JPH06326018A - Resist structure for pattern form and pattern forming method - Google Patents

Abstract

PURPOSE:To prevent the deformation of a resist pattern and the generation of a mixed layer at the interface of the resist in the pattern forming method using multilayered resist wherein two or more kinds of resist films are overlapped in the layered shape. CONSTITUTION:A first resist film 12 is applied and formed on a substrate 11. A water-soluble polymer film 13 is formed thereon. A second resist film 14 is applied and formed thereon. Thus, a pattern forming resist structure is provided. In the pattern forming method using this resist structure, there is no deformation during the manufacturing process of the first pattern. The mixed film, which is formed at the interface between two resist films and cannot be removed with developer, is not formed. Therefore, the formation of the excellent fine pattern using the multilayered resist can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method using a multi-layer resist structure used in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art For the purpose of reducing the gate length of a transistor and reducing the gate resistance, a gate having a T-shaped cross section has been formed by lift-off using a two-layer resist. As a pattern forming method using a two-layer resist, a pattern forming method as described in JP-A-2-191347, "Method for forming electrode for semiconductor device" is known. The pattern forming method described in the above publication is shown in FIG.
It shows in (a)-(b). After coating and forming a first resist film 31 on one main surface of the semiconductor substrate 301, exposure by electron beam exposure and development are performed, and then a SiO ₂ film is sputtered on the first resist film 31 as a thin film 32. Form by method. (FIG. 3 (a)).

Next, a (second) resist film 33 is formed by coating. Next, the second resist film 33 is exposed and developed to form a wide opening 3 including the opening 34 of the first resist film 31.
5 is formed, the thin film 32 is etched with an aqueous solution of ammonium fluoride through the opening 35 to form the semiconductor substrate 3
An opening (a T-shaped cross-section pattern 36) having a T-shaped cross-sectional shape is formed in the first resist film and the thin film 32 on 01 (FIG. 3B).

[0004]

The above-mentioned method is a method of forming a pattern by a multi-layer resist structure. However, in order to form a thin film on the first resist, sputter vapor deposition, electron melting vapor deposition, or electric conduction is used. Although it is necessary to adopt a method of heating vapor deposition, it is necessary to use a resist having high heat resistance so as not to cause the formation of the first resist pattern in any case. Limited.

A method of directly coating the second resist on the first resist film without using a thin film is conceivable. Generally, however, for overcoating the resist, a mixed layer is formed at the resist interface. Is known, and it is also known that this mixed layer cannot be easily removed by a developing solution.
Therefore, it has been necessary to consider a combination of resists that does not form a mixed layer, or a combination of resists that forms a mixed layer that can be removed depending on a developing solution.

The present invention is intended to provide a method capable of forming a pattern in a multi-layer resist structure by eliminating such conventional defects.

[0007]

The pattern forming method of the present invention comprises a step of coating and forming a first resist film on a substrate, and a developing treatment after irradiating the first resist film with a first energy ray. Thereby forming a first resist pattern, a step of coating and forming a water-soluble polymer film on the first resist film having the first pattern, and a second step on the water-soluble polymer film. A step of coating and forming a resist film, a step of forming a second resist pattern on the first resist pattern by developing the second resist film by irradiating it with a second energy ray, and Selectively removing the water-soluble polymer film using the second resist pattern as a mask, exposing a part or all of the second resist pattern to form a desired pattern. It is a symptom.

The resist structure used in this pattern forming method is characterized in that it is composed of first and second resist films and a water-soluble polymer film formed between them.

[0009]

In the present invention, the presence of the water-soluble polymer film between the first resist film and the second resist film causes generation of a mixed layer by mixing the first resist film and the second resist film. Has the effect of suppressing A mixed layer may be formed between the first resist film and the water-soluble polymer film,
Generally, if the property of the first resist film is hydrophobic, no mixed layer is generated. A mixed layer may be formed between the second resist film and the water-soluble polymer film, but even if the mixed layer is formed, the water-soluble polymer component can be removed with water. The second resist material component can be removed with a developing solution for the second resist film. Therefore, it is possible to form a resist pattern while avoiding the generation of a mixed layer that cannot be removed by development due to repeated coating of resist.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram showing a resist structure of the present invention,
2A to 2B are cross-sectional views for each step for explaining the method of the present invention.

FIG. 1 shows a resist structure formed by coating on a substrate according to the present invention. A first resist film 12 on the substrate 11, for example, an electro-photosensitive resist polymethylmethacrylate (polymethyl me).
thickness of 0.25 μm
And then formed on the first resist film 12 by a water-soluble polymer film 13, such as methyl cellulose (methyl cellulose).
Cellulose) is applied and formed to a thickness of 0.20 μm, and then a second resist film 14, for example, AZ1350J (trade name, manufactured by Hoechst) is applied to the water-soluble polymer film 13 to a thickness of 1.5 μm. It was formed.

