JP3022412B2 - Negative photoresist material and pattern forming method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photolithography process for manufacturing a semiconductor device, and more particularly to a negative photoresist material and a pattern forming method suitable for lithography using light having a wavelength of 220 nm or less as exposure light. .

[0002]

2. Description of the Related Art In the field of the manufacture of various electronic devices requiring fine processing on the order of half microns as represented by semiconductor devices, there is an increasing demand for higher density and higher integration of devices. Therefore, the demand for photolithography technology for forming fine patterns is becoming more and more severe.

As one of means for miniaturizing a pattern, there is a method of shortening the wavelength of exposure light used in forming a resist pattern.
In the mass production process of DRAM (25 μm or less), use of a shorter wavelength KrF excimer laser beam (wavelength = 248 nm) as an exposure light source instead of i-line (wavelength = 365 nm) is being actively studied.

However, in order to manufacture a DRAM having a degree of integration of 1 Gbit or more that requires a finer processing technique (processing dimension of 0.18 μm or less), a light source having a shorter wavelength is required. ArF excimer laser light (wavelength =
193 nm) has recently been considered [Donald C. et al. Hoffer et al., Journal of Photopolymer Science and
Technology (Journal of Photopolymer Science and
Technology), 9 (3), pp. 387-397 (19
1996)].

[0005] Therefore, development of a negative photoresist corresponding to photolithography using ArF excimer laser light is desired. When developing this resist for ArF exposure, the gas used as the material for laser oscillation has a short life, and the laser device itself is expensive.
It is necessary to improve the cost performance of the laser. For this reason, there is a high demand for high sensitivity in addition to high resolution corresponding to miniaturization of processing dimensions.

As a method for increasing the sensitivity of a resist, a chemically amplified resist utilizing a photoacid generator as a photosensitive agent is well known. For example, a typical example is disclosed in
No. 27660 discloses triphenylsulfonium.
A resist comprising a combination of hexafluoroarsenate and poly (p-tert-butoxycarbonyloxy-α-methylstyrene) is described. Such a chemically amplified resist is currently widely used as a resist for a KrF excimer laser [for example, Hiroshito, C.I. Grant Wilson, American Chemical
Society Symposium Series, 242 volumes, 1
1 to 23 (1984)].

A feature of the chemically amplified resist is that a proton acid generated by light irradiation from a photoacid generator as a contained component causes an acid-catalyzed reaction with a resist resin or the like by heat treatment after exposure. In this way, the photoreaction efficiency (reaction per photon) is significantly higher than that of a conventional resist having less than 1.

At present, most of resists to be developed are of the chemical amplification type, and the use of a chemical amplification mechanism is indispensable for the development of a high-sensitivity material corresponding to a shorter wavelength of an exposure light source.

[0009]

SUMMARY OF THE INVENTION However, ArF
In the case of lithography using short-wavelength light of 220 nm or less typified by excimer laser light, a negative-type photoresist for forming a fine pattern has new characteristics that cannot be satisfied with conventional materials, that is, exposure light of 220 nm or less. , High transparency and dry etching resistance are required.

Conventional negative photoresist materials for g-line (wavelength = 438 nm), i-line (wavelength = 365 nm), and KrF excimer laser light (wavelength = 248 nm) mainly consist of a resin and a cross-linking agent. For example, a resin having an aromatic ring in a structural unit such as a novolak resin or poly (p-vinylphenol) is used, and the etching resistance of the resin can be maintained by the dry etching resistance of the aromatic ring. As the crosslinking agent, for example, an azide compound such as 2,6-di (4′-azidobenzal) -4-methylcyclohexanone or 3,3′-diazidophenylsulfone, or a methylolmelamine resin is used. However, the resin having an aromatic ring has extremely strong light absorption for light having a wavelength of 220 nm or less. Therefore, most of the exposure light is absorbed by the resist surface, and the exposure light does not transmit to the substrate, so that a fine resist pattern cannot be formed. Therefore, the conventional resin cannot be directly applied to photolithography using short-wavelength light of 220 nm or less. Therefore, it does not contain an aromatic ring and has etching resistance,
There is a strong need for photoresist materials that are transparent for wavelengths below 20 nm.

