JP3416196B2 - Resist surface anti-reflective coating forming composition and pattern forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a composition for forming a resist surface antireflection film when patterning is performed using a photoresist sensitive to radiation and a method for forming a pattern using the same. is there.

[0002]

2. Description of the Related Art As the degree of integration of semiconductor devices has been improved, the miniaturization of patterns has been advanced. Optical lithography using light as a light source is still used there. At present, the reduction projection exposure method is the mainstream because of its high resolution and excellent alignment accuracy. The problems in forming a fine pattern by the one-layer resist method by photolithography are the change in the pattern dimension (bulk effect) due to the local fluctuation of the resist film thickness due to the substrate step and the local resist due to the scattered light from the side wall of the substrate step. This is due to the thinning of the pattern size (notching effect) due to static overexposure. Since reduction projection exposure uses a refractive optical system, monochromatic light is used as a light source.
There is a problem caused by using this monochromatic light.

That is, the incident light to the resist, the reflected light from the resist surface, and the reflected light from the resist / substrate interface interfere with each other and are absorbed in the resist with a slight change in the resist film thickness. The fluctuation of the effective light quantity is λ / 2
It occurs at a cycle of n (λ: exposure wavelength, n: refractive index of resist), the resist pattern dimension varies (intra-film multiple reflection effect), and a periodic light intensity distribution occurs in the resist thickness direction. , A corrugated shape corresponding to the resist pattern cross section after development occurs (standing wave effect). Each of these causes variations in resist pattern dimensions and poor resolution.

As a method for solving these problems of the conventional one-layer resist method, a multi-layer resist method, an ARC method, and an AR method.
The COR method and the like have been proposed. However, the multi-layer resist method forms three resist layers, and then performs pattern transfer to form a resist pattern that serves as a mask.
There is a problem that the number of steps is large and the throughput is low. A
In the RC method, the antireflection film formed under the resist is wet-etched by development, so that there is a large amount of side etching, and there is a problem in that dimensional accuracy is greatly reduced. The ARCOR method is a method of coating a resist film with a single-layer or multi-layer interference-type antireflection film of an oil-soluble perfluoroalkyl compound to suppress multiple reflection in the resist film. Can not be applied as an aqueous solution, so it is applied as a solvent solution, but of course,
Since the antireflection film cannot be removed by washing with water, it is complicated, and there is a problem that the number of steps and the materials used increase considerably. The multilayer resist method is disclosed in JP-A-51-10.
No. 775 and the like. The ARC method is disclosed in JP-A-59-93448, and the ARCOR method is disclosed in JP-A-62-6.
No. 2520.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object thereof is a composition for coating a photoresist film to form a surface antireflection film when forming a pattern. To provide things. Further, another object is a method for improving the variation and resolution of the resist pattern dimension in pattern formation, wherein the antireflection film-forming composition can be applied as an aqueous solution, and the obtained antireflection film is After forming the photoresist pattern,
An object of the present invention is to provide a method that can be removed by a simple method such as a general post-process of washing with water and alkali development.

[0006]

As a result of various studies conducted by the present inventors in order to solve such a problem, when the water-soluble fluorine compound is applied onto a photoresist, the water-soluble formed film is formed. The present invention has been completed by finding that the fluorine compound film can be easily removed by washing with water and development and has an excellent function as an antireflection film.

That is, the gist of the present invention lies in a resist surface antireflection film-forming composition comprising an aqueous solution of a water-soluble fluorine compound. Further, other gist is a step of applying a photoresist composition on a substrate, a step of applying a resist surface antireflection film-forming composition on the obtained photoresist,
In the pattern forming method, including the step of exposing the photoresist and the obtained resist surface antireflection film to a predetermined pattern, and the step of developing the photoresist with an alkaline aqueous solution, the resist surface antireflection film formability A pattern forming method is characterized in that a composition comprising an aqueous solution of a water-soluble fluorine compound is used as the composition.

