Rapid cooling method for shutdown of single crystal furnace

Abstract

The invention relates to a single crystal furnace shutdown rapid cooling method, which is mainly used for rapidly cooling the interior of a furnace body after single crystal growth is finished, and comprises the following steps: extracting residual gas in the single crystal furnace and treating the residual gas; the treated gas is conveyed back into the single crystal furnace; and the steps are alternated until the temperature of the extracted gas meets the requirement. According to the method, the hot air flow in the furnace body of the single crystal furnace after furnace shutdown is recycled, the hot air flow is sequentially subjected to filtering treatment, cooling treatment and heat exchange treatment to reach the standard that the hot air flow can be introduced into the single crystal furnace for use, and then the treated air flow is introduced into the furnace body of the single crystal furnace so as to achieve the purpose of quickly cooling a thermal field, shorten the furnace shutdown cooling time and improve the production efficiency. The unit capacity is increased, and the effects of increasing the yield and increasing the efficiency are achieved. Meanwhile, the auxiliary chamber is pressurized by replacing inert gas argon with filtered gas, so that the working hours of equipment are reduced, the working efficiency is improved, and the use amount of argon is reduced; the working efficiency can be improved, the effect of increasing production and efficiency is achieved, and automation is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of Czochralski single crystal production, and in particular relates to a method for rapid cooling of a single crystal furnace when it is shut down. Background Art

[0002] The process of producing silicon single crystals by the Czochralski method is completed in a single crystal furnace. After the production of the existing single crystal furnace is completed, the heat field needs to be cooled, cleaned, and re-fired. Since the entire heat field structure of the existing single crystal furnace heat field is all covered with carbon-based insulation materials, it is ensured that the heat is lost as little as possible during the entire production process, thereby ensuring the constant temperature of the entire heat field environment. After the furnace is stopped and the heating element is turned off, the residual heat in the heat field components can only be transferred and radiated to the furnace bottom plate, furnace barrel, furnace cover, etc. by the natural heat of the insulation material, and then the heat on the surface of the furnace bottom plate, furnace barrel, furnace cover, etc. is taken away by circulating water. The heat dissipation is slow and it takes 10 hours of natural cooling. As the single crystal heat field increases, the cooling time of the heat field furnace is extended to 10 to 12 hours. The longer the cooling waiting time, the lower the production efficiency. In addition, after 10 to 12 hours of natural cooling, the temperature of the heat field is still very high. When the furnace is dismantled, the heat field components are prone to local oxidation due to the high temperature, resulting in accelerated aging of the heat field and accelerated loss of graphite parts, further bringing about the problem of high production costs.

[0003] At present, the single crystal furnace shutdown cooling in the industry is still carried out through the cooling circulation system of the single crystal furnace body. The disadvantage is that there are requirements for the flow rate and water temperature of the cooling water. The water temperature cannot be too low and the water flow cannot be too large, otherwise it will cause production accidents such as stick explosion, and will also increase the power consumption of the single crystal furnace during operation and increase production costs. Therefore, the water temperature and flow must be controlled in a relatively appropriate range to ensure process stability. Water temperature and flow are important factors in heat exchange. If the process stability is guaranteed, the cooling effect of the shutdown cannot be guaranteed, the cooling speed is slow, and the flexibility is poor. Summary of the invention

[0004] The present application provides a method for rapid cooling of a single crystal furnace after shutdown, which solves the technical problems of unstable crystal pulling quality and serious loss of man-hours caused by the existing manual observation of equal diameter deformation.

[0005] In order to solve at least one of the above technical problems, the technical solution adopted in this application is:

[0006] A method for rapid cooling of a single crystal furnace after shutdown, mainly for rapid cooling of the furnace body after the single crystal growth is completed, the steps comprising:

[0007] Extract the remaining gas in the single crystal furnace and treat it;

[0008] The treated gas is then fed back into the single crystal furnace;

[0009] Repeat the above steps until the extracted gas temperature meets the requirements.

