JPH09255370A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resist pattern having high dimensional accuracy and positioning accuracy by forming a resist film on a substrate and further forming a specified antireflection film, exposing the resist film and then developing. SOLUTION: A resist liquid is applied on a substrate 10 and the solvent is vaporized to form a resist film 20. Then a liquid compsn. for an antireflection film containing a compd. having a perfluoroether group expressed by formula Rf-(Z-R)j is applied and heated at 30 to 100 deg.C for 1 to 10min. to remove the solvent and to form an antireflection film 30 having 65-100nm thickness. In formula, Rf is a univalent or bivalent perfluoroether, R is a substd. or unsubstd. univalent hydrocarbon group having >=10 carbon number, Z is a bivalent connecting group, j is 1 or 2. Then the resist film 20 is exposed to light through the antireflection film 30, and developed to form a resist pattern 20a by leaving the unexposed part 20a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern forming method in photolithography and X-ray lithography used for fine processing of semiconductor elements, magnetic bubble elements, superconducting elements and the like.

[0002]

2. Description of the Related Art The degree of integration of semiconductor circuits, magnetic bubble memory circuits, etc. is improving year by year. In order to improve the degree of integration, it is necessary to miniaturize the pattern, and it is also necessary to improve the precision of the pattern dimension and the alignment accuracy. However, in the photolithography, there is a problem that dimensional accuracy and alignment accuracy are lowered due to the influence of optical interference.
Hereinafter, such problems will be described.

First, the problem of deterioration in dimensional accuracy will be described. The reduction projection exposure method, which has a high resolution, a low defect occurrence rate due to foreign particles, and is capable of correcting wafer distortion by a step-and-repeat mechanism, is used as a mainstream of fine pattern forming methods. In the reduction projection exposure method, monochromatic light is used due to restrictions of lenses and optical systems, and optical interference occurs in the resist. Since the effective amount of light absorbed in the resist changes due to the light interference, the pattern size changes. The pattern line width periodically fluctuates as the resist film thickness changes, and the fluctuation amount is about 0.3 μm in the case of a silicon substrate. The minimum line width is required to be about 1 μm or less, and the decrease in dimensional accuracy due to this dimensional variation is a serious problem.

A multi-layer resist method, an ARC method, etc. have been proposed as a method for reducing the deterioration of the dimensional accuracy due to such optical interference. However, the multi-layer resist method has a problem in that the number of steps is large and the throughput is low because two or three resist layers are formed and then a pattern is transferred to form a resist pattern serving as a mask. Further, the improvement of the dimensional accuracy is not always sufficient due to the reflected light from the intermediate layer. The ARC method has a problem that since the antireflection film formed under the resist is wet-etched by development, the amount of side edges is large, resulting in a large decrease in dimensional accuracy. The multilayer resist is described in JP-A-51-10775. The ARC method is disclosed in Japanese Patent Laid-Open No. 59-9.
It is disclosed in Japanese Patent No. 3448.

Next, the problem of deterioration of alignment accuracy will be described. The alignment method using monochromatic light is TTL (Thro
The ugh The Lense) method can be used, which is advantageous in terms of throughput and offset variation, and is therefore advantageous for chip-by-chip alignment (hereinafter referred to as chip alignment) capable of correcting asymmetrical wafer distortion. Further, in the case of the Fresnel zone alignment method which also uses monochromatic light and utilizes the optical interference, it is possible to perform focus position and pattern alignment at the same time, which is very effective. However, there were the following problems, and sufficient pattern accuracy could not be obtained.

