Disclosure of Invention
The invention aims to solve the technical problem of providing a method for efficiently preparing a large-diameter hollow silicon core and a corresponding preparation device aiming at the defects in the prior art.
The technical scheme adopted for solving the technical problem of the invention is as follows:
the invention provides a preparation method of a hollow silicon core, which comprises the following steps:
loading the blocky crystal silicon material into a crucible, and after the loading is finished, enabling the crucible and the silicon material in the crucible to be in a sealed cavity;
discharging air in a sealing pipe in the sealing cavity, the top of the sealing pipe and the bottom of the sealing cavity, and in a silicon core cache chamber in which the top of the sealing pipe is communicated with the bottom of the sealing pipe, and introducing protective gas into the sealing cavity to maintain a micro-positive pressure environment in the sealing cavity, the sealing pipe and the silicon core cache chamber;
heating the crucible to melt the massive crystalline silicon material in the crucible into liquid;
enabling the melted liquid crystal silicon material to flow downwards through an annular nozzle which is arranged at the bottom of the crucible and extends into the sealing tube under the action of self gravity and the pressure of protective gas, thereby forming a hollow silicon tube in the sealing tube;
the length of the hollow silicon tube in the sealing tube from the lower end to the upper part is monitored by using a length measuring device, the holding device in the sealing tube is started to fix the lower part of the hollow silicon tube when the length reaches a preset length value, then the cutting device is started to cut the lower part of the hollow silicon tube into a finished hollow silicon core meeting the preset length value, after the cutting is finished, the holding device drives the finished hollow silicon core to descend into the silicon core cache chamber and lay well, then the holding device is reset upwards, the hollow silicon tube in the sealing tube is fixed and cut when the length from the lower end to the upper part reaches the preset length value again, and is driven to descend into the silicon core cache chamber, and the steps are repeated in a circulating mode until the preparation process is finished.
Optionally, the sealing cavity, the top of the sealing cavity and the bottom of the sealing cavity are communicated with each other, and the protective gas is introduced into the sealing cavity after the air in the silicon core cache chamber communicated with the top of the sealing cavity and the bottom of the sealing tube is exhausted so as to maintain the micro-positive pressure environment in the sealing cavity, the sealing tube and the silicon core cache chamber:
and vacuumizing the sealing cavity, the sealing pipe and the silicon core cache chamber to pump the interiors of the sealing cavity, the sealing pipe and the silicon core cache chamber to negative pressure, introducing protective gas into the sealing cavity until the pressure in the sealing cavity, the sealing pipe and the silicon core cache chamber rises to positive pressure, repeating the vacuumizing of the sealing cavity, the sealing pipe and the silicon core cache chamber for 1-3 times, and finally continuously introducing the protective gas into the sealing cavity to maintain the micro-positive pressure environment in the sealing cavity, the sealing pipe and the silicon core cache chamber until the preparation process is finished.
Optionally, the heating treatment of the crucible is specifically: heating the crucible to 1400-1500 ℃.
Optionally, during the process of forming the hollow silicon tube in the sealed tube, the temperature of the hollow silicon tube formed in the sealed tube is controlled by a temperature adjusting device to ensure the viscosity of the hollow silicon tube.
Optionally, in the process of forming the hollow silicon tube in the sealed tube, continuously introducing inert gas into the hollow silicon tube from the top thereof to ensure the pressure of the inner hole of the drawn hollow silicon tube, and adjusting the flow rate of the inert gas according to the specification requirement of the hollow silicon tube to prepare the hollow silicon tube with a preset diameter and a preset wall thickness.
Optionally, the preparation method further comprises the following steps:
when the finished hollow silicon cores in the silicon core cache chamber reach a preset number, closing a channel between the sealing pipe and the silicon core cache chamber;
opening an outlet of the silicon core cache chamber, and closing the outlet after taking out the finished hollow silicon core in the silicon core cache chamber;
replacing the silicon core cache chamber for a preset time by using protective gas;
and after the preset time is over, opening a channel between the sealing pipe and the silicon core cache chamber.
