KR20060135984A - Spin coating method - Google Patents

Abstract

The present invention is to provide a spin coating method that can be applied to the photoresist film with a uniform thickness over the entire surface of the wafer during the spin coating process, for this purpose, the present invention is spaced a certain distance from the central axis of the wafer Dropping the coating material in the direction of the rotating axis; leaving the coating material spreading over the central axis to fill the center of the wafer; and a first rotational speed such that the coating material dropped on the wafer is fused to each other. And rotating the wafer at a second rotational speed that is faster than the first rotational speed such that the coating material is applied over the entire surface of the wafer.

Semiconductor devices, spin coating, photoresist, axis of rotation

Description

Spin coating method {SPIN COATING METHOD}

1 (a) and (b) are a plan view and a cross-sectional view shown for explaining the spin coating method according to the prior art.

2 to 4 are a plan view and a cross-sectional view shown for explaining the spin coating method according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10, 110: substrate

20, 120: photoresist solution

30, 130: turntable

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a spin coating method for coating a photoresist film.

In forming an integrated circuit on a semiconductor wafer, the pattern corresponding to the circuit elements of the integrated circuit is made by photolithography. In the photolithography process, a photoresist film is coated on a wafer, followed by an exposure and development process using a photo mask to form a photoresist pattern. Then, an etching process using the photoresist pattern is performed to form a circuit pattern.

As described above, in the photolithography process, the photoresist film is first applied onto the wafer surface. In general, the coding process of the photoresist film is performed in spin coating equipment. Spin coating equipment drops the photoresist solution near the center of the wafer while rotating the wafer at a predetermined rotational speed, and the photoresist solution dropped on the wafer is applied to the wafer surface while spreading uniformly around by the centrifugal force.

As shown in (a) and (b) of FIG. 1, during the spin coating process, the photoresist solution 20 is dropped on the center of the wafer 10 corresponding to the rotation center of the spin coating equipment. As a result, the centrifugal force becomes '0' on the rotational central axis so that the photoresist solution 20 located at the center of the center does not spread laterally. As a result, the photoresist film 20 is formed thicker at the center of the wafer 10 than at the edges.

In particular, in the case of a 300 mm large wafer, a larger centrifugal force is required to spread the photoresist solution 20 dropped to the center portion to the edge of the wafer 10. However, even if the spin coating equipment that provides greater rotational force provides more rotational force to spread the photoresist solution 20 on the rotational axis, it is difficult to ensure the thickness uniformity of the photoresist film at the edge of the wafer 10. It is difficult.

Meanwhile, '30', which is not illustrated and illustrated in FIG. 1, is a turn table for rotating the wafer.

Accordingly, an object of the present invention is to provide a spin coating method capable of applying a photoresist film with a uniform thickness over the entire surface of a wafer during the spin coating process.

According to an aspect of the present invention, a coating material is dropped in a direction of a rotation axis spaced apart from a central axis of a wafer by a predetermined distance, and the coating material spreads to the central axis to fill the center of the wafer. To rotate the wafer at a first rotational speed such that the coating materials dropped on the wafer are fused to each other, and faster than the first rotational speed so that the coating material is applied over the entire surface of the wafer. It provides a spin coating method comprising rotating the wafer at a second rotational speed.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. In addition, the same reference numerals throughout the specification represent components that perform the same function.

Example

2 to 4 are diagrams for explaining the spin coating method according to a preferred embodiment of the present invention. (A) is a top view of each figure, (b) is sectional drawing which shows along the II 'line | wire.

First, as shown in FIGS. 2A and 2B, the coating material may be a coating material in a rotational direction near an off axis spaced a certain distance from the central axis 111 of the wafer 110. The photoresist solution 120 is dropped. At this time, the photoresist solution 120 is preferably dropped by one drop in each of the east, west, north and north in the rotation direction. However, the number of dropping points for dropping the photoresist solution 120 is not limited to four east, west, north and south, and may be increased according to the size of the wafer 110. The greater the number of dropping points, the higher the uniformity of coating of the photoresist film. In addition, the method of dropping the photoresist solution 120 on the wafer 110 may be performed in a multi-drop method through one nozzle installed in spin coating equipment, or may be dropped at a time through a plurality of nozzles. It may be carried out in a floating manner.

On the other hand, in order to increase the coating uniformity of the photoresist film, a small amount of the photoresist solution 120 may be dropped on the central axis 111 in addition to the rotation axis direction. In this case, the amount of the photoresist solution 120 dropped on the central axis 111 may be 3-7%, preferably 5%, to the total amount of the photoresist solution 120 dropped on the wafer 110. .

Subsequently, as shown in FIGS. 3A and 3B, the photoresist solution 120 is left on the wafer 110 for a predetermined time. At this time, the photoresist solution 120 dropped on the wafer 110 is left to partially fill the center of the wafer 110. For example, the leaving time is set to several seconds, preferably 5 to 9 seconds.

Then, the turntable 130 is slowly rotated to fuse the photoresist solution 120 with each other. That is, when the wafer 110 is rotated through the turn-table 130, the photoresist solution 120 is spread by Coriolis' force and is present between the photoresist solutions 120 dropped on the wafer 110. The empty space is filled. At this time, the fusion process is carried out at 100 to 300rpm, preferably 200rpm for several seconds, preferably 5 to 9 seconds.

4, the photoresist solution 120 is uniformly coated over the entire surface of the wafer 110 by rotating the wafer 110 at 1500 to 3000 rpm, preferably 2000 rpm.

Although the technical spirit of the present invention has been described in detail in the preferred embodiments, it should be noted that the above-described embodiments are for the purpose of description and not of limitation. In addition, it will be understood by those skilled in the art that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, according to the present invention, the coating material is dropped in the rotational direction of the rotating shaft spaced apart from the central axis of the wafer at a predetermined interval, and the spin process is performed to shorten the distance that the coating material reaches the wafer edge. In addition, by reducing the amount of the coating material dropped in the center portion to prevent the phenomenon that the coating material is thickly applied to the center portion after the spin coating to ensure the uniformity of the coating over the entire surface.

Claims (7)

Dropping the coating material in the direction of the rotation axis spaced a distance from the central axis of the wafer; Allowing the coating material to spread to the central axis to fill the center of the wafer; Rotating the wafer at a first rotational speed such that the coating materials dropped on the wafer are fused together; And Rotating the wafer at a second rotational speed faster than the first rotational speed such that the coating material is applied over the entire wafer surface Spin coating method comprising a. The method of claim 1, Wherein the number of dropping points of the coating material is at least four. The method according to claim 1 or 2, And about 3 to 7% of the total amount of the coating material falls on the central axis of the wafer. The method according to claim 1 or 2, The step of leaving the wafer is carried out for 5 to 9 seconds spin coating method. The method according to claim 1 or 2, The first rotational speed is 100 ~ 300rpm spin coating method. The method of claim 5, Spinning the wafer at the first rotational speed is performed for 5 to 9 seconds. The method according to claim 1 or 2, The second rotational speed is 1500 ~ 3000rpm spin coating method.

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