That is, in the reflection detection method of irradiating the combined target pattern formed on the substrate with monochromatic light or quasi-monochromatic light and detecting the pattern reflected light from the target pattern, the surface of the resist formed on the substrate is detected. Since the light is reflected, the pattern detection light causes optical interference in the resist film. As a result, the reflected light (detection light) is also affected, and the light intensity and phase change as the resist film thickness changes. As a result, the pattern detection signal is disturbed and the alignment accuracy is reduced. For example, when the resist is applied with an asymmetric film thickness with respect to the target pattern, the position of the target is detected at a position shifted from the actual position. That is, false detection is performed. Further, depending on the film thickness of the resist, the reflected light intensities of the target pattern portion and other portions become almost equal, and the contrast of the target pattern may be significantly reduced, that is, the detection of the target pattern may become extremely difficult. Such a problem exists in the alignment system using monochromatic light.

For this reason, for example, in the Fresnel zone pattern detection system, SP I E (SPI
E) Optimization of the target pattern shape is being investigated, as discussed in Volume 470, pages 122-135. Further, as disclosed in Japanese Patent Publication No. 58-30736, dual wavelength detection has been studied. But,
In either case, prevention of pattern detection signals due to optical interference is insufficient, and improvement is desired.

In order to achieve the above-mentioned object, Japanese Unexamined Patent Publication (Kokai) No. 62-62520 discusses formation of a commercially available perfluoropolyether film as an antireflection film on a photoresist film or an X-ray resist film. ing.
However, the perfluoropolyether used in these techniques is problematic from the viewpoint of the environment or cost because it dissolves only in a fluorine-based solvent such as freon (fluorochlorinated carbon) or perfluorocarbon.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pattern forming method capable of easily and inexpensively forming a resist pattern having high dimensional accuracy and alignment accuracy.

[0010]

In order to achieve the above object, the present invention provides a step of forming a resist film on a substrate, and a perfluoropolyether group represented by the following general formula (1) on the resist film. A step of forming an antireflection film from a liquid composition for an antireflection film containing a compound having: R _f- (ZR) _j (1) (where R _f is a monovalent or divalent perfluoro). Represents a polyether group, R represents an unsubstituted or substituted monovalent hydrocarbon group having 10 or more carbon atoms, Z represents a divalent linking group, and j represents 1
Or 2. ) A pattern forming method is provided, which comprises a step of exposing the resist film and a step of developing the exposed resist film to form a pattern of the resist film.

Further, in order to achieve the above object, the present invention comprises a step of forming a resist film on a substrate on which an alignment pattern is formed, and a step of forming the resist film on the resist film by the general formula (1). A step of forming an antireflection film from a liquid composition for an antireflection film containing a compound having a fluoropolyether group, and irradiating the substrate with pattern detection light for detecting the alignment pattern and reflecting the light Pattern formation, which comprises the steps of: detecting the resist pattern, aligning a desired pattern, exposing the resist film, and developing the exposed resist film to form a pattern of the resist film. Provide a way.

The pattern forming method of the present invention uses a composition containing a fluorine-containing compound having a perfluoropolyether group and a hydrocarbon group having 10 or more carbon atoms in one molecule represented by the above formula (1). The feature is that an antireflection film is formed on the resist. Since this fluorine-containing compound has a long-chain hydrocarbon group in its molecular structure, it is soluble in an inexpensive organic solvent other than a fluorine-based one, for example, a mixed solvent containing alcohol. The antireflection film using this fluorine-containing compound does not absorb visible light, and has a low refractive index of about 1.35 even though it contains hydrocarbons, which is a property suitable as an antireflection film for resists. Have. Therefore, by using the above-mentioned fluorine-containing compound, the reflected light on the resist surface can be reduced without loss of incident light, and an antireflection film that can prevent deterioration of pattern dimensional accuracy due to optical multiple interference in the resist film can be easily formed. Can be formed or removed. Further, with the same principle, deterioration of the pattern detection signal for mask alignment can be reduced, and alignment accuracy is improved.

Therefore, according to the pattern forming method of the present invention, it is possible to easily and inexpensively form a resist pattern with high dimensional accuracy and alignment accuracy.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to the following embodiments. As described above, the pattern forming method of the present invention is characterized by forming an antireflection film using a fluorine-containing compound represented by the following general formula (1) on a resist. Will be described.