ArF excimer laser light (wavelength = 193n)
m) as a polymer compound having transparency and resistance to dry etching, a copolymer having an adamantyl methacrylate unit, which is an alicyclic polymer [Takechi et al., Journal of Photopolymer Science.
And Technology (Journal of Photopolymer Scie
5 (No. 3), pp. 439-446 (1992)] and copolymers having isobornyl methacrylate units [RD Allen et al., Journal of Photopolymer Science and Technology.・ Technology (Journal of Photopolymer Science and Tech)
nology), volume 8, (4), pages 623 to 636 (199).
5 years) and Vol. 9 (No. 3), pp. 465-474 (19)
1996)]. Previously, the present inventors also
JP-A-7-2542324 and JP-A-8-259 disclose photoresist materials satisfying these requirements.
No. 626 discloses a resin developed.

However, these photoresist compositions are:
A chemically amplified positive photoresist comprising a resin having an acid-decomposable group and a photoacid generator, which gives a positive pattern, and a negative photoresist satisfying the above requirements has not been developed.

Accordingly, the present invention provides a highly sensitive negative photoresist material excellent in transparency and etching resistance, which is used for lithography using exposure light having a wavelength of 220 nm or less, particularly exposure light having a wavelength of 180 to 220 nm. The purpose is to: It is another object of the present invention to provide a pattern forming method using the negative photoresist material.

[0014]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, completed the present invention.

The present invention provides a negative photoresist comprising at least a polymer represented by the general formula (1) having a weight average molecular weight of 1,000 to 500,000 and a photoacid generator which generates an acid upon exposure. About the material.

[0016]

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(In the above formula, R ¹ , R ³ , R ⁵ are a hydrogen atom or a methyl group, R ² is a divalent hydrocarbon group having 7 to 18 carbon atoms having a bridged cyclic hydrocarbon group, R ⁴ Is a hydrocarbon group having an epoxy group, and R ⁶ is a hydrogen atom or carbon atom 1
Represents up to 12 hydrocarbon groups. Also, x, y and z are respectively x + y + z = 1, 0 <x <1, 0 <y <1, 0 ≦ z
<An arbitrary number that satisfies 1. In addition, the present invention has a weight average molecular weight represented by the general formula (2) of 1,000 to 5,000.
A negative photoresist material comprising at least a polymer of No. 00, a photoacid generator that generates an acid upon exposure, and a polyfunctional epoxy compound.

[0018]

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(In the above formula, R ¹ and R ⁵ are a hydrogen atom or a methyl group, R ² is a divalent hydrocarbon group having 7 to 18 carbon atoms having a bridged cyclic hydrocarbon group, and R ⁶ is a hydrogen atom Or a hydrocarbon group having 1 to 12 carbon atoms, and x and z are arbitrary numbers satisfying x + z = 1, 0 <x ≦ 1, and 0 ≦ z <1, respectively.) A step of applying a photoresist material on a substrate to be processed, a step of performing exposure,
The present invention relates to a pattern forming method including at least a baking step and a developing step.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (1), R ¹ ,
R ³ and R ⁵ are a hydrogen atom or a methyl group.

R ² is a divalent hydrocarbon group having a carbon number of 7 to 18 having a bridged cyclic hydrocarbon group.
A tricyclo [5.2.1.0 ^2,6 ] decylmethyl group, a tricyclo [5.2.1.0 ^2,6 ] decanediyl group, an adamantanediyl group, a norbornanediyl group, a methylnorbornanediyl group, Isobornanediyl group, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecanediyl group, methyltetracyclo [4.4.0.1
^2,5 . 1 ^7,10 ] dodecanediyl group, hexacyclo [6.6.1.1 ^3,6 . 0 ^10,13 . 0 ^9,14 ] heptadecanediyl group, methylhexacyclo [6.6.1.1 ^3,6 .
0 ^10,13 . 0 ^9,14 ] heptadecanediyl group, and the like, but is not limited thereto.

