KR20050003604A - Photoresist Composition - Google Patents

Abstract

PURPOSE: A photoresist composition is provided to form a micropattern up to 50 nm and thus to be useful for a photolithographic process employing an EUV light source. CONSTITUTION: The photoresist composition comprises as base resins, a photoresist polymer containing a repeating unit of the formula 1 and a photoresist polymer containing a repeating unit of the formula 2, a photoacid generator and an organic solvent. In the formulas 1 and 2, each of R1, R2, R3, R8, R9 and R10 is hydrogen or methyl, each of R4, R5, R6, R7 and R11 is a substituted linear or branched C1-C10 alkyl, R12 is a substituted linear or branched C1-C10 alkylene, a : b : c is 10-50 mol%: 0-30 mol%: 50-80 mol%, and d : e : f is 10-70 mol%: 10-50 mol%: 10-50 mol%. Such photoresist composition is employed to form a photoresist pattern for a semiconductor device by applying the photoresist composition onto a top portion of a layer to be etched to form a photoresist film, exposing the photoresist film with a light source, and developing the exposed film.

Description

Photoresist Composition

FIELD OF THE INVENTION The present invention relates to photoresist compositions, and more particularly to photoresist polymers suitable for use in photolithography processes using light sources in the far ultraviolet region, particularly EUV (Extreme Ultraviolet, 13 nm) light sources, in the manufacture of microcircuits of highly integrated semiconductor devices. And a photoresist composition containing the polymer.

In order to achieve high sensitivity in the microcircuit forming process of semiconductor manufacturing, chemically amplified deep ultraviolet (DUV) photoresist has recently been in the spotlight, and its composition is sensitive to photoacid generators and acids. It is prepared by blending the matrix polymer.

The action mechanism of the photoresist generates acid when the photo-acid generator receives ultraviolet light from the light source, and the acid or the main chain or side chain of the matrix polymer compound reacts and decomposes or crosslinks in the baking process after exposure. The polarity of is greatly changed, so that the exposed portion and the non-exposed portion have different solubility in the developer. For example, in the case of a negative photoresist, an acid is generated at an exposed part, and the acid generated in this way causes the main chain or side chain of the high molecular compound to crosslink and insoluble, so that it is not dissolved in a subsequent developing process, thereby eliminating the mask image. You can leave a negative image above.

In such a photolithography process, the resolution may form a fine pattern as the wavelength of the light source decreases depending on the wavelength of the light source. Exposure equipment required for pattern formation below 50nm is currently being developed as EUV equipment, and photoresist is also being developed. In the case of the photoresist, since the biggest problem expected when forming a pattern of 50 nm or less is the collapse of the pattern, it is necessary to develop a negative photoresist rather than a positive photoresist.

The present invention is for forming a fine pattern of 50 nm or less, and an object thereof is to provide a negative photoresist composition that can be used in a photolithography process using an EUV light source.

Moreover, an object of this invention is to provide the method of forming a photoresist pattern using the said photoresist composition, and the semiconductor element obtained by such a method.

1 is an NMR spectrum of a photoresist polymer according to an embodiment of the present invention.

Figure 2 is a photoresist pattern photo formed using a photoresist composition according to an embodiment of the present invention.

In order to achieve the above object, the present invention provides a photoresist polymer comprising a polymerizing repeating unit represented by the following Chemical Formula 1, and a negative photoresist composition comprising the polymerized repeating unit represented by the Chemical Formula 2.

[Formula 1]

Where

R ₁ , R ₂ and R ₃ are hydrogen or methyl,

R ₄ , R ₅ , R ₆ and R ₇ are each C 1 -C 10 main or branched substituted alkyl,

a: b: c is 10-50 mol%: 0-30 mol%: 50-80 mol%.

[Formula 2]

Where

R ₈ , R ₉ and R ₁₀ are hydrogen or methyl,

R ₁₁ is C1-C10 main chain or branched substituted alkyl,

R ₁₂ is a main chain or branched substituted alkylene having 1 to 10 carbon atoms,

d: e: f is 10-70 mol%: 10-50 mol%: 10-50 mol%.

Preferred examples of the polymerized repeating unit of Formula 1 include poly (N, N-dimethylacrylamide / 3,3-dimethoxypropene / acrolein), and a preferred example of the polymerized repeating unit of Formula 2 is poly (methyl Methacrylate / 2-hydroxyethyl methacrylate / acrylic acid), poly (methyl methacrylate / 2-hydroxypropyl methacrylate / acrylic acid), poly (ethyl methacrylate / 2-hydroxypropyl methacrylate) / Acrylic acid) or poly (ethyl methacrylate / 2-hydroxyethyl methacrylate / acrylic acid).

The photoresist composition of the present invention includes the photoresist polymers as a base resin, and includes an organic solvent and a photoacid generator.

