JPH1010752A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a resolution and to enable dry development by exposing a resist film containing an aliphatic compd. for a pattern, sililating and developing with O2 plasma. SOLUTION: A resist film comprising a photosensitive compsn. containing an aliphatic compd., especially compd. having a terpenoid skelton or alicyclic skelton is formed on a substrate and exposed for patterning. Then the resist film is subjected to sililation to make difference of the silicon density between in the exposed part and in the nonexposed part. The film is subjected to dry development by oxygen plasma etching to selectively remove the area having low silicon density. As for the compd. having a terpenoid skelton, hydrocarbons having a C5 H8 structure as the basic compsn. almost according to the isoprene low can be used, or oxygen-contg. compds. derived from these hydrocarbons, compds. having different unsaturation degrees or derivs. of these compds. can be used. As for the alicyclic skelton, any monocyclic or polycyclic skeltons may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a resist pattern, and more particularly to a method for forming a pattern by dry development using oxygen plasma etching or the like without using a developing solution in lithography in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In forming a resist pattern, a method called wet development using an organic solvent or the like as a developing solution has conventionally been adopted. When developing the resist film using a developing solution, since the resist film swells and contracts during development, it becomes difficult to control the resolution and decrease the size of the fine pattern, and as a result,
Yield and reliability are reduced. Therefore, there is an increasing demand for a resist material capable of dry development without swelling development during development. On the other hand, from the viewpoint of the semiconductor process, since a dry process using plasma is established in CVD and etching, a dry development resist process is desired from the viewpoint of establishing a dry process throughout the manufacturing process. I have.

[0003] Further, miniaturization of circuit patterns is indispensable for high integration of large integrated circuits. For this purpose, it is necessary to increase the resolution of an exposure apparatus first. The resolution is γ / NA (where γ is the wavelength of the exposure light and NA
The numerical aperture of the lens. ), The resolution is increased by shortening the wavelength of the exposure light and increasing the numerical aperture of the lens. On the other hand, the focal intensity of the exposure device is γ /
Since it is proportional to (NA) ² , increasing the resolution inevitably reduces the depth of focus.

Since the thickness of a resist film formed on an underlayer having a step becomes non-uniform, for example, when focusing is performed on a region having a small thickness, if the depth of focus is shallow, the region on a thick region may be formed. Resolution decreases. In order to solve this problem, a multilayer resist method has been developed in which mapping and smoothing are assigned to different films. Although the resolution can be suppressed from being lowered by using this method, the number of film forming steps is increased and the economic burden is increased. Therefore, a method of forming a resist mask pattern using a selective silylation method, which can obtain the effects of a single-layer and two-layer resist method, has attracted attention.

[0005] The silylation is a method in which a silylating agent such as hexamethyldisilazane is brought into contact with a resin having an OH group to bond the silyl group to the resin. The formation is taking place. First,
A resist in which a photosensitive agent containing a naphthoquinonediazide group is mixed with a resin having an OH group is applied to a substrate to form a resist film, and the resist film is subjected to pattern exposure through a predetermined mask. Next, hexamethyldisilazane is brought into contact with the exposed resist film to selectively silylate the exposed portion of the resist film. Finally, dry development is performed using an O ₂ plasma etching apparatus to remove a non-silylated resist film in an unexposed portion, thereby obtaining a patterned resist mask.

In general, a novolak resin-based resist is used as the upper resist, and a silylating agent directly reacts with an OH group contained in the molecular structure of the resist to introduce the silyl group. A novolak-based resist is formed.

[0007]

Recently, for the purpose of improving the performance of the upper resist, improvements have been made such as introduction of side walls into the molecular structure of the novolak resin, and the resist base used for the upper resist of the pattern has been improved. The molecular structure is complicated. Therefore, the three-dimensional structure becomes very complicated, and there is a problem that the novolak resin cannot be easily silylated.

That is, after the silylation of the resist film,
Since it is subjected to RIE etching using _two- gas plasma, silyl groups must be introduced into the novolak resin until sufficient resistance to this etching is obtained. For this purpose, the silylation reaction needs to be performed at a high temperature of 120 to 150 ° C. or higher. However, when the silylation temperature is increased, the resist pattern flows and deforms, In some parts, the silylation progresses and the selectivity is lost, and furthermore, there is a problem that a resist arrow occurs.

Accordingly, an object of the present invention is to provide a pattern forming method which is suitable for fine processing of a high-density semiconductor device, has excellent resolution, and is capable of dry development which realizes all dry processing of the fine processing. And

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies on a resist material for obtaining a pattern by dry development using O ₂ plasma and a process, and as a result, have found that an aliphatic compound, particularly a menthyl group, is contained in the skeleton. After conducting pattern exposure on a resist film containing a compound, performing silylation, and then performing O ₂ plasma development, it was discovered that an ultrafine pattern with small line width variations can be formed with high resolution. Was. The present invention has been made based on such findings.

That is, the present invention provides a step of forming a resist film comprising a photosensitive composition containing an aliphatic compound on a substrate, a step of subjecting the resist film to pattern exposure, There is provided a pattern forming method including a step of performing a silylation treatment on a resist film and a step of performing dry development on the resist film subjected to the silylation treatment.

More specifically, a resist film made of a photosensitive composition containing an aliphatic compound, particularly a compound having a terpenoid skeleton or an alicyclic skeleton is formed on a substrate, and a pattern is formed on the resist film. A pattern in which the resist film is exposed and then subjected to a silylation process to provide a difference in the silicon concentration between the exposed and unexposed portions, and is subjected to dry development by oxygen plasma etching to selectively remove regions having a low silicon concentration. It is a forming method.

Hereinafter, the pattern forming method of the present invention will be described.

The photosensitive composition used in the pattern forming method of the present invention contains an aliphatic compound, in particular, a compound having a terpenoid skeleton or an alicyclic skeleton. This will be described in detail.

Specific examples of the photosensitive composition include a resin whose main chain can be cut by exposure, a resin composition containing a compound whose solubility is improved by exposure (negative resist), and a resin which can be crosslinked by exposure. And a resin composition (positive resist) containing a compound whose solubility is reduced by exposure to light.

Further, a chemically amplified resist which amplifies a photochemical reaction by a thermal reaction after exposure is effective.

The negative chemically amplified resist includes a compound called a photoacid generator capable of generating an acid upon exposure and a compound having at least one bond decomposable by an acid, for example, a dissolution inhibiting group. Compounds, and, if necessary, a photosensitive composition containing an alkali-soluble resin.

Examples of the positive chemically amplified resist include a photosensitive composition containing a photoacid generator, an alkali-soluble resin, and a compound capable of crosslinking the resin component with an acid or a compound whose solubility is reduced with an acid. Is mentioned.

The photosensitive composition used in the present invention comprises a skeleton of a compound constituting such a photosensitive composition, for example, a main chain or a side chain of a resin component, a photosensitive agent component, or a photoacid generator. The skeleton of the component contains a terpenoid skeleton or a group having an alicyclic skeleton.

A compound having a terpenoid skeleton substantially conforms to the isoprene rule, and differs in hydrocarbons having a basic composition of C ₅ H ₈ , oxygen-containing compounds derived from the hydrocarbons, and degrees of unsaturation. A compound or a derivative of the compound, which can be used as a component of the photosensitive composition.

