JP2000147769A - Negative photoresist material and pattern forming method using the material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a negative photoresist material having excellent transparency and durability against etching and high sensitivity to be used for lithography using exposure light especially in a specified range by incorporating at least a specified polymer and a photoacid producing agent which produces an acid by exposure. SOLUTION: This negative photoresist material contains a polymer expressed by the formula and at least a photoacid producing agent which produces an acid by exposure. In the formula, each of R1 to R3 and R5 is a hydrogen atom or methyl group, R4 is a 3-13C hydrocarbon group having epoxy groups, R6 is a hydrogen atom or 7-13C org. cyclic hydrocarbon group having carboxyl groups, and x, y, z are numbers satisfying x+y+z=1, 0<x<1, 0<y<1 and 0<z<1. Thereby, the obtd. negative photoresist material has excellent transparency and etching durability and high sensitivity and can be used for lithography using exposure light at <220 nm wavelengths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a lithography process in the manufacture of semiconductor devices, and more particularly to a lithography process having a wavelength of 22 nm.
The present invention relates to a negative photoresist material and a pattern forming method suitable for lithography using far ultraviolet light of 0 nm or less as exposure light.

[0002]

2. Description of the Related Art In the field of manufacturing various electronic devices that require fine processing of a half-micron order represented by a semiconductor device, there is an increasing demand for higher density and higher integration of devices. Therefore, the demand for photolithography technology for forming fine patterns has become more and more severe. In particular, a DRAM having an integration of 1 Gbit or more that requires a processing technology of 0.18 μm or less
The use of photolithography with an ArF excimer laser (193 nm) has recently been considered for the production of [Donald C. et al. Hoffer et al., Journal of Photopolymer Science and Technology (J
ownnal of Photopolymer Sc
issue and Technology), 9 (3), pp. 387-397 (1996)].

Therefore, development of a resist material corresponding to photolithography using ArF light is desired.
In developing this resist for ArF exposure, it is necessary to satisfy the improvement of laser cost performance because the life of the gas which is the material of the laser is short and the laser device itself is expensive. is there. 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 describes a resist comprising a combination of triphenylsulfonium hexafluoroacetate and poly (p-tert-butoxycarbonyloxy-α-methylstyrene). Such chemically amplified resists are currently widely used as resists for KrF excimer lasers [for example, Hiroshito,
C. Grant Wilson, American Chemical Society Symposium Series 242, pp. 11-23 (1984)]. A characteristic 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 the developed resists are chemically amplified.

[0005]

However, in the case of lithography using short-wavelength light of 220 nm or less typified by ArF excimer laser light, a negative photoresist material for forming a fine pattern is a conventional negative photoresist material. There is a need for new properties that cannot be satisfied with materials, that is, high transparency to exposure light of 220 nm or less and dry etching resistance.

Conventional g-line (438 nm) and i-line (365 nm)
The negative photoresist material for the KrF excimer laser (248 nm) mainly comprises a resin and a cross-linking agent, and the resin component is a novolak resin or poly (p).
A resin having an aromatic ring in a structural unit such as (vinyl phenol) is used, and the etching resistance of the resin can be maintained by the dry etching resistance of the aromatic ring. As the cross-linking agent, for example, an azide compound such as 2,6-di (4′-azidobenzal) -4-methylcyclohexanone or 3,3′-diazidodiphenyl sulfone, or a methylol melamine 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. For this reason, conventional resins cannot be directly applied to photolithography using short-wavelength light of 220 nm or less. Therefore, a negative photoresist material that does not contain an aromatic ring, has etching resistance, and is transparent to a wavelength of 220 nm or less has been desired.

As a polymer compound having transparency to ArF excimer laser light (193 nm) and resistance to dry etching, a copolymer having an adamantyl methacrylate unit which is an alicyclic polymer [Takechi et al.
Null of Photopolymer Science and Technology (Journal of Photopol)
ymer Science and Technology
gy), 5 (3), pages 439-446 (1992)
Years)] and copolymers having isobornyl methacrylate units [R. D. RD Allen et al., Jar.
Null of Photopolymer Science and Technology (Journal of Photopol)
ymer Science and Technology
gy), Volume 8 (No. 4), pp. 623-636 (1995)
Year 9), and Volume 9 (No. 3), pp. 465-474 (19
1996)] has been proposed.

