JP2012017998A - Polycrystalline silicon rod, inspection method of polycrystalline silicon rod, and manufacturing method of polycrystalline silicon rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high quality polycrystalline silicon rod through easy detection of a crack in a polycrystalline silicon rod to select a polycrystalline silicon rod having no crack.SOLUTION: A polycrystalline silicon rod (100) is impacted with a hammer (120) to produce a hit sound which is recorded in a recorder (140) through a microphone (130). The hit sound is analyzed to calculate a natural frequency f, and acoustic signals of the hit sound are fast Fourier transformed to display a frequency distribution. A peak frequency f exhibiting a maximum loudness in the frequency distribution after the fast Fourier transformation is then detected to compare the natural frequency f(Hz) with the peak frequency f (Hz). For example, in the case that a frequency ratio R(f/f) is in the range of 0.9≤R≤1.1, the polycrystalline silicon rod is judged to be free from internal and external cracks.

Description

  The present invention relates to a polycrystalline silicon rod, a method for inspecting a polycrystalline silicon rod, and a method for producing a polycrystalline silicon rod, and more particularly to a technique for easily detecting cracks inside and outside the polycrystalline silicon rod.

  A Siemens method is known as a method for producing polycrystalline silicon which is a raw material for single crystal silicon for producing semiconductor devices or silicon for producing solar cells. The Siemens method is a method in which a source gas containing chlorosilane is brought into contact with a heated silicon core wire, and polycrystalline silicon is vapor-phase grown on the surface of the silicon core wire using a CVD (Chemical Vapor Deposition) method.

  When growing polycrystalline silicon by the Siemens method, two silicon core wires are assembled into a torii type in the vertical direction and one horizontal direction in the reactor of the vapor phase growth apparatus, and both ends of the torii type silicon core wire are connected to a pair of core wires. It fixes to a pair of metal electrode arrange | positioned on a baseplate through a holder.

  Next, while conducting a current from the metal electrode and heating the silicon core wire in a temperature range of 900 ° C. or more and 1200 ° C. or less in a hydrogen atmosphere, a source gas such as a mixed gas of trichlorosilane and hydrogen is introduced from the gas nozzle into the reactor. When supplied, silicon grows on the silicon core, and polycrystalline silicon having a desired diameter is formed in an inverted U shape.

  When single crystal silicon is manufactured by FZ (Floating Zone) method using polycrystalline silicon vapor-phase grown by Siemens method, both ends of the inverted U-shaped polycrystalline silicon are cut to obtain a desired length. Adjust to a crystalline silicon rod (cutting step), polish the outer periphery of this polycrystalline silicon rod to make the diameter uniform in the longitudinal direction (cylindrical polishing step), and further process and sharpen one end of this polycrystalline silicon rod ( The tip processing step) and finally, the surface of the polycrystalline silicon rod is etched to remove impurities and strain (etching step).

  With such a polycrystalline silicon rod, cracks are easily formed on the inside and outside in the vapor phase growth process and the cooling process after growth as the diameter increases in recent years.

  If cracks are formed on the inside and outside of the polycrystalline silicon rod, they may break in the above-described cutting step, cylindrical polishing step, tip processing step, or etching step. In the worst case, the polycrystalline silicon rod may break during the growing process of the single crystal silicon ingot by the FZ method. If the polycrystalline silicon rod breaks during these processes, not only the previous process work is wasted, but the equipment used in the process may be damaged.

  In addition, when a polycrystalline silicon rod is used as a recharge material or recharge material in the growth process of a single crystal silicon ingot by the CZ (Czochralski) method, if there is a crack inside or outside the polycrystalline silicon rod, it will be used as a rod When machining to make it, or when descending to a crucible in a CZ furnace heated to a high temperature, the polycrystalline silicon rod breaks and falls starting from cracks, and the silicon melt is scattered or the crucible is destroyed Sometimes.

  Here, the additional charge is to increase the amount of the melt in the crucible by melting the silicon lump filled in the crucible and then gradually dissolving the polycrystalline silicon rod suspended on the crucible into the melt. . In addition, recharging is to increase the amount of melt in the crucible by gradually dissolving the polycrystalline silicon rod suspended on the crucible into the residual liquid after pulling up the CZ crystal.