Examples of the hydrocarbon, the oxygen-containing compound derived therefrom, and the compound having a different degree of unsaturation include myrcene, kalen, ocimene, pinene, limonene, camphene, terpinolene, tricyclene, terpinene, Fenchen, Ferrandrene, Silvestren, Sabinen, Citronellol, Pinocamperol, Geraniol, Fentyl Alcohol, Nerol, Borneol, Linalool, Menthol, Tenepineol, Carveol, Twill Alcohol, Citronellal, Yonon, Iron, Cinerol, Citral, Mentone , Pinol, cyclocitral, carbomentone,
Ascaridol, safranal, carbotanaceton, ferrandral, pimelitenone, citronellolic acid, perilaldehyde, thuyon, caron, dageton, camphor, bisabolene, santalen, zingiberen, cariophyllene, curcumen, cedren, casinen, longifolene, sesquibenijen, falsol, falsol Nerolidol, carotol, casinols, lanseol, oidesmol, cedrol, guayol, kessoglycol, cyperone, hinoki acid, eremofilone, santalic acid, zerumbong, camphoren, podocarprene, millen, phylocladen, totalen, phytol, sclareol, manol, hinokiol , Ferruginol, totarol, sugiol, ketomanoyl oxide, manoyl oxide Abietic acid, pimaric acid, neoabietic acid, levopimaric acid, iso -d- pimaric acid,
Examples thereof include compounds having a skeleton such as agatendicarboxylic acid, rubenic acid, triterpene, and carotenoid in the structure.

The alicyclic skeleton may be either a monocyclic skeleton or a polycyclic skeleton. In the present invention, a compound having the above skeleton is used as a component of the photosensitive composition. Modified and used.

When a compound having a terpenoid skeleton is used as a resin component in the photosensitive composition, a polymer having a menthyl group or a menthyl derivative group is preferable for further improving dry etching resistance. This is considered to be because a menthyl group or the like has a ring structure, so that even if one carbon-carbon bond is broken, the other bond remains. It is also considered that there is an effect based on the fact that the compound containing the menthyl group or the menthyl derivative group is chiral, and a steric effect resulting from the presence of an alkyl substituent such as an isopropyl group or a methyl group on the menthyl group. . Furthermore, the presence of the substituent contributes more to the stabilization of the ring conformation, and this is considered to have an effect. In addition, menthol (C ₁₀ H ₂₀ O), which is a raw material for a polymer having a menthyl group or a menthyl derivative group, is easily available, safe, inexpensive, and chemically very stable.

Hereinafter, the compound having a terpenoid skeleton or an alicyclic skeleton in the photosensitive composition used in the present invention will be described in detail using a menthyl group or a menthyl derivative group as an example.

The menthyl group or the menthyl derivative group is represented by the following general formula (1).

[0026]

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(In the general formula (1), R ¹ may be the same or different, and may be a hydrogen atom, a halogen atom, a hydrocarbon group, a hydroxyl group, an alkoxyl group, an amino group, an imide group, an amide group, R ¹ may be bonded to each other to form a ring.) In the general formula (1), R ¹ may be a ring, a carboxyl group, an alkoxycarbonyl group, a carbonyl group, a sulfonamide group, or a sulfonyl group. The hydrogen group may be an aliphatic group or an aromatic group, and may be substituted with a hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom, and phosphorus, and is not limited at all. The aliphatic group may be saturated or contain an unsaturated bond, and may be linear or branched. Further, the aliphatic group may include a cyclic compound. Further, the aromatic group may be unsubstituted or substituted with the aromatic group.

R ¹ is an amino group, a carboxyl group,
In the case of a hydroxyl group, its hydrogen atom may be substituted by the aforementioned hydrocarbon group R ¹ .

The menthyl group or the menthyl derivative group represented by the general formula (1) includes, for example, 8-butylmenthyl group, 8-β-naphthylmenthyl group, 8-α-naphthylmenthyl group and the like. The menthyl group and its derivative may be present in any part of the polymer and are not particularly limited.

In order to obtain a polymer containing a group having an alicyclic skeleton or a terpenoid skeleton, more generally, the above-mentioned group is introduced as a side chain of a compound having a polymerizable double bond, and the alicyclic skeleton is introduced. Or a group having a terpenoid skeleton may be obtained and further homopolymerized or copolymerized.

A group having an alicyclic skeleton in the photosensitive composition,
Alternatively, the amount of the compound containing a group having a terpenoid skeleton is preferably at least 10% by weight to 95% by weight. The reason for this is that if the amount of the compound is less than 10% by weight, the selectivity of silylation between the exposed part and the unexposed part of the resist film is reduced. Conversely, if the amount is 95% by weight or more,
This is because the sensitivity of silylation may decrease. The more preferable amount of the compound having a group having an alicyclic skeleton or a group having a terpenoid skeleton in the skeleton is 20 to 20.
70% by weight, most preferably 25-70% by weight.

In the photosensitive composition used in the pattern forming method of the present invention, the group having an alicyclic skeleton or the compound having a terpenoid skeleton can be present in any component of the composition. . Thus, even when these groups are present, for example, in a photoacid generator,
The amount is preferably within the above-mentioned range finally in the solid content of the photosensitive composition.

Further, a compound having a group having an alicyclic skeleton or a group having a terpenoid skeleton is more preferably copolymerized with a vinyl compound and used as a resin component of the photosensitive composition. In particular, when a methacrylic acid ester or an acrylic acid ester is used, the solubility is improved, so that a higher resolution of the photosensitive composition can be achieved.

Examples of the vinyl compound include methyl acrylate, methyl methacrylate, α-chloroacrylate, cyanoacrylate, trifluoromethyl acrylate, α-methylstyrene, trimethylsilyl acrylate, trimethylsilyl methacrylate, trimethylsilyl α-chloroacrylate, and trimethylsilylmethyl α. -Chloroacrylate, maleic acid, fumaric acid, maleic anhydride, tetrahydropyranyl acrylate, tetrahydropyranyl methacrylate, tetrahydropyranyl α-chloroacrylate, t-butyl acrylate, t-butyl methacrylate, t-butyl α-chloroacrylate, Butadiene, glycidyl acrylate, glycidyl methacrylate, isobornyl acrylate, isobornyl meth Relate, menthyl acrylate, menthyl methacrylate, norbornyl acrylate, norbornyl methacrylate, adamantyl acrylate, adamantyl methacrylate, allyl acrylate and allyl methacrylate.

Particularly, when the copolymer composition is methyl methacrylate, α-chloromethacrylate, trifluoroethyl α
-In the case of acrylic compounds such as chloroacrylate, trifluoromethyl acrylate, and olefin sulfonic acid, the formed resist film is preferably used as a negative resist by subjecting the formed resist film to pattern exposure, silylation, and dry development. Can be. In this case, a vinyl resin having a structure represented by the general formula (1) in the side chain or an acrylic compound represented by the following general formula (2) as a base resin, and an acid A copolymer with a monomer having a decomposable group is preferred.

[0036]

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(In the general formula (2), R ² may be the same or different, and may be a hydrogen atom, a halogen atom, a hydrocarbon group, a hydroxyl group, an alkoxyl group, an amino group, an imide group, an amide group, R ² may be bonded to each other to form a ring, and R ² may be a hydrogen atom, a chlorine atom, or a carboxyl group, an alkoxycarbonyl group, a carbonyl group, a sulfonamide group, or a sulfonyl group. ,
It is preferably a cyano group or an alkyl group. Further, a compound having a group having an alicyclic skeleton or a group having a terpenoid skeleton, which is used for obtaining a polymer,
In the case of an acrylic compound represented by the general formula (2),
This is preferable because it can be easily polymerized or copolymerized. The acrylic compound is represented by the following general formula (3). The desired polymer can be obtained by homopolymerizing or copolymerizing this compound.

