Method for producing silicon microparticles and silicon microparticles produced thereby

Abstract

A method for producing silicon microparticles includes the steps of: flowing a silane gas mixture into a reactor; and decomposing the silane gas mixture in the reactor to produce silicon microparticles, wherein the silane gas mixture includes a first silane gas and a second silane gas, and the decomposition temperature of the first silane gas is lower than the decomposition temperature of the second silane gas. The method also provides silicon microparticles produced thereby.

Description

[Technical Field]

[0001] The present invention relates to a method for producing silicon microparticles and silicon microparticles produced thereby. [Background technology]

[0002] Silicon is used in various industrial fields such as solar power and semiconductors, and the demand for silicon is increasing dramatically.

[0003] Silicon is typically produced by the Siemens process, which uses a bell-jar type reactor, and the FBR (fluidized bed reactor) process.

[0004] Among these, the Siemens process is a method of depositing silicon on the surface of a silicon rod installed in a bell-shaped reactor. However, the surface area required for silicon deposition is limited, and the diameter of the silicon rod that increases through the deposition reaction is limited, making continuous processing impossible. In addition, the amount of power consumed per unit weight of silicon is large, resulting in a limited productivity.

[0005] The FBR method grows silicon seed particles by depositing silicon on the surface of silicon seed particles heated to high temperatures. The silicon produced in this way is generally produced in sizes of millimeters or larger. To obtain micro-sized silicon, a separate crushing process is required. The crushing process can produce fine powder, necessitating a sieving process, complicating the process, increasing time and cost, and resulting in inefficiency. Furthermore, during the seed particle growth process in a fluidized bed reactor, the silicon comes into contact with the reactor's inner wall, increasing the impurity content.

[0006] Therefore, it is necessary to develop a method for solving the above problems and efficiently manufacturing silicon microparticles with controlled particle size while minimizing the content of impurities.

[0007] Therefore, the present inventors have confirmed that silicon microparticles can be produced by simultaneously forming silicon seed particles and growing particles in one reactor without the need for silicon rods or seed particles, and have completed the present invention. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for efficiently and continuously producing silicon microparticles of controlled size while minimizing the content of impurities.

[0009] An object of the present invention is to provide an economical and efficient method for producing silicon microparticles, which does not require a separate crushing or sorting process.

[0010] The objects of the present invention are not limited to those mentioned above, and other objects and advantages of the present invention not mentioned above can be understood from the following description and can be more clearly understood from the examples of the present invention. Furthermore, it can be easily understood that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0011] To achieve the above object, the present invention provides a method for producing silicon microparticles, comprising the steps of: flowing a silane gas mixture into a reactor; and decomposing the silane gas mixture in the reactor to produce silicon microparticles, wherein the silane gas mixture includes a first silane gas and a second silane gas, and the decomposition temperature of the first silane gas is lower than the decomposition temperature of the second silane gas.

[0012] According to the present invention, silicon microparticles with a low content of impurities can be provided, which are manufactured by the method for manufacturing silicon microparticles. [Effects of the Invention]

[0013] The method for producing silicon microparticles according to the present invention can produce silicon microparticles without silicon rods or silicon seed particles, thereby avoiding unnecessary contact and thereby reducing the content of metal impurities without any additional process steps.

[0014] The method for producing silicon microparticles according to the present invention is more economical and efficient since the production of silicon seed particles and particle growth are carried out simultaneously in one reactor.

[0015] The method for producing silicon microparticles according to the present invention does not require a separate pulverization process, does not generate fine powder, and does not require a sieving process, so silicon microparticles can be produced more economically and efficiently.

[0016] The above-mentioned effects and specific effects of the present invention will be described in conjunction with the following description of the preferred embodiment of the invention. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a scanning electron microscope (SEM) photograph of silicon microparticles prepared according to Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The above-mentioned objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily implement the technical concept of the present invention. In describing the present invention, if a detailed description of known technologies relating to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0019] Among the contents not described in this specification, those that can be technically inferred by an ordinary technician in this technical field will be omitted from the description.

[0020] Hereinafter, when it is said that an arbitrary configuration is arranged "above (or below)" a component or "on (or under)" a component, it means that the arbitrary configuration is arranged not only in contact with the upper surface (or lower surface) of the above component, but also that other configurations may be interposed between the above component and an arbitrary configuration arranged "above (or below)" the above component.

[0021] Also, when it is described that a certain component is "connected", "coupled" or "connected" to another component, it should be understood that the above components may be directly connected or connected to each other, but other components may "intervene" between the components, or each component may be "connected", "coupled" or "connected" through another component.

[0022] In this specification, "<X" and "≦X" respectively mean less than X and less than or equal to X, and ">X" and "≧X" respectively mean greater than X and greater than or equal to X.