  Conventionally, various methods have been proposed for detecting cracks inside and outside the polycrystalline silicon. For example, in Japanese Patent Laid-Open No. 2001-21543 (Patent Document 1), a polycrystalline silicon lump is placed in water or other liquid, and a sound wave of 0.5 to 10 MHz is transmitted while scanning a probe above the lump. In addition, a flaw detection method for receiving and displaying an abnormal part directly below the probe in a second-order plane is disclosed.

  Japanese Patent Application Laid-Open No. 2007-218638 (Patent Document 2) compares image data of infrared transmission light and image data of infrared reflected light of a polycrystalline silicon wafer, and compares the brightness or luminance corresponding to the same position. Has been disclosed for each pixel, and a crack inspection method for judging whether or not there is a crack inside and outside is disclosed.

JP 2001-21543 A JP 2007-218638 A

  However, the flaw detection method and the crack inspection method disclosed in Patent Document 1 and Patent Document 2 must be a large-scale inspection apparatus. In addition, crack inspection by hitting sounds of workers has been performed conventionally, but since this hitting sound inspection is a sensory test, there is inevitably a variation in judgment among workers.

  The present invention has been made in order to solve the problems of the conventional method for inspecting cracks in polycrystalline silicon, and the object of the present invention is not to require a large-scale apparatus and is high. The object is to provide a method for inspecting the presence or absence of cracks in polycrystalline silicon with high accuracy, and to provide a high-quality polycrystalline silicon rod.

In order to solve the above-described problem, the polycrystalline silicon rod inspection method according to the present invention performs frequency analysis of the hitting sound obtained by hitting the polycrystalline silicon rod, and the natural frequency f ₀ (Hz) of the hitting sound. ) And a peak frequency f (Hz), and the presence or absence of cracks on the inside and outside of the polycrystalline silicon rod is determined based on the frequency ratio R (f ₀ / f).

For example, when the frequency ratio R (f ₀ / f) is 0.9 ≦ R ≦ 1.1, it may be determined that there is no crack inside and outside the polycrystalline silicon rod.

For example, when the frequency ratio R (f ₀ / f) is 0.95 ≦ R ≦ 1.05, it may be determined that there is no crack inside and outside the polycrystalline silicon rod.

  The polycrystalline silicon rod is obtained, for example, by vapor phase growth by the Siemens method.

The method for producing a polycrystalline silicon rod according to the present invention comprises growing polycrystalline silicon by a vapor phase growth method, using the polycrystalline silicon as a polycrystalline silicon rod, and hitting the polycrystalline silicon rod. Perform frequency analysis to determine the natural frequency f ₀ (Hz) and peak frequency f (Hz) of the percussion sound, and remove the region where the frequency ratio R (f ₀ / f) deviates from 0.9 ≦ R ≦ 1.1 It is characterized by doing.

Further, the method for producing a polycrystalline silicon rod according to the present invention is obtained by growing polycrystalline silicon by a vapor phase growth method, using the polycrystalline silicon as a polycrystalline silicon rod, and hitting the polycrystalline silicon rod. The frequency of the sound is analyzed, the natural frequency f ₀ (Hz) and the peak frequency f (Hz) of the percussion sound are obtained, and the frequency ratio R (f ₀ / f) is outside the range of 0.95 ≦ R ≦ 1.05 It is good also as removing.

  The vapor phase growth method is, for example, a Siemens method.

The polycrystalline silicon rod of the present invention has a ratio R between the natural frequency f ₀ (Hz) obtained from the waveform of the hitting sound of the polycrystalline silicon rod and the peak frequency f (Hz) obtained by frequency analysis of the hitting sound. (F ₀ / f) is 0.9 ≦ R ≦ 1.1.

  The R value may be 0.95 ≦ R ≦ 1.05.

  The polycrystalline silicon rod is obtained, for example, by vapor phase growth by the Siemens method.

  The present invention can be implemented with, for example, a hammer for striking a polycrystalline silicon rod, a voice recorder for recording a striking sound, software for use in frequency analysis, and a PC (personal computer), so that a large-scale apparatus is not required. It can be done easily.

