JP2000167476A - Formation of colored coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a colored coating film for producing excellent color filters for a display without any visible defective stripes or steps and excellent in surface smoothness at the time of forming a colored coating film on a substrate with a slit coater, then smoothing and drying the film with a spin coater to form a colored coating film. SOLUTION: A colored coating soln. 23 is applied on a substrate 11 by a slit coater to form a coating film, and the coating film is smoothed and dried by a spin coater to form a colored coating film. In this case, a colored coating soln. having 5-20 cps viscosity is applied by a slit coater to 20-50 μm thickness before the solvent is dried to form a coating film, and the coated substrate in a horizontal state is continuously rotated by a spin coater until the film thickness is decreased to 1-2 μm after the solvent is dried to form a colored coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a film such as a photoresist on a substrate,
In particular, the present invention relates to a method for forming a colored film having excellent surface smoothness.

[0002]

2. Description of the Related Art In a display device, it is a useful means to use a color filter for the purpose of color display, reduction of reflectance, improvement of contrast, control of spectral characteristics, and the like. In many cases, the color filters used in this display device are formed and used as pixels. As a method of forming the pixels of the color filter for a display device, a photolithography method, a printing method, and the like are mentioned as methods that have been put to practical use so far.

For example, in a liquid crystal display device,
In recent years, with the progress of liquid crystal display devices, larger ones, from a diagonal size of 5 inches to 8 inches, 10 inches, 12 inches, and 14 inches, have come into practical use. Heretofore, in order to efficiently produce such a color filter for a liquid crystal display device, a method has been adopted in which color filters for a liquid crystal display device of these sizes are mounted on a single glass substrate in multiple planes. For example, a color filter for a liquid crystal display device having a diagonal size of 8 inches is manufactured by attaching four surfaces to a glass substrate having a size of about 300 × 400 mm. The production of color filters for a liquid crystal display device having a diagonal size of 12 inches is performed by attaching four surfaces on a glass substrate of 400 × 500 mm square and six surfaces on a glass substrate of about 550 × 650 mm square. The size of a glass substrate for manufacturing a color filter for a device has been gradually increased along with the size of a diagonal inch of a liquid crystal display device.

[0004] With the enlargement of the glass substrate for producing such a color filter for a liquid crystal display device, a method of using a slit coater and a spin coater together as a method of applying a photoresist in the production of a color filter by photolithography, that is, A method of forming a coating film such as a photoresist, in which a photoresist or the like is applied on a substrate by a slit coater to form a coating film, and the formed coating film is smoothed and dried by a spin coater, has begun. Heretofore, a method of forming a film such as a photoresist using only a spin coater has been adopted, but the aim is to reduce a weak point of the spin coater that appears remarkably with the enlargement of the glass substrate. .

That is, in the method of using both the slit coater and the spin coater, first, a slight excess of photoresist or the like is applied in advance to the entire surface of the substrate by the slit coater, and then the thickness of the photoresist or the like is determined by the spin coater. The coating is formed by smoothing the film surface and drying the coating film. In such a method using a slit coater and a spin coater in combination, compared with a method of forming a film such as a photoresist using only a spin coater, there is no need to transfer or apply a sufficiently excessive amount of photoresist or the like to the center of the substrate, and the formation is performed. The uniformity of the resulting coating is improved, the spin coater used is simplified, and a coating forming method with improved quality and productivity as a whole is obtained. This tendency becomes more remarkable as the size of the glass substrate increases.

[0006] However, even in such a method in which a slit coater and a spin coater are used in combination, there may be a problem in terms of the surface smoothness of the coating film. FIG. 3 is a side cross-sectional view showing an example of the slit coater. The coating head (12) on the glass substrate (11) moves in the direction of the arrow while a photoresist (13) or the like is applied from the coating head (12). It shows the state that is performed. FIG. 4 is a plan view showing a state where a photoresist (13) and the like are applied on a glass substrate (11). FIG. 5 shows the glass substrate (11) coated with the photoresist (13) in FIG.
It is sectional drawing shown by X 'cross section.

[0007] As shown in FIGS. 4 and 5, the coating of the photoresist (13) applied on the glass substrate (11) is substantially uniform over the entire surface, but the moving direction of the coating head (12) (arrow) ) May occur in the form of uneven streaks (14) indicated by halftone dots. This is because the film thickness in this portion is different from the film thickness in the normal region due to, for example, attachment of foreign matter to the ejection portion of the coating head (12), and the surface smoothness is deteriorated. Is what it is.

Further, as shown in FIGS. 4 and 5, a step unevenness (15) indicated by a halftone dot at right angles to the moving direction (arrow) of the coating head (12) may occur. This is because the film thickness in this portion is different from the film thickness in the normal region due to, for example, a change in the moving speed of the coating head (12) in the direction of the arrow, and the surface smoothness deteriorates. Is what it is. The degree of deterioration of the surface smoothness due to the occurrence of the uneven streaks (14) and the step unevenness (15) is smoothed and reduced by the spin coater after the coating film is formed by the slit coater. As a filter, the surface smoothness is not sufficient, and is not preferable because it is viewed as unevenness.

