JP2010228938A - Silicon purification apparatus and silicon purification method - Google Patents

Abstract

To provide a silicon purification apparatus and a silicon purification method capable of refining silicon at a low cost by greatly improving the purification efficiency of silicon.
A plurality of treatment chambers including a decompression vessel capable of reducing an internal pressure, a heat-resistant vessel, and a heating device for heating the heat-resistant vessel are provided, and the plurality of treatment chambers are molten silicon under reduced pressure. A silicon refining apparatus that is selectively switchable to a dephosphorization processing apparatus that removes phosphorus from the metal or a demetallation processing apparatus that removes metal from molten silicon by segregation, and a silicon purification method using the apparatus.
[Selection] Figure 1

Description

  The present invention relates to a silicon purification apparatus and a silicon purification method.

  Due to environmental problems, the use of natural energy as an alternative to oil has attracted attention. Among them, a solar cell using the photoelectric conversion principle of a silicon semiconductor is particularly attracting attention because it can easily convert solar energy into electric energy.

  However, since solar cells are still expensive, it is important to reduce the manufacturing cost of solar cells, especially the manufacturing cost of the silicon semiconductor that will be the main body of the solar cells, in order to further spread the solar cells. is there.

  For example, Patent Document 1 discloses a silicon purification method that provides silicon for solar cells at low cost by purifying metal silicon to a purity of about 7N. Hereinafter, a conventional silicon purification method described in Patent Document 1 will be described with reference to FIGS. 3 (a) to 3 (c).

  First, as shown in FIG. 3A, molten silicon 105 obtained by melting solid raw silicon is contained in a crucible 102 installed in a melting furnace 101 and purified in the molten silicon 105. Contains additive 104. Then, the rotating body 100 is rotated and stirred to mix the molten silicon 105 and the purification additive 104, and the purified gas 103 is blown from the tip of the rotating body 100. As a result, boron in the molten silicon 105 is oxidized by silicon oxide in the purification additive 104 to remove boron from the molten silicon 105.

  Next, as shown in FIG. 3B, phosphorus or the like is removed from the molten silicon 205 by reducing the pressure inside the melting furnace 201 while stirring the molten silicon 205 in the crucible 202 with the rotating body 200.

  Finally, as shown in FIG. 3 (c), the silicon substrate 303 is segregated on the surface of the deposition substrate 300 by immersing the deposition substrate 300 whose interior is cooled in the molten silicon 305 in the crucible 302. . As a result, the metal is removed from the molten silicon 305 on the surface of the deposition base 300 to obtain a silicon crystal 303.

  Through the above steps, it is possible to purify the silicon having a purity of about 7N required for solar cell silicon.

JP 2005-255417 A

  However, since the process of removing phosphorus from the molten silicon requires more time than other processes, the purification rate of silicon greatly depends on the removal rate of phosphorus from the molten silicon.

  Therefore, in the method described in Patent Document 1 described above, even if the processing speed of processes other than the process of removing phosphorus from molten silicon can be improved, it is not possible to expect a significant improvement in the purification efficiency of silicon. Therefore, it has been demanded to refine silicon at low cost by greatly improving the purification efficiency of silicon.

  In view of the above circumstances, an object of the present invention is to provide a silicon purification apparatus and a silicon purification method capable of performing silicon purification at a low cost by greatly improving the silicon purification efficiency. is there.

  The present invention includes a plurality of processing chambers including a decompression vessel capable of reducing an internal pressure, a heat resistant container, and a heating device for heating the heat resistant container, and the plurality of processing chambers are made of molten silicon in a reduced pressure state. This is a silicon refining apparatus that is selectively switchable to a dephosphorization processing apparatus that removes phosphorus from a metal or a demetallation processing apparatus that removes metal from molten silicon by segregation.

  The silicon purification apparatus of the present invention preferably includes a silicon charging apparatus capable of charging raw silicon into a heat-resistant container of the processing chamber, and the silicon charging apparatus is shared by at least two of the processing chambers. It is more preferable.

  Further, the silicon purification apparatus of the present invention preferably includes a pressure reducing device capable of reducing the internal pressure of the processing chamber, and the pressure reducing device is shared by at least two of the processing chambers. More preferred.

  In addition, the silicon purification apparatus of the present invention includes a rotating body that can move up and down and rotate with respect to the vertical axis as a mechanism for switching the processing chamber to a dephosphorization processing apparatus or a demetalization processing apparatus. Preferably, the rotating body is more preferably installed so as to be movable between at least two of the processing chambers. More preferably, the rotating body is a deposition substrate having a cooling function by allowing a cooling medium to pass therethrough.

  In the silicon purification apparatus of the present invention, it is preferable that the heat-resistant container is provided with a hot water discharge mechanism for discharging the molten silicon stored in the heat-resistant container.

  Moreover, the silicon purification apparatus of the present invention uses, as a raw material, the number of first processing chambers used as a dephosphorization processing apparatus and the number of second processing chambers used as a demetallation processing apparatus among a plurality of processing chambers. Preferably, it is determined by the impurity concentration of silicon.