The present invention will be described in more detail below. The resist surface antireflection film-forming composition of the present invention has a water-soluble flux.
As a fluorine compound, perfluoroalkyl alcohol
Ethylene oxide adduct and / or its derivative and other water
Soluble fluorine compound (however, other water-soluble fluorine compound
Is a perfluoroalkyl alcohol / ethyleneoxy
Are not adducts and / or derivatives thereof)
It Here, perfluoroalkyl alcohol
As the oxide adduct and / or its derivative, α-
Perfluorononenyl-ω-methoxypolyoxyethylene
Down _{(C 9 F 17 O- (CH} 2 CH 2 O) 20 CH 3 , etc.)
And so on. In addition, other water-soluble fluorine compounds (
However, the other water-soluble fluorine compound is a perfluoroalkane.
Kill alcohol / ethylene oxide adduct and / or
(Not a derivative of), the following may be mentioned , for example. Ammonium perfluorononanecarboxylate (C
₉ F ₁₉ COONH ₄ ) and other perfluoroalkylcarboxylic acids and salts thereof, ammonium perfluorooctanesulfonate (C ₈ F ₁₇ SO ₃ NH ₄ ) and other perfluoroalkylsulfonic acids and salts thereof, and p represented by the following formula (I) -Perfluoroalkyl benzene sulfonic acid such as perfluoro nonyl benzene sulfonic acid and its salt, perfluoro alkyl oxy benzene sulfonic acid such as p-perfluoro nonyl oxy benzene sulfonic acid shown by the following formula (II) and its salt, and the following formula (III) Perfluoroalkylamines such as perfluorononyltrimethylammonium chloride and salts thereof, perfluorinated compounds such as N-propyl-N- (2-hydroxyethyl) perfluorooctanesulfonamide represented by the following formula (IV) Examples include lower alkyl sulfonamides .

[0009]

[Chemical 1]

Examples of the carboxylic acid and sulfonic acid salts include inorganic salts such as sodium salts and ammonium salts, and organic salts such as alkylamine salts. Examples of the amine salt include inorganic acid salts such as hydrochlorides and sulfates, organic acid salts such as carboxylates, and quaternary salts. The solubility of the water-soluble fluorine compound in the present invention in water is usually 1% by weight or more. Among the water-soluble fluorine compounds, perfluoroalkylcarboxylic acid and its salt, or perfluoroalkyl alcohol / ethylene oxide adduct and its derivative are preferable in terms of solubility.

The composition of the present invention comprises a water-soluble fluorine compound and
Then, perfluoroalkyl alcohol and ethylene oxide
Cid adduct and / or its derivative (A) and other water-soluble flux
Fluorine compounds (however, the other water-soluble fluorine compounds are
Rufluoroalkyl alcohol / ethylene oxide addition
(And not a derivative thereof) (B),
The composition is applied on a photoresist film.
Used to form surface anti-reflective coatings.
However, it is preferable in terms of coatability and antireflection effect of the coating film.
Yes.

The blending ratio in this case is usually (A) /
(B) = 9/1 to 1/9 (weight ratio), preferably (A) / (B) = 8/2 to 2/8. If B is too small in the above ratio, the pattern dimensional accuracy decreases,
Also, if the amount is too large, the pattern dimensional accuracy is lowered. Examples of the other water-soluble fluorine compound (B) include perfluoroalkylcarboxylic acid and salts thereof, perfluoroalkylsulfonic acid and salts thereof, perfluoroalkyloxybenzenesulfonic acid and salts thereof, perfluoroalkylbenzenesulfonic acid and salts thereof, perfluoroalkylamine and It is recommended to select from its salt, perfluoroalkylsulfonamide, etc., but perfluoroalkylcarboxylic acid salt is particularly preferable, and the mixture of perfluoroalkylcarboxylic acid salt and perfluoroalkyl alcohol / ethylene oxide adduct and / or its derivative is antireflection. Most preferable in terms of effects and coating formation.

