WO2013099365A1

WO2013099365A1 - Apparatus for refining semiconductor or metal

Info

Publication number: WO2013099365A1
Application number: PCT/JP2012/073283
Authority: WO
Inventors: 貴博中野; 健司和田; 佳彦永田
Original assignee: シャープ株式会社
Priority date: 2011-12-26
Filing date: 2012-09-12
Publication date: 2013-07-04
Also published as: JP5399465B2; JP2013133240A

Abstract

A cooling body (100) has a hollow rotating shaft section (120), and a hollow immersion section (110), which is a portion communicated with the rotating shaft section (120), and immersed in a molten semiconductor or a molten metal. The immersion section (110) is configured of a cylindrical circumferential side surface, and a bent bottom surface continuous from the circumferential side surface. Piping (130) for circulating a cooling fluid that cools the cooling body (100) is provided inside of the rotating shaft section (120). An outlet section (140), which is communicated with the piping (130), and which has a plurality of outlet ports (141) for blowing out the cooling fluid toward the inner surface of the immersion section (110), is provided on the inner side of the immersion section (110). The outlet ports (141) are positioned on the side surface and the bottom surface of the outlet section (140). A distance (L₂) between an upper end position of an upper end outlet port positioned at the top among the outlet ports (141) positioned on the side surface of the outlet section (140), and a lower end position of the immersion section (110) is equal to or shorter than half a distance (L₁) between an upper end position of the immersion section (110) and a lower end position of the immersion section (110).

Description

Semiconductor or metal purification equipment

The present invention relates to a semiconductor or metal purification apparatus.

Various types of materials are used industrially. Some materials exist in nature alone, such as oxygen and nitrogen, but most metal materials such as silicon exist in the form of compounds such as oxides or sulfides, and they exist in nature alone. It is rare.

Therefore, in order to obtain a specific metal element, it is necessary to reduce oxides or sulfides and remove impurities. Since various metal elements are used in various applications, a method for purifying the metal elements at low cost is required.

On the other hand, due to environmental problems, the use of natural energy is attracting attention as an alternative to fossil fuel energy such as oil. Solar cells that generate power using natural energy are actively introduced in Japan and Europe because they do not require large facilities and do not generate noise during operation.

In solar cells, new solar cells made of compound semiconductors such as cadmium tellurium are being developed. However, solar cells using crystalline silicon as a substrate currently occupy a large share in terms of the safety of the substance itself, past use results and price. Among them, the proportion of polycrystalline silicon solar cells manufactured from a polycrystalline silicon wafer (hereinafter also simply referred to as a wafer) is large.

There are roughly two types of wafers used for crystalline silicon solar cells: single crystal silicon wafers and polycrystalline silicon wafers. CZ (Czochralski) method and FZ (Floating Zone) method are generally used for the production of a single crystal silicon wafer.

The production of a polycrystalline silicon wafer includes a casting method in which a large polycrystalline lump is grown from molten silicon and then sliced to obtain a wafer, and a ribbon method in which a polycrystalline silicon wafer is directly grown from molten silicon. The ribbon method includes both a method using a substrate and a method not using a substrate. In addition, for the production of polycrystalline silicon, the shape is different from that of wafers, but as with wafers, silicon particles that are used as base materials for solar cells are produced by dropping silicon droplets in vacuum or in an inert gas. There is a spherical silicon method.

In the production of crystalline silicon wafers, ribbons and spherical silicon, molten silicon is almost always required, and most impurities such as metals adversely affect the characteristics of electronic devices. Therefore, silicon is not an example of the above-described metal element, and a method for purifying it inexpensively is required.

As one of the methods for purifying silicon, there is a metallurgical method using solidification segregation of impurities. This method is attracting attention because it may be able to remove impurities at a lower cost than gas phase methods such as the Siemens method and the fluidized bed method.

Hereinafter, a method for removing impurities will be described using silicon as an example. In the metallurgical method, impurities in silicon are classified into the following three types.
(1) Group III elements such as boron (hereinafter referred to as the first class).
(2) Group V elements such as phosphorus (referred to as the second class).
(3) Metal elements such as iron (referred to as the third class).

In the above-mentioned first and second types of impurities, since it is difficult to obtain the effect of removing impurities by segregation, the impurities are removed by oxidation treatment or vacuum heat treatment. For the third type of impurities, it is possible to reduce the impurity concentration basically by utilizing segregation at grain boundaries or segregation at the solid liquid interface.

