JP4969787B2 - Film forming apparatus and film forming method - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is suitably used when a transparent conductive film or the like is formed on a substrate by a spray pyrolysis method (SPD: Spray Pyrolysis Deposition), and can spray droplets having a uniform particle size in advance. The present invention relates to a film forming apparatus and a film forming method.

Conventionally, in a solar cell, a liquid crystal display (LCD), a plasma display (PDP), etc., transparent conductive films (TCF: Transparent Conductive Films) are formed on a transparent base material made of, for example, glass as an insulator. Substrates with a transparent conductive film are widely used.
This transparent conductive film is composed mainly of conductive metal oxides such as tin-doped indium oxide (ITO), tin oxide (TO), and fluorine-doped tin oxide (FTO). It has excellent transparency to visible light and excellent electrical conductivity. Among these transparent conductive films, transparent conductive films mainly composed of tin-doped indium oxide (ITO) are widely known, and liquid crystal display devices (LCD) such as personal computers (PCs), televisions, and portable telephones. Has been applied.

As a method for forming a transparent conductive film such as tin-added indium oxide (ITO) on a transparent substrate, there is a spray pyrolysis method (SPD).
This spray pyrolysis method involves spraying a solution that is a raw material of a film on a substrate that has been heated to a film formation temperature in advance using a spraying means such as an atomizer, so that in the initial stage of the reaction, Crystals are formed by the reaction of solvent evaporation and solutes in the droplets attached to the surface. When the reaction proceeds, the droplets adhere to the crystals (polycrystals) formed on the substrate. This is a technology that applies a series of reactions in which the growth of crystals (polycrystals) progresses by the reaction between the evaporation of the solvent and the solute and the lower crystals.
In this spray pyrolysis method, an aqueous solution or alcohol solution of a metal inorganic salt, an organic solution in which an organic metal compound or an organic acid salt is dissolved in an organic solvent, or a solution thereof is mixed as a raw material solution suitable for spraying. A mixed solution or the like is used. Although the temperature of a base material changes with the kind of starting raw material or raw material solution, it is set to the temperature range of 250-700 degreeC. Such a spray pyrolysis method is effective for forming a transparent conductive film at low cost because the film forming apparatus is simple and inexpensive.

  However, in the conventional film forming apparatus 100 including the liquid supply member 120 and the gas supply member 121 as shown in FIG. 3, the liquid supplied from the liquid supply member 120 and the gas supply member 121 in the fine particle generation unit a. The size of the droplets 122 sprayed from the spraying means c when the supplied raw material solution is made into fine particles by colliding with the supplied gas and sprayed onto the substrate 110 by the spraying means c. Depends on the spray nozzle of the spray means c (hereinafter sometimes referred to as “two-fluid spray nozzle”), and it is difficult to make the size of the droplets 122 uniform, resulting in variations in film thickness. . That is, in the production of the transparent conductive film by the spray pyrolysis method in the transparent conductive film forming means d, when the raw material solution is sprayed by the spray nozzle onto the substrate heated in the temperature range of 250 to 700 ° C., the spray is sprayed from the spray nozzle. Even when a two-fluid spray nozzle capable of miniaturization is used, the size of the droplet 122 to be formed has a distribution of 10 to 120 μm as shown in FIG. In some cases, an in-plane distribution occurs in the sprayed droplets (mist), a film thickness distribution occurs, and a large distribution occurs in film characteristics such as sheet resistance and transmittance.

Therefore, several means have been proposed as means for equalizing the size of the ejected droplets. For example, droplets sprayed from a spray nozzle have many droplets with a large particle size at a position away from the center of the spray path, and coarse droplets included near the center have a high ejection speed and are fine liquids. Focusing on the fact that the droplets are blown far away compared to the droplets, wall surfaces are provided around or in front of the spray path, and large droplets with a particle size away from the center of the spray path, or coarse liquids that are blown away near the center. There is one in which drops are applied to these wall surfaces to be removed (see Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 5-320919 JP 2001-205151 A

However, the above-described means is intended to efficiently sort the sprayed droplets to make the droplet sizes uniform, and does not spray droplets having a uniform particle size in advance. Therefore, there is a limit to uniformizing the size of the droplets, and it is difficult to use only the miniaturized droplets for film formation.
In addition, a sufficient distance between the spray spray and the substrate is necessary, for example, about 500 mm, and it is impossible to actively control the droplet temperature, the droplet spray speed, and the collision force with the substrate. Film formation with precise control of film characteristics was impossible.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a film forming apparatus and a film forming method capable of spraying droplets having a uniform particle diameter in advance.

