Flow guide device for single crystal silicon growth furnace, method and single crystal silicon growth furnace

Abstract

The present disclosure provides a flow guide device, method and single crystal silicon growth furnace for single crystal silicon growth furnace, aiming at solving the problem of uneven crystal quality caused by the asymmetry of the circumferential thermal field in the furnace during the Czochralski single crystal silicon growth process. The device includes a fixedly arranged flow guide cylinder body, a plurality of independently adjustable asymmetric flow guide plates circumferentially arranged at the lower end or inner wall of the flow guide cylinder, a driving mechanism located outside the furnace, a sealed transmission assembly passing through the furnace wall, and a closed-loop control system containing sensors. Based on the real-time monitoring of the circumferential temperature distribution of the melt surface or the air flow pressure distribution, the control system independently adjusts the deflection angle of each flow guide plate through the driving mechanism, actively builds an asymmetric air flow field in the furnace, and dynamically compensates for the inherent or time-varying thermal field asymmetry of the furnace body. The present disclosure can significantly improve the thermal field uniformity of the crystal growth interface, reduce the density of primary particles and light scattering defects, and improve the uniformity of the radial oxygen content and resistivity of the crystal.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor material preparation equipment and process technology, and in particular to a flow guiding device, method and single crystal silicon growth furnace for a single crystal silicon growth furnace. Background Technology

[0002] The Czochralski (CZ) process is currently the mainstream technology worldwide for producing large-size single-crystal silicon for integrated circuits (e.g., 12-inch and larger wafers). The core of this process involves melting high-purity polycrystalline silicon in a quartz crucible, with a seed crystal contacting the melt surface, and the crystal gradually growing from the melt under strictly controlled temperature gradients and pulling speeds. The design of the hot zone system is crucial in this process, directly determining the temperature distribution near the crystal growth interface, the convection pattern of the melt, and the transport behavior of impurities (such as oxygen and carbon). The flow guide tube, a key component of the hot zone system, is typically suspended between the heater and the crystal. Its main functions include two aspects: first, acting as a thermal shield to block direct radiation from the heater to the crystal, increasing the axial temperature gradient of the crystal; second, guiding a protective gas (usually high-purity argon) at a specific flow rate and direction across the melt surface, carrying away byproducts such as silicon oxide (SiO) volatilized from the melt, preventing them from depositing in the furnace or falling into the melt and causing dislocations.

[0003] Existing flow guide tube designs generally adhere to strict axisymmetry principles. In traditional single-crystal furnace thermal configurations, the flow guide tube is typically designed as an inverted frustum or cylindrical integral structure with a standard circular cross-section, exhibiting rotational symmetry along its central axis. The bottom opening edge of the flow guide tube is usually designed as a straight circle or a symmetrical shape with a large arc transition. This design concept is based on the idealized assumption that the thermal field, airflow field, and mechanical structure within the single-crystal furnace are perfectly axisymmetrically distributed. In practice, process engineers typically control the crystal cooling rate and melt surface evaporation macroscopically only by adjusting the axial distance between the flow guide tube and the silicon melt surface. This passive, single-dimensional (vertical only) adjustment method is effective for crystal growth under ideal conditions and is relatively simple in structure, easy to process and install.

[0004] However, a key problem that has long remained unresolved in existing operating methods is the inherent, difficult-to-eliminate, and time-varying circumferential asymmetry of the internal thermal field of single-crystal furnaces in actual production environments. This asymmetry does not originate from the flow guide tube itself, but rather from other auxiliary structures of the furnace and the operating environment. For example, to power the heaters, asymmetrical electrode rods must be arranged inside the furnace, creating localized "cold spots" or "hot spots." Observation windows on the furnace walls, used for real-time monitoring of crystal growth, disrupt the continuity of the insulation layer, creating localized heat dissipation channels. Furthermore, the location of the vacuum vent, the non-ideal symmetry of the magnetic field, and the slight eccentricity of the crucible rotation mechanism all contribute to deviations of the actual temperature field within the furnace from the ideal axisymmetric distribution. Traditional axisymmetric flow guide tubes are ineffective in addressing this issue; in fact, their rigid symmetrical structure may restrict the natural balance of airflow, exacerbating localized airflow vortices or dead zones. This circumferential thermal field inhomogeneity is directly projected onto the crystal growth interface, resulting in inconsistent temperature gradients in different directions. This inconsistency is the root cause of uneven distribution of crystal-originated particles (COP), light point defects (LDP), and excessive fluctuations in radial oxygen content (ROG) and radial resistivity (RRG) in the crystal, which severely restricts the improvement of the yield of high-end semiconductor-grade single crystal silicon. Summary of the Invention

