal magnetic field generating structure can be controlled to move in the axial direction of the crystal bar away from the silicon solution; when c is less than zero, it means that the strongest Gauss surface 5 is located above the liquid surface of the silicon solution, and the horizontal magnetic field generating structure can be controlled to move in the axial direction of the crystal bar towards the silicon solution.

[0065] In an exemplary embodiment, the crystal bar growth method further comprises:

[0066] Adjusting the position of the zero magnetic surface 7 so that the position of the zero magnetic surface 7 is always located at the R-arc position of the crucible during the crystal pulling process.

[0067] According to different oxygen content specifications of the target crystal bar, the relative position of the zero magnetic surface 7 of the cusp magnetic field and the R-arc position or the strength of the cusp magnetic field (the greater the magnetic field strength, the more oxygen is precipitated) can be adjusted accordingly to control the effective precipitation of oxygen.

[0068] During the crystal pulling process, as the crystal bar is lifted, the crucible will be lifted. In order to ensure that the zero magnetic surface 7 of the cusp magnetic field is always located at the R-arc position, the cusp magnetic field generating structure generating the cusp magnetic field and the crucible can be made to move synchronously, i.e. as long as the initial position of the zero magnetic surface 7 is determined according to the R-arc position of the crucible.

[0069] The crucible is fixed by a crucible shaft through the bottom, the initial length of the crucible shaft is set as h, the length of the R arc part in the axial direction of the crystal bar is g, the distance between the second end surface of the sharp-point magnetic field generating structure far away from the horizontal magnetic field generating structure and the zero magnetic surface 7 is k, the distance between the bottom of the furnace body and the second end surface is j, and the zero magnetic surface 7 is located in the R arc part, and h < k + j < g + h.

[0070] Reference Figure 2 And Figure 3 ( Figure 3 The crystal bar growing method in the embodiment is realized by a crystal bar growing device, and the crystal bar growing device comprises:

[0071] a furnace body;

[0072] a crucible 9 located in the furnace body, and the crucible 9 contains a silicon melt;

[0073] a flow guide cylinder 3 located above the silicon melt;

[0074] a water cooling jacket 2 located on the side of the flow guide cylinder 3 far away from the silicon melt;

[0075] a horizontal magnetic field generating structure 4 arranged on the periphery of the furnace body and used for outputting a horizontal magnetic field to the crucible 9;

[0076] a sharp-point magnetic field generating structure 6 arranged on the periphery of the furnace body and used for outputting a sharp-point magnetic field to the crucible 9, and the sharp-point magnetic field generating structure 6 is located on the side of the horizontal magnetic field generating structure 4 far away from the top of the furnace body;

[0077] a seed crystal lifting structure used for controlling the lifting movement of a seed crystal 12 in the first direction (i.e. the axial direction of the furnace body);

[0078] a first sensing structure 13 arranged on the furnace body and located at a first position of the furnace body in the first direction, and used for sending a first signal when the seed crystal lifting structure controls the seed crystal to descend through the first position. The second position is a position flush with the silicon melt surface 8;

[0079] a second sensing structure arranged on the furnace body and used for sending a second signal when the seed crystal lifting structure controls the seed crystal to descend to the second position;

[0080] a processing structure used for obtaining a second distance b of the first position and the second position in the first direction according to the first signal and the second signal, and obtaining the first distance c according to the second distance b, wherein c = a + d - b, a is the distance between the first end surface and the first position in the first direction, and d is the distance between the first end surface and the magnetic field strongest Gauss surface 5 in the first direction.

[0081] A first adjusting structure is arranged to control the movement of the horizontal magnetic field generating structure in the axial direction of the crystal bar according to the feedback of the processing structure, so that the distance between the strongest Gauss plane 5 of the horizontal magnetic field and the liquid surface of the silicon solution is less than a first preset value during the crystal pulling process.

[0082] The first sensing structure and the second sensing structure are arranged to record information, such as time and speed, of the seed crystal when passing through the first position and the second position respectively during the descending process, so as to obtain the second distance b of the first position and the second position in the first direction, the distance a between the first end surface and the first position can be obtained by direct measurement, the position of the magnetic field generating structure is fixed, thus the strongest Gauss plane is fixed, the distance d between the first end surface and the strongest Gauss plane 5 of the magnetic field can be obtained according to the first end surface of the magnetic field generating structure, so that the distance MP between the strongest Gauss plane and the silicon melt can be obtained. The above scheme is used to obtain the distance MP between the strongest Gauss plane and the silicon melt, which improves the accuracy of the parameter and is simple and fast.

[0083] The first sensing structure can have various specific structural forms. For example, the first sensing structure comprises a pair of sensors, and the signal emitting part and the signal receiving part of the pair of sensors are located on opposite sides of the furnace body.

[0084] The positions of the signal emitting part and the signal receiving part in the first direction are both located at the first position, so that the first signal can be accurately emitted when the seed crystal passes through the first position.

[0085] The setting position of the pair of sensors can be set according to actual needs, that is, the first position can be set according to actual needs, as long as it is located above the crucible in the furnace body. For example, the furnace body comprises a main body and a cover body, and the signal emitting part and the signal receiving part are located on opposite sides of the cover body.

[0086] The pair of sensors can be arranged on the outer surface of the cover body, so that the influence on the devices in the furnace body can be avoided.

[0087] The second sensing structure can have various specific structural forms, as long as it can emit the second signal when the seed crystal contacts the liquid surface of the silicon melt. For example, the second sensing structure comprises a current detection element, one end of the current detection element is connected with the seed crystal pulling structure, the other end of the current detection element is immersed in the silicon melt, and the second sensing structure is used to emit the second signal when the seed crystal pulling structure controls the seed crystal to descend to the position where the seed crystal contacts the silicon melt.

