KR20060105266A - Method for forming photoresist pattern using immersion lithography process - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a photoresist pattern using an immersion lithography process, wherein a photoresist pattern is immersed in a liquid for immersion lithography for a predetermined time before exposure to form a photoresist pattern through an exposure process. Even without the top anti-reflective film used in the process, the top loss and roughness of the photoresist can be prevented to obtain a stable pattern of a uniform CD. As a result, the efficiency and yield of semiconductor device characteristics can be maximized. have.

Description

Method for Forming Photoresist Pattern Using Immersion Lithography Process

1 is a photoresist pattern photo formed by Example 1.

2 is a photoresist pattern photo formed by Example 2.

3 is a photoresist pattern photo formed by Example 3.

4 is a photoresist pattern photo formed by Example 4.

5 is a photoresist pattern photo formed by Example 5.

6 is a photoresist pattern photo formed by Example 6.

7 is a photoresist pattern photo formed by Example 7.

The present invention relates to a method of forming a photoresist pattern using an immersion lithography process. More particularly, a photoresist pattern is formed by immersing a photoresist-coated wafer in a liquid for immersion lithography before exposure for a predetermined time and then forming a photoresist pattern through an exposure process. The present invention relates to a method for forming a stable fine pattern without using a top anti-reflective coating used in an immersion lithography process.

In order to manufacture an increasingly smaller semiconductor device, the size of the pattern is gradually decreasing. Currently, 248 nm or 193 nm is mainly used for production as an exposure wavelength to form a dense line or a single line pattern during patterning, and many evaluations of patterning using a wavelength of 157 nm are being conducted.

In general, however, when the wavelength is used, air having a refractive index of 1.0 is used as a medium of the exposure beam between the exposure lens and the photoresist film in the exposure apparatus. ₂ O) or other fluids such as organic solvents to relatively increase the numerical aperture value of the exposure equipment, and also allow the wavelength value of the applied wavelength to be incident at a value smaller than the original value. Immersion lithography processes are available that can increase the

In the case of applying the immersion lithography process, there is an advantage in that a smaller fine pattern can be formed when the existing exposure wavelength is applied. However, water is applied on the surface of the photoresist film as an intermediate medium presently applied, and since the water moves to the photoresist film during the patterning process and is absorbed into the resin or photoacid generator component in the photoresist film, the expansion of the photoresist is performed. In order to prevent this, a general Top Anti-Reflective Coating (hereinafter referred to as "TARC") material is used.

The TARC is applied by an aqueous alkali solution or an organic solvent in a subsequent process after exposure. The top loss of the photoresist is generated by the aqueous alkali solution or the organic solvent, and roughness of the non-exposed sites is generated. This phenomenon of top loss and roughness of the resist eventually affects the etching margin by reducing the photoresist barrier in the subsequent etching process, and also causes uneven pattern formation in forming the fine pattern, and CD non-uniformity in the wafer during semiconductor device fabrication. It negatively affects the characteristics of the semiconductor device according to FIG.

The present invention is to solve the problems of the prior art, by immersing a photoresist-coated wafer in a liquid for immersion lithography for a predetermined time before exposure to form a photoresist pattern through the exposure process, used in the immersion lithography process An object of the present invention is to provide a photoresist pattern forming method capable of forming a stable fine pattern without a top anti-reflective coating.

In order to achieve the above object, the present invention provides a photoresist pattern forming method comprising the following steps.

(a) coating the photoresist composition on top of the etched layer on the wafer to form a photoresist film;

(b) immersing the photoresist film in a liquid for immersion lithography and then drying;

(c) exposing the dried photoresist film using exposure equipment for immersion lithography; And

(d) developing the exposed photoresist film to obtain a photoresist pattern.

Hereinafter, a method of forming a photoresist pattern according to the present invention will be described in detail.

First, a photoresist composition is coated on top of an etched layer on a wafer to form a photoresist film having a thickness of 700 GPa to 10000 GPa.

The etched layer is preferably formed of a nitride film, an oxide film, a BPSG film, a PSG film, a USG film, a PETEOS film, a SiON film, a polysilicon film, an inorganic antireflection film, or an organic antireflection film in a thickness of 200 kPa to 10000 kPa. Preference is given to using from 60 mm to 300 mm in size.

The photoresist composition may include a photoresist polymer, a photoacid generator, an organic solvent, and the like, and the photoresist polymer may include a polyvinylphenol-based polymer, a polyhydroxystyrene-based polymer, a polynorbornene-based polymer, and a polyadamant-based polymer. Polymers, polyimide-based polymers, polyacrylate-based polymers, polymethacrylate-based polymers, polyfluorine-based polymers or polymers substituted with fluorine are used.

As photoacid generator, diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenyl sulfonium triflate, diphenyl paratoluenyl sulfonium Triflate, diphenylparaisobutylphenylsulfonium triflate, diphenylparat-butylphenylsulfonium triflate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, triphenyl Sulfonium triflate or dibutylnaphthylsulfonium triflate is used, and the amount of the photoacid generator is preferably 0.01% by weight to 1% by weight based on the total amount of the photoresist composition.