For the first and second type impurities, it is necessary to add both elements in an appropriate ratio in order to determine the conductivity type (P type or N type) of the solar cell. About the 3rd type metal impurity, in order to prevent the fall of the photoelectric conversion efficiency of a solar cell, it is necessary to suppress as low a density | concentration as possible.

JP-A-2006-27940 (Patent Document 1) and JP-A-60-190531 disclose prior art documents that disclose a method or apparatus for removing a third type of impurity having an extremely small segregation coefficient such as metal. (Patent Document 2).

In the metal refining method described in Patent Document 1, a refined metal is deposited on the surface of a cooling body, and the metal is refined using a solidification segregation phenomenon.

A rotary cooling device for a high-purity aluminum production apparatus described in Patent Document 2 includes a cylindrical hollow rotary cooling body attached to the lower end of a hollow rotary shaft, a cooling fluid supply pipe disposed in the hollow rotary shaft, And a hollow cylindrical cooling fluid blowing member disposed in the hollow rotary cooling body and communicated with the cooling fluid supply pipe.

In the rotary cooling device for high-purity aluminum manufacturing equipment, the thickness of the bottom wall of the hollow rotary cooling body is made thicker than the thickness of the peripheral wall, so that the amount of heat transfer inside and outside through the bottom wall is reduced. Aluminum is not deposited on the outer surface, and a large number of cooling fluid outlets are uniformly distributed on the peripheral wall of the cooling fluid outlet member.

JP 2006-27940 A JP-A-60-190531

In the metal refining method or apparatus described in Patent Documents 1 and 2, the impurity concentration of the purified metal deposited on the cooling body may be significantly lower than the impurity concentration of the molten metal before purification by solidification segregation. it can.

In the purification of semiconductors or metals, it is desired to purify more weight in a short time. Therefore, further increase in the recovered weight of the purified semiconductor or purified metal has been demanded.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a purification apparatus capable of pulling up and collecting more refined semiconductors or refined metals.

A semiconductor or metal refining apparatus according to the first aspect of the present invention includes a crucible for melting a semiconductor or metal therein, and cooling in a state of being rotationally driven by being immersed in the molten semiconductor or molten metal melted in the crucible. And a hollow cooling body that precipitates a refined semiconductor or refined metal in which impurities are reduced by solidifying and segregating the melted semiconductor or melted metal on the outer surface. The cooling body has a hollow rotating shaft portion and a hollow immersion portion that is in contact with the rotating shaft portion and is immersed in the molten semiconductor or molten metal. A pipe for passing a cooling fluid for cooling the cooling body is provided inside the rotating shaft. Inside the immersion part, there is provided a blowout part having a plurality of outlets that communicate with the piping and blow out the cooling fluid toward the inner surface of the immersion part. The plurality of air outlets are located on the side surface and the bottom surface of the air outlet. The distance between the upper end position of the uppermost blower outlet located at the uppermost position and the lower end position of the immersion part among the plurality of outlets located on the side surface of the blowout part is the upper end position of the immersion part and the lower end position of the immersion part. Is less than half compared to the distance between.

The semiconductor or metal refining device according to the second aspect of the present invention includes a crucible for melting the semiconductor or metal therein, and cooling in a rotationally driven state immersed in the molten semiconductor or molten metal melted in the crucible. And a cooling body for precipitating a refined semiconductor or refined metal in which impurities are reduced by solidifying and segregating the melted semiconductor or melted metal on the outer surface. The cooling body has a rotating shaft portion and an immersion portion that is in communication with the rotating shaft portion and is immersed in a molten semiconductor or a molten metal. The immersion part is composed of a cylindrical peripheral side surface and a curved bottom surface that is continuous with the peripheral side surface.

A semiconductor or metal refining device according to a third aspect of the present invention includes a crucible for melting a semiconductor or metal therein, and cooling in a rotationally driven state immersed in the molten semiconductor or molten metal melted in the crucible. And a hollow cooling body that precipitates a refined semiconductor or refined metal in which impurities are reduced by solidifying and segregating the melted semiconductor or melted metal on the outer surface. The cooling body has a hollow rotating shaft portion and a hollow immersion portion that is in communication with the rotating shaft portion and is immersed in the molten semiconductor or molten metal. The immersion part is composed of a cylindrical peripheral side surface and a curved bottom surface that is continuous with the peripheral side surface. A pipe for passing a cooling fluid for cooling the cooling body is provided inside the rotating shaft. Inside the immersion part, there is provided a blowout part having a plurality of outlets that communicate with the piping and blow out the cooling fluid toward the inner surface of the immersion part. The plurality of air outlets are located on the side surface and the bottom surface of the air outlet. The distance between the upper end position of the uppermost blower outlet located at the uppermost position and the lower end position of the immersion part among the plurality of outlets located on the side surface of the blowout part is the upper end position of the immersion part and the lower end position of the immersion part. Is less than half compared to the distance between.

