Temperature control system and method for continuous Czochralski single crystal shoulder expanding process
By constructing a temperature control model and adjusting the feeding amount and heater power in real time, the temperature fluctuation problem in the CCZ continuous straight pulling shoulder expansion stage was solved, stable crystal growth was achieved and the shoulder expansion survival rate was improved.
Patent Information
- Application Number
- CN202510857903.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-09-16
AI Technical Summary
During the CCZ continuous straight pulling and shoulder expansion stage, when granular silicon is continuously added, the feeding amount and the cooling amount are set as fixed parameters, which leads to melt temperature fluctuations and unstable crystal growth.
A temperature control system is used, including the single crystal furnace thermal field, feeding device and data acquisition device. By constructing a temperature control model, the feeding amount and heater power are adjusted in real time to achieve heat balance and stabilize the melt temperature.
By dynamically controlling feeding and cooling, the melt temperature is kept stable, the shoulder expansion survival rate is improved, and the stability and efficiency of crystal growth are ensured.
Smart Images
Figure CN120649142A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of single crystal silicon manufacturing, and in particular to a temperature control system and method for a continuous Czochralski single crystal shoulder expansion process. Background Art
[0002] CCZ is an improved Czochralski single crystal silicon growth technology that replaces the intermittent feeding of the traditional CZ method with continuous feeding. It can continuously replenish polysilicon raw materials (such as granular silicon) during the crystal pulling process, achieving the continuity of the crystal growth process, thereby improving production efficiency and crystal resistivity uniformity.
[0003] The crystal pulling process includes welding, seeding, shoulder expansion, equal diameter, and finishing. The shoulder expansion process gradually increases the crystal diameter through continuous cooling until the melt temperature remains constant after the shoulder expansion is completed.
[0004] Problems with the existing technology: During the CCZ continuous straight pulling and shoulder expansion stage, when granular silicon is continuously added, a dynamic temperature control model is not established, and the addition amount and the cooling amount are both fixed parameter settings. During the melting process of the granular silicon solid added to the crucible, the temperature of the granular silicon rises and the heat absorbed by the phase change causes the melt temperature to fluctuate, making the crystal growth unstable.
[0005] Therefore, it is necessary to invent a temperature control system and method for a continuous Czochralski single crystal shoulder expansion process to solve the above problems. Summary of the Invention
[0006] The purpose of the present invention is to provide a temperature control system and method for a continuous Czochralski single crystal shoulder expansion process, which solves the problem that when granular silicon is continuously added, the feeding amount and the cooling amount are both fixed parameter settings. During the melting process of granular silicon solid added to the crucible, the temperature of the granular silicon rises and the heat absorbed by the phase change causes the melt temperature to fluctuate, making the crystal growth unstable.
[0007] To achieve this object, the present invention adopts the following technical solutions: Provided is a temperature control system for a continuous Czochralski single crystal shoulder expansion process, comprising a single crystal furnace thermal field, a feeding device, a data acquisition device, and a calculation module; A heater for maintaining the temperature of the thermal field is provided inside the thermal field of the single crystal furnace; The feeding device is provided with a feeding module inside which can quantitatively feed materials according to feeding parameters; The feeding module is used to control the feeding mass Δm per unit time and stabilize the feeding speed; The data acquisition device is used to collect the temperature of the granular silicon inside the feeding device and the temperature of the molten silicon in the thermal field of the single crystal furnace, and calculate the temperature difference ΔT between the two; The calculation module uses Δm and ΔT and related parameters of granular silicon to construct a temperature control model and calculates the power change value according to the input feeding amount parameter and the cooling amount parameter; The temperature control model includes the total cooling amount in the shoulder expansion stage and the feeding speed of the corresponding node, wherein the heat required to heat and melt the granular silicon added to the crucible and the heater power reduction value are equal to the total cooling amount Qtotal.
[0008] As a preferred solution for a temperature control system in a continuous Czochralski single crystal shoulder expansion process, the granular silicon-related parameters for constructing a temperature control model include the granular silicon specific heat capacity Cp and the unit mass solid melting heat ΔH. The calculation module calculates the granular silicon melting latent heat Lf using Δm and ΔH. The calculation formula for the granular silicon melting latent heat Lf is Lf=Δm*ΔH. The heat ΔQ of the granular silicon heated to the molten silicon temperature per unit time is calculated by Cp, Δm and ΔT; the calculation formula of the heat ΔQ of the granular silicon heated to the molten silicon temperature per unit time is ΔQ=Cp*Δm*ΔT; The total heat Q material of the granular silicon melt is calculated by ΔQ and Lf; finally, the heater cooling difference Q plus is obtained by subtracting the total cooling amount Q total from Q material; the calculation formula for the total heat Q material of the granular silicon melt is Q material = ΔQ + Lf; the calculation formula for the heater cooling difference Q plus is Q plus = Q total - Q material.
