System and method for preparing quartz crucible with low bubble density

Abstract

The invention discloses a system and method for preparing a low-bubble-density quartz crucible, and belongs to the technical field of crucible production, the system comprises a mold air permeability structure optimization module, a feeding proportion optimization module, an electrode control module and a vacuum control module; a plurality of non-uniformly distributed air vents and a plurality of independent temperature control areas are arranged on the mold air permeability structure optimization module; the feeding proportion optimization module comprises a material storage and distribution device used for achieving gradient particle gradation feeding. The electrode control module comprises a position and angle adjustable electrode group and a pulse current generation unit; the vacuum control module comprises a grading exhaust pipeline with asymmetric pipeline diameters and an intelligent frequency conversion regulation and control unit. The micro-bubble density of the liquid level line area of the upper opening of the crucible is greatly reduced, and the problem that the stability of subsequent crystal bar growth and the crystal quality are affected due to the fact that the bubble density of the liquid level line of the upper opening of the quartz crucible is too high in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of crucible manufacturing technology, and more specifically to a system and method for preparing low-bubble-density quartz crucibles. Background Technology

[0002] With the rapid development of global semiconductor, new energy and other industries, the market demand for quartz crucibles, as a key basic consumable for crystal growth, continues to grow, and the requirements for product quality are becoming increasingly stringent. During the melting process of quartz crucibles, the microbubble problem at the liquid level line at the top of the melt (i.e., at the solid-liquid-gas three-phase interface) is a core technical bottleneck affecting the quality of the inner wall of the quartz crucible, and thus restricting the yield and performance of single-crystal silicon and other crystal growth.

[0003] Currently, the industry commonly uses traditional graphite molds for melting. These molds generally suffer from poor uniformity of pore distribution and a single pore size structure, leading to an imbalance in the surface tension of the melt and making it difficult to form stable and orderly venting channels. This results in abnormal aggregation and retention of microbubbles in the liquid level region. Furthermore, the entire melting process heavily relies on operator experience for parameter control, lacking precise theoretical model guidance. For example, fixed electrode positions and current parameters are difficult to adapt to the dynamically changing temperature and flow fields during melting, easily inducing new bubble nucleation due to current concentration. Additionally, vacuum pumping systems often employ fixed flow rates and uniform diameter pipe layouts, failing to consider the differences in bubble migration paths and degassing efficiency at different melt depths, thus limiting their ability to suppress and remove microbubbles. These factors collectively result in high bubble density and large liquid level fluctuations at the liquid level of the prepared quartz crucible, severely impacting the stability and crystal quality of subsequent crystal growth. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, this invention provides a system and method for preparing low-bubble-density quartz crucibles, which can reduce the bubble density at the liquid level line at the top of the quartz crucible and improve the stability and crystal quality of subsequent crystal rod growth.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A system for preparing low bubble density quartz crucibles includes a mold permeability structure optimization module, a feeding ratio optimization module, an electrode control module, and a vacuum control module;

[0007] The mold permeability structure optimization module includes a crucible mold made of porous gradient composite material. The crucible mold has multiple non-uniformly distributed permeable holes with different diameters. The inner wall of the crucible mold is integrated with multiple independently temperature-controlled zones. The distribution of the temperature-controlled zones is related to the distribution of the permeable holes.

[0008] The feeding ratio optimization module includes a storage and distribution device for realizing gradient particle size distribution feeding;

[0009] The electrode control module includes an electrode group with adjustable position and angle, and a pulse current generating unit that powers the electrode group.

[0010] The vacuum control module includes a staged extraction pipeline with an asymmetric pipe diameter and an intelligent frequency conversion control unit. The staged extraction pipeline is equipped with multiple pressure sensors and gas flow sensors. The intelligent frequency conversion control unit dynamically adjusts the extraction parameters of the staged extraction pipeline based on the feedback parameters of the pressure sensors and gas flow sensors.

[0011] Preferably, the crucible mold is divided into multiple independently temperature-controlled zones along its axial and / or circumferential directions, and each temperature-controlled zone integrates independent heating and / or cooling elements;

[0012] The vent holes on the crucible mold are divided into multiple vent hole distribution areas, and the multiple temperature control areas correspond one-to-one with the multiple vent hole distribution areas. Among them, the pore size and opening density of the vent holes in at least two different vent hole distribution areas are not exactly the same.

