Apparatus and method for coating particle

Abstract

To provide an apparatus and method for coating particles, capable of efficiently manufacturing particles covered with a coating film having a thin and uniform thickness.SOLUTION: An apparatus for coating particles, capable of forming a coating film on the particle surface of powder to be processed by an atomic layer deposition method includes: a processing chamber; a powder supply part including a front chamber for storing the powder to be processed and supplying the powder to be processed into the processing chamber in a state isolated from the open air; a supply switching part provided between the front chamber and the processing chamber and configured to switch the supply of the powder to be processed; a raw material gas supply part for supplying raw material gas into the processing chamber; an oxidizer supply part for supplying an oxidizer into the processing chamber; a processing chamber exhaust part for exhausting the inside of the processing chamber; and a powder layer holding part arranged into the processing chamber and configured to hold a powder layer obtained by spreading the powder to be processed supplied from the front chamber into a layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a particle coating apparatus and a particle coating method. [Background technology]

[0002] For magnetic powders used in inductors, etc., it is necessary to apply an insulating treatment to the particle surface to suppress eddy currents flowing between particles and to insulate terminals. For this reason, methods for forming insulating coatings on the particle surfaces of magnetic powders using various film-forming methods are being investigated.

[0003] For example, Patent Document 1 discloses a particle coating device that forms an insulating film on the surface of soft magnetic metal particles by atomic layer deposition (ALD), which is a type of chemical vapor deposition method. Atomic layer deposition makes it possible to form an insulating film that is thin and uniform in thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-085050 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 does not describe a method for supplying soft magnetic metal particles into a chamber. Therefore, the particle coating device described in Patent Document 1 cannot efficiently supply soft magnetic metal particles to be used for forming a coating. As a result, there is a problem in that the production efficiency of coated particles cannot be sufficiently improved. [Means for solving the problem]

[0006] A particle coating apparatus according to an embodiment of the present invention includes: A particle coating apparatus for forming a coating on a surface of a powder to be treated by an atomic layer deposition method, A processing chamber; a powder supply unit having a front chamber for accommodating the powder to be processed and supplying the powder to be processed into the processing chamber in a state isolated from outside air; a supply switching unit provided between the antechamber and the processing chamber for switching the supply of the powder to be processed; a raw material gas supply unit for supplying a raw material gas into the processing chamber; an oxidant supply unit for supplying an oxidant into the processing chamber; a processing chamber exhaust unit that exhausts the inside of the processing chamber; a powder layer holding section disposed within the processing chamber and holding a powder layer formed by laying the powder to be processed supplied from the anterior chamber in a layer shape; Equipped with.

[0007] A particle coating method according to an embodiment of the present invention includes the steps of: A particle coating method for forming a coating on a surface of a powder to be treated by atomic layer deposition, comprising the steps of: supplying the powder to be treated, which is contained in a front chamber airtightly connected to a treatment chamber, into the treatment chamber while being isolated from outside air; forming a powder layer by spreading the powder to be treated supplied into the treatment chamber in a layer shape; forming the coating on the powder layer by atomic layer deposition in the processing chamber; has. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a particle coating apparatus according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates an example of a coated particle produced by the particle coating apparatus illustrated in FIG. [Diagram 3] 1A to 1C are process diagrams illustrating a particle coating method according to an embodiment. [Figure 4] 1A to 1C are cross-sectional views showing an example of a method for forming a powder layer. [Diagram 5]1A to 1C are cross-sectional views showing an example of a method for forming a powder layer. [Figure 6] 1A to 1C are cross-sectional views showing an example of a method for forming a powder layer. [Figure 7] 1A to 1C are cross-sectional views showing an example of a method for forming a powder layer. [Figure 8] 1A to 1C are cross-sectional views showing an example of a method for forming a powder layer. [Figure 9] FIG. 13 is a perspective view showing a squeegee included in the particle coating apparatus according to the first modified example. [Figure 10] FIG. 11 is a cross-sectional view showing a processing chamber included in a particle coating apparatus according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the particle coating apparatus and particle coating method of the present invention will be described in detail with reference to the accompanying drawings.

[0010] 1.Particle coating equipment First, a particle coating apparatus according to an embodiment will be described.

[0011] FIG. 1 is a cross-sectional view showing a particle coating apparatus 1 according to an embodiment. FIG. 2 is a cross-sectional view showing a schematic example of a coated particle 93 produced by the particle coating apparatus 1 shown in FIG. 1. For convenience of explanation, in FIG. 1, an X-axis, a Y-axis, and a Z-axis are set as three mutually orthogonal axes, and each axis is indicated by an arrow. The Z-axis is a vertical axis, and the XY plane is a horizontal plane. The base end side of the arrow is referred to as the negative side of each axis, and the tip end side is referred to as the positive side of each axis.

[0012] The particle coating apparatus 1 shown in FIG. 1 is an apparatus for forming a coating 92 shown in FIG. 2 on the surface of a particle 91 by atomic layer deposition (ALD). In the following description, an aggregate of the particles 91 is referred to as a "powder to be processed". The particle coating apparatus 1 includes a processing chamber 11, a powder layer holding unit 12, a powder supply unit 13, a raw material gas supply unit 142, an oxidizing agent supply unit 144, a processing chamber exhaust unit 15, a processing chamber heating unit 16, a powder recovery unit 17, a supply switching unit 182, and a recovery switching unit 184. In the particle coating apparatus 1, the particles 91 of the powder to be processed are accommodated in the processing chamber 11, and after the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, the raw material gas supply unit 142 and the oxidizing agent supply unit 144 introduce the raw material gas G1 and the oxidizing agent G2. In addition, the particles 91 of the powder to be processed are heated by the processing chamber heating unit 16. The source gas G1 introduced into the treatment chamber 11 is decomposed, and the decomposition products are adsorbed on the surfaces of the particles 91 of the powder to be treated, ultimately forming a coating 92 as shown in Fig. 2. This results in the formation of coated particles 93 as shown in Fig. 2. In the following description, the collection of coated particles 93 is also referred to as the "treated powder."

