JPH0263572A - Method and device for coating of thin film - Google Patents

Abstract

PURPOSE:To execute partial coating of sheet glass, etc., without masking by introducing a coating liquid into a treating tank in the state of bringing the lateral open surface attached with a flow regulating part in the lower part into tight contact with a substrate to be coated, then removing the coating liquid. CONSTITUTION:A holder 2 for the substrate 1 and the flow regulating part 4 having a downwardly converged shape are provided to the treating tank 5 having the construction consisting in opening one side surface to the shape complying with the shape of the substrate 1 and closing the other side surface and the base. Further, a coating liquid supplying tank 8 provided freely liftably by a lifting device 7 and the flow regulating part 4 of the treating tank 5 are connected by a tube 9. The open side surface of the treating tank 5 is brought into tight contact with the substrate 1 in this constitution and the coating liquid is introduced in this state into the tank up to a prescribed level. The soln. is removed at a prescribed rate after the liquid level comes to a standstill. The action corresponding to the dipping and pulling up of a dipping method is executed in this way, by which the partial coating is enabled.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to wet coating using a solution, particularly when coating by a sol-gel method using a metal alkoxide as a starting material, to partially form a thin film on a substrate. The present invention relates to a coating method and apparatus suitable for coating.

[Conventional technology]

Conventionally, wet coating methods in which a solution is applied to a substrate include a dipping method, in which the substrate is immersed in a solution and pulled up at a constant speed; a flow coating method, in which the solution is poured from above the substrate and diffused; Various methods are known, such as a roller coating method in which the substrate is conveyed by two lower rolls and coated with a solution that is in contact with one or both rolls.

[Problem that the invention seeks to solve]

However, when partially coating the substrate,
70- In the coating method and roller coating method, it is practically impossible to mask unnecessary areas with masking tape, etc., so first coat the entire surface and then remove a large amount of unnecessary areas by etching or other methods. Moreover, it has been extremely difficult to obtain a film thickness that is delicately controlled on the order of submicrons.

The dipping method is said to be the most effective way to obtain a film thickness on the order of submicrons, but this method involves immersing a large substrate in the coating solution and pulling it out.
The driving equipment is large and complicated, making it difficult to handle and increasing costs.
Since fluctuations in the liquid level caused by vibrations of the substrate itself cannot be avoided, horizontal stripes are likely to occur, making it difficult to form a thin film with a uniform thickness. In addition, when partially coating the substrate, mask not only the unnecessary parts on the surface to be coated but also the entire back side, or mask the entire back side and the unnecessary parts on the front side after partially coating both the front and back sides of the board. It is necessary to remove the paint film using methods such as etching.
This required a great deal of effort.

In view of these points, the present applicant filed Japanese Patent Application No. 6219523.
No. 9 was filed, but the present invention further improves this and aims to provide a method and apparatus that can coat a homogeneous thin film having a desired thickness, and that is particularly suitable for coating a part of a substrate. purpose.

[Structure of the invention]

The method of the present invention is an IIQ coating method in which a coating solution is brought into contact with a substrate such as plate glass or plastic to form a film. The coating solution is poured into the processing tank to a predetermined level with the opening surface in close contact with the substrate, and the coating solution is then withdrawn at a predetermined speed, and the dimensions of the apparatus for carrying out this method are as follows: It is equipped with a holding device for holding a substrate, a processing tank having a structure in which one side is opened in a shape that matches the substrate, a rectifying section attached below, and a coating liquid supply tank that is movable up and down. , the rectifier is configured to communicate with the bottom of the coating liquid supply tank through a tube, or the rectifier is configured to have a structure in which a holding device for holding the substrate and one side is opened in a shape that matches the substrate; A processing tank is provided below, and a supply tank for supplying the coating solution to the processing tank and a recovery tank for extracting the coating solution from the bottom of the rectifying section are provided above and below the processing tank, respectively. and are connected by tubes via valves.

[For production]

With the substrate stationary, a treatment tank with an area slightly larger than the surface to be coated and an opening on one side shaped to match the substrate is placed in close contact with the surface to be coated of the substrate, and the coating solution is applied in this state. The solution is added to the same or slightly higher level than the top of the surface to be coated to perform an action equivalent to immersing the substrate in the dipping method, and after the liquid level has stopped, the solution is withdrawn at a predetermined speed to remove the substrate in the dipping method. It is possible to perform partial coating by performing an action equivalent to lifting the substrate, and because the level of the coating solution is controlled by keeping the substrate stationary, it is easy to control the film thickness and achieve a uniform thickness. A thin film can be obtained.

The invention proposed in Japanese Patent Application No. 62-19523 achieves these effects and is particularly suitable for partial coating, but as shown in Fig. There was a fear that unevenness would occur.

