JPS5914891B2 - Spin coating method and spin coating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spin coating method and a spin coating device, and relates to a spin coating method and a spin coating device for coating a semiconductor substrate (hereinafter referred to as a wafer) surface with a resin (hereinafter referred to as a photoresist) free of foreign matter in a photolithography process for manufacturing semiconductor devices. The purpose is to uniformly apply the

Conventionally, a method called a spinner method is mainly used to apply photoresist to the surface to be coated (hereinafter referred to as the surface) of a wafer.As shown in FIG. Set the wafer 5-3 and apply an appropriate amount of photoresist 5 from above using a syringe 4 or nozzle, etc.
was applied dropwise, and the surface of the wafer 3 was applied by spinning with the surface facing upward.

However, in the method of dropping the photoresist 10 using a syringe, nozzle, etc., foreign matter contained in the photoresist is also applied at the same time, and since the surface of the way -3 is facing upward, the photoresist 5 is coated with foreign matter present in the air as well. Therefore, in the method shown in FIG. 1, in which foreign matter is applied dropwise, pattern defects 15 are generated due to foreign matter, and the manufacturing yield of semiconductor devices is greatly reduced.

The amount of photoresist to be dropped is, for example, 3 inches.

When applying a film thickness of 100OOA using a chip wafer, approximately 5×1
0 cwl is applied, but in reality, in order to eliminate uneven coating, a large amount of approximately 5 x 10 cd must be dropped onto the wafer using a syringe and then coated by high speed rotation.

Therefore, the method shown in FIG. 1 results in a great deal of wasted photoresist. Furthermore, in Fig. 1, the photoresist is dropped only in the center of the wafer.
The photoresist does not spread over the entire surface of the wafer, and a photoresist film with a non-uniform thickness is formed, especially at the periphery of the wafer, making microfabrication very difficult. 30 In order to solve the above-mentioned problems, an improved method was proposed in Japanese Patent Application No. 52-141362 (see Japanese Unexamined Patent Publication No. 54-73576).

This method will be explained with reference to FIG. Surface 1 of wafer 11
After setting the wafer 11 on the chuck 13Vc with the wafer 11 facing downward, the surface 12 of the wafer 11 is coated with photoresist 1.
After installing the photoresist 14 at position 1 close to the liquid level 15Vc of photoresist 14, pressurized gas is introduced into the pressurizing chamber 16 and the partition membrane 17 is expanded as indicated by 17'.
As shown by a broken line 155, the wafer is adhered to almost the entire surface 12 of the wafer 11.

Subsequently, the pressure inside the pressurizing chamber 16 is reduced to return the liquid level 152 of the photoresist 14 to the normal position 15, and the motor 1
At step 8, the wafer chuck 13 is rotated, and the wafer chuck 13 is pulled up to position 2 to form a photoresist film on the surface 12 of the wafer 11. As a result of studies conducted by the present inventor regarding this method, the following problems were found.

In other words, when attaching photoresist to one surface of the wafer, since the wafer and the photoresist liquid level are in a stationary state, air bubbles are likely to form on the one surface of the b-way due to the recesses formed on the wafer surface. Moreover, since it is difficult to apply the photoresist over the entire surface of the wafer, the photoresist film thickness also becomes uneven around the wafer, making microfabrication difficult. Further, foreign matter adhering to the wafer surface before the photoresist is attached is coated directly into the photoresist, making it difficult to uniformly apply the photoresist film, and also causing pattern defects due to the foreign matter. The present invention provides a coating method and apparatus that can eliminate such inconveniences, can uniformly coat photoresist, and is suitable for microfabrication. Fig. 3 shows the configuration of the method according to an embodiment of the present invention. .

As shown in FIG. 3, 21 is a wafer with its surface 22 facing downward, 28 is a wafer chuck for holding the wafer 21, 24 is a motor for rotating the wafer chuck 23, 25 is a photoresist solution, and 26 is a photoresist solution reservoir. The tank (container) 27 is located at the liquid level 28 of the photoresist 25.
This is an ultrasonic vibration generator for forming unevenness on the surface.
The surface 22 of the way 21 is the liquid level 28 of the photoresist 25.
It is installed so that it is almost parallel to the Also wafer
21, wafer chatter 25, and motor 24, or portion B, which includes tank 26 and ultrasonic vibration generator 27, is movable up and down. Next, the coating method will be described. Either the block portion A or the blotter portion B is moved up and down to bring the entire back surface 22 of the wafer 21 into contact with the liquid surface 28 of the photoresist 25.

