JPH0613305A - Rotational coater - Google Patents

Abstract

PURPOSE:To prevent the re-adhesion of resist during coating so as to improve the quality and film-thickness uniformity of resist thin film forming on a wafer by keeping air flow in a spin cup to be uniform. CONSTITUTION:The title is provided with a spin chuck 12 inside a spin cup 11, and a fan 31 rotating along an internal wall 18 of the spin cup 11 is prepared between the wall 18 of the spin cup 11 and a substrate (wafer 51) mounted on the spin chuck 12 therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a lithographic process in the manufacture of semiconductor devices.
The present invention relates to a spin coating device for coating OG (Spin on glass) or the like on a wafer.

[0002]

2. Description of the Related Art Spin coating is one of the conventional resist coating techniques. In this spin coating method, the spin coating device, resist approximately dropwise 1cm ³ ~10cm ³ about the surface of the semiconductor substrate (hereinafter referred to as wafer), was then rotating the wafer at a rotation speed of about 1000Rpm～5000rpm, wafer A uniform resist thin film is formed on the surface.

The spin coater will be described with reference to the schematic sectional view of FIG. As shown in the figure, a spin chuck 12 is provided inside the spin cup 11. A motor (not shown) is connected to the spin chuck 12 via a rotary shaft 13. An exhaust port 14 and a drain port 15 are provided on the bottom side of the spin cup 11. An exhaust pipe 16 is connected to the exhaust port 15,
A drain pipe 17 is connected to the drain port 15. A resist solution supply nozzle (not shown) is provided substantially above the center of the spin chuck 12. In the spin coater 3 having the above structure, for example, an SOG thin film can be formed in addition to the resist thin film.

Next, a method of forming a resist thin film on the upper surface of the wafer 51 using the above-mentioned spin coater 3 will be described.
First, the wafer 51 is fixed on the upper surface of the spin chuck 12. To rotate the spin chuck 12 in a predetermined direction by a subsequent motor, the resist solution supply nozzle (not shown) the resist solution is added dropwise about 1cm ³ ~10cm ³ a more. Then, the wafer 51 is immediately rotated at a predetermined rotation speed (for example, 1000 rpm to 5000 rpm) to spread the resist solution dropped on the surface of the wafer 51 to form a resist thin film (not shown) having a uniform film thickness. At this time, the inside of the spin cup 11 is exhausted from the exhaust port 14. Therefore, the airflow inside the spin cup 11 flows as indicated by an arrow, for example. Further, the resist liquid shaken off by the rotation of the spin chuck 12 is discharged from the drain port 15.

[0005]

However, in the structure of the above-mentioned spin coating apparatus, as shown in FIG. 8, when the exhaust amount per unit time is small, the wafer 51 is dropped and dropped.
A part of the resist liquid 61 spread on the top is the resist droplet 6
It becomes 2 and scatters. The resist droplets 62 collide with the inner side wall 18 of the spin cup 11 and become mist-like or flaky. A part 63 of the mist or flaky resist droplets is carried on the wafer 51 by the air flow generated by the rotation of the wafer 51, and reattaches to the resist thin film formed on the wafer 51. Therefore, the quality of the resist thin film deteriorates. Further, as the diameter of the wafer 51 increases, the peripheral speed of the wafer 51 increases, so that the number of redeposited resists increases.

Further, the exhaust port 14 is provided in the spin coating device 3.
Since only one place is formed, the spin cup 11
In the interior of the fuel cell, a region where the exhaust amount is large and a region where the exhaust amount is small locally occur. Therefore, in order to prevent the re-adhesion of the resist, it is necessary to secure an exhaust amount over the entire area of the spin cup 11 so that the resist does not re-adhere. However,
When the exhaust amount is increased, the film thickness uniformity of the resist thin film (not shown) formed on the wafer 51 deteriorates.

