JP2002229210A - Positive type resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist material having satisfactory resolving power and heat resistance even in ordinary pattern formation, capable of making pattern size smaller only by a proper flow baking temperature and having a proper flow speed, easily controllable the flow volume and rectangular profile when a semiconductor device is produced. SOLUTION: The positive type resist composition contains (a) an acid decomposable resin having solubility in an alkali developing solution increased by the action of an acid and (b) a photo-acid generating agent and the resin (a) comprises a resin A and a resin B satisfying the following characteristics; (the glass transition temperature of the resin A)>(the glass transition temperature of the resin B) before acid decomposition and (the glass transition temperature of the resin A)<(the glass transition temperature of the resin B) after acid decomposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified positive resist composition for semiconductor production, and more particularly to a chemically amplified positive resist for thermal flow, and more particularly to a resist for forming a contact hole and a method of forming a pattern thereof. is there.

[0002]

2. Description of the Related Art Heretofore, a reduced projection exposure method using light (g-line, i-line, KrF excimer laser light) has been used. In general, the resolution R of a lens is expressed by the following equation according to Rayleigh's theoretical equation. R = k [λ / (NA)] Here, λ is the exposure wavelength, and NA is the numerical aperture of the lens (Nume).
rical Aparture), assuming that the angle of opening incident on the wafer is θ, NA = sin θ. k indicates a different value depending on the resist, and is often used as a characteristic parameter indicating the performance of the resist. Experience with i-line resist shows that even if the resist is improved, it will only be reduced to about 0.5. To increase the resolving power, as is apparent from the above equation, is to decrease R, and for that purpose, NA is increased or λ is decreased.
It is necessary to reduce k. However, N.
A. also increased to a value approaching 0.7, and k reached the limit of 0.5. From the viewpoint of further shortening the wavelength, K
From 248 nm of rF excimer laser light to 193 nm of ArF excimer laser light and 157 nm of F2 excimer laser light have been studied. However, the development of resist materials and equipment that can be used in actual semiconductor manufacturing has been delayed. Therefore, a resist material and a pattern forming method capable of forming a finer pattern have been desired.

As a technique corresponding to the above method, Japanese Patent Laid-Open No.
UV (U) in a vacuum disclosed in US Pat.
Although the wafer is heated (flow-baked) while irradiating V), the shape of the resist is changed (flow), and the method of adjusting the contact hole diameter of a semiconductor device capable of reducing the size of the resist pattern is promising. However, development of a resist material suitable for it has been insufficient. In addition, since the process of flow baking a wafer while irradiating UV in a vacuum is complicated, a resist material that can obtain the same effect only by flow baking in air has been desired.
However, when a flow bake process is applied to a resist material known so far, problems such as a high flow rate and difficulty in controlling the hole size and a problem such as insufficient flow even at a practical flow temperature (150 ° C. or lower) are encountered. was there. Japanese Patent Application Laid-Open No. 2000-137329 discloses a mixture of a polymer having a malonic ester group in a polymer skeleton and a polymer which is thermally decomposed below the glass transition point of the polymer and increases intermolecular interaction. However, the shape after the flow is not rectangular, and heat resistance is a problem.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a resist composition exhibiting sufficient resolution and high heat resistance even in a normal pattern forming method, a resist material suitable for reducing a pattern size only by flow baking, and a resist material therefor. It is an object to provide a pattern forming method. ADVANTAGE OF THE INVENTION According to this invention, it shows sufficient resolving power and heat resistance even in normal pattern formation, and it is possible to reduce the pattern size only at an appropriate flow bake temperature, and the flow rate is appropriate and the flow amount is controlled. A resist material having a rectangular profile that is easy to use is provided.

[0005]

Means for Solving the Problems As a result of intensive studies on the constituent materials of the positive type chemically amplified resist composition, the present inventors have achieved the object of the present invention by using a material having the following structure. And found the present invention.
That is, the above object is achieved by the following constitutions.

(1) (a) An acid-decomposable resin whose solubility in an alkaline developer is increased by the action of an acid and (b) a photoacid generator, wherein the resin (a) is used before and after acid decomposition. A positive resist composition comprising a resin A and a resin B satisfying the following characteristics with respect to the glass transition point: Before acid decomposition: glass transition point of resin A> glass transition point of resin B After acid decomposition: glass transition point of resin A <glass transition point of resin B

(2) A positive resist composition for thermal flow having the constitution of the above (1). (3) After forming a photoresist film on the semiconductor substrate using the positive resist composition of (1) above,
A pattern of a desired size is formed by sequentially performing pattern exposure, heat treatment, and development processing with radiation of the following wavelengths to form a slightly larger pattern than desired, heating this semiconductor substrate to 120 to 160 ° C., and thermally deforming the resist. Forming a pattern.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each component used in the present invention will be described in detail. [1] Acid-Decomposable Resin A resin whose solubility in an alkali developer is increased by the action of an acid is obtained by protecting an alkali-soluble group of the resin with an acid-decomposable group. As the alkali-soluble group, a phenolic hydroxyl group and a carboxylic acid group are preferable. As the protecting group for the alkali-soluble group, an acetal group, a ketal group, an acetal ester group, a t-butyl ester group, a t-butoxycarbonyl group, and the like are preferable, and an alicyclic tertiary ester group is also preferable. Among these, an acetal group and a t-butyl ester group are more preferable, and an acetal group is particularly preferable from the viewpoints of sensitivity, sensitivity variation with respect to a storage time after exposure, and stability of dimensional variation (PED). When the exposure light source is ArF, a t-butyl ester group or an acetal ester of a carboxyl group is preferred because the absorption of the phenol skeleton is high.