Optionally, the crystalline silicon material is an electronic grade crystalline silicon material; the size of the massive crystalline silicon material is not less than 2 cm; the total amount of the blocky crystalline silicon material which is added into the crucible once does not exceed 3/4 of the volume of the crucible, and the protective gas is argon.
The invention also provides a preparation device of the hollow silicon core, which comprises a sealing cavity, a sealing pipe with the top communicated with the bottom of the sealing cavity, and a silicon core cache chamber with the top communicated with the bottom of the sealing pipe, wherein a crucible filled with blocky crystal silicon materials is placed in the sealing cavity, the bottom of the crucible is contacted with the bottom in the sealing cavity, and the bottom of the crucible is provided with an annular nozzle extending into the sealing pipe;
the preparation device also comprises a vacuumizing device, a protective gas source, a heating device, a length measuring device and a cutting device which are arranged at the lower part of the sealing pipe, and a holding device arranged in the sealing pipe;
the vacuumizing device is used for exhausting air in the sealing cavity, the sealing pipe and the silicon core cache chamber;
the protective gas source is communicated with the upper part of the sealing cavity and is used for introducing protective gas into the sealing cavity to maintain the micro-positive pressure environment in the sealing cavity, the sealing pipe and the silicon core cache chamber after air in the sealing cavity, the sealing pipe and the silicon core cache chamber is exhausted;
the heating device is arranged inside the sealed cavity and outside the crucible and is used for heating the crucible so as to melt the massive crystalline silicon material in the crucible into liquid, and the melted liquid crystalline silicon material flows downwards through the annular nozzle arranged at the bottom of the crucible under the action of self gravity and the pressure of protective gas, so that a hollow silicon tube is formed in the sealed tube;
the length measuring device is used for monitoring the length of the hollow silicon tube in the sealing tube from the lower end to the upper end, and starting the holding device when the length reaches a preset length value; the clamping device is used for fixing the lower part of the hollow silicon tube in the sealing tube under the starting of the length measuring device and starting the cutting device after the fixing is finished; the cutting device is used for cutting the lower part of the hollow silicon tube into a finished hollow silicon core meeting the preset length value under the starting of the clamping device, and the clamping device is started after the cutting is finished; the clamping device is started by the cutting device and is used for driving the finished hollow silicon core to descend into the silicon core cache chamber and be well placed, and then ascending for resetting;
the length measuring device, the clamping device and the cutting device are matched with each other so as to fix and cut the hollow silicon tube in the sealed tube when the length from the lower end to the upper end reaches the preset length value again, and the hollow silicon tube is driven to be sent into the silicon core cache chamber, and the steps are repeated in a circulating mode until the preparation process is finished.
Optionally, the vacuumizing device is specifically configured to vacuumize the sealing cavity, the sealing tube and the silicon core cache chamber to vacuumize the interiors of the sealing cavity, the sealing tube and the silicon core cache chamber to a negative pressure; the protective gas source is specifically used for introducing protective gas into the sealing cavity when the interiors of the sealing cavity, the sealing tube and the silicon core cache chamber are in a negative pressure state, and stopping until the pressures in the sealing cavity, the sealing tube and the silicon core cache chamber are increased to positive pressures; the vacuumizing device is also used for repeatedly vacuumizing the three parts for 1-3 times when the interiors of the three parts are in positive pressure; and the protective gas source is also used for continuously introducing protective gas into the sealing cavity when the vacuumizing is finished so as to maintain the micro-positive pressure environment in the sealing cavity, the sealing pipe and the silicon core cache chamber until the preparation process is finished.
Optionally, the heating device is specifically used for heating the temperature of the crucible to 1400-1500 ℃.
Optionally, the preparation apparatus further comprises a temperature adjusting device disposed at an upper portion of the sealing tube, for controlling a temperature of the hollow silicon tube formed inside the sealing tube to ensure a viscosity of the hollow silicon tube.