In one form of this invention, the bottom face of the immersion part is comprised by a part of spherical surface.
In one embodiment of the present invention, the semiconductor or the metal is silicon.

In one embodiment of the present invention, the cooling body is made of graphite.

According to the present invention, more refined semiconductors or refined metals can be pulled up and collected.

It is a partial cross section figure which shows the structure of the cooling body in the refiner | purifier of the semiconductor or metal which concerns on one Embodiment of this invention. It is a partial cross section figure which shows the structure of the cooling body which concerns on Example 2 of this invention. It is a partial cross section figure which shows the structure of the cooling body which concerns on Example 3 of this invention. 10 is a partial cross-sectional view illustrating a configuration of a cooling body according to Comparative Example 2. FIG. In the silicon | silicone refinement | purification apparatus which concerns on the comparative example 1, it is a partial cross section figure which shows the state which immerses a cooling body in molten silicon. In the refiner | purifier of the silicon | silicone which concerns on the comparative example 1, it is sectional drawing which shows the state which has refined silicon deposited on the surface of the cooling body immersed in molten silicon. In the refiner | purifier of the silicon | silicone which concerns on the comparative example 1, it is sectional drawing which shows the state which pulled up the cooling body from molten silicon. FIG. 4 is a side view showing the shape of precipitated purified silicon in the silicon purification apparatus according to Comparative Example 1.

The present inventors tried to increase the recovered weight of the refined semiconductor or refined metal through various evaluations and considerations. Hereinafter, evaluation and consideration in Comparative Example 1 of a semiconductor or metal purification apparatus performed using a cooling body having a structure equivalent to that of the rotary cooling apparatus described in Patent Document 2 will be described. In Comparative Example 1, silicon was used as an example of a semiconductor or metal.

(Comparative Example 1)
FIG. 5 is a partial cross-sectional view showing a state in which a cooling body is immersed in molten silicon in the silicon purification apparatus according to Comparative Example 1. In addition, in FIG. 5, the inside of the cooling body 300 is not illustrated.

As shown in FIG. 5, the silicon purification apparatus according to Comparative Example 1 includes a crucible 20 that melts silicon inside and a hollow cooling body 300.

Depending on the type of semiconductor or metal to be purified, various materials such as graphite, silica, quartz, silicon carbide, alumina, mullite, iron, stainless steel, or copper can be used as the material of the crucible 20. When the semiconductor or metal to be purified is silicon, graphite, silica, quartz, silicon carbide, alumina, mullite, or the like can be used. However, graphite, silica, quartz, or silicon carbide is preferable as the material of the crucible 20 in order to suppress the entry of impurities from the crucible 20 into the silicon.

The cooling body 300 has a hollow rotating shaft portion 320 and a hollow immersion portion 310 that is in communication with the rotating shaft portion 320 and is immersed in the molten silicon 10. In Comparative Example 1, the immersion part 310 has a tapered outer shape with a tapered tip and a flat surface at the tip.

The material of the cooling body 300 must be selected according to the semiconductor or metal to be purified, and graphite is preferable when the semiconductor or metal to be purified is silicon.

A pipe (not shown) through which a cooling fluid for cooling the cooling body 300 flows is provided inside the rotary shaft portion 320. Inside the immersion part 310, there is provided a blow-out part (not shown) that communicates with the pipe and has a plurality of outlets for blowing a cooling fluid toward the inner surface of the immersion part 310. The plurality of outlets are uniformly positioned on the side surface of the outlet. For example, graphite can be used as the material of the pipe and the blowout part.

The crucible 20 is accommodated in the chamber 30. An opening 32 that allows the cooling body 300 to move in and out of the chamber 30 is provided in the upper portion of the chamber 30. The inner space 31 of the chamber 30 is filled with an inert gas such as helium, argon or nitrogen. A heater (not shown) is disposed around the crucible 20 in the chamber 30.