  In addition, since the presence or absence of cracks can be uniquely determined, variations such as sensory inspection do not occur.

  According to the present invention, it is possible to easily detect cracks inside and outside the polycrystalline silicon rod. Based on this method, a polycrystalline silicon rod having no cracks is selected and high-quality polycrystalline silicon is selected. It becomes possible to manufacture a rod.

It is the schematic for demonstrating the one aspect | mode of the inspection method of the polycrystal silicon stick | rod of this invention. It is a flowchart for demonstrating the procedure which frequency-analyzes the impact sound from a polycrystalline silicon stick | rod in this invention. It is a figure which shows an example of the acoustic signal of an impact sound. It is a figure which shows an example of the frequency distribution obtained by carrying out the fast Fourier transform of the acoustic signal of an impact sound. It is a figure which shows the result of having calculated | required the relationship between the value which remove | divided the natural frequency by the peak frequency, and the peak frequency about the polycrystalline silicon rod. It is a figure which shows the result of having calculated | required the relationship between the value which remove | divided the natural frequency by the peak frequency, and the peak frequency about the polycrystalline silicon rod. It is a flowchart which shows the example of a process for classifying a polycrystalline silicon stick without a crack inside and outside. It is the schematic which shows the structural example of the apparatus used for manufacture of a polycrystalline-silicon stick | rod. It is the schematic which shows the structural example of the carbon electrode with which the manufacturing apparatus of a polycrystalline silicon stick is provided.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view for explaining one embodiment of the method for inspecting a polycrystalline silicon rod of the present invention. In the figure, reference numeral 100 denotes a polycrystalline silicon rod to be inspected. The polycrystalline silicon rod 100 exemplified here is obtained by vapor phase growth by the Siemens method described above, and has a diameter of about 110 mm. The length is about 1600 mm. Reference numeral 110 denotes a roller on which the polycrystalline silicon rod 100 is placed, reference numeral 120 denotes a hammer for hitting the polycrystalline silicon rod 100, and reference numeral 130 denotes a sound from the polycrystalline silicon rod 100 generated by the hammer 120. A microphone is used for picking up, and a reference numeral 140 is a recording device for recording a hitting sound picked up by the microphone 130.

  In the inspection method of the present invention, the polycrystalline silicon rod 100 is hit with the hammer 120, and the frequency of the hitting sound generated thereby is analyzed to determine whether or not there are cracks inside and outside the polycrystalline silicon rod 100. For this reason, in order to obtain the original hitting sound of the polycrystalline silicon rod 100, it is desirable that the polycrystalline silicon rod 100 is not in contact with other members as much as possible. That is, in order to perform accurate frequency analysis, it is desirable to hold the polycrystalline silicon rod 100 in a state where the contact area with other members is as narrow as possible. Therefore, in the example shown in FIG. 1, the polycrystalline silicon rod 100 is placed on the two rollers 110.

  The hammer 120 used for hitting the polycrystalline silicon rod 100 is preferably made of a material that hardly causes heavy metal contamination to the polycrystalline silicon rod 100 when hit. For example, it is desirable to use a plastic hammer or a tungsten hammer.

  When the polycrystalline silicon rod 100 is hit with the hammer 120, a striking sound of 100 Hz to 5000 Hz is produced. The longer the polycrystalline silicon rod 100, the lower the frequency of the impact sound. Further, if there are cracks inside and outside the polycrystalline silicon rod 100, the frequency of the hitting sound becomes low.

  The hitting sound from the polycrystalline silicon rod 100 is picked up by the microphone 130 and recorded in the recording device 140. When a digital voice recorder, for example, is used as the recorder 140, an acoustic signal is converted from analog to digital and recorded.

FIG. 2 is a flowchart for explaining the procedure for frequency analysis of the impact sound from the polycrystalline silicon rod in the present invention. First, the hammer 120 is used to hit the polycrystalline silicon rod 100 (S101), and this hitting sound is recorded in the recorder 140 via the microphone 130 (S102). The striking sound is analyzed to calculate the natural frequency f ₀ (Hz) (S103), and the sound signal of the striking sound is fast Fourier transformed (FFT) to display the frequency distribution (S104). ).

