CN113834315A - Method and system for drying polycrystalline silicon - Google Patents

Method and system for drying polycrystalline silicon Download PDF

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Publication number
CN113834315A
CN113834315A CN202111416887.9A CN202111416887A CN113834315A CN 113834315 A CN113834315 A CN 113834315A CN 202111416887 A CN202111416887 A CN 202111416887A CN 113834315 A CN113834315 A CN 113834315A
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China
Prior art keywords
supercritical
polycrystalline silicon
drying
stage
spray head
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CN202111416887.9A
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Inventor
张天雨
蒋文武
吴鹏
吴锋
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Jiangsu Xinhua Semiconductor Materials Technology Co ltd
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Jiangsu Xinhua Semiconductor Materials Technology Co ltd
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Priority to CN202111416887.9A priority Critical patent/CN113834315A/en
Publication of CN113834315A publication Critical patent/CN113834315A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/001—Drying-air generating units, e.g. movable, independent of drying enclosure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/004—Nozzle assemblies; Air knives; Air distributors; Blow boxes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/14—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects using gases or vapours other than air or steam, e.g. inert gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)
  • Cleaning Or Drying Semiconductors (AREA)
  • Silicon Compounds (AREA)

Abstract

The invention discloses a method and a system for drying polycrystalline silicon. The method comprises the following steps: spraying supercritical CO to the surface of polycrystalline silicon2So as to remove residual moisture on the surface of the polycrystalline silicon, and spraying supercritical CO2The process of (a) comprises three stages which are carried out in sequence, wherein: the injection pressure of the first stage is 1-3 MPa, and the injection time is 10-15 min; the injection pressure of the second stage is 3-5 MPa, and the injection time is 8-12 min; and the injection pressure of the third stage is 4-6 MPa, the injection time is 5-8 min, the injection pressure of the first stage is smaller than that of the second stage, and the injection pressure of the second stage is smaller than that of the third stage. The method for drying the polycrystalline silicon is simple to operate, can be carried out at normal temperature, is high in drying efficiency and good in drying effect, does not introduce new impurities, and can ensure the drying effect and the quality of the polycrystalline silicon.

Description

Method and system for drying polycrystalline silicon
Technical Field
The invention belongs to the field of materials, and particularly relates to a method and a system for drying polycrystalline silicon.
Background
Electronic grade polysilicon produced using the modified siemens process requires crushing, screening, cleaning, drying and packaging. The surface of the polycrystalline silicon produced by the improved Siemens method has a plurality of tiny gaps and holes, water vapor is easy to remain in the tiny gaps, the water vapor can be always attached to the surface of a silicon material because the sealing performance of a packaging bag is extremely high, and when the silicon material with trace water vapor enters a straight pulling single crystal link, the straight pulling single crystal is broken.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a method and a system for drying polysilicon, so as to ensure the efficiency and effect of drying the surface of polysilicon.
The invention is mainly based on the following problems:
the inventor finds that hot air can be blown to the surface of the silicon material to remove the residual moisture on the surface of the silicon material, but the method needs to heat drying gas such as air, and after drying is finished, the silicon material is hotter and needs to be cooled and then subjected to subsequent processes such as charging, and more importantly, the hot air drying also easily introduces external pollution sources, for example, impurities can be introduced due to impure drying gas, and impurities such as metal and dust can be introduced into a heating pipe to cause impurity residues; in addition, the surface of the silicon material can also be dried by adopting a vacuumizing mode, but the method has higher requirement on the sealing performance of a drying box, enough power of a vacuum pump and high required energy consumption, but the drying effect on the surface of the silicon material is not ideal because part of water bubbles in tiny gaps and holes on the surface of the silicon material are difficult to completely escape through air.