R ⁴ is a hydrocarbon group having an epoxy group, and specifically, a glycidyl group as shown in Table 2;
3,4-epoxy-1-cyclohexylmethyl group, 5,
6-epoxy-2-bicyclo [2,2,1] heptyl group, 5 (6) -epoxyethyl-2-bicyclo [2,
2,1] heptyl, 5,6-epoxy-2-bicyclo [2,2,1] heptyl methyl group, 3,4-epoxytricyclo [5.2.1.0 ^{2, 6]} decyl group, 3 , 4-Epoxytricyclo [5.2.1.0 ^2,6 ] decyloxyethyl group, 3,4-epoxytetracyclo [4.4.
0.1 ^2,5 . 1 ^7,10 ] dodecyl group, 3,4-epoxytetracyclo [4.4.0.1 ^2,5 . [ ^1,7,10 ] dodecylmethyl group, but is not limited thereto.

R ⁶ is a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, specifically, a methyl group, an ethyl group,
n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, cyclohexyl group, dimethylcyclohexyl group, tricyclo [5.2.1.0 ^2,6 ]
Examples include, but are not limited to, a decyl group, an adamantyl group, a norbornyl group, and an isobornyl group.

In the general formula (1), x, y and y are
X + y + z = 1, 0 <x <1, 0 <y <1,
Any number that satisfies 0 ≦ z <1.

In the general formula (2), x and z are arbitrary numbers satisfying x + z = 1, 0 <x ≦ 1, 0 ≦ z <1, respectively, and R ¹ , R ² , R ⁵ , R ⁶ Is the same as in the general formula (1).

The weight average molecular weight of the polymer used in the present invention is 1,000 to 500,000, preferably 500
0 to 200,000.

[0027]

[Table 1]

[0028]

[Table 2]

In the production of the polymer used in the present invention, in the case of the polymer of the general formula (1), the (meth) acrylate monomer represented by the following general formulas (3), (4) and (5) is used. In the case of the polymer represented by the general formula (2), a general polymerization method such as radical polymerization or ionic polymerization is performed using (meth) acrylate monomers represented by the following general formulas (3) and (5). Can be done by

[0030]

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(In the above formula, R ⁷ is a hydrogen atom or a methyl group, and R ⁸ is a bridged cyclic hydrocarbon group having 7 to 7 carbon atoms.)
And represents 18 divalent hydrocarbon groups. )

[0032]

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(In the above formula, R ⁹ represents a hydrogen atom or a methyl group, and R ¹⁰ represents a hydrocarbon group having an epoxy group.)

[0034]

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(In the above formula, R ¹¹ represents a hydrogen atom or a methyl group, and R ¹² represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.) In the production of the polymer used in the present invention, for example, In tetrahydrofuran, under an inert gas (argon, nitrogen, etc.) atmosphere, a suitable radical polymerization initiator [for example, azobisisobutyronitrile (AIBN)] is added, and the mixture is heated and stirred at 50 to 70 ° C. for 0.5 to 12 hours. And polymerizing the above monomer. In addition, an arbitrary copolymer can be obtained by selecting the ratio of charged monomers of the copolymer and other polymerization conditions.

The (meth) acrylate monomer represented by the general formula (3), which is a raw material of the polymer, can be obtained by the method described in JP-A-8-25926, which has already been disclosed by the inventors. Further, among monomers having an epoxy group represented by the general formula (4), for example, a compound represented by the formula (6)

[0037]

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The 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl acrylate represented by the following formula is obtained by subjecting dicyclopentenyl acrylate to epoxidation reaction with acetic acid in peracetic acid. Similarly, equation (7)

[0039]

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5,6-epoxy-2-bicyclo [2,2,1] heptyl methacrylate represented by the following formula:

[0041]

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3,4-epoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10] dodecyl acrylate, 5-norbornene-2-methacrylate or tetracyclo [4.4.0.1 ^{2, 5.} [ ^7,10 ] ^dodecenyl acrylate by subjecting it to an epoxidation reaction.

The photoacid generator which is a component of the negative photoresist material of the present invention is a photoacid generator which generates an acid upon irradiation with light having a wavelength of 400 nm or less, preferably in the range of 180 to 220 nm. It is desirable that the mixture with the polymer or the like in the present invention shown above is sufficiently dissolved in an organic solvent, and that the solution can form a uniform coating film by a film forming method such as spin coating. Any photoacid generator may be used. Moreover, you may use individually or in mixture of 2 or more types.

