JP3199077B2 - Positive photosensitive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a positive photosensitive composition sensitive to radiation, and more particularly to a positive photosensitive composition having a high resolution and a good pattern shape.

[0002]

2. Description of the Related Art As the degree of integration of a semiconductor integrated circuit is generally increased four times in three years as generally known, for example, dynamic random access memory (DR)
AM) as an example, full-scale production has started at present with a storage capacity of 4 Mbits. As a result, the demand for photolithography technology, which is indispensable for the production of integrated circuits, is increasing year by year. For example, the production of a 4 Mbit DRAM requires a lithography technology at a level of 0.8 μm, and 16
It is anticipated that a 0.5 μm level lithography technique will be required in MDRAM. Most of the resists conventionally used in the photolithography technique are negative resists obtained by adding a bisazide compound as a crosslinking agent to a cyclized polyisoprene rubber. However, this type of resist has a limited resolution due to swelling during development, and it is difficult to obtain a resolution of 3 μm or more.

[0003] Positive photoresists can meet the above requirements. A positive photoresist contains an alkali-soluble resin and a photosensitive material, generally a compound containing a substituted naphthoquinonediazide group. Naphthoquinone diazide absorbs ultraviolet light upon irradiation, generates ketene via a carbene, and reacts with water present in the system to form indene carboxylic acid, which dissolves in the alkaline water of the developer.

As described above, since the positive type photoresist uses an alkaline aqueous solution as a developing solution, the resist does not swell unlike the negative type photoresist, and therefore the resolution can be increased. Thus, a positive photoresist is
In general, it has emerged as a resist characterized by non-swelling and high resolution as compared with a negative resist, and has been widely used in the manufacture of VLSI. However, the resolution of the conventionally used positive photoresist is insufficient for extremely fine processing of 0.5 μm or less.

Therefore, a conventional exposure technique using light in the visible or near-ultraviolet region can be used as it is, and it can respond to half-micron lithography, that is, a resolution of 0.5 μm.
There has been a strong demand for the development of a positive photoresist having a pattern profile of at least μm.

[0006]

In order to form a fine pattern in a good shape as a photoresist for VLSI manufacturing, the dissolution rate of an unexposed portion and a low exposure portion of the resist during development must be reduced. Must. This is because, in a reduction projection exposure apparatus generally used in the manufacture of VLSI, an optical image of a pattern of half a micron or less has a slight light wraparound even in a shadow portion of a mask, and the resist in that portion This is because the film is exposed to light. As a result, when the dissolution rate of the resist film portion, which should be left, in the developing solution is increased, the pattern shape is deteriorated. Therefore, it is necessary to minimize the dissolution rate of the unexposed portion and the low exposure portion in the developing solution.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resist composition which solves the above-mentioned problems of the prior art and which can respond to half-micron lithography using light in the visible or near ultraviolet region. is there. In order to solve such a problem, as a result of various studies, we have found that the use of a compound represented by the general formula (I) having a sterically large substituent as a photosensitizer makes it possible to obtain unexposed portions and Positive photoresist composition that has a low dissolution rate in the low exposure area, has a resolution of 0.4 μm or more, has a good pattern profile, and has other properties equal to or better than those of the conventional one. Have been found, and the present invention has been achieved.

That is, the gist of the present invention is to provide an alkali-soluble resin and a photosensitive agent represented by the following general formula (I):

[0009]

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(However, in the general formula (I), R ¹ , R
² , R ³ are a hydrogen atom, 1,2-naphthoquinonediazide-
4- sulfonyl represents a group or a 1,2-naphthoquinonediazide-5-sulfonyl group (wherein, R ^1, R ^2, at least one of R ³ is not a hydrogen atom.), R ^4, R
⁵ , R ⁶ and R ⁷ each may have a hydrogen atom, a C ₄ or more alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or a substituent. Represents an aryl group or an aralkyl group which may have a substituent (provided that at least one of R ⁴ and R ⁵ is not a hydrogen atom, and at least one of R ⁶ and R ⁷ is not a hydrogen atom .). ) Is contained in the positive photosensitive composition.

Hereinafter, the present invention will be described in detail. In the present invention, the compound represented by the general formula (I) is used as a photosensitive agent. In the compound represented by the general formula (I), alkyl, cycloalkyl, aryl or aralkyl, which is a substituent represented by R ⁴ , R ⁵ , R ⁶ or R ⁷ , is sterically large. Are preferred, and those having hydrophobicity are more preferred. Examples of the alkyl group, preferably a C ₄ or higher C ₂₀ an alkyl group, more preferably include an alkyl group of C ₄ or higher _of C ₁₀ or less, particularly n- butyl, s- butyl, t-
Examples include a butyl group, an n-pentyl group, a t-pentyl group, an n-hexyl group, a 1,1,3,3-tetramethylbutyl group, and the like.

