CN109252216B - Device and process for preparing polycrystalline silicon by purifying under controlled heating temperature field - Google Patents
Device and process for preparing polycrystalline silicon by purifying under controlled heating temperature field Download PDFInfo
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- CN109252216B CN109252216B CN201811378303.1A CN201811378303A CN109252216B CN 109252216 B CN109252216 B CN 109252216B CN 201811378303 A CN201811378303 A CN 201811378303A CN 109252216 B CN109252216 B CN 109252216B
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
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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
- C01B33/037—Purification
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
- C30B28/04—Production of homogeneous polycrystalline material with defined structure from liquids
- C30B28/06—Production of homogeneous polycrystalline material with defined structure from liquids by normal freezing or freezing under temperature gradient
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Abstract
The invention discloses a device for purifying and preparing polycrystalline silicon by controlling a heating temperature field, wherein a heat insulation plate, a cooling disc, a crucible, a heating induction coil and a heat insulation cylinder are arranged in a furnace body, an upper section graphite heating ring, a middle section graphite heating ring and a lower section graphite heating ring are arranged in the heat insulation cylinder, connecting rings are arranged between the upper section graphite heating ring and the middle section graphite heating ring and between the middle section graphite heating ring and the lower section graphite heating ring, and the connecting rings are made of high-temperature-resistant materials with heat conductivity coefficients of 10-50W/m.k. The purification process comprises the following steps: introducing cooling gas into the cooling disc; introducing inert gas into the furnace body, and discharging the inert gas through an exhaust pipe arranged at the top of the furnace body to ensure that certain air pressure exists in the furnace body; and controlling the upper section graphite heating ring, the middle section graphite heating ring and the lower section graphite heating ring to cool according to a certain program. The invention is beneficial to forming uniform temperature gradient, is beneficial to crystal growth, and can effectively prevent the stepped thermal field from being stepped from top to bottom.
Description
Technical Field
The invention relates to the technical field of photovoltaics, in particular to a device and a process for preparing polycrystalline silicon by purifying under the control of a heating temperature field.
Background
At present, solar energy becomes the most concerned green energy, polycrystalline silicon is the most widely applied solar cell material at present, and directional solidification is an effective metallurgy purification means for obtaining solar-grade polycrystalline silicon materials. Directional solidification is a technique in which a temperature gradient in a specific direction is established in a solidified metal melt and an unsolidified metal melt by adopting a forced means in a solidification process, so that the melt is solidified in a direction opposite to a heat flow, and finally, columnar crystals with specific orientation are obtained. The directional solidification is an important means for researching the solidification theory and the metal solidification rule, and is also an important method for preparing single crystal materials, micron-scale (or nano-scale) continuous fiber crystal high-performance structural materials and functional materials. Directional solidification technology has developed rapidly since the 60's of the 20 th century. The method develops from the initial heat generating agent method and the power reduction method to the high-speed solidification method, the liquid metal cooling method and the continuous directional solidification technology which are widely applied at present. The directional solidification technology is widely applied to the preparation of equiforce surfaces of high-temperature alloys, magnetic materials, single crystal growth, autogenous composite materials and the like, and has extremely wide application prospect in the fields of single crystal-like intermetallic compounds and shape memory alloys.
One of the current directional solidification methods is a power reduction method, wherein the power of a melt external heating system is continuously reduced from top to bottom, the upper part has high power, more heat is generated, the temperature is high, the lower part has low power, less heat is generated, the temperature is low, heat flow is from top to bottom, a certain temperature gradient is formed, and the size of the temperature gradient can be adjusted by controlling the power. However, the temperature field control of the power-down method is discontinuous, and the thermal field is stepped from top to bottom, which is not favorable for the growth of columnar crystals.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the invention provides a device and a process for purifying and preparing polycrystalline silicon by controlling a heating temperature field, which solve the problems that the temperature field control of the existing power reduction method is discontinuous, the thermal field is in step mutation from top to bottom, and the growth of columnar crystals is not facilitated.
