JP3392546B2 - Pattern formation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern used for fine processing of semiconductor devices, particularly large scale integrated circuits (LSI).
It relates to a forming method .

[0002]

2. Description of the Related Art In manufacturing semiconductor devices such as LSIs and thin-film magnetic heads such as hard disk drives, a fine processing technique by photolithography is adopted. Specifically, this technique is performed according to the following process. That is, first, a photoresist film is formed on a substrate such as a silicon single crystal wafer by, for example, a spin coating method. Next, after exposing this resist film, processing such as development and rinsing is performed to form a resist pattern. Then, a fine device is manufactured by etching the exposed wafer surface using the resist pattern as an etching resistant mask or by doping impurities, and a desired circuit is formed.

In the manufacturing process of an LSI, a processing technique capable of forming a finer pattern is required in the lithography technique as the LSI is highly integrated.
In the future, as the integration density of LSI advances to 1 Gbit,
ArF excimer laser (wavelength: 1
(93 nm) and an extremely short wavelength light source will be used.

Further, even in the hard disk drive, the recording density exceeds 1 Gbit / in, and a finer pattern will be required in the future. As a resist capable of forming a fine pattern, an alkali-soluble resin, a dissolution inhibitor,
A chemically amplified resist containing an arylonium salt having a benzene ring in the skeleton as an acid generator has been proposed (JP-A-63-27829, etc.). This chemically amplified resist has sufficient dry etching resistance for microfabrication, and moreover, the acid generated by irradiation of actinic radiation functions as a catalyst, and even a trace amount efficiently causes a chemical change inside the resist film. It is possible to form a pattern with high sensitivity.

However, such a conventional chemically amplified resist is sufficiently effective when the g-line, i-line, KrF excimer laser beam or the like which is the bright line of a mercury lamp is used as a light source. When a shorter wavelength light source such as ArF excimer laser light is used as the light source, the transparency of the material is extremely lowered, and it becomes impossible to perform patterning at all.

[0006]

Therefore [0007] The present invention aims at providing very short wavelength ultraviolet rays, particularly for ArF excimer laser, high sensitivity, a method of forming a pattern with high-resolution .

[0007]

In order to solve the above-mentioned problems, the present invention provides (a) an alkali-soluble resin, (b) a compound whose solubility is changed by an acid, and (c) an acid by irradiation with actinic radiation. a compound that generates, following the shown <br/> to the general formula (1), (2), and at least one photosensitive, containing a compound selected from the group consisting of compounds represented by (3) A resin layer containing the composition as the main component on the substrate
And a step of forming an ArF excimer laser on the resin layer.
Pattern exposure using the resin, the resin layer after the exposure
And a tree after baking.
Provided is a pattern forming method including a step of developing an oil layer .

[0008]

[Chemical 3] (In the above general formula, A is a polycyclic aromatic ring having at least 5 conjugated double bonds, Z is a chlorine atom, a bromine atom, or an iodine atom. R ¹ is a hydrogen atom; A hydrocarbon group of 6 or less; or a hydrocarbon group substituted by at least one selected from the group consisting of a halogen atom, a nitro group, and a cyano group, and B represents a substituted or unsubstituted at least A polycyclic aromatic ring having 5 conjugated double bonds, a cycloalkane, and a chain alkane, and X is CF ₃ SO ₃ , SbF ₆ ,
BF ₄ or PF ₆ . R ² and R ³ may be the same or different and each is a hydrogen atom; a halogen atom; a nitro group, a cyano group; a hydrocarbon group having 6 or less carbon atoms, a halogen atom, a nitro group, and a cyano group. A hydrocarbon group substituted with at least one selected from the group consisting of groups is shown. )

The photosensitive composition of the present invention will be described in detail below. In the photosensitive composition of the present invention, as the alkali-soluble resin as the component (a), for example, a resin containing an aryl group having a hydroxy group introduced therein or a resin containing a carboxyl group is suitable. Specific examples thereof include copolymers of methacrylic acid derivatives, acrylonitrile, styrene derivatives and the like; isopropenylphenol and acrylic acid,
Copolymer of methacrylic acid derivative, acrylonitrile, styrene derivative, etc .; Copolymer of styrene derivative with acrylic resin, methacrylic resin, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, acrylonitrile, etc .; or these polymers Mention may be made of compounds containing silicon.

