JP2001343748A - Negative-type resist composition, resist pattern forming method and method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist composition capable of forming a fine pattern without swellings having practical sensitivy by developing it using a basic aqueous solution. SOLUTION: In the negative-type resist composition, an oxetane structure of formula (1) is contained in the structure of an alkali-soluble resin or in the structure of a compound, used in combination with the alkali-soluble resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine processing technique, and more particularly, to a negative resist composition which can be developed with a basic aqueous solution without swelling, and a method for forming a fine resist pattern using the same. And a method for manufacturing a semiconductor device. According to the present invention, a resist material having less absorption of light at a short wavelength, good sensitivity, and high dry etching resistance is provided, so that semiconductor integrated circuits such as VLSI and ULSI and other fine processing Devices for which
For example, a magnetoresistive head (MR head) can be advantageously manufactured.

[0002]

2. Description of the Related Art IBM's H.I. With the advent of chemically amplified resists presented by Ito et al., Photolithography using a krypton fluoride excimer laser (wavelength: 248 nm, hereinafter abbreviated as KrF) is becoming a mainstay in mass production. For example, JMJ Frechet et al., Proc. Mic
rocircuit Eng., 260 (1982), H. Ito et al., Digesto
f Technical Papers of 1982 Symposium on VLSI Techn
ology, 86 (1983), H. Ito et al., “Polymers in Elect
ronics ”, ACS Symposium Series 242, T. Davidson, e
d., ACS, 11 (1984), USP 4,491,628 (1985).

In recent years, gigabit class DRAMs
For the fabrication of devices with a higher degree of integration, such as those described above, lithography using an ArF (argon fluoride) excimer laser (wavelength 193 nm) having a shorter wavelength has been actively studied. At such a short wavelength, the conventional phenolic resin absorbs light so strongly that it is necessary to change the material from the base resin itself. Therefore, development of a resist applicable to such a short wavelength has been urgently required.

As a chemically amplified resist applicable at the wavelength of ArF, a positive type resist has been actively developed conventionally (for example, see K. Nozaki et al, Chem. Mate).
r., 6, 1492 (1994), K. Nakano et al., Proc. SPIE,
2195 , 194 (1994), RD Allen et al., Proc. SPIE, 2
438 , 474 (1994), JP-A-9-90637, K. No.
zaki et al., Jpn. J. Appl. Phys., 35 , L528 (1996),
K. Nozaki et al., J. Photopolym. Sci. Technol., 10
(4), 545-550 (1997)), and there have been few reports of single-layer negative type chemically amplified resists, and many were crosslinked resists. For example, A. Katsuyama et al., Abstrac
ted Papers of Third International Symposium on 193
nm Lithography, 51 (1997), Maeda et al., Proceedings of the 58th JSAP, No. 2, 647 (3a-SC-17) (1997), T. N
aito et al., Proc. SPIE, 3333 , 503 (1998), JP 20
JP-A-00-122288, JP-A-2000-14776
As described in No. 9 and the like, a crosslinked resist is
By increasing the molecular weight by utilizing a crosslinking reaction in the exposed portion, a difference in solubility between the exposed portion and the unexposed portion in a developing solution is caused to perform patterning. For this reason, the limit of fine processing due to swelling of the pattern is inevitable.

[0005] Recently, polarity changes by intramolecular lactonization using a hydroxycarboxylic acid structure (for example, Y.Y.
okoyama et al., J. Photopolym. Sci. Technol., 13
(4), 579 (2000)) and pinacol transfer (see, for example, S. Cho et al., Proc. SPIE, 3999 , 62 (200).
0) has also been reported. However, when using intramolecular lactonization, the rate of polarity change is relatively small,
There is a problem that it is difficult to obtain high contrast, and in the case of pinacol transition, there are problems such as substrate adhesion due to containing fluorine and storage stability due to the inclusion of maleic anhydride. Absent. The present inventors have also developed a single-layer negative chemically amplified resist using a polarity change due to an intermolecular protection reaction (JP-A-11-31860 and JP-A-11-311).
No. 05436), there is a problem that it is difficult to obtain sufficient reactivity due to the intermolecular reaction.

[0006] A negative resist can be used advantageously when it is difficult to form a mask with a positive resist or when the exposed area typified by the gate of a transistor is small, because the unexposed portion dissolves. It is also useful when using a phase shift mask or a Levenson-type mask, which is one of the promising super-resolution techniques as a technique for obtaining resolution below the wavelength, to enhance the optical image. The demand for is strong. These masks are A
When rF is used as a light source, it is expected to be applied when a resolution of 130 nm or less is required, and development of a resist capable of resolving such a fine pattern without swelling is urgently required.

Further, in recent years, as semiconductor devices have become more highly integrated, finer wiring and multi-layer wiring have been developed. Correspondingly, demands for resist materials used in the lithography process have become stricter, and dimensional accuracy after etching as well as resolution has been attracting attention as a very important characteristic. In the future, if the exposure light source shifts to shorter wavelengths, it will become difficult to maintain the transmittance of the resist itself, and the tendency to reduce the thickness of the resist will progress, and as a result, the problem of etching will become even more important. it is obvious.
In addition, the lithography technology similar to that used in semiconductor manufacturing has been used in the production of magnetoresistive heads in which the density of photomasks has been increased due to the miniaturization of wiring, and in recent years, the density has been rapidly increasing. The requirements for resist materials have a common problem.

Meanwhile, surface imaging has been proposed as an effective technique for the above-mentioned problems.
Among them, a two-layer resist method using a resist composition containing a silicon-containing resin has been studied. In the two-layer resist method, an organic resin is applied to a thickness of about 0.5 μm to form a lower resist film, and then an upper resist film having a thickness of about 0.1 μm is formed thereon. The upper layer is patterned by exposing and developing the upper layer resist film, and the lower layer is etched using the obtained upper layer pattern as a mask to form a resist pattern having a high aspect ratio. The performance required for the resist material used in the two-layer resist method is defined as oxygen reactive ion etching (O ₂
-RIE) In addition to resistance, resolution, storage stability, and the fact that a basic aqueous solution generally used in recent years for the single-layer resist method can be used, in other words, alkali development can be used. Highly required. However, currently commercially available resist materials have difficulty meeting all of these requirements simultaneously.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and can use a basic aqueous solution as a developer, has a practically usable sensitivity, and has a swelling property. It is an object of the present invention to provide a novel negative resist composition capable of forming a fine pattern having no fine pattern. Another object of the present invention is to provide a novel resist composition which is compatible with an exposure light source in the deep ultraviolet region represented by a KrF or ArF excimer laser and has excellent dry etching resistance.

Another object of the present invention is to provide a novel resist composition capable of forming a fine pattern having high sensitivity, high contrast, and high resolution by increasing the difference in polarity between exposed and unexposed portions. To provide. Still another object of the present invention is to form an upper resist film by a multi-layer resist method, because it has a high O ₂ -RIE resistance, a fine resist pattern can be obtained by development with a basic aqueous solution, and a high exposure sensitivity. Another object of the present invention is to provide a novel resist composition useful for the above.

It is another object of the present invention to provide a method for forming a resist pattern using such a resist composition. Still another object of the present invention is to provide a method for manufacturing a semiconductor device using such a resist composition as a pattern forming material. The above and other objects of the present invention will be easily understood from the following detailed description.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the chemically amplified resist composition has an alkali-soluble group as a base resin, and has a basic aqueous solution. It is effective to use a soluble film-forming polymer and to introduce an oxetane structure into the alkali-soluble polymer or into a compound used in combination with the alkali-soluble polymer. Was obtained, and the present invention was completed.

According to one aspect of the present invention, there is provided a negative resist composition containing an alkali-soluble resin as a base resin, wherein the structure of the alkali-soluble resin or the compound used in combination with the alkali-soluble resin is An oxetane structure represented by the following formula (1):

[0014]

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A negative resist composition comprising: The resist composition of the present invention is preferably provided in the form of a chemically amplified resist. That is, the resist composition of the present invention is a photoacid generator (PAG) capable of generating an acid capable of causing an oxetane structure to react when absorbed and decomposed for imaging radiation used for patterning purposes.
Thus, the resist composition itself is soluble in a basic aqueous solution, but after exposure with imaging radiation, the exposed portion becomes alkali-insoluble and can be developed with the basic aqueous solution. Here, the content of the photoacid generator depends on the strength of the acid generated after it is exposed to the exposure light source, but usually,
It is preferably in the range of 0.1 to 50% by weight (percentage based on the weight of the polymer), more preferably 1 to 15% by weight.
Range.