The composition of the present invention may contain a water-soluble polymer compound in addition to the water-soluble fluorine compound.
As the water-soluble polymer compound, any well-known water-soluble polymer compound can be used, for example, starch and its derivatives,
Gelatin, casein, alginic acid, cellulose derivative,
Polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polymethacrylic acid, polymethyl vinyl ether, polyvinyl ethyl ether,
Examples thereof include polyethylene glycol. Among these, polyvinylpyrrolidone is preferable.

In this case, the ratio of the water-soluble fluorine compound (C) and the water-soluble polymer compound (D) is usually C / D = 9.
It is 5 / 0.5 to 0.5 / 9.5 (weight ratio), but preferably C / D = 9/1 to 4/6. When the water-soluble polymer compound is contained in the aqueous solution of the water-soluble fluorine compound,
This has the effect of improving the stability of the coating film.

The composition of the present invention is an aqueous solution of the above water-soluble fluorine compound. The amount of the water-soluble fluorine compound added to water is not particularly limited as long as it forms an aqueous solution, but the concentration used during formation of the antireflection film is usually 1 to 30% by weight, preferably 3 to 25% by weight with respect to water. Is. The composition of the present invention may be prepared by preparing a composition having a higher concentration in advance, and diluting the composition with water to obtain the above concentration before use.

On the other hand, in the pattern forming method of the present invention, a step of applying a photoresist composition on a substrate, a step of exposing a predetermined pattern to the obtained photoresist film, and developing the photoresist using an alkaline aqueous solution. A known pattern forming method comprising a step is characterized in that the composition of the present invention comprising an aqueous solution of a water-soluble fluorine compound is applied onto the photoresist film before exposure.

The photoresist composition used in the pattern forming method of the present invention may be either a positive type or a negative type, and various conventionally known photoresist compositions can be used. As the positive photoresist composition,
Usually, a naphthoquinonediazide-based positive photoresist composition comprising an alkali-soluble resin, a naphthoquinonediazide-based photosensitizer and a solvent can be mentioned. (See, for example, JP-A-61-118744).

Examples of the chemically amplified positive photoresist include, for example, a combination of a polymer obtained by protecting the hydroxyl group of polyhydroxystyrene with a t-butoxycarbonyl group and a photoacid generator (HIto, CG Willso).
n: Polym. Eng. Sci. 23,1012 (1
983))) and the like. Among the negative photoresist compositions, examples of the chemically amplified negative photoresist include a photoresist composition comprising an alkali-soluble resin, hexamethoxymelamine as a crosslinking agent, and a photoacid generator. (For example, WE Feely,
J. C. Imhof, C.I. M. Stein, T .; A. F
isher, M .; W. Legenza: Polym. E
ng. Sci. , 26, 1101 (1986)).

The substrate used in the pattern forming method of the present invention is not particularly limited, but a substrate for IC production such as a silicon substrate or a gallium arsenide substrate is generally used. The method for applying the photoresist composition onto the substrate is a conventional method using a spin coater or the like. The film thickness of the obtained photoresist composition is 0.3 to 5.0.
It is about μ.

The heating and drying treatment after coating the photoresist on the substrate is carried out using a hot plate or the like and is usually at 70 to 100 ° C. for about 30 to 120 seconds. The pattern forming method of the present invention is characterized in that a surface antireflection film is formed by applying a composition comprising an aqueous solution of a water-soluble fluorine compound as described above onto a photoresist.

The film thickness of the antireflection film may be appropriately optimized depending on the exposure wavelength and the like. In the present invention, since a composition comprising an aqueous solution of a water-soluble fluorine compound is used as the composition for forming the antireflection film, the formed antireflection film is exposed, exposed, or developed in an alkaline aqueous solution, or simply. It can be easily removed by washing with water. Moreover, since the antireflection film is formed on the photoresist,
Variations in resist pattern size and resolution are improved.