Particularly, as a trunk polymer suitable for introducing an acid-decomposable group suitable for KrF excimer laser and electron beam exposure, hydroxystyrenes are preferable, and the hydroxystyrenes and an acid such as t-butyl acrylate or t-butyl methacrylate are preferably used. A copolymer with a decomposable (meth) acrylate can also be used. Further, a non-acid-decomposable group can be introduced for the purpose of adjusting the alkali solubility of the trunk polymer. As a method of introduction, styrenes,
A method by copolymerization with (meth) acrylic esters and (meth) acrylic amides or a method of protecting the hydroxyl group of hydroxystyrene with a non-acid-decomposable substituent is preferable. As the non-acid-decomposable substituent, an acetyl group, a mesyl group, a toluenesulfonyl group, an isopropoxy group and the like are preferable, but not limited thereto. It is also sensitive that other acid-decomposable groups exhibiting different acid-decomposability, such as t-butoxy group, t-butoxycarbonyloxy group, tetrahydropyranyloxy group, tetrahydrofuranyloxy group, etc., coexist in the same main chain. It is preferable because the profile can be adjusted.

The general formula (E) of an acid-decomposable resin suitable for KrF excimer laser exposure and electron beam irradiation is shown below.

[0011]

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R ₃ ′ independently represents a hydrogen atom or a methyl group, and each of a plurality of R ₃ ′ s may be the same or different. R ₄ is a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms, which may have a substituent, or an aromatic group having 6 to 18 carbon atoms, which may have a substituent. Or an aralkyl group having 7 to 18 carbon atoms which may have a substituent.

Examples of the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group and a t-butyl group.
Butyl, pentyl, hexyl, heptyl, 2-
Examples include an ethylhexyl group, an octyl group, a cyclopropyl group, a cyclopentyl group, and a 1-adamantylethyl group. The alkyl group as R ₄ may further have a substituent. Examples of such a substituent include a hydroxyl group, fluorine, chlorine, bromine, a halogen atom such as iodine, an amino group, a nitro group, a cyano group, a carbonyl group, an ester group,
Examples include an alkoxy group, a cycloalkyl group optionally containing a hetero atom, an aryloxy group, and a substituent having a sulfonyl group. Here, the carbonyl group is preferably an alkyl-substituted carbonyl group (a carbonyl group bonded to an alkyl group) or an aromatic-substituted carbonyl group (a carbonyl group bonded to an aromatic group), and the ester group is an alkyl-substituted ester group (alkyl group). An ester group bonded to a group) and an aromatic substituted ester group (an ester group bonded to an aromatic group) are preferred. As the alkoxy group, a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group and the like are preferable. Examples of the cycloalkyl group include a cyclohexyl group, an adamantyl group, a cyclopentyl group, and a cyclopropyl group.
Oxolanyl groups and the like. Examples of the aryloxy group include a phenoxy group and the like, and the aryl group may have a substituent. Examples of the substituent having a sulfonyl group include an alkylsulfonyl group such as a methylsulfonyl group and an ethylsulfonyl group, and an arylsulfonyl group such as a phenylsulfonyl group.

Examples of the aromatic group represented by R ₄ include groups derived from a benzene ring, a naphthalene ring, an anthracene ring and a phenanthrene ring. On the ring of these aromatic groups,
The substituents described as the substituents that the alkyl group as R ₄ may have may be present as the substituent. Examples of the aralkyl group for R ₄ include a benzyl group, a phenethyl group, a benzhydryl group, and a naphthylmethyl group. These aralkyl groups can have, as substituents, those described as the substituents that the alkyl group as R ₄ may have.

R ₅ is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms (eg, methyl, ethyl, propyl, butyl, sec-butyl, t-butyl, etc.), A chain or branched alkoxy group having 1 to 4 carbon atoms (for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, t-butoxy group, etc.), acetyloxy group, mesyloxy group , A tosyloxy group, a t-butoxycarbonyloxy group, a t-butoxycarbonylmethoxy group, a tetrahydrofuranyloxy group or a tetrahydropyranyloxy group,
A butyl group, an acetyl group, an isopropoxy group, and a tetrahydrofuranyloxy group are more preferred. R ₆ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, an aromatic group which may have a substituent having 6 to 12 carbon atoms, or 7 to 18 carbon atoms. Aralkyl group which may have a substituent, preferably a t-butyl group,
And a 1-methylcyclohexyl group.

R₇And R₈Are each independently a hydrogen source
, Linear, branched or cyclic alkyl having 1 to 8 carbon atoms
Group, an aromatic group having 6 to 12 carbon atoms, or 7-1.
Represents an aralkyl group which may have 8 substituents.
These may have a substituent. R₆~ R₈As
Specific examples of the alkyl group, aromatic group and aralkyl group
R _FourAmong the specific examples of
Can be mentioned.