The alkali-soluble polymer used as the base resin is preferably a carboxyl group, a phenolic hydroxyl group, an N-hydroxyamide group, an oxime group, an imide group, in order to obtain a desired level of alkali solubility.
1,1,1,3,3,3-hexafluorocarbinol group of the following formula (2):

[0017]

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And a polymer containing at least one substituent selected from the group consisting of sulfonic acid groups. Also,
In the alkali-soluble polymer, preferably, at least one of the monomer units constituting the polymer is a (meth) acrylate monomer unit, that is, an acrylate and methacrylate monomer unit, a vinylphenol monomer unit,
N-substituted maleimide monomer units, styrene monomer units, or monomer units having a polycyclic alicyclic hydrocarbon moiety having a plurality of cyclic structures represented by norbornene. Those which are monomer units having a structure typified by an adamantyl group, a norbornyl group, or the like in the polycyclic alicyclic hydrocarbon portion are more preferable.

When the above-mentioned alkali-soluble polymer is in the form of a copolymer, the polymerization partner monomer unit of the monomer unit having an alkali-soluble group may be any one as long as the polymer can maintain appropriate alkali solubility in a developer. May have a simple structure. Further, even if the above-mentioned alkali-soluble polymer is in the form of a terpolymer, it is free as long as the polymer retains alkali solubility, as described above, and such a combination is also preferable. In this case, in addition to the first monomer unit having an alkali-soluble group, a second monomer unit having a weak alkali-soluble group may be contained, and such a combination is also preferable.

The proportion of monomer units having an alkali-soluble group in the alkali-soluble polymer used in the present invention is not limited as long as the resin itself exhibits appropriate alkali-solubility. Possible suitable alkali dissolution rate (2.38%
Dissolution rate in TMAH developer is 100 ° / s-1000
In consideration of obtaining a polymer unit having two or more components, the content of the monomer unit having an alkali-soluble group is preferably in the range of 5 to 95 mol%, more preferably 30 mol / s. ７０70 mol%. If the content of the monomer unit is less than 5 mol%, satisfactory patterning becomes impossible due to insufficient alkali solubility of an alkali-soluble group having a lower acidity than carboxylic acid. Conversely, if it exceeds 95 mol%, in the case of an alkali-soluble group having a higher acidity than that of the carboxylic acid, the alkali-solubility is too strong, and the dissolution rate in a basic aqueous solution is too high, so that patterning becomes difficult. Therefore, it is desirable to appropriately control the content of such monomer units depending on the acidity of the alkali-soluble group used.

In one aspect of the resist composition of the present invention, the alkali-soluble polymer itself preferably has an oxetane structure in its structure. In such a case, the proportion occupied by the monomer unit having an oxetane structure is not limited as long as the resin itself exhibits appropriate alkali solubility and sufficient patterning can be performed. However, the post exposure PEB (post-exposure baking) is not required. It is desirable to control the content so that the dissolution rate in the exposed portion with the 2.38% TMAH developer after the reaction is within the range of 0 to 40 ° / s. For example, in the case of a polymer comprising two or more monomers, the content of the monomer unit having an oxetane structure is preferably from 5 to 95 mol%, more preferably from 30 to 70 mol%.

According to another aspect of the present invention, it is also preferable to use a compound having an oxetane structure in the structure together with the alkali-soluble polymer of the resist composition. In such a case, although the content largely depends on the alkali dissolution rate of the polymer, the content of 1 to 80% by weight (percentage based on the weight of the polymer) for the polymer having the above-described appropriate alkali dissolution rate is high. Recommended. More preferably, 10-4
A content of 0% by weight is recommended.

In the resist composition of the present invention, the alkali-soluble resin used as the base resin is preferably a silicon-containing resin when the present invention is viewed from another aspect.
Further, the silicon-containing resin preferably contains at least one substituent such as a carboxyl group, a phenolic hydroxyl group, and hexafluorocarbinol of the above formula (2).

The silicon-containing resin preferably contains an oxetane structure in its structure. Oxetane structure-containing silicon-containing resin suitable as a base resin, preferably,
A silicon-containing polymer represented by the following formula (3) or (4):

[0025]

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[0026]

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(Where p, q and r are each positive integers). In still another aspect, the alkali-soluble resin used as the base resin may be used in combination with a compound having an oxetane structure. The oxetane structure-containing compound is preferably a silicon-containing resin represented by the following formula (5):

[0028]

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(In the above formula, n is a positive integer.) The above-mentioned alkali-soluble polymer used as a base resin in the resist composition of the present invention can be prepared according to the composition of the resist composition or the desired composition. Although it can be changed in a wide range depending on the effects and the like, it is usually preferable to have a weight average molecular weight of 2000 to 1,000,000, more preferably 300
The range is from 0 to 50,000.

The resist composition of the present invention preferably comprises ethyl lactate, methyl amyl ketone, methyl-3-methoxypropionate, ethyl-3-ethoxypropionate, propylene glycol methyl ether acetate,
Alternatively, it is provided in the form of a solution dissolved in a solvent selected from the group consisting of mixtures thereof. Also, this resist solution is, if necessary, butyl acetate, γ-butyrolactone,
A solvent selected from the group consisting of propylene glycol methyl ether and a mixture thereof may be further contained as an auxiliary solvent. The auxiliary solvent added to the resist solution is
Although not necessary depending on the solubility of the solute, when a solute with low solubility is used, it is usually added in the range of 1 to 30% by weight, more preferably 10 to 20% by weight based on the main solvent.
Range.

The resist composition of the present invention has an absorbance at a wavelength of an exposure light source (157 to 300 nm) of 1.
It is desirable to be 75 or less in order to obtain sufficient patterning characteristics. In another aspect, the present invention resides in a method for forming a negative resist pattern using the resist composition of the present invention. In the method for forming a resist pattern, the resist composition of the present invention may be used in a single-layer resist method, or may be used in a multi-layer resist method, for example, a two-layer resist method or a three-layer resist method.

The method for forming a resist pattern according to the present invention comprises:
The following steps: A resist film is formed by coating the resist composition of the present invention on a substrate to be processed, selectively exposing the resist film to imaging radiation, and exposing the exposed resist film to a basic aqueous solution. To form a negative resist pattern.

When the multilayer resist method is carried out, the method for forming a resist pattern according to the present invention comprises the following steps: forming a lower resist film by coating a first resist composition on a substrate to be processed; And on the lower resist film,
An upper resist film is formed by coating the resist composition of the present invention, the upper resist film is selectively exposed to imaging radiation, and the exposed upper resist film is developed with a basic aqueous solution to form a resist pattern. Forming, etching the underlying lower resist film using the resist pattern as a mask, and forming a negative resist pattern comprising the lower resist film and the upper resist film thereon. I do.

In the method of forming a resist pattern according to the present invention, the resist film formed on the substrate to be processed is preferably subjected to a heat treatment before and after it is subjected to a selective exposure step. That is, in the method of the present invention, it is preferable that the resist film is subjected to a pre-bake treatment before the exposure, and is also subjected to a post-bake treatment described above as PEB after the exposure and before the development.
These heat treatments can be performed according to a conventional method.

In the method of forming a resist pattern according to the present invention, radiation capable of inducing the decomposition of the photoacid generator contained in the resist composition is used as the imaging radiation. Further, the basic aqueous solution used as a developer is preferably an aqueous solution of a metal hydroxide belonging to Group I and Group II of the periodic table represented by potassium hydroxide or the like, or a tetraalkylammonium hydroxide or the like. An aqueous solution of an organic base containing no metal ions, more preferably an aqueous solution of tetramethylammonium hydroxide (TMAH). Additives such as surfactants may be added to these basic aqueous solutions to improve the developing effect.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising a step of performing the above-described method of forming a resist pattern.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION The negative resist composition of the present invention is used in the structure of an alkali-soluble resin used as a base resin or in the structure of a compound used in combination with an alkali-soluble resin. The oxetane structure represented by the formula (1) is included. Here, it is known that a compound having an oxetane structure can be used alone as a photocurable coating material.
The present invention is characterized in that the oxetane structure is introduced into a resin which is soluble in alkali and has excellent dry etching resistance as a side chain, or is added and used as a compound having an oxetane structure. Although it could not be found until now, by using the oxetane structure in such a form, it has become possible to provide a resist material particularly suitable for fine processing.

