CN107815731B - Polycrystal ingot furnace with gas-carrying heating device - Google Patents

Abstract

The invention discloses a polycrystal ingot furnace with a carrier gas heating device, which comprises a drainage device and a heating device, wherein the drainage device is assembled in the ingot furnace and used for conveying carrier gas into the furnace, the heating device is used for heating the carrier gas, the output end of the heating device is communicated with the input end of the drainage device, and the input end of the heating device is communicated with a gas conveying pipe of the carrier gas. The cold carrier gas is heated by the heating device to form hot carrier gas with higher temperature, and the hot carrier gas is blown to eject the silicon material in the crucible through the drainage device; the supercooling degree of the liquid silicon in the blowing and jetting area is reduced, and impurity nucleation and impurity nucleus growth promoted by carrier gas in the liquid silicon are reduced or even eliminated.

Description

Polycrystal ingot furnace with gas-carrying heating device

The application is a divisional application of a patent application with the application number of 201610082945.1 and the application date of 2016-02-03 and the name of a polycrystal ingot furnace with a gas-carrying heating device.

Technical Field

The invention relates to a polycrystal ingot furnace, in particular to a polycrystal ingot furnace with a gas-carrying heating device, and belongs to the field of crystal growth equipment.

Background

The polycrystal ingot furnace comprises a furnace body, a heat insulation cage, a heater, a heat exchange platform and a drainage device. The heater comprises a top heater and a side heater, and is arranged in the heat insulation cage; the heat exchange platform is assembled in the lower furnace body through the graphite upright post and is positioned in the heat insulation cage. The crucible filled with the silicon material is placed on the heat exchange platform and is positioned in the side heater; the flow guiding device penetrates through and is assembled on a top heat insulation plate of the heat insulation cage, and an outlet at the lower end of the flow guiding device faces to the central part of the crucible and is used for conveying carrier gas. The ingot furnace adopts five-surface heating on four sides and the top surface, so that the temperature of the four sides of the liquid silicon in the crucible is higher than that of the middle part, and a natural convection flow field with the four sides of the liquid silicon floating upwards and the middle of the liquid silicon sinking downwards is formed. If the melting degree of some impurities (such as carbon and nitrogen) melted in the liquid silicon with higher temperature on the four sides reaches or approaches saturation, when the liquid silicon flows to the middle part, the melting degree of the impurities reaches supersaturation due to temperature reduction, and the impurities such as carbon and nitrogen are nucleated and separated out; the impurity nuclei drop in temperature with the falling of the liquid flow and grow gradually to form impurity inclusions. Cold carrier gas is intensively and vertically blown to a central area of the liquid silicon through an outlet of the drainage device, the carrier gas carries a large amount of heat from the liquid silicon in the central area, the temperature of the liquid silicon in the central area is further reduced, the supercooling degree is enhanced, and therefore supersaturation nucleation and precipitation of impurities such as carbon, nitrogen and the like in the liquid silicon are promoted, and growth of impurity nuclei is promoted to form macroscopic impurities such as silicon carbide impurities and silicon nitride impurities. Silicon carbide impurities are electrically active and affect the conversion efficiency of solar cells. Therefore, it is highly desirable to develop a polycrystal ingot furnace with a carrier gas heating device, which heats cold carrier gas into hot carrier gas with higher temperature, and then blows liquid silicon in a crucible by a flow guiding device to reduce impurity nucleation and impurity nucleus growth caused by the carrier gas in the liquid silicon.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a polycrystalline ingot furnace with a gas-carrying heating device. To overcome the problems existing in the prior art: the cold carrier gas is intensively blown to a certain area, such as the middle area, of the surface of the liquid silicon, and the carrier gas takes away a large amount of heat from the area, so that the area is greatly cooled, the liquid silicon is overcooled, and impurity nucleation and impurity nucleus growth in the liquid silicon are promoted to form impurity inclusions.

The invention provides a polycrystal ingot furnace with a carrier gas heating device and a flow guide device, which comprises a heat insulation cage and a flow guide pipe, wherein the heat insulation cage is a cavity mainly composed of a side heat insulation plate, a top heat insulation plate and a bottom heat insulation plate, and the design key points are as follows: the gas-carrier heating device comprises a flow guide cylinder part and an air inlet table part, wherein the flow guide cylinder part is fixedly connected with the air inlet table part, the flow guide cylinder part is a cylinder provided with a through hole along the central line direction of the flow guide cylinder part, and the air inlet table part is arranged outside the flow guide cylinder part; an annular shunt cavity which is concentric with the flow guide cylinder part is arranged in the cylinder wall at the upper end part of the flow guide cylinder part; an air inlet hole for carrier gas to flow into is arranged in the air inlet table part, and the air inlet hole is communicated with the flow dividing cavity through a communicating air passage; at least one guide air passage extending downwards from the lower end face of the diversion cavity along a non-uniform-pitch cylindrical spiral line is arranged in the cylinder wall of the guide cylinder part, and an outlet of the guide air passage is positioned at the lower end of the guide cylinder part; the guide pipe is assembled on the top heat insulation plate, and the lower end of the guide pipe penetrates through the through hole in the middle of the top heat insulation plate and extends out of the lower end face of the top heat insulation plate; the flow guide device is axially and fixedly connected with the lower end part of the flow guide pipe; the output end of the heating device is communicated with the air inlet of the flow guide device through a matching pipeline, and the input end of the heating device is communicated with the carrier gas conveying pipe.

In application, the polycrystalline ingot furnace provided by the invention also has the following further preferable technical scheme.

Preferably, one end of the communicating air channel is tangentially communicated with the air inlet hole, and the other end of the communicating air channel is tangentially communicated with the side surface of the shunting cavity.

Preferably, the heating device is an air heater, a heat insulation layer is arranged in a shell of the air heater, the output end of the air heater is communicated with the air inlet of the flow guide device through a matching and connecting pipeline, and the output end of the air heater is communicated with a gas conveying pipe for carrier gas; and the outside of the adapting pipe is coated with a heat insulation layer.

Preferably, the air heater is a ribbed tube air heater.

Preferably, the heating device is a heating pipe, the heating pipe is arranged in a heat insulation cage of the ingot furnace, the output end of the heating pipe is communicated with the air inlet of the flow guiding device through a matching and connecting pipeline, and the output end of the heating pipe is communicated with the gas conveying pipe of the carrier gas.

Preferably, the heating pipes are distributed in a circuitous manner and are arranged between the heater and the heat insulation cage of the ingot furnace.

Preferably, the heating pipe is a finned pipe and is arranged between a top heater of the heater and a top heat insulation plate of the heat insulation cage.

Preferably, the material of the ribbed pipe and the heating pipe is molybdenum, tungsten or titanium.

Preferably, the pitch of the spiral line of the outlet section of the guide air passage is gradually reduced, and the outlet of the guide air passage is positioned on the lower end surface of the guide cylinder part; or,

the screw pitch of the spiral line of the outlet section of the flow guide air passage is gradually reduced, the radius is gradually increased, and the outlet of the flow guide air passage is positioned at the lower end of the outer side surface of the flow guide cylinder part or the intersection of the outer side surface and the lower end surface of the flow guide cylinder part.

Preferably, the number of the diversion air passages is 3, 4 or 5, and the diversion air passages are uniformly distributed around the central line of the diversion device.

Preferably, the material of guiding device is graphite or molybdenum.

The flow guiding device of the polycrystalline ingot furnace is internally provided with a plurality of flow guiding air passages for changing the flow direction of carrier gas, the outlets of the flow guiding air passages are uniformly distributed along the same angular direction around the central line of the flow guiding device, the carrier gas is divided into a plurality of carrier gas flows through the flow guiding device, the plurality of carrier gas flows are scattered and obliquely blown to different areas of the surface of the liquid silicon to generate carrier gas stress which is circumferentially distributed around the center of the liquid silicon, the carrier gas stress drives the liquid silicon on the surface layer to flow, and a rotary flow field which circumferentially flows is formed in the liquid silicon. The rotating flow field is beneficial to conveying impurities in the liquid silicon to the surface and promoting the volatilization of the impurities; the method is beneficial to the transportation and uniform distribution of impurities in the liquid silicon, and the radial resistivity of the crystal is more uniform. The field of view leading to the ingot furnace in the flow guide device is not blocked, the state of a silicon material in the furnace can be seen through an observation window at the top of the furnace, and a crystal measuring rod is inserted to measure the growth speed of the crystal; the infrared detector can detect the state of the silicon material in the furnace. The cold carrier gas is heated by the heating device to form hot carrier gas with higher temperature, and then the hot carrier gas is blown to the silicon material in the crucible through the drainage device. When the temperature of the carrier gas is lower than that of the liquid silicon, the heat taken away by the carrier gas from the liquid silicon in the blown area is less, the temperature drop amplitude of the liquid silicon in the area is greatly reduced, the probability of nucleation of impurities caused by the carrier gas in the liquid silicon is reduced, and the formation of the impurities promoted by the carrier gas is reduced or even eliminated; when the temperature of the carrier gas is higher than that of the liquid silicon in the blowing and jetting area, the carrier gas supplies heat to the liquid silicon in the blowing and jetting area, so that the temperature of the liquid silicon in the area is increased, the radial temperature difference in the liquid silicon is reduced, and the impurity nucleation and the impurity nucleus growth in the liquid silicon in the area are inhibited.