  The present invention also includes a plurality of processing chambers including a decompression container capable of reducing the internal pressure, a heat resistant container, and a heating device for heating the heat resistant container, and the plurality of processing chambers are in a decompressed state. A silicon refining method using a silicon refining device that can be selectively switched to a dephosphorization processing device that removes phosphorus from molten silicon or a metal removal device that removes metal from molten silicon by segregation. When the processing chamber is selectively switched to either a dephosphorization processing device or a demetalization processing device, the heat setting temperature of the heat-resistant container, the heat setting temperature of the molten silicon, the internal pressure of the processing chamber, and the processing The silicon purification method includes a step of changing at least one selected from the group consisting of the presence or absence of introduction of an inert gas into the chamber.

  Furthermore, the present invention comprises a plurality of processing chambers including a decompression container capable of reducing the internal pressure, a heat resistant container, and a heating device for heating the heat resistant container, and the plurality of processing chambers are in a decompressed state. A silicon refining method using a silicon refining device that can be selectively switched to a dephosphorization processing device that removes phosphorus from molten silicon or a metal removal device that removes metal from molten silicon by segregation. The silicon purification method includes a step of measuring the impurity concentration of the raw silicon and a step of determining the number of switching chambers used and the switching timing of the plurality of processing chambers based on the impurity concentration.

  ADVANTAGE OF THE INVENTION According to this invention, the silicon | silicone refinement | purification apparatus which can implement the refinement | purification of silicon | silicone at lower cost by significantly improving the refinement | purification efficiency of silicon | silicone can be provided.

It is the schematic diagram which showed the outline of an example of the silicon refinement | purification apparatus of this invention. (A)-(c) is a time chart of an example of the refinement | purification method of the silicon | silicone using the silicon refinement | purification apparatus shown in FIG. (A)-(c) is the schematic diagram illustrated about the purification method of the conventional silicon | silicone.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

  In FIG. 1, the schematic diagram which showed the outline of an example of the silicon refinement | purification apparatus of this invention is shown. Here, the silicon purification apparatus having the configuration shown in FIG. 1 has a first processing chamber 15a, a second processing chamber 15b, and a third processing chamber 15c arranged in parallel.

  Here, inside the first processing chamber 15a, there are a first heat-resistant container 17a, a first heating device 19a for heating the first heat-resistant container 17a, and a first heat-resistant container 17a. And a first silicon introduction path 13a for introducing raw material silicon into the first silicon introduction path 13a. Note that the first processing chamber 15a includes a decompression vessel that can reduce the internal pressure.

  Further, outside the first processing chamber 15a, a first silicon injection device connection portion 12a for connecting the silicon injection device 11 and a first rotation device connection portion for connecting the rotation device 18 are provided. 14a.

  The first processing chamber 15a is provided with a first pressure reducing device connecting portion 21a for connecting the first pressure reducing device 20a.

  The second processing chamber 15b includes a second heat-resistant container 17b, a second heating device 19b for heating the second heat-resistant container 17b, and a second heat-resistant container 17b. A second silicon introduction path 13b for introducing raw silicon is provided. Note that the second processing chamber 15b includes a decompression vessel that can reduce the internal pressure.

  In addition, outside the second processing chamber 15b, a second silicon injection device connection portion 12b for connecting the silicon injection device 11 and a second rotation device connection portion for connecting the rotation device 18 are provided. 14b.

  The second processing chamber 15b has a second pressure reducing device connection portion 21b for connecting the first pressure reducing device 20a and a third pressure connecting device for connecting the second pressure reducing device 20b. A pressure reducing device connecting portion 21c is provided.

  Further, in the third processing chamber 15c, a third heat resistant container 17c, a third heating device 19c for heating the third heat resistant container 17c, and a third heat resistant container 17c are provided. A third silicon introduction path 13c for introducing raw material silicon is provided. Note that the third processing chamber 15c includes a decompression vessel that can reduce the internal pressure.

  Further, outside the third processing chamber 15 c, a third silicon loading device connection portion 12 c for connecting the silicon loading device 11 and a third rotation device connecting portion for connecting the rotation device 18. 14c.

  The third processing chamber 15c is provided with a fourth pressure reducing device connecting portion 21d for connecting the second pressure reducing device 20b.

Note that at least one of the first heat-resistant container 17a, the second heat-resistant container 17b, and the third heat-resistant container 17c includes a hot water discharge mechanism for discharging molten silicon contained in the heat-resistant container. It is preferable. Examples of the tapping mechanism include the following mechanisms.
(1) A mechanism in which only the molten silicon inside the heat-resistant container is discharged by providing a tap hole in the heat-resistant container and tilting the heat-resistant container.
(2) A mechanism in which a tapping hole and a stopper are provided at the bottom of the heat-resistant container, and normally operated with the stopper plugged, but only the molten silicon inside the heat-resistant container is discharged by removing the stopper.
(3) A mechanism for sucking out only molten silicon by immersing one end of a tubular piping member in molten silicon and lowering the pressure of the other end of the piping member (or increasing the pressure in the furnace).