Optionally, the preparation apparatus further comprises an inert gas source for continuously introducing inert gas into the hollow silicon tube from the top thereof to ensure the pressure of the inner hole of the drawn hollow silicon tube, and adjusting the flow rate of the inert gas according to the specification requirement of the hollow silicon tube to prepare the hollow silicon tube with a preset diameter and a preset wall thickness.
Optionally, a through hole is formed in the bottom of the crucible, an outer tube extending into the sealing tube is connected to the through hole, the sealing tube is sleeved outside the outer tube and is spaced at a certain distance, an inner tube passing through the silicon material in the crucible upwards is arranged in the middle of the outer tube, and an annular nozzle extending into the sealing tube is formed in a gap between the outer tube and the lower end of the inner tube wall.
Optionally, the upper end of the inner tube is connected with the lower end of the gas supply tube, and the upper end of the gas supply tube passes through the upper side wall of the sealed cavity and then is communicated with the inert gas source, so that the inert gas sequentially passes through the gas supply tube and the inner tube and then enters the hollow silicon tube from the top thereof.
Optionally, an isolating switch in a normally open state is arranged at the joint of the bottom of the sealing pipe and the top of the silicon core cache chamber, an outlet for taking out a finished hollow silicon core is arranged on the silicon core cache chamber, the lower part or the bottom of the silicon core cache chamber is communicated with a protective gas source, and the top of the silicon core cache chamber is communicated with an exhaust pipeline provided with a one-way valve; the isolating switch is used for closing when an outlet of the silicon core cache chamber is opened so as to isolate the sealing pipe from the silicon core cache chamber; after the finished hollow silicon core in the silicon core cache chamber is taken out from the outlet of the silicon core cache chamber and the outlet is closed, the protective gas source is also used for introducing protective gas for preset time into the silicon core cache chamber so as to replace the silicon core cache chamber for the preset time by using the protective gas; and the isolating switch is also used for opening after the preset time is finished so as to open a channel between the sealing pipe and the silicon core cache chamber.
Optionally, the crystalline silicon material is an electronic grade crystalline silicon material; the size of the massive crystalline silicon material is not less than 2 cm; 3/4 of the volume of the crucible is not exceeded by the total amount of the blocky crystalline silicon material which is added into the crucible once; the crucible is a high-purity quartz crucible or a silicon nitride crucible, and the protective gas is argon; the annular nozzle is in the shape of a circular ring, a square ring, a triangular ring or a polygonal ring and is made of ceramic; the heating mode of the heating device is graphite resistance heating or induction heating; the cutting mode of the cutting device is mechanical cutting or laser cutting; the length measuring device adopts a laser length detector.
Has the advantages that:
1) according to the invention, the gravity of the liquid crystalline silicon material and the pressure of the protective gas are utilized, and the hollow silicon tube is drawn downwards in a self-flowing mode, so that the process is simple, the hollow silicon tube forming rate is high, and the efficiency is high;
2) according to the invention, the temperature adjusting device is arranged at the upper part of the sealing tube, so that the viscosity of the hollow silicon tube can be adjusted, and the forming effect is ensured;
3) the inert gas is continuously introduced into the hollow silicon tube in the sealing tube, so that the surface of the hollow silicon tube is prevented from being oxidized at high temperature, and meanwhile, the inert gas also has the function of adjusting the temperature, and the hollow silicon tube extending out of the sealing tube is prevented from being subjected to violent oxidation reaction with air due to too high temperature.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.
Aiming at the problems of low production efficiency, long production period, high energy consumption, high cost and the like in the process of producing the hollow silicon core by adopting the pulling method in the prior art, the invention provides a method for efficiently preparing the large-diameter hollow silicon core and a corresponding preparation device, which effectively improve the preparation efficiency of the hollow silicon core, have high product molding rate and high production efficiency and greatly reduce the production cost of the hollow silicon core. The following is a detailed description of specific examples.
