JP2533401B2 - Rotary coating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention applies a coating liquid such as a photoresist liquid to the surface of a substrate such as a glass substrate for a liquid crystal display panel, a semiconductor wafer, or a mask substrate for manufacturing a semiconductor device. The present invention relates to a rotary coating device used when coating a thin film.

<Prior Art> A rotary coating apparatus is one in which a coating liquid supplied onto a substrate is diffused and flowed on the substrate by centrifugal force to coat by rotating the substrate. Therefore, the film thickness tends to be thicker than the others.

This is because the corners of the rectangular substrate rotate with the wind blown, so that the corners receive wind more strongly than others, the evaporation of the solvent component of the coating liquid is promoted, the viscosity of the coating liquid increases, and the diffusion flow due to centrifugal force occurs. Because it weakens. Also, even if it is round,
The larger the difference, the more significant the difference in peripheral speed of rotation between the inside and the outside of the radial direction. Therefore, in a large-sized substrate, the tendency of increasing the film thickness at the peripheral portion cannot be ignored.

As a rotary coating apparatus which has dealt with the problem in such a rectangular substrate or a large substrate, there are (1) JP-A-57-48980, (2) JP-B-58-4588, and (3) JP-A-5-48980. As shown in JP-A-1-135565, a substrate horizontally mounted on a turntable is rotated synchronously with a rotating container surrounding the turntable, and a coating liquid supplied onto the substrate is diffused and flowed by a centrifugal force. It is known that a thin film is formed by coating on the upper surface of the substrate.

In the conventional examples (1), (2) and (3), the substrate is airtightly or substantially airtightly enclosed in a rotating container, the substrate is rotated together with the container, and the coating solution is spin-coated to spin-coat the substrate. The substrate is placed in an atmosphere of the coating liquid solvent, and even in areas such as the corners of the substrate where the wind is stronger than others, the partial evaporation of the solvent components is prevented from being accelerated, and the film thickness is increased due to the wind. There is an effect that it is possible to suppress unevenness to some extent.

<Problems to be Solved by the Invention> However, the above-mentioned conventional example has the following problems.

That is, in each of the above-mentioned conventional examples, since the rotating container hermetically or substantially hermetically surrounds the substrate for spin coating, the coating solution mist generated by rotation drifts in the rotating container and contaminates the front and back surfaces of the substrate. It is inconvenient.

The operation of the conventional examples (1) and (2) is that the periphery of the substrate is hermetically surrounded by a rotating container that rotates in synchronization with the substrate,
A "uniform atmosphere of the coating solution solvent" is created around the substrate to prevent partial vaporization acceleration of the coating solution solvent, thereby trying to obtain a uniform film thickness. If the rotation container is incompletely closed or the packing or the like is defective due to inadequate substrate loading / unloading work, etc., there is a problem that uniform coating liquid becomes difficult due to the influence.

In addition, the conventional examples (1) and (2) are not suitable for continuous processing because the excess coating liquid is stored in the rotary container, and the conventional example (3) has an excessive amount at the bottom of the rotary container. This has been dealt with by providing a small hole or tube for discharging the coating solution, but if the opening area of such small hole or tube is too small, the excess coating solution will not be discharged sufficiently and the mist in the container will increase. When the opening area is large, the distribution of the solvent atmosphere in the container becomes uneven, which easily causes the film thickness unevenness.

The present invention has been made in view of such an actual situation, and an object thereof is to eliminate the above-mentioned inconvenience by improving the formation structure of the coating processing space for loading the substrate.

<Means for Solving the Problems> In order to achieve the above object, a rotary coating apparatus of the present invention has a rotary table having a size equal to or larger than the outer shape of a substrate and rotating the substrate in a horizontally supported state. And an upper portion which is arranged in parallel with the upper surface of the substrate supported on the turntable at a predetermined small interval and has a size equal to or larger than the outer shape of the substrate and which is rotated integrally with the turntable. A rotary plate is provided, and an outer peripheral edge of a flat coating processing space formed between the rotary table and the upper rotary plate is opened to allow the excess coating liquid to be scattered and flown out.

