KR100641918B1 - Over-coating Composition for Photoresist and Process for Forming Photoresist Pattern Using the Same - Google Patents

Abstract

The present invention relates to a new photoresist overcoating composition, and more particularly, by introducing a material that stably weakens acid into the overcoating composition, such a material is uniformly diffused into the lower photoresist film. By neutralizing the acid generated much on the upper portion of the photoresist to make the vertical distribution of the acid uniform, a fine and vertical pattern of 100 nm or less can be obtained.

Description

Over-coating Composition for Photoresist and Process for Forming Photoresist Pattern Using the Same}

1A is a cross-sectional view showing the shape of a pattern obtained when the absorbance of a photoresist with respect to a light source is very small.

1B is a cross-sectional view showing the shape of a pattern obtained when the absorbance of a photoresist with respect to a light source is large.

2 is a process chart showing a photoresist pattern forming method according to Comparative Example 2. FIG.

3 is a process chart showing a photoresist pattern forming method according to Comparative Example 3. FIG.

4 is a process chart showing a method of forming a photoresist pattern according to Embodiment 2 of the present invention.

5 is a SEM photograph showing a photoresist pattern according to Comparative Example 2. FIG.

6 is a SEM photograph showing a photoresist pattern according to Comparative Example 3. FIG.

7 is a SEM photograph showing a photoresist pattern according to Comparative Example 4. FIG.

8 is a SEM photograph showing a photoresist pattern according to Example 2 of the present invention.

<Description of the symbols for the main parts of the drawings>

10 semiconductor substrate 20 organic diffuse reflection prevention film

30 photoresist film 32 non-exposed area

34: exposure area 40a, 40b, 40c: photoresist pattern

50: overcoating layer

The present invention relates to a photoresist overcoating composition, and more particularly, by introducing a substance that weakens an acid into the overcoating composition, even when the absorbance of the photoresist to a light source is relatively large, the pattern is not inclined. The present invention relates to a photoresist overcoating composition capable of obtaining a vertical and fine pattern.

In the semiconductor microcircuit manufacturing process using the 248nm light source (KrF), a 150nm L / S microcircuit has already been formed, and efforts are being made to form a pattern of 150nm or less. On the other hand, in order to form a finer circuit, a research on a microcircuit manufacturing process using a low-light source such as ArF (193nm), F ₂ (157nm), EUV (Extremely Ultraviolet (13nm)) is in progress. However, there is a problem that it is not easy to develop a photoresist resin having good transmittance for these wavelengths. For example, photoresists for i-line (365 nm) and KrF (248 nm) are composed of resins with aromatic compounds, which cannot be used because the absorbance for 193 nm is too large. For this reason, photoresists for 193 nm have been developed using acrylic or alicyclic resins containing no aromatic compounds. However, these resins also have a relatively high absorbance at 193 nm, making it difficult to form a good pattern.

FIG. 1A is a cross-sectional view showing a pattern shape after development when the absorbance of a photoresist (photosensitive agent) with respect to a light source is very small. Since the amount of light reaching the upper portion and the lower portion of the photoresist film applied on the etched layer is almost the same, a vertical pattern may be formed. However, when the absorbance of the photoresist to the light source of the photoresist is large, as shown in FIG. 1B, since the amount of light reaching the upper portion of the photoresist film is greater than the lower portion, the amount of acid generated at the upper portion is generated at the lower portion of the chemically amplified photoresist. Since the amount is greater than the amount of acid, the inclined pattern may be formed as shown in FIG. 1B. That is, the inclined pattern is formed because the concentration gradient of the acid generated by the exposure differs depending on its height in the vertical direction.

Therefore, in order to overcome this, most research directions are focused on developing resins with low absorbance for light sources, but the development of such resins has reached its limit, especially when using F ₂ (157 nm) or EUV (13 nm) light sources.

In addition, a resist flow process or an alkali treatment process may be performed to form a pattern having a fine size exceeding an exposure limit. However, in the case of performing the resist flow process, the size of the first contact formed does not have the same size after the flow, but the size thereof varies depending on the density and size of the contact hole. Non-uniform diffusion causes the contact to deform.

