Film forming apparatus, conductive film manufacturing apparatus, film forming method, and conductive film manufacturing method

Abstract

To provide a deposition system which forms a thin film made of resin and inorganic fine particles in a uniform and accurate thickness on a large film surface.SOLUTION: A deposition system supplies mist containing fine particles to a substrate P to form a film including the fine particles on a surface of the substrate and includes: a mist generation part 14 which atomizes a liquid containing the fine particles to generate the mist; and a mist supply part 31 which supplies the mist to the substrate. The mist supply part includes: a temperature regulating part which regulates a temperature of the mist to a first temperature; and a substrate temperature regulating part which makes a temperature of the substrate to a second temperature. The substrate temperature regulating part sets the second temperature to a temperature lower than the first temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film forming apparatus, a conductive film manufacturing method, and a conductive film manufacturing method that spray a mist of a solution containing fine material particles (nanoparticles) onto a substrate to be processed, thereby forming a thin film of material substance made of the fine particles on the surface of the substrate to be processed. [Background technology]

[0002] In the manufacturing process of electronic devices, a film formation process (film formation treatment) is carried out to form a thin film of various materials on the surface of a substrate (substrate) on which the electronic device is to be formed. There are various film formation methods in the film formation process, and in recent years, a mist film formation method has attracted attention. This method involves spraying a mist generated from a solution containing molecules or fine particles (nanoparticles) of the material onto the surface of the substrate, and then reacting or evaporating the solvent components contained in the mist (solution) that has adhered to the substrate, thereby forming a thin film of the material (metallic material, organic material, oxide material, etc.) on the surface of the substrate. A known film formation method similar to the mist film formation method is the electrospray deposition method, as disclosed in Patent Document 1. The electrospray deposition method involves electrostatically charging a liquid to be applied, converting the charged liquid into fine droplets (mist) or filaments, and then adhering the charged liquid to the substrate. Patent Document 1 discloses a configuration in which a solution in which a resin is dissolved in a solvent or a dispersion in which a resin and inorganic fine particles are dispersed, to be formed into a film on the surface of an insulating film, is supplied to a spray nozzle having a capillary tube at the tip, and charged droplets or filaments with diameters of 0.5 to tens of microns are sprayed onto the film surface from the capillary tube at the tip of the nozzle by applying a high voltage to the spray nozzle while applying pressure to the spray nozzle to maintain a constant flow rate. Furthermore, Patent Document 1 discloses that the film is placed on a conductive plate larger than the area of ​​the film, and a constant potential difference is applied between the conductive plate and the spray nozzle, thereby efficiently adhering the charged droplets or filaments to the film surface.

[0003] In electrostatic spray deposition (ESD), the droplets or filaments ejected from the capillary tube of the spray nozzle depend on the distance from the nozzle tip to the film surface or the potential difference between the spray nozzle and the conductive plate. Patent Document 1, however, employs a configuration in which the diameter of the spray nozzle tip (capillary tube) is preferably set to a range of 0.4 to 1 mm, and the voltage applied between the spray nozzle and the conductive plate is preferably set to a range of 10 to 20 kVk, thereby ejecting droplets or filaments from the nozzle tip by electrostatic repulsion. As a result, the film thickness formed is thickest at the center where the extension of the nozzle tip's capillary tube intersects with the film surface, and tends to decrease from the center to the periphery. Therefore, to form a thin film of resin or inorganic particles with a uniform and accurate thickness on a large film surface, the film and the spray nozzle must be precisely moved relative to each other at a constant speed in a plane parallel to the film surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-281679 Summary of the Invention

[0005] A first aspect of the present invention is a mist film forming device that sprays a mist containing fine particles of a material substance onto a substrate and forms a film layer of the material substance on the surface of the substrate, and includes a mist generation mechanism that sends out a mist gas containing mist generated by atomizing a solution containing the fine particles, a mist ejection mechanism that flows in the mist gas and ejects it toward the substrate, an air guide mechanism having a wall surface facing the surface of the substrate at a predetermined distance in order to flow the mist gas from the mist ejection mechanism along the surface of the substrate, and a mist induction mechanism that generates a repulsive force between the wall surface of the air guide member and the mist in order to generate an attractive force that attracts the mist toward the surface of the substrate.

[0006] A second aspect of the present invention is a mist film forming apparatus that sprays a mist gas, in which a mist containing fine particles is carried on a carrier gas, onto the surface of a substrate and forms the fine particles into a thin film on the surface of the substrate, and includes a mist spraying unit having a nozzle opening facing the surface of the substrate at a predetermined distance and spraying the mist gas from the nozzle opening toward the substrate, a mist supplying unit that supplies the mist gas to the mist spraying unit at a predetermined flow rate and sets the mist gas sprayed from the nozzle opening to a first temperature lower than ambient temperature, a moving mechanism that supports the substrate and moves it in a direction along the surface of the substrate, and a substrate temperature control mechanism that sets the substrate onto which the mist gas is sprayed to a second temperature lower than the first temperature.

[0007] A third aspect of the present invention is a mist film forming method for spraying a mist gas, in which a mist containing fine particles is carried on a carrier gas, onto the surface of a substrate to be processed, and forming the fine particles into a thin film on the surface of the substrate to be processed, the method comprising: setting the temperature of the mist gas sprayed from a mist outlet toward the surface of the substrate to be processed to a first temperature higher than 0°C and not higher than 30°C by a first temperature regulator; setting the temperature of the substrate to be processed to a second temperature not higher than the first temperature by a second temperature regulator; and spraying the mist gas set to the first temperature onto the surface of the substrate to be processed, which has been set to the second temperature, while moving the substrate to be processed and the mist outlet relative to each other along the surface of the substrate to be processed by a moving mechanism.

[0008] A fourth aspect of the present invention is a film forming apparatus that supplies a mist containing fine particles to a substrate and forms a film containing the fine particles on the surface of the substrate, comprising: an air guide member that covers at least a portion of the surface of the substrate; and a mist supply unit that supplies the mist into a space between the surface of the substrate and the air guide member, wherein the mist supply unit includes a charge applying unit that charges the mist positively or negatively, and a mist ejection unit that ejects the mist charged by the charge applying unit into the space, and the air guide member has a wall surface facing the surface of the substrate and comprises an electrostatic field generating unit that generates a potential on the wall surface of the same sign as the mist charged by the charge applying unit.

[0009] A fifth aspect of the present invention is a film forming apparatus that supplies a mist containing fine particles to a substrate and forms a film containing the fine particles on the surface of the substrate, comprising: a mist generating unit that atomizes a liquid containing the fine particles to generate the mist; and a mist supplying unit that supplies the mist to the substrate, wherein the mist supplying unit includes a temperature adjusting unit that adjusts the temperature of the mist to a first temperature, and a substrate temperature adjusting unit that adjusts the temperature of the substrate to a second temperature.

[0010] A sixth aspect of the present invention is a conductive film manufacturing apparatus, comprising: a film forming apparatus according to the first or second aspect described above; and a drying section that dries the mist on the substrate formed by the film forming apparatus.

[0011] A seventh aspect of the present invention is a film forming method for supplying a mist containing fine particles to a substrate and forming a film containing the fine particles on the surface of the substrate, comprising: a mist supplying step in which the mist is positively or negatively charged by a charge imparting unit, and the charged mist is supplied by a mist ejecting unit to a space between an air guide member covering at least a portion of the surface of the substrate and the surface of the substrate; and an electrostatic field generating step in which an electric potential of the same sign as that of the charged mist is generated on a wall surface of the air guide member facing the surface of the substrate.

[0012] An eighth aspect of the present invention is a film forming method for supplying a mist containing fine particles to a substrate and forming a film containing the fine particles on the surface of the substrate, comprising a mist generation process for atomizing a liquid containing the fine particles to generate mist, and a mist supply process for supplying the mist to the substrate, wherein in the mist supply process, a temperature control unit sets the temperature of the mist to a first temperature, and a substrate temperature control unit sets the temperature of the substrate to a second temperature.

[0013] A ninth aspect of the present invention is a method for producing a conductive film, comprising: a film formation step of forming a film of a conductive film material on the substrate using the film formation method of the fourth or fifth aspect described above; and a drying step of drying the substrate on which the film has been formed. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic overall configuration of a mist film forming apparatus MDE according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a specific external appearance of a mist film forming unit of the mist film forming apparatus MDE shown in FIG. 1. [Figure 3] 3A is a front view of a mist jetting portion in the mist film forming portion, and FIG. 3B is a cross-sectional view taken along the k1-k2 arrows in FIG. 3A. [Figure 4] FIG. 2 is a diagram showing a schematic configuration of a mist film forming unit of the mist film forming apparatus MDE according to a first modified example of the first embodiment. [Figure 5] 5 is a partial cross-sectional view showing a configuration according to a second modified example of the first embodiment, in which the rotating drum DR and the chamber portion 40 shown in FIG. 4 are cut along a plane including the center line AXo. FIG. [Figure 6] FIG. 10 is a diagram showing a schematic overall configuration of a mist film forming apparatus MDE according to a second embodiment. [Figure 7] FIG. 7 is a diagram showing a specific configuration of a nanoparticle deposition uniforming unit in the mist film-forming apparatus MDE shown in FIG. 6. [Figure 8] FIG. 8 is a diagram showing a schematic configuration of a preliminary experiment device for confirming the function and effect of the deposition uniforming unit of FIG. 7. [Figure 9] 9 is a graph showing the experimental results of preliminary experiment 1, which was conducted using the preliminary experiment apparatus of FIG. 8 to examine the frequency dependency when an AC electric field was applied to a liquid film containing ITO nanoparticles. [Figure 10] 9 is a graph showing the experimental results of preliminary experiment 2, which was conducted using the preliminary experiment apparatus of FIG. 8 to examine the dependence of an AC electric field on the electric field strength when an AC electric field was applied to a liquid film containing ITO nanoparticles. [Figure 11] 9 is a graph showing the experimental results of preliminary experiment 3, which investigates the frequency dependence due to differences in nanoparticle diameter when an AC electric field is applied to a liquid film containing ITO nanoparticles using the preliminary experimental apparatus of FIG. 8. [Figure 12]12A to 12C are diagrams showing several examples of the waveform of the AC voltage Ev applied between the electrode plates Ef1 to Ef4 and the electrode plate Em by the AC electric field generating unit 90 of the mist film forming apparatus shown in FIGS. 6 and 7. [Figure 13] 13A and 13B are a top view and a front view showing the configuration of a deposition uniforming unit (electrophoresis imparting unit) according to Modification 5. FIG. [Figure 14] FIG. 10 is a diagram showing a schematic configuration of a mist film forming apparatus MDE according to a third embodiment. [Figure 15] 15 is a diagram showing waveforms of AC electric fields applied to a mist induction mechanism provided in the mist film forming unit of the mist film forming device of FIG. 14 and to a deposition uniforming unit (electrophoresis imparting unit) after mist film formation. FIG. [Figure 16] 15 is a circuit diagram showing an example of a specific circuit configuration of an AC electric field generating section 92 shown in FIG. 14. FIG. [Figure 17] FIG. 10 is a diagram showing a schematic configuration of an experimental device for confirming whether or not ITO nanoparticles that crystallize to have a non-rectangular parallelepiped outer shape migrate in solution Lq. [Figure 18] 18 is a table showing the experimental results obtained using the experimental apparatus of FIG. 17. [Figure 19] FIG. 10 is a diagram showing a schematic configuration of a mist film forming apparatus MDE according to a fourth embodiment. [Figure 20] FIG. 10 is a perspective view showing a schematic configuration of a preliminary experiment device for confirming the effect of the mist film forming method according to the fourth embodiment. [Figure 21] 21 is a graph showing the relationship between the substrate temperature and the film thickness of the nanoparticles obtained by an experiment using the preliminary experiment apparatus of FIG. 20. [Figure 22] FIG. 13 is a diagram showing a schematic configuration of a mist film forming unit of a mist film forming apparatus MDE according to a fifth embodiment. [Figure 23] 20 is a perspective view showing a schematic configuration of a mist film-forming apparatus MDE according to a sixth modified example obtained by modifying the mist film-forming apparatus MDE of FIG. 19. FIG. [Figure 24] 24A and 24B are diagrams showing the configuration of a valve mechanism 310 for quickly switching between a supply state and a non-supply state of mist gas Msg to the auxiliary mist spraying part SMD shown in FIG. [Figure 25] 1. FIG. 10 is a partial cross-sectional view showing a specific configuration of the mist generating unit 14 shown in FIG. 1 as a seventh modified example. [Figure 26] 26 is a diagram showing the arrangement in a plane of four ultrasonic vibrators 14C1 to 14C4 arranged at the bottom of outer container 14D of mist generating unit 14 shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments of a mist film-forming device and a mist film-forming method according to the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments and includes various modifications and improvements. In other words, the components described below include those that would be easily conceivable to a person skilled in the art and those that are substantially identical, and the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.

[0016] [First embodiment] FIG. 1 is a diagram showing a schematic overall configuration of a mist film-forming apparatus MDE according to a first embodiment. In FIG. 1, unless otherwise specified, an XYZ Cartesian coordinate system is set, with the direction of gravity being the Z direction. According to the arrows shown in FIG. 1, the transport direction of a flexible sheet substrate P (also simply referred to as substrate P) serving as a substrate to be processed is set as the X direction, and the width direction of sheet substrate P, which is perpendicular to the transport direction, is set as the Y direction. In this embodiment, the surface of sheet substrate P during mist film formation is set to a horizontal plane parallel to the XY plane. In this embodiment, sheet substrate P is a flexible sheet elongated in the X direction and made of a resin such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), or polyimide, with a thickness of several hundred to several tens of micrometers. However, other materials may also be used, such as a metal foil sheet thinly rolled from a metal material such as stainless steel, aluminum, brass, or copper; an ultrathin glass sheet with a thickness of 100 μm or less to provide flexibility; or a plastic sheet containing cellulose nanofibers. The sheet substrate P does not necessarily have to be long, and may be, for example, a single sheet substrate with standardized long and short side dimensions such as A4 size, A3 size, B4 size, or B3 size, or a non-standard, irregularly shaped single sheet substrate.

[0017] 1, the mist film-forming apparatus MDE according to this embodiment generally includes a transport unit (transport section) 5 that supports and transports a sheet substrate P in the X direction, a solution tank 10 that stores a solution (dispersion or liquid) Lq in which nanoparticles serving as a film-forming material are dispersed, a mist generation section 14 that efficiently generates mist having particle sizes of several μm to several tens of μm from the solution Lq, a mist ejection section 30 that receives mist generated by the mist generation section 14, carried by a carrier gas CGS, as mist gas Msg, via a flexible pipe 17, and sprays the mist gas Msg toward the sheet substrate P, a mist collection section 32 that collects the mist gas Msg, including mist that is not attached to the sheet substrate P and is floating, and a chamber section 40 that is provided to cover the sheet substrate P supported by the mist ejection section 30, the mist collection section 32, and the transport unit 5 to prevent leakage of the mist gas Msg into the ambient air (outside the apparatus). The configuration of each section will be described in more detail below.

[0018] 1 includes a roller 5A that rotates about a central axis AXa that is parallel to the Y axis, a roller 5B that rotates about a central axis AXb that is positioned parallel to the central axis AXa and a predetermined distance away from the central axis AXa in the X direction, an endless belt 5C that is stretched between the two rollers 5A and 5B and that supports the sheet substrate P flatly on the upper surface of a flat portion, and a support table 5D that is positioned on the back side of the flat portion of the belt 5C that supports the sheet substrate P and that supports the belt 5C flat. The width of the belt 5C in the Y direction is set to be slightly larger than the width (short dimension) of the substrate P in the Y direction, and the belt 5C vacuum-sucks the substrate P in an area corresponding to the upper surface of the support table 5D, and is transported and driven in a non-contact (or low-friction) state with respect to the upper surface of the support table 5D by a static pressure gas layer (air bearing) generated between the upper surface of the support table 5D and the back surface of the belt 5C. A transport unit 5 having such a configuration is disclosed, for example, in International Publication No. 2013 / 150677. Belt 5C is preferably made of a thin metal plate (conductive thin plate) such as stainless steel, which has high rigidity and ensures flatness. Nip rollers 5E and 5F are provided downstream (negative X direction) of belt 5C to apply tension to sheet substrate P in the longitudinal direction so that sheet substrate P is adsorbed onto belt 5C without wrinkles.

