JP2003305405A - Method of forming film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformalize the thickness of a film formed on a substrate and to shorten the treating time with a simple structure to have no bad effect in a method of forming the film by heating under vacuum. <P>SOLUTION: In the film forming method having a process for applying a solution on the substrate and a process for removing a solvent in the solution, the method of removing the solvent has (1) a process for transporting the substrate into a vacuum vessel, (2) a process for evacuating the vacuum vessel to reduce the pressure, (3) a process for heating the vacuum vessel, (4) a process for cooling the vacuum vessel, (5) a process for returning the inside of the vacuum vessel into atmospheric pressure and (6) a process for carrying out the substrate from the vacuum vessel. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a film by removing a solvent, for example, forming an organic insulating film or a photosensitive resin film on a silicon wafer in a semiconductor process, The present invention relates to a film forming method used when an alignment film is formed on a glass substrate in a liquid crystal panel process.

[0002]

2. Description of the Related Art In order to form a film from a liquid (solution) in which a compound is dissolved in a solvent, a step of applying a liquid on a substrate to form a "coating film" and removing the solvent of the liquid to form a "film" A forming process is required. There are spin coating method, spray coating method, slit coating method, dipping method, etc. as a method for applying a liquid on a substrate to form a coating film, and each of them depends on the film thickness, the physical properties of the coating liquid material, and the application target. An appropriate method is selected depending on the existing substrate form. On the other hand, as a method for removing the solvent of the liquid to form a film, a method by heating such as a hot plate method, a hot air heating method, a far infrared heating method, a vacuum method utilizing a change in vapor pressure, or a solvent removal by a combination thereof is used. A method has been devised.

The present invention relates to the latter of the above steps, that is, a method for removing the solvent of the solution. One of the problems in this process is the occurrence of wind pattern-like non-uniformity of the film thickness due to the influence of the air flow. In particular, when a low-viscosity material or a liquid film becomes thicker, the flow becomes easier, so that the film thickness tends to become nonuniform, and this problem will be highlighted. It is known that heat treatment in a vacuum without air flow is effective as a method for solving such a problem of non-uniform film thickness. However, there is a problem in heat treatment in vacuum. First, when the processed substrate is exposed to the atmosphere without being cooled, a compound material having a low viscosity under heating is affected by an air flow and deteriorates film thickness uniformity. In addition, there is a problem that it takes a long time to cool the substrate even if the substrate is separated from the heating source because of its low thermal conductivity in a vacuum, and as a result, the property of the film changes. As a measure against this, means for forcibly cooling the substrate in a vacuum is known, and for example, Japanese Patent Laid-Open No. 2001-854.
There is a publication No. 40. In this known example, after heat-treating a substrate in a heat treatment space in a vacuum container, the substrate is separated from the space, and a radiant heat from a heater is prevented by a heat blocking shutter,
In addition, the cooling plate installed in the vacuum vessel is brought into contact with the cooling plate via the susceptor. With this means, it is necessary to provide an operating part in the vacuum container, and there is a concern that the device configuration will be complicated and that the problem of dust from the operating part will occur.

[0004]

Therefore, an object of the present invention is to make the film thickness formed on the substrate uniform with respect to the film forming method by heat treatment in vacuum, and to shorten the processing time with a simple structure. That is, it does not adversely affect the properties of the film.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for forming a film by heat treatment in a vacuum, wherein the film thickness formed on a substrate is made uniform, and the processing time is shortened with a simple structure. It does not adversely affect the property of. The means is a film forming method including a step of applying a solution to a substrate and a step of removing the solvent of the solution, wherein the solvent removing method is 1. 1. a step of transferring the substrate into a vacuum container; 2. depressurizing the inside of the vacuum container; 3. heating the vacuum container; 4. cooling the vacuum vessel;
According to the film forming method, the method includes a step of returning the inside of the vacuum container to atmospheric pressure, and a step of carrying out the substrate from the inside of the vacuum container.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a conceptual diagram of a film forming method according to an embodiment of the present invention. In the figure, 11 is a substrate having a coating film formed on its upper surface, 12 is a coated liquid film, 1
3 is an upper lid of the vacuum container, 14 is a lower member of the vacuum container, 15 is packing, 16 is a proxy, 17 is a hot plate, 1
8 is a cool plate.

In the present invention, the solution is applied onto the silicon wafer by, for example, the slit coating method. The coating method may be a spin coating method or a dipping method, and is not particularly limited as long as it applies a liquid diluted with a solvent. Next, the coated substrate is transported and placed at a predetermined position on the proxy in the vacuum container, and the upper lid and the lower member of the vacuum container are closed to reduce the pressure in the vacuum container.