[0088] When the seed crystal head contacts the surface of the silicon melt, the seed crystal pulling structure forms a loop with the silicon melt, the resistance changes (the current changes), the processing structure receives the second signal, and obtains the distance between the first position and the second position in the first direction according to the first signal.

[0089] It should be noted that the second sensing structure can further include a monitoring element for monitoring the change of the current detection element, and sending the second signal when the change of the current detection element is monitored, but not limited thereto.

[0090] The monitoring element can include a switching circuit and a position information acquisition structure, when the seed crystal head contacts the surface of the silicon melt, the seed crystal pulling structure forms a loop with the silicon melt, the resistance changes (the current changes), the switching circuit is closed, thereby sending a signal to the position information acquisition structure, so that the position information acquisition structure acquires the distance between the first position and the second position according to the moving speed of the seed crystal, the time required to move from the first position to the second position, and the like, but not limited thereto.

[0091] For example, the seed crystal pulling structure includes a seed crystal chuck 11 and a seed crystal 12 fixed to the seed crystal chuck 11, and one end of the current detection element is connected to the seed crystal chuck 11. For example, the crucible 9 includes a quartz crucible and a graphite crucible located outside the quartz crucible, and the bottom of the graphite crucible is supported and fixed by a crucible shaft 10.

[0092] For example, a crucible tray is arranged between the graphite crucible and the crucible shaft.

[0093] For example, the crystal bar growth device further includes:

[0094] The first adjusting structure is used to control the movement of the horizontal magnetic field generating structure in the axial direction of the crystal bar according to the feedback of the processing structure, so that the distance between the strongest gauss surface 5 of the horizontal magnetic field and the surface of the silicon solution is less than a first preset value during the crystal pulling process.

[0095] The second adjusting structure is used to control the movement of the cusp magnetic field generating structure in the axial direction of the crystal bar, so that the zero magnetic surface 7 of the cusp magnetic field is always located at the R arc portion of the crucible during the crystal pulling process.

[0096] Specifically, the second adjusting structure is used to control the synchronous lifting of the cusp magnetic field generating structure and the crucible, so that the zero magnetic surface 7 of the cusp magnetic field is always located at the R arc portion of the crucible.

[0097] It is understood that the above embodiments are only exemplary for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A method for growing a crystal ingot by using a single crystal furnace including a crucible for containing a silicon melt therein, characterized by, The method comprises the following steps: immersing a seed crystal into a silicon melt to form a crystal rod by seeding, and applying a horizontal magnetic field with a magnetic field strength of a first preset value, wherein, in the axial direction of the crystal rod, the first distance between the strongest Gauss surface of the horizontal magnetic field and the liquid surface of the silicon solution in the axial direction of the crystal rod is less than a second preset value; performing equal-diameter growth on the crystal rod, and applying a cusp magnetic field with a magnetic field strength of a third preset value, wherein the zero magnetic surface of the cusp magnetic field is located at the R-arc portion of the crucible; the horizontal magnetic field and the cusp magnetic field do not interfere with each other.

2. The method of growing a boule according to claim 1, wherein, Further comprising: performing shoulder reduction on the crystal rod after seeding, and increasing the strength of the horizontal magnetic field from the first preset value to a fourth preset value before entering the equal-diameter growth process.

3. The method of claim 2, wherein the seed crystal is a single crystal seed crystal. performing shoulder reduction on the crystal rod after seeding, and increasing the strength of the horizontal magnetic field to the fourth preset value when the diameter of the crystal rod is greater than or equal to 80% of the target equal-diameter length.

4. The method of claim 2, wherein the seed crystal is a single crystal seed crystal. In the step of performing equal-diameter growth on the crystal rod and applying a cusp magnetic field with a magnetic field strength of a third preset value: while applying the cusp magnetic field, the strength of the horizontal magnetic field is increased from the fourth preset value to a fifth preset value.

5. The method of claim 4, wherein the seed crystal is a single crystal seed crystal. The first preset value is 1100-1300 Gauss, the fourth preset value is 1450-1550 Gauss, and the fifth preset value is 2100-2300 Guass.

6. The method of growing a boule as defined in claim 1, wherein, The third preset value is 1400-1600 Guass.

7. The method of growing a boule as recited in claim 1, wherein, Further comprising: adjusting the position of the strongest Gauss surface so that the first distance is always less than the second preset value during the crystal pulling process, and the second preset value is 2-3 mm.

8. The method of growing a boule as defined in claim 1, wherein, Further comprising: adjusting the position of the zero magnetic surface so that the position of the zero magnetic surface is always located at the R-arc portion of the crucible during the crystal pulling process.

9. A crystal bar growth apparatus for implementing the crystal bar growth method according to any one of claims 1 to 8, characterized by, Comprising: a furnace body; a crucible located in the furnace body, the crucible containing a silicon melt; a horizontal magnetic field generating structure arranged at the periphery of the furnace body and used for outputting a horizontal magnetic field to the crucible; a cusp magnetic field generating structure arranged at the periphery of the furnace body and used for outputting a cusp magnetic field to the crucible, wherein the cusp magnetic field generating structure is located on the side of the horizontal magnetic field generating structure away from the top of the furnace body; Further comprising: a first adjusting structure for controlling the movement of the horizontal magnetic field generating structure in the axial direction of the crystal rod, so that the distance between the strongest Gauss surface of the horizontal magnetic field and the liquid surface of the silicon solution is less than a second preset value during the crystal pulling process; a second adjusting structure for controlling the movement of the cusp magnetic field generating structure in the axial direction of the crystal rod, so that the zero magnetic surface of the cusp magnetic field is always located at the R-arc portion of the crucible during the crystal pulling process.

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