JP2000019732A - Polymer for photosensitive composition and pattern forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive composition having excellent light transmittance, excellent dry etching resistance, high reaction efficiency by an acid catalyst, alkali solubility and excellent adhesion to a substrate, and surface roughness. Provided is a pattern forming method capable of obtaining an excellent pattern shape with a small size. SOLUTION: The weight average molecular weight Mw and the number average molecular weight Mn obtained by subjecting a vinyl monomer having an alicyclic skeleton or a naphthalene skeleton and / or a (meth) acrylate monomer to living polymerization are obtained. Ratio Mw
Exposure of a photosensitive composition comprising a copolymer having a molecular weight distribution given by / Mn of 1.0 to 1.4 and a photoacid generator, and a photosensitive material using the same with short-wavelength light Pattern forming method for developing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, in particular, a thin-film magnetic head for a large-scale integrated circuit (LSI), a hard disk drive, and the like, and a photosensitive composition used for microfabrication of a liquid crystal display. It relates to pattern formation.

[0002]

2. Description of the Related Art In the field of semiconductor integrated circuit devices such as LSIs, thin-film magnetic heads such as hard disk drives, and electronic components that require various types of fine processing such as liquid crystal displays, fine processing technology using lithography technology is applied. Photoresists are widely used as photosensitive materials. In particular, recently, with the diversification, multifunctionality, and high density of electronic devices, finer resist patterns are required. One measure for improving the ability to form a fine pattern is to shorten the wavelength of an exposure light source. For this purpose, for example, an ArF excimer laser (193) is used.
nm) or a fifth harmonic (213 nm) of a YAG laser as an exposure light source has been developed.

[0003] However, with respect to such extremely short wavelength light, many substances have too large absorbances to resolve resist patterns. Specifically, in the conventional resist material, since light in this wavelength range is transmitted only to a depth of about 1/30 μm, a resist material having a special composition is required. Therefore, development of a resist material having high sensitivity and high resolution to the light source and having etching resistance for fine processing is desired.

[0004] As such a resist material, for example, a copolymer of a polymerizable compound having an aliphatic hydrocarbon skeleton and a polymerizable compound having alkali solubility, as shown in JP-A-4-39965, etc., is used. A resist composed of coalescing is used. This resist has the advantage of being excellent in optical transparency and having resistance to dry etching, but as far as the present inventors know, the alkali solubility was insufficient. This is thought to be due to copolymerization of a polymerizable compound having extreme properties such as an alicyclic compound showing no alkali solubility and a carboxylic acid-containing compound showing strong alkali solubility. Can be For this reason, during development, only the easy-to-dissolve parts are dissolved and the dissolution is likely to be uneven, and the reproducibility is low, or cracks and surface roughness are likely to occur due to partial dissolution in unexposed areas, development on the substrate interface It seems to cause a problem that the liquid is soaked and the pattern is easily collapsed. Furthermore, the copolymer is liable to undergo phase separation, and the solubility in the solvent is non-uniform, the coating property is poor, and the selection of the coating solvent is limited.

[0005] Further, there has been reported a resist comprising a conjugated complex aromatic ring as disclosed in Japanese Patent Application No. 5-4953. Such a resist has the best dry etching resistance among the resist materials currently known, alkali solubility, solubility in a solvent,
Adhesion to the substrate is comparable to that of conventional phenolic resins. However, the transparency to light in the above-mentioned wavelength region is inferior to the former, so that it is difficult to form a pattern with high accuracy.

In response to this, development of a resist material which exhibits high light transmittance to the exposure light source and has excellent alkali solubility for fine processing has been desired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has high light transmittance to short-wavelength ultraviolet rays, excellent alkali solubility, and adhesion to a substrate. Another object is to provide a resist composition exhibiting dry etching resistance.

[0008]

The present invention has been made in view of the above problems. The challenge is that
By providing a photosensitive composition suitable as a resist material, which has high sensitivity and high resolution with respect to ultra-short wavelength ultraviolet light, particularly ArF excimer laser, and has high stability through a pattern forming process. is there.

It is known that a radical polymerization of an acrylic resin-based resist can provide a pattern of 0.15 μmL / S. Further, by introducing an aliphatic cyclic hydrocarbon into the main chain as disclosed in JP-A-9-325498, good dry etching resistance is obtained.

[0010] These resist materials are obtained by radical polymerization. In radical polymerization, the molecular weight can be controlled by controlling the amount of the polymerization initiator and the polymerization temperature. This makes it possible to resolve a fine pattern. However, it is difficult to control the molecular weight distribution by radical polymerization. For this reason, the obtained resin often shows a Poisson distribution and a wide molecular weight distribution. It has been theoretically elucidated that even polymers having exactly the same composition have different solubility in a developer when the molecular weight is different (details will be described later). For this reason, if the molecular weight distribution is wide, resins having different solubility in a developer are mixed, and the dissolution tends to be uneven.

Therefore, we separated by molecular weight by gel permeation chromatography (GPC) to obtain a resin with a narrow molecular weight distribution. As a result, it was found that when a resin having a uniform molecular weight was used, a vertical pattern was obtained at the interface with the substrate, and the roughness of the resist surface was reduced. It has been found that when the molecular weights are uniform, the pattern shape is improved.

However, separating a resin obtained by radical polymerization by GPC or the like requires a complicated operation, and the yield is often as low as 10% or less.

[0013]

[Summary of the Invention] <Summary> The photosensitive composition of the present invention comprises a vinyl monomer having an alicyclic skeleton or a naphthalene skeleton, and / or a (meth) acrylate ester. Weight average molecular weight Mw and number average molecular weight M obtained by living polymerization
The molecular weight distribution given by the ratio Mw / Mn to n is 1.0 to
Comprising the copolymer of 1.4 and a photoacid generator;
It is characterized by the following.

The pattern forming method of the present invention is characterized by including the following steps. (1) Ratio of weight average molecular weight Mw to number average molecular weight Mn obtained by living polymerization of a vinyl monomer having an alicyclic skeleton or a naphthalene skeleton and / or a (meth) acrylate monomer. A photosensitive material obtained by applying a photosensitive composition comprising a copolymer having a molecular weight distribution given by Mw / Mn of 1.0 to 1.4 and a photoacid generator on a substrate. Preparation process, (2)
Exposing the photosensitive material imagewise with actinic radiation having a wavelength of 220 nm or less; and (3) developing the exposed photosensitive material with an alkaline developer.

<Effects> According to the present invention, there is provided a photosensitive composition having excellent light transmittance, excellent dry etching resistance, high reaction efficiency with an acid catalyst, excellent alkali solubility, and excellent adhesion to a substrate. Is done.

According to the pattern forming method of the present invention, a pattern having a small surface roughness and an excellent pattern shape is formed.

[Specific Description of the Invention] The polymer contained in the photosensitive composition of the present invention is a vinyl monomer having an alicyclic skeleton or a naphthalene skeleton, and / or (meth)
A copolymer having a molecular weight distribution of 1.0 to 1.4, which is obtained by living polymerization of an acrylate ester and has a ratio Mw / Mn of a weight average molecular weight Mw to a number average molecular weight Mn.

The copolymer has the following general formula (1)
It is preferable that at least one of the monomers represented by (3) is contained as a component and the monomer is obtained by living polymerization.