In order to solve the above-mentioned problems, the present invention provides a film forming apparatus and a film forming method by the following spray pyrolysis method.
That is, the film forming apparatus using the spray pyrolysis method of the present invention includes means A for generating liquid fine particles having a controlled particle diameter , and transport as a space for guiding and transporting the generated liquid fine particles while controlling the temperature. means B that have a road, and means C for spraying induced the liquid fine particles, and means D consisting nebulized the liquid particles from the space for forming a transparent conductive film by coated on the workpiece, And a film made of a resin having water repellency is formed on the surface of the inner wall of the transport path .

In the film forming apparatus using this spray pyrolysis method, means A controls the particle size of the sprayed droplets to generate liquid fine particles having a uniform particle size in advance. Next, in the means B, only liquid fine particles having a uniform particle diameter are conveyed to the means C. After that, in the means C, a film is formed by spraying only fine liquid fine particles having a uniform particle diameter on the substrate (object to be processed) disposed in the space of the means D.
As a result, a film with small variations in film thickness can be formed.

During this, water repellency, the coating film in contact with the inner wall and the liquid fine particles of the transport path for transporting while inducing liquid particles suitable for imparting water repellency such as Teflon (registered trademark) resin and a vinyl chloride resin It is preferable to ensure the condition that the contact angle is 80 ° or more by providing the contact angle.
By adopting such a configuration, it is possible to suppress adhesion of liquid fine particles to the partition plate while reducing the influence of the outside air temperature.

The means B may have a mechanism for controlling the temperature so that the space for guiding the liquid fine particles is isolated from the outside by the partition member and the temperature in the space is kept higher than the outside.
By adopting such a configuration, it is possible to suppress adhesion of liquid fine particles to the inner wall of the conveyance path due to dew condensation or the like, and adhesion between the liquid fine particles, and stably supply liquid fine particles having a uniform particle diameter to the means C. be able to.

Further, the film forming method of the present invention is a method of forming a film on a substrate by spray pyrolysis, which includes a step of generating liquid fine particles having a controlled particle size, and temperature control of the generated liquid fine particles. Then, the process of guiding the inside of the conveyance path in which a film made of a resin having water repellency is formed on the surface of the inner wall while keeping the particle size uniform, the process of spraying the induced liquid fine particles, and the sprayed And a step of depositing liquid fine particles on a substrate to form a film.
As a result, the film can be formed using only the liquid fine particles having a finely aligned particle size, so that a film having a small film thickness distribution can be formed.

According to the film forming apparatus using the spray pyrolysis method of the present invention, the liquid fine particles having a controlled particle diameter are sprayed from the nozzle by introducing them into the nozzle as the spraying means through the space that is guided while controlling the temperature. The in-plane distribution of the liquid fine particles can be made uniform, and the in-plane distribution range of the film characteristics can be reduced (narrowed).
Therefore, the film forming apparatus according to the present invention contributes to a field requiring a large-area transparent conductive film, for example, a field such as a liquid crystal display device or an EL display device.

Further, in the film forming method of the present invention, since the transparent conductive film is formed using liquid fine particles having a uniform particle diameter, uniform and uniform film formation is possible regardless of the area of the base material (object to be processed). It becomes possible.
Therefore, the film forming method according to the present invention contributes to the construction of a mass production system for mass-producing a transparent conductive film having a large area.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is a schematic view showing the structure of a film forming apparatus according to this embodiment.
The film forming apparatus 1 according to this embodiment includes a means (hereinafter referred to as “liquid fine particle producing means”) A for generating first liquid fine particles having a controlled particle diameter, and the produced first liquid fine particles. A means (hereinafter referred to as “liquid fine particle guiding means”) B that guides while controlling the temperature, and a means for spraying the induced first liquid fine particles in place of the refined second liquid fine particles 2. (Hereinafter referred to as “liquid fine particle spraying means”) From the space where C and the sprayed second liquid fine particles 2 are applied to the glass substrate 10 as the object to be processed (base material) to form a transparent conductive film. And means D (hereinafter referred to as “transparent conductive film forming means”) D.

The liquid fine particle generating means A efficiently takes out droplets preliminarily sprayed by a spraying means different from the liquid fine particle spraying means C, which will be described later, by taking out only small (fine) droplets as first liquid fine particles. The control is performed so as to make uniform.
The generated first liquid fine particles desirably contain 60.0 to 98.8 vol% of air.

