JP2000241976A - (co)polymer for resist and resist composition using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a (co)polymer for a resist having high sensitivity in the far UV region and high dry etching resistance comparable to that of an aromatic ring by incorporating specified repeating units and to obtain a resist composition using the (co)polymer. SOLUTION: The (co)polymer for a resist contains repeating units of the formula, wherein R1 is H or a 1-25C hydrocarbon group which may have a substituent. When the (co)polymer is used as a chemically amplified resist, it preferably has an ester group which can be released by acid and the symbol R1 in the formula may be a group which can be released by acid (R1 forms the ester group in combination with a carboxyl group) or R1 may be contained in other repeating units contained in the (co)polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a (co) polymer and a resist composition for a resist used in a lithography technique.

[0002]

2. Description of the Related Art As the size of semiconductor integrated circuits is reduced, the wavelength of exposure light sources in lithography is shortened. Therefore, excimer lithography using a KrF laser or an ArF laser has attracted attention as a next-generation integrated circuit. However, the conventional photoresist cannot be used for excimer lithography because the novolak resin and the photosensitive agent have strong absorption in the far ultraviolet region. For this reason, the development of a new resist material has become an important problem for practical use of excimer lithography.

[0003] In order to solve this problem, there is known a method using a polyvinylphenol resin having higher transparency than novolak resin (RG Taras).
con, E.C. Reichmannis, F .; H
oulihan, A .; Shugard and L.S.
F. Thompson, SPE; Photo Pol
ymers; Principles, Procedures
ses and Materials, 11 (198
8); F. Thompson, E .; Reic
hamanis, F .; Houlihan, and
R. G. FIG. Taracon, Polymer Ma
ter. Sci. Eng. , 60, 137 (19
89); Ito, M .; Ueda and W.W.
P. England, ACS PMSE Prepr
ints, 60, 67 (1989)).

Japanese Patent Application Laid-Open No. 27660/1990 proposes a chemically amplified excimer lithography using a combination of a base polymer and a photoacid generator. In this chemically amplified lithography, a pattern is formed by the mechanism shown in the following reaction formula. That is, the exposed portion is caused by the action of the acid generated from the photoacid generator by the excimer light.
It is based on a mechanism in which a elimination reaction of a protecting group occurs and is solubilized in an alkali developing solution. JP-A-2-27660 discloses a chemically amplified resist using a polymer having a t-butyl carboxylate and capable of obtaining high sensitivity with a small amount of a photosensitive agent.

[0005]

Embedded image

[0006]

However, these polyvinyl phenol-based resists contain a benzene ring which is a kind of aromatic ring in order to obtain dry etching resistance, and even if they are more transparent than novolak resin, It has a strong absorption in the deep ultraviolet region and is completely opaque especially at a wavelength of 193 nm used in ArF excimer lithography, so that the sensitivity is insufficient.

In order to solve this problem, Japanese Patent Laid-Open No. Hei 2-27
Japanese Patent Publication No. 660 improves the transparency at 193 nm by introducing a resin containing poly-t-butyl methacrylate, but in this case, dry etching resistance is reduced.

Therefore, there has not been known a resist resin which is excellent in both sensitivity in a deep ultraviolet region and dry etching resistance when used for a resist.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and is intended for resists having high sensitivity in the deep ultraviolet region and high dry etching resistance comparable to an aromatic ring. A) a polymer and a resist composition using the polymer;

[0010]

According to the present invention, there is provided the following formula (I):
And a (co) polymer for resist containing a repeating unit represented by the formula:

[0011]

Embedded image (In the formula (I), R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms which may have a substituent.) Further, the present invention relates to the resist (co) polymer and And a photoacid generator that generates an acid upon exposure to light.

As a result of extensive studies, the present inventors have found that the resist composition of the present invention has high sensitivity, high dry etching resistance comparable to an aromatic ring, and extremely high transparency in far ultraviolet rays. The present invention has been found to be good.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the (co) polymer for resists of the present invention, the content of the repeating unit of the formula (I) is not particularly limited. Is preferable, and more preferably 20
% Or more, and most preferably 30% or more. The (co) polymer of the present invention has a content of the repeating unit of the formula (I) of 1
It may be a homopolymer of 00%.