FIG. 6 is a cross-sectional view showing a state in which purified silicon is deposited on the surface of a cooling body immersed in molten silicon in the silicon purification apparatus according to Comparative Example 1.

As shown in FIG. 6, the cooling body 300 is immersed in the molten silicon 10 melted in the crucible 20 and cooled in a rotationally driven state, so that the molten silicon 10 is solidified and segregated to reduce impurities. Purified silicon 40 is deposited on the outer surface.

Specifically, the cooling body 300 is cooled by blowing an inexpensive refrigerant having a high thermal conductivity such as nitrogen as a cooling fluid from the outlet of the outlet through the pipe. Since the blower outlet is provided uniformly on the side surface of the blowout part, the entire side surface of the immersion part 310 is cooled. On the other hand, since the blowout port is not provided on the bottom surface of the immersion part 310, the bottom surface of the immersion part 310 is not cooled compared to the side surface.

Further, the cooling body 300 is rotationally driven around a line 300 a that is orthogonal to the horizontal section of the immersion part 310 and passes through the center of the outer shape of the immersion part 310.

FIG. 7 is a cross-sectional view showing a state in which the cooling body is pulled up from the molten silicon in the silicon purification apparatus according to Comparative Example 1. As shown in FIG. 7, the cooling body 300 with the purified silicon 40 deposited on the surface is pulled up above the molten silicon 10.

FIG. 8 is a side view showing the shape of precipitated purified silicon in the silicon purification apparatus according to Comparative Example 1. As shown in FIG. 8, the purified silicon 40 deposited on the surface of the cooling body of Comparative Example 1 has a wide portion 41 formed so as to protrude at the upper end portion, and a corner portion around the tip of the immersion portion 310 at the lower end portion. And the formed thin portion 42. The thickness of the thin portion 42, and W _s.

The reason why the wide portion 41 is formed is that the temperature near the liquid surface of the molten silicon 10 is lower than the temperature inside the molten silicon 10, and the precipitation rate of the purified silicon near the liquid surface of the molten silicon 10 is different. This is probably because it is faster than the part.

The reason why the thin-walled portion 42 is formed is that the bottom surface of the immersion portion 310 is not provided with an air outlet, so that the temperature of the bottom surface of the immersion portion 310 is higher than that of the side surface, and the purified silicon 40 is deposited on the bottom surface of the immersion portion 310. This is because the speed is slower than the deposition speed of the purified silicon 40 deposited on the side surface of the immersion part 310.

In the wide part 41, when the cooling body 300 was pulled up, it collided with the opening 32, and the impact caused a phenomenon that the whole or part of the purified silicon 40 was broken and dropped. Further, since the thickness of the refined silicon 40 is greatly changed locally in the thin portion 42, the refined silicon 40 is liable to crack, and when the cooling body 300 is pulled up, the crack progresses and the refined silicon 40 as a whole. Or there was a phenomenon that a part of it dropped.

When the whole or a part of the purified silicon 40 falls, the amount of the purified silicon 40 recovered is reduced. In addition, since it is necessary to re-melt the purified silicon 40 that has fallen into the molten silicon 10, the amount of recovered purified silicon 40 per hour is further reduced.

(Examination example for Comparative Example 1)
In order to suppress the above-described falling phenomenon, the present inventors tried the examination plans 1 and 2. Study plan 1 is to shorten the deposition time of the purified silicon 40. Study plan 2 is to keep the temperature of the molten silicon 10 high.

In Study Plan 1, formation of the wide portion 41 was suppressed, and the occurrence of collision between the wide portion 41 and the opening 32 was reduced. However, the thickness of the thin portion 42 is further reduced, and the occurrence of cracks in the thin portion 42 is increased. As a result, the frequency of occurrence of falling purified silicon 40 was not reduced. Further, the amount of purified silicon 40 that can be recovered by one purification is reduced.

Also in the examination plan 2, formation of the wide part 41 was suppressed, and the occurrence of collision between the wide part 41 and the opening 32 was reduced. However, the thickness of the thin portion 42 is further reduced, and the occurrence of cracks in the thin portion 42 is increased. As a result, the frequency of occurrence of falling purified silicon 40 was not reduced. Moreover, the precipitation time of the purified silicon 40 is required to be long, and the recovered amount of the purified silicon 40 per hour is reduced.

From the above examination results, it was found that further improvement of the purification apparatus is necessary in order to increase the recovered weight of the purified silicon.