Advantageous effects

Local supercooling caused by carrier gas in the liquid silicon is reduced or even eliminated, the cold carrier gas is heated by the heating device to form hot carrier gas by arranging the heating device of the carrier gas, and then the hot carrier gas is blown to the liquid silicon; when the temperature of the hot carrier gas is lower than that of the liquid silicon, the heat taken away by the carrier gas from the liquid silicon in the blown area is greatly reduced, the temperature drop of the liquid silicon in the area is greatly reduced, the supercooling degree is reduced, the nucleation probability of impurities caused by the carrier gas in the liquid silicon is reduced, and the formation of the impurities promoted by the carrier gas is reduced or even eliminated; when the temperature of the hot carrier gas is higher than that of the liquid silicon, the carrier gas supplies heat to the liquid silicon in the blown area, so that the temperature of the liquid silicon is increased, the radial temperature difference in the liquid silicon is reduced, the impurity nucleation in the liquid silicon in the area is inhibited, the formation of impurities promoted by the carrier gas is eliminated, and the quality of crystals is improved.

The observation window on the top of the furnace is provided with a view field leading to the interior of the ingot furnace, and the view field leading to the interior of the ingot furnace in the flow guide device is not blocked by arranging an air inlet platform part (an air inlet pipe part) of the flow guide device outside a matching barrel part/flow guide barrel part (a flow distribution chamber part) of the flow guide device; the condition in the ingot furnace can be observed through the observation window on the top of the furnace, so that the furnace operation is convenient; the crystal measuring bar can penetrate through the flow guide device to be inserted into the ingot furnace, and the growth speed of the crystal is convenient to measure; the infrared detector can detect the state of the silicon material in the ingot furnace through the observation window, and the automatic crystal growth process is smoothly carried out.

The local temperature drop caused by the carrier gas in the liquid silicon is further reduced, the carrier gas is divided into a plurality of carrier gas flows by the plurality of flow guide channels of the flow guide device, the plurality of carrier gas flows are scattered and obliquely blown to different areas of the surface of the liquid silicon, the contact area between the carrier gas and the surface of the liquid silicon is effectively increased, the heat carried away by the carrier gas flows from the unit area is further reduced, the local temperature drop caused by the carrier gas flows is reduced, and the local temperature drop caused by the carrier gas in the liquid silicon is further reduced and even avoided.

The method has the advantages that the volatilization of impurities and the uniform distribution of the impurities are promoted, the quality of crystals is improved, the guide channels of the guide device are uniformly distributed around the center line of the guide device, carrier gas is divided into a plurality of carrier gas flows through the guide channels, the carrier gas flows are obliquely blown to different areas of the surface of the liquid silicon respectively, the blown areas of the carrier gas flows are distributed around the center of the surface of the liquid silicon, the carrier gas flows generate carrier gas stress for driving laminar flow to the liquid silicon, and the carrier gas stress drives the liquid silicon to flow to form a rotary flow field flowing around the center of the liquid silicon. The rotating flow field is beneficial to conveying the floating impurities on the surface of the liquid silicon to the edge of the liquid silicon, so that the influence of the floating impurities on the yield of crystals is reduced, and the yield of the crystals is improved; the method is also beneficial to conveying impurities in the liquid silicon to the surface of the liquid silicon and accelerating the volatilization of the impurities in the liquid silicon; under the combined action of the natural convection flow field and the rotary flow field, the liquid silicon is beneficial to the transportation and the uniform distribution of impurities in the liquid silicon, the local enrichment of the impurities is avoided, the radial resistivity distribution of the crystal is more uniform, and the quality of the crystal is further improved.

Drawings

Fig. 1 is a schematic structural view of a polycrystalline ingot furnace according to embodiment 1.

Fig. 2 is another schematic structural view of the polycrystalline ingot furnace according to embodiment 1.

Fig. 3 is an enlarged schematic view of the area of the thermal cage of fig. 2.

Fig. 4 is a view in the direction of a-a in fig. 3.

Fig. 5 is a schematic structural view of a polycrystalline ingot furnace according to embodiment 2.

Fig. 6 is an enlarged schematic view of the region a in fig. 5.

Fig. 7 is a schematic structural view of the deflector 20.

Fig. 8 is a schematic structural view of the adapter cylinder 21.

Fig. 9 is a view in the direction B-B in fig. 8.

Fig. 10 is a left side view of the adapter cartridge 21 of fig. 8.

Fig. 11 is a schematic bottom view of guide shell 22.

Fig. 12 is another structural schematic diagram of guide shell 22.

Fig. 13 is a view in the direction of C-C in fig. 12.

Fig. 14 is a schematic structural view of a polycrystalline ingot furnace according to embodiment 3.

Fig. 15 is an enlarged schematic view of region B in fig. 14.

Fig. 16 is a schematic view of a structure of the deflector 30.

Fig. 17 is a view in the direction of E-E in fig. 16.

Fig. 18 is a left side view of the deflector 30 of fig. 16.

Fig. 19 is a bottom schematic view of the deflector 30 of fig. 16.

Fig. 20 is another structural schematic view of the deflector 30.

Fig. 21 is a view in the direction F-F in fig. 20.

Fig. 22 is a schematic structural view of a polycrystalline ingot furnace according to embodiment 4.

Fig. 23 is an enlarged schematic view of region C in fig. 22.

Fig. 24 is a schematic view of a structure of the deflector 40.

Fig. 25 is a view in the direction of G-G in fig. 24.

In the figure, 11-furnace body, 12-drainage device, 13-cage, 131-lifting screw rod, 14-heat insulation cage, 15-heater, 16-heat exchange platform, 17-graphite upright post, 18-crucible, 19-silicon material, 90-infrared detector, 50-gas pipe, 20, 30, 40-guiding device, 60-heating device, 61-adapting pipe, 111-upper furnace body, 112-lower furnace body, 113-top end cover, 114-observation window, 121-adapting nut, 122-guiding pipe, 123-graphite pipe, 141-side heat insulation board, 142-top heat insulation board, 143-bottom heat insulation board, 151-side heater, 152-top heater, 181-graphite bottom board, 182-graphite guard plate, 183-cover plate, 21-adapting barrel, 22-a guide cylinder, 222, 36-a guide air channel, 217, 37, 46-internal threads, 224-external threads, 223-a flange, 211-a matching barrel part, 212, 32-an air inlet platform part, 213-an air inlet hole, 214, 34-a communicating air channel, 216-an annular step, 215-a first diversion cavity, 221-a second diversion cavity, 31-a guide barrel part, 35-a diversion cavity, 41-a diversion cavity part, 42-an air inlet pipe part, 43-a guide air pipe, 44-a communicating pipe and 45-a fastening part.

Detailed Description

In order to clarify the technical solution and technical object of the present invention, the present invention will be further described with reference to the accompanying drawings and the detailed description.

Embodiment mode 1

The polycrystal ingot furnace with the carrier gas heating device comprises an ingot furnace body 10 and a heating device 60 used for heating carrier gas, wherein the heating device 60 is communicated with the ingot furnace body 10 and used for conveying the heated carrier gas to the interior of the ingot furnace and blowing and jetting silicon materials 19 in a crucible, and the carrier gas carries impurities volatilized from the silicon materials 19 to the exterior of the furnace so as to improve the purity and the quality of crystals, as shown in figures 1 and 2.