[0013] Preferably, the multiple independently temperature-controlled zones integrated on the inner wall of the crucible mold include at least a first temperature-controlled zone corresponding to the liquid level line at the top of the quartz crucible, and a second temperature-controlled zone adjacent to the first temperature-controlled zone.

[0014] The pore density and pore diameter of the pore distribution area corresponding to the first temperature control zone are both greater than those of the pore distribution area corresponding to the second temperature control zone.

[0015] Preferably, in the vent distribution area corresponding to the first temperature control zone, the vents are distributed in a matrix, and the distance between two adjacent vents is 25mm.

[0016] The set control temperature of the first temperature control zone is higher than the set control temperature of the second temperature control zone.

[0017] Preferably, the storage and distribution device includes a storage mechanism and a distribution mechanism. The storage mechanism includes at least three independent storage bins, each of which is used to store quartz raw materials with different particle size ranges. The distribution mechanism is used to control the quartz raw materials in the storage bins to be sequentially added to the crucible mold according to a set ratio and layer sequence.

[0018] Preferably, the storage mechanism includes:

[0019] The first storage silo is used to store coarse-grained quartz sand with a particle size greater than 40 mesh.

[0020] The second storage bin is used to store medium-sized quartz particles with a particle size between 70 mesh and 120 mesh.

[0021] The third storage silo is used to store nano-sized silicon powder with a particle size of less than 325 mesh.

[0022] The delivery mechanism sequentially controls the coarse-grained quartz sand in the first storage bin to be fed to the bottom of the crucible mold to form a core layer, the medium-grained quartz particles in the second storage bin to be fed to the middle of the crucible mold to form a transition layer, and the nano-sized silicon powder in the third storage bin to be fed to the top of the crucible mold to form a surface layer, so as to achieve gradient particle gradation feeding.

[0023] Preferably, the electrode control module further includes:

[0024] Electrode drive mechanism: used to drive the individual electrodes in the electrode group to move in position and adjust their opening angle;

[0025] Status detection unit: used to acquire in real time the melting progress and temperature distribution information of the melt inside the crucible mold;

[0026] Control unit: It is connected to the electrode driving mechanism and the status detection unit by signal. The control unit generates adjustment instructions for the position and angle of each electrode in the electrode group according to the material processing progress information and temperature distribution information obtained by the status detection unit and sends them to the electrode driving mechanism. The electrode driving mechanism drives each electrode in the electrode group to move its position and adjust its opening angle according to the received adjustment instructions for the position and angle of each electrode.

[0027] Preferably, the control unit stores a three-dimensional electric field-thermal field coupled simulation model. The control unit obtains the melting progress information and temperature distribution information of the melt in the crucible mold from the state detection unit, calculates the position and angle parameters of each electrode in the electrode group through the three-dimensional electric field-thermal field coupled simulation model, and generates adjustment commands for the position and angle of each electrode in the electrode group based on the obtained position and angle parameters of each electrode in the electrode group.

[0028] Preferably, the staged extraction pipeline includes at least a first extraction branch located at the liquid level line at the top of the crucible mold and a second extraction branch located at the lower part of the crucible mold, and the diameter of the first extraction branch is larger than the diameter of the second extraction branch.

[0029] A method for preparing a low-bubble-density quartz crucible, using the system described above, includes the following steps:

[0030] Mold preparation steps: Prepare a crucible mold. The crucible mold is made of porous gradient composite material. The crucible mold has multiple non-uniformly distributed vent holes with different diameters. The inner wall of the crucible mold is integrated with multiple independent temperature control zones. The distribution of the temperature control zones is related to the distribution of the vent holes.

[0031] Gradient feeding step: Using the storage and distribution device, at least three different particle size ranges of quartz raw materials are layered and distributed from the bottom to the top of the crucible mold to form a gradient particle size distribution feeding from bottom to top;

[0032] Melting control steps: Place the electrodes in the electrode group into the melt of the crucible mold, and apply pulse current to each electrode in the electrode group through the pulse current generating unit;

[0033] In the vacuum evacuation step, during the melting process, the interior of the crucible mold is evacuated through a staged evacuation pipeline with an asymmetric pipe diameter. The intelligent frequency conversion control unit dynamically adjusts the evacuation parameters of the staged evacuation pipeline based on the feedback parameters of the pressure sensor and the gas flow sensor.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. This invention, through the synergistic effect of optimizing the permeability of the crucible mold, gradient feeding ratio, dynamic electrode control and intelligent vacuum pumping, can intervene in the entire process from bubble nucleation, migration, aggregation to removal. It can reduce the microbubble density in the liquid level line area at the top of the crucible (at -1mm) to ≤2 bubbles / cm², significantly reduce the average size and number of microbubbles, thereby reducing the bubble density at the liquid level line at the top of the quartz crucible and improving the stability and quality of subsequent crystal rod growth.