Embedded image Here, R ¹ , R ¹¹ , R ¹² and R ²¹ are respectively
A group selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, and a halogen, which may be the same or different. Specific examples include hydrogen, a methyl group, an ethyl group, a methoxy group, an ethoxy group, chlorine, fluorine, a cyano group, and others. R ² , R ¹³ , and R ^{22 each} have 1 to 1 carbon atoms such as hydrogen, a methyl group, and an ethyl group.
5, an alkyl group, a cycloolefin group, a cycloolefin containing oxygen in the ring, and a cyclic ether group, which may be the same or different. Specific examples include hydrogen, a methyl group, an ethyl group, a cyclohexyl group, a 1-isopropyl-4-methylcyclohexyl group, a furanyl group, a pyranyl group, an adamantyl group, and others.

Further, R ² , R ¹³ and R ²² may be each independently substituted with a hydroxyl group, a carboxyl group and others.

Z in the formula (2) is a simple and / or bridged alicyclic skeleton, for example, a cyclohexyl skeleton, a norbornyl skeleton, an isobornyl skeleton, an adamantyl skeleton, a mentyl skeleton, a tricyclodecanyl skeleton, a bicyclopentane skeleton, And others.

More specifically, the cycloolefin group may be a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring or a cyclooctane ring having a bridged hydrocarbon chain, spiroheptane, spiro Spiro rings such as octane, norbornene rings,
Terpene rings such as adamantane ring, bornene ring, menthyl ring, and menthane ring, tujang, sapinen, tujjon, karan, karen, pinan, norpinan, bornan,
Examples include steroids such as fencan, tricyclene, and cholesteric ring, tanjusan, digitaloids, camphor ring, isocamphor ring, sesquiterpene ring, sandton ring, diterpene ring, triterpene ring, and steroid saponins.

At this time, specifically, a polymerizable compound having an alicyclic skeleton, a polymerizable compound whose alkali solubility is changed by an acid, a polymerizable compound having an alkali-soluble group, and a hydroxyalkyl ester are added to the side chain. A polymer in which an acrylic polymerizable compound is combined is used as the alkali-soluble resin of the photosensitive composition of the present invention.

In the present invention, the weight average molecular weight Mw
Mn can be measured by the light scattering method, the X-ray small angle scattering method, and the osmotic pressure method, the boiling point raising method, the viscosity method and the like.
More simply, Mw and Mn in terms of polystyrene are determined by gel permeation chromatography (GPC).
Can be measured. In the specification of the present application, the measured values by GPC are described unless otherwise specified.

Polymers having these structures can be obtained by radical polymerization, but by using polymers having a narrow molecular weight distribution obtained by living polymerization as in the present invention,
It was found that a good pattern with little footing could be obtained on the contact surface with the substrate without surface roughness.

The radical polymerization method is a simple method as a polymerization method, and is widely used as a method for polymerizing a resist resin. However, it is difficult to control the molecular weight and generally has a broad molecular weight distribution. Another disadvantage is that the reaction is determined by the lifetime of the radical, and the reaction is completed in a relatively short time after the generation of the radical, so that the monomer is susceptible to steric hindrance. It is well known that the acrylic resin, main chain alicyclic resin, and naphthalene-containing resin, which are particularly problematic in the present application, all have very bulky monomers, and it is particularly difficult to control the molecular weight. The present inventor has also made considerable efforts in this regard, but acrylic resins, main-chain alicyclic resins, and naphthalene-containing resins are not easily reproducible due to the influence of molecular weight and molecular weight distribution despite the exact same composition. There were many. In order to solve this, the active site of the polymerization reaction can be utilized for a long time.
It has been found that it is effective to use living polymerization in which two reactions are not completed in an instant. On the other hand, since the proportion of the benzene ring and the like in the space is small, novolak resins and PHS resins, which have been representatives of conventional resist resins, are not so difficult to control the molecular weight and molecular weight distribution by radical polymerization. .

That is, when living polymerization is carried out to obtain the above polymer, Mw / Mn having a narrow molecular weight distribution becomes 1.0 to 1.0.
About 1.4 resin is obtained. At this time, butyllithium, diphenylhexyllithium, fluorenyllithium, 1,1,
Alkyl lithiums such as diphenyl-3-methylpentyl lithium and α-methylstyrene lithium, alkali metal reagents such as sodium benzophenone ketyl, sodium naphthalene, α-methylstyrene sodium, biphenyl sodium, fluorenyl sodium and benzyl sodium, benzyl sodium And dibenzo-18-
Organic cesiums such as cumyl cesium and fluoresceium, alkoxides or amides of sodium and potassium, crown ether complexes of sodium-cesium, butyl magnesium bromide, phenyl magnesium bromide, naphthyl magnesium bromide, vinylbenzyl magnesium chloride, such as crown ether complexes And Grignard reagents such as cyclohexylmagnesium bromide, and aluminum complexes of porphyrin.

As a polymerization solvent, tetrahydrofuran,
Examples thereof include cyclic ethers such as tetrahydrobiran, aliphatic hydrocarbons such as n-hexane, dimethoxyethane, cyclohexane, and dioxane; aromatic compounds such as benzene, toluene, and xylene; and alkyl halides such as methylene chloride and chloroform.

In such a polymer, the amount of the acrylic polymerizable compound having a functional group in the side chain is preferably about 20 to 80 mol% of the monomer to be polymerized. 20m
ol% or less, the dry etching resistance is reduced, and 80 m
If the amount is more than 0%, the change in solubility with respect to the alkali developer becomes insufficient, and it may be impossible to form a pattern. However, when combined with a general polymerizable compound having an alicyclic skeleton, the amount of the acrylic polymerizable compound may be 20 mol% or less to the extent that the dry etching resistance is not hindered.

The photosensitive composition of the present invention preferably has excellent transparency at 193 nm, which is the wavelength of an ArF excimer laser.
Preferably, the absorbance at 93 nm is 2 or less per micron.

Here, in order to reduce the absorbance at 193 nm of this polymer, it is desirable to use a polymerizable compound having the following combination of an acidic substituent and an alicyclic compound. Includes alkyl groups containing ketone oxime structures, such as propanone oxime and propanal oxime groups, hydroxyiminopentanone, demethylglyoxime, dicarboxylic acid imides such as succinimide and pyrrolidinedione, and N-hydroxysuccinimide structures Alkyl groups, substituents having a dicarbonylmethylene structure such as cyclopentene 1,3 dione, acetylacetone, and 3methyl-2,4 pentanedione; carboxyl groups, substituents having a sulfamide structure, and alkyl groups having a polysubstituted sulfonylmethane structure , An alkyl group containing a thiol such as hexanethiol, an alcohol containing an enol structure such as hydroxycyclopentenone,
Examples include a substituent having a furfuryl alcohol structure and an alkyl group having an amic acid structure. Here, in order to lower the absorbance, it is preferable that a monocyclic aromatic group is not contained as a substituent.

However, such a compound has poor solubility in an organic solvent and very poor solubility in an alkali developing solution. If an attempt is made to increase the solubility in an alkali developing solution, the adhesion to the substrate may be reduced, and the pattern may be peeled off. In addition, the dissolution rate differs depending on each polymer chain due to the molecular weight distribution and does not dissolve uniformly, so that a good pattern shape may not be obtained.

