JP2002177874A - Coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method capable of applying a coating liquid to the surface of a substrate thinly and uniformly in a short time. SOLUTION: A slit nozzle 6 faces one end of a glass substrate W from the upper side. While a coating liquid 10 is sprayed from the slit nozzle 6, the slit nozzle 6 is moved parallel to the glass substrate W, thereby roughly applying the coating liquid to almost whole surface of the glass substrate W. Subsequently, an inner cup 2 is rotated to rotate the glass substrate W concurrently, which uniformly disperses the coating liquid coated on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a coating solution such as a photoresist to a substrate surface such as a glass substrate or a semiconductor wafer.

[0002]

2. Description of the Related Art As a means for uniformly applying a photoresist solution for a color filter to a glass substrate of a liquid crystal display device and uniformly applying various coating solutions to the surface of a semiconductor wafer, a coating solution is dropped on the center of the substrate. The substrate is rotated at a high speed, and the coating liquid is uniformly diffused over the entire surface of the substrate by centrifugal force.

In the method in which the substrate is rotated by the above-mentioned spinner, the amount of the coating liquid scattered from the substrate increases because the coating liquid dropped at the center is uniformly diffused to the periphery.
As a result, a large amount of coating liquid is used.

Therefore, a prior art using a slit nozzle in order to suppress the use amount of the coating liquid is disclosed in Japanese Patent Laid-Open No. 63-1563.
No. 20, JP-A-4-332116, JP-A-6-332116
No. 5-1296.

The technique disclosed in JP-A-63-156320 and JP-A-4-332116 discloses a technique in which a coating liquid is dropped while moving a slit nozzle facing the substrate in parallel with the substrate. Japanese Patent Application Laid-Open No. 6-15129 discloses a method in which a coating solution is applied to a uniform thickness to some extent, and then the substrate is rotated to make the thickness of the coating solution uniform.
The technique proposed in Japanese Patent Laid-Open Publication No. 6-2006 is to make the thickness of the coating liquid uniform at the tip of the slit nozzle.

[0006]

Problems to be Solved by the Invention
In the methods disclosed in Japanese Patent Application Laid-Open No. 20-320 and Japanese Patent Application Laid-Open No. 4-332116, since the coating liquid is simply dropped onto the substrate surface, the surface tension acts on the coating liquid itself at the time of dropping. Therefore, it cannot be applied uniformly, or a large amount of coating liquid is required to apply it uniformly.

In the above prior art, since the substrate is rotated in an atmosphere open to the outside air, the solvent in the coating solution evaporates at a high rate, and the viscosity of the coating solution rapidly increases, and Difficult to diffuse evenly.

On the other hand, in the method disclosed in JP-A-6-151296, since the tip of the nozzle is in contact with the coating liquid, the nozzle is easily stained, and when the nozzle is separated from the coating liquid after coating, the film thickness is reduced. Becomes uneven.

[0009]

In order to solve the above-mentioned problems, the present invention sets a rectangular substrate or a disk-shaped substrate in a cup and applies the coating to substantially the entire surface of the surface of the rectangular substrate or the disk-shaped substrate. After the liquid was roughly applied, the cup was rotated and the coating liquid applied on the substrate surface was uniformly diffused by centrifugal force. Here, it is preferable to close the opening on the upper surface of the cup with a lid before rotating the cup.

Further, another invention of the present application is different from the above invention,
The coating liquid is roughly applied to substantially the entire surface of the rectangular substrate or the disk-shaped substrate, and immediately thereafter, the rectangular substrate or the disk-shaped substrate is set in the cup, and then the cup is rotated and the substrate is centrifugally applied. The coating liquid applied to the surface was uniformly diffused. Also in this case, it is preferable to close the opening on the upper surface of the cup with the lid before rotating the cup.

In each of the above-mentioned inventions, as a means for roughly applying the coating liquid over substantially the entire surface of the rectangular substrate or the disk-shaped substrate, a jetting method from a slit or a nozzle, a roll coater method, and a bar coater method are preferable. is there.

[0012]

[Function] A rectangular substrate or a disk-shaped substrate is set in a cup, and the cup is rotated with the opening on the upper surface of the cup closed with a lid, and the coating liquid is uniformly diffused by centrifugal force, thereby drying. Diffusion in an atmosphere that is difficult to perform becomes possible.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a perspective view of a coating apparatus used to carry out the method of the present invention, FIG. 2 is a cross-sectional view of the coating apparatus,
FIG. 3 is a cross-sectional view of the tip of the slit nozzle. In the coating apparatus, an inner cup 2 rotated by a spinner is disposed in an outer cup 1.

A drain pipe 3 protrudes from an outer peripheral portion of the inner cup 2, a tip end of the drain pipe 3 faces a recovery passage 4 in the outer cup 1, and a chuck 5 is provided in the inner cup 2. The glass substrate W is suction-held by the chuck 5.

On the other hand, a slit nozzle 6 is arranged above the inner cup 2. The slit nozzle 6 is attached to an arm (not shown), and performs vertical movement and horizontal movement parallel to the surface of the glass substrate W as shown in FIG.

