A crystal pulling furnace device and a crystal pulling method

Abstract

The present application relates to the field of crystal processing, and specifically to a crystal pulling furnace device, the device comprising: a furnace body, in which a crucible for accommodating molten silicon is arranged; a magnetic field component, which is arranged outside the furnace body and is used to generate a horizontal magnetic field passing through the crucible and the molten silicon; a driving member, which is arranged outside the furnace body and is used to drive the magnetic field component to rotate so that the horizontal magnetic field rotates around the vertical axis of the furnace body. The present application can make all parts of the molten silicon receive the same magnetic field suppression effect, thereby achieving the effect of improving the stability of the crystal and ensuring the quality of the crystal.

Description

Technical Field

[0001] The present application relates to the technical field of crystal processing, and in particular to a crystal pulling furnace device and a crystal pulling method. Background Art

[0002] At present, with the development of large-size single crystal silicon, magnetic field plays an important role in the growth process of single crystal silicon. By applying a magnetic field to the silicon melt, the purpose of increasing viscosity can be achieved, which will inhibit natural convection, reduce the fluctuation of crystal growth rate, and improve the uniformity of the crystal.

[0003] In the related art, during the single crystal growth process, the magnetic field is usually kept fixed at a certain position, the magnetic field is loaded to the set value, and then the magnetic field is turned off after the end. However, no matter what type of horizontal magnetic field is used, it cannot be guaranteed that the magnetic field is centrally symmetrical as a whole during use. Under the condition of a fixed magnetic field, the internal flow of the melt is not distributed in the center, but due to the limitation of the magnetic field distribution, the internal flow asymmetry cannot be completely eliminated, which will lead to a decrease in crystal quality. Summary of the invention

[0004] The present application is proposed to solve the above-mentioned problems. According to one aspect of the present application, a crystal pulling furnace device is provided, comprising: a furnace body, in which a crucible for accommodating molten silicon is provided; a magnetic field component, which is arranged outside the furnace body and is used to generate a horizontal magnetic field passing through the crucible and the molten silicon; and a driving member, which is arranged outside the furnace body and is used to drive the magnetic field component to rotate so that the horizontal magnetic field rotates around the vertical axis of the furnace body.

[0005] Exemplarily, it also includes a magnetic field base, which is arranged outside the furnace body, and the magnetic field component is arranged on the magnetic field base. The driving member is connected to the magnetic field base to drive the magnetic field base and the magnetic field component to rotate.

[0006] Exemplarily, the driving member includes a driving motor, and the crystal pulling furnace device further includes a control module, which is electrically connected to the driving motor and is used to send a control signal to the driving motor to control the rotation speed of the magnetic field component.

[0007] Exemplarily, the crucible is rotatably disposed in the furnace body, a vertical center line of the crucible coincides with a rotation center line of the magnetic field component, and the crucible and the magnetic field component rotate in opposite directions.

[0008] Exemplarily, the crucible has a rotation speed of 0-10 rpm.

[0009] Exemplarily, the rotation speed of the magnetic field component is 1-5 rpm.

[0010] Exemplarily, the strength of the horizontal magnetic field generated by the magnetic field component is 1000-4000 Gauss.

[0011] Exemplarily, the rotation speed of the Czochralski crystal generated from the silicon melt in the crucible is 5-20 rpm.

[0012] Exemplarily, an inert gas is introduced into the furnace body, the pressure of the inert gas is 10-100 Torr, and the flow rate of the inert gas is 50-200 L / min.

[0013] According to another aspect of the present application, a crystal pulling method is provided, the method comprising: providing a furnace body, wherein a crucible in the furnace body contains molten silicon; forming a horizontal magnetic field passing through the crucible and the molten silicon by a magnetic field component, wherein the magnetic field component is arranged outside the furnace body; during the crystal pulling process, driving the magnetic field component by a driving member, so that the horizontal magnetic field formed by the magnetic field component rotates around the vertical axis of the furnace body.

[0014] According to a crystal pulling furnace device and a crystal pulling method in the present application, a horizontal magnetic field is applied to the silicon melt contained in the crucible of the furnace body through a magnetic field component. The magnetic field component can be driven by the structure of a driving part. The magnetic field component is driven to rotate during the crystal growth process, so that the rotating magnetic field can present dynamic central symmetry. When the silicon melt flows, each part can cut the horizontal magnetic field more evenly, so that each part of the silicon melt is subject to the same magnetic field suppression effect, thereby improving the stability of the crystal and ensuring the quality of the crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0016] Figure 1 A schematic structural diagram of a crystal pulling furnace device in an embodiment of the present application is shown.