[0038]

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(In the above general formula (3), R ³ is a group having an aliphatic monocyclic skeleton or an aliphatic polycyclic skeleton, or an organic group containing a terpenoid skeleton, and R ⁴ is an alkyl group, Group, an alkoxycarbonyl group, a halogen atom or a hydrogen atom.) The alicyclic skeleton or terpenoid skeleton has a polymerizable structure as represented by the following general formula (4). It may be introduced into a polycarboxylic acid. This is preferable because the solubility is further improved and higher resolution is achieved. Further, polyvalent carboxylic acids are also preferable from the viewpoint of facilitating polymer synthesis.

[0040]

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(In the above general formula (4), R ⁵ and R
⁶ is a monovalent organic group or a hydrogen atom, at least one of which includes a menthyl group or a menthyl derivative group represented by the general formula (1). In the general formula (4), a group capable of being decomposed or cross-linked by an acid can be appropriately introduced into one of R ⁵ and R ⁶ .

The compound represented by the above general formula (4)
It is a structure of a body or an E body, and is not limited to either, and a polymer obtained by homopolymerizing or copolymerizing this monomer is used.

The compound represented by the above formula (3) or (4) may be copolymerized with a compound which decomposes or crosslinks with an acid. The compound that decomposes or crosslinks with this acid is represented by the following general formula (5).

[0044]

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(In the above formula (5), R ⁷ is a monovalent organic group, and R ⁸ is an alkyl group, a halogen atom or a hydrogen atom.) It is represented by the above formula (5). When the compound is a compound that decomposes with an acid, in the general formula (5),-(C =
O) OR ⁷ may be a group decomposed by an acid described later, or R ⁷ may be an organic group containing a group decomposed by such an acid.

In particular, the resin component is represented by the general formula (2)
Or a copolymer of a monomer represented by the general formula (4) and a compound having a functional group which is decomposed or cross-linked by an acid represented by the general formula (5). In some cases, by containing a photoacid generator, it can be suitably used as a chemically amplified resist.

However, in the compound represented by the above general formula (4), at least one of R ⁵ and R ⁶ is an organic group containing a menthyl group or a menthyl derivative group, and the other is an organic group which is decomposed or cross-linked by an acid. In such a case, by blending a photoacid generator with the homopolymer, it becomes possible to suitably use the photopolymer as a chemically amplified resist.

Examples of the group which is decomposed by an acid (hereinafter referred to as a dissolution inhibiting group) include, for example, isopropyl ester, ethyl ester, methyl ester, methoxymethyl ester, ethoxyethyl ester, methylthiomethyl ester, tetrahydropyranyl ester, tetrahydrofuranyl ester , Methoxyethoxymethyl ester, 2-
Trimethylsilylethoxymethyl ester, 2,2,2
-Trichloroethyl ester, 2-chloroethyl ester, 2-bromoethyl ester, 2-iodoethyl ester, 2-fluoroethyl ester, ω-chloroalkyl ester, 2-trimethylsilylethyl ester, 2
-Methylthioethyl ester, 1,3-dithianyl-2
-Methyl ester, t-butyl ester, cyclopentyl ester, cyclohexyl ester, 3-oxocyclohexyl ester, allyl ester, 3-butene-1
-Yl ester, isobornyl ester, 4-trimethylsilyl-2-buten-1-yl ester, 9-anthrylmethyl ester, 2-9 ', 10'-dioxo-anthrylmethyl ester, 1-pyrenylmethyl ester 2-trifluoromethyl-6-chromylmethyl ester, piperonyl ester, 4-picolyl ester, trimethylsilyl ester, triethylsilyl ester,
t-butyldimethylsilyl ester, isopropyldimethylsilyl ester, di-t-butylmethylsilyl ester, thiol ester, oxazole, 2-alkyl-1,3-oxazoline, 4-alkyl-5-oxo-
1,3-oxazoline, 5-alkyl-4-oxo-
1,3-dioxolane, orthoester, pentaaminecobalt complex, triethylstannyl ester, tri-n-butylstannyl ester, N, N-dimethylamide, pyrrolidineamide, piperidineamide,
5,6-dihydrophenanthridinamide, N-7-nitroindolyl ester, N-8-nitro-1,2,2,
3,4-tetrahydroquinolylamide, hydrazide, N
Esters such as -phenylhydrazide and N, N'-diisopropylhydrazide; t-butoxycarbonyl ether, methyl ether, methoxymethyl ether, methylthiomethyl ether, t-butylthiomethyl ether, t-butoxymethyl ether, Pentenyloxymethyl ether, t-butyldimethylsiloxymethyl ether, sexyldimethylsiloxymethyl ether, 2-methoxyethoxymethyl ether, 2,2,2
-Trichloroethoxymethyl ether, bis-2'-chloroethoxy-methyl ether, 2'-trimethylsilylethoxymethyl ether, 2'-triethylsilylethoxymethyl ether, 2'-triisopropylsilylethoxymethyl ether, 2'-t-butyl Dimethylsilylethoxymethyl ether, tetrahydropyranyl ether, tetrahydrothiopyranyl ether, 3-bromotetrahydropyranyl ether, 1-methoxycyclohexyl ether, 4-methoxytetrahydropyranyl ether, 4-methoxytetrahydrothiopyranyl ether, 4-methoxytetrahydrothiopyranyl ether -S, S-dioxide, 1,4-dioxan-2-yl ether, tetrahydrofuranyl ether, tetrahydrothiofuranyl ether Tel, 2,3,3a, 4,5,6,
7,7a-octahydro-7,8,8-trimethyl-
4,7-methanobenzofuran-2-yl ether, 1-
Ethoxyethyl ether, 1-2'-chloroethoxy-
Ethyl ether, 1-methyl-1-methoxyethyl ether, 2,2,2-trichloroethyl ether, 2-trimethylsilylethyl ether, t-butyl ether,
Allyl ether, 4,4 ', 4 "-tris-4', 5 '
-Dichlorophthalimidophenyl-methyl ether,
4,4 ', 4 "-tris-4', 5'-dibromophthalimidophenyl-methyl ether, 4,4 ', 4"-tris-4',5'-iodophthalimidophenyl-methyl ether, 9-anthryl Ether, 9-9'-phenyl-10'-oxo-anthryl ether (tritylone ether), 1,3-benzodithiolan-2-yl ether, benzisothiazolyl-S, S-dioxide ether, trimethylsilyl ether Ethers such as triethylsilyl ether, triisopropylsilyl ether, dimethylisopropylsilyl ether, diethylisopropylsilylether, dimethylsexylsilylether and t-butyldimethylsilylether; methylene acetal, ethylidene acetal,
2,2-trichloroethylidene acetal, 2,2,2
-Tribromoethylidene acetal and 2,2,
Acetals such as 2-triiodoethylidene acetal; ketals such as 1-t-butylethylidene ketal, isopropylidene ketal (acetonide), cyclopentylidene ketal, cyclohexylidene ketal, and cycloheptylidene ketal; methoxymethylene Acetal, ethoxymethylene acetal, dimethoxymethylene orthoester, 1-methoxyethylidene orthoester, 1-ethoxyethylidene orthoester, 1,2-dimethoxyethylidene orthoester, 1
-N, N-dimethylaminoethylidene orthoester,
And cyclic orthoesters such as 2-oxacyclopentylidene orthoester; silylketene acetals such as trimethylsilylketene acetal, triethylsilylketene acetal, triisopropylsilylketene acetal, and t-butyldimethylsilylketene acetal; Di-t-butylsilyl ether, 1,3-1 ', 1', 3 ', 3'-tetraisopropyldisiloxanilidene ether, tetra-t-butoxydisiloxane-1,3-diylidene ether, etc. Silyl ethers: dimethyl acetal, dimethyl ketal, bis-2,2,2-trichloroethyl acetal, bis-2,2,2-tribromoethyl acetal, bis-2,2,2-triiodoethyl acetal, bis −2,2 - trichloroethyl ketal, bis-2,2,2-bromoethyl ketal, bis -
Acyclic acetal or ketal such as 2,2,2-triiodoethyl ketal, diacetyl acetal, and diacetyl ketal; 1,3-dioxane,
-Methylene-1,3-dioxane, 5,5-dibromo-
1,3-dioxane, 1,3-dioxolan, 4-bromomethyl-1,3-dioxolan, 4-3′-butenyl-1,3-dioxolan, and 4,5-dimethoxymethyl-1,3-dioxolan, etc. Cyclic acetal or ketal; S, S'-dimethyl acetal, S, S'-dimethyl ketal, S, S'-diethyl acetal, S, S'-diethyl ketal, S, S '
-Dipropyl acetal, S, S'-dipropyl ketal, S, S'-dibutyl acetal, S, S'-dibutyl ketal, S, S'-dipentyl acetal, S,
Acyclic dithioacetals or ketals such as S'-dipentyl ketal, S, S'-diacetyl acetal, and S, S'-diacetyl ketal; 1,3-
Dithian acetal, 1,3-dithian ketal, 1,
Cyclic dithioacetals or ketals such as 3-dithiolane acetal and 1,3-dithiolane ketal; O-trimethylsilyl-S-alkylacetals; O-trimethylsilyl-S-alkylketals; O-methyl-S- Acyclic monothioacetals such as 2-methylthioethyl acetal; O-methyl-
Acyclic monothioacetals such as S-2-methylthioethyl ketal; cyclic monothioacetals or ketals such as 1,3-oxathiolane acetal, diselenoacetal, and diselenoketal; O
-Cyanohydrins such as -trimethylsilylcyanohydrin, O-1-ethoxyethylcyanohydrin, O-tetrahydropyranylcyanohydrin; hydrazones such as N, N-dimethylhydrazone; oxime derivatives, O-
Oximes such as methyl oxime; oxazolidine, 1
And cyclic derivatives such as -methyl-2-1'-hydroxyalkyl-imidazole and N, N-dimethylimidazolidin.