In the present invention, it is essential to mix two or more types of acid-decomposable resins, and it is necessary to satisfy a specific relationship regarding the glass transition temperature (Tg) of these two types of resins. Each acid-decomposable resin has a different glass transition temperature depending on the molecular weight, the molecular weight distribution, the types and amounts of the acid-decomposable protecting groups and the non-acid-decomposable groups, and the copolymerization components. In addition, the acid-decomposable resin has its protective group decomposed and removed by the action of an acid, thereby generating a phenolic hydroxyl group, a carboxyl group, and the like, thereby increasing the glass transition temperature.

In the present invention, the glass transition point of the two types of acid-decomposable resins A and B before the acid decomposition is Tg.
(A1) The glass transition point of the resin A after acid decomposition was determined to be Tg (A
2) The glass transition point of the resin B before acid decomposition was determined by Tg (B
1) The glass transition point of the resin B after acid decomposition is determined by Tg.
Assuming (B2), as shown in FIG. 1, Tg (A1)>
Tg (B1), and Tg (A2) <Tg (B2)
It is necessary to satisfy

The glass transition point Tg (A
In order to lower the glass transition point Tg (B2) of the resin B after the acid decomposition of the resin B, the precursor resin before introducing the acid-decomposable group may have a molecular weight smaller than that of the resin B, or may be a non-acidic resin. It is effective to introduce a decomposable group or copolymerize a monomer having a low glass transition point. When the same non-acid-decomposable group is introduced, it is possible to make the glass transition point lower than that of the resin B by increasing the amount of introduction. When the introduced amount is the same, it is effective to use a group having a high Tg reduction effect such as long-chain alkyl. Glass transition point Tg (B1) of resin B before acid decomposition
To lower the glass transition point (A1) of the resin A before the acid decomposition of the resin A, the amount of the acid-decomposable group to be introduced is increased, or the acid-decomposable group to be introduced is a long-chain alkyl group or a bulky substituent. It is effective to use an acid-decomposable group having the same. In the synthesis of the resin, it is possible to polymerize the corresponding monomer in the presence of a solvent or in bulk by ordinary radical polymerization, anionic polymerization, cationic polymerization, etc., and to introduce an acid-decomposable group by a polymer reaction as necessary. . Further, it can also be obtained by copolymerizing a monomer having an acid-decomposable group alone or with another polymerizable monomer.

Further, Tg (A1) is preferably 5 to 60 ° C. higher than Tg (B1), and more preferably 10 to 50 ° C. higher. Tg (A2) is preferably higher by 10 to 70 ° C, more preferably higher by 15 to 50 ° C, than Tg (A1). Tg (B2) is Tg (A2)
More preferably, the temperature is higher by 5 to 70 ° C, more preferably 10 to 50 ° C.

Tg can be measured using a differential scanning calorimeter (DSC). The acid-decomposed Tg is obtained by dissolving the acid-decomposable group polymer in a suitable solvent, adding an acid such as hydrochloric acid, sulfuric acid, or paratoluenesulfonic acid, and heating in the presence of water to remove the protective group. It can be obtained by removing the solvent by water precipitation or the like, solidifying, powdering, and drying. When introducing an acid-decomposable group in a polymer reaction, the Tg of the polymer before the reaction may be measured.

The mixing ratio of the resin A and the resin B is generally from 10:90 to 90:10, preferably 2 by weight.
0: 80-80: 20, more preferably 30: 70-7
0:30.

The acid-decomposable resin used in the present invention may contain an acid-decomposable resin other than the above-mentioned resins A and B. Is generally 10 to 100% by weight, preferably 30 to 100% by weight.
It is 100% by weight, more preferably 50 to 100% by weight.

The structure, composition, molecular weight, and glass transition point of the resin before and after acid decomposition are shown below by giving specific examples of the resin.

[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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[0030]

[Table 1]

Examples of combinations of resins according to the present invention include, for example, P-5 in Table 1 above, P-5, P-4, P-1
8, P-21, P-6, P-14, P-2, P-19, P-20, P-15, P-9, P-
16, P-11, etc., P-4, P-18,
P-21, P-6, P-14, P-2, P-19, P-20, P-15, P-16, P-11
P-5, P-1, P-4, P for P-7
-18, P-21, P-6, P-14, P-2, P-19, P-20, P-15, P-9,
Combination with P-16, P-12, P-11, etc., but for P-8, P-3, P-10, P-5, P-18, P-21, P-6, P- 14, P-2, P-1
9, P-20, P-15, P-16, P-11
For 3, P-3, P-10, P-5, P-18, P-21, P-6, P-1
4, P-2, P-19, P-20, P-16, P-11, etc .; P-17, P-3, P-5, etc.
For P, combinations with P-16, P-11 and the like are preferable, and for P-14, combinations with P-2, P-19, P-20 and the like are preferable combinations.