[0036] 2. This invention optimizes the surface wettability of the vent holes in the crucible mold by introducing porous gradient composite materials, suppresses the aggregation and retention of microbubbles in the liquid level region, and constructs a collaborative control model of crucible mold temperature and vent structure by combining dynamic airflow simulation technology, so as to ensure the long-term stability of the vent holes under high temperature and high pressure.

[0037] 3. This invention constructs a gradient particle size distribution system of "core layer-transition layer-surface layer", accelerates the polymerization and escape of bubbles through the surface tension effect, introduces composite slagging agent and surfactant as additives, optimizes the ratio through orthogonal experiments, reduces the viscosity of the melt, and promotes the merging and floating of micro bubbles.

[0038] 4. This invention achieves precise control of the electrode spatial position by designing a dynamic zoning and positioning technology for electrodes, based on the differences in the melting progress and temperature gradient in different areas of the crucible. At the same time, by designing a pulse current modulation technology, periodic high-frequency pulse currents are used to form an electromagnetic stirring effect in the melt, promoting the migration and breakup of bubbles.

[0039] 5. This invention designs a staged gas extraction pipeline with an asymmetric pipe diameter to form a layered and progressive gas extraction. By designing an intelligent variable frequency control unit, pressure sensors and gas flow sensors are deployed at key nodes of the staged gas extraction pipeline to monitor changes in the degassing rate in real time and dynamically adjust the extraction parameters of the staged gas extraction pipeline accordingly.

[0040] 6. This invention employs a porous gradient composite material crucible mold and zoned temperature control technology, effectively eliminating deformation caused by localized thermal stress, ensuring the long-term stability of the venting pores and the balance of melt surface tension. Dynamic electrode control and pulsed current technology optimize the melt temperature and flow field distribution, reducing melt disturbance and controlling liquid level fluctuations to extremely low levels, providing a clean and stable environment for crystal growth. Simultaneously, it breaks away from the traditional experience-based process model, establishing an electrode-current collaborative control model and a negative pressure flow rate prediction model, achieving precise, dynamic, and automated control of key parameters in the melting process, significantly improving process consistency and repeatability. Attached Figure Description

[0041] Appendix Figure 1 This is a block diagram of the system of the present invention for preparing low bubble density quartz crucibles;

[0042] Appendix Figure 2 This is a schematic diagram showing the distribution of the first and second temperature control zones in the mold permeability structure optimization module of the system for preparing low bubble density quartz crucibles according to the present invention.

[0043] Appendix Figure 3 This is a block diagram of the electrode control module in the system for preparing low bubble density quartz crucibles of the present invention.

[0044] Appendix Figure 4 This is a block diagram of the vacuum control module in the system for preparing low bubble density quartz crucibles of the present invention.

[0045] Appendix Figure 5 This is a flowchart of the method for preparing a low-bubble-density quartz crucible according to the present invention.

[0046] Explanation of the attached diagram labels: First temperature control zone 1, Second temperature control zone 2. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0049] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation on the embodiments. Moreover, the method and / or process should not be limited to the steps performed in the written order; those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0050] First, this specific embodiment provides a system for preparing low-bubble-density quartz crucibles, as shown in the attached figure. Figure 1 As shown, it includes a mold permeability structure optimization module, a material feeding ratio optimization module, an electrode control module, and a vacuum control module.

[0051] In this specific embodiment, the mold permeability structure optimization module includes a crucible mold made of porous gradient composite material. The crucible mold has multiple non-uniformly distributed vent holes with different diameters, and the inner wall of the crucible mold is integrated with multiple independently temperature-controlled zones. The distribution of the temperature-controlled zones is related to the distribution of the vent holes.

[0052] Specifically, the crucible mold is divided into multiple independently temperature-controlled zones along its axial and / or circumferential directions, and each temperature-controlled zone integrates independent heating and / or cooling elements;

[0053] The vent holes on the crucible mold are divided into multiple vent hole distribution areas, and multiple temperature control areas correspond one-to-one with multiple vent hole distribution areas. Among them, the pore size and opening density of the vent holes in at least two different vent hole distribution areas are not exactly the same.

