JP2024077127A - Film formation method - Google Patents

Abstract

[Problem] To provide a film forming method capable of stably forming a ceramic film having excellent density and adhesion. [Solution] In one embodiment of the present invention, the film forming method includes: storing raw material particles, which are a mixture of first ceramic particles having an average particle size of 3 μm to 7 μm and second ceramic particles which are pulverized powder of ceramic particles made of the same material as the first ceramic particles and have a particle size of 0.2 μm to 0.4 μm, in a sealed container; generating an aerosol of the raw material particles by introducing a gas into the sealed container; transporting the aerosol through a transport pipe connected to the sealed container to a film forming chamber maintained at a lower pressure than the sealed container; and depositing active species derived from the raw material fine particles on a substrate housed in the film forming chamber. [Selected Figure] Figure 2

Description

The present invention relates to a method for forming a ceramic film using the aerosol gas deposition method.

The aerosol gas deposition method (hereinafter also referred to as the AGD method) is a method in which raw material particles (aerosol raw material) contained in an aerosolization container are stirred up by gas to become an aerosol, and then transported by a gas flow caused by the pressure difference between the aerosolization container and the deposition chamber, and collided with a substrate, forming a film at room temperature. With this method, the deposition speed is faster than other deposition methods, and it is generally possible to form a film with high density and high adhesion.

For example, Patent Documents 1 and 2 disclose a film formation method in which raw material particles contained in an aerosolization container are stirred up by a gas to form an aerosol, and the raw material particles are transported by a gas flow caused by a pressure difference between the aerosolization container and a film formation chamber, and are then caused to collide with a substrate placed in the film formation chamber and deposited.

Patent Document 3 also discloses a film formation method in which a gas is introduced into a sealed container containing electrically insulating raw material particles to generate an aerosol of the raw material particles, the aerosol is transported to a film formation chamber, which has a lower pressure than the sealed container, via a transport pipe connected to the sealed container, the aerosol is sprayed from a nozzle attached to the tip of the transport pipe toward a target installed in the film formation chamber, the raw material particles are positively charged by colliding with the target, the charged raw material particles are discharged to generate fine particles of the raw material particles, and the generated fine particles are deposited on a substrate installed in the film formation chamber.

JP 2014-9368 A International Publication No. WO 2012/81053 JP 2016-27185 A

In recent years, there has been a demand for further improvements in the density and adhesion of ceramic films formed using the AGD method. The average particle size of the raw material particles that can be used to form films using the aerosol gas deposition method is generally considered to be optimal at around 0.5 μm, and films are formed using powders with particle sizes close to this size. On the other hand, if the particle size of the raw material particles is larger than this, it is thought that the density and adhesion of the film will be further improved, but it has been difficult to form a stable film.

In view of the above circumstances, the object of the present invention is to provide a film formation method that can stably form a ceramic film with excellent density and adhesion.

A film forming method according to one aspect of the present invention includes the steps of:
A raw material particle mixture of first ceramic particles having an average particle size of 3 μm or more and 7 μm or less and second ceramic particles which are pulverized powder of ceramic particles made of the same material as the first ceramic particles and have a particle size of 0.2 μm or more and 0.4 μm or less is placed in a sealed container;
generating an aerosol of the raw material particles by introducing a gas into the sealed container;
The aerosol is transported to a deposition chamber maintained at a lower pressure than the sealed container through a transport pipe connected to the sealed container;
Active species derived from the raw material fine particles are deposited on a substrate accommodated in the film-forming chamber.

By mixing the first ceramic particles, which have a relatively large particle size, and the second ceramic particles, which have a relatively small particle size, as raw material particles, plasma is generated efficiently with the first ceramic particles, and the film formation efficiency is increased with the second ceramic particles, which have a larger specific surface area than the first ceramic particles. This makes it possible to stably form a dense, highly adhesive ceramic particle film.

The second ceramic particles may be formed by crushing ceramic particles having an average particle size smaller than the average particle size of the first ceramic particles.

The second ceramic particles may be formed by pulverizing the first ceramic particles.

During the transport of the raw material particles from the sealed container to the deposition chamber, the first ceramic particles may be charged, and the surfaces of the second ceramic particles may be sputtered by discharges formed between the first ceramic particles and the substrate.

The present invention makes it possible to stably form a ceramic film with excellent density and adhesion.

FIG. 1 is a schematic diagram of an aerosolized gas deposition apparatus used in one embodiment of the present invention. 3 is a schematic diagram illustrating the operation of the aerosolized gas deposition apparatus. FIG. FIG. 13 is a diagram showing the particle size distribution of the PZT powder before the pulverization process used in Experimental Example 2. FIG. 4 is a diagram showing an example of a particle size distribution of the PZT powder after pulverization.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a schematic diagram of an aerosolized gas deposition device (hereinafter also referred to as an AGD device) 1 according to one embodiment of the present invention.