The ingot furnace body 10 comprises a furnace body 11, a cage 13, a lifting screw rod 131, a heat insulation cage 14, a heater 15, a heat exchange platform 16, a graphite upright post 17, a graphite pipe 123, a drainage device 12, an infrared detector 90 and a copper electrode (not shown in the figure). The furnace body 11 comprises an upper furnace body 111, a lower furnace body 112 and a top end cover 113, wherein the upper furnace body 111 covers the lower furnace body 112, and the top end cover 113 covers the top end opening of the upper furnace body 111. A viewing window 114 is provided in the middle of the top end cap 113. The 6 copper electrodes are assembled on the top of the upper furnace body 111, distributed around the top opening of the furnace body, and fixed with the top of the furnace body in an insulating and sealing manner. The cage 13 is formed of a 4-sided ledge, with open top and bottom surfaces. The cage 13 is disposed in the furnace body 11 and suspended from the ceiling of the upper furnace body 111 by a lifting screw 131. The heat insulation cage 14 is a square cavity formed by four side heat insulation plates 141, one top heat insulation plate 142 and one bottom heat insulation plate 143. The heat insulation cage 14 is arranged in the cage 13, four-side heat insulation plates 141 of the heat insulation cage 14 are respectively fixed on the inner sides of four-side ledges of the cage 13, a top heat insulation plate 142 is suspended on the top of the upper furnace body 111 through a limit step on a copper electrode and is positioned in the four-side heat insulation plates 141, and a bottom heat insulation plate 143 is assembled above the bottom of the lower furnace body 112 through an annular step in the middle of the graphite upright post 17. The heater 15 includes a side heater 151 and a top heater 152, and the heater 15 is disposed within the insulation cage 14. The side heater 151 is disposed on the inner wall side of the side insulation plate 141 of the insulation cage with a space of 4-12cm therebetween; the top heater 15 is disposed on the lower end face side of the top insulation board 142 of the insulation cage with a space of 5-15cm therebetween. The heater 15 is fixedly connected with a copper electrode fixed on the top of the upper furnace body 111. The heat exchange platform 16 is positioned inside the heat insulation cage 14, and the heat exchange platform 16 is assembled on the bottom of the lower furnace body 112 through three graphite upright posts 17 and is positioned above the bottom heat insulation plate 143 of the heat insulation cage 14. The square graphite bottom plate 181 is placed on the heat exchange platform 16, the crucible 18 is placed on the graphite bottom plate 181, 4 graphite guard plates 182 are respectively placed on four sides of the graphite bottom plate 181 in an upright manner, the graphite guard plates 182 are attached to the outer side wall of the crucible 18, and the two adjacent graphite guard plates 182 are fixed by bolts. The upper end face of the graphite guard plate 182 is covered with a square cover plate 183, and the middle part of the cover plate 183 is provided with a through hole for conveying carrier gas. Therefore, the graphite bottom plate 181, the graphite guard plate 182, and the cover plate 183 constitute a square box and are located inside the heater 15. The drainage device 12 comprises a graphite pipe 123, a matching nut 121 and a drainage pipe 122 which are sequentially connected in the axial direction. The upper end of the drainage tube 122 is provided with an external thread matching with the internal thread of the coupling nut 121. The upper end of the draft tube 122 passes through a through hole in the middle of the top insulation plate 142 of the insulation cage 14 and is fastened to a coupling nut 121 disposed above the top insulation plate 142. The graphite tube 123 fits between the mating nut 121 and the viewing window 114 of the top end cap 113. The infrared detector 90 is fixed to the top end cap 113 with the lower probe facing the observation window 114.

The heating device 60 is an air heater, and is disposed outside the ingot furnace body 10 as shown in fig. 1. The air heater is composed of a shell, a heat insulation layer, a heating element and a circuitous pipeline for circulating carrier gas from outside to inside in sequence. The pipeline is a ribbed pipe with fins arranged outside and can also be a light pipe; the cross section of the pipeline is elliptical or rectangular, so that the heat exchange area is increased, and the heating effect is enhanced, namely the air heater is a ribbed tube type air heater. The shell is of a steel structure, the heat insulation layer is made of carbon fiber felt, and the heating element is made of graphite or tungsten wires; the ribbed tube is made of molybdenum, tungsten or titanium, so that the carrier gas can be heated to 1500 ℃ and is not polluted. One end of the pipeline is set as the output end of the air heater, and the other end is the input end of the air heater. The output end of the air heater is communicated with the upper end part of the drainage device 12 of the ingot furnace through a matching and connecting pipeline 61, and as shown in figure 1, the input end of the air heater is communicated with a gas conveying pipe 50 of carrier gas. The material of the matching and connecting pipeline 61 is molybdenum, and a heat insulation layer is coated outside the matching and connecting pipeline to reduce heat loss of carrier gas.

The heating device 60 may also be a heating tube, as shown in fig. 2, 3, and 4, which is disposed within the thermal cage between the top heater of the heater and the top insulation panel of the thermal cage to passively heat the carrier gas within the tube by absorbing thermal radiant energy. The heating pipes are distributed in a winding way, preferably along a planar spiral line, as shown in fig. 4. Wherein, the one end that the heating pipe is located the heliciform center is the output of heating pipe, and the one end that is located the heliciform avris is the input of heating pipe, also can adopt the circuitous distribution of U type, and the circuitous distribution of U type can destroy the symmetry in former temperature field, influences crystal normal growth, and is not often adopted. The heating pipes are distributed along a plane spiral line, so that the symmetry of a temperature field is maintained, the influence of the heating pipes on the original temperature field is reduced, and the normal growth of crystals is ensured. In order to increase the heating effect, the section of the heating pipe is elliptical or rectangular; further, fins are arranged outside the heating pipe to increase the heating area of the heating pipe and enhance the heating efficiency of the heating pipe to the carrier gas. The sidewall of the drainage tube 122 of the drainage device 12 is provided with a through hole through which the adapting pipe 61 can pass, as shown in fig. 3, the adapting pipe 61 is an L-shaped pipe, which passes through the through hole on the sidewall of the drainage tube 122 and extends into the drainage device 12, and the outlet is arranged downward. The heating pipe and the adapting pipe 61 are made of molybdenum, or tungsten or titanium. The output end of the heating pipe is communicated with the drainage device 12 through the adapting pipe 61, and the input end of the heating pipe is communicated with the gas conveying pipe 50 of the carrier gas.

The polycrystal ingot furnace of the embodiment is provided with a carrier gas heating device, cold carrier gas is heated by the heating device to form hot carrier gas with higher temperature, and the hot carrier gas is blown to eject silicon material in the crucible through a flow guiding device. The disturbance of the hot carrier gas to the temperature field in the liquid silicon is small, the component supercooling in the liquid silicon is not easy to occur, the supersaturation nucleation of impurities in the liquid silicon and the growth of impurity nuclei are inhibited, the generation of impurities in the crystal is reduced, and the quality of the crystal is improved. When the temperature of the carrier gas is lower than that of the liquid silicon, the heat taken away by the carrier gas from the liquid silicon in the blown area is less, the local temperature drop amplitude of the liquid silicon in the blown area of the carrier gas is greatly reduced, the supercooling degree is reduced, the nucleation probability of impurities caused by the carrier gas in the liquid silicon is reduced, and the formation of the impurities promoted by the carrier gas is reduced or even eliminated; when the temperature of the carrier gas is higher than that of the liquid silicon in the blowing and jetting area, the carrier gas supplies heat to the liquid silicon in the blowing and jetting area, so that the temperature of the liquid silicon in the area is increased, the radial temperature difference in the liquid silicon is reduced, impurity nucleation in the liquid silicon in the area is inhibited, the formation of impurities promoted by the carrier gas is eliminated, and the quality of crystals is improved.

Embodiment mode 2

Embodiment 2 differs from embodiment 1 only in that: as shown in fig. 5 and 6, the flow guiding device 20 is disposed in the polycrystalline ingot furnace, and the flow guiding device 20 is configured to divide the carrier gas into a plurality of outgoing carrier gas flows, the outgoing carrier gas flows are respectively obliquely blown to different areas of the surface of the liquid silicon to form carrier gas stresses distributed around the center of the liquid silicon, the carrier gas stresses drive the liquid silicon to flow, and a rotating flow field which flows circumferentially is formed in the liquid silicon. An air inlet hole 213 for the carrier gas to flow into is arranged outside the flow guide device 20. The heating device 60 adopts the air heater, the output end of the air heater is communicated with the air inlet hole 213 of the flow guiding device 20 through the adapting pipe 61 (not shown in the figure), and the input end is communicated with the air conveying pipe 50 of the carrier gas; the outside of the adapting pipe 61 is covered with a heat insulation layer to reduce the heat loss of the carrier gas. The heating device 60 can also adopt the heating pipe, the output end of the heating pipe is communicated with the air inlet hole 213 of the flow guiding device 20 through the adapting pipe 61, and the input end is communicated with the gas conveying pipe 50 of the carrier gas; the exterior of the portion of the mating duct 61 above the top insulation panel 142 is covered with an insulation layer.

The guide device 20 includes a fitting cylinder 21 and a guide cylinder 22, as shown in fig. 6 and 7, the lower end of the fitting cylinder 21 is provided with an internal thread 217, and the upper end of the guide cylinder 22 is provided with an external thread 224; the internal thread 217 of the adapter cylinder 21 is matched with the external thread 224 of the guide cylinder 22. The middle part of the guide shell 22 is provided with a flange 223 extending circumferentially along the outer surface thereof, as shown in fig. 7 and 12, the flange 223 surrounds the outer surface of the guide shell 22 for a circle, and an annular convex structure is formed on the surface of the guide shell 22 to play a role in limiting and fixing. In the assembly, the upper end of the guide shell 22 passes through the through hole in the middle of the top insulation plate 142 of the insulation cage 14 and is axially assembled with the adapter 21 arranged above the top insulation plate 142, and the adapter 21 and the guide shell 22 are tightly connected through the internal and external threads 217 and 224. The adapter cylinder 21 and the flange 223 cooperate to secure the guide cylinder 22 to the top insulation plate 142, as shown in fig. 6. The graphite tube 123 fits between the adapter cylinder 21 and the viewing window 114 of the top end cap 113. The material of the matching cylinder 21 and the guide cylinder 22 is graphite, preferably isostatic pressure graphite, and can also be metal molybdenum or titanium with higher cost.

