JP2011225387A - Method for processing silicon block, and silicon crushed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing a silicon block by which even when cracks exist in the surface of a silicon crushed product, the adhesion amount of an etching agent after etching can be reduced to such a degree that the significant amount of a corrosive gas is not produced, and a silicon crushed product having high cleanliness can be obtained.SOLUTION: The method for processing a silicon block includes the steps of: (a) heating a silicon block at room temperature; (b) cooling the heated silicon block to generate cracks; (c) crushing the silicon block with generated cracks to obtain a silicon crushed product; (d) immersing the silicon crushed product in pure water to infiltrate pure water into cracks generated in a surface thereof by cooling or crushing; (e) etching the surface of the silicon crushed product immersed in the pure water with an etching agent; and (f) washing the etched surface of the silicon crushed product with pure water to remove the etching agent.

Description

  The present invention relates to a silicon lump processing method capable of improving the cleanliness of a silicon crushed material obtained by crushing a silicon lump, and a silicon crushed material excellent in cleanliness. Silicon lump processing method capable of improving cleanliness of silicon crushed material used as a raw material in the Czochralski method (hereinafter referred to as "CZ method") used for silicon production, and the silicon crushing Related to things.

  In the production of single crystal silicon for semiconductors, the rotational pulling method by the CZ method is frequently used. In this CZ method, polycrystalline silicon is melted in a crucible, a silicon seed crystal is immersed in the melt, and the seed crystal is pulled up while being rotated, whereby single crystal silicon used as a material for a semiconductor device is obtained. It is a method of training.

  As a raw material for single crystal silicon for a semiconductor, a rod-shaped polycrystalline silicon lump manufactured by a Siemens method is generally used. The silicon lump is crushed using a cemented carbide tool such as tungsten carbide, and is made into a silicon crushed material having a size suitable for charging into a crucible for performing the CZ method. Since single crystal silicon for semiconductors is required to have high purity, the silicon crushed material is used as a raw material after the surface is etched with an etchant such as hydrofluoric acid, washed with pure water and dried.

  Patent Document 1 describes a method in which a polycrystalline silicon rod before crushing is etched after washing off dirt adhering to the surface with a pure water shower, and then the etching agent is washed away with the pure water shower. Further, Patent Document 2 describes that after the crushed material of a polycrystalline silicon rod is etched by washing and separating dust with pure water, the etching agent is removed again by washing with pure water.

  There are a method of crushing a silicon lump as it is manufactured and a method of performing a silicon lump whose surface is intentionally cracked by rapid cooling after heating. Since the silicon lump is hard, it cannot be easily crushed as it is manufactured, but can be easily crushed by forming a crack.

  In either case, fine cracks are formed on the surface of the silicon crushed material during crushing. An etchant enters the crack when etching is performed, and it is difficult to discharge the crack even after washing with pure water after etching. Therefore, the etching agent may remain in the cracks on the surface of the silicon crushed material after cleaning.

  The etching agent remaining in the crack is discharged from the inside of the crack to the surface by evaporation or the like during storage of the dried silicon crushed material, and causes the periphery of the silicon crushed material to be contaminated or corroded. Further, when the silicon crushed material is left in a state where the etching agent is attached to the surface, a chemical oxide film is generated depending on the type of the etching agent, and a phenomenon that the surface of the silicon crushed material is discolored occurs. The chemical oxide film takes in impurities contained in the etching agent and impurities in the storage atmosphere.

  Further, when the silicon crushed material in which the etching agent remains in the crack is used as a raw material, the etching agent and the incorporated impurities are mixed into the single crystal silicon for semiconductor, which may cause a quality defect. In addition, when manufacturing single crystal silicon for semiconductors by the CZ method, corrosive gas is generated, which may deteriorate the single crystal manufacturing apparatus.

  According to Patent Document 3, a crack is generated in the crushed material by crushing the rod-like polycrystalline silicon with the impact force of jetting high-pressure water in response to the problem that the etching agent remains in the crack on the surface of the silicon crushed material after etching. A countermeasure is described that eliminates the need for etching.

  However, in the method described in Patent Document 3, the method of breaking the silicon lump is irregular, and since the obtained silicon crushed material has a wide particle size distribution range, the yield of silicon crushed material having a desired particle size is low. . In addition, the method described in Patent Document 3 requires equipment for using high-pressure water instead of conventional equipment, and is difficult to implement.