It is known that the resolution can be improved by reducing the molecular weight of the resin used as the resist, but it is expected that if the molecular weight is too small, there will be a problem in the strength of the resist. You. It has also been found that the molecular weight distribution is also a major factor. Here, what kind of dissolution behavior is taken when there is a distribution of molecular weight is theoretically examined as follows.

First, in order to predict the dissolution of the resin, the free energy of mixing must be considered. The free energy of mixing of the polymer system and the solution is expected as follows. ΔG ₁ / RT = (1 / N) φ1nφ + (1-φ) 1n (1-φ) + χφ (1-φ) (1) where N is the degree of polymerization (proportional to the molecular weight), and φ is the fraction of the resin. (In this case, since it is in the developing solution, a considerably small φ <0.0
1) and χ are interaction parameters (the higher the solubility, the less soluble the resin and the developer).

From equation (1), the larger the value of χ, the less the solubility. In the case of the resist, thermodynamically, this χ becomes smaller due to a chemical change caused between the processes of exposure and post-exposure bake (hereinafter referred to as PEB), so that it becomes easier to dissolve in the developer.

At this time, if the molecular weight is different, N changes, so the first term of the equation (1) changes. Specifically, as the molecular weight increases, the first term decreases, and the first term is always negative, so that the free energy of mixing ΔG ₁ of the system increases. If ΔG ₁ is larger than 0, it will not be dissolved, so that it is expected that the high molecular component will not be dissolved and only the low molecular component will be dissolved.

As a result, in a resin having a wide molecular weight distribution, there is a high possibility that non-uniform dissolution of the resist will occur. Therefore, a monodisperse resin having a narrow molecular weight distribution is desired.

From the following considerations, a polymer containing a carboxylic acid has a higher monodispersion effect than a polymer based on phenol or alcohol.

In the formula (1), the polymer is considered as a single system. However, when the polymer is considered as a copolymer of two or more kinds of monomers, the same idea as the formula (1) can be obtained. You can think of free energy in the body. ΔG ₂ / RT = (1 / N ₁ ) φ1nφ + (1 / N ₂ ) (1-φ) 1n (1-φ) + χ ₁₂ φ (1-φ) (2)

The relationship between solubility parameter and chi ₁₂ between the components of the monomer 1 and 2 is expressed as follows. χ ₁₂ = (v ^* / RT) | δ ₁ −δ ₂ | ² v ^* is a molar volume, and δ ₁ is a solubility parameter of the monomer component 1 in the copolymer.

Generally, a chemically amplified resist uses two or more types of monomer components as a copolymer. The solubility parameters are generally small for non-polar ones and large for high polarity ones. For example, PHS frequently used in a chemically amplified resist is about 10 (cal 0.5 / cm ^1.5 ), and one protected with t-butyl exhibits a value of about 8.5.

On the other hand, a resin such as an acrylic resin or a main chain alicyclic resin which is promising as a resist for ArF has a value of 12 for polyacrylic acid, 11.2 for polymethacrylic acid, and 12 for polynorbornenecarboxylic acid. . When this is protected with t-butyl, the value becomes about 8 to 9.

From the above, it can be seen that the acrylic resin and the main chain alicyclic resin of the resist for ArF have a larger difference in the solubility parameter between the protected part and the unprotected part than the mainstream PHS with KrF. Understand. Further, when this result is applied to the equation (2), even if the composition ratios of the protected part and the unprotected part are completely the same when the molecular weights are different (in the equation (2), N ₁ : N _Although the ratio of ₂ is the same, but N ₁ + N ₂ is different), it can be seen that the free energy of the system is different. This indicates that the solubility in the developer is different. The broad molecular weight distribution means that many different types of free energy are included.Acrylic resins and main-chain alicyclic resins are more susceptible to molecular weight distribution than PHS resins, and have a smaller molecular weight distribution. It can be seen that the system is more stable. ArF resist KrF resist resin Acrylic resin or main chain alicyclic resin PHS δ 11-12 of unprotected part δ 8-9 of protected part Difference of 8-9 δ Large Small Free energy due to molecular weight Large Small Energy Effect of molecular weight distribution

As a result, it is expected that surface roughness during development will be reduced by narrowing the molecular weight. Also, this effect is
It can be seen that the resin for F is higher.

The influence of the molecular weight also appears at the time of etching, and the resin having a reduced molecular weight has less surface roughness. ArF
It is expected that the resist film thickness will be further reduced in the generations in which resists for the mainstream will be used for higher resolution, and the influence of surface roughness will have a greater effect on device performance.
In a resist for rF, the effect of preventing surface roughness during etching due to narrow dispersion is extremely large.

To further consider the effect of molecular weight, consider a simplified system as follows. In order to consider the molecular weight distribution, in the case of a polymer whose molecular weight is doubled by simplification, ΔG ₃ = (（N) φ1nφ + (1-φ) 1n (1-φ) + χφ (1-φ) (3) . It should be noted here that the first term is always negative, so that ΔG ₁ <ΔG ₃ (4).

It is assumed here that the protecting group is decomposed at a certain rate by the acid. This decomposition rate is considered to be independent of the molecular weight. (1) In the formula (3), only χ changes and becomes smaller due to the decomposition of the protecting group. If the rate of decomposition by the acid does not depend on the molecular weight, χ in equation (1) and equation (3)
Are the same.

Since the dissolution of the resin starts when ΔG becomes negative, the dissolved portion is ΔG <0, and the portion which is not dissolved and remains as a pattern is ΔG> 0. Therefore, if the system has no molecular weight distribution, ΔG = 0 is the contour of the resist pattern. However, when there is a molecular weight distribution, the contour of the resist pattern is in a state of ΔG ₁ <0 <ΔG ₃ (5), and only ΔG _{1 is} negative, that is, only those having a low molecular weight are dissolved. When the molecular weight distribution further widens, ΔG ₁ << 0 << ΔG ₃ (6), and non-uniform dissolution of several tens nm order starts. This makes it difficult to form a fine pattern. For this reason,
It can be seen that broadening the molecular weight distribution is not thermodynamically good for pattern formation.

However, for dissolution and development, reptation (slip-through) time due to entanglement (square of molecular weight) of polymers of resin and diffusion to developer (square of radius of gyration, that is, 1.2 times molecular weight). Since a kinetic element such as the squared value is involved, a constant dissolution rate is guaranteed when a low molecular weight component is added.

Thus, two or more kinds of narrow molecular weight resins polymerized by living polymerization are mixed, and a compound whose solubility in a developing solution is changed by an acid generated from a photosensitive agent which generates an acid by irradiation with far ultraviolet rays. Alternatively, it is understood that a photosensitive composition containing a group is preferable.

Here, in order to avoid thermodynamic nonuniformity and to add a low molecular weight element as a kinetic element, the composition may be such that ΔG ₁ = 0 = ΔG ₂ . This is achieved by reducing χ in equation (3) compared to equation (1).
Therefore, it can be seen that it is better to combine a low molecular weight component having a high protection rate or a large number of alicycles with a high molecular weight component having a low protection rate.

