JPH0990637A - Resist composition and resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resist compsn. having a sensitivity capable of practical use and capable of forming a nonswellable fine resist pattern. SOLUTION: An acid-sensitive polymer contained in this chemical amplification type resist compsn. in combination with an optical acid generating agent contains a lactone part represented by the formula [where R is optionally substd. 1-4C straight chain or branched chain alkyl and (n) is an integer of 1-4] as a protective group for each carboxyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist composition, and more particularly to a resist composition which can use light having a shorter wavelength, such as an excimer laser, as an image-forming radiation, and after exposure, a basic aqueous solution. The present invention relates to a resist composition that can be developed. The present invention also relates to a method for forming a positive resist pattern using such a resist composition. The resist composition of the present invention,
It belongs to the category of so-called "chemically amplified resists", and can form a fine positive pattern without swelling with practical sensitivity.

[0002]

2. Description of the Related Art In recent years, high integration of semiconductor integrated circuits has progressed, and LSIs and VLSIs have been put into practical use. The minimum line width of a wiring pattern extends to a sub-half micron area. For this reason, it is essential to establish a fine processing technology, and in the field of lithography,
The wavelength of the ultraviolet light of the exposure light source has been shifted to a short wavelength in the far ultraviolet region, and the development of an exposure apparatus using a light source of a wavelength in the deep ultraviolet region has been actively pursued. Along with this, there is an urgent need to develop a resist material that absorbs light at a short wavelength as described above, has high sensitivity, and has high dry etching resistance.

Currently, as a new exposure technique in semiconductor manufacturing, a krypton fluoride excimer laser (wavelength 248) is used.
nm, hereinafter KrF) has been actively researched, and there is an urgent need to develop a resist having good sensitivity and resolution in such a short wavelength region and having stability. Is coming. As a resist having a high sensitivity and a high resolution that can be applied to such a short wavelength light source, a resist composition using a concept called a chemically amplified type is disclosed by H.M. Have already been presented by Ito et al. (Eg JM J. Frechet et al.
Proc. Microcircuit Eng. , 26
0 (1982), H.M. Ito et al., Digest of
Technical Papers of 1982
Symposium on VLSI Technology
Ogy, 86 (1983), H.A. Ito et al., “Poly
mers in Electronics ”, ACS
Symposium Series 242, T.W. Da
Vidson Ed., ACS, 11 (1984), and US Pat. No. 4,491,628). The basic concept of the resist composition is, as can be easily understood from the above-mentioned documents and the like, to cause a catalytic reaction in the resist film to improve the apparent quantum yield, and thus to improve the sensitivity of the resist composition. It is based on trying to achieve

Currently, t-butoxycarbonylpolyvinylphenol (t-BOCPV), which has been very extensively studied,
As an example of a chemically amplified resist in which a photo-acid generator (PAG) having a function of generating an acid by light is added to P), in the exposed portion of the resist, heating after exposure, so-called “PEB (post-exposure)” is performed. ), The t-BOC group is eliminated to give isobutene and carbon dioxide. Further, the above-mentioned deprotection reaction progresses in a chain by using the protonic acid generated upon elimination of t-BOC as a catalyst, and the polarity of the exposed portion is largely changed. In the resist of this example, a resist pattern can be easily formed by selecting an appropriate developing solution that can cope with a large change in the polarity of the exposed portion.

However, the conventional chemical amplification type resist has requirements such as sensitivity, transparency at exposure wavelength, storage stability, easy availability, and resolution because the chemical structure of the resin is limited. It has a problem that it is difficult to meet all. Of particular importance is the restriction of the protecting groups in the chemically amplified resist to be eliminated by heat treatment in the presence of a photoacid generator. That is, when the chemical amplification component present in the side chain of the monomer unit of the film-forming polymer is a carboxylic acid ester, suitable protecting groups for the carboxyl group are t-butyl group and 1,1-dimethylbenzyl group. A group, a tetrahydropyranyl group, a 3-oxocyclohexyl group, an isobornyl group and the like are merely known, and it is desired to provide a protecting group that can act more effectively.

[0006]

The object of the present invention is therefore to solve the problems of the prior art as described above, and to use a basic aqueous solution as a developer.
It is an object of the present invention to provide a novel resist composition having practical sensitivity and capable of forming a fine pattern without swelling.

Another object of the present invention is to provide a novel resist composition which can be applied to an exposure light source in the deep ultraviolet region such as KrF 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 pattern having high sensitivity, high contrast and thus high resolution by increasing the polarity between exposed and unexposed areas. To provide.

Another object of the present invention is to provide a method for forming a resist pattern using such a novel resist composition.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, as a polymer used as a base resin in a chemically amplified resist composition,
It is effective to use a film-forming polymer having a protective group-containing carboxyl group in the side chain of the monomer unit, and to use a polymer having a specific lactone moiety as the carboxyl group protecting group of the polymer. That is, the present invention has been completed and the present invention has been completed.

In one of its aspects, the present invention is a film-forming polymer having a protecting group-containing carboxyl group in the side chain of a monomer unit, which is itself insoluble in a basic aqueous solution, provided that the above-mentioned carboxyl group is used. When the protective group of is removed from the side chain, an acid-sensitive polymer that may be soluble in a basic aqueous solution and absorption of image-forming radiation to decompose may cause elimination of the protective group of the carboxyl group. A photoacid generator capable of generating an acid, wherein the acid-sensitive polymer is a lactone moiety represented by the following formula (I):

[0011]

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(In the above formula, R represents a linear or branched alkyl group having 1 to 4 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, etc., and these groups are substituted or unsubstituted. , And n
Is an integer of 1 to 4) as a protecting group for the carboxyl group, and is a resist composition developable with a basic aqueous solution.

In the resist composition according to the present invention, the acid-sensitive polymer used as the base resin is used in a broad sense, and therefore, from a homopolymer consisting of only a single monomer unit, And various copolymers of any other monomer unit (including a three-component copolymer). The polymer used herein is preferably a polymerisation of at least one of the monomer units constituting it, and in particular when the polymer is in the form of a copolymer, of a monomer unit having a carboxyl group containing protective groups. The other monomer unit is
(Meth) acrylate-based monomer units, that is, acrylate-based and methacrylate-based monomer units, vinylphenol-based monomer units, N-substituted maleimide-based monomer units, styrene-based monomer units, or multiple or polycyclic alicyclic hydrocarbons It is a monomer unit having an ester group containing a portion, more preferably,
The alicyclic hydrocarbon moiety is a monomer unit having an ester group containing a plurality of or polycyclic alicyclic hydrocarbon moieties, which are adamantyl groups and / or norbornyl groups.