These alkali-soluble resins may be used as a mixture of two or more in order to adjust the resist contrast and the dissolution rate. The content of the alkali-soluble resin in the photosensitive composition is preferably about 5 to 60% by weight, and more preferably about 20 to 30% by weight, based on the entire solid content.

In the photosensitive composition of the present invention, the compound whose solubility is changed by the acid as the component (b) is
Examples thereof include 1) a compound having a substituent that decomposes with an acid, and 2) a compound having a substituent that crosslinks with an acid.

When a compound having a substituent capable of being decomposed by an acid is contained, the resin component is not dissolved in an alkaline solution in the unexposed state due to the action of the above dissolution inhibiting group. However, an acid is generated from the acid generator upon exposure, and the dissolution inhibiting group is decomposed by the catalytic action of the acid generated by heating at room temperature or by heating to generate an alkali-soluble group. As a result, the exposed portion of the photosensitive composition becomes soluble in the alkaline solution. That is, this resist is a positive type resist.

Examples of the substituent decomposable by an acid include esters such as t-butyl ester, isopropyl ester, ethyl ester, methyl ester and benzyl ester; ethers such as tetrahydropyranyl ether; t-butoxycarbonate and methoxy. Examples thereof include alkoxy carbonates such as carbonate and ethoxy carbonate; silyl ethers such as trimethylsilyl ether, triethylsilyl ether, triphenylsilyl ether, and the like.

These substituents are, for example, bisphenol A, bisphenol F, tri (hydroxyphenyl)
Methane, phenolphthalein, cresolphthalein, thymolphthalein, catechol, pyrogallol,
Low molecular weight aromatic compounds such as naphthol, bisnaphthol A, bisnaphthol F, and benzoic acid derivatives; cholate,
It can be used by introducing it directly into a low molecular weight aliphatic alcohol such as a steroid compound, a terpenoid derivative, or a saccharide, or via a substituent. However, since the low molecular weight aromatic compound contains a benzene ring, the transparency of the resist is lost, and therefore it is more preferable to use it in combination with other compounds.

Further, a part or all of hydroxyl groups or carboxyls of the following polymer compounds may be substituted with a dissolution inhibitor. Examples of the polymer compound include, for example, naphthol novolak resin obtained by polycondensing a polycyclic aromatic ring derivative with formaldehyde under acidic conditions, a polymer having a skeleton such as naphthol or naphthalene derivative; vinylnaphthalene, vinylnaphthol, vinyl. Polymer resins having a polycyclic aromatic ring such as anthracene and vinylanthol in the side chain and copolymers thereof; some of the hydroxyl groups are methyl groups, acetyl groups, butyloxycarbonyl groups, or in order to control the dissolution rate, or Examples thereof include polymer resins having a polycyclic aromatic ring protected by a pyranyl group in a side chain, or copolymers thereof; 4-hydroxymaleimide, polyacrylic acid, polymethacrylic acid, and a polyimide precursor (polyamic acid).

Further, the above polymer compound has a wavelength of 193 nm.
Can be used as a blend or a copolymer as a mixture with the above-mentioned resins to the extent that the transparency to the above is not impaired. When a compound having a substituent that crosslinks with an acid is contained, the resin component is soluble in an alkaline solution in the unexposed state. However, an acid is generated from the acid generator upon exposure, and the above-mentioned crosslinked portion is crosslinked by the catalytic action of the acid generated by applying an ordinary temperature or heat. As a result, the exposed portion of the photosensitive composition becomes insoluble in the alkaline solution. That is, this resist is a negative type resist.

Examples of the substituent crosslinkable with an acid include a hydroxyl group, a carboxyl group, a carbonyl group, and a substituent having a molecular structure thereof. The ratio of the substituent decomposable by an acid or the substituent crosslinked by an acid can be appropriately selected. For example, it is 10 relative to t-butoxycarbonyl group.
It can be set to about 40.