[0009] As a preferred solution for the temperature control system of a continuous CZ single crystal shoulder expansion process, the temperature control model can calculate the power adjustment amount based on the feed amount. The calculation formula is Qadd = Qtotal - (Cp*Δm*ΔT + Cp*Δm*ΔT). During the CCZ crystal pulling process, the feed amount cannot exceed the weight of the crystal removed by shoulder expansion.
[0010] As a preferred solution of a temperature control method for a continuous Czochralski single crystal shoulder expansion process, the method comprises the following steps: Step S1: During the shoulder expansion phase, a temperature control model is established. The total temperature drop includes the temperature drop caused by the reduction of heater power and the addition of granular silicon. Step S2: The corresponding feeding amount can be set according to the actual shoulder expansion process; Step S3: When adding materials at different stages, the calculation module calculates the feeding amount parameters through the temperature control model, obtains the modified heater power, and achieves thermal field temperature balance.
[0011] As an optimal solution for the temperature control method of a continuous CZ single crystal shoulder expansion process, a variety of different shoulder expansion temperature control models are established according to the sizes of different crystal rods and different shoulder expansion processes. The common crystal rod sizes are 10 inches, 11 inches, and 12 inches; the common shoulder expansion modes are flat shoulder and tower shoulder.
[0012] As an optimal solution for the temperature control method of a continuous Czochralski single crystal shoulder expansion process, any node in the shoulder expansion temperature control model can be set as a starting node for granular silicon feeding, and the calculation module calculates the corresponding power value based on the actual feeding amount parameters.
[0013] As a preferred solution for a temperature control method of a continuous Czochralski single crystal shoulder expansion process, the particle size of the granular silicon in the feeding device ranges from 0.15 mm to 5 mm.
[0014] As a preferred solution for a temperature control method of a continuous Czochralski single crystal shoulder expansion process, the temperature drop caused by adding granular silicon cannot be higher than the total temperature drop of the shoulder expansion.
[0015] The beneficial effects of the present invention are as follows: through the setting of the temperature control model, compared with the premise method of the traditional fixed cooling curve, by setting the starting granular silicon feeding node at any node in the temperature control model, the temperature rise of the granular silicon in the furnace and the heat absorbed by the phase change can be compensated for in real time. At any time point in the shoulder expansion stage, the feeding process and the like can be triggered, and there will be no large temperature fluctuations during the feeding process. By reducing the heater power and controlling the feeding amount, the cooling amplitude can be superimposed and controlled to keep the melt cooling slope consistent. On the premise of ensuring the crystal growth dynamics, stable shoulder expansion can be achieved and the shoulder expansion survival rate can be improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.
[0017] Figure 1 It is a structural schematic diagram of the shoulder expansion process described in the present invention.
[0018] Figure 2 This is a schematic diagram of a 10-inch shoulder expansion and cooling model.
[0019] Figure 3 It is a schematic diagram of the 12-inch shoulder expansion cooling model.
[0020] Figure 4 It is a simplified schematic diagram of the temperature control system of the present invention.
[0021] 1. Single crystal furnace thermal field; 2. Feeding device; 3. Calculation module. DETAILED DESCRIPTION
[0022] The technical solution of the present invention is further illustrated below through specific implementation methods.
[0023] Among them, the drawings are only used for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.
[0024] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inside", "outside" and the like indicate an orientation or position relationship based on the orientation or position relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.
[0025] In the description of the present invention, unless otherwise expressly specified or limited, when the term "connection" or the like appears to indicate a connection relationship between components, such term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be internal communication between two components or an interaction between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.
[0026] Referring to the conventional RCZ shoulder expansion mature cooling process, a CCZ shoulder expansion temperature control model is established, which includes the total cooling amount in the shoulder expansion stage and the feeding speed of the corresponding node. The heat required to heat and melt the granular silicon added to the crucible and the reduction in heater power are equal to the total cooling amount.
