JPH0675377A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To form a fine resist pattern having high sensitivity to deep UV and ionizing radiation, etc., alkali developability, excellent dry-etching resistance and a good cross-sectional shape. CONSTITUTION:The photosensitive composition contains an alkali soluble polymer, a dissolution inhibitor compound having an acid decomposable substituent and a photo acid generator compound represented by the formula which generates acid by the photoirradiation. In the formula, each of R1, R2, R3, R4, R5 and R6 is a substituted or unsubstituted group such as aromatic hydrocarbon, heterocyclic, aliphatic hydrocarbon, alicyclic hydrocarbon or characteristic group, or a hydrogen atom, wherein optionally each pair of R1 or R3 and R2, and R4 or R6 and R5 forms a hydrocarbon ring or a heterocycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive composition applicable as a photoresist in fine processing of semiconductor devices.

[0002]

2. Description of the Related Art A photolithography technique using a resist is employed in a fine processing technique for various electronic parts such as a semiconductor integrated circuit. In recent years, in particular, in order to achieve high-density integration accompanying the multifunctionalization and high density of electronic devices, miniaturization of a pattern (resist pattern) formed using a resist is required in the above technique.

As a general exposure apparatus that can be adopted for this pattern formation, there is a step-and-repeat reduction projection type mask aligner called a stepper.
In such a device, g of a mercury lamp is used as a light source (radiation source).
Line (wavelength 436 nm), h line (wavelength 405 nm), i line (wavelength 365 nm), XeF as an excimer laser
(Wavelength 351 nm), XeCl (wavelength 308 nm), K
rF (wavelength 248 nm), KrCl (wavelength 222n
m), ArF (wavelength 193 nm), F ₂ (wavelength 157 n
m) and other electron beams are used. In order to form a finer pattern, a short-wavelength light source is suitable. Therefore, in view of this point, a dee such as an excimer laser is used.
A resist material that is sensitive to pUV is desired.

Conventionally, as a resist material for the above-mentioned excimer laser exposure, polymethylmethacrylate (P
A photosensitive composition comprising an acrylic polymer such as MMA) and polyglutarmaleimide (PGMI), a polymer having a phenol skeleton, and an azide-based photosensitizer is known. However, the former resist has low sensitivity to excimer laser light, and has poor dry etching resistance, which is a problem. In addition, the latter resist has excellent sensitivity and dry etching resistance, but on the other hand, the cross-sectional shape of the formed pattern becomes an inverted triangle, and skirting occurs. Difficult to manage.

Further, in the process of forming a fine resist pattern, another problem is caused as the minimum dimension is reduced. For example, when ultraviolet exposure such as deep UV is adopted, the interference effect of the reflected light due to the step on the semiconductor substrate has a great influence on the dimensional accuracy of the formed pattern. Further, in the exposure using an electron beam, it is not possible to increase the height-to-width ratio of a fine resist pattern due to the proximity effect caused by backscattering of electrons.

As one method for solving the above-mentioned problems,
Multilayer resist processes have been developed. See Solid State Technology, [S
solid state technology] 74
(1981), an overview is published, but many other studies have been published on the above system. Currently, the most commonly attempted method is a process using a three-layer resist system. This process forms a bottom layer having a role of flattening the steps of the semiconductor substrate and preventing reflection from the substrate, an intermediate layer functioning as a mask for etching the bottom layer, and a top layer as a photosensitive layer. To do.

However, the above three-layer resist process has an advantage that a fine pattern can be formed as compared with the single-layer resist method, but has a problem that the number of steps until pattern formation increases. That is, deepU
Since there is no resist material that has sufficient sensitivity to V, ionizing radiation, etc. and resistance to reactive ion etching (RIE) by oxygen plasma, these functions must be provided by the intermediate layer and the uppermost layer. Therefore, the number of steps required to form these layers increases. In view of this point, a two-layer resist process for forming a flattening layer and a layer having both etching resistance and photosensitivity is desired.

[0008]

An object of the present invention is to provide a photosensitive composition used as a photoresist in microfabrication of a semiconductor device, which is particularly effective for short wavelength radiation such as deep UV and ionizing radiation. Provided is a photosensitive composition which is sensitive, has high tolerance in exposure and development treatment with an alkaline aqueous solution, is excellent in dry etching resistance, and can form a fine resist pattern having a good cross-sectional shape. That is.

