JPH06283414A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To form a fine resist pattern which is hardly broken and fell down and whose aspect ratio is large. CONSTITUTION:A resist film 3 formed on the surface of an Si board 1 is exposed. After it is developed for the formation of a resist pattern 13, the pattern 13 is irradiated with far ultraviolet rays 7 without releasing a rinsing liquid from the surface of the board 1 in order to deteriorate the surface of the pattern 13. Thus the mechanical strength thereof is increased and the stress at the time of releasing the developing liquid 5 and rinsing liquid 5 is decreased. Therefore, even while the developing liquid 5 and rinsing liquid 5 are released/dried, the resist pattern 13 is hardly broken and hardly fall down.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a resist pattern in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices, especially large-scale integrated circuits (LSI), have become higher in density and higher in speed, miniaturization of elements has been required. In the LSI manufacturing process, the shorter the wavelength of light used in the photolithography process is, the finer the element can be formed. Therefore, the i-line having a wavelength of 365 nm, the KrF excimer laser having a wavelength of 248 nm, and the soft X-ray having a wavelength of about 1 nm ( Many attempts have been made to form a fine resist pattern using a light source such as X-ray).

An X-ray exposure method will be briefly described as an example of a conventional exposure method for forming a resist pattern with light having such a short wavelength or X-rays.

In FIG. 2, 3 is a resist film, 30 is a resist pattern, 4 is an X-ray mask, and 5 is a developing solution or a rinsing solution.

After a resist film 3 having a thickness of 1 μm is formed on the surface of the Si substrate 1 on which the Si02 film 2 is formed by spin coating, the aligner and the X-ray mask 4 are opposed to each other to align them. Sequential exposure of irradiating X-rays is performed (FIG. 2a). When exposing with i-rays or excimer laser light instead of X-rays, instead of facing the mask and the substrate, the i-rays and excimer laser light transmitted through the mask are reduced by a lens and projected onto the surface of the Si substrate 1. .

If necessary, after-exposure baking (PEB) is carried out at a temperature of about 90 ° C. for a short time, and then development is carried out. When developing the normally exposed resist, the Si substrate 1 is immersed in a developing solution, or the Si substrate 1 adsorbed by the rotatable wafer chuck 6 is stopped or rotated at a low speed.
By pooling the developer 5 on the surface of the substrate, the same state as immersion in the developer is obtained (FIG. 2b).

After the exposed portion of the resist film 3 is dissolved to form a resist pattern 30 (positive resist), a rinse solution is added while rotating the Si substrate 1 to sufficiently replace the developing solution, Further, it is rotated at a higher speed to be detached and dried (FIG. 2c). Then, in order to prevent the shape of the resist pattern 30 from changing, the surface of the resist pattern 30 is irradiated with far-ultraviolet light to change its quality, and then the resist pattern 30 is heated at a temperature of about 120 ° C. to be hardened to enhance the etching resistance.

Since the resist pattern 30 thus formed is used as a mask in the subsequent steps, for example, when etching the SiO 2 film 2 or when implanting ions into the Si substrate 1, a sufficient thickness is required. Is. In addition, a step such as a wiring electrode pattern is often formed on the surface of the Si substrate 1 by a previous step, and the top of the step has a sufficient masking effect at the time of the etching or ion implantation. 1
It has a thickness of μm or more.

[0009]

When forming a fine pattern, the resist pattern 30 has a large ratio of the thickness to the line width (aspect ratio). For example, 0.
When forming a pattern having a width of 15 μm, the aspect ratio becomes 6 or more. When attempting to form a resist pattern having a large aspect ratio as described above, many of the pieces break and fall in the developing process (FIG. 3). It is known that the phenomenon in which the resist pattern 30 collapses as described above is more likely to occur as the width of the resist pattern 30 becomes narrower, the thickness thereof becomes thicker, and the interval between adjacent patterns becomes smaller. When desorbing and drying the developing solution and the rinse solution in the developing step, the Si substrate is usually rotated at a high speed and centrifugal desorption is used. At this time, when the developing solution or rinsing solution between the developed resist patterns is released, the surface tension exerts a tensile stress on the resist pattern, which is one of the causes and the resist pattern is broken and collapsed. it is conceivable that.