Thus, when two or more resins polymerized by living polymerization are mixed, the low molecular weight resin has a higher content of a dissolution inhibiting group or a dry etching resistant group than the high molecular weight resin. It can be seen that a photosensitive composition containing a compound or a group whose solubility in a developing solution is changed by an acid generated from a photosensitive agent that generates an acid by irradiation with far ultraviolet rays is preferable.

The alkali-soluble polymer as described above is
The polymer alone has no photosensitivity. So, for example,
A photosensitive composition such as a compound that generates an acid upon irradiation with actinic radiation (hereinafter, referred to as a photoacid generator) and / or a dissolution inhibitor is blended to form a photosensitive composition. A photoacid generator containing no aromatic ring (for example, CMS-10)
5, DAM-301, NDI-105 and EPI-105
(Manufactured by Midori Kagaku)), a dissolution inhibitor (adamantane-te)
rt-butyl ester or tert-butyl cholic acid) can be used as a photosensitive composition, but in this case, there is a drawback such as reduced heat resistance, Photoacid generators that are compounds are more desirable.

Examples of the photoacid generator that can be used in the present invention include the following. (A) triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalene sulfonate, diphenyliodonium triflate, diphenyliodonium virensulfonate, diphenyliodonium dodecylbenzenesulfonate, bis (4-tert-butylphenyl) iodonium triflate Rate, screw (4-t
tert-butylphenyl) iodonium dodecylbenzenesulfonate, bis (4-tert-butylphenyl) iodoniumnaphthalenesulfonate, bis (4-
(tert-butylphenyl) iodonium hexafluoroantimonate, (hydroxyphenyl) benzenemethylsulfonium toluenesulfonate, 1- (naphthylacetomethyl) thiolanium triflate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium triflate, dicyclohexyl (2-oxo) Cyclohexyl) sulfonium triflate, dimethyl (2-
Oxocyclohexyl) sulfonium triflate, S
Iodonium salts, sulfonium salts, phosphonium such as-(trifluoromethyl) dibenzothiophenium trifluoromethanesulfonic acid, Se- (trifluoromethyl) dibenzothiophenium trifluoromethanesulfonic acid, I-dibenzothiophenium trifluoromethanesulfonic acid Onium salts such as salts, diazonium salts and pyridinium salts, (b) 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-4-sulfonic acid ester of 2,3,4,4-tetrahydrobenzophenone 1,2-Naphthoquinonediazide-4- of 1,1,1-tris (4-hydroxyphenyl) ethane
1,3-diketo-2-diazo compounds such as sulfonic acid esters, diazoketone compounds such as diazobenzoquinone compounds and diazonaphthoquinone compounds, (c) 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane, Haloalkyl group-containing hydrocarbon compounds such as phenyl-bis (trichloromethyl) -S-triazine and naphthyl-bis- (trichloromethyl) -S-triazine; halogen-containing compounds such as haloalkyl group-containing heterocyclic compounds; -Trisphenacylsulfone, mesitylphenacylsulfone, bis (phenylsulfonyl)
Sulfone compounds such as β-ketosulfone such as methane and β-sulfonylsulfone.

In this case, when these additives are compounds having a monocyclic aromatic ring, it is not preferable to mix them in a large amount because the transparency is remarkably reduced. On the other hand, when the aromatic is a conjugated polycyclic aromatic compound, the transparency is improved, which is more preferable.

The conjugated complex aromatic ring means that a plurality of aromatic rings have a conjugated and defined molecular structure. Here, conjugate refers to a state in which every other double bond is aligned in a state close to a plane.

Examples include naphthalene ring, anthracene ring, phenanthrene ring, bilen ring, naphthacene ring, chrysene ring, 3,4 benzophenanthrene ring, perylene ring,
Examples include a pentacene ring and a bicene ring. A pyrrole ring, a benzofuran ring, a benzothiophene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, an indazole ring, a chromene ring, a quinoline ginnoline ring, a phthalazine ring, a quinazoline ring, a dibenzofuran ring, a carbazole ring, an acridine ring, and a phenanthate Lysine ring, phenanthroline ring, phenazine ring, thianthrene ring, indolizine ring, naphthyridine ring, purine ring, buteridine ring, fluorene ring and the like correspond to this. In particular, when the aromatic ring is selected from a naphthalene ring, an anthracene ring, and a phenanthrene ring, transparency and dry etching resistance are high, which is desirable. These skeletons can be introduced into a main chain skeleton or a side chain skeleton of an acid generator or a dissolution inhibitor forming a resist.

Specifically, examples of the photoacid generator include an onium salt having a naphthalene skeleton or a dibenzothiophene skeleton, a sulfonate, a sulfonyl, and a sulfamide compound. As a more specific example, N
AT-105, NDS-105 and other sulfonium salts having a nafretane ring, NDI-106 and other naphthalene-containing chlorinated triazines, sulfonimides such as naphthalidyl triflate (Midori Chemical), and onium salts of dibenzothiophene derivatives (Daikin Chemical), naphthalene bisulfone and the like. The addition amount of these compounds to the alkali-soluble resin is desirably at least 0.1% or more and less than 20%. If the amount of the photoacid generator added to the photosensitive composition is less than 0.1%, the sensitivity may be lowered, and conversely, 20%
Attention should be paid to the above because the coating film performance may be significantly reduced.

Since the polymerizable compound of the present invention is decomposed by using the acid generated from the photoacid generator as a catalyst, the addition of a compound having a dissolution inhibiting group or a dissolution inhibitor is not essential.
However, a compound having a dissolution inhibiting group or a dissolution inhibitor may be added in order to increase the difference in dissolution rate between the exposed part and the unexposed part. Such compounds include:
See, for example, U.S. Patent Nos. 4,491,628 and 460310.
Compounds described in the specifications of JP-A No. 1 and JP-A-63-27829 can be used. Among these, the aromatic ring is preferably a condensed polycyclic aromatic ring.
Alternatively, a compound having a carboxylic acid or a phenolic hydroxyl group in the condensed polycyclic aromatic ring skeleton can be used as long as a part or all of the hydroxy terminal is substituted with an acid-decomposable protecting group. For example, the protective group includes tert-butyl ester, tert-butyl carbonate, tetrahydropyranyl group, acetal group and the like. More specific examples of such compounds include naphthalene and anthracene, tert-butyl carbonate of polyhydroxy compound, tert-butyl carbonate of naphtholphthalein, quinazaline and quinizarin, tetra-butyl carbonate of naphthol novolak resin, and the like. Is done.

The addition amount of these compounds to the photosensitive composition is desirably at least 3% by weight and less than 40% by weight. When the amount of these compounds added to the photosensitive composition is 3
When the amount is less than 40% by weight, the resolution may be reduced. On the contrary, when the amount is more than 40% by weight, the coating film performance or the dissolution rate may be remarkably reduced. Usually between 10 and 30% by weight is more desirable. In addition,
When such a compound is an alkali-soluble polymer compound, it can also serve as the above-described alkali-soluble resin.