[0010] Furthermore, before extracting the remaining gas in the single crystal furnace, the method also includes closing the step of introducing high-purity gas into the furnace body.

[0011] Furthermore, the pump body used for controlling the stopping of the introduction of high-purity gas into the furnace body and the pump body used for controlling the extraction of the remaining gas in the single crystal furnace are different.

[0012] Furthermore, the residual gas in the extracted single crystal furnace is processed, specifically:

[0013] Filter the remaining gas first;

[0014] The filtered gas is then cooled down;

[0015] The cooled gas is then transferred to the secondary chamber.

[0016] Furthermore, the temperature of the gas transmitted to the secondary chamber is -10°C to 10°C.

[0017] Furthermore, extracting the remaining gas in the single crystal furnace and transmitting the cooled gas to the sub-chamber are synchronous operations.

[0018] Furthermore, while extracting the residual gas in the single crystal furnace, the temperature of the extracted residual gas is monitored.

[0019] Furthermore, the temperature of the extracted gas meets the requirement. For example, if the temperature of the remaining gas extracted from the furnace body meets the standard cleaning temperature, the introduction of the treated gas into the auxiliary chamber may be stopped. The standard cleaning temperature is 180-220°C.

[0020] Furthermore, the method also includes monitoring the gas pressure inside the single crystal furnace body.

[0021] Furthermore, in the process of extracting and treating the remaining gas in the single crystal furnace and returning the treated gas to the single crystal furnace, the main chamber and the sub-chamber in the single crystal furnace are always in an interconnected state.

[0022] A method for rapid cooling of a single crystal furnace after shutdown designed in this application is adopted to recycle the hot air flow in the furnace body of the single crystal furnace after shutdown, and filter, cool, and heat exchange the hot air flow in sequence to reach the standard for use in the single crystal furnace, and then pass the treated air flow into the furnace body of the single crystal furnace to achieve the purpose of rapid cooling of the thermal field, shorten the shutdown cooling time, increase unit production capacity, and achieve the effect of increasing production and efficiency. At the same time, by replacing the inert gas argon with filtered gas for pressurizing the secondary chamber, the equipment working hours are reduced, the work efficiency is improved, and the use of argon is saved; not only can the work efficiency be improved, the effect of increasing production and efficiency is achieved, but also automation is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of a method for rapid cooling of a single crystal furnace when it is shut down according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] This embodiment provides a method for rapid cooling of a single crystal furnace after shutdown. Figure 1 As shown, the method mainly focuses on quickly cooling the furnace body after the single crystal growth is completed, and the steps include: first extracting the remaining gas in the single crystal furnace and treating it; then returning the treated gas to the single crystal furnace; alternating the above operation steps until the extracted gas temperature meets the requirements.

[0026] When growing a single crystal, it is necessary to introduce a high-purity inert gas into the single crystal furnace body, generally high-purity argon. Argon plays an important role in the production of single crystal silicon. Argon is an inert gas. As a protective gas, it surrounds the liquid surface of single crystal silicon and polycrystalline silicon to protect single crystal silicon and polycrystalline silicon from oxidation. At the same time, argon is a monatomic gas that exists in an atomic state. There is no molecular decomposition or atomic absorption of heat at high temperatures. The specific heat capacity and heat conductivity of argon are small, that is, the absorption capacity itself is small and the heat transfer to the outside is also small. Therefore, the presence of argon can also reduce the loss of heat energy and play a role in energy saving. Not only that, because argon flows in the single crystal furnace, it can also take away volatiles in the silicon liquid and volatiles in other parts at high temperatures. In this way, it can prevent the single crystal silicon or polycrystalline silicon liquid from being contaminated and affect the product quality of single crystal silicon. In addition, argon forms a uniform laminar flow from top to bottom and passes over the crystal surface, which can take away the latent heat of crystallization, thereby ensuring the normal growth of single crystal silicon. Therefore, after the crystal growth is completed, there are still a lot of residual high-temperature mixed gases inside the furnace, mainly argon and gas volatile impurities. If these gases are directly discharged from the furnace, it will not only cause environmental pollution, but also waste resources. Recycling these mixed gases can not only protect the crystal from being affected, but also quickly reduce the temperature inside the furnace to achieve the purpose of rapid cooling.

