Control device and method for crystal bar growth and crystal pulling furnace

Abstract

The invention provides a control device and method for crystal bar growth and a crystal pulling furnace, the device is applied to a single crystal furnace comprising a heater and a quartz crucible used for containing silicon melt, the device comprises an annular gas flow guide structure and an annular spraying structure, the annular gas flow guide structure is configured to be coaxially suspended above the quartz crucible, and the annular spraying structure is configured to be coaxially suspended above the quartz crucible. The heater is radially positioned between a to-be-drawn crystal bar of the single crystal furnace and the heater; the annular gas flow guide structure comprises a hollow annular cavity, and the annular cavity is used for guiding inert gas; the annular spraying structure is in fluid communication with the annular cavity, the annular spraying structure is constructed and oriented to be used for guiding inert gas from the annular cavity into a conical laminar flow air curtain, and the conical laminar flow air curtain is obliquely sprayed out towards the free liquid level.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing equipment technology, and in particular to a control device, method, and crystal pulling furnace for ingot growth. Background Technology

[0002] The Czochralski method is currently the mainstream method for producing large-diameter, high-quality single-crystal silicon ingots. In this process, high-purity polycrystalline silicon raw material is melted into a silicon melt in a quartz crucible by a heater. Subsequently, a seed crystal is immersed in the surface of the melt and slowly rotated and pulled upwards under precise temperature control. The silicon melt crystallizes at the end of the seed crystal, ultimately forming a single-crystal silicon rod with a specific crystal orientation. During the high-temperature crystal pulling process, the quartz crucible (mainly composed of SiO2) inevitably melts, continuously supplying oxygen atoms to the silicon melt. Oxygen can form oxygen precipitates (OP) during subsequent heat treatment; these precipitates have a positive effect on pinning dislocations. Excessive or uneven oxygen content can form thermal donors (TD), causing crystal resistivity drift and potentially leading to defects during device manufacturing. Therefore, precisely controlling the oxygen content and its spatial distribution uniformity in the crystal is crucial for ensuring the performance and yield of the final chip.

[0003] Traditional single crystal furnaces typically employ a simple gas circulation design. An inert gas (such as argon) is introduced through an inlet located at the top of the furnace chamber. The gas flows naturally within the chamber and finally exits through an exhaust port at the bottom of the furnace. This simple airflow design suffers from technical problems such as uneven flow field, low SiO removal efficiency, low oxygen control precision, and unstable crystal quality. Summary of the Invention

[0004] This disclosure provides a control device, method, and crystal pulling furnace for crystal rod growth; it can solve the technical problems of uneven flow field, low SiO removal efficiency, low oxygen control accuracy, and unstable crystal quality in the prior art.

[0005] The technical solution disclosed herein is implemented as follows: In a first aspect, this disclosure provides a control device for ingot growth, the device being applied in a single crystal furnace comprising a heater and a quartz crucible for containing molten silicon, comprising: An annular gas guiding structure is configured to be coaxially suspended above the quartz crucible and radially positioned between the crystal rod to be pulled in the single crystal furnace and the heater; The annular gas guiding structure includes a hollow annular cavity, which guides inert gas. An annular jet structure is fluidly connected to the annular cavity, wherein the annular jet structure is constructed and oriented to guide the inert gas from the annular cavity into a conical laminar gas curtain, the conical laminar gas curtain being ejected at an angle toward the free liquid surface.

[0006] In a second aspect, this disclosure provides a crystal pulling furnace, including the control device for crystal rod growth described in the first aspect.

[0007] Thirdly, this disclosure provides a method for controlling the growth of crystal rods, including: Crystal growth is performed using the crystal pulling furnace described in the second aspect; The angle between the annular injection structure and the annular gas guiding structure is adjusted according to the axial oxygen content in the grown crystal.

[0008] This disclosure provides a control device, method, and crystal pulling furnace for ingot growth; a stable, conical laminar gas curtain is formed by injecting inert gas from an annular jet structure. The laminar gas curtain is constructed and oriented to be ejected obliquely towards the free liquid surface, covering the melt surface and actively forcing SiO gas volatilized near the crucible wall towards the central region of the melt. This makes the oxygen partial pressure above the entire liquid surface more uniform. This improves the uniformity of radial oxygen distribution in the grown crystal. Due to the improved oxygen uniformity, the internal thermal stress of the crystal is reduced, lowering the risk of dislocation multiplication and slip, thereby improving the integrity of the crystal and the consistency of the final chip's electrical performance. Attached Figure Description

[0009] Figure 1 This is a cross-sectional view of a crystal pulling furnace provided in the related art.

