JPH05115828A - Coating device - Google Patents

Abstract

PURPOSE:To uniformly apply a coating material on plural substrates to be coated at one time by a spin coating method by providing a horizontal turn table to the center of which the liquid coating material is dropped and a rotational driving device for the table and constituting the table in such a manner that the plural substrates to be coated can be fixed to the periphery of the center of rotation. CONSTITUTION:For example, 4 sheets of the rectangular parallelepiped-shaped substrates to be coated are disposed on the table 2 and the longitudinal direction thereof is disposed in the direction perpendicular to the center line of the table 2 running the position O of the center 3 of rotation. As a result, the difference between the longest distance OB and the shortest distance OA is minimized in the distance between the central point O of rotation of the table 2 and the arbitrary coating position on the substrates to be coated 1. The distance between the total coating surface of the substrates to be coated 1 and the center of rotation of the table is thereby maintained approximately constant and the entire surface of the coating surfaces is coated with the liquid coating material at nearly a specified circumferential speed. The surface of the table 2 and the coating surfaces of the substrates 1 to be coated are made into approximately the continuous and same plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for coating a liquid coating substance on a substrate to be coated.

[0002]

2. Description of the Related Art As is well known, in the spin coating method, a sample on a flat plate such as a wafer or a mask substrate, to which a liquid coating substance such as photoresist is supplied, is rotated on the surface of the substrate to be coated and generated. This is a method of diffusing the liquid coating substance in the outer direction of the surface of the substrate to be coated by centrifugal force to make the coating film uniform. Since the spinner coating apparatus for performing this spin coating is superior in uniformity of the thickness of the coating film as compared with other coating methods such as spray coating, a semiconductor wafer or an exposure mask for the purpose of manufacturing a semiconductor device. In photolithography that forms a fine pattern on a substrate,
It is widely used when applying photoresist to semiconductor wafers and exposure mask substrates.

In recent years, with the increase in size of liquid crystal display elements, the size of wafers has been increasing in order to coat large substrates to be coated and to improve the productivity of semiconductor devices.

1 and 2 are explanatory views of the main part of a conventional example of a spinner device. In the figure, reference numeral 1 indicates a substrate to be coated as a sample, on which a liquid coating substance is coated. Reference numeral 2 indicates a horizontal table, and the substrate 1 to be coated is held on the back side thereof by using a means such as vacuum suction. Reference numeral 9 denotes a motor, which rotates the table 2 in the horizontal direction via the shaft 4. Usually, around these, a so-called cup is generally provided.

In the spinner coating apparatus having the above structure,
The application is performed as follows.

As shown in FIGS. 1 and 2, a circular substrate to be coated 1 such as a wafer is held on a table 2 substantially concentrically.

A liquid coating substance such as a resist is dropped and supplied from the supply means (not shown) to the rotation center portion 3 of the substrate 1 to be coated.

By driving the motor 9, the substrate 2 to be coated is rotated along with its horizontal surface along with the table 2. The liquid coating substance on the substrate 1 to be coated diffuses outward on the surface of the substrate 1 to be coated by centrifugal force, and the excess liquid coating substance on the surface of the substrate 1 scatters from the outer periphery of the substrate 1 A uniform coating film is formed on top.

The rotation of the table 2 is stopped and the substrate 1 to which the liquid coating substance is applied is removed.

A new substrate 1 to be coated is placed on the table 2 again and the above steps 1 to 3 are repeated.

[0011]

By the way, originally, in the coating method of diffusing and coating the liquid coating substance by using the centrifugal force of the rotating table, the peripheral speeds of the rotation center part of the table and its peripheral part are different from each other. Because of the large difference, it was difficult to make the film thickness of the coating film near the rotation center position of the substrate on which the liquid coating material was dripped and the film thickness of the coating film in the peripheral portion (outward direction) equal. Further, when coating is performed using a liquid coating substance containing a volatile solvent or the like, the volatilization (scattering) of the solvent in the peripheral portion becomes larger than that in the vicinity of the rotation center portion due to the difference in peripheral speed. As a result, since the viscosity of the liquid coating material in the peripheral portion is increased, the diffusivity is deteriorated, and the coating film in the peripheral portion tends to be thicker than in the rotation center portion.