R _f- (ZR) _j (1) (wherein R _f represents a monovalent or divalent perfluoropolyether group, R represents an unsubstituted or substituted monovalent group having 10 or more carbon atoms) Represents a hydrocarbon group, Z represents a divalent linking group, and j represents 1
Or 2. ) This fluorine-containing compound has a perfluoropolyether group and a long-chain hydrocarbon group in one molecule. Therefore, while having the characteristics of a perfluoropolyether group, it can be dissolved in a hydrocarbon solvent before use. Cheap.

In the above formula, R _f is a perfluoropolyether group, and as the monovalent one, the following structural formula can be exemplified. _{F (CF 2 CF 2 CF 2} O) n - Further, as the divalent perfluoropolyether group, the following structural formula can be exemplified.

-(OC ₂ F ₄ ) _p (OCF ₂ ) _q -wherein, l, m, m, k, p, and q in the chemical structural formula of the perfluoropolyether are integers of 1 or more, respectively. Show. Moreover, about m / l and p / q, 0.5-
About 2.0 is preferable.

R is an unsubstituted or substituted hydrocarbon group having 10 or more carbon atoms, and by containing such a long-chain hydrocarbon group in the molecule, R is represented by the above formula (1) according to the present invention. The fluorine-containing compound is dissolved in a hydrocarbon solvent. However, as the hydrocarbon component increases, the refractive index also increases and exceeds 1.4. Therefore, the ratio of carbon number C _Rf hydrocarbon group R of carbon number C _R and _the perfluoropolyether group R _f of (C _R / C _{R f)} is important, preferably 0.25 or more, more preferably 0 The range of 0.3 to 2.0 is preferable. For example, a stearyl group (having 18 carbon atoms) is used as the long-chain hydrocarbon group R, and a perfluoropolyether group R
_When F (CF ₂ CF ₂ CF ₂ O) ₁₀ is used as _f ,
C _R / C _Rf = 0.6.

Z is a divalent linking group, and examples thereof include an ester group, an amide group, an ether group, a sulfone group, and a phosphonyl group. Of these, an ester group is preferable in view of solubility in a solvent and ease of production. When Z is an ester group, the fluorine-containing compound represented by the formula (1) is a compound represented by the following general formulas (2) to (5).

R _f -COOR ₁ (2) R _f -OCOR ₂ (3) R ₁ OCO-R _f -COOR ₁ (4) R ₂ OCO-R _f -COOR ₂ (5) (However, R _f represents a monovalent or divalent perfluoropolyether group, and R ₁ and R ₂ each represent a hydrocarbon group having 10 or more carbon atoms.) The molecular weight of the fluorine-containing compound represented by the above formula (1) is The number average molecular weight is not particularly limited, but is 500 to 10,000, preferably 10 in terms of stability, ease of handling, and the like.
It is preferably about 00 to 5000.

The fluorine-containing compound represented by the above formula (1) is synthesized by, for example, synthesizing a perfluoropolyether having a carboxyl group at a terminal and a long chain hydrocarbon having an alcohol group by a known esterification reaction, It can be easily obtained by synthesizing a perfluoropolyether having an alcohol group at the terminal and a long-chain hydrocarbon having a carboxyl group at the terminal by a known esterification reaction.

When the fluorine-containing compound represented by the above formula (1) is applied to a resist, it is usually dissolved in a solvent and used as a composition for an antireflection film. In this case, the solvent used is not particularly limited, but it should be determined in consideration of stability of the composition, wettability to a resist, volatility and the like in use. In the case of a compound containing a perfluoropolyether group which does not contain a long chain hydrocarbon group, the solvent is limited to a fluorocarbon or perfluoroalkane group, but a perfluoropolyether containing a long chain hydrocarbon group. Derivatives are soluble in ordinary organic solvents, for example, alcohol solvents such as ethyl alcohol, ketone solvents such as acetone, and hydrocarbon solvents such as hexane. Therefore, a single or a mixture of two or more of these may be used. It can be used as a solvent.