Explaining the behavior of oxetane in the resist composition of the present invention, oxetane opens under certain conditions and reacts with an alkali-soluble group such as a hydroxyl group or a carboxylic acid. After the reaction, the alkali-soluble group disappears, so that the exposed portion of the resist film becomes alkali-insoluble, so that a negative pattern can be formed after development with a basic aqueous solution. In addition, oxetane undergoes ring-opening polymerization under certain conditions, resulting in a decrease in solubility due to an increase in molecular weight due to a crosslinking reaction of the resin. Furthermore, high sensitivity can be achieved because of the amplification type which regenerates the protonic acid by the reaction. In the present invention, since the pattern is formed mainly by using the polarity change generated in the polymer, a pattern without swelling can be obtained.

In the case where the alkali-soluble polymer used as the base resin in the resist composition of the present invention is in the form of a terpolymer, the carboxylic acid is added to the first monomer unit. A weak alkali-soluble group having a representative strong alkali-soluble group and having, for example, a lactone ring structure, an acid anhydride, an imide ring structure, or the like as the second monomer unit can be used. In such a case, by controlling the content of the strong alkali-soluble group and the weak alkali-soluble group, it becomes easy to adjust the alkali dissolution rate of the base resin to a preferable value. Further, it is also possible to use a third monomer unit having a functional group having etching resistance, which is very preferable as a resist.

The structure of the alkali-soluble polymer used as the base resin in the resist composition of the present invention is not particularly limited as long as it satisfies the above-mentioned conditions, particularly the condition that it has an appropriate alkali dissolution rate. However, when consideration is given to obtaining dry etching resistance comparable to that of a novolak resist, the overlap with an acrylate monomer unit or a methacrylate monomer unit having a polycyclic alicyclic hydrocarbon compound in the ester group is considered. It is recommended to use coalesce, vinylphenol-based polymer, N-substituted maleimide-based polymer, styrene-based polymer, norbornene-based polymer and the like. In particular, acrylate-based, methacrylate-based, and norbornene-based polymers are important in that when a deep ultraviolet ray, particularly a light source having a wavelength of 250 nm or less, is used as an exposure light source, the absorption of light at that wavelength is small. In other words, when deep ultraviolet light is used as the exposure light source, a structure that generally does not include a chromophore having a large molar extinction coefficient such as an aromatic ring that absorbs light in the deep ultraviolet region or a conjugated double bond is large. It is desirable to use a polymer having

When an exposure wavelength in a short wavelength region such as an ArF excimer laser is used as a light source, transparency at the exposure wavelength (193 nm) is required together with dry etching resistance. It is recommended to use a polymer having an ester group containing a polycyclic alicyclic hydrocarbon structure such as a high adamantyl group or norbornyl group, especially an acrylate-based, methacrylate-based or norbornene-based polymer. Is done.

Further, when vacuum ultraviolet light such as an F ₂ laser (wavelength: 157 nm) is used as a light source, it is more difficult to ensure transparency. Therefore, a fluorinated norbornene-based polymer or vinyl fluoride-based polymer is required. It is recommended to combine with a fluorinated resin represented by, for example, or use an oxetane structure as a side chain of a fluorinated unit. The molecular weight (weight average molecular weight, Mw) of the above-described polymer and other alkali-soluble polymers can be changed in a wide range, but is preferably in a range of 2,000 to 1,000,000, more preferably It is 3,000-50,000.

Alkali-soluble polymers that can be advantageously used in the practice of the present invention include, but are not limited to, the following: In the formulas, l, m, and n are the numbers of monomer units (repeating units) required to obtain the above-mentioned weight average molecular weight, and R _{1 to} R ₃ are each unless otherwise specified. , An optional substituent such as a hydrogen atom,
A halogen atom (chlorine, bromine, etc.), a lower alkyl group (methyl group, ethyl group, etc.), a cyano group, a fluorinated lower alkyl group, etc., which may be the same or different. (1) Acrylate or methacrylate polymer

[0044]

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In this structural formula, R ₄ represents a weak alkali-soluble group represented by, for example, a lactone ring, and a monomer unit containing the same has an alkali dissolution rate having a value suitable for a base resin of a negative resist. Is not a required unit as long as R ₅ represents a unit having an oxetane structure. In addition, as shown in the following formula, a structure containing an ester group having a carboxylic acid which is an alkali-soluble group may of course be used.

[0046]

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In this structural formula, R ₄ has the same definition as in the previous formula. R ₆ and R ₇ both represent a unit having an H or oxetane structure, but cannot have the same structure (H or oxetane) at the same time. R _x can have any structure, but preferably has a polycyclic alicyclic structure. (2) A polymer containing a styrene unit as an alkali-soluble group as shown below

[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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In these structural formulas, R _y represents an arbitrary substituent. Preferably, R _x is selected as described above. (3) A polymer containing a fumaric acid-based unit as shown below

[0055]

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(4) A polymer containing a vinylbenzoic acid-based unit as shown below

[0057]

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[0058]

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[0059]

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(5) Polymers containing norvolic units and derivatives thereof as shown below

[0061]

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[0062]

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[0063]

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[0064]

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[0065]

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In these structural formulas, p and q are each 0 or an integer of 1 to 4, and may be the same or different. (6) Polymer containing itaconic acid-based unit as shown below

[0067]

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(7) Polymer containing maleic acid unit as shown below

[0069]

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(8) Polymers containing vinylphenol units as shown below

[0071]

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[0072]

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[0073]

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(9) A polymer containing a tetracyclododecanyl-based unit as shown below

[0075]

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[0076]

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[0077]

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[0078]

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[0079]

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As described above, these polymers may be combined with other appropriate monomer units to form an arbitrary copolymer (including those having three or more components). The alkali-soluble polymers that can be advantageously used in the practice of the present invention are described in more detail below, for example.

[0081]

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[0082]

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[0083]

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[0084]

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[0085]

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[0086]

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In the above formula, RR represents, for example, a substituent as shown below.

[0088]

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The specific examples listed above are merely examples, and the present invention is not limited to these structures. In the above formula, R _y and R ₅ are as described above.
In the above structural formula, functional groups that can be advantageously used as R ₅ include, for example, those having the following structures.

[0090]

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In the oxetanes represented by the above formula, g
Is 0 or an integer of 1 to 4, X is a hydrogen atom (H) or an alkyl group having up to 8 carbon atoms, and may have any structure such as a straight chain, a branched chain and a cyclic structure.

[0092]

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In the oxetanes represented by the above formula, R
The definitions of _x and X are as described above. The alkali-soluble polymer as described above can be prepared using a polymerization method generally used in polymer chemistry.
For example, a given monomer component can be advantageously prepared by heating in the presence of AIBN (2,2'-azobisisobutyronitrile) or the like as a free radical initiator. Also, alkali-soluble polymers other than methacrylate-based polymers can be advantageously prepared in the same manner according to a conventional method.

In addition, in the structure of the resin having high transparency in the deep ultraviolet region or the structure of the oxetane compound to be added, a structure not containing a chromophore having a large molar extinction coefficient in a wavelength range of 150 to 250 nm is appropriately selected. PA
In combination with G, a highly sensitive resist that can advantageously cope with exposure using deep ultraviolet light will be obtained. As described above, oxetane opens under certain conditions and reacts with an alkali-soluble group such as a hydroxyl group or a carboxyl group. That is, in the presence of the alkali-soluble resin, it acts as a crosslinking agent for the resin, and causes the resin to become insoluble due to an increase in the molecular weight of the alkali-soluble resin. From this, the present inventors have conceived that a composition containing these components becomes a negative resist. Oxetane also undergoes cationic polymerization under certain conditions. Therefore, when the compound having an oxetane structure shows alkali solubility, the exposed portion is insolubilized since the alkali solubility is lost by cationic polymerization. From this, the present inventors have also conceived that these compositions can be used as a negative resist.

In the resist composition of the present invention, the structure of the alkali-soluble resin is not particularly limited as long as it has an alkali-soluble group as described above. Phenolic resins and acrylic resins commonly used as base resins in single-layer resist compositions, and copolymers thereof, and further, carboxylic acids, silicon-containing resins having phenolic hydroxyl groups and hexafluorocarbinol Etc. can be used. Preferably, a silicon-containing resin represented by the above formula (4) or (5) can be used.