[0054] For example, see attached Figure 2 As shown, the multiple independent temperature control zones integrated on the inner wall of the crucible mold include at least a first temperature control zone 1 corresponding to the liquid level line at the top of the quartz crucible, and a second temperature control zone 2 adjacent to the first temperature control zone 1; wherein, the set control temperature of the first temperature control zone 1 is higher than the set control temperature of the second temperature control zone 2.

[0055] Meanwhile, the pore density and pore diameter of the pore distribution area corresponding to the first temperature control zone 1 are both greater than those of the pore distribution area corresponding to the second temperature control zone 2.

[0056] For example, in the vent distribution area corresponding to the first temperature control zone 1, the vents are distributed in a matrix, and the distance between two adjacent vents is 25mm.

[0057] For example, the set temperatures of different temperature control zones on the crucible mold can be differentiated according to their functions in crucible melting. The basic principle is:

[0058] The area corresponding to the upper liquid level line (such as the first temperature control zone) is set to the highest temperature. The purpose is to indirectly reduce the viscosity of the thin layer of melt in close contact with the inner wall of the crucible mold by heating the crucible mold, thereby significantly promoting the detachment and rising speed of microbubbles.

[0059] The central area of ​​the crucible mold (such as the second temperature control zone) is set to a medium temperature. Its main function is to maintain stable heat transfer and melting process in the main melt area.

[0060] The bottom area of ​​the mold (such as the third temperature control zone) is set to a relatively low temperature. This helps stabilize the shape of the crucible bottom and creates a beneficial temperature gradient, which helps guide deep bubbles to migrate to the upper area.

[0061] Overall, the axial temperature setting of the crucible mold exhibits a gradient distribution, with higher temperatures at the top and lower temperatures at the bottom. The upper liquid level area is the key high-temperature zone for temperature control.

[0062] The distribution pattern of vents within the vent distribution area corresponding to different temperature control zones is as follows:

[0063] In the first temperature-controlled zone (upper liquid level area) set at high temperature, the vent holes are most densely distributed and have the largest pore size (e.g., Φ6mm pores arranged in a 25×25mm matrix). This results in the maximum exhaust flow and the lowest flow resistance, designed to quickly remove the large number of bubbles activated and detached due to the high temperature.

[0064] In the second and third temperature control zones (middle and bottom) set to medium and low temperatures, the distribution of vents gradually becomes sparser, and the vent diameter is correspondingly reduced (for example, using Φ4mm vents arranged in a 30×30mm or sparser array). This avoids unnecessary heat loss and airflow interference, and mainly serves to assist in airflow guidance and balance internal pressure.

[0065] In general, the distribution of vents follows the principle of high density and large pore size in high temperature zones and low density and small pore size in low temperature zones, so as to achieve optimal matching between temperature field regulation and the efficiency of physical exhaust channels.

[0066] Furthermore, in the specific design, the distribution of vent holes can be further optimized based on the deformation of different positions of the crucible mold during the preparation process. For example, for the crucible mold area predicted to undergo compressive deformation at the target melting temperature, the initial opening ratio of the vent holes in this area can be designed to be greater than the design opening ratio under the target working condition; while for the crucible mold area predicted to undergo tensile deformation at the target melting temperature, the initial opening ratio of the vent holes in this area is designed to be less than the design opening ratio under the target working condition. This ensures that the actual geometric parameters of the vent holes approach the design value when operating at the target melting temperature. For example, for the crucible mold area corresponding to the first temperature control zone, the initial opening ratio of its vent holes can be designed to be 3%-10% larger than the design aperture at the target melting temperature.

[0067] In this specific embodiment, the feeding ratio optimization module includes a storage and distribution device for realizing gradient particle size distribution feeding.

[0068] Specifically, the storage and distribution device includes a storage mechanism and a distribution mechanism. The storage mechanism includes at least three independent storage bins, which are used to store quartz raw materials of different particle size ranges. The distribution mechanism is used to control the quartz raw materials in the storage bins to be sequentially fed into the crucible mold according to a set ratio and layer sequence.

[0069] For example, the storage mechanism includes:

[0070] The first storage silo is used to store coarse-grained quartz sand with a particle size greater than 40 mesh.