That is, as shown in FIG. 9, the quality of the resist thin film, which is shown by the relationship between the number of redeposition of resist depending on the exhaust flow rate and the film thickness uniformity of the resist thin film, is the number of redeposition of resist as the exhaust flow rate increases Although it decreases, the film thickness uniformity of the resist thin film deteriorates. Further, if the exhaust flow rate is reduced, the number of redeposited resists increases and the film thickness uniformity of the resist thin film improves. In this way, the relationship between the number of redeposited resists by the flow rate of exhaust gas and the film thickness uniformity of the resist thin film is in a contradictory relationship. Therefore, there is a limit to increasing the displacement. In FIG. 9, the left vertical axis shows the number of redeposited resists, and the right vertical axis shows the standard deviation of the film thickness uniformity of the resist thin film. The horizontal axis represents the exhaust gas flow rate.

It is an object of the present invention to provide a spin coating apparatus which forms a thin film excellent in film thickness uniformity by reducing redeposition of a coating solution such as a resist solution or an SOG solution.

[0009]

The present invention has been made to achieve the above object. That is, in a spin coating apparatus having a spin chuck inside a spin cup, a fan that rotates along the inner wall of the spin cup is provided between the inner wall of the spin cup and a substrate attached to the spin chuck. It is provided.

[0010]

In the spin coater having the above structure, the exhaust capacity is increased by providing the fan rotating along the inner wall of the spin cup between the inner wall of the spin cup and the substrate attached to the spin chuck. Instead, the pumping speed inside the spin cup is made uniform. Therefore, since the region where the exhaust speed is low is eliminated, the coating liquid scattered from the substrate is discharged to the outside of the spin cup through the fan.
Therefore, the redeposition of the coating liquid on the substrate is eliminated. Further, the film thickness uniformity of the resist thin film formed on the wafer is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the schematic sectional view of FIG. The same components as those of the spin coater (3) described in the above-mentioned conventional technique are designated by the same reference numerals. As shown in the figure, a spin chuck 12 is provided inside the spin cup 11. The spin chuck 12 is attached to a motor (not shown) via a rotary shaft 13. The spin chuck 12 has a structure that moves up and down together with the rotary shaft 13 and the motor.

An exhaust port 14 and a drain port 15 are provided on the bottom side of the spin cup 11. Exhaust port 14
An exhaust pipe 16 is connected to, and a drain pipe 17 is connected to the drain port 15. A resist supply nozzle (not shown) is provided substantially above the center of the spin chuck 12.

A fan 31 that rotates along the inner wall 18 of the spin cup 11 is provided between the inner wall 18 of the spin cup 11 and the wafer 51 attached to the spin chuck 12.

Next, the structure of the fan 31 will be described in detail with reference to FIG. 1 and the sectional view taken along the line AA in FIG. The fan 31 includes a plurality of fins 32, an upper support portion 33 that supports the upper side of each fin 32, a lower support portion 34 that supports the lower side of each fin 32, a lower support portion 34, and a lower support portion 34. And consists of. Each fin 32
Is formed of, for example, a thin flat plate. The fins 32 are attached at equal intervals along the radial direction of the spin chuck 12. The number of fins 32 is
It is appropriately selected depending on the diameter of the fan 31, the exhaust capacity, and the like.

The fan 31 has a fan chuck portion 35.
It is attached to the fan rotation shaft 36 via. The fan rotation shaft 36 is rotatably attached to the outside of the rotation shaft 13 and is connected to a fan motor (not shown) via a transmission device (not shown). .
Further, the spin cup 11 and the fan 31 are structured to move up and down in conjunction with each other. The spin coater 1 is configured as described above.

Next, the operation of coating the resist on the wafer 51 using the above-mentioned spin coating apparatus 1 will be described with reference to FIG. First, the spin chuck 12 is moved upward, and the spin cup 11 and the fan 31 are moved downward. Then, the upper surface of the spin chuck 12 is exposed above the spin cup 11, and the wafer 5 is placed on the spin chuck 12.
Fix 1 After that, the spin chuck 12 is moved downward and the spin cup 11 and the fan 31 are moved upward so that the spin chuck 12 is housed inside the spin cup 11.