Further, in such an acid-sensitive polymer, the lactone moiety as a protecting group for the carboxyl group contained in the side chain thereof can have any structure, but preferably it is represented by the following formula (IV): Represented (±) −
Mevalonic Lactone:

[0015]

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(Wherein R is as defined above). Furthermore, when the resist composition of the present invention is applied to a quartz substrate to form a film having a thickness of 1 μm on the substrate, it preferably transmits at a wavelength (180 to 300 nm) of an exposure light source in the deep ultraviolet region. The rate is 30% or more. When the above-mentioned acid-sensitive polymer is in the form of a copolymer, it is also preferable that the monomer unit of the polymerization partner of the monomer unit having a protective group-containing carboxyl group has an additional protective group-containing carboxyl group. That is, the acid-sensitive copolymer has a monomer unit containing a second protecting group-containing carboxyl group in addition to the above-mentioned monomer unit containing a first protecting group-containing carboxyl group containing the lactone moiety as a protecting group. May be present and such combinations are also preferred. Here, the monomer unit containing the second protective group-containing carboxyl group preferably contains, in the side chain of the monomer unit, an additional protective group capable of being removed by the action of an acid from the photo-acid generator. And a carboxyl group represented by the following formula (II):

[0017]

[Chemical 6]

(In the above formula, R _I represents a linear or branched alkyl group having 1 to 4 carbon atoms,
May be substituted or unsubstituted, and Z
Represents a plurality of atoms necessary for completing the alicyclic hydrocarbon group together with the carbon atom to which R _I is attached) as a protecting group for the carboxyl group.

The second protecting group-containing carboxyl group may exist in various forms, but is preferably represented by the following formula (III).

[0020]

[Chemical 7]

(In the above formula, R _I and Z are respectively the same as defined above). The resist composition of the present invention is preferably selected from the group consisting of ethyl lactate, methyl amyl ketone, methyl-3-methoxypropionate, ethyl-3-ethoxypropionate, propylene glycol methyl ether acetate and mixtures thereof. It is provided in the form of a solution dissolved in another solvent. Further, this resist solution may further contain, as an auxiliary solvent, a solvent selected from the group consisting of butyl acetate, γ-butyrolactone, propylene glycol methyl ether and a mixture thereof, if necessary.

In another aspect, the present invention is a method for forming a resist pattern, which comprises the following steps: applying the resist composition of the present invention onto a substrate to be treated to form a resist film. Selectively exposing the resist composition with imaging radiation capable of inducing decomposition of the photoacid generator of the resist composition, and developing the exposed resist film with a basic aqueous solution. There is a method for forming a resist pattern.

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 heat treatment before and after the selective exposure step. That is, in the method of the present invention, the resist film is subjected to a pre-bake treatment before the exposure, and a post-bake treatment described above as PEB (post-exposure baking) after the exposure and before the development. To serve. These heat treatments can be advantageously carried out according to a conventional method.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The resist composition and the method for forming a resist pattern according to the present invention can be carried out in various preferable modes, as can be easily understood from the following detailed description. The present invention relates to a chemically amplified resist composition that can be developed with a basic aqueous solution for forming a positive resist pattern on a substrate to be processed. This resist composition, as described above,
(A) A film-forming polymer having a protective group-containing carboxyl group in the side chain of a monomer unit, which is itself insoluble in a basic aqueous solution, provided that the protective group for the carboxyl group is eliminated from the side chain. In this case, an acid-sensitive polymer capable of being soluble in a basic aqueous solution, and (b) a light capable of generating an acid capable of causing elimination of the protective group of the carboxyl group by absorbing and decomposing imaging radiation. An acid generator (PAG), wherein the acid-sensitive polymer has the formula (I)
The specific lactone moiety represented by is contained as a protecting group for the carboxyl group. The mechanism of chemical amplification in the resist composition of the present invention will now be described as follows: The PAG in the resist composition is exposed to imaging radiation after formation of the resist film, and the PAG in the resist composition emits the radiation. Absorbs and generates acid. Then, when the resist film after this exposure is heated, the acid previously generated acts catalytically, and the following reaction proceeds in the exposed portion of the film.

[0025]

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In the resist composition of the present invention, in the acid-sensitive polymer as the base resin, a functional group which can be easily removed by heating in the presence of an acid catalyst is introduced into the ester portion of the monomer unit. Therefore, the protonic acid can be regenerated by the elimination thereof, and thus high sensitivity can be achieved. In addition, since the carboxylic acid is generated after elimination of the functional group, the exposed portion of the resist film becomes soluble in a base,
Therefore, it can be developed with a basic aqueous solution. The obtained resist pattern is a positive pattern because the exposed portion is dissolved and removed. In the present invention,
Since the pattern formation is carried out by utilizing the change in polarity generated in the polymer, a pattern without swelling can be obtained.

The acid-sensitive polymer used as the base resin in the resist composition of the present invention has an acid catalyst on the ester portion of the first monomer unit, particularly when it is in the form of a copolymer. In addition to having a functional group that can be easily removed by heating in the presence of, the second monomer unit can also have a similar functional group. In such a case, since both functional groups in the copolymer can be eliminated by an acid-catalyzed reaction, the functional group of one of the monomer units is eliminated so that the copolymerization function of the monomer unit is changed. It is possible to achieve both higher sensitivity and higher resolution than the combination.

The acid-sensitive polymer used as the base resin in the resist composition according to the present invention is particularly limited as long as it satisfies the above-mentioned conditions, especially the conditions for the mechanism of chemical amplification. However, when taking into consideration obtaining dry etching resistance equivalent to that of a novolac resist, an acrylate-based polymer, a methacrylate-based polymer, a vinylphenol-based monomer unit, an N-substituted maleimide-based polymer, a styrene-based polymer Is recommended. In particular, the acrylate-based and methacrylate-based polymers are important in that when deep ultraviolet rays are used as an exposure light source, absorption of light having a wavelength in the deep ultraviolet region is small. In other words, when the exposure light source is deep ultraviolet light, generally, an aromatic ring that largely absorbs light in the deep ultraviolet region or a chromophore having a large molar absorption coefficient such as a conjugated double bond is not included. It is desirable to use a polymer having a structure.

When an exposure light source in the extremely short wavelength region such as an argon fluoride (ArF) excimer laser is used, it is necessary to have dry etching resistance and transparency at the wavelength (193 nm) of the exposure light source. A polymer as described above, which does not contain a strongly absorbing aromatic ring, but instead has a high dry etching resistance, for example, a plurality or polycyclic alicyclic ring represented by an adamantyl group or a norbornyl group. The use of polymers having ester groups containing formula hydrocarbon moieties, especially acrylate and methacrylate polymers, is recommended. Here, the alicyclic hydrocarbon moiety to be contained in the ester group includes various groups known in the field of chemically amplified resist.
Suitable alicyclic hydrocarbon groups are, for example, those having the following compounds as a skeleton.