Accordingly, the present inventors have been trying to overcome the above problems, when using a material that stably weakens acid to the over-coating material (over-coating material) applied on the photoresist film when forming a photoresist pattern The present invention was completed by finding that the photoresist resin can obtain a vertical and stable fine pattern even if there is some absorbance with respect to the light source.

An object of the present invention is to provide a method capable of forming a vertical and stable fine pattern even when the absorbance of the photoresist resin to the light source is relatively large.

In order to achieve the above object, the present invention provides a method of forming a fine pattern of vertical and 100 nm or less even when the absorbance of a photoresist resin to a light source is relatively large. The present invention provides a composition for photoresist overcoating incorporating a salt compound that serves to stably weaken an acid.

Specifically, the composition for overcoating of the present invention comprises (i) a salt compound of formula (1), (ii) an alkali soluble resin comprising a repeating unit of formula (2), and (iii) distilled water.

[Formula 1]

X ⁺ -Y

[Formula 2]

Where

X is a primary amine, secondary amine or tertiary amine,

Y is a carboxylate or halogen element,

R ₁ and R ₂ are hydrogen or methyl,

R ₃ is C1-C10 main chain or branched substituted alkyl,

The relative ratio of a: b is 2-20 mol%: 80-98 mol%.

The salt compound is a salt of triethylamine (NEt ₃ ) and acetic acid (CH ₃ CO ₂ H) (Et ₃ N ⁺ -O ₂ CCH ₃ ) or a salt of triethylamine (NEt ₃ ) and hydrochloric acid (HCl) ( Et ₃ N ⁺ -Cl), and it is preferable to use a resin containing a repeating unit of poly (acrylic acid / methyl acrylate) or poly (acrylic acid / methyl methacrylate) as the alkali-soluble resin. desirable.

In addition, the content of the salt compound is 0.1 to 10% by weight based on the total composition, the content of the alkali soluble resin is 1 to 10% by weight based on the total composition, preferably the content of the salt compound is 0.12 to the total composition It is 2 weight%, and content of alkali-soluble resin is 2-3 weight% with respect to the whole composition.

When using the composition for overcoating of the present invention, the principle of obtaining a vertical and fine pattern is as follows.

When the transmittance of the photoresist itself is low, a greater amount of acid is generated in the upper portion of the photoresist film than in the lower portion (FIG. 1b). In the present invention, the salt compound represented by Chemical Formula 1 in the overcoating composition has a lower photoresist. It spreads uniformly into the film and neutralizes the upper part of the photoresist film, which has a relatively high amount of acid. That is, since the salt compound of Formula 1 is diffused, the amount of the salt compound diffused is also increased at the upper portion of the photoresist film and smaller at the lower portion, so that the vertical distribution of the acid in the photoresist film becomes uniform. Vertical and fine patterns can be obtained.

The present invention also provides a method of forming a photoresist pattern using the above-described overcoating composition, which includes the following processes:

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

(b) coating the photoresist overcoating composition on the photoresist film to form an overcoating film;

(c) exposing the result; And

(d) developing the resultant to obtain a desired ultrafine pattern.

In this case, before the photoresist film is formed in the step (a), a process of forming an organic diffuse reflection prevention layer on the etched layer may be further performed.

In the above process, the polymer included in the photoresist composition of the present invention may be any chemically amplified polymer, and may be used in 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 (May 12, 1998), US 6,051,678 (April 2000) 18), GB 2,345,286 A (July 5, 2000), US 6,132,926 (October 17, 2000), US 6,143,463 (November 7, 2000), US 6,150,069 (November 21, 2000), US 6,180,316 BI (2001. 1. 30), 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 cycloolefin-based comonomers A polymer in the form of addition polymerization to keep the ring structure in the main chain without breaking, a polymer in which a substituent having a ring is attached to an acryl-based side chain, or a polymer in which a substituent having a ring is attached to a methacrylic side chain Including Is preferred.

Meanwhile, the method may further include a soft bake process before the exposure of step (c), or a post bake process after the exposure of step (b), and the baking process is preferably performed at 70 to 200 ° C. .

In addition, light sources used in the exposure process include ArF (193 nm), KrF (248 nm), F ₂ (157 nm), EUV (13 nm), E-beam, X-ray or ion beam.

The present invention also provides a semiconductor device manufactured using the overcoating composition of the present invention described above.

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

Comparative Example 1.

