Silicon rod crushing method and apparatus, and method of producing silicon lumps

A silicon rod crushing method relatively moves an application position of high-voltage pulse discharge to a silicon rod in a longitudinal direction thereof while rotating the silicon rod to thereby crush the silicon rod.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method of producing silicon lumps as the raw material of a silicon single crystal by crushing a silicon rod and a silicon rod crushing apparatus.

Description of Related Art

Many silicon single crystals used as a substrate material for semiconductor devices are manufactured by the Czochralski method (CZ method). In the CZ method, polysilicon lumps filled in a quartz crucible is heated to generate a silicon melt. Then, a seed crystal is dipped into the silicon melt and slowly pulled up to grow a large single crystal at the lower end of the seed crystal.

Polysilicon lumps as the base material of a silicon single crystal are produced by crushing a high-purity polysilicon rod manufactured by a vapor phase growth method. Specifically, as a method of crushing the polysilicon rod, a method that throws a high-temperature polysilicon rod into water for rapid cooling to apply thermal shock thereto, a method that hits a polysilicon rod with a hammer or the like, and a method that crushes a polysilicon rod with a machine like a jaw crusher are generally used.

As a method of easily crushing the polysilicon rod, Japanese patent application Laid-open No. 2017-515774 describes a method that crushes a polysilicon rod by applying high-voltage pulse discharge thereto, in which the application position of the high-voltage pulse discharge is moved along the longitudinal direction of the polysilicon rod so as to efficiently crush the polysilicon rod over the entire length thereof.

Further, although not directly related to the polysilicon rod crushing method, Japanese patent application laid-open No. H11-47625 describes a method that applies high-voltage pulse discharge to a cylindrical object to be crushed made of reinforced concrete while rotating the object and moving the same in the longitudinal direction thereof.

However, in the polysilicon rod crushing method described in Japanese patent application laid-open No. 2017-515774, the application position of the high-voltage pulse discharge is merely moved along the longitudinal direction of the polysilicon rod, so that the polysilicon is finely crushed near an electrode applying the high-voltage pulse discharge, while it is coarsely crushed at larger distance from the electrode, resulting in a large variation in crushing size. Specifically, the polysilicon rod is finely crushed at its upper side near the electrode, while a large lump remains at the lower side far from the electrode, resulting in poor yield of polysilicon lumps having a size of about 10 mm to about 50 mm which is suitable for pulling-up of a single crystal according to the CZ method.

Further, in the conventional crushing method described in Japanese patent application laid-open No. H11-47625, a rotating device and a moving carriage for an object to be crushed are provided in water, so that when the object to be crushed is the polysilicon rod, the polysilicon lumps may be significantly contaminated by the rotating device and moving carriage. That is, the crushing method for the reinforced concrete cannot be simply applied to the polysilicon crushing method.

SUMMARY

The object of the present invention is therefore to provide a polysilicon rod crushing method and apparatus and a method of producing silicon lumps capable of improving the yield of silicon lumps of a size suitable for pulling-up of a silicon single crystal.

To solve the above problems, a silicon rod crushing method according to the present invention relatively moves an application position of high-voltage pulse discharge to a silicon rod in a longitudinal direction thereof while rotating the silicon rod to thereby crush the silicon rod.

According to the present invention, the application position of the high-voltage pulse discharge can be moved helically along the circumferential surface of the silicon rod, whereby high-voltage pulse power can be applied from substantially all directions of the circumferential surface of the silicon rod. Thus, the crushing size of the silicon can be made more uniform than in conventional crushing methods, allowing improvement in the yield of silicon lumps that can be used in a single crystal pulling-up process.

In the present invention, it is preferable that the silicon rod is placed on a looped endless sheet, and the endless sheet is rotated to rotate the silicon rod. In this case, it is preferable that the height position of one loop end of the endless sheet is made lower than the height position of the center of the silicon rod, and the silicon rod is rotated such that the application position of the high-voltage pulse discharge to the silicon rod goes toward the one loop end of the endless sheet. According to this method, it is possible to rotate the silicon rod at a fixed position while maintaining the horizontal attitude of the silicon rod and further to limit the landing location of silicon lumps falling downward.

In the present invention, it is preferable that the silicon rod is placed on a pair of parallel rollers, and the parallel rollers are rotated to rotate the silicon rod. Even with such a method, it is possible to rotate the silicon rod at a fixed position while maintaining the horizontal attitude of the silicon rod.