  FIG. 3A and FIG. 3B are an example of an acoustic signal of an impact sound and an example of a frequency distribution obtained by fast Fourier transforming the acoustic signal, respectively.

The time from the peak of the acoustic signal waveform of the impact sound shown in FIG. 3A to the next peak (or the valley to the next valley), that is, the period is first read, and the reciprocal of the value is obtained as the natural frequency f ₀ . Subsequently, as shown in FIG. 3B, a frequency distribution is obtained by fast Fourier transform of the acoustic signal. Note that free software for performing a fast Fourier transform on a digitally converted acoustic signal is available on the Internet.

  The sound of the hitting sound generated when the hammer 120 hits a portion of the polycrystalline silicon rod 100 that is not cracked is close to a sine wave, and there are one or two frequencies indicating a large volume recognized in the frequency distribution after the fast Fourier transform. is there.

  On the other hand, hitting a cracked portion of the polycrystalline silicon rod 100 with the hammer 120, the hammering sound is as if it is obtained when a plurality of polycrystalline silicon rods having slightly different lengths are hit at once. Occurs. Specifically, a large number of sound waves having slightly different frequencies are formed, and the waveform of the hitting sound becomes a wave-like waveform having a large number of peaks and valleys in one cycle. For this reason, the period of the waveform becomes long, the frequency becomes low, and the hitting sound can be heard low. When the acoustic signal of such an impact sound is subjected to fast Fourier transform, a frequency distribution having a relatively large volume of many frequencies can be obtained.

Therefore, in the present invention, the peak frequency f indicating the largest volume in the frequency distribution after the fast Fourier transform is detected (S105). The peak frequency f is the main frequency to form a striking sound, if the waveform of the impact sound has been tentatively formed by a single sine wave, the peak frequency f and natural frequency f ₀ is an exact match. On the other hand, when a large number of sound waves overlap to form a waveform of a hitting sound, the peak frequency f and the natural frequency f ₀ are shifted.

Therefore, the natural frequency f ₀ and the peak frequency f are compared (S106).

When the number of sound waves forming the waveform of the hitting sound is relatively small and the difference between the frequencies is small, the waveform of the hitting sound is such that the period of the sine wave is a little longer, so the natural frequency f ₀ is the peak frequency f. Slightly smaller.

On the other hand, when the number of sound waves forming the waveform of the hitting sound increases and the beat waveform is clearly recognized, the beat frequency becomes the peak frequency f. At this time, since the beat period is longer than the period of the hit sound, the natural frequency f ₀ is larger than the peak frequency f.

According to the study by the inventors, when the relationship between the natural frequency f ₀ and the peak frequency f was investigated for a total of 31 polycrystalline silicon rods and the relationship between the cracks was investigated, 10 polycrystalline silicon rods having cracks were obtained. There were 21 polycrystalline silicon rods without cracks. Further, a value (R) obtained by dividing the natural frequency f ₀ by the peak frequency f for each of these polycrystalline silicon rods was 0 or more and 2 or less.

Next, the range is gradually limited by gradually lowering the upper limit of the value (R) obtained by dividing the natural frequency f ₀ by the peak frequency f, and gradually increasing the lower limit, and there are many cracks within the limited range. The number of crystalline silicon rods and the number of polycrystalline silicon rods without cracks were examined. The results are shown in Table 1.

[Table 1]

As shown in Table 1, when the value (R) obtained by dividing the natural frequency f ₀ by the peak frequency f is limited to 0.5 or more and 1.5 or less, of the 10 polycrystalline silicon rods with cracks Seven, or 70%, were indistinguishable from cracked polycrystalline silicon rods. However, when the range of the R value is limited to 0.9 or more and 1.1 or less, there is only one polycrystalline silicon rod with a crack that cannot be distinguished from a polycrystalline silicon rod without a crack.

  When the range of the R value is limited to 0.9 or more and 1.1 or less, there are 19 cracked polycrystalline silicon rods in the R value range, which is only 2 less than the total number (21). is there. That is, it can be seen that most of the polycrystalline silicon rods without cracks have an R value in the range of 0.9 to 1.1. On the other hand, the number of cracked polycrystalline silicon rods in the R value range of 0.9 to 1.1 is only one, and most of the cracked polycrystalline silicon rods have an R value of 0. Either less than 9 or greater than 1.1.

