KR920005781B1 - Photoresist composition - Google Patents

Abstract

Photoresist composition having high resolution at 365 nm infrared is composed of (A) 20-30 parts novolak resin of formula (I) prepared from meta/paracresol and formaldehyde, which has an average molecular weight of 8000-1200 and a molecular weight distribution (Mw/Mn) less than 10, (B) 5-10 parts photosensitive agent of naphthoquinone diazide sulfonic acid ester, and (C) 5-10 parts solvent of ethylene glycol ethylether acetate. In the formula (I), m and n are each 1-10. 0.1-5 parts polyhydroxy benzophenone like 2,3,4-trihydroxy benzophenone might be added to improve sensitivity.

Description

High resolution photoresist composition in 365nm infrared light source

The present invention relates to photoresist compositions required for the manufacture of semiconductor devices. In particular, the present invention relates to a positive resist composition which is particularly excellent in photosensitivity in i-rays of infrared rays (365 nm) and enables the fabrication of ultra-fine structures.

In general, the photosensitive resin is a substance that causes a physicochemical photoreaction when exposed to infrared (UV), E-Beam, X-ray or the like. It is composed of a binder resin, a photoreactive substance and an organic solvent, and in particular, additives are used in consideration of various properties such as improving photosensitivity, enhancing resolution, and thermal stability.

Examples of using novolak-based resins as binder resins among the photosensitive resins include USP 4,636,532, USP 4,551,409, USP 4,439,516, USP 3,900,325, EP 0 287 750, Japanese Patent 65-37836, USP 4,732,836, USP 4,775,730, USP 4,588,670, USP 4,555 And USP 4,245,030. However, when using the binder resin shown in these documents there is a problem that can not exhibit excellent resolution in 365nm i-rays.

In addition, as a photosensitizer, a naphthoquinone diazide sulfonic acid ester compound is generally used, and examples of such use include USP 4,555,469, USP 3,402,044, USP 3,046,118, USP 4,173,470, and the like.

However, the photosensitive resin described in the above documents is characterized by using a mixed solvent of 2-3 kinds of solvents without using a single solvent as a solvent.

It is therefore an object of the present invention to provide a photoresist composition having particularly good resolution at 365 nm i-rays.

The object of the present invention is to use a novolak resin of meta / para cresol type of the conventional novolak-based resin as a binder resin, and a new compound using epicatechin, esculletin and picetin as a photosensitive material At the same time, by using only ethylene glycol ethyl ether acetate as a solvent, it was possible to obtain a positive photoresist composition which is particularly excellent in photosensitivity in the i-ray of infrared rays (365 nm) and which enables the fabrication of an ultrafine structure.

The photoresist composition according to the present invention is a mixed novolac resin of methacresol and paracresol having a 20-30 parts by weight of a binder resin having a weight average molecular weight of 8,000-12,000 and a naphthoquinone diazide sulfonic acid ester structure. It consists of 5-10 parts by weight of a photosensitizer having a carboxyl content of 20-32%, and 5-10 parts by weight of ethylene glycol ethyl ether acetate as a solvent.

In the present invention, in addition to the above components, 0.1-5 parts by weight of polyhydroxy benzophenones such as 2, 3, 4-trihydroxy benzophenone are used to improve the sensitivity, and triazole or tetra is used to improve contrast and resolution. Nitrogen ring compounds such as sol compounds are used.

)는 10 이하임이 특징이다. 이러한 노볼락수지의 구조는 다음의 일반식(Ⅰ)과 같다 :The polymer resin used in the present invention is an improvement of a conventional novolak-based resin, and has excellent solubility in a solvent, and a difference in solubility between exposed and non-exposed parts is particularly excellent in photochemical mechanisms with a photosensitive agent used as a photosensitive material. The resolution and profile angle of the microstructure required for the present invention are greatly improved. These novolac resins are prepared from meta cresol, para cresol and formaldehyde, and the product has a transparent brown color with a weight average molecular weight of 8,000-12,000 and a molecular weight distribution (

) Is less than 10. The structure of this novolak resin is as shown in general formula (I):

