JPH1043665A - Spin coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a trouble such as exposure failure following deposition and adhesion of chemical liquid mist (resist mist, etc.) on the wafer surface by forming an exhaust outlet to discharge air containing the chemical liquid mist floating above a spin head in a wall face of a chemical liquid scattering preventive cup installed above the spin head. SOLUTION: A chemical liquid scattering preventive cup 3 is so installed in the surrounding of a spin head 7 which rotates at high speed on a vertical center axis of a spin coater 1 as to cover the surrounding of the spin head 7. An exhaust outlet 13 is formed in the side wall of the upper part of the cut 3 to such resist mist 6 floating above a wafer 5 through the exhaust outlet 13 and discharge the mist outside of the cut 3 through an exhaust pipe 15 and an exhaust tube 21. A cover 31 having a suction inlet 33 in the lower face and hung from the side wall of the cup 3 is formed and by the cover 31, resist flow scattered to the surrounding from the surface of the wafer 5 is prevented from entering directly the exhaust pipe 15 and air containing the resist mist 6 is sucked through the suction inlet 33 and discharged out of the exhaust pipe 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin coater used for resist coating on a wafer surface in a semiconductor device manufacturing process. In particular, the present invention relates to a spin coater that can solve a problem such as exposure failure caused by a chemical mist (such as a resist mist) dropping and adhering to a wafer surface.

[0002]

2. Description of the Related Art The prior art will be described using a resist spin coater for a semiconductor wafer as an example. FIG. 2 is a cross-sectional view illustrating the configuration of a conventional general spin coater used for resist coating on the surface of a semiconductor wafer and an outline of a coating process. The spin coater 1 'has a disk-shaped spin head 7 placed horizontally. The spin head 7 is rotated about its vertical center axis at a high speed (for example, 3000 rp) by a rotation shaft 9 extending downward from the center of the lower surface.
m). The wafer 5 is mounted (vacuum chucking or the like) on the spin head 7, and the wafer 5 also rotates together with the spin head 7.

[0005] Around the spin head 7, a chemical liquid scattering prevention cup 3 ′ is provided so as to cover the periphery of the spin head 7. The upper surface of the center of the cup 3 'is an opening 11. The diameter of the opening 11 is slightly smaller than the diameter of the spin head 7. The cup 3 ′ extends laterally from above the peripheral edge of the spin head 7 except for the opening 11, reaches the lower side of the spin head 7, and narrows inward. An exhaust pipe 21 is provided at a lower portion in the cup 3 ', and discharges air in the cup 3' downward. For this reason, in the cup 3 ′, air enters below through the opening 11, passes through the upper space 12 of the spin head 7, passes through the spin head side portion 17, the spin head lower portion 19, and passes through the exhaust pipe 21.
The flow of the air flowing into is formed.

[0004] Next, a description will be given of the resist coating step, generation and discharge of mist, and descent and adhesion of mist on the wafer surface in the conventional spin coater shown in FIG. In FIG. 2 (A), the chemical liquid scattering prevention cup 3 '
The resist 43 is supplied from the upper resist supply device 41 so as to flow down onto the surface of the wafer 5.

Next, in FIG. 2B, the resist spreads on the surface of the wafer 5 by the rotation of the spin head 7, and the resist film 4 is formed. At this time, the resist mist 6 scatters in the space 12 above the wafer 5. However, most of the resist mist 6 rides on the exhaust flow, flows from the spin head side portion 17 to the spin head lower portion 19, and is discharged from the exhaust pipe 21. In FIG. 2C, the formation of the resist film 4 on the surface of the wafer 5 is completed, and the rotation of the spin head 7 is stopped. At this time, the resist mist 6 remaining in the space 12 on the wafer 5
(Some bounced off the cup 3 ′), but are going to fall to and adhere to the surface of the resist film 4 on the wafer 5.

When the resist mist 12 drops and adheres (resist return), a part of the resist film 4 rises. Then, in the subsequent exposure step using a stepper or the like, an unexposed portion is generated because the exposure is refracted by the attached resist mist. This defect eventually becomes a defect in the semiconductor circuit (such as short-circuiting of wiring) after the resist removal, etching, or film forming process, and the semiconductor manufacturing yield is reduced.

