JP2618978B2 - Resist material and pattern forming method using the resist material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A radiation-sensitive positive resist used for patterning in the manufacture of a semiconductor integrated circuit and a pattern forming method using the resist are excellent in dry etching resistance and suitable for practical use. The purpose of the present invention is to provide a resist having sensitivity and resolution and to provide a method for forming a fine pattern using the resist, such that a copolymer represented by the following general formula is used as a resist material for exposure. Configure.

Here, X is a phenyl group or a derivative thereof.

[Industrial applications]

The present invention relates to a radiation-sensitive resist used for patterning in manufacturing a semiconductor integrated circuit, and a pattern forming method using the resist.

2. Description of the Related Art In recent years, in the manufacture of semiconductor integrated circuits, as the demand for higher density and higher integration of elements has further increased, the establishment of ultra-fine circuit pattern technology has been promoted. In this trend, in lithography, a method for forming a pattern using high energy radiation such as far ultraviolet rays, X-rays, and electron beams having a short wavelength instead of conventional ultraviolet rays has been developed. Accordingly, development of a high-performance resist material that is sensitive to such high-energy radiation is indispensable.

In the production of semiconductor integrated circuits using high-energy radiation, a method is employed in which a resist material is applied onto a substrate, and then the substrate is etched using a fine pattern obtained by irradiating and developing the radiation, as a mask. .

In such a manufacturing process, the resist is required to have high sensitivity and high resolution for obtaining a pattern in a submicron region. As for the etching process, a dry etching method using reactive sputtering or the like has been replaced with a wet etching method having a large side etching. For this reason, the resist is further required to have dry etching resistance.

[Prior art] Conventionally, many radiation-sensitive positive resists have been developed in which a polymer is irradiated with radiation to reduce the molecular weight and obtain a positive pattern by utilizing a solubility difference caused by a difference in molecular weight. However, none satisfy the above performance. For example, PMMA (methyl methacrylate polymer) is a resist material with excellent resolution, but its sensitivity (Dg ゜) is about 50 to 100 μC / cm ^{2 with} respect to electron beams, so it has practically high sensitivity. However, dry etching resistance is not sufficient. EBR-9 (trade name of Toray Industries, Inc.) using a polymer of the following general formula has a higher decomposition efficiency for high-energy radiation than PMMA, and therefore has high sensitivity, but has extremely poor dry etching resistance. Become.

On the other hand, a material having an aromatic ring in the unit structure represented by the following general formula has excellent dry etching resistance, but has poor sensitivity to radiation and extremely low sensitivity.

[Problems to be Solved by the Invention] Accordingly, conventionally, a material having excellent dry etching resistance and high practical sensitivity has not been obtained, and there has been no radiation-sensitive resist satisfying the above-mentioned performance.

It is an object of the present invention to provide a resist having excellent dry etching resistance and high sensitivity and resolution suitable for practical use, and to provide a method for forming a fine pattern using this resist. .

[Means for Solving the Problems] The present invention utilizes the fact that the following polymer has practical high sensitivity to radiation and excellent dry etching resistance.

Here, X is a phenyl group or a derivative thereof.

That is, the first of the present invention is a positive resist material for radiation exposure, characterized by using a copolymer represented by the above general formula, and the second is a copolymer comprising the copolymer represented by the above general formula. A pattern forming method characterized in that the used positive resist is applied to a substrate, and the substrate is dry-etched using a mask formed by irradiating high-energy radiation.

[Action] The copolymer represented by the above general formula used in the present invention has excellent dry etching resistance because it contains an aromatic ring in its structure, while the acrylotrile skeleton has the α-position substituted with an electron-withdrawing group. Therefore, the polymer main chain is easily broken,
High sensitivity. Therefore, this copolymer becomes a positive resist having practical sensitivity excellent in dry etching resistance. As the derivative of the phenyl group, those substituted with -R, -OR (R is alkyl), -OH or the like can be used.

 Hereinafter, the present invention will be described in more detail with reference to examples.

EXAMPLES Example 1 α-Methylstyrene and α-chloroacrylonitrile
Charged at a ratio of 9: 1, AIBN using 1,4-dioxane as a solvent
Was performed to obtain a copolymer having Mw = 40,000, a dispersity of 1.6, and a composition ratio of 1: 1. After making this polymer a cyclohexanone solution, it was spin-coated on a Si wafer to a thickness of 1.0 μm and baked at 170 ° C. for 20 minutes. The resulting resist film using an electron beam at an acceleration voltage 20KV changing the amount of exposure result of the exposure, the sensitivity of the D _g ⁰ = 20μC / cm ² was obtained (see FIG. 1). The slope (γ) of the sensitivity curve in FIG.
It was 0. A 0.375 μm line and space was resolved on this resist film. Next, reactive sputter etching was performed using CF ₄ + CHF ₃ gas, and the reduction of the resist film was examined. The results shown in Table 1 were obtained. The etching resistance was equivalent to that of OFPR-800 which is a positive type photoresist. I found it.

Comparative Example 1 The results of treating a typical positive resist, PMMA, in the same manner as in Example 1 are shown in FIG. 1, Table 1 and Table 2. As compared with these results, the resist of the present invention was about twice as high in sensitivity and etching resistance, and the resolution was the same.

(Example 2) When the charge ratio at the time of synthesis in Example 1 is 7: 3, Mw =
A polymer having a molecular weight of 70,000, a dispersity of 1.8, and a composition ratio of 1: 1 was obtained, and showed the same performance as that of Example 1.

Comparative Example 2 In Example 2, α was used instead of α-chloroacrylonitrile.
Radical polymerization using methacrylonitrile, whose position is an electron donating group, resulted in Mw = 60,000, dispersity 1.7, composition ratio
A 1: 1 copolymer was obtained. This coating, after exposure, development was carried out using a mixed solvent of toluene / ethylbenzene -1/1 had a lower sensitivity and _{^{D g 0 = 2000μC / cm 2}} .

The development conditions in the above Examples and Comparative Examples were butyl cellosolve = 10/1, 90 sec.

The conditions for the reactive sputter etch were as follows.

CF ₄ / CHF ₃ flow rate ratio = 1/1 Sputter power = 300 W, pressure 0.3 Torr (Effect of the Invention) As described above, according to the present invention, radiation having excellent dry etching resistance and practical high sensitivity A sensitive positive resist can be obtained, which greatly contributes to the formation of an ultrafine pattern.

[Brief description of the drawings]

FIG. 1 is a sensitivity curve of a 1: 1 copolymer of α-methylstyrene and α-chloroacrylonitrile.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-249049 (JP, A) JP-A-60-257445 (JP, A) JP-A-53-49956 (JP, A) JP-A-53-49956 76825 (JP, A) JP-A-54-153633 (JP, A)

Claims (2)

(57) [Claims] 1. A resist material for radiation exposure, comprising a copolymer represented by the following general formula. Here, X is a phenyl group or a derivative thereof. 2. A pattern forming method, comprising applying a resist using a copolymer represented by the following general formula to a substrate, and dry-etching the substrate using a mask formed by irradiating high-energy radiation. Method. Here, X is a phenyl group or a derivative thereof.