The acid generator which is the component (c) is a compound which generates an acid upon exposure to light, that is, ultraviolet rays of short wavelength, electron beam, X-ray and the like. Particularly, in the present invention, the compounds represented by the general formulas (1) to (3) shown in Chemical formula 5 above are used.

Specific examples of the polycyclic aromatic ring having at least 5 conjugated double bonds in the general formulas (1) to (3) include naphthalene, anthracene, tetracene, pentacene, phenanthrene, and pyrene. To be The number of conjugated double bonds is preferably 12 or less.

The hydrocarbon groups introduced as R ¹ , R ² and R ³ into the compounds represented by the above general formulas (1) to (3) are, for example, allyl group, anisyl group, anthraquinolyl group and anatonaphthyl. Group, anthryl group, azulenyl group, benzofuranyl group, benzoquinolyl group, benzoxazinyl group, benzosazonyl group, benzyl group, biphenylenyl group, bornyl group, butenyl group, butyl group,
Cinnamyl group, crezotoyl group, cumenyl group, cyclobutadienyl group, cyclobutenyl group, cyclobutyl group, cyclopentadienyl group, cycloheptyl group, cyclohexenyl group, cyclopropyl group, cyclopropenyl group, cyclopentyl group, cyclopropenyl group, Decyl group, dimethoxyphenethyl group, diphenylmethyl group, docosyl group, dodecyl group, eicosyl group, ethyl group, fluorenyl group, furfuryl group, geranyl group, heptyl group, hexadecyl group, hexyl group, hydroxymethyl group, indanyl group, isobutyl group , Isopropyl group, isopropylbenzyl group, isoxazolyl group, menthyl group, mesityl group, methoxybenzyl group, methoxyphenyl group, methyl group, methylbenzyl group, naphthyl group, naphthylmethyl group, nonyl group, norbornyl group Group, Okutakojiru group, octyl group, oxazinyl group, oxazolidinyl group, oxazolinyl group, an oxazolyl group, a pentyl group, a phenacyl group, a phenanthryl group, a phenethyl group, a phenyl group, phthalidyl group, propynyl group, a propyl group, pyranyl group,
Pyridyl group, quinazonyl group, quinolyl group, salicyl group,
Examples thereof include a terephthalyl group, a tetrazolyl group, a thiazolyl group, a thiaftenyl group, a thienyl group, a tolyl group, a trityl group, an undecyl group, a valeryl group, a peracyl group, and a xylel group. However, the group containing a benzene ring can be used as long as the transparency is not impaired.

Further, the hydrogen atom of these hydrocarbon groups may be substituted with at least one selected from the group consisting of a halogen atom, a nitro group and a cyano group. When B in the general formulas (1) to (3) is a polycyclic aromatic ring having at least five conjugated double bonds, for example, naphthalene, anthracene, tetracene,
Pentacene, phenanthrene, pyrene, etc. are mentioned, and examples of cycloalkanes include cyclo, bicyclo, tricycloalkane, etc.

When B in the general formulas (1) to (3) is represented by AR ⁴ , the polycyclic aromatic ring A in the compound may be the same or different. . In addition, R ⁴ is substituted with at least one selected from the group consisting of a hydrocarbon group having 6 or less carbon atoms as listed in the above R ^{1 to} R ³ , or a halogen atom, a nitro group, and a cyano group. The hydrocarbon radicals mentioned can be used.

In the case of a positive resist, it is preferable that the content of the acid generator is 1 mol% or more of the dissolution inhibiting group. This amount depends on the structure of the resin, but in general, it is a solid content. This corresponds to 0.1% by weight or more. The amount of the acid generator is more preferably 0.5 to 5 mol% of the dissolution inhibiting group. Further, in the case of a negative type resist, it is preferable to be 1 mol% or more of the group crosslinked by an acid, and this amount generally corresponds to 3 to 4% by weight of the solid content though it depends on the structure of the resin. . The amount of the acid generator is more preferably 5 to 20 mol% of the above group.

The above general formulas (1), (2), and (3)
Among the compounds represented by formula (4), the compounds represented by formulas (4), (5), and (6) shown below are preferable.