As a countermeasure against the problem of resist mist adhesion, the following proposal is proposed in Japanese Patent Application Laid-Open No. Sho 59-120270. FIG. 3 shows an improved exhaust device of a spin coater proposed in JP-A-59-120270. FIG. 3A is a cross-sectional view of the device, and FIG. 3B is a diagram schematically showing an exhaust flow. According to the specification of the publication, the exhaust can be improved as follows. In FIG. 3, reference numeral 51 denotes a processing chamber, 52 denotes a spin head, 53 denotes a sample, and 54 denotes an exhaust port. In this spin coater, clean air is supplied from above the chamber 51 downward. Further, an inner pipe 55 is provided, a leak air opening 56 is provided, and a raised bottom straightening plate 57 is provided at the bottom of the chamber.

[0008] The inner tube 55 is a hollow structure having a bottom portion extending outward like a trumpet, and is fixed to the ceiling of the chamber 51 by a usual technique. The lower rectifying plate 57 may have a configuration in which the bottom of the chamber is raised. In any case, the height of the lower rectifying plate is lower than the height of the spin head, and the surface of the lower rectifying plate is formed substantially parallel to the surface of the spin head. The expanded portion at the bottom of the inner pipe 55 is configured to extend toward the exhaust port 54 almost in parallel with the surface of the lower rectifying plate 57. Providing such a rectifying plate 57 is effective in rectifying clean air. At the same time, leak air at atmospheric pressure is sent from the opening 56 to help straighten the clean air in the chamber 51.

With the configuration shown in FIG. 3A, the flow of clean air in the chamber 51 is as shown in a schematic sectional view of FIG. 3B. The result of an experiment using a cleaning gas obtained by adding a coloring gas to clean air is indicated by an arrow in FIG. The air coming down the inside of the inner tube 55 and hitting the sample forms an air flow parallel to the lower rectifier plate and the sample 53 on the lower rectifier plate 57 in cooperation with the atmospheric pressure leak air supplied from the opening 56. However, the resist blown off from the sample 53 by the parallel flow cannot return to the sample 53. Also, since the inner tube 55 extends outwardly from the sample 53 in a trumpet shape at the bottom, even if the resist from the sample hits the inner wall of the inner tube 55, the resist remains in the inner tube 55.
The air is swept downward by the clean air flowing downward through the inside of the device and is placed on the parallel flow above the lower rectifying plate 57, and is carried out from the exhaust port 54 to the outside.

Since a narrow space of about 5 mm is left between the bottom outer edge 55a of the inner tube and the inner wall of the chamber 51 as described above, the clean air flowing down from above the chamber 51 flows faster in this space. Thus, an air curtain is formed along the inner wall of the chamber 51, thereby sucking the parallel flow of clean air above the lower rectifying plate 57 and preventing the resist particles from adhering to the inner wall of the chamber. You.

[0011]

Problems to be Solved by the Invention
The spin coater No. 70 is useful for reducing the resist return as compared with the spin coater of FIG. However, the mist on the wafer has not yet been completely removed. The cause is disclosed in
In the spin coater of No. 120270, the exhaust at the peripheral portion of the wafer is good, but the exhaust above the wafer is insufficient.

The present invention relates to a spin coater used for coating a resist on a wafer surface in a semiconductor device manufacturing process, wherein trouble such as exposure failure due to a chemical mist (resist mist or the like) falling or adhering to the wafer surface. It is an object of the present invention to provide a spin coater capable of solving the problem.

[0013]

In order to solve the above-mentioned problems, a spin coater according to the present invention comprises a spin head which places a sample on an upper surface thereof and rotates at a high speed around a vertical axis, and prevents a chemical solution covering the spin head from scattering. A spin coater comprising: a cup; and an exhaust port for discharging air containing a chemical mist floating on the spin head is provided on a wall surface of the chemical splash prevention cup above the spin head.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific description will be given with reference to the drawings. FIG. 1 is a diagram showing a configuration around a spin head and a chemical liquid scattering prevention cup of a spin coater according to an embodiment of the present invention. (A) is a side cross-sectional view of the whole, (B) is a perspective view of the chemical liquid scattering prevention cup, (C) is a bottom view of the upper surface of the chemical liquid scattering prevention cup viewed from below, and (D) shows details of the exhaust port. It is a perspective view.

The overall structure of the spin coater of this embodiment has many parts in common with the conventional spin coater of FIG. 2, but will be described below. The spin coater 1 has a disk-shaped spin head 7 placed horizontally. The spin head 7 is driven to rotate around the vertical center axis at high speed by a rotation shaft 9 extending downward from the center of the lower surface. The wafer 5 is placed on the spin head 7 (chucking).
The wafer 5 also rotates together with the spin head 7.