The compound having the oxetane structure of the above formula (1) is not particularly limited. Incidentally, these alkali-soluble resins and compounds having an oxetane structure,
As long as the above conditions are satisfied, a plurality of types may be present at the same time. The resist composition of the present invention is a chemically amplified negative resist composition comprising an alkali-soluble resin as a main component, an oxetane structure-containing compound used as necessary as a crosslinking agent, and an acid generator added thereto. Becomes

In the chemically amplified resist of the present invention, the photoacid generator (PAG) used in combination with the acid-sensitive polymer as described above is a PAG generally used in resist chemistry, that is, an ultraviolet ray. A substance that generates a protonic acid upon irradiation with radiation such as far ultraviolet rays, vacuum ultraviolet rays, electron beams, soft X-rays, and X-rays can be used. PAGs that can be used in the present invention include, but are not limited to, those listed below. (1) Onium salts:

[0098]

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In the above formula, R ″ represents a substituted or unsubstituted aromatic ring or alicyclic group, and X represents BF ₄ , PF
₆ , AsF ₆ , SbF ₆ , CF ₃ SO ₃ , ClO _{4 and the} like. (2) Sulfonates:

[0100]

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(3) Halides:

[0102]

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These PAGs can be used in various amounts in the resist composition of the present invention. P
The amount of AG used is preferably in the range of 0.1 to 50% by weight (percentage based on the weight of the polymer), more preferably 1 to 1%.
It is in the range of 5% by weight. In the resist composition of the present invention,
In particular, it is preferable to consider the structure of the polymer and PAG and the amount of PAG used so that the absorbance at the exposure wavelength becomes 1.75 or less.

The resist composition of the present invention can usually be advantageously used in the form of a resist solution by dissolving the above-mentioned alkali-soluble polymer and PAG in a suitable organic solvent. Organic solvents useful for preparing the resist solution include ethyl lactate, methyl amyl ketone, methyl-3-methoxypropionate, ethyl-3-ethoxypropionate,
Examples include, but are not limited to, propylene glycol methyl ether acetate. In addition, these solvents may be used alone or, if necessary, may be used by mixing two or more kinds of solvents. Further, the amount of the solvent used is not particularly limited, but it is preferable to use the solvent in an amount sufficient to obtain a viscosity suitable for coating such as spin coating and a desired resist film thickness.

Further, in the resist solution of the present invention, if necessary, an auxiliary solvent may be used in addition to the above-mentioned solvent (main solvent). The auxiliary solvent is not necessary depending on the solubility of the solute and the uniformity of application of the solution. However, when a solute having low solubility is used or when the uniformity of application is not in a desired state, usually 1 to 30% by weight based on the main solvent. %, Preferably in the range of 10 to 20% by weight. Examples of useful co-solvents include, but are not limited to, butyl acetate, γ-butyrolactone, propylene glycol methyl ether, and the like.

The present invention also provides a resist pattern on a substrate to be treated, using the resist composition as described above.
In particular, a method for forming a negative resist pattern is provided. The formation of the negative resist pattern of the present invention can be usually carried out as follows. First, a resist composition of the present invention is applied on a substrate to be processed,
A resist film is formed. The substrate to be processed is a semiconductor device,
The substrate may be a substrate generally used in other devices, for example, an MR head, and some examples thereof include a silicon substrate, a glass substrate, and a non-magnetic ceramic substrate. Above these substrates, if necessary, additional layers such as a silicon oxide film layer, a wiring metal layer, an interlayer insulating film layer, a magnetic film, and the like may be present. Wirings, circuits, and the like may be formed. Further, these substrates may be subjected to a hydrophobic treatment according to a conventional method in order to increase the adhesion of the resist film to the substrates. Suitable hydrophobizing agents include, for example, 1,1,1,3,3,3-hexamethyldisilazane (HMDS).

As described above, the resist composition can be applied as a resist solution onto a substrate to be processed. The application of the resist solution may be a conventional technique such as spin coating, roll coating, or dip coating, and spin coating is particularly useful. The thickness of the resist film is recommended to be in the range of about 0.01 to 200 μm.
ArF, in the case of exposure of an excimer laser, such as F _2,
A range of 0.05 to 5 μm is recommended. Note that the thickness of the formed resist film can be widely changed depending on factors such as its use.

The resist film applied on the substrate is heated to about 60 to 180 ° C. before being selectively exposed to imaging radiation.
Prebaking at a temperature of about 30 to 120 seconds. This pre-bake can be performed by using a usual heating means in the resist process. Suitable heating means include, for example, a hot plate, an infrared heating oven, a microwave heating oven and the like.

Next, the resist film after prebaking is selectively exposed to radiation for image formation using a conventional exposure apparatus. Suitable exposure apparatuses include commercially available ultraviolet (far ultraviolet, deep ultraviolet, and vacuum ultraviolet) exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, and the like. Although exposure conditions may be selected in each case appropriate conditions, in particular (KrF laser having a wavelength of 248 nm, F ₂ laser of ArF laser and wavelength 157nm wavelength 193 nm) excimer laser as mentioned earlier in the present invention It can be advantageously used as an exposure light source.
In addition, as used herein, the term "radiation" is intended to mean radiation from any of these light sources.

After the selective exposure step, the resist film after exposure is subjected to PEB, thereby causing an acid-catalyzed protection reaction of an alkali-soluble group. The post-exposure bake can be performed in the same manner as the pre-bake as long as the protection reaction sufficiently occurs. For example, PEB
Can be performed at a temperature of about 60 to 180 ° C. for about 30 to 120 seconds, but is preferably adjusted according to a desired pattern size and shape.

After PEB, the resist film is developed with a basic aqueous solution as a developing solution. For this development, a conventional developing device such as a spin developer, a dip developer, or a spray developer can be used. Here, the basic aqueous solution used as a developer is an aqueous solution of a metal hydroxide belonging to Group I and Group II of the periodic table represented by potassium hydroxide or the like, or a metal ion such as tetraalkylammonium hydroxide. Although an aqueous solution of an organic base not containing is mentioned, an aqueous solution of tetramethylammonium hydroxide (TMAH) is more preferable, and an additive such as a surfactant may be added to improve a developing effect. As a result of the development, the unexposed area of the resist film is dissolved and removed,
Only the exposure area remains on the substrate as a negative resist pattern.

The method for forming a resist pattern according to the present invention comprises:
In addition to the above-described single-layer resist method, a multilayer resist method can be advantageously used. That is, a negative resist pattern having a large aspect ratio can be formed on a substrate to be processed by using the resist composition of the present invention for forming the uppermost resist film. For example, the formation of a negative resist pattern by the two-layer resist method can be usually performed by the following procedure.

A first resist composition is coated on a substrate to be processed to form a lower resist film, and a resist composition of the present invention is coated on the lower resist film to form an upper resist film. Selectively exposing the upper resist film to imaging radiation, developing the exposed upper resist film with a basic aqueous solution to form a resist pattern, and etching the underlying lower resist film using the resist pattern as a mask. I do.

The resist pattern of the upper layer is transferred to the lower resist film, and a resist pattern having a large aspect ratio composed of the lower resist film and the upper resist film thereon is obtained. More specifically, as a resist composition for the lower layer, an organic material generally used conventionally can be used. For example, novolak resin,
It is preferable to use a commercially available resist material made of a vinylphenol resin, or a polyaniline-based or polythiophene-based conductive material. The lower resist film is usually 0.1
It is formed to a thickness of 10 to 10 μm, preferably 0.2 to 1.0 μm.

When the resist composition of the present invention is applied to form an upper resist film, a solvent is used, if necessary, as described above. The solvent that can be used and the application of the resist composition are as described above. The coating thickness of the resist composition is preferably 0.03 to 1.0 μm. If the thickness is smaller than this, the dimensional fluctuation at the time of etching increases, and if the thickness is larger, the resolution decreases. More preferred film thickness is 0.05 to
0.2 μm.

The exposure step, the development step, and the like can also be performed by the above-described method. In addition, plasma etching of a gas containing oxygen can be used for etching the lower resist film, and etching with a mixed gas of oxygen and sulfur dioxide is particularly preferable. Further, as the plasma etching apparatus, it is preferable to use a high-density plasma etching apparatus or the like.