[0005] The purpose of this disclosure is to provide a flow guiding device, method, and single-crystal silicon growth furnace to solve the problem of uneven thermal field during crystal growth caused by the inherent circumferential asymmetry of the furnace structure and process environment in the prior art. This disclosure breaks the symmetry limitation of traditional flow guiding tubes by introducing an independently adjustable local flow guiding structure, achieving dynamic and directional compensation of the thermal field and airflow field.

[0006] To solve the above-mentioned technical problems, the present disclosure adopts the following technical solution:

[0007] In a first aspect, this disclosure provides a flow guiding device for a single-crystal silicon growth furnace, comprising: The guide tube body is constructed as a hollow rotating structure around the growth axis of single crystal silicon, and the guide tube body defines an internal channel for the flow of protective gas. An asymmetric flow guiding assembly includes at least one movable flow guide plate arranged circumferentially on the lower end or inner sidewall of the flow guide body, the flow guide plate being configured to be angularly deflected relative to the axis of the flow guide body to generate an adjustable asymmetric airflow distribution at the lower end outlet of the flow guide body. A drive mechanism is located outside the furnace chamber of the single crystal silicon growth furnace and is used to provide the power to drive the guide plate to deflect. A transmission assembly passes through the furnace wall of the single crystal silicon growth furnace and sealably connects the drive mechanism and the guide plate, transmitting the power of the drive mechanism to the guide plate; A sensing and monitoring system, deployed on the furnace wall of the single-crystal silicon growth furnace or in communication with the furnace environment, is used to detect in real time the circumferential temperature distribution parameters or airflow pressure parameters of the furnace's thermal field; and The control system is electrically connected to the sensing and monitoring system and the drive mechanism, respectively. The control system is configured to calculate the circumferential nonuniformity of the thermal field based on the circumferential temperature distribution parameters or airflow pressure parameters, and generate control commands based on the circumferential nonuniformity to control the drive mechanism to adjust the deflection angle of the guide plate, thereby dynamically compensating for the asymmetry of the circumferential thermal field in the furnace.

[0008] In some embodiments, the guide tube body is made of chemical vapor infiltration toughened carbon fiber reinforced carbon-based composite material.

[0009] In some embodiments, the inner wall of the guide tube body is covered with a silicon carbide high emissivity coating formed by chemical vapor deposition, and the outer wall of the guide tube body is covered with a thermal barrier reflective coating formed by plasma spraying.

[0010] In some embodiments, the asymmetric flow guiding assembly includes a plurality of flow guiding plates evenly spaced along the circumference of the flow guiding cylinder body, each flow guiding plate being independently connected to the transmission assembly and the drive mechanism, such that each flow guiding plate can be independently adjusted in angle.

[0011] In some embodiments, the transmission assembly includes: A drive shaft, one end of which is fixedly connected to the guide plate; A bushing, fitted over the outside of the drive shaft and fixed to the guide tube body, provides rotational support and dry lubrication for the drive shaft; and A heat-blocking section is provided on the drive shaft to block heat from being conducted to the drive mechanism.

[0012] In some embodiments, the drive mechanism includes: An active magnetic ring is located outside the furnace chamber of the single crystal silicon growth furnace and is driven to rotate by a motor; A driven magnetic ring, located inside the furnace chamber of the single-crystal silicon growth furnace, is connected to the transmission assembly; and An isolation cover, made of non-magnetic material and sealed and fixed to the furnace wall, is located between the active magnetic ring and the driven magnetic ring, isolating the vacuum environment inside the furnace from the outside atmosphere.

[0013] In some embodiments, the sensing and monitoring system includes at least four infrared thermometers installed on the furnace wall of the single crystal silicon growth furnace. The infrared thermometers are evenly distributed circumferentially, and their observation fields are respectively aligned with different circumferential regions of the silicon melt surface.

