JP4403902B2 - Raw material supply equipment - Google Patents

Description

  The present invention relates to a raw material supply apparatus for supplying a silicon raw material into a crucible after pulling a single crystal of a single crystal pulling apparatus by the Czochralski method.

  Conventionally, in the production of a silicon single crystal by the Czochralski method (hereinafter referred to as “CZ method”), a multiple method is known as a method for reducing the production cost. In the multiple pulling method, after pulling up a silicon single crystal having a dopant concentration within a predetermined range, an additional amount of silicon raw material corresponding to the amount of silicon raw material in the crucible is additionally supplied. This is a method of repeatedly pulling up the silicon single crystal. According to this method, the production yield is improved, and a plurality of single crystals can be produced from a quartz crucible that can be used only once. Therefore, it is expected that the crucible cost can be reduced and the production cost of the silicon single crystal can be reduced. Yes.

As an additional supply method of this silicon raw material, the granular silicon raw material is retained in a vertical charging pipe whose tip is close to the melt surface of the silicon melt or the solidified surface, and then the retention of the granular silicon raw material in the vertical charging pipe is maintained. The crucible is lowered or the vertical feed pipe is raised to form an unmelted layer of granular silicon material on the molten or solidified surface of the silicon melt, and the unmelted layer is melted and the granular silicon in the vertical feed pipe is melted. There has been proposed a method of supplying a granular silicon raw material to an unmelted layer through a vertical input pipe while maintaining the retention of the raw material (for example, see Patent Document 1). With this supply method, the silicon raw material can be supplied quickly and without damaging the quartz crucible, and a vertical injection pipe provided substantially vertically as an apparatus used in this method, and an upper portion of the vertical injection pipe And an inclined inclined charging pipe for supplying the granular silicon raw material to the vertical charging pipe.
Japanese Patent No. 3396388 (Claims, Description [0014], FIG. 1)

  However, in the above-mentioned conventional raw material supply apparatus, when a granular or massive polycrystalline raw material is supplied from the inclined input pipe to the vertical input pipe, the raw material supplied to the upper end of the inclined input pipe moves downward while increasing its kinetic energy. Therefore, the friction caused by the interference of the raw material at the upper end of the vertical input pipe is large, and shell-like chips and cracks may be generated on the inner surface of the vertical input pipe. Due to the magnitude of the kinetic energy, there is also a problem that wear or breakage occurs in the portion where the raw material of the inclined charging pipe or the vertical charging pipe contacts.

On the other hand, in the conventional raw material supply apparatus, although a cut gate is provided to stop the supply of the raw material once when a predetermined amount of raw material is supplied, the raw material is a massive or granular polycrystalline raw material. In addition, there may be a situation where the raw material bites into the cut gate and the supply of the raw material cannot be stopped. For this reason, even in such a situation, it is desirable to reliably dam the supply of the raw material and avoid a situation where the raw material is excessively supplied.
An object of the present invention is to provide a raw material supply apparatus capable of supplying a raw material without causing a chipping of a polycrystalline silicon raw material or the like and damage of a vertical charging pipe or the like.
Another object of the present invention is to provide a raw material supply apparatus capable of supplying a predetermined amount of raw material relatively accurately.

As shown in FIGS. 1 and 4, the invention according to claim 1 includes a vertical charging pipe 20 having a lower end facing a raw material melt 37 in a crucible 32 after pulling a single crystal of a single crystal pulling apparatus 30, And the hoppers 15, 16, and 17 capable of supplying a granular or massive raw material 26 to the upper end of the inclined charging pipe 19. This is an improvement of the raw material supply apparatus configured to be able to supply the raw material 26 supplied to the hoppers 15, 16, and 17 to the raw material melt 37 through the inclined charging pipe 19 and the vertical charging pipe 20.
As shown in detail in FIG. 1, the characteristic configuration is such that the lower end opening portion of the inclined charging pipe 19 is closed so as to be openable, and the damage applied to the vertical charging pipe 20 into which the raw material 26 flows from the inclined charging pipe 19 is reduced . A plate 22 is located at the top of the vertical input tube 20.