[0025]

[Chemical 6]

In the photosensitive composition of the present invention, an alkali-soluble resin, a compound whose solubility is changed by an acid, and a compound which generates an acid upon irradiation with actinic radiation are dissolved in an organic solvent, and this solution is filtered. Can be prepared by Examples of the organic solvent used here include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone; cellosolve solvents such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate; ethyl acetate, butyl acetate, and the like. Examples thereof include ester solvents such as isoamyl acetate, γ-butyl lactone, and methyl 3-methoxypropionate. Further, depending on the photosensitive composition, dimethylsulfoxide, dimethylformaldehyde, N-methylpyrrolidinone or the like may be used in order to improve the solubility. Further, in recent years as an alternative solvent to the low toxicity solvents, professional and methyl-methylpropionic acid
Candidates include pionic acid derivatives , water of lactate such as ethyl lactate, and solvents such as propylene glycol monoethyl acetate.

These solvents may be used alone or in the form of a mixture. Further, these solvents may contain an appropriate amount of an aliphatic alcohol such as xylene, toluene or isopropyl alcohol.

Next, the method of forming a resist pattern using the photosensitive composition of the present invention will be described by taking a positive resist as an example. First, the photosensitive composition dissolved in the above organic solvent is applied on a substrate by a spin coating method or a dipping method, and then 150 ° C. or lower, more preferably 70 to 12
Dry at 0 ° C. to form a resist film. Examples of the substrate used here include a silicon wafer, a silicon wafer on the surface of which various insulating films and electrodes, and wiring are formed, a blank mask, and a III-V group compound semiconductor wafer such as GaAs and AlGaAs. . Also, chromium or chromium oxide vapor deposition mask, aluminum vapor deposition substrate, IBP
An SG coated substrate, a PSG coated substrate, an SOG coated substrate or the like may be used.

Next, the resist film is pattern-exposed, that is, exposed through a predetermined mask pattern. As the exposure light source used for this pattern exposure, for example,
I-line, h-line, g-line of low-pressure mercury lamp, xenon lamp light, dee such as KrF or ArF excimer laser
Various kinds of ultraviolet rays such as pUV, X-rays, electron beams, γ-rays, ion beams and the like can be used, but the effects of the photosensitive composition of the present invention are most exerted when an excimer laser of ArF is used.

Subsequently, the resist film after pattern exposure is
Heat treatment (baking) is performed at about 50 to 180 ° C, preferably about 60 to 120 ° C. By such baking, in the exposed portion of the resist film, the acid generated by the exposure acts as a catalyst and reacts with the compound having a substituent that is decomposed by the acid. If the temperature is less than 50 ° C., the acid generated by the acid generator may not be able to sufficiently react with the compound having a substituent decomposable by the acid.
If the temperature exceeds ℃, excessive decomposition or curing may occur over the exposed and unexposed areas of the resist film.

Thus, the compound having a substituent decomposable by acid is decomposed into a compound soluble in alkali. In some cases, the same effect as PEB can be obtained by leaving it at room temperature for a sufficiently long time.

Next, the resist film after baking is subjected to a developing treatment using an alkali solution according to a dipping method, a spray method or the like to selectively dissolve and remove the exposed portion of the resist film to obtain a desired pattern. Examples of the alkaline solution used as the developer here include an inorganic alkaline aqueous solution such as an aqueous solution of potassium hydroxide, sodium hydroxide, sodium carbonate, sodium silicate, and sodium metasilicate, an aqueous tetramethylammonium hydroxide solution, and trimethylhydroxy. Examples thereof include organic alkali aqueous solutions such as ethylammonium hydroxide aqueous solutions, and those obtained by adding alcohols, surfactants and the like to these. The substrate and the resist film (resist pattern) after the development process are rinsed with water or the like,
Further dry.

[0033]

In the chemically amplified resist, the quantum yield of the onium salt as an acid generator depends on the cation portion, and the anion portion shows the catalytic ability of the onium salt, which indicates the degree of action of the generated acid. decide. Since the sensitivity is represented by the product of the quantum yield and the reaction efficiency, it was judged that a cation moiety having a high quantum yield should be selected in order to improve the sensitivity and the transparency at the same time.