The invention is realized by the following technical scheme:
the device for preparing the polycrystalline silicon by purifying the heating temperature field is controlled, and comprises a furnace body, wherein a heat insulation plate is arranged in the furnace body, a through hole is formed in the middle of the heat insulation plate and is used for accommodating a cooling disc, a crucible is placed on the cooling disc, a heating induction ring and a heat insulation cylinder are sleeved outside the crucible, an upper section graphite heating ring, a middle section graphite heating ring and a lower section graphite heating ring are arranged in the heat insulation cylinder, connecting rings are arranged between the upper section graphite heating ring and the middle section graphite heating ring and between the middle section graphite heating ring and the lower section graphite heating ring, and the connecting rings are made of high-temperature-resistant materials with heat conductivity coefficient of 10-50W/m.k.
The working principle of the invention is that firstly, an upper section graphite heating ring, a middle section graphite heating ring and a lower section graphite heating ring are sequentially arranged from top to bottom along the axial direction of a crucible, the three sections of graphite heating rings are independently controlled by corresponding heating induction coils to realize temperature field adjustment from high to low, and meanwhile, a cooling disc arranged at the bottom of the crucible is used for cooling, and finally, a temperature gradient in the vertical direction is formed for directional solidification of industrial silicon; the upper section graphite heating ring and the middle section graphite heating ring are connected through the connecting ring, the middle section graphite heating ring and the lower section graphite heating ring are connected through the connecting ring, and the connecting ring is made of a high-temperature-resistant material with a heat conductivity coefficient of 10-50W/m.k, so that in the process of gradually cooling each section of graphite heating ring, due to the fact that temperature drop is slower relative to a graphite heating body, an even temperature transition zone is favorably formed between the two adjacent sections of graphite heating rings, an even temperature gradient is formed, and crystal growth is favorably realized. If the heat conductivity coefficient of the material for manufacturing the connecting ring is too large, the temperature rising and reducing effects of the connecting ring are faster than those of the graphite heating rings at the two ends, a uniform transition zone is not easy to form, and if the heat conductivity coefficient is too small, the transition effect is not obvious; therefore, the stepped thermal field is easy to have step mutation from top to bottom when the heat conductivity coefficient of the connecting ring is too large or too small, which is not beneficial to crystal growth.
Preferably, the connection ring is made of zirconia ceramic or alumina ceramic.
The heat conductivity coefficient of the zirconia ceramics or the alumina ceramics meets the specification, and the high-temperature stability is good.
Preferably, the side wall of the connecting ring is provided with a plurality of through holes.
The through holes are formed in the side wall of the connecting ring, so that the inert gas is introduced into the furnace body and fills the through holes, and the effect of adjusting the heat dissipation effect of the connecting ring is achieved; in addition, the whole weight of the connecting ring is favorably reduced, the bottom layer graphite heating ring is prevented from being excessively extruded, and the carrying is convenient and easy; during the carrying process, the lifting pieces such as the hooks can be directly embedded into the through holes for carrying and lifting.
Preferably, the bottom in the heat-insulating cylinder is provided with a limit ring plate, and the inner diameter of the limit ring plate is smaller than the inner diameters of the upper graphite heating ring, the middle graphite heating ring, the lower graphite heating ring and the connecting ring.
The bottom in the heat-insulating cylinder is provided with the limiting ring plate which is mainly used for supporting and limiting the graphite heating rings and the connecting rings at all sections.