[0008] The inventors have also previously disclosed JP-A-7-252324 as a resist material satisfying these requirements.
And a resin disclosed in JP-A-8-259626. However, these photoresist materials are chemically amplified positive photoresists composed of a resin having an acid-decomposable group and a photoacid generator and give a positive pattern, and a negative photoresist satisfying the above requirements has not been developed. . Therefore, the present invention proposes that the wavelength 220
It is an object of the present invention to provide a highly sensitive negative photoresist material excellent in transparency and etching resistance used in lithography using exposure light of nm or less, particularly exposure light of 180 nm to 220 nm. It is another object of the present invention to provide a pattern forming method using the negative photoresist material.

[0009]

The above object is achieved by the following means. That is, the present invention provides a negative photoresist material comprising at least a polymer represented by the general formula (1) and a photoacid generator which generates an acid upon exposure.

[0010]

Embedded image (In the above formula, R ¹ , R ² , R ³ , and R ⁵ are a hydrogen atom or a methyl group, R ⁴ is a hydrocarbon group having 3 to 13 carbon atoms having an epoxy group, and R ⁶ has a hydrogen atom or a carboxyl group. Represents a bridged cyclic hydrocarbon group having 7 to 13 carbon atoms, and x, y, and z are respectively x + y + z = 1, 0 <x <1, 0
Any number that satisfies <y <1, 0 <z <1. Further, the weight-average molecular weight of the polymer is 2,000 to 200,000), and the method further includes that the material further contains a polyhydric alcohol. The present invention also provides a step of applying the photoresist material on a substrate to be processed,
The present invention proposes a pattern forming method characterized by having at least a step of exposing to light having a wavelength of 220 nm, a step of performing baking, and a step of performing development, including that the exposure light is ArF excimer laser light. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the general formula (1), R¹, R^Two, R^Three,
R^FiveIs a hydrogen atom or a methyl group. Also R^FourIs Epoki
A hydrocarbon group having 3 to 13 carbon atoms having
Glycidyl groups and 3,4-epoxy as shown in Table 1
C-1-cyclohexylmethyl group, 5,6-epoxy-
2-norbornyl group, 5 (6) -epoxyethyl-2-
Norbornyl group, 5,6-epoxy-2-norbornyl
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-epoxyte
Toracyclo [4.4.0.1^2,5.1^7,10A dodecylmethyl group, etc.
But not limited to these.
Also R⁶Is a carbon atom having a hydrogen atom or a carboxyl group
A bridged cyclic hydrocarbon group of the formulas 7 to 13;
Carboxytricyclo [5.2.1.0^2,6]
Silmethyl group, carboxytricyclo [5.2.1.0^2,6]
Sil group, carboxyadamantyl group, carboxynorbo
Lunyl group, carboxymethylnorbornyl group, carboxyl
Siisobornyl group, carboxytetracyclo [4.4.0.1
^2,5.1^7,10] Dodecyl group, carboxymethyltetracycline
B [4.4.0.1^2,5.1^7,10A dodecyl group, etc.
However, it is not limited to these.

[0013]

[Table 1]

[0014]

[Table 2] The polymer used in the present invention can be obtained by subjecting a (meth) acrylate monomer as a raw material to a usual polymerization method such as radical polymerization or ionic polymerization. For example, in dry tetrahydrofuran, under an atmosphere of an inert gas (argon, nitrogen, etc.), a suitable radical polymerization initiator [for example, azobisisobutyronitrile (AIBN)] is added at 50 to 70 ° C.
By stirring with heating for 0.5 to 12 hours.
The weight average molecular weight of the polymer of the present invention is 2,000 to 20.
0000, more preferably 3000-10000
0. Also, an arbitrary copolymer can be obtained by selecting the proportion of charged monomers of the copolymer and other polymerization conditions.