Examples of usable photoacid generators include, for example, Journal of the Organic Chemistry, Vol.
5, No. 5, pp. 3055-3058 (1978). V. Triphenylsulfonium salt derivatives of JV Crivello et al., And other onium salts represented by the same (for example, compounds such as sulfonium salts, iodonium salts, phosphonium salts, diazonium salts, and ammonium salts), and 2,6-dinitro Benzyl esters [O. O. Nalamasu et al., SPIE Proceedings, 1262, 32 (1990)], 1,
2,3-tri (methanesulfonyloxy) benzene [Takumi Ueno et al., Proceeding of PME '8
9, Kodansha, pp. 413-424 (1990)], and sulfosuccinimide disclosed in JP-A-5-134416.

The content of the photoacid generator is usually 0.1 to 100 parts by weight of all components of the resist material including itself.
It is 2 to 30 parts by weight, preferably 1 to 15 parts by weight. When the content is 0.2 parts by weight or more, sufficient sensitivity is obtained, and pattern formation is facilitated. When the amount is 30 parts by weight or less, formation of a uniform coating film becomes easy, and residue (scum) hardly occurs after development.

The content of the polymer which is a component of the negative photoresist material of the present invention is usually 40 to 9 based on 100 parts by weight of all components of the resist material including itself.
It is 9.8 parts by weight, preferably 60 to 99 parts by weight.

Examples of the polyfunctional epoxy compound used in the present invention include hydrogenated bisphenol A diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, and neopentyl. Glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 1,2
-Cyclohexanecarboxylic acid diglycidyl ester,
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, trisepoxypropyl isocyanurate, 2-epoxyethylbicyclo [2,
2,1] heptyl glycidyl ether, ethylene glycol bis (2-epoxyethylbicyclo [2,2,1]
Heptyl) ether, bis (2-epoxyethylbicyclo [2,2,1] heptyl) ether and the like, but are not limited thereto.

The content of the polyfunctional epoxy compound is usually 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of all components of the resist material including itself. In particular, when the polymer of the general formula (1) is used, 5 to 3
0 parts by weight, when the polymer of the general formula (2) is used, 10 to 10 parts by weight
40 parts by weight are preferred. Moreover, you may use individually or in mixture of 2 or more types.

Preferred solvents for use in the present invention are those in which resist components such as a polymer, a photoacid generator, and a polyfunctional epoxy compound are sufficiently dissolved and the solution is uniformly coated by a method such as spin coating. Any solvent may be used as long as it can form a film. Moreover, you may use individually or in mixture of 2 or more types. Specifically, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monoethyl ether acetate, methyl lactate, ethyl lactate, 2-methoxybutyl acetate, Acetic acid 2
-Ethoxyethyl, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, N-methyl-2-pyrrolidinone, cyclohexanone, cyclopentanone, cyclohexanol, methyl ethyl ketone, 1,4-dioxane , Ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, and the like, but are not limited thereto.

The "basic" constituents of the photoresist material of the present invention, when a polymer of the general formula (1) is used, are the polymer, a photoacid generator and a solvent. Compounds are added. When the polymer of the general formula (2) is used, the polymer, the photoacid generator, the solvent and the polyfunctional epoxy compound are used. If necessary, other components such as a surfactant, a dye, a stabilizer, a coating improver, and a dye may be added to the above “basic” components.

The present invention also provides a method for forming a negative pattern of a photoresist on a substrate to be processed using the above negative photoresist material. FIG. 1 shows a method for forming a negative pattern according to the present invention.

First, as shown in FIG. 1A, a negative photoresist material of the present invention is applied on a substrate 1 to be processed, and a heating means such as a hot plate is applied at 60 to 170 ° C. for 30 to 240 seconds. The resist film 2 is formed by performing a pre-baking process. Next, as shown in FIG. 1B, the resist film 2 is selectively exposed with an exposure apparatus using a mask 3. Exposure light is suitably light having a wavelength of 220 nm or less, preferably light having a wavelength of 180 to 220 nm,
More preferably, ArF excimer laser light is used. After the exposure, the resist film 2 is subjected to a heat treatment. As a result, in the exposed region, the epoxy group causes a ring-opening polymerization reaction due to the action of the acid generated from the photoacid generator, crosslinks the resin, and forms a crosslinked region 4 (FIG. 1 (C)). And finally Figure 1
As shown in (D), with an alkali developing solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH),
The unexposed portions of the resist film 2 are selectively dissolved and removed to form a negative pattern.