In order to use the (co) polymer for resist of the present invention as a chemically amplified resist, it is preferable that the (co) polymer molecule has an ester group which can be eliminated by an acid in the molecule. Even if R ¹ in the formula (I) is a group capable of being eliminated by an acid (in this case, R ¹ is combined with a carboxyl group to form an ester group), the (co) polymer May be included in the other repeating units included in.

R ¹ is a hydrogen atom; linear or branched such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, t-amyl, stearyl, lauryl and 2-ethylhexyl. Alkyl group; aryl group such as phenyl; cyclohexyl, t
-Butylcyclohexyl, dicyclopentadienyl, tricyclodecanyl, isobornyl, adamantyl, 2-
An alicyclic group such as methyl-2-adamantyl; an alkyl group substituted with an alkoxy group such as 1-methoxyethyl or 1-ethoxyethyl; an alkyl group substituted with an aryl group such as benzyl; -Butyrolactone group, β
2-lactone groups such as -methyl-δ-valerolactone group

[0016]

Embedded image And the like.

Among them, hydrogen atom, t-butyl, t-butyl
Amyl, 1-methoxyethyl, 1-ethoxyethyl, 2
-Methyl-2-adamantyl, a γ-butyrolactone group,
β-Methyl-δ-valerolactone groups, isobornyl, adamantyl, tricyclodecanyl, cyclohexyl, and t-butylcyclohexyl are preferred.

Examples of the group which can be removed by an acid include those in which a monovalent hydrocarbon residue obtained by removing hydrogen from a tertiary carbon is ester-bonded together with a carboxyl group. Depending on conditions, even a monovalent hydrocarbon residue obtained by removing hydrogen from secondary carbon may be capable of being eliminated by an acid.

The elimination reaction at this time, for example, in the case of a t-butyl ester group, proceeds as follows and functions as a chemically amplified type.

[0020]

Embedded image Thus, when R ¹ is, for example, t-butyl, t-amyl, 2-
When it is methyl-2-adamantyl or β-methyl-δ-valerolactone, the repeating unit of the formula (I) has a removable group which can function as a chemically amplified type.

On the other hand, other repeating units forming a copolymer together with the repeating units of the formula (I) are not particularly limited, but are preferably those having excellent transparency in a target far ultraviolet region. Examples include a repeating unit obtained by copolymerization from a monomer.

And R ^{1 in} the repeating unit of the formula (I)
Is not a group capable of leaving by an acid, a group capable of leaving by an acid in a repeating unit other than the formula (I) in the copolymer,
For example, t-butyloxycarbonyl, t-amyloxycarbonyl, 2-methyl-2-adamantyloxycarbonyl, and β-methyl-δ-valerolactone-oxycarbonyl are preferably contained.

The molecular weight of the (co) polymer for resist of the present invention is preferably from 3,000 to 500,000, more preferably from 5,000 to 100,000, in consideration of dry etching resistance, solubility and the like. More preferred.

The (co) polymer for resist of the present invention is generally obtained by (co) polymerizing a mixture of monomers containing a monomer represented by the following formula (II). During polymerization, the monomer of formula (II) undergoes a cyclization reaction to form a tetrahydropyran ring structure of formula (I).

[0025]

Embedded image (In the formula (II), R ¹ has the same meaning as in the formula (I).) As the monomer of the formula (II), specifically, dimethyl-
2,2 '-[oxybis (methylene)] bis-2-propenoate, diethyl-2,2'-[oxybis (methylene)] bis-2-propenoate, di (n-propyl) -2,2 '-[oxybis (Methylene)] bis-2
-Propenoate, di (isopropyl) -2,2'-
[Oxybis (methylene)] bis-2-propenoate, di (n-butyl) -2,2 '-[oxybis (methylene)] bis-2-propenoate, di (isobutyl)
-2,2 '-[oxybis (methylene)] bis-2-propenoate, di (t-butyl) -2,2'-[oxybis (methylene)] bis-2-propenoate, di (t
-Amyl) -2,2 '-[oxybis (methylene)] bis-2-propenoate, di (stearyl) -2,2'
-[Oxybis (methylene)] bis-2-propenoate, di (lauryl) -2,2 '-[oxybis (methylene)] bis-2-propenoate, di (2-ethylhexyl) -2,2'-[oxybis ( Methylene)] bis-
2-propenoate, di (1-methoxyethyl) -2,
2 ′-[oxybis (methylene)] bis-2-propenoate, di (1-ethoxyethyl) -2,2 ′-[oxybis (methylene)] bis-2-propenoate, dibenzyl-2,2 ′-[oxybis ( Methylene)] bis-
2-propenoate, diphenyl-2,2 '-[oxybis (methylene)] bis-2-propenoate, dicyclohexyl-2,2'-[oxybis (methylene)] bis-2-propenoate, di (t-butylcyclohexyl)- 2,2 '-[oxybis (methylene)] bis-2
-Propenoate, di (dicyclopentadienyl)-
2,2 '-[oxybis (methylene)] bis-2-propenoate, di (tricyclodecanyl) -2,2'-
[Oxybis (methylene)] bis-2-propenoate, di (isobornyl) -2,2 '-[oxybis (methylene)] bis-2-propenoate, diadamantyl-2,2'-[oxybis (methylene)] bis- 2-propenoate, di (2-methyl-2-adamantyl)-
2,2 ′-[oxybis (methylene)] bis-2-propenoate, di (γ-butyllactone) -2,2′-
[Oxybis (methylene)] bis-2-propenoate, di (β-methyl-δ-valerolactone) -2,2 ′
-[Oxybis (methylene)] bis-2-propenoate and the like.