More preferably, t-butyl methacrylate, ethoxyethyl methacrylate, 3-oxocyclohexyl methacrylate, t-butyl-3-naphthyl-
T-butyl esters such as 2-propenoate, isobornyl methacrylate, trimethylsilyl methacrylate, and tetrahydropyranyl methacrylate; trimethylsilyl esters; tetrahydropyranyl esters. This is because when these groups are used, they are more easily decomposed into an acid, resulting in high sensitivity.

The content of the monomer having a dissolution inhibiting group in the copolymer is 10 to the total number of moles of the whole monomer.
A range of from about mol% to about 95 mol% is desirable. If it is less than 10 mol%, a sufficient dissolution inhibiting effect cannot be imparted, while if it exceeds 95 mol%, the resolution is reduced. The content of the monomer having a dissolution inhibiting group is more preferably from 15 mol% to 70 mol%.

Further, an alkali-soluble group may be further contained as a base resin component of the photosensitive composition used in the present invention. As the monomer containing an alkali-soluble group, a monomer that itself dissolves in an alkali or a base can be used. For example, monomers containing carboxylic acid, sulfonic acid, and acid anhydride can be mentioned. Two or more alkali-soluble groups may be present in the monomer. These monomers may simultaneously have other functional groups such as esters, alcohols, amines, imines, imides, sulfonamides and amides. Such a monomer may be mixed with the polymer and the compound represented by the general formula (3) or the compound represented by the general formula (4) as a monomer, It may be a copolymer composition.

The compound having an alkali-soluble group is preferably a compound represented by the general formula (2). In this compound, when R ² is a monovalent organic group, it may have a group which is soluble in an alkali or a base.

Further, (a) an alkali-soluble resin, (b)
In a photosensitive composition containing three components of a dissolution inhibitor and (c) a photoacid generator, when a menthyl or menthyl derivative group is present in the skeleton of an alkali-soluble resin,
A copolymer of the compound represented by the general formula (3) or the compound represented by the general formula (4) and the compound having an alkali-soluble group represented by the general formula (2) is preferably used. Further, in the compound represented by the general formula (4), at least one of R ⁵ and R ⁶ is an organic group containing a menthyl group or a menthyl derivative group, and the other is a hydrogen atom or an organic group containing an alkali-soluble group. In some cases, the homopolymer can be used as an alkali-soluble resin. At this time, it goes without saying that the monomer having a dissolution inhibiting group may be further made into a copolymer composition.

As the base resin component of the photosensitive composition used in the present invention, acrylic acid ester monomers represented by the general formula (2), imide monomers, sulfonamide monomers, amide monomers and An acrylic alkylaminosulfonylalkyl ester may be further contained.
For example, a methacrylic acid ester monomer, an acrylic acid ester monomer, a crotonic acid ester monomer, a thiacrylic acid ester monomer and the like can be mentioned.

In this case, an arbitrary organic group may be introduced into R ² of the general formula (2) in order to adjust the alkali solubility of the resin component.

When an alkali-soluble group is contained in the copolymer composition, the content of the monomer having the alkali-soluble group is from 1 mol% to 95 mol% with respect to the total number of moles of the whole monomer. A range is preferred. If it is less than 1 mol%, the alkali solubility after exposure may be insufficient.
If it exceeds mol%, the sensitivity may decrease. In addition,
The content of the alkali-soluble group is more preferably from 1 to 70.
Mol%.

Further, when an acrylic acid ester monomer represented by the general formula (2) is contained, it is preferable that this monomer is added in an amount of 1 to 80% with respect to the total number of monomers. . If the value deviates from this range, the resolution decreases. The content of the methacrylic acid monomer further included,
More preferably, it is 1 to 70%. It is also possible to mix several types of copolymers and use them as the base resin. Furthermore, not only the copolymer, but also the above general formula (2),
The compound represented by (4) or (5) can be used as a base resin by appropriately mixing these homopolymers.

The photoacid generator contained as a component of the chemically amplified resist composition is a compound that generates an acid upon irradiation with actinic radiation, such as an arylonium salt,
Examples include naphthoquinonediazide compounds, diazonium salts, sulfonate compounds, sulfonium compounds, iodonium compounds, and sulfonyldiazomethane compounds.

As examples of these compounds, specifically,
Triphenylsulfonium triflate, diphenyliodonium triflate, 2,3,4,4-tetrahydroxybenzophenone-4-naphthoquinonediazidosulfonate, 4-N-phenylamino-2-methoxyphenyldiazonium sulfate, 4-N -Phenylamino-2-methoxyphenyldiazonium p-ethylphenyl sulfate, 4-N-phenylamino-2-
Methoxyphenyldiazonium 2-naphthyl sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium phenyl sulfate, 2,5-diethoxy-4-N-4′-methoxyphenylcarbonylphenyldiazonium 3-carboxy-4-hydroxy Phenylsulfate, 2-methoxy-4-N-phenylphenyldiazonium 3-carboxy-4-hydroxyphenylsulfate, diphenylsulfonylmethane, diphenylsulfonyldiazomethane, diphenyldisulfone, α-methylbenzoin tosylate, pyrogallol trimesylate, and benzoin And tosylate. Further, the compounds shown in Tables 1 and 2 below and Chemical Formulas 6 to 9 may be used.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

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[0063]

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[0064]

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[0065]

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Further, an iodonium salt represented by the following formulas 10 and 11, a sulfonium salt represented by the following formulas 12 to 14, a disulfone derivative represented by the formula 15, and an imidosulfone derivative represented by the formula 16 can also be used.

[0067]

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[0068]

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[0069]

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[0070]

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[0071]

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[0072]

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[0073]

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Further, compounds represented by the following formulas (17) to (20) may be used.