[0117]

EXAMPLES The following examples describe the synthesis of the alkali-soluble polymer used in the present invention, the preparation of a resist composition, the formation of a resist pattern, and the manufacture of a semiconductor device. The following embodiments are merely examples, and do not limit the scope of the present invention. Example 1 Synthesis of 2-oxetanepropyl methacrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0118]

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In a 100 ml eggplant flask, 2.14 g (12.57 mmol) of 2-oxetanepropyl methacrylate was added.
l), 3-carboxyadamantyl methacrylate
15 g (23.35 mmol), a Teflon (registered trademark, the same applies hereinafter) -coated stirrer bar, 24 ml of dioxane, 885 mg (5.39 mmol) of azobisisobutyronitrile (AIBN) were added, and the mixture was placed at 70 ° C. under a nitrogen atmosphere.
And stir for 7 hours. The reaction solution was diluted with THF, dropped into 1 liter of diethyl ether containing a small amount of hydroquinone, and precipitated.
Dry at 5 ° C. for 6 hours. The obtained white powder is again T
The resin is dissolved in HF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 6.05 g (73
%). ^{From 1} H NMR, the copolymerization ratio was found to be oxetane: adamantyl = 64: 36. Weight average molecular weight 1
3,400 and the degree of dispersion was 1.43. Example 2 Synthesis of 2 -oxetanebutyl methacrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0120]

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In a 100 ml eggplant flask, 2.32 g (12.57 mmol) of 2-oxetanebutyl methacrylate were added.
6.15 g of 3-carboxyadamantyl methacrylate
(23.35 mmol), Teflon coated stir bar, 24 ml dioxane, 885 mg (5.39
mmol) of azobisisobutyronitrile (AIBN) and stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution is diluted with THF, precipitated by dripping into 1 liter of diethyl ether containing a small amount of hydroquinone, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder was dissolved again in THF,
The drying operation is repeated twice to obtain a white resin powder. Yield 6.95 g (82%). ^{From 1} H NMR, the copolymerization ratio was found to be oxetane: adamantyl = 65: 35. The weight average molecular weight was 15,800 and the degree of dispersion was 1.48. Example 3 Synthesis of methacrylic acid-3- (2'-oxetanepropyloxymethyl) adamantyl methacrylate copolymer (see the following formula)

[0122]

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In a 100 ml eggplant-shaped flask, 1.09 g (12.57 mmol) of methacrylic acid, 7.81 g (23.35 mmol) of 3- (2'-oxetanepropyl) oxymethyladamantyl methacrylate, a teflon-coated stirrer bar, 15. 5 ml of dioxane, 88
5 mg (5.39 mmol) of azobisisobutyronitrile (AIBN) is added, and the mixture is stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution is diluted with THF, precipitated by dripping into 1 liter of diethyl ether containing a small amount of hydroquinone, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 5.79 g (65%). ¹ H NMR
Thus, the copolymerization ratio was methacrylic acid: adamantyl = 36:
It turned out to be 64. The weight average molecular weight was 9,200 and the degree of dispersion was 1.50. Example 4 Synthesis of 2-oxetanepropyl acrylate-carboxytetracyclododecyl acrylate copolymer (see the following formula)

[0124]

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In a 100 ml eggplant flask, 2.08 g (13.33 mmol) of 2-oxetanepropyl acrylate was added.
Carboxytetracyclododecyl acrylate 5.05
g (20 mmol), Teflon-coated stir bar, 11.1 ml dioxane, 821 mg (5 mmol)
Of azobisisobutyronitrile (AIBN) is stirred in a nitrogen atmosphere at 70 ° C. for 7 hours. The reaction solution is THF
And precipitated by dropping into 600 ml of diethyl ether containing a small amount of hydroquinone, filtered off through a glass filter and dried at 0.1 mmHg, 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 4.88 g (68.5%). ^{From 1} H NMR, the copolymerization ratio was found to be oxetane: dodecyl = 66: 34. The weight average molecular weight was 10,900 and the degree of dispersion was 1.42. Example 5 Synthesis of 2-oxetanebutyl methacrylate-3-methoxycarbonyladamantyl methacrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0126]

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In a 100 ml eggplant flask, 2.95 g (16 mmol) of 2-oxetanebutyl methacrylate and 2.78 of 3-methoxycarbonyladamantyl methacrylate were added.
g (10 mmol), 3.7 g (14 mmol) of 3-carboxyadamantyl methacrylate, a Teflon-coated stir bar, 40 ml of dioxane, 1.97 g
(12 mmol) of azobisisobutyronitrile (AIB)
N) and stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution was diluted with THF and contained a small amount of hydroquinone.
The solution is precipitated by dropping into 1 l of diethyl ether, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 7.07 g (75%). ^{From 1} H NMR, the copolymerization ratio was found to be oxetane: methoxycarbonyladamantyl: carboxyadamantyl = 53: 13: 34. The weight average molecular weight was 19,500 and the degree of dispersion was 1.52. Example 6 Synthesis of 2-oxetanepropyl methacrylate-5-norbornane-2,6-carboractone methacrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0128]

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In a 100 ml eggplant flask, 3.40 g (20 mmol) of 2-oxetanepropyl methacrylate,
1.33 g (6 mmol) of norbornane-2,6-carboractone methacrylate, 3.7 g (14 mmol) of 3-carboxyadamantyl methacrylate, a teflon-coated stirrer bar, 40 ml of dioxane,
97 g (12 mmol) of azobisisobutyronitrile (A
IBN) and stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution is diluted with THF, precipitated by dripping into 1 liter of diethyl ether containing a small amount of hydroquinone, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 5.41 g (58%). ¹ H NMR
From this, it was found that the copolymerization ratio was oxetane: norbornyl: adamantyl = 55: 11: 34. Weight average molecular weight 1
8,700 and the degree of dispersion was 1.49. Example 7 Synthesis of 3- (2'-oxetanepropyloxy) adamantyl acrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0130]

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In a 100 ml eggplant flask, 3.06 g (10 mmol) of 3- (2'-oxetanepropyloxy) adamantyl acrylate, 1.25 g (5 mmol) of 3-carboxyadamantyl acrylate, a teflon-coated stirrer bar, 10 ml of dioxane, 36
9 mg (2.25 mmol) of azobisisobutyronitrile (AIBN) is added, and the mixture is stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution is diluted with THF, precipitated by dropping into 500 ml of diethyl ether containing a small amount of hydroquinone, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 2.34 g (55%). ¹ H
From NMR, the copolymerization ratio was found to be oxetane: carboxyadamantyl = 64: 36. Weight average molecular weight 18,
200 and the degree of dispersion was 1.41. Example 8 Synthesis of 2-oxetanepropyloxynorbornene-maleic anhydride-1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypropylnorbornene copolymer (see the following formula)

[0132]

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In a 100 ml eggplant flask, 1.92 g (10 mmol) of 2-oxetanepropyloxynorbornene,
0.98 g (10 mmol) of maleic anhydride, 1,1,1-
2.62 g (10 mmol) of trifluoro-2-trifluoromethyl-2-hydroxypropylnorbornene, a teflon-coated stir bar, 20 ml of dioxane, 493 mg (3 mmol) of azobisisobutyronitrile (AIBN) were added, and nitrogen was added. Stir at 70 ° C. for 7 hours in an atmosphere. The reaction solution is diluted with THF, precipitated by dripping into 1 liter of diethyl ether containing a small amount of hydroquinone, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 3.42 g (62%). ¹ H
From NMR, the composition ratio was found to be 1: 1: 1. The weight average molecular weight was 9,400 and the degree of dispersion was 1.33. Example 9 Synthesis of 2-oxetanepropyl methacrylate-maleic anhydride-norbornene carboxylic acid copolymer (see the following formula)

[0134]

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In a 100 ml eggplant-shaped flask, 1.70 g (10 mmol) of 2-oxetanepropyl methacrylate, 0.98 g (10 mmol) of maleic anhydride, 1.38 g (10 mmol) of norbornenecarboxylic acid, a teflon-coated stir bar, 20 ml of dioxane , 493mg
(3 mmol) of azobisisobutyronitrile (AIBN)
And stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution is diluted with THF, precipitated by dripping into 1 liter of diethyl ether containing a small amount of hydroquinone, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours.
The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder.
Yield 2.35 g (58%). ^{From 1} H NMR, the composition ratio was found to be 1: 1: 1. Weight average molecular weight 9,100,
The dispersity was 1.44. Example 10 Synthesis of 2-oxetanebutyl acrylate-hydroxystyrene copolymer (see the following formula)

[0136]