When the raw material 26 supplied to the hoppers 15, 16, and 17 moves in the inclined charging pipe 19 and the vertical charging pipe 20, its kinetic energy increases with the movement, and when the raw material and the member interfere, Wear becomes remarkable, and in some cases, the member is largely peeled off, cracks are generated, and sometimes damage is caused. Here, there is a risk of breakage because the part where the inclined charging pipe 19 and the vertical charging pipe 20 are joined interferes with the moving direction of the raw material 26. However, in the raw material supply apparatus described in claim 1, the kinetic energy of the raw material 26 increased by inserting the closing plate 22 into the portion and damming the raw material 26 to move to the lower end of the inclined charging pipe 19. Can be canceled once, and damage to the vertical charging pipe 20 into which the raw material 26 flows thereafter can be reduced.
Further, in the raw material supply apparatus described in claim 1, it is possible to control the cutting and stopping of the raw material 26 by opening and closing the lower end opening of the inclined charging pipe 19 using the closing plate 22. Therefore, even if a situation occurs in which the cutting of the raw material 26 cannot be stopped on the upstream side of the inclined charging pipe 19, the lower end opening of the inclined charging pipe 19 is closed by the closing plate 22, so that the crucible 32 enters the crucible 32. It is possible to effectively avoid the trouble that the raw material 26 exceeding the capacity is supplied and the raw material 26 overflows to cause hot zone damage.

The invention according to claim 2 is the invention according to claim 1, and further, as shown in FIG. 3, a predetermined amount of raw material 26 can be deposited at the lower end of the vertical input pipe 20, and the lower part of the vertical input pipe 20. In the vertical charging pipe 20, the raw material 26 exceeding the predetermined amount of raw material 26 deposited in the deposition portion 20 c is melted in the crucible 32. This is a raw material supply device configured to fall into the liquid 37.
As described above, the portion that interferes with the raw material 26 may cause damage to the member. However, in the raw material supply apparatus described in claim 2, by depositing the raw material 26 by forming the deposition portion 20c. The kinetic energy of the raw material 26 is absorbed by the raw material 26 deposited on the deposition portion 20c by acting as a cushion, and wear and breakage in the lower portion of the vertical charging pipe 20 can be prevented.

The invention according to claim 3 is the invention according to claim 1 or 2, and further, as shown in FIGS. 2 and 5, the inclined injection pipe 19 is moved by moving the inclined injection pipe 19 in the axial direction or raising the closing plate 22. 19 is a raw material supply device in which the lower end opening of 19 is opened.
In the raw material supply apparatus according to the third aspect, the lower end opening of the inclined charging pipe 19 can be effectively opened to avoid a situation in which the raw material 26 cannot be supplied. In addition, since each can be moved arbitrarily, it is possible to cut out the raw material delicately, and it is possible to prevent the hot zone from being damaged due to excessive supply.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the closing plate 22 is made of the same material as the raw material 26 or a material having higher hardness than the raw material 26. It is.
In the raw material supply apparatus described in claim 4, if the closing plate 22 is the same as the raw material 26, there is no fear of impurity contamination even if the closing plate 22 is worn due to interference and mixed into the crucible 32. Alternatively, if the closing plate 22 is made of a material having a hardness of not less than the raw material 26 such as silicon carbide, the contamination of the closing plate 22 can be prevented and impurity contamination can be avoided.

In the raw material supply apparatus of the present invention, the lower end opening of the inclined charging pipe is closed so as to be openable, and a closing plate for reducing damage to the vertical charging pipe into which the raw material flows from the inclined charging pipe is provided at the upper part of the vertical charging pipe. Therefore, by damming the raw material at one end with the closing plate, the kinetic energy of the raw material increased by moving to the lower end of the inclined charging pipe can be canceled once, and the damage applied to the vertical charging pipe into which the raw material flows thereafter Can be reduced. Moreover, it becomes possible to control the cutting and stopping of the raw material by opening and closing the lower end opening of the inclined charging pipe using a closing plate, so that the cutting of the raw material cannot be stopped upstream of the inclined charging pipe. Even if an unforeseen situation arises, it is possible to effectively avoid the trouble that the raw material exceeding the capacity is supplied into the crucible by closing the lower end opening of the inclined charging pipe with the closing plate.