As shown in the figure, the AGD device 1 comprises an aerosolization container 2 (sealed container), a deposition chamber 3 (deposition chamber), an exhaust system 4, a gas supply system 5, and a transfer pipe 6. The aerosolization container 2 and the deposition chamber 3 each form an independent chamber, and the internal spaces of the chambers are connected to each other by the transfer pipe 6. The exhaust system 4 is connected to the aerosolization container 2 and the deposition chamber 3. The gas supply system 5 is connected to the aerosolization container 2. The aerosolization container 2 also contains an aerosol raw material P. The deposition chamber 3 contains a substrate S.

The aerosol-generating container 2 contains the aerosol raw material P, and an aerosol is generated inside it. The aerosol-generating container 2 is connected to a ground potential, has a sealable structure, and has a lid (not shown) for inserting and removing the aerosol raw material P. The aerosol-generating container 2 is connected to an exhaust system 4 and a gas supply system 5. The AGD device 1 may be provided with a vibration mechanism that vibrates the aerosol-generating container 2 to agitate the aerosol raw material P, or a heating means that heats the aerosol raw material P to degas it (remove moisture, etc.).

The deposition chamber 3 accommodates the substrate S therein. The deposition chamber 3 is configured to be able to maintain the internal pressure. The deposition chamber 3 is connected to an exhaust system 4. The deposition chamber 3 is also provided with a stage 7 for holding the substrate S and a stage drive mechanism 8 for moving the stage 7 in two in-plane axial directions (X-axis, Y-axis). The stage 7 may have a heating means for heating the substrate S in order to degas the substrate S before deposition. The deposition chamber 3 may also be provided with a vacuum gauge that indicates the internal pressure. The deposition chamber 3 and the stage 7 are connected to ground potential.

The substrate S is typically a plate-shaped member. More specifically, the substrate S may be a metal substrate such as aluminum or stainless steel, a glass substrate such as quartz, or a ceramic substrate. The substrate S may have a surface layer such as a metal film or an insulating film formed thereon.

The exhaust system 4 evacuates the aerosolization container 2 and the deposition chamber 3. The exhaust system 4 has a vacuum pipe 9, a first valve 10, a second valve 11, and a vacuum pump 12.

The vacuum pipe 9 connected to the vacuum pump 12 is branched and connected to the aerosolization container 2 and the deposition chamber 3. The first valve 10 is disposed on the vacuum pipe 9 between the branch point of the vacuum pipe 9 and the aerosolization container 2, and is configured to be able to cut off the vacuum exhaust of the aerosolization container 2. The second valve 11 is disposed on the vacuum pipe 9 between the branch point of the vacuum pipe 9 and the deposition chamber 3, and is configured to be able to cut off the vacuum exhaust of the deposition chamber 3. The configuration of the vacuum pump 12 is not particularly limited, and may be made up of multiple pump units. The vacuum pump 12 may be, for example, a mechanical booster pump and a rotary pump connected in series.

The gas supply system 5 supplies a carrier gas for determining the pressure of the aerosol-generating container 2 and forming an aerosol to the aerosol-generating container 2. The carrier gas is, for example, _N2 , Ar, He, _O2 , dry air, etc. The gas supply system 5 includes a gas pipe 13, a gas source 14, a third valve 15, a gas flow meter 16, and a gas ejector 17.

The gas source 14 and the gas ejection body 17 are connected by a gas pipe 13, and a third valve 15 and a gas flow meter 16 are arranged on the gas pipe 13. The gas source 14 is, for example, a gas cylinder, and supplies a carrier gas. The gas ejection body 17 is arranged in the aerosolization container 2, and ejects the carrier gas supplied from the gas pipe 13 uniformly. The gas ejection body 17 can be, for example, a hollow body with a large number of gas ejection holes, and is arranged in a position covered by the aerosol raw material P, thereby making it possible to effectively lift up the aerosol raw material P and to aerosolize it. The gas flow meter 16 indicates the flow rate of the carrier gas flowing through the gas pipe 13. The third valve 15 is configured to be able to adjust or block the flow rate of the carrier gas flowing through the gas pipe 13.

The transport tube 6 transports the aerosol formed in the aerosol-generating container 2 into the deposition chamber 3. One end of the transport tube 6 is connected to the aerosol-generating container 2. The transport tube 6 has a nozzle 18 provided at the other end. The nozzle 18 has a small round hole or a slit-shaped opening, and the ejection speed of the aerosol is determined by the opening diameter of the nozzle 18. The nozzle 18 is provided at a position facing the substrate S. The nozzle 18 is also connected to a nozzle movable mechanism (not shown) that determines the position and angle of the nozzle 18 to determine the ejection distance or ejection angle of the aerosol relative to the substrate S. The transport tube 6 and the nozzle 18 are connected to ground potential.

