JPH08292562A - Antireflection film composition and production of pattern using the same - Google Patents

Abstract

PURPOSE: To improve the dimensional accuracy of a pattern in a simple process without increasing the number of photoresist processes and without decreasing the sensitivity of a resist. CONSTITUTION: The production of pattern includes a process to prepare the compsn. for antireflection film containing a poly(vinylpyrolidone) resin, fluorine- based water-soluble surfactant and water-soluble fluorine compd., a process to form a resist film 2 on a substrate 1, a process to expose the resist film 2 for a specified pattern, and a process to develop the resist 2 after exposure. This method includes a process to form an antireflection film 3 by using the antireflection film compsn. on the resist film 2 before exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-soluble antireflective coating composition used for forming an antireflective coating on a resist film which can be used for producing semiconductor devices and the like and a method for producing a pattern using the same. .

[0002]

2. Description of the Related Art The degree of integration of semiconductor circuits, magnetic bubble memory circuits, etc. is increasing year by year, and it is necessary to make the patterns finer in order to improve the degree of integration and to improve the dimensional accuracy of the patterns. At present, the resolution is high, the defect occurrence rate due to foreign matter is low, and the distortion of the wafer is exposed by a step-and-repeat mechanism (each time a fixed-vacuum wafer is vacuum-fixed on an XY stage that can be moved two-dimensionally). The reduction projection exposure method that can be corrected by the above method is used as the mainstream of the fine pattern forming method. In the reduction projection exposure method, monochromatic light is used due to the limitation of the lens optical system, and optical interference occurs in the resist film. Due to optical interference, the effective amount of light absorbed by the resist fluctuates, so that the pattern dimension fluctuates. Further, as shown in FIG. 2, as the resist film thickness changes, the pattern size changes periodically, and the amount of change is about 0.3 μm for the Si substrate. In recent fine processing of semiconductor circuits and the like, the minimum processing line width is required to be 1 μm or less, and the decrease in pattern dimensional accuracy with respect to this variation in resist film thickness is a serious problem.

Conventionally, a multilayer resist method or an antireflection film method has been proposed as a method for reducing a decrease in dimensional accuracy due to optical interference. The multi-layer resist method has a problem in that the number of steps is increased because a resist film is formed in three layers or two layers and then a pattern is formed, and throughput (processing capability of a manufacturing apparatus) is low. Further, the improvement of dimensional accuracy is not always sufficient due to the reflected light from the intermediate layer. Anti-reflection film method for forming an anti-reflection film under the resist (Japanese Patent Laid-Open No. 62-62160)
JP-A-159143) has a problem that since the antireflection film is wet-etched by development, the amount of side etching is large, which causes a large decrease in dimensional accuracy.
Further, a method of forming an antireflection film on a resist upper layer (JP-A-62-62520, JP-A-62-62521, JP-A-60-38821) has been proposed.

In the method of providing the antireflection film on the resist upper layer, when the light reflected from the substrate passes through the resist film again and goes out into the air, the light reflected from the interface between the resist and the air and the light reflected from the substrate are reflected. An antireflection film having a low refractive index is formed so that light does not interfere. As materials for the low-refractive-index antireflection film used for this purpose, polysiloxane and perfluoroalkyl polyether which are non-aqueous polymers, and polyvinyl alcohol (PVA) which is a water-soluble polymer have been proposed. However, the non-aqueous polymer film having a low refractive index has a problem that the number of steps is increased because it is necessary to peel it off with an organic solvent after resist exposure and before development,
Water-soluble PVA has a problem that the refractive index is large and the effect of preventing multiple interference cannot be reduced.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and does not increase the number of steps of the conventional photoresist process and does not decrease the sensitivity of the resist, and the pattern dimensional accuracy is simple and simple. The present invention provides an antireflective coating composition capable of forming a water-soluble polymer film having a low refractive index which can be peeled off during development and a method for producing a pattern using the same.

[0006]

The present invention relates to an antireflection coating composition containing a poly (vinylpyrrolidone) resin, a fluorine-based water-soluble surfactant and a water-soluble fluorine compound. The present invention also provides a method for producing a pattern, which comprises the steps of forming a resist film on a substrate, exposing a resist film to a predetermined pattern, and developing the resist after exposure, wherein The present invention relates to a method for producing a pattern, which comprises a step of forming an antireflection film using an antireflection film composition.