[0010] Figure 2 This is a cross-sectional view of the crystal pulling furnace in which the control device for crystal rod growth is located, as provided in this disclosure.

[0011] Figure 3 A cross-sectional view of the crystal pulling furnace where another control device for crystal rod growth is located, as provided in this disclosure.

[0012] Figure 4 A cross-sectional view of a control device provided in this disclosure.

[0013] Figure 5 A top view of a control device provided in this disclosure.

[0014] Figure 6 A flowchart of a control method provided in this disclosure. Detailed Implementation

[0015] The technical solutions in this disclosure will now be clearly and completely described with reference to the accompanying drawings.

[0016] like Figure 1 As shown, a typical single crystal furnace 10 includes a furnace body 12. This furnace body 12 is typically made of high-strength, corrosion-resistant metals such as stainless steel and is equipped with a water-cooled jacket to maintain structural integrity at internal temperatures exceeding 1500°C. The primary function of the furnace body 12 is to provide a sealed environment to maintain the high-purity inert gas (e.g., high-purity argon) environment required for crystal growth and to prevent the intrusion of external air (especially oxygen and nitrogen).

[0017] Inside the furnace body 12, a heater 20 is disposed. In modern large-diameter single-crystal silicon growth, this heater 20 is typically a graphite resistance heater 20. The heater 20 is coaxially arranged around a quartz crucible 30, and its function is to melt the polysilicon raw material loaded within the quartz crucible 30 into a liquid silicon melt 40 through radiation and conduction heating. The power and structure of the heater 20 (e.g., segmented heating) are crucial for establishing and maintaining the thermal field required for crystal growth.

[0018] Inside the heater 20, a quartz crucible 30 is provided to contain the silicon melt 40. This quartz crucible 30 is made of high-purity quartz (SiO2) material. It not only serves as a container for the silicon melt 40 but also as the primary source of oxygen atoms during crystal growth. At silicon melting points above 1414°C, the inner wall of the quartz crucible 30 reacts with the liquid silicon melt 40, continuously dissolving oxygen into the melt and evaporating silicon monoxide (SiO) gas into the gas phase above the melt.

[0019] The quartz crucible 30 is typically supported by a graphite crucible 32 (or graphite base), which provides mechanical support and helps to distribute the heat from the heater 20 more evenly to the quartz crucible 30.

[0020] Polycrystalline silicon is melted under the heating of heater 20 to form a silicon melt 40. The free liquid surface of this silicon melt 40 is a critical interface for crystal growth. A seed crystal (not shown) is lowered from the top of furnace 12 via a pulling mechanism (not shown) and immersed in the center of the silicon melt 40. Subsequently, the pulling mechanism slowly pulls the seed crystal upward at a precisely controlled rate, while the seed crystal and the crucible (via a crucible rotation drive mechanism, not shown) rotate at a specific rate. The liquid silicon crystallizes at the end of the seed crystal, thereby growing a crystal ingot 50 with a specific crystal orientation to be pulled.

[0021] The furnace body 12 also includes one or more gas exhaust ports, usually located at the bottom of the furnace body, for discharging inert gases and byproducts (mainly SiO gas) generated during the growth process.

[0022] To control the atmosphere within the furnace and remove reaction products (such as SiO), an inert gas supply system 70 (e.g., a high-purity argon source, mass flow controller, valves, and piping) is configured to supply inert gas into the furnace body 12. In conventional designs, this inert gas inlet may be located at the top of the furnace body 12, leading to uneven airflow.

[0023] Based on this, this disclosure first provides a control device 100 for crystal rod growth, which is incorporated into the furnace body 12. For example... Figure 2 As shown, the control device 100 is coaxially suspended directly above the quartz crucible 30. Its radial position is precisely controlled between the ingot 50 to be pulled and the heater 20. Its vertical position is preferably located between the upper part of the silicon melt 40 and the upper part of the ingot 50 to be pulled and the heater 20.