In the present invention, a rectifier is attached to the processing tank so that the flow of the solution becomes laminar without being disturbed up to the height of the lowest surface of the surface to be coated, and as described later, an opening connecting these parts is provided. To prevent the flow from becoming too small, the flow straightening section should be constructed so that it gradually narrows down from a position lower than the bottom of the processing tank (Fig. 1), or the length of the flow straightening section should be sufficiently long without narrowing down, and the length of the flow straightening section should be made sufficiently long so that By connecting the tube to the bottom of the side, turbulent flow at the corner of the processing tank is removed.
The occurrence of coating film unevenness can be minimized.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 and FIG. 2 are Embodiment 1 and Embodiment 2 of the present invention, respectively.
FIG. 3 is a perspective view showing the processing tank of the present invention, FIG. 4 is a diagram showing the flow when removing a solution from the processing tank of the prior invention, and FIG. It is a front view of a processing tank (receiving tank omitted) showing another embodiment.

1 As shown in FIGS. 1 and 3, this device includes a holding device 2 that holds a substrate 1 such as a plate glass, one side is opened in a shape that matches the substrate 1, and the other side and bottom are closed. A processing tank 5 has a small opening 3 formed by cutting out the upper part of the unopened side surface in a sawtooth shape, and is attached with a rectifying section 4 having a downwardly narrowed structure, and the surface containing the small opening 3 is formed on one side. A receiving tank 6, a coating liquid supply tank 8, a processing tank 5, and a coating liquid supply tank 8, which can be raised and lowered by a lifting device 7.
It consists of a tube 9 that connects the two. The processing tank 5 and the rectifier 4 are communicated through an opening 10. The holding device 2 consists of two arms 13.13 having a suction pad 11 and a stopper 12 and is rotated. The processing tank 5 has an independent hollow double structure on both left and right sides and the bottom so that it can be evacuated by a tube 15. Furthermore, an elastic body 16 is provided at the part in close contact with the substrate, and a rond 18 connected to an air cylinder 17 is provided.
It reciprocates back and forth by expanding and contracting.

Next, the thin film coating procedure will be explained.

A coating liquid supply tank 8 containing an alkoxide solution (sol solution) prepared by adding a solvent such as isopropyl alcohol to titanium alkoxide as a main component as a coating solution 19 is placed in a coating liquid supply tank 8 whose liquid level is lower than the bottom surface of the processing tank 5. (2) The substrate 1 is conveyed by the belt conveyor 20 in a state where it is lowered so that the belt conveyor 20 is stopped when it reaches a predetermined position. ■ Arms 13, 13 hold stationary board 1.
Rotate it to the position shown in Figure 1 while placing it on the screen.

At this time, the substrate 1 is suctioned by the suction pad 11 during rotation, and in combination with the action of the stopper 12, the substrate 1 is safely held at a predetermined position.

(2) The processing tank 5 is moved forward by the operation of the air cylinder 17 and brought into contact with the substrate 1. After contact, the tube 15 is evacuated by a vacuum pump (not shown) to increase the degree of adhesion. (2) Raise the coating liquid supply tank 8 by operating the lifting device 7 until the liquid level is slightly higher than the top of the surface to be coated. At this time, the liquid level in the processing tank 5 rises from the O state to a predetermined level, causing a portion to overflow. (2) After the liquid level in the processing tank 5 has come to rest, the coating liquid supply 8 is lowered at a constant speed by the lifting device 7 to a position where the liquid level is lower than the bottom surface of the processing tank 5. At this time, the liquid level in the treatment tank 5 falls at a constant rate, and the coating solution is drawn out. (2) The vacuum state is released through the tube 15, and then the processing tank 5 is moved backward by reverse operation of the air cylinder 17, and is separated from the substrate 1. ■Drive device 1
4, the arm 13 of the holding device 2 is rotated to a horizontal position, and then the suction of the suction band is released and the substrate 1 is placed on the belt ampere 20. ■Reverse operation of belt conveyor 20 4m to convey substrate 1.

After this, heat treatment is performed using an electric furnace or the like to make the Ti film uniform in thickness.
Obtain an O□ film.

The coating solution overflowing from the processing tank 5 is recovered from the receiving tank 6 via a cleaning means (not shown).

Embodiment 2 As shown in FIGS. 2 and 3, this device has a holding device 2 that holds a substrate 1 such as a plate glass, one side is opened in a shape that matches the substrate 1, and the other side and bottom are closed. , a processing tank 5 with a small opening 3 formed by notching the upper part of the unopened side surface in a sawtooth shape, and a rectifying section 4 having a downwardly narrowed structure; a supply tank 8 which is provided above the processing tank 5 and supplies the same coating solution as in Example 1, and a recovery tank 21 which is provided below the processing tank 5 and which extracts the coating solution. Consists of a tube 23 connected to the bottom of the tank 8 and introduced into the processing tank 5 via a valve 22, and a tube 25 connected to the bottom of the processing tank 5 and introduced into the recovery tank 21 via a valve 24. be done.