[0009]

The photosensitive composition of the present invention comprises an alkali-soluble polymer, a compound having a substituent decomposable by an acid, and an acid represented by the following general formula (1) when exposed to an acid. Generated compounds.

[0010]

[Chemical 2] In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are
A substituted or unsubstituted aromatic hydrocarbon group, the same heterocyclic group,
It represents the same aliphatic hydrocarbon group, the same alicyclic hydrocarbon group, the same characteristic group or a hydrogen atom. Incidentally, R ₁ or R ₃ and R ₂ , R ₄ or R ₆ and R ₅ may form a hydrocarbon ring or a heterocycle.

The photosensitive composition of the present invention contains the above-mentioned three components as essential components. Of these, the alkali-soluble polymer is a resin component, and the compound having a substituent decomposable by an acid is a dissolution inhibitor. Further, a positive resist composition in which a compound that generates an acid upon irradiation with light corresponds to a photoacid generator is used. That is, in the composition, the dissolution rate of the resin component in the alkaline solution is suppressed by the action of the dissolution inhibitor in the unexposed state. However, the photo-acid generator generates an acid when exposed to light and baked, and the acid functions as a catalyst.
The substituent of the dissolution inhibitor is decomposed and changed to a group exhibiting alkali solubility. Thus, in the composition, only the exposed portion exhibits alkali solubility and is removed by the development treatment using the alkali solution to form a resist pattern.

The composition of the present invention comprises
The most characteristic point is that the compound represented by the general formula (1) is used as the photoacid generator. In this compound, the following groups are extremely unstable to exposure and easily decompose to generate an acid efficiently.

[0013]

[Chemical 3] In the compound represented by the general formula (1), R ₁ , R
Examples of the aromatic hydrocarbon group introduced as ₂ , R ₃ , R ₄ , R ₅ , and R ₆ include a benzene ring group, a naphthalene ring group, an anthracene ring group, a phenanthrene ring group,
Tetralin ring group, azulene ring group, biphenylene ring group, acenaphthylene ring group, acenaphthene ring group, fluorene ring group, triphenylene ring group, pyrene ring group, chrysene ring group,
Picene ring group, perylene ring group, benzopyrene ring group, rubicene ring group, coronene ring group, ovalen ring group, indene ring group,
Pentalene ring group, heptalene ring group, indacene ring group, phenalene ring group, fluoranthene ring group, acephenanthrylene ring group, aceanthrylene ring group, naphthacene ring group, preaden ring group, pentaphene ring group, pentacene ring group,
Examples thereof include a tetraphenylene ring group, a hexaphene ring group, a hexacene ring group, a trinaphthylene ring group, a heptaphene ring group, a heptacene ring group, and a pyrantrene ring group.

In the compound represented by the general formula (1), the heterocyclic group introduced as R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is, for example, a pyrrole ring group,
Pyroline ring group, pyrrolidine ring group, indole ring group, isoindole ring group, indoline ring group, isoindoline ring group, indolizine ring group, carbazole ring group, carboline ring group, furan ring group, oxolane ring group, coumarone ring group , Coumaran ring group, isobenzofuran ring group, phthalane ring group, dibenzofuran ring group, thiophene ring group, thiolane ring group, benzothiophene ring group, dibenzothiophene ring group, pyrazole ring group, pyrazoline ring group, indazole ring group, imidazole ring group Group, imidazoline ring group, imidazolidine ring group,
Benzimidazole ring group, benzimidazoline ring group, naphthimidazole ring group, oxazole ring group, oxazoline ring group, oxazolidine ring group, benzoxazole ring group, benzoxazoline ring group, naphthoxazole ring group, isoxazole ring group, benzisoxazole Ring group, thiazole ring group, thiazoline ring group, thiazolidine ring group, benzothiazole ring group, benzothiazoline ring group, naphthothiazole ring group, isothiazole ring group, benzisothiazole ring group, triazole ring group, benzotriazole ring group, Oxadiazole ring group, thiadiazole ring group,
Benzoxadiazole ring group, benzothiadiazole ring group, tetrazole ring group, purine ring group, pyridine ring group, piperidine ring group, quinoline ring group, isoquinoline ring group, acridine ring group, phenanthridine ring group, benzoquinoline ring group , Naphthoquinoline ring group, naphthyridine ring group, phenanthroline ring group, pyridazine ring group, pyrimidine ring group, pyrazine ring group, piperazine ring group, phthalazine ring group, quinoxaline ring group, quinazoline ring group, cinnoline ring group, phenazine ring group, perimidine Ring group, triazine ring group, tetrazine ring group, pteridine ring group, oxazine ring group, benzoxazine ring group, phenoxazine ring group, thiazine ring group, benzothiazine ring group, phenothiazine ring group, oxadiazine ring group, thiadiazine ring group, dioxolane Ring group, benzodioxole ring group, di Xan ring group, benzodioxane ring group, dithiolane ring group, benzodithiol ring group, dithian ring group, benzodithian ring group, pyran ring group, chromene ring group, xanthene ring group, oxane ring group, chroman ring group, isochroman ring group, Examples thereof include a trioxane ring group, a thiane ring group, a trithiane ring group, a morpholine ring group, a quinuclidine ring group, a selenazole ring group, a benzoselenazole ring group, a naphthoselenazole ring group, a tellurazole ring group, and a benzotelrazole ring group.