For example, in applications where the photoresist film is peeled off after the lead portion is formed, as in the case of a photoresist film for forming a lead portion of an electrode, this surface smoothness is not a problem. In a colored coating solution such as a colored photoresist used for forming pixels of a color filter for a display device, the colored coating itself after forming the pixels becomes a pixel of the color filter for a display device and is not removed by stripping. In such an application, the surface is viewed as unevenness, so that the surface smoothness is not sufficient.

[0010]

In the present invention, as described above, a colored coating solution such as a colored photoresist is coated on a substrate by a slit coater to form a coating film, and the formed coating film is formed by a spin coater. When forming a colored film on the substrate by smoothing and drying, unevenness caused by uneven streaks and unevenness is not observed, and the surface smoothness of the colored film is excellent.
An object of the present invention is to provide a method for forming a colored film for producing a good color filter for a display device.

[0011]

According to the present invention, there is provided a colored coating film on a substrate, wherein a colored coating solution is applied on a substrate by a slit coater to form a coating film, and the formed coating film is smoothed and dried by a spin coater. In the method of forming, a viscosity of 5 to 20 cp
The colored coating solution of s is coated on a horizontal substrate with a slit coater to a thickness of 20 to 50 μm before solvent drying to form a coating film, and the coated substrate is dried until the film thickness after solvent drying becomes 1 to 2 μm. Is continuously rotated by a spin coater in a horizontal state to smooth and dry the coating film, thereby forming a colored film.

Further, the present invention is the method for forming a colored film according to the above invention, wherein the slit coater and the spin coater are separated from each other.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on one embodiment. FIGS. 1A and 1B are side sectional views showing an example of a coating apparatus using a slit coater and a spin coater in combination, for illustrating a method of forming a colored film according to the present invention, and showing main parts thereof. As shown in FIGS. 1 (a) and 1 (b), the main part of a coating apparatus using both a slit coater and a spin coater is a platen / spinner head (1).
6), a slit coater section including a coating head (12), a platen / spinner head (16), and a rotating shaft (1).
7), and a spin coater section composed of a housing (18) and the like.

In FIGS. 1A and 1B, the coating head (12) of the slit coater is fixed on a surface plate / spinner head (16) while moving in the direction of the arrow from the standby position (A). The coating liquid (23) from the coating head (12) starts to be applied from the left end of the glass substrate (11) onto the horizontal glass substrate (11) placed on the glass substrate (11). The application is continued to the right end of the substrate (11), the application is finished at the right end, and the process reaches the standby position (C). The application position (B) is set on the glass substrate (1).
1) is representatively shown of the application position covering the entire left and right sides.

Subsequently, the glass substrate (21) on which the colored coating solution (23) has been applied is placed on a platen / spinner head (16).
While being fixed on the upper side, it is rotated as shown in FIG. The spin coater is a glass substrate (2
Rotate the rotation axis (17) in the direction of the curved arrow while keeping 1) horizontal, and continue to rotate this film until the film thickness after drying the solvent reaches the target film thickness. The film is smoothed and dried to form a colored film.

The coating head (1) at the standby position (C)
In 2), after the colored coating film on the glass substrate (21) is smoothed and dried by the spin coater and the colored coating is formed, the process returns to the standby position (A) again to perform coating on the next glass substrate. ing.

Specifically, first, the thickness of the colored film is set to a thickness of 1 to 2 μm after drying the solvent, which is applied to the pixels of the color filter for the liquid crystal display device in many cases, as the target thickness. did. Next, about 550 × 6
Using a 50 mm square glass substrate, it was fixed and installed on a surface plate and spinner head (16) as shown in FIG.

The coating head (12) has a slit width (S) of 20 to 50 μm corresponding to a film thickness of 1 to 2 μm after solvent drying.
About the discharge part of the coating head (12) and the glass substrate (1).
The gap (G) with 1) is about 100 to 300 μm, and the moving speed of the coating head (12) is 50 to 100 mm.
/ Sec. Similarly, the viscosity of the colored coating solution is about 5 to 20 cps, and the colored coating solution (23) from the coating head (12) is placed on a horizontal glass substrate (11) in a thickness of 20 to 50 μm before drying the solvent. To form a colored coating film.

Subsequently, as shown in FIG. 1 (b), the glass substrate (21) is kept in a horizontal state until the film thickness after solvent drying reaches a target film thickness of 1 to 2 μm.
6) Continue rotating to smooth and dry the colored coating film,
A colored film was formed. Corresponding to a film thickness of 1 to 2 μm after drying the solvent, the spin-coater was accelerated at a rise time of about 3 to 5 seconds, at a rotation speed of about 500 to 1000 rpm, and at a rotation time of about 10 to 20 seconds.