[0013] The particle coating apparatus 1 shown in Fig. 1 is supplied with powder to be treated from a supply hopper 22. The supply hopper 22 is a portable container that contains the powder to be treated. The treated powder obtained in the particle coating apparatus 1 shown in Fig. 1 is discharged to and collected in a recovery hopper 24. The recovery hopper 24 is a portable container that contains the treated powder.

[0014] The treatment chamber 11 is a rigid and airtight container in which the powder to be treated is accommodated and a coating 92 is formed on the surfaces of particles 91 of the powder to be treated. The treatment chamber 11 maintains a reduced pressure state by evacuating the inside. Examples of materials constituting the treatment chamber 11 include glass materials such as quartz glass, ceramic materials such as alumina, and metal materials such as stainless steel, aluminum, and titanium.

[0015] The powder layer holding unit 12 is disposed in the processing chamber 11, and holds the powder to be processed supplied from the powder supply unit 13 in a layered state, specifically, in the state of the powder layer 90 shown in FIG. 1. Holding means maintaining the relative positions of the particles 91 so as not to change, specifically, meaning that the powder layer 90 is left stationary. The powder layer holding unit 12 shown in FIG. 1 has a powder layer forming unit 12A and a powder layer discharging unit 12B. Of these, the powder layer forming unit 12A has a frame 122 and a stage 126. On the other hand, the powder layer discharging unit 12B has a squeegee 124.

[0016] The frame 122 is provided in the treatment chamber 11, and is a wall that rises from the bottom surface and has a closed ring shape when viewed vertically from above. A space for accommodating the powder to be treated is formed inside the frame 122.

[0017] The squeegee 124 moves in the X-axis direction along the upper end of the frame 122. The movement of the squeegee 124 shapes the upper surface of the powder to be processed housed inside the frame 122. The processed powder protruding upward from the upper end of the frame 122 is dragged sideways and discharged outside the frame 122. The discharged processed powder falls inside the treatment chamber 11 and is collected by powder collection unit 17 arranged below the treatment chamber 11.

[0018] The stage 126 is disposed inside the frame 122 and moves up and down, thereby pushing up the powder to be processed contained inside the frame 122 from below, and a new powder layer 90 can be formed.

[0019] According to the powder layer holding unit 12 configured as above, the process of holding the powder to be processed in a layer and then discharging the processed powder can be easily repeated. Therefore, the processed powder can be produced continuously and efficiently. The configuration of the powder layer holding unit 12 is not limited to the above. For example, the powder layer forming unit 12A may be configured to include a roller or the like and to level the powder to be processed to form the powder layer 90. Moreover, the powder layer discharging unit 12B may be configured to discharge the processed powder by a roller, a blower, or the like.

[0020] A raw gas supply unit 142 and an oxidizing agent supply unit 144 are connected to the processing chamber 11. The raw gas supply unit 142 supplies the raw gas G1 required for forming the coating 92 into the processing chamber 11 and adjusts the partial pressure of the raw gas G1 in the processing chamber 11. The raw gas supply unit 142 includes, for example, a raw gas storage unit, a pipe, a flow rate control valve, and the like. The oxidizing agent supply unit 144 supplies the oxidizing agent G2 required for forming the coating 92 into the processing chamber 11 and adjusts the partial pressure of the oxidizing agent G2 in the processing chamber 11. The oxidizing agent supply unit 144 includes, for example, an oxidizing agent storage unit, a pipe, a flow rate control valve, and the like. Note that in FIG. 1, ozone O3 is illustrated as an example of the oxidizing agent G2. By using ozone as the oxidizing agent G2, the coating 92 that is denser and has a uniform thickness can be formed more efficiently. The source gas G1 and the oxidizing agent G2 are supplied, if necessary, together with a carrier gas mainly composed of an inert gas such as nitrogen gas or argon gas.

[0021] The processing chamber exhaust unit 15 exhausts the inside of the processing chamber 11. This makes it possible to reduce the pressure inside the processing chamber 11. The processing chamber exhaust unit 15 includes, for example, a vacuum pump, a pressure gauge, piping, an exhaust valve, and the like.

[0022] The treatment chamber heating unit 16 heats the treatment chamber 11, and thus heats the powder layer 90. Examples of the treatment chamber heating unit 16 include a heater block, a film heater, a sheet heater, a sheath heater, and an infrared radiation heater. In FIG. 1, the treatment chamber heating unit 16 is disposed outside the treatment chamber 11, but the location of the treatment chamber heating unit 16 is not limited thereto. The treatment chamber heating unit 16 may be disposed inside the treatment chamber 11, or may be built into a wall that constitutes the treatment chamber 11. The treatment chamber heating unit 16 may be provided as necessary, and may be omitted.

[0023] By providing such a processing chamber heating unit 16, the temperature of the powder layer 90, the temperature of the source gas G1, and the temperature of the oxidizing agent G2 can be optimized, so that a denser coating 92 with a uniform thickness can be formed more efficiently.

[0024] The powder supplying unit 13 has an antechamber 132 disposed above the processing chamber 11. The antechamber 132 is a rigid and airtight container that contains the powder to be processed. The antechamber 132 maintains a reduced pressure state by evacuating the inside. Examples of materials that can be used to construct the antechamber 132 include glass materials such as quartz glass, ceramic materials such as alumina, and metal materials such as stainless steel, aluminum, and titanium.

[0025] Moreover, the powder supplying unit 13 has a front chamber exhaust unit 133 that exhausts the front chamber 132. The front chamber exhaust unit 133 includes, for example, a vacuum pump, a pressure gauge, piping, an exhaust valve, and the like.