(1) Adamantane and its derivative (2) Norbornane and its derivative (3) Perhydroanthracene and its derivative (4) Perhydronaphthalene and its derivative (5) Tricyclo [5.2.1.0 ^2,6] ] Decane and its derivative (6) Bicyclohexane and its derivative (7) Spiro [4,5] nonane and its derivative (8) Spiro [4,5] decane and its derivative These compounds are respectively as follows. Represented by a structural formula:

[0031]

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Further, the molecular weight (weight average molecular weight, Mw) of the above-mentioned (meth) acrylate polymer and other acid-sensitive polymers can be changed within a wide range.
Preferably, the molecular weight of such polymers is 2000-10.
The range is 00000, and the range of 3000 to 50,000 is more preferable. Acid-sensitive polymers that can be advantageously used in the practice of the present invention are more specifically not limited to those listed below,
The following polymers are included. In the formula, m is the number of monomer units (repeating units) necessary to obtain the above weight average molecular weight, and LAC is the formula (I).
And X represents an arbitrary substituent, for example, a hydrogen atom, a halogen atom, for example, chlorine, bromine, etc., a lower alkyl group, for example, a methyl group, etc., a cyano group, unless otherwise specified. Others. (1) (meth) acrylate-based polymer

[0033]

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(2) Vinylphenol polymer

[0035]

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(3) Fumaric acid type polymer

[0037]

[Chemical 12]

In the above formula, R'represents the above LAC or an alkoxy group such as methoxy group, isopropoxy group, t-butoxy group, etc., aryloxy group such as phenoxy group, benzyloxy group, etc. . (4) Vinyl benzoic acid polymer

[0039]

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(5) Norbornenecarboxylic acid type polymer

[0041]

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(6) Itaconic acid type polymer

[0043]

[Chemical 15]

In the above formula, R'is as defined above. (7) Maleic acid-based polymer

[0045]

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In the above formula, R'is the same as defined above. As described above, these polymers are combined with other suitable monomer units to form an arbitrary copolymer (two-component copolymer, three-component copolymer, etc.). May be. The acid-sensitive copolymer that can be used in the present invention will be described with reference to the above (meth) acrylate-based polymer as a main component, as shown in the following formulas (V) and (VI). is there. Incidentally, the (meth) acrylate-based three-component copolymer can also be constituted according to this.

[0047]

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[0048]

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In the above formula, R ¹ represents hydrogen or an arbitrary substituent such as halogen, an alkyl group and a methylol group, and Y represents an optional substituent such as an alkyl group such as t-. It represents an alicyclic group such as a butyl group, for example, adamantyl, norbornyl, cyclohexyl, tricyclo [5.2.1.0] decane, etc., B represents an arbitrary substituent such as a carboxyl group, and l and m Is the molar ratio of each monomer unit, l + m = 1, and X and LAC are each as defined above.

Further, clarification in connection with this, the inventors of the present invention have found the usefulness thereof to include (±) -mevalonic lactone (meth) acrylic acid ester as a constituent component ( (Meth) acrylate-based polymers are new and have never been taught in the prior art. These and other (meth) acrylate-based polymers, including those in the form of copolymers, can be prepared using polymerization methods commonly used in polymer chemistry. For example, the (meth) acrylate-based polymer of the present invention uses a predetermined monomer component as a free radical initiator of 2,2′-azobisisobutyronitrile (not described in detail in the present specification). It can be advantageously prepared by free-radical polymerization in the presence of (AIBN). Acid-sensitive polymers other than the (meth) acrylate-based polymer can also be advantageously prepared in the same manner as usual.

By the way, when the acid-sensitive polymer takes the form of a copolymer, the proportion of the monomer unit having the lactone moiety of the above formula (I) in the ester group in the copolymer is as follows.
Preferably, it is 20 to 70% by weight. If the content of this monomer unit is less than 20% by weight, satisfactory patterning becomes impossible, while if it exceeds 70% by weight, it becomes soluble in the basic aqueous solution.
The content of such monomer units is more preferably 3
It is 0 to 60% by weight.

Further, according to the further knowledge of the present inventors, in the resist composition of the present invention, when the acid-sensitive polymer contained as a base resin in the resist composition is in the form of a copolymer, it contains a protective group. It is also preferable that the monomer unit of the polymerization partner of the monomer unit having a carboxyl group has an additional protective group-containing carboxyl group as described above.
That is, the acid-sensitive copolymer has a monomer unit containing a second protecting group-containing carboxyl group in addition to the above-mentioned monomer unit containing a first protecting group-containing carboxyl group containing the lactone moiety as a protecting group. May be present and such combinations are preferred. Here, the monomer unit containing the second protective group-containing carboxyl group preferably contains, in the side chain of the monomer unit, an additional protective group capable of being removed by the action of an acid from the photo-acid generator. And a carboxyl group represented by the following formula (II):

[0053]

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(In the above formula, R _I represents a linear or branched alkyl group having 1 to 4 carbon atoms,
May be substituted or unsubstituted, and Z
Represents a plurality of atoms necessary for completing the alicyclic hydrocarbon group together with the carbon atom to which R _I is attached) as a protecting group for the carboxyl group. The second protective group-containing carboxyl group may exist in various forms, but is preferably represented by the following formula (III).

[0055]

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In the above equation, R _I and Z are respectively
It is the same as the above definition. More specifically, the acid-sensitive copolymer, in which each monomer unit has a protecting group-containing carboxyl group and which can be advantageously used in the practice of the present invention, is preferably represented by the following formula (VII): It is a copolymer represented.

[0057]

[Chemical 21]

In the above formula, R, R _I , R ¹ , X, m and l are respectively the same as defined above, and the substituents R ¹ and X bonded to the carbon atom of the main chain are the same or different. They may be different and are preferably a hydrogen atom or a lower alkyl group such as a methyl group. Acid-sensitive copolymers which can be used more advantageously in the practice of the present invention are therefore the methacrylic acid (±) -mevalonic lactone ester / 2-methylmethacrylate represented by the formula (VIII): It is a 2-adamantyl copolymer.

[0059]

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In the above formula, Me represents a methyl group, provided that this methyl group may be replaced by a hydrogen atom, and m and l are as defined above. Since such a copolymer and other similar copolymers contain an adamantyl group in the ester portion, high dry etching resistance (RIE resistance) can be obtained.
Here, if it is desired to obtain RIE resistance equivalent to that of a currently used general novolak resist, the second monomer unit in the copolymer, that is, 2-methylmethacrylate-2, is used.
-It is necessary to set the content of adamantyl to about 50 mol%. In addition, since this copolymer has a structure that does not contain an aromatic ring having strong absorption, it has an argon fluoride (A
It is very advantageous for transparency at very short wavelengths (193 nm) such as rF) excimer lasers.

The content of methacrylic acid (±) -mevalonic lactone ester, which is the first monomer unit in the above-mentioned copolymer, is generally preferably about 20 to 70% by weight, and further, Preferably about 30-60
% By weight. In addition, the content of the second monomer unit, 2-methyl-2-adamantyl methacrylate, in such a copolymer is generally preferably about 20 to 80% by weight, more preferably about 30 to 70% by weight. % By weight. When each monomer unit is contained in a smaller amount or a larger amount than the above-mentioned range, as described above, satisfactory patterning becomes impossible, and it is changed to be soluble in a basic aqueous solution. Occurs.