In order to increase the quantum yield, it is effective to increase the transparency, but in the case of an acid generator having a benzene ring in the skeleton, the absorption of the benzene ring around 193 nm is too large and the transparency is increased. Was impossible. Then, as a result of earnest research, the present inventors have found that a photosensitive composition using an acid generator containing a polycyclic aromatic ring such as a naphthalene ring and an anthracene ring is different from the case using an acid generator containing a benzene ring. In comparison, it was found that the transparency is significantly improved for light having a wavelength near 193 nm.

As described above, since the acid generator used in the photosensitive composition of the present invention is excellent in transparency in the vicinity of 193 nm, lithography using deep ultraviolet light such as ArF excimer laser light becomes possible. . Further, since the transparency is good, the amount of acid generated per photon absorbed by the acid generator increases, and a pattern can be formed with high sensitivity.

In order to increase the quantum yield, we have
Further consideration was made as follows. When an iodonium salt or sulfonium salt having two or more benzene rings is irradiated with light, one of the benzene rings becomes a radical and recombines with the other benzene ring to extract an electron from hydrogen and neutralize the acid. Occur. At this time, the quantum yield can be increased by smoothly recombining the benzene ring radical with another benzene ring.

Although such a mechanism can be applied to an iodonium salt having a naphthalene ring and the like, in the case of a naphthalene ring, it is necessary to further consider the spatial arrangement of molecules.

For example, in the photo reaction of dinaphthyl iodonium, the naphthalene ring radical rotates around I in either direction and recombines with another naphthalene ring.
In addition, when I is bonded to the naphthalene ring, there are two types of α-position or β-position, and in the molecule of dinaphthyliodonium, when I is bonded to the α-position of the naphthalene ring,
It is in a denser state than when I is bound to the β-position.

When I is bonded to the α-position, the naphthalene ring radical can be rebonded to another naphthalene ring by rotating in either direction around I, but β
When I is attached to the position, depending on the direction of rotation, the naphthalene ring radical cannot be recombined with another naphthalene ring without rotating 180 degrees around I. During this rotation, the naphthalene ring radical has a greater tendency to recombine with I rather than other naphthalene rings, resulting in a lower quantum yield.

Therefore, when dinaphthyl iodonium is used as the acid generator, it is preferable to use one having I bonded to the α-position. The steric hindrance of dinaphthyl iodonium is smaller at the β-position than at the α-position, so it is considered that the yield during synthesis is high. It is also considered that the same reaction occurs when one of the naphthalene rings is an alicyclic ring such as cyclohexane.

Also in the case of trinaphthylsulfonium, when S is bonded to the α-position of the naphthalene ring, the molecule is in a denser state, but when S is bonded to the α-position, it is compared with that of the β-position. The absorption around 193 nm is large, and the difference is large.

The problem of the spatial coordination of molecules as described for dinaphthyliodonium should be taken into consideration when the difference in absorbance around 193 nm is small, but if the difference in absorbance is large, then depending on the absorbance, It is possible to select α position or β position. Therefore, when using trinaphthylsulfonium as an acid generator,
It is preferable that S is bonded to the β-position of the naphthalene ring. Thus, the quantum efficiency of the acid generator can be further increased by selecting a molecular structure that easily causes a transfer reaction and easily generates an acid.

[0043]

The present invention will be described in more detail below by showing specific examples of the present invention. (Synthesis example 1) 136 g of naphthalene, iodoyl sulfate 191
g and 147 g of sulfuric acid were mixed and stirred, and reacted in a methanol solvent at 0 to 5 ° C. for 1 hour to obtain a trinaphthyliodonium sulfate solution. Then, the anion was replaced with trifluoromethanesulfonic acid to obtain dinaphthyliodonium trifluoromethanesulfonic acid. The yield was 65%. (Synthesis Example 2) Trinaphthylsulfonium trifluoromethanesulfonic acid was obtained by a conventional method. The yield is 4
It was 3%. (Synthesis Example 3) Bisnaphthylsulfonylmethane was obtained by a conventional method. The yield was 52%.