Example 1:
as shown in fig. 1, the present embodiment provides a method for preparing a hollow silicon core, which includes the following steps S101 to S108.
S101, loading a blocky crystal silicon material into a crucible, and after loading is finished, enabling the crucible and the silicon material in the crucible to be in a sealed cavity.
The crystal silicon material is an electronic grade crystal silicon material; the size of the massive crystalline silicon material is not less than 2 cm; the total amount of bulk crystalline silicon material fed into the crucible at a single time should not exceed 3/4 of the crucible volume.
S102, after air in a sealing pipe in the sealing cavity, the sealing pipe with the top communicated with the bottom of the sealing cavity and a silicon core cache chamber with the top communicated with the bottom of the sealing pipe is exhausted, protective gas is introduced into the sealing cavity to maintain the micro-positive pressure environment in the sealing cavity, the sealing pipe and the silicon core cache chamber.
The shielding gas is preferably argon.
The method comprises the following specific steps: and vacuumizing the sealing cavity, the sealing pipe and the silicon core cache chamber to pump the interiors of the sealing cavity, the sealing pipe and the silicon core cache chamber to negative pressure, introducing protective gas into the sealing cavity until the pressure in the sealing cavity, the sealing pipe and the silicon core cache chamber rises to positive pressure, repeating the vacuumizing of the sealing cavity, the sealing pipe and the silicon core cache chamber for 1-3 times, and finally continuously introducing the protective gas into the sealing cavity to maintain the micro-positive pressure environment in the sealing cavity, the sealing pipe and the silicon core cache chamber until the preparation process is finished.
S103, heating the crucible to melt the massive crystalline silicon materials in the crucible into liquid.
In this step, the heating treatment of the crucible is specifically: heating the crucible to 1400-1500 ℃.
And S104, enabling the melted liquid crystal silicon material to downwards flow through an annular nozzle which is arranged at the bottom of the crucible and extends into the sealing tube under the action of self gravity and the pressure of protective gas, thereby forming the hollow silicon tube in the sealing tube.
In the step, in the process of forming the hollow silicon tube in the sealed tube, the temperature of the hollow silicon tube formed in the sealed tube can be controlled by the temperature adjusting device so as to ensure the viscosity of the hollow silicon tube.
In the step, in the process of forming the hollow silicon tube in the sealed tube, the inert gas can be continuously introduced into the hollow silicon tube from the top of the hollow silicon tube so as to ensure the pressure of the inner hole of the drawn hollow silicon tube, and the flow of the inert gas is adjusted according to the specification requirement of the hollow silicon tube so as to prepare the hollow silicon tube with the preset diameter and the preset wall thickness.
The inert gas is preferably argon.
And S105, monitoring the length of the hollow silicon tube in the sealing tube from the lower end to the upper end by using a length measuring device.
And S106, when the measured value of the length measuring device reaches a preset length value, starting the additional holding device in the sealing tube to fix the lower part of the hollow silicon tube, and then starting the cutting device.
And S107, cutting the lower part of the hollow silicon tube into a finished hollow silicon core meeting the preset length value by using a cutting device.
S108, after cutting, the holding device drives the finished hollow silicon core to descend into the silicon core cache chamber and place the finished hollow silicon core, and then the holding device is enabled to ascend and reset.
The steps S106-S108 are repeatedly executed until the preparation process is finished.
In other words, the steps S105 to S108 are specifically: the length of the hollow silicon tube in the sealing tube from the lower end to the upper part is monitored by using a length measuring device, the holding device in the sealing tube is started to fix the lower part of the hollow silicon tube when the length reaches a preset length value, then the cutting device is started to cut the lower part of the hollow silicon tube into a finished hollow silicon core meeting the preset length value, after the cutting is finished, the holding device drives the finished hollow silicon core to descend into the silicon core cache chamber and lay well, then the holding device is reset upwards, the hollow silicon tube in the sealing tube is fixed and cut when the length from the lower end to the upper part reaches the preset length value again, and is driven to descend into the silicon core cache chamber, and the steps are repeated in a circulating mode until the preparation process is finished.