Further, as the rotating body 16 driven by the rotating device 18, for example, the following rotating body can be used. The rotating body 16 is preferably movable up and down and rotatable with respect to the vertical axis.
(1) A stirring rod for stirring molten silicon under reduced pressure, which is preferably used when the processing chamber is used as a dephosphorization processing apparatus.
(2) A deposition substrate having a cooling function by allowing a cooling medium to pass inside, which is preferably used when the processing chamber is used as a demetallizing apparatus.

  In the above description, the first heat-resistant container 17a, the second heat-resistant container 17b, and the third heat-resistant container 17c are, for example, independently of high melting points according to the heating method of the heating device described later. A metal container or a graphite crucible can be used.

  Further, in the above, as the first heating device 19a, the second heating device 19b, and the third heating device 19c, for example, a resistance heating type heating device or an induction heating type heating device can be used.

  In addition, in the above, the first silicon loading device connection portion 12a, the second silicon loading device connection portion 12b, the third silicon loading device connection portion 12c, the first rotating device connection portion 14a, the second Rotating device connection portion 14b, third rotating device connection portion 14c, first pressure reducing device connection portion 21a, second pressure reducing device connection portion 21b, and third pressure reducing device connection portion 21c. In addition, as the fourth pressure reducing device connection portion 21d, for example, one having a configuration having an open / close mechanism such as a conventionally known gate valve can be used.

  In the above description, at least one of the first pressure reducing device 20a and the second pressure reducing device 20b is provided as an accessory with the first processing chamber 15a, the second processing chamber 15b, and the third processing chamber 15c. It is preferable that a gas supply device capable of introducing an inert gas (such as nitrogen or argon gas) is provided in at least one processing chamber.

  Further, in the above, the first silicon introduction path 13a, the second silicon introduction path 13b, and the third silicon introduction path 13c are each configured to be able to transport solid silicon introduced from the silicon introduction apparatus 11. If it is, it will not specifically limit.

  Further, the silicon loading device 11 is configured to be able to accommodate solid silicon which is raw material silicon. In addition, as the silicon | silicone injection | throwing-in apparatus 11, what equips the bottom part which can accommodate the solid silicon which is raw material silicon | silicone with the opening / closing mechanism which can control the passage of solid silicon etc. is used, for example. it can.

  Further, the silicon loading device 11 is configured to be movable by a transfer device (not shown), and the first silicon loading device connection portion 12a, the second silicon loading device connection portion 12b, and the third silicon loading device. It is set as the structure which can be connected to the connection part 12c for apparatuses, respectively. Accordingly, one silicon charging apparatus 11 is used, and the first heat-resistant container 17a of the first process chamber 15a, the second heat-resistant container 17b of the second process chamber 15b, and the third heat-resistant container 17c of the third process chamber 15c. Since it is possible to put solid silicon into each of the three heat-resistant containers 17c, the silicon loading device 11 is shared by the first processing chamber 15a, the second processing chamber 15b, and the third processing chamber 15c. It is the composition which is.

  The rotating device 18 includes a rotating body 16 capable of stirring the molten silicon accommodated in the first heat-resistant container 17a, the second heat-resistant container 17b, and the third heat-resistant container 17c, respectively. The body 16 can be exchanged and used according to the purpose of use of each of the processing chambers 15a, 15b, 15c.

  The rotating device 18 is also configured to be movable by a conveying device (not shown), and the first rotating device connecting portion 14a, the second rotating device connecting portion 14b, and the third rotating device connecting portion. 14c can be connected to each other. Therefore, the single rotating device 18 is also used, and the molten silicon in the first heat-resistant container 17a of the first processing chamber 15a, the molten silicon in the second heat-resistant container 17b of the second processing chamber 15b, and the first Since the molten silicon in the third heat-resistant container 17c of the third processing chamber 15c can be purified by the rotating body 16, the rotating device 18 includes the first processing chamber 15a and the second processing chamber. 15b and the third processing chamber 15c are shared.

  The first pressure reducing device 20a is connected to the first pressure reducing device connecting portion 21a of the first processing chamber 15a and the second pressure reducing device connecting portion 21b of the second processing chamber 15b, respectively. Thus, the pressure inside the first processing chamber 15a and the pressure inside the second processing chamber 15b can be reduced. Therefore, the first pressure reducing device 20a is configured to be shared by the first processing chamber 15a and the second processing chamber 15b. As the first pressure reducing device 20a, a conventionally known vacuum device or the like can be used.

  The second pressure reducing device 20b is connected to the third pressure reducing device connecting portion 21c of the second processing chamber 15b and the fourth pressure reducing device connecting portion 21d of the third processing chamber 15c, respectively. Thus, the pressure inside the second processing chamber 15b and the pressure inside the third processing chamber 15c can be reduced. Therefore, the second pressure reducing device 20b is configured to be shared by the second processing chamber 15b and the third processing chamber 15c. As the second pressure reducing device 20b, a conventionally known vacuum device or the like can be used.

  In the description of the embodiment using FIG. 1 described above, an example in which there are three processing chambers is shown, but the present invention is not limited to this, and more processing chambers are used. May be.