Incidentally, formed on the photoresist film,
The coating film made of a water-soluble fluorine compound can be removed by a developing solution of an alkaline aqueous solution at the time of development after exposure, but it is preferable to remove it by washing with water before development.
The exposure wavelength used to transfer an image to a photoresist coating film formed on a substrate is usually g-line (436n).
m), i-line (365 nm), Xe-Cl excimer laser light (308 nm), Kr-F excimer laser light (248
nm) and Ar-F excimer laser light (193 nm), but it is also effective in the case of multiple wavelengths.

After the photoresist film and the antireflection film are exposed, if necessary, post-exposure heating (PEB) may be performed. As the PEB condition, a hot plate or the like is used,
The conditions of 90 to 120 ° C. and 60 to 120 seconds are preferably used. A convection oven may be used instead of the hot plate, but this usually requires a longer time than when using a hot plate.

As the alkaline aqueous solution for developing the photoresist after exposure, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia, sodium silicate and sodium metasilicate, ethylamine and n-propylamine are used. Primary amines such as
Aqueous solutions of secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine, and quaternary ammonium salts such as tetramethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide. Alternatively, a product obtained by adding alcohol or the like to this can be used.

If desired, a surfactant or the like can be added for use. The developing time is preferably about 0 to 180 seconds and the developing temperature is preferably about 15 to 30 ° C. The photoresist developing solution is used after being filtered to remove insoluble matters.

[0026]

EXAMPLES Hereinafter, the specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 (Reference Example) Positive photoresist MCPR-2000H (trade name, manufactured by Mitsubishi Kasei Co., Ltd.) was applied on a plurality of bare silicon wafers using a spin coater, and then 90 ° C. at 80 ° C. Second prebaking was performed to form a photoresist coating film having a thickness of 1.0 to 1.3 μm.

Thereafter, ammonium perfluoroalkylcarboxylate (Unidyne DS-1 was formed on each resist).
No. 01, a 20% by weight aqueous solution of Daikin Industries, Ltd.) is applied and prebaked at 80 ° C. for 90 seconds to give a thickness of 7
An antireflection film composed of a film of ammonium salt of perfluoroalkylcarboxylic acid of 00 angstrom was formed.

Next, an exposure apparatus (NSR1755i7A:
Nikon) was used to transfer a 1.0 μm pattern with the same exposure amount, the wafer was rinsed with pure water, the antireflection film was dissolved and removed, and a 2.38 wt% tetramethylammonium hydroxide aqueous solution was used to remove the 23 Development was performed at 50 ° C. for 50 seconds to form a resist pattern. The pattern dimension was measured for each wafer, and the relationship between the photoresist coating film and the pattern dimension is shown by the solid line in FIG.

In FIG. 1, the pattern dimension variation amount was obtained from the straight line connecting the lowest points of the curve of the pattern dimension variation curve and the highest point of the curve. The results are shown in Table-1. In addition, the coating properties of the antireflection film (combining the coating properties and the performance maintaining stability of the coating) and the releasability after development are also shown in Table-1.

Example 2 Instead of an ammonium perfluoroalkylcarboxylate aqueous solution, a derivative (A ₁ ) of perfluoroalkyl alcohol / ethylene oxide adduct (Fugent 25
0, (trade name of Neos Co., Ltd.) and a mixed aqueous solution of the perfluoroalkylcarboxylic acid ammonium salt (B ₁ ) of Example-1 (weight ratio: (B ₁ ) / (A ₁ ) = 7/3, concentration 10
Wt%) was applied in the same manner as in Example-1, except that
evaluated. The results are shown in Table-1.

Example 3 As a water-soluble fluorine compound, a perfluoroalkylcarboxylic acid ammonium salt (B ₁ ) and a perfluoroalkyl alcohol / ethylene oxide adduct (A ₂ ) and a polyvinylpyrrolidone (C ₁ ) as a water-soluble polymer compound are weighed. Evaluation was carried out in the same manner as in Example-1 except that the mixture was applied in a ratio of B ₁ / A ₂ / C ₁ = 7.5 / 0.5 / 2.0. As a result, good results are shown in Table-1,
The coating film stability was further improved as compared with Example-2.