As the photoacid generator, any compound capable of generating an acid by light may be used, for example, US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (1996. 11.28), EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997), US 5,750,680 (May 12, 1998), US 6,051,678 (April 18, 2000), GB 2,345,286 A (July 5, 2000), US 6,132,926 (October 17, 2000), US 6,143,463 (Nov. 7, 2000), US 6,150,069 (11/21/2000), US 6,180,316 BI (January 30, 2001) , US 6,225,020 B1 (May 1, 2001), US 6,235,448 B1 (May 22, 2001) and US 6,235,447 B1 (May 22, 2001) and the like, and mainly use a sulfur-based or onium salt-based compound do.

Preferably diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenylsulfonium triflate, diphenyl paratoluenylsulfonium tri Plate, Diphenylparaisobutylphenylsulfonium triflate, Diphenylpara-t-butylphenylsulfonium triflate, triphenylsulfonium hexafluoro phosphate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexa Fluoro antimonate, triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate, phthalimidotrifluoromethanesulfonate, dinitrobenzyltosylate, n-decyldisulfone and naphthylimidotrifluoromethanesulfo One or two or more may be included and used in a ratio of 1 to 10% by weight based on the base resin. It is preferable for. When the photoacid generator is used in an amount of 1% by weight or less, the sensitivity of the photoresist to light becomes weak. When the photoacid generator is used in an amount of 10% by weight or more, the photoacid generator absorbs a lot of ultraviolet rays and generates a large amount of acid, thereby obtaining a pattern having a bad cross section. .

In addition, as the organic solvent, any organic solvent commonly used in the photoresist composition may be used, and also includes those disclosed in the above literature, preferably methyl 3-methoxypropionate, ethyl 3-ethoxypropionate. Cypionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone or ethyl lactate are used and are used at a ratio of 700 to 4000% by weight relative to the base resin, to obtain a photoresist film of a desired thickness. .

The present invention also provides a method of forming a photoresist pattern comprising the following steps:

(a) applying the photoresist composition according to the present invention on the etched layer to form a photoresist film;

(b) exposing the photoresist film to an exposure source; And

(c) developing the resultant to obtain a photoresist pattern.

The process may further include a soft bake process before the exposure of step (b), or a post bake process after the exposure of step (b), which is preferably carried out at 70 to 200 ℃. .

In addition, the exposure process is performed using an exposure energy of 1 to 100 mJ / cm ² using not only EUV (13 nm) but also ArF (193 nm), KrF (248 nm), VUV (157 nm), E-beam or ion beam as a light source. It is preferable to carry out.

On the other hand, the developing step (c) in the above may be performed using an alkaline developer, the alkali developer is preferably 0.01 to 5% by weight of TMAH aqueous solution.

The mechanism of action of the negative photoresist according to the present invention generates an acid when the photoacid generator receives ultraviolet light from a light source in the case of an exposed part, and the polymer of Chemical Formula 1, which is a base resin in a post-exposure bake process by the generated acid, is produced. Since the polymer of Formula 2 and the cross-linking reaction is insoluble, it does not melt away in the subsequent development process. On the other hand, since the crosslinking reaction does not occur in the case of non-exposed sites, the mask image may be left as a negative image due to melting and disappearing in a subsequent developing process.

The present invention also provides a semiconductor device manufactured using the photoresist composition of the present invention.

Hereinafter, the present invention will be described in detail by examples. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

Example 1 Preparation of Photoresist Polymer (1)

70 g of N, N-dimethylacrylamide, 30 g of acrolein and 5 g of AIBN were dissolved in 300 g of tetrahydrofuran solvent and reacted at 66 ° C. for 8 hours. After the completion of the reaction, the mixture was dropped in ether to precipitate, which was then filtered and dried in vacuo to obtain 45 g of poly (N, N-dimethylacrylamide / acrolein) as a white solid.

Next, 45 g of the poly (N, N-dimethylacrylamide / acrolein) obtained above was dissolved in 1 L of methanol, 0.5 g of paratoluenesulfonic acid was added thereto, and the mixture was refluxed at 90 ° C. for about 24 hours. Was concentrated.

Then, the concentrated reaction solution was added to 2 L of normal hexane and stirred to cause phase separation between the product and ethyl ether. When the ethyl ether was poured off, the product remained as a mucus at the bottom of the beaker. , N-dimethylacrylamide / 3,3-dimethoxypropene / acrolein) was obtained (see FIG. 1).