The weight average molecular weight of each of the resins A and B was determined by gel permeation chromatography (GPC).
Is preferably 2,000 to 200,000, and 4,000 in terms of polystyrene equivalent molecular weight (Mw).
~ 50,000 is more preferable, and 7,000-30,0
00 is particularly preferred. When the molecular weight exceeds 200,000, the solubility is poor and the resolving power is reduced. When the molecular weight is less than 2,000, the film tends to be thin. Further, the molecular weight distribution (weight average molecular weight / number average molecular weight) is narrow (1.03
~ 1.40) Resins are suitably used from the viewpoint of resolution.

[2] Photoacid Generator As the compound used in the present invention that generates an acid upon irradiation with actinic rays or radiation (photoacid generator: also includes a compound that generates an acid by an electron beam), cationic photopolymerization A photoinitiator,
Known light (400 to 200 nm ultraviolet light, far ultraviolet light, particularly preferably g-line and h-line) used in photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, micro resists, etc. , I-ray, KrF excimer laser light), ArF excimer laser light, F2 excimer laser light, electron beam, X-ray, molecular beam, ion beam, etc., and a compound capable of generating an acid and a mixture thereof can be appropriately selected and used. it can.

Other photoacid generators used in the present invention include, for example, onium salts such as diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts and arsonium salts.
Organic halogen compound, organic metal / organic halide, o
A photoacid generator having a nitrobenzyl-type protecting group; a compound represented by photolysis such as iminosulfonate which generates sulfonic acid; a disulfone compound; a diazoketosulfone; and a diazodisulfone compound.
In addition, a group in which an acid is generated by the light or a compound in which a compound is introduced into a main chain or a side chain of a resin can be used.

Further, VNRPillai, Synthesis, (1), 1 (198
0), A. Abad etal, Tetrahedron Lett., (47) 4555 (1971),
DHR Barton et al., J. Chem. SoC., (C), 329 (1970), U.S. Pat. No. 3,779,778, European Patent 126,712, and the like can also be used compounds which generate an acid by light.

Among the above-mentioned compounds which generate an acid, those which are used particularly effectively will be described below. (1) The following general formula (PAG) substituted with a trihalomethyl group
The oxazole derivative represented by 1) or the general formula (PAG)
An S-triazine derivative represented by 2).

[0037]

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In the formula, R ²⁰¹ is a substituted or unsubstituted aryl group or alkenyl group, and R ²⁰² is a substituted or unsubstituted aryl group, alkenyl group, alkyl group, —C (Y) ₃
Show Y represents a chlorine atom or a bromine atom. Specific examples include the following compounds, but the present invention is not limited thereto.

[0039]

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(2) An iodonium salt represented by the following formula (PAG3) or a sulfonium salt represented by the following formula (PAG4).

[0041]

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Here, the formulas Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group. R ²⁰³ , R ²⁰⁴ ,
R ²⁰⁵ each independently represents a substituted or unsubstituted alkyl group or aryl group.

Z ^- represents a counter anion, for example, B
F ₄ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , SiF ₆ ²⁻ , Cl
_{^{O 4 -, CF 3 SO 3}} - perfluoroalkane sulfonate anion such as, pentafluorobenzenesulfonic acid anion, condensed polynuclear aromatic sulfonic acid anion such as naphthalene-1-sulfonic acid anion, anthraquinone sulfonic acid anion, a sulfonic acid group Dyes and the like may be included, but are not limited thereto.

Further, two of R ²⁰³ , R ²⁰⁴ and R ²⁰⁵ and Ar ¹ and Ar ² may be bonded through a single bond or a substituent.

Specific examples include the following compounds, but are not limited thereto.

[0046]

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[0047]

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[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 the above, Ph represents a phenyl group.
The onium salts represented by the general formulas (PAG3) and (PAG4) are known and can be synthesized, for example, by the methods described in U.S. Pat. Nos. 2,807,648 and 4,247,473 and JP-A-53-101,331. .

(3) Disulfone derivatives represented by the following formula (PAG5) or iminosulfonate derivatives represented by the following formula (PAG6).

[0056]

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In the formula, Ar ³ and Ar ⁴ each independently represent a substituted or unsubstituted aryl group. R ²⁰⁶ represents a substituted or unsubstituted alkyl group or aryl group. A represents a substituted or unsubstituted alkylene group, alkenylene group, or arylene group. Specific examples include the following compounds, but are not limited thereto.

[0058]

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[0059]

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[0060]

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[0061]

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[0062]

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(4) A diazodisulfone derivative represented by the following general formula (PAG7).

[0064]

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Here, R represents a linear, branched or cyclic alkyl group or an optionally substituted aryl group. Specific examples include the following compounds, but are not limited thereto.

[0066]

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Further, Japanese Patent Application Nos. 2000-241457 and 2000-2400
No. 60, Japanese Patent Application No. 2000-234733, Japanese Patent Application No. 2000-150217, Japanese Patent Application No. 20
Photoacid generators described in 00-188077 and Japanese Patent Application No. 2000-62378 can be suitably used.