The colored film thus obtained did not show any unevenness due to uneven streaks or unevenness, and was a colored film having excellent surface smoothness.

FIGS. 2A and 2B show another example of a coating apparatus using both a slit coater and a spin coater, and are side sectional views showing main parts thereof. FIG. 2A shows a main part of the slit coater, and FIG. 2B shows a main part of the spin coater. And each is separated. The slit coater includes a surface plate (19), a coating head (12), and the like. The spin coater includes a spinner head (26), a rotating shaft (17), and a housing (1).
8) and the like.

In FIG. 2 (a), the coating head (12) of the slit coater moves from the standby position (A) in the direction of the arrow, and moves horizontally in the direction of the arrow, and is fixedly installed on the surface plate (19). On the glass substrate (11), the colored coating solution (23) from the coating head (12) starts to be applied from the left end of the glass substrate (11), and passes through the application position (B).
The application is continued to the right end of 1), the application is completed at the right end, and the process reaches the standby position (C). The application position (B) is representatively shown of the application position covering the entire left and right surfaces of the glass substrate (11).

Subsequently, the glass substrate (21) on which the colored coating solution (23) has been applied is transferred from the platen (19) of the slit coater to the spinner head (26) of the spin coater by a transfer device (not shown). Transferred to the spinner head (2
6) Fixed on top. In FIG. 2 (b), the spin coater unit holds the glass substrate (21) in a horizontal state with the rotation axis (1).
7) is rotated in the direction of the curved arrow, and the rotation is continued until the film thickness after drying the solvent reaches a target film thickness, and the colored coating film on the glass substrate (21) is smoothed and dried to obtain a colored coating film. Is formed.

In the coating apparatus in which the slit coater section and the spin coater section are separated from each other, the time required for forming a colored film on a glass substrate is reduced as compared with the coating apparatus in which the slit coater section and the spin coater section are integrated. It will be. This is because it is advantageous to combine the loading and unloading of the glass substrate, the reciprocating operation of the coating head, the rotating operation of the spinner head, and the like when the colored coating is continuously formed.

[0025]

According to the present invention, there is provided a method for applying a colored coating solution on a substrate by a slit coater to form a coating film, and smoothing and drying the formed coating film by a spin coater to form a colored film. Since a low-viscosity colored coating liquid of 5 to 20 cps is applied by a slit coater, it is hard to cause uneven streaks and step unevenness. A coating film having a thickness can be formed. Further, the coated substrate is continuously rotated by a spin coater in a horizontal state until the film thickness after solvent drying becomes 1 to 2 μm, and the coated film is smoothed and dried to form a colored film. The unevenness caused by the cause is not observed, and this is a method of forming a colored film for producing a good color filter for a display device having excellent surface smoothness of the colored film.

Further, the colored film obtained according to the present invention comprises:
No unevenness due to uneven streaks or unevenness is observed, so that the colored film is excellent in surface smoothness of the colored film and efficiently produces a good color filter for a display device.

[Brief description of the drawings]

FIGS. 1A and 1B are side sectional views showing a main part of an example of a coating apparatus using a slit coater and a spin coater in combination.

FIGS. 2A and 2B are side sectional views showing main parts of another example of a coating apparatus using both a slit coater and a spin coater.

FIG. 3 is a side sectional view showing an example of a slit coater.

FIG. 4 is a plan view showing a state where a photoresist or the like is applied on a glass substrate.

FIG. 5 is a cross-sectional view showing the glass substrate coated with a photoresist or the like in FIG. 4 along the line XX ′.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Glass substrate 12 ... Coating head 13 ... Photoresist 14 ... Strigger 15 ... Stage unevenness 16 ... Stage plate and spinner head 17 ... Rotating shaft 18 ... Housing 19 ... Stage plate 21 ... Glass substrate coated with a colored coating solution 23 ... Colored coating liquid 26 ... Spinner head A, C ... Standby position B ... Coating position G ... Gap between the discharge part of the coating head and the glass substrate S ... Slit width

Claims (2)

[Claims] 1. A method for forming a colored film on a substrate, wherein a colored coating solution is applied on a substrate by a slit coater to form a coated film, and the formed coated film is smoothed and dried by a spin coater. A 20 cps colored coating solution is applied by a slit coater on a horizontal substrate to a thickness of 20 to 50 μm before drying the solvent to form a coating film.
A method for forming a colored film, wherein the coated film is smoothed and dried by continuing to rotate the substrate to be coated with a spin coater in a horizontal state until a thickness of about 2 μm is reached, thereby forming a colored film. 2. The method according to claim 1, wherein the slit coater and the spin coater are separated.