In addition, as shown in fig. 1, the preparation method may further include the following steps S109 to S112.
S109, when the number of finished hollow silicon cores in the silicon core cache chamber reaches a preset number, closing a channel between the sealing pipe and the silicon core cache chamber.
S110, opening an outlet of the silicon core cache chamber, and closing the outlet after the finished hollow silicon core in the silicon core cache chamber is taken out. The finished hollow silicon core taken out from the silicon core cache chamber can remove the oxide film on the surface through an acid washing link so as to avoid influencing the normal use of the silicon core in the later period.
And S111, replacing the silicon core cache chamber for preset time by using protective gas. The preset time is 10-30 minutes.
And S112, after the preset time is over, opening a channel between the sealing pipe and the silicon core cache chamber.
After step S112, a production cycle is finished, and if the hollow silicon core is to be continuously produced, the process returns to step S101.
In summary, in the method for preparing a hollow silicon core according to this embodiment, an electronic-grade bulk crystalline silicon material is used as a raw material, the crystalline silicon material is melted into liquid silicon by heating a crucible, the liquid silicon flows through an annular nozzle under the action of gravity and gas pressure to form a hollow silicon tube in a sealing tube, the length of the formed hollow silicon tube is detected by a length measuring device, when the length of the hollow silicon tube meets the requirement of a finished hollow silicon core, a cutting device is started to cut the hollow silicon tube into hollow silicon cores with a certain length, and the hollow silicon cores are sent into a silicon core cache chamber, so as to complete the preparation of a finished hollow silicon core, the hollow silicon cores are fixed and cut when the length of the hollow silicon tubes reaches a preset length value again, and the hollow silicon cores are sent into the silicon core cache chamber in a downward driving manner, and the above steps are repeated.
Example 2:
as shown in FIG. 2, the present embodiment provides a preparation apparatus for hollow silicon core, which includes a sealed cavity 4, a sealed tube 12 having a top portion communicated with a bottom portion of the sealed cavity 4, and a silicon core buffer chamber 18 having a top portion communicated with a bottom portion of the sealed tube 12. Wherein, the sealed cavity 4 is composed of a cylinder body with an opening at the top end and a top cover 5 covering the opening of the cylinder body.
The crucible 1 filled with the blocky crystalline silicon material 3 is placed in the sealed cavity 4, the size of the blocky crystalline silicon material 3 is not less than 2cm, and the total amount of the blocky crystalline silicon material 3 which is added into the crucible once cannot exceed 3/4 of the volume of the crucible; the crystal silicon material is preferably electronic grade crystal silicon material, and the crucible is a high-purity quartz crucible or a silicon nitride crucible. The bottom of the crucible 1 is contacted with the bottom in the sealed cavity 4, and the bottom of the crucible 1 is provided with an annular nozzle 9 extending into a sealed tube 12.
Specifically, the bottom of the crucible 1 is provided with a through hole, an outer tube 7 extending into a sealing tube 12 is connected to the through hole (i.e. the outer tube 7 is connected to the bottom of the crucible 1), the sealing tube 12 is sleeved outside the outer tube 7 and spaced apart by a certain distance, preferably, the outer tube 7 is located at the center of the sealing tube 12, an inner tube 8 extending upwards through the silicon material in the crucible 1 is arranged in the middle of the outer tube 7 (i.e. the inner tube 8 is inserted into the middle of the outer tube 7), and an annular nozzle 9 extending into the sealing tube 12 is formed in the gap between the outer tube 7 and the lower end of the inner tube 8, so that a drawing nozzle with a certain shaped gap.
In this embodiment, the annular nozzle 9 may be a circular ring, a square ring, a triangular ring or a polygonal ring, and may be made of a ceramic material such as silicon nitride or corundum. The outer tube 7 and the inner tube 8 may be made of a ceramic material such as silicon nitride or corundum.