[0026] Furthermore, the powder supplying unit 13 has a front chamber heating unit 134 that heats the front chamber 132. Examples of the front chamber heating unit 134 include the various heaters described above. In FIG. 1, the front chamber heating unit 134 is disposed outside the front chamber 132, but the location of the front chamber heating unit 134 is not limited thereto. The front chamber heating unit 134 may be disposed inside the front chamber 132, or may be built into a wall that constitutes the front chamber 132. Note that the front chamber heating unit 134 may be provided as necessary, and may be omitted.

[0027] A supply switching unit 182 is provided between the front chamber 132 and the processing chamber 11. The supply switching unit 182 has a function of switching the supply when the powder to be processed contained in the front chamber 132 is supplied into the processing chamber 11. Specifically, the supply switching unit 182 has a flow path through which the powder to be processed passes while the front chamber 132 and the processing chamber 11 are airtightly connected, and a gate valve for opening and closing the flow path. In this way, the front chamber 132, the processing chamber 11, and the supply switching unit 182 are provided with a so-called load lock mechanism. Through the supply switching unit 182, the powder supply unit 13 can supply the powder to be processed into the processing chamber 11 while being isolated from the outside air. The gate valve is operated manually or electrically. By opening the gate valve, the powder to be processed passes through the flow path and is supplied. Also, by closing the gate valve, the supply of the powder to be processed is stopped.

[0028] The powder recovery section 17 has a recovery chamber 172 disposed outside the treatment chamber 11 and below the treatment chamber 11. The recovery chamber 172 is a rigid and airtight container that contains the treated powder. The recovery chamber 172 maintains a reduced pressure state by evacuating the inside. Examples of materials that can be used to make the recovery chamber 172 include glass materials such as quartz glass, ceramic materials such as alumina, and metal materials such as stainless steel, aluminum, and titanium.

[0029] Moreover, the powder recovery unit 17 has a recovery chamber exhaust unit 173 that exhausts the recovery chamber 172. The recovery chamber exhaust unit 173 includes, for example, a vacuum pump, a pressure gauge, piping, an exhaust valve, and the like.

[0030] Furthermore, the powder collection unit 17 has a collection chamber cooling unit 174 that cools the collection chamber 172. Examples of the collection chamber cooling unit 174 include a water-cooled cooler, an air-cooled cooler, and a Peltier element. In FIG. 1, the collection chamber cooling unit 174 is disposed outside the collection chamber 172, but the location of the collection chamber cooling unit 174 is not limited thereto. The collection chamber cooling unit 174 may be disposed inside the collection chamber 172, or may be built into a wall that constitutes the collection chamber 172. The collection chamber cooling unit 174 may be provided as necessary, and may be omitted.

[0031] Between the processing chamber 11 and the recovery chamber 172, a recovery switching unit 184 is provided. The recovery switching unit 184 has a function of switching the recovery when the processed powder obtained in the processing chamber 11 is recovered into the recovery chamber 172. Specifically, the recovery switching unit 184 has a flow path through which the processed powder passes while the processing chamber 11 and the recovery chamber 172 are airtightly connected, and a gate valve for opening and closing the flow path. In this way, the processing chamber 11, the recovery chamber 172, and the recovery switching unit 184 are provided with a so-called load lock mechanism. Through the recovery switching unit 184, the powder recovery unit 17 can recover the processed powder into the recovery chamber 172 while being isolated from the outside air. The gate valve is operated manually or electrically. By opening the gate valve, the processed powder passes through the flow path and is recovered. Also, by closing the gate valve, the recovery of the processed powder is stopped.

[0032] The particle coating apparatus 1 shown in FIG. 1 further includes a supply hopper opening / closing section 186 and a recovery hopper opening / closing section 188 .

[0033] Supply hopper opening / closing unit 186 is provided between supply hopper 22 and powder supply unit 13. Supply hopper opening / closing unit 186 has a function of opening and closing a flow path that supplies the powder to be processed contained in supply hopper 22 into front chamber 132. Supply hopper opening / closing unit 186 specifically has a flow path through which the powder to be processed passes, and a gate valve that opens and closes the flow path. The gate valve is operated manually or electrically.

[0034] Collection hopper opening / closing unit 188 is provided between powder collection unit 17 and collection hopper 24. Collection hopper opening / closing unit 188 has a function of opening and closing a flow path for discharging the processed powder stored in collection chamber 172 to collection hopper 24. Collection hopper opening / closing unit 188 specifically has a flow path through which the processed powder passes, and a gate valve for opening and closing the flow path. The gate valve is operated manually or electrically.

[0035] 2. Powder to be treated Next, the powder to be treated will be described. A coated particle 93 shown in FIG. 2 has a particle 91 of the powder to be treated and a coating 92 .

[0036] The constituent material of the particles 91 (constituent material of the powder to be processed) is not particularly limited, and examples thereof include metal materials, ceramic materials, glass materials, silicon materials, carbon materials, and resin materials. Among these, the constituent material of the particles 91 may be a soft magnetic metal material. When the particles 91 made of a soft magnetic metal material are used in a magnetic element such as an inductor, it is necessary to ensure insulation between the particles 91. By using the above-mentioned particle coating device 1, it is possible to form a coating 92 that is sufficiently thin in thickness and has a high coverage rate. This allows the formation of coated particles 93 that can improve the magnetic properties and insulating properties of the magnetic element. In addition, the coating 92 formed by the atomic layer deposition method is dense, and therefore contributes to the realization of coated particles 93 with high insulating properties, for example.

[0037] Examples of soft magnetic metal materials include Fe-Si alloys such as pure iron and silicon steel, Fe-Ni alloys such as permalloy, Fe-Co alloys such as permendur, Fe-Si-Al alloys such as sendust, Fe-Cr-Si alloys, and other Fe-based alloys, as well as various Ni-based alloys, various Co-based alloys, and various amorphous alloys. Among these, examples of amorphous alloys include Fe-based alloys such as Fe-Si-B, Fe-Si-BC, Fe-Si-B-Cr-C, Fe-Si-Cr, Fe-B, Fe-PC, Fe-Co-Si-B, Fe-Si-B-Nb, and Fe-Zr-B, Ni-based alloys such as Ni-Si-B and Ni-PB, and Co-based alloys such as Co-Si-B.