The inner surface of the transport tube 6 may be made of a conductor. A straight metal tube such as a stainless steel tube may be used as the transport tube 6. The length and inner diameter of the transport tube 6 can be set appropriately, for example, the length is 300 mm to 1000 mm, and the inner diameter is 4.5 mm to 24 mm. In addition, an insulating fluororesin (e.g., PTFE; polytetrafluoroethylene) tube may be used to maintain the charge of the positively charged aerosol particles.

The nozzle 18 opening may be circular or slot-shaped. In this embodiment, the nozzle 18 opening is slot-shaped, and its length is 10 to 1000 times its width. If the ratio of the length to the width of the opening is less than 10, it is difficult to effectively charge the particles inside the nozzle. If the ratio of the length to the width of the opening exceeds 1000, the particle charging efficiency is increased, but the amount of fine particles sprayed is limited and the film formation rate is significantly reduced. The ratio of the length to the width of the nozzle opening is preferably 20 to 800, more preferably 30 to 400.

The substrate S is made of materials such as glass, metal, and ceramics. As described above, the AGD method allows for film formation at room temperature, and is a physical film formation method that does not involve chemical processes, so a wide range of materials can be selected as the substrate. In addition, the substrate S is not limited to being flat, but may be three-dimensional.

The AGD device 1 is configured as described above. Note that the configuration of the AGD device 1 is not limited to that described above. For example, it is also possible to provide a gas supply mechanism connected to the aerosol-generating container 2, which is a separate system from the gas supply system 5. In the above configuration, the pressure in the aerosol-generating container 2 is adjusted by the carrier gas supplied by the gas supply system 5, and the aerosol raw material P is stirred up to form an aerosol. Note that by separately supplying a gas that is responsible for pressure adjustment from the gas supply means of the separate system, it is possible to adjust the pressure in the aerosol-generating container 2 independently of the aerosol formation state (amount formed, particle size mainly stirred up, etc.).

The aerosol raw material P is aerosolized in the aerosol-generating container 2 and formed into a film on the substrate S. The aerosol raw material P is made of fine particles having at least an insulating surface. As such fine particles, ceramic particles are used, and examples of the ceramic particles include insulating fine particles such as alumina fine particles, PZT (lead zirconate titanate) fine particles, zirconia fine particles, and yttria fine particles. In addition, the fine particles also include conductive fine particles such as metals whose surfaces are coated with an insulating film. The particle diameter of the aerosol raw material P is not particularly limited, but fine particles having an average particle diameter (D ₅₀ ) of 0.5 μm or more and 10 μm or less can be used.

Here, in this specification, unless otherwise specified, "average particle size" means the cumulative percentage of particle size distribution measured by a laser diffraction particle size distribution measurement method at 50% ( _D50 ). The average particle size value was measured using a laser diffraction particle size distribution measurement device "SALD2000" manufactured by Shimadzu Corporation. The "specific surface area" is a value measured by a gas adsorption method, and here, the value measured using a "Flowsorb II2300" manufactured by Shimadzu Corporation was used.

In this embodiment, the aerosol raw material P is a mixture of first ceramic particles having an average particle size of 3 μm or more and 7 μm or less and second ceramic particles which are a pulverized powder of ceramic particles made of the same material as the first ceramic particles. The second ceramic particles have a particle size of 0.2 μm or more and 0.4 μm or less.

As described below, by mixing first ceramic particles of a relatively large particle size and second ceramic particles of a relatively small particle size in the aerosol raw material P, plasma is generated efficiently with the first ceramic particles, and film formation efficiency is increased with the second ceramic particles, which have a larger specific surface area than the first ceramic particles. This makes it possible to stably form a dense, highly adhesive ceramic particle film.

The second ceramic particles may be formed by pulverizing ceramic particles having an average particle size smaller than that of the first ceramic particles. Alternatively, the second ceramic particles may be formed by pulverizing the first ceramic particles using a ball mill or the like. The pulverizing method is not particularly limited, and typically, a pulverizing means such as a ball mill is used.

Next, the film formation method of this embodiment will be described with reference to FIG. 2. FIG. 2 is a schematic diagram illustrating the operation of the AGD device 1. Below, a typical film formation method using the AGD device 1 will be described.

A predetermined amount of aerosol raw material P is placed in the aerosol-generating container 2. The aerosol raw material P may be heated and degassed in advance. The aerosol-generating container 2 may also be heated to degas the aerosol raw material P while it is still contained therein. By degassing the aerosol raw material P, it is possible to increase the probability and efficiency of charging the aerosol raw material P that induces plasma.