In the compound represented by the general formula (1), the aliphatic hydrocarbon group introduced as R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is, for example, a methyl group. , Ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, tert-pentyl group, isopentyl group, neopentyl group, hexyl group, isohexyl group, heptyl group,
Examples include octyl group, nonyl group, decyl group, vinyl group, allyl group, isopropenyl group, propenyl group, methallyl group, crotyl group, butenyl group, pentenyl group, butadienyl group, ethynyl group, propynyl group, butynyl group, pentynyl group. To be

In the compound represented by the general formula (1), examples of the alicyclic hydrocarbon group introduced as R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ include cyclohexyl. Propyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group,
Examples thereof include a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group, a cyclopentadienyl group and a cyclohexadienyl group.

In the compound represented by the general formula (1), the characteristic group introduced as R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is, for example, a disubstituted amino group ( For example, dimethylamino group, diethylamino group, dibutylamino group, ethylmethylamino group, butylmethylamino group, diamylamino group, dibenzylamino group, diphenethylamino group, diphenylamino group, ditolylamino group, dixylylamino group, methylphenyl Amino group,
Benzylmethylamino group), mono-substituted amino group (for example, methylamino group, ethylamino group, propylamino group, isopropylamino group, tert-butylamino group, anilino group, anisidino group, phenetidino group, toluidino group, xylidino group, Pyridylamino group, thiazolylamino group, benzylamino group, benzylideneamino group), cyclic amino group (for example, pyrrolidino group, piperidino group, piperazino group, morpholino group, 1-pyrrolyl group, 1-pyrazolyl group, 1-imidazolyl group, 1- Triazolyl group), acylamino group (for example, formylamino group, acetylamino group, benzoylamino group, cinnamoylamino group, pyridinecarbonylamino group, trifluoroacetylamino group), sulfonylamino group (for example, mesylamino group,
(Ethylsulfonylamino group, phenylsulfonylamino group, pyridylsulfonylamino group, tosylamino group, taurylamino group, trifluoromethylsulfonylamino group, sulfamoylamino group, methylsulfamoylamino group, sulfanylamino group, acetylsulfanylamino group) , Ammonio group (eg, trimethylammonio group, ethyldimethylammonio group, dimethylphenylammonio group, pyridinio group, quinolinio group), amino group, hydroxyamino group, ureido group, semicarbazide group, carbazide group, disubstituted hydrazino group (Eg, dimethylhydrazino group, diphenylhydrazino group, methylphenylhydrazino group), mono-substituted hydrazino group (eg, methylhydrazino group, phenylhydrazino group, pyridylhydrazino group) Benzylidene hydrazino group), hydrazino group, azo group (for example, phenylazo group, pyridylazo group, thiazolylazo group), azoxy group, amidino group, cyano group, cyanato group, thiocyanato group, nitro group, nitroso group, oxy group (for example, Methoxy group, ethoxy group, propoxy group, butoxy group, hydroxyethoxy group, phenoxy group, naphthoxy group, pyridyloxy group, thiazolyloxy group, acetoxy group), hydroxy group, thio group (for example, methylthio group, ethylthio group, phenylthio group, Pyridylthio group, thiazolylthio group),
Mercapto group, halogen atom (for example, fluoro, chloro, bromo, iodo), carboxyl group, oxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl group, pyridyloxycarbonyl group), aminocarbonyl group (for example, Carbamoyl group, methylcarbamoyl group, phenylcarbamoyl group, pyridylcarbamoyl group, carbazoyl group, allofanoyl group, oxamoyl group, succinamoyl group),
Thiocarboxyl group, dithiocarboxyl group, thiocarbonyl group (eg, methoxythiocarbonyl group, methylthiocarbonyl group, methylthiothiocarbonyl group), acyl group (eg, formyl group, acetyl group, propionyl group, acryloyl group, benzoyl group, cinnamoyl) Group, pyridinecarbonyl group, thiazolecarbonyl group,
Trifluoroacetyl group), thioacyl group (for example, thioformyl group, thioacetyl group, thiobenzoyl group, pyridinethiocarbonyl group), sulfinic acid group, sulfonic acid group, and sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, phenyl) Sulfinyl group), sulfonyl group (for example, mesyl group, ethylsulfonyl group, phenylsulfonyl group, pyridylsulfonyl group, tosyl group, tauryl group, trifluoromethylsulfonyl group, sulfamoyl group, methylsulfamoyl group,
Sulfanilyl group, acetylsulfanylyl group), oxysulfonyl group (for example, methoxysulfonyl group, ethoxysulfonyl group, phenoxysulfonyl group, acetaminophenoxysulfonyl group, pyridyloxysulfonyl group), thiosulfonyl group (for example, methylthiosulfonyl group, Ethylthiosulfonyl group, phenylthiosulfonyl group, acetaminophenylthiosulfonyl group, pyridylthiosulfonyl group), aminosulfonyl group (for example, sulfamoyl group, methylsulfamoyl group, dimethylsulfamoyl group, ethylsulfamoyl group, Diethylsulfamoyl group, phenylsulfamoyl group, acetaminophenylsulfamoyl group, pyridylsulfamoyl group), halogenated alkyl groups (eg, chloromethyl group, bromome Group, fluoromethyl group, dichloromethyl group, dibromomethyl group, a difluoromethyl group,
Trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group), hydrocarbon group (eg, alkyl group, aryl group, alkenyl group, alkynyl group), heterocyclic group, organosilicon group (eg, silyl group, disilanine group) , Trimethylsilyl group, triphenylsilyl group).