[0038] The average particle size D50 of the particles 91 is not particularly limited, but is preferably 0.1 μm or more and 50.0 μm or less, more preferably 0.5 μm or more and 10.0 μm or less, and even more preferably 1.0 μm or more and 3.5 μm or less. The average particle size D50 of the particles 91 is determined as the particle size at which the cumulative amount from the small diameter side becomes 50% in the cumulative particle size distribution on a volume basis obtained by a laser diffraction method.

[0039] 3. Particle coating method Next, a particle coating method according to an embodiment will be described. FIG. 3 is a process diagram showing the particle coating method according to the embodiment.

[0040] 3 includes a powder supply step S102, a powder layer forming step S104, a film forming step S106, and a recovery step S 108. In the following description, a method using the above-described particle coating apparatus 1 will be described as an example, but the particle coating method according to the present invention may also be a method using an apparatus other than the particle coating apparatus 1.

[0041] 3.1. Supplying powder to be treated In the step S102 of feeding the powder to be treated, the feed hopper opening / closing part 186 is opened, and the powder to be treated is transferred from the feed hopper 22 into the front chamber 132. After a predetermined amount of the powder to be treated has been transferred, the feed hopper opening / closing part 186 is closed.

[0042] Thereafter, the inside of the anterior chamber 132 may be evacuated and depressurized as necessary. The pressure inside the anterior chamber 132 is not particularly limited, but is preferably 10 kPa or less, and more preferably 1 kPa or less. This makes it possible to suppress the remaining oxygen and moisture inside the anterior chamber 132, and more reliably suppress oxidation and deterioration of the powder to be treated contained in the anterior chamber 132. It is not necessary to set a lower limit for the pressure inside the anterior chamber 132, but taking into consideration the increased cost of maintaining a reduced pressure state and the possibility that the effects of reducing the pressure may not be fully obtained, a lower limit of 1×10 -5 Pa or more, and 1×10 -3 It is more preferable that the pressure is 100 Pa or more.

[0043] The powder to be treated contained in the anterior chamber 132 may be heated as necessary. The heating temperature of the powder to be treated is not particularly limited, but is preferably 30° C. or higher and 500° C. or lower, and more preferably 50° C. or higher and 300° C. or lower. This allows the powder to be sufficiently preheated. As a result, in the film-forming step S106 described below, the coating 92 can be formed with a more uniform film thickness.

[0044] Next, the supply switching unit 182 is opened, and the powder to be processed contained in the front chamber 132 is supplied into the processing chamber 11. Since the powder to be processed is supplied via the supply switching unit 182, it can be supplied in an environment isolated from the outside air. This makes it possible to suppress oxidation and deterioration of the powder to be processed that would otherwise occur due to contact with the outside air.

[0045] In this embodiment, the powder to be processed is supplied inside the frame 122. This makes it possible to hold the powder to be processed within a predetermined range within the processing chamber 11. As a result, in the film-forming step S106 described below, the powder to be processed can be kept within a range suitable for film formation, making it possible to form the coating 92 with a more uniform film thickness.

[0046] When the supply switching unit 182 is opened, it is preferable to evacuate the front chamber 132 beforehand. This makes it possible to supply the powder to be treated without returning the inside of the treatment chamber 11 to atmospheric pressure when the inside of the treatment chamber 11 is depressurized. As a result, the time and cost required for depressurization can be saved, and the coated particles 93 can be produced more quickly and at lower cost. At this time, it is also preferable to keep the pressure difference between the front chamber 132 and the treatment chamber 11 close to zero. This makes it possible to prevent the powder to be treated from flying up due to the pressure difference. After the powder to be treated has been supplied, the supply switching unit 182 is closed.

[0047] 3.2. Powder layer formation step In the powder layer forming step S104, the powder layer 90 is formed by spreading the powder to be processed supplied into the processing chamber 11 in a layer shape. The powder layer 90 is formed, for example, as follows. 4 to 8 are cross-sectional views showing an example of a method for forming the powder layer 90. FIG.

[0048] 4, the powder to be processed (particles 91) is supplied inside the frame 122. The amount of the powder to be processed supplied is preferably equal to or greater than the inner volume of the frame 122.

[0049] Next, as shown in Fig. 5, the squeegee 124 is moved to level the upper surface of the powder to be processed. This makes it possible to flatten the upper surface of the powder to be processed. As a result, the vicinity of the upper surface of the powder to be processed becomes a powder layer 90 to be subjected to a film forming process described later. The powder layer 90 is supported and held by the frame 122.

[0050] The method for forming the powder layer 90 is not limited to the above method. For example, the powder layer 90 may be formed by leveling the powder to be treated by applying vibration or the like.

[0051] Furthermore, the powder layer 90 may be subjected to a pretreatment prior to the formation of the coating 92 described below. Examples of the pretreatment include ozone treatment, radical treatment, ultraviolet treatment, plasma treatment, corona treatment, drying treatment, and solvent treatment. The pretreatment may be performed in the antechamber 132.

[0052] 3.3. Film formation step In the film forming step S106, a coating 92 is formed on the powder layer 90 by atomic layer deposition in the processing chamber 11. The coating 92 is formed, for example, as follows.

[0053] First, the powder to be treated contained in the treatment chamber 11 is heated. This heating may be performed so as to overlap in time with the formation of the coating 92 described below, or may be performed separately from the film formation, i.e., without overlapping in time. Furthermore, heating of the powder to be treated may be performed as necessary, and may be omitted.

[0054] The heating temperature is not particularly limited, but is preferably 30° C. to 500° C., more preferably 80° C. to 300° C. In particular, when the constituent material of the particles 91 is a material with low heat resistance such as a resin material, the heating temperature is preferably 30° C. to 150° C., more preferably 30° C. to 100° C. In addition, the heating time at such a heating temperature is appropriately set according to the film thickness of the coating 92, but is preferably 0.1 hours to 300 hours, more preferably 1 hour to 200 hours, and even more preferably 5 hours to 100 hours.