Examples of the substituent which can be decomposed by an acid include the following. (A) Esters such as t-butyl ester, isopropyl ester, ethyl ester, methyl ester, benzyl ester, tetrahydropyranyl ester, tetrahydrofuranyl ester, methoxyethoxy methyl ester, 2-trimethylsilylethoxymethyl ester, 3-oxocyclohexyl ester, Isobornyl esters and other (II) ethers such as tetrahydropyranyl ether, t-butoxycarbonyl ether, t-butoxymethyl ether, 4-pentenyloxymethyl ether, tetrahydropyranyl ether, tetrahydrothiopyranyl ether, 3- Bromotetrahydropyranyl ether, 1-methoxycyclohexyl ether, 4-methoxytetrahydropyranyl ether, 4-methoxy Lahydrothiopyranyl ether, 1,4-dioxan-2-yl ether, tetrahydrofuranyl ether, tetrahydrothiofuranyl ether, 2,3,3a, 4,5,6,7,7a-octahydro-7,8,8- Trimethyl-4,7-methanobenzofuran-2-yl ether, t-butyl ether, and (c) alkoxy carbonates such as t
-Butoxycarbonate, methoxycarbonate, ethoxycarbonate and others, (d) silyl ethers such as trimethylsilyl ether, triethylsilyl ether, triphenylsilyl ether, triisopropylsilyl ether, dimethylisopropylsilyl ether, diethylisopropylsilyl ether , Dimethylsexylsilyl ether, t-butyldimethylsilyl ether, di-t-butylsilyl ether, 1,3-
1 ', 1', 3 ', 3'-tetraisopropyldisiloxanylidene ether, tetra-t-butoxydisiloxane-1,3-diylidene ether, and others,
(E) silyl esters such as trimethylsilyl ester, triethylsilyl ester, isopropyldimethylsilyl ester, di-t-butylmethylsilyl ester, (f) acyclic acetal or acyclic ketal,
For example, methylene acetal, ethylidene acetal, methoxymethylene acetal, ethoxymethylene acetal, 2,2,2-trichloroethylidene acetal, I
-T-butylethylidene ketal, isopropylidene ketal (acetonide), and other (g) cyclic acetals or cyclic ketals, cyclopentylidene ketal, cyclohexylidene ketal, cycloheptylidene ketal, dimethyl acetal, dimethyl ketal,
Bis-2,2,2-trichloroethyl acetal, bis-2,2,2-trichloroethyl ketal, diacetyl acetal, diacetyl ketal, 1,3-dioxane, 5-methylene-1,3-dioxane, 5, 5-dibromo-1,3-dioxane, 1,3-dioxolan,
4-bromomethyl-1,3-dioxolan, 4,3′-
Butenyl-1,3-dioxolan, 4,5-dimethoxymethyl-1,3-dioxolan, and others,
(H) orthoesters such as dimethoxymethylene orthoester, 1-methoxyethylidene orthoester, 1-ethoxyethylidene orthoester, 1,2-
Dimethoxyethylidene orthoester, 1-N, N-dimethylaminoethylidene orthoester, 2-oxacyclopentylidene orthoester, and others,
(Li) silyl ketene acetals such as trimethylsilyl silyl ketene acetal, triethylsilyl ketene acetal, t-butyldimethylsilyl ketene acetal, and (nu) cyanohydrins such as O
-Trimethylsilyl cyanohydrin, O-1-ethoxyethyl cyanohydrin, O-tetrahydropyranyl cyanohydrin, and others, and (l) oxazoles such as oxazole, 2-alkyl-1,3-oxazoline, 4-alkyl-5-oxo-1 , 3-oxazoline, 5-alkyl-4-oxo-1,3-dioxolane, and others.

More preferably, t-butyl ester such as t-butyl methacrylate, t-butyl-3-naphthyl-2-propenoate, trimethylsilyl methacrylate and tetrahydropyranyl methacrylate, trimethylsilyl ester and tetrahydropyranyl ester are provided in the side chain. Examples thereof include a photosensitive composition in which a photoacid generator and, if necessary, a dissolution inhibitor are added to an acrylic or vinyl compound copolymer.

When the photosensitive composition contains a dissolution inhibitor, it is not always necessary to introduce a dissolution inhibiting group into the resin component. Further, a vinyl compound having an alkali-soluble group, such as methacrylic acid, which gives alkali solubility as a copolymer composition of the resin component, may be copolymerized.

A terpolymer or higher polymer containing a dissolution-inhibiting group and an alkali-soluble group simultaneously can provide two functions of alkali-solubility and dissolution-inhibiting properties with one resin component. In this case, the proportion of the dissolution inhibiting group in the polymer is preferably about 10 to 80 mol%. If the amount is less than 10 mol%, the dissolution inhibiting function may not be exhibited, and the unexposed portion may be dissolved, and the pattern may not be resolved. On the other hand, if it exceeds 80 mol%, the adhesiveness becomes extremely poor, forming a pattern becomes difficult, and the hydrophobicity of the photosensitive composition becomes too strong, so that the developer repels and the pattern may not be formed. .

The photosensitive composition of the present invention is prepared by dissolving, in a solvent, an alkali-soluble resin, a compound whose solubility is changed by the action of an acid, and a compound which generates an acid by irradiation with actinic radiation. It is adjusted by adjusting. Examples of the solvent used here include (a)
Ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, and others; (b) cellosolve solvents such as methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, and others; and (c) ester solvents such as acetic acid Examples include ethyl, butyl acetate, isoamyl acetate, γ-butyl lactone, methyl 3-methoxypropionate, and others. Further, depending on the photosensitive composition, dimethylsulfoxide, dimethylformaldehyde, N-methylpyrrolidine, or the like may be used to improve solubility.

Further, propionic acid derivatives such as methyl methyl propionate, lactate esters such as ethyl lactate, which have recently been attracting attention as alternative solvents to low toxicity solvents,
Solvents such as propylene glycol monomethyl ether acetate can also be used.

The above-mentioned solvents may be used alone or in the form of a mixture. In addition, these solvents may contain an appropriate amount of an aliphatic alcohol such as xylene, toluene, or isopropyl alcohol.

In the photosensitive composition of the present invention, in addition to the components described above, a surfactant as a coating modifier, an adhesion promoter, a basic substance, an epoxy resin, Incorporation (e.g., polymethyl methacrylate, polymethyl acrylate, propylene oxide-ethylene oxide copolymer, polystyrene, and others), or a dye as an antireflection agent may be included.

Next, a method for forming a resist pattern using the photosensitive composition of the present invention will be described with reference to examples of a positive resist.

First, the photosensitive composition dissolved in the above-mentioned solvent is applied on a substrate by a spin coating method or a dipping method, and then applied at a temperature of 200 ° C. or lower, more preferably 70 to 12 ° C.
Dry at 0 ° C. to form a resist film. As the substrate used here, for example, a silicon wafer, a silicon wafer having various insulating films and electrodes formed on its surface, a wiring, a blank mask, a GaAs, an AlGaAs, etc.
Group semiconductor wafers. Also,
Chrome or chromium oxide deposition mask, aluminum deposition substrate,
An IBPSG coated substrate, PSG coated substrate, SOG coated substrate, carbon film sputtered substrate, or the like may be used.

Next, the resist film is irradiated with actinic radiation through a predetermined mask pattern to perform pattern exposure. As a light source used for this pattern exposure, here, as the actinic radiation, for example, i of a low-pressure mercury lamp
Rays, h-rays, g-rays, xenon lamp light, various ultraviolet rays such as deep ultraviolet rays such as excimer laser light such as KrF and ArF, X-rays, electron rays, gamma rays, neutron rays, ion beams, etc. The effects of the present invention are best exhibited in exposure using an ArF excimer laser.