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100 ml of 2-oxetanebutyl acrylate 410 mg (2.41 mmol), acetoxystyrene 4.66 g (27.75 mmol), a teflon-coated stir bar, 10 ml of dioxane, 743 mg
(4.5 mmol) of azobisisobutyronitrile (AIB)
N) and stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution was diluted with THF and contained a small amount of hydroquinone.
1 ml of methanol to precipitate, filter off with a glass filter, and dry at 0.1 mmHg, 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated to obtain a white resin powder. This is treated with a basic methanol solution to obtain the desired resin. Yield 2.8g. ^{From 1} H NMR, the composition ratio was oxetane:
Hydroxystyrene was found to be 92: 8. The weight average molecular weight was 7,800 and the degree of dispersion was 1.33. Example 11 Synthesis of 6-methoxy-2-tetrahydropyranylmethyl methacrylate-3,4-carboractone adamantyl methacrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0138]

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In a 100 ml eggplant flask, 3.40 g (20 mmol) of 2-oxetanepropyl methacrylate,
4-carboractone adamantyl methacrylate 1.6
6 g (6 mmol), 3.7 g (14 mmol) of 3-carboxyadamantyl methacrylate, Teflon-coated stir bar, 40 ml of dioxane, 1.97 g
(12 mmol) of azobisisobutyronitrile (AIB)
N) and stirred at 70 ° C. for 7 hours under a nitrogen atmosphere. The reaction solution was diluted with THF and contained a small amount of hydroquinone.
The solution is precipitated by dropping into 1 l of diethyl ether, filtered off with a glass filter, and dried at 0.1 mmHg and 45 ° C. for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 5.26 g (60%). ^{From 1} H NMR, the copolymerization ratio was oxetane: lactone: adamantyl = 52:
It turned out to be 15:33. Weight average molecular weight 17,100,
The dispersity was 1.41. Example 12 Synthesis of 3- (2-oxetanepropyloxy) adamantyl methacrylate-3,4-carboractone adamantyl methacrylate-3-carboxyadamantyl methacrylate copolymer (see the following formula)

[0140]

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In a 100 ml eggplant flask, 6.17 g (20 mmol) of 3- (2-oxetanepropyloxy) adamantyl methacrylate, 1.66 g (6 mmol) of 3,4-carboractone adamantyl methacrylate, and 3.7 g of 3-carboxyadamantyl methacrylate ( 14mm
ol), Teflon-coated stirrer bar, 4
0 ml of dioxane, 1.97 g (12 mmol) of azobisisobutyronitrile (AIBN) are added, and the mixture is stirred under a nitrogen atmosphere at 70 ° C. for 7 hours. The reaction solution was diluted with THF, dropped into 1 liter of diethyl ether containing a small amount of hydroquinone, and precipitated.
Dry at 45 ° C., Hg for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 8.88 g (77
%). ^{From 1} H NMR, the copolymerization ratio was found to be oxetane: lactone: adamantyl = 54: 12: 34. The weight average molecular weight was 21,000 and the degree of dispersion was 1.47. Example 13 Synthesis of 3- (2-oxetanebutyloxy) adamantyl methacrylate-N-hydroxymethacrylamide-methacrylic acid copolymer (see the following formula)

[0142]

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In a 100 ml eggplant flask, 3- (2-oxetanebutyloxy) adamantyl methacrylate
82 g (16 mmol), N-hydroxymethacrylamide 2.02 g (6 mmol), methacrylic acid 861 mg (10 mm
ol), Teflon-coated stirrer bar, 2
0 ml of dioxane and 788 mg (4.8 mmol) of azobisisobutyronitrile (AIBN) are added, and the mixture is stirred under a nitrogen atmosphere at 70 ° C. for 7 hours. The reaction solution was diluted with THF, dropped into 1 liter of diethyl ether containing a small amount of hydroquinone, and precipitated.
Dry at 45 ° C., Hg for 6 hours. The obtained white powder is dissolved again in THF, and the above-described precipitation-drying operation is repeated twice to obtain a white resin powder. Yield 4.47 g (58
%). ^{From 1} H NMR, the copolymerization ratio was found to be adamantyl: amide: methacrylic acid = 65: 5: 30. The weight average molecular weight was 9,900 and the degree of dispersion was 1.52. Example 14 The resin of Example 1 was dissolved in EL (ethyl lactate) to obtain 13 wt.
% Solution. Note that this solution contains 10
wt% of γ-butyrolactone was also included. To the obtained solution, 2% by weight of triphenylsulfonium trifluoromethanesulfonate was added and sufficiently dissolved. After the obtained resist solution was filtered through a 0.2 μm Teflon membrane filter, it was spin-coated on a HMDS-treated silicon substrate, and prebaked at 110 ° C. for 60 seconds.
A resist film having a thickness of 0.4 μm was formed. This is called KrF
After exposure with an excimer laser stepper (NA = 0.45), the film was baked at 120 ° C. for 60 seconds, developed with a 2.38% tetramethylammonium hydroxide (TMAH) developer, and then rinsed with deionized water. Exposure 17.0
0.25 μm L / S was resolved at mJ / cm ² . Example 15 A resist film having a thickness of 0.4 μm was formed using the resist of Example 14. ArF excimer laser stepper (NA
= 0.60), baked at 120 ° C. for 60 seconds, developed with a 2.38% TMAH developer, and rinsed with deionized water. 0.15 μm at an exposure of 9.0 mJ / cm ²
L / S was resolved. Example 16 A resist was prepared using the resin of Example 2 in the same manner as in Example 14, to form a resist film having a thickness of 0.4 μm. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 12 mJ / cm ² . Example 17 Using the resin of Example 3, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 130 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 11 mJ / cm ² . Example 18 Using the resin of Example 4, a resist was prepared in the same manner as in Example 14, to form a resist film having a thickness of 0.4 μm. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 14 mJ / cm ² . Example 19 Using the resin of Example 5, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 8 mJ / cm ² . Example 20 Using the resin of Example 6, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 9 mJ / cm ² . Example 21 Using the resin of Example 7, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 8 mJ / cm ² . Example 22 Using the resin of Example 8, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 18 mJ / cm ² . Example 23 A resist was prepared using the resin of Example 9 in the same manner as in Example 14, to form a resist film having a thickness of 0.4 μm. Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 14 mJ / cm ² . Example 24 Using the resin of Example 10, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. K
After exposure with an rF excimer laser stepper (NA = 0.68), baking was performed at 110 ° C. for 60 seconds, and 2.38% T
After development with a MAH developer, the substrate was rinsed with deionized water. 0.18 μm L / S was resolved at an exposure dose of 13 mJ / cm ² . Example 25 10 wt% of 2-oxetanepropyl methacrylate homopolymer (molecular weight: 5,600) in polyhydroxystyrene
And a resist was prepared by EL. After forming a resist film having a thickness of 0.4 μm, exposing with a KrF excimer laser stepper (NA = 0.68), baking at 110 ° C. for 60 seconds, developing with a 2.38% TMAH developer, deionized water Rinsed. 0.22μ at 15mJ / cm ² exposure
ml / S was resolved. Example 26

[0144]

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12% by weight of 2-oxetanepropyl methacrylate homopolymer (molecular weight: 5,600) was added to the resin having the above structural formula (molecular weight: 9,500), and a resist was prepared by EL. A resist film having a thickness of 0.4 μm is formed, and Ar
After exposure with an F excimer laser stepper (NA = 0.60), baking was performed at 110 ° C. for 60 seconds, and TM of 2.38% was obtained.
After development with an AH developer, the substrate was rinsed with deionized water. 0.16 μm L / S was resolved at an exposure dose of 17 mJ / cm ² . Example 27 Using the resin of Example 11, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. A
After exposure with an rF excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and 2.38% T
After development with a MAH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 13 mJ / cm ² . Example 28 Using the resin of Example 12, a resist was prepared in the same manner as in Example 14, and a resist film having a thickness of 0.4 μm was formed. A
After exposure with an rF excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and 2.38% T
After development with a MAH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 12 mJ / cm ² . Example 29 Using the resin of Example 13, a resist was prepared in the same manner as in Example 14, to form a resist film having a thickness of 0.4 μm. A
After exposure with an rF excimer laser stepper (NA = 0.60), baking was performed at 120 ° C. for 60 seconds, and 2.38% T
After development with a MAH developer, the substrate was rinsed with deionized water. 0.15 μm L / S was resolved at an exposure dose of 18 mJ / cm ² . Example 30 A resist film having a thickness of 1 μm was formed on a silicon substrate using the resists of Examples 5, 7, 8, 10, 26 and 28 described above. For comparison, a commercially available novolak resist, PFI-
16 (manufactured by Sumitomo Chemical Co., Ltd.) and PMMA (polymethyl methacrylate) using a parallel plate RIE apparatus
Etching was performed for 5 minutes under the conditions of 0 W, pressure = 0.02 Torr, and CF ₄ gas = 100 sccm, and the film thickness reduction of the samples was compared. The results as shown in Table 1 below were obtained.