[0024] Specifically, the control device 100 is located between the ingot 50 and the heater 20, enabling it to precisely cover the critical area of ​​the silicon melt 40 (i.e., the entire liquid surface from the center to the crucible wall) without physically interfering with the pulling of the ingot 50. The control device 100 is positioned above the free liquid surface, allowing its sprayed gas curtain to directly act on the most active areas of SiO evaporation and transport. Simultaneously, it is located between the heater 20 (at least a portion of it) and the ingot 50 to be pulled, acting as a heat shield to partially block direct thermal radiation from the heater 20 to the melt surface, which helps stabilize the liquid surface temperature and reduce thermal fluctuations.

[0025] like Figure 2 As shown, the control device 100 includes a core component, namely an annular gas guiding structure 110. The annular gas guiding structure 110 includes a hollow annular cavity 112 and an insulating felt 114.

[0026] The main structure of the annular gas guiding structure 110 is a toroidal or ring-shaped component. Its manufacturing material is capable of withstanding the extreme environment within the hot zone of the single-crystal furnace, meeting the requirements of high temperature resistance, chemical inertness, and low thermal conductivity. It maintains mechanical stability and structural integrity at temperatures exceeding 1500°C, without softening, creeping, or breaking. It must be of high purity at high temperatures and must not react with silicon vapor (Si), silicon monoxide vapor (SiO), or high-purity argon gas within the furnace to avoid contaminating the silicon melt 40. The annular gas guiding structure 110 has a low thermal conductivity to enhance its effect as a heat shield.

[0027] Specifically, the material of the annular gas guiding structure 110 may include high-purity graphite, such as isostatic graphite. This is a commonly used material for hot zone components. To prevent graphite particles from detaching or reacting to generate CO / CO2 under trace amounts of residual oxygen, graphite components typically require a silicon carbide (SiC) coating. The SiC coating provides excellent chemical inertness and high-temperature stability.

[0028] The material of the annular gas guiding structure 110 may also include refractory metals, such as molybdenum (Mo), tungsten (W), or their alloys (such as TZM). These metals have extremely high melting points and high-temperature strength. Specific material selection can also be customized according to requirements, which will not be elaborated in this example embodiment.

[0029] The annular gas guiding structure 110 includes a hollow annular cavity 112. The annular cavity 112 extends continuously in a circumferential direction of 360° inside the annular gas guiding structure 110.

[0030] The annular cavity 112 serves not only as a channel for inert gas but also as a gas pressurization chamber or manifold. Its hydrodynamic significance lies in pressure equalization, with the inert gas initially filling the entire annular cavity 112. The specific volume of the annular cavity 112 acts as a buffer and stabilizes the pressure. It transforms high-speed airflow from one or more point sources into a static pressure or low-speed flow gas source with a highly uniform circumferential pressure distribution within the annular cavity 112.

[0031] The thermal insulation felt 114 improves the uniformity of radial oxygen distribution in the crystal by stabilizing the thermal field. The stable and uniform thermal field reduces the temperature gradient on the surface of the silicon melt, which makes the effect of sweeping SiO gas using a laminar flow gas curtain more controllable and effective. The result is a more uniform oxygen content, higher crystal integrity, and fewer defects in the grown ingot.

[0032] In one embodiment, refer to Figure 3 The control device 100 also includes at least one air inlet pipe 120. The air inlet pipe 120 is coupled to the main body of the annular gas guide structure 110 and ensures that its internal passage is in fluid communication with the hollow annular cavity 112.

[0033] The inlet pipe 120 is configured to receive inert gas from the (external) inert gas supply system 70 and transfer the inert gas to the annular cavity 112.

[0034] The number of intake pipes 120 can be one or more. For example, two intake pipes 120 can be provided, which are symmetrically distributed at 180° on the annular gas guide structure 110. Alternatively, three intake pipes 120 can be provided, which are symmetrically distributed at 120°. Alternatively, a Y-shaped or T-shaped bifurcation pipe structure can be used to split a single airflow into multiple streams near the annular gas guide structure 110 before injecting them into the annular cavity 112.

[0035] By using multiple symmetrically distributed air inlets 120, inert gas can be simultaneously injected into the annular cavity 112 from multiple directions, which greatly shortens the time for the pressure in the cavity to reach equilibrium and makes the circumferential pressure distribution in the annular cavity 112 closer to the ideal uniform state, thus providing a near-perfect uniform gas source for the annular injection structure 130.