In the pattern forming method of the present invention, a resist film is formed on a substrate, the resist film composition containing the fluorine-containing compound represented by the above formula (1) is applied to the resist film, and the solvent is volatilized. Then, an antireflection film is formed. In this case, as the substrate, other than the silicon substrate, for example, PSG is used.
(Phosphorus glass), SiO ₂ , W, Al, polyimide, S
There is no problem with iN, GaAs, etc. As the resist, for example, OFPR800, OFPR830, OFP
R5000 (above, product of Tokyo Ohka, trade name), AZ135
0 (manufactured by Microposit, trade name), HPR204
(Hunt, product name) and other phenol novolac resin-based resists, RD2000N, RU1000N (Hitachi Chemical Co., Ltd., product name), MP23 (Shipley Corporation, product name), and other polyvinyl alcohol-based resists, KTFR ( Any resist such as a cyclized rubber-based resist such as CBR (trade name, manufactured by Japan Synthetic Rubber Co., Ltd.) manufactured by Kodak Co., Ltd. may be used. Further, the resist film is not limited to one layer, and may be a multilayer resist having two layers or three layers or more.

The method for forming the antireflection film by applying the composition for antireflection film on the resist film is not particularly limited, but the liquid composition is applied to the resist film by applying an application method such as spin coating. After coating on the surface, heating is generally used to remove the solvent.

In this case, by selecting an appropriate heating condition, the allowance time for leaving after the formation of the antireflection film is improved. Specifically, conditions of 30 to 100 ° C. and 1 to 10 minutes can be adopted. The pattern forming method of the present invention can improve dimensional accuracy and alignment accuracy based on the following principles. That is, the interference of light traveling in the opposite direction such as the interference between the light reflected from the substrate and the incident light changes the light intensity distribution in the resist film thickness direction, and the "standing wave" that makes the resist cross-sectional shape wavy. However, the total amount of light absorbed by the resist does not change, and the influence on the dimensional accuracy is small. 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, the phase difference between the light changes as the resist film thickness changes, so the resist film thickness changes. Then, the light intensity of these optical interference lights increases or decreases. That is, overexposure or underexposure occurs depending on the resist film thickness, and as a result, the dimensional accuracy decreases.

In order to improve the dimensional accuracy, the reflected light traveling in the same direction may be reduced. That is, 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, an antireflection film utilizing optical interference having a small absorption coefficient is formed on the resist. That is, as shown in FIG. 3, and the reflected light L ₃ from the anti-reflection film 30 / resist 20 surface of the light L ₁ directed from the substrate 10 to the resist 20 surface, the air / anti-reflection film 30
The reflected light L ₄ from the interface is interfered with to sufficiently reduce the reflected light. In this case, the light quantity of the transmitted light L ₂ approaches the light quantity of the incident light and is completely transmitted without loss of the light quantity when it becomes non-reflecting.

According to the principle of the antireflection film, when the refractive index of the resist with respect to the exposure light is n and the wavelength of the exposure light is λ, the refractive index n ′ of the antireflection film is n ^1/2 and its film thickness is λ / 4n. '=
The reflectance (amplitude ratio) of this antireflection film decreases as it approaches an odd multiple of λ / 4n ^1/2 . The refractive index of a phenol novolac resin-based resist is about 1.7. In this case,
The optimum refractive index required for the antireflection film is about 1.3, and therefore the optimum film thickness is an odd multiple of approximately λ / 5.2. On the other hand, the fluorine-containing compound represented by the general formula (1) has a refractive index of about 1.35. Therefore, the general formula (1)
By using the fluorine-containing compound represented by (1) as the antireflection film, it is possible to significantly reduce the reflectance on the upper surface of the resist and improve the dimensional accuracy.