[0019] The solvent (including the dispersion medium) for the solution Lq stored in the solution tank 10 is pure water, which is easy to handle and highly safe. Nanoparticles, such as indium tin oxide (ITO), a material for transparent conductive films, are dispersed in the solvent (pure water) at a desired concentration. The solution Lq in the solution tank 10 is intermittently or continuously supplied to the mist generator (atomizer) 14 by a precision pump 12. The mist generator 14 is installed in a sealed outer container 14D (see FIG. 25) and includes an inner container (cup) 14A that stores the solution Lq from the precision pump 12, and an ultrasonic vibrator 14C that applies vibrations of approximately 2.4 MHz to the solution Lq via the inner container 14A to generate mist from the liquid surface of the solution Lq. Furthermore, a carrier gas CGS, adjusted to a predetermined flow rate (or pressure) by a flow control valve 15, is supplied to the upper space of the inner container 14A of the mist generator 14 through a pipe 16. In the above configuration, the precision pump 12, ultrasonic vibrator 14C, and flow control valve 15 each receive commands from a higher-level controller (such as a general control computer) not shown in the figure and are driven with appropriate drive amounts, timing, intervals, etc.

[0020] If nanoparticles used as film-forming materials tend to aggregate in pure water, adding a surfactant to the solvent of the solution Lq at a predetermined concentration can suppress nanoparticle aggregation and maintain dispersibility. If adding a surfactant to the solution Lq is not desired, an oscillator can be provided to apply ultrasonic vibrations (frequency of 200 kHz or less) to the solution Lq in the inner container 14A to suppress nanoparticle aggregation, as disclosed in International Publication No. 2017 / 154937. Non-rectangular ITO nanoparticles (aligned crystals) made by the methods disclosed in International Publication Nos. 2019 / 138707 and 2019 / 138708 can be used as ITO (indium tin oxide) nanoparticles. These nanoparticles can be maintained dispersed for long periods of time without aggregation or precipitation, even in a solution Lq made of pure water without containing a surfactant.

[0021] In addition to the ITO nanoparticles mentioned above, nanoparticles that can be deposited using the MDE mist deposition system can be nanoparticles of a variety of materials (conductive, insulating, and semiconductive). While nanoparticles are generally considered to be smaller than 100 nm, in mist deposition, they need only be smaller than the mist particle size (several microns to several dozen microns) and capable of being captured in the mist and suspended by the carrier gas CGS. Examples of such nanoparticles include metal nanoparticles such as gold nanoparticles, platinum nanoparticles, silver nanoparticles, and copper nanoparticles, as well as carbon nanorods (tubes) refined to be good conductors. Oxide nanoparticles include iron oxide nanoparticles, zinc oxide nanoparticles, and silicon oxide (silica) nanoparticles. Nitride nanoparticles include silicon nitride nanoparticles and aluminum nitride nanoparticles. Semiconductor nanoparticles include carbon nanorods (tubes) and silicon nanoparticles refined to be semiconductors. The silicon nanoparticles may be, for example, silicon nanoparticles terminated with hydrocarbon molecules, which are formed (applied) on the surface of a semiconductor layer that forms a pn junction solar cell to improve its efficiency, as disclosed in International Publication No. 2016 / 185978.

[0022] As shown in FIG. 1, the mist generated in the inner vessel 14A of the mist generating unit 14 is carried by the flow of the carrier gas CGS through the pipe 17 and supplied to the mist ejection unit 30 as mist gas Msg. The carrier gas CGS can be clean air (HO: clean air) from which dust particles have been removed, or an inert gas such as clean nitrogen (N) gas or argon (Ar) gas. In this embodiment, the mist film is simply formed under atmospheric pressure at room temperature, so the carrier gas CGS is clean air or nitrogen gas. However, as disclosed in International Publication No. 2016 / 133131, for example, in a configuration in which the mist gas Msg sprayed onto the sheet substrate P is irradiated with plasma in a non-thermal equilibrium state (plasma-assisted mist film formation method), the carrier gas CGS should be argon gas.

[0023] If it is necessary to set the temperature of the mist gas Msg sprayed from the mist jetting part 30 higher (or lower) than room temperature, a temperature control mechanism (heater, cooler, etc.) is provided as necessary to adjust the temperature of the carrier gas CGS, the temperature inside the mist generating part 14, or the temperature inside the pipe 17 to a set value. Also, as shown in Fig. 1, the mist generating part 14 (inner container 14A) should be positioned above the mist jetting part 30 in the direction of gravity (Z direction).

[0024] The mist gas Msg supplied from the top of the mist jetting unit 30 is sprayed at a predetermined flow rate (wind speed) onto the substrate P from a slit-shaped opening (nozzle opening) formed in the bottom of the mist jetting unit 30 facing the sheet substrate P. The nozzle opening is formed with a length that covers the width dimension of the substrate P in the Y direction or a length that is shorter than the width dimension, and is formed with a width of about 1 mm to several mm in the X direction, which is the longitudinal direction of the substrate P. When the transport (movement) direction of the longitudinal direction of the substrate P is defined as the +X direction, the mist collection unit 32 is disposed downstream of the mist jetting unit 30 with respect to the transport direction of the substrate P. The mist gas Msg sprayed downward (-Z direction) from the nozzle opening at the bottom of the mist ejection section 30 flows downstream (+X direction) along the surface of the sheet substrate P passing through the chamber section 40 due to the decompression effect (negative pressure) in the mist collection section 32, and during this time the mist adheres to the surface of the sheet substrate P, forming a thin liquid film of the mist solvent (pure water in this embodiment) on the surface of the sheet substrate P.

[0025] A recovery port portion (recovery opening) extending in a slot shape in the Y direction is formed at the bottom of the mist collection unit 32, and excess mist gas Msg', including mist that has not adhered to the sheet substrate P, flows into the recovery opening and is taken into a mist gas collection unit 34, which has a reduced-pressure source such as a vacuum pump, via a pipe 33 connected to the top of the mist collection unit 32. The mist gas collection unit 34 (hereinafter simply referred to as the collection unit 34) returns the mist contained in the collected excess mist gas Msg' to a state of solution Lq by condensation, and sends it to a collection tank 36 via a tube 35A. The solution Lq stored in the collection tank 36 is appropriately replenished into the solution tank 10 and reused.

[0026] Furthermore, in this embodiment, as will be described in detail later, a droplet collection unit (trap unit) 30T is provided below the mist spraying unit 30 to prevent droplets formed by the aggregation of mist adhering to the inner wall surface of the mist spraying unit 30 from traveling along the inner wall surface and dripping onto the sheet substrate P from a nozzle opening at the bottom of the mist spraying unit 30. Similarly, a droplet collection unit (trap unit) 32T is provided below the mist collecting unit 32 to prevent droplets formed by the aggregation of mist (excess mist) adhering to the inner wall surface of the mist collecting unit 32 from traveling along the inner wall surface and dripping onto the sheet substrate P from a collection opening at the bottom of the mist collecting unit 32. The droplets collected by the droplet collection unit 30T are restored to their original state as solution Lq and are sucked by a small pump 37 via a tube 35B and sent to a collection tank 36. Similarly, the droplets collected by droplet collecting section 32T are returned to the original state of solution Lq and are sucked by small pump 37 through tube 35C and sent to collection tank .

[0027] The chamber section 40 is provided with a plate-shaped air guiding member (also called a skirt member or a flow rectifying member) 40A that forms a predetermined space in the +Z direction from the surface of the sheet substrate P in order to smoothly flow the mist gas Msg from the nozzle opening at the bottom of the mist ejection section 30 to the recovery opening at the bottom of the mist recovery section 32. As is clear from the configuration of FIG. 1, the surface of the sheet substrate P moves in the +X direction while being exposed to the laminar flow of the mist gas Msg from the nozzle opening of the mist ejection section 30 to the recovery opening of the mist recovery section 32. By adjusting the relationship between the moving speed of the sheet substrate P by the conveyance unit 5 and the flow rate of the mist gas Msg flowing along the surface of the sheet substrate P, it is possible to finally change the thickness of the film formed by the nanoparticles (such as ITO) deposited on the surface of the sheet substrate P. The materials constituting the chamber section 40 (air guiding member 40A), the mist ejection section 30, the mist recovery section 32, the droplet collection sections 30T and 32T, etc. are preferably resin materials that are chemically stable, excellent in heat resistance and chemical resistance, have high electrical insulation, and are easy to process. As such a resin material, a fluororesin (fluorocarbon resin) such as polytetrafluoroethylene (PTFE) composed of fluorine atoms and carbon atoms is suitable.

[0028] In the configuration of FIG. 1, when the ejection flow rate per unit time of the mist gas Msg ejected from the nozzle opening of the mist ejection section 30 is Qf (mL / sec) and the exhaust flow rate per unit time at the recovery opening of the mist recovery section 32 is Qv (mL / sec), it is preferable to set the relationship of Qf≒Qv or the relationship of Qf<Qv. According to fluid simulation, when the exhaust flow rate Qv is made 1.5 times or more the ejection flow rate Qf, almost all of the mist gas Msg sprayed into the chamber section 40 can be recovered. The balance between the ejection flow rate Qf and the exhaust flow rate Qv can be easily set by the flow rate adjustment valve 15 that controls the flow rate of the carrier gas CGS and the flow rate adjustment of the decompression source of the mist gas collection section 34 connected to the pipe 33.

[0029] 1, a processing unit that makes the surface of the sheet substrate P lyophilic can be provided upstream of the chamber section 40 (or nip rollers 5E, 5F). Furthermore, a drying unit that evaporates a thin liquid film (water film) having a thickness of about several μm to several tens of μm that covers the surface of the sheet substrate P immediately after the mist film is formed in the chamber section 40 can be provided downstream of the chamber section 40.

[0030] Furthermore, in this embodiment, a mist supply unit 31 is provided to improve the rate at which the mist contained in the mist gas Msg adheres to the sheet substrate P. The mist supply unit 31 supplies mist to the space between the surface of the sheet substrate P and the chamber 40. This mist supply unit 31 includes a mist jetting unit 30 and a mist charging device (charge applying unit) 60 that imparts a negative charge to the mist in the mist gas Msg supplied into the space of the mist jetting unit 30 via a pipe 17. This allows the mist jetting unit 30 to supply mist charged by the mist charging device 60 to the space between the surface of the sheet substrate P and the chamber 40. Also, in this embodiment, an electrostatic field generating device (electrostatic field generating unit) 70 is provided that applies an electrostatic field in the Z direction to the space within the chamber 40 to efficiently adhere the charged mist to the sheet substrate P. The mist charging device 60 repeatedly applies high-voltage pulses of several kV or more between a pair of electrodes Ea and Eb located on the upper portions of the inner wall surfaces of the mist spraying unit 30 facing in the X direction, generating a discharge (corona discharge, etc.) between the electrodes Ea and Eb and negatively charging the mist. The electrostatic field generator 70 applies a negative electrostatic field via wiring 70a to an electrode plate Ec attached flat to the lower portion of each of the inner wall surfaces facing in the X direction of the mist spraying unit 30 and an electrode plate Ed attached flat to the inner wall surface (parallel to the XY plane) of the air guide member 40A of the chamber 40. The electrostatic field generator 70 also applies a positive electrostatic field to a contact (brush) 71 that contacts the belt (made of stainless steel) 5C on the roller 5A side of the conveying device.

[0031] The potential difference between the positive and negative electrodes of the electrostatic field generator 70 is adjusted appropriately between several volts and several hundred volts depending on the flow rate of the mist gas Msg flowing through the chamber 40, the transport speed of the sheet substrate P, the type of mist solvent, the type of nanoparticles contained in the mist, the target thickness of the nanoparticle thin film, and other factors. Because the mist contained in the mist gas Msg ejected from the nozzle opening of the mist ejection unit 30 is negatively charged, the mist floating within the chamber 40 is subjected to a force (repulsive force) that moves it away from the negative electrode plate Ed on the air guide member 40A side and a force (Coulomb force) that attracts it toward the positive belt 5C. Because the belt 5C is in close contact with the sheet substrate P, the mist flowing in the +X direction within the chamber 40 on the mist gas Msg is deflected toward the surface of the sheet substrate P, improving the adhesion rate of the mist to the surface of the sheet substrate P.

[0032] The charged mist is subjected to a force (Coulomb force) in the -Z direction only in the space where the electrode plate Ed on the air guide member 40A side faces the belt 5C. Therefore, if the distance in the X direction from the nozzle opening of the mist ejection unit 30 to the collection opening of the mist collection unit 32 is short, the length of the electrode plate Ed in the X direction also becomes short. If the flow velocity of the mist gas Msg is fast, much of the mist may be collected by the mist collection unit 32 before effectively adhering to the sheet substrate P. In this case, the potential difference applied by the electrostatic field generator 70 between the electrode plate Ed and the belt 5C can be increased. Conversely, if the flow velocity of the mist gas Msg flowing through the chamber unit 40 is slow, much of the mist will adhere to the sheet substrate P. This will result in an excessively thick liquid (water) film covering the surface of the sheet substrate P (e.g., 0.5 mm or more), causing the liquid (solvent) to flow on the surface of the sheet substrate P. In this case, it is sufficient to reduce the potential difference applied between electrode plate Ed and belt 5C from electrostatic field generator 70. Note that the absolute value of the potential difference applied from electrostatic field generator 70 is preferably a constant DC voltage, but, for example, the belt 5C side may be at zero potential (earth) and the electrode plate Ed side may be a pulsating voltage (AC voltage) whose absolute value changes with a predetermined amplitude and a predetermined frequency around a negative neutral potential (average potential). In other words, the neutral potential (average potential) is the average value of the maximum and minimum values ​​of the potential of the pulsating voltage (AC voltage).

[0033] Fig. 2 is a perspective view of the arrangement of the film-forming unit, which is composed of the mist jetting unit 30, mist collection unit 32, and chamber unit 40 of the mist film-forming apparatus MDE shown in Fig. 1, seen from diagonally above, Fig. 3A is a front view of the configuration of the mist jetting unit 30 shown in Fig. 1 and Fig. 2 in the YZ plane, seen from the +X direction, and Fig. 3B is a cross-sectional view of the mist jetting unit 30 in Fig. 3A, taken along the k1-k2 arrow. The same symbols or numbers are used for the components in Fig. 2, Fig. 3A, and Fig. 3B as those described in Fig. 1, and detailed descriptions thereof will be omitted or simplified.

[0034] 2, two pipes 17a and 17b corresponding to the pipe 17 shown in FIG. 1 are connected to the top of the mist jetting part 30. Each of the pipes 17a and 17b branches the mist gas Msg generated from one of the mist generating parts 14 in FIG. 1 and supplies it to the mist jetting part 30, but the number of pipes 17 may be three or more. In this way, by arranging multiple pipes 17 at predetermined intervals in the Y direction of the mist jetting part 30 and supplying the mist gas Msg to the internal space of the mist jetting part 30, it is possible to suppress unevenness in the flow rate distribution (or flow velocity distribution) in the Y direction of the mist gas Msg from the nozzle opening 30A, which extends like a slit in the Y direction at the bottom of the mist jetting part 30 shown in FIGS. 3A and 3B, and to make it uniform. In order to increase the total flow rate of the mist gas Msg, a mist generating unit 14 may be provided individually for each of the two pipes 17a, 17b (or three or more pipes).

[0035] 2, one electrode Ea, to which high voltage is applied from the mist charging device 60 shown in Fig. 1, is fixed to an insulating ceramic plate 30Na provided on the wall surface on the -X direction side of the mist jetting part 30 as shown in Fig. 3B, and the other electrode Eb is fixed to an insulating ceramic plate 30Nb provided on the wall surface on the +X direction side of the mist jetting part 30 as shown in Fig. 3B. In this embodiment, as shown in Figs. 3A and 3B, the electrodes Ea are needle-shaped with sharp tips and are attached to the ceramic plate 30Na at regular intervals in the Y direction, and the electrodes Eb are attached to the ceramic plate 30Nb as plates (or rods or stripes) extending along the Y direction with multiple needle-shaped electrodes Ea lined up.

[0036] As shown in FIG. 3B, when viewed in the XZ plane, the interior space of the mist sprayer 30 is surrounded by inner wall surfaces parallel to the YZ plane and spaced apart in the X direction from the top end (top plate) where the pipe 17 (17a) is connected to a height Zu in the -Z direction. The opposing inner wall surfaces are shaped so that the distance between them in the X direction gradually decreases from the height Zu to the nozzle opening 30A at the bottom of the mist sprayer 30, ultimately narrowing the width in the X direction to a few millimeters or less at the nozzle opening 30A. As shown in FIG. 3A, the electrode plate Ec shown in FIG. 1 is attached to each of the inner wall surfaces facing in the X direction of the mist sprayer 30, covering almost the entire inner wall surface in the Y direction. The electrode plate Ec applies a repulsive force to the mist charged by the mist charging device 60, reducing adhesion of the mist to the inner wall surfaces of the interior space. However, if the inner wall surface of the mist ejection part 30 is made of a highly liquid-repellent fluororesin (PTFE), the electrode plate Ec can be omitted.

