KR20010094001A - Photoresist composition comprising photosensitive polymer having naphthyl derivative (meth)acrylate monomer - Google Patents

Abstract

PURPOSE: A photo resist composition is provided, which comprises a photosensitive polymer provided with (meth)acrylic acid ester substituted with a naphthalene derivative as a monomer, to improve the resistance to dry etching. CONSTITUTION: The photo resist composition comprises a photosensitive polymer represented by the formula; 1-15 wt% of a photoacid generator; and optionally 0.01-2.0 wt% of an organic base. In the formula, R1 is 1-alkoxyethyl group, 1-alkoxypropyl group, tetrahydropyranyl group, t-butoxycarbonyl group, or an acetal group of C4-C14; R2 is H or a methyl group; X is H or a hydroxy group; and l/(l+m+n) = 0.4-0.9, m/(l+m+n) = 0.1-0.5, and n/(l+m+n) = 0.01-0.4. The mass mean molecular weight of the photosensitive polymer is 5,000-100,000. Preferably the photoacid generator is triarylsulfonium salt, diaryl iodine salt, sulfonate or their mixtures.

Description

Photoresist composition comprising photosensitive polymer having naphthyl derivative (meth) acrylate monomer having a (meth) acrylic acid ester substituted with a naphthalene derivative as a monomer

The present invention relates to a photoresist composition, and more particularly, to a photoresist composition comprising a photosensitive polymer having a (meth) acrylic acid ester substituted with a naphthalene derivative as a monomer.

As the semiconductor manufacturing process becomes complicated and the degree of integration of semiconductor devices increases, fine pattern formation is required. Moreover, as the capacity of semiconductor devices increases to 256 megabits or more, a pattern size of 0.2 µm or less is required in the photolithography process, and accordingly, a conventional chemically amplified photoresist material for deep-UV is used. There is a limit.

Furthermore, when the photolithography process is performed using a photoresist using a current KrF excimer laser (248 nm) as a light source, in order to achieve high resolution and to increase depth of focus (DOF), It is desired to form a thin film photoresist. In addition, as the aspect ratio increases as the resolution of the photoresist pattern increases, a phenomenon in which the photoresist pattern collapses is prominent, and thus the demand for a thin film is further increased.

However, the most serious problem in using a thin film photoresist is that it cannot secure resistance to dry etching of the photoresist film formed from the thin film. In particular, a thin film photoresist using a poly (hydroxystyrene) polymer, which is a conventional KrF photoresist, is less resistant to dry etching than a novolak resin, which is a conventional G-line or i-line photoresist, and thus used as a thin film photoresist. There is a limit to this.

The technical problem to be achieved by the present invention is to solve the above problems of the prior art, and includes a photosensitive polymer having a (meth) acrylic acid ester substituted with a naphthalene derivative having a structure of enhanced resistance to dry etching as a monomer. It is to provide a photoresist composition.

The photoresist composition according to the present invention for achieving the above technical problem has the following formula, and comprises a photosensitive polymer having a weight average molecular weight of 5,000 to 100,000 and a photoacid generator of 1 to 15% by weight based on the weight of the polymer. .

Wherein R ₁ is 1-alkoxyethyl, 1-alkoxypropyl, tetrahydropyranyl, t-butoxycarbonyl or a bulky acetal group of C _{4 to} C ₁₄ ,

R ₂ is a hydrogen atom or a methyl group,

X is a hydrogen atom or a hydroxy group,

l / (l + m + n) = 0.4-0.9, m / (l + m + n) = 0.1-0.5, n / (l + m + n) = 0.01-0.4.

Preferably, R ₁ is a 1-ethoxyethyl group, R ₂ is hydrogen or a methyl group, and X is a hydrogen atom.

It is preferable that the photoresist composition further includes an organic base.