Preferably, the cooling disc comprises a cylindrical shell, a gas distribution sleeve I and a gas distribution sleeve П which are coaxial are arranged in the shell, the gas distribution sleeve П is sleeved outside the gas distribution sleeve I, the outer diameter of the gas distribution sleeve П is smaller than the inner diameter of the shell, and the inner diameter of the gas distribution sleeve П is larger than the outer diameter of the gas distribution sleeve I;
the inner parts of the side walls of the gas distribution sleeve I and the gas distribution sleeve П are both annular hollow cavity structures, and the inner side wall of the gas distribution sleeve П and the outer side wall of the gas distribution sleeve I are both provided with vent holes;
the bottom of the shell is provided with an annular air inlet chamber along the circumferential direction, and the air inlet chamber is communicated with the hollow chamber of the air distribution sleeve I, the hollow chamber of the air distribution sleeve П and the annular chamber between the outer wall of the air distribution sleeve I and the inner wall of the air distribution sleeve П through air inlets;
the bottom of the shell is circumferentially provided with an annular exhaust chamber which is communicated with an annular chamber between the outer wall of the gas distribution sleeve П and the inner wall of the shell through an exhaust hole;
an exhaust pipe is further arranged at the geometric center of the bottom of the shell and is communicated with the inner environment of the gas distribution sleeve I through an exhaust hole;
and an air inlet pipeline is arranged on the air inlet chamber, and exhaust pipelines are arranged on the exhaust chamber and the exhaust pipe.
The existing method for cooling and directionally solidifying the bottom of a crucible by independently adopting a cooling disc or combining the cooling disc with the solidified melt to move out of an induction area downwards so as to obtain the unidirectional temperature gradient has the defects of central supercooling or vibration of the solidified melt and the like, thereby causing adverse effects on the growth of crystals.
The silicon ingot furnace is characterized in that gas is introduced into a gas inlet chamber through a gas inlet pipeline, and the gas in the gas inlet chamber enters a shell through two ways, wherein one way is that the gas enters a hollow chamber of a gas distribution sleeve I and a hollow chamber of a gas distribution sleeve П through a gas inlet hole, then enters an annular chamber between the outer wall of the gas distribution sleeve I and the inner wall of a gas distribution sleeve П through corresponding vent holes on the outer wall of the gas distribution sleeve I and vent holes on the inner wall of the gas distribution sleeve П to be converged and perform a convection heat exchange effect with a crucible through the top of the shell, the other way is that the gas directly enters the annular chamber between the outer wall of the gas distribution sleeve I and the inner wall of the gas distribution sleeve П through the gas inlet hole, the vent holes on the outer wall of the gas distribution sleeve I and the vent holes on the inner wall of the gas distribution sleeve П are oppositely arranged, two gas flows collide with each other, the gas flow direction directly enters the annular chamber between the outer wall of the gas distribution sleeve I and the inner wall of the gas distribution sleeve П to be vertical to the gas flow directions of the two converged gas flows, so that the disturbance of the gas flows is greatly promoted, the gas is favorably distributed at the top of the.
In addition, the solidified melt is moved out of the induction area downwards by the cooling of the conventional common matching cooling disc, so that a unidirectional temperature gradient is obtained, the downward movement method of the solidified melt can generate vibration and cause adverse effects on crystal growth.
Preferably, a cover plate is arranged at the open end of the top of the shell, and the cover plate is detachably connected through a graphite bolt; the cover plate is made of a graphite heat conducting plate.
The cover plate is connected with the shell through the graphite bolt, so that the disassembly, assembly and maintenance operations are convenient. The cover plate is made of the graphite heat conducting plate, so that a good cooling effect is guaranteed, and energy consumption is reduced.
Preferably, the inner plate surface of the cover plate is provided with a plurality of radiating fins which are radially arranged by taking the geometric center of the cover plate as a base point.
Through arranging the radiating fins to form a radial structure, the radiating is promoted, and meanwhile, the gas coming out from the annular chamber between the outer wall of the gas distribution sleeve I and the inner wall of the gas distribution sleeve П is guided, distributed to the central part of the gas distribution sleeve I, the outer wall of the gas distribution sleeve П and the annular chamber in the support of the inner wall of the shell to flow for heat exchange and discharge.