In the present invention, it is preferable that the silicon rod is housed in a container, at least two electrodes are provided near an outer peripheral surface of the silicon rod, and the electrodes are moved relative to the silicon rod to move the application position of high-voltage pulse discharge by the electrodes along the longitudinal direction of the silicon rod. According to this method, the application position of the high-voltage pulse discharge can be moved helically along the circumferential surface of the silicon rod, whereby high-voltage pulse power can be applied from substantially all directions of the circumferential surface of the silicon rod.

The silicon rod crushing method according to the present invention preferably houses the silicon rod in a container together with liquid, sets the silicon rod in the liquid, and moves at least one of the container and electrode pair relative to the silicon rod to move the application position of the high-voltage pulse discharge by the electrodes in the longitudinal direction of the silicon rod. This allows the silicon rod to be efficiently crushed.

The silicon rod crushing method according to the present invention preferably drives the endless sheet using a drive source provided outside the container. This makes it possible to crush the silicon to a uniform size while suppressing contamination of the icon rod as much as possible and thus to improve the yield of silicon lumps that can be used in a single crystal pulling-up process.

In the present invention, it is preferable that a plurality of collection containers are provided below the silicon rod so as to be arranged along the longitudinal direction of the silicon rod, and silicon lumps obtained by crushing the silicon rod are made to fall down into the collection containers. This allows the silicon lumps to be easily collected.

In the present invention, it is preferable that the collection containers are made of resin and have a structure having many holes or a mesh structure. Thus, the silicon lumps having a size equal to or larger than a certain value can be easily collected after completion of the crushing process, and the silicon lumps can be transferred to a washing process in a state of being put in the collection container and then be subjected to washing with hydrofluoric acid or nitrohydrofluoric acid.

A silicon rod crushing apparatus according to the present invention includes a container that houses therein a silicon rod, a rotary support mechanism that rotatably supports the silicon rod in the container, a high-voltage pulse discharge device that applies high-voltage pulse discharge to the silicon rod, and a moving mechanism that moves an application position of the high-voltage pulse discharge along a longitudinal direction of the silicon, rod relative to the silicon rod. The silicon rod crushing apparatus moves the application position of the high-voltage pulse discharge in the longitudinal direction of the silicon rod while rotating the silicon rod in the container to thereby crush the silicon rod.

According to the present invention, the application position of the high-voltage pulse discharge can be moved helically along the circumferential surface of the silicon rod, whereby high-voltage pulse power can be applied from substantially all directions of the circumferential surface of the silicon rod. Thus, the crushing size of the silicon can be made more uniform than in conventional crushing methods, allowing improvement in the yield of silicon lumps that can be used in a single crystal pulling-up process.

In the present invention, it is preferable that the rotary support mechanism includes a looped endless sheet, and the endless sheet is rotated in a state where the silicon rod is placed thereon to rotate the silicon rod. In this case, it is preferable that the rotary support mechanism further includes a first rotary shaft that supports one loop end of the endless sheet and a second rotary shaft that supports the other loop end of the endless sheet, the first rotary shaft is disposed in the container such that a height position of the one loop end of the endless sheet is lower than a height position of a center of the silicon rod, the second rotary shaft is disposed above the first rotary shaft such that a height position of the other loop end of the endless sheet is higher than the height position of the center of the silicon rod, and the silicon rod is rotated such that silicon lumps obtained by crushing the silicon rod due to application of the high-voltage pulse discharge are directed to the one loop end. With this configuration, it is possible to rotate the silicon rod at a fixed position while maintaining the horizontal attitude of the silicon rod and further to limit the landing location of silicon lumps falling downward.

In the present invention, it is preferable that the rotary support mechanism includes a pair of parallel rollers, and the parallel rollers are rotated with the silicon rod placed on the parallel rollers to rotate the silicon rod. Even with such a method, it is possible to rotate the silicon rod at a fixed position while maintaining the horizontal attitude of the silicon rod.

In the present invention, it is preferable that the high-voltage pulse discharge device has at least two electrodes disposed near an outer peripheral surface of the silicon rod, and the moving mechanism moves the container in the longitudinal direction of the silicon rod to move, relative to the silicon rod, the positions of the electrodes along the longitudinal direction of the silicon rod. With this configuration, the application position of the high-voltage pulse discharge can be moved helically along the circumferential surface of the silicon rod, whereby high-voltage pulse power can be applied from substantially all directions of the circumferential surface of the silicon rod.