The preparation device further comprises a vacuum pumping device (not shown in the figure), a protective gas source (not shown in the figure), an inert gas source (not shown in the figure), a heating device 2, a length measuring device 16 and a cutting device 14 which are arranged at the lower part of the sealing tube 12, a temperature adjusting device 15 which is arranged at the upper part of the sealing tube 12, and a clamping device 24 which is arranged in the sealing tube 12.
In this example, argon was used for both the protective gas and the inert gas. The cutting device 14 may be a mechanical cutting device or a laser cutting device, preferably a laser cutting device, which irradiates the surface of the workpiece with a high-energy laser beam to locally melt and gasify the irradiated area, thereby achieving the purpose of cutting, and since the laser cutting is a non-contact type, there is no mechanical punching force on the silicon tube itself, and the silicon tube is not broken. The length measuring device 16 may employ a laser length detector.
Wherein, the vacuum extractor is used for exhausting the air in the sealing cavity 4, the sealing tube 12 and the silicon core buffer chamber 18. The protective gas source (not shown in the figure) is communicated with the protective gas inlet on the upper side wall of the cylinder body of the sealed cavity 4 through a sealed cavity protective gas inlet pipeline 6 provided with a valve, and is used for introducing protective gas into the sealed cavity 4 to maintain the micro-positive pressure environment in the sealed cavity 4, the sealed tube 12 and the silicon core cache chamber 18 after air in the sealed cavity 4, the sealed tube 12 and the silicon core cache chamber 18 is exhausted.
Specifically, the vacuumizing device is used for vacuumizing the sealing cavity 4, the sealing tube 12 and the silicon core cache chamber 18 so as to vacuumize the interiors of the three to negative pressure; the protective gas source is used for introducing protective gas into the sealing cavity 4 when the interiors of the sealing cavity 4, the sealing tube 12 and the silicon core cache chamber 18 are in negative pressure, and stopping until the pressures in the sealing cavity 4, the sealing tube 12 and the silicon core cache chamber 18 are increased to positive pressure; the vacuumizing device is also used for repeatedly vacuumizing the three parts for 1-3 times (preferably 3 times) when the internal pressure of the three parts is positive; the protective gas source is also used for continuously introducing protective gas into the sealed cavity 4 when the vacuumizing is finished so as to maintain the micro-positive pressure environment in the sealed cavity 4, the sealing pipe 12 and the silicon core cache chamber 18 until the preparation process is finished.
The heating device 2 is arranged inside the sealed cavity 4 and outside the crucible 1 and used for heating the crucible 1 to 1400-1500 ℃, so that the blocky crystalline silicon material 3 in the crucible is melted into liquid. The molten liquid crystalline silicon material flows downward through an annular nozzle 9 provided at the bottom of the crucible 1 under the action of its own weight and the pressure of the protective gas, thereby forming a hollow silicon tube 13 within the sealed tube 12.
In this embodiment, the heating means 12 may be graphite (C/C) resistance heating or induction heating.
The temperature adjusting device 15 is used to control the temperature of the hollow silicon tube 13 formed inside the sealing tube 12 during the formation of the hollow silicon tube 13 to ensure the viscosity of the hollow silicon tube 13. In the present embodiment, the temperature control device 15 is heated by electric heating or radiation heating, preferably radiation heating.
In the process of forming the hollow silicon tube 13, the inert gas source is used for continuously introducing inert gas into the hollow silicon tube 13 from the top thereof so as to ensure the pressure of the inner hole of the drawn hollow silicon tube 13, and the flow rate of the inert gas is adjusted according to the specification requirement of the hollow silicon tube 13 so as to prepare the hollow silicon tube 13 with a preset diameter and a preset wall thickness.