First, the antireflection film composition of the present invention will be described. The antireflection film composition of the present invention contains the poly (vinylpyrrolidone) -based resin, the fluorine-based water-soluble surfactant and the water-soluble fluorine compound as described above.
Here, the poly (vinylpyrrolidone) -based resin is a homopolymer of vinylpyrrolidone or a copolymer of vinylpyrrolidone and a comonomer, and as the comonomer, acrylic acid, methacrylic acid, vinyl alcohol, vinyl methyl ether, etc. It is used and blended to such an extent that the effects of the present invention are not impaired. Poly (vinylpyrrolidone) is preferable in terms of properties such as antireflection. It is necessary for these resins to be capable of forming a film, and for that purpose, it is preferable that the number average molecular weight is 300 or more. Further, in consideration of use in the semiconductor process, the number average molecular weight is 1,000 to 2
More preferably, it is 0,000. Further, when a poly (vinylpyrrolidone) -based resin is used, when the antireflection film of the present invention is applied on a positive resist and used, the advantage that nitrogen gas generated by exposure can be satisfactorily transmitted can be obtained.

Further, the antireflection film composition of the present invention contains a fluorine-based water-soluble surfactant. As the fluorine-based water-soluble surfactant, various fluorine-based surfactants can be used as long as they are water-soluble. For example, perfluorooctanoic acid ammonium salt, perfluorooctanoic acid tetramethylammonium salt, perfluoroalkylsulfonic acid ammonium salt, perfluoroalkylsulfonic acid tetramethylammonium salt, fluorinated alkyl No. 4
Examples include quaternary ammonium iodide, perfluoroadipic acid, and quaternary ammonium salts of perfluoroadipic acid. These can be obtained as commercial products,
For example, Sumitomo 3M's Fluorad FC-93 or FC-135 (trade name) can be used.
This surfactant exhibits an effect of preventing striation (resist film thickness unevenness), and the above-mentioned poly (vinylpyrrolidone)
The amount is preferably 0.1 to 100% by weight, and more preferably 0.1 to 30% by weight, based on the resin. If the amount of the fluorine-containing water-soluble surfactant is too small, the antireflection effect tends to be lowered, and if it is too large, the antireflection film formed tends to be difficult to remove during development.

The antireflection film composition of the present invention further contains a water-soluble fluorine compound. The water-soluble fluorine compound is not particularly limited except the above-mentioned fluorine-based water-soluble surfactant, and various compounds can be used. For example, salts of fluoroalkylamine such as 2,2,2-trifluoroethylamine hydrochloride. , Fluorinated aliphatic carboxylic acids such as hexafluoroglutaric acid and heptafluorobutyric acid, and fluorinated aliphatic carboxylic acid amides such as 2-chloro-2,2-difluoroacetamide are mentioned as preferable compounds having excellent antireflection properties. . These water-soluble fluorine compounds have the effect of lowering the refractive index, and are preferably added in an amount of 50 to 100% by weight, preferably 50 to 70% by weight, based on the poly (vinylpyrrolidone) -based resin. More preferably, it is blended in an amount. If this amount is too large,
It tends to be difficult to form an antireflection film uniformly, and when it is too small, it tends to be difficult to reduce the refractive index of the antireflection film.

If necessary, the antireflection film composition of the present invention may be mixed with other resins such as poly (vinyl methyl ether) resin to the extent that the effects of the present invention are not impaired.

The antireflective coating composition of the present invention is used by coating it on a resist film as an aqueous solution and drying it, and the antireflective coating formed using this composition is transparent. The concentration of the aqueous solution is not particularly limited, but the concentration of all components is preferably 5 to 30% by weight from the viewpoint of easy adjustment of the thickness of the antireflection film to be formed. The coating method is also not particularly limited,
Usually, the spin coating method is adopted. The transparent anti-reflection film reduces the reflected light on the resist surface without loss of the incident light quantity, prevents the pattern dimension accuracy from deteriorating due to optical multiple interference in the resist film, and can peel off the anti-reflection film during development. , No need to add new process. An alkaline aqueous solution is used as the developing solution, and for example, a 2.38 wt% tetramethylammonium hydroxide aqueous solution is generally used.

Interference between light traveling in opposite directions, such as interference between light reflected from the substrate and incident light, changes the light intensity distribution in the resist film thickness direction, and a standing wave that corrugates the cross-sectional shape of the resist. However, the total amount of light absorbed by the resist does not change and has little influence on the dimensional accuracy. On the other hand, considering the case of light reflected from the upper surface of the resist and light traveling in the same direction such as incident light, when the resist film thickness changes, the light intensity of the interference light of these lights increases or decreases in the resist film. That is, overexposure or underexposure is caused depending on the resist film thickness, and the dimensional accuracy is reduced.