In the present invention, it is preferable that a drive source for rotating the silicon rod is provided outside the container. This makes it possible to make the crushing size of the silicon while suppressing contamination of the silicon rod as much as possible and thus to improve the yield of silicon lumps that can be used in a single crystal pulling-up process.

It is preferable that the silicon rod crushing apparatus according to the present invention further includes a plurality of collection containers which are provided below the silicon rod so as to be arranged along the longitudinal direction of the silicon rod, and silicon lumps obtained by crushing the silicon rod are made to fall down into the collection containers.

In the present invention, it is preferable that the collection containers are made of resin and have a structure having many holes or a mesh structure. With this configuration, the silicon lumps having a size equal to or larger than a certain value can be easily collected after completion of the crushing process, and the silicon lumps can be transferred to a washing process in a state of being put in the collection container and then be subjected to washing with hydrofluoric acid or nitrohydrofluoric acid.

Further, a method of producing silicon lumps according to the present invention includes a step of producing a silicon rod and a step of crushing the silicon rod according to the above-described silicon rod crushing method according to the present invention.

According to the present invention, the application position of high-voltage pulse discharge can be moved helically along the circumferential surface of the silicon rod, whereby high-voltage pulse power can be applied from substantially all directions of the circumferential surface of the silicon rod. Thus, the crushing size of the silicon can be made more uniform than in conventional crushing methods, allowing improvement in the yield of silicon lumps that can be used in a single crystal pulling-up process.

In the present invention, the step of crushing the silicon rod preferably includes a step of making silicon lumps obtained by crushing the silicon rod fall down into collection containers. This allows the silicon lumps to be easily collected.

The method of producing silicon lumps according to the present invention preferably further includes a step of washing the silicon lumps housed in the collection containers with hydrofluoric acid or nitrohydrofluoric acid. This allows smooth transfer from the crushing step to the washing step.

According to the present invention, there can be provided a silicon rod crushing method and apparatus and a silicon lump producing method capable of improving the yield of silicon lumps of an adequate size while suppressing contamination as much as possible.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a schematic cross-sectional view illustrating the configuration of a silicon rod crushing apparatus1A according to a first embodiment of the present invention.FIG. 2is a schematic side view of the silicon rod crushing apparatus1A as viewed in the X-direction shown inFIG. 1.

As illustrated inFIGS. 1 and 2, the silicon rod crushing apparatus1A has a water tank10that houses a polysilicon rod2and liquid3, a rotary support mechanism20that rotatably supports the polysilicon rod2in the water tank10, a high-voltage pulse discharge device30that applies high-voltage pulse discharge to the polysilicon rod2, and a moving mechanism40that moves the water tank10forward and backward in the longitudinal direction thereof.

The polysilicon rod2(cut rod) is obtained by cutting a high-purity polysilicon manufactured by, e.g., a vapor phase growth method as the base material of a silicon single crystal into a predetermined length. The water tank10is a container having a sufficiently larger volume than the size of the polysilicon rod2and, when the water tank10is filled with the liquid3such as pure water, the polysilicon rod2in the water tank10is surrounded by the liquid3. As the water tank10and the liquid3to be used in the present embodiment, those having no possibility of contaminating the polysilicon rod2are preferably selected.

The rotary support mechanism20has a plurality of rotary shafts21ato21d, a looped endless sheet22wound on the rotary shafts21ato21d, and a drive source23such as a motor that drives/rotates at least one (in this example, rotary shaft21d) of the rotary shafts21ato21d. The polysilicon rod2is placed on the main surface of the endless sheet22stretched between the rotary shafts21aand21band supported by the endless sheet22so as to maintain its horizontal attitude in the water. The polysilicon rod2placed on the endless sheet22can be rotated at a fixed position by rotating the endless sheet22together with the rotary shafts21ato21d.

There is no particular restriction on the material of the endless sheet22as long as the polysilicon rod2can be rotatably supported and, for example, a polyurethane sheet can be used as the endless sheet22. Although the endless sheet22according to the present embodiment is a single sheet having a large width that covers substantially the entire length of the polysilicon rod2, it may be divided in the longitudinal direction of the polysilicon rod2into a plurality of sheets with a gap interposed between mutually adjacent sheets.

The height position of the rotary shaft21apositioned to the right of the polysilicon rod2inFIG. 1is preferably lower than the height position of the center of the polysilicon rod2. This allows the height position of one loop end22aof the endless sheet22to be lower than the center of the polysilicon rod2, allowing silicon lumps obtained by crushing the polysilicon rod2to fall below the polysilicon rod2.