  In addition, in terms of device manufacturing costs, device running costs, and reduction of device footprint, it is necessary that the silicon input device, pressure reducing device, and rotating device connected to each processing chamber are shared by two or more processing chambers. Although preferred, these devices may of course be a single device connected to a single processing chamber.

Further, by adopting the apparatus configuration as described above (for example, as shown in FIG. 1), each processing chamber can be selectively used as any two or more of the following processing apparatuses (a) to (c). It will be installed in a switchable manner.
(A) A melt processing apparatus that heats raw material silicon to form molten silicon.
(B) A dephosphorization apparatus for removing phosphorus from molten silicon.
(C) A demetallation apparatus for removing metal from molten silicon.

  Note that (a) when the processing chamber is used as a melting processing apparatus, it is preferable to prevent silicon from being oxidized at the time of melting, so the raw material silicon is reduced under reduced pressure (for example, about 500 Pa or less) or under an inert gas atmosphere (for example, Conditions can be set so that the temperature is higher than the melting point of silicon (1410 ° C. to 1414 ° C.) (for example, 1450 ° C. to 1600 ° C.) at a normal pressure with argon gas following depressurization.

  Further, (b) when the processing chamber is used as a dephosphorization processing apparatus, molten silicon is heated at a relatively high temperature (for example, 1500 ° C. to 1700 ° C.) and a relatively high vacuum (preferably 10 Pa or less) in order to increase the efficiency of phosphorus evaporation. Furthermore, it is possible to set the conditions so as to be 2 Pa or less.

  In addition, when (c) the processing chamber is used as a demetallizing apparatus, the molten silicon is set at a relatively low temperature (for example, 1425 ° C. to 1500 ° C.) in order to increase the deposition efficiency on the deposition substrate by segregation. preferable. When the atmospheric gas is an inert gas, there is no need to limit the pressure, and it can usually be a normal pressure.

  Thus, in order to use each processing chamber for each purpose, at least the heating set temperature of the heat-resistant container, the heating setting temperature of the molten silicon, the internal pressure of the processing chamber, and the introduction of the inert gas into the processing chamber It is preferable to change at least one selected from the group consisting of presence and absence. As a method for setting the temperature of the molten silicon and a method for measuring the temperature of the molten silicon, for example, a method for setting the temperature of the molten silicon and a method for measuring the temperature and / or a temperature setting and measuring the temperature of the heat resistant container are performed. Possible methods.

  Directly setting and measuring the temperature of the molten silicon is preferable as reflecting the molten state more accurately than setting and measuring the temperature of the heat-resistant container. However, rather than directly measuring the temperature of the molten silicon (for example, by an emission spectrum) and changing (feedback) the driving state of the heating device by comparing with the set temperature, the temperature of the heat-resistant container is directly measured (for example, It is easier to feed back by using a thermocouple, and it does not make much sense to measure the temperature of the raw silicon itself at the start of melting (the temperature varies greatly depending on the location in the solid state) and is heat resistant. The temperature setting / measurement of the molten silicon and the temperature setting / measurement of the heat-resistant container can be properly used because it is better to set / measure the temperature of the heat resistant container.

  Furthermore, in the silicon refining method using the apparatus of the present embodiment, before starting the silicon refining process, a concentration measuring step for measuring the type and concentration of impurities in the raw silicon, and the number of processing chambers switched depending on the impurity concentration and It is preferable that a time chart creating step for determining the switching use timing is performed. Since the types and concentrations of impurities contained in the raw material silicon (for example, metal grade silicon, silicon ingot mills, non-standard IC single crystal silicon products, silicon wafer reuse, etc.) are not constant, The device configuration and time required for impurity removal vary. Therefore, in order to remove these efficiently, it is preferable to determine in advance the number of switching chambers used and the switching timing.

  Generally, phosphorus (P), boron (B), and metal (M: generally iron, aluminum, etc.) can be considered as impurities contained in the raw material silicon. In this embodiment, the raw material silicon used in the following examples The raw material silicon containing P and M will be described in line with the example.

  For example, if a conventional apparatus as shown in Patent Document 1 is used to purify raw silicon having a high phosphorus concentration and a de-P process that takes a longer time than a de-M process, the idle time of the de-M apparatus (deposition substrate) is longer. Therefore, it is considered that the operation efficiency (as the entire apparatus) is improved by increasing the number of processing chambers used as the P removal apparatus. On the other hand, when purifying raw silicon where the phosphorus concentration is low and the de-M process takes longer than the de-P process, the de-M apparatus will limit the entire process. It is considered that the operation efficiency is improved by increasing the number of processing chambers used as the de-M apparatus.

  Therefore, it is possible to change the apparatus of the silicon purification apparatus of the present invention as appropriate, and in particular, the number of first processing chambers used as the de-P processing apparatus among the plurality of processing chambers and the de-M processing apparatus. The number of second processing chambers is preferably determined by the impurity concentration of the raw silicon.

  Hereinafter, an example of a silicon purification method using the silicon purification apparatus shown in FIG. 1 will be described with reference to the time charts of FIGS. 2 (a) to 2 (c).