[0023] In various embodiments of this specification, although terms such as first, second, third, etc. are used to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another.

[0024] The terms used in this specification are for the purpose of explaining the embodiments and are not intended to limit the present invention. In this specification, the singular includes the plural unless otherwise specified. Descriptions such as "including" and "containing" used in this specification do not exclude the existence or addition of one or more other components of the recited component.

[0025] Hereinafter, the method for manufacturing silicon microparticles according to the present invention will be specifically described.

[0026] A method for manufacturing silicon microparticles according to one embodiment of the present invention includes the steps of: flowing a silane gas mixture into a reactor; and decomposing the silane gas mixture in the reactor to manufacture silicon microparticles, wherein the silane gas mixture includes a first silane gas and a second silane gas, and the decomposition temperature of the first silane gas is lower than the decomposition temperature of the second silane gas.

[0027] Considering the dispersibility of silicon particles and the activity due to the low surface area of ​​silicon particles, there is an increasing demand for silicon microparticles in various fields.

[0028] The FBR (fluidized bed reactor) method involves placing silicon seed particles in a reactor and injecting silane gas to grow the seed particles, typically producing silicon particles larger than a millimeter in size. To obtain micro-sized silicon, a separate grinding process is required, which can produce fine powder and necessitate a sieving process, resulting in complex processes, increased time and cost, and inefficiency. Another problem is that the silicon comes into contact with the inner wall of the reactor during the production process, resulting in a high impurity content.

[0029] The method for producing silicon microparticles does not use silicon rods or silicon seed particles, does not require a process of contacting a reactor during production, and can reduce the content of metal impurities without any additional process.

[0030] Specifically, the method for producing silicon microparticles includes flowing a silane gas mixture into a reactor. The silane gas mixture is a gas used as a raw material in producing silicon particles, and may be a mixture of two or more silane gases represented by Chemical Formula 1 or Chemical Formula 2. For example, the silane gas mixture may be two or more silane gases selected from the group consisting of monosilane (SiH), monochlorosilane (SiH3Cl), dichlorosilane (SiH2Cl2), trichlorosilane (SiHCl3), tetrachlorosilane (SiCl4), hexachlorosilane (Si2Cl6), disilane (Si2H6), and combinations thereof.

[0031] (Chemical 1) SiH x Cl 4-x (0≦x≦4, x is an integer.)

[0032] (Chemical 2)Si2H y Cl 6-y (0≦y≦6, y is an integer.)

[0033] The method for producing silicon microparticles does not use silicon seed particles, and can produce silicon microparticles using the silane gas mixture containing first and second silane gases having different decomposition temperatures, where the first and second silane gases can be selected from the silane gases represented by Chemical Formula 1 or Chemical Formula 2 above.

[0034] The decomposition temperature of the first silane gas is lower than the decomposition temperature of the second silane gas, and the first silane gas may be a silane gas having a decomposition temperature of 350° C. to 600° C., and the second silane gas may be a silane gas having a decomposition temperature of 600° C. to 1,000° C. For example, the first silane gas may be silane dichloride (SiH2Cl2), and the second silane gas may be silane trichloride (SiHCl3).

[0035] The method for producing silicon microparticles uses the silane gas mixtures having different decomposition temperatures to adjust the decomposition rate, thereby forming silicon seed particles and growing the particles.

[0036] For example, the decomposition temperature of the first silane gas is lower than the decomposition temperature of the second silane gas, so that the first silane gas can be thermally decomposed first to form seed particles in the reactor, and the second silane gas can be deposited on the seed particles formed by thermal decomposition, thereby producing silicon microparticles in one reactor.

[0037] The first silane gas and the second silane gas may be simultaneously introduced into the reactor at a molar ratio of 1:30 to 1:2. Preferably, they may be simultaneously introduced at a molar ratio of 1:20 to 1:2. This allows for good control of the seed particle formation rate and particle growth. For example, if the ratio of the first silane gas is below the above range, silicon seed particles may not be formed smoothly. If the ratio of the first silane gas is above the above range, only a large number of small particles that have not fully grown may be formed, making it impossible to form silicon particles of the desired size.

[0038] The silane gas mixture may be flowed into the reactor together with hydrogen gas, which may undergo a reduction reaction with the silane gas mixture to produce silicon.

[0039] The hydrogen gas may flow into the reactor at a content of 50 to 90 mol % relative to the total amount of the hydrogen gas and the silane gas mixture.

[0040] The method for producing silicon microparticles includes decomposing the silane gas mixture in the reactor to produce silicon microparticles.

[0041] In one of the reactors, the silane gas mixture can decompose to produce silicon seed particles and grow to produce silicon microparticles.