Further, the mechanism of chemical amplification in the copolymer containing the first and second monomer units as described above is basically the same as the mechanism of chemical amplification in the homopolymer described above, To this will be added a similar reaction in the second monomer unit. That is, it is well known that a polymer of acrylic acid or methacrylic acid has high transparency in the deep ultraviolet region, and
For example, a methacrylic acid (±) -mevalonic lactone ester / 2-methyl-2-adamantyl methacrylate copolymer represented by the above formula (VIII) has a structure in which two types of ester moieties contained are 190 each.
Since it does not contain a chromophore having a large molar absorption coefficient at ˜250 nm, if it is combined with a compound (PAG) capable of generating an acid when absorbing an appropriate amount of imaging radiation and decomposing, and desorbing the above ester part (PAG). A highly sensitive resist that can be advantageously used for exposure using deep ultraviolet rays.

When the PAG is exposed to the imaging radiation after forming the resist film, the PAG absorbs the radiation and generates an acid. Then, when the resist film after this exposure is heated, the acid previously generated acts catalytically and the following reactions proceed separately or simultaneously in the exposed portion of the film.

[0064]

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[0065]

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In the copolymer as described above, a functional group which can be easily eliminated by heating in the presence of an acid catalyst is introduced into the ester portion of the monomer unit, and therefore the elimination of the protonic acid causes regeneration. Therefore, high sensitivity can be achieved. Further, since the carboxylic acid is generated after the elimination of the functional group, the exposed portion of the resist film becomes soluble in the base, so that the resist film can be developed with the basic aqueous solution. The obtained resist pattern is a positive pattern because the exposed portion is dissolved and removed. In this case, a pattern without swelling can be obtained because the pattern is formed utilizing the change in polarity generated in the polymer.

The photoacid generator (PAG) used in combination with the acid-sensitive polymer as described above in the chemically amplified resist of the present invention is a photoacid generator generally used in resist chemistry. It may be an agent, that is, a substance that produces a protonic acid upon irradiation with radiation such as ultraviolet rays, far ultraviolet rays, vacuum ultraviolet rays, electron beams, X-rays, and laser light. Suitable photoacid generators in the practice of the present invention include, but are not limited to, those listed below. (1) Iodonium salt represented by the following formula:

[0068]

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(In the above formula, Ar is a substituted or non-substituted
Substituted aromatic groups such as phenyl, halogen, methyl
Group substituted with phenyl group, t-butyl group, aryl group, etc.
Groups, etc., or alicyclic groups, and X₁Is BF_Four, B
F₆, PF₆, AsF₆, SbF₆, CF_ThreeSO_Three, C
10 _Four(2) A sulfonium salt represented by the following formula:

[0070]

[Chemical formula 26]

[0071]

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[0072]

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[0073]

[Chemical 29]

[0074]

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[0075]

[Chemical 31]

(In the above formula, R ₁ , R ₂ , R ₃ and R
₄ may be the same or different and each represents hydrogen or an arbitrary substituent, for example, halogen, an alkyl group, an aryl group, etc., for example, R ₁ and R ₂
And R ₃ is a phenyl group or the like, R ₄ is a methyl group or the like, and Ar and X ₁ are the same as defined above.) (3) A sulfonate represented by the following formula:

[0077]

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(In the above formula, Ar and R ₄ are the same as defined above.) (4) Oxazole derivative represented by the following formula:

[0079]

[Chemical 33]

(In the above formula, X ₂ is halogen, for example, Cl, Br or I, provided that one of the —CX ₃ groups may be a substituted or unsubstituted aryl group or alkenyl group.) 5) Halide represented by the following formula:

[0081]

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(In the above formula, X ₂ is the same as the above definition) (6) s-triazine derivative represented by the following formula:

[0083]

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(In the above formula, X ₂ is halogen, for example Cl, Br or I, provided that one of the —CX ₃ groups may be a substituted or unsubstituted aryl group or alkenyl group) 7) disulfone derivative represented by the formula: in Ar-SO ₂ -SO ₂ -Ar (above formulas, Ar is as defined above) (8) imide represented by the formula compound:

[0085]

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(In the above formula, X ₁ is the same as the above definition) (9) Others (sulfonic acid esters represented by the following formula):

[0087]

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These photoacid generators can be used in various amounts in the resist composition of the present invention. According to the knowledge of the present inventors, the amount of the photo-acid generator used is preferably 0.1 to 5 based on the total amount of the polymer.
0% by weight. If the amount of photoacid generator exceeds 50% by weight, patterning can no longer be carried out as a result of excessive light absorption. The use amount of the photoacid generator is more preferably 1 to 15% by weight based on the total amount of the polymer.

Further, in connection with the above, the transmittance of the resist composition of the present invention comprising an acid-sensitive polymer and a photo-acid generator at the exposure wavelength (a resist film having a film thickness of 1 μm was formed on a quartz substrate. It is desirable to consider the structures of the polymer and the photo-acid generator and the amount of the photo-acid generator used so that the (time value) is 30% or more. In general, the resist composition of the present invention can be advantageously used in the form of a resist solution by dissolving the above-mentioned acid-sensitive polymer and photoacid generator in a suitable organic solvent. Organic solvents useful in the preparation of resist solutions include ethyl lactate, methyl amyl ketone, methyl-3.
-Methoxypropionate, ethyl-3-ethoxypropionate, propylene glycol methyl ether acetate and the like are recommended, but are not limited thereto. These solvents may be used alone or, if necessary, may be used by mixing two or more kinds of solvents. The amount of these solvents used is not particularly limited, but it is preferable to use an amount sufficient to obtain a viscosity suitable for coating such as spin coating and a desired resist film thickness.

In the resist solution of the present invention, if necessary, an auxiliary solvent may be used in addition to the above-mentioned solvent (particularly referred to as main solvent). The use of an auxiliary solvent is not necessary depending on the solubility of the solute, but when a solute with low solubility is used, it is usually preferable to add it in an amount of 1 to 30% by weight, more preferably 10 to 30% by weight, based on the main solvent. ~ 20% by weight
It is. Examples of useful co-solvents include, but are not limited to, those listed below, butyl acetate, γ-butyrolactone, propylene glycol methyl ether, and the like.

The present invention also provides a method for forming a resist pattern, particularly a positive resist pattern, on a substrate to be processed using the resist composition as described above. The formation of the positive resist pattern of the present invention can usually be carried out as follows. First, the resist composition of the present invention is applied onto a substrate to be processed to form a resist film. The substrate to be processed can be a substrate usually used in semiconductor devices and other devices,
Some examples are silicon substrates, glass substrates,
Nonmagnetic ceramic substrates and the like can be mentioned. Further, if necessary, additional layers such as a silicon oxide layer, a wiring metal layer, an interlayer insulating film, and a magnetic film may be present above these substrates. , Circuits, etc. may be built in. Furthermore, these substrates may be subjected to a hydrophobic treatment according to a conventional method in order to enhance the adhesion of the resist film thereto. Suitable hydrophobizing agents include, for example, 1,1,1,3
3,3-hexamethyldisilazane (HMDS) and the like can be mentioned.