[0037] As shown in Figures 2 and 3B, droplet collection units 30T extending in the Y direction are provided below each of the outer wall sections of the mist spraying unit 30 in the +X and -X directions. The droplet collection units 30T are connected to slots (grooves) 30s formed in the inner wall surface of the mist spraying unit 30, slightly spaced in the +Z direction from the nozzle opening 30A at the bottom of the mist spraying unit 30, and extending in the Y direction. The thickness (groove width) of the slots 30s in the Z direction is set to a value such that droplets flowing along the inner wall surface of the mist spraying unit 30 are absorbed by capillary action, for example, 0.5 mm to 2 mm. Furthermore, the inner surfaces of the slots 30s are surface-treated (such as by forming a lyophilic coating) to make them highly lyophilic. The droplet collecting section 30T sucks out droplets accumulated in the slots 30s at appropriate intervals by the suction force of the small pump 37 shown in FIGS. 1 and 2, and sends them to the collecting tank 36 via the tube 35B.

[0038] Droplet collectors 32T extending in the Y direction are also provided below the outer wall portions in the +X and -X directions of the mist collector 32 shown in Fig. 2. Slots (grooves) extending in the Y direction are also formed on the inner wall surface slightly away in the +Z direction from the slit-shaped collection opening at the bottom of the mist collector 32, and droplet collectors 32T suck out droplets accumulated in the slots 30s at appropriate intervals using the suction force of the small pump 37 shown in Figs. 1 and 2, and send them to collection tank 36 via tube 35C.

[0039] As shown in Fig. 1, a planar electrode plate Ed is provided on the inner wall surface (parallel to the XY plane) of the air guide member 40A of the chamber section 40, but in Fig. 2, the electrode plate Ed is shown as two electrode plates Ed1 and Ed2 divided in the conveyance direction (X direction) of the sheet substrate P. The electrode plate Ed1, which is arranged on the upstream side in the conveyance direction of the sheet substrate P, is electrically connected to a connection terminal JH1 protruding from the upper outer wall surface of the air guide member 40A, and the connection terminal JH1 is connected to the negative wiring 70a of the electrostatic field generator 70 in Fig. 1. Similarly, the electrode plate Ed2, which is arranged on the downstream side in the conveyance direction of the sheet substrate P, is electrically connected to a connection terminal JH2 protruding from the upper outer wall surface of the air guide member 40A, and the connection terminal JH2 is connected to the negative wiring 70a of the electrostatic field generator 70.

[0040] As shown in FIG. 2, when the electrode plate Ed is divided in the transport path between the mist ejection unit 30 and the mist collection unit 32 in the chamber 40, the negative voltage applied to the upstream electrode plate Ed1 and the negative voltage applied to the downstream electrode plate Ed2 can be adjusted to different values. To achieve this, a variable resistor is provided between the positive and negative poles of the voltage output stage of the electrostatic field generator 70, and the voltage (negative polarity) divided by the variable resistor is applied to one of the electrode plates Ed1 and Ed2, while the voltage (negative polarity) before voltage division is applied to the other. In this way, by applying different negative potentials to the electrode plates Ed1 and Ed2 on the upstream and downstream sides of the transport direction of the sheet substrate P, the degree of adhesion of the mist to the surface of the sheet substrate P can be adjusted over time. The electrode plate Ed may be divided into three or more sections along the transport direction of the sheet substrate P through the chamber 40, and each divided electrode plate may be set to a different negative potential.

[0041] [Variation 1] In the first embodiment described above, during mist film formation, the sheet substrate P is supported on the horizontally moving belt 5C, and the mist gas Msg is sprayed onto the surface of the sheet substrate P while maintaining the surface in a horizontal position (parallel to the XY plane). In this configuration in which the sheet substrate P is supported by the belt 5C, the sheet substrate P can be a single sheet substrate with fixed length and width dimensions, such as A4, A3, or B4. However, when continuously forming a mist film with a stable film thickness on a long sheet substrate of tens to hundreds of meters using a roll-to-roll method, there is a concern that wrinkles may occur due to vacuum suction of the sheet substrate to the belt 5C. Therefore, it is possible to use a conveying mechanism that continuously moves the sheet substrate by closely supporting a portion of the sheet substrate in the longitudinal direction on the outer circumferential surface of a rotating drum.

[0042] Figure 4 is a diagram showing a schematic modified configuration of a mist film formation unit in a mist film formation device that uses a conveying mechanism (conveying unit) with a rotating drum. The Cartesian coordinate system XYZ in Figure 4 is the same as the coordinate systems XYZ in each of Figures 1 to 3B, with the Z direction set as the vertical direction (direction of gravity) and the XY plane set as the horizontal plane. Furthermore, of the components shown in Figure 4, the same reference numerals are used to designate components that are the same as or have equivalent functions to those shown in Figures 1 to 3B.

[0043] In FIG. 4, a rotating drum DR made of metal, such as iron or aluminum, rotates around a center line AXo parallel to the Y axis and has an outer peripheral surface DRa with a constant radius Rd from the center line AXo. The length of the outer peripheral surface DRa in the Y direction is set slightly longer than the width dimension of the long sheet substrate P in the short direction (Y direction). However, the radius Rd can be set relatively freely, depending on the width dimension, and is set within the range of 5 cm≦Rd≦50 cm, for example. Metal shafts Sft are provided at both ends of the rotating drum DR in the Y direction, coaxial with the center line AXo. The shafts Sft are attached to the main frame (housing) of the mist deposition apparatus MDE via bearings and connected to the torque shaft of a rotational drive source (motor or reducer), not shown, to rotate the rotating drum DR at a predetermined angular velocity. A scale disk SD for encoder measurement is fixed coaxially with the center line AXo to the shaft Sft, located away from the Y end of the rotating drum DR in the Y direction. On the surface of the scale disk SD perpendicular to the center line AXo (a surface parallel to the XZ plane), graduations Gm that can be read by the encoder head EH1 are engraved in the circumferential direction in an annular band pattern within a certain radius from the center line AXo. The encoder head EH1 is disposed opposite the side surface (parallel to the XZ plane) of the scale disk SD, and is used to optically detect changes in the position of a grating of the graduations Gm (for example, a diffraction grating engraved at a 20 μm pitch in the circumferential direction) that moves circumferentially in response to the clockwise rotation of the rotating drum DR, and to measure the amount of circumferential movement of the outer peripheral surface DRa or the circumferential movement speed of the outer peripheral surface DRa from the rotational angle position of the rotating drum DR.

[0044] The sheet substrate P is folded back by a roller 5G disposed below the rotating drum DR, which has a rotation axis parallel to the center line AXo. The roller 5G is then applied with a certain amount of tension around a portion of the outer peripheral surface DRa of the rotating drum DR, supported in an arc shape, and wound around the roller 5H, which has a rotation axis parallel to the center line AXo and is disposed above the rotating drum DR, and conveyed in the longitudinal direction. During this process, the sheet substrate P is in close contact with the outer peripheral surface DRa over a range of approximately 90 degrees from an angular position (entrance position) Ct1 to an angular position (detachment position) Ct2 in the circumferential direction of the rotating drum DR. The mist film-forming unit, comprised of the mist ejection unit 30, the mist collection unit 32, and the chamber unit 40, is curved and positioned in the circumferential direction within the angular range between the entry position Ct1 and the detachment position Ct2 of the outer peripheral surface DRa of the rotating drum DR.

[0045] 4, the chamber 40 has a curved air guide member 40A that forms a fixed gap from the outer peripheral surface DRa or the surface of the sheet substrate P in the radial direction of the rotating drum DR. The mist jetting unit 30 is disposed upstream of the air guide member 40A in the conveyance direction of the sheet substrate P so that the direction of spraying of the mist gas Msg (the direction of the line CL) sprayed from the nozzle opening 30A of the mist jetting unit 30 is tilted at an angle -θu with respect to the horizontal plane (XY plane). By orienting the nozzle opening 30A of the mist jetting unit 30 obliquely upward in this manner, droplets of mist that adhere to and collect on the inner wall surface of the mist jetting unit 30 are prevented from dripping down the inner wall surface from the nozzle opening 30A onto the sheet substrate P. The mist gas Msg ejected from the nozzle opening 30A flows in the space between the curved inner wall surface of the air guide member 40A facing the sheet substrate P and the surface of the sheet substrate P, along the circumferential direction of the outer peripheral surface DRa of the rotating drum DR, and excess mist gas Msg' is collected in the mist collection section 32.

[0046] A curved electrode plate Ed connected to a negative wiring 70a of the electrostatic field generator 70 is attached to the curved inner wall surface of the air guide member 40A, and a contactor 71 that comes into contact with the shaft Sft of the rotating drum DR is connected via a wiring 70b to the positive electrode of the electrostatic field generator 70. As a result, an electrostatic field that attracts the mist toward the sheet substrate P is formed between the curved electrode plate Ed and the outer peripheral surface DRa of the rotating drum DR.

[0047] After passing through the chamber 40, a thin liquid film is formed on the entire surface of the sheet substrate P due to mist film formation, but the sheet substrate P is transported from the release position Ct2 toward the roller 5H while tilted upward at an angle +θp with respect to the horizontal plane (XY plane). The liquid film (solvent) on the surface of the sheet substrate P dries (evaporates) during transport from the release position Ct2 to the roller 5H, and a deposited film (conductive film) of nanoparticles contained in the mist is formed on the surface of the sheet substrate P. The distance L from the release position Ct2 to the roller 5H is set by the product (L = Vp · Tv) of the transport speed Vp of the sheet substrate P (the rotation speed of the rotating drum DR) and the time Tv until the liquid film covering the surface of the sheet substrate P has completely dried (evaporated) immediately after the mist film formation. It is advisable to provide a mechanism that can change the position of roller 5H in the Z direction and X direction so that the inclination angle +θp of the sheet substrate P from the release position Ct2 to roller 5H can be adjusted within the range of 0°≦θp<50° depending on the type of mist solvent (liquid film).

[0048] The encoder head EH1 is positioned facing the scale Gm of the scale disc SP so that its orientation is the same as that of the chamber section 40 when viewed from the center line AXo, or the same as that of the nozzle openings 30A of the mist ejection section 30. Therefore, if the mist gas Msg leaks from the gap between the chamber section 40 and the outer peripheral surface DRa of the rotating drum DR, the mist gas Msg may adhere to optical components, etc., inside the encoder head EH1, causing problems in reading the scale Gm (such as a reduction in signal strength). In such a case, as shown by the dashed line in Figure 4, the encoder head EH2 can be positioned in an orientation point-symmetrical to the encoder head EH1 with respect to the center line AXo (a position rotated approximately 180 degrees), i.e., at the position farthest from the chamber section 40. In the configuration of Figure 4, the encoder head EH1 or EH2 is arranged to face the side surface perpendicular to the center line AXo of the scale disc SD, but if the scale Gm is formed along the outer peripheral surface parallel to the center line AXo of the scale disc SD, the encoder head EH1 (or EH2) and the scale disc SD should be arranged as shown in Figure 5, which is a second modified example.

[0049] [Variation 2] FIG. 5 is a partial cross-sectional view of the rotating drum DR and chamber 40 taken along a plane that includes the center line AXo and line CL shown in FIG. 4 and passes through the nozzle opening 30A of the mist ejection unit 30. In FIG. 5, the rotating drum DR is hollow to reduce weight, and the shaft Sft is disposed so as to penetrate both ends of the rotating drum DR in the Y direction. The sheet substrate P is tightly supported on the outer peripheral surface DRa of the rotating drum DR, which has a radius Rd. The scale disk SD of the encoder measurement system is fixed coaxially with the shaft Sft on the -Y direction side of the rotating drum DR. The radius of the scale disk SD in FIG. 5 is set to be approximately the same as the radius Rd of the rotating drum DR (a radius of ±10% of the radius Rd), and the scale Gm is formed on the outer peripheral surface of the scale disk SD. Therefore, the encoder head EH1 (or EH2) is disposed radially of the scale disk SD so as to face the scale Gm.

[0050] The inner wall surface of the air guide member 40A of the chamber 40 is curved in the circumferential direction following the outer peripheral surface DRa of the rotating drum DR so that a space of a constant distance ΔSv (several mm to several tens of mm) is formed from the surface of the sheet substrate P in the radial direction. The mist gas Msg from the nozzle opening 30A of the mist ejection unit 30 is ejected in the normal direction to the surface of the sheet substrate P and then flows circumferentially through the space of the distance ΔSv. In this modification, radially extending flange portions (skirts) 41A and 41B are provided at the Y-direction ends of the air guide member 40A to prevent the mist gas Msg from leaking from the space of the distance ΔSv toward the Y direction (encoder head EH1 side). The flange portions 41A and 41B are formed in a fan shape when viewed in a YZ plane perpendicular to the center line AXo, and the distance from the center line AXo to the tip positions of the flange portions 41A and 41B on the shaft Sft side is formed to be smaller than the radius Rd of the rotating drum DR. The distance between each of the flange portions 41A, 41B and the side end surface of the rotating drum DR in the Y direction is set to be a small gap of, for example, about 1 mm to several mm.

[0051] As a result, mist gas Msg leaking from the space of the distance ΔSv toward the outside of the chamber 40 (Y direction) flows toward the shaft Sft (radial direction) through the gap between the flange portions 41A, 41B and the Y-direction side end face of the rotating drum DR, preventing it from spraying near the encoder head EH1. Furthermore, in this modified example, a disk-shaped windshield 45 is provided coaxially with the shaft Sft between the scale disc SD and the -Y-direction side end face of the rotating drum DR. The radius of the windshield 45 from the center line AXo is set to be larger than the radius Rd of the rotating drum DR (or the radius of the scale disc SD), and preferably is set to cover the radial distance from the center line AXo to the encoder head EH1, as shown in FIG. 5. As a result, mist gas Msg leaking from the flange portion 41A toward the outside of the chamber 40 (Y direction) through the space of the distance ΔSv is prevented from being sprayed onto the graduations Gm of the scale disc SD. In addition, if the leaked mist gas Msg is sufficiently prevented from spraying onto the encoder head EH1 or the graduations Gm of the scale disc SD, either the flange portion 41A or the wind shielding plate 45 can be omitted.

[0052] Furthermore, in order to maintain a constant radial distance ΔSv between the curved inner wall surface of the air guide member 40A attached to the chamber section 40 (or the tip of the nozzle opening 30A of the mist ejection section 30) and the sheet substrate P, in this modification, rolling elements (bearings) 43A, 43B are attached to the inside (rotating drum DR side) of each of the flange sections 41A, 41B. The rolling elements 43A have rotation axes parallel to the center line AXo and abut against the Y-direction ends of the outer circumferential surface DRa of the rotating drum DR. When viewed in the XZ plane, the rolling elements 43A are provided at two circumferentially spaced positions on the fan-shaped flange section 41A, and similarly, when viewed in the XZ plane, the rolling elements 43B are provided at two circumferentially spaced positions on the fan-shaped flange section 41B. 4, the chamber section 40 is disposed on the -X direction side of the rotating drum DR, and is therefore biased in the +X direction so that a total of four rolling elements 43A, 43B are always in contact with the outer peripheral surface DRa of the rotating drum DR. Each of the rolling elements 43A, 43B provided at four locations may be an air pad that ejects gas so as to form an air bearing (hydrostatic gas layer) between itself and the outer peripheral surface DRa.

[0053] As described above, according to the first embodiment, modified example 1, and modified example 2, there is provided a mist generating unit 14 as a mist generating mechanism that sends out mist gas Msg containing mist generated by atomizing a solution Lq containing fine particles of a material substance, a mist ejection unit 30 as a mist ejection mechanism that receives the mist gas Msg and ejects it toward a sheet substrate P as a substrate to be processed, and an air guide mechanism that is made up of an air guide member 40A having an inner wall surface facing the surface of the sheet substrate P at a predetermined distance (ΔSv) in order to flow the mist gas Msg from the mist ejection unit 30 along the surface of the sheet substrate P. The chamber section 40 serves as a mist guide mechanism that generates a repulsive force (a rebound force) between the inner wall surface of the air guide member 40A of the chamber section 40 and the mist, thereby generating an attractive force that draws the mist to the surface of the sheet substrate P. By providing an electrostatic field generator 70 that generates an electrostatic field between the belt 5C (or rotating drum DR) that supports the sheet substrate P and the electrode plate Ed installed on the air guide member 40A, the adhesion rate of the mist to the surface of the sheet substrate P is improved, thereby providing a mist film formation device that improves the film layer formation rate by the deposition of fine particles of the material substance.