Next, the principle of improving the alignment accuracy will be described. When a large amount of light interferes in the resist film, the reflected light reflected from the substrate is also affected, and the pattern detection accuracy deteriorates as described above. In order to solve this problem, the above-mentioned antireflection film is formed on the resist so that the outside air /
It reduces the reflected light at the resist interface and makes it completely transparent. Perfluoropolyether is transparent in the visible portion, and its refractive index can make the upper surface of the resist almost completely transparent. The optimum film thickness of the antireflection film at the time of pattern detection is ¼n ′ of the wavelength λ ′ of the pattern detection light, that is, n ′ is about 1.35, and therefore an odd number of about λ ′ / 5.4. Double.

By forming the antireflection film according to the present invention on the resist, the alignment detection signal is not disturbed by the noise due to the optical interference in the resist film, and as a result, the alignment accuracy is improved.

[0030]

EXAMPLES Examples of the pattern forming method of the present invention will be specifically described below. [Example 1] An example in which the compound 1 shown in Table 1 is used as the fluorine-containing compound represented by the general formula (1) according to the present invention and patterning is performed with a normal single-layer resist is shown.

The compounds shown in Table 1 have the following formula (2):
To (5) are fluorine-containing compounds having an ester group, and R _f , R ₁ and R ₂ in Table 1 correspond to the symbols in the formulas below. _{R f -COOR 1 ... (2)} R f -OCOR 2 ... (3) R 1 OCO-R f -COOR 1 ... (4) R 2 OCO-R f -COOR 2 ... (5) First, FIG. 1 (a ), A resist is spin-coated on a silicon substrate 10 having a step as shown in FIG.
The resist film 20 was formed by baking for 0 minutes to evaporate the solvent. The pattern on the silicon substrate 10 is a lattice pattern, a concave pattern, a convex pattern or the like, and the height of the pattern is about 0.1 to 0.6 μm. MP1300 (Shipley Co., trade name, phenol novolac type) is used for the resist, and the film thickness is about 1 μm on a flat surface.
m. The film thickness of the resist may be thicker or thinner than 1 μm as long as it is sufficient to cover the substrate step. The step difference on the substrate surface is not limited to 0.1 to 0.6 μm. Further, the shape is not limited to the above pattern.

Thereafter, as shown in FIG. 1B, a liquid composition prepared by dissolving the fluorine-containing compound 1 shown in Table 1 in hexane was spin-coated on the resist 20 to a film thickness of 65 to 100 nm. After coating and forming, it was dried at 40 ° C. for 5 minutes to form an antireflection film. Then, as shown in FIG.
Normal exposure was performed using light having a wavelength of 436 μm. After the exposure, as shown in FIG. 1D, the antireflection film was removed using hexane. Hexane did not dissolve the resist and did not cause alteration. In addition to the hydrocarbon solvent, fluorinated chlorinated carbon such as Freon can be used. However, since fluorinated chlorinated carbon has a non-zero ozone depletion potential, it is environmentally problematic. Further, it is possible to use perfluoropolyether having a low molecular weight or perfluorocarbon, but in this case, it is expensive and not practical.

Then, as shown in FIG. 1E, development was performed to form a resist pattern 20a on the silicon substrate 10 leaving the unexposed portion 20a. The pattern dimensional accuracy without the antireflection film was about 0.15 μm.
When the antireflection film was formed by the above steps, a highly accurate resist pattern having a dimensional accuracy of about 0.05 μm or less could be formed on the silicon substrate.

In the above embodiment, the case where the exposure light having the wavelength of 436 nm is used is shown. However, in the case of the exposure light having the wavelength of 405 nm, the thickness of the antireflection film is about 60 to 85 nm and the wavelength is 365 nm. With the film thickness of about 55 to 85 nm, the variation in dimensional accuracy could be kept within 0.05 μm as in the above-mentioned embodiment.