The (meth) acrylate monomer having a carboxyl group and a bridged cyclic hydrocarbon group having 7 to 13 carbon atoms, which is a raw material of the polymer, is disclosed in JP-A-8-259626, which has already been disclosed by the present inventors. It can be obtained by the method described in the gazette. Among (meth) acrylate monomers having an epoxy group, for example, 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl acrylate is obtained by subjecting dicyclopentenyl acrylate to an epoxidation reaction with peracetic acid in acetic acid. Can be Similarly, 5,6-epoxy-2-
Norbornyl methacrylate is 5-norbornene-2-
It is obtained by subjecting methacrylate to an epoxidation reaction.

The content of the polymer which is a component of the negative photoresist material of the present invention is usually from 60 to 99.8 parts by weight based on 100 parts by weight of the total components including itself.
Preferably it is 70 to 99 parts by weight.

The photoacid generator used in the present invention is 400
nm or less, preferably a photoacid generator that generates an acid by light irradiation in the range of 180 nm to 220 nm, and the mixture with the polymer or the like in the present invention described above is sufficiently dissolved in an organic solvent. Any photoacid generator may be used as long as the solution can form a uniform coating film by a film forming method such as spin coating. 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, 43, 15
No., pp. 3055-3058 (1978). V. JVCrivello et al., A triphenylsulfonium salt derivative, and other onium salts represented by the derivative (eg, a sulfonium salt, an iodonium salt,
Compounds such as phosphonium salts, diazonium salts, and ammonium salts) and 2,6-dinitrobenzyl esters [O. O. Nalamasu et al., SPIE Proceeding, 1262, 32 (1990)], 1, 2, 3.
-Tri (methanesulfonyloxy) benzene [Takumi
Ueno et al., Proceeding of PME'89, Kodansha,
413-424 (1990)], Hei 5-13441
And Sulfosuccinimide disclosed in US Pat. The content of the photoacid generator is usually 0.2 to 15 parts by weight based on 100 parts by weight of all components including itself.
Preferably it is 1 to 10 parts by weight.

When the content is less than 0.2 parts by weight, the sensitivity of the present invention is remarkably reduced, and it becomes difficult to form a pattern. On the other hand, when the amount exceeds 15 parts by weight, it becomes difficult to form a uniform coating film, and there is a problem that a residue (scum) is easily generated after development.

The polyhydric alcohol used in the present invention includes, for example, ethylene glycol, glycerol,
2-butanediol, 1,3-butanediol, 1,4
-Butanediol, 2,3-butanediol, 1,2,
4-butanetriol, 1,2-pentanediol,
1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, , 2-cyclohexanediol, 1,3-cyclohexanediol,
1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,3,5-cyclohexanetrimethanol,
2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclooctanediol, 1,5-
Cyclooctanediol, tricyclodecanedimethanol, 2,3-norbornanediol, 2 (3) -hydroxy-5,6-bis (hydroxymethyl) norbornane, 2,3-dihydroxy-5 (6) -hydroxymethylnorbornane, 1,4-anhydroerythriol,
L-arabinose, L-arabitol, D-cellobiose, cellulose, 1,5-decalindiol, glucose, galactose, lactose, maltose, mannose, mannitol, tris (2-hydroxyethyl) isocyanurate and the like, but only these. It is not limited. The content of the polyhydric alcohol is usually 1 to 40 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of all components including itself. Also, alone 2
Species or more may be mixed.