[0054] Second Embodiment FIG. 6 is a schematic diagram showing the overall configuration of a mist film-forming apparatus MDE according to a second embodiment, in which the Cartesian coordinate system XYZ is set with the Z direction as the direction of gravity, as in FIG. 1. The mist film-forming apparatus MDE of FIG. 6 is configured, as in FIG. 4, to transport a long sheet substrate P in the longitudinal direction by rotation of a rotating drum DR that supports the cylindrical surface of the long sheet substrate P. Furthermore, in the mist film-forming apparatus MDE of FIG. 6, components and components having the same functions as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and their descriptions are omitted or simplified. In this embodiment, before the solvent (e.g., pure water) of the thin liquid film formed on the surface of the sheet substrate P by mist film formation dries, the nanoparticles contained in the liquid film are vibrated by an electrical force, thereby uniforming the uneven thickness distribution of the nanoparticles deposited on the surface of the sheet substrate P.

[0055] 6, the sheet substrate P is wrapped around the conductive outer peripheral surface DRa of the rotating drum DR via rollers 5G, and after mist film formation under a chamber 40 having a mist ejection unit 30 and a mist collection unit 32, the sheet substrate P is transported substantially horizontally in the +X direction from the upper end of the outer peripheral surface DRa of the rotating drum DR in the +Z direction while maintaining a constant tension. The horizontally transported sheet substrate P is supported by multiple rollers 5J aligned in the transport direction (X direction) and bent downward (in the -Z direction) by the last roller 5H. In this embodiment, a drying process is performed on the horizontal transport path of the sheet substrate P supported by the multiple rollers 5J to dry the liquid film (solvent such as pure water) formed on the surface of the sheet substrate P by mist film formation. For this drying process, an exhaust drying unit (drying unit) 85 is disposed above the horizontal transport path of the multiple rollers 5J, which sucks up gas (air) near the surface of the horizontally transported sheet substrate P via an exhaust duct 86.

[0056] Furthermore, in chamber 40 constituting the mist film formation unit of this embodiment, mist collection units 32' similar to mist collection unit 32 are attached not only downstream of mist jetting unit 30 but also upstream with respect to the curved transport direction of sheet substrate P, and excess mist gas Msg' flowing upstream from mist jetting unit 30 is collected by mist gas collection unit 34 shown in Fig. 1 via pipe 33'. The jetting direction of mist gas Msg from nozzle opening 30A of mist jetting unit 30 of this embodiment is set so that, when viewed in the XZ plane, it is inclined within the range of 0° to -90° (preferably -45°) with respect to a plane that is parallel to the YZ plane and includes center line AXo, as shown by line CL in Fig. 6.

[0057] The rotating drum DR is rotated by a motor included in a rotation drive unit 80 coupled to the shaft Sft, and the rotation drive unit 80 servo-controls the motor so that the outer peripheral surface DRa (sheet substrate P) of the rotating drum DR is moved precisely at a commanded peripheral speed, based on speed information measured from a detection signal from an encoder head EH2 that reads the graduations Gm of the scale disc SD and command information from a drive circuit 82. The command information given to the drive circuit 82 is generated by a control unit (CPU) 100 that performs overall control of the entire apparatus.

[0058] Furthermore, in this embodiment, on the back surface side (-Z direction side) of the sheet substrate P that has separated from the rotating drum DR and is moving along the horizontal transport path, a plurality of electrode plates Ef1-Ef4 are arranged parallel to the sheet substrate P between each of the plurality of rollers 5J in the X direction. The electrode plates Ef1-Ef4 are arranged at a fixed interval (for example, several mm or more) from the back surface of the sheet substrate P. Furthermore, on the top surface side (+Z direction side) of the sheet substrate P that has separated from the rotating drum DR and is moving along the horizontal transport path, a mesh-shaped electrode plate (mesh electrode) Em having an area sufficient to cover the entire electrode plates Ef1-Ef4 is arranged parallel to the sheet substrate P between the sheet substrate P and the exhaust drying unit 85. The electrode plate Em is arranged at a fixed interval (for example, several mm or more) from the top surface of the sheet substrate P. The interval in the Z direction between the electrode plate Em and the electrode plates Ef1-Ef4 (the inter-electrode gap) is approximately constant along the X direction and is set to, for example, a range of 10 to 30 mm. An AC potential is applied between the electrode plates Ef1 to Ef4 and the electrode plate Em via the wiring Wa and Wb from the AC electric field generator 90. The AC potential is set by a command from the control unit 100.

[0059] FIG. 7 shows a detailed configuration of the nanoparticle deposition uniformization unit (also referred to as a particle vibration unit or electrophoresis unit) composed of the electrode plate Em and electrode plates Ef1-Ef4 of FIG. 6 and the AC electric field generator 90. In FIG. 7, the same components as those shown in FIG. 6 are denoted by the same reference numerals. The electrode plate Em is, for example, a stainless steel plate with countless openings Emh formed in a matrix pattern, forming a mesh of thin linear portions. The electrode plates Ef1-Ef4 are also formed from stainless steel plates, and the spacing between them in the Z direction is Zh. The AC electric field generator 90 includes an oscillator circuit 90A that generates an AC signal (sine wave) at a frequency fp in accordance with command information Sfc from the control unit 100, and an adjustment circuit 90B that modifies the waveform of the AC signal (sine wave) in accordance with command information Swc from the control unit 100 and adjusts the amplitude of the AC signal in accordance with command information Svc and applies it to the wiring Wa and Wb. The AC voltage Ev of frequency fp applied between the electrode plate Em and the electrode plates Ef1 to Ef4 is a peak amplitude value or an effective amplitude value.

[0060] As shown in FIG. 7, while the sheet substrate P is moving at a velocity Vp in the +X direction, a liquid film (referred to as Lq for convenience) of solution Lq with a thickness Δh formed on the surface (upper surface) of the sheet substrate P generates evaporated components wx as the solvent (e.g., pure water) dries. The evaporated components wx pass through openings Emh in the mesh electrode plate Em and are absorbed by the exhaust drying unit 85. Numerous nanoparticles np exist in the liquid film Lq, either deposited on the surface of the sheet substrate P or floating therein. When an AC electric field generator 90 applies an AC electric field with a frequency fp and a strength that varies in the Z direction to the liquid film Lq in this state, the nanoparticles np vibrate with a migration force fz corresponding to the strength of the AC electric field. This reduces the unevenness of the deposition state and uniforms the film thickness distribution of the deposited nanoparticles np. The electric field generated by the AC voltage Ev is preferably continued until the liquid film Lq on the surface of the sheet substrate P is substantially dry.

[0061] For this reason, if the drying time until the liquid film Lq on the sheet substrate P is mostly dry is Tvp, then the length HGx in the X direction of the electric field space between the electrode plate Em and the electrode plates Ef1 to Ef4 should be set to HGx ≥ Tvp · Vp based on the speed Vp of the sheet substrate P. Furthermore, the drying time Tvp of the liquid film Lq varies depending on the temperature of the sheet substrate P, the temperature and humidity of the ambient environment, the volume of the ambient gas that hits the sheet substrate P, and so on, but in order to shorten the drying time Tvp as much as possible, a heater unit may be provided that raises the temperature of the electrode plates Ef1 to Ef4 arranged on the back side of the sheet substrate P to a value above room temperature (24°C), for example, to a value in the range of several tens of degrees Celsius to 100°C.

[0062] In this way, we confirmed through preliminary experiments that applying an AC electric field to the liquid film Lq on the sheet substrate P before it dries improves the condition of the nanoparticle film that ultimately forms on the sheet substrate P. Figure 8 shows the configuration of a preliminary experimental apparatus used to confirm how applying an AC electric field to the liquid film Lq changes the state of the nanoparticle thin film. In the Cartesian coordinate system XYZ in Figure 8, the Z direction is the direction of gravity, and the XY plane perpendicular to it is the horizontal plane. In the preliminary experimental apparatus, a 50 mm square glass substrate P' is used as a sample onto which a mist gas Msg is sprayed for a certain period of time. The glass substrate P' is placed on a conductive film formed as an electrode plate Ef on the upper surface of an insulating bottom plate BPd. Support pillars HSP with a height Zh in the Z direction are provided on both sides of the bottom plate BPd in ​​the X direction. An insulating top plate BPu is placed on top of the support pillars HSP so that it is parallel to the bottom plate BPd. A conductive film serving as an electrode plate Em is formed on the underside of the top plate BPu. A sinusoidal AC voltage Ev (frequency fp) is applied between the conductive films of the electrode plate Ef and the electrode plate Em via the switch Swo.

[0063] In preliminary experiment 1, first, a solution Lq containing a predetermined concentration (for example, 10 wt.%) of ITO nanoparticles with particle sizes of 30 to 50 nm (average particle size 40 nm) was made into mist gas Msg and sprayed for a certain period of time onto the surface of a glass substrate P' placed on a bottom plate BPd to form a liquid film Lq. Then, the frequency fp of an AC voltage Ev applied until the liquid film Lq dried was examined to see how the resistance of the formed thin film of ITO nanoparticles changed depending on the frequency fp. Figure 9 shows the relationship between the frequency fp (Hz) of the AC voltage Ev and the resistance value (KΩ / cm) of the thin film of ITO nanoparticles. 2 1 is a graph showing experimental results 1 of preliminary experiment 1, with the vertical axis representing the electrical resistance. In preliminary experiment 1, the electrode gap Zh (height of the support HSP) between electrode plates Ef and Em was kept at 20 mm, the AC voltage Ev (effective value) was set to 20 V (i.e., the AC field strength was set to an effective value of 1 V / mm), and the glass substrate P' was replaced to form a liquid film Lq. The resistance values ​​of the ITO nanoparticles formed under AC electric fields with frequencies fp of 1 Hz, 10 Hz, 100 Hz, 1 KHz, 10 KHz, 100 KHz, 1 MHz, 10 MHz, and 100 MHz were measured.

[0064] As shown in Figure 9, in the case of the ITO nanoparticles used in preliminary experiment 1, it was found that the resistance value of the thin film made of ITO nanoparticles was reduced by almost half when the frequency fp was between 200 Hz and 20 KHz. In Figure 9, the highest resistance value obtained when the frequency fp was 0 Hz (no AC field applied) or under an AC field of 10 MHz or higher was approximately 100 KΩ / cm 2 This reduction in resistance due to the application of an AC electric field is thought to be due to the fact that the ITO nanoparticles in the liquid film Lq become polarized and vibrate, mitigating the localized density variation along the surface of the ITO nanoparticles deposited on the surface of the glass substrate P', increasing the number of contact paths (conduction paths) between the ITO nanoparticles within the surface, and increasing the average conductivity of the thin film made of ITO nanoparticles.

[0065] Next, in preliminary experiment 2, the AC voltage Ev was set to 20 V, the frequency fp to 10 KHz, and the electrode spacing Zh was set in the range of 5 mm to 50 mm, and the change in the resistance value of the thin film made of ITO nanoparticles (average particle size 40 nm) was investigated at intervals of 5 mm. Figure 10 shows the change in the resistance value (KΩ / cm) of the thin film of ITO nanoparticles, with the electrode spacing Zh (mm) on the horizontal axis. 2 10 is a graph showing experimental results 2 of preliminary experiment 2, with the vertical axis representing the frequency (fp) of the AC electric field. Based on the findings from preliminary experiment 1, in preliminary experiment 2, the frequency (fp) of the AC electric field was set to 10 kHz, at which the resistance value was lowest. As shown in Figure 10, in preliminary experiment 2, no decrease in resistance was observed when the electrode spacing (Zh) was 40 mm or more. As the electrode spacing (Zh) was narrowed from 40 mm to 20 mm, the resistance value gradually decreased, and when the electrode spacing (Zh) was 20 mm or less, the resistance value remained almost constant. This preliminary experiment 2 indicates that, for the ITO nanoparticles used in this experiment, the strength of the AC electric field applied during drying of the liquid film (Lq) should be at least 0.5 V / mm (20 V / 40 mm) in effective value, and preferably at least 1 V / mm.

[0066] Furthermore, in preliminary experiment 3, the AC voltage Ev was set to 20 V and the electrode spacing Zh to 20 mm, and the dependence of frequency fp was investigated for extremely small ITO nanoparticles with an average particle size of 10 nm, for comparison with the ITO nanoparticles with an average particle size of 40 nm used in preliminary experiments 1 and 2. In preliminary experiment 3, the electrode spacing Zh was kept at 20 mm, the AC voltage Ev (effective value) was set to 20 V, and the glass substrate P' was replaced to form a liquid film Lq. The resistance of the ITO nanoparticles with an average particle size of 10 nm formed under AC electric fields with frequencies fp of 1 Hz, 10 Hz, 100 Hz, 1 kHz, 10 kHz, 100 kHz, 1 MHz, and 10 MHz was measured.

[0067] Figure 11 shows the resistance (KΩ / cm) of the thin film of ITO nanoparticles, plotted against the frequency fp (Hz) of the AC voltage Ev on the horizontal axis. 2 11 is a graph showing experimental results 3 of preliminary experiment 3, with the vertical axis representing the resistance of the ITO nanoparticles. As shown in FIG. 11, in the case of ITO nanoparticles with an average particle size of 10 nm used in preliminary experiment 3, it was found that the resistance of the thin film made of ITO nanoparticles was reduced by almost half when the frequency fp was between 10 Hz and 1 KHz. In addition, in FIG. 11, when the frequency fp was 0 Hz (no AC field applied) or under an AC field of 10 MHz or higher, the highest resistance of the thin film made of ITO nanoparticles with an average particle size of 40 nm was approximately 100 KΩ / cm 2 (Similar to the previous preliminary experiment 1), the highest resistance value of the thin film made of ITO nanoparticles with an average particle size of 10 nm was approximately 150 KΩ / cm 2 From this preliminary experiment 3, it was found that even for nanoparticles made of the same material, the frequency band of the AC electric field that generates the electrophoretic force fz differs depending on the particle size.

[0068] Based on the findings of the above preliminary experiments, the electrode spacing Zh between the electrode plates Ef1-Ef4 and the electrode plate Em of the mist film-forming device MDE shown in Figures 6 and 7, as well as the effective value and frequency fp of the AC voltage Ev applied between the electrodes by the AC electric field generator 90, are set. The optimal values ​​of the spacing Zh, AC voltage Ev, and frequency fp vary depending on the type of solution Lq, the type and particle size of the nanoparticles, etc., and are therefore determined using a preliminary experiment device such as that shown in Figure 8. Note that one reason why the electrophoretic force fz is generated on the nanoparticles in the liquid film Lq is thought to be because the nanoparticles are polarizable.

[0069] The waveform of the AC voltage Ev applied between the electrode plates Ef1 to Ef4 and the electrode plate Em by the AC electric field generating unit 90 of the mist film forming apparatus MDE shown in Figures 6 and 7 can be modified as shown in Figures 12A to 12C. Figure 12A shows a typical sine wave WF1 as an AC voltage, and its characteristics are the frequency fp and the effective value Eva (1 / [2] of the peak value 0.5 ]). Fig. 12B shows a sawtooth wave WF2 with peak values ​​of ±Evp, and Fig. 12C shows a burst waveform WF3 in which a sine wave of frequency fp is attenuated by amplitude modulation every time Tb (Tb>1 / fp). Alternatively, the waveform of the AC electric field may be a square wave whose duty ratio (the ratio of the duration of high level in one cycle of 1 / fp) is adjustable at frequency fp.

[0070] The burst waveform WF3 shown in Figure 12C is obtained by amplitude-modulating the sine wave WF1 shown in Figure 12A with a sawtooth wave WF2 shown in Figure 12B, and includes frequency components including a frequency 1 / Tb determined by time Tb and a frequency fp of the sine wave WF1. Therefore, based on the findings of Experimental Result 1 shown in Figure 9 and Experimental Result 3 shown in Figure 11, the frequency fp can be set to 1 kHz to 10 kHz, and the frequency 1 / Tb can be set to 50 to 500 Hz, for example. By generating AC electric fields at multiple different frequencies in this way, even when the liquid film Lq on the surface of the sheet substrate P contains a mixture of nanoparticles with widely varying particle sizes (for example, a minimum particle size of 10 nm and a maximum particle size of 100 nm), a migration force fz can be effectively applied to each of the nanoparticles.