[0027] Total cooling amount = heat absorbed by new material + heater power reduction Q total = Q material + Q extra The heat absorbed by the new material = the heat of the granular silicon temperature rise + the latent heat of solid melting Q material = ΔQ + Lf ΔQ=Δm*Cp*ΔT Lf=Δm*ΔH According to the above shoulder expansion temperature control model, the power adjustment amount can be calculated according to the feeding speed. In the CCZ crystal pulling process, the feeding amount is ≤ the weight of the crystal pulled out of the shoulder expansion, ensuring that the melt temperature can be controlled during the shoulder expansion process and improving the shoulder expansion survival rate. The present invention provides a temperature control system for a continuous Czochralski single crystal shoulder expansion process, comprising a single crystal furnace thermal field, a feeding device, a data acquisition device, and a calculation module; A heater for maintaining the temperature of the thermal field is provided inside the thermal field of the single crystal furnace; The feeding device is provided with a feeding module inside which can quantitatively feed materials according to feeding parameters; The feeding module is used to control the feeding mass Δm per unit time and stabilize the feeding speed; The data acquisition device is used to collect the temperature of the granular silicon inside the feeding device and the temperature of the molten silicon in the thermal field of the single crystal furnace, and calculate the temperature difference ΔT between the two; The calculation module uses Δm and ΔT and related parameters of granular silicon to construct a temperature control model and calculates the power change value according to the input feeding amount parameter and the cooling amount parameter; The temperature control model includes the total cooling amount in the shoulder expansion stage and the feeding speed of the corresponding node, wherein the heat required to heat and melt the granular silicon added to the crucible and the heater power reduction value are equal to the total cooling amount Qtotal.
[0028] The relevant parameters of granular silicon used to construct the temperature control model include the specific heat capacity Cp of granular silicon and the heat of solid melting per unit mass ΔH. The calculation module calculates the latent heat of melting Lf of granular silicon through Δm and ΔH. The calculation formula for the latent heat of melting Lf of granular silicon is Lf=Δm*ΔH. The heat ΔQ of the granular silicon heated to the molten silicon temperature per unit time is calculated by Cp, Δm and ΔT; the calculation formula of the heat ΔQ of the granular silicon heated to the molten silicon temperature per unit time is ΔQ=Cp*Δm*ΔT; The total heat Q material of the granular silicon melt is calculated by ΔQ and Lf; finally, the heater cooling difference Q plus is obtained by subtracting the total cooling amount Q total from Q material; the calculation formula for the total heat Q material of the granular silicon melt is Q material = ΔQ + Lf; the calculation formula for the heater cooling difference Q plus is Q plus = Q total - Q material. The single crystal furnace heat field is used to accommodate molten silicon and pull single crystal silicon. It is equipped with a heater to maintain the temperature of the heat field. The feeding device is filled with granular silicon. During the crystal pulling and shoulder expansion process, the melt temperature continues to decrease to ensure the growth momentum of the crystal. The heater power is dynamically adjusted through the calculation module to achieve dynamic balance of the melt temperature. The temperature control model can calculate the power adjustment amount according to the feeding amount; The calculation formula is Qadd = Qtotal - (Cp*Δm*ΔT + Cp*Δm*ΔT). During the CCZ crystal pulling process, the feed amount cannot exceed the weight of the crystal pulled out of the shoulder expansion. This ensures that the melt temperature can be controlled during the shoulder expansion process and improves the shoulder expansion survival rate. A temperature control method for a continuous Czochralski single crystal shoulder expansion process comprises the following steps: Step S1: During the shoulder expansion phase, a temperature control model is established. The total temperature drop includes the temperature drop caused by the reduction of heater power and the addition of granular silicon. Step S2: The corresponding feeding amount can be set according to the actual shoulder expansion process; Step S3: When adding materials at different stages, the calculation module calculates the feeding amount parameters through the temperature control model, obtains the modified heater power, and achieves thermal field temperature balance.
[0029] Different shoulder expansion temperature control models are established based on different ingot sizes and different shoulder expansion processes. Common ingot sizes are 10 inches, 11 inches, and 12 inches; common shoulder expansion modes are flat shoulder and tower shoulder. The temperature control models are shown in Tables 1 and 2. Any node in the shoulder expansion temperature control model can be set as the starting point for granular silicon feeding. The calculation module calculates the corresponding power value based on the actual feeding parameters. By setting any node as the starting point for granular silicon feeding in the temperature control model, the corresponding heater power modification can be calculated at different feeding stages. This maintains stable melt cooling, achieves stable shoulder expansion, and improves the shoulder expansion survival rate.
[0030] The particle size of the granular silicon in the feeding device ranges from 0.15mm to 5mm. If the particle size is too small, it is easy to stick to the feeding pipe and cause blockage; if the particle size is too large, it will cause large fluctuations in the feeding speed and melt temperature. The cooling amount brought about by adding granular silicon cannot be higher than the total cooling amount of the shoulder expansion, so as to reduce the power of the heater, reduce the temperature fluctuation of the melt, and reduce power consumption by reducing power.
[0031] The present invention, through the setting of the temperature control model, is compared with the premise method of the traditional fixed cooling curve. By setting the starting granular silicon feeding node at any node in the temperature control model, it is possible to perform thermal balance compensation for the temperature increase of granular silicon and the heat absorbed by phase change in the furnace in real time. At any time point in the shoulder expansion stage, the feeding process and the like can be triggered, and there will be no large temperature fluctuations during the feeding process. By reducing the heater power and controlling the feeding amount, the cooling amplitude can be superimposed and controlled to keep the melt cooling slope consistent. On the premise of ensuring the crystal growth dynamics, stable shoulder expansion can be achieved and the shoulder expansion survival rate can be improved.