[0036] In one embodiment, refer to Figure 2 and Figure 4 The control device 100 also includes an annular injection structure 130. The annular injection structure 130 is coupled to the lower part (e.g., the bottom or inner bottom) of the annular gas guide structure 110 and is in fluid communication with the hollow annular cavity 112.

[0037] The annular injection structure 130 shapes and accelerates the pressure-equalized inert gas from the annular cavity 112, causing it to form a specific airflow pattern.

[0038] In some examples, refer to Figure 5 The annular jet structure 130 is a precision-manufactured annular slit nozzle. It has a long, narrow annular opening that is continuous in the circumference for 360°.

[0039] The geometry of the annular opening is crucial to the quality of the air curtain, particularly its laminar flow characteristics; specifically, the radial width of the annular opening. The radial width should remain highly consistent across the entire 360° circumference. For example, if the designed width is 1.0 mm, its manufacturing tolerance should be controlled within ±0.05 mm. Even localized width deviations will cause changes in gas velocity at that point, disrupting the uniformity of the air curtain. The width can range from 0.5 mm to 5 mm, depending on the required flow rate and velocity, which will not be elaborated upon here.

[0040] In some examples, the transition region from the annular cavity 112 to the annular opening is designed with a smooth, tapering profile. This allows the gas to accelerate smoothly with minimal energy loss and helps to form a stable, non-separated laminar jet at the outlet. Sharp corners or steps inside should be strictly avoided, as they are highly likely to induce turbulence.

[0041] The annular injection structure 130 is constructed and oriented to guide the inert gas from the annular cavity 112 into a conical laminar gas curtain.

[0042] Here, laminar flow is the opposite of turbulent flow. A laminar air curtain refers to a curtain in which gas molecules (or tiny fluid clusters) flow smoothly and parallelly, without interfering with or mixing with each other. Laminar flow is a stable and predictable air curtain. It avoids the situation where SiO is locally entrained in the melt due to violent stirring of the gas above the melt, or the thermal field becomes chaotic.

[0043] By controlling the width of the annular opening, the viscosity of the gas, and the injection speed, it can be ensured that the air curtain is kept within the laminar flow region.

[0044] In one embodiment, the annular injection structure 130 is detachably coupled to the annular gas guide structure 110.

[0045] Specifically, the connection method between the annular injection structure 130 and the annular gas guide structure 110 can be a snap-fit ​​connection, a threaded connection, a magnetic connection, etc., which can be customized according to user needs, and will not be elaborated here.

[0046] The control apparatus disclosed herein for ingot growth utilizes a conical gas curtain to sweep SiO. However, the optimal sweeping effect (i.e., achieving optimal radial uniformity) can vary with process conditions. For example, when growing large-diameter ingots, a larger melt area needs to be swept. The thermal field and SiO evaporation rate vary at different stages of crystal growth (e.g., seeding, shoulder formation, constant diameter). Different inert gas flow rates also affect the rigidity and penetration depth of the gas curtain.

[0047] In some example embodiments, the control device 100 for ingot growth also includes an angle adjustment mechanism. This angle adjustment mechanism is configured to adjust the angle between the annular injection structure 130 and the annular gas guide structure 110.

[0048] In one embodiment, the angle adjustment mechanism is configured to adjust the spray angle α within a range of 60 to 89 degrees relative to the horizontal plane.

[0049] For example, α=60° produces a flatter conical gas curtain with a stronger radial-inward velocity component. This setup is suitable for conditions requiring aggressive, strong sweeping (e.g., when SiO evaporation rates are extremely high). α=89° produces a steeper conical gas curtain with a weaker radial-inward velocity component. This setup is suitable for conditions requiring gentle sweeping or primarily acting as a "containment" mechanism (e.g., preventing external thermal disturbance to the melt center).

[0050] At 89°, the gas curtain still has an inward tilt angle of 1°, which ensures that the gas and the swept SiO always converge toward the central axis, rather than diffuse outward.

[0051] When the injection angle α is less than 60°, it means that the gas curtain ejected by the annular injection structure 30 is flatter, and its airflow direction is closer to horizontal, thus having a stronger radial inward velocity component. The radial inward thrust exerted by the gas curtain on the SiO gas volatilized from near the wall of the quartz crucible 30 reaches its maximum. This produces a more aggressive sweeping mode that can push high-concentration SiO vapor from the periphery of the melt 40 to the central region extremely rapidly.