[0055] The pressure in the processing chamber 11 before the introduction of the source gas G1 and the oxidizing agent G2 is not particularly limited, but is preferably 10 kPa or less, and more preferably 1 kPa or less. This makes it possible to suppress residual oxygen and moisture in the processing chamber 11. In addition, the lower limit of the pressure in the processing chamber 11 does not need to be set in particular, but considering the increase in the cost of maintaining a reduced pressure state and the possibility that the effects of the reduced pressure may not be fully obtained, it is preferable to set the lower limit to 1×10 -5 Pa or more, and 1×10 -3 It is more preferable that the pressure is 100 Pa or more.

[0056] Next, the raw material gas G1 is introduced into the processing chamber 11 by the raw material gas supply unit 142. The introduced raw material gas G1 is adsorbed to the surface of the particles 91 of the powder to be processed. At this time, once the raw material gas G1 is adsorbed to the surface of the particles 91, it is difficult for it to be further adsorbed in multiple layers. This makes it possible to control the thickness of the coating 92 to be finally obtained with high precision. In addition, the raw material gas G1 is adsorbed by wrapping around the portions that are in the shadows or gaps. Therefore, the thickness of the powder layer 90 shown in FIG. 1 corresponds to the depth that the raw material gas G1 can penetrate from the top surface of the leveled powder to be processed.

[0057] The source gas G1 may be, for example, a gas containing a precursor of the coating 92. Specifically, when forming a silicon oxide-based coating 92, examples of the source gas G1 include dimethylaminosilane, methylethylaminosilane, diethylaminosilane, trisdimethylaminosilane, bisdiethylaminosilane, and bistertiarybutylaminosilane.

[0058] Examples of the material of the coating 92 that is formed include, in addition to silicon oxide, oxides such as hafnium oxide, tantalum oxide, titanium oxide, and chromium oxide, and nitrides such as aluminum nitride, titanium nitride, and tantalum nitride.

[0059] Next, the source gas G1 in the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, and then an inert gas such as nitrogen or argon is introduced as necessary. This replaces the source gas G1. Although not shown, the inert gas can be introduced in the same manner as the introduction of the source gas G1 and the oxidizing agent G2.

[0060] Next, the inert gas in the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, and then the oxidizing agent G2 is introduced into the processing chamber 11 by the oxidizing agent supply unit 144. Examples of the oxidizing agent G2 include ozone shown in FIG. 1, plasma oxygen, water vapor, and the like.

[0061] The oxidizing agent G2 reacts with the source gas G1 adsorbed on the surface of the particles 91 of the powder to be treated, forming a coating 92. Like the source gas G1, the oxidizing agent G2 also gets into the shaded areas and gaps. Therefore, the thickness of the powder layer 90 shown in FIG. 1 corresponds to the depth that the oxidizing agent G2 can penetrate from the top surface of the leveled powder to be treated.

[0062] Next, the oxidizing agent G2 in the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, and then an inert gas is introduced to replace the oxidizing agent G2, if necessary. In this manner, the coating 92 is formed, and coated particles 93 are obtained. The powder layer composed of the coated particles 93 is referred to as the powder layer 95 shown in FIG. 6.

[0063] Depending on the target thickness of the coating 92, the introduction and discharge of the source gas G1 and the introduction and discharge of the oxidizing agent G2 may be repeated. The thickness of the coating 92 can be increased depending on the number of times the introduction and discharge are repeated. This makes it easy to obtain the desired thickness of the coating 92.

[0064] Thereafter, if necessary, post-treatment may be performed on the coated particles 93. Examples of the post-treatment include a charge removal treatment and a radical treatment.

[0065] Among these, the charge removal process is a process for reducing the amount of charge caused by the electrostatic charge of the coated particles 93. For example, an ionizer is used for the charge removal process.

[0066] The thickness of the coating 92 is not particularly limited, but is preferably 1 nm to 500 nm, more preferably 2 nm to 300 nm, and even more preferably 4 nm to 200 nm. Such a thickness allows the coating 92 to be formed uniformly in a relatively short time. Furthermore, the atomic layer deposition method allows the formation of a dense coating 92, so that even a thin coating of this thickness has sufficient insulating ability. In this case, the coating 92 has good insulating properties. The thickness of the coating 92 is the average value of measurements taken at five or more points by enlarging and observing the cross section of the coated particle 93.

[0067] The formation of the coating 92 as described above is performed while the powder layer 90 is left stationary. Therefore, the coating 92 can be formed with a uniform thickness.

[0068] 3.4. Collection step In the recovery step S108, first, the stage 126 is raised as shown in Fig. 7. This makes it possible to push the powder layer 95 on which the coating 92 has been formed above the frame 122.

[0069] Next, as shown in Fig. 8, the powder layer 95 is dragged to the side by the squeegee 124. This allows the powder layer 95 to be discharged to the outside of the frame 122. The discharged treated powder (coated particles 93) falls inside the treatment chamber 11 and accumulates on the recovery switching unit 184. Note that "to the side" refers to any direction along a horizontal plane. Also, "discharging" refers to moving the powder layer 95 to free up the film formation area (the space where the powder layer 95 was previously present).

[0070] Next, the recovery switching unit 184 is opened, and the treated powder is recovered into the recovery chamber 172. Since the treated powder is recovered via the recovery switching unit 184, it can be recovered in an environment isolated from the outside air. This makes it possible to suppress oxidation and deterioration of the treated powder due to contact with the outside air.

[0071] When opening the recovery switching unit 184, it is preferable to evacuate the inside of the recovery chamber 172 beforehand. This makes it possible to recover the treated powder without returning the inside of the treatment chamber 11 to atmospheric pressure. As a result, the time and cost required for depressurization can be saved, and the coated particles 93 can be produced more quickly and at lower cost. At this time, it is also preferable to keep the pressure difference between the inside of the treatment chamber 11 and the inside of the recovery chamber 172 close to zero. This makes it possible to prevent the treated powder from flying up due to the pressure difference. After the treated powder has been collected, the collection switch 184 is closed.