In addition, a predetermined amount of raw material can be deposited at the lower end of the vertical injection pipe, and a lower end portion for preventing wear and damage at the lower part of the vertical injection pipe forms a dome-like swelled deposition part, and is deposited on the accumulation part. If a material exceeding a specified amount of material falls into the material melt in the crucible, the kinetic energy of the material that falls inside the vertical charging pipe will act as a cushion on the material deposited in this accumulation part. It is possible to prevent the wear and breakage in the lower part of the vertical charging pipe. Then, if the lower end opening of the inclined inlet pipe is opened by moving the inclined inlet pipe in the axial direction or raising the closing plate, the lower end opening of the inclined inlet pipe is effectively opened and the raw material cannot be supplied. The situation can be avoided. In addition, since each can be moved arbitrarily, it is possible to cut out the raw material delicately, and it is possible to prevent the hot zone from being damaged due to excessive supply.
Furthermore, if the closing plate is made of the same material as the raw material or a material having a higher hardness than the raw material, it is possible to avoid a situation where impurities are mixed into the crucible.

Next, the best mode for carrying out the present invention will be described with reference to the drawings.
As shown in FIG. 4, the raw material supply apparatus 10 is configured to be portable so as to reciprocate between the upper portion of the main chamber 31 in the single crystal pulling apparatus 30 and a side retracted position thereof. These are connected to a top chamber 34 provided at the top of the main chamber 31 instead of a pull chamber (not shown). The raw material supply apparatus 10 is configured to automatically supply a polycrystalline raw material, particularly a bulk raw material having a particle size of 30 mm or less, to the crucible 32 in the main chamber 31. The specific configuration will be described below. The portable raw material supply apparatus 10 includes a movable frame 11, a first chamber 12 mounted on the movable frame 11, and a connecting pipe on the side of the first chamber 12. And a second chamber 14 mounted on the movable frame 11 in a state of being connected via 13.

  Inside the first chamber 12, a first hopper 15, a second hopper 16, and a third hopper 17 are arranged in order from top to bottom, and a fixed amount is placed between the second hopper 16 and the third hopper 17. A cut-out feeder 18 is arranged. The first hopper 15 is a raw material hopper, the bottom surface of which is a tapered surface with an inclination angle of 45 degrees or more, and the discharge port 15b provided at the center thereof can be opened and closed by a cut gate 15a made of polycrystalline silicon. Configured. The bottom surfaces of the second hopper 16 and the third hopper 17 are also tapered surfaces having an inclination angle of 45 degrees or more, like the first hopper 15, and the second hopper 16 is a raw material cut out from the first hopper 15 by the cut gate 15a. The third hopper 17 is configured to receive the raw material falling from the end of the feeder 18 after being guided to the quantitative cutout feeder 18.

  The connecting pipe 13 is an inclined pipe descending from the first chamber 12 toward the second chamber 14, and an inclined charging pipe 19 is accommodated therein so as to be movable in the axial direction. The inclined charging pipe 19 has an upper end disposed downstream of the third hopper 17 and is configured to guide the raw material to an upper part of a vertical charging pipe 20 described later, and the inclined charging pipe 19 has an inclination angle of 45 degrees. The second chamber 14 is a cylindrical sealed container connected to the downstream side of the connecting pipe 13, and the second chamber 14 can be connected to a top chamber 34 having a gate valve 33 of the single crystal pulling device 30. Composed. A first actuator 21 that raises and lowers the vertical charging pipe 20 is provided on the upper portion of the second chamber 14. The first actuator 21 in this embodiment is a so-called air cylinder that projects the projecting shaft 21a so as to be immersible by air pressure, and a vertical charging pipe 20 is provided on the projecting shaft 21a. The first actuator 21 projects the projecting shaft 21 a to insert the vertical throwing pipe 20 from the second chamber 14 into the main chamber 31 of the single crystal pulling apparatus 30, and the lower end of the vertical throwing pipe 20 is crucible 32. The vertical insertion tube 20 can be accommodated in the second chamber 14 by immersing the protruding shaft 21a.

  As shown in detail in FIG. 1, both the vertical charging pipe 20 and the inclined charging pipe 19 are made of quartz tubes, and a closing plate for closing the lower end opening of the inclined charging pipe 19 so as to be openable is provided above the vertical charging pipe 20. 22 is provided. The closing plate 22 in this embodiment is a plate made of the same material as the input material, and is provided on the upper portion of the vertical input tube 20 via a second actuator 23 that supports the closing plate 22 so as to be movable up and down. . The closing plate 22 is provided so as to close the lower end opening of the inclined charging pipe 19, and the connecting pipe 13 is provided with a third actuator 24 that moves the inclined charging pipe 19 in the axial direction. In the raw material supply apparatus 10 in this embodiment, the inclined actuator 19 is moved upward in the axial direction by the third actuator 24 as shown in FIG. 2, or the second actuator 23 as shown in FIG. Thus, the closing plate 22 that seals the lower end opening of the inclined charging pipe 19 is raised so that the closing plate 22 opens the lower end opening of the inclined charging pipe 19.