2.5 g of poly (acrylic acid / methyl methacrylate) (see 2002, SPIE, pp212-220) and 0.14 g of L-proline were dissolved in 100 g of distilled water to prepare a composition for overcoating.

Example 1.

2.5 g of poly (acrylic acid / methyl methacrylate) (see 2002, SPIE, pp212-220) and salts of triethylamine (NEt ₃ ) with acetic acid (CH ₃ CO ₂ H) (Et ₃ N ⁺ -O ₂ CCH ₃ ) 0.14g was dissolved in 100g of distilled water to prepare a composition for overcoating according to the present invention.

Comparative Example 2.

DARC-20, an organic antireflective coating composition of Dongjin Semichem, was spin-coated on the semiconductor substrate 10 and baked at 240 ° C. for 90 seconds to form an organic antireflective coating 20 having a thickness of 350 Å. Next, TOK TArF_7039 (commercially available) photosensitive agent containing a PR polymer in the form of a substituent having a ring attached to the side chain of the methacryl-based on the organic diffuse reflection prevention film 20, and then baked at 120 ℃ 90 seconds photoresist The string film 30 was formed. After baking, the non-exposed region 32 and the exposed region 34 were formed by using an ASF ArF exposure apparatus, and then the exposed region 34 was developed using a TMAH 2.38 wt% developer, thereby forming a photoresist pattern ( 40a) was obtained (see process diagram of FIG. 2). 5 is a SEM photograph showing a photoresist pattern according to Comparative Example 2, showing that a contact hole pattern having a size of 120 nm was obtained.

Comparative Example 3.

DARC-20, an organic antireflective coating composition of Dongjin Semichem, was spin-coated on the semiconductor substrate 10 and baked at 240 ° C. for 90 seconds to form an organic antireflective coating 20 having a thickness of 350 Å. Next, TOK TArF_7039 (commercially available) photosensitive agent containing a PR polymer of a form in which a substituent having a ring is attached to the side chain of a methacryl-based on the organic diffuse reflection prevention film 20, and then baked at 120 ℃ for 90 seconds to photoresist The film 30 was formed. After baking, the non-exposed area 32 and the exposed area 34 were formed by exposing using ASML ArF exposure equipment, and then sprinkled with 2.38% by weight of TMAH solution on the resultant. After the alkali treatment, the solution was further baked at 120 ° C. for 90 seconds.

The photoresist pattern 40b was obtained by developing the exposure area | region 34 using TMAH 2.38 weight% developing solution after baking (refer FIG. 3 process drawing). 6 is a SEM photograph showing a photoresist pattern according to Comparative Example 3, which shows that the contact hole is severely deformed due to non-uniform diffusion of TMAH compared to FIG. 5. .

Comparative Example 4.

DARC-20, an organic antireflective coating composition of Dongjin Semichem, was spin-coated on the semiconductor substrate 10 and baked at 240 ° C. for 90 seconds to form an organic antireflective coating 20 having a thickness of 350 Å. Next, TOK TArF_7039 (commercially available) photosensitive agent containing a PR polymer of a form in which a substituent having a ring is attached to the side chain of a methacryl-based on the organic diffuse reflection prevention film 20, and then baked at 120 ℃ for 90 seconds to photoresist The film 30 was formed. After baking, the overcoating composition prepared in Comparative Example 1 was coated on the photoresist layer 30 and then baked at 70 ° C. for 60 seconds to form an overcoating layer 50. After baking, the non-exposed region 32 and the exposed region 34 were formed by using an ASF ArF exposure apparatus, and then the exposed region 34 was developed using a TMAH 2.38 wt% developer, thereby forming a photoresist pattern ( 40c) was obtained (see process diagram of FIG. 4). FIG. 7 is a SEM photograph showing a photoresist pattern according to Comparative Example 4, and the size of the contact hole is reduced compared to FIG. 5, and the size of the contact hole is uniform, but there is still a problem in terms of fidelity of the contact for the actual process. I could see that. That is, here, the same process as in the embodiment of the present invention is performed to form a photoresist pattern, but L-proline, which is a kind of amino acid rather than a salt compound, is added to the overcoating composition.

Example 2.