To this end, according to a first aspect of the invention, a method of drying polycrystalline silicon is proposed. According to an embodiment of the invention, the method comprises:
spraying supercritical CO to the surface of polycrystalline silicon2So as to remove residual moisture on the surface of the polycrystalline silicon, and spraying supercritical CO2The process of (a) comprises three stages which are carried out in sequence, wherein:
the injection pressure of the first stage is 1-3 MPa, and the injection time is 10-15 min;
the injection pressure of the second stage is 3-5 MPa, and the injection time is 8-12 min;
the injection pressure of the third stage is 4-6 MPa, the injection time is 5-8 min,
the injection pressure of the first stage is less than the injection pressure of the second stage, which is less than the injection pressure of the third stage.
The inventor finds that if the drying gas is simply sprayed, the drying gas can easily escape, the drying gas is difficult to realize better contact with the surface of the polycrystalline silicon, the drying gas is difficult to enter micro gaps and holes on the surface of the polycrystalline silicon, and the drying effect and the drying efficiency on the surface of the polycrystalline silicon are poor2The supercritical carbon dioxide can be rapidly diffused into the tiny gaps and the holes on the surface of the polycrystalline silicon, and the water vapor in the tiny gaps and the holes is extruded out, so that the surface of the polycrystalline silicon is fully dried, and the supercritical carbon dioxide in the gaps of the polycrystalline silicon material can escape through volatilization; furthermore, in the drying process, supercritical CO2And the isolation of the polycrystalline silicon from the air can be realized, and the probability of oxidizing the polycrystalline silicon is reduced. Therefore, the method for drying the polycrystalline silicon is simple to operate, can be carried out at normal temperature, is high in drying efficiency and good in drying effect, does not introduce new impurities, and can ensure the drying effect and the quality of the polycrystalline silicon.
In addition, the method for drying polycrystalline silicon according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the invention, the third stage injected supercritical CO is recovered2And recovering the obtained supercritical CO2For the second stage, recovering the supercritical CO injected in the second stage2And recovering the obtained supercritical CO2For the first stage.
In some embodiments of the invention, the plurality of tabletsSpraying supercritical CO to the surface of the polysilicon at the same angle2。
In some embodiments of the invention, supercritical CO is sprayed from above the polysilicon toward the polysilicon surface2(ii) a And/or spraying supercritical CO from the side part of the polycrystalline silicon to the surface of the polycrystalline silicon2。
In some embodiments of the invention, the polycrystalline silicon is placed in a drying vessel, at least one supercritical CO being disposed in an upper portion of the drying vessel2A spray head facing a lower portion of the drying container, the spray head including a plurality of different spray angles and/or the spray head being automatically rotatable; and/or the presence of a gas in the gas,
in some embodiments of the invention, a plurality of supercritical CO are disposed at the side of the drying vessel along the circumference thereof2A spray head facing a middle of the drying container, the spray head comprising a plurality of different spray angles and/or the spray head being automatically rotatable.
In some embodiments of the invention, the polycrystalline silicon is placed in a drying vessel by supercritical CO2The spray head sprays supercritical CO to the surface of the polycrystalline silicon2The drying vessel may be along the supercritical CO2The spray head rotates.
According to a second aspect of the present invention, there is also provided a drying system for carrying out the above method of drying polycrystalline silicon. According to an embodiment of the invention, the system comprises:
the drying container is used for containing polycrystalline silicon to be dried;
supercritical CO2Supply device of the supercritical CO2The supply device is connected with supercritical CO2Showerhead, the supercritical CO2The supply means comprise a first supply means, a second supply means and a third supply means, said first supply means, said second supply means and said third supply means being adapted to pass through said supercritical CO in sequence2The spray head sprays supercritical CO to the surface of the polycrystalline silicon2。
Compared with the prior art, the drying method adopting the embodiment of the inventionThe system can spray supercritical CO to the surface of the polysilicon2And due to supercritical CO2The diffusion property of the silicon material is good, so that the supercritical carbon dioxide can be rapidly diffused into tiny gaps and cavities on the surface of the polycrystalline silicon and the water vapor in the tiny gaps and the cavities is extruded out, so that the surface of the polycrystalline silicon is fully dried, and the supercritical carbon dioxide in gaps of the polycrystalline silicon material can escape through volatilization; furthermore, in the drying process, supercritical CO2And the isolation of the polycrystalline silicon from the air can be realized, and the probability of oxidizing the polycrystalline silicon is reduced. Therefore, the system is simple in structure, can be operated at normal temperature, does not introduce new impurities, and can ensure the drying efficiency, the drying effect and the quality of polycrystalline silicon.