  Since the raw material silicon used in this example contains phosphorus and metal as impurities and the boron concentration is at a level that does not cause a problem as solar cell silicon (about 0.1 ppm by weight), the de-B process (from molten silicon to boron) Is not performed.

  FIG. 2A shows a time chart of a de-P process (step of removing phosphorus from molten silicon) and a de-M process (step of removing metal from molten silicon) performed in the first processing chamber 15a. Yes. FIG. 2B shows a time chart of the de-P process and the de-M process performed in the second processing chamber 15b. Further, FIG. 2C shows a time chart of the de-P process and the de-M process performed in the third processing chamber 15c.

  2 (a) to 2 (c), the horizontal axis indicates the elapsed time from the start of the preparation of the solid silicon serving as the source silicon in the first processing chamber 15a, and the vertical axis Indicates each step of the de-P process and the de-M process. Moreover, the shaded portion in FIGS. 2A to 2C indicates that each step of the de-P process and the de-M process is performed.

  First, as shown in FIG. 2 (a) (the uppermost stage (first stage)), in the first processing chamber 15a, a preparation process for adding solid silicon as raw material silicon is performed, for example, for 30 minutes. Here, in the solid silicon charging preparation step, for example, the silicon charging device 11 is connected to the first silicon charging device connecting portion 12a of the first processing chamber 15a, and then the silicon charging device 11 becomes raw material silicon. It can be performed by filling with solid silicon.

  Next, as shown in the second stage of FIG. 2 (a), in the first processing chamber 15a, a step of introducing solid silicon as raw material silicon is performed, for example, for 1 hour 30 minutes. Here, the solid silicon charging step is performed by, for example, opening the opening / closing mechanism of the bottom portion of the silicon charging apparatus 11 filled with solid silicon and opening the opening / closing mechanism of the first silicon charging apparatus connecting portion 12a. This can be performed by, for example, introducing silicon into the first heat-resistant container 17a inside the first processing chamber 15a through the first silicon introduction path 13a from the silicon introduction apparatus 11.

  Next, as shown in the third stage of FIG. 2A, in the first processing chamber 15a, a melting process of solid silicon, which is the raw material silicon, is performed, for example, for 30 minutes. Here, the solid silicon melting step is performed, for example, by heating the first heat-resistant container 17a in the first processing chamber 15a with the first heating device 19a, thereby solids in the first heat-resistant container 17a. It can be performed by dissolving silicon to obtain molten silicon.

Next, as shown in the fourth stage of FIG. 2A, a evacuation step is performed in the first processing chamber 15a to reduce the pressure inside the first processing chamber 15a. Here, the evacuation step is performed, for example, by opening the opening / closing mechanism of the first pressure reducing device connecting portion 21a and sucking the gas inside the first processing chamber 15a by the first pressure reducing device 20a. be able to. Note that the pressure inside the first processing chamber 15a can be set to, for example, about 10 ⁻² Pa by the evacuation step. Further, in the fourth stage of FIG. 2A, for convenience of explanation, it is described that the evacuation process is performed only for 15 minutes, but the evacuation process is continued during the de-P treatment process described later. .

  Next, as shown in the fifth stage of FIG. 2A, a de-P treatment process for removing phosphorus from the molten silicon is performed in the first treatment chamber 15a, for example, for 6 hours and 30 minutes. Here, in the de-P treatment process, for example, the evacuation process is continuously performed while the molten silicon in the first heat-resistant container 17a is maintained in the molten state, and in addition to this, the rotation mechanism 18 rotates. It can be carried out by stirring the molten silicon with a rotating body 16 (in this case, a stirring rod).

  Next, as shown in the sixth stage of FIG. 2A, in the first processing chamber 15a, an Ar introducing step for introducing argon into the first processing chamber 15a is performed, for example, for 30 minutes. Here, the Ar introduction step is performed, for example, by introducing argon into the first processing chamber 15a from an argon introduction path (not shown) and increasing the pressure inside the first processing chamber 15a to about atmospheric pressure. be able to.

  Next, as shown in the seventh stage of FIG. 2A, in the first processing chamber 15a, a temperature adjustment step for adjusting the temperature of the molten silicon in the first heat-resistant container 17a is performed, for example, for 30 minutes. It is. Here, in the temperature adjustment step, for example, at least one of a heat-resistant container, a heating device, and molten silicon is a measurement target, and the temperature is measured with a thermocouple and / or a radiation thermometer, and PID control or the like is used. A method of feeding back to the heating output can be used. Also, sample the molten silicon and measure the phosphorus concentration or resistivity (if the temperature is low, the phosphorus evaporation rate is slow, so the phosphorus concentration is higher than expected or the resistivity is low, etc. Method), measure the amount of evaporate (when the temperature is low, the rate of evaporation of phosphorus is slow, so the amount of evaporate is less than expected), measure the weight of molten silicon (if the temperature is low, silicon Since the evaporation rate is low, the weight of the molten silicon is less than expected).

