JPH0669115A - Spin coating method - Google Patents

Abstract

PURPOSE:To provide a spin coating method effective for production of a rectangular panel such as a liquid crystal panel by which a photoresist and the like can be spin coated uniformly through a simple apparatus. CONSTITUTION:A circular substrate 1b is subjected to spin coating and then cut in rectangular. The substrate 1b is cut along rectangular grooves 9 made previously in the rear surface of the substrate 1b. One or a plurality of grooves 10 are further made in parallel with the cutting groove 9 on the outside thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A rectangular liquid crystal panel using a liquid crystal display element (LCD) is usually used. The present invention relates to a spin coating method effective in manufacturing a rectangular panel such as a liquid crystal panel.

[0002]

2. Description of the Related Art A liquid crystal panel encloses liquid crystal between two glass substrates, has a transparent electrode corresponding to each pixel on the inner surface of the glass substrate, and has a bus line and a thin film transistor for switching. Since it is formed, it is manufactured by repeating film formation and patterning. Therefore, in order to manufacture a liquid crystal panel, the patterning process of spin-coating a photoresist to form a resist pattern and performing development using the resist pattern as a mask is repeated several times.

FIG. 5 is a plan view and a central sectional view showing a conventional apparatus for spin coating a photoresist. Reference numeral 1 denotes a rectangular substrate (glass plate), which is placed on the substrate holding plate 2. The circular opening of the substrate holding plate 2 is fixed to the upper end of a cylindrical rotary shaft 3, and the rotary shaft 3 is connected to a vacuum pump to generate a negative pressure.

In spin coating, with the substrate 1a placed on the substrate holding plate 2, the rotary shaft 3 is evacuated by a vacuum pump to adsorb the substrate 1a, and the rotary shaft 3 is rotationally driven at about 1,000 rpm or less. To do. In this state, when a photoresist solution is dropped on the center of the substrate 1a, the photoresist spreads over the entire surface of the substrate 1a by centrifugal force, and spin coating is performed.

[0005]

FIG. 6 is a plan view of the substrate 1a spin-coated and a diagram showing the photoresist film thickness. (b) is the result of measuring the photoresist film thickness in the cross section of the rectangular substrate 1a at the bb position in (a), and the rectangular substrate 1a shows that the photoresist film thickness at the four corners 4 is thick. There is.

In this example, a positive resist OFPR800 having a thickness of 1 μm is applied to a 140 mm square glass substrate. The thickness increases from the four corners 4 toward the center to 5 cm, and the area occupies about 30%. Therefore, as shown in FIG. 7, when the mask 6 is overlaid on the photoresist film 5 to irradiate it with light to perform exposure, the central portion 7 having a small film thickness is used.
The light can reach the entire thickness, but the four corner portions 4 having a large thickness do not reach the light. Therefore, accurate patterning may not be possible during development. 1a is a substrate and 8 is a metal film of Al, ITO, Ti or the like, which is patterned using the pattern of the photoresist film 5 as a mask.

In the liquid crystal panel, a rectangular glass substrate is used, and since it is as large as 300 to 400 mm square, it is difficult to spin coat the photoresist to a uniform thickness for the above reasons. Is.

FIG. 8 is a plan view of the substrate 1a placed on the substrate holding plate 2 of the spin coater. When the substrate 1a is rotated for spin coating, the applied photoresist moves to and concentrates on the four corners 4 of the substrate 1a due to centrifugal force, and the peripheral speed of the four corners 4 is high. As a result, the photoresist is quickly dried and hardened, and the film thickness of the four corner portions 4 is increased as shown in FIG.

As a method of solving this problem, there is known a rotary cup system in which the substrate 1a and the cup covering it rotate integrally. In this method, since the substrate 1a rotates with the air inside the cup, only the four corners dry quickly,
The problem of easy curing is solved, and a coating film with good uniformity can be obtained. However, in this method, it is necessary to cover the outside of the cup with a fixed cup for safety, and there are problems that the equipment becomes large and the equipment cost becomes high.

A technical problem of the present invention is to pay attention to such a problem, and to make it possible to spin coat a photoresist or the like uniformly with a simple apparatus.

[0011]

FIG. 1 is a diagram for explaining the basic principle of a spin coating method according to the present invention. Claim 1
In the invention of FIG. 1, a circular substrate 1b is spin-coated as shown in FIG. 1 (1), and after the spin-coating is completed, it is cut into a rectangle as shown in (2) and the rectangular substrate 1a is used. is there.

According to the second aspect of the present invention, as in (3), a rectangular groove 9 is formed in advance on the back surface of the circular substrate 1, and after spin coating, cutting is performed at the position of the groove 9. is there. According to the invention of claim 3, as in (4), one or a plurality of grooves 10 parallel to the cutting groove 9 are formed outside the cutting groove 9, and after spin coating, The rectangular substrate 1a is left by cutting from the cutting groove 9.