In the compound represented by the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are the exemplified heterocyclic group, aromatic hydrocarbon group or aliphatic group. The hydrocarbon group and the alicyclic hydrocarbon group may be further substituted with the above-mentioned characteristic group.

In the compound represented by the general formula (1), when R ₁ or R ₃ and R ₂ , and / or R ₄ or R ₆ and R ₅ form a hydrocarbon ring or a heterocycle,
Specific examples thereof include unsubstituted propane rings such as cyclopropane ring, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclopentene ring, cyclohexene ring, cycloheptene ring, cyclooctene ring and cyclopentadiene ring. Hydrogen ring, benzothiazine ring, phenothiazine ring, oxadiazine ring, thiadiazine ring, dioxolane ring, benzodioxole ring, dioxane ring, benzodioxane ring, dithiolane ring, benzodithiol ring, dithian ring, benzodithian ring, pyran ring, chromene ring, Xanthene ring, oxane ring, chroman ring, isochroman ring, trioxane ring, thian ring, trithian ring, morpholine ring, quinuclidine ring, selenazole ring, benzoselenazole ring, naphthoselenazole ring, tellurazo Rings include those unsubstituted heterocyclic ring such as benzotellurazole ring, and hydrogen atoms of these rings are substituted with characteristic group as described above.

Specific examples of the compound represented by the general formula (1) are listed below.

[0021]

[Chemical 4]

[Chemical 5] Examples of the alkali-soluble polymer corresponding to the resin component in the photosensitive composition of the present invention include polymers having a hydroxyl group-introduced aryl group (for example, phenolic hydroxyl group) or a carboxyl group. Specific examples thereof include phenol novolac resins, vinyl phenol resins, isopropenyl phenol resins, copolymers of vinyl phenol with acrylic acid, acrylic acid derivatives, methacrylic acid, methacrylic acid derivatives, acrylonitrile, or styrene, and isopropenyl. Copolymer of phenol with acrylic acid, acrylic acid derivative, methacrylic acid, methacrylic acid derivative, acrylonitrile, styrene derivative, etc., acrylic resin, methacrylic resin, copolymer of acrylic acid or methacrylic acid with acrylonitrile or styrene derivative , And a copolymer of malonic acid and vinyl ether. More specifically, poly (p-vinylphenol), a copolymer of p-isopropenylphenol and acrylonitrile (copolymer ratio 1: 1), a copolymer of p-isopropenylphenol and styrene (copolymer). Polymer ratio 1: 1), copolymer of p-vinylphenol and methyl methacrylate (copolymer ratio 1: 1), copolymer of p-vinylphenol and styrene (copolymer ratio 1: 1) Is mentioned.