Specifically, the upper end of the inner tube 8 is connected with the lower end of the air supply tube 10 through a flange, and the upper end of the air supply tube 10 penetrates through the upper side wall of the cylinder body of the sealed cavity 4 and then is communicated with an inert gas source through an inert gas inlet pipeline 11 provided with a valve, so that inert gas sequentially passes through the air supply tube 10 and the inner tube 8 and then enters the hollow silicon tube 13 from the top of the hollow silicon tube, the pressure of the inner hole of the hollow silicon tube is guaranteed to be pulled out, the diameter and the wall thickness of the hollow silicon tube are convenient to adjust and pull out, and the inner tube 8 can be arranged at the center of the outer tube 7 under the fixing action.
The length measuring device 16 is used for monitoring the length of the hollow silicon tube 13 in the sealed tube 12 from the lower end to the upper part, and starting the holding device 24 when the length reaches a preset length value, for example, after the lower end of the hollow silicon tube passes through the upper detection port of the length measuring device, the length measuring device starts to measure the length of the hollow silicon tube; the clamping device 24 is used for fixing the lower part of the hollow silicon tube 13 in the sealing tube 12 under the starting of the length measuring device 16, and the cutting device 14 is started after the fixing is finished; the cutting device 14 is used for cutting the lower part of the hollow silicon tube 13 into a finished hollow silicon core 19 with a preset length value under the starting of the clamping device 24, and the clamping device 24 is started after the cutting is finished; the holding device 24 is used for driving the finished hollow silicon core 19 to descend into the silicon core cache chamber 18 and be placed well under the starting of the cutting device 14, and then ascending for resetting.
As can be seen, the silicon core cache chamber 18 is used for storing finished hollow silicon cores 19. The clamping device 24 has a clamping and loosening function, and also has an up-and-down moving function, and can move between the sealing tube 12 and the silicon core cache chamber 18 to realize the fixation of the hollow silicon tube 13 in the cutting process, and convey the finished hollow silicon core 19 into the silicon core cache chamber 18 after the cutting is finished.
The length measuring device 16, the holding device 24 and the cutting device 14 are matched with each other to fix and cut the hollow silicon tube 13 in the sealed tube 12 when the length from the lower end to the upper end reaches the preset length value again, and drive the hollow silicon tube to descend to the silicon core cache chamber 18, and the steps are repeated in a circulating mode until the preparation process is finished.
In addition, an isolating switch 17 in a normally open state is arranged at the joint of the bottom of the sealing tube 12 and the top of the silicon core cache chamber 18; an outlet 20 for taking out a finished hollow silicon core 19 is arranged at a proper position on the silicon core cache chamber 18, and the lower part or the bottom of the silicon core cache chamber 18 is communicated with a protective gas source through a protective gas inlet pipeline 23 of the silicon core cache chamber, which is provided with a valve; the top of the silicon core cache chamber 18 is communicated with a silicon core cache chamber exhaust pipeline 21 provided with a one-way valve, and due to the one-way valve, air can only flow out of the silicon core cache chamber 18, so that the air is prevented from entering the silicon core cache chamber 18 through the exhaust pipeline 21; the silicon core buffer chamber 18 is also provided with a pressure detection device 22. The isolating switch 17 is used for closing when an outlet 20 of the silicon core cache chamber is opened so as to isolate the sealing tube 12 from the silicon core cache chamber 18; in the process of taking out the finished hollow silicon core 19 from the outlet 20 of the silicon core cache chamber and closing the outlet 20, air can enter the silicon core cache chamber 18 through the outlet 20, so that after the outlet 18 of the silicon core cache chamber is closed, the protective gas source is also used for introducing protective gas for a preset time into the silicon core cache chamber 18 so as to replace the silicon core cache chamber 18 with the protective gas for the preset time, wherein the preset time is 10-30 minutes; the isolating switch 17 is further configured to open after the preset time is over, so as to open a channel between the sealing tube 12 and the silicon core cache chamber 18, and then continue to prepare the hollow silicon tube.
Therefore, the preparation process of the hollow silicon core preparation device can be summarized into five major steps of feeding, material melting, silicon core drawing, product output and acid pickling, which are described in detail below.