Subsequently, the resist film after pattern exposure is
About 50 to 180 ° C., preferably about 60 to 120 ° C., by heating on a hot plate or in a heating furnace or by infrared irradiation,
Heat treatment (baking) as appropriate. By the baking for the heat treatment, the acid generated by the exposure acts as a catalyst in the exposed portion of the resist film and reacts with a compound having a substituent which is decomposed by the acid. When the temperature is less than 50 ° C,
There is a possibility that the acid generated by the photoacid generator may not sufficiently react with the compound having a substituent that is lucky by the acid.
If the temperature exceeds 80 ° C., excessive decomposition and curing may occur over the exposed and unexposed portions of the resist film.

Thus, the compound having a substituent which is decomposed by an acid is converted into an alkali-soluble compound by decomposing the substituent. In some cases, the same effect as the above-described post-exposure bake may be obtained by leaving the substrate at room temperature for a sufficiently long period of time.

Next, the exposed portion of the resist film is selectively dissolved and removed by developing the baked resist film using an alkaline solution according to an immersion method, a spray method or the like, thereby obtaining a desired pattern. Here, examples of the alkaline solution used as a developer include an aqueous solution of an inorganic alkali such as an aqueous solution of sodium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, an aqueous solution of tetramethylammonium hydroxide, and an aqueous solution of trimethylhydroxyethylammonium hydroxy. Organic alkali aqueous solution such as an aqueous solution of sodium chloride, and those obtained by adding alcohols and surfactants to these. The substrate and the resist film (resist pattern) after the development process are usually subjected to a rinsing process using water or the like, and further dried.

It should be noted that any other steps other than the above steps may be added. For example, a flattening formation step as a base of the resist film, a pretreatment step for improving the adhesion between the resist film and the substrate or the base, and an antireflection film for preventing reflected light from the substrate and obtaining a good resist pattern. An application step, a rinsing step of removing the developing solution with water after development of the resist film, a re-irradiation step before dry etching, and the like can be appropriately performed.

Since the photosensitive composition of the present invention has an extremely good alkali solubility, the resist pattern using the composition does not crack or roughen the surface and does not collapse. Moreover, a pattern can be formed with high reproducibility. The obtained pattern has extremely good resolution. For example, a fine pattern of about 0.15 μm can be faithfully transferred to an exposed substrate or the like by dry etching using this resist pattern as an etching mask.

The pattern formation using the resist composition of the present invention is specifically described as follows.

[0077]

EXAMPLES Polymerization Example 1 0.043 mol of menthyl acrylate and 0.057 mol of tetrahydropyranyl methacrylate were mixed.
Freezing and deaeration were performed three times at a liquid nitrogen temperature under an argon atmosphere. This was used as a monomer stock solution.

The reaction was performed in a Schlenk tube under a nitrogen atmosphere, and the transfer of the reagent was performed using a syringe. Toluene and THF were refluxed over sodium and then distilled under a nitrogen atmosphere. The monomer was purified through an activated basic alumina column and an activated molecular sieve column.

2,6-di-t-butylphenol (Al
drich, 99 +%) (8.87 g, 40.2 mm
ol) was dissolved in 25 ml of dry toluene. While stirring, a toluene solution of Al (i-Bu) ₃ (Al
drich, 1M) (8.03 g, 40.4 mmol)
l) was added using a syringe. The reaction was heated to about 50 ° C. Generation of butane gas was observed. Solution volume 5
0 ml and used as a 0.8 M solvent for the polymerization reaction.

A pentane solution of t-BuLi (Aldri
(Ch. 1.7M), the TH of diphenylacetic acid was used before use.
The concentration was determined by titration with the F solution. The reaction vessel was dried by framing under vacuum. A predetermined amount of the toluene solution was mixed with toluene (40 ml) and cooled to -5 ° C. To this is added a predetermined amount of t-BuLi pentane solution,
The complex was allowed to react for several minutes to form. The monomer solution was added at such a rate that the temperature of the system did not rise. When the monomer was added, the polymerization system turned yellow, but this color disappeared when the polymerization was completed. The polymerization reaction was stopped by adding methanol, the product was recovered by precipitating in hexane, filtered through a glass filter, and the solid content was vacuum-dried at 60 ° C. for 1 day.

10 g of the polymer obtained here was dissolved in 40 g of tetrahydrofuran, and a small amount of hydrochloric acid was added thereto to add 2.5 g of the polymer.
Was added and the mixture was stirred at 60 ° C. for 4 to 5 hours. The reaction solution was dropped into hexane and reprecipitated. The mixture was filtered through a glass filter, and the solid content was vacuum-dried at 60 ° C. for 1 day. Thus, a base resin from which tetrahydrofuran was removed was obtained.

The weight average molecular weight is 1 in terms of polystyrene.
5000. Mw / Mn was 1.1.

5 g of the polymer obtained above was redissolved in 20 g of tetrahydrofuran, dihydrofuran was added in an amount of 1.2 mol times the carboxylic acid in the polymer, a small amount of hydrochloric acid was added dropwise, and a little heat was generated. Do not go up 3
The reaction was carried out at room temperature for an hour. After that, the mixture was left overnight to attain a sufficient equilibrium state, reprecipitated in hexane, filtered through a glass filter, and dried under vacuum at 60 ° C. for 3 days.

A small amount of the obtained polymer was dissolved in chloroform-form and the composition ratio was examined by NMR. As a result, it was found that 43 mol% of menthyl acrylate, 34 mol% of tetrahydropyranyl methacrylate and 23 mol% of methacrylic acid were obtained.

Polymerization Example 2 A resin was obtained in the same manner as in Polymerization Example 1, except that the amount of the pentane solution of t-BuLi was 1.2 times. The weight average molecular weight was 11,000 in terms of polystyrene. Mw
/ Mn was 1.1. When the composition ratio was examined by NMR, it was 43 mol% of menthyl acrylate, 34 mol% of tetrahydropyranyl methacrylate, and 23 mol% of methacrylic acid.

Polymerization Example 3 The same method as in Polymerization Example 1 was used except that the amount of the pentane solution of t-BuLi was 1.2-fold and dihydrofuran was added in an amount of 1.5 mol times the carboxylic acid in the polymer. To obtain a resin. The weight average molecular weight was 11,000 in terms of polystyrene. Mw / Mn was 1.1. When the composition ratio was examined by NMR, it was 43 mol% of menthyl acrylate, 39 mol% of tetrahydropyranyl methacrylate, and 18 mol% of methacrylic acid.

Polymerization Example 4 The monomer composition was changed to 0.048 mol of menthyl acrylate,
Tetrahydropyranyl methacrylate 0.052mol
A resin was obtained in the same manner as in Polymerization Example 1, except that the amount of the pentane solution of t-BuLi was 1.2 times. The weight average molecular weight was 11,000 in terms of polystyrene. Mw / Mn was 1.1. The composition ratio is menthyl acrylate 48 mol%, tetrahydropyranyl methacrylate 34 mol% and methacrylic acid 18 mol%
Met.