In addition, as a solvent of the photoresist composition, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, cyclohexanone, propylene glycol methyl ether acetate, methyl ethyl ketone, benzene, toloene, dioxane, One selected from the group consisting of dimethylformamide is used alone or in combination.

Next, the photoresist film is dipped in a liquid for immersion lithography at 20 ° C. to 30 ° C. for 10 seconds to 40 seconds and then dried.

As the liquid for immersion lithography, pure water such as H ₂ O or D ₂ O, hexane, xylene, cyclooctane, perfluoropolyether or a mixture thereof is used, and the liquid for immersion lithography is lithium hydroxide, sodium hydroxide, Potassium hydroxide, cesium hydroxide or a mixture thereof may be further included. As such, the hydroxide is dissolved in the liquid for immersion lithography, thereby increasing the refractive index, thereby improving the resolution and DOF margin of the pattern.

In addition, the immersion process is preferably performed one or more times using one or two developing process units or wafer cleaning units.

In the present invention, the immersion process, in addition to water, in consideration of the dissolving power to the photoacid generator having each of the various organic solvents, which are materials used between the wafer and the exposure lens during the exposure process according to immersion lithography, that is, liquid for immersion lithography. Use it. In addition, the immersion process is performed for a suitable time for 10 to 40 seconds as described above so that a predetermined amount of the polymer or photoacid generator in the photoresist is dissolved by contact between the surface of the photoresist film and the liquid for immersion lithography.

The dried photoresist film is then exposed using exposure equipment for immersion lithography.

The exposure step is a light source as an i-line (365㎚), KrF (248nm), ArF (193nm), F 2 using (157nm), or EUV (extreme ultraviolet) exposure energy of 15mJ / cm ² to 150mJ / cm ² It is preferable to carry out. In the present invention, in view of the amount of the photoacid generator dissolved in the liquid for immersion lithography by the immersion step in the exposure step, the exposure is performed with an appropriate amount of exposure energy.

In addition, the exposure process is preferably carried out in a gas atmosphere of nitrogen, oxygen, argon, helium and the like.

Finally, the exposed photoresist film is developed to obtain a photoresist pattern. In the present invention, a dense line / space pattern, a single line / space pattern, or a contact hole pattern can be obtained by the above method.

Hereinafter, the present invention will be described in detail by examples. In the following examples, the process proceeds without forming a TARC material on the surface of the photoresist when forming a fine pattern using an immersion lithography process according to the present invention, thereby shortening the process step and reducing the cost, improving etching characteristics and improving CD uniformity. Describe how you can do it. In addition, the following Example is only an illustration of invention, and this invention is not limited by these.

Example 1

After coating a chemically amplified polyhydroxy styrene-based photoresist for KrF with a thickness of 4100 kPa on the surface of the SiON film to be etched, the photoresist is coated in a developing process unit or a device capable of performing a wafer cleaning process in general. The wafer was immersed in pure water for 15 seconds or 45 seconds at a temperature of 23 ℃ and then dried by spin method. Next, after exposing using an exposure apparatus of the immersion exposure method, a development pattern using an aqueous alkali solution was performed to form a fine pattern of 70 nm.

Example 2

After coating a chemically amplified polyhydroxy styrene-based photoresist for KrF with a thickness of 3500 kPa on the surface of the polysilicon layer to be etched, the photoresist may be formed in a developing process unit or a device capable of performing a wafer cleaning process. The coated wafer was immersed in pure water for 30 seconds at a temperature of 25 ° C. and then dried by spin. Next, after exposing using an exposure apparatus of the immersion exposure method, a development process using an aqueous alkali solution was performed to form a fine pattern of 65 nm.

Example 3

After coating a poly-amplified polyacrylate-based photoresist for ArF with a thickness of 2100 GPa on the surface of the polysilicon layer to be etched, the photoresist is coated in a developing process unit or a device capable of performing a wafer cleaning process in general. The wafer was immersed in pure water for 30 seconds at a temperature of 25 ℃ and then dried by spin method. Next, after exposing using an exposure apparatus of an immersion exposure method, a development process using an aqueous alkali solution was performed to form a 55 nm fine pattern.

Example 4

After coating a chemically amplified polyacrylate-based photoresist for ArF with a thickness of 1800Å on the surface of the oxide layer to be etched, the photoresist-coated wafer in a developing unit or a device capable of performing a wafer cleaning process in general. Was immersed in pure water for 25 seconds at a temperature of 23 ℃ and then dried by spin method. Next, after exposing using an exposure apparatus of an immersion exposure method, a development pattern using an aqueous alkali solution was performed to form a 52 nm fine pattern.

Example 5

After coating a chemically amplified polynorbornene-based photoresist for ArF with a thickness of 1800 GPa on the surface of the oxide layer to be etched, the photoresist-coated wafer in a developing process unit or a device capable of performing a wafer cleaning process in general. It was immersed in hexane (hexane) for 10 seconds at a temperature of 23 ℃ and then dried by spin method. Next, after exposing using an immersion exposure apparatus, a development process using an aqueous alkali solution was performed to form a 50 nm fine pattern.