Where m and n are integers greater than or equal to 10

Examples of the photosensitive substance include epicatechin having a polyhydroxy group of general formula (II), escullet of general formula (III), phycetin of general formula (IV), and 1,2-naphthoquinone azido-5-sulfonyl Use the reactant to which the chloride is reacted:

OH 또는 H임In the above formula, X ₁ , X ₂ , X ₃ , X ₄ , X ₅ , X ₆ , X ₇ , X ₈ , X ₉ , X ₁₀ , X ₁₁ are

OH or H

The above photosensitive material is characterized in that the content of the hydroxyl group is about 20-32% and when used with the novolak resin, it serves to improve the resolution and photosensitive properties.

The solvent does not change the physicochemical properties of the photoresist by using only ethylene glycol ethyl ether acetate rather than using 2-3 mixed solvents.

In addition, in the present invention, compounds such as triazole or tetrazole and polyhydroxy benzophenone are used in the range of 0.1-5 parts by weight so that the photoresist may have an ultrafine resolution in a UV light source of 365 nm.

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

Example 1

(Production of novolac resin)

At a temperature of 110 ° C., metacresol, paracresol and formaldehyde are mixed in an equivalent ratio, and a small amount of the metal catalyst [Zn (OAc) .2H ₂ O] is added thereto, stirred for about 30 minutes to completely dissolve, and then oxalic acid, ethyl A small amount of cellosolve acetate and water are added and polymerized for about 5-8 hours.

)는 10 이하이었다.After the reaction is neutralized using 70-100ml of 10% sodium carbonate, washed 2-3 times with water and dried. As a result of drying, a transparent brown compound was obtained. The weight average molecular weight was in the range of 8,000-12,000 and the molecular weight distribution (

) Was 10 or less.

Example 2

(Production of Photosensitive Material)

Compounds (II), (III), (IV) and 1,2-naphthoquinone diazide-5-sulfonylchloride described above are quantified according to a constant molar ratio (calculated in molar ratio depending on the number of hydroxyl groups in the reactants). The solution is dissolved in dioxane and reacted in a mixed solvent of triethylamine and dioxane.

The reaction product is a yellow powder, the yield is 90% or more, the content of the remaining hydroxyl group is 20-32%.

Example 3

(Production of Photoresist)

20 parts by weight of meta / para cresol novolac prepared in Example 1 and 10 parts by weight of the ortho-naphthoquinone diazide compound prepared in Example 2 were dissolved in 70 parts by weight of ethylene glycol ethyl ether acetate, an organic solvent, and then photospeed. Photoresist is prepared by adding 2 parts by weight of 2, 3, 4-trihydroxybenzophenone in consideration of photospeed, resolution, and adhesion to the wafer.

Example 4

22 parts by weight of the meta / para mixed cresol novolac (weight average molecular weight; 9,600) prepared in Example 1 and 6 parts by weight of the offto-naphthoquinone diazide sulfonic acid ester compound prepared in Example 2 ethylene glycol ethylether acetate 72 It was dissolved in parts by weight to prepare a photoresist.

Example 5

In Example 3, 2, 3, 4-trihydroxy benzophenone and 5-methyl-benzo triazole were added in an amount of 0.1-5 parts by weight to improve resolution and photosensitivity.

Example 6

As the polymer material prepared in Example 1, a novolac resin having a weight average molecular weight of 8,500 was used (meta / para-mixed type).

Example 7

As the polymer material prepared in Example 1, a novolak resin having a weight average molecular weight of 11,000 was used (meta / para mixed type).

Example 8

In Example 3, a mixing ratio of meta / para cresol novolak resin and ortho-naphthoquinone diazide sulfonic acid ester was prepared by 20: 8 (weight ratio).

Example 9

In Example 3, an equivalent amount of Compound (III) was used instead of Compound (II).

Example 10

In Example 3, the same amount of the compound (III) synthesized by the preparation method of Example 2 was used, and as the additive, 2, 3, 4-trihydroxy benzophenone and 1-phenyl-5-mercapto- The tetrazole was 0.1-5 weight part each.

