KR100811393B1 - Photoresist additive for inhibiting pattern collapse and photoresist composition containing the same - Google Patents

Abstract

The present invention relates to a photoresist additive for improving pattern collapse and a photoresist composition containing the same. More particularly, the pattern collapse is improved by lowering the surface tension of the photoresist itself to increase adhesion between the photoresist pattern and the etched layer. It relates to a photoresist additive used for the purpose of improving, a photoresist composition containing the same and a pattern forming method using the same.

When the salt compound, which is a photoresist additive according to the present invention, is added to the photoresist composition to form a photoresist pattern, the salt compound lowers the surface tension of the photoresist itself, thereby increasing adhesion between the etched layer and the photoresist, thereby causing a pattern collapse. Can be improved.

Description

Photoresist additive for inhibiting pattern collapse and photoresist composition containing same {Photoresist additive for inhibiting pattern collapse and photoresist composition containing the same}

1 is a photoresist pattern photo formed by Example 1 according to the present invention.

Figure 2 is a photoresist pattern photo formed by Example 2 according to the present invention.

Figure 3 is a photoresist pattern photo formed by Example 3 according to the present invention.

4 is a photoresist pattern photo formed by Example 4 according to the present invention.

5 is a photoresist pattern photo formed by Example 5 according to the present invention.

6 is a photoresist pattern photo formed by Example 6 according to the present invention.

7 is a photoresist pattern photo formed by Example 7 according to the present invention.

8 is a photoresist pattern photo formed by Example 8 according to the present invention.

9 is a photoresist pattern photo formed by Example 9 according to the present invention.

10 is a photoresist pattern photo formed by the comparative example.

The present invention relates to a photoresist additive for improving pattern collapse and a photoresist composition containing the same. More specifically, the pattern collapse is enhanced by lowering the surface tension of the photoresist itself to increase adhesion between the photoresist pattern and the etched layer. It relates to a photoresist additive used for the purpose of improving the photoresist composition containing the same, and a pattern forming method using the same.

In recent years, as the device becomes more and more fine, the coating thickness of the photoresist is also decreasing. Also, since the coating thickness of the photoresist is reduced, the formation of the circuit is difficult because the etching layer is not effectively removed in the subsequent etching process. There is a problem that becomes impossible. As a solution to this, a new etching process or a hard mask process may be further introduced, which causes a problem of increasing production cost, and an aspect ratio (photoresist thickness, that is, the height / line width of the formed pattern). Increasing the problem causes the pattern to collapse.

Meanwhile, when a general method of forming a photoresist pattern on a semiconductor substrate is roughly described, first, an etching target layer is formed on a semiconductor substrate, and then a photoresist film is formed on the etching target layer, and the photoresist layer is exposed and developed to expose a portion of the etching target layer. A photoresist pattern is formed to expose the film. In this case, when a positive photoresist film is used, the photoresist film is removed from the exposure area by a chemical reaction between the developer and the photoresist film to form a photoresist pattern.

After forming the photoresist pattern as described above, the semiconductor substrate is cleaned by spraying deionized water from the top of the spin apparatus while spinning the semiconductor substrate. In this process, the surface tension of the ultrapure water is high and the pattern is removed. Falling problem occurs.

To this end, efforts have been made to improve the photoresist pattern collapse by adding additives or surfactants to the ultrapure water to lower the surface tension of the ultrapure water, but this requires the creation of a new ultrapure water supply line in light of the existing centrally supplied ultrapure water supply system. I have a problem.

For this reason, many efforts have been made to improve the adhesion of the photoresist to the substrate, but no clear results are obtained.

The collapse of the photoresist pattern is that when the height of the formed photoresist pattern exceeds the critical height, the capillary force exceeds the elastic force of the photoresist itself, causing the pattern to collapse.

Therefore, the pattern collapse can be prevented by increasing the elasticity inside the photoresist or lowering the surface tension of the photoresist itself to increase the adhesion between the etched layer and the photoresist.

Accordingly, the present inventors have been trying to focus on lowering the surface tension of the photoresist itself in a solution for the above problems, and by adding a specific salt compound to the photoresist composition to lower the surface tension of the photoresist itself, The present invention was completed by finding that the adhesion between the photoresists can be improved to improve the pattern collapse phenomenon.

It is an object of the present invention to provide a photoresist additive and a photoresist composition containing the same, which are used for the purpose of improving the collapse of the photoresist pattern by lowering the surface tension of the photoresist.