The amount of the photoacid generator to be added is generally in the range of 0.1 to 30% by weight, preferably 0.3 to 20% by weight, more preferably 0.3 to 20% by weight, based on the solid content in the composition. Is used in the range of 0.5 to 10% by weight. If the added amount of the photoacid generator is less than 0.1% by weight, the sensitivity tends to be low. If the added amount is more than 30% by weight, the light absorption of the resist becomes too high, and the profile deteriorates and the process becomes poor. (Especially baking) The margin becomes narrow, which is not preferable.

[3] Alkali-Soluble Resin In the present invention, in the case of KrF excimer laser and electron beam exposure, in addition to the above acid-decomposable resin, an alkali-soluble resin containing no acid-decomposable group in the positive resist composition Resins can be used, which improves sensitivity.
The alkali-soluble resin containing no acid-decomposable group (hereinafter, simply referred to as an alkali-soluble resin) is a resin that is soluble in alkali, and preferably includes polyhydroxystyrene, novolak resin, and derivatives thereof.
A copolymer resin containing a p-hydroxystyrene unit can also be used as long as it is alkali-soluble. Among them, poly (p-hydroxystyrene), poly (p- / m-
(Hydroxystyrene) copolymer, poly (p- / o-hydroxystyrene) copolymer and poly (p-hydroxystyrene / styrene) copolymer are preferably used. Furthermore, poly (alkyl-substituted hydroxystyrene) resins such as poly (4-hydroxy-3-methylstyrene) and poly (4-hydroxy-3,5-dimethylstyrene), and a part of the phenolic hydroxyl groups of the above resins are alkylated. Alternatively, an acetylated resin is preferably used as long as it is soluble in alkali.

Further, when a part of the phenol nucleus (30 mol% or less of the total phenol nucleus) of the above resin is hydrogenated, the transparency of the resin is improved, and the sensitivity, the resolving power, and the rectangular formation of the profile are improved. preferable. The weight average molecular weight of the alkali-soluble resin is determined by gel permeation chromatography (GPC) in terms of polystyrene equivalent molecular weight (M
w) is preferably 2,000 to 200,000
And 4,000 to 50,000 is more preferable.
7,000 to 30,000 are particularly preferred. In the present invention, the amount of the alkali-soluble resin not containing an acid-decomposable group in the composition is preferably 2 to 60% by weight, more preferably 2 to 60% by weight, based on the total weight of the solid content of the composition. 5 to 30% by weight.

[4] Acid-decomposable dissolution-inhibiting compound Further, the invention of the present application is a compound having a certain molecular weight with respect to an alkali developer and having a single structure which is decomposed by the action of an acid and decomposable with an acid. A low molecular compound into which a group is introduced and which is decomposed by the action of an acid and has increased solubility in an alkaline developer is also preferably used. The low molecular weight compound which decomposes by the action of an acid to increase solubility in an alkali developing solution preferably has a constant molecular weight of 3000 or less, and introduces a group decomposable with an acid into a compound having a single structure. These compounds are decomposed by the action of an acid and become alkali-soluble. Preferably, the compound having at least two groups capable of being decomposed by an acid in its structure, and at the position where the distance between the acid-decomposable groups is the longest, passing through at least eight bonding atoms excluding the acid-decomposable group. is there. More preferably, 1
A compound passing through 0, more preferably 12, or at least 3 acid-decomposable groups, and at the position where the distance between the acid-decomposable groups is the longest, at least 9 bonding atoms excluding the acid-decomposable group are present. , Preferably at least 10 and more preferably 11 compounds. The preferred upper limit of the number of the bonding atoms is 50, more preferably 30. In the present invention, when the acid-decomposable dissolution-inhibiting compound has three or more, preferably four or more acid-decomposable groups, and even when the compound has two acid-decomposable groups, the acid-decomposable groups are mutually present. If more than a certain distance is accustomed, Arca
The dissolution inhibiting property for the resoluble resin is significantly improved.

The acid-decomposable dissolution inhibiting compound may have a plurality of acid-decomposable groups on one benzene ring.
Preferably, a compound composed of a skeleton having one acid-decomposable group on one benzene ring is preferable. Further, the molecular weight of the dissolution inhibiting compound is preferably 3000 or less, more preferably 500 to 3000, and still more preferably 1,000.
２2500. The group which can be decomposed by an acid is preferably a silyl ether group, a cumyl ester group, an acetal group, a tetrahydropyranyl ether group, an enol ether group, an enol ester group, a tertiary alkyl ether group, or a tertiary alkyl ester group. And tertiary alkyl carbonate groups. More preferably, the third
And a tertiary alkyl carbonate group, a cumyl ester group and a tetrahydropyranyl ether group.

[5] Organic Basic Compound An organic basic compound can be further added to the composition of the present invention. Preferred organic basic compounds that can be used in the present invention are compounds that are more basic than phenol. Among them, a nitrogen-containing basic compound is preferable. By adding the organic basic compound, the sensitivity fluctuation over time is improved. Examples of the organic basic compound include a compound having a structure shown below.

[0074]

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Here, R²⁵⁰, R²⁵¹And R²⁵²Are each
Independently, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
1-6 aminoalkyl groups, hydroxy having 1-6 carbon atoms
Alkyl group or substituted or unsubstituted 6 to 20 carbon atoms
An aryl group, where R ²⁵¹And R²⁵²Are connected to each other
To form a ring.

