CN114408927B - Preparation method of high-purity silicon core - Google Patents

Preparation method of high-purity silicon core Download PDF

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Publication number
CN114408927B
CN114408927B CN202111592084.9A CN202111592084A CN114408927B CN 114408927 B CN114408927 B CN 114408927B CN 202111592084 A CN202111592084 A CN 202111592084A CN 114408927 B CN114408927 B CN 114408927B
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silicon
silicon core
stage
rod
core
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CN114408927A (en
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蔡延国
丁小海
杨明财
吉红平
张孝山
施光明
曹延德
肖建忠
宗冰
梁哲
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Qinghai Asia Silicon Silicon Material Engineering Technology Co Ltd
Asia Silicon Qinghai Co Ltd
Qinghai Asia Silicon Semiconductor Co Ltd
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Qinghai Asia Silicon Silicon Material Engineering Technology Co Ltd
Asia Silicon Qinghai Co Ltd
Qinghai Asia Silicon Semiconductor Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/035—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
    • B28D5/04—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by tools other than rotary type, e.g. reciprocating tools
    • B28D5/045—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by tools other than rotary type, e.g. reciprocating tools by cutting with wires or closed-loop blades
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Silicon Compounds (AREA)

Abstract

The invention provides a preparation method and a preparation device of a high-purity silicon core, which relate to the technical field of polysilicon production, and the preparation method of the high-purity silicon core comprises the following steps: a starting stage: placing the silicon core in a reaction container, and increasing the surface temperature of the silicon core; introducing preheated materials into the reaction vessel to enable the silicon core to grow; and (3) a growth stage: introducing preheated materials into the reaction vessel, and raising the surface temperature of the silicon core to enable the silicon rod to grow rapidly; and (3) an adjustment stage: repairing the silicon rod; taking the repaired silicon rod out of the reaction vessel, and cutting to form a plurality of high-purity silicon cores; wherein the flow rate of the preheating material in the starting stage is 800-1200kg/h, and the flow rate of the preheating material in the growing stage is 4000-5500kg/h. The preparation method of the high-purity silicon core can relieve the problems of impurity introduction and uneven quality of the silicon core in the preparation process of the silicon core, thereby improving the production quality.