It is also an object of the present invention to provide a method of forming a photoresist pattern using the photoresist composition and a semiconductor device obtained by the method.

In order to achieve the above object, the present invention first provides a photoresist additive for improving pattern collapse.

As the additive of the present invention, a salt compound selected from the group consisting of thiazolium salt, indolium salt, and pyrylium salt may be used alone or in combination.

Preferred examples of the thiazolium salts include salt compounds of the following Chemical Formula 1a, and preferred examples of indoleium salts include salt compounds of the following Chemical Formulas 1b, 1c, 1d, 1g, and 1h, and preferred examples of pyrilium salts. And salt compounds represented by the following formulas (1e), (1f) and (1i).

2- [3- (3-ethyl-2 (3H) -benzothiazolidene) -2-methyl-1-propenyl] -3- [3- (sulfooxy) -butyl] benzothiazolium hydride of formula 1a Rockside;                     

[Formula 1a]

2- [2- [2-chloro-3-[(1,3-dihydro-3,3-dimethyl-1-alkyl-2H-indole-2-ylidene) ethylidene] -1-cyclo of formula 1b Hexen-1-yl] ethenyl] -3,3-dimethyl-1-alkylindolinium iodide;

[Formula 1b]

2- [2- [3- (1,3-dihydro-3,3-dimethyl-1-alkyl-2H-indol-2-ylidene) ethylidene] -2- (phenylthio) -1 of formula 1c -Cyclohexen-1-yl] ethenyl] -3,3-dimethyl-1-alkylindolinium iodide;

[Formula 1c]

1,1'-alkyl-3,3,3 ', 3'-tetramethyl-4,5,4', 5'-dibenzoindo-dicarbocyanine of Formula 1d;

[Formula 1d]

4- [2- [3-[(2,6-diphenyl-4H-thiopyran-4-ylidene) ethylidene] -2-phenyl-1-cyclohexen-1-yl] ethenyl of the formula 1e] -2,6-diphenylthiopyryllium tetrafluoroborate;

[Formula 1e]

4- [2- [2-chloro-3-[(2,6-diphenyl-4H-thiopyran-4-ylidene) ethylidene] -1-cyclohexen-1-yl} ethenyl of Formula 1f] -2,6-diphenylthiopyryllium tetrafluoroborate;                     

[Formula 1f]

1-alkyl-2- [2- [3-[(1-alkyl-6-chlorobenz [cd] indole-2 (1H) -ylidene) ethylidene] -2-chloro-1-cyclohexene of formula 1 g -1-yl] ethenyl] -6-chlorobenz [cd] indoleium tetrafluoroborate;

[Formula 1g]

6-chloro-2- [2- [3-[(6-chloro-1-alkylbenz [cd] indole-2 (1H) -ylidene) ethylidene] -2-phenyl-1-cyclopentene of formula 1h -1-yl] ethenyl] -1-alkylbenz [cd] indoleium tetrafluoroborate;                     

[Formula 1h]

8-[[3-[(6,7-dihydro-2,4-diphenyl-5H-1-benzopyran-8-yl) methylene] -2-phenyl-1-cyclopentene-1- of Formula 1i Il] methylene] -5,6,7,8-tetrahydro-2,4-diphenyl-1-benzopyryllium tetrafluoroborate (if m = 1); And 8-[[3-[(6,7-dihydro-2,4-diphenyl-5H-1-benzopyran-8-yl) methylene] -2-phenyl-1-cyclohexen-1-yl] Methylene] -5,6,7,8-tetrahydro-2,4-diphenyl-1-benzopyryllium tetrafluoroborate (if m = 2).

Formula 1i]

Where

R is a straight or branched alkyl group of C ₁ -C ₁₀ .

The photoresist additive, which is a salt compound of Formulas 1a to 1i, is added to the photoresist composition to lower the surface tension of the photoresist itself, thereby improving the adhesion between the layer and the photoresist, thereby improving the pattern collapse phenomenon.

The present invention also provides a photoresist composition comprising (i) a photoresist additive selected from the group consisting of the above formulas (Ia) to (i) a base resin (iii) an organic solvent and optionally (iv) a photoacid generator. do. That is, the additive according to the present invention can be used in conventional photoresist compositions, and is particularly effective for chemically amplified photoresist compositions.

Such a photoresist composition may further include other additives and the like, as necessary, including the above elements.

First, the photoresist additive is preferably used in a ratio of 0.01 to 0.2% by weight based on the base resin. If too large amounts of additives of 0.2% by weight or more are used, there is a problem in that the pattern shape is deformed due to the increase in the resolution and absorption of the photoresist.