In some embodiments of the invention, the drying system satisfies at least one of the following conditions: the supercritical CO2The spray head is arranged at the upper part and/or the side part of the drying container; the side part of the drying container is provided with a plurality of supercritical CO along the circumferential direction2A spray head; the supercritical CO2The spray head comprises a plurality of different spray angles and/or the spray head can rotate automatically; the drying vessel may be along the supercritical CO2Rotating the spray head; the supercritical CO2Supply device and supercritical CO2A booster pump is connected between the spray heads.
In some embodiments of the invention, the drying system further comprises: supercritical CO2Recovery unit, said supercritical CO2The recovery device is suitable for recovering the supercritical CO supplied to the surface of the polycrystalline silicon by the third supply device2And recovering the supercritical CO2Transferring to the second supply device, and recovering supercritical CO supplied from the second supply device to the surface of the polycrystalline silicon2And recovering the supercritical CO2Transferring to the first supply device.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a simplified schematic illustration of a method of drying polycrystalline silicon according to one embodiment of the invention;
fig. 2 is a schematic diagram of a system for implementing a method for drying polycrystalline silicon, according to one embodiment of the present invention.
Fig. 3 is a schematic view of a system configuration for implementing a method for drying polycrystalline silicon according to still another embodiment of the present invention.
Reference numerals:
10: drying the container;
20: supercritical CO2A supply device; 21: supercritical CO2A spray head; 22: a first supply device; 23: a second supply device; 24: a third supply device 24;
30: a header pipe; 31: a first branch pipe; 32: a second branch pipe; 33: a third branch pipe;
40: supercritical CO2A recovery device; 41: a first recycling device; 42: and a second recovery device.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", "circumferential", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral connections; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. In addition, in the present invention, unless otherwise explicitly specified or limited, a first feature "on" or "under" a second feature may be directly contacted with the first and second features, or indirectly contacted with the first and second features through an intermediate. Also, a first feature "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature.
According to a first aspect of the present invention, a method of drying polycrystalline silicon is presented. According to an embodiment of the invention, the method comprises: spraying supercritical CO to the surface of polycrystalline silicon2(understood with reference to fig. 1) to remove residual moisture on the surface of the polysilicon, spraying supercritical CO2The process of (a) comprises three stages which are carried out in sequence, wherein: the injection pressure of the first stage is 1-3 MPa, and the injection time is 10-15 min; the injection pressure of the second stage is 3-5 MPa, and the injection time is 8-12 min; the injection pressure of the third stage is 4-6 MPa, the injection time is 5-8 min, the injection pressure of the first stage is smaller than that of the second stage, and the injection pressure of the second stage is smaller than that of the third stage. The inventors found that if the drying gas is simply sprayed, the drying gas easily escapes, and it is difficult to achieve the drying gas in a large amountThe liquid supercritical carbon dioxide adopted in the invention has very low surface tension and good diffusivity, can realize better contact with the surface of the polysilicon and infiltration on the surface of the polysilicon even if polysilicon silicon materials are stacked, thereby spraying supercritical CO to the surface of the polysilicon2The supercritical carbon dioxide can be rapidly diffused into the tiny gaps and the holes on the surface of the polycrystalline silicon, and the water vapor in the tiny gaps and the holes is extruded out, so that the surface of the polycrystalline silicon is fully dried, and the supercritical carbon dioxide in the gaps of the polycrystalline silicon material can escape through volatilization; furthermore, in the drying process, supercritical CO2And the isolation of the polycrystalline silicon from the air can be realized, and the probability of oxidizing the polycrystalline silicon is reduced. Therefore, the method for drying the polycrystalline silicon is simple to operate, can be carried out at normal temperature, is high in drying efficiency and good in drying effect, does not introduce new impurities, and can ensure the drying effect and the quality of the polycrystalline silicon. It should be noted that the drying process in the present invention is performed on the polysilicon after cleaning and before packaging, and the polysilicon is dried after cleaning, and then packaged after drying.