[0072] The pressure in the recovery chamber 172 is not particularly limited, but is preferably 10 kPa or less, and more preferably 1 kPa or less. This makes it possible to suppress residual oxygen and moisture in the recovery chamber 172, and more reliably suppress oxidation and deterioration of the treated powder recovered in the recovery chamber 172. It is not necessary to set a lower limit for the pressure in the recovery chamber 172, but taking into consideration the increased cost of maintaining a reduced pressure state and the possibility that the effects of reducing the pressure may not be fully obtained, a lower limit of 1×10 -5 Pa or more, and 1×10 -3 It is more preferable that the pressure is 100 Pa or more.

[0073] The treated powder collected in the collection chamber 172 may be cooled by the collection chamber cooling section 174 as necessary. This allows the temperature of the treated powder to be lowered, and prevents the high-temperature treated powder from deteriorating due to exposure to the atmosphere. In addition, the time required for the treated powder to be exposed to the atmosphere can be shortened.

[0074] After the treated powder has dissipated heat, the recovery chamber 172 is returned to atmospheric pressure. Then, the recovery hopper opening / closing portion 188 is opened, and the treated powder is transferred from the recovery chamber 172 to the recovery hopper 24. After the treated powder has been transferred, the recovery hopper opening / closing portion 188 is closed. In this manner, the treated powder (coated particles 93) can be collected.

[0075] 4. Variations Next, a particle coating apparatus 1 according to a first modified example of the above embodiment will be described.

[0076] FIG. 9 is a perspective view showing a squeegee 124 provided in the particle coating apparatus 1 according to the first modified example.

[0077] The first modified example will be described below, but in the following description, the differences from the above embodiment will be mainly described, and a description of similar points will be omitted.

[0078] The first modified example is similar to the above embodiment except that the shape of the squeegee 124 is different. The squeegee 124 shown in Fig. 9 is in the form of a plate extending along the Y axis and moves along the X axis. This flattens the powder while forming an upper surface along the XY plane of the powder to be processed. As a result, a powder layer 90 having this upper surface is obtained.

[0079] Squeegee 124 shown in FIG. 9 has ridges 125. The shape of ridges 125 is reflected on the upper surface of powder layer 90. Ridges 125 shown in FIG. 9 are corrugated. Therefore, when squeegee 124 having ridges 125 shown in FIG. 9 is dragged and powder layer 95 is discharged, powder layer 90 having a corrugated upper surface can be newly formed. In other words, the shape left on the upper surface (surface) of powder layer 90 by squeegee 124 has a shape including ridges 901 or grooves 902 extending along the X-axis.

[0080] By using a squeegee 124 having such wavy ridges 125, the surface area of ​​the upper surface of the powder layer 90 can be made larger than in the case of using a squeegee having straight ridges, for example. This allows the source gas G1 and the oxidizing agent G2 to penetrate deeper when forming the coating 92 on the powder layer 90. As a result, it is possible to increase the amount of treated powder that can be produced at one time and to increase the production speed of the treated powder.

[0081] The shape of the ridge 125 is not limited to the waveform shown in Fig. 9, and may be any shape that includes the ridges 901 or grooves 902 left on the top surface of the powder layer 90 by the squeegee 124. In other words, the ridges may not be straight, and may have any shape that includes some convex or concave portion. However, in order to make the permeation amount of the source gas G1 and the oxidizing agent G2 uniform, it is preferable that the shape be a repeating pattern as shown in Fig. 9. In addition, the powder layer 90 may have the ridges 901 or grooves 902, but it is preferable that the powder layer 90 has both of these in terms of increasing the surface area.

[0082] Fig. 10 is a cross-sectional view showing a processing chamber 11 included in a particle coating apparatus 1 according to a second modified example. Note that in Fig. 10, some components are not shown.

[0083] The second modified example will be described below, but in the following description, the differences from the above embodiment will be mainly described, and a description of similar points will be omitted.

[0084] The second modified example is similar to the above embodiment, except that the oxidizing agent supply unit 144 includes an oxygen gas supply unit 146 and a plasma generation unit 148 shown in FIG.

[0085] The oxygen gas supply unit 146 supplies oxygen gas G3 required for generating plasma oxygen into the processing chamber 11, and adjusts the partial pressure of the oxygen gas G3 in the processing chamber 11. The oxygen gas supply unit 146 includes, for example, an oxygen gas storage unit, a pipe, a flow rate adjustment valve, and the like.

[0086] The plasma generating unit 148 has an upper electrode 148a, a lower electrode 148b, and a high-frequency power supply 148c. The upper electrode 148a is disposed at the top of the processing chamber 11 and is connected to the high-frequency power supply 148c. The lower electrode 148b is disposed inside the frame 122 and is grounded.

[0087] Oxygen gas G3 is supplied into the processing chamber 11 by the oxygen gas supply unit 146, and in this state, the oxygen gas G3 is converted into plasma oxygen by the plasma generation unit 148. That is, plasma oxygen is generated in the processing chamber 11. As a result, the plasma oxygen generated in the processing chamber 11 can be used as the oxidizing agent G2. By using plasma oxygen as the oxidizing agent G2, the temperature when the coating 92 is formed can be lowered. That is, the coating can be formed at a lower temperature. As a result, even if the heat resistance of the constituent material of the particles 91 is low, it can be used to form the coating 92.

[0088] Alternatively, the lower electrode 148b may be connected to a high-frequency power source 148c, and the upper electrode 148a may be grounded.

[0089] Alternatively, the upper electrode 148a and the lower electrode 148b may both be connected to the high frequency power supply 148c so that they have opposite polarities. In this case, the generated plasma oxygen can be drawn to the lower electrode 148b side. This allows the plasma oxygen as the oxidizer G2 to penetrate deeper into the powder layer 90. As a result, the amount of treated powder that can be produced at one time can be increased, and the production efficiency of the treated powder can be improved. In the above modified example, the same effects as those of the above embodiment can be obtained.