The photoresist composition according to the present invention includes a photosensitive polymer having a (meth) acrylic acid ester substituted with a naphthalene derivative as a monomer. Therefore, the photoresist composition according to the present invention ensures sufficient resistance to dry etching. Therefore, in the subsequent dry etching process of patterning a photoresist film made of the photoresist composition according to the present invention and then using the mask layer as a mask layer, resistance to dry etching is large, so that sufficient etching time can be obtained. Therefore, a pattern with a large aspect ratio can be formed.

Hereinafter, a photoresist composition according to the present invention will be described. Moreover, the preferable photolithography process using a photoresist composition is also demonstrated. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only the embodiments are to make the disclosure of the present invention complete, and complete the scope of the invention to those skilled in the art. It is provided to inform you.

Photosensitive polymer and photoresist composition for photoresist

The photosensitive polymer constituting the photoresist composition according to the present invention is represented by the following formula.

Wherein R ₁ is 1-alkoxyethyl, 1-alkoxypropyl, tetrahydropyranyl, t-butoxycarbonyl or a bulky acetal group of C _{4 to} C ₁₄ ,

R ₂ is a hydrogen atom or a methyl group,

X is a hydrogen atom or a hydroxy group,

l / (l + m + n) = 0.4 to 0.9, m / (l + m + n) = 0.1 to 0.5, n / (l + m + n) = 0.01 to 0.4,

The weight average molecular weight of the polymer is 5,000 to 30,000.

Preferably, R ₁ is a 1-ethoxyethyl group, R ₂ is hydrogen or a methyl group, and X is a hydrogen atom.

The photoresist composition according to the present invention comprises a photoacid generator mixed with the polymer of Formula 1 and 1 to 15% by weight based on the weight of these polymers.

As the photoacid generator, a material having high thermal stability is preferably used. Thus, triarylsulfonium salts, diaryliodonium salts, sulfonates or mixtures thereof can be used. For example, a mixture of triphenylsulfonium triflate and trifluoromethanesulfonate, diphenyliodinium triflate, a mixture of triphenylsulfonium nonaplate and nonafluoromethanesulfonate, diphenyliodonium nonaplate, triphenyl Sulfonium antimonate, diphenyl iodonium antimonate, di-t-butyldiphenyl iodonium triflate, N-succinimide triflate, 2,6-dinitrobenzyl sulfonate and the like can be used as the photoacid generator.

The photoresist composition according to the present invention further comprises 0.01 to 2.0% by weight of organic base based on the weight of the polymer. Triethylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanolamine, etc. are used as an organic base. After exposure, the organic base is added to prevent the problem that the acid generated in the exposed portion diffuses into the non-exposed portion to form a non-exposed portion, which also hydrolyzes and deforms the pattern.

In addition, the photoresist composition may further include about 50-300 ppm of a surfactant in the form of a salt or an organic material. As the surfactant, polyether, poly (ethylene glycol) or polysulfonate may be used.

Manufacturing method of the polymer

1. Manufacturing method of monomer (III)

As described in Scheme 1, (meth) acryloyl chloride (I) is reacted with naphthol or naphthol derivative (II) to prepare monomer (III) substituted with naphthalene derivative.

Wherein R ₂ is a hydrogen atom or a methyl group,

X is a hydrogen atom or a hydroxyl group.

2.Production method of copolymer (VI)

As shown in the following Reaction Formula (2), the monomer (III) and acetoxy styrene synthesized above are dissolved in an organic solvent, and then a polymerization initiator is added to prepare a copolymer (V).

Subsequently, the copolymer is refluxed in a solution of ammonium hydroxide and methanol as in Scheme (3) to produce a hydroxystyrene-based copolymer (VI).

3. Process for preparing terpolymer (VII)

After dissolving a compound capable of providing a protecting group (R ₁ , protecting group) to the copolymer (VI) and the hydroxy styrene monomer prepared above as in Scheme 4 in an organic solvent, the protecting group (R ₁ ) is hydroxy styrene. Subsequent reaction of substituting some of the monomers proceeds to prepare terpolymer (VII). The protecting group R ₁ refers to a group which is deprotected by an acidolysis reaction with an acid catalyst produced by a photoacid generator.