[0012] Examples of the cycloalkyl group, preferably a C ₄ or higher C ₂₀ a cycloalkyl group, more preferably be a cycloalkyl group C ₅ or more _of C ₁₀ or less, specifically, a cyclohexyl group, a cyclopentyl group, etc. Is mentioned. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Examples of the aralkyl group include a benzyl group and a phenethyl group. The above R ⁴ , R ⁵ ,
The substituent represented by R ⁶ or R ⁷ is, for example, a methoxy group,
It may be substituted with an alkoxy group such as an ethoxy group, an alkylcarbonyloxy group such as an acetyloxy group or a propionyloxy group, a nitro group, or a halogen atom such as a chlorine atom.

The compound represented by the general formula (I) includes a compound in which R ¹ , R ² and R ³ are all hydrogen atoms;
It can be obtained by reacting 1,2-naphthoquinonediazide-4-sulfonyl chloride or 1,2-naphthoquinonediazide-5-sulfonyl chloride in the presence of a base catalyst. Compounds in which R ¹ , R ² , and R ³ are all hydrogen atoms to be reacted with 1,2-naphthoquinonediazidosulfonyl chloride can be obtained, for example, by subjecting a monovalent phenol having a sterically large substituent and hydroxybenzaldehyde to an acid catalyst. And a condensation reaction.

Examples of monovalent phenols having a sterically large substituent which can be used for synthesizing the compound represented by the general formula (I) include, for example, on-butylphenol and m-butylphenol.
-N-butylphenol, pn-butylphenol,
os-butylphenol, ms-butylphenol, ps-butylphenol, ot-butylphenol, mt-butylphenol, pt-butylphenol, pn-pentylphenol, pt-pentylphenol, pn-hexylphenol, or p
Alkylphenols such as-(1,1,3,3-tetramethylbutyl) phenol, o-cyclohexylphenol, m-cyclohexylphenol, o-cyclopentylphenol, p-cyclopentylphenol, p
-Cycloalkylphenols such as cyclohexylphenol, arylphenols such as o-phenylphenol, m-phenylphenol or p-phenylphenol, and aralkylphenols such as 2-hydroxydiphenylmethane or 4-hydroxydiphenylmethane.

By introducing such a sterically large substituent as R ₄ , R ₅ , R ₆ , and R ₇ , the effect of suppressing the dissolution of the unexposed portion by the photosensitive agent at the time of development becomes large, and the residue of the resist remains. The film ratio is increased, and a good pattern shape is obtained. The amount of the photosensitizer is preferably 0.1 to 50% by weight, more preferably 0.5 to 40% by weight, based on the solid of the photoresist. If the amount is too small, the resolving power and the pattern profile are degraded. If the amount is too large, the sensitivity is lowered.

In the present invention, as the alkali-soluble resin, any resin can be used as long as the exposed portion becomes alkali-soluble at the time of development and is eluted in an alkali developer, but preferably novolak resin, polyacrylic acid, polyvinyl alcohol, Polyvinyl phenol or a derivative thereof is used. Of these, a novolak resin is particularly preferred. Specifically, o-cresol,
One or two or more phenols such as m-cresol, p-cresol, 2,5-xylenol, and 3,5-xylenol are selected from aldehydes such as formaldehyde, acetaldehyde or propionaldehyde. A novolak resin condensed with at least one aldehyde is used.

Paraformaldehyde may be used instead of formaldehyde. The condensation is usually carried out using a carboxylic acid such as oxalic acid or citric acid, a mineral acid such as hydrochloric acid, sulfuric acid or phosphoric acid or a Lewis acid as a catalyst. The molecular weight of the alkali-soluble resin is generally 1,000 to 15,000, preferably 1,500 to 1 in terms of polystyrene (GPC measurement).
000 is used.

The photosensitive composition of the present invention is usually used by dissolving the above-mentioned photosensitizer and alkali-soluble resin in a suitable solvent. The solvent is not particularly limited as long as it has sufficient solubility in the photosensitizer and the resin and gives good coating properties, but is not particularly limited, and is a cellosolve-based solvent such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate. Solvents, ester solvents such as butyl acetate, amyl acetate, methyl lactate, ethyl lactate, methyl 3-methoxypropionate, highly polar solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, or a mixed solvent thereof, or further Those to which an aromatic hydrocarbon is added are exemplified.