The purification process of the device for preparing the polycrystalline silicon by purifying based on the controlled heating temperature field is characterized by comprising the following steps of:
step 2, introducing inert gas into the furnace body, and discharging the inert gas through an exhaust pipe arranged at the top of the furnace body to ensure that certain air pressure exists in the furnace body;
and 3, controlling the upper section graphite heating ring to cool according to the following procedures: reducing the temperature from 1480 ℃ to 1360 ℃ at a cooling rate of 3 ℃/h and keeping the temperature stable;
controlling the middle section graphite heating ring to cool according to the following procedures: the temperature is reduced from 1480 ℃ to 1100 ℃ at the cooling rate of 4 ℃/h and kept stable;
controlling the lower section graphite heating ring to cool according to the following procedures: the temperature is reduced from 1480 to 900 ℃ at a cooling rate of 5 ℃/h and remains stable.
Preferably, the inert gas is nitrogen or argon.
Preferably, in the step 2, the flow rate of the gas in the furnace body is 18-25L/h, and the gas pressure is 0.2-0.5 MPa.
The invention has the following advantages and beneficial effects:
1. the working principle of the invention is that firstly, an upper section graphite heating ring, a middle section graphite heating ring and a lower section graphite heating ring are sequentially arranged from top to bottom along the axial direction of a crucible, the three sections of graphite heating rings are independently controlled by corresponding heating induction coils to realize temperature field adjustment from high to low, and meanwhile, a cooling disc arranged at the bottom of the crucible is used for cooling, and finally, a temperature gradient in the vertical direction is formed for directional solidification of industrial silicon; the upper section graphite heating ring and the middle section graphite heating ring are connected through the connecting ring, the middle section graphite heating ring and the lower section graphite heating ring are connected through the connecting ring, and the connecting ring is made of a high-temperature-resistant material with a heat conductivity coefficient of 10-50W/m.k, so that in the process of gradually cooling each section of graphite heating ring, due to the fact that temperature drop is slower relative to a graphite heating body, an even temperature transition zone is favorably formed between the two adjacent sections of graphite heating rings, an even temperature gradient is formed, and crystal growth is favorably realized. If the heat conductivity coefficient of the material for manufacturing the connecting ring is too large, the temperature rising and reducing effects of the connecting ring are faster than those of the graphite heating rings at the two ends, a uniform transition zone is not easy to form, and if the heat conductivity coefficient is too small, the transition effect is not obvious; therefore, the stepped thermal field is easy to have step mutation from top to bottom when the heat conductivity coefficient of the connecting ring is too large or too small, which is not beneficial to crystal growth.
The through holes are formed in the side wall of the connecting ring, so that the inert gas is introduced into the furnace body and fills the through holes, and the effect of adjusting the heat dissipation effect of the connecting ring is achieved; in addition, the whole weight of the connecting ring is favorably reduced, the bottom layer graphite heating ring is prevented from being excessively extruded, and the carrying is convenient and easy; during the transportation process, the lifting pieces such as the hooks can be directly embedded into the through holes for transportation and lifting operation;
2. in the prior art, a cooling disc is adopted to cool and directionally solidify the bottom of a crucible or a solidified melt is moved out of an induction zone downwards in a combined manner, so that the defects of central supercooling or solidified melt vibration and the like exist in the operation process of obtaining a unidirectional temperature gradient, and adverse effects are caused on crystal growth.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic view of the structure of the installation position of the cooling plate according to the present invention;
FIG. 2 is a schematic view of a radial cross-sectional perspective view of a cooling plate of the present invention;
FIG. 3 is a schematic view of a circumferential cross-section of a cooling plate according to the present invention;
FIG. 4 is a schematic bottom view of the cover plate of the present invention;
FIG. 5 is a schematic view of the structure of the heat-insulating cylinder of the present invention;
fig. 6 is a schematic structural view of the graphite heater of the present invention.
