JPH07181684A - Antireflection film composition and production of pattern using that - Google Patents

Abstract

PURPOSE:To form a water-soluble polymer film having low refractive index without increasing the number of process by incorporating a poly resin, fluorine- base water-soluble surfactant and water-soluble fluorine compd. into the film and forming the film on a resist film. CONSTITUTION:The compsn. of an antireflection film 3 contains poly(vinylmethylether) resin, fluorine-base water-soluble surfactant and water-soluble fluorine compd. and is formed on a resist film 2. It is necessary that the poly(vinylmethylether) resin can be formed in a film. The fluorine water-soluble surfactant is available as a commercial product. As for the water-soluble fluorine compd., any water-soluble fluorine compds may be used. Light e2 from the substrate 1 to the surface of the resist 2 is reflected by the antireflection film/resist interface. The reflected light e2'' and reflected light e3 from the air/antireflection film interface cause interference which sufficiently decreases the reflected light. Thereby, with the obtd. antireflecting film compsn., a pattern can be made fine without increasing the number of the photoresist process and without decreasing the sensitivity of the resist.

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 which is used as an upper layer of a resist 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 miniaturize the patterns 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 the step-and-repeat mechanism (every time the wafer fixed in vacuum on an XY stage that can be moved in two dimensions is fed at a fixed size). 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 the light interference, the effective amount of light absorbed by the resist fluctuates, so that the pattern size fluctuates. As shown in FIG. 2, as the resist film thickness changes, the pattern size changes periodically, and the amount of change is S
In case of i substrate, it is about 0.3 μm. In the recent fine processing of semiconductor circuits and the like, the minimum processing line width is required to be 1 μm or less, and the reduction of the pattern dimensional accuracy due to the dimensional variation of the 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 the deterioration of dimensional accuracy due to optical interference. The multi-layer resist method has a problem that the number of steps for forming a resist film in three layers or two layers and then forming a pattern is large and throughput (processing capacity of a manufacturing apparatus) is low. Further, the improvement of the dimensional accuracy is not always sufficient due to the reflected light from the intermediate layer. The antireflection film method (Japanese Patent Application Laid-Open No. 62-159143) formed under the resist has a problem in that the amount of side etching is large because the antireflection film is wet-etched by development, and this causes a large decrease in dimensional accuracy. Further, a method of forming an antireflection film on a resist upper layer (JP-A-62-62520 and JP-A-62-62520).
-62521, JP-A-60-38821)
Is proposed.

[0003]

In the antireflection film method provided 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 at the interface between the resist and the air and the substrate. An antireflection film having a low refractive index is formed so that the reflected light from will not interfere. As a material for a low refractive index antireflection film, polysiloxane, which is a non-aqueous polymer, perfluoroalkyl polyether, and PVA (polyvinyl alcohol), which is a water-soluble polymer, have been proposed. However, a 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. On the other hand, water-soluble PVA has a large refractive index. There is a problem that the effect of preventing multiple interference cannot be reduced. In order to solve the above problems, the present invention provides a composition capable of forming a water-soluble polymer film having a low refractive index and capable of peeling an antireflection film during development without increasing the number of steps, and a pattern using the composition. It provides a manufacturing method.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to an antireflective coating composition containing a poly (vinyl methyl ether) resin, a fluorine-based water-soluble surfactant and a water-soluble fluorine compound and formed on a resist film. It relates to a method for producing a pattern using this composition.

In the present invention, poly (vinyl methyl ether) resin is used. It is necessary that the resin can be formed into a film. Therefore, the number average molecular weight is preferably 300 or more, and in consideration of the use in the semiconductor process, the number average molecular weight is preferably 1000 or more. Further, as the surfactant used in the present invention, a fluorinated water-soluble surfactant is used. These can be obtained as commercial products, and are manufactured by Sumitomo 3M Ltd., Florard FC-93 or F.
There are C-135 and the like. It is preferable that 2% by weight or less of this surfactant is mixed with the resin. The fluorine-based surfactant in the present invention is a material essential for the effect of preventing striation (uniformity in resist film thickness).