[0042] Specifically, the first silane gas, which has a temperature lower than the decomposition temperature of the silane gas mixture introduced into the reactor, is first thermally decomposed to form seed particles, and the second silane gas is then deposited on the seed particles formed by thermal decomposition to produce silicon microparticles through a homogeneous reaction using chemical vapor synthesis (CVS). As a result, the silicon microparticles can be produced at a faster rate and may have smaller crystal grains.

[0043] In this way, seed particle generation and particle growth are simultaneously performed in one reactor, eliminating the need for a separate grinding process, generating no fine powder, and eliminating the need for a sieving process, allowing for more economical and efficient continuous production of silicon microparticles.

[0044] When the silane gas mixture is decomposed to produce silicon microparticles, the internal temperature of the reactor may be 700°C to 1,000°C, and the internal pressure of the reactor may be 1 bar to 10 bar. Maintaining the temperature and pressure of the reactor within the above ranges during the reaction step is preferable from the viewpoints of controlling the thermal decomposition rate of the silane gas mixture, controlling the size of the silicon particles, and improving the reaction yield. The reactor may be heated to the above temperature by a heating device.

[0045] The silane gas mixture can be retained in the reactor for 5 to 60 minutes to produce the silicon microparticles. By adjusting the retention time of the silane gas mixture within the above range, the desired silicon microparticles can be produced more efficiently. For example, if the retention time of the silane gas mixture is less than the above range, there may be insufficient time for seed particle formation and particle growth. If the retention time of the silane gas mixture is greater than the above range, the size of the silicon particles may deviate from the desired range, and the crystal grains of the silicon particles may grow too large.

[0046] The method for producing silicon microparticles may further include a step of recovering the silicon microparticles, and may further include a step of cooling the silicon microparticles before recovery.

[0047] Another embodiment of the present invention provides silicon microparticles manufactured by the method for manufacturing silicon microparticles, which can be used as a silicon nitride raw material, a solar cell material, an anode material for lithium ion batteries, etc.

[0048] Specifically, according to the method for producing silicon microparticles of the present invention, the silicon microparticles are 1 μm <d 10 <4 μm, 2 μm <d 50 <7 μm and 4 μm <d 90 It may have a particle size of <13 μm, which eliminates the need for a separate grinding process. Furthermore, since there is no grinding process, no fine powder is generated and no sieving process is required.

[0049] The silicon microparticles having a particle size distribution within the above range are suitable for use as raw materials for silicon nitride and battery anode materials, etc. The size of the silicon microparticles can be measured by a laser diffraction method using a Beckman Coulter LS13 320.

[0050] The silicon microparticles may have the form of spherical particles.

[0051] The silicon microparticles may have a particle size within the above range and a total metal impurity content of 2,000 ppm or less. In this specification, the term "metal impurities" refers to metal elements that affect the quality of silicon particles when they are used in secondary batteries, etc., and may typically refer to the 24 metal elements from Al to Zn listed in Table 2 of the specification, but is not necessarily limited thereto.

[0052] The silicon microparticles are produced by using a silane gas mixture to produce powder without silicon rods or silicon seed particles, which eliminates unnecessary contact and allows for more accurate reduction of the metal impurity content.

[0053] If metal impurities remain in silicon microparticles, side reactions due to the metal impurities may occur, thereby degrading physical properties. Therefore, additional processes are required to remove the metal impurities contained in the silicon particles. On the other hand, the silicon microparticles produced by the above-described production method may contain low levels of metal impurities without additional processes. Specifically, the silicon particles may contain the metal impurities at 2,000 ppm or less. For example, the silicon particles may contain 1,000 ppm or less, or 500 ppm or less.

[0054] The silicon microparticles may be polycrystalline silicon and may have an average crystal grain size of 60 nm or less. The silicon particles produced by the above-mentioned production method may have the above-mentioned micro-sized particles and also crystal grains of 60 nm or less. This can provide excellent effects in necessary fields. For example, the silicon microparticles can be used as an anode material for lithium-ion batteries, and in this case, they can reduce particle damage due to volume changes that occur during battery charge and discharge, thereby improving capacity retention.

[0055] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples.

[0056] Example 1 Ar gas was introduced into the reactors to bring the reactors to a pressure of 5 bar and a temperature of 900° C. Then, a silane gas mixture of 3 mol % silane dichloride (SiH2Cl2, first silane gas, decomposition temperature = 599° C.) and 30 mol % silane trichloride (SiHCl3, second silane gas, decomposition temperature = 648° C.) together with 67 mol % hydrogen (H2) was simultaneously flowed into one reactor.

[0057] The silane gas mixture was reacted and decomposed in one reactor for about 40 minutes to produce micro-sized silicon particles. The internal temperature of the reactor was 900°C and the internal pressure was 5 bar. The produced silicon particles were then cooled and collected.