As shown in FIG. 3, the vertical injection pipe 20 includes a vertical main body portion 20a with a lower end portion closed and a guide portion 20b connected in parallel to the lower end portion of the main body portion 20a. The lower end portion of the main body 20a is a raw material depositing portion 20c for depositing the bulk raw material 26. The guide part 20b is a vertical pipe whose lower end is opened and whose upper end is closed, and is connected to a side surface of the main body part 20a via a discharge port 20d. Here, the lower end of the guide part 20b protrudes downward from the lower end of the raw material deposition part 20c. The raw material depositing portion 20c has a lower end surface swelled downward in a dome shape, deposits a predetermined amount of the bulk material 26 falling on the main body portion 20a, and passes the bulk material 26 falling over this from the discharge port 20d to the guide portion 20b. It is structured so that it can be discharged sequentially to the outlet. The reason why the lower end portion of the raw material deposition portion 20c is formed in a dome shape is to prevent breakage due to stress concentration between heat. That is, in the case of a square shape, there is a risk of breakage at the corner. The surface of the deposition material 26 in the material deposition unit 20c is an inclined surface that descends toward the discharge port 20d, and the inclination angle is a so-called repose angle. The distance L ₁ from the inclined surface to the upper end of the discharge port 20d and the diameter D ₁ of the discharge port 20d are equal to or larger than the inner diameter D ₀ of the vertical input tube 20 in order to smoothly flow out the raw material from the material deposition unit 20c to the guide unit 20b. Is set.

  The crucible 32 has a double structure in which an inner quartz crucible 32 a and an outer graphite crucible 32 b are combined, and a heat shielding member 36 is provided concentrically above the crucible 32. The raw material supply apparatus 10 according to the present embodiment inserts the vertical charging pipe 20 into the center of the crucible 32 through the inside of the heat shielding member 36 and then melts the raw material remaining in the crucible 32 through the vertical charging pipe 20. The bulk material 26 is supplied to the liquid 37.

Next, a raw material supply method using the raw material supply apparatus 10 configured as described above will be described.
In the single crystal pulling apparatus 30, a pull chamber (not shown) is connected to the top chamber 34, and the single crystal is pulled by a normal procedure. When the pulling of the single crystal is completed, the single crystal is pulled into the pull chamber, the gate valve 33 in the top chamber 34 is closed, and then the pull chamber is separated from the top chamber 34. While pulling a single crystal using a pull chamber (not shown), the raw material supply apparatus 10 of the present invention is fixed at a retracted position so as not to interfere with the pull chamber.

  When the pulling of the single crystal is completed and the pull chamber is separated, the raw material supply device 10 moves from the retracted position to the supply position on the single crystal pulling device 30. As a result, the second chamber 14 of the raw material supply apparatus 10 moves above the top chamber 34, and then the second chamber 14 is connected to the top chamber 34 as shown in FIG. When the connection between the second chamber 14 and the top chamber 34 is completed, the inside of the chamber of the raw material supply apparatus 10 is depressurized to the same pressure as in the single crystal pulling apparatus 30 and replaced with the same argon atmosphere. Then, the gate valve 33 in the top chamber 34 is opened. Thereby, the connection between the raw material supply apparatus 10 and the single crystal pulling apparatus 30 is completed.

  When the connection between the raw material supply apparatus 10 and the single crystal pulling apparatus 30 is completed, the vertical charging pipe 20 in the second chamber 14 is lowered. As a result, the vertical charging tube 20 is inserted into the center of the crucible 32 installed in the main chamber 31 of the single crystal pulling apparatus 30. Then, the tilting input pipe 19 is lowered in the axial direction by the third actuator 24, the lower end thereof is connected to the upper end of the vertical input pipe 20, and the setting of the vertical input pipe 20 is completed.