The spectrum of the dinaphthyl iodonium trifluorosulfonic acid (DNI.OTf) obtained in Synthesis Example 1 is shown by the curve a in FIG. It should be noted that diphenyliodonium trifluoromethanesulfonic acid (DPI · O, which is an acid generator having a benzene ring, corresponds to this compound.
The spectrum of Tf) is shown by the curve b in FIG.

Also, trinaphthylsulfonium trifluorosulfonic acid (TNS.OTf) obtained in Synthesis Example 2
The spectrum of is shown by curve c in FIG. The spectrum of triphenylsulfonium trifluoromethanesulfonic acid (TPS.OTf), which is an acid generator having a benzene ring and corresponds to this compound, is shown by a curve d in FIG.

As shown in FIGS. 1 and 2, the acid generator having a benzene ring has an absorption peak near 193 nm, but the absorption peak was 50 nm by replacing the benzene ring with a naphthalene ring. It is shifted to the long wavelength side. This is because the conjugation length of the naphthalene ring is
It is thought that this is due to the fact that it is longer than the conjugation length of the benzene ring. By thus opening the transmittance window near 193 nm, the light of this wavelength is transmitted.

Next, regarding each compound obtained in the above-mentioned Synthesis Examples 1 and 2 and a compound having a benzene ring and corresponding thereto, a photon 1 having a wavelength of 193 nm in PMMA was prepared.
The quantum yield per unit was calculated.

The quantum yield was calculated as follows. Quantum yield = (number of generated acid generated by acid generator) / (number of photons absorbed in acid generator) Here, the number of acid is per unit volume generated by reaction by photoreaction in the polymer matrix. Is defined as the number of acids in. The number of acids was determined by observing the fading of an indicator prepared by dissolving tetrabromophenol blue sodium salt in ethyl cellosolve acetate at 7.9 × 10 ⁻⁵ mol with a UV spectrophotometer, and the number of photons absorbed by the acid generator was calculated as follows. It was determined by the difference in the transmittance of the resist when the acid generator was mixed.
The quantum yields for each acid generator are shown in Table 1 below.

[0049]

[Table 1]

As shown in Table 1, the quantum yield of the acid generator having a naphthalene ring is higher than that of the conventional acid generator containing a benzene ring. Next,
The spectrum of the resist mixed with the above-mentioned acid generator was investigated and is shown in FIG. In FIG. 3, a curve e and a curve f are obtained by adding poly (methyl methacrylate) (PMMA) to DNI · OTf.
And the results of the resists obtained by mixing TNS and OTf at 5 wt% respectively. Curves g and h represent the spectra of conventional resists, curve g is a novolak resist for g-line (cresol novolac + naphthoquinone diazide) system, and curve h is a resist for KrF excimer laser (polyhydroxystyrene resin). + Triphenylsulfonium) was used. The spectrum is standardized per 1 μm of resist thickness.

As shown in FIG. 3, the resists (curves e and f) using the acid generator of the present invention have an absorbance of 1 or less at 193 nm. On the other hand, the conventional resists (curves g and h) have an absorbance at 193 nm close to 30, which means that they cannot be used for ArF excimer laser.

[0052] FIG. 4 shows a resist sensitivity curve using the acid generator of the present invention. Polymethylmethacrylate (PMMA) was used as the resin, and DNI.OTf and TNS.OTf were mixed at a ratio of 5% by weight. For comparison, it is an acid generator used in KrF resists. A sensitivity curve of a resist using diphenyliodonium triflate ( DPI.OTf ) and triphenylsulfonium triflate (TPS.OTf) in the same amount, and polyhydroxystyrene (PHS) which is a resist for KrF excimer laser light.
-Based resin triphenylsulfonium triflate (T
3 shows the sensitivity curve of a typical conventional KrF resist with PS * OTf) added.