The names of the parts marked in the drawing and corresponding to the parts are 1-a cooling disc, 101-a shell, 102-a gas distribution sleeve I, 103-a gas distribution sleeve П, 104-a vent hole, 105-an air inlet chamber, 106-an air inlet hole, 107-an air outlet chamber, 108-an air outlet hole, 109-an air outlet pipe, 110-an air inlet pipeline, 111-an air outlet pipeline, 112-a cover plate, 113-a graphite bolt, 114-a radiating fin, 115-a sealing groove, 2-a furnace body, 3-a heat insulating plate, 4-a crucible, 5-a heating induction ring, 6-a heat insulating cylinder, 7-an upper section graphite heating ring, 8-a middle section graphite heating ring, 9-a lower section graphite heating ring, 10-a connecting ring, 11-a through hole and 12-a limiting ring plate.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1
The embodiment provides a device for purifying and preparing polycrystalline silicon by controlling a heating thermal field, which comprises a furnace body 2, wherein a heat insulation plate 3 is arranged in the furnace body 2, a through hole is formed in the middle of the heat insulation plate 3 and used for accommodating a cooling disc 1, a crucible 4 is arranged on the cooling disc 1, a heating induction coil 5 and a heat insulation cylinder 6 are sleeved outside the crucible 4, an upper graphite heating ring 7, a middle graphite heating ring 8 and a lower graphite heating ring 9 are arranged in the heat insulation cylinder 6, connecting rings 10 are arranged between the upper graphite heating ring 7 and the middle graphite heating ring 8 and between the middle graphite heating ring 8 and the lower graphite heating ring 9, and the connecting rings 10 are made of high-temperature-resistant materials with heat conductivity of 10-50W/m.k. The graphite heating body is formed by connecting the upper section graphite heating ring 7, the middle section graphite heating ring 8, the lower section graphite heating ring 9 and the two connecting rings 10 as a whole as shown in fig. 6.
Example 2
The improvement is further improved on the basis of the embodiment 1, the connecting ring is made of zirconia ceramics or alumina ceramics, and a plurality of through holes 11 are arranged on the side wall of the connecting ring 10. The bottom in the heat preservation cylinder 6 is provided with a limit ring plate 12, and the inner diameter of the limit ring plate 12 is smaller than the inner diameters of the upper graphite heating ring 7, the middle graphite heating ring 8, the lower graphite heating ring 9 and the connecting ring 10.
Example 3
The cooling disc 1 further improves the embodiment 2, and comprises a cylindrical shell 101, wherein a gas distribution sleeve I102 and a gas distribution sleeve П 103 which are coaxial are arranged in the shell 101, the gas distribution sleeve П 103 is sleeved outside the gas distribution sleeve I102, the outer diameter of the gas distribution sleeve П 103 is smaller than the inner diameter of the shell 101, and the inner diameter of the gas distribution sleeve П 103 is larger than the outer diameter of the gas distribution sleeve I102;
the inner parts of the side walls of the gas distribution sleeve I102 and the gas distribution sleeve П 103 are both annular hollow cavity structures, and the inner side wall of the gas distribution sleeve П 103 and the outer side wall of the gas distribution sleeve I102 are both provided with vent holes 104;
an annular air inlet chamber 105 is arranged at the bottom of the shell 101 along the circumferential direction, and the air inlet chamber 105 is communicated with a hollow chamber of the air distribution sleeve I102, a hollow chamber of the air distribution sleeve П 103 and an annular chamber between the outer wall of the air distribution sleeve I102 and the inner wall of the air distribution sleeve П 103 through an air inlet hole 106;
an annular exhaust chamber 107 is arranged at the bottom of the shell 101 along the circumferential direction, and the exhaust chamber 107 is communicated with an annular chamber between the outer wall of the gas distribution sleeve П 103 and the inner wall of the shell 101 through an exhaust hole 108;
an exhaust pipe 109 is further arranged at the geometric center of the bottom of the shell 101, and the exhaust pipe 109 is communicated with the cylinder environment of the gas distribution sleeve I102 through an exhaust hole 108;
an air inlet pipeline 110 is arranged on the air inlet chamber 105, and an air outlet pipeline 111 is arranged on the air outlet chamber 107 and the air outlet pipe 109.