The water-soluble fluorine compound used in the present invention is not particularly limited as long as it is a water-soluble fluorine compound, and amine salts having a fluorine atom, weak acids, amides and the like are preferable, for example, hydrochloric acid 2,2,2. 2-Trifluoroethylamine, hexafluoroglutaric acid, heptafluorobutyric acid, 2-chloro-2,2-difluoroacetamide and the like are used. This compound is preferably one which is not corrosive to metals, and is preferably mixed in an amount of 50 to 100% by weight based on the resin. If the mixed amount exceeds 100% by weight, it may be difficult to form the antireflection film uniformly, and if the mixed amount is less than 50% by weight, the decrease in the refractive index of the antireflection film may be insufficient.

The antireflection film composition of the present invention is used by coating it on a resist film as an aqueous solution and drying it. The antireflection film formed by using the composition is transparent. There is no particular limitation on the concentration of the aqueous solution. The coating method is not particularly limited, and the spin coating method is usually used. Since the transparent antireflection film reduces the reflected light on the resist surface without loss of the incident light quantity, it can prevent the pattern dimension accuracy from being deteriorated due to optical multiple interference in the resist film, and the antireflection film can be peeled off during development. There is no need to add a new process. An alkaline aqueous solution is used as the developing solution, and 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 causes a change in the light intensity distribution in the resist film thickness direction and a standing wave that corrugates the cross-sectional shape of the resist. Although this causes a phenomenon called "whole", 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. 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. In order to reduce the reflected light from the upper surface of the resist without attenuating the exposure light, a transparent antireflection film 3 having a small absorption coefficient and utilizing optical interference is formed on the resist. That is, as shown in FIG. 1, 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 reflected by interference. Light is sufficiently small, e0 is exposure light, e
0'represents the reflected light of e0, and e3 represents the reflected light from the substrate appearing in the air. Based on the principle of the antireflection film, assuming that 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 the film thickness becomes closer to an odd multiple of λ / 4n ′. The reflectance (amplitude ratio) of the antireflection film is reduced. Since the refractive index of the phenol novolac-based resist is 1.7, the refractive index required for the antireflection film is 1.
It is 5 or less.

Striation can be prevented by the composition of the poly (vinyl methyl ether) resin, the water-soluble fluorine compound and the fluorine-based water-soluble surfactant. When striation occurs, as can be seen from the relationship between the thickness of the antireflection film and the reduction of the multiple interference effect as shown in FIG.
The dimensional accuracy in the plane changes greatly.

The present invention is also a method of manufacturing a pattern, which comprises a step of forming a resist film on a substrate, a step of exposing the resist film to a predetermined pattern, and a step of developing the resist after the exposure. The present invention relates to a pattern manufacturing method including a step of forming an antireflection film using the above antireflection film composition. Since the removal of the antireflection film can be shared with the resist developing step, 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. Also,
If the drying temperature after exposure is higher than 85 ° C,
Since a dedicated stripping solution is required, it is preferable that the antireflective film is stripped with water in advance by rinsing before drying after the exposure.

[0011]