The negative photoresist material of the present invention is prepared by dissolving the components in a solvent so that the concentration of all the constituents at the time of use is 5 to 40% by weight, and then filtering through a filter. A preferred solvent to be used is an organic solvent in which components composed of a resin, a photoacid generator, and a polyhydric alcohol are sufficiently dissolved, and the solution is capable of forming a uniform coating film by a method such as spin coating. Any solvent may be used. Moreover, you may use individually or in mixture of 2 or more types. Specifically, n-propyl alcohol,
Isopropyl alcohol, n-butyl alcohol, te
rt-butyl alcohol, methyl cellosolve acetate
G, ethyl cellosolve acetate, propylene glyco-
Lumonoethyl ether acetate, methyl lactate, ethyl lactate, 2-methoxybutyl acetate, 2-ethoxyethyl acetate, 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
Ter, ethylene glycol monoisopropyl ether,
Examples include diethylene glycol monomethyl ether and diethylene glycol dimethyl ether, but are not limited thereto.

Further, other components such as a surfactant, a dye, a basic additive, a stabilizer, a coating improver, and a dye may be added to the resist composition of the present invention, if necessary.

The present invention also provides a method for forming a negative photoresist pattern 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 60 to 1
The resist film 2 is formed by performing a pre-baking process at 70 ° C. for 30 to 240 seconds using a heating means such as a hot plate. Next, as shown in FIG. 1B, the resist film 2 is selectively exposed using an exposure apparatus. 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, and cross-linking of the resin occurs as shown in FIG. 1 (C). In addition, when a photoresist material to which a polyhydric alcohol is added is used, in the exposed region, the epoxy group reacts not only with the epoxy groups but also with the polyhydric alcohol by the action of an acid. Is promoted. Finally, as shown in FIG. 1 (D), an alkaline developing solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH) is used.
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 has high transparency to light of 220 nm or less, has 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 negative pattern can be formed.

[0025]

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) 5-Acryloyloxy-2,6-norbornanecarbolacto
Synthesis of ne.

[0026]

Embedded image 5-Hydroxy-2,6-norbornanecarbolactone (HB He
nbest et al. Chem. Soc. , 221-22
6 g (1959)) 10 g (0.0653 mol),
9.49 g of N, N-dimethylaniline and 20 mg of phenothiazine are dissolved in 60 ml of dry THF and cooled with ice. A solution obtained by dissolving 6.5 g of acryloyl chloride in 10 ml of dry THF is added dropwise thereto. After stirring for 2 hours under ice cooling and 3 hours at room temperature, the filtrate is concentrated under reduced pressure. Ether 25
0 ml, 0.5N hydrochloric acid 200 ml, saturated saline,
Wash with 200 ml of 3% NaHCO ₃ aqueous solution, saturated saline solution and water in that order. After the ether layer was dried over MgSO ₄ , the ether was distilled off under reduced pressure.
After washing with ml × 2, 5.38 g of the desired product was obtained (white solid, yield: 40%). Melting point: 96 ° C; 1H-NMR
(CDCl3) δ 1.66 (1H, d), 1.78 (1
H, d), 1.99-2.11 (2H, m), 2.53-
2.62 (2H, m), 3.18-3.25 (1H,
m), 4.59 (1H, d), 4.64 (1H, s),
5.89 (1H, dd), 6.11 (1H, dd), 6.
43 (1H, dd); IR (KBr) 2880,298
0 (νC−H), 1712, 1773 (νC = O), 1
618, 1630 (νC = C), 1186, 1205
(ΝC-O) cm ^-1 (Synthesis Example 2) 5-Methacryloyloxy-2,6-norbornanecarbol
Synthesis of actone (methacrylate of the following structure).

[0027]

Embedded imageSame as in Synthesis Example 1, except that acryloyl chloride is replaced with meta
It was synthesized using acryloyl chloride (yield 20%).
1H-NMR (CDCl3) δ 1.62 (1H, d),
1.75 (1H, d), 1.92 (3H, s), 1.95
-2.16 (2H, m), 2.53-2.66 (2H,
m), 3.20-3.28 (1H, m), 4.59 (1
H, d), 4.65 (1H, s), 5.62 (1H, d)
d), 6.10 (1H, dd); IR (KBr) 288
0, 2982 (νC-H), 1715, 1780 (νC
= O), 1630 (νC = C), 1156, 1178
(ΝC-O) cm^-1 (Synthesis Example 3) Polymer having the following structure (in general formula (1)
And R¹, R^Two, R^Three, R^FiveIs a hydrogen atom, R ^FourIs epoxy
Tylnorbornyl group, R6 is carboxytetracyclo
[4.4.0.1^{2, Five}.1^7,10A dodecyl group, x = 0.2, y =
0.47, z = 0.33)