According to a fourth aspect of the present invention, the spin coater side is improved. As shown in FIG. 4, the substrate holding plate 2 and the rectangular substrate 1a mounted on the substrate holding plate 2 are stored in the substrate storage chamber 12. Has a turntable 11 that rotates in a rotating state, holds the substrate 1 so that the surface of the turntable 11 and the surface of the substrate 1 are in the same plane, and cools the substrate storage chamber 12 with inert cooling. Spin coating is performed while supplying gas to cool the substrate 1 from the back surface.

[0014]

According to the first aspect of the present invention, the circular substrate 1b is spin-coated on the substrate 1b in advance, and after the spin-coating is completed, the substrate is cut into rectangles. It will be done in the state of. As a result, the four corners of the rectangular substrate do not exist, and spin coating can be performed to a uniform thickness over the entire surface. After the spin coating, it is cut into a rectangular shape, so that a rectangular substrate 1a suitable for a liquid crystal panel or the like is finally obtained.

According to a second aspect of the present invention, a rectangular groove 9 is previously formed on the back surface of the circular substrate 1b, and after spin coating, cutting is performed at the groove 9 position. Since it is cut, it can be easily cut into a predetermined rectangle. Further, as in claim 3, if one or a plurality of grooves 10 parallel to the cutting groove 9 are formed outside the cutting groove 9,
Since the photoresist that has sneaked from the substrate surface to the back surface of the substrate when spin-coated spills into the groove 10 outside the cutting groove 9, the back surface of the rectangular substrate 1a is stained with the photoresist as in the conventional case, and As a result, the device is not contaminated in the subsequent steps, and the subsequent steps can be smoothly advanced.

According to a fourth aspect of the present invention, the substrate holding plate 2 and the rectangular substrate 1a placed on the substrate holding plate 2 are housed in the substrate housing chamber 12 of the turntable 11 and the surface of the turntable 11 is Since the surfaces of the substrate 1a are aligned in the same plane and the substrate 1a is rotated together with the turntable 11, the wind does not occur only at the four corners 4 of the rectangular substrate 1a. Moreover, since an inert cooling gas is supplied into the substrate storage chamber 12 to cool the substrate 1a from the back surface, the evaporation of the solvent is suppressed over the entire surface of the substrate 1a, and the photoresist drying rate becomes more uniform. As a result, unlike the conventional case, the photoresist is not concentrated and hardened in the four corner portions 4 of the rectangular substrate 1a, and the entire surface has a uniform film thickness.

[0017]

EXAMPLES Next, practical examples of how the spin coating method according to the present invention is embodied will be described. FIG. 2 is a view showing an embodiment of claims 1 to 3, (a) is a rear view of the circular substrate 1b, (b) is an enlarged view taken along line bb in (a), (c).
[Fig. 3] is a rear perspective view of the circular substrate 1b.

The invention of claim 1 is a circular substrate as the substrate.
1b is used to spin-coat and then cut into rectangles, which can be cut by any cutting method. Claim 2
In the invention, as shown in FIG. 2, a groove 9 is formed in advance at a cutting position, and after spin coating, cutting is performed at the position of the groove 9. The groove 9 is formed on the back surface of the circular substrate 1b.

According to a third aspect of the invention, as shown in FIG. 2, a groove 10 parallel to the cutting groove 9 is provided outside the cutting groove 9.
Is formed in advance. Then, after the spin coating, cutting is performed from the position of the cutting groove 9 to form a rectangular portion.
Use 1a.

In this embodiment, since a plurality of grooves 10 are formed in parallel with each other outside the cutting groove 9, the photoresist dropped on the circular substrate 1b is indicated by an arrow a ₁ in FIG. As you can see, it spreads from the center toward the outer circumference, and when it reaches the outer circumference,
The excess photoresist is shaken off by the centrifugal force, and wraps around inside the grooves 9 and 10 on the back surface and propagates into the grooves 9 and 10 as indicated by an arrow a ₂ .

The dashed line 1b in FIG. 6 (a) shows a circular substrate 1b for comparison, and unlike the rectangular substrate 1a, the applied photoresist is evenly distributed toward all outer peripheral positions. Unlike the rectangular substrate 1a in which the photoresist spreads and the photoresist is concentrated in the grooves 9 and 10 on the back surface as described above, unlike the rectangular substrate 1a in which the photoresist is concentrated in the four corners, as shown by the chain line in FIG. , The film thickness on the outer peripheral side is 4 at the four corners of the rectangular substrate 1a.
It is thinner.