A charging
The method comprises the steps of loading high-purity blocky crystal silicon materials into a crucible, wherein the size of the blocky materials is not less than 2cm, the loading amount of single crystal silicon materials cannot exceed 3/4 parts of the volume of the crucible, installing a top cover of a sealed cavity after loading is finished, enabling the crucible and the silicon materials in the crucible to be located in the sealed cavity, checking the sealing performance to be good, then opening a valve on a vacuumizing pipeline, vacuumizing the system to negative pressure, opening a valve on a protective gas inlet pipeline of the sealed cavity, introducing protective gas into the system, closing the valve on the protective gas inlet pipeline when the pressure in the system rises to positive pressure, repeating vacuumizing operation for 3 times, closing the valve on the vacuumizing pipeline, continuously introducing the protective gas into the sealed cavity through the protective gas inlet pipeline to maintain the positive pressure environment in the system, and preventing air from flowing into the sealed tube.
B chemical material
And starting a heating device on the outer side of the crucible, and heating the crucible to 1400-1500 ℃ so as to melt the crystalline silicon material in the crucible into a liquid state.
C drawing silicon core
The melted liquid silicon material enters a gap between the inner pipe and the outer pipe under the action of gravity and the pressure of protective gas, the melted liquid silicon material downwards passes through the annular nozzle to form a hollow silicon pipe, the temperature of the hollow silicon pipe is controlled by a temperature adjusting device on the upper part of the sealing pipe to ensure the viscosity of the hollow silicon pipe, a valve on an inert gas inlet pipeline is opened, inert gas is introduced into the hollow silicon pipe through the gas supply pipe, and meanwhile, the flow of the inert gas flowing through the gas supply pipe is adjusted according to the specification requirement of the hollow silicon pipe to prepare the hollow silicon pipe with different sizes and thicknesses. In the process of drawing the hollow silicon tube, protective gas is continuously introduced into the sealing cavity, so that the micro-positive pressure environment in the sealing cavity, the sealing tube and the silicon core cache chamber can be ensured, and air back-flowing is avoided. Of course, the hollow silicon core can be continuously produced by continuously adding the crystalline silicon material into the crucible.
D production of the product
The hollow silicon tube formed by the annular nozzle enters the sealing tube, when the lower end of the hollow silicon tube passes through the upper detection port of the length measuring device, the length measuring device starts to measure the length of the hollow silicon tube, when the length of the hollow silicon tube reaches a preset length value, namely the product requirement is met, the holding device in the sealing tube starts to fix the lower part of the hollow silicon tube, the cutting device starts immediately to cut the hollow silicon tube into finished hollow silicon cores with certain lengths, after the cutting, the holding device drives the finished hollow silicon cores to descend to the silicon core cache chamber, the finished hollow silicon cores are placed into the silicon core cache chamber, then the holding device ascends into the sealing tube to reset, and the next silicon tube fixing is repeated.
When the finished hollow silicon cores in the silicon core cache chamber reach a certain number, an isolating switch between the sealing pipe and the silicon core cache chamber is closed, an outlet of the silicon core cache chamber is opened, the finished hollow silicon cores are taken out, then the outlet of the silicon core cache chamber is closed, a valve on a protective gas inlet pipeline of the silicon core cache chamber is opened, the cache chamber is replaced for 10min, then the valve on the protective gas inlet pipeline of the silicon core cache chamber is closed, and then the isolating switch between the silicon core cache chamber and the sealing pipe is opened.
E acid cleaning
When the temperature of the finished hollow silicon core taken out from the silicon core cache chamber is too high, the finished hollow silicon core is exposed in the air and is easy to form an oxidation film on the surface of the silicon core, so that the normal use of the silicon core at the later stage is influenced, and therefore, the finished hollow silicon core needs to be pickled to remove the oxidation film on the surface of the finished hollow silicon core. Wherein the acid washing solution can be 10-20% hydrofluoric acid solution or hydrochloric acid solution.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.