[0017] Figure 2 A schematic diagram of a magnetic field component in an embodiment of the present application is shown.

[0018] Figure 3(a)-Figure 3(b) A schematic diagram showing a horizontal magnetic field and a silicon melt.

[0019] Figure 4(a)-Figure 4(b) A schematic diagram of a crystal cut is shown.

[0020] Figure 5A flow chart of a crystal pulling method in an embodiment of the present application is shown.

[0021] Figure numerals: 1. furnace body; 2. magnetic field component; 3. crucible; 31. silicon melt; 32. crystal; 4. magnetic field base; 41. driving part; 5. heater. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0023] like Figure 1 As shown, an embodiment of the present application provides a crystal pulling furnace device, including a furnace body 1, a magnetic field component 2 and a driving component 41.

[0024] The furnace body 1 is provided with a crucible 3 for containing silicon melt 31. The magnetic field component 2 is arranged outside the furnace body 1, and is used to generate a horizontal magnetic field passing through the crucible 3 and the silicon melt 31. The driving member 41 is arranged outside the furnace body 1, and is used to drive the magnetic field component 2 to rotate, so that the horizontal magnetic field rotates around the vertical axis of the furnace body 1.

[0025] A crystal pulling furnace device in an embodiment of the present application applies a horizontal magnetic field to the silicon melt 31 contained in the crucible 3 of the furnace body 1 through the magnetic field component 2. The magnetic field component 2 can be driven by the structure of the driving part 41. The magnetic field component 2 is driven to rotate during the growth of the crystal 32, so that the rotating magnetic field can present dynamic central symmetry. When the silicon melt 31 flows, each part can cut the horizontal magnetic field more evenly, so that each part of the silicon melt 31 is subject to the same magnetic field suppression effect, thereby improving the stability of the crystal 32 and ensuring the quality of the crystal 32.

[0026] Exemplarily, the silicon melt 31 in the embodiment of the present application is a polycrystalline silicon material, and the silicon melt 31 is doped with dopants, specifically including P, B, As, etc., and the available resistivity of the single crystal silicon rod can be increased by adding N-type dopants (such as phosphorus, etc.) or P-type doping (such as boron, etc.). The available range of resistivity should be between the target resistivity lower limit and the target resistivity upper limit. By doping N-type dopants or P-type dopants, the available range of resistivity can be effectively improved, so that when preparing a higher size of crystal rods, the resistivity requirements can also be met. Because different dopants have different effects on crystals, it is necessary to select a suitable dopant according to specific needs in practical applications, and the embodiment of the present application does not limit this.

[0027] Exemplarily, the crucible 3 is rotatably installed in the furnace body 1, and the vertical center line of the crucible 3 coincides with the rotation center line of the magnetic field component 2. In some embodiments, the vertical center line of the crucible 3, the rotation center line of the magnetic field component 2, and the vertical center line of the furnace body 1 coincide. When the crucible 3 rotates, the silicon melt 31 in the crucible 3 will be driven to rotate, and the convection speed of the molten silicon material will be changed during the rotation process, thereby controlling the oxygen content. Among them, the crucible 3 in the embodiment of the present application can adopt a quartz crucible 3, and the rotation direction of the crucible 3 is opposite to the rotation direction of the magnetic field component 2. When the magnetic field and the crucible 3 are both rotating, the silicon melt 31 in the crucible 3 can pass through the magnetic flux lines of the horizontal magnetic field more evenly, so that the magnetic field can achieve the best effect of suppressing natural convection on the crystal 32, reduce the fluctuation of the growth rate of the crystal 32, and further improve the uniformity of the crystal 32.

[0028] Exemplarily, a heater 5 is further provided in the furnace body 1 . The heater 5 is located outside the crucible 3 . When the heater 5 is working, the silicon melt 31 in the crucible 3 can be heated. The heater 5 can be an electric heater 5 .

[0029] Please refer to Figure 1 and Figure 2 Exemplarily, the crystal pulling furnace device further includes a magnetic field base 4, which is located outside the furnace body 1 and is arranged at the bottom of the magnetic field component 2, and the magnetic field component 2 is installed on the upper surface of the magnetic field base 4. The vertical center line of the magnetic field base 4 coincides with the vertical center line of the furnace body 1, and when the magnetic field base 4 rotates, the magnetic field component 2 can be driven to rotate. The driving member 41 is installed on the magnetic field base 4, and when the driving member 41 drives the magnetic field base 4, the magnetic field base 4 and the magnetic field component 2 will rotate, thereby realizing the driving of the magnetic field component 2.

