JPS6031817Y2 - Film rotation coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spin coating device, and more particularly to a spin coating device for forming a thin film of resin or the like.

A spinner coating method is widely used as a method for applying liquid resin or the like onto a coating substrate.

According to this method, the coating film can be formed with a thickness of about 0.1 to 5 μm.

As shown in Fig. 1, a commonly used rotary coating device using a spinner coating method has a chuck table 1 that rotates at high speed around a vertical axis line A-A. A board 2 for use is placed thereon.

The chuck table 1 has a suitable rotating shaft portion 3, and this shaft portion is rotated by a rotation driving means such as a motor (not shown).

A sealing ring 4 made of rubber or the like is attached to the upper surface of the chuck table 1, and the substrate 2 is placed on this ring 4.

A vacuum suction hole 5 connected to a vacuum pump is formed in the shaft portion 3 and the chuck base 1, and when the vacuum pump is operated, a vacuum is applied to the lower space 6 of the substrate 2 through the suction hole 5. 2 is held on the chuck stand 1 by suction.

As the chuck table 1 rotates, the substrate 2 is also rotated.

After setting the substrate 2 on the stationary chuck table 1, drop the liquid resin 7 as a film forming material onto the substrate 2, reduce the pressure through the vacuum suction hole 5, and fix the substrate 2 to the chuck table 1 by vacuum suction. When the taste chuck table 1 is rotated at a rotational speed of 100 to 7000 rpm, the liquid resin is diffused onto the substrate surface by centrifugal force or the like, and a thin film 7a is formed on the substrate surface as shown in FIG.

An example of the use of the film 7a formed in this way is to form a photosensitive resin film as the film 7a, expose it to light,
Color separation filters for image pickup tubes and solid-state image pickup devices can be obtained by performing development, followed by plate making and coloring.

In addition, a photomask is made by spin-coating a negative or positive type photoresist on a substrate formed by forming a Cr layer or the like on a glass plate, and then exposing and developing it to obtain a resist layer.
It is manufactured by etching the Cr layer using a resist layer as a masking layer.

Furthermore, I.C. In one step of lithography for LSI, a photoresist is spin-coated onto a wafer as a substrate, and after plate making, SiO□, polysilicon, aluminum, etc. are etched.

An example of the process of spin-coating a photosensitive resin onto a substrate and making a plate is explained with reference to FIGS. 3 and 4.
As shown in the figure, a mask 9 having a light-shielding layer 8 is brought into close contact with the coating 7a on the substrate 2, and ultraviolet rays are irradiated as shown by arrow B. As shown, the portion 7b irradiated with ultraviolet rays is hardened and left behind.

As described above, the coating 7a formed on the substrate 2 for various uses must be uniformly applied to a certain thickness.

For example, in the case of manufacturing color separation filters, if the thickness of the resin coating differs by 0.1μ, the half-value wavelength of the filter's spectral characteristics will differ by about 1 nm (nanometer).
The coating thickness must always remain constant.

In addition, for LSI photomasks, if the resist coating thickness differs by 0.05 micrometers, the dimensional accuracy of the resist will decrease by 0.02 to 0.04 micrometers (μ
rrL) Different.

In this way, a high level of quality is required for the coating on the substrate, but with the conventional coating spin coating device whose principle is shown in Figure 1,
Occurrence of uneven coating cannot be avoided.

For example, use a glass disk with a thickness of 0.5 mm and a diameter of 3 inches as the substrate 2, apply a vacuum of 60 cm H9 to the chuck table 1, and apply a photosensitive resin to a film thickness of 1.0 μ, iooor
When spin coating is performed under the conditions of 5 pm and 5 oz., coating unevenness occurs in the shape of the chuck table due to the difference in film thickness, as shown in FIG.

In the figure, reference numeral 11 indicates coating unevenness that occurs at the position corresponding to the O-ring 4 on the chuck table, and the difference in film thickness is 0.0.
It has reached 4μ.

Further, as shown in FIGS. 6A and 6B, a vacuum suction groove consisting of a concentric groove 12 and a radial groove 13 is formed on the top surface of the chuck base 1, centered around the vacuum suction hole 5, and a When the substrate 2 is mounted under the same conditions as described above and spin coating is performed, coating unevenness occurs in the shape shown in FIG. 6C.

In the figure, reference numeral 14 indicates coating unevenness that occurs along the shape of the vacuum suction grooves 12 and 13, and reference numeral 15 indicates coating unevenness that occurs along the dimensions of the chuck table 1.

Such chuck stand unevenness is thought to be caused by changes in substrate temperature due to vacuum suction chucking during spin coating and bending deformation of the substrate.

However, it is considered that the unevenness that occurs even when the substrate thickness is as large as 2 to 3 wR is influenced not only by bending deformation of the substrate but also by changes in substrate temperature due to chucking.

FIG. 7 shows the relationship between the vacuum suction pressure (vacuum pressure) of the chuck table 1 and the occurrence of coating unevenness.

As is clear from this figure, as the vacuum suction pressure increases, the coating unevenness also increases.

In addition, if the vacuum suction pressure is made weaker than 30crrLHg,
The fixation of the board becomes incomplete and the board falls off during rotation.

Therefore, in the conventional type of apparatus, even if an attempt is made to reduce the vacuum suction pressure in order to eliminate uneven coating, it is impossible to do so, and as a result, uneven coating cannot be removed.

This fact becomes more pronounced as the thickness of the substrate decreases.