JP 2005-288333 A JP-A-8-67510 JP-A-6-271309

  The present invention has been made in view of the above-mentioned problems, and even when cracks exist on the surface, the amount of etching agent after etching is set to such an extent that the amount of corrosive gas generated is not significant. A silicon lump treatment method capable of obtaining a high-cleanness silicon crushed material, and the amount of adhesion of the etching agent after etching is such that the generation amount of corrosive gas is not significant. The purpose is to provide crushed silicon crushed material.

  In order to solve the above problems, the present inventors can suppress the penetration of the etching agent into the crack by etching the silicon crushed material in a state where the crack is filled with pure water. Therefore, it was studied to fill the cracks in the silicon crushed material before etching with pure water. In addition, the amount of etching agent on the surface of the silicon crushed material, where the generation of corrosive gas becomes significant during the production of single crystal silicon for semiconductors by the CZ method, was examined.

As a result, it was found that the generation of corrosive gas becomes remarkable when the amount of the etching agent on the surface of the silicon crushed material exceeds 30 ng / cm ² .

And, when pure water was simply bathed on the crushed silicon by shower, the adhesion amount of the etching agent after etching could not be reduced to 30 ng / cm ² or less. This is presumably because the surface of the silicon crushed material was wet, but pure water did not enter the crack.

On the other hand, when the silicon crushed material was completely immersed in pure water, the adhesion amount of the etching agent after etching could be 30 ng / cm ² or less. This is probably because pure water was filled in the cracks, and the infiltration of the etching agent during etching could be suppressed. Moreover, it is thought that the pure water was filled in the cracks due to the effect of the water pressure when immersed in pure water.

  This invention is made | formed based on the above knowledge, The summary exists in the processing method of the silicon lump of following (1)-(4), and the silicon crushed material of (5).

(1) A silicon lump processing method comprising the following steps (a) to (f).
(A) a step of heating a silicon mass at room temperature;
(B) cooling the heated silicon mass to generate cracks;
(C) a step of crushing the silicon lump in which the crack has occurred to obtain a silicon crushed material,
(D) a step of immersing the silicon crushed material in pure water and allowing pure water to penetrate into cracks generated on the surface by cooling or crushing;
(E) a step of etching the surface of the silicon crushed material immersed in the pure water using an etching agent; and (f) washing the surface of the etched silicon crushed material with pure water to remove the etching agent. Process.

(2) The silicon lump processing method according to (1), wherein the time from the completion of the step (d) to the start of the step (e) is within 10 hours.

(3) In the step (a), the room temperature silicon mass is heated to 200 ° C. or higher and 1200 ° C. or lower,
In the step (b), the heated silicon mass is cooled to 100 ° C. or lower,
In the step (d), 90% by volume or more of the silicon crushed material group consisting of a plurality of the silicon crushed materials is immersed under the pure water surface. Processing method.

(4) In the said process (d), the immersion time to the pure water of the said silicon crushed material shall be 1 second or more and 60 minutes or less, The processing method of the silicon lump of said (1)-(3) characterized by the above-mentioned.

(5) A silicon crushed material obtained by crushing a silicon lump that has been cracked by heating after being heated from room temperature, and the amount of etching agent deposited per unit area on the surface after etching is 30 ng / cm ² or less. Silicon crushed material characterized by being.

  According to the silicon lump processing method of the present invention, even if cracks exist on the surface, the amount of the etching agent after etching is such that the amount of corrosive gas generated is not significant, and the silicon having high cleanliness. A crushed material can be obtained. In addition, by using the silicon crushed material obtained by the silicon lump processing method of the present invention and the silicon crushed material of the present invention as raw materials, high-quality single crystal silicon for semiconductors with few impurities can be produced. There is also no risk of degrading the single crystal manufacturing apparatus.

It is a figure which shows the structural example after the pure water immersion process of the processing apparatus which can implement the processing method of the silicon lump of this invention. It is a figure which shows the structural example of the ultrasonic cleaning apparatus for measuring the adhesion amount of an etching agent.

1. The silicon lump treatment method of the present invention The silicon lump treatment method of the present invention comprises a heating step, a cooling step, a crushing step, a pure water immersion step, an etching step, and a pure water washing step.

