JP4632292B2 - Spherical silicon fine particles and production method thereof - Google Patents

Description

  The present invention relates to a nanometer-sized spherical silicon fine particle, and more particularly to a silicon fine particle having a feature that the particle structure is amorphous or crystalline and the particle shape and surface state can be controlled, and a method for producing the same. Here, the nanometer size refers to a size having a particle size of 1000 nanometers (nm) or less, preferably 500 nm or less.

  As typical methods for producing nanometer-sized silicon fine particles, a gas phase method, laser ablation, anodization method, and the like are known.

  The gas phase method has long been used for the production of metal fine particles, and has been used for the production of many metal fine particles, particularly for the production of refractory metal fine particles such as Au, Ag and Cu. A typical particle size is 20 nm (nanometer) to 100 nm. The particle shape is close to a sphere.

  Laser ablation is a new manufacturing method, and finer silicon particles can be obtained. The particle size is 100 nm to 800 nm, and high-purity silicon fine particles can be obtained.

  The anodic oxidation method is a simple manufacturing method, and relatively fine silicon fine particles can be obtained. The particle size is about 100 nm.

  The conventional techniques, such as the gas phase method, laser ablation, and anodic oxidation method, each have problems, particularly in terms of cost and yield. In the vapor phase method, the metal fine particles which are easily oxidized, such as silicon, are severely oxidized and aggregated, and it is difficult to control the particle size of the fine particles and handle the metal fine particles. Laser ablation has the disadvantages that the device itself is expensive and the yield is extremely poor. The anodic oxidation method requires a chemical solution such as hydrofluoric acid for etching, and it is difficult to control impurities, control the particle size, and obtain a crystal structure. Therefore, there is a need to solve the above problems and to obtain silicon fine particles having nanometer size silicon fine particles, the inside of the particles having an amorphous or crystalline structure, the particle shape being nearly spherical, and the surface state being controllable. ing.

  Nanometer-sized spherical polycrystalline or amorphous silicon fine particles (hereinafter abbreviated as spherical silicon fine particles) according to the present invention are supplied as molten silicon on a dish-shaped disk that rotates at high speed, and centrifugal force is applied to cause the particles to scatter as small droplets. The silicon particles obtained by quenching in an active gas atmosphere are dispersed in a liquid medium, and the operation of pressurizing the dispersion and passing through a small-diameter nozzle is repeated.

  Nanometer-sized spherical silicon fine particles obtained by reheating the silicon fine particles described in claim 1 in an inert gas atmosphere are also included in the present invention.

  Further, spherical silicon fine particles which are further refined by repeating the surface oxidation of the spherical silicon fine particles obtained in claim 1 and the removal of the oxide film are also included in the present invention.

  The nanometer-sized spherical silicon fine particles according to claim 1 or 2, wherein the surface oxide film thickness and / or surface state are controlled by containing a trace amount of oxygen in the inert gas. include.

  Nanometer-sized silicon microparticles can be obtained that have an amorphous or crystalline structure inside the particles, a particle shape that is nearly spherical, and that has features that allow control of the surface state.