  After setting the vertical charging pipe 20 in this way, the bulk material 26 accommodated in the first hopper 15 in the first chamber 12 is cut out by a cut gate 15a by a predetermined amount (for example, 5 kg). The bulk material 26 cut out from the first hopper 15 is supplied to the third hopper 17 through the second hopper 15 and the quantitative cut-out feeder 18 at a predetermined speed (for example, 500 g / min). The bulk material 26 supplied to the third hopper 17 moves downward in the inclined charging pipe from the upper end of the inclined charging pipe 19 in accordance with the inclination, and the raw material is placed below the inclined charging pipe 19 closed by the closing plate 22. Temporarily damming. As a result, the kinetic energy that has been cut out and increased by moving the inside of the inclined charging pipe 19 to the lower end can be canceled once at the lower end.

  Next, as shown in FIG. 2, the lower side of the tilted charging pipe 19 closed by the closing plate 22 is opened by moving the tilted charging pipe 19 in the axial direction by the third actuator 24, and the lower part is dammed up. The stopped raw material 26 is guided to the upper part of the vertical charging pipe 20 and dropped onto the main body 20a. Since the raw material 26 is guided to the upper part of the vertical charging pipe 20 with zero kinetic energy, damage due to the raw material 26 interfering with the vertical charging pipe 20 can be avoided. At this time, it is preferable that the distance y for moving the inclined charging pipe 19 has a relationship of 1.5b <y <3.0b, where b is the average size of the raw materials 26. This is because the raw material 26 is not dropped when y is 1.5 b or less, and the apparatus itself is enlarged when y is 3.0 b or more.

As shown in FIG. 3, the bulk material 26 guided to the upper part of the vertical charging pipe 20 drops the main body part 20a and is deposited in a predetermined amount on the raw material accumulation part 20c. Sequentially flows from the outlet 20d to the guide portion 20b and is supplied to the crucible 32. By repeating this, a predetermined amount (for example, 100 kg) of bulk material 26 is added from the first hopper 15 in the material supply apparatus 10 to the residual liquid 37 in the crucible 32.
When the additional supply of the bulk material 26 is completed, the gate valve 33 is closed, the material supply device 10 is separated from the single crystal pulling device 30, and a pull chamber (not shown) is connected instead to perform the second pulling. As a result, a plurality of single crystals can be pulled up from the quartz crucible 32 that can be used only once, and the manufacturing cost of the pulled silicon single crystal can be reduced.

In the above-described embodiment, the case where a bulk material having a particle size of 30 mm or less is supplied has been described. However, the material to be supplied may be a bulk material exceeding 30 mm, and not a bulk material but a granular material. It may be.
Further, in the above-described embodiment, the case has been described in which the lower part of the tilted charging pipe 19 is opened by moving the tilted charging pipe 19 in the axial direction by the third actuator 24, but as shown in FIG. The lower part of the tilting pipe 19 closed by the closing plate 22 may be opened by moving the closing plate 22 upward by the second actuator 23. The distance x for raising the closing plate 22 at this time preferably has a relationship of 1.0b <x <2.5b, where b is the average size of the raw materials 26. This is because the raw material 26 is not dropped when x is 1.0 b or less, and the apparatus itself is enlarged when y is 2.5 b or more.

Next, the degree of damage to the vertical injection pipe due to the presence or absence of the closing plate was investigated.
<Example 1>
As shown in FIG. 4, a raw material supply apparatus 10 having an inclined charging pipe 19 made of quartz, a vertical charging pipe made of quartz, and a closing plate 22 made of quartz was prepared. The first hopper 15 in the raw material supply apparatus 10 is filled with 100 kg of bulk polycrystalline silicon raw material, the raw material 26 is cut out at a rate of about 10 kg / time by the cut gate 15a, the second hopper 15 and the quantitative cutout feeder 18 are cut out. Then, the third hopper 17 was introduced into the upper end of the tilting inlet pipe 19 in this order, and 10 kg of the raw material was temporarily dammed under the inclined inlet pipe 19 closed by the closing plate 22. Thereafter, the inclined charging pipe 19 is moved so as to rise in the axial direction, the lower part of the inclined charging pipe 19 closed by the closing plate 22 is opened, and the raw material 26 blocked by the lower part is placed on the upper part of the vertical charging pipe 20. The inside was dropped and supplied to the crucible 32. This was repeated 10 times to supply all of the 100 kg of raw material filled in the first hopper 15 to the crucible 32.