[0071] The second storage bin is used to store medium-sized quartz particles with a particle size between 70 mesh and 120 mesh.

[0072] The third storage silo is used to store nano-sized silicon powder with a particle size of less than 325 mesh.

[0073] The distribution mechanism sequentially controls the feeding of coarse-grained quartz sand from the first storage bin to the bottom of the crucible mold to form a core layer, medium-grained quartz particles from the second storage bin to the middle of the crucible mold to form a transition layer, and nano-sized silicon powder from the third storage bin to the top of the crucible mold to form a surface layer, so as to achieve gradient particle gradation feeding.

[0074] The feed ratio is a fundamental factor affecting the bubble density at the top liquid level in the quartz crucible melting process. Through particle size distribution research, a gradient distribution system of "core layer - transition layer - surface layer" was constructed. The core layer uses coarse-grained quartz sand to form a skeletal structure, improving the initial permeability of the melt; the transition layer introduces medium-sized particles to fill the pores and optimize mass transfer efficiency; the surface layer uses nano-sized silica powder, which accelerates bubble aggregation and escape through surface tension. This layered design effectively avoids cavitation caused by the accumulation of single-size raw materials, allowing the melt to form orderly bubble migration channels in the early stages of melting. Simultaneously, composite slagging agents and surfactants are introduced as additives to reduce melt viscosity, promote the merging and floating of microbubbles, and optimize the additive ratio through orthogonal experiments, ensuring that it does not decompose and generate new bubbles at high temperatures while precisely controlling the surface properties of the melt.

[0075] In this specific embodiment, as shown in the appendix Figure 3 As shown, the electrode control module includes an electrode group with adjustable position and angle, and a pulse current generating unit that powers the electrode group.

[0076] Specifically, the electrode control module also includes:

[0077] Electrode drive mechanism: used to drive the individual electrodes in the electrode group to move in position and adjust their opening angle;

[0078] Status detection unit: used to acquire real-time information on the melting progress and temperature distribution of the melt inside the crucible mold; for example, by deploying infrared thermal imagers, high-temperature cameras and / or optical sensors at key locations in the crucible mold, real-time information on the melting progress (solid-liquid interface position) and temperature distribution of different areas inside the crucible mold can be acquired.

[0079] Control Unit: Connected to the electrode drive mechanism and the status detection unit, the control unit generates adjustment commands for the position and angle of each electrode in the electrode group based on the material processing progress information and temperature distribution information obtained by the status detection unit and sends them to the electrode drive mechanism. The electrode drive mechanism drives each electrode in the electrode group to move its position and adjust its opening angle according to the received adjustment commands for the position and angle of each electrode.

[0080] For example, the control unit stores a three-dimensional electric field-thermal field coupled simulation model. The control unit obtains the melting progress information and temperature distribution information of the melt in the crucible mold from the state detection unit, calculates the position and angle parameters of each electrode in the electrode group through the three-dimensional electric field-thermal field coupled simulation model, and generates adjustment commands for the position and angle of each electrode in the electrode group based on the obtained position and angle parameters of each electrode in the electrode group.

[0081] Specifically, during the melting process, infrared thermal imagers, high-temperature cameras, and / or optical sensors are used to acquire real-time information on the melting progress and temperature distribution in each area of ​​the crucible and send it to the control unit. The control unit inputs the received melting progress and temperature distribution information into a three-dimensional electric-thermal field coupled simulation model, and outputs a recommended adjustment scheme for electrode position, angle, and current parameters through simulation calculation. At the same time, it determines the area that needs enhanced heating and generates an adjustment command. The control unit sends the adjustment command to the electrode driving mechanism, which drives each electrode in the electrode group to move towards the area that needs enhanced heating or adjusts its angle, and simultaneously adjusts the current parameters applied to the electrode.

[0082] In practice, the melt can be divided into multiple logical zones, and an independent temperature target value can be set for each logical zone. By dynamically moving the position and angle of the electrodes, the measured temperature of each logical zone can be made to approach its corresponding target value.

