KR20080009939A - Manufacturing method of semiconductor device using immersion lithography process - Google Patents

Abstract

A method for manufacturing a semiconductor device using an immersion lithography process is provided to obtain vertical patterns by improving the top loss of a photoresist pattern by neutralizing acid existing on a surface of a resist layer. A method for manufacturing a semiconductor device using an immersion lithography process includes the steps of: forming the resist film on an etched layer of a semiconductor wafer; coating an aqueous solution including a basic compound and a non-ionic surfactant on a surface of the resist film; performing an exposing process by using immersion lithography equipment; baking the product of third step after exposure; and obtaining a desired pattern by developing the product of the fourth step.

Description

Manufacturing Method of Semiconductor Device Using Immersion Lithography Process

1A to 1C are cross-sectional views showing a method of manufacturing a semiconductor device using an immersion lithography process according to the prior art.

2A to 2D are cross-sectional views illustrating a method of manufacturing a semiconductor device using an immersion lithography process according to the present invention.

3 is a SEM photograph of a photoresist pattern formed by an immersion lithography process according to a comparative example of the present invention.

4A and 4B are SEM photographs of photoresist patterns formed by an immersion lithography process according to an embodiment of the invention.

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

10, 110: semiconductor wafer 20 120: resist film

22, 122: non-exposure area 24, 124: exposure area

130: surface treatment layer 40, 140: immersion lithography fluid

50, 150 photoresist pattern

The present invention relates to a method of manufacturing a semiconductor device using an immersion lithography process, and more particularly, to improve the top loss phenomenon of the photoresist pattern formed by the immersion lithography process and to bubble-deposit the wafer surface. The present invention relates to a method of manufacturing a semiconductor device capable of reducing a defect defect phenomenon.

In order to manufacture a semiconductor device which is gradually miniaturized, the size of the pattern is also gradually decreasing. In the meantime, research has been conducted toward developing an exposure apparatus and a corresponding resist in order to obtain a fine pattern.

In exposure equipment, an exposure light source is mainly a KrF of 248 nm wavelength or an ArF light source of 193 nm wavelength is applied to the production process, but gradually a short wavelength light source and a lens numerical aperture (F ₂ (157 nm) or EUV (13 nm), etc.) are applied. Efforts have been made to increase the numerical aperture.

However, when a new light source such as F ₂ is employed, a new exposure apparatus is required, which is not efficient in terms of manufacturing cost, and there is a problem that a method of increasing the numerical aperture also lowers the depth of focus.

Recently, immersion lithography processes have been developed to solve this problem. In the conventional exposure process, the exposure equipment uses air having a refractive index of 1.0 as the medium of the exposure beam between the wafer and the resist lens formed thereon, whereas the immersion lithography process uses water having a refractive index of 1.0 or more as an intermediate medium. By using fluids such as H ₂ O) or an organic solvent, the same effect as using a shorter wavelength light source or a lens having a high numerical aperture can be achieved even when using a light source of the same exposure wavelength, and a decrease in depth of focus. none.

The immersion lithography process has an advantage that the depth of focus can be remarkably improved and a smaller fine pattern of less than 60 nm can be formed even using an existing exposure source.

1A to 1C are cross-sectional views illustrating a method of manufacturing a semiconductor device using an immersion lithography process according to the prior art.

Referring to FIG. 1A, a chemically amplified photoresist composition including a chemically amplified photoresist resin and an acid generator is coated on an etched layer (not shown) on a semiconductor wafer 10, and then soft baked to resist resist 20. ).

Referring to FIG. 1B, an exposure process using an exposure apparatus for immersion lithography is performed. It can be seen that the immersion lithography fluid 40 is used as a medium of the exposure beam between the exposure lens (not shown) of the exposure equipment and the semiconductor wafer 10 on which the resist film 20 is formed.

As a result of the exposure process, the non-exposed areas 22 and the exposed areas 24 are formed in the resist film 20. At this time, since the resist film 20 is formed of a chemically amplified photoresist, acid is generated in the exposure region 24 by the photoacid generator in the photoresist.

On the other hand, since the immersion lithography fluid 40 is present on the resist film 20, the immersion lithography fluid 40 is generated in the exposure area 24 on the surface of the resist film 20, that is, the interface between the resist film 20 and the immersion lithography fluid 40. Acid diffuses. That is, acid is present not only in the exposure region 24 but also on the surface of the non-exposure region 22 by diffusion.