[0075]

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[0076]

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[0077]

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[0078]

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In the above formula, C ¹ and C ²
Forms a single bond or a double bond, and R ′ is —CF ₃ ,
—CF ₂ CF ₃ , —CF ₂ CF ₂ H, and — (C
F ₂ ) a group selected from the group consisting of nZ ′ (n is 1 to 4, and Z ′ is selected from H, alkyl, aryl, and a group represented by the following formula (21)). And X and Y form (1) a monocyclic or polycyclic ring which may contain one or more heteroatoms,
(2) may form a fused aromatic ring, (3) may be independently hydrogen, alkyl or aryl, (4) may bind to other sulfonyloxyimide containing residues, or (5) It may be attached to a polymerizable chain or backbone.

[0080]

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In particular, it is preferable to use a photoacid generator having a naphthalene skeleton because the number of conjugated systems is increased and the light transmittance near 193 nm is increased.

Examples of the photoacid generator having a naphthalene skeleton include naphthalene, pentalene, indene, azulene, heptalene, biphenylene, as-indacene,
s-Indacene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene, fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, naphthacene, pleiadene, picene, perylene, pentaphen, pentacene, tetraphenylene, hexaphen, hexacene , Rubicene, coronene, trinaphthylene, heptaphen, heptacene, pyranthrene, ovalene, dibenzophenanthrene, benz [a] anthracene, dibenzo [a, j] anthracene, indeno [1,2-a] indene, anthra [2,1-a] Naphthacene, 1H-benzo [a] cyclopent [j] sulfonyl or sulfonate compound having an anthracene ring; naphthalene, pentalene,
Inden, azulene, heptalene, biphenylene, as
-Indacene, s-indacene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene,
Fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, naphthacene, pleiaden, picene, perylene, pentaphene,
Pentacene, tetraphenylene, hexaphene, hexacene, rubicene, coronene, trinaphthylene, heptaphen, heptacene, pyranthrene, ovalene, dibenzophenanthrene, benz [a] anthracene, dibenzo [a, j] anthracene, indeno [1,2-a] indene, Anthra [2,1-a] naphthacene, 1H-benzo [a] cyclopent [j] 4-quinonediazide compound having a hydroxy compound on an anthracene ring; naphthalene, pentalene, indene, azulene, heptalene, biphenylene, as-indacene, s- Indacene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene, fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, naphthacene Play Aden, picene, perylene, pentaphene, pentacene, tetra-phenylene, hexaphene, hexacene, rubicene, coronene, trinaphthylene, heptaphene, heptacene, pyranthrene,
Ovalene, dibenzophenanthrene, benz [a] anthracene, dibenzo [a, j] anthracene, indeno [1,2-a] indene, anthra [2,1-a] naphthacene, 1H-benzo [a] cyclopent [j] anthracene Examples thereof include salts of sulfonium or iodonium having a side chain with triflate and the like. Particularly, a sulfonyl or sulfonate compound having a naphthalene ring or an anthracene ring: a 4-quinonediazide compound having a hydroxy compound on naphthalene or anthracene: a salt with a triflate of sulfonium or iodonium having a naphthalene or anthracene chain is preferred. Among these compounds, trinaphthylsulfonium triflate, dinaphthyliodonium triflate, dinaphthylsulfonylmethane, NAT-105 manufactured by Midori Kagaku (CAS No. [137867-
61-9]), NAT-103 manufactured by Midori Kagaku (CAS.
No. [131582-00-8]). Green Chemical N
AI-105 (CAS No. [85342-62-
7]), and TAZ-106 (CA
S. No. [69432-40-2]), Midori Kagaku NDS-105, Midori Kagaku CMS-105, Midori Kagaku DAM-301 (CAS No. [138529]
-81-4]), Midori Kagaku SI-105 (CAS.
No. [34694-40-7]), Midori Chemical ND
I-105 (CAS. No. [133710-62-
0]), EPI-105 manufactured by Midori Kagaku (CAS No.
[135133-12-9], Midori Kagaku PI-1
05 (CAS No. [41580-58-9]) is preferred. Further, compounds shown in the following Chemical formulas 22 to 26 may be used.

[0083]

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[0084]

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[0085]

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[0086]

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[0087]

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Among these compounds, more preferred are trinaphthyl sulfonium triflate, dinaphthyl iodonium triflate, dinaphthyl sulfonylmethane, and NAT-105 manufactured by Midori Kagaku (CAS.
No. [137867-61-9]), Midori Kagaku N
DI-105 (CAS No. [133710-62-
0]). And Midori Kagaku NAI-105 (CA
S. No. [85342-62-7]).

In the photosensitive composition used in the present invention, when an aliphatic compound, particularly a compound having a terpenoid skeleton or an alicyclic skeleton, is used as a photoacid generator, 193n
This is more preferable because the light transmittance near m can be further increased.

The photoacid generator is specifically,
Triphenylsulfonium triflate, diphenyliodonium triflate, 2,3,4,4-tetrahydroxybenzophenone-4-naphthoquinonediazidosulfonate, 4-N-phenylamino-2-methoxyphenyldiazonium sulfate, 4-N -Phenylamino-2-methoxyphenyldiazonium-p-ethylphenyl sulfate, 4-N-phenylamino-2
-Methoxyphenyldiazonium 2-naphthyl sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium phenyl sulfate, 2,5-diethoxy-4-N-4'-methoxyphenylcarbonylphenyldiazonium 3-carboxy-4- Examples include hydroxyphenyl sulfate, 2-methoxy-4-N-phenylphenyldiazonium 3-carboxy-4-hydroxyphenyl sulfate, diphenylsulfonylmethane, diphenylsulfonyldiazomethane, and pyrogallol trimesylate.

It is preferable that the added photoacid generator is in the range of 0.001 mol% to 50 mol% based on the whole base resin. If the amount is less than 0.001 mol%, a sufficient amount of acid is not generated, and pattern formation may not be possible,
On the other hand, if it exceeds 50 mol%, the resolution and sensitivity are undesirably reduced. The content of the photoacid generator is more preferably 0.01 to the entire base resin.
Mol% to 40 mol%.

The photosensitive composition used in the present invention comprises (a) an alkali-soluble resin, (b) a dissolution inhibitor,
(C) A negative chemically amplified resist containing three components of a photoacid generator may be used, in which a monomer having a dissolution inhibiting group is introduced as a copolymer composition of a resin component. May further contain a dissolution inhibitor.

This dissolution inhibitor has a substituent or a functional group that decomposes in the presence of an acid, as in the case of the above-mentioned dissolution inhibiting group, and the product after decomposition is converted to-(C = O) O-, -OS (= O) _2- or-
There is no particular limitation as long as it generates O-.