As described above, the resist composition can be applied as a resist solution onto the substrate to be treated. The resist solution can be applied by a conventional technique such as spin coating, roll coating, or dip coating, but spin coating is particularly useful. Resist film thickness is about 0.1
A range of up to 200 μm is recommended, but 0.1 to 1.5 μm is recommended for KrF exposure. Note that the thickness of the formed resist film can be widely changed depending on factors such as the use of the resist film.

The resist film coated on the substrate is about 60-160 ° C. before it is selectively exposed to the imaging radiation.
Prebaking at a temperature of about 60 to 120 seconds. This pre-bake can be performed using a heating means commonly used in a resist process. Suitable heating means include, for example, a hot plate, an infrared heating oven, a microwave heating oven and the like.

Next, the prebaked resist film is selectively exposed to image forming radiation by a conventional exposure device. Suitable exposure apparatuses are commercially available ultraviolet (far ultraviolet / deep ultraviolet) exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, excimer steppers, and the like. As the exposure condition, an appropriate condition can be selected each time. Particularly, in the present invention, as described above, the excimer laser (K of wavelength 248 nm is
An rF laser and an ArF laser having a wavelength of 193 nm) can be advantageously used as an exposure light source. In addition, in the present specification, when the term "radiation" is used, light from these various light sources, that is, ultraviolet light, far ultraviolet light, deep ultraviolet light, electron beam (EB), X-ray, laser light, etc. Shall mean. As a result of this selective exposure, the dissolution inhibitor compound contained in the exposed region of the resist film absorbs the radiation and decomposes, solubilizing the exposed region in a basic aqueous solution.

Then, the resist film after exposure is subjected to post-exposure baking (PEB) to cause an acid-catalyzed elimination reaction of the protective group. This post-exposure bake can be performed in the same manner as the previous pre-bake. For example, the baking temperature is about 60-150 ° C, preferably about 100-15.
0 ° C. After completion of the post-exposure bake, the exposed resist film is developed with a basic aqueous solution as a developing solution. For this development, spin developers, dip developers,
A conventional developing device such as a spray developer can be used. Here, a basic aqueous solution that can be advantageously used as a developer is an aqueous solution of a hydroxide of a metal belonging to Group I or II of the periodic table represented by potassium hydroxide or the like, or a tetraalkylammonium hydroxide. And an aqueous solution of an organic base containing no metal ion. The basic aqueous solution is more preferably tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH).
AH) and the like. Further, such a basic aqueous solution may contain additives such as a surfactant for improving the developing effect. As a result of the development, the exposed region of the resist film is dissolved and removed, and only the unexposed region remains on the substrate as a resist pattern.

[0096]

EXAMPLES Next, the present invention will be described with reference to some examples regarding the synthesis of an acid-sensitive polymer, the preparation of a resist composition and the formation of a resist pattern. In addition,
It is to be understood that the following examples are merely examples and are not intended to limit the scope of the invention. Example 1 Synthesis of Methacrylic Acid (±) -Mevalonic Lactone Ester In a well-dried 100 ml eggplant-shaped flask containing Teflon ^™ coated star rubber, 30 ml of dry methylene chloride, 6 g (46.1 mmol) (±)
-Mevalonic lactone and 4.82 g (46.1 mmol) methacrylic acid chloride were added and stirred at 0 ° C under a dry nitrogen atmosphere. 5.1 g (5
0.4 mmol) triethylamine and 10 mg N,
N-Dimethylaminopyridine was added, and the mixture was stirred at 0 ° C for 1 hr. After confirming the disappearance of the starting materials by thin layer chromatography, the reaction solution was transferred to a 300 ml separatory funnel, washed with 100 ml of water, and the aqueous phase was extracted three times with methylene chloride. The organic layers were collected, washed with saturated brine, and dried over anhydrous sodium sulfate. The dried organic layer was filtered with a filter paper, and the solvent of the filtrate was distilled off under reduced pressure. A brown oil was obtained. When the obtained oily substance was purified by silica gel chromatography, colorless transparent oily methacrylic acid (±) -mevalonic lactone ester was obtained. Yield = 5.94 g (65%).

The results of the analysis of the obtained product are as follows. In the parentheses, s is a singlet, d is a doublet, and m is a multiplet. ¹ H NMR (CDCL ₃ , δ, J in Hz): 6.0
5, 5.58 (1H each), 4.44-4.35
(2H, m), 3.19 (1H, d, J = 17.5),
2.62 (1H, m), 2.60 (1H, d, J = 1
7.5), 2.03 (1H, m), 1.91, 1.66
(3H and s, respectively).

The results of IR analysis are as follows. In addition, in lowercase letters in brackets, s is s
strong (strong), m is medium (medium), and w
Means weak. IR (KBr, neat, cm ^-1 ): 2980 (w),
1743 (s), 1714 (s), 1271 (m), 1
173 (s), 1161 (s), 1074 (m). Example 2 Methacrylic acid (±) -mevalonic lactone ester /
Synthesis of Cyclohexyl Methacrylate Copolymer 5.94 In a well-dried 100 ml eggplant-shaped flask containing Teflon ^™ coated star rubber.
g (30 mmol) of methacrylic acid (±) -mevalonic lactone ester prepared in Example 1 above, 5.04 g
(30 mmol) cyclohexyl methacrylate, 20
ml dioxane and 1.48 g (9 mmol) azobisisobutyronitrile (AIBN) were added and stirred at 80 ° C. for 8 hours under nitrogen atmosphere. The reaction solution was diluted with tetrahydrofuran (THF) and then added dropwise to 1 liter of a water-ethanol mixed solution containing a small amount of hydroquinone. The precipitate formed is filtered off with a glass filter and washed with 0.1
It was dried at mmHg and 45 ° C. for 16 hours. The obtained white powder was dissolved again in THF, and the same precipitation-drying operation as described above was repeated twice. The desired white copolymer was obtained. Yield = 7.69 g (70%).

From ¹ H NMR, it was found that the copolymerization ratio of the obtained copolymer was 1: 1. The transmittance of this copolymer at a wavelength of 248 nm is 95% (film thickness: 1 μm,
It was on a quartz substrate) and was shown to have excellent transparency. The results of other analyzes are as follows. Weight average molecular weight: 11860 (standard polystyrene conversion).