In the composition of the present invention, it is preferable to use a polymer containing silicon as the alkali-soluble polymer. A composition containing such a polymer as a resin component is remarkably improved in etching resistance, particularly in resistance to oxygen RIE, and thus is suitable as an upper layer of a two-layer resist process.

Examples of the silicon-containing alkali-soluble polymer usable in the present invention include (1) polysiloxane having phenol as a side chain, (2) polysilane having phenol as a side chain, and (3) silicon as a side chain. And a novolac resin synthesized from the phenol in 1.

Specific examples of the polysiloxane (1) are listed below.

[0025]

[Chemical 6]

[Chemical 7]

[Chemical 8] (N represents the degree of polymerization.) Specific examples of the polysilane (2) are listed below.

[0026]

[Chemical 9] (M and n represent a copolymer composition.) The novolak resin (3) can be synthesized, for example, by condensing a silicon-containing phenol monomer and another phenol compound with formalin or formaldehyde. it can. Specific examples of the phenol compound used here include phenol, 0-chlorophenol, m-chlorophenol, p-chlorophenol, m-cresol, p-cresol, xylesol,
Examples include bisphenol A, 4-chloro-3-cresol, dihydroxybenzene, trihydroxybenzene and the like. Specific examples of usable silicon-containing phenol monomers are listed below.

[0027]

[Chemical 10]

[Chemical 11]

[Chemical 12]

[Chemical 13]

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17] Examples of the compound having a substituent capable of being decomposed by an acid corresponding to the dissolution inhibitor in the composition of the present invention include poly-t-butylvinylbenzol and poly-t-butoxycarbonyloxystyrene described in U.S. Pat. No. 4,491,628. And a corresponding α-methylstyrene polymer; poly-t-butoxystyrene, poly-t-butoxy-α-methylstyrene described in US Pat. No. 4,603,101; poly having a t-butyl ester group or a benzyl ester group. Acrylates and polymers having such acid labile groups as side groups in or corresponding to the main chain; aromatic polymers having carbonate side groups such as t-butoxycarbonyloxy groups and trimethylsilyl ether side groups, etc. be able to. Specific examples of such compounds are listed below.

[0028]

[Chemical 18]

[Chemical 19]

[Chemical 20]

[Chemical 21]

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24]

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

[Chemical 28]

[Chemical 29]

[Chemical 30] (M and n represent a copolymer composition.) The blending amount of each of the above components in the composition of the present invention can be set as follows.

First, the compounding amount of the photoacid generator, that is, the compound represented by the general formula (1) which generates an acid upon irradiation with light is
Based on the total weight of solids of the photosensitive composition, preferably,
About 0.01 to 30% by weight, more preferably 0.5 to 1
The range is 5% by weight. The compounding amount of the compound is 0.01
If it is less than wt%, it may be difficult to exert a sufficient action as an acid catalyst. On the other hand, when it exceeds 30% by weight, the coating property of the composition (resist) is deteriorated, and it may be difficult to form a resist layer having a uniform film thickness.

The amount of the dissolution inhibitor, that is, the compound having a substituent decomposable by an acid, is preferably about 1 to 500 with respect to 100 parts by weight of the alkali-soluble polymer.
Parts by weight, more preferably 5 to 200 parts by weight. When the compounding amount of the compound is less than 1 part by weight, it becomes difficult to obtain a sufficient effect of suppressing dissolution in an alkali developing solution, which may make it difficult to form a pattern. On the other hand, when it exceeds 300 parts by weight, the coating property of the composition may be deteriorated and it may be difficult to form a resist layer having a uniform film thickness.

In addition to the above essential components, the photosensitive composition according to the present invention may optionally contain a sensitizer, a dye, a surfactant and a polymer for modifying the coating film (eg, epoxy resin, You may mix | blend polymethylmethacrylate resin, a propylene oxide-ethylene oxide copolymer, polystyrene, a silicone ladder polymer).