[0071] [Variation 3] 6, in the deposition uniforming unit composed of electrode plates Em and Ef1-Ef4 and AC electric field generator 90, an AC electric field of constant intensity and frequency fp is applied to the liquid film Lq on the front surface of sheet substrate P during the drying process in which sheet substrate P is transported horizontally in the +X direction. However, because the four electrode plates Ef1-Ef4 arranged on the back surface of sheet substrate P are divided along the horizontal transport path of sheet substrate P, the AC voltage Ev and frequency fp applied to each of electrode plates Ef1-Ef4 may be different. To achieve this, it is necessary to provide multiple oscillator circuits 90A and adjustment circuits 90B in AC electric field generator 90 shown in FIG. 7.

[0072] [Variation 4] The deposition uniforming unit shown in FIG. 7, which is composed of electrode plates Em, Ef1-Ef4 and AC electric field generator 90, can function as long as a liquid film Lq is formed on the sheet substrate P to a thickness that allows migration of nanoparticles np (e.g., several times the particle size of the nanoparticles). Therefore, the process of forming the liquid film Lq on the sheet substrate P is not limited to the mist film-forming method, and the liquid film Lq may be formed using various printing methods (gravure printing, silk printing, die coater printing, etc.) or an inkjet coating device. In particular, when forming conductive wiring patterns, electrode patterns, etc. by selectively applying minute droplets containing metallic nanoparticles to the surface of the substrate P using the inkjet method, the resistance of the wiring patterns or electrode patterns made of nanoparticles formed on the substrate P can be reduced by passing the substrate P through the deposition uniforming unit shown in FIG. 7 before the applied droplets dry.

[0073] [Variation 5] In the second embodiment and modified examples 3 and 4, an AC electric field is applied between the electrode plate Em and the electrode plates Ef1 to Ef4 shown in Fig. 7, that is, in a direction perpendicular to the plane on which the liquid film Lq spreads on the sheet substrate P. However, by changing the configuration and arrangement of the electrode plates, it is possible to change the direction of the electrophoretic force fz acting on the nanoparticles in the liquid film Lq so that it has a vector not only in the vertical direction (Z direction) but also in the horizontal direction (within the XY plane).

[0074] FIG. 13 shows the configuration of the deposition uniforming unit (electrophoresis imparting unit) according to Modification 5. The upper part of FIG. 13 is a top view of the configuration in the XY plane, and the lower part is a front view of the configuration in the XZ plane. In Modification 5, instead of the electrode plate Em arranged on the upper surface of the sheet substrate P, multiple electrode wires (wires or steel wires) Em' are arranged at regular intervals in the X direction (the conveyance direction of the sheet substrate P), each of which extends linearly in the Y direction so as to be longer than the width of the sheet substrate P (Y-direction dimension). Both ends of each of the multiple electrode wires Em' in the Y direction are fixed to a metal frame TF1 and connected to the wiring Wb from the AC electric field generator 90 shown in FIG. 7. Furthermore, in Modification 5, instead of the electrode plates Ef1 to Ef4 arranged on the back side of the sheet substrate P, multiple electrode wires (wires or steel wires) Ef' are arranged at regular intervals in the X direction (the conveyance direction of the sheet substrate P), each of which extends linearly in the Y direction so as to be longer than the width of the sheet substrate P (Y-direction dimension). Both ends of each of the plurality of electrode wires Ef' in the Y direction are fixed to a metal frame TF2 and connected to the wiring Wa extending from the AC electric field generating unit 90 shown in FIG.

[0075] When viewed in the XY plane, the multiple electrode wires Em' on the upper surface of the sheet substrate P and the multiple electrode wires Ef' on the back surface of the sheet substrate P are alternately arranged at regular intervals in the X direction. When an AC voltage Ev is applied between the frames TF1 and TF2 via the wiring Wa and Wb, an AC electric field Fe tilted in the X direction is generated between each of the upper electrode wires Em' and each of the lower electrode wires Ef', as shown in the lower part of Figure 13. As a result, the nanoparticles in the liquid film Lq on the surface of the sheet substrate P are subjected to an electrophoretic force fz tilted in the X direction, i.e., electrophoretic forces in the Z direction and the X direction. This causes the nanoparticles in the liquid film Lq to actively move slightly laterally (vibrate slightly) along the surface of the sheet substrate P, thereby improving the uniformity of the deposition state of the thin film of nanoparticles after drying.

[0076] 13 may be inclined at a certain angle (for example, 45° or 90°) relative to the Y axis (or X axis) in the XY plane while remaining parallel to each other. Furthermore, when viewed in the XY plane, the electrode wires Em' and Ef' do not need to be straight, and may be curved in an arc (bow), zigzag, or wavy.

[0077] According to the second embodiment and Modifications 3 to 5 described above, a film-forming apparatus for depositing fine particles (nanoparticles np) to a predetermined thickness on the surface of a sheet substrate P as a substrate to be processed is provided, which includes a mist film-forming unit for forming a liquid film Lq of a solution containing the nanoparticles np to a predetermined thickness on the surface of the sheet substrate P, or a liquid film-forming unit configured with a printing or inkjet coating device, and a deposition uniforming unit as a migration imparting unit that applies an AC electric field to the liquid film Lq to impart a migration force fz to the nanoparticles np in the liquid film Lq before the liquid film Lq formed on the surface of the sheet substrate P evaporates or volatilizes. Note that the mist film-forming apparatus MDE shown in FIG. 6 closely supports the sheet substrate P with a rotating drum DR having a conductive outer peripheral surface. Therefore, a first electrode (Em) may be provided on the inner wall surface of the chamber unit 40 facing the sheet substrate P, and the outer peripheral surface of the rotating drum DR may be used as a second electrode (Ef), and an AC electric field may be applied between the first electrode (Em) and the second electrode (Ef).

[0078] Third Embodiment Fig. 14 shows a schematic configuration of a mist film-forming apparatus MDE according to the third embodiment, and the Cartesian coordinate system XYZ in Fig. 14 is set to be the same as the Cartesian coordinate systems XYZ in Fig. 1 and Fig. 6. This embodiment combines the mist film-forming unit shown in Fig. 2 of the first embodiment with the deposition uniforming unit shown in Fig. 7 of the second embodiment. Therefore, of the components in Fig. 14, components having substantially the same configuration or function as the components in Fig. 1 and Fig. 6 are assigned the same reference numerals.

[0079] 14, sheet substrate P is supported by a horizontal portion of endless metal belt 5C stretched between rollers 5A and 5B and transported in the -X direction, and mist gas Msg is sprayed onto the surface of horizontally supported sheet substrate P from mist ejection unit 30, mist collection unit 32, and mist film formation unit consisting of chamber unit 40. Belt 5C is electrically connected to wiring Wa from AC electric field generation unit 92 via contactor 71, and electrode plate Ed installed above sheet substrate P in chamber unit 40 (in the +Z direction) is electrically connected to wiring Wb from AC electric field generation unit 92. In this embodiment as well, belt 5C, electrode plate Ed, and AC electric field generation unit 92 form a mist induction mechanism.

[0080] The sheet substrate P, on whose surface a liquid film (Lq) has been formed in the mist film-forming section, is separated from the belt 5C at the position of the roller 5B and transported into the deposition uniforming section along a linear transport path inclined downward by approximately 45° from the horizontal plane (XY plane). Similar to the configuration shown in FIG. 6, the transport path is provided with a plurality of rollers 5J and a plurality of electrode plates Ef1-Ef4 disposed on the back side of the sheet substrate P, and a mesh-like electrode plate Em disposed on the upper surface of the sheet substrate P. The electrode plates Ef1-Ef4 are electrically connected to wiring Wa extending from the AC electric field generator 92, and the electrode plate Em is electrically connected to wiring Wb extending from the AC electric field generator 92. In this embodiment, the deposition uniforming section is also formed by the electrode plates Ef1-Ef4, the electrode plate Em, and the AC electric field generator 92. The electrode plates Ef1 to Ef4 may be changed to a plurality of electrode wires Ef' as shown in FIG. 13, and the electrode plate Em may be changed to a plurality of electrode wires Em' as shown in FIG.

[0081] In this embodiment, both the electrostatic field generated by the mist induction mechanism and the AC electric field generated by the deposition uniformization unit are generated by a single AC electric field generator 92. As described in the previous embodiments and modifications, the mist induction mechanism requires that the electrode plate Ed be generally negatively polarized relative to the belt 5C so as to induce the negatively charged mist toward the sheet substrate P. Therefore, the AC electric field generator 92 is configured to generate an AC voltage Ev as shown in FIG. 15, for example. In FIG. 15, the vertical axis represents the AC voltage Ev and the horizontal axis represents time. The neutral potential (average potential) of the waveform of the AC voltage Ev, whose amplitude is an effective value Eva and whose intensity varies sinusoidally with a frequency fp, is set to −Ene (V) on the negative side relative to zero potential (earth potential of the main body). The absolute value |Eva| of the effective amplitude Eva and the absolute value |Ene| of the neutral potential −Ene are set to satisfy the relationship |Ene| ≧ |Eva|.

[0082] 14, the magnitude of the force attracting the mist to the sheet substrate P changes over time with frequency fp, but the average strength of the electrostatic field becomes neutral potential -Ene, so the effect of improving the adhesion rate of the mist to the sheet substrate P is obtained to the same extent as in the first embodiment. On the other hand, when AC voltage Ev as in Fig. 15 is applied between electrode plates Ef1 to Ef4 and electrode plate Em of the deposition uniforming unit (electrophoresis imparting unit) shown in Fig. 14, an AC electric field that is steadily offset to the negative side and changes in amplitude with effective value Eva is applied to the liquid film Lq on the sheet substrate P, so that an electrophoretic force fz is applied to the nanoparticles in the liquid film Lq, as in the second embodiment.

[0083] FIG. 16 shows an example of a specific circuit within the AC electric field generator 92 that generates the AC voltage Ev shown in FIG. 15. It uses a differential amplifier OPA that can operate at a relatively high power supply voltage ±Vcc (e.g., ±50 V or higher). A voltage +Eni from a DC variable power supply DCO is applied to the inverting input (-) of the differential amplifier OPA via a resistor RS1, and a resistor RS2 is connected between the inverting input (-) and the output of the differential amplifier OPA. The voltage +Eni from the variable power supply DCO generates the neutral potential (offset voltage) −Ene shown in FIG. 15. A resistor RS4 is connected between the non-inverting input (+) of the differential amplifier OPA and earth potential (0 V), and a sinusoidal AC voltage Evi with a frequency fp output from the oscillator circuit 90A shown in FIG. 7 is applied to the non-inverting input (+) of the differential amplifier OPA via a series connection of a coupling capacitor CC1 and a resistor RS3. The capacitance of the capacitor CC1 is determined according to the series resistance value of the resistors RS3 and RS4 so that the low cutoff frequency of the frequency fp of the AC voltage Evi is about 1 Hz.

[0084] In the circuit configuration of Figure 16, if resistors RS1 and RS3 have the same resistance value and resistors RS2 and RS4 have the same resistance value, the output voltage Vout at the output of the differential amplifier OPA relative to the ground potential (connected to wire Wa) is Vout = (RS2 / RS1) · (Evi - Eni). The AC voltage Evi has a waveform whose amplitude changes sinusoidally over time, so it can be expressed as Evi = Epi · sin(2π · fp · t), where Epi is the peak value and t is the time. If the absolute values ​​of the peak value Epi of the AC voltage Evi and the voltage +Eni from the variable power supply DCO are set so that Epi ≦ Eni, the output voltage Vout will have a waveform like that shown in Figure 15. The output voltage Vout of the differential amplifier OPA is applied to the electrode plates Ed and Em shown in Figure 14 via wire Wb.

[0085] As an example, if resistors RS1 and RS3 are set to 20 kΩ and resistors RS2 and RS4 are set to 100 kΩ, the neutral potential (average potential) −Ene in Fig. 15 is set to −25 V, and the peak value Evp of the amplitude of AC voltage Ev in Fig. 15 is set to 22 V, then voltage +Eni from variable power supply DCO is set to +5 V, and the peak value of the amplitude of AC voltage Evi from oscillator circuit 90A is set to 4.4 V (effective value: approximately 3.08 V). Note that the circuit configuration for generating AC voltage Ev whose amplitude changes at frequency fp with reference to neutral potential (offset potential) Ene other than 0 V (earth potential) as shown in Fig. 15 is not limited to the circuit configuration shown in Fig. 16, and various other circuit configurations can also be used.

[0086] In this embodiment, as shown in Figure 14, a conveyor transport system using rollers 5A, 5B and a belt 5C is used to transport the sheet substrate P horizontally in the mist film forming section, but as shown in Figure 6 above, a roll transport system may also be used in the mist film forming section, in which the sheet substrate P is wrapped around a rotating drum DR and transported.

[0087] As described above, according to the third embodiment, the electrostatic field generating unit that generates an electrostatic field between electrode plate Ed and belt 5C as a mist induction mechanism provided in the mist film forming unit can also be used as an AC electric field generating unit that generates an AC electric field between electrode plates Ef1-Ef4 and electrode plate Em as a deposition uniforming unit (electrophoresis imparting unit) that uniforms the deposition distribution of nanoparticles in the liquid film on the substrate during the drying process immediately after mist film formation, thereby simplifying the device configuration. Furthermore, when the deposition uniforming unit (electrophoresis imparting unit) applies an AC electric field to the liquid film Lq on the sheet substrate P, the neutral potential (Ene) and amplitude range of the AC electric field are offset to one polarity (negative polarity). Therefore, the nanoparticles np polarized in the liquid film Lq are subjected to an electrophoretic force (vibration) and also to an inductive force that attracts them toward the sheet substrate P.

[0088] In an experiment, two needle electrodes were immersed at a predetermined distance in a solution Lq (liquid film Lq) containing a dispersion of ITO nanoparticles crystallized into a non-rectangular parallelepiped shape by the manufacturing method disclosed in WO 2019 / 138707 and WO 2019 / 138708. A DC voltage was applied between the needle electrodes for a certain period of time. A thin film of ITO nanoparticles was formed on the surface of one of the needle electrodes. Figure 17 shows the schematic configuration of the experimental setup. A solution Lq (solvent: pure water) containing a dispersion of non-rectangular parallelepiped ITO nanoparticles at a predetermined concentration was stored to a certain depth in a container CK, such as a petri dish. Two gold-plated needle electrodes SHa and SHb, spaced a distance dX apart in a direction parallel to the liquid surface, were immersed perpendicular to the liquid surface. A voltage of 40 V was applied between the needle electrodes SHa and SHb from a variable DC power supply DCO.

[0089] In this experiment, the voltage of the DC variable power supply DCO was set to 40 V, and the distance dX between the two electrode needles SHa and SHb was varied to visually confirm whether ITO nanoparticles were deposited on one of the electrode needles. Because the surfaces of the electrode needles SHa and SHb were gold-plated, the immersed portion of the electrode needle SHb began to turn gray when ITO nanoparticle deposition began, making it easy to observe visually. As shown in Figure 18, no deposition was observed when the distance dX was 10 mm or greater. However, when the distance dX was 2 mm, 5 mm, or 7 mm, non-rectangular ITO nanoparticles were deposited on one of the electrode needles with the electrode directly immersed in the solution Lq. This suggests that a kinetic force (repulsive or attractive force) was exerted on the ITO nanoparticles in the region (space) where the electric field acts between the electrode needles SHa and SHb.

[0090] [Fourth embodiment] Fig. 19 shows a schematic configuration of a mist film-forming apparatus MDE according to the fourth embodiment, in which the Cartesian coordinate system XYZ has the Z direction as the gravity direction (vertical direction) and the XY plane as the horizontal direction, as in Figs. 1, 4, 6, and 14. The mist film-forming unit in this embodiment is configured to spray a mist gas Msg onto the surface of the sheet substrate P to form a liquid film Lq while moving the sheet substrate P in the longitudinal direction using the conveyor transport system shown in Figs. 1 to 3B or 14. Therefore, in the apparatus configuration shown in Fig. 19, members and mechanisms that perform the same functions as members and mechanisms shown in Figs. 1 to 3B or 6 are designated by the same reference numerals, and their description will be simplified or omitted.