1-1. Target silicon lump In the silicon lump processing method of the present invention, not only a rod-shaped polycrystalline silicon lump produced by the Siemens method but also a single crystal silicon lump produced by the CZ method can be used as the silicon lump. it can. In addition, a large silicon lump is not easily crushed compared to a small one. Here, the “large size” of the size of the silicon lump means a size that does not allow passage of holes having a diameter of 40 mm or less. The silicon lump processing method of the present invention is effective for crushing a large silicon lump, and particularly effective for crushing a large silicon lump that cannot pass through a hole having a diameter of 100 mm or more.

1-2. Description of each step (1) Heating step In the heating step, a silicon chunk at room temperature is heated using a heating furnace so that the temperature rises to the inside. This is because a large temperature gradient is formed inside the silicon mass so that cracks are generated in the silicon mass in the next cooling step. The temperature of the entire silicon lump after completion of heating is preferably 200 ° C. or higher, and more preferably 300 ° C. or higher in order to generate sufficient cracks.

  In the heating process, it is desirable that the heating temperature is not too high in order to prevent contamination from the heating furnace. However, when a heating furnace with a very high cleanliness is used, heating up to 1200 ° C. is allowed. Considering the cost of the heating furnace, the temperature raising time, the energy required for heating, etc., the heating temperature is practically 900 ° C. or less.

(2) Cooling process In a cooling process, the silicon lump heated at the heating process is cooled, and a crack is generated in the silicon lump. The cooling method may be simply taking out from the heating furnace to the room temperature atmosphere and leaving it to stand. However, in order to effectively generate cracks by forming a large temperature gradient inside the silicon lump, and to suppress contamination of the silicon lump during cooling, it is desirable to cool the silicon lump in contact with pure water. For cooling with pure water, a method of taking a shower of pure water, a method of immersing in pure water in a water tank, or the like can be appropriately employed.

(3) Crushing process In the crushing process, the silicon lump in which the crack has occurred is crushed into a silicon crushed material. The crushing of the silicon lump may be performed with a machine such as a jaw crusher or a blow crusher, or may be performed manually with a tool such as a hammer.

(4) Pure water immersion process FIG. 1: is a figure which shows the structural example after the pure water immersion process of the processing apparatus which can implement the processing method of the silicon lump of this invention. The processing apparatus includes a pure water immersion tank 11, an etching tank 12, a pure water cleaning tank 13, and a drying chamber 14. The pure water immersion tank 11 and the pure water washing tank 13 are provided with pure water supply pipes 11a and 13a, and contain pure water 11b and 13b.

  In the pure water immersion step, the silicon crushed material is immersed in pure water, and the pure water is infiltrated into the cracks generated on the surface of the silicon crushed material in the cooling step and the crushing step. Specifically, the crushed silicon group 1 is accommodated in a container 2 having a hole made of fluorine resin, and the whole container 2 is immersed in pure water 11 b in the pure water immersion tank 11. The pure water 11b may be continuously supplied from the pure water supply pipe 11a to be in a fluid state or may be in a stationary state.

  By allowing pure water to permeate into the crack, intrusion of the etching agent into the crack can be suppressed in the next etching step. In order to suppress the penetration of the etchant into the crack, it is not necessary to penetrate pure water deep into the crack, but if pure water is present in the vicinity of the cracked silicon crushed surface (that is, in the vicinity of the opening of the crack) Good.

  When silicon crushed material is immersed in pure water, when multiple silicon crushed materials (hereinafter referred to as “silicon crushed material group”) are immersed together, etching mixed into the raw material of single crystal silicon for semiconductors In order to make the total amount of the agent not to deteriorate the quality of the single crystal silicon and to deteriorate the single crystal production apparatus, it is desirable to immerse 90% by volume or more of the silicon crushed material group below the pure water surface. It is further desirable to immerse the volume%.

  In order to infiltrate pure water into the crack, it is effective to increase the water pressure on the surface of the silicon crushed material. Therefore, it is desirable to immerse the crushed silicon deeply by 20 mm or more from the pure water surface.

  If the time for immersing the silicon crushed material in pure water is 1 second or longer, the effect of suppressing the infiltration of the etching agent into the crack in the etching process can be obtained. However, in order to sufficiently obtain the effect of suppressing the penetration of the etching agent, 5 seconds or more is desirable, and 30 seconds or more is more desirable. Although there is no particular upper limit, it is preferably 1 hour or less and more preferably 10 minutes or less from the viewpoint of the processing efficiency of the silicon lump.