As shown in fig. 8 and 9, the adapter cylinder 21 includes an adapter cylinder portion 211 and an air inlet table portion 212, the adapter cylinder portion 211 is a cylinder whose middle portion is provided with a through hole having a center line with the center line, i.e., a cylinder, the top of the adapter cylinder portion 211 is provided with a counter bore having an inner diameter larger than the through hole, the counter bore and the through hole have a center line with the center line, and the counter bore and the through hole cooperate to form an annular step 216 at the top of the adapter cylinder portion 211. The annular step 216 is used to assemble a prior art graphite tube 123 for transporting a carrier gas, as shown in fig. 6. A first diversion cavity 215 with an open lower end is arranged in the cylinder wall of the adapter cylinder part 211, the first diversion cavity 215 is an annular cavity surrounding the center line of the adapter cylinder part 211 for one circle, the first diversion cavity 215 and the adapter cylinder part 211 are concentric, and as shown in fig. 8 and 9, the first diversion cavity 215 is positioned below the annular step 216. The female screw 217 is provided at the lower end of the adapter cylinder portion 211 and is located below the first branch chamber 215. The internal thread 217 extends in the direction of the center line of the adapter cylinder portion 211 and is concentric with the adapter cylinder portion 211, as shown in fig. 8. The air inlet table portion 212 is provided outside the adapter tube portion 211, and as shown in fig. 9 and 10, the air inlet table portion 212 and the adapter tube portion 211 are integrally formed, thereby avoiding a problem that the graphite material member is not easily fixed and connected. An air inlet hole 213 for the carrier gas to flow into is arranged in the air inlet table part 212, the axial line of the air inlet hole 213 is perpendicular to the axis of the adapter cylinder part 211, as shown in fig. 9 and 10, the air inlet hole 213 is tangentially communicated with the first diversion chamber 215 and is arranged at the left side of the first diversion chamber 215, as shown in fig. 10, so that the carrier gas flow in the air inlet hole 213 flows into the first diversion chamber 215 in the clockwise direction (from top to bottom). The axial lead of the air inlet hole 213 can also be parallel to the axial lead of the adapting tube part 211 (not shown in the figure), the opening of the air inlet hole 213 can be arranged upwards or downwards according to the assembly requirement, and the air inlet hole 213 and the first diversion cavity 215 need to be communicated through a communicating air passage; the communicating air passage is arranged in a clockwise direction (when viewed from top to bottom, not shown in the figure), one end of the communicating air passage is tangentially communicated with the air inlet hole 213, the other end of the communicating air passage is tangentially communicated with the side wall of the first diversion chamber 215, the carrier gas flow in the communicating air passage flows into the first diversion chamber 215 in the clockwise direction, and the carrier gas in the first diversion chamber 215 flows in the clockwise direction.

The guide shell 22 is a cylinder with a through hole in the middle, which is concentric with the guide shell. The guide shell 22 is provided with the above-mentioned external thread 224 at the upper end, and as shown in fig. 7 and 12, the external thread 224 is matched with the above-mentioned internal thread 217. A second diversion cavity 221 with an open upper end surface is arranged in the wall of the upper end part of the guide shell 22, and the second diversion cavity 221 is an annular cavity surrounding the center line of the guide shell 22 for one circle, as shown in fig. 7 and 12. The external thread 224 is nested outside the outer side wall of the second branch chamber 221. The second branch chamber 221, the external thread 224 and the guide cylinder 22 are concentric. The second branch chamber 221 corresponds to the first branch chamber 215, i.e. the upper opening of the second branch chamber 221 is opposite to the lower opening of the first branch chamber 215. 4 guide air channels 222 are arranged in the wall of the guide shell 22, as shown in fig. 9 and 11, and the 4 guide air channels 222 are uniformly distributed around the center line of the guide shell 22, as shown in fig. 9. The number of the guide air passages 222 may be 2, 3 or more than 5. The diversion air channel 222 extends downward from the lower end surface of the second diversion cavity 221 along a cylindrical spiral line, that is, the center line of the diversion air channel 222 extends downward along the spiral line direction and coincides with the spiral line. The spiral line has non-uniform screw pitch, the screw pitch of the upper end part is longer than that of the lower end part, and the screw pitch of the outlet section of the flow guide air passage is shortest; the spiral line is located in the wall of the guide shell 22, rotates clockwise (when viewed from top to bottom), and has the same direction as the direction in which the carrier gas air flow in the air inlet hole 213 flows into the first diversion cavity 215, and the spiral line and the guide shell 22 share the center line. An inlet of the upper end of the guide air passage 222 is communicated with the lower end surface of the second diversion cavity 221, and an outlet of the lower end of the guide air passage 222 is located at the lower end of the guide cylinder 22, as shown in fig. 7 and 12.

The inlet hole 213 and the first branch chamber 215 are communicated tangentially, and the communication part is smoothly transited. Therefore, the resistance of the carrier gas flowing can be reduced, the carrier gas keeps higher kinetic energy and enters the first flow dividing cavity 215 and the second flow dividing cavity 221, the carrier gas rotates in the first flow dividing cavity and the second flow dividing cavity, and a longer flow path is provided, so that the carrier gas can uniformly flow into the flow guide air passage 222. The carrier gas flows along the same rotation direction through the gas inlet hole 213, the first secondary flow dividing cavities 215 and 221 and the diversion gas passage 222, the flowing resistance met by the flowing of the carrier gas is small, the kinetic energy loss is small, the carrier gas still has high energy when flowing to the outlet of the diversion gas passage 222, so that the carrier gas has high emergent speed, the emergent carrier gas generates large carrier gas stress on the liquid silicon, the flowing of the liquid silicon on the surface layer is promoted, and a strong rotation flow field is generated in the liquid silicon.

By changing the pitch and radius of the spiral line of the outlet section of the guide air passage 222, the position of the outlet of the guide air passage 222 at the lower end of the guide cylinder 22 and the outgoing direction of the carrier gas flow at the outlet of the guide air passage 222, that is, the tangential direction of the center line at the outlet of the guide air passage 222, are designed. When the pitch of the spiral line of the outlet section of the guide air passage 222 is gradually reduced and the radius is not changed, the outlet of the guide air passage 222 is located on the lower end surface of the guide cylinder 22, as shown in fig. 11, an included angle (an included angle between a tangent line and a plane normal line) between a tangent line (i.e., an exit direction of the carrier gas) of a center line at the outlet of the guide air passage 222 and the lower end surface (parallel to the surface of the liquid silicon) of the guide cylinder 22 is gradually increased, and the carrier gas stress of the exit carrier gas flow to the liquid silicon is gradually reduced; when the pitch of the outlet of the guide air passage 222 is close to the inner diameter of the hole of the guide air passage 222, an included angle between a tangent line of a center line of the outlet of the guide air passage 222 and the lower end surface (parallel to the surface of the liquid silicon) of the guide cylinder 22 is close to 90 degrees, namely, the tangent line of the center line of the outlet of the guide air passage 222 and the lower end surface of the guide cylinder 22 are close to parallel, at the moment, the emergent carrier gas flow is close to parallel to the surface of the liquid silicon, and the stress of the emergent carrier gas flow to the carrier gas of the liquid silicon is minimum. In addition, according to the local requirement, the pitch and radius of the spiral line of the outlet section of the guide air passage 222 can be changed, so that the pitch of the spiral line of the outlet section of the guide air passage 222 is gradually reduced, and the radius of the spiral line of the outlet section of the guide air passage 222 is gradually increased, and the outlet of the guide air passage 222 is located at the lower end of the outer side surface of the guide cylinder 22, or at the intersection of the outer side surface and the lower end surface of the guide cylinder 22, as shown in fig. 12 and 13, so as to conveniently design the outlet direction of the guide air passage 222, optimize the blowing and emitting area of the emergent carrier gas flow on the surface of the liquid silicon, and generate a stronger rotating flow field in the liquid silicon under the condition that the pressure of the carrier gas is determined.

In the present embodiment, the air inlet table portion 212 is provided outside the adapter tube portion 211, and the field of view of the deflector to the inside of the ingot furnace is not blocked. The observation window 114 on the top of the furnace has a view field leading to the interior of the ingot furnace through the flow guiding device 20, and an operator can see the state of the silicon material in the furnace through the observation window 114 and the flow guiding device 20, so that the furnace driver can conveniently operate; the infrared detector 90 fixed above the observation window 114 can detect the state of the silicon material in the furnace through the observation window and the flow guiding device, and the automatic crystal growth process is smoothly carried out; the crystal measuring rod can be inserted into the ingot furnace through the flow guide device, and the growth speed of the crystal is convenient to measure.