Similarly, using the compounds shown in Table 1, a wavelength of 43
The exposure light of 6 nm was used to measure the variation in dimensional accuracy when the coating thickness was 80 nm. The results are also shown in Table 1. From the results of Table 1, by forming the antireflection film on the resist with the fluorine-containing compound according to the present invention,
Dimensional accuracy variation of 0.1 when anti-reflection film is not formed
It is recognized that 5 μm can be set to 0.03 to 0.05 μm, and the amount of variation in dimensional accuracy can be extremely reduced.

[0036]

[Table 1]

[Example 2] Mask alignment was performed using light having the same wavelength as the exposure light in Example 1. A concave pattern, a convex pattern, a double slit pattern, a grid pattern, a dot pattern, and a hole pattern were used as the target pattern on the substrate at this time, and the pattern signal was observed for each of them, and the alignment accuracy was evaluated. As a result, the asymmetry of the signal waveform due to the uneven resist coating, the decrease in the signal intensity due to the optical interference, and the decrease in the contrast can be suppressed, and the alignment accuracy is improved. [Example 3] The effect of preventing the variation in dimensional accuracy due to the thickness of the antireflection film was confirmed. A resist was applied on a flat silicon wafer to a thickness of about 1.0 μm. The variation in resist film thickness was within about 0.05 μm. The wafer is not limited to silicon, and GaAs can be used. Then, one substrate was exposed as it was at a wavelength of 436 nm. On the other substrates, an antireflection film was formed by changing the film thickness on the resist on each substrate in the range of 0 to 160 nm, and exposed at a wavelength of 436 nm. After exposing the resist, the antireflection film is removed using a solvent, and then developed to form a pattern,
The dimensional variation was measured. The result is shown in FIG.

From FIG. 3, about 0.16 μm is obtained by the usual method.
The variation in the existing dimensions was reduced. In particular, when the thickness of the antireflection film is 80 nm, the dimensional variation becomes minimum, and
It was possible to be within 015 μm. The film thickness of the resist is not limited to 1.0 μm in this embodiment, and the exposure wavelength is 43 μm.
The wavelength is not limited to 6 nm, for example, 405 nm or 365 nm can be used, and multiple wavelengths may be used. [Example 4] This is an example of forming an antireflection film on a three-layer resist. As shown in FIG. 2A, a resist is spin-coated on the stepped silicon substrate 10 and then about 20
Baking was performed at 0 ° C. for 30 minutes to form a lower layer resist 21 of the three-layer resist. The pattern on the silicon substrate 10 is a lattice pattern, a concave pattern, a convex pattern or the like, and various steps are formed up to a step of about 1.5 μm at the maximum.
MP1300 was used for the resist 21, and the film thickness was about 2.0 μm on the flat surface. By the baking, the step on the surface of the lower layer resist 21 was alleviated. The material and film thickness of the lower layer resist 21 are not limited to the above examples, and any material that can be generally used for the lower layer resist can be used without any problem. The substrate step is not limited to the above example. There is no problem even if a metal film such as aluminum, an insulating film such as silicon oxide, an organic film such as polyimide, or a semiconductor film such as Ge is deposited on the substrate.

After that, as shown in FIG. 2 (b), SOG (Spinon Glass) 22 was formed in a thickness of about 0.18 μm as an intermediate layer of the three-layer resist. OCD (trade name) manufactured by Tokyo Ohka Co., Ltd. was used for SOG. As the intermediate layer 22, a commonly used material such as SiO ₂ or Si
An insulating film such as N, a metal compound such as organic titanium, a metal such as W, and a semiconductor such as Si can also be used.

Next, the upper layer resist 23 of the three-layer resist was formed on the intermediate layer 22 using MP1300 as a resist to have a film thickness of 2 μm. Next, the antireflection film 30 containing the fluorine-containing compound according to the present invention is coated with the upper resist 2
A film having a thickness of about 70 nm was formed on No. 3.