Therefore, in order to improve the dimensional accuracy, it is sufficient to reduce the reflected light traveling in the same direction, and it is sufficient to reduce the reflected light on the upper surface of the resist. Therefore, in the present invention, in order to reduce the reflected light from the upper surface of the resist without attenuating the exposure light, a transparent antireflection film having a small absorption coefficient and utilizing optical interference is formed on the resist.

In the present invention, first, a resist film is formed on a substrate, then an antireflection film is formed on the resist film using the antireflection film composition of the present invention, and then a predetermined pattern is exposed. Then, the pattern can be manufactured by developing. In this method, the removal of the antireflection film can be shared with the resist developing step, so that there is no process problem and it is simple. After coating, it is preferable to carry out drying at a temperature of 85 ° C. or lower at which it can be peeled off simultaneously during development. If the drying temperature after exposure is higher than 85 ° C, a dedicated stripping solution is required. Therefore, rinse after performing drying after exposure and peel the antireflection film with water in advance. Preferably.

FIG. 1 is an explanatory view showing the principle of the present invention. As shown in FIG. 1, a resist 2 and an antireflection film 3 using the antireflection film composition of the present invention are formed on a substrate 1. In the present invention, the reflected light e2 ″ from the antireflection film / resist interface and the reflected light e3 ′ from the atmosphere / antireflection film interface of the light e2 traveling from the substrate 1 to the surface of the resist 2 are sufficiently interfered with each other. In Fig. 1, e
0 represents exposure light, e0 ′ represents reflected light of e0, and e3 represents reflected light from the substrate that appears in the air.

From the principle of the antireflection film, when the refractive index for resist exposure light is n and the wavelength of the exposure light is λ, the refractive index n'of the antireflection film is √n, and its film thickness is an odd multiple of λ / 4n '. The reflectance (amplitude ratio) of this antireflection film decreases as the value becomes closer to. Since the refractive index of the phenol novolac resist is 1.7, the refractive index required for the antireflection film is 1.5 or less.

According to the invention, poly (vinylpyrrolidone)
Striation can be prevented by adding a fluorine-based water-soluble surfactant to an aqueous solution of a water-based resin and a water-soluble fluorine compound, and using this to form an antireflection film. When the striation occurs, the in-plane dimensional accuracy changes greatly, as can be seen from the relationship between the film thickness of the antireflection film and the reduction of the multiple interference effect as shown in FIG.

[0018]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these.

Example 1 70 of poly (vinylpyrrolidone) resin (trade name P0696, number average molecular weight 160,000) manufactured by Tokyo Chemical Industry Co., Ltd.
15% by weight aqueous solution, 10.5 g of 2,2,2-trifluoroethylamine hydrochloride, and 0.05 g of Fluorosurfactant Florard FC-93 manufactured by Sumitomo 3M Ltd. in water 1
It was dissolved in 50 g and filtered using a 0.5 μm filter to obtain an aqueous polymer solution. (The refractive index of the film formed by using this aqueous solution is 1.43, and when this film is used as the antireflection film, the reflectance on the upper surface of the resist can be significantly reduced and the dimensional accuracy is improved. A resist film having a film thickness of 9000 to 13500Å (a resist is a g-line resist manufactured by Hitachi Chemical Co., Ltd .: RG-8018P-
20) is formed on the resist film of the substrate on which the above polymer aqueous solution is applied at 3000 rpm using an automatic coating device D-SPIN manufactured by Dainippon Screen Mfg. Co., Ltd.
Was spin coated for 30 seconds at 85 ° C. and dried on a hot plate at 85 ° C. for 90 seconds to obtain a coating film of 62 nm.

Each of the obtained substrates was pattern-exposed for 170 msec by an i-line reduction projection exposure apparatus LD-5010i manufactured by Hitachi, Ltd., dried on a hot plate at 110 ° C./90 sec, and then tetramethylammonium hydroxide. Paddle development was performed for 60 seconds using a 2.38 wt% aqueous solution. Then, rinsed with pure water for 20 seconds and spin-dried for 30 seconds to obtain a resist pattern. The length of the obtained resist pattern having a mask size of 0.7 μm was measured using a length measuring electron microscope S-6000 manufactured by Hitachi Ltd., and the obtained result is shown by a broken line in FIG. As a result, the change in the pattern dimension due to the change in the resist film thickness was reduced by 60% as compared with the case where the antireflection film was not used (shown by the dotted line in FIG. 2).