[0091] In this embodiment, in a conveyor transport mechanism including rollers 5A, 5B, and a belt 5C, the belt 5C moves linearly from roller 5A to roller 5B, and the portion of the belt 5C that supports the sheet substrate P in a planar state is inclined at a certain angle from the XY plane with respect to the movement direction of the sheet substrate P. That is, roller 5B, which is located downstream in the transport direction of the sheet substrate P, is positioned so as to be higher in the Z direction than roller 5A. As the surface of the sheet substrate P is inclined in the transport direction in this manner, the mist film formation unit, which is composed of the mist ejection unit 30, mist collection units 32, 32', and chamber unit 40, is also positioned so as to be inclined overall. Furthermore, as in FIG. 1, a support table 5D' that supports the belt 5C and the sheet substrate P in a planar state is provided between rollers 5A and 5B, inclined in the transport direction with respect to the XY plane. The support surface of the support table 5D' is formed with a plurality of pairs of nozzles that spray pressurized gas toward the back surface of the belt 5C and suction holes that suck the sprayed gas near the nozzles, arranged two-dimensionally at regular intervals, and an air bearing layer (gas layer) is formed between the back surface of the belt 5C and the support surface.

[0092] In this embodiment, a supply / exhaust unit 200, a temperature adjustment (cooling) (temperature control section) unit 202, and a temperature sensor 204 are provided to lower the temperature of the air bearing layer formed between the support surface of the support table 5D' and the back surface of the belt 5C below the temperature of the mist gas Msg ejected from the nozzle openings 30A of the mist ejection section 30 (or the ambient temperature). The supply / exhaust unit 200 exhausts gas from the air bearing layer via a tube TPc that communicates with all of the multiple suction holes formed in the support surface of the support table 5D', and supplies pressurized gas via a tube TPa to the temperature adjustment (cooling) unit 202. The temperature adjustment (cooling) unit 202 supplies temperature-adjusted gas for the air bearing layer via a tube TPb that communicates with all of the multiple ejection holes formed in the support surface of the support table 5D'. The temperature sensor 204 outputs measurement information (actual measurement value) 204s corresponding to the temperature of the gas recovered from the air bearing layer and flowing through the tube TPc to the temperature adjustment (cooling) unit 202. The temperature adjustment (cooling) unit 202 servo-controls the temperature of the gas so that the measurement information (actual measurement value) 204s matches the target temperature information (command value) 100a from the control unit (CPU) 100.

[0093] 6, and in this embodiment, the control unit 100 outputs a control signal to a drive circuit section 82' of a drive section 80' that includes a motor and a reducer that rotates and drives the roller 5A so as to transport the belt 5C. Furthermore, in this embodiment, a temperature control unit 212 is provided that drives a temperature adjustment element (e.g., a Peltier element) 210A provided inside the roller 5A and a temperature adjustment element (e.g., a Peltier element) 210B provided inside the roller 5B so as to set them to a predetermined temperature corresponding to target temperature information 100b from the control unit 100. The temperature adjustment elements (temperature control sections) 210A and 210B adjust the temperatures of the outer circumferential surfaces of the rollers 5A and 5B, which come into contact with the belt 5C, to the same temperature as the air bearing layer formed on the support surface of the support table 5D'. By cooperation of such temperature adjustment elements 210A, 210B and temperature adjustment (cooling) unit 202, belt 5C is set to the target temperature commanded by control unit 100, and sheet substrate P closely supported by belt 5C is also set to the target temperature.

[0094] In addition, if the belt 5C is made of a thin metal plate such as stainless steel, heat conduction is fast, so the temperature adjustment element 210B in the roller 5B (downstream of the conveyance of the sheet substrate P) may be omitted and the temperature of the belt 5C may be adjusted only by the temperature adjustment element 210A on the roller 5A side, or the temperature adjustment element 210A and the temperature control unit 212 may also be omitted. Also, although the temperature sensor 204 measures the temperature of the gas passing through the tube TPc, a temperature sensor made of a semiconductor or the like may be embedded in the support surface of the support table 5D' to measure the temperature of the support surface or the temperature of the gas in the air bearing layer, and the measurement signal may be sent to the temperature adjustment (cooling) unit 202 as measurement information (actual measurement value) 204s.

[0095] In this embodiment, in order to efficiently attach the mist in the mist gas Msg ejected from the nozzle opening 30A of the mist ejection unit 30 to the surface of the sheet substrate P, the target temperature information 100a, 100b from the control unit 100 is set so that the temperature of the sheet substrate P is lower than the temperature of the mist gas Msg (or the ambient temperature). Here, when the ambient temperature in which the mist film-forming apparatus MDE of FIG. 19 is installed is Tev°C, the temperature of the mist gas Msg sprayed from the nozzle opening 30A of the mist ejection unit 30 is Tms°C, and the temperature of the sheet substrate P (the object to be film-formed) is Tfs°C, it is desirable to set the relationship Tev≧Tms>Tfs. In this case, the temperature of the sheet substrate P, Tfs, is adjusted by the temperature adjustment (cooling) unit 202 and the temperature control unit 212 so that the temperature Tfs of the sheet substrate P is approximately the freezing temperature of the solvent liquid of the solution Lq that is the source of the mist or a temperature slightly higher than the freezing temperature.

[0096] To confirm the optimal temperature of the sheet substrate P to be cooled, the temperature dependence of the mist deposition rate was investigated using a preliminary experimental apparatus as shown in FIG. 20. The preliminary experimental apparatus in FIG. 20 is equipped with a temperature control unit (substrate temperature control section) 230 capable of placing a sample glass substrate P' and cooling the temperature of the glass substrate P' from room temperature (ambient temperature) to -5°C, and a pipe 17 from a mist generator arranged so that mist gas Msg is sprayed along the surface of the glass substrate P'. As an example, the pipe 17 is the same flexible pipe 17 (PTFE: fluororesin material) as that connected from the mist generating section 14 to the mist ejection section 30 shown in FIG. 1. The pipe 17 is arranged so that the center line 17x (a line passing through the center point of the circular opening of the tip opening 17T) of the mist gas Msg sprayed from a circular tip opening (ejection port) 17T with an inner diameter (diameter) φm of 15 mm is approximately parallel to the surface of the glass substrate P'. The glass substrate P' was cut out into a square of approximately 25 mm on each side from a glass plate (or a semiconductor wafer) with a thickness of 0.5 mm and whose surface had been treated to be lyophilic.

[0097] Here, the center line 17x is set parallel to the X-axis of an XYZ Cartesian coordinate system in which the Z-direction is the direction of gravity. Therefore, the surface of the glass substrate P' is set parallel to the XY plane, a normal line Lz passing through the center point of the surface of the glass substrate P' is set parallel to the Z-axis, and the opening plane of the tip opening 17T of the pipe 17 is set parallel to the YZ plane. The glass substrate P' (rectangular) is mounted on the temperature control unit 230 so that the end face Eg on the pipe 17 side is approximately parallel to the Y-axis and the distance in the X direction from the tip opening 17T of the pipe 17 to the end face Eg is always approximately constant (e.g., 10 mm). Furthermore, the tip opening 17T of the pipe 17 is fixed by a support member (not shown) so that the distance in the Z direction between the surface of the glass substrate P' and the center line 17x is a constant value, for example, in the range of 0.5 to 1.5 times the inner diameter φm.

[0098] The temperature control unit (substrate temperature control section) 230 includes a temperature control plate section 230A on which the glass substrate P' is placed, a supply port section 230B into which a temperature control liquid (coolant liquid) LLC flows to control the temperature of the temperature control plate section 230A, a discharge port section 230C through which the temperature control liquid LLC is discharged, and a temperature sensor 230S. The temperature control liquid LLC is delivered to the supply port section 230B via a tube from a separate chiller device (a cooling water / hot water circulator) and returned to the chiller device via a tube from the discharge port section 230C. The temperature sensor 230S sends a detection signal Sgt corresponding to the temperature of the temperature control liquid LLC to the chiller device, and the chiller device uses the detection signal Sgt as a feedback signal to control the temperature of the temperature control liquid LLC to a specified target temperature. The temperature sensor 230S that measures the temperature of the temperature control liquid LLC may be provided on the chiller device side.

[0099] In an experiment using the experimental setup shown in Figure 20, the target temperature of the chiller was set to change the temperature of the glass substrate P' to room temperature (ambient temperature) of +27°C and to temperatures ranging from +25°C to -5°C in 5°C increments. In addition to the temperature change of the glass substrate P', experiments were also conducted in which the mist gas Msg was changed to +10°C, +30°C, and +50°C to confirm the effect of the temperature change of the mist gas Msg sprayed from the pipe 17. For the experiment using the experimental setup shown in Figure 20, non-rectangular ITO nanoparticles (average particle size 30 nm) manufactured by the method disclosed in International Publication Nos. 2019 / 138707 and 2019 / 138708 were dispersed at a concentration of 10 wt.% in the solution (presumably pure water) Lq stored in the inner container 14A of the mist generating unit (atomizer) 14 shown in Figure 1.

[0100] The time for spraying the mist gas Msg (film formation time) was set to a constant 5 minutes (300 seconds) for each sample glass substrate P', and the flow rate of the mist gas Msg ejected from the tip opening 17T of the pipe 17 was set to a constant value (10 L / min) for each glass substrate P' using the flow control valve 15 of the carrier gas CGS shown in FIG. 1. Furthermore, the temperature of the mist gas Msg can be easily changed by adjusting the temperature of the carrier gas CGS introduced into the mist generator 14 shown in FIG. 1. However, to perform a more rigorous experiment, before placing the glass substrate P' in a predetermined position on the temperature control plate unit 230A, the temperature of the mist gas Msg ejected near the tip opening 17T was directly measured by holding a rod-shaped thermometer using an alcohol column or mercury column over it, and the temperature of the carrier gas CGS was controlled to be the predetermined temperature (+10°C, +30°C, +50°C).

[0101] In the experiment, first, the temperature of the mist gas Msg was set to +10°C, and the temperature of the temperature control plate unit 230A (and the glass substrate P' placed on it) was set to room temperature, +27°C. With the mist gas Msg sprayed from the tip opening 17T of the pipe 17 for 5 minutes (mist film formation), the glass substrate P' was then removed from the temperature control plate unit 230A and dried. To measure the thickness of the thin film of non-rectangular ITO nanoparticles formed on the dried glass substrate P', the thickness of the step between the surface of the glass substrate P' that was revealed by locally scraping off the thin film in the center of the glass substrate P' and the upper surface of the thin film (i.e., the film thickness) was measured using a stylus film thickness measuring device (e.g., a Surface Profiler P16 manufactured by KLA-Tencor).

[0102] Similarly, the temperature of the temperature control plate unit 230A (and the glass substrate P' placed on it) was changed to +25°C, +20°C, +15°C, +10°C, +5°C, 0°C, and -5°C, and a mist film was formed on the surface of the glass substrate P' using mist gas Msg at +10°C, and the thickness of the thin film made of ITO nanoparticles after drying was measured. As a result, when the temperature of the mist gas Msg was set to +10°C, the relationship between the thickness of the thin film made of ITO nanoparticles formed and the temperature of the substrate was as shown in characteristic A of the graph in Figure 21. Figure 21 is a graph showing the dependence of the thickness of the thin film formed on the substrate temperature, with the horizontal axis representing the substrate temperature (°C) and the vertical axis representing the thickness of the thin film (ITO nanoparticles) (nm).

[0103] When the temperature of the mist gas Msg was +10°C, as shown in characteristic A, the thickness of the deposited thin film remained constant at approximately 350 nm when the substrate temperature was between room temperature (+27°C) and +10°C. However, when the substrate temperature was below +10°C (below the temperature of the mist gas Msg), at +5°C, 0°C, or -5°C, the thickness of the deposited thin film increased by approximately 1.43 times to approximately 500 nm. This means that the mist contained in the mist gas Msg during mist deposition was more attracted to the glass substrate P', which had a lower temperature than the mist itself, i.e., the adhesion rate of the mist to the substrate surface was improved. Therefore, by lowering the temperature of the sheet substrate P as the substrate to be coated below the temperature of the mist gas Msg, the adhesion rate of the mist can be improved, enabling the liquid film layer formed on the surface of the substrate to be coated by the aggregation of countless mist particles (with particle sizes of several μm) to grow more quickly.

[0104] When the substrate temperature is set to -5°C, the mist (pure water) adhering to the surface of the glass substrate P' immediately freezes, and a thin layer of frost (ice layer) forms on the surface of the glass substrate P' after the mist spray time (5 minutes) has elapsed. Even in this case, the ice layer changes into a liquid film as time passes after the mist is sprayed, and eventually the liquid film also evaporates (or vaporizes), so the thickness of the thin film formed by the deposition of ITO nanoparticles can be measured in a similar manner.

[0105] Next, the temperature of the carrier gas CGS was adjusted to raise the temperature of the mist gas Msg to +30°C, and the same experiment as at +10°C was performed. As a result, the relationship between the substrate temperature and the film thickness of the ITO nanoparticle thin film was as shown by characteristic B in the graph in Figure 21. When the temperature of the glass substrate P' was room temperature, +27°C (or +25°C), and the mist gas Msg temperature was +30°C, the film thickness was approximately 200 nm, which was a lower film formation amount (film formation rate) than the film thickness (approximately 350 nm) when the mist gas Msg temperature was +10°C. Furthermore, the temperature of the glass substrate P' was set to +20°C, +15°C, +10°C, +5°C, and 0°C, and the thickness of the thin film of ITO nanoparticles formed was measured.In the range where the substrate temperature was below +10°C, as shown in characteristic B, the change in film thickness relative to the substrate temperature showed the same trend as in the case of mist gas Msg at a temperature of +10°C, and a film thickness of approximately 500 nm was obtained at substrate temperatures below +5°C.

[0106] Furthermore, we adjusted the temperature of the carrier gas CGS to raise the mist gas Msg temperature to +50°C and performed the same experiment as at +10°C and +30°C. The relationship between substrate temperature and ITO nanoparticle thin film thickness was as shown by characteristic C in the graph in Figure 21. When the temperature of the glass substrate P' was room temperature (+27°C or +25°C) and the mist gas Msg temperature was +50°C, the film thickness was approximately 160 nm. This was less than half the film thickness (approximately 350 nm) when the mist gas Msg temperature was +10°C. We then measured the film thickness of the ITO nanoparticle thin film by setting the temperature of the glass substrate P' to +20°C, +15°C, +10°C, +5°C, and 0°C. When the substrate temperature was +10°C, the film thickness was approximately 300 nm, approximately double the film thickness of 160 nm when the substrate temperature was room temperature (+27°C) or +25°C. Furthermore, when the substrate temperature was +5°C, the film thickness was approximately 480 nm, which was approximately three times the film thickness of 160 nm when the substrate temperature was room temperature (+27°C) or +25°C.

[0107] As a result of the above preliminary experiments, it was found that by lowering the substrate temperature with respect to the temperature of the mist gas Msg, the adhesion rate of the mist (growth rate of the liquid film) is improved, and the film formation rate of the thin film by the nanoparticles is improved. Further, when the solution that forms the mist is pure water, it was also found that when the substrate temperature is set in the range of +10°C to 0°C, more preferably in the range of +5°C to 0°C, the adhesion rate of the mist can be maximized regardless of the temperature of the mist gas Msg.

[0108] Also, in the experimental apparatus of FIG. 20, the mist gas Msg is ejected in a room temperature +27°C free space so as to follow the surface of the glass substrate P' horizontally from the tip opening 17T of the pipe 17. In that case, when the temperature of the mist gas Msg is higher than the room temperature +27°C, the mist gas Msg ejected from the tip opening 17T of the pipe 17 has an upward force (buoyant force) directed upward (+Z direction). In the case of the glass substrate P' set to the same temperature as the ambient temperature, the amount of mist adhering to (descending onto) its surface is reduced. However, if the temperature of the glass substrate P' is made sufficiently lower than the temperature of the mist gas Msg, the temperature of a part of the mist gas Msg crossing the surface of the glass substrate P' is lower than the ambient temperature (room temperature), and a part of the mist gas Msg will have a downward force (sedimentation force), and it is considered that the mist adhesion force is improved.

[0109] Here, in the mist film forming apparatus MDE shown in FIG. 19, if the temperature of the mist gas Msg ejected from the nozzle opening 30A of the mist ejection unit 30 toward the substrate P in the chamber unit 40 is Tms (°C), the temperature of the surface of the substrate P adjusted through the support table 5D' and the belt 5C temperature-controlled by the temperature control (cooling) unit 202 is Tpp (°C), and the temperature in the chamber unit 40 (temperature of the internal space of the chamber unit 40, or temperature of the inner wall surface defining the internal space) is Tct (°C), it is preferable to set the temperature Tpp to be not less than the freezing temperature of the solution that forms the mist and to satisfy the relationship Tpp < Tms ≤ Tct. Note that if the mist gas Msg is continuously sprayed into the chamber unit 40 for a long time, the temperature Tct in the chamber unit 40 (inner wall surface) will adapt to the temperature Tms of the mist gas Msg and become the same.