The negative photoresist material of the present invention comprises 22
It has high transparency of light of 0 nm or less, high dry etching resistance, and can be used as a new negative photoresist material. Further, by using the negative photoresist material of the present invention in a photolithography process, a fine negative pattern can be formed.

[0054]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention.

(Synthesis Example 1) A polymer having the following structure (in the general formula (1), R ¹ is a methyl group, and R ² is a tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodecanediyl group) ,
R ³ is a hydrogen atom, R ⁴ is a 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl group, x = 0.7, y =
0.3, z = 0. ) Was performed.

[0056]

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In a 100 ml eggplant flask equipped with a reflux tube, 3.075 g of carboxytetracyclododecyl methacrylate and 3,4-epoxytricyclo [5.2.
1.0 ^{2, 6]} decyl acrylate 1g dissolved in dry tetrahydrofuran 27 ml, AIBN223mg there
(50 mmol·l ⁻¹ ), and the mixture was added under an argon atmosphere.
Stir at 0-65 ° C. After cooling for 2 hours, the reaction mixture was poured into 300 ml of ligroin, and the deposited precipitate was separated by filtration. Further, re-precipitation purification was performed once again to obtain 2.851 g of the desired product (yield 70%). The copolymerization ratio at this time was 7: 3 from the integral ratio of ¹ H-NMR (x
= 0.7, y = 0.3). According to GPC analysis, the weight average molecular weight (Mw) was 22,300 (in terms of polystyrene),
The degree of dispersion (Mw / Mn) was 2.15.

(Synthesis Examples 2 and 3) Polymerization was carried out in the same manner as in Synthesis Example 1 except that the charge ratio of the monomers was changed. Table 3 below
To the charge ratio of the monomer, the copolymerization ratio of the polymer (x / y),
Shows the weight average molecular weight.

[0059]

[Table 3]

(Synthesis Examples 4 and 5) Polymerization was carried out in the same manner as in Synthesis Example 1 except that the amount (concentration) of AIBN was changed. Table 4 below shows the AIBN concentration, the copolymerization ratio (x / y) of the polymer, and the weight average molecular weight.

[0061]

[Table 4]

[0062] (Synthesis Example 6) polymer of the following structure in (formula ^{(1), R 1, R} 3 is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 A dodecanediyl group, R ⁴ is a glycidyl group, x = 0.7, y = 0.3, z
= 0. ) Was performed.

[0063]

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Synthesis was performed in the same manner as in Synthesis Example 1 except that glycidyl methacrylate (Light Ester G, manufactured by Kyoeisha Chemical Co., Ltd.) was used instead of 3,4-epoxytricyclodecyl acrylate. The molecular weight of the obtained polymer is M
w = 24500 and Mw / Mn = 1.92.

[0065] (Synthesis Example 7) polymers of the following structures in (Formula ^{(1), R 1, R} 3 is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ], A dodecanediyl group, R ⁴ is a 3,4-epoxy-1-cyclohexylmethyl group, x = 0.7, y = 0.3, z = 0.).

[0066]

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As in Synthesis Example 1, but using 3,4-epoxy-1-cyclohexylmethyl methacrylate (Cycloma-M100 manufactured by Daicel Chemical Industries, Ltd.) instead of 3,4-epoxytricyclodecyl acrylate. did. The molecular weight of the obtained polymer was Mw = 2100
0, Mw / Mn = 1.88.

[0068] (Synthesis Example 8) polymer of the following structure in (formula ^{(1), R 1, R} 3 is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 A dodecanediyl group, wherein R ⁴ is 5,6-epoxy-2-bicyclo [2,
2,1] heptyl group, x = 0.7, y = 0.3, z = 0
It is. ) Was performed.

[0069]

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The synthesis was carried out in the same manner as in Synthesis Example 1 except that 5,6-epoxy-2-bicyclo [2,2,1] heptyl methacrylate was used instead of 3,4-epoxytricyclodecyl acrylate. The molecular weight of the obtained polymer is M
w = 20800 and Mw / Mn = 2.03.

