JPH0619136A - Photosensitive material - Google Patents

Abstract

PURPOSE:To provide a resist which satisfies the requirement for high resolution and high sensitivity by adding photosensitive group to Fullerene. CONSTITUTION:Photosensitive groups are added to Fullerene which is a carbon allotrope called as a carbon cluster. Fullerene expressed by molecular formula C60 or C70 is preferably used. Any functional groups which can cause chemical reaction by irradiation of UV rays, for UV rays, X-rays, electron beams or the like can be used as the photosensitive groups. To introduce photosensitive groups to Fullerene, normal chemical reaction is used. For example, Fullerene is stirred in alkyl amine at room temp. for several hours to add alkyl amino to the Fullerene and then the reaction with methacryl chloride is effected at room temp. for several hours. Thus, a photosensitive material having methacrylamide group as photosensitive groups can be synthesized. This photosensitive material has high dry etching resistance and can be used in a thin film state, so that the film has high resolution and high sensitivity.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a light-sensitive material. More specifically, the present invention relates to a photosensitive material suitable for manufacturing semiconductor elements such as LSI, and more specifically to ultraviolet light, far ultraviolet light,
The present invention relates to a photosensitive material suitable as a resist for photolithography for manufacturing a semiconductor device using an X-ray, an electron beam or the like as a light source.

[0002]

2. Description of the Related Art So far, as a semiconductor resist, g
For light sources such as X-ray (436 nm), i-line (366 nm), and KrF excimer laser light (248 nm), a positive resist in which a quinonediazide compound as a photosensitive component is added to a novolac type phenol resin (hereinafter abbreviated as novolac resin) is used. For X-rays and electron beams, a positive resist obtained by adding poly-2-methylpentene-1-sulfone as a photosensitive component to a novolak resin has been widely used.

[0003]

Problems to be Solved by the Invention In recent years, semiconductor devices such as LSI have become finer and finer, and the demand for photolithography has become stricter year by year. At present, there is a demand for a resist capable of forming a high-resolution pattern having a minimum line width of half micron (0.5 μm) and further coater micron (0.25 μm). Further, a highly sensitive resist is required to further improve productivity. However, in reality, the above-mentioned resist cannot sufficiently meet this requirement. Therefore, in the semiconductor industry, the emergence of new resists that satisfy the requirements for high resolution and high sensitivity is strongly demanded.

[0004]

The present invention solves the above-mentioned problems and provides a resist having high resolution and high sensitivity. That is, the present invention provides a photosensitive material obtained by adding a photosensitive group to fullerene.

The fullerene of the present invention refers to a carbon allotrope which is also called a carbon cluster. The fullerene known so far has a molecular formula of C60, C70,
C76, C78, C82, C84, C90, C96 and the like. In the present invention, one kind or a mixture of two or more kinds of these fullerenes can be used. Of these, C60 and C70 are preferable, and C60 is particularly preferable.
Can be preferably used as the fullerene of the present invention.

Generally, cross-linking type (negative type) and disintegrating type (positive type) are known as types of photosensitive reaction, and either of them can be used in the present invention, but the cross-linking type reaction is more preferable.

As the photosensitive group of the present invention, any functional group which causes a chemical reaction upon irradiation with ultraviolet rays, deep ultraviolet rays, X-rays, electron beams or the like can be used without any particular limitation. Of these, acryloyl group, methacryloyl group, vinyl group and epoxy group are preferable, and acryloyl group and methacryloyl group are particularly preferable as the photosensitive group of the invention.
The type of photosensitive group to be added is usually one type, but two or more types can be added if necessary.

The method of introducing a photosensitive group into fullerene is not particularly limited, and a usual chemical reaction can be adopted. For example, after the alkylamine is added to the fullerene by stirring the fullerene in the alkylamine at room temperature for several hours, the fullerene is further reacted with methacryl chloride at room temperature for several hours to give a methacrylamide group having a methacrylamide group as a photosensitive group. Photosensitive materials can be synthesized.

The amount of the photosensitive group can be selected according to the reactivity of the photosensitive group, but is usually 0.1 to 10 mol, preferably 0.3 to 5 mol, and particularly preferably 1 mol of fullerene. Can be used in the range of 0.5 to 3 mol. If it is less than 0.1 mol, the photosensitivity will be insufficient. If it is more than 10 mol, the storage stability will be lowered.

The light-sensitive material of the present invention has the feature that it has extremely high resistance to dry etching as compared with conventional light-sensitive materials. For example, the reactive ion etching using CF ₄ gas is 40 times to 60 times that of the conventional photosensitive material.
It is twice as resistant. Therefore, when it is used as a light-sensitive material, its film thickness can be reduced to an ordinary tenths. As a result, it exhibits remarkably higher resolution and sensitivity than conventional light-sensitive materials.