In addition, the base resin, the photoacid generator and the organic solvent included in the photoresist composition may be any one used in a conventional chemically amplified photoresist composition, for example, US 5,212,043 (May 18, 1993), WO 97 / 33198 (September 12, 1997), WO 96/37526 (Nov. 28, 1996), EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997), US 5,750,680 (1998. 5.12), GB 2,340,830 A (March 1, 2000), US 6,051,678 (April 18, 2000), GB 2,345,286 A (May 5, 2000), US 6,132,926 (October 17, 2000), US 6,143,463 ( 7 November 2000), US 6,150,069 (11/21/2000), US 6,180,316 B1 (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.

In particular, the base resin has a cycloolefin backbone structure and functions as a functional group, for example, an acid-sensitive protecting group that acts as a dissolution inhibitor, and a carboxylic acid for improving light sensitivity. It is preferable that the cycloolefin-based comonomers having groups include repeating units in which the ring structure of the cyclopolymerized cycloolefin backbone, which is addition-polymerized, is maintained in the main chain without breaking, and more preferably, it is used for controlling substrate adhesion and sensitivity. It is preferred to include cyclo olefin comonomers having oxyalkyl functional groups.

For example, a base resin including a polymerized repeating unit represented by Chemical Formula 2 may be used, in which 2-hydroxyethyl bicyclo [2.2.1] hept-5 as shown in Chemical Formula 2a to improve adhesion to a substrate. -En-2-carboxylate (n = 1) or preferably 2-hydroxyethyl bicyclo [2.2.2] oct-5-ene-2-carboxylate (n = 2) comonomer .

[Formula 2]

[Formula 2a]

Where

R ₁ is an acid sensitive protecting group;

R ₂ is a C ₁ -C ₁₀ hydroxy alkyl group;

a: b: c: d is 0-50 mol%: 20-50 mol%: 1-30 mol%: 0-45 mol%;

n is 1 or 2.

The acid-sensitive protecting group is a group that can be detached by an acid. When an acid-sensitive protecting group is attached, the photoresist is prevented from being dissolved by an alkaline developer, and the sensitive protecting group is released by an acid generated by exposure. Can be dissolved in an alkaline developer.

Such acid-sensitive protecting groups can be any so long as they can play such roles, including those disclosed in the above cited references, preferably t-butyl, tetrahydropyran-2-yl, 2-methyl tetra Hydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl, 1- Ethoxy-1-methylethyl, 1-methoxyethyl, 1-ethoxyethyl, t-butoxy ethyl, 1-isobutoxyethyl or 2-acetylment-1-yl and the like.

As the photoacid generator, diazomethane-based compounds, glyoxime-based compounds and benzyltosylate-based compounds having relatively low absorbance at 157 nm and 193 nm, for example, phthalimidotrifluoromethanesulfonate and dinitrobenzyltosylate n-decyldisulfone and naphthylimidotrifluoromethanesulfonate are mainly used; Diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxy phenyl triflate, diphenyl paratoluenyl Triflate, Diphenylparaisobutylphenyl Triflate, Diphenylpara-t-butylphenyl Triflate, Triphenylsulfonium Hexafluor Phosphate, Triphenylsulfonium Hexafluor Arsenate, Triphenylsulfonium Hexafluor Antimonate , Triphenylsulfonium triflate or dibutylnaphthylsulfonium triflate compound may also be used.

The photoacid generator is preferably used in a ratio of 0.05 to 10% by weight relative to the photoresist polymer, when the amount of 0.05% by weight or less is used, the sensitivity of the photoresist to light is used and an amount of 10% by weight or more may be used. In this case, the photoacid generator absorbs a lot of ultraviolet rays and a large amount of acid is generated to obtain a pattern having a bad cross section.

In addition, the organic solvent is preferably methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone or ethyl lactate. It is used in a ratio of 200 to 1000% by weight based on the photoresist polymer, which is used to obtain a photoresist film having a desired thickness. For example, when the organic solvent is used in an amount of 800% by weight based on the photoresist polymer, the thickness of the photoresist is about 0.3 μm. Becomes

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

(a) coating 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 exposed photoresist film 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 exposed to 0.1 to 50mJ / cm ² using VUV (157nm), ArF (193nm), KrF (248nm), EUV (13nm), E-beam, X-rays or ion beam as an exposure source It is preferably carried out with energy.