(Evaluation and discussion)
As a result of various evaluations and considerations, the inventors of the present invention can reduce the above-described dropping phenomenon by changing the arrangement of the outlet in the outlet and the outer shape of the immersion part of the cooling body. I found.

Specifically, by disposing the outlet on the lower side and the bottom surface of the side surface of the blowout part, the precipitation rate of the purified silicon 40 in the vicinity of the liquid surface of the molten silicon 10 is reduced and the formation of the wide part 41 is suppressed. The present inventors have found that the formation rate of the thin-walled portion 42 can be suppressed by increasing the deposition rate of the purified silicon 40 deposited on the bottom surface of the immersion portion 310.

Further, by forming the outer shape of the immersion part of the cooling body from a cylindrical peripheral side surface and a curved bottom surface that is continuous with the peripheral side surface, the formation of the thin portion 42 around the corner of the tip of the immersion part is suppressed. I found out that I can do it.

As a result of separately measuring and evaluating the impurity concentration of the purified silicon deposited on each of the peripheral side surface and the bottom surface, there was no significant difference between the impurity concentrations of both, and both had sufficient solidification segregation effects. It was confirmed that it was obtained.

This is thought to be because the peripheral speed due to the rotation of the cooling body could be secured even at the bottom surface of the immersion part by forming the bottom surface of the immersion part into a curved surface. As a result, segregation due to the rotation of the cooling body. It is presumed that the effect of increasing the coefficient could be obtained on the bottom surface of the immersion portion as well as the side surface of the immersion portion.

The present invention has been made based on the above evaluation and consideration.
Hereinafter, a semiconductor or metal purification apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

In the semiconductor or metal refining apparatus according to this embodiment, only the configuration of the cooling body is different from that of Comparative Example 1, and therefore, description of other configurations will not be repeated.

FIG. 1 is a partial cross-sectional view showing a configuration of a cooling body in a semiconductor or metal purification apparatus according to an embodiment of the present invention. In addition, in FIG. 1, the piping 130 and the blowing part 140 which flow a cooling fluid have shown the state of side view.

As shown in FIG. 1, the cooling body 100 has a hollow rotary shaft portion 120 and a hollow immersion portion 110 that is in communication with the rotary shaft portion 120 and is immersed in a molten semiconductor or molten metal. is doing. The immersion part 110 is composed of a cylindrical peripheral side surface and a curved bottom surface that is continuous with the peripheral side surface. In the present embodiment, the bottom surface of the immersion part 110 is constituted by a part of a spherical surface. By constituting the bottom surface of the immersion part 110 with a part of the spherical surface, the molten silicon 10 can be more uniformly stirred on the bottom surface of the immersion part 110 when the cooling body 100 is rotated.

Inside the rotating shaft portion 120, a pipe 130 for allowing a cooling fluid for cooling the cooling body 100 to flow is provided. Inside the immersion part 110, there is provided a blowing part 140 having a plurality of outlets 141 that communicate with the pipe 130 and blow the cooling fluid toward the inner surface of the immersion part 110. The cooling fluid sprayed on the inner surface of the immersion part 110 flows between the pipe 130 and the rotary shaft part 120 and is collected.

The blow-out part 140 has a cylindrical outer shape whose bottom is closed. As shown in FIG. 1, chamfering may be performed on a corner portion on the lower end side of the blowing portion 140. Moreover, the blowing part 140 may have a tapered part on the peripheral side surface that gradually becomes larger in diameter from the lower end in a cross-sectional view.

In the present embodiment, the plurality of air outlets 141 are located on the side surface and the bottom surface of the air outlet 140. The distance L ₂ between the upper end position of the uppermost upper outlet located among the plurality of outlets 141 located on the side surface of the outlet part 140 and the lower end position of the immersion part 110 is the upper end position of the immersion part 110. Compared to the distance L ₁ between the lower end position of the immersion part 110 and less than half.

As the shape of the outlet 141, various shapes such as a circular shape, an elliptical shape, a polygonal shape, or a slit shape can be adopted, but in the present embodiment, the shape is a circular shape.

Further, the opening area per one outlet 141 is preferably 0.5% or more and 2% or less with respect to the flow area of the cross section of the pipe 130, for example.