(5) Etching process In the etching process, the surface of the silicon crushed material immersed in pure water is etched using an etching agent in order to dissolve and remove foreign substances and impurities adhering to the surface of the silicon crushed material in the crushing process. To do. Specifically, the silicon crushed material group 1 in which pure water is infiltrated into the crack is transported to the etching tank 12 together with the container 2 and immersed in the etching agent 12a. As the etching agent, hydrofluoric acid, nitric acid, hydrogen peroxide solution, sulfuric acid, ammonia, and a sodium hydroxide aqueous solution can be used alone or in a mixture of two or more thereof.

  The pure water in the crack is difficult to evaporate because the area of the portion in contact with the air is small. However, if the silicon crushed material is left after the pure water cleaning step is completed, the pure water in the cracks is reduced by evaporation. When pure water in the cracks disappears, it is not possible to suppress the penetration of the etchant into the cracks in the etching process.

  Therefore, the time from the completion of the pure water immersion process to the start of the etching process (hereinafter referred to as “etching start time”) is preferably within 10 hours, and more preferably within 1 hour. In the case where the pure water immersion process, the etching process, and the pure water cleaning process are continuously performed, the etching start time is preferably within 10 minutes from the viewpoint of the processing efficiency of the silicon lump.

(6) Pure water cleaning step In the pure water cleaning step, the etched silicon crushed material is washed with pure water to remove the etching agent adhering to the surface. Specifically, the etched silicon crushed material group 1 is transferred to the pure water cleaning tank 13 together with the container 2 and immersed in the pure water 13b. The pure water 13b may be continuously supplied from the pure water supply pipe 13a to be in a fluid state or may be in a stationary state. Moreover, you may perform washing | cleaning by bathing a silicon crushed material with a pure water with a shower.

  The crushed silicon washed with pure water is dried because pure water adheres to the surface. The silicon crushed material may be dried by blowing hot air in the drying chamber 14 shown in FIG. 1 or by leaving it alone.

In the silicon crushed material obtained by the silicon lump processing method of the present invention, not only foreign substances and impurities on the surface are removed by the etching process, but the etching agent adhering to the surface may be 30 ng / cm ² or less. Therefore, it can be used as single crystal silicon used as a material for a semiconductor device that requires high purity, and there is no possibility of degrading the single crystal manufacturing apparatus when manufacturing single crystal silicon.

2. Silicon crushed material of the present invention The silicon crushed material of the present invention is characterized in that the adhesion amount of the etching agent per unit area on the surface after etching is 30 ng / cm ² or less. By using the silicon crushed material of the present invention as a raw material, the purity of the silicon single crystal can be improved without contaminating the single crystal production apparatus. The silicon crushed material of the present invention can be produced by the silicon lump processing method of the present invention.

3. Method for measuring amount of etching agent adhesion on crushed silicon surface The etched silicon crushed material may have an etching agent remaining on the surface even if it is washed with water. The adhesion amount of the etching agent can be measured as follows.

3-1. Outline FIG. 2 is a diagram showing a configuration example of an ultrasonic cleaning apparatus for measuring the amount of etching agent attached. One specimen shall be one crushed silicon. At the time of measurement, the entire silicon crushed material 21 as a specimen is immersed in pure water 23 in a container 22 and left for 24 hours or longer, and the etching agent adhering to the surface of the silicon crushed material 21 is eluted in the pure water 23. Let The amount of pure water in the container 22 may be an amount that allows the entire silicon crushed material 21 as a specimen to be immersed. Thereafter, the silicon crushed material 21 is placed in an ultrasonic cleaning device 24 containing water 25 together with the container 22, and ultrasonic vibration is applied to the container 22, the pure water 23 and the silicon crushed material 21, The etching agent in the cracks is discharged and the pure water 23 is stirred to make the concentration of the etching agent in the pure water 23 uniform.

  The ion chromatograph method is applied to the pure water 23 in which the concentration of the etching agent becomes uniform, and the etching agent concentration in the pure water 23 is measured. By multiplying the etching agent concentration by the amount of pure water and dividing by the total surface area of one silicon crushed material 21 as a specimen, the amount of the etching agent per unit surface area of the silicon crushed material 21 for the specimen. (Hereinafter, also simply referred to as “etching agent adhesion amount”) can be calculated. Such measurement and calculation are performed on a plurality of specimens, and the average value of the obtained etching agent adhesion amount is adopted as the etching agent adhesion amount of the silicon crushed material obtained from the original silicon lump. The greater the number of specimens, the higher the accuracy of the numerical values obtained, and 100 specimens will provide sufficiently accurate values.