<Comparative Example 1>
The same raw material supply apparatus 10 as in Example 1 was prepared, and the closing plate 22 in the raw material supply apparatus 10 was maintained in a raised state as shown in FIG. 5, and the lower end opening of the inclined charging pipe 19 was opened. . In this state, the first hopper 15 is filled with 100 kg of massive polycrystalline silicon raw material, and the raw material 26 is cut out at a rate of about 10 kg / time by the cut gate 15a. The second hopper 15, the quantitative cut-out feeder 18, and the third The hopper 17 is introduced into the upper end of the inclined introduction pipe 19 in this order, and 10 kg of the raw material is moved obliquely downward inside the inclined introduction pipe 19 and is directly guided to the upper part of the vertical introduction pipe 20 without damming. , And supplied to the crucible 32. This was repeated 10 times to supply all of the 100 kg of raw material filled in the first hopper 15 to the crucible 32.

<Evaluation test and evaluation>
Each time 10 kg of the raw material is supplied to the crucible 32 once in each of Example 1 and Comparative Example 1, the raw material 26 interferes with the inner surface of the upper portion of the vertical input pipe facing the lower end of the inclined input pipe. The state of wear and breakage in the brazing part was visually observed. The results are shown in Table 1.

  As is apparent from the results in Table 1, in the case of Comparative Example 1 where the raw material is not dammed by the closing plate 22, the wear of the inner surface of the vertical input pipe advances with the increase of the number of cuts, and the cloudiness is completely observed in the sixth time Then, cracks occurred at the eighth time, and cracks at the interference site occurred at the tenth time. On the other hand, in the case of Example 1 in which the raw material was dammed at one end by the closing plate 22 to the lower part of the inclined charging pipe 19, significant interference between the raw material and the vertical charging pipe 20 was prevented, and no wear occurred. In addition, it is confirmed that the degree of wear of the vertical injection pipe below the closing plate 22 is also reduced compared to the case without the closing plate 22 due to the effect that the kinetic energy is reduced by discharging after damming once. It turns out that there is an effect.

It is the A section expanded sectional view of Drawing 4 showing the raw material supply device of the embodiment of the present invention. It is sectional drawing corresponding to FIG. 1 which shows the state which moved the inclination injection pipe and opened the lower end opening part. It is the B section expanded sectional view of Drawing 4. It is a block diagram which shows the whole structure of the raw material supply apparatus. It is sectional drawing which shows the state which raised the closing plate and open | released the lower end opening part of the inclination injection pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Raw material supply apparatus 15, 16, 17 Hopper 19 Inclined injection pipe 20 Vertical injection pipe 20c Deposition part 22 Closing plate 26 Raw material 30 Single crystal pulling apparatus 32 Crucible 37 Raw material melt

Claims (4)

A vertical feeding pipe (20) whose lower end faces the raw material melt (37) in the crucible (32) after pulling up the single crystal of the single crystal pulling device (30), and a lower end that is inclined at a predetermined angle An inclined inlet pipe (19) connected to the upper end of the inlet pipe (20), and a hopper (15, 16, 17) capable of supplying granular or massive raw material (26) to the upper end of the inclined inlet pipe (19). The raw material (26) supplied to the hopper (15, 16, 17) can be supplied to the raw material melt (37) through the inclined charging pipe (19) and the vertical charging pipe (20). In the raw material supply apparatus configured in
A closing plate for closing the lower end opening of the inclined charging pipe (19) so as to be openable and reducing damage to the vertical charging pipe (20) into which the raw material (26) flows from the inclined charging pipe (19) ( 22) A raw material supply apparatus characterized in that 22) is provided at an upper portion of the vertical charging pipe (20) . A predetermined amount of raw material (26) can be deposited on the lower end of the vertical injection pipe (20), and the lower end of the vertical injection pipe (20) is prevented from being worn and damaged, and the accumulation part (20c In the raw material melt (37) in the crucible (32), the vertical injection pipe (20) has a raw material (26) exceeding a predetermined amount of the raw material (26) deposited in the deposition part (20c). The raw material supply apparatus of Claim 1 comprised so that it might fall to.   The raw material supply device according to claim 1 or 2, wherein the lower end opening of the inclined charging pipe (19) is opened by the axial movement of the inclined charging pipe (19) or the raising of the closing plate (22).   The raw material supply apparatus according to any one of claims 1 to 3, wherein the closing plate (22) is made of the same material as the raw material (26) or a material having higher hardness than the raw material (26).

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