[0058] Comparative Example 1 Using a conventional FBR reaction method, silicon seed particles with a particle size of 600 μm were introduced into a reactor, and 33 mol% of trichlorosilane (SiHCl) was introduced into the reactor along with 67 mol% of hydrogen (H) to produce silicon particles. The internal temperature of the reactor was 900°C and the internal pressure was 5 bar.

[0059] Comparative Example 2 Metal silicon (MG-Si, Elpion, particles less than 45 μm classified with a sieve) was crushed using a ball mill (Zirconia) to have a size similar to that of Example 1.

[0060] Experimental Example 1: Silicon particle size The sizes of silicon particles in Example 1 and Comparative Example 2 were measured using a laser diffraction particle size analyzer (LS13 320, Beckman Coulter), and particles having a size in the millimeter range, such as in Comparative Example 1, were measured using a Digimatic caliper (Mitutoyo). The results are shown in Table 1 below.

[0061] [Table 1]

[0062] As can be seen from Table 1 above, it was confirmed that the silicon particles produced according to Example 1 were micro-sized. On the other hand, it was confirmed that the silicon particles produced using seed particles in Comparative Example 1 were large silicon particles of millimeter size.

[0063] Experimental Example 2: Metal impurity content The metal impurity contents of the silicon particles of Example 1 and Comparative Example 2 are shown in Table 2 below. The metal impurity contents were measured using Thermo Fisher's iCAP7600 equipment.

[0064] [Table 2]

[0065] As can be seen from Table 2 above, Comparative Example 2 was found to contain approximately 12,700 metal impurities. Thus, while it is possible to crush silicon particles to a size similar to that of Example 1, there is a problem with this method, which is that the impurity content increases. Example 1 does not require a separate crushing process, and silicon microparticles can be produced, with the impurity content reduced.

[0066] Experimental Example 3: Grain Size The average size of the crystal grains contained in the silicon particles produced according to the Examples and Comparative Examples was measured using XRD (Panalytical, Empyrean XRD), and the results are shown in Table 3 below.

[0067] [Table 3]

[0068] As can be seen from Table 3 above, it can be confirmed that the silicon particles of Example 1 contain small crystal grains.

[0069] Although the present specification has been described in detail above with reference to the examples and drawings, the present specification is not necessarily limited to these examples and drawings, and various modifications are possible within the scope of the technical concept of the present specification. Therefore, the examples disclosed in the present specification are intended to illustrate, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these examples. Therefore, it should be understood that all of the examples described above are illustrative and not limiting. The present specification and the scope of protection of the present invention should be interpreted by the scope of the claims, and any technical concept within the scope equivalent thereto should be interpreted as being included in the scope of the present specification and the present invention.

Claims

1. flowing a silane gas mixture into a reactor; decomposing the silane gas mixture in the reactor to produce silicon microparticles; Including, the silane gas mixture includes a first silane gas and a second silane gas; The decomposition temperature of the first silane gas is lower than the decomposition temperature of the second silane gas. Method for producing silicon microparticles.

2. The silane gas mixture is composed of two or more silane gases selected from silane gases represented by Chemical Formula 1 or Chemical Formula 2. The method for producing silicon microparticles according to claim 1 . (Chemical Formula 1) SiH ｘ Cl ４－ｘ (0≦x≦4, x is an integer.) (Chemical formula 2) Si ２ H ｙ Cl ６－ｙ (0≦y≦6, y is an integer.)

3. the first silane gas has a decomposition temperature of 350°C to 600°C; The second silane gas has a decomposition temperature of 600°C to 1,000°C. The method for producing silicon microparticles according to claim 1 .

4. The first silane gas and the second silane gas are flowed into the reactor at a molar ratio of 1:30 to 1:

2. The method for producing silicon microparticles according to claim 1 .

5. In one of the reactors, the silane gas mixture decomposes to produce silicon seed particles, which grow to produce silicon microparticles. The method for producing silicon microparticles according to claim 1 .

6. No silicon rods or silicon seed particles are used; The method for producing silicon microparticles according to claim 1 .

7. The silane gas mixture is allowed to remain in the reactor for 5 to 60 minutes to produce the silicon microparticles. The method for producing silicon microparticles according to claim 1 .

8. The temperature of the reactor is 700°C to 1,000°C and the pressure is 1 bar to 10 bar. The method for producing silicon microparticles according to claim 1 .

9. Produced by the method for producing silicon microparticles according to any one of claims 1 to 8. Silicon microparticles.

10. The silicon microparticles have a diameter of 1 μm<d １０ <4 μm, 2 μm<d ５０ < 7 μm, and 4 μm < d ９０ having a particle size of <13 μm, The total metal impurity content is 2,000 ppm or less; 10. Silicon microparticles according to claim 9.

11. The silicon microparticles have an average grain size of 60 nm or less.

10. Silicon microparticles according to claim 9.

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