Furthermore, when the R value was limited to a range of 0.95 to 1.05, all the polycrystalline silicon rods in the R value range were free from cracks. That is, it can be seen that the presence or absence of cracks in the polycrystalline silicon rod can be determined by comparing the natural frequency f ₀ and the peak frequency f. Since the number of polycrystalline silicon rods in the R value range is 11, 10 out of 21 polycrystalline silicon rods without cracks have R values not in the range.

  4A and 4B are diagrams showing the results of obtaining the relationship between the R value and the peak frequency for a population of polycrystalline silicon rods different from those summarized in Table 1. In FIGS. 4A and 4B, the vertical axis represents the vertical axis. The scale is different. In these figures, black circles indicate the values of polycrystalline silicon rods without cracks, and white circles indicate the values of polycrystalline silicon rods with cracks.

  As shown in FIG. 4B, most of the cracked polycrystalline silicon rods (white circles) show an R value of less than 0.9 or more than 1.1, and some of them are 0.9 or more and 1.1 or less. Some exhibit R values in the range. However, nothing belongs to the range of 0.95 to 1.05.

That is, as shown in FIG. 4B, a region where the value R obtained by dividing the natural frequency f ₀ by the peak frequency f is less than 0.9 or more than 1.1, more preferably less than 0.95 or more than 1.05. By removing it by cutting or the like, it is possible to sort out the polycrystalline silicon rod 100 having no cracks.

  Therefore, in the present invention, based on the principle described above, the presence / absence of cracks inside and outside the polycrystalline silicon rod is determined (S107).

  FIG. 5 is a flowchart showing an example of a process for selecting a polycrystalline silicon rod having no cracks inside and outside. FIGS. 6 and 7 are a schematic diagram showing a configuration example of an apparatus used for manufacturing polycrystalline silicon and a schematic diagram showing a configuration example of a carbon electrode provided in the polycrystalline silicon manufacturing apparatus, respectively.

  Referring to FIG. 6, a polycrystalline silicon manufacturing apparatus 50 is an apparatus for vapor-phase growing polycrystalline silicon on the surface of a silicon core wire by the Siemens method, and is roughly constituted by a base plate 1 and a reaction vessel 10 and obtained. The polycrystalline silicon 100 includes a straight body portion 100a that is vapor-phase grown on the vertical portion 5a of the silicon core wire 5 assembled in a torii type and a bridge portion 100b that is vapor-phase grown on a horizontal portion (bridge portion 5b).

  The base plate 1 is provided with a metal electrode 2 for supplying current to the silicon core wire 5, a gas nozzle 3 for supplying process gas such as nitrogen gas, hydrogen gas, trichlorosilane gas, and an exhaust port 4 for exhausting exhaust gas.

  The metal electrode 2 is connected to another metal electrode (not shown) or connected to a power source disposed outside the reaction furnace, and receives power from the outside. An insulator 7 is provided on the side surface of the metal electrode 2, and penetrates the base plate 1 while being sandwiched between the insulators 7.

  As shown in FIG. 6, when vapor-phase growing polycrystalline silicon, two core wires (5a) in the vertical direction and one core (5b) in the horizontal direction are assembled in the reactor 10 in a torii type. The silicon core wire 5 is fixed to both ends of the vertical portion 5a of the silicon core wire 5 by the core wire holder 20 held by the carbon electrode 30, and the external power supplied to the metal electrode 2 is passed through the carbon electrode 30. The silicon core wire 5 is energized.

  In addition, the metal electrode 2, the base plate 1, and the reaction furnace 10 are cooled using a refrigerant. The core wire holder 20 and the carbon electrode 30 are both made of graphite.

  At least one of the carbon electrodes 30 has a structure that can slide in all directions within a horizontal plane in the drawing. The carbon electrode 30 includes a lower electrode 32 fixed on the metal electrode 2, which is an external electrode for energizing the silicon core wire 5, and an upper electrode 31 placed on the lower electrode 32. On the upper surface side of the upper electrode 31, a fixing portion for the core wire holder 20 that holds the silicon core wire 5a is provided.