The guiding device 20 of the polycrystal ingot furnace of the embodiment is internally provided with 4 guiding air passages for changing the flow direction of the carrier gas, the guiding air passages are distributed around the central line of the guiding device, and the outlets of the guiding air passages are uniformly distributed around the central line of the guiding device along the same angular direction, as shown in fig. 13. The carrier gas is divided into 4 carrier gas flows by 4 guide gas passages of the guide device, the 4 carrier gas flows are respectively and dispersedly blown to 4 areas of the surface of the liquid silicon, the 4 areas are distributed around the center of the liquid silicon, the included angle between the emergent carrier gas flow and the surface of the liquid silicon is properly reduced, preferably 30-40 degrees, the emergent carrier gas flow is obliquely blown to the surface of the liquid silicon, the emergent carrier gas flow generates larger carrier gas stress driving laminar flow to the liquid silicon, the carrier gas stress is distributed around the center of the liquid silicon, the carrier gas stress drives the surface layer liquid silicon to flow, and a rotating flow field which flows in the circumferential direction is formed in the liquid silicon. The rotating flow field is beneficial to conveying the floating impurities on the surface of the liquid silicon to the edge of the liquid silicon, so that the influence of the floating impurities on the yield of crystals is reduced, and the yield of the crystals is improved; meanwhile, the method is also beneficial to conveying impurities in the liquid silicon to the surface and promoting the volatilization of the impurities; under the combined action of the natural convection flow field and the rotary flow field, the liquid silicon is beneficial to the transportation and the uniform distribution of impurities in the liquid silicon, the radial resistivity of the crystal is more uniform, and the quality of the crystal is further improved. The guiding device ensures that the carrier gas is dispersedly blown to different areas of the surface of the liquid silicon, the contact area between the carrier gas flow and the surface of the liquid silicon is effectively increased, the amount of the carrier gas in contact with the surface of the liquid silicon in unit area is reduced, the heat taken away by the carrier gas from the liquid silicon in the blown area is less, the temperature drop amplitude of the area is small, the supercooling degree of the liquid silicon component is reduced, and the impurity nucleation and the impurity nucleus growth in the liquid silicon in the blown area of the carrier gas can be effectively reduced.

Embodiment 3

Embodiment 3 differs from embodiment 1 only in that: the flow guide device 30 is arranged in the polycrystalline ingot furnace, and as shown in fig. 14 and 15, the flow guide device 30 and the lower end part of the draft tube 122 of the draft device 12 are axially fixed. The flow guiding device 30 is used for dividing the carrier gas into a plurality of outgoing carrier gas flows, the outgoing carrier gas flows are respectively obliquely blown to different areas of the surface of the liquid silicon to form carrier gas stress distributed circumferentially around the center of the liquid silicon, the carrier gas stress drives the liquid silicon to flow, and a rotary flow field which flows circumferentially is formed in the liquid silicon. An air inlet 33 for the carrier gas to flow into is arranged outside the flow guiding device 30. The heating device 60 adopts the heating pipe arranged in the heat insulation cage, the output end of the heating pipe is communicated with the air inlet 33 of the diversion device 30 through the adapting pipe 61, and the input end is communicated with the gas conveying pipe 50 of the carrier gas. The heating device 60 can also adopt the air heater, the output end of the air heater is communicated with the air inlet 33 of the flow guiding device 30 through the adapting pipe 61, and the input end is communicated with the gas conveying pipe 50 of the carrier gas; the part of the adapting pipe 61 outside the furnace body is externally coated with a heat insulation layer to reduce the heat loss of the carrier gas.

As shown in fig. 16 and 17, the deflector device 30 includes a deflector tube portion 31 and an air inlet table portion 32, and the deflector tube portion 31 and the air inlet table portion 32 are made of relatively inexpensive graphite, preferably isostatic graphite, or relatively expensive molybdenum or titanium. The guide cylinder part 31 is a cylinder with a through hole in the center line direction, the through hole and the guide cylinder part 31 share the center line, the upper end of the guide cylinder part 31 is provided with an internal thread 37 for fixed connection, the internal thread 37 extends along the center line direction of the guide cylinder part 31, and an external thread can be arranged according to requirements. A flow dividing cavity 35 extending along the circumferential direction is arranged in the cylinder wall of the upper end part of the flow guide cylinder part 31, the flow dividing cavity 35 is an annular closed cavity surrounding the center line of the flow guide cylinder part 31 for one circle, and the flow dividing cavity 35 is positioned below the internal thread 37 and shares the center line with the flow guide cylinder part 31. The air inlet table portion 32 is provided outside the guide cylinder portion 31, and as shown in fig. 17, the guide cylinder portion 31 and the air inlet table portion 32 are integrally formed, thereby avoiding a problem that graphite material members are not easily fixedly connected. An air inlet hole 33 for the carrier gas to flow in is arranged in the air inlet table part 32, the axial lead of the air inlet hole 33 is vertical to the axial lead of the flow guide cylinder part 31, the air inlet hole 33 is communicated with the side wall of the flow distribution cavity 35 in a tangent mode, as shown in fig. 17, and smoothing is carried out on the communicated position to reduce the resistance of the carrier gas to flow. The openings of the intake holes 33 are located on the left side as shown in fig. 17 and 18, so that the carrier gas flow in the intake holes 33 flows into the diversion chamber 35 in the clockwise direction (viewed from the top down), and the carrier gas flows in the diversion chamber 35 in the clockwise direction. The axial lead of the air inlet 33 can also be parallel to the axial lead of the guide cylinder part 31 (not shown in the figure), the opening of the air inlet 33 can be arranged upwards or downwards according to the assembly requirement, and the air inlet 33 is communicated with the diversion cavity 35 through a communicating air passage; the communicating air passage is arranged along the clockwise direction (seen from top to bottom, not shown in the figure), one end part of the communicating air passage is tangentially communicated with the air inlet hole 33, the other end part of the communicating air passage is tangentially communicated with the side surface of the diversion cavity 35, and the carrier gas flow in the communicating air passage flows into the diversion cavity 35 along the clockwise direction.

4 guide air passages 36 are arranged in the wall of the guide cylinder part 31, and the guide air passages 36 are uniformly distributed around the central line of the guide cylinder part 31, as shown in fig. 17, 19 and 21. The diversion air channel 36 extends downward from the lower end face of the diversion cavity 35 along a cylindrical spiral line, that is, the central line of the diversion air channel 36 extends downward along the spiral line direction and coincides with the spiral line. The helix has a non-uniform pitch, the pitch of the helix at the outlet of the diversion air passage 36 is the shortest, the helix is located in the cylinder wall of the diversion cylinder part 31, the helix rotates clockwise (when viewed from top to bottom), the helix is the same as the flowing direction of the carrier gas flow in the diversion cavity 35, and the helix and the diversion cylinder part 31 are coaxial. The inlet of the upper end of the diversion air passage 36 is communicated with the lower end surface of the diversion cavity 35, and the outlet of the lower end is positioned at the lower end of the diversion cylinder part 31.

The air inlet hole 33 and the flow dividing cavity 35 are communicated tangentially, and smooth transition is realized at the communication position. The layout can reduce the resistance of carrier gas circulation and reduce the energy loss of the carrier gas, so that the carrier gas keeps higher kinetic energy, enters the diversion cavity 35 and rotates in the diversion cavity 35, a longer flow path is provided, and the carrier gas can uniformly flow into the diversion air passage 36. The carrier gas flows in a rotating mode along the same direction through the air inlet hole 33, the flow dividing cavity 35 and the flow guide air passage 36, the flowing resistance met by the carrier gas flowing is small, the kinetic energy loss is small, the carrier gas still has high energy when flowing to the outlet of the flow guide air passage 36, the carrier gas has high emergent speed, the emergent carrier gas flow generates large carrier gas stress on liquid silicon, the flowing of the liquid silicon is facilitated, and a strong rotating flow field is generated in the liquid silicon.

