JPH0897118A - Method for applying resist - Google Patents

Abstract

PURPOSE: To apply resist without any application irregularity even if the amount of discharged resist is small by discharging resist while moving a nozzle from a periphery of a wafer during rotation toward a center. CONSTITUTION: A wafer 2 is subjected to vacuum suction to a spin chuck 1 of a resist application device and the spin chuck 1 is speedily rotated. The tip of a nozzle 3 is located at approximately 5mm at the upper portion of the periphery of the wafer 2 in advance. Then, resist is discharged at 1cc/sec while moving the nozzle 3 toward the center of the wafer 2. In two seconds after the nozzle 3 starts moving, the nozzle 3 moves by approximately 80mm and reaches the center of the wafer 2. The amount of discharge during this period is approximately 2cc. Then, the comparison of the film thicknesses between the center and peripheral parts of the wafer 2 revealed that a uniformity which is equal to the conventional level can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist coating method in a semiconductor device manufacturing process, and more particularly to a resist coating method which suppresses resist coating unevenness due to spin coating and reduces the amount of resist used.

[0002]

2. Description of the Related Art Generally, in a manufacturing process of a semiconductor device such as an LSI, a photolithography process is repeatedly performed to pattern a resist pattern such as fine wiring. In order to prevent the resist pattern from being distorted and to accurately form the line width, it is necessary to form a uniform resist film without coating unevenness on the wafer. Therefore,
Conventionally, a method called spin coating has been used.

The method is, for example, as shown in FIG. 2, in which a wafer 2 is vacuum-sucked to a spin chuck 1 of a resist coating apparatus, and a nozzle 3 is introduced from about 5 mm above the rotating wafer 2.
Then, the resist 4 is discharged onto the wafer 2. The resist 4 ejected to the center of the wafer 2 receives the centrifugal force due to the rotation and spreads to the peripheral portion to form a resist film that covers the entire surface of the wafer 2. In this case, the uniformity of the film thickness of the resist film mainly depends on the rotation speed of the wafer 2 and the ejection amount of the resist 4.

When the above method is applied to a wafer having a diameter of 6 inches, the wafer 2 is used as a condition for obtaining a uniform film thickness.
The number of revolutions was required to be 1000 rpm to 2000 rpm, and the discharge amount was 3 cc to 4 cc.

[0005]

However, in the conventional method, since the resist is ejected while the nozzle 3 remains fixed on the center of the wafer 2, when the ejection amount is reduced to a certain extent, even the periphery of the wafer 2 is reached. There is a problem in that the resist 4 becomes unsatisfactory and uneven coating occurs.
Therefore, as described above, the ejection amount is set to 3 cc to 4 cc, but this naturally causes an increase in the cost of the semiconductor device.

The present invention has been made in view of the above problems, and provides a method for applying a resist having no application unevenness even with a smaller resist discharge amount than in the past, thereby reducing the cost in the manufacturing process of a semiconductor device. It is an object.

[0007]

In order to solve the above-mentioned problems, the present invention discharges the resist 4 while moving the nozzle 3 from the periphery of the rotating wafer 2 toward the center. Is characterized by.

[0008]

According to the above means, the resist 4 is moved while moving the nozzle 3 from the periphery of the rotating wafer 2 toward the center.
In comparison with the conventional method, a sufficient amount of the resist 4 can reach even in the periphery of the wafer 2.
A resist film having no coating unevenness can be formed even with a small resist discharge amount. According to the experiment by the inventor of the present application,
Even with a resist discharge amount of about 2 cc, a uniform resist film of about 1 micron without coating unevenness was obtained.

Therefore, it is 40% to 5% as compared with the conventional one.
It was possible to save 0% of resist and contribute to cost reduction in the semiconductor manufacturing process. In addition, when the nozzle 3 was moved from the center of the wafer 2 to the periphery in the opposite direction, coating unevenness occurred, so that the improvement effect was not obtained. It is considered that this is because the amount of the resist 4 around the wafer 2 is reduced.

[0010]

EXAMPLE An example of the resist coating method according to the present invention will be described below with reference to FIG. The present invention is characterized in that the resist 4 is ejected while moving the resist 3 from the periphery of the rotating wafer 2 toward the center, as shown in FIG. According to such a method, compared to the conventional method, the sufficient amount of the resist 4 reaches the periphery of the wafer 2 quickly, so that a resist film having no coating unevenness can be formed even with a small resist discharge amount.

The experiment conducted by the inventor of the present application will be described below. First, a wafer 2 having a diameter of 6 inches is prepared, and the wafer 2 is vacuum-sucked to the spin chuck 1 of the resist coating apparatus. Then, the spin chuck 1 is rotated at 1000 rpm.
Rotate at rpm to 2000 rpm. The tip of the nozzle 3 is in advance above the periphery of the wafer 2 by about 5 mm.
Put in the position. Then, while moving the nozzle 3 toward the center of the wafer 2 at a constant speed of about 40 mm / sec, 1 c
The resist is ejected at a rate of c / sec. Here, as the resist, OFPR which is a general positive type resist is used.
800 (trade name) was used. About 2 seconds after the start of movement, the nozzle 3 moves about 80 mm and reaches the center of the wafer 2. The amount of resist discharged during this period was about 2 cc.

Next, in order to check the uniformity of the resist film formed on the wafer 2, a film at the central portion and the peripheral portion of the wafer 2 is used by using an optical film thickness measuring device applying light diffraction. The thickness was compared. As a result, it was confirmed that the same uniformity as the conventional one was obtained. Further, it was confirmed by visual observation that there was no resist coating unevenness (wrinkles or light-colored portions) on the entire surface of the wafer 2.

Therefore, according to this embodiment, the amount of resist discharged is about 2 cc, which is 40% to 50% less than the conventional method, and the working time is 1
It becomes possible to shorten the second to 2 seconds. This has a significant saving effect in a wafer process that processes a large number of wafers. In the above embodiment, the case where the nozzle 3 is moved from the periphery of the wafer 2 toward the center has been described. Conversely, when the nozzle 3 is moved from the center of the wafer 2 to the periphery, the same effect is apparently obtained. It is possible that it will be obtained. However, according to the experiments conducted by the inventor of the present application, it was found that in this case, coating unevenness occurs, which is not practical. It is considered that this is because the amount of the resist 4 around the wafer 2 is reduced.

[0014]

As described above, according to the present invention,
Since the resist 4 is ejected while moving the nozzle 3 from the periphery of the rotating wafer 2 toward the center, a sufficient amount of the resist 4 can reach the periphery of the wafer 2 as compared with the conventional method. Therefore, a resist film having no coating unevenness can be formed with a small amount of resist discharged. According to the experiment by the inventor of the present application, a uniform resist film of about 1 micron was obtained even with a resist discharge amount of about 2 cc.

Therefore, according to the present invention, it is possible to save 40% to 50% of the resist as compared with the conventional case, and it is possible to contribute to the cost reduction in the semiconductor manufacturing process.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a resist coating method of the present invention.

FIG. 2 is a cross-sectional view illustrating a resist coating method according to a conventional example.

Claims (1)

[Claims] 1. A resist coating method in which a nozzle discharges resist onto a wafer from above a rotating wafer, and the resist is discharged while moving the nozzle from the periphery of the rotating wafer toward the center. A method for applying a resist, characterized in that