Example 4 (Reference Example) Perfluoroalkylsulfonic acid (D1) as a water-soluble fluorine compound and polyvinylpyrrolidone (C1) as a water-soluble polymer compound were mixed in a weight ratio of D1 / C1 = 6/4. The evaluation was performed in the same manner as in Example-1 except that the coating was performed. As a result, good results are shown in Table-1,
The coating film stability was further improved as compared with Example-2.

Comparative Example-1 Evaluation was carried out in the same manner as in Example-1, except that the antireflection film was not formed. The relationship between the photoresist coating film and the pattern size is shown in FIG.
The evaluation results are shown in Table-1.

Comparative Example 2 Instead of the ammonium perfluoroalkylcarboxylate aqueous solution, a Freon solution of perfluoroalkyl polyether (KRYTOX: registered trademark of DuPont) (concentration 1
(0% by weight) was used to form a pattern in the same manner as in Example-1, but the perfluoroalkyl polyether coating film could not be removed by rinsing with pure water and a developer.
No pattern could be formed after development.

Comparative Example-3 Instead of the ammonium perfluoroalkylcarboxylate aqueous solution, an aqueous solution of a water-soluble polysaccharide, sodium alginate, was applied, and the same evaluation as in Example-1 was performed.

[0037]

[Table 1]

[0038]

Since the composition of the present invention can be applied as an aqueous solution on a photoresist, an antireflection film can be easily formed, and it can be easily removed by washing with water or development with an alkaline aqueous solution. Moreover, according to the pattern forming method of the present invention, the antireflection film can be formed and removed by a simple method, a pattern with high dimensional accuracy can be formed, and it has great advantages in industrially manufacturing an LSI or the like. Is.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a photoresist film thickness and a pattern dimension in Example-1 and Comparative Example-1.

[Explanation of symbols] d: Pattern variation of Example-1 d ': pattern variation of Comparative Example-1

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mineo Nishi Nishi, Kurosaki Shiroishi 1-1, Yawatanishi-ku, Kitakyushu Sanritsu Kasei Co., Ltd. Kurosaki Factory (72) Hideo Makishima 1-1-3 Kurosaki Shiroishi, Hachiman Nishi-ku, Kitakyushu City Ryosei Co., Ltd. Kurosaki Plant (56) Reference JP-A-5-188598 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F 7/11 G03F 7/004 H01L 21 / 027

Claims (4)

(57) [Claims] 1. A resist surface antireflection film-forming composition comprising an aqueous solution of a water-soluble fluorine compound, said water-soluble
Perfluoroalkyl alcohol as a fluorine compound
.Ethylene oxide adducts and / or derivatives thereof and other
Water-soluble fluorine compound (however, other water-soluble fluorine compounds
The product is perfluoroalkyl alcohol / ethylene oxy.
Sid adduct and / or derivative thereof)
The above composition . 2. Another water-soluble fluorine compound is (1) perfluoroalkylcarboxylic acid and its salt, (2) perfluoroalkylsulfonic acid and its salt, (3) perfluoroalkyloxybenzenesulfonic acid and its salt, (4) ) perfluorinated alkyl benzene sulfonic acid and salts thereof, (5) perfluoroalkyl amine and its salts, and (6) claims, characterized in that at least one water-soluble compound selected from perfluoroalkyl sulfonamide, made from the group The composition according to 1. 3. A composition according to claim 1 or 2 aqueous solution of a water-soluble fluorine compound is characterized in that it comprises a water-soluble polymer compound. 4. A step of applying a photoresist composition on a substrate, a step of applying a resist surface antireflection film-forming composition on the obtained photoresist, the photoresist and the obtained resist surface antireflection film In a pattern forming method, which comprises a step of exposing a predetermined pattern to the photoresist, and a step of developing the photoresist with an alkaline aqueous solution, the resist surface antireflection film-forming composition according to any one of claims 1 to 3. Counter surface of resist according to item 1
A method for forming a pattern , which comprises using a composition for forming an anti-reflection film .