The photosensitive composition of the present invention can be applied to a substrate by a conventional method, followed by drying, exposure, heating after exposure, and the like, followed by development to form a pattern. As a developer, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate,
Inorganic alkalis such as aqueous ammonia, ethylamine, n
Primary amines such as -propylamine; secondary amines such as diethylamine and di-n-propylamine; tertiary amines such as triethylamine and N, N-diethylmethylamine; tetramethylammonium hydroxide; A quaternary ammonium salt such as trimethylhydroxyethylammonium hydroxide or the like to which an alcohol, a surfactant or the like is added can be used.

The positive photosensitive composition of the present invention is useful not only for the production of VLSI, but also for general IC production, mask production, image formation, liquid crystal screen production or offset printing.

[0021]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Synthesis Example 1 5 ′, 5 ″ -di-t- was added to a 200 ml four-necked flask.
Butyl-2 ′, 2 ″, 4 ″ ″-trihydroxytriphenylmethane 8.1 g (20 mmol), 1,2-naphthoquinonediazide-5-sulfonyl chloride 16.1
2 g (60 mmol) and tetrahydrofuran 100
Then, the mixture was stirred and dissolved. To this solution, a solution of 6.2 g (61 mmol) of triethylamine dissolved in 5 ml of tetrahydrofuran was added dropwise over 5 minutes. After the completion of the dropwise addition, the reaction was carried out at room temperature for 3 hours. After completion of the reaction, the precipitated salt was separated by filtration, and the filtrate was poured into 1 liter of water to precipitate a photosensitive agent. The suspension is washed for 1 hour, the solid is filtered off and dried, and the following structural formula (II)

[0023]

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(In the formula, Q represents a 1,2-naphthoquinonediazido-5-sulfonyl group)
5 g (98% yield) were obtained. Synthesis Example 2 As in Synthesis Example 1, 5 ′, 5 ″ -diphenyl-
8.9 g (20 mmol) of 2 ', 2 ", 4"'-trihydroxytriphenylmethane, 16.1 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride (60
mmol) and 6.2 g (61 mm) of triethylamine.
ol) from the following structural formula (III)

[0025]

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(Wherein Q is the same as in formula (II)) 20.5 g (yield 90%) of a photosensitive agent represented by formula (II) was obtained.

Synthesis Example 3 As in Synthesis Example 1, 9.0 g (20 mmol) of 5 ′, 5 ″ -dicyclohexyl-2 ′, 2 ″, 4 ′ ″-trihydroxytriphenylmethane, -Naphthoquinonediazide-5-sulfonyl chloride 16.1 g
(60 mmol) and 6.2 g (6
1 mmol) from the following structural formula (IV)

[0028]

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(In the formula, Q is the same as that in the formula (II)) 21.3 g (yield 93%) of a photosensitive agent represented by the formula was obtained.

Synthesis Example 4 In the same manner as in Synthesis Example 1, 5 ′, 5 ″ -dimethyl-
6.4 g (20 mmol) of 2 ', 2 ", 4"'-trihydroxytriphenylmethane, 16.1 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride (60
mmol) and 6.2 g (61 mm) of triethylamine.
ol) and the following structural formula (V)

[0031]

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In the formula, 19.9 g (yield 98%) of a photosensitive agent represented by the formula (II) was obtained.

Synthesis Example 5 A mixture of 189 g (1.75 mol) of m-cresol, 236 g (2.19 mol) of p-cresol and 54 g (0.44 mol) of 2,5-xylenol was stirred at 91 ° C.
Heated. To this, 276.3 g of a 37% by weight aqueous solution of formaldehyde (3.40 mol of formaldehyde)
A solution prepared by dissolving 10.0 g (0.079 mol) of oxalic acid in 1) was added dropwise, and after completion of the addition, the mixture was reacted at 91 to 94 ° C. for 5 hours. After completion of the reaction, water and unreacted monomers were distilled off under reduced pressure while gradually increasing the bath temperature (final liquid temperature: 176 ° C,
30 mmHg). The product was allowed to cool, yielding 414 g of novolak resin. When this novolak resin was analyzed by GPC, the weight average molecular weight was 5,650.