Further, as a monomer of the copolymer component, a compound of the formula (I)
When R ^{1 in} I) is a removable group, it is not particularly limited as long as it has a copolymerizable polymer group, but in terms of transparency, (meth) acrylic esters and (meth) acrylates are preferred. Acrylic acid, maleic acids and the like are preferred. These copolymer components can be copolymerized by two or more kinds.

The proportion of the monomer of the formula (II) in the monomer mixture at the time of (co) polymerization is such that the content of the repeating unit of the formula (I) in the (co) polymer is a mole of the repeating unit. Preferably the number is at least 10%, more preferably 2%.
0% or more, most preferably 30% or more,
It is preferable to determine the polymerization conditions in consideration of the copolymerization ratio and the like. Further, the monomer of the formula (II) may be homopolymerized.

When R ¹ in the monomer of the formula (II) is not a group capable of being eliminated by an acid, a group capable of being eliminated by an acid is included in the monomer which is a copolymer component. For example, t-butyloxycarbonyl, t-amyloxycarbonyl,
2-methyl-2-adamantyloxycarbonyl, β-
It is preferable that methyl-δ-valerolactone-oxycarbonyl is contained. Such materials include t-butyl (meth) acrylate, t-amyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, β-methyl-δ-valerolactone (meth) acrylate And the like.

As the polymerization method for obtaining the copolymer of the present invention, generally known polymerization methods such as radical polymerization, anion polymerization, group transfer polymerization (G
TP), coordination anionic polymerization and the like.
The polymerization initiator is not particularly limited as long as it has no adverse effect such as side reaction or coloring during polymerization. It can be appropriately selected according to the polymerization mode, polymerization temperature, and polymerization time, and a plurality of types of polymerization initiators can be used together. Examples thereof include azo compounds such as azobisisobutyronitrile and peroxide compounds such as benzoyl peroxide.

The resist composition of the present invention contains at least such a (co) polymer for resist and a photoacid generator. When it is in the form of a resist composition, it contains a solvent that dissolves the (co) polymer for resist.

The photoacid generator is not particularly limited as long as it generates an acid upon exposure, but is preferably a diaryliodonium salt, a triarylsulfonium salt, a triarylselenonium salt, or a substituted aryldiazonium salt.
BF as a counter anion of these salts
_{^{4 -, SbF 6 -, AsF}} 6 -, PF 6 - are preferable.

The amount of the photoacid generator used in the present invention is in the range of 0.01 to 100% by weight, preferably 0.1 to 10% by weight, based on the (co) polymer.

The solvent for use as the resist composition can be selected in consideration of coating performance, drying speed, and the like. Examples thereof include cyclohexane, propylene glycol monomethyl ether acetate, and ethyl lactate.

The resist composition using the (co) polymer for resist of the present invention has excellent transparency in the deep ultraviolet region and excellent dry etching resistance in the repeating unit of the formula (I). Especially 150 nm to 350 nm
Suitable for photoresist exposed to light in the wavelength range of

[0035]

The present invention will be described more specifically with reference to the following examples. Various evaluations of the examples and comparative examples were performed as follows.