On the other hand, the height position of the rotary shaft21dpositioned on the opposite side (left side inFIG. 1) of the rotary shaft21awith respect to the polysilicon rod2is preferably higher than the center of the polysilicon rod2and, more preferably, higher than the top of the water tank10. This allows the height position of the other loop end22bof the endless sheet22to be higher than the height position of the polysilicon rod2. In particular, the drive source23that drives/rotates the rotary shaft21dcan be disposed outside the water tank10, thereby making it possible to prevent contamination of the polysilicon rod2.

The rotary shafts21aand21bare immersed in the water, so that they are preferably made of a material having no possibility of contaminating the polysilicon rod2; however, taking mechanical strength into consideration, a metal material is preferably used. Thus, for example, it is preferable to constitute the center shaft of each of the rotary shafts21aand21bby metal such as stainless steel and to coat the exposed surface thereof with fluororesin.

In the present embodiment, the rotary shaft21cis disposed above the water surface; however, it may be immersed in the water. In this case, like the rotary shafts21aand21b, the rotary shaft21cis also preferably made of a material having no possibility of contaminating the polysilicon rod2and having high mechanical strength. There is no particular restriction on the number and positions of the rotary shafts as long as the endless sheet22can be driven/rotated, and various configurations may be adopted.

The high-voltage pulse discharge device30has high-voltage pulse oscillator31and at least two electrodes32connected to the high-voltage pulse oscillator31. The leading ends of the respective electrodes32are inserted into the water and are positioned near the upper outer peripheral surface of the horizontally-installed polysilicon rod2.

The high-voltage pulse discharge device30applies high-voltage pulse discharge several tens to several thousands of times during one rotation of the polysilicon rod2. When the high-voltage pulse discharge period is shortened, the crushing size of the polysilicon rod2can be made fine, while when the high-voltage pulse discharge period is prolonged, the crushing size can be made large. Voltage to be applied to the electrodes32is preferably 100 kV to 300 kV, and the frequency of the high-voltage pulse is preferably 0.5 Hz to 40 Hz.

The moving mechanism40has a support base41on which the water tank10and rotary support mechanism20are placed, a guide rail42that regulates the moving direction of the support base41, and a traveling mechanism43that drives the support base41. The guide rail42is laid in the longitudinal direction of the polysilicon rod2held in the water tank10.

In the present embodiment, the high-voltage pulse discharge device30is not moved together with the moving mechanism40but fixed in place. Thus, when the water tank10is slid together with the moving mechanism40, the positions of the electrodes32above the polysilicon rod2are relatively moved along the longitudinal direction of the polysilicon rod2.

When the rotary shafts21ato21dare disposed as described above, the polysilicon rod2is rotated clockwise. By thus rotating the polysilicon rod2such that the application position of the high-voltage pulse discharge above the polysilicon rod2goes toward the one loop end22aof the endless sheet22, the polysilicon lumps generated by crushing the polysilicon rod2at the upper outer periphery thereof can be made to fall immediately. At this time, the polysilicon lumps can be made to fall reliably since the rotary shaft21aand endless sheet22do not protrude laterally.

During the crushing process, the polysilicon rod2may be rotated counterclockwise on the endless sheet22. For example, when the raw material still keeps a rod shape as illustrated inFIG. 1, the polysilicon rod2is crushed while it is rotated counterclockwise together with the endless sheet22, and then the rotation direction of the endless sheet22is reversed to the clockwise direction after the polysilicon rod2is finely crushed to thereby make the crushed raw material fall down to a collection container side, thus allowing efficient collection of the crushed raw material. Further, when the endless sheet22is divided in the longitudinal direction into a plurality of sheets, the polysilicon rod2on the endless sheets22is crushed while it is rotated counterclockwise, and every time crushing in an area corresponding to the width of each sheet is completed, the endless sheet22is reversely rotated clockwise for collection of the fine raw materials.

In the present embodiment, a plurality of collection containers50are arranged along the longitudinal direction of the polysilicon rod2at the landing location of polysilicon lumps5. This allows the polysilicon lumps5obtained by crushing the polysilicon rod2through application of pulse power from one end to the other end thereof in the longitudinal direction of the polysilicon rod2, to be collected in the collection containers50. Further, the polysilicon lumps5can be subdivided in the early stage of the crushing process, thus simplifying quantitative distribution of the polysilicon lumps5. Each of the collection containers50preferably has a size capable of holding the polysilicon lumps5in an amount corresponding to about 5 kg to 10 kg.