The liquid fine particle guiding means B prevents the particle diameter of the first liquid fine particles generated by controlling the particle diameter by the liquid fine particle generating means A from the liquid fine particle generating means A to the subsequent liquid fine particle spraying means C. It has a transport path as a space for transporting while guiding.
This conveyance path is isolated from the outside by a partition member, and is controlled so that the temperature of the inner wall is the same as or higher than that of the liquid fine particles, and the temperature at which the evaporation rate of the solvent of the transparent conductive film raw material liquid does not become extreme. Yes. That is, there is a relationship of liquid fine particle temperature> conveying path inner wall temperature> solvent evaporation temperature.
The liquid fine particles in the conveyance path have a flow rate of 100 to 100,000 cm / min.

Further, the inner wall of the conveyance path is isolated from the outside by adopting a water repellent material such as a fluororesin, or by performing a process of imparting water repellency to the surface. At this time, if the transport path is made of a material with good thermal conductivity such as metal, it is easily affected by the outside air temperature, which leads to adhesion of liquid fine particles to the inner wall of the transport path. It is desirable to employ a resin material with low thermal conductivity such as resin. In addition, when employ | adopting a metal material, it can respond by performing temperature control of a conveyance path outer wall.
In addition, when using hydrochloric acid, sulfuric acid, nitric acid, etc. as the chemical solution, it is necessary to use a chemical resistant material on the inner wall that is in direct contact with the liquid fine particles, or to apply a surface treatment with a chemical resistant material. Become.
Furthermore, it is desirable that the distance of the conveyance path is as short as possible. However, in consideration of the picture, it is desirable that the distance is less than 10 m, considering that the distance may be required from the viewpoint of design such as the temperature of the liquid fine particles, the temperature of the inner wall, and restrictions on the arrangement of each means.

  The liquid fine particle spraying means C sprays the liquid fine particles induced by the liquid fine particle guiding means B onto the glass substrate 10 disposed in the space of the subsequent transparent conductive film forming means D. From the outlet of the liquid fine particle spraying means C, the liquid fine particles are sprayed at a flow rate of 1,000 to 100,000 cm / min. Further, the distance between the outlet of the liquid fine particle spraying means C and the surface of the glass substrate 10 is controlled to 5 to 200 mm.

The transparent conductive film forming means D is disposed to face the outlet of the liquid fine particle spraying means C, and has a space for placing the glass substrate 10 on which the liquid fine particles to be a transparent conductive film are deposited. In the transparent conductive film forming means D, the raw material liquid of the transparent conductive film containing the conductive polymer sprayed on the glass substrate 10 is applied to form the initial layer of the transparent conductive film.
The surface of the glass substrate 10 is heated by heat transfer from the lower substrate heater, heat ray irradiation from the upper part of the thermal battle heater, and high-temperature flow from the upper atmosphere, and the temperature is in the range of 200 to 600 ° C. It is controlled.

Next, a method for forming a transparent conductive film according to this embodiment will be described.
First, liquid fine particles having a controlled particle size are generated by the liquid fine particle generating means A. Next, the temperature of the generated liquid fine particles is controlled by the liquid fine particle guiding means B, and the liquid fine particles are guided to the liquid fine particle spraying means C with the same particle diameter. Thereafter, the induced liquid fine particles are sprayed onto the object to be processed by the liquid fine particle spraying means C, and the liquid fine particles 2 sprayed in the transparent conductive film forming means D are deposited on the glass substrate 10 as the object to be processed. Form a film.

Next, examples of the present invention will be described. These examples are made specifically for better understanding of the present invention, and the present invention is not limited to these examples.
First, in this embodiment, a tin-added indium oxide (ITO) film is formed as a transparent conductive film. The solution used as a raw material for the ITO film was indium chloride (III) pentahydrate (InCl ₃ .5H ₂ O, molecular weight: 293.24) 5.58 g, tin (IV) chloride pentahydrate (SnCl ₄ · _5H 2 O, molecular weight: 350.60) and 0.32 g, pure water was adjusted by dissolving in 100ml as a solvent.

  In this example, the liquid fine particles generated by the liquid fine particle generating means A were guided to the liquid fine particle guiding means B under the conditions shown in Table 1 below. Further, the conveying path of the liquid fine particle guiding means B for guiding the liquid fine particles adopted a bellows pipe made of vinyl chloride having elasticity, and the inner surface was subjected to fluororesin processing to ensure water repellency.

  Further, in this example, the liquid fine particles induced by the liquid fine particle guiding means B were sprayed on the glass substrate 10 as the object to be processed by the nozzle of the liquid fine particle spraying means C under the conditions shown in Table 2 below. .