[0030] like Figure 2 As shown, it is a schematic diagram of the magnetic field component 2 in the present application. The magnetic field component 2 is arranged on the magnetic field base 4. The magnetic field component 2 continuously generates a horizontal magnetic field. When the base drives the magnetic field component 2 to rotate, the horizontal magnetic field will rotate. As the horizontal magnetic field rotates, the entire magnetic field becomes a horizontal magnetic field that is symmetrical around the center of the crucible 3. Compared with a horizontal magnetic field that does not rotate, the magnetic field in the present application can act more evenly on various parts of the silicon melt 31.

[0031] Exemplarily, the driving member 41 is a driving motor, and the output shaft of the driving motor is connected to the magnetic field base 4. When the driving motor is working, it drives the magnetic field base 4 and the magnetic field component 2 to rotate, so that the horizontal magnetic field rotates around the center line of the furnace body 1, forming a centrally symmetrical horizontal magnetic field, thereby achieving a better suppression effect on the crystal 32.

[0032] The crystal pulling furnace device also includes a control module. In some embodiments, the control module is a PLC. The PLC is electrically connected to the drive motor to control the drive motor. The control module sends a control signal to the drive motor so as to control the rotation speed of the drive motor and the magnetic field component 2. The control signal includes the setting parameters of the drive motor, and the setting parameters include at least the setting speed of the drive motor. The drive motor rotates based on the setting parameters. In addition, the drive motor also feeds back the current actual speed to the PLC to determine whether the actual speed is deviated by the PLC, so as to facilitate real-time adjustment. In some embodiments, the difference between the actual speed of the drive motor and the setting parameters (i.e., the rotation accuracy) does not exceed 0.05 revolutions per minute.

[0033] Please refer to FIG3, which is a top view of the silicon melt 31 and the horizontal magnetic field in the present application. FIG3(a) is a schematic diagram of the magnetic field not rotating, and FIG3(b) is a schematic diagram of the magnetic field rotating. The bent arrows indicate the rotation direction of the crucible 3 and the silicon melt 31. As shown in FIG3(a), when the crucible 3 and the silicon melt 31 rotate, and the magnetic field component 2 is fixed and does not rotate, the rotation of the crucible 3 will drive the silicon melt 31 to rotate, and the horizontal magnetic field suppression effect at each position in the silicon melt 31 will be different. As shown in FIG3(a), the flow direction of the solution at positions A and C is perpendicular to the magnetic flux lines (the dotted line part in the figure), and the suppression effect is the greatest. The flow direction of the solution at positions B and D is parallel to the magnetic flux lines, and the suppression effect is the smallest. In the process of the rotation of the silicon melt 31, there will always be a situation where the relative position between the flow direction and the horizontal magnetic field at each position is not the same, which makes it difficult for the horizontal magnetic field to uniformly suppress the silicon melt 31 at each position, and will also affect the quality of the finally formed Czochralski crystal 32.

[0034] As shown in FIG3(b), when the magnetic field component 2 also rotates, the magnetic flux lines of the horizontal magnetic field will also change, which is equivalent to forming a centrally symmetrical horizontal magnetic field. The relative relationship between the melt flow direction and the magnetic flux lines at positions A-D is vertical, which can be better suppressed, and the suppression effect on the silicon melt 31 at each position is more uniform, thereby ensuring the optimal crystal 32 growth conditions, improving the stability of crystal pulling, and obtaining high-quality crystals 32. The rotation speed of the magnetic field is too slow. For example, the rotation speed of the magnetic field component 2 is 1-5 rpm.