3-2. Measurement conditions The etching agent adhesion amount is measured under the following conditions.
(1) Specimen One specimen of silicon crushed material is used as one specimen, and the average value of the measured values of 100 specimens is used as the etching agent adhesion amount. The mass of one specimen is not particularly defined, and may be appropriately determined as the mass in the vicinity of the average mass of the silicon crushed material group to be sampled so as to facilitate sampling. For example, the mass of one specimen can be 120 g. Since the measurement accuracy increases when the masses of the respective specimens are made uniform, each specimen is selected within a range of ± 3% of the determined mass. When the mass of one specimen is 120 g, a silicon crushed material of 116.4 g or more and 123.6 g or less is selected as the specimen.
(2) Conditions for applying ultrasonic vibration Amount of pure water in the container: 400 mL
Pure water immersion time before application of ultrasonic vibration: 24 hours Ultrasonic cleaning device: UT-204 (manufactured by Sharp Corporation)
Frequency and output: 39kHz, 200W
Application time: 600 s or more (3) Ion chromatography conditions a. Apparatus: DX-500 (manufactured by Dionex)
b. Column: Separation column AS4A
Guard column AG4A
Suppressor column ASRS300
c. Eluent (for nitric acid and hydrofluoric acid):
NO ₃ ^- 1.5 m moles Na ₂ CO ₃ + 1.0m mol NaHCO ₃
F ^- 5 mmol Na ₂ SO ₄
d. Liquid feed rate: 2 ml / min
e. Sample injection volume: 200 μL

(4) Etching agent adhesion amount calculation method The etching agent adhesion amount can be calculated by the following equation (1) from the etching agent concentration in pure water measured under the above conditions.
A = D × V / S (1)
Here, each symbol in the formula (1) means the following quantities (the units of each quantity are arbitrary). A: Etching agent adhesion amount per unit surface area of silicon crushed material, D: Etching agent concentration in pure water, V: Pure water amount, S: Total surface area of three silicon crushed materials.
The total surface area S of the three silicon crushed materials is calculated on the assumption that the shape of each silicon crushed material is a sphere. S (cm ² ) can be calculated by the following equation (2) since the silicon density is 2.33 g / cm ^{3 when} the average weight of each silicon crushed material is W (g).
S = 2.75 × W ^2/3 (2)

  In order to confirm the effects of the silicon lump processing method and the silicon crushed material of the present invention, the following tests were conducted and the results were evaluated.

1. Test conditions The silicon lump of normal temperature was made into the silicon crushed material by the heating process, cooling process, and crushing process which were mentioned above. From this silicon crushed material, those whose cracks can be confirmed on the surface by visual inspection were selected and used as the objects to be transferred to the steps after the pure water immersion step. When the surface of the selected silicon crushed material was observed, the maximum width of the crack was 0.3 mm.

  Among the examples, in the present invention example, the silicon crushed material was processed using the processing apparatus shown in FIG. Moreover, although the comparative example differed from the process of the example of this invention only in the point which did not immerse in the pure water in a pure water immersion tank, the process similar to the example of this invention was performed in another point.

  Capacity of pure water immersion tank, etching tank and pure water cleaning tank, flow rate and immersion time of pure water in pure water immersion tank, nitric acid concentration of etching agent, flow rate and immersion time of pure water in pure water immersion tank, and Table 1 shows the set temperature of the drying chamber and the drying time of the silicon crushed material.

  The silicon crushed material group consisting of the crushed silicon crushed material is housed in a container having a hole made of fluororesin, and the whole container is immersed in pure water in a pure water immersion tank, and pure water is infiltrated into the crack (pure water). Water immersion step). Pure water was continuously supplied from a pure water supply pipe to be in a fluid state.

  The crushed silicon group in which pure water was infiltrated into the cracks was transferred to the etching tank together with the container and immersed in an etching agent (etching step). The etchant was a mixed solution of hydrofluoric acid and nitric acid containing 70% by weight of nitric acid, and the immersion time was 5 minutes.

  And the etched silicon crushed material group was conveyed to the pure water washing tank with the container, and was immersed in the pure water, and the etching agent was removed from the surface of the silicon crushed material (pure water washing process). Pure water was continuously supplied from a pure water supply pipe to be in a fluid state.