[0146]

[Table 1]

From the results shown in Table 1 above, the etching resistance of the resist according to the present invention is close to that of the novolak resist, and particularly, in the resists of Examples 7 and 28, A
It had a composition that could be used for rF exposure, and exhibited resistance equal to or higher than that of novolak. From this experiment, it was confirmed that each of the resists was significantly superior to PMMA. In the resist patterns of Examples 5, 7, 8, 10, 26 and 28, no swelling was observed. Example 31 Synthesis of silicon-containing resin (see the following formula)

[0148]

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In a four-necked flask equipped with a reflux tube and a thermometer and having a nitrogen flow, 6.9 g (0.023 mol) of 1,3-bis (carboxypropyl) tetramethyldisiloxane, 35 ml of pure water, and acetic acid 20. Add 6 ml and stir,
The temperature is raised to 60 ° C. by an oil bath. 12.48 g (0.06 mol) of tetraethoxysilane is dropped into the mixture in 30 minutes, and the mixture is reacted for 1 hour. Next, 6.24 g (0.03 mol) of tetraethoxysilane was added to the mixture.
For 30 minutes, and the reaction is carried out for 3 hours. After allowing to cool to room temperature, the reaction solution is transferred to a separatory funnel, and 100 ml of water and 100 ml of methyl isobutyl ketone (MIBK) are added, followed by solvent extraction. Thereafter, the organic layer was filtered through a liquid separation filter paper,
It is transferred to a four-necked flask, and water is removed by azeotropic distillation to obtain a MIBK solution of a tetrafunctional siloxane resin.

Next, a reflux tube and a thermometer were attached, and a MIBK solution and a tetrahydrofuran solution, which had been concentrated to about half, were added to a four-necked flask with a nitrogen flow. While stirring at room temperature, trimethylsilyl imidazole 12.0 was added.
g (0.84 mol) is added dropwise and reacted for 2 hours. After adding 18 ml of hydrochloric acid, the mixture is filtered through a liquid phase separation filter paper, transferred to a four-necked flask, and drained by azeotropic distillation. Further, this component is concentrated and the component precipitated with hexane is freeze-dried with dioxane. The desired silicon-containing resin having a molecular weight of 6000 was obtained in a yield of 85%. Example 32 A molecular weight of 60 represented by the formula (4) synthesized in Example 31
00 and 100 parts by weight of the alkali-soluble silicon-containing resin of formula (3), a silicon-containing resin having an oxetane structure and a molecular weight of 3000 (Japanese Patent Laid-Open No. 6-16804).
Synthesized by the synthesizing method described in Japanese Patent Publication No.

[0151]

Embedded image

100 parts by weight and 5 parts by weight of triphenylsulfonium triflate are dissolved in propylene glycol monomethyl ether acetate (PGMEA),
A resist solution was prepared. The obtained resist solution was spin-coated on a hexamethyldisilazane-treated silicon (Si) substrate, and prebaked at 100 ° C./60 seconds.
A 14 μm thick resist film was formed. After exposing this resist film with a KrF excimer laser stepper (NA = 0.45), it was baked at 135 ° C. for 60 seconds and 2.38% T
Development was carried out with an aqueous MAH solution. With an exposure of 7 mJ / cm ² ,
A 0.25 μm line & space pattern was resolved. Example 33 Molecular weight of 60 represented by the formula (4) synthesized in Example 31
Of 100 parts by weight of the alkali-soluble silicon-containing resin of No. 00, 70 parts by weight of a silicon-containing resin having an oxetane structure represented by the formula (3) and having a molecular weight of 3000, and 3 parts by weight of triphenylsulfonium triflate were added to methyl isobutyl ketone. (MIBK) to prepare a resist solution.

First, a novolak resin-based solution was spin-coated on a Si substrate and baked in an oven at 280 ° C. for 3 hours to form a lower resist film having a thickness of 0.4 μm.
Next, the resist solution prepared as described above was spin-coated on the lower resist film and prebaked at 110 ° C. for 60 seconds to form an upper resist film having a thickness of 0.1 μm.
After exposing the obtained two-layer structure resist film with an ArF excimer laser exposure apparatus, baking was performed at 140 ° C. for 60 seconds,
Development was performed with a 2.38% TMAH aqueous solution. Exposure 10
A 0.17 μm line & space pattern was resolved at mJ / cm ² . As a mask layer a resist pattern obtained in Example 34 Example 33, was transferred to the resist pattern to the lower resist film with O ₂ -RIE. The conditions of O ₂ -RIE are as follows: RF power: 0.16 W / cm ² , oxygen flow rate: 10 sccm, gas pressure:
10 mTorr. The result of the etching rate in this example is
The plot is shown in FIG. The upper resist is about 100 times as large as the lower resist under the same conditions as above.
_It showed _2- RIE resistance. As a result, it was confirmed that the 0.17 μm line & space pattern obtained by the upper layer patterning can be transferred to the lower layer resist without causing dimensional fluctuation. Example 35 A molecular weight of 60 represented by the formula (4) synthesized in Example 31
100 parts by weight of the alkali-soluble silicon-containing resin of the formula (3), 50 parts by weight of a silicon-containing resin having an oxetane structure having a molecular weight of 3000 represented by the above formula (3) and 5 parts by weight of triphenylsulfonium triflate were added to methyl isobutyl ketone. (MIBK) to prepare a resist solution.

In the same manner as in Example 33, 0.4
After forming a lower resist film having a thickness of μm, the resist solution prepared as described above is spin-coated on the lower resist film, and prebaked at 110 ° C. for 60 seconds to form a resist film having a thickness of 0.1 μm.
An m-thick upper resist film was formed. After exposing the obtained double-layered resist film with an electron beam exposure apparatus, 135 ° C./6
It was baked for 0 second and developed with a 2.38% TMAH aqueous solution. A 0.125 μm line & space pattern was resolved at an exposure amount of 45 μC / cm ² . Example 36 Using the upper resist pattern obtained in Example 35 as a mask, the resist pattern was transferred to the lower resist film by O ₂ -RIE. The conditions for O ₂ -RIE were the same as in Example 34.
And the same conditions. In the case of this example, the upper layer resist was about 90 times as resistant to O ₂ -RIE as the lower layer resist. As a result, 0.125 μm obtained by upper layer patterning
It was confirmed that the line & space pattern could be transferred to the lower resist without causing dimensional fluctuation. Example 37 A specific method for producing a device using the resist composition according to the present invention will be described below.

FIG. 2 sequentially shows a method of forming a gate wiring pattern requiring a high aspect ratio.
On the silicon substrate 1, a MOS transistor 10 whose elements are separated by field oxidation is formed. This MOS
An insulating layer 21 is formed over the gate electrode of the transistor, and an opening for leading a wiring from the gate electrode 11 is formed by lithography. Thereafter, a thin film 31 of titanium nitride (TiN) used as a barrier metal is formed, and a thin film 32 of Al as a wiring material is deposited thereon (see step A in FIG. 2).

In order to process this Al / TiN film as a wiring pattern, a resist pattern 42 serving as an etching mask is formed on the Al / TiN laminated film in accordance with the method described in Embodiment 32. Thereafter, using the obtained resist pattern as an etching mask, the pattern is transferred to a lower layer using oxygen plasma etching (see step B in FIG. 2). Further, the resist pattern 42 is removed by fluorine plasma etching to complete the etching mask 41 using the lower resist.

Using this etching mask 41, the Al / Ti laminated film to be etched is etched using chlorine-based plasma to complete a gate wiring pattern with a high aspect ratio (see step C in FIG. 2). . The present invention has been described with reference to the embodiments and examples. Finally, for a better understanding of the invention, preferred embodiments of the invention are organized and described below.

(Supplementary Note 1) A negative resist composition containing an alkali-soluble resin as a base resin, wherein the structure of the alkali-soluble resin or the compound used in combination with the alkali-soluble resin has the formula (I) A negative resist composition comprising the oxetane structure represented by 1).