[0083] In the quartz crucible melting process, electrode parameters and positions play a crucial role in regulating the melt temperature field, flow field distribution, and bubble behavior. Therefore, this scheme constructs a three-dimensional electric-thermal field coupled simulation model and develops a dynamic zoning and positioning technology for electrodes. Based on the differences in melting progress and temperature gradient in different regions of the crucible, precise control of the electrode spatial position is achieved. An adjustable electrode opening control system is introduced to establish a dynamic response relationship between the opening parameter and the melt resistivity. The gradual design of the arc-shaped electrode opening optimizes the uniformity of current distribution on the melt surface and suppresses microbubble nucleation caused by current concentration. Simultaneously, a pulsed current modulation technology is designed to replace the traditional constant current mode. Through periodically varying high-frequency pulsed current, a dynamic electromagnetic stirring effect is formed inside the melt, promoting bubble migration and breakup. Combined with online monitoring of melt conductivity, the pulse frequency is adjusted in real time to ensure that the current distribution matches the crucible melting process.

[0084] In this specific embodiment, as shown in the appendix Figure 4 As shown, the vacuum control module includes a staged pumping pipeline with an asymmetric pipe diameter and an intelligent frequency conversion control unit. The staged pumping pipeline is equipped with multiple pressure sensors and gas flow sensors. The intelligent frequency conversion control unit dynamically adjusts the pumping parameters of the staged pumping pipeline based on the feedback parameters of the pressure sensors and gas flow sensors.

[0085] Specifically, the staged evacuation pipeline includes at least a first evacuation branch located at the liquid level line at the top of the crucible mold and a second evacuation branch located at the lower part of the crucible mold, wherein the diameter of the first evacuation branch is larger than the diameter of the second evacuation branch.

[0086] Specifically, the intelligent variable frequency control unit includes:

[0087] The data acquisition module is used to acquire real-time data from pressure sensors and gas flow sensors installed at key nodes of the staged extraction pipeline.

[0088] The control and execution module is connected to the vacuum pump and the regulating valve. The regulating valve is installed on the staged gas pipeline and is used to regulate the speed of the vacuum pump and / or regulate the opening of the valve.

[0089] The processing module is connected to the data acquisition module and the control execution module respectively. The processing module issues control commands based on the real-time data from the pressure sensor and gas flow sensor obtained by the data acquisition module. The control execution module then adjusts the speed of the vacuum pump and the opening of the regulating valve according to the control commands, thereby realizing the regulation of the pumping volume of the staged pumping pipeline.

[0090] For example, the processing module also stores or runs a negative pressure flow rate prediction model, which takes real-time data from pressure sensors and gas flow sensors as input and the predicted trend of melt degassing rate as output; the processing module generates control commands based on the output trend of degassing rate.

[0091] Vacuum system layout is the core path to achieving efficient gas removal and dynamic equilibrium during crucible melting. This scheme, based on the flow characteristics of the melt and the bubble migration law, designs an asymmetric pipe diameter tiered system. Large-radius pipes are used in the gas-liquid interface region of the melt surface to reduce flow resistance, while small-diameter pipes are configured in the deeper regions of the melt to enhance suction efficiency, forming a layered, progressive gas extraction. Simultaneously, an intelligent variable frequency control system is developed to replace the traditional fixed-flow-rate pumping mode. By deploying pressure sensors and gas flow monitoring devices at key pipe nodes, changes in the melt degassing rate are captured in real time, establishing a negative pressure flow rate prediction model to dynamically adjust the vacuum pump speed and valve opening.

[0092] In addition, this specific embodiment also provides a method for preparing a low-bubble-density quartz crucible, using the above-described system for preparing a low-bubble-density quartz crucible, as shown in the attached figure. Figure 5 As shown, it includes the following steps:

[0093] Step S1) Mold preparation steps: Prepare a crucible mold. The crucible mold is made of porous gradient composite material. The crucible mold has multiple non-uniformly distributed vent holes with different diameters. The inner wall of the crucible mold is integrated with multiple independent temperature control zones. The distribution of the temperature control zones is related to the distribution of the vent holes.

[0094] Step S2) Gradient feeding step: Using a storage and distribution device, at least three different particle size ranges of quartz raw materials are layered and distributed from the bottom to the top of the crucible mold to form a gradient particle size distribution feeding from bottom to top.

[0095] Step S3) Melting control step: Place the electrodes in the electrode group into the melt of the crucible mold, and apply pulse current to each electrode in the electrode group through the pulse current generating unit;

[0096] Step S4) Vacuum evacuation step: During the melting process, the inside of the crucible mold is evacuated through a staged evacuation pipeline with an asymmetric pipe diameter. The intelligent frequency conversion control unit dynamically adjusts the evacuation parameters of the staged evacuation pipeline based on the feedback parameters of the pressure sensor and the gas flow sensor.