Description

Preparation method of high-purity silicon core
Technical Field
The invention relates to the technical field of polysilicon production, in particular to a preparation method of a high-purity silicon core.
Background
Currently, in the production of polysilicon, the following methods are often employed: a plurality of thin silicon cores are installed in a Chemical Vapor Deposition (CVD) reactor to be used as carriers, and silicon core beams are built to form a conductive loop. When the CVD reactor is in operation, the surface of the silicon rod is maintained in a certain temperature range by using an electric heating mode, and the silicon-containing gas and the reducing gas are introduced into the furnace to achieve reaction conditions, so that elemental silicon is deposited on the surface of the silicon rod, and the growth of the polycrystalline silicon rod is realized. Because the carrier fine silicon core prepared by the polycrystalline silicon in the reducing furnace cannot be completely separated in the finished product, the impurity content of the silicon core can directly influence the quality of the polycrystalline silicon rod of the product.
Typically, the silicon core carriers used in CVD reactors for preparing polycrystalline silicon are prepared by a czochralski single crystal silicon rod cutting process or by zone-melt drawing of a polycrystalline silicon masterbatch. The two processes have in common that: the primary silicon rod needs to be melted, and silicon in a melted state is active in chemical property, easy to react with contact substances to introduce pollution, and easy to diffuse and infiltrate impurities to form impurities in the body. In addition, impurity segregation phenomenon exists in the processes of straight drawing and zone melting, namely concentration gradient exists at the upper end and the lower end of the prepared silicon core, and the quality of the silicon core is uneven, so that the grade classification of the final polysilicon product is complicated.
Disclosure of Invention
The invention aims to provide a preparation method of a high-purity silicon core, which is used for solving the technical problems that impurities are easy to introduce and the quality of the silicon core is uneven in the preparation process of the silicon core in the prior art.
The preparation method of the high-purity silicon core provided by the invention comprises the following steps: a starting stage: placing the silicon core in a reaction container, and increasing the surface temperature of the silicon core; introducing preheated materials into the reaction vessel to enable the silicon core to grow; and (3) a growth stage: introducing preheated materials into the reaction vessel, and raising the surface temperature of the silicon core to enable the silicon rod to grow rapidly; and (3) an adjustment stage: repairing the silicon rod; taking the repaired silicon rod out of the reaction vessel, and cutting to form a plurality of high-purity silicon cores; wherein the flow rate of the preheating material in the starting stage is 800-1200kg/h, and the flow rate of the preheating material in the growing stage is 4000-5500kg/h.
Further, three rows of cutting lines are adopted, and the included angle of each row is 60 degrees, so that a plurality of high-purity silicon cores with regular triangular cross sections are formed.
Further, the preheated material includes a reducing gas and a silicon-containing gas.
Further, in the growth stage, the molar ratio of the reducing gas to the silicon-containing gas is 2 to 3.
Further, in the adjustment stage, the molar ratio of the reducing gas to the silicon-containing gas is 5 to 8.
Further, during the start-up phase, the surface temperature of the silicon core is raised to above 1000 ℃.
Further, the difference of diameters of two ends of the silicon rod is less than or equal to 15mm.
Further, the diameter difference between the thickest and thinnest eccentric position of the silicon rod is less than or equal to 15mm.
According to the preparation method of the high-purity silicon core, provided by the invention, the low-flow preheating material is introduced in the starting stage, so that the situation that the silicon core falls down and burrs grow in the growing process is avoided; the large-flow preheating material is introduced in the growth stage so as to enable the silicon rod to grow rapidly, thereby improving the primary conversion rate; through fine adjustment and repair in the adjustment stage, the silicon rod can be more compact and uniform, and the apparent morphology and the like meet the subsequent cutting requirements. Compared with the prior art, the large-diameter high-purity compact polycrystalline silicon rod obtained by the steps has high mechanical strength and strong processability, improves the efficiency of preparing the silicon core and the utilization rate of the silicon core, can save the production cost and reduces the energy consumption. On the other hand, the method avoids the possible pollution of the prior art in the process of preparing the silicon core, avoids the problem that impurities are introduced into the silicon rod, and improves the quality of the polysilicon product; and the problems of uneven quality of the silicon core and complicated classification of the polysilicon product grade are avoided.
From the above, the preparation method of the high-purity silicon core can relieve the problems of impurity introduction and uneven quality of the silicon core in the preparation process of the silicon core, thereby improving the production quality.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of steps of a method for preparing a high-purity silicon core according to an embodiment of the present invention;
FIG. 2 is a schematic view of a high purity silicon core cut into a plurality of regular triangular cross sections according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a device for preparing a high-purity silicon core according to an embodiment of the present invention.
Icon: 1-a reduction furnace; 2-chassis; 3-air inlet; 4-an air outlet; 5-monitoring means; 6-a current controller; 7-air flow controller.
Description of the embodiments
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
FIG. 1 is a block diagram of steps of a method for preparing a high-purity silicon core according to an embodiment of the present invention; as shown in fig. 1, the preparation method of the high-purity silicon core provided by the embodiment of the invention comprises the following steps: a starting stage: placing the silicon core in a reaction container, and increasing the surface temperature of the silicon core; introducing preheated materials into the reaction vessel to enable the silicon core to grow; and (3) a growth stage: introducing preheated materials into the reaction vessel, and raising the surface temperature of the silicon core to enable the silicon rod to grow rapidly; and (3) an adjustment stage: repairing the silicon rod; taking the repaired silicon rod out of the reaction vessel, and cutting to form a plurality of high-purity silicon cores; wherein the flow rate of the preheating material in the starting stage is 800-1200kg/h, and the flow rate of the preheating material in the growing stage is 4000-5500kg/h.
Wherein the running time of the starting stage is 10-25h.
Further, the silicon core is broken down pair by adopting a high voltage of 5000-10000V in the starting stage, so that the surface temperature of the silicon core is increased.
Further, during the start-up phase, the surface temperature of the silicon core is raised to above 1000 ℃.