Next, the aerosol-generating container 2 and the film-forming chamber 3 are evacuated to a vacuum by the exhaust system 4 .
While the vacuum pump 12 is in operation, the first valve 10 and the second valve 11 are opened, and the aerosol-generating container 2 and the film-forming chamber 3 are evacuated until the pressure is sufficiently reduced. When the pressure in the aerosol-generating container 2 is sufficiently reduced, the first valve 10 is closed. The film-forming chamber 3 is evacuated during film formation.

Next, the carrier gas is introduced into the aerosol-generating container 2 by the gas supply system 5. The third valve 15 is opened, and the carrier gas is ejected from the gas ejection body 17 into the aerosol-generating container 2. The pressure inside the aerosol-generating container 2 increases due to the carrier gas introduced into the aerosol-generating container 2. In addition, the aerosol raw material P is lifted up by the carrier gas ejected from the gas ejection body 17 as shown in FIG. 2, and floats in the aerosol-generating container, forming an aerosol (shown as A in FIG. 2) in which the aerosol raw material P is dispersed in the carrier gas. The generated aerosol flows into the carrier pipe 6 due to the pressure difference between the aerosol-generating container 2 and the deposition chamber 3, and is ejected from the nozzle 18. The pressure difference between the aerosol-generating container 2 and the deposition chamber 3 and the state of aerosol formation are controlled by adjusting the opening of the third valve 15.

The aerosol (shown as A' in FIG. 2) is ejected from the nozzle 18 at a flow rate determined by the pressure difference between the aerosol-generating container 2 and the deposition chamber and the opening diameter of the nozzle 18. This aerosol reaches the surface of the substrate S or the existing film, and the aerosol raw material P contained in the aerosol, i.e., the ceramic particles, collide with the surface of the substrate S or the existing film. In the process, a ceramic thin film is formed.

By moving the substrate S, a ceramic thin film (indicated by F in FIG. 2) is formed in a predetermined area on the substrate S. By moving the stage 7 by the stage driving mechanism 8, the relative position of the substrate S with respect to the nozzle 18 changes. By moving the stage 7 in one direction parallel to the substrate S surface to be coated, a thin film can be formed in a line shape having the same width as the opening diameter of the nozzle 18. By moving the stage 7 back and forth, a film can be further formed on the existing film, and thus a ceramic thin film can be formed with a predetermined thickness. In addition, by moving the stage 7 two-dimensionally, a ceramic thin film is formed in a predetermined area. The angle of the nozzle 18 with respect to the substrate S surface to be coated may be a right angle or may be oblique. By tilting the nozzle 18 with respect to the substrate surface to be coated, even if aggregates of fine particles that reduce the quality of the coating are attached, the attached matter can be removed.

In the film formation method according to this embodiment, when aerosol A is generated and when aerosol A is transported by the transport pipe 6, static electricity is generated on the surfaces of the fine particles that make up the raw material P due to collisions between the fine particles or between the fine particles and the inner surface of the transport pipe 6 and the nozzle 18, and the charged fine particles are deposited on the substrate S. The greater the charge on the fine particles, the denser the film will be and the faster the film formation speed will be. The excess charge of the deposited fine particles is released into the space within the film formation chamber, and depending on the amount of released charge, it is accompanied by noticeable light emission. This light emission phenomenon is mainly due to plasma, and is believed to contribute to the generation of active species.

More specifically, when the aerosol raw material P is aerosolized by the gas in the aerosolization container 2, the ceramic raw material powder that is positively charged upon contact with the bottom wall of the aerosolization container 2 has a higher charging efficiency when the particle size is large. Smaller particles have a higher probability of being transported by the gas without colliding with anything, so the number of charged particles is reduced. When a positively charged particle flies near the earthed substrate S (stage 7), electrons are emitted from the earth side, which causes the gas near the particle to discharge. This can be seen with the naked eye as gas plasma, and large particle sizes are better for generating this plasma.

During this process, the surface of the raw material powder flying through the discharge is sputtered, knocking out atoms and molecules, and further merging and growing into fine nanoparticles (these are called active species) that contribute to film formation. This self-generated plasma region is spatially limited, and the probability of being sputtered within it increases the greater the specific surface area of the particles being sputtered during the flight process. In other words, in order to create active species, it is necessary for small particles (with a large specific surface area) to fly through the plasma, and the greater the amount of these active species, the higher the film formation speed.

In this embodiment, the aerosol raw material P is a mixed powder of raw material particles, which is a mixture of first ceramic particles having an average particle size of 1 μm or more and second ceramic particles obtained by pulverizing the first ceramic particles. This makes it possible to efficiently electrostatically charge and sputter the raw material powder in a technique for producing a film by spraying ceramic powder at room temperature.

