JPH02123732A - Resist-spin-coating method - Google Patents

Abstract

PURPOSE:To prevent the formation of stagnant part of resist in the vicinity of the facet of a semiconductor wafer and to form a resist film having the uniform thickness by dropping the resist on the semiconductor wafer, turning the wafer in the forward direction, spreading the resist to the peripheral part, and thereafter turning the wafer in the reverse direction. CONSTITUTION:Resist is dropped on the central part of a semiconductor wafer 1. The wafer is turned, e.g., in the clockwise direction. The resist is made to spread to the peripheral part of the semiconductor wafer 1. Thereafter, the wafer is turned in the counterclockwise direction. Thus the operation is finished. In this method a stangnant part of the resist is not formed in the vicinity of a facet 1A of the semiconductor wafer 1. A resist film 2 whose thickness is approximately uniform along the entire surface can be formed. Lithography can be performed readily. Generation of dust comprising resist pieces is eliminated, and the yield rate of the semiconductors is improved.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the resist spin coating method applied when forming a resist film on a semiconductor wafer, it is possible to form a resist film with a uniform thickness over the entire surface of the semiconductor wafer. A semiconductor wafer is held in a rotating chuck that can be rotated forward and reverse, a predetermined amount of resist is dropped onto the center of the semiconductor wafer, and the semiconductor wafer is rotated forward to remove the resist around the periphery. The method is structured to include the step of spreading the resist to a certain area, and then turning the semiconductor wafer upside down to finish applying the resist.

[Industrial application field]

The present invention relates to improvements in a resist spin coating method applied when forming a resist film on a semiconductor wafer.

In order to increase the degree of integration of semiconductor devices, it is necessary to form fine patterns, and mass production of submicron devices is currently about to begin.

A resist process is essential for patterning semiconductor devices, and in order to make a resist film into a mask with a fine pattern, it is important that the thickness of the resist film is uniform.

[Conventional technology]

Currently, when applying resist to semiconductor wafers, spin
The coat method is often used.

This technology holds a semiconductor wafer on a rotating chuck, drops resist onto the center of the chuck, rotates the rotating chuck, and therefore the semiconductor wafer, and spreads the resist to the periphery to obtain a coating film with a uniform thickness. This is what we are trying to do.

[Problem to be solved by the invention]

When a resist film is formed by the conventional spin coating method, it is difficult to make the film thickness uniform over the entire surface of a semiconductor wafer.

The reason for this is the presence of facets on the semiconductor wafer.

FIG. 3 is an explanatory diagram of the main parts for explaining the case of applying resist to a semiconductor wafer by the conventional spin coating method,
FIG. 4 shows a cutaway side view of the main part taken along the line X--X shown in FIG. 3, respectively.

In the figure, 1 is a semiconductor wafer, IA is a facet, 2
2A indicates a resist film, and 2A indicates a portion where the resist remains.

Here, it is assumed that the semiconductor wafer 1 is held by a rotating chuck (not shown) and rotated by a motor (not shown).

Now, drop the resist onto the center of the semiconductor wafer 1 and rotate it clockwise to spread the resist to the periphery of the semiconductor wafer l.

In this way, a retention portion 2A in which the resist film thickness is significantly increased is generated in a part of the vicinity of the facet IA.

This retained portion 2A not only makes the lithography process difficult, but also disintegrates in a later process and becomes dust that adheres to the semiconductor device, reducing the manufacturing yield.

The present invention aims to provide a resist spin coating method that can form a resist film having a uniform thickness over the entire surface of a semiconductor wafer.

[Means to solve the problem]

In the resist spin coating method according to the present invention, a semiconductor wafer (for example, semiconductor wafer 1) is held on a rotary chuck that can rotate forwardly and reversely, and a predetermined amount of resist is dropped onto the central portion of the semiconductor wafer. The method includes the steps of rotating the wafer in the normal direction to spread the resist to the peripheral area, and then rotating the semiconductor wafer in the reverse direction to finish applying the resist.

[Effect]

By adopting the above-mentioned means, no residual portion of the resist occurs near the facets of the semiconductor wafer, and a resist film having a substantially uniform thickness can be formed over the entire surface, facilitating lithography, and The production yield of semiconductor devices is improved since the generation of dust made of resist pieces is also eliminated.

〔Example〕

Fig. 1 is an explanatory view of the main part for explaining the case of applying resist to a semiconductor wafer according to an embodiment of the present invention, and Fig. 2 is a cut side view of the main part along the ¥ax-x shown in Fig. 1. The symbols used in FIGS. 3 and 4 indicate the same parts or have the same meaning, and the semiconductor wafer is held by a rotating chuck and can rotate freely. However, the rotary chuck is designed so that clockwise rotation and counterclockwise rotation can be arbitrarily selected.

Now, in order to form a resist film, the resist is dropped onto the central part of the semiconductor wafer 1 and then rotated, for example, clockwise to spread the resist to the peripheral part of the semiconductor wafer 1, and then rotated counterclockwise. then exit.

Examples of main data in this case are as follows.

Resist: 0FPR-800 (trade name, Tokyo Ohka product) Clockwise rotation: 1 [second] Counterclockwise rotation = 20 [seconds] Rotational acceleration: to, oo.

Rotation speed: 4000 (rpm) When the film thickness distribution of the resist film 2 formed as described above was investigated, in the vicinity of the facet IA,
The thickness was about 200 to 300 people thicker than the central part, but this distribution can be ignored in practical terms. Incidentally, when the conventional spin coating method is used, the thickness of the retention portion 2A reaches approximately 1 to 3 μm.

〔Effect of the invention〕

In the resist spin coating method according to the present invention, resist is dropped onto a semiconductor wafer, the wafer is rotated in the normal direction to spread the resist to the peripheral area, and then the wafer is rotated in the reverse direction.

By employing the above configuration, no residual portion of the resist occurs near the facets of the semiconductor wafer, and a resist film having a substantially uniform thickness can be formed over the entire surface, facilitating lithography, and The production yield of semiconductor devices is improved since the generation of dust made of resist pieces is also eliminated.

[Brief explanation of drawings]

FIG. 1 is an explanatory view of the main parts for explaining the case of applying resist to a semiconductor wafer according to an embodiment of the present invention, and FIG. 2 is a cutaway side view of the main parts along wAx-x seen in FIG. 1. , Fig. 3 is an explanatory diagram of the main parts to explain the case of applying resist to a semiconductor wafer by the conventional spin coating method, and Fig. 4 is an explanatory diagram of the main parts along l/lAx -x seen in Fig. 3. Each shows a partially cutaway side view. In the figure, 1 is a semiconductor wafer, IA is a facet, 2
2A indicates a resist film, and 2A indicates a portion where the resist remains. Patent applicant: Fujitsu Ltd. Representative Patent Attorney Shoji Aitani

Claims (1)

[Claims] A semiconductor wafer is held in a rotating chuck that can be rotated forward and reverse, a predetermined amount of resist is dropped onto the central portion of the semiconductor wafer, and the semiconductor wafer is rotated forward to apply the resist to the peripheral portion. 1. A resist spin coating method comprising the steps of: spreading the semiconductor wafer until the resist is applied, and then reversing the semiconductor wafer to finish applying the resist.