Polymerization Example 5 The monomer composition was changed to 0.038 mol of adamantyl acrylate.
1, 0.062 m of tetrahydropyranyl methacrylate
A resin was obtained in the same manner as in Polymerization Example 1 except that the amount was changed to ol. The weight average molecular weight is 14,000 in terms of polystyrene.
Met. Mw / Mn was 1.1. The composition was adamantyl acrylate 38 mol%, tetrahydropyranyl methacrylate 34 mol% and methacrylic acid 28
mol%.

Polymerization Example 6 The monomer composition was changed to 0.033 mol of menthyl acrylate,
A resin was obtained in the same manner as in Polymerization Example 1, except that 0.034 mol of t-butyl methacrylate and 0.033 mol of tetrahydropyranyl methacrylate were used. The weight average molecular weight was 14,000 in terms of polystyrene. M
w / Mn was 1.1. Composition is 33 mol% of menthyl acrylate, 34 mol of t-butyl methacrylate
% And methacrylic acid 33 mol%.

Polymerization Example 7 A resin was obtained in the same manner as in Polymerization Example 1, except that the monomer composition was changed to 0.025 mol of vinylnaphthalene, 0.020 mol of menthyl acrylate, and 0.055 mol of tetrahydropyranyl methacrylate. The molecular weight was 16,000 in terms of polystyrene. Mw / Mn is 1.1
Met. The composition was 25 mol% of vinyl nafretane, 20 mol% of menthyl acrylate, 33 mol% of tetrahydropyranyl methacrylate and 22 m of methacrylic acid.
ol%.

Polymerization Example 8 The monomer composition was changed to tetrahydropyranylcyclohexene-3.
-A base resin was obtained in the same manner as in Polymerization Example 1, except that carboxylic acid was 0.060 mol and tetrahydropyranyl methacrylate was 0.040 mol. The weight average molecular weight was 12000 in terms of polystyrene. Mw
/ Mn was 1.15. A resist resin was obtained in the same manner as in Polymerization Example 1, except that an equimolar amount of dihydropyran was dropped into the monomer unit of the base resin. Tetrahydropyranyl was introduced in an amount of 42 mol%.

Polymerization Example 9 A resin was obtained in the same manner as in Polymerization Example 1, except that the monomer was changed to 0.1 mol of cyclohexene-3-tetrahydropyranylcarboxylic acid and an equimolar amount of dihydropyran was added dropwise.
The weight average molecular weight was 8,000 in terms of polystyrene. Mw / Mn was 1.15. Tetrahydropyranyl was introduced in an amount of 46 mol%.

Polymerization Example 10 A resin was obtained in the same manner as in Polymerization Example 1, except that the monomer was changed to 0.1 mol of 5-norbornene-2-tetrahydropyranylcarboxylic acid and an equimolar amount of dihydropyran was added dropwise. Was. The weight average molecular weight was 7000 in terms of polystyrene. Mw / Mn was 1.2. Tetrahydropyranyl was introduced in an amount of 45 mol%.

Polymerization Example 11 A resin was obtained in the same manner as in Polymerization Example 1 except that the monomer was changed to 0.045 mol of 5-isobornene-2-tetrahydropyranylcarboxylic acid and an equimolar amount of dihydropyran was added dropwise. Was. The weight average molecular weight is 600 in terms of polystyrene.
It was 0. Mw / Mn was 1.2. Tetrahydropyranyl was introduced in an amount of 42 mol%.

Embedded image

Comparative Polymerization Example 1 0.043 mol of menthyl acrylate, 0.034 mol of tetrahydropyranyl methacrylate and 0.023 mol of methacrylic acid were added to tetrahydrofuran (TH
F) dissolved in 20 g of azobisbutyronitrile (AIB)
N) 0.0125 mol was added as a polymerization initiator. Freezing and deaeration were performed three times at a liquid nitrogen temperature under an argon atmosphere. This is carried out at 60 ° C. for 30 minutes in an argon atmosphere.
Allowed to react for hours. 2 ml of methanol was added to the reaction solution to stop the reaction. While stirring 250 g of hexane, the reaction solution was dropped drop by drop to perform reprecipitation. The mixture was filtered through a glass filter, and the solid content was dried under vacuum at 60 ° C. for 3 days. The molecular weight was 15,000 in terms of polystyrene. Mw
/ Mn was 1.7.

The resin and the comparative polymer obtained in the above polymerization examples were mixed with the following photoacid generators and subjected to an exposure experiment.

Example-1 [Effect of Molecular Weight Distribution] The resin obtained in Polymerization Example-1.
To 0 g, 0.05 g of triphenylsulfonium trifluoromethanesulfonic acid (hereinafter referred to as TPS.OTf) as a photoacid generator was added, and dissolved in 4.2 g of propylene glycol monomethyl ether acetate (PGMEA) to obtain a resist solution. (Resist 1)

Similarly, the resin obtained in Comparative Polymerization Example 1
1.0 g of TPS.OTf as a photoacid generator in 0.0 g
5 g was added and dissolved in 4.2 g of propylene glycol monomethyl ether acetate (PGMEA) to obtain a resist solution. (Resist 2) The obtained two kinds of resist solutions were spin-coated on a silicon wafer at 3000 rpm for 30 seconds by spin coating. Thereafter, a pre-exposure bake was performed at 120 ° C. for 90 seconds on a hot plate. The thickness of the resist was 0.5 μm. to this,
Exposure was performed using ArF excimer laser light (wavelength: 193 nm) to pattern lines and spaces. The exposure apparatus is a Nikon ArF exposure apparatus (NA = 0.55, σ =
0.7) was used.

After baking after exposure at 100 ° C. for 180 seconds, development was carried out at 25 ° C. for 60 seconds in a 0.04N tetramethylammonium hydroxide aqueous solution. As a result, the exposed portion of the resist film was selectively dissolved and removed to form a positive pattern. A cross-sectional view of the obtained pattern was as shown in FIG. Both resists
A 0.15 μm line & space was resolved.

[0100]

From this, it can be seen that the photosensitive composition of the present invention did not cause a decrease in sensitivity. At this time, the shape of the resist was improved because the resist of the present invention had a more vertical wall surface than the comparative example.

Example 2 [Effect of Mixing Two Resins with Narrow Molecular Weight Distribution] 1.0 g of the resin obtained in Polymerization Example 1 was added with T as a photoacid generator.
0.05 g of PS / OTf was added, and 4.2 g of propylene glycol monomethyl ether acetate (PGMEA) was added.
And a resist solution was obtained. (Resist 1)

The composition of Resist 1 was 0.5 g of the resin obtained in Polymerization Example-1 and 0.5 g of the resin obtained in Polymerization Example-2.
A resist solution was obtained in the same manner as in Resist 1, except that the resist solution was changed to a mixture. (Resist 3)

The composition of the resist 1 was 0.5 g of the resin obtained in Polymerization Example-1 and 0.5 g of the resin obtained in Polymerization Example-3.
A resist solution was obtained in the same manner as in Resist 1, except that the resist solution was changed to a mixture. (Resist 4)

The composition of the resist 1 was 0.5 g of the resin obtained in Polymerization Example-1 and 0.5 g of the resin obtained in Polymerization Example-5.
A resist solution was obtained in the same manner as in Resist 1, except that the resist solution was changed to a mixture. (Resist 5)

These resists were coated, baked before exposure, exposed, baked after exposure, and developed in the same manner as in Example 1 to form a positive pattern.