  Next, as shown in the eighth stage of FIG. 2 (a), in the first treatment chamber 15a, metal or the like is removed by segregating the molten silicon in the first heat-resistant container 17a by rotational segregation. A rotational segregation process for obtaining purified silicon crystals is performed, for example, for 3 hours. Here, the rotation segregation step can be performed, for example, as follows. First, the rotating device 18 is moved to the first processing chamber 15a, the rotating device 18 and the second rotating device connecting portion 14b are connected, and the opening / closing mechanism of the second rotating device connecting portion 14b is opened and rotated. The body 16 (in this case, the deposition base) is lowered, and the rotating body 16 of the rotating device 18 is immersed in the molten silicon in the first heat-resistant container 17a. Thereafter, the rotation can be performed by causing the silicon crystal to segregate on the outer surface of the rotating body 16 by rotating the rotating body 16 while flowing a coolant such as nitrogen.

  Here, as shown in the fifth stage of FIG. 2 (a) and the first stage of FIG. 2 (b), 1 hour 30 minutes from the start of the de-P treatment process in the first treatment chamber 15a. After the lapse of time, similarly to the processing in the first processing chamber 15a, in the second processing chamber 15b, a preparation process (for example, 30 minutes) of solid silicon to be raw material silicon is started. Then, following the solid silicon charging preparation process, the solid silicon charging process (for example, 1 hour 30 minutes), the solid silicon melting process (for example, 30 minutes), the vacuuming process (for example, 15 minutes), the de-P treatment process ( For example, an Ar introduction process (for example, 30 minutes), a temperature adjustment process (for example, 30 minutes), and a rotation segregation process (for example, 3 hours) are performed in this order.

  The solid silicon charging preparation step (first stage in FIG. 2B) in the second processing chamber 15b is, for example, for the silicon charging device 11 and the first silicon charging device in the first processing chamber 15a. After releasing the connection with the connecting portion 12a, the silicon loading apparatus 11 is moved to the second processing chamber 15b, and the silicon loading apparatus 11 and the second silicon loading apparatus connecting portion 12b of the second processing chamber 15b are connected. The connection can be made, and then the silicon charging device 11 can be filled with solid silicon as raw material silicon.

  In addition, the solid silicon charging step (second stage in FIG. 2B) in the second processing chamber 15b includes, for example, opening an opening / closing mechanism at the bottom of the silicon charging apparatus 11 filled with solid silicon, and By opening the opening / closing mechanism of the connection portion 12b for the silicon injection device 2, the solid silicon is transferred from the silicon injection device 11 to the second heat-resistant container 17b inside the second processing chamber 15b through the second silicon introduction path 13b. This can be done by throwing it in.

  In addition, the solid silicon melting step (second stage in FIG. 2B) in the second processing chamber 15b is performed by, for example, replacing the second heat-resistant container 17b inside the second processing chamber 15b with the second process chamber 15b. The heating can be performed by heating the heating device 19b to dissolve the solid silicon in the second heat-resistant container 17b to form molten silicon.

Further, the evacuation process (fourth stage in FIG. 2B) in the second processing chamber 15b can be performed, for example, as follows. First, while the de-P process step (fifth stage in FIG. 2A) in the first processing chamber 15a is being performed, the opening / closing mechanism of the third pressure reducing device connecting portion 21c is opened. For example, the second pressure reducing device 20b sucks the gas inside the second processing chamber 15b. Then, when the de-P treatment process in the first processing chamber 15a is completed, the second pressure reducing device 20b stops the suction of the gas inside the second processing chamber 15b and the third pressure reducing device connecting portion. The opening / closing mechanism 21c is closed. Then, the opening and closing mechanism of the second pressure reducing device connecting portion 21b can be opened to switch the suction of the gas inside the second processing chamber 15b to the first pressure reducing device 20a. Note that the pressure inside the second processing chamber 15b can be set to, for example, about 10 ⁻² Pa by the evacuation step. Also, in the fourth stage of FIG. 2B, for convenience of explanation, it is described that the evacuation process is performed only for 15 minutes, but the evacuation process is a de-P treatment process (FIG. 2B) described later. The fifth stage) continues.

  In addition, the de-P treatment process (fifth stage in FIG. 2B) in the second treatment chamber 15b is performed, for example, with the above vacuum while maintaining the molten state of the molten silicon in the second heat-resistant container 17b. It can be carried out by continuing the drawing step.

  In addition, the Ar introduction step (sixth stage in FIG. 2B) in the second processing chamber 15b is performed by introducing argon into the second processing chamber 15b from an argon introduction path (not shown), for example. This can be done by increasing the pressure inside the processing chamber 15b to about atmospheric pressure.

  Further, the temperature adjustment step (seventh stage in FIG. 2B) in the second processing chamber 15b can be performed by the same method as described above.

  Moreover, the rotation segregation process (8th stage | paragraph of FIG.2 (b)) in the 2nd process chamber 15b can be performed as follows, for example. First, the rotating device 18 is moved to the second processing chamber 15b, the rotating device 18 and the second rotating device connecting portion 14b are connected, and the opening / closing mechanism of the second rotating device connecting portion 14b is opened to rotate. The body 16 (in this case, the deposition base) is lowered, and the rotating body 16 of the rotating device 18 is immersed in the molten silicon in the second heat-resistant container 17b. Thereafter, the rotation can be performed by causing the silicon crystal to segregate on the outer surface of the rotating body 16 by rotating the rotating body 16 while flowing a coolant such as nitrogen.