[0076]

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Wherein R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R
²⁵⁶ independently represents an alkyl group having 1 to 6 carbon atoms.) Further preferred compounds are nitrogen-containing basic compounds having two or more nitrogen atoms having different chemical environments in one molecule, and particularly preferred. , A compound containing both a substituted or unsubstituted amino group and a ring structure containing a nitrogen atom, or a compound having an alkylamino group. Preferred specific examples include substituted or unsubstituted guanidine, substituted or unsubstituted aminopyridine, substituted or unsubstituted aminoalkylpyridine, substituted or unsubstituted aminopyrrolidine, substituted or unsubstituted indazol, substituted or unsubstituted Pyrazole, substituted or unsubstituted pyrazine, substituted or unsubstituted pyrimidine, substituted or unsubstituted purine, substituted or unsubstituted imidazoline, substituted or unsubstituted pyrazoline, substituted or unsubstituted piperazine, substituted or unsubstituted amino Morpholine, substituted or unsubstituted aminoalkylmorpholine and the like. Preferred substituents are an amino group, aminoalkyl group, alkylamino group, aminoaryl group, arylamino group, alkyl group, alkoxy group, acyl group, acyloxy group, aryl group, aryloxy group, nitro group, hydroxyl group, cyano group It is.

Preferred specific examples of the nitrogen-containing basic compound include dicyclohexylmethylamine, guanidine,
1-dimethylguanidine, 1,1,3,3-tetramethylguanidine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2-dimethylaminopyridine, 4-dimethylaminopyridine, 2-diethylaminopyridine, 2- (aminomethyl) pyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-6
-Methylpyridine, 3-aminoethylpyridine, 4-aminoethylpyridine, 3-aminopyrrolidine, piperazine, N- (2-aminoethyl) piperazine, N- (2-
Aminoethyl) piperidine, 4-amino-2,2,6,
6-tetramethylpiperidine, 4-piperidinopiperidine, 2-iminopiperidine, 1- (2-aminoethyl)
Pyrrolidine, pyrazole, 3-amino-5-methylpyrazole, 5-amino-3-methyl-1-p-tolylpyrazole, pyrazine, 2- (aminomethyl) -5-methylpyrazine, pyrimidine, 2,4-diaminopyrimidine ,
4,6-dihydroxypyrimidine, 2-pyrazoline, 3
-Pyrazolin, N-aminomorpholine, N- (2-aminoethyl) morpholine, 1,5-diazabicyclo [4.3.0] non-5-ene, 1,8-diazabicyclo [5.4.0] Undec-7-ene, 1,4-diazabicyclo [2.2.2] octane, 2,4,5-triphenylimidazole, N-methylmorpholine, N-ethylmorpholine, N-hydroxyethylmorpholine, N-benzylmorpholine Tertiary morpholine derivatives, such as cyclohexylmorpholinoethylthiourea (CHMETU);
Examples include, but are not limited to, hindered amines described in JP-A-11-52575 (for example, those described in [0005]).

Particularly preferred specific examples are 1,5-diazabicyclo [4.3.0] non-5-ene, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,4-diazabicyclo [2.2.2] Tertiary such as octane, 4-dimethylaminopyridine, hexamethylenetetramine, 4,4-dimethylimidazoline, dicyclohexylmethylamine, pyrroles, pyrazoles, imidazoles, pyridazines, pyrimidines, and CHMETU Examples thereof include hindered amines such as morpholines and bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebagate. Among them, 1,5-diazabicyclo [4.3.0] non-5-ene, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,4-diazabicyclo [2.2.2] Octane, 4-dimethylaminopyridine, hexamethylenetetramine, CHMETU,
Bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and dicyclohexylmethylamine are preferred.

These organic basic compounds are used alone or in combination of two or more. The amount of the organic basic compound to be used is generally 0.001 to 10% by weight, preferably 0.1 to 10% by weight, based on the solid content of the entire photosensitive resin composition.
01 to 5% by weight. If the amount is less than 0.001% by weight, the effect of the addition of the organic basic compound cannot be obtained. Meanwhile, 1
If it exceeds 0% by weight, the sensitivity tends to decrease and the developability of the unexposed area tends to deteriorate.

[6] Surfactant The positive photoresist composition of the present invention may further contain another fluorine-based and / or silicon-based surfactant in addition to the fluorine-based polymer according to the present invention. Good. The positive photoresist composition of the present invention may contain a fluorine-based surfactant, a silicon-based surfactant, or a surfactant containing both a fluorine atom and a silicon atom, or may contain two or more kinds. it can.

As these surfactants, for example, those described in
No. 62-36663, JP-A-61-226746, JP-A-61-226745,
JP-A-62-170950, JP-A-63-34540, JP-A-7-23016
No. 5, JP-A-8-62834, JP-A-9-54432, JP-A-9-598
No. 8, U.S. Pat.No. 5,405,720, No. 5360692, No. 5529881,
No. 5296330, No. 5436098, No. 5576143, No. 5294511
And No. 5824451. The following commercially available surfactants can also be used as they are. As commercially available surfactants that can be used, for example, F-top EF301, EF303, (manufactured by Shin-Akita Kasei Co., Ltd.), Florad F
C430, 431 (manufactured by Sumitomo 3M Limited), Megafac F17
1, F173, F176, F189 (Dai Nippon Ink Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troysol S-366 (Troy Chemical Co., Ltd.) )) Or a silicon-based surfactant. Also, polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used as a silicon-based surfactant.