[0052] A spray angle α less than 60° is suitable for special process stages where the SiO evaporation rate on the inner wall of the quartz crucible is extremely high, such as when growing ultra-large diameter crystal rods or when the melt level drops significantly in the later stages of the process. It can achieve the most efficient sweeping of volatiles. However, this setting also has significant risks. Too small an angle can easily disrupt the laminar flow state of the gas curtain, induce turbulence, thereby disturbing the thermal field and potentially re-winding SiO back into the melt. Furthermore, its excessive shear force on the surface of the silicon melt can interfere with the natural convection of the melt, potentially changing the crystal growth interface morphology and introducing defects. When the spray angle α is less than 60°, a high-precision controller and real-time monitoring system can be equipped to coordinately adjust the gas flow rate and achieve a balance between obtaining high sweeping efficiency and maintaining process stability.

[0053] The control device 100 for crystal growth also includes a controller. The controller (e.g., a dedicated microprocessor, PLC, or a software module integrated into the main control system of the single crystal furnace 10) is configured to control the angle adjustment mechanism according to the axial oxygen content in the grown crystal.

[0054] An automated closed-loop feedback control system was implemented. The controller can receive real-time or near-real-time data on the axial oxygen content in the long crystal from a sensor (e.g., a residual gas analyzer (RGA) installed at the exhaust port, or a model that indirectly estimates oxygen content through crystal resistivity). The real-time data is compared with a preset target axial oxygen content. A control algorithm is then executed, outputting a control signal to the drive angle adjustment mechanism.

[0055] For example, if the controller detects that the axial oxygen content is higher than the target value (meaning insufficient SiO removal), it may (as part of its multivariable control strategy) command the angle adjustment mechanism to reduce the angle α (e.g., from 80° to 75°) to perform a more aggressive sweep, thereby more effectively pushing SiO toward the central exhaust flow and reducing the average oxygen partial pressure above the melt.

[0056] Specifically, the injection angle (α) of the annular injection structure is the key variable for adjusting the oxygen content. There is a clear negative correlation between axial oxygen content and injection angle. When the axial oxygen content of the crystal is detected to be too high, the control system will instruct to reduce the angle α (e.g., from 80° to 70°). At this time, the gas curtain becomes flatter, and its radial inward velocity component is significantly enhanced. This allows it to more forcefully sweep away the high concentration of SiO vapor volatilized near the quartz crucible wall and push it towards the center of the melt, where it is efficiently carried away by the main exhaust flow. Ultimately, this reduces the average oxygen partial pressure above the melt, bringing the axial oxygen content back to the target range. Conversely, when the axial oxygen content is too low or needs to be kept stable, the angle α is increased (e.g., to above 85°) to reduce the SiO discharge rate and prevent the oxygen content from becoming too low.

[0057] This mechanism, which automatically adjusts the injection angle based on axial oxygen content feedback, represents a highly refined and intelligent control of oxygen transport during crystal growth.

[0058] In many traditional CZ hot zone designs, a separate cylindrical guide tube is used to guide the main furnace gas flow, and quartz pins are often suspended on this guide tube. These quartz pins (made of high-purity quartz rods) hang above the melt, and they are heated at high temperatures and emit light, acting as passive thermal radiators to help finely adjust the thermal gradient near the crystal growth interface.

[0059] In some embodiments, the lower surface of the annular jet structure 130 may also include a plurality of suspension points configured for suspending quartz pins.

[0060] These suspension points can be a series of small holes, hooks, or lugs located on the lower surface of the annular jet structure 130 (i.e., the side facing the melt). One end of a quartz pin (not shown) can be configured in a T-shape or L-shape to allow it to be securely suspended at these suspension points.

[0061] The control device 100 for ingot growth (especially its annular jet structure 130) not only achieves active airflow control and sweeping functions, but also simultaneously performs the function of suspending quartz pins (and their associated passive thermal regulation) of a traditional guide tube. This allows the original guide tube inside the furnace to be removed, thereby reducing the number of components in the hot zone and lowering complexity. Removing a component that could obstruct the main airflow makes the organization of the overall airflow inside the furnace (including the air curtain generated by the control device 100 and the main exhaust flow) simpler and more controllable.

[0062] Figure 6 This is a flowchart illustrating a control method for ingot growth according to an embodiment of the present disclosure. The method aims to achieve precise control of oxygen uniformity during single-crystal silicon growth.