Dispersity: 1.45. IR (KRS-5, cm ^-1 ): 2937, 1726, ¹
259, 1149, 1112. Example 3 Methacrylic acid (±) -mevalonic lactone ester /
Synthesis of p-acetoxystyrene copolymer 5.94 in a well-dried 100 ml eggplant-shaped flask containing Teflon ^™ coated star rubber.
g (30 mmol) of methacrylic acid (±) -mevalonic lactone ester prepared in Example 1 above, 4.87 g
(30 mmol) p-acetoxystyrene, 20 ml dioxane and 1.48 g (9 mmol) azobisisobutyronitrile (AIBN) were added and stirred under a nitrogen atmosphere at 80 ° C. for 8 hours. The reaction solution was diluted with tetrahydrofuran (THF) and then added dropwise to 1 liter of a water-ethanol mixed solution containing a small amount of hydroquinone. The resulting precipitate was filtered off with a glass filter and dried at 0.1 mmHg and 45 ° C. for 16 hours. The obtained white powder was dissolved again in THF, and the same precipitation-drying operation as described above was repeated twice. The desired white copolymer was obtained. Yield = 7.78 g (72%).

¹ H NMR revealed that the copolymerization ratio of the obtained copolymer was 1: 1. The transmittance of this copolymer at a wavelength of 248 nm is 75% (film thickness 1 μm,
It was on a quartz substrate) and was shown to have excellent transparency. The results of other analyzes are as follows. Weight average molecular weight: 7620 (standard polystyrene conversion).

Dispersity: 1.41. IR (KRS-5, cm ^-1 ): 3193, 1751, ¹
726, 1218, 1201. Example 4 Formation of Resist Pattern The copolymer synthesized in Example 2 was dissolved in propylene glycol methyl ether acetate to prepare a 17 wt% solution. The copolymer solution also contained 8% by weight of γ-butyrolactone as an auxiliary solvent. To the obtained solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 5% by weight with respect to the copolymer was added and sufficiently dissolved. 0.2 μ of the obtained resist solution
After filtration with a Teflon ^TM membrane filter m, HM
A silicon substrate subjected to DS treatment was spin-coated at 2000 rpm and prebaked at 110 ° C. for 60 seconds. A resist film having a thickness of 0.7 μm was obtained. Use this resist film as a KrF excimer laser stepper (NA = 0.45)
After exposure to water, the film was developed with a 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution and rinsed with deionized water for 60 seconds. With an exposure dose of 40 mJ / cm ² ,
A 0.3 μm line and space (L / S) pattern could be resolved.

Then, the silicon substrate coated with the resist as described above is housed in a parallel plate type RIE apparatus, and P
μ = 200 W, pressure = 0.02 Torr, argon (Ar)
When Ar sputter etching was carried out under the condition of gas = 50 sccm, it was confirmed by film thickness measurement that the same dry etching resistance as that of Nagase positive resist NPR-820 (manufactured by Nagase & Co., Ltd.) which is a novolak resist was exhibited. Example 5 Formation of Resist Pattern The copolymer synthesized in Example 3 was dissolved in ethyl lactate to prepare a 18 wt% solution. To the obtained ethyl lactate solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 2% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 110 ° C. for 60 seconds. Thickness 0.7
A μm resist film was obtained. This resist film is
After exposure with an rF excimer laser stepper (NA = 0.45), the film was developed with a 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution and rinsed with deionized water for 60 seconds. With an exposure dose of 35 mJ / cm ² , 0.3
The μm L / S pattern could be resolved.

Then, a resist is applied as described above.
The silicon substrate was subjected to Ar in the same manner as in Example 4 above.
After sputter etching, Nagase Positive Regis
Dry etching resistance equivalent to NPR-820 (described above)
It was confirmed that the product exhibits sex. Example 6 Formation of resist pattern Dissolve the copolymer synthesized in Example 2 above in ethyl lactate
To give an 18 wt% solution. Obtained ethyl lactate solution
And diphenyliodine in an amount of 2% by weight, based on the copolymer.
Add enough trinium trifluoromethanesulfonate
Dissolved. The resist solution obtained was applied with a 0.2 μm Tef
Ron^TMAfter filtering with a membrane filter, HMDS treatment
Spin coating on a coated silicon substrate at 2000 rpm
And prebaked at 110 ° C. for 60 seconds. Film thickness 0.7μ
m resist film was obtained. This resist film is Ar
F excimer laser exposure device (Nikon, NA = 0.5
After exposure with 5), 2.38% tetramethylammonium
Develop with um hydroxide (TMAH) aqueous solution and remove
Rinse with ionized water for 60 seconds. 10 mJ / cm²Exposure of
Then, a 0.2 μm L / S pattern could be resolved.

Then, a resist is applied as described above.
The silicon substrate was subjected to Ar in the same manner as in Example 4 above.
After sputter etching, Nagase Positive Regis
Dry etching resistance equivalent to NPR-820 (described above)
It was confirmed that the product exhibits sex. Example 7 Methacrylic acid (±) -mevalonic lactone ester /
Synthesis of norbornyl methacrylate copolymer Teflon^TMTens with coated star rubber
In a 200 ml eggplant-shaped flask that has been dried for 10 minutes, 10 g
(50.5 mmol) of methacrylic acid prepared in Example 1 above
(±) -Mevalonic lactone ester, 9.90 g
(50.5 mmol) norbornyl methacrylate, 3
3.7 ml dioxane and 2.49 g (15.2 millimolar)
Azobisisobutyronitrile (AIBN)
Then, the mixture was stirred at 80 ° C. for 8 hours under a nitrogen atmosphere. Reaction solution
Was diluted with tetrahydrofuran (THF),
3 liters of water-ethanol mixed solution containing hydroquinone
Dropped into the liquid. The generated precipitate is filtered with a glass filter
And dried at 0.1 mmHg and 45 ° C. for 16 hours. Get
The white powder obtained was dissolved in THF again and
The same precipitation-drying operation as above was repeated twice. Target white
A color copolymer was obtained. Yield = 14.33 g (72
%).

From ¹ H NMR, it was found that the copolymerization ratio of the obtained copolymer was 1: 1. The transmittance of this copolymer at a wavelength of 248 nm is 95% (film thickness: 1 μm,
It was on a quartz substrate) and was shown to have excellent transparency. The results of other analyzes are as follows. Weight average molecular weight: 13600 (standard polystyrene conversion).

Dispersity: 1.52. IR (KRS-5, cm ^-1 ): 2960, 1727, ¹
259, 1148. Example 8 Methacrylic acid (±) -mevalonic lactone ester /
Synthesis of adamantyl methacrylate copolymer 10 g in a well-dried 200 ml eggplant-shaped flask containing Teflon ^™ coated star rubber.
(50.5 mmol) of methacrylic acid (±) -mevalonic lactone ester prepared in Example 1 above, 11.13 g
(50.5 mmol) adamantyl methacrylate, 3
3.7 ml dioxane and 2.49 g (15.2 mmol) azobisisobutyronitrile (AIBN) were added and stirred at 80 ° C. for 8 hours under nitrogen atmosphere. The reaction solution was diluted with tetrahydrofuran (THF) and then added dropwise to 3 liters of a water-ethanol mixed solution containing a small amount of hydroquinone. The resulting precipitate was filtered off with a glass filter and dried at 0.1 mmHg and 45 ° C. for 16 hours. The obtained white powder was dissolved again in THF, and the same precipitation-drying operation as described above was repeated twice. The desired white copolymer was obtained. Yield = 15.85 g (75
%).