Comparative Example 1 10 g of a 55% by weight aqueous solution of poly (vinylpyrrolidone) resin (trade name, P0696) manufactured by Tokyo Chemical Industry Co., Ltd. used in Example 1 and 2,2,2-trifluoroethylamine hydrochloride 10. 5 g was dissolved in 150 g of water and filtered using a 0.5 μm filter to obtain a polymer aqueous solution. Using this aqueous solution, an antireflection film was formed on a substrate having a resist film by the same method as in Example 1 to form a resist pattern. The obtained resist pattern having a mask size of 0.7 μm was measured using a measuring electron microscope S-6000 manufactured by Hitachi, Ltd., and the obtained results are shown in FIG. As a result, the swing curve of the standing wave was scattered due to the influence of the uneven thickness of the antireflection film, and the pattern dimension accuracy was not improved.

Example 2 10 g of a 55% by weight aqueous solution of poly (vinylpyrrolidone) resin (trade name, P0696) manufactured by Tokyo Kasei Kogyo Co., Ltd. used in Example 1, 2,2,2-trifluoroethylamine hydrochloride 10. 5 g and 0.05 g of the fluorochemical surfactant Florard FC-135 manufactured by Sumitomo 3M Limited were dissolved in 150 g of water, and filtered using a 0.5 μm filter to obtain an aqueous polymer solution. Resist film with a film thickness of 9000 to 13500Å (The resist is a g-line resist manufactured by Hitachi Chemical Co., Ltd .:
RG-8018P-20) was formed on the resist film of the substrate on which
Using an automatic coating device D-SPIN manufactured by Dainippon Screen, spin coating was performed for 30 seconds at a rotation speed of 3000 rpm, and dried on a hot plate at 85 ° C. for 90 seconds to obtain a coating film of 62 nm.

Each of the obtained substrates was pattern-exposed for 170 msec using an i-line reduction projection exposure system LD-5010i manufactured by Hitachi, Ltd., dried on a hot plate at 110 ° C./90 sec, and then tetramethylammonium hydroxide. Paddle development was performed for 60 seconds using a 2.38 wt% aqueous solution. Then, rinsed with pure water for 20 seconds and spin-dried for 30 seconds to obtain a resist pattern. The length of the obtained resist pattern having a mask size of 0.7 μm was measured using a length measuring electron microscope S-6000 manufactured by Hitachi, Ltd.
As a result, the change in the pattern dimension due to the change in the resist film thickness was reduced by 60% as compared with the case where the antireflection film was not used.

Example 3 10 g of a 55% by weight aqueous solution of poly (vinylpyrrolidone) resin (trade name, P0696) manufactured by Tokyo Kasei Kogyo Co., Ltd. used in Example 1, 2,2,2-trifluoroethylamine hydrochloride 10. 5 g and 0.05 g of Fluorosurfactant Florard FC-93 manufactured by Sumitomo 3M Ltd. were dissolved in 150 g of water, and filtered using a 0.5 μm filter to obtain an aqueous polymer solution. Resist film with a film thickness of 9000 to 13500Å (The resist is a g-line resist manufactured by Hitachi Chemical Co., Ltd .: R
G-8018P-20) was formed on each of the resist films of the substrate on which the above polymer aqueous solution was applied for 30 seconds at a rotation speed of 3000 rpm using an automatic coating device D-SPIN manufactured by Dainippon Screen Mfg. Co., Ltd. Spin coating, 85
It was dried on a hot plate at 90 ° C. for 90 seconds to obtain a coating film of 62 nm.

Each of the obtained substrates was pattern-exposed for 170 msec by an i-line reduction projection exposure system LD-5010i manufactured by Hitachi, Ltd., and then rinsed with pure water for 30 sec, 1
It was dried on a hot plate at 10 ° C./90 seconds, and then paddle development was performed for 60 seconds using a 2.38 wt% tetramethylammonium hydroxide aqueous solution. Then 2 with pure water
Rinse for 0 seconds and spin dry for 30 seconds to obtain a resist pattern. The obtained resist pattern having a mask size of 0.7 μm is measured by a Hitachi Ltd. measuring electron microscope S-.
The length was measured using 6000. As a result, the change in the pattern dimension due to the change in the resist film thickness was reduced by 60% as compared with the case where the antireflection film was not used.