In addition, according to the embodiment of the invention, one or more polysilicon samples to be dried can be used as a group of samples to be dried, and supercritical CO can be sprayed to the surface of the polysilicon according to the same group of samples to be dried2The method comprises three successive stages, wherein the injection pressure can be gradually increased and the injection time can be gradually shortened, and the supercritical CO can be realized by adopting relatively lower injection pressure and longer injection time in the first stage2Contact time with the surface of polycrystalline silicon to realize supercritical CO2The polycrystalline silicon surface is fully contacted and soaked so as to discharge water vapor in gaps on the polycrystalline silicon surface as much as possible; the purpose of the subsequent stepwise increase of the injection pressure is to utilize the supercritical CO2The impact force of the method realizes the small quantity of the residue on the surface of the polysilicon and the removal difficulty is higherAnd a small amount of water vapor remained on the surface of the polycrystalline silicon can be further removed by adopting larger injection pressure in the third stage, so that the aim of further ensuring the drying effect is achieved, and therefore, the drying effect on the surface of the polycrystalline silicon can be further ensured by adopting the three-stage injection operation. Further, supercritical CO is injected2In the three stages (a), the injection pressure in the first stage can be 1-3 MPa, for example, 1.5MPa, 2MPa or 2.5MPa, and the injection time can be 10-15 min; the injection pressure in the second stage can be 3-5 MPa, for example, 3.5MPa, 4MPa or 4.5MPa, and the injection time can be 8-12 min; the third stage of injection pressure can be 4-6 MPa, for example, 4.5MPa, 5MPa or 5.5MPa, the injection time can be 5-8 min, the first stage of injection pressure is less than the second stage of injection pressure, the second stage of injection pressure is less than the third stage of injection pressure, and the inventor finds that by controlling the injection conditions, the drying effect on the surface of the polycrystalline silicon can be further ensured, the sufficient discharge of water vapor in micro gaps and holes on the surface of the polycrystalline silicon can be realized, and the problem of straightening the single crystal breakage line when the polycrystalline silicon enters a Czochralski single crystal link can be effectively solved.
The method of drying polycrystalline silicon according to the above embodiment of the present invention will be described in detail.
According to the embodiment of the invention, supercritical CO is sprayed on the surface of the polycrystalline silicon2By spraying supercritical CO onto the surface of the polysilicon2Not only can increase the supercritical CO2The utilization rate of the catalyst is more favorable for realizing supercritical CO2And recycling and reusing.
According to some embodiments of the invention, the supercritical CO injected in the third stage may be recovered2And recovering the obtained supercritical CO2For the second stage, recovery of supercritical CO injected in the second stage2And recovering the obtained supercritical CO2For the first stage, it is possible, for example, to recover the supercritical CO injected during the third stage of drying the last set of samples to be dried2And recovering the obtained supercritical CO2Supercritical CO for the second stage of the next set of samples to be dried2Spraying, recovering the supercritical CO sprayed in the second stage when the previous group of samples to be dried are dried2And recovering the obtained supercritical CO2Supercritical CO for the first stage of the next set of samples to be dried2Injection, whereby both supercritical CO can be achieved2The continuous drying of a plurality of groups of polysilicon samples during drying can not be influenced by the recycling of the silicon samples.