Example 11

In Example 3, the same amount of the compound of compound (IV) synthesized in Example 2 was used.

Example 12

As the polymer resin used in Example 3, the same amount as the molecular weight of the m / p mixed cresol novolac prepared by the preparation method of Example 1 was 8,500.

Comparative Example 1

In Comparative Example 1, 23 parts by weight of conventional methacresol novolac (weight average molecular weight: 21,600) and a photoresist of naphthoquinone diazide structure (hereinafter referred to as PAC) 6 disclosed in US Pat. No. 3,402,044 of shipley co. Parts by weight were dissolved in 70 parts by weight of a mixed solvent of n-butyl acetate, xylene and ethyl cellosolve acetate (mixing ratio 1: 1: 8), and prepared with a surface treating agent to prepare a photosensitive resin (photoresist).

Comparative Example 2

In Comparative Example 1, 21 parts by weight of metacresol (weight average molecular weight: 18,000) and 8 parts by weight of a photosensitive agent were prepared.

Comparative Example 3

In Comparative Example 1, paracresol novolac (weight average molecular weight: 11,000) was used in the same amount instead of metacresol novolac.

Comparative Example 4

In Comparative Example 1, 1-5 parts by weight of 2, 3, 4-trihydroxy benzophenone and an additive of Compound (II) or (III) were added to improve resolution and photosensitivity.

Example 13

(evaluation)

The photoresist for manufacturing a semiconductor prepared in the above Examples and Comparative Examples was filtered through a 0.2 μm PTTE filtration membrane (removing impurity particles) and coated on a HMDS treated silicon wafer at about 1.1-1.2 μm by spin coating, and then at 110 ° C. After heat-treating for 70-90 seconds (Soft bake) and exposed by a 365 nm i-line (Hitachi stepper) and developed, the resolution of the microcircuit in the coating thin film was analyzed by SEM (SEM: electron microscope). At this time, the sensitivity, resolution, developability, uniform coating properties, thermal stability, and the like according to the exposure amount were evaluated to finally be suitable for the semiconductor manufacturing process.

Evaluation Results The photoresist preparations prepared by the comparative example were good in developability and thermal stability, but the resolution of 0.5 μm necessary for the fabrication of ultrafine circuits could not be reproduced. However, in the case of the photoresist prepared according to the present invention, when the m-cresol / p-cresol novolac (weight average molecular weight 8,000-11,000, molecular weight distribution Mw / Mn = 3-8) is used, the solubility of the exposed and non-exposed parts is Since the difference is large, a circuit pattern having a resolution (0.5 μm or less) suitable for microcircuits can be obtained, and affinity with novolak resin can be improved by using a naphthoquinone diazide compound having 20-32% of hydroxyl groups. It was. In addition, by using additives such as triazole and tetrazol to improve contrast and resolution, it can be improved to maintain good contrast even in ultra-fine structures, and 2, 3, 4-trihydroxy benzophenone at 0.1-5 parts by weight Adjust the dissolution rate while maintaining optimum sensitivity.

Claims (3)

A photoresist composition comprising a novolak resin, a photosensitizer and a solvent as a binder resin, wherein the copolymer is prepared from meta / paracresol and formaldehyde and has a weight average molecular weight in the range of 8,000-12,000.

20-30 parts by weight of a novolak resin of the following general formula (I) having 10 or less); 5-10 parts by weight of a naphthoquinone diazide sulfonic acid ester photosensitive agent having a hydroxy group content of 20-32% and having the following general formulas (II), (III) and (IV): ethylene glycol ethyl ether acetate alone solvent 5- Excellent photoresist composition in a 365 nm infrared light source, characterized in that consisting of 0 parts by weight:

In the above formula, m, an integer equal to or greater than 10, X ₁ -X ₁₁ =

OH or H. The photoresist composition of claim 1, further comprising 0.1-5 parts by weight of polyhydroxy benzophenones such as 2, 3, 4-trihydroxy benzophenone as a sensitivity enhancer. The photoresist composition of claim 1 or 2, further comprising a small amount of nitrogen ring compounds such as triazole or tetrazole compounds as contrast and resolution enhancers.