[0027] Specifically, before extracting the remaining gas in the single crystal furnace, the step of closing the high-purity gas introduced into the furnace body is also included. That is, after the crystal growth is completed, the high-purity nitrogen is stopped from being introduced into the furnace body, but the main chamber and the auxiliary chamber are kept in communication with each other, so that the recovered gas can enter the main chamber from the auxiliary chamber again, ensuring the smooth flow path of the gas flow from the auxiliary chamber to the main chamber, so as to gradually reduce the thermal field temperature in the main chamber to meet the requirements of the dismantling conditions.

[0028] Since the pump body that introduces high-purity nitrogen into the furnace body is connected to the high-purity nitrogen source, and the pump body for extracting the remaining mixed gas in the furnace body is connected to the external filtration unit and the cooling unit, the pump body used to control stopping the introduction of high-purity gas into the furnace body and the pump body used to control the extraction of the remaining gas in the single crystal furnace are not controlled by the same driving source, but are controlled by different pump bodies.

[0029] The remaining mixed gas in the furnace is extracted directly from the bottom of the main chamber, because all gases flow from top to bottom and are discharged through the outlet on the bottom of the main chamber. While discharging the gas, the gas pressure in the main chamber and the temperature of the discharged gas need to be monitored to observe in real time whether the gas pressure in the furnace has risen from the negative pressure state to the normal pressure state, and to monitor whether the temperature of the discharged gas meets the requirements for dismantling and cleaning.

[0030] Furthermore, the residual gas in the extracted single crystal furnace is processed, specifically:

[0031] The remaining gas is first filtered to completely filter out the volatiles and particulate impurities in the remaining mixed gas to obtain nitrogen with purity that meets the requirements. In this embodiment, the purity of the filtered nitrogen is required to reach more than 98% before it can be refluxed into the secondary chamber.

[0032] The filtered gas is then cooled down. Since the temperature of the gas just discharged from the main chamber is relatively high, reaching 4000°C, the pure nitrogen after filtration needs to be heat exchanged to cool its temperature to -10°C ~ 10°C. The cooled gas is then recycled and transmitted to the auxiliary chamber. The gas flow then flows along the auxiliary chamber to the main chamber and then flows out of the main chamber.

[0033] When the recovered airflow moves to the main chamber, it drives the volatiles and impurities in the main chamber out together, and is pumped out to the outside of the furnace by the auxiliary pump again, and is filtered and cooled again, and then returned to the auxiliary chamber to continue to cool the temperature in the furnace. By repeatedly returning the recovered nitrogen to the auxiliary chamber, the temperature of the thermal field in the main chamber can be reduced to achieve the purpose of rapid cooling.

[0034] In this embodiment, the operation of extracting the remaining gas in the single crystal furnace and the operation of transmitting the cooled gas to the auxiliary chamber are processed simultaneously. That is, the extraction of the mixed gas in the furnace body and the introduction of the processed gas into the auxiliary chamber can be performed simultaneously without affecting each other, and the efficiency is higher.

[0035] Furthermore, the temperature of the extracted gas meets the requirement. To monitor and obtain that the temperature of the remaining gas extracted from the furnace body meets the dismantling temperature, the treated gas can be stopped from being introduced into the auxiliary chamber, wherein the standard dismantling temperature is 180-220°C. That is, the temperature of the extracted gas is monitored in real time. When the temperature of the discharged gas meets the temperature required by the dismantling temperature, the ventilation treatment of the auxiliary chamber can be stopped, but the extracted mixed gas still needs to be filtered and cooled, and then the cooled nitrogen is discharged into the air, or stored, to cool down the furnace body of other single crystal furnaces.