According to some embodiments of the present invention, a plurality of sets of samples to be dried may be placed in a plurality of different open drying containers, respectively, and the plurality of drying containers containing the samples to be dried may be placed in an open chamber, and supercritical CO may be sprayed2During the process, the surfaces of the polycrystalline silicon in the drying containers are sprayed simultaneously, so that the batch drying of the polycrystalline silicon can be realized, the production efficiency is greatly improved, and the supercritical CO sprayed out of the drying containers can be recovered by utilizing the cavities2. Further, in this operation, supercritical CO is sprayed to the surface of the polycrystalline silicon2The method can also be divided into three stages which are carried out in sequence, wherein the injection pressure of the first stage can be 1-3 MPa, and the injection time can be 10-15 min; the injection pressure of the second stage can be 3-5 MPa, and the injection time can be 8-12 min; the injection pressure of the third stage can be 4-6 MPa, the injection time can be 5-8 min, and in addition, the supercritical CO of the first stage can be controlled2The flow rate of the injection can be 20-30L/min, and the supercritical CO in the second stage2The flow rate of the injection can be 30-40L/min, and the third stage of supercritical CO2The flow rate of the spraying can be 40-50L/min, so that the drying effect of the batch drying of the polycrystalline silicon can be further ensured.
According to still other embodiments of the present invention, supercritical CO is sprayed onto a polysilicon surface2At the same time, the supercritical CO can be sprayed to the surface of the polysilicon from a plurality of different angles2Thereby being more favorable for realizing supercritical CO2Fully contacts and soaks the surface of the polycrystalline silicon to ensure that the supercritical CO is2Can be diffused to the tiny gaps and holes on the surface of the polycrystalline silicon more quickly, and extrude the residual water vapor in the gaps on the surface of the polycrystalline silicon, thereby further improving the drying efficiency and the drying effectThe purpose is.
According to still other embodiments of the present invention, supercritical CO is sprayed onto a polysilicon surface2At this time, supercritical CO can be sprayed from the upper part of the polycrystalline silicon to the surface of the polycrystalline silicon2The spraying direction can be towards the polysilicon and comprises a plurality of different spraying angles, the spraying angles are towards the polysilicon and the included angle between the spraying angles and the horizontal plane is not more than 90 degrees, for example, the polysilicon can be placed in an open drying container, and at least one supercritical CO is arranged at the upper part of the drying container2A spray head facing the lower part of the drying container and including multiple different spray angles and/or capable of automatically rotating, wherein when the spray head can automatically rotate, even if the spray angle of the spray head is single, supercritical CO can be sprayed on the surface of the polycrystalline silicon from multiple angles2Preferably, the spray head is rotatable by 360 degrees, and more preferably, the spray direction of the spray head is always directed into the drying container during rotation of the spray head. Thereby, even if supercritical CO is injected to the surface of the polycrystalline silicon from above the polycrystalline silicon2And the drying efficiency can be obviously improved.
According to still other embodiments of the present invention, supercritical CO is sprayed onto a polysilicon surface2At the same time, supercritical CO can be sprayed from the side part of the polysilicon to the surface of the polysilicon2The spraying direction can be towards the polysilicon and comprises a plurality of different spraying angles, the spraying angles are towards the polysilicon and the included angle between the spraying angles and the vertical plane is not more than 90 degrees, for example, the polysilicon can be placed in a drying container, and a plurality of supercritical CO are arranged on the side part of the drying container along the circumferential direction of the drying container2Spray head, preferably for multiple supercritical CO2The spray heads are uniformly distributed along the circumferential direction of the drying container, wherein the spray heads face the middle part of the drying container, and the spray heads can comprise a plurality of different spray angles and/or can automatically rotate, wherein when the spray heads can automatically rotate, even if the spray angles of the spray heads are single, the supercritical CO can be sprayed on the surface of the polycrystalline silicon from a plurality of angles2Preferably, the spray head is rotatable by 360 degrees, and more preferably, the spray direction of the spray head is always directed into the drying container during rotation of the spray head. Thereby, even if only from the upper part of the polycrystalline silicon to the polycrystalline siliconSurface spraying supercritical CO2And the drying efficiency can be obviously improved. More preferably, supercritical CO can also be sprayed from the upper and side portions of the polycrystalline silicon to the surface of the polycrystalline silicon at the same time2For example, the polysilicon can be placed in an open drying container, and supercritical CO can be fixed on the upper part of the drying container and the inner side wall of the drying container2A spray head facing the inside of the drying container and including multiple different spray angles and/or capable of automatically rotating to ensure that the upper part and the side part of the polycrystalline silicon can realize supercritical CO2And the multi-angle spraying can further improve the efficiency of drying the surface of the polycrystalline silicon.