In view of the above points, it is an object of the present invention to provide a coating rotary coating device that has a simple configuration and can eliminate coating unevenness.

This objective is furthered by providing a breathable porous layer on the chuck table surface.

Next, an embodiment of the present invention will be described with reference to FIG. 8 and subsequent figures.

According to the present invention, an air permeable porous layer 17 is provided on the upper surface of the chuck base 1, as shown in FIG. 8A.

This porous layer 17 has a disk shape, and as is clear from FIG. 8B, concentric vacuum suction grooves 12 and radial grooves 13 communicate with the vacuum suction holes 5 extending upward through the shaft portion 3. An annular protruding edge 1 on the outer periphery of the chuck stand 1 having on the upper surface
It is fixed to the upper surface of 8 with adhesive or the like.

The outer circumferential end 17a of this disc-shaped porous layer 17 is blocked from air permeability by adhesive or the like as necessary.

The material for the porous layer 17 is a sheet made by sintering powder such as polyethylene with a diameter of about 10 to 200 μm to a thickness of about 0.5 to 5 μm (for example, a sheet manufactured by Kaken Co., Ltd. Related filterane sheets [trade name]), quartz fiber filter paper, filter plates made by mixing asbestos, filter plates made by mixing paper with cellulose fibers and diatomaceous earth, glass fiber filter paper, and 4-fluorinated ethylene It is preferable to use a polyflon filter, membrane filter, glass filter, etc.

In any case, the porous layer 17 is generally 0.
A filtration filter having a thickness of 5 to 5 mm is used, and its pore diameter is preferably about 500 μm or less.

Chuck stand 1 with porous layer 17 provided on the top surface as described above
A film coating substrate 2 is placed on top as shown in FIG. 8C,
When a film is formed on the substrate 2 by applying a vacuum and rotating the chuck table 1 at high speed, coating unevenness 19 having a shape as shown in FIG. 8D occurs. This occurs only in the portion where the substrate 2 protrudes from the outer periphery of the table 1.

That is, the outer periphery 19a of the uneven coating 19 corresponds to the outer periphery of the substrate 2, and the inner periphery 19b thereof is located at a position corresponding to the outer periphery of the chuck plate 1.

In this way, the coating formed inside the inner circumferential edge 19b does not have uneven coating and a uniform coating can be obtained, so that only the inner portion thereof can be used for the product.

However, if the portion outside the inner peripheral edge 19b of the uneven coating 19 falls within the effective area of the substrate, as shown in FIG. 9A,
The outer diameter of the chuck stand 1 may be approximately the same as the outer diameter of the substrate 2.

In this way, the portion where the coating unevenness 19 occurs will be located outside the effective area of the substrate 2, as shown in FIG. 9B.

As described above, by interposing the porous layer 17, the vacuum acting on the substrate 2 becomes uniform without being affected by the dimensions, shapes, etc. of the suction grooves 12, 13, suction holes 5, etc. There is no need to apply slightly different forces to the substrate 2.

That is, the vacuum acts on the substrate 2 while being distributed over the entire surface of the porous layer 17, and since the entire lower surface of the substrate 2 is supported by the upper surface of the porous layer, local deformation of the substrate can be avoided.

Further, the porous layer also exhibits the effect of mitigating temperature changes throughout the substrate.

Therefore, according to the present invention, a uniform coating without uneven coating can be formed on the substrate.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a known spin coating device, Fig. 2 is a longitudinal cross-sectional view showing a film formed on the substrate, and Fig. 3 is an exposure process for the film formed as shown in Fig. 2. FIG. 4 is a diagram showing the state of the film obtained as a result of the process shown in FIG. 3, and FIG. 5 is a diagram showing the state of uneven coating of the film obtained by the rotary coating device of FIG. 1. FIG. 6A is a diagram showing another known rotary coating device, FIG. 6B is a plan view of the chuck plate of FIG. 6A, and FIG. 6C is a diagram showing the occurrence of uneven coating of the film obtained by the device of FIG. 6A. 7 is a graph showing the relationship between suction pressure and coating unevenness, FIG. 8A is a vertical sectional view showing the chuck plate of the rotary coating device according to the present invention, FIG. 8B is a plan view of FIG. 8A, and FIG. 8C is a graph showing the relationship between suction pressure and coating unevenness. Figure 8A is a diagram showing a state in which a substrate is applied to a chuck plate, Figure 8D is a diagram showing uneven coating that occurs in the coating obtained by the apparatus of Figure 8C, and Figure 9A is a diagram showing a state in which the chuck plate is enlarged in size. 8th case showing
FIG. 9B, which is similar to FIG. C, is a diagram showing uneven coating of the film obtained by the apparatus of FIG. 9A. 1... Chuck stand, 2... Film coating substrate, 3... Shaft, 5... Suction hole, 1
2.13... Suction groove, 17... Porous layer, 18... Annular protrusion, 19... Uneven coating.

Claims (1)

[Claims for Utility Model Registration] 1. A coating having a chuck stand that supports a coated substrate on its upper surface and holds the coated substrate by vacuum suction, and a rotation drive means for rotating the chuck stand around a vertical axis. 1. A rotary coating device, characterized in that the upper surface of a chuck table is formed by a porous layer. 2. The coating rotary coating apparatus according to claim 1, wherein the lateral dimension of the chuck table is substantially the same as the lateral dimension of the coating substrate supported thereon.