  Further, as shown in FIG. 7, the upper electrode 31 is provided with a hole portion (through hole) 35 penetrating from the upper surface 33 to the lower surface 34, and a bolt 36, which is a rod-shaped fastening member, is placed on It is inserted into the hole 35 from the upper surface 33 of the electrode 31 and fixed by being screwed with the lower electrode 32.

  As shown in FIG. 7, the diameter of the hole 35 is larger than the diameter of the straight body portion of the bolt 36 so that a gap 38 is formed between the straight body portion of the bolt 36 in the hole 35. Yes. The gap between the hole 35 and the straight body portion of the bolt 36 is a mounting surface where the upper electrode 31 is in contact with the upper surface of the lower electrode 32 (the lower electrode in contact with the lower surface 34 of the upper electrode 31 in FIG. 7). 32), it is possible to slide in all directions within the plane, and therefore, the effect of suppressing the occurrence of cracks and cracks in polycrystalline silicon that can expand and contract in any direction during the vapor phase growth process is exhibited.

  First, with the apparatus having the configuration illustrated in FIG. 6, an inverted U-shaped polycrystalline silicon is vapor-phase grown by the Siemens method (S201).

  After the vapor phase growth of the polycrystalline silicon, the inverted U-shaped polycrystalline silicon is taken out from the reaction furnace 10 and divided into the straight body portion 100a and the bridge portion 100b. However, since cracks often remain at both ends of the polycrystalline silicon rod 100, both ends of the polycrystalline silicon rod 100 are cut (S202).

Next, as shown in FIG. 1, the polycrystalline silicon rod 100 is placed on the roller 110 and hit with the hammer 120, and the hitting sound is recorded via the microphone 130. Then, the frequency analysis of the impact sound is performed in the manner described with reference to FIG. 2, and the value R obtained by dividing the natural frequency f ₀ by the peak frequency f is 0.9 or more and 1.1 or less or 0. It is confirmed whether it is 95 or more and 1.05 or less (S203).

  As a simple method, the entire polycrystalline silicon rod 100 may be hit with the hammer 120, and only the hitting sound in the region where the sound is relatively low may be recorded and the frequency analysis may be performed.

If there is a region where the value R obtained by dividing the natural frequency f ₀ by the peak frequency f is outside 0.9 ≦ R ≦ 1.1 or 0.95 ≦ R ≦ 1.05, it seems that cracks exist inside and outside. Therefore, the area is cut and removed (S204). In this case, the frequency analysis is performed again after cutting and removing the crack region (S205). Further, if necessary, steps S204 and S205 are repeated a plurality of times, and finally a value R obtained by dividing the natural frequency f ₀ by the peak frequency f is 0.9 or more and 1.1 or less or 0.95 in all regions. After confirming that it is 1.05 or less, the single crystal silicon rod is selected (S206). In this way, a polycrystalline silicon rod free from cracks can be selected.

[Example 1] Both ends of polycrystalline silicon 100 obtained by vapor phase growth by the Siemens method were cut into a polycrystalline silicon rod 100 having a length of 1.2 m and a diameter of 121 mm. The polycrystalline silicon rod 100 was hit with a tungsten carbide hammer 120, and the hitting sound was recorded in a digital voice recorder 140 with a microphone 130 attached. The natural frequency f ₀ of the recorded hitting sound was 595 Hz.

Subsequently, when the acoustic signal of the impact sound was subjected to fast Fourier transform to display the frequency distribution, the peak frequency f was 603 Hz. At this time, a value R obtained by dividing the natural frequency f ₀ by the peak frequency f is 0.99.

  When this polycrystalline silicon rod 100 was visually inspected under a fluorescent lamp, there was no crack at all. The polycrystalline silicon rod 100 was subjected to cylindrical polishing, tip processing, and etching, and a single crystal ingot was grown by the FZ method, but cracks occurred in the polycrystalline silicon rod 100 during these series of steps. There was nothing.

[Comparative Example 1] In the same manner as in Example 1 described above, the natural frequency f ₀ and peak frequency f of a polycrystalline silicon rod having a length of 1.5 m and a diameter of 122 mm obtained by the Siemens method were measured. As a result, the natural frequency f ₀ was 147 Hz, the peak frequency f was 75.4 Hz, and the value R obtained by dividing the natural frequency f ₀ by the peak frequency f was 1.96.