In this way, the ultrasonic vibration generator 27 causes the liquid surface 28 of the photoresist 25 to be uneven at least while the photoresist 25 is in contact. The amplitude of the unevenness at this time is determined by the output and frequency of the ultrasonic vibration generator 27, but the way -
The conditions are such that the photoresist 25 does not adhere to the back surface 29 of the photoresist 21. That is, when the photoresist 25 adheres to the back surface 29 of the wafer 21 and further adheres to the wafer chatter 23, the photoresist 25 adheres to the front surface 22 of the wafer 21.
After spin coating, when removing the wafer 21 from the wafer chuck 23, it is difficult to remove it because the wafer 21 is adhered to the wafer chuck 23.
This may cause the wafer to be unable to be transported smoothly when the coating device is automated, and this situation must be avoided. Next, the wafer chuck 23 is moved upward or the tank 26 is moved downward to separate the back surface 22 of the wafer 21 from the liquid level 28 of the photoresist 25 by an appropriate distance.

Thereafter, the wafer chuck 23 is rotated by the motor 24 at a rotation speed necessary to obtain a desired photoresist film thickness, thereby coating a photoresist film. As shown in FIG. 3, when ultrasonic vibrations are applied to the photoresist 25 using the ultrasonic vibration generator 27, minute irregularities of amplitude are generated on the liquid surface of the photoresist 25, and the convex portions are formed on the wafer 21. The recesses formed on the surface 22 are also sufficiently filled to allow the photoresist to adhere uniformly to the entire surface.

Furthermore, since the minute vibrations generated on the liquid surface 28 of the photoresist 25 have vertical and horizontal momentum, foreign matter adhering to the back surface 22 of the wafer 21 before coating can be easily removed. In this manner, the following effects can be brought about by placing the back side of the wafer facing downward and bringing it into contact with the photoresist liquid surface while applying ultrasonic vibrations to the photoresist.

(1) Since it is possible to completely adhere the photoresist even to the concave portions of the pattern formed on the wafer surface, uniform photoresist application can be achieved.

(2) Even if foreign matter is on one surface of the wafer before coating, it is completely removed by ultrasonic vibrations of the photoresist liquid surface.

Uniform application of photoresist and removal of foreign matter are extremely important in manufacturing high-density semiconductor devices, and the present invention greatly contributes to improvements in this respect.

As described above, according to the present invention, it is possible to form a uniform photoresist film that does not contain foreign matter, and it is also possible to improve the manufacturing yield due to pattern defects, thereby adding great industrial value to the manufacturing of semiconductor devices. It is something that can be demonstrated.

[Brief explanation of the drawing]

FIG. 1 is a basic diagram of a conventional photoresist coating method, FIG. 2 is a schematic cross-sectional view of an apparatus showing an improved photoresist coating method, and FIG. 3 is a photoresist coating method according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the coating device in FIG. 21...Wafer one, 23...Wafer chuck, 24...Motor, 25...
・Photoresist solution, 26...tank (container),
27... Ultrasonic vibration generator, 28...
·Liquid surface.

Claims (1)

[Claims of Claims] 1. After the surface of the semiconductor substrate to be coated is facing downward and the entire surface of the surface to be coated of the semiconductor substrate is brought into contact at least once or more with the resin liquid level in the container to which ultrasonic vibrations are being applied. . A spin coating method, characterized in that the semiconductor substrate is rotated at a desired rotation speed while separating the resin liquid level from the surface to be coated of the semiconductor substrate. 2. A container having an ultrasonic vibration generator, a rotary table installed so that the surface of the semiconductor substrate to be coated faces the resin liquid level stored in the container, and a rotational drive for rotating the rotary table. a mechanism, at least one of the container or the turntable moves up and down so that the surface to be coated of the semiconductor substrate comes into contact with the resin surface in the container, and the resin is applied to the surface of the semiconductor substrate. Features: Rotary coating equipment.