According to still other embodiments of the present invention, supercritical CO is sprayed onto a polysilicon surface2In this case, the polysilicon can also be placed in an open drying vessel and passed through supercritical CO2The spray head sprays supercritical CO to the surface of the polycrystalline silicon2In this case, supercritical CO may be used2The nozzle is fixed to ensure that the drying container is along the supercritical CO2The spray head rotates to ensure that the opening direction of the drying container always faces to the supercritical CO2The spray head can also realize supercritical CO by adopting the scheme2And the multi-angle spraying ensures the efficiency of drying the surface of the polycrystalline silicon. Further, supercritical CO can be used2The nozzle head comprises a plurality of different injection angles, thereby being more beneficial to supercritical CO2Fully contacts and wets the surface of the polysilicon, thereby achieving the purpose of remarkably improving the drying efficiency and the drying effect.
According to a second aspect of the present invention, there is also provided a drying system for carrying out the above method of drying polycrystalline silicon. According to an embodiment of the invention, as understood with reference to FIGS. 2-3, the system includes: drying vessel 10 and supercritical CO2 A supply device 20, the drying container 10 is used for containing polysilicon to be dried; supercritical CO2The supply device 20 is connected with supercritical CO2Spray head 21, supercritical CO2The supply device 20 comprises a first supply device 22, a second supply device 23 and a third supply device 24, the first supply device 22, the second supply device 23 and the third supply device 24 being adapted to pass supercritical CO in sequence2The sprayer 21 sprays supercritical CO to the surface of the polysilicon2. Compared with the prior art, the drying system adopting the embodiment of the invention can spray supercritical CO to the surface of the polycrystalline silicon2And due to supercritical CO2The diffusion property of the silicon material is good, so that the supercritical carbon dioxide can be rapidly diffused into tiny gaps and cavities on the surface of the polycrystalline silicon and the water vapor in the tiny gaps and the cavities is extruded out, so that the surface of the polycrystalline silicon is fully dried, and the supercritical carbon dioxide in gaps of the polycrystalline silicon material can escape through volatilization; furthermore, in the drying process, supercritical CO2And the isolation of the polycrystalline silicon from the air can be realized, and the probability of oxidizing the polycrystalline silicon is reduced. Therefore, the system is simple in structure, can be operated at normal temperature, does not introduce new impurities, and can ensure the drying efficiency, the drying effect and the quality of polycrystalline silicon. It should be noted that the features and effects described for the above method for drying polysilicon are also applicable to the drying system, and are not described in detail herein.
According to an embodiment of the invention, as understood with reference to fig. 3, the first supply device 22, the second supply device 23 and the third supply device 24 may in turn be passed through the supercritical CO2The spray head sprays supercritical CO to the surface of the polycrystalline silicon2I.e. supplying supercritical CO to the injection process of the first, second and third stages in sequence2At this time, supercritical CO2Supply device 20 and supercritical CO2The spray heads 21 can be connected with branch pipes through a main pipe 30, and supercritical CO can be obtained2The spray head 21 is connected with a main pipe 30, the main pipe 30 is respectively connected with a first supply device 22 through a first branch pipe 31, is connected with a second supply device 23 through a second branch pipe 32, and is connected with a third supply device 24 through a third branch pipe 33, wherein the first branch pipe 31, the second branch pipe 32 and the third branch pipe 33 can be respectively and independently provided with a valve (not shown), and the supercritical CO can be realized through switching of different branch valves2Switching of the supply device. Further, with supercritical CO2The pipeline connected with the spray head can be also provided with a pressure valve and/or a flow meter, so that the supercritical CO at different stages can be monitored in real time2Injection pressure and/or flow ofAmount of the compound (A).