In the present embodiment, the collection container50preferably has a structure having many holes or a mesh structure that allows no polysilicon lumps5to pass therethrough and allows liquid to pass therethrough. Further, the collection container50is preferably made of fluororesin. With this configuration, after the liquid3is drawn off from the water tank10after completion of the crushing process, or after overflowing dirty supernatant contaminated with floating silicon fragments, to clear it off, the polysilicon lumps5having a size equal to or larger than a certain value can be easily collected from the liquid, whereby the polysilicon lumps5can be transferred to a washing process in a state of being put in the collection container50and then be subjected to washing with hydrofluoric acid or nitrohydrofluoric acid.

FIGS. 3A and 3Bare views each schematically illustrating the positional relationship between the polysilicon rod2and electrodes32.FIG. 3Aillustrates a state before the water tank10is slid, andFIG. 3Billustrates a state after the water tank10is slid.

At the start of the crushing process of the polysilicon rod2, the water tank10is positioned at the right end side of the guide rail42as illustrated, e.g., inFIG. 3A, and the electrodes32are positioned at the left end side of the polysilicon rod2.

As illustrated inFIG. 3B, when the water tank10is moved to the left along the guide rail42, the polysilicon rod2is also moved together with the water tank10, and the electrodes32are moved to the right side of the polysilicon rod2. By thus relatively moving the electrodes32from one end to the other end in the longitudinal direction of the polysilicon rod2, the polysilicon rod2can be crushed over the entire length thereof.

When the polysilicon rod2is rotated at this time, the electrodes32can be moved helically along the circumferential surface of the polysilicon rod2, whereby high-voltage pulse power can be applied from substantially all directions of the circumferential surface of the polysilicon rod2. The polysilicon lumps5obtained by crushing the polysilicon rod2fall downward from the crushing position to be held in the collection containers50.

FIGS. 4A and 4Bare schematic views for explaining the relationship between the moving speed of the electrode32and the rotating speed of the polysilicon rod2.FIG. 4Aillustrates a case where the moving speed of the electrodes32is higher, or the rotating speed of the polysilicon rod2is lower, andFIG. 4Billustrates a case where the moving speed of the electrodes32is lower, or the rotating speed of the polysilicon rod2is higher.

As illustrated inFIG. 4A, when the moving speed of the electrodes32is higher than the rotating speed of the polysilicon rod2, a crushing period T of the polysilicon rod2is prolonged, so that the polysilicon lumps5having a comparatively large size can be obtained.

On the other hand, as illustrated inFIG. 4B, when the moving speed of the electrodes32is lower than the rotating speed of the polysilicon rod2, the crushing period T of the polysilicon rod2is shortened, so that the polysilicon lumps5having a comparatively small size can be obtained.

Thus, by adjusting the moving speed of the electrodes32along the longitudinal direction of the polysilicon rod2and the rotating speed of the polysilicon rod2, the acquisition rate of the polysilicon lumps of a size suitable for pulling-up of a silicon single crystal according to the CZ method can be improved.

As described above, the silicon rod crushing method according to the present embodiment moves the application position of the high-voltage pulse discharge in the longitudinal direction of the polysilicon rod2while rotating the polysilicon rod2in the water, thereby allowing high-voltage pulse power to be applied from substantially all directions of the circumferential surface of the polysilicon rod2. Therefore, it is possible to reduce a variation in the crushing size, i.e., to solve the conventional problem that the polysilicon rod2is finely crushed only at the upper side and coarsely crushed only at the lower side, whereby the polysilicon lumps of an adequate size can be produced.

FIG. 5is a schematic cross-sectional view illustrating the configuration of a silicon rod crushing apparatus according to a second embodiment of the present invention.

As illustrated inFIG. 5, a silicon rod crushing apparatus1B applies high-voltage pulse discharge through the electrodes32not from the upper side, but from the lateral side (in this example, from the right side inFIG. 5). According to the present embodiment, the polysilicon lumps5fall along the right side of the polysilicon rod2. Thus, the landing location of the polysilicon lumps5is limited to make it easy to collect the polysilicon lumps5.

FIG. 6is a schematic cross-sectional view illustrating the configuration of a silicon rod crushing apparatus according to a third embodiment of the present invention.