Example 2 Preparation of Photoresist Polymer (2)

40 g of methyl methacrylate, 30 g of 2-hydroxyethyl methacrylate, 30 g of acrylic acid and 2.5 g of AIBN were dissolved in 250 g of tetrahydrofuran solvent and 250 g of methyl ethyl ketone solvent, followed by reaction at 66 ° C. for 8 hours. After the completion of the reaction, the mixture was dropped in ether to precipitate, which was then filtered and dried in vacuo to obtain 86 g of a poly (methyl methacrylate / 2-hydroxyethyl methacrylate / acrylic acid) as a white solid. The polystyrene reduced number average molecular weight of obtained poly (methyl methacrylate / 2-hydroxyethyl methacrylate / acrylic acid) was 17,500.

Example 3 Preparation of Negative Photoresist Composition

3 g of poly (N, N-dimethylacrylamide / 3,3-dimethoxypropene / acrolein) obtained in Example 1, poly (methyl methacrylate / 2-hydroxyethyl methacrylate obtained in Example 2) 7 g of triphenylsulfonium triflate as a photoacid generator was dissolved in 130 g of propylene glycol methyl ether acetate (PGMEA) as an organic solvent and filtered through a 0.20 μm filter to obtain a photoresist composition.

Example 4 Photoresist Pattern Formation

The photoresist composition obtained in Example 3 was spin coated on a silicon wafer and then baked at 130 ° C. for 90 seconds. After baking, it was exposed using ASML KrF exposure equipment and then baked again at 130 ° C. for 90 seconds. After completion of the bake, a 100 nm L / S pattern was obtained in which 2.38 wt% of tetramethylammonium hydroxide aqueous solution was developed for 40 seconds, and then no collapse occurred (see FIG. 2).

As described above, in the present invention, by using a negative photoresist composition containing a polymer that causes a crosslinking reaction by an acid generated during exposure, a fine pattern in which a collapse phenomenon does not occur may be formed. Such a photoresist composition of the present invention may be particularly useful in photolithography processes using EUV light sources for pattern formation of 50 nm or less.

Claims (10)

A photoresist polymer comprising a polymerization repeating unit (repeating unit) represented by the following formula (1) as a base resin and a photoresist polymer, a photoacid generator and an organic solvent comprising a polymerization repeating unit represented by the following formula (2) As photoresist composition. [Formula 1] Where R ₁ , R ₂ and R ₃ are hydrogen or methyl, R ₄ , R ₅ , R ₆ and R ₇ are each C 1 -C 10 main or branched substituted alkyl, a: b: c is 10-50 mol%: 0-30 mol%: 50-80 mol%. [Formula 2] Where R ₈ , R ₉ and R ₁₀ are hydrogen or methyl, R ₁₁ is C1-C10 main chain or branched substituted alkyl, R ₁₂ is a main chain or branched substituted alkylene having 1 to 10 carbon atoms, d: e: f is 10-70 mol%: 10-50 mol%: 10-50 mol%. The method of claim 1, The polymerization repeating unit of Formula 1 is poly (N, N-dimethylacrylamide / 3,3-dimethoxypropene / acrolein), and the polymerization repeating unit of Formula 2 is poly (methylmethacrylate / 2-hydroxyethyl Methacrylate / acrylic acid), poly (methyl methacrylate / 2-hydroxypropyl methacrylate / acrylic acid), poly (ethyl methacrylate / 2-hydroxypropyl methacrylate / acrylic acid) and poly (ethyl methacrylate) Rate / 2-hydroxyethyl methacrylate / acrylic acid). The method of claim 1, The photoacid generator is diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenylsulfonium triflate, diphenyl paratoluenyl sulphate Phosphorus Triflate, Diphenylparaisobutylphenylsulfonium Triflate, Diphenylpara-t-butylphenylsulfonium Triflate, Triphenylsulfonium Hexafluoro Phosphate, Triphenylsulfonium Hexafluoro Arsenate, Triphenylsulphate Phosphorous hexafluoro antimonate, triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate, phthalimidotrifluoromethanesulfonate, dinitrobenzyltosylate, n-decyldisulfone and naphthylimidotrifluoro Photoresists, characterized in that one or more compounds selected from the group consisting of methanesulfonates Composition. The method of claim 1, The photoresist composition is a photoresist composition, characterized in that used in 1 to 10% by weight relative to the base resin. The method of claim 1, The organic solvent is selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone and ethyl lactate, alone or in combination. Photoresist composition, characterized in that used. The method of claim 1, The organic solvent is a photoresist composition, characterized in that used at 700 to 4000% by weight relative to the base resin. (a) applying the photoresist composition of claim 1 over the etched layer to form a photoresist film; (b) exposing the photoresist film to an exposure source; And (c) developing the resultant to obtain a photoresist pattern. The method of claim 7, wherein And performing a soft bake process before the exposure of step (b) or a post bake process after the exposure of step (b). The method of claim 7, wherein And the exposure source is selected from the group consisting of EUV, KrF, ArF, VUV, E-beam, X-ray and ion beam. A semiconductor device manufactured using the method of claim 7.