[0014] In some embodiments, the control system internally stores a thermal field hydrodynamic model, and the control system is configured to calculate the target deflection angle of the guide vane required to eliminate the currently detected circumferential temperature difference using a PID control algorithm or a model predictive control algorithm.

[0015] In a second aspect, embodiments of this disclosure provide a flow guiding method for a single-crystal silicon growth furnace, the method being performed using a flow guiding device for a single-crystal silicon growth furnace according to the first aspect, the method comprising: The sensor monitoring system is used to collect circumferential multi-point temperature data on the surface of the silicon melt in the single crystal silicon growth furnace in real time. The control system compares the collected temperature data from multiple points and calculates the temperature deviation value. When the temperature deviation exceeds a preset threshold, the control system identifies the high-temperature zone or low-temperature zone of the thermal field. The control system calculates the required deflection angle of the guide vane in the corresponding area and sends control commands to the drive mechanism. The driving mechanism drives the corresponding guide vane to deflect to the target angle, changing the local airflow speed until the temperature deviation value is reduced to below the preset threshold.

[0016] Thirdly, embodiments of this disclosure provide a single-crystal silicon growth furnace, including a furnace body, a crucible disposed within the furnace body, a heater, and a flow guiding device for a single-crystal silicon growth furnace as described in the first aspect.

[0017] This disclosure provides a flow guiding device, method, and single-crystal silicon growth furnace. First, this disclosure achieves precise circumferential compensation of the thermal field within the single-crystal furnace. By breaking away from the absolute symmetry design of traditional flow guide tubes, an asymmetric airflow field is generated circumferentially using independently adjustable flow guide plates. This device can specifically counteract inherent thermal field deviations caused by observation windows, electrodes, or process fluctuations. For example, when a region is detected to have a high temperature, the angle of the corresponding flow guide plate can be adjusted to increase the local airflow velocity, enhance convective heat transfer, and thus eliminate local hot spots. Second, this disclosure significantly improves the intrinsic quality of single-crystal silicon. Due to the circumferential homogenization of airflow and temperature above the melt surface, the radial temperature gradient at the crystal growth interface becomes more consistent. This directly reduces the density of primary particles (COP) and light scattering defects (LDP) caused by uneven thermal stress during crystal growth, and significantly improves the uniformity of radial oxygen content (ROG) and resistivity (RRG) of the wafer, making the produced wafers more compliant with the stringent requirements of advanced process technologies (such as 7nm and 5nm nodes). Finally, this disclosure possesses high dynamic adaptability and process stability. Combining real-time sensing with closed-loop control algorithms (such as PID or model predictive control), the device can automatically track and compensate for thermal field drift during crystal pulling processes that can last for several days, without frequent manual intervention. Simultaneously, the use of external furnace drive and magnetic coupling / sealed transmission design avoids contamination of the high-purity environment inside the furnace by moving parts, ensuring the purity of crystal growth. The carbon-carbon composite material and internal and external functional coatings used in the guide tube body further optimize radiative heat transfer efficiency, reduce energy consumption, and extend the service life of components. Attached Figure Description

[0018] Figure 1 This is a longitudinal cross-sectional schematic diagram of the overall structure of the flow guiding device for a single crystal silicon growth furnace disclosed herein, showing the installation position of the device inside the furnace and the connection relationship of each subsystem.

[0019] Figure 2 This is a bottom view of the guide tube body and asymmetric guide components in this disclosure, which focuses on the layout of the four circumferentially distributed adjustable guide plates and their correspondence with the sensors.

[0020] Figure 3 This is a partially enlarged cross-sectional schematic diagram of the drive mechanism and transmission components in this disclosure, which shows in detail the magnetic coupling drive structure and sealing design.

[0021] Figure 4 This is a schematic cross-sectional view of the wall microstructure of the guide tube body in this disclosure, showing the layered structure of the carbon-carbon composite matrix and the inner and outer heterogeneous functional coatings.

[0022] Figure 5This is a logic block diagram of the control system disclosed herein, illustrating the closed-loop control process from signal acquisition and algorithm processing to actuator action.