Therefore, in the spin coating method in which the liquid coating material dropped on the substrate is diffusion-coated on the substrate by using the centrifugal force of the rotating table, the center of rotation of the table is reduced in order to minimize the above defects and problems. The method of overlapping the centers of the substrates to be coated has been adopted.

[0013] This means that only one substrate to be coated can be coated per coating, which causes a problem of poor coating efficiency.

Therefore, it is an object of the present invention to provide a coating apparatus capable of uniformly coating a coating substance on a plurality of substrates at once.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a horizontal rotary table on the center of which a liquid coating substance is dripped,
And a rotary drive device for rotating the table, wherein a plurality of substrates to be coated are configured to be fixed on the table around the rotation center of the table. ..

Preferably, the substrate to be coated is arranged so that the difference between the longest distance and the shortest distance between the rotation center of the table and an arbitrary coating position on the substrate to be coated is minimized. This is achieved with a coating device.

A surface onto which the liquid coating material is dropped,
This is preferably achieved by a coating device in which the coating surfaces of the substrates to be coated are substantially coplanar.

[0018]

According to the coating apparatus having the above structure, the coating substance can be uniformly coated on a plurality of substrates to be coated at one time.

[0019]

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows the basic arrangement of the substrate 1 to be coated on the table 2 according to the present invention. 4 and 5 are diagrams for explaining the distance between the rotation center 3 of the table 2 and an arbitrary coating position on the substrate 1 to be coated, and the maximum and minimum distances thereof.

In addition, FIGS. 6, 7, 8, 9, and 10.
FIG. 6 is a diagram for explaining that the surface onto which the liquid coating substance is dropped and the coating surface of the substrate to be coated are on substantially the same plane.

In FIG. 3, four coated substrates 1 each having a rectangular parallelepiped shape are arranged on a table 2, and the condition of the arrangement is that the center line of the table 2 passing through the position O of the rotation center 3 is set. And its longitudinal direction is arranged in a vertical direction (θ = 90 °).

FIG. 4 illustrates FIG. 3 in more detail. When the substrate 1 to be coated is arranged as shown in FIG. 3, the straight line passing through the position O of the rotation center 3 and the side in the longitudinal direction of the substrate 1 are perpendicular to each other. Point A (θ = 90 °) that intersects with point O, which is the center of rotation 3.
Let OA be the line segment connecting the two, and let OB be the line segment OB connecting the vertex B of the rectangular substrate 1 to be located closest to the outer periphery of the table 2 and the position O of the rotation center 3. At this time, in the distance between the rotation center point O of the table 2 and an arbitrary coating position on the substrate 1 to be coated, OA represents the shortest distance and OB represents the longest distance. In this case, the longest distance OB and the shortest distance O
The difference in A is the smallest. For example, when θ is set to a value other than 90 °, in other words, when the rectangular substrate 1 is tilted from the solid line position shown to the position indicated by the alternate long and short dash line, the difference between OB and OA increases.

That is, in the coating method in which the liquid coating substance is diffused by using the centrifugal force of the rotating table, the rotation center point O of the table 2 and the table 2 are, as described above.
The peripheral speed of the peripheral part of the vehicle increases as the distance from the rotation center point O increases. Therefore, in order to reduce the variation in the film thickness of the coating film in one substrate to be coated, in other words, to improve the uniformity of the film thickness, the entire substrate 1 to be coated with the liquid coating substance should be coated. It is preferable that the distance between the application surface and the rotation center of the table is substantially constant. By doing so, the liquid application substance is applied to the entire application surface at a substantially constant peripheral speed. If the distance to the center of rotation of the table is greatly different between the long distance and the short distance within one substrate 1 to be coated, the peripheral speed received correspondingly varies, and the uniformity of the film thickness is greatly impaired. .