Moreover, since the circular substrate 1b has the same outer peripheral positions at the same distance from the center, the wind does not locally occur and the photoresist is not quickly dried. Since the drying speed is constant, the coating film thickness becomes more uniform. In addition, excess photoresist is used for the grooves 9 and 10.
Since it wraps around inside, it does not wrap around on the back surface of the rectangular substrate 1a as in the conventional case, and does not cause problems such as soiling the device in the subsequent steps and hindering alignment. Therefore, the need for back rinse with a solvent during spin coating is reduced. Not only improving the uniformity of resist coating,
Even in other film forming steps, if film formation is performed on a circular substrate, distortion occurring during film formation is reduced and device characteristics are improved as compared with the case of forming a film on a rectangular substrate. .

As shown in FIG. 2 (b), the cutting groove 9 is deeper than the outer groove 10 and can be easily cut.
The shape of the grooves 9 and 10 is preferably V-shaped in consideration of cutting and absorption of excess photoresist.

A substrate used for a liquid crystal panel or the like is not limited to a square, but a rectangular substrate is often used. When a rectangular substrate is required, as shown in FIG.
Is formed into a rectangle.

The steps of applying a photoresist to form a mask and patterning a metal film are required several times when manufacturing a liquid crystal panel, and when one patterning step is completed, the photoresist is a solvent. Wash with
Since it is removed, the photoresist that has entered the grooves 9 and 10 on the back surface is also removed.

Therefore, even if the photoresist wraps around and fills the grooves 9 and 10 in each photoresist coating step, the photoresist completely fills the grooves 9 and 10 and protrudes from the back surface of the substrate. There is no. The cutting in the groove 9 can be performed at any time after the spin coating which requires uniform coating is completed.

FIG. 4 is a diagram showing an embodiment of the invention of claim 4. The inventions of claims 1 to 3 are methods for performing uniform coating on the substrate side, while the invention of claim 4 is for improving the spin coater side.

FIG. 4 (a) is a plan view of a rectangular substrate 1a set on a spin coater, and FIG. 4 (b) is b- in FIG. 4 (a).
b sectional view, (c) is an enlarged sectional view taken along line cc in (a). In terms of spin-coating by rotating the substrate holding plate 2 with the rectangular substrate 1a placed on the substrate holding plate 2 fixed to the upper end of the cylindrical rotating shaft 3 connected to the vacuum pump, This is the same as the conventional device shown in FIG.

In the present invention, there is a turntable 11 that rotates together with the substrate holding plate 2, and the turntable 11 has the substrate holding plate 2
A substrate storage chamber 12 for storing the rectangular substrate 1a placed on the substrate holding plate 2 is formed, and the substrate is held so that the surface of the turntable 11 and the surface of the substrate 1a are aligned in the same plane. Board 2
The height of is set. The outer circumference of the substrate storage chamber 12 is formed in a rectangular shape so as to match the outer circumference of the rectangular substrate 1a.

As described above, since the rectangular substrate 1a is embedded in the turntable 11 so that the surface of the substrate 1a and the surface of the turntable 11 are the same, even if the rectangular substrate 1a is rotated, the four corners are rotated. The problem that the wind is generated only in the portion 4 and the applied photoresist is quickly dried is solved. As a result, the photoresist concentrated in the four corner portions 4 is transmitted to the rotary disk 11 outside the rectangular substrate 1a by centrifugal force without being dried and cured, and the excess photoresist is shaken off.

Conventionally, in order to prevent the solvent of the photoresist from evaporating at the four corners 4 of the rectangular substrate 1a,
A method called back rinse is known, in which a cooled solvent is supplied to the back surface of the substrate 1a to cool the substrate 1a and prevent the photoresist from drying quickly.

In this embodiment, cooled inert gas is supplied to the back surface of the substrate 1a instead of the solvent for back rinse. That is, the substrate storage chamber 12 of the turntable 11
Is connected to the cooling gas source via a cylindrical rotary shaft 13 on the outer side of the rotary shaft 3. As the cooling gas, an inert gas such as nitrogen gas is suitable so as not to react with the photoresist. The cooling temperature of the gas is determined by the photoresist coating conditions, and the flow rate and pressure of the gas are determined according to the size and the number of rotations of the substrate 1a. in this way,
By supplying an inert cooling gas into the substrate storage chamber 12 and cooling the substrate 1a from the back surface, quick drying of the applied photoresist can be more reliably prevented.

The substrate storage chamber 12 is formed in accordance with the outer periphery of the rectangular substrate 1a so that the gap 14 between the outer periphery of the substrate 1a and the outer periphery of the substrate storage chamber 12 is as narrow as possible, but there is no gap. Instead, the cooling gas is blown out from the gap 14 to the upper surface of the turntable 11 as shown in FIG. As a result, it is possible to completely eliminate the influence of the wind generated when the substrate 1a rotates, and moreover, the gas blows out from the gap 14 between the substrate 1a and the turntable 11, which prevents the photoresist from wrapping around around the back surface of the substrate 1a. Can be prevented. It should be noted that it is also possible to open the opening 15 on the bottom surface of the substrate storage chamber 12 near the outer periphery as shown by the broken line, and exhaust the used cooling gas to the rear surface side of the turntable 11, whereby the gap 14 can be discharged. You can also control the amount of blowing.