Further, the running time of the growth stage is 50-80h.
Further, the operation time of the adjustment stage is 10-20h.
Further, in the adjustment stage, the appearance and the compactness of the silicon rod need to be repaired.
Further, the preheated material includes a reducing gas and a silicon-containing gas.
The reducing gas may be hydrogen, and the silicon-containing gas may be trichlorosilane or dichlorosilane.
Further, in the repair, the molar ratio of the reducing gas to the silicon-containing gas is adjusted to increase the flow rate of the reducing gas.
Further, in the growth stage, the molar ratio of the reducing gas to the silicon-containing gas is 2 to 3.
Further, in the adjustment stage, the molar ratio of the reducing gas to the silicon-containing gas is 5 to 8.
Further, silicon rod diameter Φ: the diameter of the root part phi 1 is 100mm above the graphite chuck, the diameter of the top part phi 2 is 100mm below the joint of the cross beams, and phi= (phi 1+ phi 2)/2 is more than or equal to 150mm. In the use process, as the root silicon rod contains graphite clamping petals, the top silicon rod is rough and cannot be used, and therefore the silicon rod is cut off at the two positions so as to ensure the quality of the silicon core.
Further, the diameter difference between the thickest and thinnest eccentric position of the silicon rod is less than or equal to 15mm.
Wherein, the surface of the silicon rod is uneven and has bulges and depressions; along a direction parallel to the surface of the silicon rod, a datum line is defined for the silicon rod. The position above the reference line is referred to as a protrusion, and the position below the reference line is referred to as a recess. The distance between the convex crest point and the concave trough point and the datum line is less than or equal to 3mm.
In addition, the minimum distance between adjacent protrusions, and the minimum distance between adjacent depressions should be 3mm or less.
Further, the straightness of the silicon rod: the minimum diameter phi 3 of the eccentric position and the maximum diameter phi 4 of the eccentric position are: ΔΦ=Φ4- Φ3 is less than or equal to 15mm.
Further, the diameter difference between the two ends of the silicon rod is less than or equal to 15mm, namely the size head delta phi=phi 2-phi 1 of the silicon rod is less than or equal to 15mm.
Further, in the cutting process, the silicon rod can be cut into silicon cores with different shapes and sizes by adopting cutting equipment such as diamond wires according to the requirements of users.
According to the preparation method of the high-purity silicon core, provided by the embodiment of the invention, the low-flow preheating material is introduced in the starting stage, so that the situation that the silicon core is lodged and burrs are grown in the growing process is avoided; the large-flow preheating material is introduced in the growth stage so as to enable the silicon rod to grow rapidly, thereby improving the primary conversion rate; through fine adjustment and repair in the adjustment stage, the silicon rod can be more compact and uniform, and the apparent morphology and the like meet the subsequent cutting requirements. Compared with the prior art, the large-diameter high-purity compact polycrystalline silicon rod obtained by the steps has high mechanical strength and strong processability, improves the efficiency of preparing the silicon core and the utilization rate of the silicon core, can save the production cost and reduces the energy consumption. On the other hand, the method avoids the possible pollution of the prior art in the process of preparing the silicon core, avoids the problem that impurities are introduced into the silicon rod, improves the quality of the polysilicon product, and avoids the problems of uneven quality of the silicon core and complicated classification of the polysilicon product grade.
From the above, the preparation method of the high-purity silicon core can relieve the problems of impurity introduction and uneven quality of the silicon core in the preparation process of the silicon core, thereby improving the production quality.
FIG. 2 is a schematic view of a high purity silicon core cut into a plurality of regular triangular cross sections according to an embodiment of the present invention; as shown in fig. 2, on the basis of the above embodiment, further, three rows of cutting lines are used to cut the silicon rod in a manner that each row has an included angle of 60 degrees, so as to form a plurality of high-purity silicon cores with regular triangular cross sections.
In this embodiment, the cutting method can obtain regular triangle high-purity silicon cores, so that the utilization rate of the silicon rod can be improved, and a larger number of high-purity silicon cores can be obtained.
Fig. 3 is a schematic structural diagram of a high-purity silicon core preparation device according to an embodiment of the present invention; as shown in fig. 3, on the basis of the above embodiment, further, the embodiment of the present invention further provides a high-purity silicon core preparation apparatus, where the high-purity silicon core preparation apparatus includes a reduction furnace 1; the chassis 2 of the reduction furnace 1 is provided with an air inlet 3, an air outlet 4 and a monitoring mechanism 5; the monitoring means 5 is for monitoring data of an internal flow field and data of a temperature field in the interior of the reduction furnace 1.
The current and air flow regulation parameters of the reduction furnace 1 can be obtained through simulation and calculation according to actual requirements.
In this embodiment, during the use process, the user places the silicon core inside the reduction furnace 1, and the preheated material is introduced from the air inlet 3, and the monitoring mechanism 5 is used for monitoring the internal flow field data and the temperature field data inside the reduction furnace 1, so as to adjust the flow of the current and the air flow according to the actual requirement. The silicon rod generated in the reducing furnace 1 can be cut in a cutting mode, so that the efficiency of preparing the silicon core and the utilization rate of the silicon core are improved, the production cost can be saved, and the energy consumption is reduced. On the other hand, the method can also avoid the possible pollution of the prior art in the process of preparing the silicon core, avoid the problem of impurity introduction, improve the quality of the polysilicon product, and simultaneously avoid the problems of uneven quality of the silicon core and complicated classification of the polysilicon product grade.
As shown in fig. 3, further, on the basis of the above embodiment, the high purity silicon core preparation apparatus further includes a current controller 6 and an air flow controller 7; the monitoring mechanism 5 is respectively connected with the current controller 6 and the airflow controller 7 to realize linkage.
In this embodiment, the monitoring mechanism 5 is configured to monitor internal flow field data and temperature field data inside the reducing furnace 1, and transmit the two data to the current controller 6 and the airflow controller 7 respectively, so as to adjust the current and the airflow, thereby more accurately controlling the growth environment of the silicon rod in the reducing furnace 1, improving the quality of the silicon rod, and further improving the quality of the polysilicon product.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (7)