[0110] 19, the temperature (Tpp) of the sheet substrate P, which is adjusted by the temperature adjustment (cooling) unit 202 and the temperature control unit 212, is set to, for example, 0°C to +5°C, and the temperature (Tms) of the mist gas Msg ejected from the nozzle opening 30A of the mist ejection unit 30 is set to, for example, +5°C to +10°C, which is lower than room temperature (ambient temperature) and close to the temperature of the sheet substrate P. Note that the temperature (Tms) of the mist gas Msg may be set to the same as the set temperature (Tpp) of the substrate P as long as the mist does not freeze. In this way, by lowering the temperature (Tpp) of the sheet substrate P within a range where the mist does not freeze, the adhesion rate of the mist improves and the liquid film formed on the surface of the substrate P grows more quickly, resulting in an improved thin film formation rate due to the nanoparticles contained in the mist. An improvement in the film formation rate leads to effects such as an improvement in the transport speed of the sheet substrate P and a reduction in the flow rate (flow velocity) of the mist gas Msg from the mist ejection section 30 (reducing the consumption of solution Lq in the mist generation section 14), thereby enabling more efficient use of the nanoparticles of the material substance being formed into the film.

[0111] Fifth Embodiment The configuration for cooling the sheet substrate P as shown in FIG. 19 can also be applied to a mist film-forming apparatus, such as those shown in FIGS. 4 to 6, in which the sheet substrate P is supported by a rotating drum DR and transported in the longitudinal direction. FIG. 22 shows the configuration of a mist film-forming apparatus MDE according to a fifth embodiment using a rotating drum DR. The basic configuration and basic components are the same as those shown in FIGS. 4 to 6, and components with the same functions as those components are assigned the same reference numerals. The Cartesian coordinate system XYZ is also set the same as that shown in FIG. 4. In this embodiment, in order to cool the outer peripheral surface DRa of the rotating drum DR that supports the sheet substrate P, multiple (12 in FIG. 22) pipe-shaped cooling pipes (heat exchange pipes) HF are provided inside the rotating drum DR, through which a temperature-controlled fluid (temperature-controlled gas or liquid) supplied via a tube TPb from a temperature adjustment unit (chiller) 202 passes. In the case of Figure 22, each of the multiple cooling pipes HF is extended parallel to the center line AXo at a position at a certain radius from the center line AXo of rotation of the rotating drum DR, and is arranged at a certain angular interval (30 degrees in this modified example) in the circumferential direction of the outer peripheral surface DRa of the rotating drum DR.

[0112] The temperature control fluid supplied via the tube TPb is supplied to circulate through each of the twelve cooling pipes HF via a port JS provided in the shaft Sft of the rotating drum DR and a flow path Fv provided within the rotating drum DR. The temperature control fluid circulated through the cooling pipes HF is returned to the temperature adjustment unit 202 via the internal flow path Fv, port JS, and tube TPc, where it is again controlled to a predetermined temperature and sent to the tube TPb. In addition, in this embodiment, in order to preliminarily control the temperature (cool) of the sheet substrate P before it enters the rotating drum DR, a configuration is provided in which the outer peripheral surface of the roller 5G' arranged upstream of the rotating drum DR is set to a temperature lower than the ambient temperature by the temperature control fluid from the temperature adjustment unit 202.

[0113] 4, the sheet substrate P contacts (is in intimate contact with) the outer peripheral surface DRa of the rotating drum DR in the circumferential direction within the range from the entry position Ct1 to the release position Ct2, and the chamber 40 constituting the mist film-forming unit is arranged so as to curve cylindrically in the circumferential direction within the angular range from the entry position Ct1 to the release position Ct2 and cover the sheet substrate P. The chamber 40 is provided with the mist jetting unit 30 and the mist collecting units 32, 32' in the same arrangement as in FIG. 6, but in this embodiment, the mist jetting unit 30 is tilted so that the line CL representing the jetting direction of the mist gas Msg jetted from the nozzle opening 30A of the mist jetting unit 30 is not parallel to the normal to the tangent plane at the position on the surface of the sheet substrate P facing the nozzle opening 30A (the position where the line CLj extending radially from the center line AXo in FIG. 22 passes through).

[0114] In this embodiment, the mist spraying part 30 is tilted so that the nozzle opening 30A side of the mist spraying part 30 is located in the +Z direction relative to the pipe 17 side, i.e., when viewed in the XZ plane, the +X side of the line CL is higher than the −X side. With this configuration, even if some of the mist in the mist gas Msg gathers and forms droplets and adheres to the inner wall surface of the mist spraying part 30, the possibility that the droplets will grow large, travel along the inner wall surface, and fall from the nozzle opening 30A onto the sheet substrate P is greatly reduced. Furthermore, as shown in FIG. 22 , since droplets that adhere to the inner wall surface of the mist spraying part 30 flow down in the −Z direction, which is the direction of gravity, a droplet trap (collection part) 30u can be provided at the lowest part of the inner wall surface.

[0115] Furthermore, if the inner wall surface of the air guide member 40A of the chamber 40 is made suitably lyophilic, the mist will form a liquid film that covers the inner wall surface of the air guide member 40A before it locally collects and turns into droplets (particles), and this liquid film will eventually flow downward (in the -Z direction) along the inner wall surface. Therefore, in this embodiment, a collection section 40u for the liquid film that flows down along the inner wall surface of the air guide member 40A is provided near the end that is located at the lowest point of the chamber 40 in the direction of gravity.

[0116] 22, when the outer peripheral surface DRa of the rotating drum DR is cooled below room temperature (ambient temperature), the sheet substrate P first comes into contact with (closely adheres to) the low-temperature outer peripheral surface DRa at the entry position Ct1, and is cooled while moving from the entry position Ct1 to the separation position Ct2. In the present embodiment, mist film formation (adhesion of the mist to the substrate surface) occurs mainly between the position of the nozzle opening 30A of the mist jetting unit 30 (the position of the line CLj) and the position of the mist collecting unit 32 downstream (near the separation position Ct2). Therefore, it is necessary to maintain the sheet substrate P at the target temperature while the sheet substrate P is moving from the position of the line CLj to the separation position Ct2.

[0117] For example, if the temperature of the sheet substrate P upstream of the entry position Ct1 is room temperature (e.g., +20°C to +25°C) and the temperature of the outer peripheral surface DRa of the rotating drum DR is set between 0°C and +5°C, and the thermal conductivity of the substrate P is low, it may happen that the temperature of the surface of the substrate P does not sufficiently drop to the temperature of the outer peripheral surface DRa of the rotating drum DR within the time it takes for the sheet substrate P to move from the entry position Ct1 to the position of line CLj (the position directly below the nozzle opening 30A). Therefore, in this embodiment, the surface of the roller 5G' arranged upstream of the rotating drum DR is cooled to, for example, +10°C or below (or may be close to 0°C) by a temperature control fluid (coolant) from the temperature control unit 202. The sheet substrate P is pre-cooled while it is in contact (close contact) with the roller 5G', and this time Tph (seconds) is determined by Tph = (π·φd·Δθr) / (360·Vp), where φd (mm) is the diameter of the outer surface of the roller 5G', Δθr (degrees) is the embrace angle (angle range of contact) of the sheet substrate P with the roller 5G', and Vp (mm / second) is the conveying speed of the sheet substrate P.

[0118] When the sheet substrate P, which has been pre-cooled by the roller 5G', reaches the entry position Ct1 of the outer peripheral surface DRa of the rotating drum DR, it is cooled to a temperature close to the temperature of the outer peripheral surface DRa of the rotating drum DR (0°C to +5°C), and then, as it moves from the entry position Ct1 to the position of line CLj (the position directly below the nozzle opening 30A), it becomes accustomed to the target temperature of the outer peripheral surface DRa, and mist film formation (mist spraying) is performed.

[0119] In the above-described embodiment, the direction (line CL) of mist gas Msg ejected from the nozzle opening 30A of the mist ejection unit 30 is tilted downstream in the transport direction of the sheet substrate P, so that the flow rate of mist gas Msg flowing in the space within the chamber 40 (the space between the air guide member 40A and the substrate P) from the nozzle opening 30A to the downstream mist collection unit 32 can be made greater than the flow rate of mist gas Msg flowing in the space from the nozzle opening 30A to the upstream mist collection unit 32'. This configuration in which the direction of ejection of mist gas Msg from the nozzle opening 30A of the mist ejection unit 30 is tilted from a direction perpendicular to the sheet substrate P can also be applied to the mist film formation devices shown in each of FIGS. 1 to 3B, 4, 6, 14, and 19.

[0120] 19 and 22, when the temperature of the mist gas Msg ejected from the nozzle opening 30A of the mist ejection unit 30 is set to a first temperature in the range of 0°C to 15°C, the temperature of the sheet substrate P, which is lowered by the substrate temperature adjustment mechanism consisting of the temperature adjustment (cooling) unit 202 in Fig. 19 or the temperature adjustment unit (chiller) 202 in Fig. 22, is set to a second temperature in the range of 0°C to 15°C, which is lower than the first temperature. However, if the solvent of the solution Lq that is the source of the mist is pure water, setting the temperature of the sheet substrate P to 0°C may cause the adhering mist to freeze like frost, so the temperature of the sheet substrate P is actually set to a temperature higher than 0°C (for example, +4°C or higher).

[0121] [Variation 6] 23 is a perspective view showing a schematic configuration of a mist film formation apparatus MDE according to a modification of the mist film formation apparatus shown in FIG. 19 (fourth embodiment). In FIG. 23, the Z axis of the Cartesian coordinate system XYZ is the direction of gravity, and the XY plane perpendicular to the Z axis is set parallel to the surface of the sheet substrate P on which the mist film is formed. However, as in the embodiment of FIG. 19, in this modification, the sheet substrate P may be tilted in the longitudinal direction (X direction) with respect to the XY plane. Note that in FIG. 23, the same rollers 5A, 5B, belt 5C, and support table 5D' as those described in FIG. 19 are provided below the sheet substrate P (in the -Z direction), and the sheet substrate P is cooled.

[0122] In Figure 23, a chamber section 40 is installed upstream in the transport direction (+X direction) of the sheet substrate P, which is transported in a flat state, so as to cover the surface of the sheet substrate P, and the chamber section 40 is provided with a mist ejection section 30 to which mist gas Msg is supplied via two pipes 17a, 17b, and mist collection sections 32, 32' which collect excess mist gas Msg ejected inside the chamber section 40 and discharge it to the outside via pipes 33, 33'. Furthermore, between the slit-shaped nozzle opening 30A (not shown in Figure 23) that sprays the mist gas Msg from the mist ejection section 30 and the surface of the sheet substrate P, as disclosed, for example, in International Publication No. 2016 / 133131, two electrode rods Ema and Emb are fixed to the chamber section 40 so that they extend in the Y direction and are parallel to each other at a fixed interval in the X direction to irradiate the mist gas Msg sprayed from the mist ejection section 30 onto the sheet substrate P with plasma in a non-thermal equilibrium state.

[0123] 21, the temperature of the sheet substrate P passing under the chamber section 40 is lowered to 0°C or below, for example, -5°C, and the temperature of the mist gas Msg sprayed from the mist ejection section 30 is set to a temperature at which the mist (pure water) does not freeze, for example, about +5°C to +10°C. As a result, the mist that adheres to the surface of the sheet substrate P passing under the chamber section 40 freezes and forms a cloudy, frost-like film. An observation section OVS for observing the surface condition of the sheet substrate P is provided downstream of the chamber section 40 in the transport direction (+X direction) of the sheet substrate P.

[0124] The observation unit OVS is provided with two imaging units CV1 and CV2 that are arranged at a certain height above (in the +Z direction) the surface of the sheet substrate P and spaced a predetermined distance apart in the Y direction, and an illumination unit ILU that illuminates an imaging area on the sheet substrate P. The imaging range of the imaging unit CV1 is set to cover an area Aim that spans half of the width of the sheet substrate P in the -Y direction, and the imaging range of the imaging unit CV2 is set to cover half of the width of the sheet substrate P in the +Y direction. Image information sequentially captured by the imaging units CV1 and CV2 is sent to an image analysis unit (not shown), which analyzes the state of the cloudy frost formed on the surface of the sheet substrate P (such as the density distribution of the cloudiness) and identifies areas with particularly light cloudiness.

[0125] An auxiliary mist spraying unit SMD is provided downstream of the observation unit OVS in the transport direction of the sheet substrate P. The auxiliary mist spraying unit SMD is provided above the sheet substrate P and includes a guide member 300 whose length in the Y direction is longer than the width of the sheet substrate P, a slider unit 302 that is guided by a linear guide surface 300a formed on the side of the guide member 300 in the X direction and is movable in the Y direction, and auxiliary mist ejection unit 304 and auxiliary mist collection units 305A and 305B that are fixed to the slider unit 302 and spray mist gas Msg toward the surface of the sheet substrate P. In addition, a slot-shaped opening 300b extending in the Y direction is formed in the center of the guide member 300 in the X direction, and the opening 300b is sized to allow a pipe mp1 that supplies mist gas Msg to the auxiliary mist ejection section 304 and a pipe mp2 that discharges mist gas Msg' collected in the auxiliary mist collection sections 305A and 305B to pass through while the slider section 302 moves in the Y direction.

[0126] An elongated nozzle opening for spraying mist gas Msg is formed on the bottom surface of auxiliary mist jetting unit 304 facing sheet substrate P. The nozzle opening has a length in the X direction shorter than the dimension of area Aim in the X direction and a width in the Y direction of several millimeters or less. The nozzle opening is formed on the bottom surface of each of auxiliary mist collecting units 305A and 305B, which are arranged side by side in the Y direction with auxiliary mist jetting unit 304 in between. A slit-shaped opening for sucking mist gas Msg' is formed parallel to the slit-shaped nozzle opening formed on the bottom surface of auxiliary mist jetting unit 304. Slider unit 302 is driven by a drive source such as a linear motor so that the nozzle opening on the bottom surface of auxiliary mist jetting unit 304 can move to any Y direction position within the width of sheet substrate P in the Y direction.

[0127] The auxiliary mist jetting unit 304 locally deposits additional mist film on thin portions of the frosty, opaque film on the sheet substrate P observed by the imaging units CV1 and CV2 of the observation unit OVS. For this purpose, a mechanism is provided that positions the nozzle opening of the auxiliary mist jetting unit 304 so that it faces the area on the sheet substrate P where additional mist film deposition is to be performed, and then sprays mist gas Msg from the nozzle opening toward the sheet substrate P for a short period of time. This mechanism is configured, for example, as shown in Figures 24A and 24B. Figures 24A and 24B show the schematic configuration of a valve mechanism 310 provided in a flow path that supplies mist gas Msg to the auxiliary mist jetting unit 304. The valve mechanism 310 is connected to a pipe mp0 through which mist gas Msg is supplied from the mist generating section 14 shown in Figure 1, a pipe mp1 that delivers the mist gas Msg toward the auxiliary mist ejection section 304, and a pipe mp3 that delivers the mist gas Msg toward the mist gas collecting section 34 shown in Figure 1.

[0128] The valve mechanism 310 has a rotary valve unit 310S with a T-shaped passage formed by three ports a, b, and c inside, which is rotated by a plunger (drive source) 312 back and forth by 90 degrees clockwise or counterclockwise to switch the flow path of the mist gas Msg. FIG. 24A shows a state in which the rotary valve unit 310S is positioned so that the mist gas Msg supplied from pipe mp0 flows from port b to pipe mp1 via the passage between port b and port c (mist gas Msg supply state). FIG. 24B shows a state in which the rotary valve unit 310S is rotated 90 degrees clockwise from the state shown in FIG. 24A, and the rotary valve unit 310S is switched so that the mist gas Msg supplied from pipe mp0 flows from port a to pipe mp3 via the passage between port b and port b (mist gas Msg non-supply state). Since the flow path is switched at high speed by the rotary valve section 310S using the plunger (drive source) 312, the spraying of the mist gas Msg from the auxiliary mist ejection section 304 onto the sheet substrate P can be limited to a short period of time at any timing.