The light-sensitive material of the present invention is usually 2 to 2 on the substrate.
It is used by forming a film with a film thickness of 00 nm, preferably 5 to 100 nm, particularly preferably 10 to 50 nm.
If it is thinner than 2 nm, the uniformity of the thin film is slightly deteriorated. If it is thicker than 200 nm, the features of the present invention cannot be fully exhibited.

As the method for forming the film, various methods such as spin coating (spin coating) and vapor deposition can be used, but spin coating is most preferable. In that case, the solution of the light-sensitive material of the present invention is applied. As the solvent, any solvent capable of dissolving the photosensitizer of the present invention can be used, but as a preferable solvent, an aromatic solvent can be used, and among them, particularly preferable solvents can be toluene, xylene, pseudocumene and the like. The concentration is adjusted depending on the film thickness to be formed, but is usually 0.1 to 1% by weight.

The light-sensitive material of the present invention contains ultraviolet rays, far ultraviolet rays, X
The light source is not particularly limited because it has high resolution and high sensitivity to various light sources such as rays and electron rays, but the effect is particularly high for X-rays and electron rays.

The conditions for development after exposure can be selected depending on the type of photosensitive group to be added. When used as a negative type photosensitive material, an aromatic solvent is preferable as a developing solution, and toluene and xylene are particularly preferable as a developing solution. The temperature and time of development are not particularly limited, but the development is usually performed by immersing in a developing solution at a temperature of 20 to 30 ° C. for 30 to 200 seconds.

[0015]

EXAMPLES The present invention will be described below in greater detail by giving Examples, but the present invention is not limited thereto. (Synthesis example) 0.2 g of high-purity C60 (purity 99.8%) was charged into a 200 mL flask equipped with a stirrer together with 100 g of n-propylamine, and reacted at 20 ° C for 1 hour.
After the completion, the product obtained by distilling off n-propylamine was subjected to elemental analysis and NMR analysis, and as a result, it was found that 1.2 pieces of n-propylamine were added to C60 on average. The adduct was further reacted with methacryl chloride in toluene to obtain a resist in which 1.2 units of the following formula (Formula 1) were added to C601 molecule on average.

[0016]

[Chemical 1]

(Comparative Synthesis Example) Phenol 11.4 g, m
-Prepare 26.1 g of cresol, 28.5 g of 37% aqueous formaldehyde solution, 0.61 g of oxalic acid dihydrate, 3.6 g of ion-exchanged water, and 12.0 g of ethyl cellosolve acetate in a 300 mL separable flask at 110 ° C for 3 hours. The mixture was heated and stirred to cause a reaction. After the post-treatment, ethyl cellosolve acetate was distilled off to recover the novolak resin. The average molecular weight was 13,000. A resist was prepared by uniformly mixing 90 parts by weight of this novolac resin with 10 parts by weight of poly-2-methylpentene-1-sulfone having an average molecular weight of 82,000.

<Evaluation of resist performance> (Synthesis example resist) 0.5% by weight of the synthesis example resist
A silicon wafer was spin-coated with the pseudocumene solution containing it and further preheated to form a film of the photosensitive material of the synthesis example with a film thickness of 22.0 nm. A sensitivity characteristic curve is created by exposing this resist to a predetermined amount of electron beam and developing with toluene for 1 min. The sensitivity (smaller the value, the higher the sensitivity) and the γ value (the larger the value, the higher the resolution). ) Was asked.

(Resist of Comparative Synthesis Example) Similarly, a film having a thickness of 1200 nm was formed from an ethyl cellosolve acetate solution containing 10% by weight of the resist of Comparative Synthesis Example. After exposure to an electron beam, development was carried out for 1 min with an alkaline aqueous solution, and the sensitivity and γ value were obtained in the same manner as the resist of the synthesis example.

[0020]

[Table 1]

As is clear from Table 1, the resists of the synthesis examples have extremely high sensitivity and resolution. <CF ₄ Reactive Ion Etching Test> A test film was prepared in the same manner as in the evaluation of resist performance. Since the resist of the synthesis example is a negative type, a test was conducted by exposing it to an electron beam having a considerable sensitivity and developing it. Since the resist of the comparative synthesis example is a positive type, the resist developed without exposure was tested. The test was carried out using a reactive ion etching apparatus RIE-1 manufactured by Samco Co., Ltd. with a CF ₄ gas pressure of 0.10.
It was performed under the conditions of torr and output of 100 W. The results are shown in Table 2.

[0022]

[Table 2]

As is clear from Table 2, the resist of the synthetic example has an etching resistance about 60 times that of the resist of the comparative example. Therefore, even if the film thickness is much smaller than that of the resist of the comparative synthesis example, the length of time to endure the etching (until the film thickness becomes zero) is the same.

[0024]

As described above, the light-sensitive material of the present invention has an extremely high resistance to dry etching and therefore can be used with an extremely thin film thickness, and therefore exhibits extremely high resolution and photosensitivity.

Claims (1)

[Claims] 1. A photosensitive material obtained by adding a photosensitive group to fullerene.