【Example】

Example 1 15 g of 70% by weight aqueous solution of poly (vinyl methyl ether) resin (P0384) manufactured by Tokyo Kasei Co., Ltd., 2,2,2-trifluoroethylamine 1 hydrochloride manufactured by Tokyo Kasei Co., Ltd.
0.5 g, 0.05 g of Fluorosurfactant Florard FC-93 manufactured by Sumitomo 3M Limited was dissolved in 150 g of water, and a polymer aqueous solution was obtained using a 0.5 μm filter (film formation from this aqueous solution. The refractive index of the formed film is 1.4
40, 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). This aqueous solution has a film thickness of 900
0 (Å) to 13500 (Å) resist film (resist is Hitachi Chemical Co., Ltd. g-line resist: RG-8018P)
-20) was formed on each of the substrates, and the automatic coating device D-SPIN manufactured by Dainippon Screen was used to
Rotate at 000 rpm for 30 seconds and coat at 85 ° C for 9 seconds.
It was dried on a hot plate for 0 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 of Hitachi, Ltd., dried on a hot plate at 110 ° C / 90 sec, and then 2.38 wt of tetramethylammonium hydroxide. % Aqueous solution, paddle development was performed for 60 seconds. Then, rinse with pure water for 20 seconds and spin dry for 30 seconds to obtain a resist pattern. Obtained mask size 0.7μ
The resist pattern of m 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 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 15 g of a 70% by weight aqueous solution of poly (vinyl methyl ether) resin manufactured by Tokyo Kasei Co., Ltd. used in Example 1 and 2,2,2-trifluoroethylamine hydrochloride 1,2 manufactured by Tokyo Kasei Co., Ltd.
0.5 g was dissolved in 150 g of water, and a 0.5 μm filter was used to obtain an aqueous polymer solution. A substrate was prepared from this aqueous solution by the same method as in Example 1 to form a resist pattern.
The obtained resist pattern with a mask size of 0.7 μm was measured using a length 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 uneven thickness of the antireflection film, and the pattern dimensional accuracy was not improved.

Example 2 15 g of a 70% by weight aqueous solution of poly (vinyl methyl ether) resin manufactured by Tokyo Kasei Co., Ltd. used in Example 1 and 2,2,2-trifluoroethylamine hydrochloride 1,2 manufactured by Tokyo Kasei Co., Ltd.
0.05 g of Sumitomo 3M Co., Ltd. fluorosurfactant Florard FC-135 was dissolved in 150 g of water, and a polymer solution was obtained using a 0.5 μm filter. The film thickness of this solution is 9000 (Å) ~ 13500 (Å)
Each of the substrates on which the resist film (using a resist of Hitachi Chemical Co., Ltd. g-line resist: RG-8018P-20) is formed, is applied at 3000 rpm using an automatic coating device D-SPIN manufactured by Dainippon Screen. 30 rpm
Spin coating was performed for 2 seconds and dried at 80 ° C. for 90 seconds on a hot plate to obtain a coating film of 62 nm. Each of the obtained substrates was LD-50, an i-line reduction projection exposure apparatus manufactured by Hitachi, Ltd.
The pattern was exposed at 10i for 170 msec, dried at 110 ° C for 90 sec on a hot plate, and then paddle-developed for 60 sec using a 2.38 wt% tetramethylammonium hydroxide 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 measuring electron microscope S-6000 manufactured by Hitachi, Ltd. As a result, the change in the pattern size 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 15 g of a 70% by weight aqueous solution of poly (vinyl methyl ether) resin manufactured by Tokyo Kasei Co., Ltd. used in Example 1 and 2,2,2-trifluoroethylamine 1 hydrochloric acid manufactured by Tokyo Kasei Co., Ltd.
0.05 g of Sumitomo 3M Fluorosurfactant Florard FC-93 was dissolved in 150 g of water, and a polymer solution was obtained using a 0.5 μm filter. The film thickness of this solution is 9000 (Å) ~ 13500 (Å)
Each of the substrates on which the resist film (using a resist of Hitachi Chemical Co., Ltd. g-line resist: RG-8018P-20) is formed, is applied at 3000 rpm using an automatic coating device D-SPIN manufactured by Dainippon Screen. 30 rpm
Spin coating was performed for 2 seconds and dried at 85 ° C. for 90 seconds on a hot plate to obtain a coating film of 62 nm. Each of the obtained substrates was LD-50, an i-line reduction projection exposure apparatus manufactured by Hitachi, Ltd.
Pattern exposure for 170 msec at 10i, and then 30 times with pure water.
Rinse for 2 seconds, dry at 110 ° C. for 90 seconds on a hot plate, then tetramethylammonium hydroxide 2.38.
Paddle development was performed for 60 seconds using a wt% aqueous solution.
Then, rinsed with pure water for 20 seconds and spin dried for 30 seconds to obtain a resist pattern. Obtained mask size 0.7
The resist pattern of μm was measured using a 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 (shown by the dotted line in FIG. 2).