[0090] 5. Effects of the above embodiment or the above modification As described above, the particle coating apparatus 1 according to the embodiment or the modified example is an apparatus for forming a coating 92 on the surface of a particle 91 of a powder to be processed by atomic layer deposition, and includes a processing chamber 11, a powder supply unit 13, a supply switching unit 182, a raw material gas supply unit 142, an oxidizing agent supply unit 144, a processing chamber exhaust unit 15, and a powder layer holding unit 12. The powder supply unit 13 has a front chamber 132 for accommodating the powder to be processed, and supplies the powder to be processed into the processing chamber 11 in a state isolated from the outside air. The supply switching unit 182 is provided between the front chamber 132 and the processing chamber 11, and switches the supply of the powder to be processed. The raw material gas supply unit 142 supplies a raw material gas G1 into the processing chamber 11. The oxidizing agent supply unit 144 supplies an oxidizing agent G2 into the processing chamber 11. The processing chamber exhaust unit 15 exhausts the inside of the processing chamber 11. The powder layer holding unit 12 is disposed in the treatment chamber 11 and holds a powder layer 90 in which the powder to be treated supplied from the front chamber 132 is laid out in a layer shape.

[0091] According to this configuration, the powder layer 90 is left stationary while the coating 92 is formed, so that the coating 92 can be formed with a uniform thickness. Furthermore, the powder supplying unit 13 can supply the powder to be processed into the processing chamber 11 while maintaining the airtightness of the front chamber 132 that contains the powder to be processed, so that, for example, by reducing the pressure inside the front chamber 132, the powder to be processed can be supplied without returning the pressure inside the processing chamber 11 to atmospheric pressure. Therefore, according to the above configuration, it is possible to obtain the particle coating device 1 that can efficiently produce particles 91 coated with a thin coating 92 with a uniform thickness, i.e., coated particles 93.

[0092] In the particle coating apparatus 1, the powder layer holding unit 12 may have a powder layer forming unit 12A and a powder layer discharging unit 12B. The powder layer forming unit 12A has a frame 122 that houses the powder to be treated before the coating 92 is formed thereon, and supports the powder to be treated with the frame 122 to form a powder layer 90 before the coating 92 is formed. The powder layer discharging unit 12B has a squeegee 124, and discharges the powder layer 95 after the coating 92 is formed from the powder layer forming unit 12A by dragging the powder layer 95 after the coating 92 is formed laterally with the squeegee 124.

[0093] According to this configuration, the powder layer 95 after the coating 92 is formed can be produced continuously and efficiently.

[0094] Moreover, in the particle coating apparatus 1, the squeegee 124 has a ridge 125 that comes into contact with the powder to be treated when dragging the powder layer 95. This ridge 125 may be configured so that the shape left on the surface of the powder to be treated dragged by the squeegee 124 includes a convex ridge or a groove.

[0095] According to this configuration, it is possible to form a powder layer 90 with a large surface area. This allows the source gas G1 and the oxidizing agent G2 to penetrate deeper when forming a coating 92 on the powder layer 90. As a result, it is possible to increase the amount of treated powder that can be produced at one time and to improve the production efficiency of the treated powder.

[0096] Alternatively, the oxidizing agent G2 may be ozone. In this case, the particle coating apparatus 1 may further include a processing chamber heating unit 16. The processing chamber heating unit 16 heats the powder layer 90.

[0097] According to this configuration, a denser coating 92 with a uniform thickness can be formed more efficiently.

[0098] The oxidizing agent G2 may be plasma oxygen. In this case, the oxidizing agent supply unit 144 may include an oxygen gas supply unit 146 and a plasma generation unit 148. The oxygen gas supply unit 146 supplies oxygen gas G3 into the processing chamber 11. The plasma generation unit 148 changes the oxygen gas G3 into plasma oxygen.

[0099] According to this configuration, plasma oxygen can be used as the oxidizing agent G2, which allows the temperature at which the coating 92 is formed to be lowered. In other words, the coating can be formed at a lower temperature. This allows the coating 92 to be formed even if the material constituting the particles 91 has low heat resistance.

[0100] The particle coating apparatus 1 may further include a powder recovery unit 17 and a recovery switching unit 184. The powder recovery unit 17 is provided outside the processing chamber 11 and recovers the powder layer 95 after the coating 92 is formed in a state isolated from the outside air. The recovery switching unit 184 is provided between the processing chamber 11 and the powder recovery unit 17 and switches the recovery of the powder layer 95.

[0101] According to such a configuration, for example, by reducing the pressure inside the recovery chamber 172, it becomes possible to recover the treated powder without returning the pressure inside the treatment chamber 11 to atmospheric pressure.

[0102] The particle coating method according to the embodiment or the modified example is a method for forming a coating 92 on the surface of a particle 91 of a powder to be processed by atomic layer deposition, and includes a powder supply step S102, a powder layer forming step S104, and a coating step S106. In the powder supply step S102, the powder to be processed contained in a front chamber 132 airtightly connected to the processing chamber 11 is supplied into the processing chamber 11 in a state isolated from the outside air. In the powder layer forming step S104, the powder to be processed supplied into the processing chamber 11 is laid in layers to form a powder layer 90. In the coating step S106, a coating 92 is formed on the powder layer 90 by atomic layer deposition in the processing chamber 11.

[0103] According to this configuration, the powder layer 90 is left stationary while the coating 92 is formed, so that the coating 92 can be formed with a uniform thickness. Furthermore, the powder supplying unit 13 can supply the powder to be processed into the treatment chamber 11 while maintaining the airtightness of the front chamber 132 that contains the powder to be processed, so that, for example, by reducing the pressure inside the front chamber 132, the powder to be processed can be supplied without returning the pressure inside the treatment chamber 11 to atmospheric pressure. Therefore, according to the above configuration, particles 91 covered with a thin coating 92 with a uniform thickness, i.e., coated particles 93, can be efficiently produced.