Similar to FIGS. 3 and 4, FIG. 5 shows a case where the plurality of substrates 1 to be coated are arranged around the rotation center point O of the table 2 in a different arrangement manner. As is clear from FIG. 5, the lateral direction of the coated substrate 1 having a rectangular shape is
In this arrangement, a straight line passing through the rotation center position O of the table is vertically intersected (θ = 90 °). This arrangement
From the comparison with FIG. 4 described above, the distance between the substrate 1 to be coated and the rotation center position O, for example, OB ′ in the drawing is the longest distance, OA ′.
Is the shortest distance, and the substrate 1 to be coated is arranged such that the difference obtained from OB'-OA 'is maximum. In this case, the peripheral speed caused by the rotation of the table is significantly different between the vicinity of A ′ and the vicinity of B ′ of the coated substrate surface 1. Therefore, the uniformity of the film thickness becomes poor.

In the present invention, it is important not only to arrange the plurality of substrates 1 to be coated around the rotation center point O of the table 2 but also to consider the distance between the coating surface and the rotation center. To repeat, in the present invention, as shown in FIG.
By disposing one substrate 1 to be coated, four substrates having the same coating film characteristics can be obtained by one coating operation.

In the above example, the example in which the rectangular substrate to be coated is used has been described, but this is merely an example selected for convenience of description, and in the present invention, the shape of the substrate to be coated used is There is no particular limitation, and therefore, an elliptical shape, a circular shape or the like may be used.

Further, in FIGS. 6, 7, 8 and 9 and 10, it is necessary that the surface 2a of the table 2 on which the liquid coating substance is dropped and the coating surface 1a of the substrate 1 to be coated be substantially continuous and on the same plane. It is a schematic diagram explaining. If the dripping surface 2a of the liquid coating substance and the coating surface 1a of the substrate 1 to be coated are not substantially on the same plane, for example, if there is a step,
For example, FIG. 6 shows a case where the surface of the table on which the liquid coating material is dropped is higher than the coating surface 1a of the substrate 1 to be coated. In this case, the dropped coating material is mostly rotated by the rotation of the table 2. , Is not coated on the substrate 1 to be coated and is scattered outside the table 2. Further, as in the case of FIG. 7, when the dropping surface 2 a of the table 2 is lower than the coating surface 1 a of the substrate 1 to be coated, the dropped liquid coating substance is deposited on the substrate 1 to be coated at the step portion 5. It will hit the wall of and scatter. Further, in the case of FIG. 8, the groove portion 6 is provided between the dropping surface 2a of the table 2 and the coating surface 1a of the substrate 1 to be coated, and in this case as well, the size of the gap of the groove portion 6 is large. If the amount is too much, smooth diffusion coating of the liquid coating material becomes difficult. In any of FIGS. 6, 7 and 8, the level of the step and the quality of the groove differ depending on the properties of the liquid coating material used and the rotation speed of the table. Is difficult to define. However, it goes without saying that in the present invention, it is preferable to minimize both the step and the gap between the grooves.

9 and 10 are schematic views showing one of the embodiments of the present invention. As shown in the figure, the table is
Upper table 7 onto which liquid coating substance is dropped and substrate 1 to be coated
Is divided into a lower table 8 on which the coated substrate 1 is coated, and a coated surface 1a of the coated substrate 1 and a surface 7a of the upper table 7 are coated on the coated substrate 1
Although the upper table 7 has a minute gap in the adjacent portion, it can be said that they are substantially continuous and on the same plane. In such a case, the liquid coating substance dropped on the position of the rotation center 3 of the upper table 7 smoothly moves onto each substrate 1 to be coated through the surface of the upper table 7 as the table rotates.

Although not shown, it is also possible to consider a structure in which the table is provided with a recess for allowing the entire substrate to be coated to fall, so that the table surface and the substrate coating surface are flush with each other.

Although the arrangement of the coated substrates in the present invention has been described above, the number of coated substrates arranged on the table is arbitrary. For example, in FIG. 11, six substrates 1 to be coated are arranged, and here, θ = 90, α, β
The value is 60 °.

As the liquid coating material that can be used in the present invention, all the liquid coating materials that can be used by the conventional spin coating method can be used. A typical example is a resist solution.

