JPH0777635B2 - Spin coating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention forms a thin film of photoresist, for example, on the surface of an optical disk, a semiconductor wafer, or the like, or forms a coating film of a magnetic paint on a magnetic disk while rotating the same. The present invention relates to a spin coating apparatus suitable for achieving a uniform coating film by forming a flow of air along the wafer surface which is sometimes uniform in the circumferential direction of the wafer, for example. It is a thing.

[Conventional technology]

As an example of a conventional spin coating apparatus, a resist apparatus used for manufacturing a semiconductor has a wafer 21 as an object to be coated, which is attracted and fixed on a spinner 23 rotated by a motor 22, as shown in FIG. After the resist solution 25 is dripped and supplied from the nozzle 24 installed above the wafer 21, the spinner 23 is rotated to uniformly distribute the resist solution 25 on the surface of the wafer 21 by the effect of centrifugal force. After being expanded and dried, a resist film is formed.

When the spinner 23 rotates in the above process, most of the resist solution 25 dripped and supplied from the nozzle 24 is the wafer.
After being scattered from the outer periphery of 21 and vaporizing the liquid particles or the solvent of the resist liquid, the liquid particles float as solid particles in the resist coating apparatus, or adhere to the wall surface or bounce on the wall surface. When the particles due to the rebound adhere to the surface of the wafer 21 again, the resist film thickness becomes non-uniform, and the adhered solid particles cause a product defect like foreign matter.

Therefore, generally, clean air in the manufacturing environment is sucked into the apparatus from the upper surface of the upper cup 26 of the coating apparatus, and an exhaust pipe installed at one or more locations on the circumference of the lower cup 27 located below the spinner 23. Exhaust by an exhaust pump 29 through 28,
By this air flow, the particles scattered from the outer periphery of the rotating wafer 21 are removed.

Further, as an example of making the air flow in the coating apparatus uniform in the circumferential direction of the wafer, it is described in JP-A-59-90928, which is eccentric to the wafer 21 as shown in FIG. It is known that a current plate 30 is attached on the circumference.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, in the case of using the resist device, the effect of removing particles scattered from the outer periphery of the wafer can be improved by increasing the exhaust amount. However, by increasing the exhaust amount, a large amount of air is passed through the coating device. This affects the drying rate of the resist solution, and therefore is not suitable for the spin coating method that controls the film thickness of the resist coating film formed on the wafer surface by the viscosity of the resist solution and the rotation speed of the spinner. It will be appropriate. Further, in order to form a uniform coating film, it is necessary not to disturb the flow of air in the coating apparatus. For this reason, even when the wafer is rotated, the air exhausted in the wafer circumferential direction is required. Although it is necessary to make the flow uniform, these measures have not been taken in the above-mentioned prior art.

On the other hand, also in the technique disclosed in Japanese Patent Laid-Open No. 59-90928, the amount of air sucked and discharged from the exhaust pipe depends on the difference in the flow passage area, that is, the difference in the flow passage resistance causes the air flow to move around the wafer. Although it is intended to make uniform in the direction, the flow path resistance is not simply proportional to the flow path area,
It also largely depends on the positional relationship with the exhaust pipe, and sufficient consideration has not been given to the movement of air flowing along the wafer surface. When the wafer further rotates, the air in the vicinity of the wafer is dragged by viscous action and rotates in the same direction as the wafer. However, in the above-mentioned conventional technique, consideration is given to this dynamic state, that is, in the rotation direction of the wafer. Since sufficient consideration is not given to this, a uniform flow cannot be obtained in the wafer circumferential direction.

An object of the present invention is to provide a spin coating apparatus capable of forming a uniform air flow along the wafer surface in the circumferential direction of the wafer and making the film thickness of the coating film formed on the wafer surface uniform. It is to be.

[Means for solving problems]

As a means for solving the above problems, the spin coating apparatus of the present invention comprises a spinner (3) for adsorbing and rotating an object to be coated (1) and a nozzle for providing a coating liquid on the object to be coated (1). (24), an upper cup (6) and a lower cup (7) that surround the spinner (3) and face each other, and an intake port that is provided substantially in the center of the upper cup (6) and through which a nozzle (24) is inserted. A spin coating device comprising at least one exhaust pipe (8) opening at the outer periphery of the inner surface of a lower cup (7) below the object to be coated (1), wherein the inner surface of the lower cup (7) extends along the outer periphery. At least one exhaust passage (10) communicating with each exhaust pipe (8) is formed, and the cross-sectional area of each exhaust passage (10) that guides air to each exhaust pipe (8) is determined by It has a configuration in which it is increased in the circumferential direction toward the position of the pipe (8).