[0023] Figure 6 This is a schematic flow diagram of the flow guiding method for a single-crystal silicon growth furnace disclosed herein. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following will provide a more detailed description of this disclosure in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this disclosure.

[0025] First, the overall system architecture and layout are introduced. To address the key technical problem of circumferential thermal asymmetry during single-crystal silicon growth, this disclosure provides a current guiding device. See [link to relevant documentation]. Figure 1 The device is installed on the furnace wall 701 of the single-crystal silicon growth furnace (see attached figure). A single-crystal silicon growth furnace typically includes a crucible 702 containing molten silicon 704, a main heater 703 surrounding the crucible, and a lifting mechanism (not shown). The growing single-crystal silicon rod 705 is lifted out of the molten silicon 704. The flow guiding device of this disclosure is suspended above the furnace body, located between the single-crystal silicon rod 705 and the main heater 703, and its main function is to guide the protective argon gas flow line 706 and shield against thermal radiation.

[0026] The device is mainly composed of five core subsystems: the guide tube body 100, the asymmetric guide component 200, the drive mechanism 300, the transmission component 400, and a closed-loop intelligent control network including a sensing and monitoring system 500 and a control system 600.

[0027] The following section describes the fine structure and composite material processing of the guide tube body. In traditional single-crystal furnace designs, the guide tube is often made of high-purity graphite. However, graphite is brittle and typically has a large wall thickness (over 10 mm), resulting in high heat capacity and sluggish thermal response. To achieve the rapid thermal response sought in this disclosure, the guide tube body 100 has undergone in-depth material and structural optimization.

[0028] See Figure 1 The main structure of the guide tube body 100 is an inverted frustum-shaped thin-walled cylinder. Its upper end is designed with a reinforced flange as the upper mounting part 102, which is fixed to the lifting ring below the furnace cover by molybdenum bolts or ceramic pins. The cylinder gradually tapers downwards, forming an internal channel 101, extending to the lower airflow outlet 103. The diameter of the lower airflow outlet 103 is slightly larger than the target diameter of the single-crystal silicon rod 705, typically with an annular gap of 30mm to 50mm.

[0029] To illustrate the material composition more clearly, refer to... Figure 4 The micro-section of the guide tube body 100 shows that it adopts the design concept of "gradient functional materials". Its core layer is a carbon-based composite matrix 110, specifically a carbon fiber reinforced carbon-based composite material (C / C composite material) toughened by chemical vapor infiltration (CVI).

[0030] In the manufacturing process, polyacrylonitrile (PAN)-based carbon fibers are first used to create a fiber preform for the flow guide tube through a three-dimensional weaving technique. The three-dimensional weaving structure imparts extremely high interlaminar shear strength to the matrix, preventing delamination. Subsequently, the preform is placed in a CVI deposition furnace, and carbon source gases such as methane or propylene are introduced. Under high temperature and low pressure, the gases are pyrolyzed, causing pyrolytic carbon to deposit in the fiber pores until the density reaches 1.6 g / cm³. 3 Up to 1.75 g / cm 3 .

[0031] Compared to traditional graphite, C / C composite materials have 3-5 times higher tensile strength, which allows the wall thickness of the guide tube body 100 to be designed to be very thin, preferably ranging from 3 mm to 8 mm, and even reaching 3 mm to 5 mm in some high-performance models. The extremely thin wall thickness means extremely low thermal mass, enabling the guide tube to rapidly change its own temperature in response to changes in heater power, laying the foundation for dynamic control.

[0032] A silicon carbide inner coating 111 is provided on the inner wall surface 104 (facing the crystal side) of the carbon-based composite matrix 110. This coating is prepared by chemical vapor deposition (CVD) and has a thickness of approximately 50 to 100 micrometers. The silicon carbide inner coating 111 has two key functions.

[0033] First, there is the high emissivity: SiC has a spectral emissivity exceeding 0.85 at high temperatures. This allows the inner wall 104 to act as a highly efficient "heat absorber," rapidly absorbing the latent heat released by the newly solidified high-temperature crystal, and transferring the heat to the low-temperature argon gas flowing through the internal channel 101 via radiation, accelerating crystal cooling and thus allowing for increased crystal pulling speed.