DARC-20, an organic antireflective coating composition of Dongjin Semichem, was spin-coated on the semiconductor substrate 10 and baked at 240 ° C. for 90 seconds to form an organic antireflective coating 20 having a thickness of 350 Å. Next, TOK TArF_7039 (commercially available) photosensitive agent containing a PR polymer of a form in which a substituent having a ring is attached to the side chain of a methacryl-based on the organic diffuse reflection prevention film 20, and then baked at 120 ℃ for 90 seconds to photoresist The film 30 was formed. After baking, the overcoating composition prepared in Example 1 was coated on the photoresist layer 30 and then baked at 70 ° C. for 60 seconds to form an overcoating layer 50. After baking, the non-exposed area 32 and the exposed area 34 are formed by using an ASF ArF exposure apparatus, and then the exposed area 34 is developed using a TMAH 2.38 wt% developer to form the photoresist pattern 40c. ) Was obtained (see the process diagram in FIG. 4). FIG. 8 is a SEM photograph showing a photoresist pattern according to Example 2, which shows that the size of the contact hole is reduced compared to FIG. 5, and the contact hole is uniform, so that it can be applied to an actual process.

As described above, when the composition for photoresist overcoating of the present invention is used, the salt compound contained in the overcoating composition is uniformly diffused in the lower photoresist film to neutralize a large amount of acid generated on the photoresist film. By making the vertical distribution of the acid uniform, the fine and vertical pattern of 100 nm or less can be obtained.

Claims (12)

A composition for photoresist overcoating, comprising: (i) a salt compound of formula 1, (ii) an alkali soluble resin comprising a polymerization repeating unit of formula (2), and (iii) distilled water. [Formula 1] X ⁺ -Y [Formula 2]

Where X is a primary amine, secondary amine or tertiary amine, Y is a carboxylate or halogen element, R ₁ and R ₂ are hydrogen or methyl, R ₃ is C1-C10 main chain or branched substituted alkyl, The relative ratio of a: b is 2-20 mol%: 80-98 mol%. The method of claim 1, The salt compound of Formula 1 is a salt of triethylamine (NEt ₃ ) and acetic acid (CH ₃ CO ₂ H) (Et ₃ N ⁺ -O ₂ CCH ₃ ); Or a salt (Et ₃ N ⁺ -Cl) of triethylamine (NEt ₃ ) and hydrochloric acid (HCl) composition for photoresist overcoating. The method of claim 1, The polymerization repeating unit of Formula 2 is a poly (acrylic acid / methyl acrylate) or a poly (acrylic acid / methyl methacrylate) composition for photoresist overcoating, characterized in that. The method of claim 1, The content of the salt compound is 0.1 to 10% by weight based on the total composition, the content of the alkali soluble resin is 1 to 10% by weight based on the total composition, the composition for the photoresist overcoating. The method of claim 4, wherein The content of the salt compound is 0.12 to 2% by weight based on the total composition, the content of the alkali soluble resin is 2 to 3% by weight based on the total composition, the composition for the photoresist overcoating. (a) applying an alkali poorly soluble chemically amplified photoresist composition over the etched layer to form a photoresist film; (b) coating the photoresist overcoating composition of claim 1 on the photoresist film to form an overcoating film; (c) exposing the resultant to an exposure source; And (d) developing the resultant to obtain a desired ultrafine pattern. The method of claim 6, Before forming the photoresist film in the step (a), further comprising the step of forming an organic diffuse reflection prevention film on the etched layer further. The method of claim 6, The alkali poorly soluble chemically amplified photoresist composition is a polymer in which cycloolefin-based comonomers are additionally polymerized to maintain a ring structure without breaking the ring structure, a polymer in which a substituent having a ring is attached to an acrylic side chain, and a mat And a photoresist polymer selected from the group consisting of polymers in which a substituent having a ring is attached to an acrylic side chain. The method of claim 6, And performing a soft bake process before the exposure of step (c) or a post bake process after the exposure of step (c). The method of claim 9, The baking process is a photoresist pattern forming method, characterized in that performed at 70 to 200 ℃. The method of claim 6, The exposure source is a photoresist pattern forming method is selected from the group consisting of ArF (193nm), KrF (248nm), F ₂ (157nm), EUV (13nm), E-beam, X-ray and ion beam. . The semiconductor device manufactured by the method of Claim 6.

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