Referring to FIG. 1C, the resultant is baked after exposure. As a result, the deprotection group adhering to the resin in the photoresist is detached by the acid generated in the exposure area 24 during the exposure step, so that the exposure area 24 is converted into a property that is dissolved in a developer described later. At this time, the upper portion of the non-exposed region 22 in which the acid is diffused is also converted to the property of dissolving in the developer.

Next, the exposure region 24 is selectively removed using a developer such as a TMAH 2.38 wt% aqueous solution to obtain a desired photoresist pattern 50. At this time, since the upper part of the non-exposed area 22 is also dissolved in the developer, the top loss of the photoresist pattern 50, that is, the upper part of the pattern is shaved and tilted.

As described above, when the photoresist pattern 50 having the top loss is used as a mask in a subsequent process, an etching process of the lower etching layer is caused.

In addition, according to the conventional immersion lithography process, there is a problem that bubble defect occurs due to the surface tension between the semiconductor wafer 10 and the immersion lithography fluid 40 during the exposure process.

Accordingly, the inventors of the present invention have developed a semiconductor device manufacturing method that can reduce the bubble defect and at the same time improve the top loss phenomenon of the pattern generated during the immersion lithography process without expensive equipment development Was completed.

The present invention is designed to improve the top loss phenomenon of the pattern generated during the immersion lithography process and to reduce bubble defects, and to suppress diffusion of acid generated on the surface of the resist film due to the immersion lithography fluid during the exposure process. It is an object of the present invention to provide a method of manufacturing a semiconductor device using a method of neutralizing and washing away acid on the surface of a resist film before performing an exposure process, and reducing the surface tension between the semiconductor wafer and the immersion lithography fluid.

In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device comprising the step of treating the surface of the resist film using an aqueous solution containing a basic compound and a nonionic surfactant before the exposure process using immersion lithography.

Specifically, the semiconductor device manufacturing method according to the present invention

Forming a resist film on the etched layer on the semiconductor wafer;

Coating an aqueous solution containing a basic compound and a nonionic surfactant on the surface of the resist film;

Performing an exposure process using an exposure apparatus for immersion lithography;

Baking the resultant after exposure; And

Developing the result to obtain a desired pattern.

The semiconductor device manufacturing method according to the present invention

The resist film is formed of a chemically amplified photoresist composition comprising a chemically amplified photoresist resin and an acid generator,

Examples of the basic compound include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, n-propylamine, iso-propylamine, n-butylamine, tert-butylamine, di (n -Butyl) amine, ethylenediamine, diethylenediamine, tetraethylenetriamine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, propanolamine, tetramethyl ammonium hydroxide and tetraethyl ammonium hydroxide Using a water-soluble amine selected from the group in an amount of 0.01 to 10% by weight, preferably 0.1 to 2% by weight based on the total aqueous solution,

Examples of the nonionic surfactants include compounds represented by the following Chemical Formula 1, such as polyethylene glycol, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene isooctylcyclo ether, and polyoxyethylene 0.1 to 10% by weight, preferably 0.3 to 3% by weight, based on the total aqueous solution, selected from the group consisting of isooctylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether It is characterized by using the content of;

[Formula 1]

R- (OCH ₂ CH ₂ ) _n -OH

Where

R is H or a hydrocarbon group of 1 to 40 carbon atoms,

n is an integer selected from 10 to 2000,

The weight average molecular weight is 50 to 80000.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

2A to 2D are cross-sectional views illustrating a method of manufacturing a semiconductor device using an immersion lithography process according to the present invention.

Referring to FIG. 2A, a chemically amplified photoresist composition including a chemically amplified photoresist resin and an acid generator is coated on the etched layer (not shown) on the semiconductor wafer 110, and then soft baked to resist resist 120. ).

Referring to FIG. 2B, an aqueous solution containing a basic compound and a nonionic surfactant is coated on the resist film 120 to form a surface treatment layer 130.

The aqueous solution containing the basic compound and the nonionic surfactant forming the surface treatment layer 130 is applied in an amount of 50 to 100 ml when the size of the semiconductor wafer 110 is 200 mm, If the size is 300 mm, it is applied in an amount of 100 to 300 ml.

Examples of the basic compound include water-soluble amines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, n-propylamine, iso-propylamine, n-butylamine, tert-butylamine , Di (n-butyl) amine, ethylenediamine, diethylenediamine, tetraethylenetriamine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, propanolamine, tetramethyl ammonium hydroxide and tetraethyl ammonium hydride Any one selected from the group consisting of the hydroxide may be used alone or in combination, and it is preferable to use in an amount of 0.01 to 10% by weight based on the total aqueous solution, more preferably in an amount of 0.1 to 2% by weight.