As a raw material, high-purity (for example, 11 nines) silicon is used. The first step for obtaining the nanometer-sized spherical silicon fine particles of the present invention is to supply molten silicon onto a dish-shaped disk that rotates at high speed, and to apply centrifugal force to disperse it as droplets and rapidly cool them in an inert gas atmosphere. It is to obtain silicon fine particles having a particle size of 10 to 50 μm (micrometer). This will be described in detail with reference to FIG. 1. The granulation chamber 1 has a cylindrical upper portion and a cone lower portion, and has a lid 2 on the upper portion. A nozzle 3 is inserted vertically in the center of the lid 2, and a dish-shaped rotating disk 4 is provided immediately below the nozzle 3. Reference numeral 5 denotes a mechanism for supporting the dish-shaped rotating disk 4 so as to be movable up and down. Further, a discharge pipe 6 for the generated particles is connected to the lower end of the cone portion of the granulating chamber 1. The upper part of the nozzle 3 is connected to an electric furnace (high frequency furnace) 7 for melting the metal to be granulated. The atmosphere gas adjusted to a predetermined component in the mixed gas tank 8 is supplied to the inside of the granulating chamber 1 and the upper part of the electric furnace 7 through the pipe 9 and the pipe 10, respectively. The pressure in the granulating chamber 1 is controlled by the valve 11 and the exhaust device 12, and the pressure in the electric furnace 7 is controlled by the valve 13 and the exhaust device 14, respectively. If the internal pressure of the electric furnace 7 is kept slightly higher than the atmospheric pressure and the internal pressure of the granulating chamber 1 is kept slightly lower than the atmospheric pressure, the metal melted in the electric furnace 7 is transferred from the nozzle 3 to the plate-shaped rotating disk 4 by the differential pressure. To be supplied. The supplied metal is dispersed in the form of fine droplets by the action of the centrifugal force by the dish-shaped rotating disk 4 and is cooled to solid particles. And now separated. Reference numeral 16 denotes a fine particle collecting apparatus.
JP 2001-254103 A

  Next, nanometer-sized spherical silicon fine particles are obtained by dispersing the silicon particles having a particle size of 10 to 50 μm thus obtained in a liquid medium, pressurizing the dispersion liquid, and passing through a small-diameter nozzle. It is done.

  Using the apparatus shown in FIG. 1, a silicon melt is supplied onto a dish-shaped desk having an inner diameter of 35 mm and a depth of 5 mm and rotating at high speed in an argon gas atmosphere with a chamber internal pressure of minus 0.3 MPa, and centrifugal force is applied. The particles were scattered as small droplets and rapidly cooled to obtain silicon particles having a particle size of 30 to 40 μm as shown in the electron micrograph of FIG. By dispersing 55 parts by weight of the silicon particles thus obtained in 45 parts by weight of isopropyl alcohol (IPA) as a liquid medium, and pressurizing the dispersion and passing through a small-diameter nozzle, the nanometer size is repeated. Spherical silicon fine particles were obtained. FIG. 3 shows a traveling electron micrograph (SEM) of silicon fine particles with a small-diameter nozzle passage 10 times, and FIG. 4 shows a transmission electron micrograph (TEM) of silicon fine particles with a passage number 30 times. It can be seen that the particle diameter gradually decreases as the number of repetitions increases.

  Nanometer-sized silicon microparticles can be obtained that have an amorphous or crystalline structure inside the particles, a particle shape that is nearly spherical, and that has features that allow control of the surface state.

It is explanatory drawing of the specific example of the apparatus used at the 1st step which manufactures the spherical silicon microparticles | fine-particles which concern on this invention. 3 is a traveling electron micrograph (SEM) of silicon particles obtained in the first stage of producing spherical silicon fine particles according to the present invention. It is a running electron micrograph (SEM figure) of the silicon fine particle with the small diameter nozzle passage number of 10 times. It is a transmission electron micrograph (TEM figure) of the silicon fine particle with the small diameter nozzle passing frequency of 30 times.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Powdering chamber 2 Lid 3 Nozzle 4 Rotary desk 5 Rotary desk support mechanism 6 Particle discharge pipe 7 Electric furnace 8 Mixed gas tank 9 Pipe 10 Pipe 11 Valve 12 Exhaust device 13 Valve 14 Vacuum pump 15 Automatic filter 16 Particulate collection device

Claims (3)

Silicon particles obtained by supplying molten silicon onto a dish disk rotating at high speed and applying centrifugal force to be dispersed as droplets and rapidly cooled in an inert gas atmosphere are dispersed in a liquid medium, and the dispersion is added. Including the step of repeating the operation of passing through the small diameter nozzle by pressing ,
A method for producing nanometer-sized spherical polycrystalline or amorphous silicon fine particles . A manufacturing method according to claim 1,
Further refinement by repeating the surface oxidation of the obtained spherical silicon fine particles and the removal of the oxide film ,
Production method. A manufacturing method according to claim 1 or 2,
Control the surface oxide film thickness and / or surface state by containing a trace amount of oxygen in the inert gas .
Production method.

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