[0063] The method utilizes a crystal pulling furnace for crystal growth, which includes the control device 100 for ingot growth described in the foregoing embodiments.

[0064] This method includes the following key steps: Step S602: Positioning and injecting inert gas.

[0065] At the start of the method, the control device 100 for the growth of the crystal rod during the crystal growth process is positioned above the silicon melt 40 in the quartz crucible 30.

[0066] Subsequently, the inert gas supply system 70 is activated, and inert gas is injected into the annular gas guide structure 110 of the control device 100 through the inlet pipe 120, first filling the hollow annular cavity 112. As before, the annular cavity 112 serves to equalize pressure and dampen pulsations, ensuring that the gas source pressure supplied to the annular injection structure 130 is uniform and stable throughout the entire 360° circumference. Then, the pressure-equalized inert gas is ejected from the annular injection structure 130 (e.g., annular opening) of the control device 100 at high speed and uniformly.

[0067] Step S604: Form a conical laminar air curtain.

[0068] Since the annular injection structure 130 is constructed and oriented to be sprayed at an angle toward the free liquid surface, the inert gas sprayed in step S602 forms a stable and uniform conical laminar gas curtain above the free liquid surface of the silicon melt 40.

[0069] This gas curtain physically functions as a gas barrier, covering the entire liquid surface from the center of the melt to the outer perimeter (adjacent to the crucible wall). Its laminar flow characteristics ensure the predictability and stability of its flow.

[0070] Step S606: Actively sweep away silica vapor.

[0071] This is the core and key innovative step of this open methodology.

[0072] At high temperatures, the inner wall of the quartz crucible 30 (especially the outer region in contact with the melt 40) continuously reacts to generate SiO gas, which then evaporates. In conventional furnaces (such as those in the background art), due to the lack of effective directional airflow, this SiO gas accumulates in the outer region of the melt, resulting in a significantly higher SiO partial pressure in this region compared to the SiO partial pressure in the central region of the melt.

[0073] In step S606, the conical gas curtain formed in step S604, using its radially inward velocity component, exerts an active, forced directional thrust on the SiO vapor evaporating from the outer region of the surface of the melt 40 adjacent to the wall of the crucible 30. This thrust sweeps these high-concentration SiO vapors away from their source, forcing them to move radially inward and converge towards the central region of the surface of the melt 40. In the central region, the converged SiO vapor can be more effectively captured and carried away by the main exhaust flow of the furnace.

[0074] When the pulled crystal rod 50 is grown from such an atmosphere with uniform oxygen partial pressure, the concentration of oxygen atoms incorporated in its radial direction naturally becomes highly uniform, thus fundamentally solving the problem of radial oxygen inhomogeneity in the prior art.

[0075] Step S608: Dynamic adjustment and control.

[0076] In actual crystal growth, process conditions such as melt level drop and heater power change dynamically, which causes the SiO evaporation rate and axial oxygen content to fluctuate accordingly.

[0077] This step S608 dynamically adjusts the operating parameters of the control device 100 based on the axial oxygen content in the grown crystal.

[0078] Axial oxygen content is a key indicator of the overall oxygen content of a crystal (e.g., the head, middle, and tail of the crystal), and it can be monitored through real-time models (e.g., calculated based on argon flow rate, furnace pressure, heater power, and melt level) or sensors.

[0079] In one embodiment, the method includes adjusting the angle between the annular injection structure 130 and the annular gas guide structure 110 based on the axial oxygen content in the grown crystal. Adjusting the injection angle (α) optimizes radial uniformity. As before, a smaller α (e.g., 60°) provides a stronger sweep, while a larger α (e.g., 89°) provides a gentler sweep.

[0080] Furthermore, in one embodiment, the method further includes adjusting the flow rate of the inert gas entering the annular cavity 112 based on the axial oxygen content in the grown crystal. This is achieved by controlling a mass flow controller (MFC) in the inert gas supply system 70. Increasing the flow rate results in a stronger gas curtain, more effectively sweeping and carrying away SiO; it also produces a stronger cooling effect on the melt surface, thereby reducing the evaporation rate of SiO. Decreasing the flow rate results in an increase in the axial oxygen content.