[0036] Of course, while extracting the mixed gas in the furnace body, the gas pressure in the single crystal furnace body is also monitored to ensure that the gas pressure in the furnace body changes from a negative pressure state to a normal pressure state to verify the cooling effect on the furnace body.

[0037] A method for rapid cooling of a single crystal furnace after shutdown designed in this application is adopted to recycle the hot air flow in the furnace body of the single crystal furnace after shutdown, and filter, cool, and heat exchange the hot air flow in sequence to reach the standard for use in the single crystal furnace, and then pass the treated air flow into the furnace body of the single crystal furnace to achieve the purpose of rapid cooling of the thermal field, shorten the shutdown cooling time, increase unit production capacity, and achieve the effect of increasing production and efficiency. At the same time, by replacing the inert gas argon with filtered gas for pressurizing the secondary chamber, the equipment working hours are reduced, the work efficiency is improved, and the use of argon is saved; not only can the work efficiency be improved, the effect of increasing production and efficiency is achieved, but also automation is realized.

[0038] The above is a detailed introduction to a method for rapid cooling of a single crystal furnace provided by an embodiment of the present application. The description of the above embodiment is only used to help understand the structure and core idea of ​​the present application; at the same time, for a person skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0039] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that different manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. "Including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is still for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0040] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0041] The above detailed description of the embodiments of the present application is only a preferred embodiment of the present application and cannot be considered to limit the scope of implementation of the present application. All equivalent changes and improvements made within the scope of the present application should still fall within the scope of the patent coverage of the present application.

Claims

1. A method for rapid cooling of a single crystal furnace after shutdown, characterized in that: The main purpose is to quickly cool the furnace body after the single crystal growth is completed. The steps include: Extract the remaining gas in the single crystal furnace and treat it; The treated gas is then fed back into the single crystal furnace; Repeat the above steps until the extracted gas temperature meets the requirements.

2. A method for rapid cooling of a single crystal furnace after shutdown according to claim 1, characterized in that: Before extracting the remaining gas in the single crystal furnace, the method also includes closing the step of introducing high-purity gas into the furnace body.

3. A method for rapid cooling of a single crystal furnace after shutdown according to claim 2, characterized in that: The pump body used for controlling the stopping of the introduction of high-purity gas into the furnace body and the pump body used for controlling the extraction of the remaining gas in the single crystal furnace are different.

4. A method for rapid cooling of a single crystal furnace after shutdown according to any one of claims 1 to 3, characterized in that: The residual gas in the extracted single crystal furnace is processed as follows: Filter the remaining gas first; The filtered gas is then cooled down; The cooled gas is then transferred to the secondary chamber.

5. A method for rapid cooling of a single crystal furnace after shutdown according to claim 4, characterized in that: The temperature of the gas transmitted to the secondary chamber is -10°C to 10°C.

6. A method for rapid cooling of a single crystal furnace after shutdown according to claim 5, characterized in that: Extracting the remaining gas in the single crystal furnace and transmitting the cooled gas to the auxiliary chamber are synchronous operations.

7. A method for rapid cooling of a single crystal furnace after shutdown according to any one of claims 1-3, 5-6, characterized in that: While extracting the residual gas in the single crystal furnace, the temperature of the extracted residual gas is also monitored.

8. A method for rapid cooling of a single crystal furnace after shutdown according to claim 7, characterized in that: The extracted gas temperature meets the requirement. When the temperature of the remaining gas extracted from the furnace body meets the cleaning temperature, the treated gas can be stopped from being introduced into the auxiliary chamber. The standard cleaning temperature is 180-220°C.

9. A method for rapid cooling of a single crystal furnace after shutdown according to claim 8, characterized in that: It also includes monitoring the gas pressure inside the single crystal furnace.

10. A method for rapid cooling of a single crystal furnace after shutdown according to any one of claims 1-3, 5-6, 8-9, characterized in that: In the process of extracting and treating the remaining gas in the single crystal furnace and returning the treated gas to the single crystal furnace, the main chamber and the sub-chamber in the single crystal furnace are always in an interconnected state.

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