[Action]

According to the above configuration, when the object to be coated is a wafer, the air flowing into the coating apparatus flows out to the outer peripheral portion along the surface of the wafer, but as the wafer rotates, the air in the vicinity of the wafer becomes viscous. The air that is dragged by and flows out from the outer periphery of the wafer has a swirling component and rotates in the same direction as the wafer. Therefore, the air flowing out to the outer peripheral portion of the wafer along the wafer surface can flow into the exhaust passage under the same condition at any position in the circumferential direction. That is, the air flowing along the surface of the wafer becomes uniform in the circumferential direction of the wafer, so that the air flow in the coating apparatus becomes stable without any turbulence, and the resist formed on the wafer surface is formed. The film thickness is also made uniform.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the air that has flowed into the coating cup from the air suction port that is provided substantially in the center of the upper surface of the upper cup 6 and that passes through the nozzle 24 is exhausted through the exhaust passage 10 to the exhaust pipe 8.
In this case, the exhaust flow path 10 is formed on the outer periphery of the inner surface of the lower cup 7 on the lower side of the wafer (object to be coated) 1, and gradually expands along the outer periphery of the wafer 1 to form the exhaust pipe 8. At the position, the exhaust passage 10 is configured such that the cross-sectional area of the exhaust passage 10 becomes the largest. By forming the exhaust flow path 10 in this manner, the air flow along the wafer 1 can flow from the outer peripheral portion of the wafer 1 to the exhaust flow path 10 under the same conditions at any position in the circumferential direction. Become. That is, since the flow passage cross-sectional area is gradually increased in the circumferential direction by the amount of the air flowing out from the outer peripheral portion of the wafer 1, the air flowing out to the outer peripheral portion of the wafer 1 at a certain circumferential position is moved in the circumferential direction. The flow of air flowing out to the outer periphery of the wafer 1 at the positions adjacent to each other can flow out without being obstructed.

FIG. 2 shows a cross-sectional area diagram in the OB direction of FIG.
The cross-sectional area A ₁ of the air passage 10 is small in value proportional to the angle in the circumferential direction. This is because only the amount of air flowing out from the surface of the wafer 1 between O-D direction and O-B direction in FIG.
This is because it suffices to flow the gas in the exhaust passage 10 in the B direction. If the cross-sectional area of the exhaust passage 10 is increased linearly in proportion to the angle in the circumferential direction, the uniformity of the amount of air flowing from the surface of the wafer 1 into the exhaust passage 10 in the circumferential direction of the wafer 1 is secured. To be done. In order to further stabilize the flow, the direction in which the cross-sectional area of the exhaust passage 10 increases should be made coincident with the rotation direction 11 of the wafer 1.

Similar to FIG. 2, FIG. 3 shows a sectional view taken along the line OC of FIG. This is a position where the angle in the circumferential direction is further increased as compared with the case of FIG. 2, and the cross-sectional area A ₂ of the exhaust passage 10 in the O-C direction is larger than A ₁ . The rate of increase of this cross-sectional area is, of course, proportional to the angle in the circumferential direction.

FIG. 4 shows a sectional view in the OD direction when the circumferential angle is further increased as compared with FIG. 3, and this position is the position where the exhaust pipe 8 is installed. The cross-sectional area A ₃ of the exhaust passage 10 in the O-D cross section has the largest value in the exhaust passage 10 in the circumferential direction. Further, by making the cross-sectional area A ₃ equal to the cross-sectional area A of the exhaust pipe 8 shown in FIG. 1, the flow uniformly along the surface of the wafer 1 in the circumferential direction and the flow gathered over the entire circumferential direction. It is stably discharged from the coating apparatus through the exhaust pipe 8 without being accelerated or decelerated at the inlet of the exhaust pipe 8.

As can be seen from the above description, the cross-sectional area of the exhaust passage 10 is formed so as to increase along the outer periphery of the wafer 1 and linearly in proportion to the amount of increase in the angle in the circumferential direction. The air flowing out to the outer circumference of the wafer along the surface of No. 1 has the same exhaust flow path at any position in the circumferential direction.
Can flow into within 10. Further, as the wafer 1 rotates, the air near the wafer is dragged by viscous action and rotates in the same direction as the wafer 1. By making the air flow along the wafer surface uniform in the circumferential direction of the wafer 1 in this way, the air flow in the coating apparatus becomes stable, and the resist film thickness formed on the surface of the wafer 1 becomes stable. Can be made uniform.