In view of the above problems, it is an object of the present invention to form a resist pattern having a large aspect ratio and a fine dimension without breaking and collapsing.

[0011]

The method of forming a resist pattern according to the present invention increases the resistance to the stress applied to the resist pattern when the developing solution or the rinse solution is desorbed and dried, and also reduces the stress. It is intended to prevent the developed resist pattern from being broken and falling.

According to the structure of claim 1, the resist formed on the surface of the Si substrate is exposed to light, a resist pattern is formed with a developing solution, and then the developing solution or the rinsing solution is removed from the surface of the Si substrate and dried. It is characterized in that the surface of the resist pattern is altered by irradiating it with energetic light, and then the developing solution or rinsing solution is removed and dried.
According to claim 2, the high-energy light is far-ultraviolet light.

[0013]

According to the method of forming a resist pattern according to the first aspect of the invention, the surface of the resist pattern formed by the development after the exposure is altered by the irradiation of high energy light and hardened to become hydrophobic. Therefore, the resistance to the stress received from the developing solution or the rinsing solution is increased, the surface tension is further reduced, and the stress received by the resist pattern when the developing solution or the rinsing solution is released is reduced. It does not fall down.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a partial process of forming a resist pattern. 1 is a Si substrate, 2 is a SiO2 film, 3 is a resist film, 5 is a developing solution or a rinsing solution, 6 is a wafer chuck, and 7 is a remote wafer. Ultraviolet light, 13 is a resist pattern.

After the positive resist film 3 having a thickness of 1 μm is formed on the Si substrate 1 having the SiO 2 film 2 on its surface, the aligner is opposed to the X-ray mask 4 by an aligner to align them, and then the X-ray Sequential exposure is performed (Fig. 1a).

If necessary, after post-exposure baking (PEB) at a temperature of about 90 ° C. for a short time, the wafer is chucked by a wafer chuck 6 and then the Si substrate 1 is adsorbed by the conventional developing method.
The developing solution 5 is stored on the surface with surface tension, and the region irradiated with X-rays is dissolved. After the resist pattern 13 is formed,
The developer is replaced with the rinse liquid by adding the rinse liquid while the developer is stored. Further, the far-ultraviolet light 7 is irradiated while the rinse liquid 5 is stored on the surface of the Si substrate 1 (see FIG. 1).
b). As a result, the surface of the resist pattern 13 is altered.

After that, the Si substrate 1 is rotated, and the rinse liquid 5 accumulated on the surface is decentered and dried (FIG. 1c).
The surface of the resist pattern 13 is altered, the mechanical strength against stress is increased, and the resist pattern 13 becomes hydrophobic.
Since the stress received by the surface tension when the rinse liquid is separated from the surface is small, even the fine resist pattern 13 having a large aspect ratio does not break and fall.

[0019]

In the resist pattern forming method of the present invention, since the surface of the formed resist pattern is altered before the developing solution or the rinsing solution is removed from the substrate surface and dried after the development, the developing solution or the rinsing solution is used. It is easy to form a fine resist pattern having a large aspect ratio without breaking and falling when the liquid is released.

[Brief description of drawings]

FIG. 1 is a partial process sectional view of a resist pattern forming method according to an embodiment of the present invention.

FIG. 2 is a partial process sectional view of a conventional resist pattern forming method.

FIG. 3 is a schematic sectional view of a resist pattern formed by a conventional method.

[Explanation of symbols]

 1 Si substrate 2 SiO2 film 3 Resist film 4 X-ray mask 5 Developer or rinse liquid 6 Wafer chuck 7 Far-ultraviolet light

Claims (2)

[Claims] 1. A resist formed on the surface of a substrate is exposed to light, then dipped in a developing solution for development, and the formed resist pattern is dipped in a developing solution or a rinsing solution, and high energy rays are applied to the resist pattern. A method for forming a resist pattern, which comprises irradiating to modify the surface of the resist pattern, and then removing and drying the developing solution or rinsing solution. 2. The method of forming a resist pattern according to claim 1, wherein the high energy rays are deep ultraviolet rays.