According to some embodiments of the invention, the supercritical CO2The spray head 21 may be provided at the upper portion and/or the side portion of the drying container 10, thereby spraying supercritical CO to the polysilicon from above2Supercritical CO can also be sprayed to the polysilicon from the side part thereof2(ii) a Wherein a plurality of supercritical CO may be provided at a side portion (i.e., inner circumferential wall) of the drying container 10 along a circumferential direction thereof2A shower head 21, whereby supercritical CO can be simultaneously realized from different directions of the side of the polycrystalline silicon2Greatly improves the supercritical CO2Contact with the surface of the polysilicon and infiltration efficiency, so that the supercritical CO is obtained2Can be diffused into the tiny gaps and holes on the surface of the polycrystalline silicon more quickly, and the drying efficiency and the drying effect are ensured. Further, supercritical CO2The spray head 21 may comprise a plurality of different spray angles and/or the spray head may be automatically rotated, thereby enabling even supercritical CO2The spray head is arranged only at the upper part or the side part of the drying container, or only comprises one supercritical CO2Spray head, also can realize supercritical CO2The multi-angle spraying and the contact with the surface of the polycrystalline silicon ensure the drying efficiency and the drying effect, and in addition, the supercritical CO needs to be explained2The rotation angle of the nozzle is not particularly limited, and those skilled in the art can select the rotation angle according to actual needs, preferably supercritical CO2The spray head always faces to the surface of the polycrystalline silicon during the rotation process.
According to still further embodiments of the present invention, the drying vessel 10 may be enabled to operate along supercritical CO2The nozzle 21 is rotated, preferably automatically, even in the case of supercritical CO2The spray head is fixed and can realize supercritical CO2The multi-angle spraying ensures the efficiency of drying the surface of the polysilicon, and preferably ensures that the opening direction of the drying container always faces to the supercritical CO in the rotating process2And (4) a spray head. Further, supercritical CO can also be used2The nozzle head comprises a plurality of different injection angles, thereby being more beneficial to supercritical CO2Fully contacts and wets the surface of the polysilicon to achieve the aim of further improving the drying efficiency and the drying effect.
According to further embodiments of the present invention, the type of the drying container 10 in the present invention is not particularly limited, and those skilled in the art can select the drying container according to actual needs, for example, the drying container may be an open cylindrical container, an open polygonal container, or the like.
According to further embodiments of the present invention, supercritical CO2Supply device 20 and supercritical CO2A booster pump (not shown) may be connected between the showerheads 21 to spray supercritical CO onto the polysilicon surface2The method can comprise three stages which are carried out in sequence, wherein in the three stages which are carried out in sequence, the injection pressure can be increased step by step, and therefore the supercritical CO of each stage can be flexibly controlled through the arrangement of the booster pump2The spray pressure of the spray nozzle is used for ensuring the drying efficiency and effect of the surface of the polycrystalline silicon.