[0028]

Embedded image In a 100 ml eggplant flask equipped with a reflux tube, 2 g of the acrylate obtained in Synthesis Example 1, 4.7 g of epoxyethylnorbornyl acrylate, and 4.38 g of carboxytetracyclododecyl acrylate were placed in dry tetrahydrofuran 60.
and 295 mg of AIBN (monomer /
AIBN = 28/1) and added under argon atmosphere
Stir at 65 ° C. After cooling for 2 hours, the reaction mixture was poured into 900 ml of a hexane / toluene (2/1) mixed solution, and the deposited precipitate was separated by filtration. Further purification was performed once again to obtain 5.69 g of the desired product (yield: 51%). The copolymerization ratio at this time was 2 from the integration ratio of ¹ H-NMR.
0:47:33 (x = 0.2, y = 0.47,
Z = 0.33). According to GPC analysis, the weight average molecular weight (Mw) was 8600 (in terms of polystyrene), and the degree of dispersion (Mw) was
w / Mn) was 1.45. (Synthesis Examples 4 and 5) Polymerization was carried out in the same manner as in Synthesis Example 3 except that the charge ratio of the monomers was changed. Table 3 below shows the charge ratio of the monomers, the copolymerization ratio (x / y / z) of the polymer, and the weight average molecular weight.

[0029]

[Table 3] (Synthesis Examples 6 and 7) Polymerization was carried out in the same manner as in Synthesis Example 3, except that the amount of AIBN (monomer / AIBN) was changed. Table 4 below
Shows the copolymerization ratio and weight average molecular weight of the polymer.

[0030]

[Table 4] (Synthesis Example 8) A polymer having the following structure (in the general formula (1), R ¹ , R ² and R ³ are hydrogen atoms, R ⁴ is an epoxyethylnorbornyl group, R ⁵ is a methyl group, and R ⁶ is hydrogen Atom, x =
0.2, y = 0.47, z = 0.33)

[0031]

Embedded image Synthesis was performed in the same manner as in Synthesis Example 3, except that methacrylic acid was used instead of carboxytetracyclododecyl acrylate. Yield 61%, Mw = 10800, Mw / Mn = 1.
55 (Synthesis Example 9) Polymer having the following structure (in the general formula (1), R ¹ and R ⁵ are methyl groups, R ² and R ³ are hydrogen atoms, R ⁴ is an epoxyethylnorbornyl group, and R ⁶ is Carboxynorbornyl group, x = 0.2, y = 0.47, z = 0.3
3)

[0032]

Embedded image Synthesis was performed in the same manner as in Synthesis Example 3, except that the monomer obtained in Synthesis Example 2 was used instead of the monomer obtained in Synthesis Example 1, and carboxynorbornyl methacrylate was used instead of carboxytetracyclododecyl acrylate. Yield 53
%, Mw = 16300, Mw / Mn = 1.4 (Synthesis Example 10) A polymer having the following structure (in the general formula (2), R ¹ , R ² , and R ³ are hydrogen atoms, and R ⁴ is 3,4- An epoxytricyclo [5.2.1.0 ^2,6 ] decyl group, R ⁵ is a methyl group,
R ⁶ is carboxy tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl group, x = 0.2, y = 0.47 , z = 0.33)

[0033]

Embedded image As in Synthesis Example 3, except that epoxyethyl norbornyl acrylate was used instead of 3,4-epoxytricyclo [5.2.
1.0 ^2,6] decyl acrylate, using carboxy-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl methacrylate in place of the carboxy-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl acrylate And synthesized. Yield 46%, Mw =
17000, Mw / Mn = 1.5 (Synthesis Example 11) Polyhydric alcohol having the following structure (2,3-dihydroxy-5 (6) -hydroxymethylnorbornane)