The coating liquid is supplied to the slit nozzle 6 via a pressurizing device 7, and the structure of the slit nozzle 6 is not limited to the structure having one nozzle hole 8 as shown in FIG. As shown in FIG. 4, gas ejection holes 9, 9 may be formed before and after the nozzle hole 8, and the coating solution 10 may be drawn out with the gas ejection power from the gas ejection holes 9, 9 to apply the coating solution.

In the above description, in order to apply the coating liquid to the glass substrate W, as shown in FIG.
The slit nozzle 6 is moved in parallel with the glass substrate W while ejecting the coating liquid 10 from the above to apply the coating liquid to substantially the entire surface of the surface of the glass substrate W. Thereafter, by rotating the inner cup 2, the glass substrate W is simultaneously rotated to uniformly diffuse the coating liquid applied to the surface. Simultaneous rotation suppresses the generation of airflow on the substrate, which can contribute to uniformity of the film.

In the above coating method, the slit nozzle 6
Although the start position and the end position of the application by the above are set above the edge of the glass substrate W, the start position and the end position may be set to positions deviated from the edge of the glass substrate W. In this case, the coating liquid can be applied even to the edge of the glass substrate W although some application liquid is wasted.

When the coating liquid is uniformly diffused by rotation, it is preferable to apply the coating liquid as thinly and uniformly as possible in the coating step using the slit nozzle 6 in the preceding step. For this purpose, when the coating liquid is jetted toward the surface of the glass substrate, it may be performed while suppressing the surface tension of the coating liquid.

Factors relating to the surface tension of the coating solution include the viscosity (cP) of the coating solution, the pressure applied to the coating solution (kg / cm2), the distance between the lower end of the slit nozzle and the substrate surface (mm), and the movement of the nozzle. The speed, the surface roughness of the substrate, the temperature, and the like can be considered.

For example, when considering a photoresist for a color filter, the usual viscosity is 10 cP or less.
For such a coating solution of 10 cP or less, the above conditions ~
Is fixed, the pressure P applied to the coating solution is 0.5 (kg / cm
2) It is preferable that the distance D between the lower end of the slit nozzle and the surface of the substrate is 10 (mm) or less, and 10 (kg / cm2) or less.

FIG. 5 is a cross-sectional view showing a state in which a coating is applied to a semiconductor wafer W as a substrate. In this case, a slit nozzle 6 is exposed above the semiconductor wafer W, and the coating liquid 10 After applying the coating liquid to substantially the entire surface of the semiconductor wafer W by rotating the semiconductor wafer W at a low speed while suppressing the surface tension, the semiconductor wafer W is rotated at a high speed to diffuse the coating liquid uniformly.

The following (Table) shows a photoresist for a color filter having a viscosity of 6.5 cP using the nozzle shown in FIG. 4 at a moving speed of the nozzle of 500 mm / s, a temperature of 23 ° C., a humidity of 50%, and a distance of 5 mm from the substrate. In the state of the above, when applying on a 200 mm x 200 mm glass substrate, the pressure (kg / cm2) applied to the coating solution and the amount of dropping (g) were changed, and the result was obtained by rotating at 700 rpm for 6 seconds. Was evaluated. When a conventional nozzle was used, a pressure of 1.0 kg / cm 2 was required, and 3.00 g of photoresist was required to cover the entire surface of the glass substrate. The average film thickness at this time is 1.82 μm,
The uniformity was ± 2.84%.

[0024]

[Table 1]

Further, the rotating cup type coating apparatus is not limited to the above-described one having an open top, and FIG.
As shown in FIG. 5, a so-called rotary cup type coating apparatus having lids 21 and 22 for closing the openings of the outer cup 1 and the inner cup 2 may be used.

That is, the cover 21 for the outer cup 1 is connected via the pin 25 to the support block 24 at the tip of the arm 23 which can move linearly, rotationally, vertically, or a combination thereof.
Are slidably mounted vertically, and the support block 24
The lid 22 for the inner cup 2 is attached to a shaft 26 provided at the bottom.

When closing the upper openings of the outer cup 1 and the inner cup 2, the arm 23 is moved to position the lids 21 and 22 above the coating apparatus, and then the arm 23 is lowered. Then, first, the lid 21 closes the upper surface of the outer cup 1, and then the arm 23,
The support block 24 and the lid 22 descend, and the lid 22 closes the upper surface opening of the inner cup 2.

As described above, when the upper openings of the outer cup 1 and the inner cup 2 are closed by the lids 21 and 22, the concentration of the solvent in the inner cup 2 becomes high, so that the evaporation of the solvent from the coating solution is suppressed. As a result, a rise in the viscosity of the coating solution can be suppressed, so that smooth diffusion can be achieved.
In addition, a more uniform coating film can be obtained by providing a rectifying plate below the inner cup lid in parallel with the substrate W and reducing the gap above the substrate W.