The uniformity of the coating thickness in the present invention is
Determine as follows. That is, after the coating substance is coated on the substrate to be coated, the film thickness of the coating film formed by being solidified by heat treatment or the like is measured at many positions with respect to the entire coating surface, and the obtained measurement data is obtained. It is expressed by the difference between the maximum film thickness value and the minimum film thickness value. That is, the smaller the difference, the better the uniformity of the film thickness. Regarding the method of measuring the film thickness, any of several conventionally known methods can be arbitrarily selected. For example, there are a mass measurement method, a stylus method, an absorbance method, a light section method, an interferometry method, an ellipsometry method, and a SEM (scanning electron microscope).

Next, a more specific example of the embodiment of the present invention will be described.

First, four glass plates having a thickness of 1.1 mm, a width of 150 mm and a length of 50 mm were used as substrates to be coated, and a solid component 4 was used.
A resist solution (main solvent in the resist, ethyl cellosolve acetate) adjusted to 4% and a viscosity of 300 cps (25 ° C.) was used as a liquid substance, and was applied by the application device shown in FIG. As the conditions of the apparatus, the rotation number of the table was 400 rpm, the rotation time was 20 seconds, and the dropping amount of the resist solution was 25 ml.

As a result, in each of the four coated substrates, the maximum film thickness is about 86 μm and the minimum film thickness is about 80 μm.
μm was obtained, and the difference was about 6 μm. In this case, 15 coating points were set for each coated substrate and the film thickness was measured. For comparison, when a coating test was conducted under the same conditions with the coating apparatus of the embodiment shown in FIG. 5 and evaluated, the maximum film thickness was about 89 μm and the minimum film thickness was about 72 μm.
μm, and the difference was about 17 μm. When applied in the form of FIG. 9, excellent film thickness uniformity was obtained.

[0037]

As described above, according to the present invention, (1) it is possible to coat a plurality of substrates to be coated with one coating operation as compared with the conventional one, so that the coating efficiency is significantly improved. improves. Moreover, the characteristics of the individual coating films applied are the same.

(2) Even in an elongated substrate to be coated having a rectangular shape, the variation in the film thickness characteristics of the coating film can be suppressed to the minimum.

[Brief description of drawings]

FIG. 1 is a side view of a main part of a conventional coating device.

FIG. 2 is a plan view of a main part of a conventional coating device.

FIG. 3 is a plan configuration diagram of a rotary table of an apparatus showing an example of a basic arrangement of substrates to be coated in the coating apparatus of the present invention.

FIG. 4 is a plan view of the table showing the relationship between the longest distance and the shortest distance from the rotation center of the rotary table of the coating apparatus of the present invention to the coating surface.

FIG. 5 is a plan view of a table showing the relationship between the longest distance and the shortest distance from the rotation center of the rotary table of the coating apparatus of the comparative example to the coating surface.

FIG. 6 is a side sectional view of a main part of a coating apparatus of a comparative example.

FIG. 7 is a side sectional view of a main part of a coating device of a comparative example.

FIG. 8 is a side sectional view of a main part of a coating apparatus of a comparative example.

FIG. 9 is a main part plan view of an apparatus showing another embodiment of the coating apparatus of the present invention.

FIG. 10 is a side sectional view of an essential part of an apparatus showing another embodiment of the coating apparatus of the present invention.

FIG. 11 is a plan view of a main part of an apparatus showing still another mode of the coating apparatus of the present invention.

[Explanation of symbols]

 1 coated substrate 1a coated surface 2 table 2a surface 3 rotation center 4 axis 5 step 6 groove 7 upper table 7a surface 8 lower table 9 motor

Claims (3)

[Claims] 1. At least a horizontal rotary table on which a liquid coating substance is dropped, and a rotary drive device for rotating the table, wherein a plurality of substrates to be coated on the table are the center of rotation of the table. An applicator characterized in that it can be fixed to the periphery of. 2. The substrate to be coated on the table is fixed so that the difference between the longest distance and the shortest distance in the distance between the rotation center of the table and an arbitrary coating position on the substrate to be coated is minimized. The coating device according to claim 1, wherein the position is set. 3. The coating apparatus according to claim 1, wherein the surface of the table on which the liquid coating substance is dropped and the coating surface of the substrate to be coated fixed on the table form substantially the same plane. ..