For example, a phenolic compound is converted to t-butoxycarbonyl ether, methyl ether, methoxymethyl ether, methylthiomethyl ether, t-butylthiomethyl ether, t-butoxymethyl ether,
Pentenyloxymethyl ether, t-butyldimethylsiloxymethyl ether, sethoxyldimethylsiloxymethyl ether, 2-methoxyethoxymethyl ether,
2,2,2-trichloroethoxymethyl ether, bis-2'-chloroethoxy-methyl ether, 2'-trimethylsilylethoxymethyl ether, 2'-triethylsilylethoxymethyl ether, 2'-triisopropylsilylethoxymethyl ether, 2 '-T-butyldimethylsilylethoxymethyl ether, tetrahydropyranyl ether, tetrahydrothiopyranyl ether, 3-bromotetrahydropyranyl ether, 1-methoxycyclohexyl ether, 4-methoxytetrahydropyranyl ether, 4-methoxytetrahydrothiopyranyl ether, 4- Methoxytetrahydrothiopyranyl ether-S, S-dioxide, 1,4-dioxan-2-yl ether, tetrahydrofuranyl ether, tetrahydrothiofurani Ether, 2,3,3
a, 4,5,6,7,7a-octahydro-7,8,8
-Trimethyl-4,7-methanobenzofuran-2-yl ether, 1-ethoxyethyl ether, 1-2'-chloroethoxy-ethyl ether, 1-methyl-1-methoxyethyl ether, 2,2,2-trichloroethyl Ether, 2-trimethylsilylethyl ether, t-butyl ether, allyl ether, 4,4 ', 4 "-tris-4', 5'-dichlorophthalimidophenyl-methyl ether, 4,4 ', 4"-tris-4' , 5'-dibromophthalimidophenyl-methyl ether, 4,4
4 ', 4 "-tris-4', 5'-iodophthalimidophenyl-methyl ether, 9-anthryl ether,
9-9'-phenyl-10'-oxo-anthryl ether (tritylone ether), 1,3-benzodithiolan-2-yl ether, benzisothiazolyl-S, S
-Dioxide ether, trimethylsilyl ether, triethylsilyl ether, triisopropylsilyl ether, dimethylisopropylsilylether, diethylisopropylsilylether, dimethylsexylsilylether, and compounds converted to t-butyldimethylsilylether. In particular, a compound obtained by protecting a phenolic compound with a t-butoxycarbonyl group, a t-butoxycarbonylmethyl group, a trimethylsilyl group, a t-butyldimethylsilyl group, or a tetrahydropyranyl group is preferable. Or isopropyl ester, ethyl ester, methyl ester, methoxymethyl ester, methylthiomethyl ester, tetrahydropyranyl ester, tetrahydrofuranyl ester, methoxyethoxymethyl ester, 2-trimethylsilylethoxymethyl ester, 2,2,2-polycarboxylic acid Trichloroethyl ester, 2-chloroethyl ester, 2
-Bromoethyl ester, 2-iodoethyl ester,
2-fluoroethyl ester, ω-chloroalkyl ester, 2-trimethylsilylethyl ester, 2-methylthioethyl ester, 1,3-dithianyl-2-methyl ester, t-butyl ester, cyclopentyl ester, cyclohexyl ester, allyl ester, 3 −
Buten-1-yl ester, 4-trimethylsilyl-2
-Buten-1-yl ester, 9-anthrylmethyl ester, 2-9 ', 10'-dioxo-anthrylmethyl ester, 1-pyrenylmethyl ester, 2-trifluoromethyl-6-chromylmethyl ester, Piperonyl ester, 4-picolyl ester, trimethylsilyl ester, triethylsilyl ester, t-butyldimethylsilyl ester, isopropyldimethylsilyl ester, di-t-butylmethylsilyl ester, thiol ester, oxazole, 2-alkyl-1,3- Oxazoline, 4-alkyl-5-oxo-1,3-oxazoline, 5-alkyl-4-oxo-1,3-dioxolane, orthoester, pentaaminecobalt complex, triethylstanyl ester, tri-n-butylstanyl ester N, N-dimethylamide, pyrrolidineamide, piperidineamide, 5,6-dihydrophenanthridinamide, N-7-nitroindolyl ester, N-8-nitro-1,2,3,4-tetrahydroquinolylamide , Hydrazide, N-phenylhydrazide,
N, N′-diisopropyl hydrazide, t-butyl ester, and the like may be used. Also,
The compounds shown in Chemical formulas 39 to 39 can also be used.

[0095]

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[0096]

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[0097]

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[0098]

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[0099]

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[0100]

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[0101]

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[0102]

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[0103]

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[0104]

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[0105]

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[0106]

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[0107]

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In particular, a compound in which a polyhydroxynaphthol having a naphthalene skeleton in its structure is protected with a t-butoxycarbonyl group is desirable because the transmittance at 193 nm is increased.

Further, a compound represented by the following general formula (6) can also be used.

[0110]

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(In the above general formula (6), R ⁹ and R ^9
10 is a hydrogen atom, a halogen atom, a cyano group, a nitro group,
It represents a silyl group or a monovalent organic group, which may be the same or different. R ⁹ and R ¹⁰ may be bonded to each other to form a ring. X is> C = O or -SO ₂ - shows a. Y represents a divalent organic group. At least one of R ⁹ , R ^{10 and} Y has a substituent or a functional group that is decomposed by an acid. In the compound represented by the general formula (6), examples of the monovalent organic group introduced as R ⁹ or R ¹⁰ include, for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, and s-butyl. And substituted or unsubstituted alicyclic or heterocyclic groups such as cyclohexyl, piperidyl and pyranine.

Further, as the divalent substituent Y, for example,
Examples include unsaturated aliphatic groups such as ethylene, propylene, and butylene; and substituted or unsubstituted alicyclic or heterocyclic groups such as cyclohexane, pyrazine, pyran, and morpholane.

It is to be noted that the compound having a substituent and a functional group which decomposes in the presence of an acid, and the decomposed product is-(C = O) O-, -OS (= O) _In the case where the composition further contains a compound producing _2- or -O-, the content is preferably in the range of 1 to 60 mol% based on the base resin.
If the ratio deviates from this range, a problem may occur in the applicability. In this case, the base resin component to be used may not contain a group that is decomposed by an acid.

In the resin component used in the present invention, an acrylic compound having a vinyl group, an allyl group, or an epoxy group in a side chain and an acrylic compound having 4 or more carbon atoms in an ester side chain are copolymerized. In the case of a composition, the formed resist film can be preferably used as a positive resist by subjecting the formed resist film to pattern exposure, silylation, and dry development. Note that the acrylic compound is represented by the aforementioned general formula (2).

In this case, a vinyl compound or an acrylic compound represented by the general formula (2) containing the structure represented by the general formula (1) is combined with an alkali-soluble general formula such as methacrylic acid or acrylic acid. A photosensitive composition can be prepared by blending a photoacid generator and a photocrosslinking agent with a copolymer with an acrylic or vinyl compound represented by (2).

As the photoacid generator, in addition to those listed for the negative type, triazines and naphthyridine compounds substituted with an alkyl halide can be used. Further, the compounds shown in Table 3 and Chemical Formula 41 below may be used.

[0117]

[Table 3]

[0118]

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Further, an oxadiazole derivative substituted with a trihalomethyl group represented by the following formula
An s-triazine derivative substituted with a trihalomethyl group shown in 3 can also be used.

[0120]

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[0121]

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Examples of the photocrosslinking agent include vinyl having an epoxy group in a side chain, an acrylic polymer represented by the general formula (2); melamine compounds such as methylol-substituted triazine and naphthyridine compounds. Can be used.

The copolymer blended as a resin component of the chemically amplified resist for silylation used in the present invention preferably satisfies the following conditions. That is, the specific gravity is 10
And an average molecular weight of 500 to 500,00
0. When the specific gravity of the resin component of the photosensitive composition exceeds 10, the site into which the silylating agent enters is too small to make it difficult to enter the resist layer, and the progress of silylation may be suppressed.

In the case of too high molecular weight polymer,
When a resist composition containing the same is irradiated with electron radiation, the irradiation and baking after the irradiation promote a cross-linking reaction, which may reduce the selectivity of silylation and deteriorate the image quality of the resist. is there.

Next, a preparation example of a photosensitive composition used in the present invention and a pattern forming method using the same will be described by taking a negative chemically amplified resist as an example.

In this case, the polymer can be prepared by dissolving the polymer, a compound which can be decomposed by an acid if necessary, and a compound which generates an acid upon irradiation with actinic radiation in an organic solvent and filtering.