(1) Evaluation of dry etching resistance A resist composition (resist solution) was spin-coated on a silicon substrate, and heated at 100 ° C. and 60 ° C. using a hot plate.
After baking for 2 seconds to dry and form a film, reactive ion etching was performed using a parallel plate type device, and the amount of film loss was measured by a light interference type film thickness measuring device to obtain an etching rate. Etching conditions are Ar gas or CF.
_{Using 4} gases, pressure 0.02 torr (flow rate 100s
ccm) at 200W. The etching rate at that time was obtained by standardizing NPR (Novolak Resist: Nagase Sangyo) as a reference.

(2) Evaluation of alkali solubility The resist composition (resist solution) was spin-coated on a silicon substrate, and heated at 100 ° C. and 60 ° C. using a hot plate.
Bake for 2 seconds. The applied film thickness was 0.5 μm. After exposing this resist film using an ArF lighter, post-exposure bake (PEB) was performed on a hot plate at 100 ° C. for 60 seconds. The development was performed by immersing in NMD-3 (tetramethylammonium hydride (TMAH) 2.38% aqueous solution: Tokyo Ohka) for 60 seconds. As a result, a pattern having a good shape was evaluated as ○ (good), and a pattern having a poor shape was evaluated as ×.
(Poor).

(3) Evaluation of Light Transmittance Each polymer was press-molded into a flat plate having a thickness of 1 mm, a length of 60 mm and a width of 60 mm, and the transparency at 193 nm was measured with a UV measuring instrument.

Reference Example 1 824 g (4 mol) of tricyclodecanyl acrylate (Fancryl 513A, manufactured by Hitachi Chemical Co., Ltd.) in a 2 L flask, purity: 75%
Paraformaldehyde (160 g: 4 mol), 1,
4-Diazabiccyclo [2,2,2] octa
ne (60 g: 0.53 mol), p-methoxyphenol (616 mg), t-butyl alcohol (120
g) was reacted at 80 ° C. for 24 hours while performing air bubbling. After the completion of the reaction, the reaction solution was poured into 3 L of methanol and stirred for 30 minutes. Then, the mixed solution was allowed to stand at room temperature overnight, and di (tricyclodecanyl) -2,2 ′-[oxybis (methylene)] bis-2 as white crystals was obtained.
And 650 g (74% yield) of propenoate (hereinafter abbreviated as TCDD).

Reference Example 2 In a 2 L flask, t-
Amyl acrylate 568 g (4 mol), purity 75%
Paraformaldehyde (160 g: 4 mol), 1,
4-Diazabiccyclo [2,2,2] octa
ne (60 g: 0.53 mol), p-methoxyphenol (616 mg), t-butyl alcohol (120
g) was reacted at 80 ° C. for 24 hours while performing air bubbling. After completion of the reaction, ether was added, and
Washed with N hydrochloric acid. After the organic phase was dried over anhydrous sodium sulfate, the solvent was distilled off, and the residue was purified with a silica gel column to give di (t-butyl) -2,2′-colorless transparent liquid.
[Oxybis (methylene)] bis-2-propenoate (hereinafter abbreviated as TAD) 464 g (yield 78%) and (t-amyl) -α-hydroxymethyl acrylate (hereinafter abbreviated HOTA) 121 g (yield 17) 0.5%).

[Example 1] Toluene 480 m as a solvent
1 g of TAD, TCDD4
5 g and HOTA 8 g were added and dissolved. Azobisisobutyronitrile (AIBN) 10 is used as an initiator in this solution.
g was added and the mixture was stirred for 40 minutes while purging with nitrogen. Then 8
The mixture was heated to 0 ° C. to start the polymerization, and the polymerization was performed for 5 hours.

This reaction solution was put into a large amount of hexane to precipitate a copolymer, which was filtered and washed with hexane. After vacuum drying, this was dissolved again in toluene and reprecipitated with hexane. This was repeated three times to obtain 82 g of a powdery copolymer (yield: 82%). This copolymer was press-molded and the transparency was evaluated.

Next, the synthesized copolymer (weight average molecular weight: 16,000) was dissolved in propylene glycol monomethyl ether acetate (PGMEA) so that the solid content concentration became 20% by weight. Next, 2% by weight of triphenylsulfonium triflate was dissolved in the copolymer to obtain a resist composition. Using this resist composition, dry etching resistance and alkali solubility were evaluated. Table 1 shows the evaluation results.