[0034] Secondly, the SiO gas emitted from the silicon melt has a strong corrosive effect on carbon materials (generating SiC and CO gases, leading to carbon loss). The dense CVD-SiC layer completely seals the carbon matrix, preventing this chemical erosion and also eliminating the risk of carbon dust falling and contaminating the silicon melt 704.

[0035] A zirconia outer coating 112 is provided on the outer wall surface 105 (facing the heater side) of the carbon-based composite matrix 110. The coating is prepared by atmospheric plasma spraying (APS) process, and its main component is yttrium-stabilized zirconia.

[0036] It is worth noting that the carbon matrix (coefficient of thermal expansion CTE is approximately 1-2 × 10⁻⁶)-6 / K) and zirconium oxide (CTE approximately 10 × 10⁻⁶) -6 There is a significant thermal expansion mismatch between / K). Direct spraying can easily lead to coating peeling at high temperatures. Therefore, as Figure 4 As shown, a bonding transition layer 113 is introduced between the substrate and the outer coating. The bonding transition layer 113 is typically composed of a multilayered silicon / silicon carbide / mullite mixture with varying compositions, or it may be designed as a stress-relieving layer with a microcrack structure to buffer thermal stress.

[0037] The zirconia outer coating 112 has extremely low thermal conductivity (<2 W / m·K) and high infrared reflectivity. It acts as a thermal barrier layer, reflecting the heat radiated from the main heater 703 back to the crucible 702, preventing heat from penetrating laterally through the flow tube to heat the crystal. This asymmetric coating design of "external barrier and internal absorption" further enhances the axial temperature gradient required for crystal growth.

[0038] The kinematics and hydrodynamics design of asymmetric flow guiding components will be discussed next. See [link / reference] Figure 1 and Figure 2 The asymmetric flow guiding component 200 is the execution end of the present disclosure for realizing circumferential flow field control. At the lower end of the flow guiding tube body 100, at the airflow outlet 103, four independent flow guiding plates 201 are evenly arranged in the circumferential direction, namely the first flow guiding plate 201a, the second flow guiding plate 201b, the third flow guiding plate 201c and the fourth flow guiding plate 201d.

[0039] In terms of shape design, the baffle 201 is not a simple flat plate. Considering that the argon gas inside the furnace is in a high-temperature (approximately 1400℃) and low-pressure (approximately 15-20 Torr) state, with a low Reynolds number and significant gas viscosity effect, in order to avoid the generation of unstable vortices behind the baffle due to gas flow separation (which would cause oscillations on the melt surface), the cross-section of the baffle 201 is designed as a streamlined airfoil, or a curved plate structure with a smooth arc. The chord length of the baffle 201 is approximately 30mm to 60mm, and the span covers 50% to 80% of the height of the baffle tube outlet.

[0040] Each deflector 201 is connected to the deflector body 100 via a pivot joint 202. The pivot joint 202 allows the deflector to rotate about a nearly vertical axis. The deflector 201 can be continuously adjusted within the range of 0 degrees (parallel to radial airflow, undisturbed) to 30 degrees (inward or outward deflection, maximum disturbance) via a drive mechanism.

[0041] When the guide vane 201 deflects inward, it reduces the airflow area in that quadrant. According to the continuity equation, the gas velocity flowing through this region will increase significantly. The high-speed airflow enhances convective heat transfer (cooling effect) on the melt surface and accelerates the evaporation of SiO. Conversely, if the guide vane deflects outward, the flow velocity decreases, and the heat preservation effect is enhanced.

[0042] In terms of materials, the deflector 201 also uses C / C composite material prepared by CVI process and is coated with CVD-SiC on its entire surface. In order to prevent the deflector 201 from fluttering under the impact of high temperature airflow, a reinforcing rib structure is designed at its root.

[0043] The high-temperature adaptability design of the transmission components is described below. Transmitting driving force from the ambient temperature outside the furnace to the high-temperature environment exceeding 1400°C inside the furnace without disrupting the vacuum seal is a major challenge of this device. (See also...) Figure 1 and Figure 3 This disclosure employs a precision transmission component 400.