[0034]

Embedded image 11 g of 2-hydroxymethyl-5-norbornene is dissolved in 21 ml of pyridine, 11 ml of acetic anhydride is added dropwise thereto, and the mixture is stirred at room temperature for 12 hours. 100 m of water in the reaction mixture
and extract the organic layer with 100 ml of ethyl acetate.
Then, the organic layer is washed with 0.5N hydrochloric acid, 3% aqueous sodium carbonate solution and saturated saline in this order. After drying over magnesium sulfate, ethyl acetate was distilled off under reduced pressure to obtain 13 g of 2-acetoxy-5-norbornene. Next, 90% formic acid 50
and a mixture of 13 ml of 30% aqueous hydrogen peroxide under ice-cooling.
-13 g of acetoxy-5 norbornene is added dropwise, and the mixture is further stirred at room temperature for 12 hours. The formic acid was distilled off under reduced pressure, and 30 ml of methanol, 13 g of sodium hydroxide, and 25
Then, the mixture is reacted at 45 to 50 ° C. for 1 hour. After allowing to cool, the organic layer is extracted with 100 ml of ethyl acetate, and the organic layer is washed with brine and dried over magnesium sulfate. The solvent is distilled off under reduced pressure to give 2,3-dihydroxy-5 (6)-.
5 g of hydroxymethylnorbornane were obtained. IR (KB
r) 3380 (νO-H), 2950, 2860 (νC-
H), 1050 (νC-O) cm ^-1 (Example 1) (Evaluation of etching resistance of polymer) 2 g of the resin obtained in Synthesis Example 3 was dissolved in 10 g of ethyl lactate, and then a 0.2 μm Teflon filter was used. And filtered. Next, spin coating is performed on a 3-inch silicon substrate and baked on a hot plate at 90 ° C. for 60 seconds to form a film having a thickness of 0.7 μm.
Was formed. The obtained film was used as a DEM manufactured by Nidec Anelva.
The etching rate for CF ₄ gas was measured using a 451 reactive ion etching (RIE) apparatus (etching conditions: Power = 100 W, pressure = 5 P)
a, gas flow rate = 30 sccm). Table 5 shows the results. Similarly, the etching rate of the resin obtained in Synthesis Example 10 was measured. As comparative examples, novolak resist (PFI-15A manufactured by Sumitomo Chemical Co., Ltd.), poly (p-vinylphenol) used as a base resin of KrF resist, and a resin having no bridged cyclic hydrocarbon group in its molecular structure. The results for a poly (methyl methacrylate) coating film are also shown. The etching rate was standardized for the novolak resist.

[0035]

[Table 5] The above results indicate that the resin used in the present invention has a low etching rate with respect to CF ₄ gas and is excellent in dry etching resistance. (Example 2) (Evaluation of transparency of polymer) 2.5 g of resin obtained in Synthesis Example 3
Was dissolved in 10 g of ethyl lactate, and then filtered using a 0.2 μm Teflon (registered trademark) filter. Next, spin coating was performed on a 3-inch quartz substrate, and baked on a hot plate at 90 ° C. for 60 seconds to form a thin film having a thickness of 1 μm. The center wavelength of the ArF excimer laser light was 1 for this thin film using an ultraviolet-visible spectrophotometer.
The transmittance at 93.4 nm was measured. Similarly,
The resin obtained in Synthesis Example 10 was also measured. as a result,
The transmittance of the polymer obtained in Synthesis Example 3 was 53% / μm, and the transmittance of the polymer of Synthesis Example 10 was 57% / μm. from this result,
It was confirmed that the polymer of the present invention exhibited transparency usable as a single-layer resist. (Example 3) (Evaluation of patterning of resist using polymer 1) A resist solution having the following composition was prepared. (A) Polymer (Synthesis Example 3): 2 g (b) Photoacid generator (triphenylsulfonium triflate): 0.04 g (c) Ethyl lactate: 11.5 g Using a 0.2 μm Teflon filter, the above mixture was used. And filtered to prepare a resist solution. The above resist solution is spin-coated on a 4-inch silicon substrate,
Baking was performed on a hot plate for 1 minute to form a thin film having a thickness of 0.4 μm. Then, the wafer having the film formed thereon was allowed to stand in a contact-type exposure experiment machine sufficiently purged with nitrogen. A mask in which a pattern of chrome was drawn on a quartz plate was adhered to the resist film, and ArF excimer laser light was irradiated through the mask. Immediately thereafter, baked on a hot plate at 130 ° C. for 60 seconds, and 2.38% TMAH at a liquid temperature of 23 ° C.
Development was carried out by immersion in an aqueous solution for 60 seconds, followed by rinsing with pure water for 20 seconds. As a result, only the unexposed portion of the resist film was dissolved and removed in the developing solution to obtain a negative pattern. Synthesis Example 1
The resist using the polymer obtained in Step No. 0 was also evaluated.
Table 6 shows the results of sensitivity and resolution.