5 to 8 show another embodiment of the present invention. FIG. 5 shows an example in which the exhaust flow path 10 is configured similarly to the case of FIG. 1, but in the case of this embodiment, two exhaust pipes 8 are installed in the circumferential direction. The cross-sectional area of the exhaust passage 10 is
Similar to the case of FIG. 1, the wafer is increased to the position of the exhaust pipe 8 in the same direction as the rotation direction 11 of the wafer 1 in proportion to the angle in the circumferential direction. The cross-sectional area is made equal to the cross-sectional area of the exhaust pipe 8. Also in the case of this embodiment, the same effect as that of the embodiment of FIG. 1 can be obtained. Further, when the exhaust pipes are installed at three or more places, the exhaust flow path 10 may be similarly determined.

In the embodiment shown in FIG. 6, the flow is sucked from both sides toward the two exhaust pipes 8. According to this embodiment, when the amount of air passing through the coating apparatus is large and the influence of the rotation of the wafer 1 is small, the resist film thickness can be made uniform. Also in this case, the cross-sectional area of the exhaust passage 10 is proportional to the angle in the circumferential direction.

The case where the upper cup 6 and the lower cup 7 are composed of curved lines has been described above, but it is an embodiment showing that the exhaust passage 10 may be composed of a rectangle as shown in FIG. . Also in this case, the cross-sectional area of the exhaust passage 10 is increased in proportion to the angle in the circumferential direction and is maximized at the position of the exhaust pipe 8.

FIG. 8 shows the case where the exhaust passage 10 is present at the tangential position on the outer periphery of the wafer 1. Even in this embodiment, the cross-sectional area of the exhaust passage 10 can be increased in the circumferential direction. Good.

〔The invention's effect〕

As described above, according to the present invention, the exhaust passage is formed along the outer periphery of the object to be coated, and the cross-sectional area of the exhaust passage is formed so as to gradually increase in the circumferential direction toward the position of the exhaust pipe. The air flow along the surface of the object to be coated can flow into the exhaust flow path under the same conditions at any position in the circumferential direction, whereby air that is uniform and undisturbed in the circumferential direction of the object to be coated. Therefore, the coating film formed on the surface of the object to be coated can be made uniform with no film thickness distribution.

[Brief description of drawings]

FIG. 1 is a plan view showing an exhaust passage of a spin coating apparatus according to an embodiment of the present invention, and FIGS. 2, 3, and 4 are OB, OC, and C shown in FIG. 1, respectively. Sectional views in the direction of O-D, FIGS. 5 and 6 are plan views showing an exhaust passage of another embodiment of the present invention when the exhaust pipe is at two places, and FIG. 7 is a short exhaust passage. FIG. 8 is a cross-sectional view showing another embodiment of the present invention when it is configured in a shape, and FIG. 8 is a schematic view showing another embodiment of the present invention when the exhaust passage is arranged at the tangent position of the object to be coated. FIG. 9 is a sectional view of a conventional spin coating apparatus, and FIG. 10 is a side sectional view showing a known example of a spin coating apparatus equipped with a current plate. 1 ... Wafer, 22 ... Motor, 3 ... Spinner, 24 ... Nozzle, 25 ... Resist plate, 6 ... Upper cup, 7 ... Lower cup, 8 ... Exhaust pipe, 29 ... Exhaust pump, 10 ...... exhaust passage, the cross-sectional area of 11 ...... rotational direction of the _{wafer, a 1, a 2, a} 3 ...... exhaust passage.

Claims (4)

[Claims] 1. A spinner (3) for adsorbing and rotating an object to be coated (1), a nozzle (24) for supplying a coating liquid onto the object to be coated (1), and a spinner (3) surrounding the nozzle. An upper cup (6) and a lower cup (7) that face each other, an intake port that is provided substantially in the center of the upper cup (6) and through which the nozzle (24) is inserted, and a lower side of the coated object (1). A spin coating apparatus having at least one exhaust pipe (8) opening on the outer circumference of the inner surface of the lower cup (7), the exhaust pipes (8) on the inner surface of the lower cup (7) along the outer circumference.
At least one exhaust passage (10) communicating with the exhaust pipe (8) is formed, and the cross-sectional area of each exhaust passage (10) that guides air to each exhaust pipe (8) is set to the position of each exhaust pipe (8). The spin coating device is characterized by increasing the number in the circumferential direction. 2. A cross-sectional area (10) of each exhaust passage is increased in proportion to an increase in a circumferential angle from the vicinity of each exhaust pipe (8). The spin coater according to claim 1. 3. The cross-sectional area (10) of each exhaust passage is increased in the same direction as the rotation method of the object (1) to be coated, according to claim 1. Spin coating device. 4. A cross-sectional area (10) of each exhaust passage is provided at each exhaust pipe (8) at each exhaust pipe (8).
2. The spin coating apparatus according to claim 1, wherein the spin coating apparatus has a sectional area substantially equal to that of the spin coating apparatus.