Furthermore, it is desirable to arrange the outlets 141 so that the position distribution is not locally biased. For example, in a divided piece obtained by dividing the blowing portion 140 into two planes in an arbitrary plane that includes the rotation center axis of the cooling body 100 and is parallel to the rotation axis direction of the cooling body 100, the divided piece having the smaller outlet 141. It is desirable that the opening areas of all the outlets 141 occupy in the range of 1/3 or more and ½ or less of the opening areas of all the outlets 141 occupying the entire blowing part 140.

With the above configuration, the refined semiconductor or refined metal deposited on the bottom surface of the immersion part 110 is suppressed by reducing the deposition rate of the refined semiconductor or refined metal in the vicinity of the liquid surface of the melted semiconductor or melted metal to suppress the formation of the wide portion 41. It is possible to suppress the formation rate of the thin-walled portion 42 around the corner portion at the tip of the immersion portion 110 by increasing the deposition rate.

As a result, the refined semiconductor or refined metal deposited on the surface of the cooling body 100 can be recovered while suppressing reduction due to falling, and the recovered weight of the refined semiconductor or refined metal can be increased.

In the present embodiment, the immersion part 110 has a cylindrical peripheral side surface. For example, a tapered part having a gradually increasing diameter from the lower part to the upper part in a sectional view is provided on the peripheral side surface. You may have. Further, the bottom surface of the immersion part 110 may be a flat surface instead of a curved surface. Furthermore, the structure of the cooling body 100 is not limited to the above. For example, the cooling body may be cooled by bringing a cooling component such as a water cooling plate into contact with the upper side of the solid cooling body. Also in this case, the formation of the wide portion 41 can be suppressed, and the recovered weight of the purified semiconductor or purified metal can be increased.

Alternatively, the air outlet 141 may be evenly disposed on the entire side surface and bottom surface of the air outlet 140. In this case, the formation of the thin portion 42 can be suppressed, and the recovered weight of the purified semiconductor or purified metal can be increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although silicon is purified in the embodiments, the present invention is not limited to silicon and can be applied to the purification of semiconductors or metals.

(Example 1)
In Example 1, 430 kg of silicon was charged into a crucible 20 made of isotropic graphite having an outer diameter of 630 mm and melted. The temperature of the molten silicon 10 was kept at the melting point of silicon + 10 ° C.

As shown in FIG. 1, the cooling body 100 of the present embodiment has a rotating shaft portion 120 and an immersion portion 110, and the immersion portion 110 has a cylindrical peripheral side surface and a spherical surface continuous with the peripheral side surface. It is comprised from the bottom face comprised from the part. The size of the immersion part 110 was such that the cylindrical diameter on the peripheral side surface was 200 mm, and the distance L ₁ between the upper end position of the immersion part 110 and the lower end position of the immersion part 110 was 500 mm.

Also, 48 outlets 141 having a hole diameter of 5 mm were provided on the side surface of the outlet 140 and 9 locations on the bottom surface. The intervals between the adjacent outlets 141 were all equal. A distance L ₂ between the upper end position of the uppermost outlet and the lower end position of the immersion part 110 among the plurality of outlets 141 located on the side surface of the outlet part 140 was set to 250 mm. The blowing part 140 was formed from isotropic graphite.

As indicated by an arrow 50 in FIG. 1, the molten silicon is rotated for 17 minutes while rotating the cooling body 100 at a rotation speed of 30 rotations / minute with nitrogen gas flowing through the pipe 130 at a flow rate of 6000 L / minute. The immersion part 110 was immersed in 10 and the purified silicon 40 was deposited.

After the cooling body 100 was pulled up from the molten silicon 10, the purified silicon 40 was peeled off from the cooling body 100, and the purified silicon 40 was recovered.

Hereinafter, a series of operations from precipitation to collection of the purified silicon 40 will be referred to as purification operations. This purification operation was performed a plurality of times, and each time the recovered amount of the purified silicon 40 reached 160 kg, the same amount of solid silicon was replenished into the crucible 20 and melted. The above refining operation was repeated 229 times while appropriately replenishing the solid silicon.

(Example 2)
FIG. 2 is a partial cross-sectional view showing the configuration of the cooling body according to the second embodiment of the present invention. In addition, in FIG. 2, the piping 130 and the blowing part 140 which flow a cooling fluid have shown the state of side view.

As shown in FIG. 2, the cooling body 200 includes a rotating shaft part 220 and an immersion part 210, and the immersion part 210 includes a cylindrical peripheral side surface and a bottom surface formed of a flat surface continuous with the peripheral side surface. Has been. The thickness of the bottom surface of the immersion part 210 was doubled compared to the thickness of the side surface.