Example 4 15 g of a 70% by weight aqueous solution of poly (vinyl methyl ether) resin (P0384) manufactured by Tokyo Kasei Co., Ltd., 10.5 g of hexafluoroglutaric acid manufactured by Tokyo Kasei Co., Ltd., and fluorine manufactured by Sumitomo 3M Co., Ltd. System surfactant Florard FC-
93, 0.05 g was dissolved in 150 g of water, and a 0.5 μm filter was used to obtain an aqueous polymer solution (the film formed from this aqueous solution has a refractive index of 1.435, and this film has antireflection properties). If it is used for a film, it is possible to significantly reduce the reflectance on the upper surface of the resist and improve the dimensional accuracy). The film thickness of this solution is 9000 (Å) ~ 1350
0 (Å) resist film (resist is Hitachi Chemical Co., Ltd.
G-line resist: made of RG-8018P-20) is formed on each of the substrates formed by using an automatic coating device D-SPIN manufactured by Dainippon Screen at a rotation speed of 3000 rpm for 30 seconds, and then at 90 ° C. at 85 ° C. It was dried on a hot plate for 2 seconds to obtain a coating film of 62 nm. Each of the obtained substrates is an i-line reduction projection exposure apparatus LD of Hitachi, Ltd.
The pattern was exposed to −5010i for 170 msec, dried at 110 ° C. for 90 sec on a hot plate, and then dried with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 6 min.
Paddle development was performed for 0 seconds. 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 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 (shown by the dotted line in FIG. 2).

Example 5 15 g of 70% by weight aqueous solution (P0384) of poly (vinyl methyl ether) resin manufactured by Tokyo Kasei Co., Ltd., 2-chloro-2,2-difluoroacetamide 1 manufactured by Aldrich
0.5 g, 0.05 g of Fluorosurfactant Florard FC-93 manufactured by Sumitomo 3M Limited was dissolved in 150 g of water, and a polymer aqueous solution was obtained using a 0.5 μm filter (film formation from this aqueous solution. The refractive index of the formed film is 1.4
42, 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). This solution has a film thickness of 9000
(Å) to 13500 (Å) resist film (resist is g-line resist manufactured by Hitachi Chemical Co., Ltd .: RG-8018P-
20) is formed on each of the substrates, and each of the substrates is formed by using an automatic coating device D-SPIN manufactured by Dainippon Screen Co., Ltd.
Spin coating at a rotation speed of 00 rpm for 30 seconds and at 90 ° C at 90
It was dried on a hot plate for 2 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 of Hitachi, Ltd., dried on a hot plate for 90 sec at 110 ° C., and then 2.38 weight of tetramethylammonium hydroxide. % Aqueous solution, paddle development was performed for 60 seconds. Then, rinsed with pure water for 20 seconds and spin dried for 30 seconds to obtain a resist pattern. Obtained mask size 0.7μ
The resist pattern of m was measured using a 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 (shown by the dotted line in FIG. 2).

[0017]

According to the present invention, the anti-reflection pattern can be improved in a simple process without increasing the number of steps of the conventional photoresist process and without lowering the sensitivity of the resist. A film composition and a method for producing a pattern using the film composition can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is a diagram showing a relationship between a resist film thickness and a pattern size.

[Explanation of symbols]

 1 substrate 2 resist 3 antireflection film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03F 7/26 511 H01L 21/027

Claims (2)

[Claims] 1. An antireflective coating composition containing a poly (vinyl methyl ether) resin, a fluorine-based water-soluble surfactant and a water-soluble fluorine compound and formed on a resist film. 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 film after exposure. A method for producing a pattern, comprising the step of forming an antireflection film using the antireflection film composition according to claim 1.