The basic compound serves to improve the top loss of the pattern by neutralizing and washing the acid generated on the surface of the resist film 120 to prevent acid from diffusing to the surface of the non-exposed area 122, the content of which is 0.01 weight. If it is less than%, the effect of improving the top loss is insignificant, and if it exceeds 10% by weight, a problem occurs in that a T-top shaped pattern is formed.

In addition, the nonionic surfactant is a compound represented by Formula 1, such as polyethylene glycol, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene isooctylcyclo ether, poly One selected from the group consisting of oxyethylene isooctylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene octylphenyl ether can be used alone or in combination, and 0.1 to 10% by weight of the total aqueous solution. It is preferable to use it in the content of%, More preferably, it is used in the content of 0.3-3 weight%.

In particular, polyoxyethylene stearyl ether and polyoxyethylene oleyl ether are most preferably used because they can lower the surface tension while acting as an antifoaming agent that does not cause foam at all.

The nonionic surfactant serves to reduce the surface tension between the resist film 120 and the immersion lithography fluid, which will be described later. If the content is less than 0.1% by weight, the effect of removing bubble defects is insignificant. If it exceeds%, the surfactant is coated on the resist film 120, so that the immersion lithography fluid is eluted on the wafer surface at the beginning of exposure, thereby causing a temporary change in refractive index. In addition, the effect due to the increase in the amount of use does not appear anymore. Because it is not desirable.

Referring to FIG. 2C, an exposure process using an exposure apparatus for immersion lithography is performed. In this case, it can be seen that the immersion lithography fluid 140 is used between the resist film 120 on the semiconductor wafer 110 and the surface treatment layer 130 as a medium of the exposure beam.

As a result of the exposure process, the non-exposed regions 122 and the exposed regions 124 are formed in the resist film 120. Since the resist film 120 is formed of a chemically amplified photoresist, acid is generated in the exposure region 124 by the photoacid generator in the photoresist.

At this time, since the surface treatment layer 130 by an aqueous solution containing a basic compound and a nonionic surfactant is present on the resist film 120, the basic compound neutralizes and washes away the acid generated on the surface of the resist film 120. The acid does not diffuse to the surface of the non-exposed area 122, so no acid is present on the surface of the non-exposed area 122. In addition, the nonionic surfactant reduces the surface tension between the resist film 120 and the immersion lithography fluid 140.

Referring to FIG. 2D, the resultant is baked after exposure. As a result, the deprotection group adhering to the resin in the photoresist is detached by the acid generated in the exposure area 124 during the exposure process, so that the exposure area 124 is converted into a property that is dissolved in a developer described later.

Next, the exposure region 124 is selectively removed using a developer such as a TMAH 2.38 wt% aqueous solution to obtain a photoresist pattern 150 having a vertical shape.

In the following Examples, a photoresist pattern is formed by treating an aqueous solution containing a basic compound and a nonionic surfactant on a surface of a resist film, and in the comparative example, an aqueous solution containing the basic compound and a nonionic surfactant is used. The result of forming a photoresist pattern without performing this is shown concretely.

Preparation Example 1

1 g of polyoxyethylene (100) stearyl ether (Bridj 700 from Aldrich) and 1 g of triethanolamine were dissolved in 500 g of ultrapure water to prepare an aqueous solution containing a basic compound and a nonionic surfactant.

Preparation Example 2

1 g of polyoxyethylene (20) oleyl ether (Bridj 98 of Aldrich) triethanolamine was dissolved in 500 g of ultrapure water to prepare an aqueous solution containing a basic compound and a nonionic surfactant.

Comparative example

An etched layer was formed on a hexamethyldisilazane (HMDS) -treated silicon wafer, spin-coated a chemically amplified photoresist (PAR955A1), and soft baked in an oven at 100 ° C. for 90 seconds to form a resist film.

Next, the exposure equipment for immersion lithography (AT1400i 0.93NA Dipole 0.97_0.85σ) was exposed and post-baked again in an oven at 105 ° C. for 90 seconds, and then developed in a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 30 seconds. As a result of obtaining a resist pattern, not only the top loss occurred in the photoresist pattern, the pattern was inclined, but also the bubble defect was measured to be about 500 (see FIG. 3).

Example 1

An etched layer was formed on a hexamethyldisilazane (HMDS) -treated silicon wafer, spin-coated a chemically amplified photoresist (PAR955A1), and soft baked in an oven at 100 ° C. for 90 seconds to form a resist film.