  The silicon crushed material group from which the etching agent had been removed was transferred to the drying chamber together with the container, and hot air was blown to dry the adhering pure water.

  Moreover, as shown in Table 2, in the examples of Test Nos. 1 to 3 which are examples of the present invention, the time until the etching process was started after the completion of the pure water immersion process (etching start time) was changed. The example of test number 4 is a comparative example, and since there is no pure water immersion step, the etching start time could not be specified.

2. Test Results The amount of etching agent deposited on the surface of the crushed silicon obtained in each example was evaluated using the amount of nitric acid deposited per unit area as an index. The nitric acid adhesion amount was measured by the above-described method for measuring the etching agent adhesion amount, and was an average value of the measurement values of 100 samples. The results are shown in Table 2. Nitric acid was evaluated because the concentration in the etching agent was higher than that of the other components, and the concentration could be easily measured.

  The silicon crushed material obtained in each example was screened by overlapping a JIS standard sieve having a desired opening and a opening having a larger opening than that, and selecting those having a uniform particle diameter. Three samples were randomly selected from the selected crushed silicon and used as specimens for measuring the amount of adhering etchant, and the measurement method described above was applied.

Etching agent adhesion amount of the silicon crushed material of test numbers 1 to 3 which is an example of the present invention is 30 ng / cm ² or less, and problems such as poor quality and deterioration of manufacturing equipment even when used as a raw material for single crystal silicon for semiconductors It was a grade which does not produce. The longer the etching start time is, the larger the amount of the etching agent attached is because the pure water in the cracks evaporates and decreases before the etching starts and the etching agent enters the cracks.

On the other hand, the etching agent adhesion amount of the silicon crushed material of Test No. 4 which is a comparative example was very large at 100 ng / cm ² . This is presumably because the etchant entering the cracks containing no pure water could not be discharged even in the pure water cleaning process.

  According to the silicon lump processing method of the present invention, even if cracks exist on the surface, the amount of the etching agent after etching is such that the amount of corrosive gas generated is not significant, and the silicon having high cleanliness. A crushed material can be obtained. In addition, by using the silicon crushed material obtained by the silicon lump processing method of the present invention and the silicon crushed material of the present invention as raw materials, high-quality single crystal silicon for semiconductors with few impurities can be produced. There is also no risk of degrading the single crystal manufacturing apparatus. Therefore, the present invention is a useful technique in the field of semiconductor silicon single crystals.

DESCRIPTION OF SYMBOLS 1: Silicon crushed material group, 2: Container, 11: Pure water immersion tank, 11a: Pure water supply pipe, 11b: Pure water, 12: Etching tank, 12a: Etching agent, 13: Pure water washing tank, 13a: Pure Water supply pipe, 13b: pure water, 14: drying chamber, 21: crushed silicon, 22: container, 23: pure water, 24: ultrasonic cleaning device, 25: water

Claims (5)

A silicon lump processing method comprising the following steps (a) to (f):
(A) a step of heating a silicon mass at room temperature;
(B) cooling the heated silicon mass to generate cracks;
(C) a step of crushing the silicon lump in which the crack has occurred to obtain a silicon crushed material,
(D) a step of immersing the silicon crushed material in pure water and allowing pure water to penetrate into cracks generated on the surface by cooling or crushing;
(E) etching the surface of the silicon crushed material immersed in the pure water using an etching agent; and (f) washing the surface of the etched silicon crushed material with pure water to remove the etching agent. Process.   2. The method for processing a silicon lump according to claim 1, wherein the time from the completion of the step (d) to the start of the step (e) is within 10 hours. In the step (a), the normal temperature silicon mass is heated to 200 ° C. or more and 1200 ° C. or less,
In the step (b), the heated silicon mass is cooled to 100 ° C. or lower,
In the said process (d), 90 volume% or more of the silicon | silicone crushed material group which consists of the said some silicon | silicone crushed material is immersed under the pure water liquid surface, The process of the silicon lump of Claim 1 or 2 characterized by the above-mentioned. Method.   The method for treating a silicon lump according to any one of claims 1 to 3, wherein, in the step (d), the immersion time of the silicon crushed material in pure water is 1 second or more and 60 minutes or less. It is a silicon crushed material obtained by crushing a silicon lump that has been cracked by heating after being heated from room temperature, and the amount of etching agent deposited per unit area on the surface after etching is 30 ng / cm ² or less. Characterized by crushed silicon.

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