Example 6

After coating a chemically amplified polymaleic hydride-based photoresist for ArF with a thickness of 1600Å on the surface of the organic diffuse reflection prevention layer, which is an etched layer, the photoresist in a developing process unit or a device capable of performing a wafer cleaning process in general. The coated wafer was immersed in hexane for 15 seconds at a temperature of 23 ° C. and then dried by spin. Next, after exposing using an immersion exposure apparatus, a development process using an aqueous alkali solution was performed to form a 50 nm fine pattern.

Example 7

After coating a polyacrylate-based photoresist substituted with chemically amplified 157nm F with a thickness of 1500Å on the surface of the organic diffuse reflection prevention layer, which is an etched layer, in a developing process unit or an apparatus capable of performing a wafer cleaning process in general, The photoresist-coated wafer was immersed in hexane for 17 seconds at a temperature of 23 ° C. and then dried by spin. Next, after exposing using an exposure apparatus of the immersion exposure method, a development pattern using an aqueous alkali solution was performed to form a fine pattern of 45 nm.

As described above, in the present invention, when the liquid for immersion lithography such as water or an organic solvent is used as an intermediate medium between the exposure lens and the photoresist when the immersion lithography process is applied, the fine pattern is applied without the application of TARC applied during the photoresist coating. Can be formed.

To this end, in the present invention, after forming the photoresist film after the photoresist coating, the wafer on which the photoresist film is formed without forming TARC on the photoresist film is pure in a developing process unit or an apparatus capable of performing a wafer cleaning process in general. After immersion in water or an organic solvent for a certain time, it can be seen that a fine pattern is formed by performing an exposure process with drying of the pure water or the organic solvent.

As described above, in the present invention, since the TARC formation and removal steps are omitted, process progress time can be shortened, cost can be reduced due to non-use of TARC, and alkali used for TARC removal is not required. Since the top loss of the photoresist by the aqueous solution or the organic solvent is prevented, subsequent etching characteristics can be improved. In addition, since roughness is prevented, a stable pattern of a uniform CD may be obtained when forming a fine pattern of 100 nm or less, and as a result, efficiency and yield of semiconductor device characteristics may be maximized.

Claims (14)

(a) coating the photoresist composition on top of the etched layer on the wafer to form a photoresist film; (b) immersing the photoresist film in a liquid for immersion lithography and then drying; (c) exposing the dried photoresist film using exposure equipment for immersion lithography; And (d) developing the exposed photoresist film to obtain a photoresist pattern. The method of claim 1, And said liquid for immersion lithography is selected from the group consisting of pure water, hexane, xylene, cyclooctane, perfluoropolyether, and mixtures thereof. The method of claim 2, The liquid for immersion lithography further comprises a hydroxide selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide and mixtures thereof. The method of claim 1, And the temperature of the liquid for immersion lithography is 20 ° C to 30 ° C. The method of claim 1, The immersion process of step (b) is performed at least once using one or two units selected from the group consisting of a developing process unit and a wafer cleaning unit. The method of claim 1, The immersion process of step (b) is performed for 10 seconds to 40 seconds. The method of claim 1, The photoresist composition may be a polyvinylphenol polymer, a polyhydroxystyrene polymer, a polynorbornene polymer, a polyadamant polymer, a polyimide polymer, a polyacrylate polymer, a polymethacrylate polymer, or a polyfluorine polymer. A method of forming a photoresist pattern comprising a polymer selected from the group consisting of a polymer and a polymer substituted with fluorine. The method of claim 1, The photoresist composition is diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxy phenylsulfonium triflate, diphenyl paratoluenyl sulphate Phosphonate triflate, diphenylparaisobutylphenylsulfonium triflate, diphenylparat-butylphenylsulfonium triflate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, tri A photoresist pattern forming method comprising a photoacid generator selected from the group consisting of phenylsulfonium triflate and dibutylnaphthylsulfonium triflate. The method of claim 8, The photoacid generator is a method for forming a photoresist, characterized in that used 0.01% by weight to 1% by weight based on the total amount of the photoresist composition. The method of claim 1, The solvent of the photoresist composition is ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, cyclohexanone, propylene glycol methyl ether acetate, methyl ethyl ketone, benzene, toloene, dioxane, dimethylform A method of forming a photoresist pattern, characterized in that it is used alone or in combination selected from the group consisting of amides. The method of claim 1, And a thickness of the photoresist film is 700 kPa to 10000 kPa. The method of claim 1, The etching layer is a photoresist pattern forming method, characterized in that selected from the group consisting of nitride film, oxide film, BPSG film, PSG film, USG film, PETEOS film, SiON film, polysilicon film, inorganic diffuse reflection prevention film and organic diffuse reflection prevention film. The method of claim 1, The exposure process of step (c) is performed using a light source selected from the group consisting of i-line (365 nm), KrF (248 nm), ArF (193 nm), F ₂ (157 nm) and EUV (extreme ultraviolet). A photoresist pattern forming method, characterized in that. The method of claim 1, The exposure process of step (c) is a photoresist pattern forming method, characterized in that carried out with an exposure energy of 15mJ / cm ² to 150mJ / cm ² .

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