[0129] In this modified example, the thin film thickness on the sheet substrate P is identified based on the film formation state (the cloudy concentration distribution of the frost-like frozen mist) observed by the imaging units CV1 and CV2 of the observation unit OVS. The slider unit 302 is then moved so that the auxiliary mist spraying unit SMD (auxiliary mist jetting unit 304) faces that portion, and the rotary valve unit 310S of the valve mechanism 310 is temporarily switched from the state shown in FIG. 24B to the state shown in FIG. 24A, and additional mist film formation is performed only on the thin film thickness portion. As a result, thickness unevenness is reduced on the surface of the sheet substrate P that has passed under the auxiliary mist spraying unit SMD, and a thin film made of nanoparticles with improved uniformity is formed. After passing through the auxiliary mist spraying unit SMD, the sheet substrate P is returned to room temperature, for example, about 25°C, and the frost-like frozen liquid film on the sheet substrate P changes phase to a liquid state and dries. 23, a configuration for applying an AC electric field to the liquid film on the surface of the sheet substrate P can be provided as shown in FIGS. 7, 13, and 14.

[0130] [Variation 7] FIG. 25 is a partial cross-sectional view showing a modified example of the mist generator 14 shown in FIG. 1. For ease of explanation, the Z axis of the Cartesian coordinate system XYZ is the direction of gravity (vertical direction), and the XY plane is the horizontal plane. FIG. 25 shows the mist generator 14 cut along a plane parallel to the XZ plane. Components in FIG. 25 that have the same functions as components of the mist generator 14 in FIG. 1 are designated by the same reference numerals. FIG. 26 is a top view of the bottom side of the mist generator 14 shown in FIG. 25, cut along a plane parallel to the XY plane at a height Cj in the Z direction. The mist generator 14 shown in FIGS. 25 and 26 is used as a generator of the mist gas Msg used in the previous embodiments, modifications, or preliminary experiments.

[0131] 25, mist generator 14 includes outer container 14D, which has a rectangular cross section in the XY plane and is filled with liquid (water) Wq for propagating ultrasonic vibrations, and has multiple ultrasonic vibrators 14C1, 14C2, etc., installed at its bottom. An inner container (cup) 14A has a circular cross section in the XY plane and is submerged in the liquid Wq to hold a predetermined volume of mist-generating solution Lq. Cover member 14E supports inner container 14A at a predetermined position within the space of outer container 14D and seals the upper opening of outer container 14D. Cover member 14B also seals the upper opening of inner container 14A. Attached to cover member 14B are pipe 16, which serves as an inlet port for introducing carrier gas CGS via flow control valve 15 shown in FIG. 1, pipe 17, which serves as an outlet port for ejecting mist gas Msg, and pipe 18 for refilling solution Lq.

[0132] The height (position in the Z direction) of the liquid surface of the solution Lq in the inner container 14A is set to approximately half the height of the inner container 14A so that an appropriate space is formed above the liquid surface, and is set to approximately the same height as the liquid surface of the liquid Wq filled in the outer container 14D. The inner container 14A is made of translucent polypropylene resin, and the outer container 14D is made of transparent acrylic resin. The tip (inlet port) 16E of the pipe 16 through which the carrier gas CGS is introduced is bent 90 degrees in a direction parallel to the liquid surface so that the carrier gas CGS is not sprayed directly onto the liquid surface of the solution Lq. As a result, the carrier gas CGS sprayed from the tip 16E circulates along the cylindrical inner wall surface of the inner container 14A within the space above the liquid surface of the inner container 14A without being sprayed directly onto the liquid surface of the solution Lq, thereby preventing the generation of mist rising from the liquid surface of the solution Lq.

[0133] Specifically, the ultrasonic transducers 14C1, 14C2, etc., shown in FIG. 25, are composed of ultrasonic transducers 14C1, 14C2, 14C3, and 14C4 fixed to the four corners of the bottom of the outer container 14D, as shown in FIG. 26. Each of the ultrasonic transducers 14C1, 14C2, 14C3, and 14C4 is configured by housing a thin diaphragm Vpu and a drive unit Sdu with a built-in drive circuit in a waterproof metal case. As shown in FIG. 26, each of the diaphragms Vpu is positioned near the periphery of the circular bottom of the inner container 14A when viewed in the XY plane. The four ultrasonic transducers 14C1 to 14C4 are selectively driven (on / off controlled) by a control circuit 400 that supplies drive signals and power to the drive unit Sdu shown in FIG. 26. Driving all four ultrasonic vibrators 14C1-14C4 maximizes the amount of mist generated from the liquid surface of the solution Lq, while reducing the number of ultrasonic vibrators 14C1-14C4 to be driven can adjust (reduce) the amount of mist generated. The control circuit 400 also controls the flow rate adjustment valve 15, which adjusts the flow rate of the carrier gas CGS.

[0134] When the drop-in ultrasonic transducers 14C1-14C4 are driven for a long time (several tens of minutes), the temperature rises to several tens of degrees Celsius, and the temperature of the surrounding liquid Wq also rises to about 40°C. The temperature of the liquid Wq is transmitted to the solution Lq via the inner container 14A, and the temperature of the solution Lq also rises to about 40°C. Accordingly, the temperature in the space above the liquid surface in the inner container 14A also rises, and the temperatures of the carrier gas CGS and the mist gas Msg also rise above room temperature (e.g., 25°C). Therefore, the temperature rise of the mist gas Msg sprayed onto the sheet substrate P from the mist jetting unit 30 shown in each embodiment and modification reduces the rate of mist adhesion to the surface of the sheet substrate P. Therefore, in this modification, a cooler (temperature regulator) 402 is provided to cool the temperature of the liquid Wq in the outer container 14D. The cooler 402 supplies temperature-controlled liquid Wq at a predetermined flow rate into the external container 14D via the supply pipe 14G based on temperature setting information from the control circuit 400 and the temperature measured by the temperature sensor 14S installed in the external container 14D, and also recovers the liquid Wq in the external container 14D through the recovery pipe 14H and circulates it.

[0135] The set temperature of the liquid Wq is set, for example, to about 10°C below room temperature, and the cooler 402 feedback-controls the temperature of the circulating liquid Wq so that the temperature measured by the temperature sensor 14S becomes the set temperature (10°C). As a result, the mist gas Msg supplied from the inner container 14A through the pipe 17 to the mist jetting unit 30 (or the auxiliary mist spraying unit SMD in FIG. 23) is set to a first temperature higher than 0°C and lower than 30°C, for example, a temperature of about 10°C. Note that if the liquid Wq is an antifreeze liquid (a coolant such as ethylene glycol), the cooler 402 has the ability to cool the temperature of the liquid Wq to 0°C or lower, for example, to near -20°C. Furthermore, if the solvent of the solution Lq stored in the inner container 14A is pure water, the temperature of the liquid Wq will not be lowered below 0°C to avoid freezing. However, if a surfactant is added to the pure water as the solvent for the solution Lq to suppress the aggregation of nanoparticles, the freezing temperature of the solution Lq can be lowered below 0°C. Furthermore, it is advisable to set the temperature of the carrier gas CGS introduced into the space inside the inner container 14A from the pipe 16 serving as the inflow port shown in FIG. 25 to be approximately the same as the temperature of the solution Lq.

[0136] As described above, in the mist generator 14 using the drop-in ultrasonic vibrators 14C1-14C4, ultrasonic vibrations are propagated to the solution Lq in the internal container 14A via the liquid Wq. Heat generated by the ultrasonic vibrators 14C1-14C4 increases the temperature of the liquid Wq, as well as the temperature of the solution Lq. As a result, the temperature of the mist generated from the surface of the solution Lq also rises above room temperature. This increases the temperature of the mist gas Msg sprayed onto the sheet substrate P during mist film formation above the ambient temperature (room temperature), reducing the rate at which the mist adheres to the sheet substrate P. However, as in this modification, the decrease in the rate of adhesion is reduced by suppressing the temperature rise of the liquid Wq and lowering the temperature using the cooler (temperature regulator, temperature control unit) 402. Furthermore, this modification, when combined with the configuration for lowering the temperature of the sheet substrate P as shown in Figures 19-22, can improve the rate at which the sprayed mist adheres to the sheet substrate P by setting the relationship between ambient temperature (room temperature) > temperature of the mist gas Msg > temperature of the sheet substrate P.

[0137] According to this modification, in order to form a thin film of fine particles of a material substance on the surface of a processing object as a sheet substrate P by mist film formation, the mist generating device that generates mist from a solution Lq in which fine particles are dispersed comprises an inner container 14A that stores the solution Lq so that a predetermined space is formed above the liquid surface, an outer container 14D that is provided with ultrasonic vibrators 14C1 to 14C4 for atomization at the bottom and is filled with liquid Wq for propagating ultrasonic vibrations and contains the inner container 14A so that it is submerged in the liquid Wq, and a predetermined space is formed within the space of the inner container 14A. The mist generating unit 14 is configured to include a pipe 16 and a tip 16E as an inlet port for introducing a carrier gas CGS at a constant flow rate, a pipe 17 as an outlet port for driving ultrasonic vibrators 14C1-14C4 to cause mist generated from the liquid surface of the solution Lq in the internal container 14A to flow on the carrier gas CGS and be discharged as mist gas Msg to the outside of the internal container 14A, and a cooler (temperature regulator) 402 as a temperature regulator for adjusting the temperature of the solution Lq stored in the internal container 14A to below the ambient temperature. Furthermore, in this modification, the cooler (temperature regulator) 402 as a temperature regulator is configured to adjust the temperature of the solution Lq via the internal container 14A by cooling the temperature of the liquid Wq filled in the external container 14D to below the ambient temperature.

[0138] [Other Modifications] In each of the above embodiments and modifications, if the nanoparticles of the material contained in the mist sprayed onto the sheet substrate P as the mist gas Msg have a polarization property, the film thickness distribution of the nanoparticles on the sheet substrate P can be made uniform by applying an AC electric field to the liquid film formed on the sheet substrate P after the mist film is formed. If the nanoparticles of the material used for film formation do not have a polarization property but have a magnetic property, the adhesion rate of the mist in the mist gas Msg to the sheet substrate P can be improved by embedding a magnetic body (such as a permanent magnet or an electromagnet) in the substrate support surface of the support table 5D, 5D' or the rotating drum DR that supports the sheet substrate P. Furthermore, applying an AC magnetic field to the liquid film formed on the sheet substrate P after the mist film is formed can also make the film thickness distribution of the nanoparticles on the sheet substrate P uniform.

[0139] Furthermore, in the above-described embodiments and modifications, the solution Lq is atomized using the ultrasonic vibrator 14C (14C1 to 14C4) as the mist generator (mist generating device) 14. However, a configuration in which a predetermined amount of granular dry ice is added at predetermined intervals into the internal container 14A that stores the solution Lq may be used to generate mist from the liquid surface of the solution Lq. In this case, the space above the internal container 14A is filled with cooled carbon dioxide gas (CO2) generated by the evaporation of the dry ice. The carbon dioxide gas, together with the carrier gas CGS supplied from the pipe 16 (tip 16E), is converted into mist gas Msg and supplied to the mist ejection unit 30 via the pipe 17. The temperature of the mist gas Msg ejected from the nozzle opening 30A of the mist ejection unit 30 is lower than the ambient temperature (e.g., +20°C to +30°C), thereby improving the adhesion rate of the mist to the sheet substrate P.

[0140] In each of the above embodiments and variants, a configuration has been exemplified in which a nanoparticle deposition film is formed by mist deposition over almost the entire surface of the sheet substrate P. However, as disclosed in International Publication No. 2013 / 176222, after applying a photosensitive silane coupling agent to the surface of the sheet substrate P, highly liquid-repellent and highly liquid-philic areas can be formed in the layer of the photosensitive silane coupling agent using an ultraviolet pattern exposure device, and by actively adhering mist to the highly liquid-philic areas, a nanoparticle deposition film can be formed in a pattern only in partial areas on the sheet substrate P.

[0141] Alternatively, as in screen printing, a mask made of a thin magnetic metal foil (preferably stainless steel foil with a thickness of 100 μm or less) with partial openings formed therein can be attached to the surface of the sheet substrate P, and mist deposition can be performed on top of the mask, forming a nanoparticle laminate film only in the areas of the sheet substrate P that correspond to the openings in the mask. In this case, it is preferable to embed permanent magnets or electromagnets in the support tables 5D, 5D' or rotating drum DR that support the back surface of the sheet substrate P, so that the mask plate is forcibly attached to the surface of the sheet substrate P by magnetic force. In this case, the mask plate is peeled off from the surface of the sheet substrate P after the liquid film formed on the sheet substrate P by mist deposition in the areas corresponding to the openings in the mask plate has dried. As in the previous embodiments, the sheet substrate P (or mask plate) can be cooled during mist deposition, or an AC electric field can be applied to the liquid film until it dries, causing the nanoparticles to vibrate slightly. [Explanation of symbols]

[0142] 5A, 5B... Rollers 5C... Belt 5D, 5D'... Support table 10... Solution tank 14... Mist generating unit 14C, 14C1 to 14C4... Ultrasonic vibrators 16, 17, 18... Pipe 30... Mist outlet 30A...Nozzle opening 31...Mist supply section 32, 32'... mist collection section 40... chamber section (air guide mechanism) 60... mist charging device 70... electrostatic field generating device (electrostatic field generating unit) 90, 92... AC electric field generating unit 100... Control unit (CPU) 202...Temperature control (cooling) unit (temperature control section) 212...Temperature control unit 402...Cooler (temperature controller) AXo: Center line CGS: Carrier gas DR...Rotating drum Ea, Eb...Electrodes Ec, Ed…electrode plate Ef1~Ef4, Em…electrode plate Ef', Em'...electrode wire HF...cooling tube (heat exchange tube) Lq: Solution Msg: Supplied mist gas Msg': Exhausted mist gas np: Nanoparticles (fine particles) OVS: Observation unit P: Sheet substrate SMD: Auxiliary mist spray unit Wq: Liquid

Claims

1. 1. A film forming apparatus that supplies a mist containing fine particles to a substrate and forms a film containing the fine particles on a surface of the substrate, a mist generating unit that atomizes the liquid containing the fine particles to generate the mist; a mist supply unit that supplies the mist to the substrate; a first cooling unit that cools the mist to a first temperature that is lower than an ambient temperature; a second cooling unit for bringing the temperature of the substrate to a second temperature; The second cooling unit sets the second temperature to a temperature lower than the first temperature.

2. 2. The film forming apparatus according to claim 1, the mist supply unit has a support unit that supports the substrate, The second cooling unit adjusts the temperature of the support part to set the substrate to the second temperature.

3. 3. The film forming apparatus according to claim 2, a film forming apparatus having a transport section that transports the substrate while supporting it on the support section;

4. 4. The film forming apparatus according to claim 3, The transport unit supports and transports the substrate in an arc shape using the support unit having a rotating drum.

5. The film forming apparatus according to any one of claims 2 to 4, The liquid is a dispersion liquid in which the fine particles are dispersed in pure water or a liquid containing a surfactant.

6. The film forming apparatus according to any one of claims 1 to 5, The first cooling unit sets the first temperature so that the temperature of the dispersion liquid falls within a range of 0°C to 15°C.

7. 7. The film forming apparatus according to claim 6, The second temperature set by the second cooling unit is lower than the first temperature and is set to a temperature in the range of 0°C to 15°C.

8. The film forming apparatus according to any one of claims 1 to 7, a drying section that dries the mist on the substrate on which the film has been formed by the film forming apparatus.

9. 1. A film forming method comprising: supplying a mist containing fine particles to a substrate and forming a film containing the fine particles on a surface of the substrate, the method comprising: a mist generating step of atomizing the liquid containing the fine particles to generate mist; a mist supplying step of supplying the mist to the substrate, In the mist supplying step, a first cooling unit is used to set the temperature of the mist to a first temperature that is lower than an ambient temperature, and a second cooling unit is used to set the temperature of the substrate to a second temperature; In the mist supplying step, the second temperature is set lower than the first temperature by the second cooling unit.

10. The film forming method according to claim 9, In the mist supplying step, the substrate is supported by a support part, and the temperature of the support part is adjusted by the second cooling unit to set the substrate to the second temperature.

11. The film forming method according to claim 10, In the mist supplying step, the substrate is supported by the support part and transported by a transport part having the support part.

12. The film forming method according to claim 11, In the mist supplying step, the substrate is supported in an arc shape by the support unit having a rotating drum.

13. The film forming method according to any one of claims 9 to 12, The liquid is a dispersion liquid in which the fine particles are dispersed in pure water or a liquid containing a surfactant.

14. The film forming method according to any one of claims 9 to 13, In the mist supplying step, the first temperature is set by the first cooling unit so that the temperature of the dispersion liquid falls within a range of 0°C to 15°C.

15. The film forming method according to claim 14, In the mist supplying step, the second temperature is set by the second cooling unit to a temperature in the range of 0°C to 15°C so as to be lower than the first temperature.

16. a film formation step of forming a conductive film material on the substrate using the film formation method according to any one of claims 9 to 15; and a drying step of drying the substrate on which the film has been formed.

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