<Operation> According to the present invention, the air layer in the flat coating processing space formed between the rotary base and the upper rotary plate rotates together with the rotary base and the upper rotary plate that rotate integrally to rotate the coating space. Since no air flow is generated on the surface of the substrate contained inside, a uniform film thickness can be obtained.

Further, since the outer side in the radial direction of rotation in the coating processing space is open, the excess coating liquid mist scattered from the substrate is promptly removed from the space and does not adhere to the substrate. Moreover, the excess coating liquid mist once removed from the coating processing space does not flow into the coating processing space again because there is no air flowing in or out of the coating processing space.

<Embodiment> FIGS. 1 to 3 show an embodiment of the rotary coating apparatus according to the present invention.

This rotary coating apparatus is equipped with a rectangular substrate 1 and rotates horizontally about a vertical axis P, and a rotary table 2 above which is installed in parallel with the rotary table 2 and rotates integrally with the rotary table 2. Rotating plate 3, upper supporting plate 4 for supporting this upper rotating plate 3, waste liquid recovery case 5 fixedly arranged so as to surround the lower and peripheral portions of these rotating members, and output as a vertically rotating shaft. A motor 7 having a shaft 6 provided upright is provided.

The motor 7 is connected to and supported by a bracket 9 provided on a base plate 8, and a central boss 10 of the rotary table 2 is externally fitted onto a vertically oriented rotary shaft 6 from above to drive a drive pin 6a provided on the rotary shaft 6. Is engaged with the notch 10a of the boss 10 to transmit rotation.

The turntable 2 is configured as an outer disk which is sufficiently larger than the outer shape of the board 1, and the board 1 is horizontally mounted and supported on a large number of board support pins 11 standing upright on the upper surface thereof. There is. Further, four pairs of engaging pins 12 that engage with the four corners of the board 1 are provided on the turntable 2, and the board 1 is horizontally rotated integrally with the turntable 2 by these pins 12. As shown in FIG. 2, a resin collar 13 is fitted on the engaging pin 12 so as not to damage the edge of the substrate 1.

A spacer ring 14 and a ring plate 15 having the same outer diameter as that of the rotary table 2 are connected to the rotary table 2 at the same location in the radial direction at a plurality of positions, and the ring plate 15 is connected to the upper support plate 4 at the same time. Is detachably mounted via a knob bolt 16, and by removing the upper support plate 4, the substrate 1 can be taken in and out from the central opening of the ring plate 15. A grip 17 for attachment / detachment is provided on the central upper surface of the upper support plate 4 material.

The spacer ring 14 has a trapezoidal cross-sectional shape, and the upper and lower washers 19 externally fitted to the connecting bolt 18 are provided.
A gap 20 for draining the waste liquid, which corresponds to the thickness of, is formed at the top and bottom.

The upper rotary plate 3 is a disk having a diameter larger than the outer shape of the substrate 1, and is bolted to the lower surface of the upper support plate 4 via a collar 21. The distance between the substrate 1 and the upper rotary plate 3, that is, the distance between the upper surface of the substrate 1 and the lower surface of the upper rotary plate 3 is 50 mm or less for any large substrate, and various factors such as warpage of the substrate 1 are taken into consideration. The spacing is as narrow as possible, and for a 300 mm square substrate, for example, the practically desirable spacing is around 10 mm.

The bottom of the waste liquid recovery case 5 is narrowed down, and a waste liquid discharge port 22 is formed at the lower end thereof, and exhaust ports 23 for discharging solvent gas evaporated from the coating liquid and coating liquid mist are formed at a plurality of circumferential positions. Has been done.

The rotary coating apparatus of the present invention is configured as described above, and in the coating process, first, the upper support plate 4 is removed and the substrate 1 is placed on the substrate support pins 11 of the rotary table 2 in a predetermined posture. Installed and set.

Next, a coating liquid supply nozzle (not shown) is moved above the center of the substrate 1, and a predetermined amount of the coating liquid is dropped and supplied.

After that, the upper support plate 4 is mounted and fixed on the ring plate 15, and the motor 7 is activated to horizontally rotate the rotary base 2, the upper support plate 4, the upper rotary plate 3 and the substrate 1 integrally.

By this rotation, the coating liquid on the substrate 1 is diffused and flowed outward by the centrifugal force, and is applied thinly on the upper surface of the substrate 1.