By changing the pitch and radius of the spiral line at the outlet section of the guide air passage 36, the outlet of the guide air passage 36 is designed to be positioned at the lower end part of the guide cylinder part 31, and the outgoing direction of the carrier gas flow at the outlet of the guide air passage 36, namely the tangential direction of the central line of the guide air passage 36 at the outlet. When the pitch of the spiral line of the outlet section of the guide air passage 36 is gradually reduced and the radius is not changed, the outlet of the guide air passage 36 is positioned on the lower end surface of the guide cylinder part 31, as shown in fig. 19, the included angle (the included angle between the tangent line and the surface normal line) between the tangent line of the center line of the guide air passage 36 at the outlet (i.e. the exit direction of the carrier gas flow) and the lower end surface (parallel to the surface of the liquid silicon) of the guide cylinder part 31 is gradually increased, and the carrier gas stress of the exit carrier gas flow to the liquid silicon is reduced; when the pitch of the spiral line at the outlet of the guide air passage 36 is close to the aperture of the guide air passage 36, the included angle between the tangent of the center line of the guide air passage 36 at the outlet and the lower end surface (parallel to the surface of the liquid silicon) of the guide cylinder part 31 is close to 90 degrees, namely, the tangent of the center line of the guide air passage 36 at the outlet and the lower end surface of the guide cylinder part 31 are close to parallel, at the moment, the emergent carrier gas flow is close to parallel to the surface of the liquid silicon, and the emergent carrier gas flow has the minimum carrier gas stress to the liquid silicon. In addition, the pitch and radius of the spiral line of the outlet section of the guide air passage 36 can be changed according to needs, so that the pitch of the spiral line of the outlet section is gradually reduced, the radius is gradually increased, the outlet of the guide air passage 36 is positioned at the lower end of the outer side surface of the guide cylinder part 31, or at the intersection of the outer side surface and the lower end surface of the guide cylinder part 31, as shown in fig. 20 and 21, so as to conveniently design the outlet direction of the guide air passage 36, optimize the blowing and shooting area of the emergent carrier gas flow on the surface of the liquid silicon, such as the middle position between the center of the liquid silicon and the edge of the liquid silicon, and generate a stronger rotating flow field in the liquid silicon under the condition of certain carrier gas pressure.

In the present embodiment, the air inlet table portion 32 is provided outside the guide cylinder portion 31, and the field of view of the guide device 30 into the ingot furnace is not blocked. The observation window 114 has a view field leading to the interior of the ingot furnace through the flow guiding device 30, and an operator can see the state of the silicon material in the furnace through the observation window 114, so that the furnace operation is convenient; the infrared detector 90 fixed above the observation window 114 can detect the state of the silicon material in the furnace through the observation window and the flow guiding device, and the automatic crystal growth process is smoothly carried out; the crystal measuring rod can be inserted into the ingot furnace through the flow guide device, and the growth speed of the crystal is convenient to measure.

The guiding device 30 of the ingot furnace of this embodiment has 4 guiding air passages for changing the flow direction of the carrier gas, the guiding air passages are distributed around the center line of the guiding device, and the outlets of the guiding air passages are uniformly distributed along the same angular direction around the center line of the guiding device, as shown in fig. 19 and 21. The carrier gas is divided into 4 beams of carrier gas flows through 4 diversion gas passages of the diversion device, the 4 beams of carrier gas flows are respectively dispersedly blown to the surface of the liquid silicon, 4 blowing areas are formed on the surface of the liquid silicon, the 4 blowing areas are distributed around the center of the liquid silicon, the included angle between the emergent carrier gas flow and the surface of the liquid silicon is properly reduced, preferably 30-40 degrees, the emergent carrier gas flow is obliquely blown to the surface of the liquid silicon, the emergent carrier gas flow generates larger carrier gas stress of a driving laminar flow to the liquid silicon, the carrier gas stress is distributed around the center of the liquid silicon along the circumferential direction, the carrier gas stress drives the liquid silicon on the surface layer to flow, and then a rotating flow field which flows along the circumferential direction is formed in the liquid silicon. The rotating flow field is beneficial to conveying the floating impurities on the surface of the liquid silicon to the edge of the liquid silicon, so that the influence of the floating impurities on the yield of crystals is reduced, and the yield of the crystals is improved; meanwhile, the method is also beneficial to conveying impurities in the liquid silicon to the surface and promoting the volatilization of the impurities; under the combined action of the natural convection flow field and the rotary flow field, the liquid silicon is beneficial to the transportation and the uniform distribution of impurities in the liquid silicon, the radial resistivity distribution of the crystal is more uniform, and the quality of the crystal is further improved. The guiding device ensures that the carrier gas is dispersedly blown to different areas of the surface of the liquid silicon, the contact area between the carrier gas flow and the surface of the liquid silicon is effectively increased, the amount of the carrier gas in contact with the surface of the liquid silicon in unit area is reduced, the heat taken away by the carrier gas from the liquid silicon in the blown area is less, the temperature drop amplitude of the area is reduced, the supercooling degree of the liquid silicon component is reduced, and the impurity nucleation and the impurity nucleus growth in the liquid silicon in the blown area of the carrier gas can be effectively reduced.

Embodiment 4

Embodiment 4 differs from embodiment 1 only in that: the flow guide device 40 is arranged in the polycrystalline ingot furnace, and as shown in fig. 22 and 23, the flow guide device 40 and the lower end part of the draft tube 122 of the draft device 12 are axially fixed. The flow guiding device 40 is used for dividing the carrier gas into a plurality of outgoing carrier gas flows, the outgoing carrier gas flows are respectively obliquely blown to different areas of the surface of the liquid silicon to form carrier gas stress distributed circumferentially around the center of the liquid silicon, the carrier gas stress drives the liquid silicon to flow, and a rotary flow field which flows circumferentially is formed in the liquid silicon. An inlet duct portion 42 into which the carrier gas flows is provided outside the deflector 40. The heating device 60 adopts the above heating pipes built in the heat insulation cage 14, and the output ends of the heating pipes are communicated with the air inlet pipe part 42 of the diversion device 40 through the adapting pipe 61, and the input ends are communicated with the air conveying pipe 50 of the carrier gas. The heating device 60 for the carrier gas may also adopt the above air heater, the output end of the air heater is communicated with the air inlet pipe part 42 of the flow guiding device 40 through the adapting pipe 61, the input end is communicated with the gas conveying pipe 50 for the carrier gas, and the part of the adapting pipe 61 outside the furnace body is externally coated with a heat insulating layer to reduce the heat loss of the carrier gas.

As shown in fig. 24 and 25, the guide device 40 includes a fastening portion 45, a flow dividing chamber portion 41, an air inlet pipe portion 42, and a guide air pipe 43, and is made of molybdenum, or a high-temperature resistant material such as titanium, which is expensive, may be used. The fastening portion 45 is a hollow cylinder, is provided at the top of the flow dividing chamber portion 41, and is axially fixed thereto. The inner wall of the fastening portion 45 is provided with an internal thread 46 along the center line direction thereof, and an external thread may be provided according to the necessity. The shunt cavity part 41 is an annular cylindrical closed cavity body and mainly comprises an inner side wall, an outer side wall, an upper end wall and a lower end wall, wherein the inner side wall and the outer side wall are cylindrical, and the inner side wall is nested in the outer side wall and shares the same center line. The air inlet pipe portion 42 is disposed outside the flow dividing chamber portion 41, the axial line of the air inlet pipe portion 42 is perpendicular to the axial line of the flow guiding device 40, as shown in fig. 25, the air inlet pipe portion 42 is fixed to the outer side wall of the flow dividing chamber portion 41, the air inlet pipe portion 42 is in tangential communication with the side wall of the flow dividing chamber portion 41, and the inlet of the air inlet pipe portion 42 is disposed on the left side of the flow dividing chamber portion 41, so that the carrier airflow in the air inlet pipe portion 42 flows into the flow dividing chamber portion 41 in the clockwise direction (when viewed from top to bottom). The axis of the air inlet pipe part 42 can also be parallel to the axis of the flow guide device 40 (not shown in the figure), the opening of the air inlet pipe part 42 can be arranged upwards or downwards according to the assembly requirement, and the air inlet pipe part 42 is communicated with the flow dividing cavity part 41 through a communicating air pipe; the connecting air pipe is arranged in a clockwise direction (seen from top to bottom, not shown in the figure), one end part of the connecting air pipe is communicated with the air inlet pipe part 42 in a tangent mode, the other end part of the connecting air pipe is communicated with the side wall of the diversion cavity part 41 in a tangent mode, the carrier air flow in the connecting air pipe flows into the diversion cavity part 41 in a clockwise direction (seen from top to bottom), and then the carrier air in the diversion cavity part 41 flows in a clockwise direction. 4 diversion air pipes 43 for changing the flow direction of the carrier gas are arranged below the flow dividing cavity part 41, as shown in fig. 23 and 24, the 4 diversion air pipes 43 are uniformly distributed around the axial lead of the flow dividing cavity part 41, and the number of the diversion air pipes 43 can be 2, 3 or more than 5. The guide air pipe 43 is distributed right below the diversion chamber part 41 along a cylindrical spiral line, i.e. the central line of the guide air pipe 43 extends downwards along the spiral line direction and is overlapped with the spiral line, as shown in fig. 24. The spiral line is located right below the lower end wall of the diversion cavity part 41 and is a non-uniform pitch spiral line, the pitch of the outlet of the diversion air pipe 43 is the shortest, and the spiral line and the diversion cavity part 41 are coaxial. The spiral turns in the clockwise direction (when viewed from above, downward) in the same direction as the flow of the carrier gas in the branch chamber section 41. The inlet end of the upper end of the air guide pipe 43 is communicated and fixed with the lower end wall of the flow dividing cavity part 41, and the outlet of the lower end of the air guide pipe 43 is positioned below the lower end wall of the flow dividing cavity part 41 and is uniformly distributed along the same angular direction around the central line of the air guide device, as shown in fig. 24, and faces different areas of the surface of the liquid silicon.