Example 2 Toluene 480 m as a solvent
1 g of TAD, TCDD4 in a 1 L flask containing
6 g, β-methyl-δ-valerolactone 8 methacrylate
g was added and dissolved. Thereafter, polymerization was performed in the same manner as in Example 1,
After the treatment, 84 g (yield 84%) of a powdery copolymer was obtained. This polymer was press-molded and the transparency was evaluated.

Next, a resist composition was obtained by repeating Example 1 except that the thus synthesized copolymer (weight average molecular weight: 21,000) was used. Using this resist composition, dry etching resistance and alkali solubility were evaluated. Table 1 shows the evaluation results.

[Example 3] Toluene 480m as a solvent
1 g of TAD, TCDD4 in a 1 L flask containing
6 g and 8 g of methacrylic acid were added and dissolved. Thereafter, polymerization and treatment were performed in the same manner as in Example 1 to obtain a powdery copolymer 87.
g (87% yield). This copolymer was press-molded and the transparency was evaluated.

Next, a resist composition (varnish) was obtained by repeating Example 1 except that the thus synthesized copolymer (weight average molecular weight 23,000) was used. Using this resist composition, dry etching resistance and alkali solubility were evaluated. Table 1 shows the evaluation results.

Comparative Example 1 A resist composition was prepared in the same manner as in Example 1 except that NPR (Novolak Resist: manufactured by Nagase & Co., Ltd.) was used as a copolymer when preparing the resist composition. Obtained. Using this resist composition, dry etching resistance and alkali solubility were evaluated. NPR was press-molded and its transparency was evaluated. Table 1 shows the evaluation results.

[Comparative Example 2] Polymethyl methacrylate (Acrypet VH: manufactured by Mitsubishi Rayon Co., Ltd.) was used in place of the copolymer used in preparing the resist composition.
A resist composition was obtained in the same manner as in Example 1. Using this resist composition, dry etching resistance and alkali solubility were evaluated. Acrypet VH was press-molded and its transparency was evaluated. Table 1 shows the evaluation results.

[0050]

[Table 1]

[0051]

According to the present invention, there is provided a (co) polymer for resist having high sensitivity in a deep ultraviolet region and high dry etching resistance comparable to an aromatic ring, and a resist composition using the same. be able to.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Fujiwara 20-1, Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Satoshi Tokimitsu 20-1, Miyukicho, Otake City, Hiroshima Prefecture F-term in Central Research Laboratory of Mitsubishi Rayon Co., Ltd. (Reference) 2H025 AA00 AA01 AA09 AB16 AC04 AC08 AD03 BE00 BE10 CB06 CB41 CB43 CB52 4J100 AE71P AE83P AJ02Q AJ09Q AL03Q BA11P BA15P BA16P BA20P BC04P BC09P BC43BC

Claims (8)

[Claims] 1. A (co) polymer for resist containing a repeating unit represented by the following formula (I). Embedded image (In the formula (I), R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms which may have a substituent.) 2. A (co) polymer for resist containing a tetrahydropyran structure in a part of a main chain obtained by (co) polymerizing a monomer mixture containing a monomer represented by the following formula (II). Embedded image (In the formula (II), R ¹ has the same meaning as described above.) 3. The (co) polymer for a resist according to claim ^1, wherein said R ¹ is a group capable of leaving by an acid. 4. The (co) polymer for a resist according to claim 3, wherein R ¹ is a monovalent hydrocarbon residue obtained by removing hydrogen from tertiary carbon. 5. The method according to claim 1, wherein R ¹ is a hydrogen atom, t-butyl,
Amyl, 1-methoxyethyl, 1-ethoxyethyl, 2
-Methyl-2-adamantyl, a γ-butyrolactone group,
The (co) polymer for resist according to claim 1 or 2, which is a group selected from the group consisting of a β-methyl-δ-valerolactone group, isobornyl, adamantyl, tricyclodecanyl, cyclohexyl, and t-butylcyclohexyl. 6. The (co) polymer for a resist according to claim 1, comprising a repeating unit represented by the formula (I) and a repeating unit having a group capable of leaving by an acid. 7. The resist according to claim 2, which is a copolymer of a monomer mixture containing the monomer represented by the formula (II) and a monomer having a group capable of leaving by an acid. (Co) polymer. 8. A resist composition comprising the (co) polymer for a resist according to claim 1 and a photoacid generator that generates an acid upon exposure.