The amount of these surfactants is usually 0.001% by weight based on the solids in the composition of the present invention.
To 2% by weight, preferably 0.01% to 1% by weight. These surfactants may be added alone or in some combination. Examples of the surfactant that can be used in addition to the above include, specifically, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether. , Polyoxyethylene alkyl allyl ethers such as polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether;
Polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate,
Sorbitan fatty acid esters such as sorbitan trioleate and sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxy Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as ethylene sorbitan tristearate and the like can be mentioned. The amount of these other surfactants is usually 2 parts by weight or less, preferably 1 part by weight or less, per 100 parts by weight of the solids in the composition of the present invention.

[7] Compound for Promoting Solubility in Developer Solution A compound having two or more phenolic OH groups for promoting solubility in developer solution may be contained. Such compounds include polyhydroxy compounds, preferably polyhydroxy compounds include phenols, resorcin, phloroglucin, phloroglucid,
2,3,4-trihydroxybenzophenone, 2,3,4,
4'-tetrahydroxybenzophenone, α, α ', α''
-Tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, tris (4-hydroxyphenyl) methane, tris (4-hydroxyphenyl) ethane, 1,1′-bis (4-hydroxyphenyl) cyclohexane There is.

The chemically amplified positive resist composition of the present invention is obtained by dissolving the above components in a solvent that dissolves the components and coating the solution on a support. Examples of the solvent that can be used include ethylene dichloride, cyclohexanone, and cyclohexanone. Pentanone, 2-heptanone, γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, Ethyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate,
Propyl pyruvate, N, N-dimethylformamide,
Dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran and the like are preferable, and these solvents are used alone or in combination.

Further, N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N, N-
High-boiling solvents such as dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and benzylethyl ether can be used as a mixture.

The above-mentioned chemically amplified positive resist composition is applied onto a substrate (eg, silicon / silicon dioxide coating) used for the production of precision integrated circuit devices by an appropriate application method such as a spinner or a coater, and then applied to a predetermined area. A good resist pattern can be obtained by exposing through a mask, baking and developing.

Examples of the developer for the chemically amplified positive resist composition of the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium phosphate, sodium metasilicate and aqueous ammonia. Primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, dimethylethanolamine,
Alcoholamines such as triethanolamine, amides such as formamide and acetamide, tetramethylammonium hydroxide, trimethyl (2-hydroxyethyl) ammonium hydroxide, tetraethylammonium hydroxide, tributylmethylammonium hydroxide, tetraethanolammonium hydroxide , Methyltriethanol ammonium hydroxide,
Quaternary ammonium salts such as benzylmethyldiethanolammonium hydroxide, benzyldimethylethanolammonium hydroxide, benzyltriethanolammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, and alkalis such as cyclic amines such as pyrrole and piperidine And the like.

The positive photoresist composition of the present invention is applied on a substrate to form a thin film. The thickness of this coating film is preferably from 0.2 to 1.2 μm. In the present invention, if necessary, a commercially available inorganic or organic antireflection film can be used.

As the antireflection film, an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, α-silicon, and an organic film type formed of a light absorbing agent and a polymer material can be used. The former requires equipment such as a vacuum deposition apparatus, a CVD apparatus, and a sputtering apparatus for film formation. As the organic antireflection film, for example, Japanese Patent Publication No. 7-69
No. 611, consisting of a condensate of a diphenylamine derivative and a formaldehyde-modified melamine resin, an alkali-soluble resin, and a light absorbing agent; a reaction product of a maleic anhydride copolymer and a diamine type light absorbing agent described in US Pat. No. 5,294,680; No. 6,118,631 containing a resin binder and a methylolmelamine-based thermal crosslinking agent; Japanese Patent Application Laid-Open No. 6-118656, an acrylic resin type antireflection film having a carboxylic acid group, an epoxy group and a light absorbing group in the same molecule; JP-A-8-87115, comprising a methylolmelamine and a benzophenone-based light-absorbing agent;
No. 79509 in which a low molecular weight light absorbing agent is added to a polyvinyl alcohol resin. As an organic anti-reflection film, DUV3 manufactured by Brewer Science Co., Ltd.
0 series, DUV-40 series, AC-2 and AC-3 manufactured by Shipley Co. can also be used.

The resist solution is applied onto a substrate (eg, a silicon / silicon dioxide coating) used for the production of precision integrated circuit devices (on a substrate provided with the antireflection film if necessary), a spinner, a coater, and the like. After coating by an appropriate coating method such as that described above, exposure through a predetermined mask, baking and development can provide a good resist pattern. Here, the exposure light or radiation is preferably light having a wavelength of 150 nm to 250 nm or X.
And a KrF excimer laser (248 nm) and an ArF excimer laser (1
93 nm), F ₂ excimer laser (157 nm), X
And an electron beam.