The gas distribution sleeve I102 is provided with a plurality of vent holes 104, the vent holes 104 are arranged on the inner side wall of the gas distribution sleeve П 103 in a staggered manner, the top open end of the shell 101 is provided with a cover plate 112, the cover plate 112 is detachably connected through a graphite bolt 113, a sealing groove 115 is formed on the lower plate surface of the cover plate 112 close to the outer edge along the circumferential direction, a sealing gasket is arranged in the sealing groove 115, the top open end of the shell 101 is embedded into the sealing groove 115 to be in over-fit and press-fixing with the sealing gasket, the cover plate 112 is made of a graphite heat conducting plate, the inner plate surface of the cover plate 112 is provided with a plurality of radiating fins 114, the radiating fins 114 are radially arranged by taking the geometric center of the cover plate 112 as a base.
Example 4
Based on the device provided by the embodiment 3, the process for preparing the polycrystalline silicon by purifying the heating temperature field is controlled, and the specific steps are as follows:
step 2, introducing inert gas into the furnace body, and discharging the inert gas through an exhaust pipe arranged at the top of the furnace body to ensure that certain air pressure exists in the furnace body;
and 3, controlling the upper section graphite heating ring 7 to cool according to the following procedures: reducing the temperature from 1480 ℃ to 1360 ℃ at a cooling rate of 3 ℃/h and keeping the temperature stable; and controlling the middle section graphite heating ring 8 to cool according to the following procedures: the temperature is reduced from 1480 ℃ to 1100 ℃ at the cooling rate of 4 ℃/h and kept stable; the lower section graphite heating ring 9 is controlled to be cooled according to the following procedures: the temperature is reduced from 1480 to 900 ℃ at a cooling rate of 5 ℃/h and remains stable.
The inert gas is argon, the flow rate of the argon in the furnace body is 18-25L/h, and the air pressure is 0.2-0.5 MPa.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. Device of preparation polycrystalline silicon is purified in control heating temperature field, including furnace body (2), be equipped with heat insulating board (3) in furnace body (2), heat insulating board (3) middle part is seted up the through-hole and is used for holding cooling disc (1), places crucible (4) on cooling disc (1), and crucible (4) overcoat is equipped with heating induction coil (5) and heat preservation section of thick bamboo (6), its characterized in that, be equipped with upper graphite heating ring (7), middle section graphite heating ring (8) and hypomere graphite heating ring (9) in heat preservation section of thick bamboo (6), and between upper graphite heating ring (7) and middle section graphite heating ring (8) and between middle section graphite heating ring (8) and hypomere graphite heating ring (9) all be equipped with go-between (10), go-between (10) adopt the high temperature resistant material that coefficient is 10 ~ 50W/m.k to make.
2. The device for purifying and preparing the polycrystalline silicon by the controlled heating temperature field as claimed in claim 1, wherein the connecting ring is made of zirconia ceramic or alumina ceramic.
3. The device for purifying and preparing the polysilicon by controlling the heating temperature field according to claim 1, wherein the side wall of the connecting ring (10) is provided with a plurality of through holes (11).
4. The device for purifying and preparing the polycrystalline silicon by the controlled heating temperature field is characterized in that a limiting ring plate (12) is arranged at the bottom in the heat preservation cylinder (6), and the inner diameter of the limiting ring plate (12) is smaller than the inner diameters of the upper graphite heating ring (7), the middle graphite heating ring (8), the lower graphite heating ring (9) and the connecting ring (10).