The photosensitive composition of the present invention is prepared in the form of a solution (varnish) by dissolving the above-mentioned essential components and additives in a suitable organic solvent and further filtering. The organic solvent is not particularly limited, for example, cyclohexane, acetone, methyl ethyl ketone, a ketone solvent such as methyl isobutyl ketone, methyl cellosolve, methyl cellosolve acetate, cellosolve solvent such as ethyl cellosolve acetate, ethyl acetate,
Examples thereof include ester solvents such as butyl acetate and isoamyl acetate, or mixed solvents thereof.

Next, the process of forming a pattern by the single layer resist method using the composition of the present invention and the etching process using this pattern will be described.

First, a photosensitive composition (varnish) of the present invention prepared in an organic solvent is applied onto a substrate by a spin coating method or a dipping method and then dried to form a resist layer (photosensitive resin layer). Form. Examples of the substrate used here include a silicon single crystal wafer, the same wafer on the surface of which various insulating films and conductive films (electrode layers, wiring layers, etc.) are formed, and a mask blank.

Next, the resist layer is subjected to pattern exposure, that is, selective exposure through a predetermined mask pattern. As the light source used for this exposure, for example,
XeF (wavelength 351 nm), XeCl (wavelength 308n)
m), KrF (wavelength 248 nm), KrCl (wavelength 22)
2 nm), ArF (wavelength 193 nm), F ₂ (wavelength 15)
(Ex. 7 nm) excimer laser, mercury lamp, etc. de
epUV, or ionizing radiation such as electron beam or X-ray. As the exposure method, either contact exposure or iso-liquid exposure may be adopted. When an electron beam is used, a pattern may be drawn on the resist layer by scanning the beam. If necessary, the resist layer after exposure may be baked at a predetermined temperature.

Subsequently, the resist layer after exposure or after baking is subjected to development treatment by an immersion method, a spray method or the like using an alkaline aqueous solution to obtain a desired resist pattern. Examples of the alkaline aqueous solution used as the developing solution include organic alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution and inorganic alkaline aqueous solutions such as potassium hydroxide and sodium hydroxide. These alkaline aqueous solutions are
It is usually used at a concentration of about 15% by weight or less. Further, the developed resist film may be rinsed with water or the like.

Using the single-layer resist pattern thus obtained as a mask, the underlying substrate is etched to transfer the above pattern. Examples of the etching means adopted here include a wet etching method and a dry etching method. In particular, the width of lines and spaces is 3 μm.
When transferring the following fine patterns, the dry etching method is preferable. In these etching processes,
As the wet etching agent, a hydrofluoric acid aqueous solution, an ammonium fluoride aqueous solution or the like is used when the silicon oxide film is an etching target, and a phosphoric acid aqueous solution, an acetic acid aqueous solution or a nitric acid aqueous solution is used when the aluminum film is an etching target. However, when a chromium-based film is to be etched, an aqueous solution of cerium ammonium nitrate or the like is used. Gases for dry etching include CF ₄ and C ₂ F
₆ , CCl ₄ , BCl ₃ , Cl ₂ , HCl, H _{2 and the} like can be mentioned, and these gases are used in combination as required. The etching conditions are based on the combination of the substance of the base substrate to which the fine pattern is transferred and the combination of the resist layer (photosensitive composition), the concentration of the wet etching agent in the reaction tank, or the gas for dry etching. The concentration, the reaction temperature, the reaction time and the like are determined, but the setting method and the like are not particularly limited.

After the above-described etching, the resist pattern remaining on the substrate is removed by a stripping agent such as J-100 manufactured by Nagase Kasei Co., or oxygen gas plasma.

Next, the process of forming a pattern by the two-layer resist method using the composition of the present invention and the etching process using this pattern will be described. still,
In these processes, it is particularly preferable to use a composition containing the silicon-containing alkali-soluble polymer as a resin component.

First, a polymer material solution (varnish) is applied on a substrate by a spin coating method or a dipping method, and then,
Baking is performed at 100 to 250 ° C. for 30 to 150 minutes to form a layer having a desired thickness (planarization layer). The polymer material used here may be any as long as it has a purity that does not hinder the production of semiconductor elements and the like. Examples of such a polymer material include, for example, a positive resist composed of a substituted o-quinonediazide and a novolac resin, polystyrene, polymethylmethacrylate,
Examples thereof include polyvinyl phenol, novolac resin, polyester, polyvinyl alcohol, polyethylene, polypropylene, polyimide, polybutadiene, polyvinyl acetate and polyvinyl butyral. These materials are used alone or in the form of a mixture.