1. The preparation method of the high-purity silicon core is characterized by comprising the following steps of:
a starting stage: placing a silicon core in a reaction container, and raising the surface temperature of the silicon core; introducing preheated materials into the reaction vessel to enable the silicon core to grow; the preheated material comprises a reducing gas and a silicon-containing gas;
and (3) a growth stage: introducing preheated materials into the reaction vessel, and raising the surface temperature of the silicon core to enable the silicon rod to grow rapidly;
and (3) an adjustment stage: repairing the silicon rod;
taking the repaired silicon rod out of the reaction container, and cutting to form a plurality of high-purity silicon cores;
wherein the flow rate of the preheating material in the starting stage is 800-1200kg/h, and the flow rate of the preheating material in the growing stage is 4000-5500kg/h;
and in the adjustment stage, repairing the appearance and the density of the silicon rod, and adjusting the mole ratio of the reducing gas to the silicon-containing gas to increase the flow rate of the reducing gas during repairing.
2. The method for preparing a high purity silicon core according to claim 1, wherein three rows of cutting lines are used, each row having an included angle of 60 ° to cut the silicon rod, so as to form a plurality of high purity silicon cores each having a regular triangle shape in cross section.
3. The method for producing a high purity silicon core according to claim 1 or 2, wherein in the growth stage, the molar ratio of the reducing gas to the silicon-containing gas is 2 to 3.
4. The method for producing a high purity silicon core according to claim 1 or 2, wherein in the adjustment stage, the molar ratio of the reducing gas to the silicon-containing gas is 5 to 8.
5. The method of claim 1, wherein the surface temperature of the silicon core is raised to above 1000 ℃ during the start-up phase.
6. The method for preparing a high-purity silicon core according to claim 1, wherein the difference between the diameters of the two ends of the silicon rod is 15mm or less.
7. The method for preparing a high purity silicon core according to claim 1, wherein the difference between the thickest and thinnest diameter of the eccentric position of the silicon rod is 15mm or less.
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Publication number Priority date Publication date Assignee Title
CN102020277B (en) * 2010-12-24 2012-05-16 中科协鑫（苏州）工业研究院有限公司 Method for depositing polycrystalline silicon by adopting surface microstructure silicon core
CN104118879B (en) * 2014-08-06 2016-06-22 四川永祥多晶硅有限公司 A kind of preparation method of silicon core masterbatch

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