  And by measuring the volume distribution ratio with respect to the particle diameter of the liquid fine particles generated based on the above conditions, the liquid supplied from the liquid supply member and the gas supplied from the gas supply member collide with each other. The raw material solution was microparticulated, and the droplet size distribution was compared with droplets generated by a conventional apparatus in which the microparticulated raw material solution was sprayed onto the substrate by a two-fluid spray nozzle of the spraying means. In addition, the atomizing nozzle in this Example used the micro mist generator by Atmax. The result is shown in FIG.

  From the results shown in FIG. 2, the droplet size distribution is 9 to 160 μm in the conventional apparatus, whereas the droplet size distribution is 1 to 60 μm in the apparatus based on the present invention, and the droplet size distribution is reduced. It can be seen that droplets of 70 μm or more can be removed and droplets having a uniform particle size can be sprayed.

  In this example, a borosilicate glass substrate of 500 mm square and 2 mm thickness was used as the base material, and the film thickness, sheet resistance, and visible resistance of the ITO film formed at a glass substrate surface temperature of 350 ° C. under the above conditions. Each of the light transmittances was measured and compared with the measurement results of a conventional apparatus. The results are shown in Table 3.

  From the results shown in Table 3 above, it can be seen that the apparatus based on the present invention contributed to uniform film thickness distribution and sheet resistance distribution, and improved film quality including transmittance.

  In this example, a 500 mm square and 2 mm thick borosilicate glass substrate was used as the base material, and in order to realize 500 mm square film formation, + -150 mm in the direction with the horizontal direction as the X axis on the substrate side, On the nozzle side, it was driven + -100 mm in a direction with the horizontal direction orthogonal to the X-axis direction on the substrate side as the Y-axis. Therefore, at that time, the substrate-nozzle direction perpendicular to the substrate-side X-axis direction and the nozzle-side Y-axis direction is the Z-axis direction. Then, the substrate was heated under the combination conditions (A) + (B) shown in Table 4 below.

  The film thickness distribution, the sheet resistance distribution, and the visible light transmittance distribution of the ITO film formed under the above conditions were measured, respectively, and compared with the measurement results of the conventional apparatus. The results are shown in Table 5. The film formation time is 15 minutes for both the apparatus of this example and the conventional apparatus.

From the results shown in Table 5 above, it can be seen that the film growth was faster in the same film formation time, the film thickness distribution and the sheet resistance were reduced, and the transmittance characteristics could be greatly improved.
This is because the in-plane distribution of the liquid fine particles ejected from the nozzle is uniform, the nozzle can be sprayed close to the substrate (conventional 500 mm, 20 mm in this embodiment), the flow rate of the liquid fine particles ejected from the nozzle This is considered to be due to the fact that it can be controlled, the temperature of the liquid fine particle temperature until reaching the substrate can be controlled, and the like.

It is the schematic which shows the structure of the film-forming apparatus of this invention. It is a figure which shows the size distribution of the liquid microparticles | fine-particles controlled by the film-forming apparatus of this invention compared with the conventional apparatus. It is the schematic which shows the structure of the conventional film-forming apparatus.

Explanation of symbols

A liquid fine particle production | generation means, B liquid fine particle guidance | induction means, C liquid fine particle spraying means (nozzle), D transparent conductive film formation means, 1 film-forming apparatus, 2 liquid fine particles, 10 to-be-processed object (base material, glass substrate).

Claims (3)

Means A for producing liquid fine particles having a controlled particle size;
The generated said liquid particles induced with temperature control means B that have a conveying path as a space for conveying,
Means C for spraying the induced liquid fine particles;
Means D consisting nebulized the liquid particles from the space for forming a transparent conductive film by coated on the workpiece, the at least comprising,
A film forming apparatus, wherein a film made of water-repellent resin is formed on a surface of an inner wall of the transport path .  The means B has a mechanism for controlling a temperature so that a space for inducing liquid fine particles is isolated from the outside by a partition member and the temperature in the space is kept higher than the outside. Item 2. The film forming apparatus according to Item 1. A method of forming a film on a substrate by spray pyrolysis,
Producing liquid fine particles with controlled particle size;
A step of guiding the inside of the transport path in which a film made of a resin having water repellency is formed on the surface of the inner wall while keeping the particle size uniform by controlling the temperature of the generated liquid fine particles;
Spraying the induced liquid particulates;
Depositing the sprayed liquid fine particles on a substrate to form a film;
A film forming method comprising:

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