[0044] The transmission assembly 400 includes a slender drive shaft 401. To withstand high temperatures and maintain rigidity, the main body of the drive shaft 401 is made of a molybdenum alloy (such as TZM, a titanium-zirconium-molybdenum alloy). Molybdenum alloys have high strength at high temperatures but also good thermal conductivity. To prevent a large amount of heat from being conducted upwards along the axis and burning out the seals or drive mechanism, a heat-blocking section 403 is connected in series at the upper part of the drive shaft 401. The heat-blocking section 403 is made of structural ceramic (such as zirconium oxide or silicon nitride), and both ends of the ceramic are connected to the metal shaft by brazing or mechanical fitting.

[0045] The drive shaft 401 needs to pass through the side wall or be fixed along the inner wall of the guide tube body 100. A bushing 402 is provided here. Since grease lubrication cannot be used at high temperatures, the bushing 402 is made of high-purity isotropic graphite. Dry friction is achieved by utilizing the self-lubricating properties of the graphite layered structure.

[0046] Furthermore, thermal expansion must be considered in the design. The coefficient of linear expansion of molybdenum is approximately 5.5 × 10⁻⁶. -6 / K, while isotropic graphite is approximately 4.0-5.0×10⁻⁶. -6 / K. Although the two are close, the dimensional changes are still significant at a temperature difference of 1000℃. Therefore, when assembling the bushing 402 and the drive shaft 401 at room temperature, a precisely calculated gap (e.g., 0.05mm to 0.1mm) must be reserved to ensure that at the operating temperature, the gap is neither too large to cause wobbling nor too small to cause jamming.

[0047] To completely eliminate the risk of leakage that may be caused by dynamic seals, the drive mechanism 300 adopts magnetofluid or magnetic coupling technology. Figure 3A preferred magnetic coupling drive scheme is presented.

[0048] The drive mechanism 300 is installed on the flange interface outside the furnace body wall 701. It includes an active magnetic ring 301, a driven magnetic ring 302, and an isolation cover 303.

[0049] The isolation hood 303 is a cup-shaped sealed blind tube, typically made of non-magnetic stainless steel (such as 316L), high-strength engineering plastics (such as PEEK, for low-temperature zones only), or quartz. It forms a static seal with the furnace body via the furnace wall sealing flange 405, completely enclosing the vacuum environment inside the furnace within the hood.

[0050] The driven magnetic ring 302 is located inside the isolation cover 303 and is connected to the top of the drive shaft 401 via a connecting coupling 404. The driving magnetic ring 301 is located outside the isolation cover 303, fitted over the outside of the isolation cover, and is driven to rotate by the drive motor 304.

[0051] When the drive motor 304 rotates, the strong magnetic lines of force penetrate the isolation cover 303, locking the internal driven magnetic ring 302 and causing it to rotate synchronously. This non-contact transmission method completely eliminates the potential for dynamic seal leakage at the shaft's penetration point.

[0052] Since the driven magnetic ring 302 is located in the extension part of the furnace body, it may be affected by some heat conduction. In order to prevent the permanent magnet from demagnetizing, the driven magnetic ring 302 is made of high-temperature resistant samarium cobalt magnet (operating temperature up to 350℃). At the same time, a water-cooling jacket 305 is wrapped around the outside of the driving magnetic ring 301, and circulating cooling water is introduced to remove the residual heat conducted by the drive shaft and the heat generated by magnetic eddy currents.

[0053] The sensing and monitoring and closed-loop control logic are described in detail below. (See also...) Figure 1 , Figure 2 and Figure 5 The reason why this device can achieve "adaptation" is due to the control system.

[0054] The sensing and monitoring system 500 includes four high-precision dual-color infrared thermometers 501, each mounted outside one of the four observation windows 502 above the furnace body. Dual-color thermometers were chosen because they determine temperature by measuring the ratio of the radiation of two wavelengths, and are less affected by contamination of the window glass or obstruction by smoke and dust. The fields of view of the four thermometers are aligned with the four quadrants of the surface of the silicon melt 704. A specially designed purge gas path is located below the observation windows 502, using high-speed argon gas to form an air curtain to prevent SiO dust deposition.

[0055] The control system 600 includes a signal processing unit 601, a core controller 602, and a drive controller 603. Its workflow is as follows.

[0056] The first step is data acquisition. The signal processing unit 601 acquires the temperature signals T1, T2, T3, and T4 from the four infrared thermometers 501 at a high frequency (e.g., 10Hz).