The air inlet pipe part 42 is tangentially communicated with the flow dividing cavity part 41, and smooth transition is made at the communicated part. The layout can reduce the resistance of carrier gas circulation, reduce the energy loss of the carrier gas, ensure that the carrier gas keeps higher kinetic energy, enters the diversion cavity part 41, rotates in the diversion cavity part 41, has longer flow path, and is beneficial to the carrier gas to uniformly flow into the diversion air pipe 43. The carrier gas rotates along the same direction through the gas inlet pipe part 42, the flow dividing cavity part 41 and the diversion gas pipe 43, the flowing resistance met by the carrier gas flowing is small, the kinetic energy loss is small, the carrier gas still has high energy at the outlet of the diversion gas pipe 43, so that the carrier gas has high emergent speed, the emergent carrier gas generates large carrier gas stress on the liquid silicon, the liquid silicon flowing is promoted, and a strong rotating flow field is generated in the liquid silicon.

By changing the pitch and radius of the spiral line of the outlet section of the diversion air pipe 43, the position of the outlet of the diversion air pipe 43 below the lower end wall of the diversion cavity part 41 and the outgoing direction of the carrier gas flow at the outlet of the diversion air pipe 43 are designed, namely the tangential direction of the central line of the diversion air pipe 43 at the outlet are designed. When the pitch of the spiral line of the outlet section of the diversion air pipe 43 is gradually reduced and the radius is unchanged, the outlet of the diversion air pipe 43 is positioned right below the lower end wall of the diversion cavity part 41; the included angle (the included angle between the tangent line and the normal line of the lower end wall surface) between the tangent line of the central line of the diversion air pipe 43 at the outlet (namely the outgoing direction of the carrier gas flow) and the lower end wall surface (parallel to the liquid silicon surface) of the diversion cavity part 41 is gradually increased, and the carrier gas stress of the outgoing carrier gas flow to the liquid silicon is gradually reduced; when the pitch of the spiral line of the outlet section of the diversion gas pipe 43 is close to the outer diameter of the diversion gas pipe, the included angle between the tangent line of the center line of the diversion gas pipe 43 at the outlet and the lower end wall surface (parallel to the liquid silicon surface) of the diversion cavity part 41 is close to 90 degrees, namely the tangent line of the center line of the diversion gas pipe 43 at the outlet and the lower end wall surface of the diversion cavity part 41 are close to parallel, the emergent carrier gas flow and the liquid silicon surface are close to parallel, and the emergent carrier gas flow has the minimum carrier gas stress on the liquid silicon at the moment. In addition, according to the requirement, the pitch and radius of the spiral line of the outlet section of the diversion air pipe 43 can be changed, so that the pitch of the spiral line of the outlet section is gradually reduced, and the radius of the spiral line of the outlet section is gradually increased, and the outlet of the diversion air pipe 43 is positioned at the lower end of the extension surface of the outer side wall of the diversion cavity part 41, or positioned outside the extension surface of the outer side wall of the diversion cavity part 41; the outlet direction of the gas guide pipe 43 is conveniently designed, the blowing and jetting area of the emergent carrier gas flow on the surface of the liquid silicon is optimized, for example, the blowing and jetting area is positioned in the middle between the center of the liquid silicon and the edge of the liquid silicon, and a stronger rotating flow field is generated in the liquid silicon under the condition of certain carrier gas pressure.

In the present embodiment, the air inlet pipe portion 42 is provided outside the branch chamber portion 41, and the field of view of the deflector 40 into the ingot furnace is not blocked. The observation window 114 on the furnace top is provided with a view field leading to the interior of the ingot furnace through the flow guiding device 40, and an operator can see the state of the silicon material in the furnace through the observation window 114, so that the furnace operation is convenient; the infrared detector fixed above the observation window 114 can detect the state of the silicon material in the furnace through the observation window 114 and the flow guide device 40, and the automatic crystal growth process is smoothly carried out; the crystal measuring bar can be inserted into the ingot furnace through the flow guiding device, and the growth speed of the crystal is convenient to measure.

The guiding device 40 of the ingot furnace of this embodiment is provided with 4 guiding air pipes for changing the flow direction of the carrier gas, the guiding air pipes are distributed around the center line of the guiding device, and the outlets of the guiding air pipes are uniformly distributed along the same angular direction around the center line of the guiding device, as shown in fig. 24. The carrier gas is divided into 4 beams of carrier gas flow by 4 guide gas pipes of the guide device, the 4 beams of carrier gas flow dispersedly blow and shoot the surface of the liquid silicon, 4 blow and shoot areas are formed on the surface of the liquid silicon, and the 4 blow and shoot areas are distributed around the center of the liquid silicon. Properly reducing an included angle between the emergent carrier gas flow and the surface of the liquid silicon, preferably 30-40 degrees, so that the emergent carrier gas flow obliquely blows the surface of the liquid silicon, the emergent carrier gas flow generates larger carrier gas stress of a driving laminar flow to the liquid silicon in a blowing area, and the carrier gas stress drives the liquid silicon on the surface layer to flow; the carrier gas stress is distributed circumferentially around the center of the liquid silicon, forming a rotating flow field in the liquid silicon for circumferential flow. The rotating flow field is beneficial to conveying the floating impurities on the surface of the liquid silicon to the edge of the liquid silicon, so that the influence of the floating impurities on the yield of crystals is reduced, and the yield of the crystals is improved; meanwhile, the method is also beneficial to conveying impurities in the liquid silicon to the surface and promoting the volatilization of the impurities; under the combined action of the natural convection flow field and the rotary flow field, the liquid silicon is beneficial to the transportation and the uniform distribution of impurities in the liquid silicon, the local enrichment of the impurities is avoided, the radial resistivity distribution of the crystal is more uniform, and the quality of the crystal is further improved. The guiding device ensures that the carrier gas is dispersedly blown to different areas of the surface of the liquid silicon, the contact area between the carrier gas flow and the surface of the liquid silicon is effectively increased, the amount of the carrier gas in contact with the surface of the liquid silicon in unit area is reduced, the heat taken away by the carrier gas from the liquid silicon in the blown area is less, the temperature drop amplitude of the area is reduced, the supercooling degree of the liquid silicon component is reduced, and the impurity nucleation and the impurity nucleus growth in the liquid silicon in the blown area of the carrier gas can be effectively reduced.

For convenience of description, the following unification processing is performed on corresponding technical names in the flow guiding devices of the latter three embodiments. The intake holes 213, 33 and the intake pipe portion 42 will be collectively referred to as an intake port; the first flow dividing chamber, the flow dividing chamber 35 and the flow dividing chamber part 41 will be generally referred to as a flow dividing chamber; the diversion air passages 36, 222 and the diversion air pipes 43 will be collectively referred to as diversion passages.

The working principle of the polycrystalline ingot furnace is as follows: firstly, the quartz crucible 18 is placed on the graphite bottom plate 181, the quartz crucible 18 is filled with silicon materials, then 4 graphite guard plates 182 are respectively vertically placed on the side edges of the graphite bottom plate 181, the graphite guard plates 182 are attached to the side walls of the crucible 18, then two adjacent graphite guard plates 182 are sequentially fixed by bolts, and finally, the cover plate 183 is covered on the top end surface of the graphite guard plates 182. And opening the lower furnace body of the polycrystalline ingot casting, dragging the graphite bottom plate 181 by using a fork arm of a forklift, moving the graphite bottom plate into the furnace, placing the graphite bottom plate on the heat exchange platform 16, closing the upper furnace body and the lower furnace body, and starting an automatic crystal growth process to perform ingot casting. The gas pipe 50 conveys cold carrier gas to the heating device for heating to form hot carrier gas with higher temperature, the hot carrier gas flows into the diversion cavity of the diversion device through the adapting pipe and rotates in the diversion cavity, then the hot carrier gas flows into a plurality of diversion channels which are uniformly distributed from the lower end of the diversion cavity respectively and then is emergent from the outlet of the diversion channels, and emergent carrier gas flows are respectively and dispersedly blown to different areas on the surface of the liquid silicon. The multiple flow guide channels of the flow guide device are distributed around the center line of the flow guide device, outlets of the flow guide channels are uniformly distributed around the center line of the flow guide device along the same angular direction, emergent carrier gas flows of the flow guide channels respectively and dispersedly blow different areas of the surface of the liquid silicon, the blow-shooting areas are uniformly distributed around the center of the liquid silicon, the emergent carrier gas flows generate carrier gas stress for driving laminar flow on the liquid silicon in the blow-shooting areas, the carrier gas stress is distributed around the center of the liquid silicon, the carrier gas stress drives the surface layer liquid silicon to flow, and a rotary flow field which flows in the circumferential direction is formed in the liquid silicon. The angle between the outgoing carrier gas flow and the surface of the liquid silicon is suitably reduced, preferably 30-40 degrees, the outgoing carrier gas flow blows obliquely onto the surface of the liquid silicon, the outgoing carrier gas flow generates a larger carrier gas stress of the driving laminar flow to the liquid silicon, and a stronger rotating flow field is generated in the liquid silicon. The rotating flow field is beneficial to conveying the floating impurities on the surface of the liquid silicon to the edge of the liquid silicon, so that the influence of the floating impurities on the yield of crystals is reduced, and the yield of the crystals is improved; meanwhile, the method is beneficial to conveying impurities in the liquid silicon to the surface of the liquid silicon and accelerating the volatilization of the impurities in the liquid silicon; under the combined action of the natural thermal convection flow field and the rotary flow field, the liquid silicon is beneficial to the transportation and the uniform distribution of impurities in the liquid silicon, the local enrichment of the impurities is avoided, the radial resistivity distribution of the crystal is more uniform, the electrical property of the crystal is optimized, and the quality of the crystal is further improved.