In this case, the air layer in the flat coating processing space S formed between the rotary table 2 and the upper rotary plate 3 also rotates integrally, and the diffusion flow of the coating liquid is performed on the substrate 1 without generating an air flow. Be seen.

The excess coating liquid flowing on the substrate 1 and reaching the outer periphery flows out from the peripheral edge of the substrate 1 and is scattered from the entire outer periphery of the coating processing space S. Then, the scattered coating liquid is used for the spacer ring 14
Through the gaps 20 formed at the upper and lower sides of the container, it flows out into the waste liquid recovery case 5 and is recovered.

Another embodiment of the invention is shown in FIGS.

In this case, basically there is no difference from the previous embodiment, but in order to connect the ring plate 15 on the rotary table 2 with the bolts 18, the spacer ring 14 and the washer 19 are connected to each other as shown in FIG. Instead, a spacer pipe 24 is used, and the space between the rotary table 2 and the ring plate 15 is largely opened over the entire circumference, and excess coating liquid and solvent evaporation gas from the coating processing space S immediately flow into the waste liquid recovery case 5. It is like this.

Further, the upper rotary plate 3 does not necessarily need to be attached to the ring plate 15 with the upper support plate 4 interposed therebetween. Then, the upper rotating plate 3
May be directly attached to the ring plate 15. However,
In order to transfer the substrate 1 to the turntable 2 and to supply the coating liquid, it is necessary to attach it detachably.

Although not shown, a nozzle for spraying the cleaning liquid onto the lower surface of the substrate 1 is fixed to the center of the rotary table 2 or is rotatably provided integrally with the rotary table 2, and the cleaning liquid is rotated along with the rotation of the substrate 1. By centrifugally flowing outward along the lower surface, even if the coating liquid mist enters the space below the substrate 1, it may be possible to prevent the coating liquid mist from adhering to and soiling the lower surface of the substrate.

Further, the means for mounting and fixing the substrate 1 on the rotary table 2 is not limited to the above configuration, and a vacuum chuck method can be adopted.

<Effects of the Invention> As described above, according to the rotary coating apparatus of the present invention, the following effects are brought about.

In the flat coating process space formed between the rotary table and the upper rotary plate, there is no movement of air to the substrate surface, and the partial vaporization of the coating liquid solvent is caused by the partial increase in the viscosity of the coating liquid. The increase in film thickness was eliminated, and it became possible to apply a uniform coating film.

The coating process space does not seal the substrate,
Since the outer side in the radial direction of rotation in the same space is open, the excess coating liquid mist is promptly removed from the same space, so that it does not adhere to the substrate and contaminate it.

Since the excess coating liquid does not collect in the same space, it is not necessary to remove the excess coating liquid stored in the rotating container as in the device for sealing the substrate, and the productivity is suitable for continuous processing.

The excess coating liquid is scattered and discharged from the outer periphery of the coating processing space, and a part thereof floats in the form of mist, but since there is no air flowing into or out of this coating processing space, the coating liquid mist returns to the coating processing space. Does not adhere to the substrate.

Since the outer space of the coating process space is only for the excess coating liquid to flow out by centrifugal force, it may have any form, and a desired waste liquid treatment form can be freely set.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention. FIG. 1 is a vertical sectional view of the entire rotary coating apparatus, FIG. 2 is an enlarged vertical sectional view of essential parts, and FIG. It is a partially cutaway plan view of the portion. Further, FIGS. 4 and 5 show another embodiment, FIG. 4 is a vertical sectional view of the whole, and FIG. 5 is an enlarged vertical sectional view of a main part. 1 ... Substrate, 2 ... Rotating table 3 ... Upper rotating plate

Claims (1)

(57) [Claims] 1. A rotary table having a size equal to or larger than the outer shape of the substrate and rotating the substrate in a state of horizontally supporting the substrate, and parallel to the upper surface of the substrate supported on the rotary table at a predetermined small interval. A flat plate formed between the rotary table and the upper rotary plate, which is provided and has a size equal to or larger than the outer shape of the substrate, and includes an upper rotary plate that rotates together with the rotary table. Rotating coating device that opens the outer peripheral edge of the coating space to allow the excess coating liquid to scatter and flow out.