Next, the motor is driven at a low speed to rotate the spin chuck 12 in a fixed direction at, for example, 300 rpm. At the same time, a fan motor (not shown) is driven to rotate the fan 31 at 1000 rpm in a direction opposite to the rotation direction of the spin chuck 12, for example.

Subsequently, a resist solution supply nozzle (not shown)
The resist solution is supplied to the upper surface of the wafer 51 by, for example, about 7 cm ³ . The supply amount of the resist solution is appropriately selected depending on the viscosity of the resist solution, the diameter of the wafer 51, the film thickness of the resist thin film to be formed, and the like.

Immediately after dropping the resist solution, the spin chuck 12 is rotated at a high speed, for example, at 3500 rpm. Then, the resist solution is spread over the entire upper surface of the wafer 51, and excess resist solution on the wafer 51 is scattered in the circumferential direction of the wafer 51 to form a resist thin film (not shown) having a predetermined thickness on the upper surface of the wafer 51. To form.

After the formation of the resist thin film is completed, the rotation of the spin chuck 12 is stopped. Then, the rotation of the fan 31 is stopped. And spin chuck 12 and fan 31
After the and are stopped, the upper surface of the spin chuck 12 is moved above the spin cup 11 and the wafer 51 is removed from the spin chuck 12.

The rotation speed of the fan 31 is not limited to the above rotation speed, and the diameter of the wafer 51, the rotation speed of the wafer 51, the viscosity of the resist solution, the dropping amount of the resist solution, and the exhaust in the spin cup 11 are performed. It is appropriately selected depending on the amount and the like. The exhaust speed of the airflow discharged from between the fins 32 is determined by the rotation speed of the fan 31 together with the flow rate discharged from the exhaust port 14.

Next, the air flow inside the spin cup 11 will be described with reference to FIG. 3 in the case where the fan 31 is rotating in the arrow A direction and the wafer 51 is rotating in the arrow A direction. Since the atmosphere inside the spin cup 11 is forcibly exhausted from the exhaust port 14, the atmosphere inside the fan 31 is exhausted in the arrow C direction. At this time, the fan 31
, The airflow discharged from between the fins 32 has a substantially constant velocity. Therefore, there is no unevenness in the exhaust speed inside the fan 31.

As a result, the resist droplets 62 scattered from the wafer 51 are discharged from the inside of the fan 31 to the outside along the direction of the arrow D along with the discharged air flow, so that the resist thin film formed on the wafer 51. Do not redeposit on.
Further, the formed resist thin film has excellent film thickness uniformity. Particularly, the film thickness uniformity of the resist thin film formed on the large diameter wafer is remarkably improved.

If the fan 31 is rotated at too high a speed, the exhaust effect is greatly reduced. Therefore, the rotation speed of the fan 31 is
The rotation speed at which the exhaust amount inside the spin cup 11 is sufficiently obtained is appropriately set.

Next, a second embodiment will be described with reference to the schematic sectional view of FIG. 4 and the sectional view taken along the line BB in FIG. 4 shown in FIG. As shown in the figure, the spin coating device 2 includes a fan 41
Except for the fan (31) described in the first embodiment.
It has a structure similar to that of. That is, the fan 41
Is provided between the inner wall 18 of the spin cup 11 and the wafer 51 attached to the spin chuck 12. Here, detailed description of the structure of the spin coating device 2 other than the fan 41 is omitted.