FIG. 2 shows a pattern forming method according to the present invention in the order of steps, which will be described with reference to FIGS. 2 (a) to 2 (c). Here, a method of forming a T-shaped cross-section pattern is shown as an example.

As shown in FIG. 2 (a), a first resist film 22 is formed on a substrate 21, for example, an electrophotosensitive resist polymethylmethacrylate.
PMMA) is applied and formed to a thickness of 0.25 μm, and then a predetermined pattern is irradiated with electrons 221. Here, the pattern is used to form the openings.

Next, as shown in FIG. 2 (b), a developing solution is prepared by mixing the first resist film 22 with methyl isobutyl ketone (MIBK) and isopropyl alcohol (IPA) in a volume ratio of 1: 9. It is used for development to form an opening 25 of 0.1 μm in the first resist film 22. next,
A water-soluble polymer film 23, for example, an aqueous solution of methyl cellulose is applied and dried to have a thickness of 0.25 μm, and then a second resist film 24, for example, is formed on the water-soluble polymer film 23. AZ135
0J (trade name, manufactured by Hoechst) is applied and formed to a thickness of 1.5 μm. Next, the predetermined pattern is irradiated with ultraviolet light 224.

Next, as shown in FIG. 2C, the second resist film 24 is developed by using, for example, an AZ developer (trade name, manufactured by Hoechst Co.) to form the second resist film 24. A 0.7 μm opening 26 is formed in a region including the opening 25 to expose the water-soluble polymer film 23.

Then, as shown in FIG. 2D, the opening 2
The water-soluble polymer film 23 exposed by using 6 as a mask is removed by water to expose the opening 25, and a T-shaped cross-section pattern 27 constituted by the opening 26 and the opening 25 is formed.

According to this embodiment, a good fine T-shaped pattern could be formed without deformation of the first resist.

In the above embodiment, the first resist is PMMA and the second resist is AZ1350J.
Another resist may be used as long as it is a water-insoluble resist. The exposure method is not limited to this. Further, the opening width of the opening 25 of the first resist film is set to 0.1 μm.
Although the opening width of the second resist material layer is 0.7 μm, there is no problem even if the opening width of the opening 25 is larger than the opening width of the opening 26, and each opening width has a desired size. It is possible.

As the water-soluble polymer film 23, in this example,
Although methylcellulose water-soluble was used, it is natural that polyvinyl alcohol, polyvinylpyrrolidone, amylose and the like can also be used.

[0020]

According to the present invention, the presence of the water-soluble polymer film between the first resist film and the second resist film allows the mixing of the first resist film and the second resist film. It has an effect of suppressing the generation of the mixed layer. A mixed layer may be formed between the first resist film and the water-soluble polymer film, but generally, if the property of the first resist film is hydrophobic, the mixed layer does not occur. It is also possible to form a mixed layer between the second resist film and the water-soluble polymer film,
Even if the mixed layer is formed, the water-soluble polymer component can be removed with water, and the second resist material component can be removed with the developer for the second resist film. Therefore, it is possible to form a resist pattern while avoiding the generation of a mixed layer that cannot be removed by development due to repeated coating of resist.

According to the present invention, a fine pattern can be accurately formed even when a multilayer resist pattern is used. In particular, it is effective for pattern formation of a T-type gate structure and can reduce the gate length.

[Brief description of drawings]

FIG. 1 is a diagram showing a resist structure of the present invention.

FIG. 2 is a cross-sectional view for explaining a step of the pattern forming method of the present invention.

FIG. 3 is a cross-sectional view showing a conventional manufacturing process.

[Explanation of symbols]

 11 substrate 12 first resist film 13 water-soluble polymer film 14 second resist film 21 substrate 22 first resist film 221 electron beam 25, 26 opening 27 cross-section T-shaped pattern 23 water-soluble polymer film 24 second Resist film 224 UV light 301 Semiconductor substrate 31 First resist film 33 Second resist films 34, 35 Opening 36 T-shaped cross-section pattern

Claims (2)

[Claims] 1. A first resist film is formed by coating on a substrate, a water-soluble polymer film is formed by coating on the first resist film, and a second resist film is formed on the water-soluble polymer film. A resist structure for pattern formation, wherein the resist structure is formed by coating. 2. A step of coating and forming a first resist film on a substrate, and a step of irradiating the first resist film with a first energy beam and then developing it to form a first resist pattern. A step of coating and forming a water-soluble polymer film on the first resist film having the first pattern,
A step of coating and forming a second resist film on the water-soluble polymer film, and a developing process after irradiating the second resist film with a second energy beam to form a second resist pattern with the first A step of forming on the resist pattern, selectively removing the water-soluble polymer film using the second resist pattern as a mask to expose a part or all of the second resist pattern to form a desired pattern. And a step of forming the pattern.