The other conditions were the same as in Example 1, and the refining operation was repeated 229 times while appropriately replenishing solid silicon.

Example 3
FIG. 3 is a partial cross-sectional view showing the configuration of the cooling body according to the third embodiment of the present invention. In addition, in FIG. 3, the piping 230 and the blowing part 240 which flow a cooling fluid have shown the state of side view.

As shown in FIG. 3, in the blowing unit 240 of the present embodiment, the plurality of outlets 241 are located only on the entire side surface of the blowing unit 240. The distance L ₃ between the upper end position of the uppermost outlet and the lower end position of the immersion part 210 among the plurality of outlets 241 located on the side surface of the outlet part 240 is the upper end position of the immersion part 210. Compared to the distance L ₁ between the lower end position of the immersion part 210 and larger than half. Specifically, the distance L ₃ was 400 mm.

In addition, 57 outlets 241 with a hole diameter of 5 mm were provided on the side of the outlet 140. The intervals between the adjacent outlets 241 were all equal. The blowing part 240 was formed from isotropic graphite.

The other conditions were the same as in Example 1, and the refining operation was repeated 165 times while appropriately replenishing solid silicon.

(Comparative Example 2)
FIG. 4 is a partial cross-sectional view illustrating a configuration of a cooling body according to Comparative Example 2. In addition, in FIG. 4, the piping 230 and the blowing part 240 which flow a cooling fluid have shown the state of side view.

As shown in FIG. 4, in the comparative example 2, the cooling body 200 has the rotating shaft part 220 and the immersion part 210, and the immersion part 210 is a flat surface continuous with the cylindrical peripheral side surface and the peripheral side surface. It is comprised from the bottom which consists of. The thickness of the bottom surface of the immersion part 210 was doubled compared to the thickness of the side surface.

In the blowing part 240, the plurality of outlets 241 are located only on the entire side surface of the blowing part 240. The distance L ₃ between the upper end position of the uppermost outlet and the lower end position of the immersion part 210 among the plurality of outlets 241 located on the side surface of the outlet part 240 is the upper end position of the immersion part 210. Compared to the distance L ₁ between the lower end position of the immersion part 210 and larger than half. Specifically, the distance L ₃ was set to 400 mm.

The other conditions were the same as in Example 1, and the refining operation was repeated 87 times while appropriately replenishing solid silicon.

(Comparison between Examples and Comparative Example 2)
In each of Examples 1 to 3 and Comparative Example 2 above, the average thickness of the purified silicon 40 deposited on the peripheral side surface of the immersion part, the average thickness of the purified silicon 40 deposited on the bottom surface of the immersion part, and the immersion part The difference between the average thickness of the purified silicon 40 deposited on the peripheral side surface and the average thickness of the purified silicon 40 deposited on the bottom surface of the immersion portion was determined. Moreover, the incidence rate of the falling phenomenon of the purified silicon 40 and the recovery amount of the purified silicon 40 per dipping process were calculated. Further, the Fe concentration in the purified silicon deposited on the bottom surface of the immersion part and the Fe concentration in the purified silicon deposited on the peripheral side surface of the immersion part were measured.

Table 1 summarizes the above data.

As shown in Table 1, compared with Comparative Example 2, in Example 2 and Example 3, the difference in average thickness of purified silicon 40 deposited on the peripheral side surface and the bottom surface of the immersion part was reduced. . That is, the local thickness change of the purified silicon 40 was reduced. Moreover, the incidence rate of the dropping phenomenon of the purified silicon 40 was also reduced. From this result, formation of the wide part 41 or the thin part 42 is suppressed by having either the arrangement of the outlet 141 in the outlet part 140 according to this embodiment and the outer shape of the immersion part 110, and purified silicon. It was confirmed that a recovery weight of 40 could be increased.

Further, in Example 1, compared with Comparative Example 2, the difference in average thickness of the purified silicon 40 deposited on the peripheral side surface and the bottom surface of the immersion part is further reduced, and the occurrence rate of the dropping phenomenon of the purified silicon 40 is further increased. It was reduced. Therefore, by having both the arrangement of the outlet 141 in the outlet 140 and the outer shape of the immersion part 110 according to the present embodiment, the formation of the wide part 41 and the thin part 42 is suppressed, and the purified silicon 40 is made efficient. It was confirmed that it could be purified well.