[0036]

[Table 6] (Example 4) (Evaluation of resist patterning using polymer 2) A resist having the following composition was prepared. (A) Polymer (Synthesis Example 3): 2 g (b) Polyhydric alcohol (Synthesis Example 11): 0.3 g (c) Photoacid generator (triphenylsulfonium triflate): 0.04 g (d) Ethyl lactate Exposure, baking, and development were performed in the same manner as in Example 3 to evaluate patterning. Similarly, a resist to which tricyclo [5.2.1.0 ^2,6 ] decane dimethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a polyhydric alcohol was also evaluated. Table 7 shows the results of sensitivity and resolution.

[0037]

[Table 7] From the results of Example 3 and Example 4, it was found that the negative photoresist material of the present invention had excellent resolution characteristics. In addition, since there was no phenomenon such as pattern peeling, it was confirmed that the substrate had excellent adhesiveness. It has also been found that the resolution and sensitivity are improved by adding a polyhydric alcohol.

[0038]

As is apparent from the above description, the negative photoresist material of the present invention has excellent dry etching resistance and transparency, and the negative photoresist material of the present invention has excellent resolution and substrate adhesion. Thus, it is possible to form a fine pattern required for manufacturing a semiconductor device.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views illustrating a method for forming a resist pattern according to the present invention.

[Explanation of symbols]

 1: substrate to be processed 2: resist film 3: mask 4: cross-linked area

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Etsuo Hasegawa 5-7-1 Shiba, Minato-ku, Tokyo F-term in NEC Corporation (Reference) 2H025 AA01 AA02 AA09 AB16 AC08 AD01 BD23 BE10 CB14 CB41 CB43 CB55 CC20 FA12 2H096 AA25 AA27 BA06 EA05 FA01 GA08

Claims (4)

[Claims] 1. A negative photoresist material comprising at least a polymer represented by the general formula (1) and a photoacid generator which generates an acid upon exposure. Embedded image (In the above formula, R ¹ , R ² , R ³ , R ⁵ are a hydrogen atom or a methyl group, R ⁴ is a C 3-13 hydrocarbon group having an epoxy group, and R ⁶ is a hydrogen atom or a carboxyl group. Represents a bridged cyclic hydrocarbon group having 7 to 13 carbon atoms, and x, y, and z are respectively x + y + z = 1, 0 <x <1, 0
Any number that satisfies <y <1, 0 <z <1. The weight average molecular weight of the polymer is 2,000 to 200,000.) 2. The negative photoresist material according to claim 1, wherein said material further contains a polyhydric alcohol. 3. A step of applying the photoresist material according to claim 1 on a substrate to be processed, a step of exposing the substrate to light having a wavelength of 180 to 220 nm,
A pattern forming method comprising at least a baking step and a developing step. 4. The pattern forming method according to claim 3, wherein the exposure light is ArF excimer laser light.