In other words, when the raw material powder is rubbed together during the gas transport process and becomes electrostatically charged, if the positively charged particles fly near the grounded substrate S, electrons are emitted from the ground side, which causes the gas near the particles to discharge and become plasma. As the particles fly through the plasma, the particle surface is sputtered, sputtered atoms and molecules are generated, and fine nanocrystalline particles (active species) are formed by coalescence and growth. It is believed that these active species contribute to the formation of the film by aerosol gas deposition. In other words, in order to stably form a dense and highly adhesive ceramic thin film, it is believed that an optimal mixed powder, etc. is required as the aerosol raw material P, because the particle shape (size) that efficiently electrostatically charges and generates plasma is different from the particle shape (size) that is efficiently sputtered in the plasma.

[Experimental Example 1]
Hereinafter, an experimental example of a film forming method using the AGD apparatus 1 configured as above will be described. Here, an experimental example using alumina powder as raw material powder will be described.

(Experimental Example 1-1)
30 g of alumina powder (AL-160SG-3 manufactured by Showa Denko) having an average particle size of 0.52 μm was placed in an alumina crucible and subjected to a heat treatment in the atmosphere at a temperature of 300° C. for 1 hour. After that, 30 g of the alumina powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the aluminum substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an alumina film. The drive speed of the substrate was set to 5 mm/s, and 40 layers were formed with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 12 minutes, and an alumina film with a thickness of 7 μm and an area of 50 mm x 30 mm was formed.
The film was dense and had strong adhesion to the aluminum substrate (it did not peel off even when rubbed with a HB pencil). However, this film was a whitish gray film. In addition, this alumina film was conductive even at an applied voltage of 100 V or less, and was not electrically insulating. The resistance was 1 kΩ or less.

(Experimental Example 1-2)
30 g of alumina powder (AES-12, manufactured by Sumitomo Chemical) with an average particle size of 0.44 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 30 g of the alumina powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the aluminum substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an alumina film. The drive speed of the substrate was set to 5 mm/s, and 40 layers were formed with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 12 minutes, and an alumina film with an area of 50 mm x 30 mm was formed.
The film was a green compact, not dense, and could be peeled off if rubbed. The reason for this is believed to be that the raw powder had a large number of particles with sizes between 0.1 μm and 0.2 μm, as determined from the particle size distribution of the raw powder.

(Experimental Example 1-3)
150 g of alumina powder (AL-160SG-3 manufactured by Showa Denko) having an average particle size of 0.52 μm was ground for 3 hours in a planetary ball mill, and 30 g of the ground powder was placed in an alumina crucible and heated for 1 hour at a temperature of 300° C. in the atmosphere. After that, 30 g of the alumina powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the aluminum substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an alumina film. The drive speed of the substrate was set to 5 mm/s, and 40 layers were deposited with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 12 minutes, and an alumina film with a thickness of 7 μm and an area of 50 mm x 30 mm was formed.
The film was dense and had strong adhesion to the aluminum substrate (it did not peel off even when rubbed with a HB pencil). Compared to the film formed using alumina powder that had not been milled (Experimental Example 1-1), the film was less whitish and had a transparent gray-black color. This alumina film was found to be conductive in many places even when a voltage of 100 V or less was applied, and it did not have any electrical insulation properties. The resistance was 1 kΩ or less.

(Experimental Example 1-4)
150 g of alumina powder (AES-12, manufactured by Sumitomo Chemical) having an average particle size of 0.44 μm was ground for 3 hours in a planetary ball mill, and 30 g of the ground powder was placed in an alumina crucible and heated for 1 hour at a temperature of 300° C. in the atmosphere. After that, 30 g of the alumina powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the aluminum substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an alumina film. The drive speed of the substrate was set to 5 mm/s, and 40 layers were formed with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 12 minutes, and an alumina film with an area of 50 mm x 30 mm was formed, but the film was not dense and peeled off when rubbed.

(Experimental Example 1-5)
30 g of alumina powder (ALM-43 manufactured by Sumitomo Chemical) having an average particle size of 3.7 μm was placed in an alumina crucible and subjected to a heat treatment in the atmosphere at a temperature of 300° C. for 1 hour. After that, 30 g of the alumina powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the aluminum substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an alumina film. The substrate was driven at a speed of 5 mm/s, and 40 layers were deposited with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 12 minutes.
The film thickness was 1 μm or less, and although there was a discharge mark with an area of 50 mm × 30 mm, the film was not thick, and even if the number of laminations was 100, the film thickness did not exceed 1 μm. There was no trace of the compact, and although reddish purple discharge was observed during film formation, no film was formed. It is believed that the reason the film thickness did not increase is that there were no particles with a size of 0.4 μm or less based on the particle size distribution of the raw material powder.