Wherein R ₁ is 1-alkoxyethyl, 1-alkoxypropyl, tetrahydropyranyl, t-butoxycarbonyl or a bulky acetal group of C _{4 to} C ₁₄ ,

l / (l + m + n) = 0.4 to 0.9, m / (l + m + n) = 0.1 to 0.5, n / (l + m + n) = 0.01 to 0.4,

The weight average molecular weight of the polymer is 5,000 to 30,000.

Manufacturing method of photoresist composition and photolithography method using same

A photoresist composition is prepared by dissolving 1-15% by weight of a photoacid generator in an appropriate solvent in a terpolymer (VII) prepared by the above manufacturing process based on the weight of the terpolymer. As the photoacid generator, a triarylsulfonium salt, a diaryl iodonium salt, a sulfonate or a mixture thereof described above is used. Further, an organic base which is 0.01 to 2.0% by weight based on the weight of the polymer is further added. Preferably, about 50-300 ppm of surfactant is added.

The photolithography process using the photoresist composition prepared according to the method described above proceeds as follows.

First, hexamethyldisilazane (HMDS) is applied onto a substrate on which a target layer to be patterned is formed, and then the photoresist composition described above is applied to form a photoresist film having a predetermined thickness. Since the photoresist composition according to the present invention is composed of a polymer having hydroxy styrene as a monomer, it easily adheres to the substrate. Next, pre-baking is performed on the photoresist film. After the pre-exposure bake step, the photoresist film is exposed using a mask having a predetermined pattern using a suitable exposure source (Deep-UV, KrF excimer laser, electron beam or X-ray). By exposure, acid is generated from the photoacid generator in the photoresist film, and the generated acid catalyzes to hydrolyze the protecting group R ₁ to form a large amount of hydroxyl groups.

Therefore, the polarity of the photoresist film of the exposed portion and the polarity of the photoresist film of the unexposed portion are remarkably different. In other words, the contrast is significantly increased.

After the exposure is completed, before the development, the photoresist film is baked again for a short time (post-exposure treatment: Post-Exposure Bake). The post-exposure bake is performed to further activate the acidolysis reaction by the acid catalyst in the exposed portion. In other words, the protective group R _{1 in the} exposed portion is carried out to promote hydrolysis.

Next, a developing step is performed using an appropriate developer to complete the photoresist pattern. At this time, the developer used is a developer at a concentration used in a conventional process, such as 2.38% by weight of tetramethylammonium hydroxide (TMAH).

The etching target layer under the photoresist pattern is etched using a dry etching gas (halogen or carbon fluoride (C _x F _y )) using the photoresist pattern thus formed as an etching mask. In this case, the photoresist film has a high resistance to dry etching, and thus, there is an advantage in that it can have sufficient etching time.

The present invention is described in more detail with reference to the following experimental examples, which are not intended to limit the present invention.

Experimental Example 1: Preparation of 2-naphthyl acrylic ester

2-naphthol (29 g, 0.2 mol) and triethylamine (23.3 g, 0.22 mol) were dissolved in dichloromethane (500 mL) in a 1 L three-necked flask, followed by acryl chloride. Day (20g, 0.22mol) was slowly dropped and reacted for about 12 hours.

After the reaction was completed, the reaction mass was dropped into excess water, neutralized with HCl, and extracted with diethyl ether. The extracted organic layer was dried using magnesium sulfate, and the product was separated by column chromatography using a solvent having an ethyl acetate: n-hexane ratio of 1: 3. (Yield 75%)

Experimental Example 2: Synthesis of Copolymer

Acetoxy styrene (14.6 g, 90 mmol) and 2-naphthyl acrylate ester (2.0 g. 10 mmol) were dissolved in toluene (80 mL) together with azobisisobutyronitrile (AIBN) (1.0 g, 6 mmol), followed by nitrogen. The reaction was purged for about 1 hour and the resulting reaction was polymerized at 70 ° C. for 24 hours.