From ¹ H NMR, it was found that the copolymerization ratio of the obtained copolymer was 1: 1. The transmittance of this copolymer at a wavelength of 248 nm is 95% (film thickness: 1 μm,
It was on a quartz substrate) and was shown to have excellent transparency. The results of other analyzes are as follows. Weight average molecular weight: 14100 (standard polystyrene conversion).

Dispersity: 1.41. IR (KRS-5, cm ^-1 ): 2912, 1722, ¹
259, 1093. Example 9 Formation of Resist Pattern The copolymer synthesized in Example 7 was dissolved in ethyl lactate to prepare a 17 wt% solution. To the obtained ethyl lactate solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 5% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 120 ° C. for 60 seconds. Thickness 0.7
A μm resist film was obtained. This resist film is
After exposure with an rF excimer laser stepper (NA = 0.45), the film was developed with a 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution and rinsed with deionized water for 60 seconds. With an exposure dose of 38 mJ / cm ² , 0.3
The μm L / S pattern could be resolved. Example 10 Formation of Resist Pattern The copolymer synthesized in Example 8 was dissolved in ethyl lactate to prepare a 17 wt% solution. To the obtained ethyl lactate solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 5% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 120 ° C. for 60 seconds. Thickness 0.7
A μm resist film was obtained. This resist film is
After exposure with an rF excimer laser stepper (NA = 0.45), baking was performed at 100 ° C. for 60 seconds, and 2.38% tetramethylammonium hydroxide (TMAH)
Develop with aqueous solution and rinse with deionized water for 60 seconds. 3
A 0.3 μm L / S pattern could be resolved at an exposure dose of 0 mJ / cm ² . Example 11 Formation of Resist Pattern The copolymer synthesized in Example 7 was dissolved in ethyl lactate to prepare a 17 wt% solution. To the obtained ethyl lactate solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 2% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 120 ° C. for 60 seconds. Thickness 0.7
A μm resist film was obtained. This resist film is
After exposure with an rF excimer laser stepper (NA = 0.45), baking was performed at 100 ° C. for 60 seconds, and 2.38% tetramethylammonium hydroxide (TMAH)
Develop with aqueous solution and rinse with deionized water for 60 seconds. Two
A 0.3 μm L / S pattern could be resolved at an exposure dose of 0 mJ / cm ² . Example 12 Formation of Resist Pattern The copolymer synthesized in Example 8 was dissolved in ethyl lactate to prepare a 17 wt% solution. To the obtained ethyl lactate solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 2% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 120 ° C. for 60 seconds. Thickness 0.7
A μm resist film was obtained. This resist film is
After exposure with an rF excimer laser stepper (NA = 0.45), baking was performed at 100 ° C. for 60 seconds, and 2.38% tetramethylammonium hydroxide (TMAH)
Develop with aqueous solution and rinse with deionized water for 60 seconds. Two
A 0.3 μm L / S pattern could be resolved with an exposure dose of ³ mJ / cm ² . Example 13 Methacrylic acid (±) -mevalonic lactone ester /
Synthesis of 2-methyl-2-adamantyl methacrylate copolymer 4.96 in a well-dried 100 ml eggplant-shaped flask containing Teflon ^™ coated star rubber.
g (25 mmol) of methacrylic acid (±) -mevalonic lactone ester prepared in Example 1 above, 5.87 g
(25 mmol) 2-methyl-2-adamantyl methacrylate, 16.7 ml dioxane and 1.23 g (9
Mmol) of azobisisobutyronitrile (AIBN)
Was added, and the mixture was stirred at 80 ° C. for 8 hours under a nitrogen atmosphere. After diluting the reaction solution with tetrahydrofuran (THF),
It was added dropwise to 1 liter of methanol containing a small amount of hydroquinone. The generated precipitate is filtered off with a glass filter,
Dried at 0.1 mm Hg and 45 ° C. for 16 hours. The obtained white powder was dissolved again in THF, and the same precipitation-drying operation as described above was repeated twice. The target white copolymer powder was obtained. Yield = 7.44 g (68.7)
%).

From ¹ H NMR, the copolymerization ratio of the obtained copolymer was lactone: adamantyl = 46.5: 53.5.
Turned out to be. This copolymer had a transmittance of 96% at a wavelength of 248 nm and 64% at a wavelength of 193 nm (film thickness: 1 μm, on a quartz substrate), showing that it has excellent transparency. The results of other analyzes are as follows.

Weight average molecular weight: 13900 (converted to standard polystyrene). Dispersion degree: 1.78. IR (KRS-5, cm ^-1 ): 2914, 1724, ¹
259, 1147, 1103. Example 14 Formation of resist pattern 19% by weight of the copolymer prepared in Example 13 was dissolved in propylene glycol methyl ether acetate.
It was a solution. The copolymer solution also contained 8% by weight of γ-butyrolactone as an auxiliary solvent. To the obtained solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 5% by weight with respect to the copolymer was added and sufficiently dissolved. The resulting resist solution is 0.2
After filtration Teflon ^TM membrane filter [mu] m, H
A MDS-treated silicon substrate was spin-coated at 2000 rpm and prebaked at 120 ° C. for 60 seconds. A resist film having a thickness of 0.7 μm was obtained. This resist film was coated with a KrF excimer laser stepper (NA = 0.4
After exposure in 5), bake at 100 ° C. for 60 seconds, 2.
Developed with a 38% aqueous solution of tetramethylammonium hydroxide (TMAH) and rinsed with deionized water for 60 seconds. A 0.25 μm line-and-space (L / S) pattern could be resolved at an exposure dose of 8.3 mJ / cm ² .

Next, as described above, the resist (MLMA
-MAdMA) coated silicon substrate is housed in a parallel plate type RIE device, Pμ = 200 W, pressure = 0.02 Torr, C
Etching was performed for 5 minutes under the condition of F ₄ gas = 100 sccm. Etching rate and rate ratio (NP
For R-820), the test results as shown in the following table were obtained.

For comparison, the same etching and test were performed using commercially available novolac resist Nagase positive resist NPR-820 (manufactured by Nagase & Co., Ltd.) and PMMA (polymethylmethacrylate). Test resist etching rate (Å / min) rate ratio NPR-820 523 1.00 PMMA 790 1.51 MLMA-MAdMA 610 1.17 From the results shown in the above table, the resist (ML
It has been confirmed that the etching resistance of MA-MAdMA) is equivalent to that of Nagase positive resist NPR-820 which is a novolac resist, and is far superior to PMMA (polymethylmethacrylate). Example 15 Formation of Resist Pattern The copolymer synthesized in Example 13 was dissolved in ethyl lactate to prepare a 18 wt% solution. To the obtained ethyl lactate solution, triphenylsulfonium trifluoromethanesulfonate in an amount of 5% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 120 ° C. for 60 seconds. Thickness 0.7
A μm resist film was obtained. This resist film is
After exposure with an rF excimer laser stepper (NA = 0.45), baking was performed at 100 ° C. for 60 seconds, and 2.38% tetramethylammonium hydroxide (TMAH)
Develop with aqueous solution and rinse with deionized water for 60 seconds.
A 0.25 μm L / S pattern could be resolved at an exposure dose of 7.4 mJ / cm ² .