Example 1 0.14 g (0.13 mmol) of the photosensitive agent synthesized in Synthesis Example 1
l) and 1.0 g of the novolak resin synthesized in Synthesis Example 5 were dissolved in 3.5 g of methyl 3-methoxypropionate,
The mixture was microfiltered using a 0.2 μm Teflon filter paper to prepare a photoresist composition. This photoresist composition was applied to a silicon wafer having a diameter of 5 inches using a spin coating apparatus (manufactured by Dainippon Screen) in an amount of 1.22.
μm, and after pre-baking on a hot plate at 80 ° C. for 90 seconds, an i-line reduction projection exposure apparatus (Nikon,
(NA = 0.50) and exposed on a hot plate.
After baking at 00 ° C. for 90 seconds, 23.38% aqueous solution of tetramethylammonium hydroxide was used.
A resist pattern was formed by developing at 60 ° C. for 60 seconds. The resolution was measured by observing the obtained resist pattern with a scanning electron microscope. The results are shown in Table 1. Since the photosensitive agent has a three-dimensionally large t-butyl group, the dissolution rate of the unexposed portion was suppressed, and the pattern of 0.32 μm was resolved in a good shape.

Example 2 In the same manner as in Example 1, the photosensitive agent 0.1 was synthesized in Synthesis Example 2.
A resist photosensitive solution was prepared from 15 g (0.13 mmol), 1.0 g of the novolak resin synthesized in Synthesis Example 5, and 3.5 g of methyl 3-methoxypropionate. The resolution was measured in the same manner as in Example 1. The results are shown in Table 1. Also in this case, since the photosensitive agent has a sterically large phenyl group, the dissolution rate of the unexposed portion is suppressed, and
m pattern was resolved with a good shape.

Example 3 In the same manner as in Example 1, the photosensitive agent synthesized in Synthesis Example 3 was added.
A resist photosensitive solution was prepared from 15 g (0.13 mmol), 1.0 g of the novolak resin synthesized in Synthesis Example 5, and 3.5 g of methyl 3-methoxypropionate. The resolution was measured in the same manner as in Example 1. The results are shown in Table 1. Also in this case, since the photosensitive agent has a three-dimensionally large cyclohexyl group, the dissolution rate of the unexposed portion is suppressed, and
A 36 μm pattern was resolved with a good shape.

Comparative Example 1 In the same manner as in Example 1, the photosensitive agent synthesized in Synthesis Example 4 was added.
A resist photosensitive solution was prepared from 13 g (0.13 mmol), 1.0 g of the novolak resin synthesized in Synthesis Example 5, and 3.5 g of methyl 3-methoxypropionate. The resolution was measured in the same manner as in Example 1. The results are shown in Table 1. In this case, since there is no sterically large substituent, the dissolution rate of the unexposed portion and the low exposure portion is increased,
Resolution was only possible up to 0.5 μm, and the pattern shape was also poor.

[0038]

[Table 1] * 1) Pattern shape: A and B correspond to the shapes shown in FIGS. 1A and 1B, respectively.

[0039]

The positive photosensitive composition of the present invention enables half-micron lithography using light in the visible or near-ultraviolet region, and is useful for the production of ultra LSI.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic cross-sectional views showing the shape of a resist pattern.

[Explanation of symbols]

 1 resist 2 substrate

────────────────────────────────────────────────── ─── Continuation of the front page (73) Patentee 596156668 455 Forest Street, Marlborough, MA 01752 U.S.A. S. A (72) Inventor Yasuhiro Kameyama 1000 Kamoshita-cho, Midori-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Research Institute (56) References JP-A-4-284454 (JP, A) JP-A-5-88363 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03F 7/022 H01L 21/027

Claims (2)

(57) [Claims] 1. An alkali-soluble resin and a photosensitive agent represented by the following general formula (I): (In the general formula (I), R ¹ , R ² , and R ³ represent a hydrogen atom, a 1,2-naphthoquinonediazide-4-sulfonyl group, or a 1,2-naphthoquinonediazide-5-sulfonyl group (provided that: At least one of R ¹ , R ² , and R ³ is not a hydrogen atom.), R ⁴ , R ⁵ , R ⁶ , R
⁷ is a hydrogen atom or a cycloalkyl which may have a substituent
Kill group, an optionally substituted aryl group or an optionally substituted aralkyl group, (provided that,
At least one of R ⁴ and R ⁵ is not a hydrogen atom, and at least one of R ⁶ and R ⁷ is not a hydrogen atom. ). A positive photosensitive composition comprising a compound represented by the formula: 2. The positive photosensitive composition according to claim 1, wherein the alkali-soluble resin is a novolak resin.