(Synthesis Example 9) A polymer having the following structure (in the general formula (1), R ¹ is a methyl group, R ² is a norbornanediyl group, R ³ is a hydrogen atom, and R ⁴ is 3,4-epoxytricyclo. [5.2.1.0 ^2,6 ] decyl group, x = 0.
7, y = 0.3 and z = 0. ) Was performed.

[0072]

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Synthesis was performed in the same manner as in Synthesis Example 1 except that carboxynorbornyl methacrylate was used instead of carboxytetracyclododecyl methacrylate. The molecular weight of the obtained polymer was Mw = 22,500, Mw / Mn =
2.06.

(Synthesis Example 10) A polymer having the following structure (in the formula (1), R ¹ is a methyl group, R ² is a tricyclo [5.2.1.0 ^2,6 ] decylmethyl group, and R ³ is hydrogen The atom R ⁴ is 3,4-epoxytricyclo [5.2.1.
0 ^2,6 ] decyl group, x = 0.7, y = 0.3, z = 0. ) Was performed.

[0075]

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Synthesis was performed in the same manner as in Synthesis Example 1 except that carboxytricyclodecylmethyl methacrylate was used instead of carboxytetracyclododecyl methacrylate. The molecular weight of the obtained polymer was Mw = 21800, Mw
/Mn=2.12.

(Synthesis Example 11) A polymer having the following structure (in the general formula (1), R ¹ is a methyl group, and R ² is a tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodecanediyl group) , R
³ is a hydrogen atom, R ⁴ is 3,4-epoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecyl group, x = 0.
7, y = 0.3 and z = 0. ) Was performed.

[0078]

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As in Synthesis Example 1, but instead of 3,4-epoxytrisictodecyl acrylate, 3,4-epoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ]
It was synthesized using dodecyl acrylate. The molecular weight of the obtained polymer was Mw = 18300, Mw / Mn = 2.38.
Met.

[0080] (Synthesis Example 12) polymer of the following structure in (formula ^{(1), R 1, R} 5 is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 A dodecanediyl group, R ³ is a hydrogen atom, R ⁴ is 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl group, R ⁶ is a methyl group,
x = 0.6, y = 0.2, z = 0.1. ) Was performed.

[0081]

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In a 100 ml eggplant flask equipped with a reflux tube, 2.636 g of carboxytetracyclododecyl methacrylate, 1 g of 3,4-epoxytricyclodecyl acrylate and 0.152 g of methyl methacrylate were dissolved in 25 ml of dry tetrahydrofuran, and AIB was added thereto.
N206 mg (50 mmol·l ⁻¹ ) was added, and the mixture was stirred at 60 to 65 ° C. under an argon atmosphere. Let cool after 2 hours,
The reaction mixture was poured into 300 ml of ligroin, and the deposited precipitate was separated by filtration. Further, re-precipitation purification was performed once again to obtain 2.462 g of the desired product (yield: 65%). The molecular weight of the obtained polymer was Mw = 25800, Mn / 2.24.
Met.

[0083] (Synthesis Example 13) polymer of the following structure in (formula ^{(1), R 1, R} 5 is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 A dodecanediyl group, R ³ is a hydrogen atom, R ⁴ is a 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl group, R ⁶ is a tricyclodecyl group, x = 0.6, y = 0.3, z = 0.1).

[0084]

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The synthesis was carried out in the same manner as in Synthesis Example 12 except that tricyclodecyl methacrylate (FA-513M, manufactured by Hitachi Chemical Co., Ltd.) was used instead of methyl methacrylate. The molecular weight of the obtained polymer was Mw = 21600, Mw
/Mn=2.32.

[0086] (Synthesis Example 14) polymer of the following structure in (general formula (1), R ¹ is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecanediyl group , R ³
Is a hydrogen atom, R ⁴ is a 5 (6) -epoxyethyl-2-bicyclo [2,2,1] heptyl group, x = 0.7, y =
0.3, z = 0. ) Was performed.