(Supplementary Note 2) The oxetane structure further contains a photoacid generator capable of generating an acid capable of causing a reaction when absorbed and decomposed by imaging radiation, and is itself soluble in a basic aqueous solution. 2. The negative resist composition according to claim 1, wherein the exposed portion becomes alkali-insoluble after exposure to the imaging radiation and can be developed with a basic aqueous solution.

(Supplementary Note 3) The alkali-soluble resin is
Carboxyl group, phenolic hydroxyl group, N-hydroxyamide group, oxime group, imide group, 1 of the formula (2)
Supplementary note 1 characterized by being a polymer containing at least one substituent selected from the group consisting of a 1,1,3,3,3-hexafluorocarbinol group and a sulfonic acid group.
Or the negative resist composition according to 2.

(Supplementary Note 4) The alkali-soluble resin is
The negative type according to any one of Supplementary notes 1 to 3, wherein the polymer is derived from acrylic acid, methacrylic acid, itaconic acid, vinylbenzoic acid, norbornene, vinylphenol, styrene, and derivatives thereof. Resist composition. (Supplementary Note 5) The alkali-soluble resin is a lactone ring,
The negative resist composition according to any one of Supplementary notes 1 to 4, wherein the composition is a polymer containing at least one kind of weak alkali-soluble group selected from the group consisting of an imide ring and an acid anhydride.

(Supplementary Note 6) The alkali-soluble resin is
The negative resist composition according to any one of supplementary notes 1 to 5, wherein the negative resist composition is a polymer containing a polycyclic alicyclic hydrocarbon moiety. (Supplementary Note 7) When the polycyclic alicyclic hydrocarbon moiety is an adamantyl group, a norbornyl group, and a bicyclo [2.2.2]
7. The negative resist composition according to claim 6, comprising a member selected from the group consisting of octyl groups.

(Supplementary Note 8) The negative resist composition according to Supplementary Note 7, wherein the polycyclic alicyclic hydrocarbon moiety contains at least one alkoxycarbonyl group or ketone group either alone or simultaneously. (Supplementary Note 9) The negative resist composition as described in any one of Supplementary Notes 3 to 8, wherein the alkali-soluble resin has an oxetane structure represented by the above formula (1) in its structure.

(Supplementary Note 10) The negative resist composition according to any one of Supplementary Notes 3 to 8, wherein the alkali-soluble resin is a silicon-containing resin. (Supplementary Note 11) The negative resist composition according to Supplementary Note 10, wherein the silicon-containing resin has an oxetane structure represented by the formula (1) in its structure.

(Supplementary Note 12) The negative resist composition according to Supplementary Note 11, wherein the silicon-containing resin is a silicon-containing polymer represented by the above formula (3) or (4). (Supplementary Note 13) The negative resist composition according to any one of Supplementary Notes 1 to 12, wherein the compound used in combination with the alkali-soluble resin is a silicon-containing polymer represented by the formula (5). object.

(Supplementary note 14) Supplementary notes 1 to 1, wherein the absorbance at the wavelength of the exposure light source is 1.75 or less.
4. The negative resist composition according to any one of items 3 to 5. (Supplementary Note 15) A solvent selected from the group consisting of ethyl lactate, methyl amyl ketone, methyl-3-methoxypropionate, ethyl-3-ethoxypropionate and propylene glycol methyl ether acetate, alone or in combination. Supplementary notes 1 to 14 characterized by the following.
The negative resist composition according to any one of the above.

(Supplementary note 16) The negative resist composition according to Supplementary note 15, further comprising a solvent selected from the group consisting of butyl acetate, γ-butyrolactone and propylene glycol methyl ether as an additional solvent. (Supplementary Note 17) A resist film is formed by coating the resist composition according to any one of Supplementary Notes 1 to 16 on a substrate to be processed, and selectively exposing the resist film to imaging radiation; A method of forming a resist pattern, comprising developing a resist film after exposure with a basic aqueous solution to form a negative resist pattern.

(Supplementary Note 18) The lower resist film is formed by coating the first resist composition on the substrate to be processed, and the lower resist film is formed on the lower resist film. Forming an upper resist film by coating the resist composition, selectively exposing the upper resist film to imaging radiation, developing the exposed upper resist film with a basic aqueous solution to form a resist pattern, The resist pattern according to claim 17, wherein the underlying lower resist film is etched using the resist pattern as a mask to form a negative resist pattern including the lower resist film and the upper resist film thereon. Formation method.

(Supplementary Note 19) As the imaging radiation,
19. The method of forming a resist pattern according to Supplementary Note 17 or 18, wherein radiation capable of inducing the decomposition of the photoacid generator contained in the resist composition is used. (Supplementary Note 20) A method for manufacturing a semiconductor device, comprising a step of performing the resist pattern forming method according to any one of Supplementary Notes 17 to 19.

[0170]

By using the resist composition according to the present invention, a fine negative resist pattern free from swelling with practical sensitivity can be formed. Further, when the alkali-soluble polymer of the resist composition is in the form of a terpolymer, and the first monomer unit contains a strong alkali-soluble group and the second monomer unit contains a weak alkali-soluble group, It is easy to control alkali solubility, and since it contains an oxetane structure, an intermolecular or intramolecular reaction can be adopted, so that a pattern can be formed by polarity change along with the conventional cross-linking type, and high contrast and resolution can be achieved. Can easily be obtained.

Furthermore, the resist composition of the present invention can be used not only in a single-layer resist method but also in a two-layer resist method or other multi-layer resist methods. High sensitivity in short wavelength range,
The requirement of etching resistance can be satisfied. Furthermore, the method for forming a resist pattern using the resist composition of the present invention can not only achieve high integration of a semiconductor device, but also manufacture MR heads and the like, which have been increasingly dense in recent years. It can be easily realized.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of O ₂ -RIE resistance in a two-layer resist method using a resist composition according to the present invention.

FIG. 2 is a sectional view sequentially showing a method of forming a wiring pattern using a resist composition according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 10 ... MOS transistor 11 ... Gate electrode 12 ... Gate oxide film 21 ... Insulating layer 31 ... Titanium nitride thin film 32 ... Aluminum thin film 41 ... Etching mask 42 ... Resist pattern

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Miwa Ozawa 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Keiji Watanabe 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 Inside Fujitsu Limited

Claims (10)

[Claims] 1. A negative resist composition comprising an alkali-soluble resin as a base resin, wherein the composition of the alkali-soluble resin or the compound used in combination with the alkali-soluble resin has the following formula (1):
Oxetane structure represented by: A negative resist composition comprising: 2. The oxetane structure further includes a photoacid generator capable of generating an acid capable of causing a reaction when absorbing and decomposing the imaging radiation, and the oxetane structure itself is soluble in a basic aqueous solution. 2. The negative resist composition according to claim 1, wherein the exposed portion becomes alkali-insoluble after exposure to radiation for use and can be developed with a basic aqueous solution. 3. The method according to claim 1, wherein the alkali-soluble resin comprises a carboxyl group, a phenolic hydroxyl group, an N-hydroxyamide group,
Oxime group, imide group, 1,1,1,3 of the following formula (2)
3,3-hexafluorocarbinol group: And at least one member selected from the group consisting of
The negative resist composition according to claim 1, wherein the composition is a polymer containing various kinds of substituents. 4. The method according to claim 1, wherein the alkali-soluble resin is a polymer derived from acrylic acid, methacrylic acid, itaconic acid, vinylbenzoic acid, norbornene, vinylphenol, styrene and derivatives thereof. 4. The negative resist composition according to any one of items 1 to 3, wherein 5. The negative resist composition according to claim 3, wherein the alkali-soluble resin has an oxetane structure represented by the following formula (1) in its structure. 6. The negative resist composition according to claim 3, wherein the alkali-soluble resin is a silicon-containing resin. 7. The negative resist composition according to claim 6, wherein the silicon-containing resin has an oxetane structure represented by the following formula (1) in its structure. 8. A compound used in combination with the alkali-soluble resin, wherein the compound is a silicon-containing polymer represented by the following formula (5): The negative resist composition according to claim 1, wherein, in the above formula, n is a positive integer. 9. A resist film is formed by coating the resist composition according to claim 1 on a substrate to be processed, and the resist film is selectively exposed to imaging radiation. And developing the exposed resist film with a basic aqueous solution to form a negative resist pattern. 10. A method of manufacturing a semiconductor device, comprising a step of performing the method of forming a resist pattern according to claim 9.