After forming a photoresist film on a semiconductor substrate using the chemically amplified positive resist composition of the present invention,
Pattern exposure, heat treatment, and development are sequentially performed with radiation having a wavelength of 300 nm or less, and the diameter after development is about 1
A contact hole having a desired size can be obtained by forming a contact hole larger than 0 nm to 150 nm and heating the substrate at 120 ° C. to 160 ° C. for 30 seconds to 120 seconds to cause the resist to thermally flow. For example, a diameter of 150 nm can be obtained by a heat flow from a diameter of 150 nm.

[0093]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

Examples 1 to 8 and Comparative Examples 1 to 6 Each material shown in Table 2 was dissolved in 700 parts by weight of PGMEA (propylene glycol monoethyl ether acetate).
The solution was filtered through a 1 μm filter to prepare a resist solution.

Each resist solution obtained above was applied to a DUV-44 (Brewer) on a silicon wafer using a spin coater.
Science Co.) applied on a substrate with a thickness of 60 nm,
Baking was performed for 90 seconds to obtain a resist film having a thickness of 0.76 μm.

[0096]

[Table 2]

The photoacid generator and nitrogen-containing basic compound used are shown below. The resin is the acid-decomposable resin in Table 1.

[0098]

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[0099]

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[0100]

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The resist film was subjected to pattern exposure with a 248 nm KrF excimer laser stepper (NA = 0.55) through a 6% halftone mask. After exposure, heating is performed at 110 ° C. for 90 seconds, and immediately, 0.26N tetramethylammonium hydroxide (TMAH)
Development was carried out with an aqueous solution for 60 seconds, followed by rinsing with water for 30 seconds and drying. The wafer thus obtained was processed on a hot plate for 90 seconds (flow bake processing).
Hereinafter, the temperature of the hot plate during the flow bake processing is referred to as a flow bake temperature.

The pattern on the wafer not subjected to the flow bake treatment was observed with a scanning electron microscope, and the exposure amount at which the mask size portion of 240 nm (mask size) became 180 nm (first target size) was determined as the optimum exposure amount. At the optimum exposure, measure how the size of the first target size changes due to the difference in the flow bake temperature, and evaluate the optimum flow temperature (flow temperature at which the hole size becomes 130 nm) and the flow speed from the graph of FIG. did. Furthermore, by observing the shape of the section at the time the first target size has flow 130nm with a scanning electron microscope to measure the length of △ L _L and △ L _R shown in FIG. _{2, (△ L L + △} L _R ) / 2 was calculated as the bite amount, and the hole shape after the flow was evaluated. The smaller the bite, the better. Table 3 shows the evaluation results.

[0103]

[Table 3]

[0104]

According to the present invention, it is possible to form a rectangular profile exhibiting sufficient resolving power even in normal pattern formation, to reduce the pattern size only at an appropriate flow bake temperature, and to increase the flow bake speed. It is possible to provide a resist material which is appropriate, has a good shape after flow, and can easily control the flow amount.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between glass transition points before and after acid decomposability of resins A and B used in combination in the present invention.

FIG. 2 is a graph showing a relationship between a contact hole size (nm) and a flow bake temperature (° C.) for calculating a flow rate and an optimum flow temperature.

FIG. 3 is a schematic diagram showing measurement points ΔL _L and ΔL _R in a resist for calculating a bite amount as an evaluation of a hole shape after a flow.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tsukasa Yamanaka 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture F-term in Fujisha Shin Film Co., Ltd. (Reference) 2H025 AA02 AA03 AA10 AB16 AC04 AC08 AD03 BE00 BE10 BG00 FA17 FA29 2H096 AA25 BA11 EA03 EA04 GA08 HA01 4J002 BC10W BC10X BC12W BC12X EB006 EB016 EN136 EQ016 ES006 EU186 EV216 EV256 EV296 EW176 EY006 EZ006 FD310 GP03 HA05 5F046 LA13 LA18

Claims (3)

[Claims] (1) An acid-decomposable resin whose solubility in an alkali developer is increased by the action of an acid and (A) a photoacid generator, wherein the resin (A) is used before and after acid decomposition. A positive resist composition comprising a resin A and a resin B satisfying the following properties with respect to a glass transition point. Before acid decomposition: glass transition point of resin A> glass transition point of resin B After acid decomposition: glass transition point of resin A <glass transition point of resin B (2) An acid-decomposable resin whose solubility in an alkaline developer is increased by the action of an acid, and (A) a photoacid generator, wherein the resin (A) is used before and after acid decomposition. A positive resist composition for thermal flow, comprising a resin A and a resin B satisfying the following properties with respect to a glass transition point. Before acid decomposition: glass transition point of resin A> glass transition point of resin B After acid decomposition: glass transition point of resin A <glass transition point of resin B 3. After forming a photoresist film on a semiconductor substrate using the positive resist composition according to claim 1 or 2, a pattern exposure, a heat treatment, and a development treatment are sequentially performed with radiation having a wavelength of 300 nm or less. A pattern slightly larger than desired is formed, and this semiconductor substrate is
A pattern forming method of forming a pattern of a desired size by heating the resist to a temperature of 100 ° C. and thermally deforming the resist.