[0087]

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As in Synthesis Example 1, but instead of 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl acrylate, 5 (6) -epoxyethyl-2-bicyclo [2,2 , 1] heptyl acrylate. The molecular weight of the obtained polymer was Mw = 16800, Mw
/Mn=2.29.

[0089] (Synthesis Example 15) polymer of the following structure in (formula ^{(2), R 1, R} 5 is a methyl group, R ² is tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 A dodecanediyl group, R ⁶ is a tricyclodecyl group, x = 0.7, z = 0.
3. ) Was performed.

[0090]

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The synthesis was carried out in the same manner as in Synthesis Example 1 except that tricyclodecyl methacrylate was used instead of 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl acrylate. The molecular weight of the obtained polymer was Mw = 1940.
0, Mw / Mn = 2.08.

(Evaluation of etching resistance of polymer) Synthesis example
1 g of diethylene glycol dimethyl
Dissolved in 10 g of ether, then 0.2 μm Teflon
It filtered using the filter. Next, 3 inch silicon base
Spin coat on the plate and hot-press at 90 ° C for 60 seconds
Perform baking on a rate to form a thin film with a thickness of 0.7 μm.
Formed. The obtained membrane was used for DEM451
C using active ion etching (RIE) equipment
F _Four The etching rate for the gas was measured. At this time
Etching conditions are as follows: Power = 100 W, pressure = 5
Pa, gas flow rate = 30 sccm. Similarly,
The etching rate was measured for the polymer obtained in Example 13.
did. Table 4 shows the results. Novolac Regis as a comparison
(PFI-15A manufactured by Sumitomo Chemical Co., Ltd.), KrF resist
(P-vinyl resin) used as a base resin for
Enol), having no bridged cyclic hydrocarbon group in the molecular structure
It consisting of resin poly (methyl methacrylate)
The results for each coating film are also shown. Note that the etching rate is
With the relative value with the etching rate of volak resist being 1
Indicated.

From the results, the polymer used in the present invention was:
It is clear that the etching rate with respect to CF ₄ gas is low and the dry etching resistance is excellent.

[0094]

[Table 5]

(Example 1) A resist having the following composition was prepared. (A) Polymer (Synthesis Example 1): 2 g (b) Photoacid generator (triphenylsulfonium triflate): 0.02 g (c) Ethyl lactate: 10.5 g A 0.2 μm Teflon filter was used for the above mixture. After filtration, the resultant was spin-coated on a 3-inch quartz substrate and baked at 100 ° C. for 1 minute on a hot plate to form a thin film having a thickness of 1 μm.

This thin film was measured with an ultraviolet-visible spectrophotometer at the center wavelength of ArF excimer laser light of 19%.
The transmittance at 3.4 nm was measured. Similarly, the polymer obtained in Synthesis Example 13 was measured.

As a result, the transmittance containing the polymer of Synthesis Example 1 was 53% / μm and that containing the polymer of Synthesis Example 13 was 56% / μm. From this result, it is clear that the photoresist material of the present invention shows sufficient transparency as a single-layer resist.

(Example 2) A wafer in which the resist of Example 1 was formed to a thickness of 0.5 μm on a Si substrate was allowed to stand in a contact-type exposure experiment machine sufficiently purged with nitrogen. A mask in which a pattern was drawn with chrome on a quartz plate was brought into close contact with the resist film, and ArF excimer laser light was irradiated through the mask. Immediately thereafter, bake on a hot plate at 140 ° C. for 60 seconds, and then 2.38% of the liquid temperature of 23 ° C.
The phenomenon by the immersion method was performed for 60 seconds in a TMAH aqueous solution, and subsequently, the rinse treatment was performed for 60 seconds with pure water. As a result, only the unexposed portion of the resist film was dissolved and removed in the developing solution, and a negative pattern was obtained.

As a result, the resist containing the polymer of Synthesis Example 1 had a resolution of 0.25 μmL / S and a sensitivity of 30 m
J / cm ² , the resist containing the polymer of Synthesis Example 13 had a resolution of 0.24 μmL / S and a sensitivity of 45 mJ / c.
m ² . From this result, it was found that the negative photoresist material of the present invention had excellent resolution characteristics. Further, since there was no phenomenon such as pattern peeling, it was confirmed that the substrate had excellent adhesiveness.