[0097] Compared with existing technologies, this invention, through the synergistic effect of optimizing the permeability of the crucible mold, gradient feeding ratio, dynamic electrode control, and intelligent vacuum pumping, can intervene in the entire process from bubble nucleation, migration, aggregation to removal. This reduces the microbubble density in the upper liquid level region (at -1 mm) of the crucible to ≤2 bubbles / cm², significantly reducing the average size and number of microbubbles. This results in lowering the bubble density at the upper liquid level of the quartz crucible, improving the stability and quality of subsequent crystal growth. This invention introduces porous gradient composite materials to optimize the surface wettability of the crucible mold's permeable pores, inhibiting the aggregation and retention of microbubbles in the liquid level region. Combined with dynamic airflow simulation technology, a synergistic control model of crucible mold temperature and permeability structure is constructed to ensure the long-term stability of the permeable pores under high temperature and high pressure. This invention constructs a gradient particle size distribution system of "core layer - transition layer - surface layer," accelerating bubble aggregation and escape through surface tension effect. Composite slagging agents and surfactants are introduced as additives, and the ratio is optimized through orthogonal experiments to reduce melt viscosity and promote the merging and floating of microbubbles. This invention employs a dynamic zoning and positioning technology for electrodes, precisely controlling their spatial position based on differences in melting progress and temperature gradients in different areas of the crucible. Simultaneously, it utilizes pulsed current modulation technology, employing periodic high-frequency pulsed currents to create an electromagnetic stirring effect within the melt, promoting bubble migration and breakup. Furthermore, it designs a tiered gas extraction pipeline with asymmetrical pipe diameters, achieving layered and progressive gas extraction. An intelligent frequency conversion control unit deploys pressure and gas flow sensors at key nodes of the tiered extraction pipeline to monitor degassing rate changes in real time and dynamically adjust the extraction parameters accordingly. Finally, the invention utilizes a porous gradient composite material crucible mold and zoning temperature control technology, effectively eliminating deformation caused by localized thermal stress, ensuring the long-term stability of the vents and the balance of melt surface tension. Dynamic electrode control and pulsed current technology optimize the melt temperature and flow field distribution, reducing melt disturbance and controlling liquid level fluctuations to extremely low levels, providing a clean and stable environment for crystal growth. At the same time, it breaks away from the traditional experience-based process model. By establishing an electrode-current collaborative control model and a negative pressure flow rate prediction model, it achieves precise, dynamic, and automated control of key parameters in the melting process, significantly improving the consistency and repeatability of the process.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A system for preparing low-bubble-density quartz crucibles, characterized in that, It includes a mold permeability structure optimization module, a material feeding ratio optimization module, an electrode control module, and a vacuum control module; The mold permeability structure optimization module includes a crucible mold made of porous gradient composite material. The crucible mold has multiple non-uniformly distributed permeable holes with different diameters. The inner wall of the crucible mold is integrated with multiple independently temperature-controlled zones. The distribution of the temperature-controlled zones is related to the distribution of the permeable holes. The feeding ratio optimization module includes a storage and distribution device for realizing gradient particle size distribution feeding; The electrode control module includes an electrode group with adjustable position and angle, and a pulse current generating unit that powers the electrode group. The vacuum control module includes a staged extraction pipeline with an asymmetric pipe diameter and an intelligent frequency conversion control unit. The staged extraction pipeline is equipped with multiple pressure sensors and gas flow sensors. The intelligent frequency conversion control unit dynamically adjusts the extraction parameters of the staged extraction pipeline based on the feedback parameters of the pressure sensors and gas flow sensors.

2. The system for preparing low-bubble-density quartz crucibles according to claim 1, characterized in that, The crucible mold is divided into multiple independently temperature-controlled zones along its axial and / or circumferential directions, and each temperature-controlled zone integrates independent heating and / or cooling elements. The vent holes on the crucible mold are divided into multiple vent hole distribution areas, and the multiple temperature control areas correspond one-to-one with the multiple vent hole distribution areas. Among them, the pore size and opening density of the vent holes in at least two different vent hole distribution areas are not exactly the same.

3. The system for preparing low-bubble-density quartz crucibles according to claim 2, characterized in that, The multiple independent temperature control zones integrated on the inner wall of the crucible mold include at least a first temperature control zone corresponding to the liquid level line at the top of the quartz crucible, and a second temperature control zone adjacent to the first temperature control zone. The pore density and pore diameter of the pore distribution area corresponding to the first temperature control zone are both greater than those of the pore distribution area corresponding to the second temperature control zone.