[0032] It should be noted that the above-described specific embodiments are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that various modifications, equivalent substitutions, and variations may be made to the present invention. However, as long as these modifications do not depart from the spirit of the present invention, they are intended to be within the scope of protection of the present invention. Furthermore, certain terms used in the specification and claims of this application are not intended to be limiting and are provided solely for ease of description.
Claims
1. A temperature control system for a continuous Czochralski single crystal shoulder expansion process, characterized by: It includes single crystal furnace thermal field, feeding device, data acquisition device and calculation module; A heater for maintaining the temperature of the thermal field is provided inside the thermal field of the single crystal furnace; The feeding device is provided with a feeding module inside which can quantitatively feed materials according to feeding parameters; The feeding module is used to control the feeding mass Δm per unit time and stabilize the feeding speed; The data acquisition device is used to collect the temperature of the granular silicon inside the feeding device and the temperature of the molten silicon in the thermal field of the single crystal furnace, and calculate the temperature difference ΔT between the two; The calculation module uses Δm and ΔT and related parameters of granular silicon to construct a temperature control model and calculates the power change value according to the input feeding amount parameter and the cooling amount parameter; The temperature control model includes the total cooling amount in the shoulder expansion stage and the feeding speed of the corresponding node, wherein the heat required to heat and melt the granular silicon added to the crucible and the heater power reduction value are equal to the total cooling amount Qtotal.
2. The temperature control system for a continuous Czochralski single crystal shoulder expansion process according to claim 1, characterized in that: The relevant parameters of granular silicon used to construct the temperature control model include the specific heat capacity Cp of granular silicon and the heat of solid melting per unit mass ΔH. The calculation module calculates the latent heat of melting Lf of granular silicon through Δm and ΔH. The calculation formula for the latent heat of melting Lf of granular silicon is Lf=Δm*ΔH. The heat ΔQ of the granular silicon heated to the molten silicon temperature per unit time is calculated by Cp, Δm and ΔT; the calculation formula of the heat ΔQ of the granular silicon heated to the molten silicon temperature per unit time is ΔQ=Cp*Δm*ΔT; The total heat Q material of the granular silicon melt is calculated by ΔQ and Lf; finally, the heater cooling difference Q plus is obtained by subtracting the total cooling amount Q total from Q material; the calculation formula for the total heat Q material of the granular silicon melt is Q material = ΔQ + Lf; the calculation formula for the heater cooling difference Q plus is Q plus = Q total - Q material.
3. The temperature control system for a continuous Czochralski single crystal shoulder expansion process according to claim 2, characterized in that: The temperature control model can calculate the power adjustment amount according to the feeding amount. The calculation formula is Qadd = Qtotal - (Cp*Δm*ΔT + Cp*Δm*ΔT). In the CCZ crystal pulling process, the feeding amount cannot be higher than the weight of the crystal pulled out by shoulder expansion.
4. A temperature control method for a continuous Czochralski single crystal shoulder expansion process, characterized in that: The temperature control system according to claim 1-3 comprises the following steps: Step S1: During the shoulder expansion phase, a temperature control model is established. The total temperature drop includes the temperature drop caused by the reduction of heater power and the addition of granular silicon. Step S2: The corresponding feeding amount can be set according to the actual shoulder expansion process; Step S3: When adding materials at different stages, the calculation module calculates the feeding amount parameters through the temperature control model, obtains the modified heater power, and achieves thermal field temperature balance.
5. The temperature control method for a continuous Czochralski single crystal shoulder expansion process according to claim 4, characterized in that: A variety of shoulder expansion temperature control models are established based on different crystal ingot sizes and different shoulder expansion processes. The most common crystal ingot sizes are 10 inches, 11 inches, and 12 inches; the most common shoulder expansion modes are flat shoulder and tower shoulder.
6. The temperature control method for a continuous Czochralski single crystal shoulder expansion process according to claim 5, characterized in that: Any node in the shoulder expansion temperature control model can be set as a starting node for granular silicon feeding, and the calculation module calculates the corresponding power value based on the actual feeding amount parameters.
7. The temperature control method for a continuous Czochralski single crystal shoulder expansion process according to claim 4, characterized in that: The particle size of the granular silicon in the feeding device ranges from 0.15 mm to 5 mm.
8. The temperature control method for a continuous Czochralski single crystal shoulder expansion process according to claim 4, characterized in that: The cooling amount brought about by the addition of granular silicon cannot be higher than the total cooling amount of shoulder expansion.