The dry etching resistance of each sample was measured. The measurement condition is the etching gas CF
₄ , 30 sccm, 0.1 mtorr, 150 W. The results obtained are as summarized in Table 2.

Table 2 Resist 6 Resist 7 Resist 8 Resist 9 Resolution 0.15 μm 0.15 μm 0.14 μm 0.15 μm Sensitivity 4.4 mJ 4.0 mJ 4.7 mJ 4.8 mJ Etching rate 1.0 1.00 .97 0.92

As described above, when two kinds of resins having a narrow molecular weight distribution are mixed, sensitivity is increased when a resin having the same composition and a low molecular weight is mixed, and a resin having a low molecular weight and a high degree of dissolution of a dissolution inhibiting group is obtained. It can be seen that the resolution performance is improved by mixing, and the dry etching resistance is improved by mixing those having a low molecular weight and a high degree of dry etching resistance.

Example 3 To 1.0 g of the resin obtained in Polymerization Examples-5 to 11 was added 0.05 g of TPS.OTf as a photoacid generator, and propylene glycol monomethyl ether acetate (PGME
A) The resist solution was dissolved in 4.2 g to obtain a resist solution.

Table 3 Resist Resin Sensitivity mJ Resolution Other μmL / S Resist 6 Polymerization Example-5 7.0 0.15 Resist 7 Polymerization Example-6 12.5 0.17 PEB140 ° C Resist 8 Polymerization Example-7 17 .8 0.15 Resist 9 Polymerization Example -8 12.0 0.15 Resist 10 Polymerization Example -9 11.2 0.15 Resist 11 Polymerization Example -10 21.4 0.16 Resist 12 Polymerization Example -11 19.8 0.15

As a result, not only acrylic resin but also ArF
It is understood that a resist pattern can be formed by reducing the molecular weight of the resist.

Comparison with polyhydroxystyrene A resist for KrF synthesized by living anion polymerization (resin obtained by converting polyhydroxystyrene to 23% t-butoxycarbonyl, Mw = 6000, Mw / Mn = 1.
1) (Resin A) and a resin polymerized by radical polymerization (resin obtained by converting polyhydroxystyrene into 23% t-butoxycarbonyl, Mw = 5700, Mw / Mn = 1.9) (Resin B) in PGMEA by 20% The two solutions were dissolved and spin-coated on a silicon wafer at 3000 rpm for 30 seconds by spin coating. Thereafter, baking was performed at 120 ° C. for 90 seconds on a hot plate.
It was immersed in a 0.21N aqueous solution of tetramethylammonium hydroxide at 25 ° C. for 60 seconds to erode the surface.

Similarly, the resins obtained in Polymerization Example-1 and Comparative Polymerization Example-1 were subjected to the same steps, and the surface condition of the resins was observed by an atomic force microscope (AFM) for surface roughness. Table 4 Resin Molecular weight distribution Correlation length Resin A (PHS) 1.1 1.0 nm Resin B (PHS) 1.9 2.5 nm Polymerization example-1 (acryl) 1.1 1.0 nm Comparative polymerization example-1 (acryl) ) 1.7 5.0 nm

The correlation length indicates the degree of the unevenness when the occurrence probability of the unevenness is considered to follow an exponential function. The larger the correlation length, the larger the unevenness. It can be seen that the acrylic system has a high effect of narrow dispersion. This is because, as pointed out in the present application, the energy state of acrylic is more unstable.

[0116]

According to the present invention, there is provided a photosensitive composition having excellent light transmittance, excellent dry etching resistance, high reaction efficiency with an acid catalyst, excellent alkali solubility, and excellent adhesion to a substrate. As described above, and according to the pattern forming method of the present invention, a pattern having an excellent pattern shape with a small surface roughness is formed as described in the section of the Summary of the Invention.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a pattern formed by a resist (a) according to the present invention and a resist (b) according to a comparative example.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/027 H01L 21/30 502R (72) Inventor Toru Gogouchi Toshiba-cho, Komukai-ku, Kawasaki-shi, Kanagawa Prefecture 1 Toshiba Research and Development Center, Inc. (72) Inventor Takeshi Okino Toshiba-cho, Komukai-ku, Kawasaki-shi, Kanagawa 1 In Toshiba Research and Development Center, Inc. (72) Naomi Shinoda Kawasaki-shi, Kanagawa Komukai Toshiba-cho, Sachi-ku 1 F-term in the Toshiba Research and Development Center (reference) BK001 EN136 EQ016 EU046 EU186 EV046 EV166 EV216 EV236 EV246 EV296 EW176 FD156 FD206 GP03 4J011 QB01 SA79 SA83 SA84 SA87 UA01 VA02 WA01

Claims (6)

[Claims] (1) a vinyl monomer having an alicyclic skeleton or a naphthalene skeleton, and / or a (meth) acrylate monomer obtained by living polymerization.
Ratio Mw / M between weight average molecular weight Mw and number average molecular weight Mn
A photosensitive composition comprising a copolymer having a molecular weight distribution given by n of 1.0 to 1.4 and a photoacid generator. 2. A copolymer comprising at least one of the following general formulas (1) to (3) as a monomer:
The photosensitive composition according to claim 1, which has been subjected to living polymerization. Embedded image Here, R ¹ , R ¹¹ , R ¹² and R ²¹ are respectively
A group selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, and a halogen, which may be the same or different, and R ² , R ¹³ , and R ^{22 each} represent a hydrogen, a methyl group, an ethyl group And C 1 to C 15 alkyl groups, cycloolefin groups, cycloolefins containing oxygen in the ring, and cyclic ether groups, which may be the same or different, and Z represents an alicyclic skeleton. 3. The copolymer further comprises (1) a group having a group which changes the solubility of the copolymer in a developer by an acid, or (2) a compound which changes the solubility in a developer by an acid. The photosensitive composition according to claim 1. 4. A weight average molecular weight Mw and a number average obtained by subjecting a vinyl monomer having an alicyclic skeleton or a vinyl monomer having a naphthalene skeleton and / or a (meth) acrylate ester to living polymerization. Molecular weight M
The molecular weight distribution given by the ratio Mw / Mn to n is 1.0 to
The composition according to claim 1, comprising two or more types of the copolymer of 1.4.
4. The photosensitive composition according to any one of 3. 5. The copolymer according to claim 4, wherein, of the two or more copolymers, a lower molecular weight copolymer has a higher content of a dissolution inhibiting group or a dry etching resistant group than a higher molecular weight copolymer. Photosensitive composition. 6. A pattern forming method, comprising the following steps. (1) Ratio of weight average molecular weight Mw to number average molecular weight Mn obtained by living polymerization of a vinyl monomer having an alicyclic skeleton or a naphthalene skeleton and / or a (meth) acrylate monomer. A photosensitive material obtained by applying a photosensitive composition comprising a copolymer having a molecular weight distribution given by Mw / Mn of 1.0 to 1.4 and a photoacid generator on a substrate. Preparation process, (2)
Exposing the photosensitive material imagewise with actinic radiation having a wavelength of 220 nm or less; and (3) developing the exposed photosensitive material with an alkaline developer.