[0035] Please refer to Figure 1, exemplarily, during the crystal pulling process, the crucible 3 and the single crystal silicon rod (Czochralski crystal 32) formed by the silicon melt 31 will rotate, and the convection speed of the silicon melt 31 will also change during the rotation process, thereby controlling the oxygen content. Among them, the rotation speed of the crucible 3 is 0-10 rpm. The rotation speed of the Czochralski crystal 32 generated by the silicon melt 31 in the crucible 3 is 5-20 rpm. In addition, inert gas will be introduced during the growth of the single crystal silicon rod, and the flow rate and pressure of the inert gas will also change the convection speed of the molten silicon material and thus affect the oxygen content. Specifically, the inert gas can be argon. The pressure of the inert gas is 10-100 Torr, and the flow rate of the inert gas is 50-200 liters / minute. In addition, increasing the rotation speed of the crystal 32 is conducive to reducing the non-axisymmetry of the solid-liquid interface shape and changing the concave-convex degree of the interface shape. Increasing the rotation speed of the crucible 3 is conducive to improving the uniformity of the temperature distribution in the melt, but it will expand the radial temperature gradient in the melt. During the crystal pulling process, the stability of the crystal 32 can be further improved by controlling the rotation speeds of the crystal 32 and the crucible 3 .

[0036] Exemplarily, the strength of the horizontal magnetic field generated by the magnetic field component 2 in the embodiment of the present application is 1000-4000 Gauss. When the strength of the horizontal magnetic field is 1000-2000 Gauss, the magnetic field strength is a low magnetic field, and when the strength of the horizontal magnetic field is 3000-4000 Gauss, the magnetic field strength is a high magnetic field.

[0037] Please refer to Figures 4(a) and 4(b). Figure 4(a) is a schematic cross-sectional view of the crystal 32 when the magnetic field is not rotating. It can be seen from the figure that no matter in the state of low magnetic field (left figure) or high magnetic field (right figure), there will be uneven minority carrier lifetime on the surface of the crystal 32. The manifestation in Figure 4(a) is that the radial color of the crystal 32 is different in depth, which will affect the quality of the crystal rod finally formed. In contrast, Figure 4(b) is a schematic cross-sectional view of the crystal 32 in the state of rotating magnetic field in the embodiment of the present application. The left and right figures in Figure 4(b) are schematic diagrams in the state of low magnetic field (1000-2000 Gauss) and high magnetic field (3000-4000) respectively. It can be seen from the figure that no matter in the state of low magnetic field or high magnetic field, the surface minority carrier lifetime of the crystal 32 is more uniform. This is also because the horizontal magnetic field in the present application can be rotated, so that each part of the silicon melt 31 can be more uniformly suppressed by the magnetic field.

[0038] After obtaining the crystal silicon rod through the direct pulling method, the silicon rod is subjected to rolling, segmenting, slicing, chamfering, grinding, polishing and other mid- and late-stage processes to obtain single crystal silicon wafers that meet the requirements.

[0039] A crystal pulling furnace device in an embodiment of the present application applies a horizontal magnetic field to the silicon melt 31 contained in the crucible 3 of the furnace body 1 through the magnetic field component 2. The magnetic field component 2 can be driven by the structure of the driving part 41. The magnetic field component 2 is driven to rotate during the growth of the crystal 32, so that the rotating magnetic field can present dynamic central symmetry. When the silicon melt 31 flows, each part of the crystal 32 can cut the horizontal magnetic field more evenly, so that each part of the silicon melt 31 is subject to the same magnetic field suppression effect, thereby improving the stability of the crystal 32 and ensuring the quality of the crystal 32.

[0040] like Figure 5 As shown, the embodiment of the present application also provides a crystal pulling method, which uses the above-mentioned crystal pulling furnace device to pull crystals, including the following steps:

[0041] S510, providing a furnace body, wherein a crucible in the furnace body contains molten silicon.

[0042] S520, forming a horizontal magnetic field passing through the crucible and the silicon melt by means of a magnetic field component, wherein the magnetic field component is arranged outside the furnace body.

[0043] S530. During the crystal pulling process, the magnetic field component is driven by a driving member so that the horizontal magnetic field formed by the magnetic field component rotates around the vertical axis of the furnace body.

[0044] Exemplarily, during the crystal pulling process, the crucible also rotates, and the crucible and the magnetic field component rotate in opposite directions, the crucible rotates at a speed of 0-10 rpm, and the magnetic field component rotates at a speed of 1-5 rpm. The crucible drives the silicon melt to rotate, and the silicon melt cuts the magnetic flux lines during the rotation. During the rotation of the magnetic field component, the horizontal magnetic field also rotates, so that the horizontal magnetic field presents a centrally symmetrical state, the relative position difference between each part of the silicon melt and the magnetic flux lines is smaller, and the magnetic field suppresses each part of the silicon melt more evenly. Among them, the intensity of the horizontal magnetic field generated by the magnetic field component is 1000-4000 Gauss.