After the end of the polymerization, the reaction was precipitated in excess n-hexane (10-fold) and the precipitate was dried for 24 hours in a vacuum oven maintained at 50 ° C. to afford the desired product. (Yield 75%)

At this time, the weight average molecular weight (Mw) of the obtained product was 12240, and polydispersity was 1.8.

Experimental Example 3 Hydrolysis of Copolymer

The copolymer (10 g) synthesized in Experimental Example 2 was refluxed in a solution of ammonium hydroxide (28% NH ₄ OH solution, 10 mL) and methanol (80 mL) for 4 hours, and then the resulting reaction was slowly added to excess water (10 times). Precipitated.

The precipitate obtained was dissolved in THF again, then reprecipitated in excess n-hexane, and the precipitate was dried in a vacuum oven maintained at 50 ° C. for 24 hours to give the desired product. (Yield 90%).

At this time, the weight average molecular weight (Mw) of the obtained product was 11080, and polydispersity was 1.8.

Experimental Example 4 Synthesis of Terpolymer

The copolymer (10 g) and ethyl vinyl ether (6 g) synthesized in Experimental Example 3 were dissolved in THF (100 mL), and then a small amount of sulfuric acid was added thereto, followed by reaction at room temperature for about 8 hours. After the reaction was completed, the reaction was precipitated while slowly dropping in excess water, neutralized with sodium bicarbonate and the precipitate was filtered using a glass filter.

The precipitate was redissolved in THF solution and then reprecipitated in n-hexane (10-fold) and the precipitate was dried for 24 hours in a vacuum oven maintained at 50 ° C. to afford the desired product. (Yield 90%)

At this time, the weight average molecular weight (Mw) of the obtained product was 12100, and polydispersity was 1.8.

Experimental Example 5 Synthesis of Terpolymer

The copolymer (10 g) and 1,2-dihydropyran (7 g) synthesized in Experimental Example 3 were dissolved in THF (100 mL), and then a small amount of p-toluenesulfonic acid was added thereto, followed by about 12 hours at room temperature. Reacted. After the reaction was completed, the reaction was purified in the same manner as in Experiment 4. (Yield 90%)

At this time, the weight average molecular weight (Mw) of the obtained product was 12500, and polydispersity was 1.85.

Experimental Example 6 Synthesis of Terpolymer

The copolymer (10 g) and di-t-butyl dicarbonate (18 g) synthesized in Experimental Example 3 were dissolved in THF (100 mL), and then pyridine (3.5 g) was added thereto, followed by reaction at room temperature for about 12 hours. I was. After the reaction was completed, the reactants were purified in the same manner as in Experiment 4 except that the reaction was neutralized with HCl. (Yield 85%)

At this time, the weight average molecular weight (Mw) of the obtained product was 13200, and polydispersity was 1.83.

Experimental Example 7 Preparation of Photoresist Composition and Photo Etching Process Using the Same

Terpolymer (1.0 g) synthesized in Experimental Example 4, triphenylsulfonium triflate (TPSOTf) (20 mg), which is PAG, and triisobutylamine (5 mg), which is an organic base, were used as PGMEA (propylene glycol monomethyl ether acetate) ( 8.0 g) dissolved in a solvent and completely dissolved, and then filtered using a 0.2 µm membrane filter to obtain a photoresist composition. The resulting photoresist composition was coated on a silicon wafer to a thickness of about 0.3 μm.

Thereafter, the wafer coated with the photoresist composition was soft baked at a temperature of 100 ° C. for 90 seconds, exposed using a KrF excimer laser (NA = 0.45, sigma = 0.7), and then 90 seconds at a temperature of 110 ° C. During the post-exposure bake (PEB).

Thereafter, it was developed for about 60 seconds using a 2.38 wt% TMAH solution to form a resist pattern.

As a result, a 0.30 mu m line and space pattern (1: 1) could be formed with an exposure energy of 30 mJ / cm 2 dose. The material layer was etched using the thus formed photoresist pattern. The collapse of the photoresist pattern was not found, and the etching resistance was also increased to form a material layer pattern having a desired critical dimension, that is, a material layer pattern having an excellent pattern profile.