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

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 Composition and Formation of Photoresist Pattern (1)

The compound of formula 1a (0.001 g) as an additive according to the present invention, the compound of formula 2 (10 g) as a base resin, 1% by weight of trioctylamine solution (1 g of trioctylamine to 99 g of propylene glycol methyl ether acetate) Dissolved solution) (0.2 g) and phthalimidotrifluoromethanesulfonate (0.06 g) and triphenylsulfonium triflate (0.06 g) as a photoacid generator were dissolved in 100 g of propylene glycol methyl ether acetate as an organic solvent. Filtration with a filter produced a photoresist composition.

The photoresist composition thus obtained was spin-coated on the etching target layer of the silicon wafer to prepare a photoresist thin film, followed by soft baking for 90 seconds in an oven or hot plate at 140 ° C., and then exposed to light using an ArF laser exposure apparatus, followed by 90 ° at 140 ° C. Post bake again for a second. The wafer thus exposed was immersed in a 2.38 wt% TMAH aqueous solution for 40 seconds and developed to obtain a 110 nm L / S ultrafine photoresist pattern (see FIG. 1).

Example 2 Preparation of Photoresist Composition and Forming Photoresist Pattern (2)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1b (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 2).

Example 3 Preparation of Photoresist Composition and Formation of Photoresist Pattern (3)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1a (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S second using the same. A fine photoresist pattern was obtained (see FIG. 3).

Example 4 Preparation of Photoresist Composition and Forming Photoresist Pattern (4)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1d (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 4).

Example 5 Preparation of Photoresist Composition and Formation of Photoresist Pattern (5)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1e (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 5).

Example 6 Preparation of Photoresist Composition and Formation of Photoresist Pattern (6)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1f (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 6).

Example 7 Preparation of Photoresist Composition and Formation of Photoresist Pattern (7)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1g (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 7).

Example 8 Preparation of Photoresist Composition and Photoresist Pattern Formation 8

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1h (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 8).

Example 9 Preparation of Photoresist Composition and Forming Photoresist Pattern (9)

A photoresist composition was prepared in the same manner as in Example 1, except that the compound of Formula 1i (0.001 g) was used instead of the compound of Formula 1a, which is an additive of Example 1, and 110 nm L / S was used. An ultrafine photoresist pattern was obtained (see FIG. 9).

Comparative Example: Preparation of Photoresist Composition and Forming Photoresist Pattern (10)

A photoresist composition was prepared in the same manner as in Example 1, except that the additive was not used unlike in Example 1, and a 110 nm L / S ultrafine photoresist pattern was obtained using the same. Unlike the pattern, the pattern collapsed (see FIG. 10).

As described above, when a photoresist pattern is formed by adding a photoresist composition to the salt compound, which is a photoresist additive, according to the present invention, the salt compound lowers the surface tension of the photoresist itself, thereby reducing the adhesion between the etched layer and the photoresist. To increase the pattern collapse.

Claims (9)

In a photoresist composition comprising a chemically amplified photoresist polymer having a cyclo olefin back bone structure, a photoacid generator and an organic solvent, the composition is an additive of thiazolilium salt and indolium salt. and at least one salt compound selected from the group consisting of salts and pyrylium salts. The method of claim 1, The salt compound is a photoresist composition, characterized in that selected from the group consisting of the formula 1a to 1i. [Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

[Formula 1f]

[Formula 1g]

[Formula 1h]

Formula 1i]

Where R is a straight or branched alkyl group of C ₁ -C ₁₀ , and m is 1 or 2. The method of claim 1, The photoresist additive is a photoresist composition, characterized in that used in a ratio of 0.01 to 0.2% by weight relative to the base resin. delete The method of claim 1, The chemically amplified photoresist polymer photoresist composition, characterized in that it comprises a polymerization repeating unit of the formula (2). [Formula 2]

Where R ₁ is an acid sensitive protecting group; R ₂ is a C ₁ -C ₁₀ hydroxy alkyl group; a: b: c: d is 0-50 mol%: 20-50 mol%: 1-30 mol%: 0-45 mol%; n is 1 or 2. (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 exposed photoresist film to obtain a desired pattern. The method of claim 6, And performing a soft bake process before the exposure of step (b) and a post bake process after the exposure of step (b). The method of claim 6, The exposure source is a photoresist pattern forming method, characterized in that selected from the group consisting of VUV, ArF, KrF, EUV, E-beam, X-ray and ion beam. A semiconductor device manufactured using the method of claim 6.

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