[0045] Exemplarily, the magnetic field component is mounted on the magnetic field base, and the driving of the magnetic field component is achieved by a driving motor on the magnetic field base. The driving motor is connected to the magnetic field base and drives the magnetic field base and the magnetic field component to rotate. The rotation center of the magnetic field component and the crucible coincides with the vertical center line of the furnace body. The operation of the driving motor is controlled by the PLC, and the setting parameters are sent by the PLC to control the driving motor. The driving motor works based on the set speed in the setting parameters, and the actual speed is fed back to the PLC for adjustment and control. The difference between the actual speed and the set speed of the driving motor does not exceed 0.05 rpm.

[0046] During crystal pulling, an inert gas is introduced into the furnace body, the pressure of the inert gas is 10-100 Torr, and the flow rate of the inert gas is 50-200 L / min, wherein the inert gas may be argon.

[0047] After obtaining the silicon rod through the above method, the silicon rod is subjected to the middle and later processes such as rolling, segmenting, slicing, chamfering, grinding, polishing, etc. to obtain the monocrystalline silicon wafer that meets the requirements. Because the suppression effect of the magnetic field is more uniform, the radial distribution of the obtained monocrystalline silicon wafer product is more uniform, which ensures the quality of the wafer.

[0048] A crystal pulling furnace method in an embodiment of the present application applies a horizontal magnetic field to the silicon melt contained in the crucible of the furnace body through a magnetic field component. The magnetic field component can be driven by the structure of a driving part. The magnetic field component is driven to rotate during the crystal growth process, so that the rotating magnetic field can present dynamic central symmetry. When the silicon melt flows, each part can cut the horizontal magnetic field more evenly, so that each part of the silicon melt is subject to the same magnetic field suppression effect, thereby improving the stability of the crystal and ensuring the quality of the crystal.

[0049] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0050] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0051] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0052] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0053] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0054] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A crystal pulling furnace device, characterized in that: include: A furnace body, wherein a crucible for accommodating molten silicon is arranged in the furnace body; A magnetic field component, which is arranged outside the furnace body and is used to generate a horizontal magnetic field passing through the crucible and the silicon melt; A driving member is arranged outside the furnace body, and is used for driving the magnetic field component to rotate so that the horizontal magnetic field rotates around the vertical axis of the furnace body.

2. The crystal pulling furnace device according to claim 1, characterized in that: It also includes a magnetic field base, which is arranged outside the furnace body, and the magnetic field component is arranged on the magnetic field base. The driving member is connected to the magnetic field base to drive the magnetic field base and the magnetic field component to rotate.

3. The crystal pulling furnace device according to claim 2, characterized in that: The driving member includes a driving motor, and the crystal pulling furnace device also includes a control module, which is electrically connected to the driving motor and is used to send a control signal to the driving motor to control the rotation speed of the magnetic field component.

4. The crystal pulling furnace device according to claim 1, characterized in that: The crucible is rotatably disposed in the furnace body, a vertical center line of the crucible coincides with a rotation center line of the magnetic field component, and the crucible and the magnetic field component rotate in opposite directions.

5. The crystal pulling furnace device according to claim 4, characterized in that: The rotation speed of the crucible is 0-10 rpm.

6. The crystal pulling furnace device according to claim 4, characterized in that: The rotation speed of the magnetic field component is 1-5 rpm.

7. The crystal pulling furnace device according to any one of claims 1 to 6, characterized in that: The intensity of the horizontal magnetic field generated by the magnetic field component is 1000-4000 Gauss.

8. The crystal pulling furnace device according to any one of claims 1 to 6, characterized in that: The rotation speed of the Czochralski crystal generated from the silicon melt in the crucible is 5-20 rpm.

9. The crystal pulling furnace device according to any one of claims 1 to 6, characterized in that: An inert gas is introduced into the furnace body, the pressure of the inert gas is 10-100 Torr, and the flow rate of the inert gas is 50-200 L / min.

10. A crystal pulling method, characterized in that: The method comprises: Providing a furnace body, wherein a crucible in the furnace body contains molten silicon; forming a horizontal magnetic field passing through the crucible and the silicon melt by a magnetic field component, wherein the magnetic field component is arranged outside the furnace body; During the crystal pulling process, the magnetic field component is driven by a driving member so that the horizontal magnetic field formed by the magnetic field component rotates around the vertical axis of the furnace body.

Images