Furthermore, it was confirmed that in any of Examples 1 to 3, the recovered amount of purified silicon 40 per dipping process was improved as compared with Comparative Example 2. In Example 2 and Comparative Example 2, the Fe concentration in the purified silicon on the bottom surface is higher than that on the peripheral side surface of the immersion part, whereas in Example 1 and Example 3, the peripheral side surface of the immersion part is It was confirmed that there was no difference in Fe concentration in the purified silicon between the bottom surface and the bottom surface.

The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. 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.

10 molten silicon, 20 crucible, 30 chamber, 31 inner space, 32 opening, 40 purified silicon, 41 wide part, 42 thin part, 100, 200, 300 cooling body, 110, 210, 310 immersion part, 120, 220, 320 Rotating shaft, 130, 230 piping, 140, 240 outlet, 141, 241 outlet.

Claims

A crucible (20) for melting a semiconductor or metal therein;
A refined semiconductor or refined metal in which impurities are reduced by solidifying and segregating the melted semiconductor or melted metal by being immersed in a molten semiconductor or melted metal melted in the crucible (20) and being driven to rotate. A hollow cooling body (100, 200) that deposits on the outer surface,
The cooling body (100, 200) is a hollow rotating shaft portion (120, 220) and a hollow portion that is in contact with the rotating shaft portion (120, 220) and is immersed in a molten semiconductor or a molten metal. Having a shaped immersion part (110, 210),
Pipes (130, 230) for passing a cooling fluid for cooling the cooling body (100, 200) are provided inside the rotating shaft portion (120, 220),
A plurality of outlets (141, 141) that communicate with the pipe (130, 230) inside the immersion part (110, 210) and blow out the cooling fluid toward the inner surface of the immersion part (110, 210). 241) is provided with outlets (140, 240),
The plurality of outlets (141, 241) are located on the side and bottom of the outlet (140, 240),
The upper end position of the uppermost outlet and the lower end position of the immersion part (110, 210) among the plurality of outlets (141, 241) located on the side surface of the outlet (140, 240) The semiconductor or metal purifier is a half or less of the distance between the upper end position of the immersion part (110, 210) and the lower end position of the immersion part (110, 210).
A crucible (20) for melting a semiconductor or metal therein;
A refined semiconductor or refined metal in which impurities are reduced by solidifying and segregating the melted semiconductor or melted metal by being immersed in a molten semiconductor or melted metal melted in the crucible (20) and being driven to rotate. And a cooling body (100) for depositing on the outer surface,
The cooling body (100) has a rotating shaft portion (120), and an immersion portion (110) that is a portion that is in communication with the rotating shaft portion (120) and is immersed in a molten semiconductor or a molten metal,
The immersion unit (110) is a semiconductor or metal refining device that includes a cylindrical peripheral side surface and a curved bottom surface that is continuous with the peripheral side surface.
A crucible (20) for melting a semiconductor or metal therein;
A refined semiconductor or refined metal in which impurities are reduced by solidifying and segregating the melted semiconductor or melted metal by being immersed in a molten semiconductor or melted metal melted in the crucible (20) and being driven to rotate. A hollow cooling body (100) for depositing on the outer surface,
The cooling body (100) includes a hollow rotary shaft portion (120) and a hollow immersion portion (110) that is in communication with the rotary shaft portion (120) and is immersed in a molten semiconductor or a molten metal. )
The immersion part (110) is composed of a cylindrical peripheral side surface and a curved bottom surface continuous with the peripheral side surface,
A pipe (130) through which a cooling fluid for cooling the cooling body (100) flows is provided inside the rotating shaft portion (120),
A blowout part (140) having a plurality of outlets (141) that communicate with the pipe (130) and blow out the cooling fluid toward the inner surface of the immersion part (110) inside the immersion part (110). )
The plurality of outlets (141) are located on the side and bottom of the outlet (140),
The distance between the upper end position of the uppermost outlet and the lower end position of the immersion part (110) among the plurality of outlets (141) located on the side surface of the outlet (140) is: A semiconductor or metal refining apparatus, which is less than half the distance between the upper end position of the immersion part (110) and the lower end position of the immersion part (110).
The semiconductor or metal purifier according to claim 2 or 3, wherein the bottom surface of the immersion part (110) is constituted by a part of a spherical surface.
The semiconductor or metal purification apparatus according to any one of claims 1 to 4, wherein the semiconductor or the metal is silicon.
The semiconductor or metal purifier according to claim 5, wherein the cooling body is formed of graphite.