After that, patterning was performed using light having a wavelength of 365 nm, and then the antireflection film was removed. And
After development is performed to obtain a patterned upper resist layer 23 as shown in FIG. 2C, the pattern of the upper resist layer 23 is changed to the intermediate layer SOG2 as shown in FIG. 2D.
2 was transferred to form a transfer pattern on the intermediate layer 22. Then, as shown in FIG. 2E, the intermediate layer pattern 22 was used as a mask to transfer the pattern to the lower layer resist pattern 21 to form a pattern, that is, a three-layer resist pattern.

As a result, the dimensional variation, which was about 0.04 μm in the ordinary three-layer resist without the antireflection film, was improved to 0.01 μm or less by forming the antireflection film. In the above embodiment, the wavelength is 365 nm, but the wavelength is not limited to this. Also, although an example of a three-layer resist is shown, the same effect was observed in the case of a two-layer resist. [Embodiment 5] In Embodiment 2, e-line (546 nm), d-line (577 nm), and He of mercury having different wavelengths from the exposure light are used.
Mask alignment was performed using Ne laser light (633 nm) or the like. The pattern detection signal was better than that without the antireflection film, and the alignment accuracy was improved. In particular, when the thickness of the antireflection film is set to 1 / 5.4 of the wavelength λ ′ of the pattern detection light, that is, about 100 nm, 105 nm, and 115 nm for the e-line, d-line, and HeNe light, respectively. The alignment detection signal is the best and the alignment accuracy is improved.

In this embodiment, e line, d line, HeN
Although e light was used, the same effect was observed with other monochromatic light or polychromatic light. For mask alignment, a resist having sensitivity to X-rays such as RE-5000p (manufactured by Hitachi Chemical Co., Ltd.) can be used. [Example 6] In Example 4, mercury e-line, d-line, H
Mask alignment was performed using eNe light. As in the case of Example 2, the target pattern used was a concave pattern, a convex pattern, a double slit pattern, a grid pattern, and a hole pattern, and each case was examined. Even in a multi-layer resist, the pattern detection light intensity is sufficient by performing the pattern detection using the exposure light and the light of different wavelengths, and the antireflection film can improve the asymmetry of the pattern detection signal and the deterioration of the contrast. did it. In particular, in the case of a multi-layer resist, the flatness of the resist upper surface was high, so that the film thickness of the antireflection film was uniform, and as a result, the reduction effect was greater than that of the single-layer resist. Further, the film thickness of the antireflection film is set to 1 / 5.4 of the wavelength λ of the pattern detection light, that is, e
Line, d-line, and HeNe light, respectively, about 100 nm,
At 105 nm and 115 nm, the pattern detection signal waveform was almost as good as when the substrate was directly detected, and the effect of optical interference due to the resist could be eliminated. As a result, the alignment accuracy is about 0.3μ
m to about 0.2 μm, and the alignment accuracy due to the apparatus was almost achieved.

In this embodiment, e line, d line, HeN
Although e light was used, the same effect can be obtained in principle at other wavelengths as long as it is light that passes through the lower layer resist. Example 7 A resist was applied on a silicon substrate on which a Fresnel zone pattern was formed, and then an antireflection film according to the present invention was formed on the resist. Its film thickness is about 115 nm. Then, pattern position detection and in-focus position detection were performed using HeNe laser light. By forming the antireflection film according to the present invention, the pattern detection position and the in-focus position detection signal become sharp and the detection accuracy is improved.

The detection light is not limited to the HeNe laser light, and other monochromatic light can be used. Further, a multi-layer resist can be used instead of the single-layer resist. Further, as a result of an experiment using not only the Fresnel zone pattern but also a matching pattern utilizing interference or diffraction like a lattice pattern, the method of overcoating the antireflection film according to the present invention on the resist is extremely effective. Met. [Embodiment 8] In the above-mentioned Embodiments 1 to 7, after coating the resist with the antireflection film of the present invention, the coating was applied at about 90 ° C. for 1 hour.
Baking was performed for 0 minutes. By this heat treatment, the margin of time for leaving after forming the antireflection film was improved. The heat treatment condition is not limited to this condition as long as it does not deteriorate the photosensitive property and the developing property of the resist.