4. The system for preparing low-bubble-density quartz crucibles according to claim 3, characterized in that, In the vent distribution area corresponding to the first temperature control zone, the vents are distributed in a matrix, and the distance between two adjacent vents is 25mm. The set control temperature of the first temperature control zone is higher than the set control temperature of the second temperature control zone.

5. The system for preparing low-bubble-density quartz crucibles according to claim 1, characterized in that, The storage and distribution device includes a storage mechanism and a distribution mechanism. The storage mechanism includes at least three independent storage bins, which are used to store quartz raw materials with different particle size ranges. The distribution mechanism is used to control the quartz raw materials in the storage bins to be sequentially added to the crucible mold according to a set ratio and layer sequence.

6. The system for preparing a low-bubble-density quartz crucible according to claim 5, characterized in that, The storage mechanism includes: The first storage silo is used to store coarse-grained quartz sand with a particle size greater than 40 mesh. The second storage bin is used to store medium-sized quartz particles with a particle size between 70 mesh and 120 mesh. The third storage silo is used to store nano-sized silicon powder with a particle size of less than 325 mesh. The delivery mechanism sequentially controls the coarse-grained quartz sand in the first storage bin to be fed to the bottom of the crucible mold to form a core layer, the medium-grained quartz particles in the second storage bin to be fed to the middle of the crucible mold to form a transition layer, and the nano-sized silicon powder in the third storage bin to be fed to the top of the crucible mold to form a surface layer, so as to achieve gradient particle gradation feeding.

7. The system for preparing a low-bubble-density quartz crucible according to claim 1, characterized in that, The electrode control module further includes: Electrode drive mechanism: used to drive the individual electrodes in the electrode group to move in position and adjust their opening angle; Status detection unit: used to acquire in real time the melting progress and temperature distribution information of the melt inside the crucible mold; Control unit: It is connected to the electrode driving mechanism and the status detection unit by signal. The control unit generates adjustment instructions for the position and angle of each electrode in the electrode group according to the material processing progress information and temperature distribution information obtained by the status detection unit and sends them to the electrode driving mechanism. The electrode driving mechanism drives each electrode in the electrode group to move its position and adjust its opening angle according to the received adjustment instructions for the position and angle of each electrode.

8. The system for preparing a low-bubble-density quartz crucible according to claim 7, characterized in that, The control unit stores a three-dimensional electric field-thermal field coupled simulation model. The control unit obtains the melting progress information and temperature distribution information of the melt in the crucible mold from the state detection unit. It calculates the position and angle parameters of each electrode in the electrode group through the three-dimensional electric field-thermal field coupled simulation model, and generates adjustment commands for the position and angle of each electrode in the electrode group based on the obtained position and angle parameters.

9. The system for preparing a low-bubble-density quartz crucible according to claim 1, characterized in that, The staged extraction pipeline includes at least a first extraction branch located at the liquid level line at the top of the crucible mold and a second extraction branch located at the lower part of the crucible mold, wherein the diameter of the first extraction branch is larger than the diameter of the second extraction branch.

10. A method for preparing a low-bubble-density quartz crucible, characterized in that, The system for preparing a low-bubble-density quartz crucible as described in claim 1 includes the following steps: Mold preparation steps: Prepare a crucible mold. The crucible mold is made of porous gradient composite material. The crucible mold has multiple non-uniformly distributed vent holes with different diameters. The inner wall of the crucible mold is integrated with multiple independent temperature control zones. The distribution of the temperature control zones is related to the distribution of the vent holes. Gradient feeding step: Using the storage and distribution device, at least three different particle size ranges of quartz raw materials are layered and distributed from the bottom to the top of the crucible mold to form a gradient particle size distribution feeding from bottom to top; Melting control steps: Place the electrodes in the electrode group into the melt of the crucible mold, and apply pulse current to each electrode in the electrode group through the pulse current generating unit; In the vacuum evacuation step, during the melting process, the interior of the crucible mold is evacuated through a staged evacuation pipeline with an asymmetric pipe diameter. The intelligent frequency conversion control unit dynamically adjusts the evacuation parameters of the staged evacuation pipeline based on the feedback parameters of the pressure sensor and the gas flow sensor.

Images