Experimental Example 8 Preparation of Photoresist Composition and Photo Etching Process Using the Same

The terpolymer synthesized in Example 4 (1.0 g), triphenylsulfonium triflate (TPSOTf) (10 mg) and DAM-301 (20 mg) as PAG, triisobutylamine (5 mg) as an organic base. ) And completely dissolved in PGMEA (8.0 g) solvent, and then filtered using a 0.2 ㎛ membrane filter to obtain a photoresist composition. The resulting photoresist composition was coated on a silicon wafer to a thickness of about 0.3 μm.

Thereafter, as a result of exposure under the same conditions as in Example 7, a 0.30 µm line and space pattern (1: 1) could be formed at an exposure energy of 45 mJ / cm 2 dose.

Experimental Example 9 Preparation of Photoresist Composition and Photo Etching Process Using the Same

Terpolymer (1.0 g) synthesized in Experimental Example 5, triphenylsulfonium triflate (TPSOTf) (10 mg), which is PAG, and DAM-301 (20 mg), triisobutylamine (5 mg) as an organic base. ) And completely dissolved in PGMEA (8.0 g) solvent, and then filtered using a 0.2 ㎛ membrane filter to obtain a photoresist composition. The resulting photoresist composition was coated on a silicon wafer to a thickness of about 0.3 μm.

Subsequently, as a result of exposure under the same conditions as in Example 7, a 0.30 µm line and space pattern (1: 1) could be formed with an exposure energy of 48 mJ / cm 2 dose.

Experimental Example 10 Preparation of Photoresist Composition and Photo Etching Process Using the Same

The terpolymer (1.0 g) synthesized in Experimental Example 6, triphenylsulfonium triflate (TPSOTf) (10 mg) and DAM-301 (Midori Co., Ltd.) (20 mg), PAG, and triethanolamine (5 mg) as organic bases; The mixture was dissolved in a PGMEA (8.0 g) solvent and completely dissolved, and then filtered using a 0.2 µm membrane filter to obtain a photoresist composition. The resulting photoresist composition was coated on a silicon wafer to a thickness of about 0.3 μm.

Thereafter, as a result of exposure under the same conditions as in Example 7, a 0.30 µm line and space pattern (1: 1) could be formed at an exposure energy of 46 mJ / cm 2 dose.

The resist composition according to the present invention ensures sufficient resistance to dry etching to be suitable for use in the manufacture of thin film resists. This is possible because the monomer having a (meth) acrylic acid ester substituted with a naphthalene derivative having a strong resistance to dry etching. Naphthalene derivatives can be used to prepare resist compositions with improved resistance to dry etching over i-line resins, ie novolak resins.

Therefore, after the photoresist pattern is formed using the photoresist composition according to the present invention, a subsequent dry etching process using the photoresist pattern as a mask layer is advantageous in that resistance to dry etching is large and sufficient etching time can be obtained. Therefore, the present invention can be applied not only to the patterning of various thin films, but also usefully applicable to the case of forming a pattern having a deep etching depth when forming a pattern of a device having a very large lower step. Therefore, it can be very useful for manufacturing next-generation semiconductors and various devices.

The present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. Do.

Claims (3)

A photosensitive polymer represented by the formula: and A photoresist composition comprising 1 to 15% by weight of a photoacid generator based on the weight of the polymer. Wherein R ₁ is 1-alkoxyethyl, 1-alkoxypropyl, tetrahydropyranyl, t-butoxycarbonyl or a bulky acetal group of C _{4 to} C ₁₄ , R ₂ is a hydrogen atom or a methyl group, X is a hydrogen atom or a hydroxy group, l / (l + m + n) = 0.4-0.9, m / (l + m + n) = 0.1-0.5, n / (l + m + n) = 0.01-0.4. The photoresist composition of claim 1, wherein R ₁ is a 1-ethoxyethyl group, R ₂ is hydrogen or a methyl group, and X is a hydrogen atom. The photoresist composition of claim 1, further comprising an organic base.