Example 4 10 g of 55% by weight aqueous solution of poly (vinylpyrrolidone) resin (trade name P0696) manufactured by Tokyo Chemical Industry Co., Ltd., 10.5 g of hexafluoroglutaric acid manufactured by Tokyo Chemical Industry Co., Ltd. and Sumitomo 3M ( Fluorosurfactant made by Fluoro F
Dissolve 0.05 g of C-93 in 150 g of water and add 0.5 μ
An aqueous polymer solution was obtained by filtration using a m filter. (The refractive index of the film formed using this aqueous solution is 1.
435, and when this film is used as an antireflection film, the reflectance on the upper surface of the resist can be significantly reduced, and the dimensional accuracy can be improved. ) A resist film having a film thickness of 9000 to 13500Å (a resist is a g-line resist manufactured by Hitachi Chemical Co., Ltd .: RG-8018P-
20) is formed on the resist film of the substrate on which the above polymer aqueous solution is applied at 3000 rpm using an automatic coating device D-SPIN manufactured by Dainippon Screen Mfg. Co., Ltd.
Was spin coated for 30 seconds at 85 ° C. and dried on a hot plate at 85 ° C. for 90 seconds to obtain a coating film of 62 nm.

Each of the obtained substrates was pattern-exposed for 170 msec by an i-line reduction projection exposure apparatus LD-5010i manufactured by Hitachi, Ltd., dried on a hot plate at 110 ° C./90 sec, and then tetramethylammonium hydroxide. Paddle development was performed for 60 seconds using a 2.38 wt% aqueous solution. Then, rinsed with pure water for 20 seconds and spin-dried for 30 seconds to obtain a resist pattern. The length of the obtained resist pattern having a mask size of 0.7 μm was measured using a length measuring electron microscope S-6000 manufactured by Hitachi, Ltd.
As a result, the change in the pattern dimension due to the change in the resist film thickness was reduced by 60% as compared with the case where the antireflection film was not used.

Example 5 15 g of 55% by weight aqueous solution of poly (vinylpyrrolidone) resin (trade name P0696) manufactured by Tokyo Chemical Industry Co., Ltd., 10.5 g of 2-chloro-2,2-difluoroacetamide and Sumitomo 3M Limited Fluorine-based surfactant Florard FC
-93, 0.05g is dissolved in 150g of water, 0.5μm
An aqueous polymer solution was obtained by filtration using the above filter. (The refractive index of the film formed using this aqueous solution is 1.
432, and when this film is used as an antireflection film, the reflectance on the upper surface of the resist can be significantly reduced, and the dimensional accuracy can be improved. ) A resist film having a film thickness of 9000 to 13500Å (a resist is a g-line resist manufactured by Hitachi Chemical Co., Ltd .: RG-8018P-
20) is formed on the resist film of the substrate on which the above polymer aqueous solution is applied at 3000 rpm using an automatic coating device D-SPIN manufactured by Dainippon Screen Mfg. Co., Ltd.
Was spin coated for 30 seconds at 85 ° C. and dried on a hot plate at 85 ° C. for 90 seconds to obtain a coating film of 62 nm.

Each of the obtained substrates was pattern-exposed for 170 msec by an i-line reduction projection exposure apparatus LD-5010i manufactured by Hitachi, Ltd., dried on a hot plate at 110 ° C./90 sec, and then tetramethylammonium hydroxide. Paddle development was performed for 60 seconds using a 2.38 wt% aqueous solution. Then, rinsed with pure water for 20 seconds and spin-dried for 30 seconds to obtain a resist pattern. The length of the obtained resist pattern having a mask size of 0.7 μm was measured using a length measuring electron microscope S-6000 manufactured by Hitachi, Ltd.
As a result, the change in the pattern dimension due to the change in the resist film thickness was reduced by 60% as compared with the case where the antireflection film was not used.

[0030]

When the antireflection film composition according to claim 1 is used, the pattern size can be simplified by a simple process without increasing the number of steps in the conventional photoresist process and without lowering the sensitivity of the resist. The accuracy can be improved. According to the pattern manufacturing method of the second aspect, the pattern dimension accuracy is improved by a simple process without increasing the number of steps of the conventional photoresist process and without lowering the sensitivity of the resist. be able to.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the principle of the present invention.

FIG. 2 is a relationship diagram between a resist film thickness and a pattern dimension measured in Example 1 and Comparative Example 1.

[Explanation of symbols]

 1 substrate 2 resist 3 antireflection film

Claims (2)

[Claims] 1. An antireflection film composition containing a poly (vinylpyrrolidone) resin, a fluorine-based water-soluble surfactant and a water-soluble fluorine compound. 2. A method of manufacturing a pattern, which comprises the steps of forming a resist film on a substrate, exposing a resist film to a predetermined pattern, and developing the resist after exposure. Item 10. A method for producing a pattern, comprising the step of forming an antireflection film using the antireflection film composition according to item 1.