(Experimental Example 1-6)
150 g of alumina powder (AL-160SG-3 manufactured by Showa Denko) having an average particle size of 0.52 μm was ground for 3 hours in a planetary ball mill to produce alumina powder (second ceramic particles) having a particle size of 0.2 μm or more and 0.4 μm or less. 60 g of the powder after the grinding process was mixed with 20 g of alumina powder (first ceramic particles) (ALK-43 manufactured by Sumitomo Chemical) having an average particle size of 3.7 μm, placed in an alumina crucible, and subjected to a heat treatment at a temperature of 300 ° C. in air for 1 hour. Then, 30 g of the alumina powder was quickly transferred to a glass aerosolization container 2, and evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosolization container 2 was heated to 150 ° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the aluminum substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an alumina film. The drive speed of the substrate was set to 5 mm/s, and 200 layers were deposited with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 108 minutes, and an alumina film with a thickness of 4 μm and an area of 50 mm x 30 mm was formed.
The film was dense and had strong adhesion to the aluminum substrate (it did not peel off even when rubbed with a HB pencil). The film was a glossy black film. The resistance of this alumina film was 40 MΩ or more over the entire surface, and a high level of electrical insulation was observed.
In this experimental example, the data was for a case where the mixing ratio of large size 3.7 μm to small powder was 25%. When this mixing ratio was increased to 50%, it was confirmed that a black alumina film could be formed, but the film had uneven surface gloss.

As described above, in the film formation examples using raw material powder of a single particle size (Experimental Examples 1-1 to 1-5), it was difficult to form an alumina film that was dense, had high adhesion, and had excellent electrical insulation. However, in the film formation example using raw material powder of two different particle sizes (Experimental Example 1-6), it was possible to stably form an alumina film that was dense, had high adhesion, and had excellent electrical insulation.

[Experimental Example 2]
Next, an experimental example in which PZT (Pb(Zr _0.52 Ti _0.48 )O ₃ ) powder was used as the raw material powder will be described.

(Experimental Example 2-1)
50 g of PZT powder (manufactured by Kojundo Chemical Laboratory) with an average particle size of 2.9 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the PZT powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 8 L/min, and the carrier gas was supplied at 5 L/min, so that the PZT powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the aerosol was sprayed and deposited on the quartz substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form a PZT film. The drive speed of the substrate was set to 5 mm/s, and 60 layers were formed with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 10 minutes, but the film thickness was 1 μm or less, and although there was a thin deposition mark with an area of 50 mm x 30 mm, the film thickness was not thick, and even if the number of layers was 100, the film thickness did not exceed 1 μm.

(Experimental Example 2-2)
150 g of PZT powder (manufactured by Kojundo Kagaku Kenkyusho) with an average particle size of 2.9 μm was ground for 3 hours in a planetary ball mill to produce PZT powder (second ceramic particles) with a particle size of 0.2 μm or more and 0.4 μm or less. 15 g of the ground powder and 45 g of the PZT powder (first ceramic particles) with an average particle size of 2.9 μm were mixed and placed in an alumina crucible, and heat-treated at a temperature of 300° C. in air for 1 hour. Then, 60 g of the PZT powder was quickly transferred to a glass aerosolization container 2 and evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosolization container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the ITO-coated quartz substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), forming a PZT film. The substrate was driven at a speed of 5 mm/s, and 50 layers were deposited with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 27 minutes, and a PZT film with a thickness of 2 μm and an area of 50 mm x 30 mm was formed.
The film was dense and had strong adhesion to the quartz substrate (it did not peel off even when rubbed with a HB pencil). The film was a transparent, yellowish-black glossy film. The film weight was about 6 mg.

Figure 3 shows the particle size distribution of the PZT powder before the crushing process, and Figure 4 shows the particle size distribution of the PZT powder after the crushing process. As shown in the figure, the PZT powder after the crushing process is finer, and it was confirmed that the PZT powder after the crushing process contains a large amount of raw material powder (second ceramic particles) with a particle size of 0.2 μm or more and 0.4 μm or less.