[0057] Next is the non-uniformity calculation. The core controller 602 calculates the current circumferential average temperature T. avg And calculate the deviation ΔTi = Ti - T at each point. avg .

[0058] The next step is policy generation. Assume that T1 is detected to be more than T... avg If the temperature exceeds 5°C (exceeding the preset uniformity threshold of 2°C), it is determined that there is heat accumulation in the first quadrant region. Based on the built-in thermal-flow coupling model (which pre-stores the correspondence between the guide vane angle and the local flow velocity and heat dissipation), the controller calculates that the first guide vane 201a needs to be deflected inward by 12 degrees.

[0059] Next, the adjustment is performed. The drive controller 603 sends a pulse signal to the drive motor 304 that controls the first guide plate. The motor rotates, driving the guide plate 201a to deflect through magnetic coupling.

[0060] Finally, there is feedback correction. After the deflector deflects, the flow velocity in the first quadrant increases, heat dissipation accelerates, and T1 begins to decrease. The controller continuously monitors the rate of change of T1 and uses a PID algorithm to fine-tune the angle until T1 returns to the allowable deviation range.

[0061] In addition, the control system can also incorporate data from pressure sensor 503. If high-frequency fluctuations in the furnace pressure are detected (indicating unstable airflow), the system will appropriately reduce the deflection amplitude of the guide vanes to prioritize flow field stability.

[0062] In a typical crystal pulling process, as the length of the crystal rod increases, the crucible 702 will rise continuously, and the position of the melt surface relative to the heater will change, causing the thermal field structure to drift.

[0063] During the crystal pulling stage, in order to prevent the melt from overcooling and causing edge breakage, the control system keeps all guide plates 201 at 0 degrees to reduce heat dissipation.

[0064] During the constant-diameter growth stage, the system enters a fully automatic closed-loop mode. Assume that at this time, due to heat dissipation from the furnace wall observation window, the melt temperature on the side facing the window is lower. The sensor keenly detects this temperature difference. The control system then instructs the guide vane facing the observation window to deflect outwards, slowing the airflow on that side and reducing heat loss; simultaneously, it instructs the guide vane on the opposite side to fine-tune inwards, increasing heat dissipation. Through this dynamic "peak shaving and valley filling," an extremely uniform thermal environment is maintained on the melt surface.

[0065] Accordingly, see Figure 6This disclosure provides a flow guiding method for a single-crystal silicon growth furnace, which is executed using a flow guiding device for a single-crystal silicon growth furnace according to the foregoing embodiments. The method includes: S601: Real-time collection of circumferential multi-point temperature data on the surface of silicon melt in the single crystal silicon growth furnace using a sensor monitoring system; S602: The control system compares the collected temperature data from multiple points and calculates the temperature deviation value; S603: When the temperature deviation exceeds the preset threshold, the control system identifies the high-temperature zone or low-temperature zone of the thermal field. S604: The control system calculates the required deflection angle of the guide vane in the corresponding area and sends control commands to the drive mechanism; S605: The drive mechanism drives the corresponding guide vane to deflect to the target angle, changing the local airflow speed until the temperature deviation value is reduced to below the preset threshold.

[0066] Experimental data show that after applying this device, the radial resistivity non-uniformity (RRG) of the grown 12-inch single crystal silicon rod was reduced from the traditional 5% to less than 2%, the COP defect density was reduced by an order of magnitude, and the product yield was significantly improved.

[0067] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A flow guiding device for a single-crystal silicon growth furnace, characterized in that, include: The guide tube body is constructed as a hollow rotating structure around the growth axis of single crystal silicon, and the guide tube body defines an internal channel for the flow of protective gas. An asymmetric flow guiding assembly includes at least one movable flow guide plate arranged circumferentially on the lower end or inner sidewall of the flow guide body, the flow guide plate being configured to be angularly deflected relative to the axis of the flow guide body to generate an adjustable asymmetric airflow distribution at the lower end outlet of the flow guide body. A drive mechanism is located outside the furnace chamber of the single crystal silicon growth furnace and is used to provide the power to drive the guide plate to deflect. A transmission assembly passes through the furnace wall of the single crystal silicon growth furnace and sealably connects the drive mechanism and the guide plate, transmitting the power of the drive mechanism to the guide plate; The sensing and monitoring system is arranged on the furnace wall of the single crystal silicon growth furnace or in a position that is in communication with the furnace environment, and is used to detect the circumferential temperature distribution parameters or airflow pressure parameters of the furnace thermal field in real time. as well as The control system is electrically connected to the sensing and monitoring system and the drive mechanism, respectively. The control system is configured to calculate the circumferential nonuniformity of the thermal field based on the circumferential temperature distribution parameters or airflow pressure parameters, and generate control commands based on the circumferential nonuniformity to control the drive mechanism to adjust the deflection angle of the guide plate, thereby dynamically compensating for the asymmetry of the circumferential thermal field in the furnace.