[0104] Furthermore, the step of supplying the powder to be processed S102 (the step of supplying the powder to be processed into the processing chamber 11) may include an operation of supplying the powder to be processed inside the frame 122 arranged in the processing chamber 11.

[0105] According to such a configuration, the powder to be treated can be kept within an area suitable for film formation, so that the film 92 can be formed with a more uniform film thickness.

[0106] Moreover, the particle coating method according to the embodiment or the modified example includes a recovery step S108. In the recovery step S108, the powder layer 95 after the coating 92 is formed is recovered. Furthermore, the recovery step S108 (a step of recovering the powder layer 95) includes an operation of dragging the powder layer 95 after the coating 92 is formed laterally. With this configuration, the powder layer 95 can be discharged from the deposition area and collected.

[0107] The powder to be treated may be made of a soft magnetic metal material, and the coating 92 may be made of an insulating material.

[0108] According to such a configuration, it is possible to form coating 92 that is sufficiently thin, dense, and has a high coverage rate, thereby obtaining coated particles 93 that can realize a magnetic element having excellent magnetic properties and insulating properties.

[0109] Although the particle coating apparatus and the particle coating method according to the present invention have been described based on the illustrated embodiments, the present invention is not limited to these.

[0110] For example, the particle coating apparatus according to the present invention may be one in which each part of the above embodiment is replaced with any component having the same function, or any component may be added to the above embodiment. Also, the particle coating method according to the present invention may be one in which any purposed step is added to the above embodiment. [Explanation of symbols]

[0111] 1...particle coating device, 11...treatment chamber, 12...powder layer holding section, 12A...powder layer forming section, 12B...powder layer discharge section, 13...powder supply section, 15...treatment chamber exhaust section, 16...treatment chamber heating section, 17...powder recovery section, 22...supply hopper, 24...recovery hopper, 90...powder layer, 91...particle, 92...coating, 93...coated particle, 95...powder layer, 122...frame, 124...squeegee, 125...ridge line, 126...stage, 132...antechamber, 133...antechamber exhaust section, 134...antechamber heating section, 142...raw material gas supply section, 144...oxidizer supply section, 146...oxygen gas supply unit, 148...plasma generation unit, 148a...upper electrode, 148b...lower electrode, 148c...high frequency power supply, 172...recovery chamber, 173...recovery chamber exhaust unit, 174...recovery chamber cooling unit, 182...supply switching unit, 184...recovery switching unit, 186...supply hopper opening / closing unit, 188...recovery hopper opening / closing unit, 901...ridge, 902...groove, G1...raw material gas, G2...oxidizer, G3...oxygen gas, S102...processed powder supply step, S104...powder layer forming step, S106...film forming step, S108...recovery step

Claims

1. A particle coating apparatus for forming a coating on a surface of a powder to be treated by an atomic layer deposition method, A processing chamber; a powder supply unit having a front chamber for accommodating the powder to be processed and supplying the powder to be processed into the processing chamber in a state isolated from outside air; a supply switching unit provided between the antechamber and the processing chamber for switching the supply of the powder to be processed; a raw material gas supply unit for supplying a raw material gas into the processing chamber; an oxidant supply unit for supplying an oxidant into the processing chamber; a processing chamber exhaust unit that exhausts the inside of the processing chamber; a powder layer holding section disposed within the processing chamber and holding a powder layer formed by laying the powder to be processed supplied from the anterior chamber in a layer shape; A particle coating apparatus comprising:

2. The powder layer holding unit includes: a powder layer forming section that has a frame body that contains the treated powder before the coating is formed therein, and supports the treated powder with the frame body to form the powder layer before the coating is formed; a powder layer discharge section having a squeegee and configured to discharge the powder layer after the coating has been formed from the powder layer forming section by dragging the powder layer after the coating has been formed laterally with the squeegee; 2. The particle coating apparatus according to claim 1, further comprising:

3. the squeegee has edges that contact the powder being processed as it drags the powder layer; 3. The particle coating apparatus according to claim 2, wherein the ridges are configured so that a shape left on the surface of the treated powder dragged by the squeegee includes a ridge or a groove.

4. the oxidizing agent is ozone; 4. The particle coating apparatus according to claim 1, further comprising a processing chamber heating section for heating the powder layer.

5. the oxidant is plasma oxygen; The oxidant supply unit is an oxygen gas supply unit for supplying oxygen gas into the processing chamber; a plasma generating unit that converts the oxygen gas into the plasma oxygen; The particle coating apparatus according to claim 1 , further comprising:

6. a powder recovery unit that is provided outside the treatment chamber and that recovers the powder layer after the coating is formed in a state isolated from outside air; a recovery switching unit that is provided between the processing chamber and the powder recovery unit and that switches the recovery of the powder layer; The particle coating apparatus according to claim 1 , further comprising:

7. A particle coating method for forming a coating on a surface of a powder to be treated by atomic layer deposition, comprising the steps of: supplying the powder to be treated, which is contained in a front chamber airtightly connected to a treatment chamber, into the treatment chamber while being isolated from outside air; forming a powder layer by spreading the powder to be treated supplied into the treatment chamber in a layer shape; forming the coating on the powder layer by atomic layer deposition in the processing chamber; A particle coating method comprising the steps of:

8. 8. The particle coating method according to claim 7, wherein the step of supplying the powder to be treated into the treatment chamber includes an operation of supplying the powder to the inside of a frame disposed in the treatment chamber.

9. recovering the powder layer after the coating is formed; 9. The method for coating particles according to claim 7 or 8, wherein the step of recovering the powder layer includes an operation of dragging the powder layer laterally after the coating is formed.

10. The powder to be treated is made of a soft magnetic metal material, 9. The method for coating particles according to claim 7, wherein the coating is made of an insulating material.

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