(Experimental Example 2-3)
150 g of PZT powder (manufactured by Kojundo Kagaku Kenkyusho) with an average particle size of 2.9 μm was ground for 3 hours in a planetary ball mill to produce PZT powder (second ceramic particles) with a particle size of 0.2 μm or more and 0.4 μm or less. 30 g of the ground powder and 30 g of the PZT powder (first ceramic particles) with an average particle size of 2.9 μm were mixed and placed in an alumina crucible, and heat-treated at a temperature of 300° C. in air for 1 hour. Then, 60 g of the PZT powder was quickly transferred to a glass aerosolization container 2 and evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosolization container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the alumina powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the alumina powder was sprayed and deposited on the ITO-coated quartz substrate as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), forming a PZT film. The substrate was driven at a speed of 5 mm/s, and 50 layers were deposited with a length of 50 mm in the X-axis direction and 30 mm in the Y-axis direction. The deposition time was about 27 minutes, and a PZT film with a thickness of 2 μm and an area of 50 mm x 30 mm was formed.
The film was dense and had strong adhesion to the quartz substrate (it did not peel off even when rubbed with a HB pencil). However, protruding film was observed in places. The film was a yellowish blackish color. The weight of the film was about 29 mg.

[Experimental Example 3]
Next, an experimental example in which yttria-stabilized zirconia powder was used as the raw material powder will be described.

(Experimental Example 3-1)
50 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet process by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 2.5 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 6 L/min, and the carrier gas was supplied at 7 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 32 kPa) was aerosolized, and the aerosol was sprayed and deposited on a SUS substrate having a diameter of 25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through a carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 44 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 4.5 minutes, and an yttria-stabilized zirconia film having a central thickness of 14 μm and an area of φ25 mm was formed.
The film was dense and had strong adhesion to the SUS substrate (it did not peel off even when rubbed with a HB pencil). The film was gray in color. The weight of the film was about 25 mg.

(Experimental Example 3-2)
50 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet process by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 6.3 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 8 L/min, and the carrier gas was supplied at 5 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 29 kPa) was aerosolized, and the aerosol was sprayed and deposited on a SUS substrate having a diameter of 25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through a carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 240 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 24 minutes, and an yttria-stabilized zirconia film having a central thickness of 2.6 μm and an area of φ25 mm was formed.
The film was dense and had strong adhesion to the SUS substrate (it did not peel off even when rubbed with a HB pencil). The film was glossy black in color. The weight of the film was about 9.8 mg.
The density is high, but the film formation speed tends to be slow. From the particle size distribution of the raw material powder, it is thought that there is little powder below 1 μm, and although plasma is generated, there is a tendency for little powder to be sputtered. Here, since dry powder is produced by crushing large lumps, it is speculated that the powder sprayed onto the substrate during the film formation process is crushed, and the crushed small powder below 1 μm is sputtered. In other words, it is thought that film formation requires the generation of crushed powder by spraying it onto the substrate. In the worst case, it is thought that the blasting effect may cause cutting of the base material, but cutting does not occur on the hard SUS substrate.

(Experimental Example 3-3)
50 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet process by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 5.4 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 8 L/min, and the carrier gas was supplied at 5 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 32 kPa) was aerosolized, and the aerosol was sprayed and deposited on a SUS substrate having a diameter of 25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through a carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 80 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 8 minutes, and an yttria-stabilized zirconia film having a central thickness of 11 μm and an area of φ25 mm was formed.
The film was dense and had strong adhesion to the SUS substrate (it did not peel off even when rubbed with a HB pencil). The film was black in color. The weight of the film was about 22 mg.

(Experimental Example 3-4)
50 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet process by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 1.4 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 6 L/min, and the carrier gas was supplied at 7 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the aerosol was sprayed and deposited on a SUS substrate having a diameter of 25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through a carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 64 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 6.5 minutes, and an yttria-stabilized zirconia film having a central thickness of 14 μm and an area of φ25 mm was formed.
The film was dense and had strong adhesion to the SUS substrate (it did not peel off even when rubbed with a HB pencil). The film was gray in color. The weight of the film was about 17.5 mg.

From the above results, it can be seen that in the film formation using 8 mol % yttria-stabilized zirconia powder, the density increases in the following order of particle size of the powder used: Therefore, it is found that to form a film with high density, it is better to use the larger particle size of 6.3 μm.
1. Average particle size 6.3 μm (dry type) High density approx. 5.7 g/ ^cm3
2. Average particle size: 5.4 μm (dry type) Approx. 4.1 g/ ^cm3
3. Average particle size: 2.5 μm (wet) Approx. 3.7 g/ ^cm3
4. Average particle size 1.4 μm (dry type) Low density Approximately 2.5 g/ ^cm3

(Experimental Example 3-5)
50 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet process by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 6.3 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 8 L/min, and the carrier gas was supplied at 5 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 29 kPa) was aerosolized, and the aerosol was sprayed and deposited on the porous ceramic undercoat film on the SUS substrate of φ25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 240 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 24 minutes, but as a result, 50% (25% to 75%) of the porous ceramic undercoat film was peeled off from the entire film. Plasma was confirmed during deposition.