2. The flow guiding device for a single-crystal silicon growth furnace according to claim 1, characterized in that, The guide tube body is made of carbon fiber reinforced carbon-based composite material toughened by chemical vapor infiltration.

3. The flow guiding device for a single-crystal silicon growth furnace according to claim 2, characterized in that, The inner wall of the guide tube body is covered with a silicon carbide high emissivity coating formed by chemical vapor deposition, and the outer wall of the guide tube body is covered with a thermal barrier reflective coating formed by plasma spraying.

4. The flow guiding device for a single-crystal silicon growth furnace according to claim 1, characterized in that, The asymmetric flow guiding assembly includes a plurality of flow guiding plates evenly spaced along the circumference of the flow guiding cylinder body. Each flow guiding plate is independently connected to the transmission assembly and the drive mechanism, so that each flow guiding plate can be independently adjusted in angle.

5. The flow guiding device for a single-crystal silicon growth furnace according to claim 1, characterized in that, The transmission assembly includes: A drive shaft, one end of which is fixedly connected to the guide plate; A bushing, fitted over the outside of the drive shaft and fixed to the guide tube body, provides rotational support and dry lubrication for the drive shaft; and A heat-blocking section is provided on the drive shaft to block heat from being conducted to the drive mechanism.

6. The flow guiding device for a single-crystal silicon growth furnace according to claim 1, characterized in that, The drive mechanism includes: An active magnetic ring is located outside the furnace chamber of the single crystal silicon growth furnace and is driven to rotate by a motor; A driven magnetic ring, located inside the furnace chamber of the single-crystal silicon growth furnace, is connected to the transmission assembly; and An isolation cover, made of non-magnetic material and sealed and fixed to the furnace wall, is located between the active magnetic ring and the driven magnetic ring, isolating the vacuum environment inside the furnace from the outside atmosphere.

7. The flow guiding device for a single-crystal silicon growth furnace according to claim 1, characterized in that, The sensing and monitoring system includes at least four infrared thermometers installed on the furnace wall of the single crystal silicon growth furnace. The infrared thermometers are evenly distributed circumferentially, and their observation fields are respectively aligned with different circumferential areas of the silicon melt surface.

8. The flow guiding device for a single-crystal silicon growth furnace according to claim 1, characterized in that, The control system stores a thermal field fluid dynamics model and is configured to calculate the target deflection angle of the guide vane required to eliminate the currently detected circumferential temperature difference using a PID control algorithm or a model predictive control algorithm.

9. A flow guiding method for a single-crystal silicon growth furnace, characterized in that, The method is performed using a flow guiding device for a single-crystal silicon growth furnace according to any one of claims 1 to 8, the method comprising: The sensor monitoring system is used to collect circumferential multi-point temperature data on the surface of the silicon melt in the single crystal silicon growth furnace in real time. The control system compares the collected temperature data from multiple points and calculates the temperature deviation value. When the temperature deviation exceeds a preset threshold, the control system identifies the high-temperature zone or low-temperature zone of the thermal field. The control system calculates the required deflection angle of the guide vane in the corresponding area and sends control commands to the drive mechanism. The driving mechanism drives the corresponding guide vane to deflect to the target angle, changing the local airflow speed until the temperature deviation value is reduced to below the preset threshold.

10. A single-crystal silicon growth furnace, characterized in that, It includes a furnace body, a crucible disposed within the furnace body, a heater, and a flow guiding device for a single-crystal silicon growth furnace according to any one of claims 1 to 8.

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