FIG. 7 is a view for explaining a coating method according to another embodiment. In the above-described embodiment, the coating liquid is applied to substantially the entire area of the substrate inside the rotary coating apparatus. However, in this embodiment, another coating station 30 is arranged outside the coating apparatus, and this coating station 3
At 0, the coating liquid 10 is roughly applied to almost the entire surface of the substrate W using, for example, a roll coater 31, and then the substrate W is set in the inner cup 2, and then the upper surface of the outer cup 1 and the inner cup 2 Opening the lid 21,
At 22, the inner cup 2 is rotated, and the coating liquid 10 applied to the surface of the substrate W is uniformly diffused by centrifugal force.

In the above embodiment, the slit nozzle and the roll coater are shown as means for roughly coating the coating liquid on substantially the entire surface of the substrate W. As shown in FIG.
The coating liquid 10 may be applied in a dot shape to substantially the entire surface of the substrate W using the ink jet 32, and thereafter, the substrate W may be rotated to be uniformly diffused.

As a means for roughly coating the coating liquid over substantially the entire surface of the substrate W, a roll coater method or a bar coater method may be used in addition to the above.

[0032]

According to the present invention as described above,
In applying a coating liquid such as photoresist to the surface of a rectangular substrate such as a glass substrate or a disk-shaped substrate such as a semiconductor wafer, a slit nozzle that can be simultaneously applied with a certain width is used. Since the coating is applied while applying pressure to the coating liquid with a small interval, the surface tension of the coating liquid when it comes into contact with the substrate surface can be controlled, and the coating liquid can be applied to the substrate surface thinly and uniformly in a short time. And the amount of the coating liquid used can be greatly reduced.

As a device for uniformly dispersing the coating liquid applied to substantially the entire surface of the substrate surface, a rotatable inner cup is disposed inside the outer cup, and the upper surface of the outer cup and the upper surface of the inner cup are closed with a lid. When a structure having a structure is used, the solvent concentration in the inner cup can be kept high during diffusion, so that the increase in the viscosity of the coating solution applied on the substrate surface is suppressed, and the uniformity of the thickness of the coating film is further improved. .

Further, if the solvent concentration in the inner cup can be maintained high, the position where the coating liquid is applied to substantially the entire surface of the substrate and the position where the applied coating liquid is diffused by rotation can be separated. This is advantageous in terms of apparatus design, and a roll coater, a bar coater, a flow coater, a spray, an electrostatic coating, an ink jet, or the like can be used in addition to the slit nozzle.

[Brief description of the drawings]

FIG. 1 is a perspective view of a coating apparatus used to carry out a method of the present invention.

FIG. 2 is a sectional view of the coating apparatus.

FIG. 3 is a sectional view of the tip of a slit nozzle.

FIG. 4 is a sectional view showing another embodiment of the slit nozzle.

FIG. 5 is a cross-sectional view showing a state in which a semiconductor wafer is being coated;

FIG. 6 is a cross-sectional view showing a state in which a coating liquid is diffused by a coating apparatus having a lid.

FIG. 7 is a view for explaining a method of roughly applying a coating liquid to a substrate outside a rotating cup type coating apparatus.

FIG. 8 is a diagram showing a state in which a coating liquid is roughly applied to substantially the entire area of a glass substrate by an ink jet;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer cup, 2 ... Inner cup, 5 ... Chuck, 6 ... Slit nozzle, 7 ... Pressurizing device, 8 ... Nozzle hole, 9 ... Gas ejection hole, 10 ... Application liquid, 21 ... Lid for outer cup, 22 ... Lid for inner cup, 30. Coating station, 31. Roll coater, 32. Ink jet, W.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Futa Shimai 150 Nakamurako Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Tokyo Ohka Kogyo Co., Ltd. (72) Inventor Akira Uehara 150 Nakamaruko Nakahara-ku Kawasaki City, Kanagawa Prefecture Higashikyo Ohka Kogyo Incorporated F term (reference) 2H025 AA18 EA05 4D075 AC02 AC06 AC21 AC22 AC64 AC73 AC79 AC84 AC91 CA48 DA06 DA08 DB13 DB14 DC22 DC24 EA07 EA45 5F046 JA02 JA05 JA10 JA16 JA19

Claims (5)

[Claims] 1. A rectangular substrate or a disk-shaped substrate is set in a cup, and the coating liquid is roughly applied to substantially the entire surface of the rectangular substrate or the disk-shaped substrate. Wherein the coating liquid applied to the substrate surface is uniformly diffused. 2. A rough coating of a coating solution over substantially the entire surface of a rectangular substrate or a disk-shaped substrate, and immediately thereafter, the rectangular substrate or a disk-shaped substrate is set in a cup, and then the cup is rotated and centrifuged. A coating method, wherein the coating liquid applied to the substrate surface is uniformly diffused by force. 3. The coating method according to claim 1, wherein the means for roughly applying the coating liquid to substantially the entire surface of the rectangular substrate or the disk-shaped substrate suppresses the surface tension of the coating liquid. A coating method characterized in that the coating is performed while performing. 4. The coating method according to claim 1 or 2, wherein the means for roughly coating the coating liquid on substantially the entire surface of the rectangular substrate or the disk-shaped substrate comprises a method of jetting from a slit or a nozzle. A coating method, which is one of a roll coater method and a bar coater method. 5. The coating method according to claim 1, wherein the opening of the upper surface of the cup is closed with a lid before rotating the cup.