A chemical liquid scattering prevention cup 3 is provided around the spin head 7 so as to cover the periphery of the spin head 7. The upper surface of the center of the cup 3 is an opening 11. The diameter of the opening 11 is slightly smaller than the diameter of the spin head 7. The cup 3 extends laterally from above the peripheral edge of the spin head 7 except for the opening 11, reaches the lower side of the spin head 7, and narrows inward. An exhaust pipe 21 is provided at a lower portion in the cup 3 to discharge air in the cup 3 downward. For this reason, cup 3
Inside, basically, air goes down through the opening 11,
A flow of air flowing through the upper space 12 of the spin head 7, the spin head side part 17, the spin head lower part 19, and the exhaust pipe 21 is formed.

The feature of the spin coater of this embodiment is that an exhaust port 13 is provided on the upper side wall of the cup 3. The resist mist 6 floating on the wafer 4 is sucked from the exhaust port 13, sent to the exhaust pipe 21 through the exhaust pipe 15, and discharged out of the cup 3. Exhaust pipe 1
5 extends downward along the outer surface of the cup 3 as shown in FIG.

The details of the exhaust port will be described with reference to FIG. The exhaust port 13 has a cover 31 which hangs from a side wall of the cup and has a suction port 33 on the lower surface thereof. The cover 31 covers the front surface of the opening 35 of the exhaust pipe 15 so that the resist flow blown from the wafer 5 to the periphery by the centrifugal force does not directly enter the exhaust pipe 15. On the other hand, the air containing the resist mist is sucked from the suction port 33 opened on the lower surface of the cover 31 and discharged through the exhaust pipe 15.

It is preferable that a plurality of such exhaust ports 13 are provided in the upper portion of the side wall of the cup 3 for rotating objects in order to improve the uniformity of exhaust. In this embodiment, FIG.
As shown in (C), eight exhaust ports 13 are evenly arranged on the circumference.

In the spin coater according to the present embodiment, the resist mist 6 floating on the wafer 5 after the formation of the resist film 4 on the wafer 5 passes through the exhaust port 13 provided on the side wall of the cup above the wafer 5. It is removed by suction. Therefore, return (fall / adhesion) of the resist mist 6 onto the resist film 4 can be prevented. In particular, the wafer 5
In the outer peripheral region, the exhaust flow toward the exhaust port 13 has an upward velocity component, so that the descent of the resist mist 6 can be suppressed.

[0021]

As is apparent from the above description, in the spin coater of the present invention, the chemical mist (resist mist, etc.) falls and adheres to the wafer surface during the resist coating on the wafer surface in the semiconductor device manufacturing process. Troubles such as exposure failures caused by the above can be solved. Therefore, the yield of semiconductor device products and the like is improved.

[Brief description of the drawings]

FIG. 1 is a view showing a configuration around a spin head and a chemical liquid scattering prevention cup of a spin coater according to an embodiment of the present invention. (A) is a side cross-sectional view of the whole, (B) is a perspective view of the chemical liquid scattering prevention cup, (C) is a bottom view of the upper surface of the chemical liquid scattering prevention cup viewed from below, and (D) shows details of the exhaust port. It is a perspective view.

FIG. 2 is a cross-sectional view illustrating the configuration of a conventional general spin coater used for resist coating on the surface of a semiconductor wafer and an outline of a coating process.

FIG. 3 shows an improved exhaust device of a spin coater proposed in JP-A-59-120270. (A) is a sectional view of the device, and (B) is a diagram schematically showing an exhaust flow.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spin coater, 3 ... Chemical liquid scattering prevention cup, 4 ... Resist film, 5 ... Wafer, 7 ... Spin head, 9 ... Rotating shaft, 11 ... Top opening, 12 ... Top space, 13 ... Exhaust port,
15 exhaust pipe, 17 side part, 19 lower part, 21 exhaust pipe, 31 cover, 33 suction port, 35 pipe opening, 41 resist supply pipe, 43 resist

Claims (4)

[Claims] 1. A spin coater comprising: a spin head having a sample placed on an upper surface thereof and rotating at a high speed around a vertical axis; and a chemical scattering prevention cup covering the periphery of the spin head; floating on the spin head. A spin coater characterized in that an exhaust port for discharging air containing a chemical mist is provided on a wall surface of a chemical liquid scattering prevention cup above a spin head. 2. An exhaust pipe extending downward from an outer periphery of the spin head to an outer periphery of the cup from the exhaust port and joining to a lower side of the spin head of the exhaust passage is provided. The spin coater according to claim 1, wherein: 3. The spin coater according to claim 1, wherein a plurality of said exhaust ports are provided for a rotating object. 4. The spin coater according to claim 1, wherein said exhaust port has a cover hanging down from a side wall of said cup and having a suction port formed on a lower surface thereof.