Next, an aqueous solution containing the basic compound and the nonionic surfactant obtained in Preparation Example 1 was applied to the resist film surface.

It was then exposed with an exposure equipment for immersion lithography (AT1400i 0.93NA Dipole 0.97_0.85σ), post-baked for 90 seconds in an oven at 105 ° C, and then developed in a 2.38% by weight aqueous tetramethylammonium hydroxide solution for 30 seconds. As a result of obtaining the photoresist pattern, the number of bubble defects occurring in the photoresist pattern was significantly reduced to about 10 and the pattern shape was also vertical (see FIG. 4A).

Example 2

An etched layer was formed on a hexamethyldisilazane (HMDS) -treated silicon wafer, spin-coated a chemically amplified photoresist (PAR955A1), and soft baked in an oven at 100 ° C. for 90 seconds to form a resist film.

Next, an aqueous solution containing the basic compound and the nonionic surfactant obtained in Preparation Example 2 was applied to the resist film surface.

It was then exposed with an exposure equipment for immersion lithography (AT1400i 0.93NA Dipole 0.97_0.85σ), post-baked for 90 seconds in an oven at 105 ° C, and then developed in a 2.38% by weight aqueous tetramethylammonium hydroxide solution for 30 seconds. As a result of obtaining the photoresist pattern, as a result of obtaining the photoresist pattern, the number of bubble defects generated in the photoresist pattern was significantly reduced to about 8 and the pattern shape was also vertical (see FIG. 4B).

On the other hand, the preferred embodiment of the present invention for the purpose of illustration, those skilled in the art will be possible to various modifications, changes, replacements and additions through the spirit and scope of the appended claims, such modifications and changes are as follows It should be regarded as belonging to the claims.

As described above, in the present invention, by treating the surface of the resist film with an aqueous solution containing a basic compound and a nonionic surfactant before the exposure process, the acid present on the surface of the resist film is neutralized to cause top loss of the photoresist pattern. In addition to improving the vertical pattern, it is possible to remove bubble defects on the wafer surface, which is advantageous for the subsequent etching process, resulting in improved semiconductor production yield.

Claims (11)

In the semiconductor device manufacturing method using an immersion lithography process, And treating the surface of the resist film with an aqueous solution containing a basic compound and a nonionic surfactant before the exposure process. The method of claim 1 wherein the method is Forming a resist film on the etched layer on the semiconductor wafer; Coating an aqueous solution containing a basic compound and a nonionic surfactant on the surface of the resist film; Performing an exposure process using an exposure apparatus for immersion lithography; Baking the resultant after exposure; And Developing the resultant to obtain a desired pattern. The method according to claim 1 or 2, The resist film is a semiconductor device manufacturing method, characterized in that formed by a chemical amplification type photoresist resin and a chemical amplification type photoresist composition comprising an acid generator. The method according to claim 1 or 2, The basic compound is a method for manufacturing a semiconductor device, characterized in that the water-soluble amines. The method according to claim 1 or 2, The nonionic surfactant is a semiconductor device manufacturing method characterized in that the compound represented by the formula (1); [Formula 1] R- (OCH ₂ CH ₂ ) _n -OH Where R is H or a hydrocarbon group of 1 to 40 carbon atoms, n is an integer selected from 10 to 2000, The weight average molecular weight is 50 to 80000. The method according to claim 1 or 2, The basic compound is a method of manufacturing a semiconductor device, characterized in that contained in an aqueous solution of 0.01 to 10% by weight. The method of claim 6, The basic compound is a semiconductor device manufacturing method, characterized in that contained in the content of 0.1 to 2% by weight. The method according to claim 1 or 2, The nonionic surfactant is a method for manufacturing a semiconductor device, characterized in that contained in an aqueous solution of 0.1 to 10% by weight. The method of claim 8, The nonionic surfactant is a semiconductor device manufacturing method, characterized in that contained in the content of 0.3 to 3% by weight. The method of claim 4, wherein The water-soluble amines are monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, n-propylamine, iso-propylamine, n-butylamine, tert-butylamine, di (n- Butyl) amine, ethylenediamine, diethylenediamine, tetraethylenetriamine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, propanolamine, tetramethyl ammonium hydroxide and tetraethyl ammonium hydroxide The semiconductor device manufacturing method, characterized in that selected from The method of claim 5, wherein The nonionic surfactants include polyethylene glycol, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene isooctylcyclo ether, polyoxyethylene isooctylphenyl ether, polyoxyethylene lauryl Method of manufacturing a semiconductor device, characterized in that selected from the group consisting of ether, polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

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