[0081] The inert gas flow rate and the axial oxygen content of the crystal generally exhibit a controlled negative correlation. Increasing the gas flow rate into the annular cavity enhances the momentum of the conical laminar gas curtain ejected from the annular jet structure. This allows the laminar gas curtain to more effectively sweep away and carry SiO vapor volatilized near the quartz crucible wall to the center of the melt, thereby reducing the partial pressure of oxygen in the gas phase above the melt. Simultaneously, the cooling effect from the increased flow rate also slightly inhibits the evaporation rate of SiO. These two mechanisms work together to reduce the axial oxygen content entrained in the crystal from the melt.

[0082] In practice, the angle α, axial oxygen content, and inert gas flow rate are controlled in a coordinated manner. For example, when growing a 200mm diameter ingot, if the axial oxygen content reaches 18.5 ppma during the mid-stage of constant-diameter growth (assuming a target value of 17.5 ppma), the controller can first lower the angle α from the default 82° to 75° to initiate a strong sweeping mode. Simultaneously, to maintain the laminar flow stability of the gas curtain and enhance the sweeping effect, the inert gas flow rate will be increased from the set 40 SLPM to 50 SLPM via the flow controller. This combined operation can quickly bring the axial oxygen content back to the set range. After the oxygen content stabilizes, the system may fine-tune the angle to 78° and the flow rate back to 45 SLPM, entering a stable control stage that balances sweeping efficiency and gas consumption. This dynamic adjustment mechanism ensures that the oxygen content remains highly uniform and stable throughout the entire crystal pulling process, even if the amount of SiO volatilization changes due to a drop in melt level or increased crucible wall erosion.

[0083] This disclosure also provides a crystal pulling furnace (i.e., a single crystal furnace 10). See reference... Figure 2 and Figure 3 The crystal pulling furnace, based on its standard configuration (including furnace body 12, heater 20, quartz crucible 30, pulling mechanism, inert gas supply system 70, etc.), includes the control device 100 for crystal rod growth as described in the aforementioned embodiment.

[0084] The specific structure of the crystal pulling furnace has been described in detail above and will not be repeated here.

[0085] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not conflict.

[0086] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A control device for crystal rod growth, characterized in that, The apparatus is used in a single-crystal furnace comprising a heater and a quartz crucible for containing molten silicon, the apparatus comprising: An annular gas guiding structure is configured to be coaxially suspended above the quartz crucible and radially positioned between the crystal rod to be pulled in the single crystal furnace and the heater; The annular gas guiding structure includes a hollow annular cavity, which is used to guide inert gas. An annular jet structure is fluidly connected to the annular cavity, wherein the annular jet structure is constructed and oriented to guide the inert gas from the annular cavity into a conical laminar gas curtain, the conical laminar gas curtain being ejected at an angle toward the free liquid surface.

2. The control device for crystal rod growth according to claim 1, characterized in that, The device further includes: An intake pipe, in fluid communication with the annular cavity, is configured to receive inert gas from an inert gas supply system and to transfer the inert gas to the annular cavity.

3. The control device for crystal rod growth according to claim 1, characterized in that, The device further includes: An angle adjustment mechanism is used to adjust the angle between the annular injection structure and the annular gas guide structure.

4. The control device for crystal rod growth according to claim 3, characterized in that, The device further includes: A controller is used to control the angle adjustment mechanism based on the axial oxygen content in the grown crystal.

5. The control device for crystal rod growth according to claim 3, characterized in that, The angle adjustment mechanism is configured to adjust the spray angle within a range of 60 to 89 degrees relative to the horizontal plane.

6. The control device for crystal rod growth according to claim 1, characterized in that, The annular jet structure also includes multiple suspension points configured to suspend quartz pins.

7. The control device for crystal rod growth according to claim 1, characterized in that, The annular injection structure is detachably coupled to the annular gas guide structure.

8. A crystal pulling furnace, characterized in that, Includes the control device for crystal rod growth as described in any one of claims 1 to 7.

9. A method for controlling the growth of crystal rods, characterized in that, include: Crystal growth is performed using the crystal pulling furnace described in claim 8; The angle between the annular injection structure and the annular gas guiding structure is adjusted according to the axial oxygen content in the grown crystal.

10. The control method for crystal rod growth according to claim 9, characterized in that, The method further includes: The flow rate of the inert gas entering the annular cavity is adjusted according to the axial oxygen content in the grown crystal.

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