Then, the silicon substrate coated with the resist as described above was etched in the same manner as in Example 14 to find that the Nagase positive resist NPR-
It was confirmed that the etching resistance was equivalent to 820 (supra) and markedly superior to PMMA. Example 16 Formation of Resist Pattern The copolymer synthesized in Example 13 was dissolved in ethyl lactate to prepare a 18 wt% solution. To the obtained ethyl lactate solution, diphenyliodonium trifluoromethanesulfonate in an amount of 2% by weight based on the copolymer was added and sufficiently dissolved. The resulting resist solution was filtered through a 0.2 μm Teflon ^™ membrane filter, spin-coated at 2000 rpm on a HMDS-treated silicon substrate, and prebaked at 120 ° C. for 60 seconds. Film thickness 0.7μ
m of the resist film was obtained. This resist film is
F excimer laser exposure device (Nikon, NA = 0.5
After exposure in 5), bake at 100 ° C. for 60 seconds, 2.
Developed with a 38% aqueous solution of tetramethylammonium hydroxide (TMAH) and rinsed with deionized water for 60 seconds. 0.2 μm L / S at an exposure dose of 6 mJ / cm ²
The pattern was resolved.

Then, the silicon substrate coated with the resist as described above was etched in the same manner as in Example 14 to find that the Nagase positive resist NPR-
It was confirmed that the etching resistance was equivalent to 820 (supra) and markedly superior to PMMA.

[0116]

When the resist composition according to the present invention is used, it is possible to form a fine positive resist pattern without swelling with practical sensitivity. In addition, the acid-sensitive polymer of the resist composition is in the form of a copolymer, the monomer skeleton of the first monomer unit is selected, and as a partner of the copolymerization, a plurality of or polycyclic oils By using a monomer unit containing a cyclic hydrocarbon group, it is possible to provide a novel high-sensitivity resist that can be applied to an exposure light source with an extremely short wavelength such as ArF excimer laser.

Furthermore, in the acid-sensitive polymer in the form of a copolymer, in addition to the inclusion of the first protecting group (ester group) -containing carboxyl group in the side chain of the first monomer unit, When the side chain of the monomer unit also contains a second protecting group (ester group) -containing carboxyl group, both the first and second ester groups protecting the carboxyl group are removed by an acid-catalyzed reaction. Since they can be separated, higher sensitivity and higher resolution can be easily obtained than in the case of the conventional resist composition. Also in this copolymer, since the second monomer unit of the copolymer has an adamantyl group which is a polycyclic alicyclic hydrocarbon group, the RIE resistance is high and the copolymer itself has a deep ultraviolet region. Since it does not contain a chromophore having a large absorption coefficient, it is possible to provide a novel high-sensitivity resist that can be applied to an exposure light source with an extremely short wavelength such as ArF excimer laser.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiji Watanabe 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Takahisa Namiki 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 72) Inventor Miwa Igarashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Yoko Kuramitsu 1015, Uedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Fujitsu Limited (72) Inventor Akiko Kodachi, 1015 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Within Fujitsu Limited

Claims (10)

[Claims] 1. A film-forming polymer having a protecting group-containing carboxyl group in the side chain of a monomer unit, which is itself insoluble in a basic aqueous solution, provided that the protecting group of the carboxyl group is removed from the side chain. An acid-sensitive polymer that can be soluble in a basic aqueous solution when released, and a photoacid that can generate an acid that can cause elimination of the protective group of the carboxyl group when absorbed by decomposing by absorbing imaging radiation. A lactone moiety represented by the following formula (I), wherein the acid-sensitive polymer comprises: (In the above formula, R represents a linear or branched alkyl group having 1 to 4 carbon atoms, which may be substituted or unsubstituted, and n is an integer of 1 to 4. ) As a protecting group for the carboxyl group, a resist composition developable with a basic aqueous solution. 2. The resist composition according to claim 1, wherein the lactone moiety is derived from (±) -mevalonic lactone. 3. The monomer unit of a polymerization partner in the acid-sensitive polymer is a (meth) acrylate-based monomer unit, a vinylphenol-based monomer unit, an N-substituted maleimide-based monomer unit, a styrene-based monomer unit, and a plurality or a plurality thereof. The resist composition according to claim 1 or 2, wherein the resist composition is a member selected from the group consisting of monomer units having an ester group containing a cyclic alicyclic hydrocarbon moiety. 4. The resist composition according to claim 3, wherein the alicyclic hydrocarbon portion of the monomer unit is an adamantyl group and / or a norbornyl group. 5. A quartz substrate having a film thickness of 1 μm on the substrate.
The resist according to any one of claims 1 to 4, which has a transmittance of 30% or more at a wavelength (180 to 300 nm) of an exposure light source in the deep ultraviolet region when a film of m is formed. Composition. 6. A monomer unit as a polymerization partner in the acid-sensitive polymer has an additional side chain of the monomer unit,
A moiety having a carboxyl group containing a protecting group that can be eliminated by the action of an acid from the photoacid generator and represented by the following formula (II): (In the above formula, R _I represents a linear or branched alkyl group having 1 to 4 carbon atoms, which may be substituted or unsubstituted, and Z is a group to which R _I is bonded. 3. A resist composition according to claim 1 or 2, which contains, together with carbon atoms, a plurality of atoms necessary for completing an alicyclic hydrocarbon group, as a protective group for the carboxyl group. . 7. The additional protective group-containing carboxyl group is represented by the following formula (III):
The resist composition according to claim 6. Embedded image (In the above formula, R _I and Z are respectively the same as defined above). 8. A solution dissolved in a solvent selected from the group consisting of ethyl lactate, methyl amyl ketone, methyl-3-methoxypropionate, ethyl-3-ethoxypropionate, propylene glycol methyl ether acetate and mixtures thereof. The resist composition according to claim 1, which is in the form of 9. The resist composition according to claim 8, further comprising a solvent selected from the group consisting of butyl acetate, γ-butyrolactone, propylene glycol methyl ether and a mixture thereof as an auxiliary solvent. 10. The following steps: The resist composition according to any one of claims 1 to 9 is applied onto a substrate to be treated, and the formed resist film is treated with a photoacid generator of the resist composition. Selectively exposed to imaging radiation that can induce decomposition,
And developing the resist film after exposure with a basic aqueous solution, which is a method for forming a resist pattern.