Next, the photosensitive composition (varnish) of the present invention prepared in an organic solvent is applied onto the flattening layer by a spin coating method, a dipping method, a spraying method, a printing method, etc., and then dried. To form a photosensitive resin layer.

Subsequently, the photosensitive resin layer is subjected to pattern exposure and development treatment in the same manner as in the above-mentioned single-layer resist process to obtain a desired pattern. If necessary, the photosensitive resin layer may be baked at a predetermined temperature after exposure and before development processing.

Next, the planarizing layer is etched by oxygen RIE using the obtained photosensitive resin pattern as a mask. In this way, the exposed planarizing layer is selectively removed to form a two-layer structure pattern.

Further, using the obtained two-layer structure pattern as a mask, the underlying substrate is etched to transfer the above pattern. The etching means and conditions for this substrate are the same as those for the above-mentioned single-layer resist method.

After the etching, a pattern of a two-layer structure consisting of a flattening layer (polymer material) and a resist remaining on the substrate is formed, for example, by Nagase Kasei Co., Ltd. under the trade name: J-10.
It is removed by a stripping agent such as 0, oxygen gas plasma, or the like.

In addition to the steps described above, it does not matter at all that additional steps may be added depending on the purpose. As an example, for the purpose of improving the adhesion between the photosensitive resin layer and the flattening layer, or the flattening layer and the substrate, a step of pretreating the flattening layer or the surface of the substrate, or a baking step performed before or after the development, respectively. The UV re-irradiation step performed before the dry etching of the planarizing layer can be mentioned.

[0047]

According to the photosensitive composition of the present invention, as described above, by exposing with deepUV, ionizing radiation, etc., the photoacid generator (represented by the general formula (1)) is exposed in the exposed portion. Compound) generates an acid, and the action of this acid decomposes the dissolution inhibitor (compound having a substituent that is decomposed by the acid). As a result, the dissolution inhibiting power inherent to the dissolution inhibitor for the alkali-soluble polymer disappears, and a pattern latent image is formed. Further, when a developing process is performed, the latent image is selectively dissolved and removed in the exposed partial alkaline solution to form a positive resist pattern.

In the photosensitive composition of the present invention, since the compound represented by the general formula (1), which has a very high acid generation efficiency upon exposure to light, is used as the photoacid generator,
High sensitivity to deep UV, ionizing radiation, etc. Further, since the alkali-soluble polymer is used as the resin component, development processing with an alkali solution is possible, and a resist pattern having a good cross-sectional shape with reduced swelling and the like can be formed.

Further, the photosensitive composition of the present invention is excellent in etching resistance, particularly oxygen RIE resistance, when an alkali-soluble polymer containing silicon is used as a resin component.
This is because when a pattern obtained by using the composition is used as a mask and an etching treatment such as oxygen RIE is performed, a silicon-containing oxide film such as a silicon dioxide (SiO ₂ ) film is formed on the surface. This is because it is formed.

In particular, when the two-layer resist method is performed with the composition of the present invention containing a silicon-containing alkali-soluble polymer as the upper layer (photosensitive resin layer), the pattern of the composition is exposed in the lower layer, that is, The oxygen RIE resistance is about 10 to 100 times that of the planarization layer made of a polymer material. Therefore, by using the pattern as an oxygen RIE-resistant mask for the planarization layer and performing dry etching with oxygen plasma, a fine two-layer structure pattern having a high aspect ratio and a favorable cross-sectional shape can be formed.

[0051]

EXAMPLES The present invention will be described in more detail below with reference to examples. These examples are described for the purpose of facilitating the understanding of the present invention, and do not limit the present invention.

Examples 1 to 9 According to the formulations shown in Table 1 below, an alkali-soluble polymer, a dissolution inhibitor, that is, a compound having a substituent decomposable by an acid, and a photoacid generator, that is, a compound represented by the general formula (1) The compound represented by the formula (1) was dissolved in 280 g of ethyl cellosolve acetate, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare 9 kinds of solutions of the photosensitive composition of the present invention.

The compounds indicated by abbreviations in Table 1 are shown in succession in the same table.

Next, a solution of each composition was applied onto a silicon wafer and dried on a hot plate at 90 ° C. for 5 minutes to form a resist layer having a thickness of about 1.0 μm. Then, KrF (wavelength 248n
m) After pattern exposure (150 mJ / cm ² ) was performed by a reduction projection exposure machine using excimer laser light, baking treatment was further performed at 70 ° C. for 3 minutes on a hot plate. Next, the silicon wafer was immersed in a tetramethylammonium hydroxide aqueous solution (TMAH aqueous solution) for 1 minute to develop the resist layer, and a positive resist pattern was obtained. In Example 1, an aqueous TMAH solution having a concentration of 1.8% by weight was used, and in Examples 2 to 9, an aqueous TMAH solution having a concentration of 2.38% by weight was used.