According to still further embodiments of the present invention, the drying system may further include: supercritical CO2Recovery unit 40, supercritical CO2The recovery device 40 is adapted to recover the supercritical CO supplied to the surface of the polycrystalline silicon by the third supply device 242And recovering the supercritical CO2Transferring to the second supply device 23, and recovering the supercritical CO supplied to the surface of the polycrystalline silicon by the second supply device 232And recovering the supercritical CO2Is transferred to the first supply device 22, whereby supercritical CO can be achieved2The recycling of (2). Preferably, supercritical CO2The recycling device 40 may comprise a first recycling device 41 and a second recycling device 42, the first recycling device 41 is adapted to recycle the supercritical CO supplied to the polysilicon surface by the third supplying device 242And recovering the supercritical CO2The process is transferred to the second supply device 23, and the supercritical CO supplied to the surface of the polycrystalline silicon by the second supply device 23 is recovered by the second recovery device 422And recovering the supercritical CO2Transferred to the first supply means 22. Thereby, the supercritical CO of different injection stages can be more favorably realized2Respectively recovering.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (9)

1. A method of drying polycrystalline silicon, comprising:
spraying supercritical CO to the surface of polycrystalline silicon2So as to remove residual moisture on the surface of the polycrystalline silicon, and spraying supercritical CO2The process of (a) comprises three stages which are carried out in sequence, wherein:
the injection pressure of the first stage is 1-3 MPa, and the injection time is 10-15 min;
the injection pressure of the second stage is 3-5 MPa, and the injection time is 8-12 min;
the injection pressure of the third stage is 4-6 MPa, the injection time is 5-8 min,
the injection pressure of the first stage is less than the injection pressure of the second stage, which is less than the injection pressure of the third stage.
2. The method of claim 1, wherein the third stage injected supercritical CO is recovered2And recovering the obtained supercritical CO2For the second stage, recovering theSecond stage injection of supercritical CO2And recovering the obtained supercritical CO2For the first stage.
3. The method of claim 1 or 2, wherein the supercritical CO is sprayed onto the polysilicon surface from a plurality of different angles2。
4. The method of claim 3, wherein supercritical CO is sprayed from above the polysilicon toward the polysilicon surface2(ii) a And/or spraying supercritical CO from the side part of the polycrystalline silicon to the surface of the polycrystalline silicon2。
5. The method according to claim 1 or 4, wherein the polycrystalline silicon is placed in a drying vessel, at least one supercritical CO being provided in an upper part of the drying vessel2A spray head facing a lower portion of the drying container, the spray head including a plurality of different spray angles and/or the spray head being automatically rotatable; and/or the presence of a gas in the gas,
disposing a plurality of supercritical CO at a side portion of the drying vessel along a circumferential direction thereof2A spray head facing a middle of the drying container, the spray head comprising a plurality of different spray angles and/or the spray head being automatically rotatable.
6. The method of claim 1 or 4, wherein the polycrystalline silicon is placed in a drying vessel by supercritical CO2The spray head sprays supercritical CO to the surface of the polycrystalline silicon2The drying vessel may be along the supercritical CO2The spray head rotates.
7. A drying system for carrying out the method of any one of claims 1 to 6, comprising:
the drying container is used for containing polycrystalline silicon to be dried;
supercritical CO2Supply device of the supercritical CO2The supply device is connected with supercritical CO2Showerhead, the supercritical CO2The supply means comprise a first supply means, a second supply means and a third supply means, said first supply means, said second supply means and said third supply means being adapted to pass through said supercritical CO in sequence2The spray head sprays supercritical CO to the surface of the polycrystalline silicon2。
8. Drying system according to claim 7, wherein at least one of the following conditions is fulfilled:
the supercritical CO2The spray head is arranged at the upper part and/or the side part of the drying container;
the side part of the drying container is provided with a plurality of supercritical CO along the circumferential direction2A spray head;
the supercritical CO2The spray head comprises a plurality of different spray angles and/or the spray head can rotate automatically;
the drying vessel may be along the supercritical CO2Rotating the spray head;
the supercritical CO2Supply device and supercritical CO2A booster pump is connected between the spray heads.
9. The drying system of claim 7 or 8, further comprising:
supercritical CO2Recovery unit, said supercritical CO2The recovery device is suitable for recovering the supercritical CO supplied to the surface of the polycrystalline silicon by the third supply device2And recovering the supercritical CO2Transferring to the second supply device, and recovering supercritical CO supplied from the second supply device to the surface of the polycrystalline silicon2And recovering the supercritical CO2Transferring to the first supply device.
CN202111416887.9A 2021-11-26 2021-11-26 Method and system for drying polycrystalline silicon Pending CN113834315A (en)

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Application publication date: 20211224