Although not shown in FIG. 2, in this case as well, it is preferable to form a double structure around the processing tank 5 so that it can be evacuated.

Next, the thin film coating procedure will be explained.

First, a substrate 1 such as a plate glass is placed on the holding device 2, and with the substrate 1 and the processing tank 5 in close contact with each other, the valve 22 is opened and the coating liquid is poured into the processing tank, until the liquid level partially overflows from a predetermined level. By the way, valve 22 is closed. After the liquid level in the processing tank 5 becomes stationary, the valve 24 is opened and its opening degree is adjusted so that the rate of drop in the liquid level becomes a desired value, and the coating liquid is extracted at a substantially constant rate.

After that, as in Example 1, a heat treatment tank is used to obtain a uniform thickness of T.
An iO2 film was obtained.

Although the present invention has been described above using preferred embodiments, the present invention is not limited to these embodiments, and various applications are possible.

In addition to the TiO□ film, the thin film obtained by the present invention is
Optical materials such as t film, ZrOz film, Ah03, or a mixture of these films? ! There are various thin films for holograms such as J film and dichromate gelatin film, and therefore various coating solutions can be applied.

The substrate can be made of various plastic plates other than plate glass, and even if the shape is not only flat but curved, the opening of the processing tank can be shaped to match the substrate, so it can be applied to substrates of various shapes. can do.

In addition to the pentagonal shape of the rectifying section as in the embodiment, the rectifying section may have a triangular shape that is gradually narrowed, or the length of the rectifying section may be made sufficiently long without narrowing, as shown in Fig. 5. It goes without saying that the tube may be connected to the bottom or the lower side of the processing tank, and may be provided on the bottom of the processing tank instead of being attached to the lower part of the back side of the processing tank as in the embodiment.

Furthermore, it is preferable that the area of the opening that communicates the treatment tank and the rectifier be large in order to avoid disturbing the flow, but once the coating solution has been poured into the treatment tank to a certain level, the rate of descent of the solution when withdrawing it will depend on the film thickness. It is decided,
The area may be appropriately selected so that the flow velocity at the opening is 6 times or less, preferably 4 times or less, with respect to this descending speed, that is, the area is 1 or more, preferably 174 or more times the cross-sectional area of the processing tank.

The notch provided in the treatment tank to form a small opening acts as a weir for overflowing the coating solution to remove floating matter such as dust, and is cut in a sawtooth shape as in the example. It is preferable that the cross-sectional area becomes smaller and the flow rate of the overflow liquid increases, allowing floating matter to be removed over a wide range. However, various shapes such as a linear one can be used.

Further, although the present invention is suitable for partial coating, if the opening area of the container is increased, that is, if the container is made larger, it is also possible to coat the entire surface of one side.

〔Effect of the invention〕

According to the present invention, there is no need to mask partial coating, which has conventionally been difficult in wet coating.
This makes it easy to eliminate or minimize the need to remove unnecessary films, and the film thickness can be easily controlled and a uniform film can be changed, making it suitable for head-up display combiners, reflectors, It can be used for a wide variety of purposes, including decorative boards.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are Embodiment 1 and Embodiment 2 of the present invention, respectively.
FIG. 3 is a perspective view showing a processing tank according to the present invention; FIG. 4 is a diagram showing the flow when coating solution is removed from the processing tank according to the prior invention; FIG. It is a front view of a processing tank (at the time of a receiving tank) showing another embodiment. 1-m-substrate 2--holding device 4-- rectifying section 5-m-processing tank 8-- coating liquid supply tank 9.23.25-m-tube 21--1 recovery tank 22.24- --Valve Figure 2

Claims (3)

[Claims] (1) In a thin film coating method in which a coating solution is brought into contact with a substrate to form a film, a processing tank having a structure with one side open and a rectifier attached below the opening is brought into close contact with the substrate. A method for coating a thin film, the method comprising: charging a coating solution into the processing tank to a predetermined level, and then withdrawing the coating solution at a predetermined speed. (2) A holding device that holds the substrate, a processing tank with an opening on one side in a shape that matches the substrate, a processing tank with a flow straightening section attached below, and a coating liquid supply tank that can be raised and lowered. What is claimed is: 1. A thin film coating apparatus, further comprising: a tube that communicates the flow straightening section with the bottom surface of the coating liquid supply tank. (3) A holding device for holding a substrate, a processing tank having a structure in which one side is opened in a shape that matches the substrate, and a rectifying section attached below, and a coating solution is poured into the processing tank. A thin film coating characterized in that a supply tank for supplying and a recovery tank for extracting the coating solution from the bottom of the rectifying section are provided above and below the processing tank, respectively, and are connected to the processing tank by a tube via a valve. Device.