In the conventional method of performing back rinse using a solvent, the solvent may flow around the surface of the substrate 1a and the photoresist may be diluted. However, when a gas is used as in the present invention, Such a problem is solved, and since an inert gas is used in particular, deterioration and alteration of the photoresist can be reliably prevented. In addition, the equipment is simple and easy to manage and maintain.

The turntable 11 is provided with several pins 16 which vertically move through the bottom surface of the substrate storage chamber 12 for attaching and detaching the substrate. The setting is completed by placing the substrate 1a on the pin 16 in a raised state and lowering the pin 16 until the substrate 1a is set on the substrate holding plate 2.

Next, the vacuum chuck mechanism is activated to activate the substrate.
With 1a fixed, the rotary disk 11 and the rotary shaft 3 are rotated to perform spin coating. After the spin coating, when the pin 16 is raised, the substrate 1a is pushed up and can be taken out from the substrate storage chamber 12. The present invention is also effective for spin coating other than photoresist.

[0037]

As described above, according to the present invention, the circular substrate 1b is spin-coated, and after the spin-coating is completed, it is cut into a rectangular shape.
Since it is carried out in the state of 1b, the entire surface can be spin-coated to a uniform thickness, and the conventional apparatus can be used as it is.

According to a second aspect of the present invention, a rectangular groove 9 is previously formed on the back surface of the circular substrate 1, and the third groove 9 is provided outside the cutting groove 9 as in the third aspect. Grooves parallel to 9
If one or a plurality of 10 are formed, it can be easily cut into a predetermined rectangle after spin coating, and the photoresist that has sneaked to the back surface of the substrate at the time of spin coating is guided into the groove 10, so that The back surface of is not contaminated with photoresist, and the subsequent steps can proceed smoothly.

As in claim 4, the rectangular substrate 1a and the turntable 11 are arranged.
In the method in which the surface of the substrate is aligned at the same height and the substrate 1a and the turntable 11 are rotated together for spin coating, wind is generated at the four corners 4 of the outer periphery of the substrate 1a, and the photoresist on that portion is removed. It is possible to prevent quick drying, and to supply the cooling gas to the substrate storage chamber 12 to cool the substrate 1a, so that quick drying of the photoresist can be prevented more reliably, and the thickness of the photoresist is locally thickened. Can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a basic principle of a spin coating method according to the present invention.

FIG. 2 is a diagram showing an embodiment of the invention of claims 1 to 3;

FIG. 3 is a back view of a substrate showing another embodiment of the inventions of claims 1 to 3.

FIG. 4 is a plan view and a vertical sectional view showing an embodiment of the invention of claim 4;

FIG. 5 is a plan view and a central sectional view showing a conventional apparatus for spin coating a photoresist.

FIG. 6 is a plan view of a spin-coated substrate and a diagram showing a photoresist film thickness.

FIG. 7 is a cross-sectional view showing a method for forming a photoresist mask pattern.

FIG. 8 is a plan view showing a change in film thickness due to wind speed during spin coating on a rectangular substrate.

[Explanation of symbols]

 1a Rectangular substrate 1b Circular substrate 2 Substrate holding plate 3 Cylindrical rotation axis 4 Four corners of rectangular substrate 5 Photoresist film 6 Mask for patterning photoresist 7 Thin central part of photoresist film 8 Metal film 9 For cutting Groove 10 Groove for wrapping around excess photoresist 11 Rotating plate 12 Substrate storage chamber 13 Cylindrical rotating shaft 14 Gap 15 Exhaust port at the bottom of the substrate storage chamber 16 Pin for attaching / detaching the substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area // B05C 11/08 6804-4D

Claims (4)

[Claims] 1. A spin coating method comprising spin coating a circular substrate (1b) and cutting the substrate into a rectangle at least after the spin coating is completed. 2. A rectangular groove is previously formed on the back surface of the circular substrate (1b).
2. The spin coating method according to claim 1, wherein (9) is formed in advance, and after spin coating, cutting is performed at the position of the groove (9). 3. One or a plurality of grooves (10) parallel to said cutting groove (9) are formed outside said cutting groove (9). The spin coating method described. 4. A rotating plate (11) for rotating a substrate holding plate (2) and a rectangular substrate (1a) placed on the substrate holding plate (2) in a substrate storage chamber (12). The substrate (1a) is mounted and held so that the surface of the turntable (11) and the surface of the substrate (1a) are flush with each other, and an inert cooling gas is stored in the substrate storage chamber (12). Supply the board (1
A spin coating method characterized by spin coating while cooling a) from the back surface.