When used as a conventional resist, the resist can be prepared by dissolving the polymer and a photo-crosslinking agent or a photo-main chain-cutting material in a solvent, followed by filtration. Examples of such organic solvents include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone; methyl cellosolve;
Cellosolve solvents such as 2-ethoxyethyl acetate, 2-methoxyethyl acetate, 2-propoxyethyl acetate, or 2-butoxyethyl acetate; glycol solvents such as propylene glycol monomethyl ether acetate; ethyl acetate, butyl acetate, or And ester solvents such as isoamyl acetate; γ
Lactone solvents such as -butyrolactone; nitrogen-containing solvents such as dimethyl sulfoxide, hexamethylphosphoric triamide dimethylformamide and N-methylpyrrolidone. These solvents may be used alone or as a mixed solvent. Furthermore, aromatic solvents such as xylene and toluene, or
Isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, n-butyl alcohol,
An appropriate amount of an aliphatic alcohol such as s-butyl alcohol, t-butyl alcohol, and isobutyl alcohol may be contained.

In addition to the above three components, if necessary, a surfactant as a coating modifier; epoxy resin; other polymers such as polymethyl methacrylate, propylene oxide-ethylene oxide copolymer, and polystyrene; Alternatively, a dye as an antireflection agent may be blended.

The solution of the photosensitive composition prepared as described above is applied on a substrate by a spin coating method or a dipping method, and then applied at about 150 ° C. or lower, preferably 70 to 120 ° C.
Drying at a temperature of ° C. forms a photosensitive resin layer (resist film) containing the above composition as a main component. As the substrate used here, for example, a silicon wafer, a silicon wafer having steps on the surface of various insulating films, electrodes, and wirings, a blank mask, GaAs, AlGaAs, etc.
A group II-V compound semiconductor wafer can be used.

Next, pattern exposure is performed on the resist film,
That is, irradiation of actinic radiation is performed through a predetermined mask. As the actinic radiation used for this pattern exposure, short-wavelength ultraviolet rays, electron beams, X-rays, low-pressure mercury lamp light, excimer laser light of KrF or ArF, synchrotron orbital radiation light, γ-rays, ion beams, etc. are used. However, the pattern forming method of the present invention is particularly effective for pattern exposure using an ArF excimer laser as a light source.

Subsequently, the exposed resist film is heated to 130-130 ° C. by using a hot plate, an oven, or the like, or by irradiating infrared rays.
At a temperature of 150 ° C., the resist film is subjected to silylation while baking by heat treatment for 1 to 30 minutes. The silylating agent used here is preferably selected from chlorosilanes, silazanes and aminosilanes.

Examples of the chlorosilane include trimethylchlorosilane, dimethylchlorosilane, methylchlorosilane, methyldichlorosilane, dimethylchlorosilane, dimethylvinylchlorosilane, methylvinylchlorosilane, methylchlorodisilane, methyldiphenylchlorosilane, diphenyldichlorosilane, methylphenyldichlorosilane, Examples include phenyltrichlorosilane and chloromethyldimethylchlorosilane. Examples of the silazane include hexamethyldisilazane, tetramethyldisilazane, hexamethylcyclotrisilazane, a cyclic silazane mixture, N, N-bistrimethylsilylacetamide, N , N-bistrimethylsilyltrifluoroacetamide, dimethyltrimethylsilylamine, diethyltri Chill silyl amines, and trimethylsilyl imidazole.

Examples of the aminosilane include dimethylaminodimethylsilane, diethylaminodimethylsilane, dimethylaminotrimethylsilane, diethylaminotrimethylsilane, bisdimethylaminomethylsilane, and bisdimethylaminodimethylsilane.

In the silylation, the inside of the chamber is filled with the vapor of the silylating agent, and the chamber is brought into direct contact with the substrate on which the resist film is formed. The concentration of the silylating agent in the atmosphere is preferably set to a partial pressure of about 10 to 500 torr. When the partial pressure is less than 10 torr, it is difficult to sufficiently perform silylation, while the partial pressure is 500 torr.
If the pressure exceeds torr, the selectivity between the unexposed portion and the exposed portion may be lost.

By performing the treatment under the above conditions, silylation proceeds selectively in the exposed portion of the resist film, and a difference in silicon concentration from the unexposed portion occurs. In addition,
The difference in silicon concentration between the exposed part and the unexposed part is that the density of the exposed part is at least 1.
It is preferably two or more. If less than 1.2,
There is a possibility that a sufficient etching rate difference cannot be obtained between the exposed part and the unexposed part of the resist film.

Next, the substrate subjected to the silylation treatment is placed in a vacuum vessel of a plasma etching apparatus, and dry etching is performed by oxygen plasma. At the time of etching, for example, the pressure in the vacuum vessel is 5 to 500 mt.
Oxygen plasma is generated by supplying oxygen at about 20 to 300 sccm while applying high frequency power at a power density of 0.05 to 20 Wcm ⁻² at about orr. When about 5% of carbon dioxide or sulfur dioxide is added to oxygen, effects such as anisotropy increase are obtained.

Since silicon is contained in the exposed portion of the resist film due to the above-mentioned silylation step, when this resist film is subjected to oxygen plasma treatment, silicon and oxygen react on the surface of this region to cause silicon to react. An oxide film is formed preferentially. On the other hand, in the unexposed portion, since the progress of silylation is suppressed, such an oxide film is not formed. Therefore, the exposed portion is hardly etched by the oxygen plasma, and the unexposed portion having a low silicon concentration is selectively removed to form a fine pattern.

The present inventors have found that the aliphatic compound used in the present invention, particularly the compound having a terpenoid skeleton or the compound having an alicyclic skeleton, has excellent dry etching resistance despite having no aromatic ring. Research. Since it has high dry etching resistance and does not have an aromatic ring, it has little absorption in a short wavelength region such as KrF excimer laser light and ArF excimer laser light, and is excellent in transparency.

Further, terpene is a highly safe compound which exists naturally and is used also as a fragrance raw material, foodstuff, medicine and the like. Therefore, when a compound having a terpenoid skeleton is used as a polymer, the compound after decomposition becomes a terpene, so that a photosensitive material excellent in safety can be obtained.

A resist pattern formed using these compounds has a very small variation in line width, and does not cause any deformation of the resist pattern or resist arrow at all.
This is due to the fact that the resist film after exposure can be silylated at a lower temperature and in a shorter time than before. The photosensitive composition used in the present invention is a photosensitive composition containing a component containing an aliphatic compound, in particular, a terpenoid skeleton or an alicyclic skeleton, and the specific gravity of the composition is higher than that of a novolak resin. Since it is small, silyl groups are easily incorporated. On the other hand, the conventional novolak resin has a very complicated three-dimensional structure, and the silylation reaction is hindered because the OH group, which is the reaction site, is masked by the effect of π-stacking of the benzene ring. it is conceivable that.
Therefore, when a silyl group is directly introduced into the OH group contained in the molecular structure of such a resist, the reactivity is poor due to steric hindrance, and it has been necessary to promote the reaction by heating to a high temperature.

As described above, in the present invention, since the specific photosensitive composition is used, the resist film after pattern exposure can be subjected to silylation at a low temperature and in a short time. As a result, it is possible to suppress the occurrence of pattern flow and the like, and it is possible to preferentially increase the silicon concentration only in a desired region.

By exposing the resist film silylated with high selectivity to oxygen plasma etching, a region having a low silicon concentration is selectively removed, and a resist pattern with a small line width variation is formed with extremely high accuracy. can do.

If the etching contrast between the substrate and the silylated layer is not so good when etching the substrate after the dry development, the resist under the silylated layer has high dry etching resistance. Better. Therefore, it is preferable to use an aliphatic compound having high dry etching resistance, particularly a compound having a terpenoid skeleton or an alicyclic skeleton.