Example 3 A resist having the following composition was prepared. (A) Polymer (Synthesis Example 1): 2 g (b) Photoacid generator (triphenylsulfonium triflate): 0.02 g (c) Alicyclic epoxy compound (EHPE-3150, manufactured by Daicel Chemical): 0 0.4 g (d) Ethyl lactate: 10.5 g The patterning was evaluated in the same manner as in Example 2. As a result, the above resist has a resolution of 0.22.
μmL / S, sensitivity was 20 mJ / cm ² .

Similarly, a resist using trisepoxypropyl isocyanurate (manufactured by Nissan Chemical Co., Ltd.) instead of the alicyclic epoxy compound (EHPE-3150, manufactured by Daicel Chemical Co., Ltd.) was prepared and evaluated. . As a result, the resolution was 0.22 μmL / S and the sensitivity was 16 mJ / c.
m ² .

Example 4 A resist having the following composition was prepared. (A) Polymer (Synthesis Example 15): 2 g (b) Photoacid generator (triphenylsulfonium triflate): 0.02 g (c) Alicyclic epoxy compound (EHPE-3150, manufactured by Daicel Chemical Industries): 0 0.8 g (d) Ethyl lactate: 10.5 g The patterning was evaluated in the same manner as in Example 2. As a result, the above resist has a resolution of 0.22.
μmL / S, sensitivity was 50 mJ / cm ² .

Similarly, a resist using trisepoxypropyl isocyanurate (manufactured by Nissan Chemical Industries, Ltd.) instead of the alicyclic epoxy compound (EHPE-3150, manufactured by Daicel Chemical Co., Ltd.) was prepared and evaluated. . As a result, the resolution was 0.22 μmL / S, and the sensitivity was 60 mJ / c.
m ² .

[0104]

As is apparent from the above description, the negative photoresist material of the present invention is excellent in dry etching resistance and transparency, and furthermore, the negative photoresist material of the present invention can be used for manufacturing a semiconductor device by using the negative photoresist material of the present invention. Necessary fine patterns can be formed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for forming a resist pattern according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate to be processed 2 Resist film 3 Mask 4 Crosslinked area

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Etsuo Hasegawa 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (56) References JP-A-8-259626 (JP, A) JP-A-6 -348017 (JP, A) JP-A-7-33855 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 7/038 G03F 7/004 G03F 7/033 H01L 21/027

Claims (6)

(57) [Claims] 1. A negative photoresist material comprising at least a polymer represented by the general formula (1) and having a weight average molecular weight of 1,000 to 500,000 and a photoacid generator which generates an acid upon exposure. Embedded image (In the above formula, R ¹ , R ³ , and R ⁵ are a hydrogen atom or a methyl group, and R ² is a bridged cyclic hydrocarbon group having 7 to 7 carbon atoms.)
18, a divalent hydrocarbon group, R ⁴ represents a hydrocarbon group having an epoxy group, and R ⁶ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. X, y and z are x + y +
z is an arbitrary number satisfying 0, 0 <x <1, 0 <y <1, and 0 ≦ z <1. ) 2. The negative photoresist material according to claim 1, further comprising a polyfunctional epoxy compound. 3. It comprises at least a polymer represented by the general formula (2) and having a weight average molecular weight of 1,000 to 500,000, a photoacid generator which generates an acid upon exposure, and a polyfunctional epoxy compound. Negative photoresist material. Embedded image (In the above formula, R ¹ and R ⁵ are a hydrogen atom or a methyl group, and R ² is a bridged cyclic hydrocarbon group having 7 to 18 carbon atoms.
R ⁶ is a hydrogen atom or a C 1 -C
Represents 12 hydrocarbon groups. X and z are x
+ Z = 1, 0 <x ≦ 1, 0 ≦ z <1 is an arbitrary number that satisfies 0 <z <1. ) 4. A process comprising applying the photoresist material according to claim 1, 2 or 3 onto a substrate to be processed, exposing, baking, and developing. Pattern formation method. 5. The pattern forming method according to claim 4, wherein the exposure light has a wavelength of 180 to 220 nm. 6. The pattern forming method according to claim 4, wherein the exposure light is ArF excimer laser light.