  Further, as shown in the fifth stage of FIG. 2B and the first stage of FIG. 2C, 1 hour and 30 minutes have elapsed since the start of the de-P treatment process in the second treatment chamber 15b. Later, similarly to the processing in the first processing chamber 15a and the second processing chamber 15b, in the third processing chamber 15c, a preparation process (for example, 30 minutes) of solid silicon to be raw material silicon is started. Then, following the solid silicon charging preparation process, the solid silicon charging process (for example, 1 hour 30 minutes), the solid silicon melting process (for example, 30 minutes), the vacuuming process (for example, 15 minutes), the de-P treatment process ( For example, an Ar introduction process (for example, 30 minutes), a temperature adjustment process (for example, 30 minutes), and a rotation segregation process (for example, 3 hours) are performed in this order.

  Here, the solid silicon charging preparation step (first stage in FIG. 2C) in the third processing chamber 15c is, for example, the silicon charging device 11 and the second silicon charging device in the second processing chamber 15b. After the connection with the connection portion 12b is released, the silicon loading device 11 is moved to the third processing chamber 15c, and the silicon loading device 11 and the third silicon loading device connection portion 12c in the third processing chamber 15c After that, the silicon charging device 11 can be filled with solid silicon as raw material silicon.

  The solid silicon charging step (second stage in FIG. 2C) in the third processing chamber 15c opens, for example, an opening / closing mechanism at the bottom of the silicon charging apparatus 11 filled with solid silicon, By opening the opening / closing mechanism of the silicon injection device connecting portion 12c, the solid silicon is transferred from the silicon input device 11 to the third heat-resistant container 17c inside the third processing chamber 15c through the third silicon introduction path 13c. This can be done by throwing it in.

  In addition, the solid silicon melting step (third stage in FIG. 2C) in the third processing chamber 15c is performed by, for example, replacing the third heat-resistant container 17c inside the third processing chamber 15c with the third The heating can be performed by, for example, melting the solid silicon in the third heat-resistant container 17c to form molten silicon by heating with the heating device 19c.

Further, in the evacuation step (fourth stage in FIG. 2C) in the third processing chamber 15c, for example, the second pressure reducing device is opened by opening the opening / closing mechanism of the fourth pressure reducing device connecting portion 21d. It can be performed by sucking the gas inside the third processing chamber 15c by 20b. Note that the pressure inside the third processing chamber 15c can be set to, for example, about 10 ⁻² Pa by the evacuation step. In FIG. 2C, for convenience of explanation, it is described that the evacuation process is performed only for 15 minutes, but the evacuation process is continued during the de-P treatment process described later.

  Further, the de-P treatment process (fifth stage in FIG. 2 (c)) in the third treatment chamber 15c is, for example, the above vacuum while maintaining the molten state of the molten silicon in the third heat-resistant container 17c. It can be carried out by continuing the drawing step.

  The Ar introducing step (the sixth stage in FIG. 2C) in the third processing chamber 15c is performed by introducing argon into the third processing chamber 15c from an argon introduction path (not shown), for example. This can be done by increasing the pressure inside the processing chamber 15c to about atmospheric pressure.

  Further, the temperature adjustment step (seventh stage in FIG. 2C) in the third processing chamber 15c can be performed by the same method as described above.

  Moreover, the rotation segregation process (the 8th stage of FIG.2 (c)) in the 3rd process chamber 15c can be performed as follows, for example. First, the rotating device 18 is moved to the third processing chamber 15c, the rotating device 18 and the third rotating device connecting portion 14c are connected, and the opening / closing mechanism of the third rotating device connecting portion 14c is opened to rotate. The body 16 (in this case, the deposition base) is lowered to immerse the rotating body 16 of the rotating device 18 in the molten silicon in the third heat-resistant container 17c. Thereafter, the rotation can be performed by causing the silicon crystal to segregate on the outer surface of the rotating body 16 by rotating the rotating body 16 while flowing a coolant such as nitrogen.

  Further, as shown in the first stage of FIG. 2A and the fifth stage of FIG. 2C, 1 hour and 30 minutes have elapsed since the start of the de-P treatment process in the third treatment chamber 15c. Later, in the first processing chamber 15a, a second silicon purification step similar to the above is started. Here, the second silicon purification step is performed in the same manner as described above, in the step of preparing solid silicon (for example, 30 minutes), the step of introducing solid silicon (for example, 1 hour and 30 minutes), and the step of dissolving solid silicon (for example, 30). Minutes), evacuation process (for example, 15 minutes), de-P treatment process (for example, 6 hours and 30 minutes), Ar introduction process (for example, 30 minutes), temperature adjustment process (for example, 30 minutes), and rotational segregation process (for example, 3 hours) Are performed in this order.

  In the embodiment described here, the treatment time of the de-P treatment process is longer than the treatment time of the de-M treatment process (rotational segregation process). In such a case, as described above, while the de-P process is performed in any one of the first to third process chambers, a part of the de-P process and the de-M process are performed in another process chamber. By controlling to perform the steps, the silicon purification efficiency can be improved.