5. The device for purifying and preparing the polycrystalline silicon by controlling the heating temperature field according to the claim 1 is characterized in that the cooling plate (1) comprises a cylindrical shell (101), a gas distribution sleeve I (102) and a gas distribution sleeve П (103) which are coaxial are arranged in the shell (101), the gas distribution sleeve П (103) is sleeved outside the gas distribution sleeve I (102), the outer diameter of the gas distribution sleeve П (103) is smaller than the inner diameter of the shell (101), and the inner diameter of the gas distribution sleeve П (103) is larger than the outer diameter of the gas distribution sleeve I (102);
the insides of the side walls of the gas distribution sleeve I (102) and the gas distribution sleeve П (103) are both annular hollow cavity structures, and the inside wall of the gas distribution sleeve П (103) and the outside wall of the gas distribution sleeve I (102) are both provided with vent holes (104);
an annular air inlet chamber (105) is arranged at the bottom of the shell (101) along the circumferential direction, and the air inlet chamber (105) is communicated with a hollow chamber of the air distribution sleeve I (102), a hollow chamber of the air distribution sleeve П (103) and an annular chamber between the outer wall of the air distribution sleeve I (102) and the inner wall of the air distribution sleeve П (103) through an air inlet hole (106);
an annular exhaust chamber (107) is arranged at the bottom of the shell (101) along the circumferential direction, and the exhaust chamber (107) is communicated with an annular chamber between the outer wall of the gas distribution sleeve П (103) and the inner wall of the shell (101) through an exhaust hole (108);
an exhaust pipe (109) is further arranged at the geometric center of the bottom of the shell (101), and the exhaust pipe (109) is communicated with the cylinder inner environment of the gas distribution sleeve I (102) through an exhaust hole (108);
an air inlet pipeline (110) is arranged on the air inlet chamber (105), and an air outlet pipeline (111) is arranged on the air outlet chamber (107) and the air outlet pipe (109).
6. The device for preparing the polysilicon through the purification of the controlled heating temperature field according to the claim 5 is characterized in that the open top end of the shell (101) is provided with a cover plate (112), and the cover plate (112) is detachably connected through a graphite bolt (113); the cover plate (112) is made of a graphite heat conducting plate.
7. The device for preparing polysilicon by purifying through the controlled heating temperature field as claimed in claim 6, wherein the inner plate surface of the cover plate (112) is provided with a plurality of heat dissipation fins (114), and the heat dissipation fins (114) are radially arranged by taking the geometric center of the cover plate (112) as a base point.
8. The purification process of the device for purifying and preparing the polysilicon based on the controlled heating temperature field as claimed in any one of claims 1 to 7, is characterized by comprising the following steps:
step 1, introducing cooling gas into a cooling disc;
step 2, introducing inert gas into the furnace body, and discharging the inert gas through an exhaust pipe arranged at the top of the furnace body to ensure that certain air pressure exists in the furnace body;
and 3, controlling the upper section graphite heating ring (7) to cool according to the following procedures: reducing the temperature from 1480 ℃ to 1360 ℃ at a cooling rate of 3 ℃/h and keeping the temperature stable;
controlling the middle section graphite heating ring (8) to cool according to the following procedures: the temperature is reduced from 1480 ℃ to 1100 ℃ at the cooling rate of 4 ℃/h and kept stable;
controlling the lower section graphite heating ring (9) to cool according to the following procedures: the temperature is reduced from 1480 to 900 ℃ at a cooling rate of 5 ℃/h and remains stable.
9. The purification process for controlling the heating temperature field to purify the device for preparing polysilicon according to claim 8, wherein the inert gas is nitrogen or argon.
10. The purification process of the device for preparing polysilicon by controlling the heating temperature field according to claim 9, wherein in the step 2, the flow rate of the gas in the furnace body is 18-25L/h, and the gas pressure is 0.2-0.5 MPa.
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| CN204738044U (en) * | 2015-06-26 | 2015-11-04 | 湖南南方搏云新材料有限责任公司 | Three section formula die -pin for single crystal growing furnace |
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| JP2018048043A (en) * | 2016-09-21 | 2018-03-29 | 国立大学法人信州大学 | Manufacturing apparatus for lithium tantalate crystal, and manufacturing method for lithium tantalate crystal |
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| CN204738044U (en) * | 2015-06-26 | 2015-11-04 | 湖南南方搏云新材料有限责任公司 | Three section formula die -pin for single crystal growing furnace |
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