[0144]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a resist mask pattern according to an embodiment of the present invention will be described below. Note that the present invention is not limited to these examples.

Example 1 First, a 50:50 copolymer of menthyl methacrylate and glycidyl methacrylate was prepared as a cyclohexanone solution (concentration: 10 wt%), and this solution was applied onto a silicon wafer by spin coating. The molecular weight of the copolymer used here was about 20,0.
The specific gravity relative to the novolak resin was 0.1.
It was about 5. Further, a heat treatment was performed at 100 ° C. for 1 minute to form a resist film. An ArF excimer laser beam is applied to the resist film at 50 mJ / cm.
Exposure was performed by irradiating with an irradiation amount of ² , and further, hexamethyldisilazane as a silylating agent was directly contacted with the exposed resist film to perform silylation, and the temperature and time were examined.

(Comparative Example 1) A copolymer having a molecular weight of 5,000
A cyclohexanone solution was obtained in the same manner as in Example 1 except that the novolak resin was changed to a novolak resin, and the silylation was carried out in the same process, and the temperature and time were examined.

The silylation temperatures and times for Example 1 and Comparative Example 1 are summarized in Table 4 below.

[0148]

[Table 4]

Here, the silylation means that the silicon concentration in the resist film becomes 3% or more. As shown in Table 4, the photosensitive composition used in the pattern forming method of Example 1 can be silylated at a lower temperature than a resist containing a novolak resin.
It can be seen that the time is remarkably short.

Example 2 First, a 50:50 copolymer of menthyl methacrylate and allyl methacrylate was prepared as follows:
It is applied as a 10% by weight cyclohexanone solution on a wafer to a thickness of 0.6 μm, and placed on a hot plate at 90 ° C., 9
Baking was performed for 0 seconds to form a resist film.

Next, an IC pattern is exposed at 50 to 500 mJcm ⁻² from an ArF excimer laser as a light source using a reduction projection type exposure apparatus or the like, and then exposed at a temperature of about 50 to 75 ° C. on a hot plate. While baking for 30 minutes, a vapor of hexamethyldisilazane as a silylating agent was brought into contact with the surface of the resist film.

The above wafer is placed in a vacuum vessel of a plasma etching apparatus, oxygen is supplied at 60 sccm, the pressure in the vacuum vessel is maintained at 30 mtorr, and the high frequency power is adjusted to a power density of 1.57 Wcm ^−2. To convert oxygen into a plasma. The oxygen plasma thus generated was brought into contact with the resist film to remove the unsilylated resist film in the unexposed area, thereby forming a resist mask.

As a result, a positive pattern of 0.12 μm could be formed.

As the alkaline solution, choline, sodium hydroxide, and potassium hydroxide can be used in addition to tetramethylammonium hydroxide.

(Examples 3 to 12) Using various copolymers, 1% by weight of triphenylsulfonium triflate as a photoacid generator was added to each to form a cyclohexanone solution, and the photosensitivity used in Examples 3 to 12 was determined. A composition was prepared. The composition, molecular weight and specific gravity of the copolymer used are summarized in Table 5 below.

[0156]

[Table 5]

Each photosensitive composition was applied on a wafer to a thickness of 0.6 μm by spin coating, and prebaked on a hot plate at 90 ° C. for 90 seconds to form a resist film.

Next, after using a ArF excimer laser as a light source and subjecting the resist film to pattern exposure at 50 mJcm ⁻² through a predetermined mask, the resist film
While heating to ° C., it was treated with a vapor of hexamethyldisilazane at a partial pressure of 40 to 200 torr for 5 minutes. This wafer is housed in a plasma generator, and the oxygen pressure is 100 mtorr.
When oxygen plasma etching was performed at a power temperature of 0.1 Wcm ⁻² , the etching rate ratio between the unexposed portion and the exposed portion was 10 or more, and a favorable negative pattern having a line width of 0.15 μm could be formed.

Further, the temperature and time of silylation were evaluated in the same manner as in Example 1, and the obtained results are summarized in Table 6 below.

[0160]

[Table 6]

As described above, according to the methods of Examples 3 to 12, silylation of the resist film can be performed with high selectivity by treating at a maximum of 75 ° C. for 15 minutes. In particular, cyclohexyl acrylate and glycidyl methacrylate can be used. In the case where a 1: 1 copolymer was used (Example 8), silylation was possible by treatment at 50 ° C. for 5 minutes.

(Comparative Example 2) Pattern formation was attempted in the same manner as in Examples 3 to 12 except that the copolymer was changed to a novolak resin, but the silylation was not easily performed.

Examples 13 to 22 Using various copolymers, 1% by weight of triphenylsulfonium triflate as a photoacid generator and 5% by weight of naphthoquinonediazide as a photocrosslinking agent were blended. Photosensitive compositions used in Examples 13 to 22 were prepared as cyclohexanone solutions. The composition, molecular weight and specific gravity of the copolymer used are summarized in Table 7 below.

[0164]

[Table 7]

Each photosensitive composition was applied on a wafer to a thickness of 0.6 μm by spin coating, and prebaked on a hot plate at 90 ° C. for 90 seconds to form a resist film.

Next, after using a ArF excimer laser as a light source and subjecting the resist film to pattern exposure at 180 mJcm ⁻² through a predetermined mask, the resist film is heated to 60 ° C. Treated with 200 torr of hexamethyldisilazane vapor for 5 minutes. This wafer is housed in a plasma generator and has an oxygen pressure of 100 mto.
When oxygen plasma etching was performed at rr and a power temperature of 0.1 Wcm ^-2 , the etching rate ratio between the unexposed portion and the exposed portion was 10 or more, and a favorable positive pattern having a line width of 0.15 μm could be formed. Was.

Further, the temperature and time of silylation were evaluated in the same manner as in Example 1, and the obtained results are summarized in Table 8 below.

[0168]

[Table 8]

As described above, according to the methods of Examples 13 to 22, the silylation of the resist film can be performed with high selectivity by performing the treatment at 75 ° C. for at most 15 minutes.
In particular, when a 1: 1 copolymer of cyclohexyl acrylate and trifluoromethyl methacrylate is used (Example 18), silylation can be performed by treatment at 50 ° C. for 5 minutes.

Comparative Example 3 Pattern formation was attempted in the same manner as in Examples 13 to 22 except that the copolymer was changed to a novolak resin, but no silylation was possible.

[0171]

As described in detail above, according to the present invention,
A resist pattern forming method capable of forming a fine pattern with a small line width variation with high resolution and high accuracy is provided. Moreover, in the method of the present invention, a pattern is formed by dry development, which leads to realization of a completely dry semiconductor manufacturing process, and is effective for high integration of a semiconductor integrated circuit, and its industrial value is enormous. is there.

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/30 568 (72) Inventor Makoto Nakase 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Corporation R & D center

Claims (3)

[Claims] A step of forming a resist film made of a photosensitive composition containing an aliphatic compound on a substrate; a step of subjecting the resist film to pattern exposure; A pattern forming method, comprising: a step of performing a chemical conversion treatment; and a step of performing dry development on the resist film subjected to the silylation treatment. 2. A step of forming a resist film made of a photosensitive composition containing a compound having a terpenoid skeleton on a substrate; a step of performing pattern exposure on the resist film; and a resist after the pattern exposure. A pattern forming method comprising: a step of performing a silylation treatment on a film; and a step of performing dry development on the resist film that has been subjected to the silylation treatment. 3. A step of forming a resist film made of a photosensitive composition containing a compound having an alicyclic skeleton on a substrate; a step of performing pattern exposure on the resist film; A step of performing a silylation treatment on the resist film of the above, and a step of performing dry development on the resist film subjected to the silylation treatment.