  As described above, in the silicon purification apparatus of the present invention, the silicon purification step in the first processing chamber 15a, the silicon purification step in the second processing chamber 15b, and the silicon purification step in the third processing chamber 15c are performed. Each can be done in parallel. Therefore, in the silicon purification apparatus of the present invention, steps other than the de-P treatment step such as the rotation segregation step can be performed in another treatment chamber while the de-P treatment step proceeds in a certain treatment chamber.

  Therefore, in the silicon purification apparatus of the present invention, the purification rate of silicon can be advanced without depending on the de-P treatment process, so that the silicon purification efficiency can be greatly improved. As a result, the silicon can be purified at a low cost.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  There is a possibility that the silicon purification apparatus of the present invention can be suitably used for purification of silicon for solar cells, for example.

  11 Silicon input device, 12a First silicon input device connection, 12b Second silicon input device connection, 12c Third silicon input device connection, 13a First silicon introduction path, 13b Second Silicon introduction path, 13c 3rd silicon introduction path, 14a 1st rotation apparatus connection part, 14b 2nd rotation apparatus connection part, 14c 3rd rotation apparatus connection part, 15a 1st process chamber, 15b 2nd processing chamber, 15c 3rd processing chamber, 16 rotator, 17a 1st heat resistant container, 17b 2nd heat resistant container, 17c 3rd heat resistant container, 18 rotation apparatus, 19a 1st heating Device, 19b second heating device, 19c third heating device, 20a first pressure reducing device, 20b second pressure reducing device, 21a first pressure reducing device connection, 21b second Force reduction device connection, 21c third pressure reduction device connection, 21d fourth pressure reduction device connection, 100,200 rotor, 101, 201, 301 melting furnace, 102, 202, 302 crucible, 103 Purified gas, 104 Purified additive, 105, 205, 305 Molten silicon, 300 Precipitation substrate, 303 Silicon crystal.

Claims (12)

A decompression vessel capable of reducing the internal pressure;
A heat-resistant container;
A plurality of processing chambers including a heating device for heating the heat-resistant container,
The silicon purification, wherein the plurality of processing chambers are selectively switchable to a dephosphorization apparatus for removing phosphorus from molten silicon in a reduced pressure state or a demetallation apparatus for removing metal from molten silicon by segregation. apparatus.   The silicon refining apparatus according to claim 1, further comprising a silicon charging apparatus capable of charging raw silicon into the heat resistant container of the processing chamber.   The silicon purification apparatus according to claim 2, wherein the silicon charging apparatus is shared by at least two of the processing chambers.   The silicon purifier according to any one of claims 1 to 3, further comprising a pressure reducing device capable of reducing an internal pressure of the processing chamber.   The silicon purification apparatus according to claim 4, wherein the pressure reducing apparatus is shared by at least two of the processing chambers.   6. The rotating body that is vertically movable and rotatable about a vertical axis is provided as a mechanism for switching the processing chamber to the dephosphorization processing apparatus or the demetalization processing apparatus. 6. A silicon purification apparatus as described in 1.   The silicon refining apparatus according to claim 6, wherein the rotating body is movably installed between at least two of the processing chambers.   The silicon refining device according to claim 6 or 7, wherein the rotary body is a deposition base having a cooling function by allowing a cooling medium to pass therethrough.   The silicon purification apparatus according to any one of claims 1 to 8, wherein the heat-resistant container includes a hot water discharge mechanism for discharging molten silicon stored in the heat-resistant container.   Of the plurality of processing chambers, the number of first processing chambers used as the dephosphorization processing apparatus and the number of second processing chambers used as the demetallation processing apparatus are determined by the impurity concentration of the raw silicon. The silicon purifier according to any one of claims 1 to 9. A decompression vessel capable of reducing the internal pressure;
A heat-resistant container;
A plurality of processing chambers including a heating device for heating the heat-resistant container,
The silicon purification apparatus in which the plurality of processing chambers are selectively switchable to a dephosphorization apparatus that removes phosphorus from molten silicon in a reduced pressure state or a demetallation apparatus that removes metal from molten silicon by segregation. A silicon purification method using
When the processing chamber is selectively switched to either the dephosphorization processing apparatus or the demetalization processing apparatus, the heat setting temperature of the heat-resistant container, the heat setting temperature of the molten silicon, A silicon purification method comprising a step of changing at least one selected from the group consisting of an internal pressure and presence / absence of introduction of an inert gas into the processing chamber. A decompression vessel capable of reducing the internal pressure;
A heat-resistant container;
A plurality of processing chambers including a heating device for heating the heat-resistant container,
The silicon purification apparatus in which the plurality of processing chambers are selectively switchable to a dephosphorization apparatus that removes phosphorus from molten silicon in a reduced pressure state or a demetallation apparatus that removes metal from molten silicon by segregation. A silicon purification method using
Measuring the impurity concentration of the raw material silicon;
And determining the switching usage number and switching usage timing of the plurality of processing chambers according to the impurity concentration.

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