As shown in FIG. 4, it is understood that the conventional KrF resist is hardly exposed to ArF excimer laser light. This is 193 for both acid generator and resin.
It means that no light is transmitted because it has no nm transparency. Further, the sensitivity of the resist using the acid generator of the present invention is higher than that of the resist containing the acid generator having a phenyl group. (Example 1) To 10 g of polymethylmethacrylate, 5% by weight of dinaphthyliodonium trifluoromethanesulfonic acid as an acid generator was added and dissolved in 30 g of ethyl cellosolve acetate to prepare a solution containing the photosensitive composition of the present invention. Obtained.

The obtained solution was applied on a silicon wafer by spin coating to a film thickness of 0.65 μm, and then 1
Prebaking was performed at 00 ° C. for 100 seconds. The film thickness of the resist film after prebaking was 0.5 μm. afterwards,
Contact exposure was performed using an ArF excimer laser (wavelength 193 nm), and baking was performed at 90 ° C. for 200 seconds. Further, it was developed in a 0.28N tetramethylammonium hydroxide aqueous solution at 25 ° C. for 60 seconds.

As a result, it was possible to resolve a line-and-space pattern of 0.25 μm with an exposure dose of 130 mJ / cm ² . (Example 2) Trinaphthylsulfonium trifluoromethanesulfonic acid was used in the same amount as the acid generator, except that
In the same manner as in Example 1, a solution containing the photosensitive composition of the present invention was obtained, and prebaking, exposure, and development were performed under the same conditions to form a pattern, and its characteristics were examined.

As a result, a 1.5 μm line-and-space pattern could be resolved with an exposure dose of 540 mJ / cm ² . (Example 3) A solution containing the photosensitive composition of the present invention was obtained in the same manner as in Example 1 except that the same amount of bisnaphthylsulfonylmethane was used as the acid generator, and prebaking and exposure were performed under the same conditions. , And development were performed to form a pattern, and its characteristics were examined.

As a result, a 1.2 μm line-and-space pattern could be resolved with an exposure dose of 560 mJ / cm ² . ( Reference Example ) 1% by weight of dinaphthyl iodonium trifluoromethanesulfonic acid as an acid generator was added to 10 g of a resin in which polyhydroxystyrene was partially substituted with a tertiary-butoxycarbonyl group at 26 mol%, and dissolved in 30 g of ethyl cellosolve acetate. Thus , a solution containing the photosensitive composition was obtained.

The obtained solution was applied on a silicon wafer to a film thickness of 0.96 μm by spin coating, and then 1
Prebaking was performed at 20 ° C. for 100 seconds. The thickness of the resist film after prebaking was 1 μm. Then Kr
Contact exposure was performed with an F excimer laser (wavelength 248 nm), and baking was performed at 95 ° C. for 90 seconds. Further, it was developed in a 0.28N tetramethylammonium hydroxide aqueous solution at 25 ° C. for 60 seconds.

As a result, at an exposure dose of 55 mJ / cm ² ,
A 0.35 μm line-and-space pattern could be resolved. From the results of this example, it is understood that dinaphthyl iodonium trifluoromethanesulfonic acid can be applied to KrF excimer laser light. (Comparative Example 1) Except that the same amount of diphenyliodonium trifluoromethanesulfonic acid was used as the acid generator,
A pattern was formed in the same manner as in Example 1.

As a result, at an exposure dose of 28 mJ / cm ² ,
Although the 0.25 μm line-and-space pattern could be resolved, the 0.225 μm pattern could not be formed. Comparative Example 2 A pattern was formed in the same manner as in Example 1 except that the same amount of triphenylsulfonium trifluoromethanesulfonic acid was used as the acid generator.

As a result, at an exposure dose of 34 mJ / cm ² ,
Although the 0.25 μm line-and-space pattern could be resolved, the 0.225 μm pattern could not be formed. (Comparative Example 3) A pattern was formed in the same manner as in Example 1 except that the same amount of bisphenylsulfonylmethane was used as the acid generator.

As a result, with an exposure dose of 56 mJ / cm ² ,
Although the 0.275 μm line-and-space pattern could be resolved, the 0.225 μm pattern could not be formed.

Therefore, the photosensitive composition of the present invention is
It can be seen that it has high sensitivity and high resolution with respect to the rF excimer laser. As shown in Reference Examples , the photosensitive composition of the present invention has high sensitivity and high resolution also for KrF excimer laser.