As illustrated inFIG. 6, in a silicon rod crushing apparatus10, only the endless sheet22supporting the polysilicon rod2exists in the water tank10, and six rotary shafts21ato21fare all disposed outside the water tank10. Thus, not only the rotary shaft21apositioned to the right of the polysilicon rod2, but also the rotary shaft21fpositioned to the left of the polysilicon rod2is disposed at a position higher than the center of the polysilicon rod2. Further, the height positions of respective loop ends22aand22bof the endless sheet22are higher than the height position of the polysilicon rod2. The endless sheet22entering the water tank10from the rotary shaft21aside reaches the rotary shaft21f, goes around the outside of the water tank10, and returns to the position of the rotary shaft21a. The drive source23drives the rotary shaft21dto thereby drive/rotate the endless sheet22.

In such a configuration, the polysilicon lumps5obtained by crushing remain on the endless sheet22and cannot be made to fall down to the bottom of the water tank10. Therefore, the collection containers50are not provided on the bottom of the water tank10. The polysilicon lumps5are raked and collected from the endless sheet22after the liquid3in the water tank is drawn off.

As described above, the endless sheet22may be divided in the longitudinal direction of the polysilicon rod2into a plurality of sheets. In this case, the polysilicon lumps5can be made to fall through a gap formed between mutually adjacent sheets to be collected in the collection containers50.

According to the present embodiment, the rotary shafts21ato21fthat may contaminate the polysilicon lumps5can be removed from the inside of the water tank10, allowing further improvement in the quality of the polysilicon lumps5.

FIG. 7is a schematic cross-sectional view illustrating the configuration of a silicon rod crushing apparatus according to a fourth embodiment of the present invention.FIG. 8is a schematic side view of the silicon rod crushing apparatus as viewed in the X-direction shown inFIG. 7.

As illustrated inFIGS. 7 and 8, in a silicon rod crushing apparatus1D according to the present embodiment, a pair of rollers25disposed parallel to each other directly support the polysilicon rod2. Therefore, the endless sheet22is not provided. At least one of the pair of rollers25is driven/rotated by the drive source23, whereby the polysilicon rod2is also rotated. Preferably, the drive source23is disposed outside the water tank10, and only the rollers25are disposed in the water tank10. Although details will be described later, with the silicon rod crushing apparatus1D according to the present embodiment, the electrodes32can be installed so as to sandwich the polysilicon rod2therebetween.

In order to prevent contamination of the polysilicon lumps5obtained by crushing the polysilicon rod2, the pair of rollers25are preferably made of stainless steel coated with fluororesin. By coating the rotary shaft made of the stainless steel with fluororesin, contamination of the polysilicon lumps5can be prevented.

FIG. 9is a schematic cross-sectional view illustrating the configuration of a silicon rod crushing apparatus according to a fifth embodiment of the present invention.

As illustrated inFIG. 9, in a silicon rod crushing apparatus1E, the pair of electrodes32are disposed so as to sandwich the polysilicon rod2therebetween. Other configurations are the same as those of the silicon rod crushing apparatus1D according to the fourth embodiment. When the pair of rollers25are used to support the polysilicon rod2from below as described above, the left and right spaces of the polysilicon rod2are opened, so that the electrodes32can be disposed there. In this case, it is possible to prevent the crushing size of the polysilicon rod2from being too small due to overconcentration of crushing energy.

As described above, the silicon rod crushing method according to the present embodiment moves the application position of the high-voltage pulse discharge in the longitudinal direction of the polysilicon rod2while rotating the polysilicon rod2in the water, so that it is possible to reduce a variation in the crushing size and thus to produce the polysilicon lumps5of an adequate size.

While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and various modifications may be made within the scope of the present invention, and all such modifications are included in the present invention.

For example, in the above embodiments described above, the polysilicon lumps5made to fall downward by crushing the polysilicon rod2are collected by the collection containers50; however, in the present invention, the provision of the collection containers50is not necessarily required. For example, the polysilicon lumps5made to fall downward by crushing the polysilicon rod2may be made to remain on the bottom surface of the water tank10, followed by raking and collection after drawing-off of the water from the water tank10.

Further, in the above embodiments, the polysilicon rod2is slid in the longitudinal direction thereof together with the water tank10to move the positions of the electrodes32relative to the polysilicon rod2; conversely, the electrodes32may be slid in the longitudinal direction of the polysilicon rod2with the position of the polysilicon rod2fixed.

Further, in the above embodiments, the polysilicon rod2is held in the water tank10together with the liquid3such as water and subjected to crushing in the liquid; however, in the present invention, the crushing of the polysilicon rod2may not necessarily be performed in the liquid, and may be performed in the air. Further, although the polysilicon rod is used as the raw material of the silicon lump in the above embodiments, a single crystal silicon rod may be used.