The sectional shapes of the patterns formed in the above Examples 1 to 9 were observed with a scanning electron microscope. The results are also shown in Table 1 below.

[0056]

[Table 1]

[Chemical 31]

[Chemical 32]

[Chemical 33] As is clear from the results in Table 1, according to the compositions of Examples 1 to 9, it was possible to form a fine resist pattern having a rectangular shape and a rectangular cross section.

Examples 10 to 18 According to the formulation shown in Table 2 below, an alkali-soluble polymer, a dissolution inhibitor, that is, a compound having a substituent decomposable by an acid, and a photoacid generator, that is, the general formula (1) ) Is dissolved in 400 g of ethyl cellosolve acetate, and the solution is filtered through a membrane filter having a pore size of 0.2 μm to give 9 kinds of solutions (varnish) of the photosensitive composition of the present invention. Prepared. In these compositions, an alkali-soluble polymer containing silicon is blended.

The compounds indicated by abbreviations in Table 2 are shown in succession in the same table.

Next, a polymer material solution (resist solution) made of a commercially available novolac resin is applied to a silicon substrate by 2.0.
After being coated to a thickness of μm, it was heat-treated at 220 ° C. for 30 minutes to form a flattening layer.

Subsequently, a solution of the photosensitive composition was applied on the flattening layer to a thickness of 0.6 μm, and dried on a hot plate at 90 ° C. for 5 minutes to form a photosensitive resin layer. did. This layer is subjected to pattern exposure (100 mJ / c) by KrF (wavelength 248 nm) excimer laser light.
m ² ) and then 90 on a hot plate
Baking treatment was performed at 1 ° C. for 1 minute. Then TMAH
It was immersed in an aqueous solution for 1 minute and developed to form a positive pattern (upper layer pattern). In Example 10, an aqueous solution of TMAH having a concentration of 2.0% by weight was used, and in Examples 11 to 18, an aqueous solution of TMAH having a concentration of 2.38% by weight was used.

Next, the silicon substrate on which the upper layer pattern is formed is set in a dry etching apparatus (trade name: HIRRIE manufactured by Tokuda Manufacturing Co., Ltd.), and an output of 0.8 W / c is obtained.
RIE with oxygen plasma was performed for 2 minutes under the conditions of m ² , oxygen gas pressure of 4 pa, and flow rate of 50 SCCM, and the flattening layer was etched using the upper layer pattern as a mask. Thus, a two-layer structure pattern was obtained.

The sectional shapes of the patterns formed in Examples 10 to 18 above were observed with a scanning electron microscope. The results are also shown in Table 2 below.

[0063]

[Table 2]

[Chemical 34]

[Chemical 35]

[Chemical 36] As is clear from the results in Table 2, according to the compositions of Examples 10 to 18, it was possible to form a highly precise two-layer resist pattern having a fine and rectangular cross section.

[0064]

As described above in detail, according to the present invention, d
It is highly sensitive to eepUV and ionizing radiation, especially KrF excimer laser (248 nm) light, can be developed by an alkaline aqueous solution, has excellent dry etching resistance, and can form a fine resist pattern having a rectangular cross section. A photosensitive composition capable of being provided can be provided. Furthermore,
The photosensitive composition of the present invention is particularly excellent in oxygen RIE resistance,
Since it can be applied to a two-layer resist system and is extremely convenient for fine processing in a semiconductor device manufacturing process, its industrial value is extremely large.

Claims (1)

[Claims] 1. A photosensitive composition comprising an alkali-soluble polymer, a compound having a substituent capable of decomposing by an acid, and a compound represented by the following general formula (1) which generates an acid upon irradiation with light. [Chemical 1] In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are
Each of them represents a substituted or unsubstituted aromatic hydrocarbon group, the same heterocyclic group, the same aliphatic hydrocarbon group, the same alicyclic hydrocarbon group, the same characteristic group or a hydrogen atom. In addition, R ₁ or R ₃ and R ₂ ,
R ₄ or R ₆ and R ₅ may together form a hydrocarbon ring or a heterocycle.