  When this polycrystalline silicon rod was visually inspected under a fluorescent lamp, there were many cracks, and processing as a polycrystalline silicon rod for growing an FZ silicon ingot was not performed.

  As described above, according to the present invention, it becomes possible to easily detect cracks inside and outside the polycrystalline silicon rod, and based on this method, a polycrystalline silicon rod having no cracks is selected for high quality. It becomes possible to provide a simple polycrystalline silicon rod.

  According to the present invention, it becomes possible to select only polycrystalline silicon rods without cracks, and it is possible to suppress the occurrence of cracks in polycrystalline silicon rods used for growing silicon single crystals by the FZ method or the CZ method.

DESCRIPTION OF SYMBOLS 1 Base plate 2 Metal electrode 3 Gas nozzle 4 Exhaust port 5 Silicon core wire 5a Vertical part 5b Bridge part 10 Reaction container 20 Core wire holder 30 Carbon electrode 31 Upper electrode 32 Lower electrode 33 Upper surface 34 of upper electrode 31 Lower surface 35 of upper electrode 31 Through-hole 36 bolt 37 washer 38 gap 50 polycrystalline silicon manufacturing apparatus 100 polycrystalline silicon rod 110 roller 120 hammer 130 microphone 140 recorder

Claims (10)

A ratio R () between a natural frequency f ₀ (Hz) obtained from a waveform of a hitting sound of the polycrystalline silicon bar and a peak frequency f (Hz) obtained by frequency analysis of the hitting sound. A polycrystalline silicon rod, wherein f ₀ / f) is 0.9 ≦ R ≦ 1.1.   The polycrystalline silicon rod according to claim 1, wherein the R value is 0.95 ≦ R ≦ 1.05.   The polycrystalline silicon rod according to claim 1 or 2, wherein the polycrystalline silicon rod is obtained by vapor phase growth by a Siemens method. The frequency analysis of the hitting sound obtained by hitting the polycrystalline silicon rod is performed, the natural frequency f ₀ (Hz) and the peak frequency f (Hz) of the hitting sound are obtained, and the frequency ratio R (f ₀ / f) is obtained. Based on the above, a method for inspecting a polycrystalline silicon rod, wherein the presence or absence of cracks inside and outside the polycrystalline silicon rod is judged. 5. The method according to claim 4, wherein when the frequency ratio R (f ₀ / f) is 0.9 ≦ R ≦ 1.1, it is determined that there is no crack inside and outside the polycrystalline silicon rod. The inspection method of the polycrystalline silicon rod as described. 6. The method according to claim 5, wherein when the frequency ratio R (f ₀ / f) is 0.95 ≦ R ≦ 1.05, it is determined that there is no crack inside and outside the polycrystalline silicon rod. The inspection method of the polycrystalline silicon rod as described.   The method for inspecting a polycrystalline silicon rod according to any one of claims 4 to 6, wherein the polycrystalline silicon rod is obtained by vapor phase growth by a Siemens method. A polycrystalline silicon is grown by a vapor phase growth method, the polycrystalline silicon is used as a polycrystalline silicon rod, a frequency analysis of a hitting sound obtained by hitting the polycrystalline silicon rod is performed, and a natural frequency f of the hitting sound is obtained. Production of a polycrystalline silicon rod characterized by obtaining ₀ (Hz) and a peak frequency f (Hz) and removing a region where the frequency ratio R (f ₀ / f) deviates from 0.9 ≦ R ≦ 1.1 Method. A polycrystalline silicon is grown by a vapor phase growth method, the polycrystalline silicon is used as a polycrystalline silicon rod, a frequency analysis of a hitting sound obtained by hitting the polycrystalline silicon rod is performed, and a natural frequency f of the hitting sound is obtained. Production of a polycrystalline silicon rod characterized by obtaining ₀ (Hz) and a peak frequency f (Hz) and removing a region where the frequency ratio R (f ₀ / f) deviates from 0.95 ≦ R ≦ 1.05 Method.   The method for producing a polycrystalline silicon rod according to claim 8 or 9, wherein the vapor phase growth method is a Siemens method.