Here, as the constituent material of the vacuum container, the surface to be heated and cooled later (the lower member of the vacuum container in FIG. 1) is preferably a metal or alloy such as aluminum, copper, SUS or brass having high thermal conductivity. When heating and cooling by contacting a hot plate or a cool plate, both sides should be smoothed or processed into a zigzag shape as shown in Fig. 2 to increase the contact area with respect to the volume of the lower member. Is more preferable, and it is more preferable from the viewpoint of increasing the temperature rising rate. Further, the thickness of the metal plate is preferably thin from the viewpoint of the temperature rising / falling rate, and is preferably thick from the viewpoint of thermal deformation and deformation due to pressure difference. The allowable amount of displacement differs depending on the coating material and process settings, etc., and if a proxy is not used, the displacement will have a large effect because the contact between the substrate and the lower member becomes incomplete. If some displacement is allowed using the proxy, for example, the displacement of the lower member is 0.1 mm with the 1 mm proxy.
If SUS is used as the lower member, it is 20
When the diameter is 0 mm, the thickness of the lower member of the vacuum container is preferably about 5 mm. Further, as the size of the vacuum container increases, its deformation increases, so that the hot plate and the lower member of the vacuum container may be mechanically fixed. For example, as shown in FIG. 3, it is conceivable to provide a mechanical lock mechanism with the hot plate at the center of the lower member having the largest displacement. The packing between the upper lid and the lower member of the vacuum container may be one that can withstand the conditions of heating and depressurization, and nitrile rubber, silicone rubber, fluororubber or the like can be used. The upper lid of the vacuum container is preferably made of a material such as glass which has a small temperature change due to heating and cooling and a small thermal conductivity, but the same material as the lower member can be used depending on the heat insulating performance of the packing. The material and height of the proxy are determined according to the rate of temperature rise, the request of the transfer robot, the amount of displacement of the lower member, etc., and are not essential.

After the pressure is reduced, the vacuum container is placed on a hot plate and heated. In this step, the substrate on which the coating film has been formed is subjected to vacuum heat treatment to remove the solvent and form a film. After that, the vacuum container is placed on a cool plate, and the temperature of the substrate is lowered by cooling the lower member of the vacuum container. It is important to increase the heat capacity of the cool plate so that the plate temperature does not rise, and it is preferable to circulate cooling water in some cases.

After that, when the temperature of the substrate falls below a required temperature, the vacuum container is opened to the atmosphere, the member serving as the upper lid of the vacuum container is opened, and the substrate on which the film is formed is carried out.

Example 1 On a silicon wafer having a diameter of 125 mmφ, a solution containing the following composition was applied by a slit coating method so that the coating film thickness would be 100 μm. Composition EHPE-3150 (trade name, manufactured by Daicel Chemical Industries, Ltd.) 100 parts by weight SP-170 (trade name, manufactured by Asahi Denka Co., Ltd.) 1.5 parts by weight Diethylene glycol dimethyl ether 100 parts by weight Thereafter, in a vacuum container And placed on a brass proxy with a thickness of 1 mm. Next, the vacuum vessel was closed and the vacuum pump was operated to reduce the pressure. 1 when the degree of vacuum reaches 133 Pa
A vacuum container was placed on a hot plate heated to 00 ° C. to perform a vacuum heat treatment. The vacuum container was placed on the hot plate, and after 10 minutes, the vacuum container was placed on the cool plate and cooled. The temperature rising rate was 5 minutes for increasing the temperature from room temperature to 80 ° C., and the temperature decreasing rate was about 35 seconds for decreasing the temperature to 60 ° C. Here, the vacuum container is used as a lower member.
A smooth aluminum plate having a diameter of 5 mm and a thickness of 5 mm was used, and an aluminum block of 400 × 400 × 20 mm ³ was used as a cool plate. Subsequently, when the vacuum container was opened to the atmosphere and the substrate was taken out, no wind ripple was generated and the film thickness was uniform.

(Comparative Example 1) A silicon wafer coated with the same coating solution as in the above Example was placed in a vacuum container, placed on a hot plate, and subjected to vacuum heat treatment for 10 minutes in the same manner. Here, the substrate was unloaded and observed while the vacuum vessel was opened to the atmosphere in the heated state. As a result, the film surface was undulated and the film thickness was non-uniform.

(Comparative Example 2) A silicon wafer coated with the same coating solution as in the above Example was placed in a vacuum container, placed on a hot plate, and subjected to vacuum heat treatment for 10 minutes in the same manner. Here, the cooling of the substrate was performed by natural cooling without turning the power of the hot plate to the cool plate. As a result, it took about 60 minutes to cool to 60 ° C.

[0014]

As described above, according to the present invention, by moving the vacuum container having a simple structure on the hot plate and the cool plate, the film thickness nonuniformity problem (wind ripple pattern) which is particularly likely to occur at the time of forming a thick film. Also, it is possible to solve the problem that the processing time becomes long due to cooling in a vacuum.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram 1 related to contact between a hot plate and a lower member of a vacuum container.

FIG. 3 is a diagram relating to contact between the hot plate and the lower member of the vacuum container (2).

[Explanation of symbols]

11 Substrate with coating film formed on the upper surface 12 Applied liquid film 13 Top cover of vacuum container 14 Lower part of vacuum container 15 packing 16 proxies 17 hot plate 18 cool plate

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Claims (5)

[Claims] 1. A method of forming a film, comprising: a step of applying a solution to a substrate; and a step of removing the solvent of the solution. A step of transferring the substrate into a vacuum container,
2. 2. depressurizing the inside of the vacuum container; 3. heating the vacuum container; 4. cooling the vacuum vessel; A film forming method comprising: a step of returning the inside of a vacuum container to atmospheric pressure; and 6) a step of unloading a substrate from the inside of the vacuum container. 2. The film forming method according to claim 1, wherein
The method for heating a vacuum container is carried out by placing the vacuum container on a hot plate. 3. The film forming method according to claim 1, wherein
A film forming method characterized in that the method of cooling the vacuum container is performed by installing the vacuum container on a cool plate. 4. The film forming method according to claim 1, wherein a material having a heating surface thermal conductivity of the vacuum container higher than a non-heating surface thermal conductivity is used. 5. The film forming method according to claim 2,
A method for forming a film, wherein a vacuum container and a hot plate are mechanically fixed.