The fan 41 includes a plurality of fins 42,
An upper support portion 43 that supports the upper side of each fin 42, a lower support portion 44 that supports the lower side of each fin 42, a lower support portion 44, and a lower support portion 44. Each fin 42 is formed in a wing shape, for example. Each fin 42
Are attached to the fan 41 at an equal interval while being inclined in the direction in which the air flow flows from the inside to the outside when the fan 41 rotates. That is, the fin 42 is attached with the inner side of the fan 41 tilted toward the rotation direction side. Therefore, the exhaust speed of the airflow discharged from between the fins 42 is
It is determined by the number of the fins 42, the inclination angle θ of each fin 42 (the angle formed by the radial direction of the spin chuck 12), the rotation speed of the fan 41, and the like, as well as the exhaust capacity discharged from the exhaust port 14.

The fan 41 has a fan chuck portion 45.
It is attached to the fan rotation shaft 46 via. The fan rotation shaft 46 is rotatably attached to the outside of the rotation shaft 13 that rotates the spin chuck 12, and is connected to a fan motor (not shown) via a transmission device (not shown). )It is connected to the. Also, the spin cup 11
And the fan 41 are interlocked with each other so that they can be raised and lowered. The spin coater 2 is configured as described above.

Next, the air flow inside the spin cup 11 when the fan 41 is provided will be described with reference to FIG.
As shown in FIG. 6, a case where the fan 41 is rotating in the arrow direction and the wafer 51 is rotating in the arrow direction will be described. Since the atmosphere inside the spin cup 11 is forcibly exhausted from the exhaust port 14, the atmosphere inside the fan 41 is exhausted in the arrow direction. At this time, the airflow smoothly flows from the inner side to the outer side of the fan 41 because the fins 42 are attached so as to be inclined by the inclination angle θ. Further, since the fan 41 is rotating, the airflow discharged from between the fins 42 has a substantially constant velocity. Therefore,
The exhaust speed of the airflow exhausted from the inside of the spin cup 11 is more uniform than that of the fan (31) described in the first embodiment. As a result, the unevenness of the exhaust speed is eliminated inside the spin cup 11.

As a result, the resist droplets 62 scattered from the wafer 51 are discharged from the inside of the fan 41 to the outside along the direction of the arrow with the discharged air flow, so that the resist thin film formed on the wafer 51. Do not redeposit on.
Further, the formed resist thin film has excellent film thickness uniformity. Particularly, the film thickness uniformity of the resist thin film formed on the large diameter wafer is remarkably improved.

In the first and second embodiments, the case of applying a resist has been described, but the thin film formed by the application is not limited to the resist thin film. For example, S
It is also possible to form a thin film made of a material such as an OG thin film or a methyl methacrylate resin thin film.

[0031]

As described above, according to the present invention,
A fan that rotates along the inner wall of the spin cup is provided between the inner wall of the spin cup and the substrate attached to the spin chuck, so that the exhaust speed inside the spin cup is uniform without increasing the exhaust capacity. Be converted. Therefore, since the region where the exhaust speed is low is eliminated, the coating liquid scattered from the substrate is discharged to the outside of the spin cup through the fan. Therefore, the resist liquid scattered on the substrate does not redeposit, so that the quality of the formed resist thin film can be improved. Further, it is possible to improve the uniformity of the formed resist thin film.

[Brief description of drawings]

FIG. 1 is a schematic configuration sectional view of a first embodiment.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is an explanatory diagram of airflow in the first embodiment.

FIG. 4 is a schematic configuration sectional view of a second embodiment.

5 is a sectional view taken along line BB in FIG.

FIG. 6 is an explanatory diagram of airflow in the second embodiment.

FIG. 7 is a schematic configuration sectional view of a conventional example.

FIG. 8 is an explanatory diagram of a problem.

FIG. 9 is an explanatory diagram of the quality of a resist thin film depending on the exhaust flow rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 spin coater 2 spin coater 11 spin cup 12 spin chuck 18 inner wall of spin cup 31 fan 41 fan 51 wafer

Claims (1)

[Claims] 1. A spin coating apparatus having a spin chuck inside a spin cup, wherein the spin cup is rotated along the inner wall of the spin cup between the inner wall of the spin cup and a substrate attached to the spin chuck. A spin coating device, which is provided with a fan.