(Experimental Example 3-6)
50 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet process by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 5.4 μm was placed in an alumina crucible and subjected to heat treatment in air at a temperature of 300° C. for 1 hour. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosol-generating container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosol-generating container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 29 kPa) was aerosolized, and the aerosol was sprayed and deposited on the porous ceramic undercoat film on the SUS substrate of φ25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 240 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 24 minutes, but as a result, 50% (25% to 75%) of the porous ceramic undercoat film was peeled off from the entire film. Plasma was confirmed during deposition.

(Experimental Example 3-7)
150 g of 8 mol% yttria-stabilized zirconia powder (powder produced by wet method, manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) having an average particle size of 2.5 μm was subjected to a pulverization process for 3 hours in a planetary ball mill, and 50 g of the powder after the pulverization process was placed in an alumina crucible and subjected to a heat treatment for 1 hour at a temperature of 300° C. in the atmosphere. After that, 50 g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosolization container 2, and the container was evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosolization container 2 was heated to 150° C. by a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to be supplied at 8 L/min, and the carrier gas was supplied at 5 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the aerosol was sprayed and deposited on the porous ceramic undercoat film on the SUS substrate of φ25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The drive speed of the substrate was set to 5 mm/s, and 8 layers of 30 mm in length were formed only in the X-axis direction. The deposition time was about 1 minute, and an yttria-stabilized zirconia film with a thickness of 4 μm and an area of φ25 mm was formed.
There was no peeling between the porous ceramic undercoat film and the film, which was whitish in color. The weight of the film formed was about 4.5 mg.

(Experimental Example 3-8)
150g of 8 mol% yttria-stabilized zirconia powder (powder manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd. using a planetary ball mill) with an average particle size of 2.5 μm was ground for 3 hours to produce yttria-stabilized zirconia powder (second ceramic particles) with a particle size of 0.2 μm or more and 0.4 μm or less. 15g of the powder after the grinding process and 35g of 8 mol% yttria-stabilized zirconia powder (first ceramic particles) (powder manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd. using a dry process) with an average particle size of 6.3 μm were placed in an alumina crucible and subjected to a heat treatment at a temperature of 300 ° C. in the atmosphere for 1 hour. Then, 50g of the yttria-stabilized zirconia powder was quickly transferred to a glass aerosolization container 2 and evacuated to 10 Pa or less. In order to promote degassing of the powder, the aerosolization container 2 was heated to 150 ° C. using a mantle heater.
The exhaust valve (first valve 10) of the aerosolization container 2 was closed, and the nitrogen gas was adjusted with a flow meter to supply 8 L/min, and the carrier gas was supplied at 5 L/min, so that the yttria-stabilized zirconia powder in the aerosolization container 2 (pressure: about 30 kPa) was aerosolized, and the aerosol was sprayed and deposited on the porous ceramic undercoat film on the SUS substrate of φ25 mm as the substrate S attached to the stage 7 in the deposition chamber 3 (pressure: about 200 Pa) through the carrier pipe/nozzle (opening 30 mm x 0.3 mm), to form an yttria-stabilized zirconia film. The substrate was driven at a speed of 5 mm/s, and 120 layers were deposited over a length of 30 mm only in the X-axis direction. The deposition time was about 9 minutes, and an yttria-stabilized zirconia film having a thickness of 7.8 μm and an area of φ25 mm was formed.
There was no peeling between the porous ceramic base film and the film, and the film was black in color. The weight of the film formed was about 14.2 mg. Compared to Experimental Example 3-7, it was possible to form a film with increased density.

1... Aerosolized gas deposition device (AGD device)
2 aerosol container 3 deposition chamber 6 transfer pipe 18 nozzle S substrate

Claims (4)

A raw material particle mixture of first ceramic particles having an average particle size of 3 μm or more and 7 μm or less and second ceramic particles which are pulverized powder of ceramic particles made of the same material as the first ceramic particles and have a particle size of 0.2 μm or more and 0.4 μm or less is placed in a sealed container;
generating an aerosol of the raw material particles by introducing a gas into the sealed container;
The aerosol is transported to a deposition chamber maintained at a lower pressure than the sealed container through a transport pipe connected to the sealed container;
The film forming method further comprises depositing the raw material fine particles on a substrate accommodated in the film forming chamber. The film forming method according to claim 1 ,
The second ceramic particles are formed by pulverizing ceramic particles having an average particle size smaller than that of the first ceramic particles. The film forming method according to claim 1 ,
The second ceramic particles are formed by pulverizing the first ceramic particles. The film forming method according to any one of claims 1 to 3,
the first ceramic particles are charged during transport of the raw material particles from the sealed container to the film-forming chamber, and surfaces of the second ceramic particles are sputtered by discharge generated between the first ceramic particles and the substrate.

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