[0046]

According to the pattern forming method of the present invention, since an antireflection film having a high antireflection effect can be formed on a resist by a simple method, a pattern with high dimensional accuracy can be easily formed. In addition, since the alignment pattern can be detected with high accuracy, the alignment accuracy is improved.

Therefore, the circuit can be integrated and the chip area can be reduced, and a high-quality element with stable electric characteristics can be obtained with a high yield. Furthermore, the formation and removal of the antireflection film is easy to handle and the manufacturing cost is lowered because the antireflection film is dissolved in the hydrocarbon solvent. Moreover, there are few environmental problems.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating an example of a pattern forming method of the present invention.

FIG. 2 is a flowchart illustrating another example of the pattern forming method of the present invention.

FIG. 3 is a conceptual diagram for explaining improvement in dimensional accuracy of resist exposure by an antireflection film.

FIG. 4 is a graph showing the relationship between the thickness of the antireflection film and the variation in pattern dimensions.

[Explanation of symbols]

10 ... Substrate, 20 ... Resist, 21 ... Lower resist layer,
22 ... Intermediate layer, 23 ... Upper resist layer, 30 ... Antireflection film.

Claims (8)

[Claims] 1. A process of forming a resist film on a substrate, and a method for reflecting from a liquid composition for an antireflection film, which comprises a compound having a perfluoropolyether group represented by the following general formula (1) on the resist film. forming a barrier _{layer, R f - (Z-R} ) j ... (1) ( where, R _f represents a monovalent or divalent perfluoropolyether group, R is an unsubstituted having 10 or more carbon atoms Or a substituted monovalent hydrocarbon group, Z is a divalent linking group, and j is 1
Or 2. ) A pattern forming method comprising: a step of exposing the resist film; and a step of developing the exposed resist film to form a pattern of the resist film. 2. The film thickness of the antireflection film, where the wavelength of the exposure light of the exposure is λ and the refractive index of the resist is n,
The method for forming a pattern according to claim 1, wherein the number is approximately an odd multiple of λ / 4n ^1/2 . 3. The pattern forming method according to claim 1, further comprising the step of applying heat treatment after applying the liquid composition for an antireflection film. 4. The pattern forming method according to claim 1, further comprising a step of removing the antireflection film after exposing the resist. 5. The number of carbon atoms in the hydrocarbon group R is C_R, Perfluo
R polyether group R_fCarbon number of C _RfThen, (C
_R/ C_Rf) Is 0.25 or more, The putter according to claim 1.
Forming method. 6. A step of forming a resist film on a substrate on which an alignment pattern is formed, and a reflection containing a compound having a perfluoropolyether group represented by the following general formula (1) on the resist film. A step of forming an antireflection film from the liquid composition for an antireflection film, and R _f- (ZR) _j (1) (wherein R _f represents a monovalent or divalent perfluoropolyether group, R _f Represents an unsubstituted or substituted monovalent hydrocarbon group having 10 or more carbon atoms, Z represents a divalent linking group, and j represents 1
Or 2. ) A step of irradiating the substrate with pattern detection light for detecting the alignment pattern and detecting the reflected light to align the desired pattern, a step of exposing the resist film, and an exposed resist And a step of forming a pattern of a resist film by developing the film. 7. The pattern forming method according to claim 6, wherein when the wavelength of the pattern detection light is λ ′ and the refractive index of the resist is n, it is approximately an odd multiple of λ ′ / 4n ^1/2 . 8. The pattern forming method according to claim 6, wherein a heat treatment is applied after applying the liquid composition for an antireflection film.