Compared with the prior art, the invention has the following technical progress.

1) Local supercooling caused by carrier gas in the liquid silicon is reduced or even eliminated, and by arranging the heating device of the carrier gas, the cold carrier gas is heated by the heating device to form heat carrier gas, and then the heat carrier gas is blown to the liquid silicon. When the temperature of the hot carrier gas is lower than that of the liquid silicon, the heat taken away by the carrier gas from the liquid silicon in the blown area is greatly reduced, the temperature drop of the liquid silicon in the area is greatly reduced, the supercooling degree is reduced, the nucleation probability of impurities caused by the carrier gas in the liquid silicon is reduced, and the formation of the impurities promoted by the carrier gas in the liquid silicon is reduced or even eliminated; when the temperature of the hot carrier gas is higher than that of the liquid silicon, the carrier gas supplies heat to the liquid silicon in the blown area, so that the temperature of the liquid silicon in the area is increased, the radial temperature difference in the liquid silicon is reduced, the impurity nucleation in the liquid silicon in the area is inhibited, the formation of impurities promoted by the carrier gas is eliminated, and the quality of crystals is improved.

2) The observation window on the top of the furnace is provided with a view field leading to the interior of the ingot furnace, and the view field leading to the interior of the ingot furnace in the flow guide device is not blocked by arranging an air inlet platform part (an air inlet pipe part) of the flow guide device outside a matching barrel part/flow guide barrel part (a flow distribution chamber part) of the flow guide device; the condition in the ingot furnace can be observed through the observation window on the top of the furnace, so that the furnace operation is convenient; the crystal measuring bar can penetrate through the flow guide device to be inserted into the ingot furnace, and the growth speed of the crystal is convenient to measure; the infrared detector can detect the state of the silicon material in the ingot furnace through the observation window, and the automatic crystal growth process is smoothly carried out.

3) The local temperature drop caused by the carrier gas in the liquid silicon is further reduced, the carrier gas is divided into a plurality of carrier gas flows by the plurality of flow guide channels of the flow guide device, the plurality of carrier gas flows are scattered and obliquely blown to different areas of the surface of the liquid silicon, the contact area between the carrier gas and the surface of the liquid silicon is effectively increased, the heat carried by the carrier gas flow in a unit area is reduced, the local temperature drop amplitude caused by the carrier gas flow is reduced, and the local temperature drop caused by the carrier gas in the liquid silicon is reduced or even avoided.

4) The method has the advantages that the volatilization of impurities and the uniform distribution of the impurities are promoted, the quality of crystals is improved, the guide channels of the guide device are uniformly distributed around the center line of the guide device, carrier gas is divided into a plurality of carrier gas flows through the guide channels, the carrier gas flows are obliquely blown to different areas of the surface of the liquid silicon respectively, the blown areas of the carrier gas flows are distributed around the center of the surface of the liquid silicon, the carrier gas flows generate carrier gas stress for driving laminar flow to the liquid silicon, and the carrier gas stress drives the liquid silicon to flow to form a rotary flow field flowing around the center of the liquid silicon. The rotating flow field is beneficial to conveying the floating impurities on the surface of the liquid silicon to the edge of the liquid silicon, so that the influence of the floating impurities on the yield of crystals is reduced, and the yield of the crystals is improved; the method is also beneficial to conveying impurities in the liquid silicon to the surface of the liquid silicon and accelerating the volatilization of the impurities in the liquid silicon; under the combined action of the natural convection flow field and the rotary flow field, the liquid silicon is beneficial to the transportation and the uniform distribution of impurities in the liquid silicon, the local enrichment of the impurities is avoided, the radial resistivity distribution of the crystal is more uniform, and the quality of the crystal is further improved.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the foregoing description only for the purpose of illustrating the principles of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims, specification, and equivalents thereof.

Claims (10)

1. The utility model provides a polycrystal ingot furnace with carrier gas heating device, includes thermal-insulated cage and honeycomb duct, the thermal-insulated cage is the cavity that mainly comprises side heat insulating board, top heat insulating board and end heat insulating board, its characterized in that: the gas-carrier heating device comprises a flow guide cylinder part and an air inlet table part, wherein the flow guide cylinder part is fixedly connected with the air inlet table part, the flow guide cylinder part is a cylinder provided with a through hole along the central line direction of the flow guide cylinder part, and the air inlet table part is arranged outside the flow guide cylinder part; an annular shunt cavity which is concentric with the flow guide cylinder part is arranged in the cylinder wall at the upper end part of the flow guide cylinder part; an air inlet hole for carrier gas to flow into is arranged in the air inlet table part, and the air inlet hole is communicated with the flow dividing cavity through a communicating air passage; at least one guide air passage extending downwards from the lower end face of the diversion cavity along a non-uniform-pitch cylindrical spiral line is arranged in the cylinder wall of the guide cylinder part, and an outlet of the guide air passage is positioned at the lower end of the guide cylinder part; one end of the communicating air passage is communicated with the air inlet hole in a tangent mode, and the other end of the communicating air passage is communicated with the side face of the shunting cavity in a tangent mode, so that the carrier gas can rotationally flow in the same direction through the air inlet hole, the shunting cavity and the flow guide air passage; the guide pipe is assembled on the top heat insulation plate, and the lower end of the guide pipe penetrates through the through hole in the middle of the top heat insulation plate and extends out of the lower end face of the top heat insulation plate; the flow guide device is axially and fixedly connected with the lower end part of the flow guide pipe; the output end of the heating device is communicated with the air inlet of the flow guide device through a matching pipeline, and the input end of the heating device is communicated with the gas conveying pipe of the carrier gas.

2. The polycrystal ingot furnace with a carrier gas heating device according to claim 1, wherein: the heating device is an air heater, a heat insulation layer is arranged in a shell of the air heater, the output end of the air heater is communicated with the air inlet of the flow guide device through a matching pipeline, and the input end of the air heater is communicated with a gas conveying pipe for carrier gas; and the outside of the adapting pipe is coated with a heat insulation layer.

3. The polycrystal ingot furnace with a carrier gas heating device according to claim 2, wherein: the air heater is a ribbed tube type air heater.

4. The polycrystal ingot furnace with a carrier gas heating device according to claim 1, wherein: the heating device is a heating pipe, the heating pipe is arranged in a heat insulation cage of the ingot furnace, the output end of the heating pipe is communicated with the air inlet of the flow guiding device through a matching pipeline, and the input end of the heating pipe is communicated with a gas conveying pipe of carrier gas.

5. The polycrystal ingot furnace with an air-carrying heating device according to claim 4, wherein: the heating pipes are distributed in a circuitous manner and are arranged between the heater and the heat insulation cage of the ingot furnace.

6. The polycrystal ingot furnace with an air-carrying heating device according to claim 5, wherein: the heating pipe is a finned pipe and is arranged between the top heater of the heater and the top heat insulation plate of the heat insulation cage.

7. The polycrystal ingot furnace with an air-carrying heating device according to claim 4, wherein: the heating pipe is made of molybdenum, tungsten or titanium.

8. The polycrystal ingot furnace with a gas-carrying heating apparatus according to any one of claims 1 to 7, wherein:

the screw pitch of the spiral line of the outlet section of the flow guide air passage is gradually reduced, and the outlet of the flow guide air passage is positioned on the lower end face of the flow guide cylinder part.

9. The polycrystal ingot furnace with a gas-carrying heating apparatus according to any one of claims 1 to 7, wherein: the screw pitch of the spiral line of the outlet section of the diversion air passage is gradually reduced, the radius is gradually increased, and the outlet of the diversion air passage is positioned at the lower end of the outer side surface of the diversion cylinder part.

10. The polycrystal ingot furnace with an air-carrying heating device according to claim 9, wherein: the number of the diversion air passages is 3, 4 or 5, and the diversion air passages are uniformly distributed around the center line of the diversion device.

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