[0064]

As described in detail above, according to the present invention,
Since a specific acid generator having a polycyclic aromatic ring is used in the skeleton, the transparency to ultrashort wavelength light such as ArF excimer laser is increased , and therefore, high sensitivity of the resist can be achieved and the resist pattern The resolution can be significantly improved. This pattern forming method is effective in photolithography technology such as fine processing of electronic components.

[Brief description of drawings]

FIG. 1 is a graph showing a spectrum of an acid generator.

FIG. 2 is a graph showing a spectrum of an acid generator.

FIG. 3 is a graph showing a spectrum of a resist composition.

FIG. 4 is a graph showing a sensitivity curve of a resist composition.

[Explanation of symbols]

a ... A curve showing the absorption characteristics of the acid generator of the present invention. b ... Curve showing absorption characteristics of the conventional acid generator. c ... A curve showing the absorption characteristics of the acid generator of the present invention. d ... A curve showing the absorption characteristics of the conventional acid generator. e ... A curve showing absorption characteristics of a resist using the acid generator of the present invention. f ... A curve showing absorption characteristics of a resist using the acid generator of the present invention. g ... A curve showing the absorption characteristics of a resist using a conventional acid generator. h ... A curve showing absorption characteristics of a resist using a conventional acid generator.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Naomi Shinoda, Komukai Toshiba Town, 1st, Komukai Toshiba Town, Saiwai Ward, Kawasaki City, Kanagawa Prefecture (72) Inventor, Makoto Nakase, Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture No. 1 in Research & Development Center, Toshiba Corporation (56) Reference JP-A-6-51519 (JP, A) JP-A-5-150454 (JP, A) JP-A-5-313371 (JP, A) JP-A 8-123031 (JP, A) JP-A-6-317907 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (3)

(57) [Claims] 1. An alkali-soluble resin (a), a compound whose solubility is changed by an acid (b), and a compound (c) which generates an acid upon irradiation with actinic radiation, represented by the following general formula (1): A resin layer containing a photosensitive composition as a main component, which contains at least one compound selected from the group consisting of the compounds represented by, (2), and (3) on the substrate.
Forming a pattern using an ArF excimer laser on the resin layer
Step of performing exposure, step baking resin layer after the exposure, and the
A package including a step of developing the resin layer after baking.
Turn formation method. [Chemical 1] (In the above general formula, A is a polycyclic aromatic ring having at least 5 conjugated double bonds, Z is a chlorine atom, a bromine atom, or an iodine atom. R ¹ is a hydrogen atom; A hydrocarbon group of 6 or less; or a hydrocarbon group substituted by at least one selected from the group consisting of a halogen atom, a nitro group, and a cyano group, and B represents a substituted or unsubstituted at least A polycyclic aromatic ring having 5 conjugated double bonds, a cycloalkane, and a chain alkane, and X is CF ₃ SO ₃ , SbF ₆ ,
BF ₄ or PF ₆ . R ² and R ³ may be the same or different and each is a hydrogen atom; a halogen atom; a nitro group, a cyano group; a hydrocarbon group having 6 or less carbon atoms, a halogen atom, a nitro group, and a cyano group. A hydrocarbon group substituted with at least one selected from the group consisting of groups is shown. ) 2. The composition (c) in the photosensitive composition.
Min is characterized in that B in the general formulas (1), (2), and (3) is a compound represented by AR ^4.
The pattern forming method according to claim 1 . (In addition, A
Is a polycyclic aromatic ring having at least 5 conjugated double bonds, R ⁴ is a hydrogen atom; a halogen atom; a nitro group,
Cyano group: a hydrocarbon group substituted with at least one selected from the group consisting of a hydrocarbon group having 6 or less carbon atoms, a halogen atom, a nitro group, and a cyano group. ) 3.The general formula in the photosensitive composition
Actinic radiation represented by (1), (2), and (3)
Compounds that generate acid by irradiation ofBelowIndication
Expressed by equations (4), (5), and (6)Compound
Is characterized byAccording to claim 1.Pattern formation
Method. [Chemical 2]