JP3036147B2 - Positive photoresist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION This invention relates to positive photoresist compositions and more particularly to the manufacture of high density integrated circuits which are sensitive to radiation such as ultraviolet, far ultraviolet, X-ray and electron beams. The present invention relates to a positive-type photoresist composition suitable as a resist for use.

[0002]

2. Description of the Related Art Positive photoresist compositions include:
A novolak resin using cresol as a raw material as a resin component, and a quinonediazide compound as a photosensitizer, particularly those containing 1,2-naphthoquinonediazide-5-sulfonic acid ester of polyhydroxybenzophenone, are known,
Used for integrated circuit manufacturing.

As the density of integrated circuits has increased in recent years, there has been a demand for a positive photoresist excellent in sensitivity, resolution, mask fidelity and heat resistance. However, for example, if the molecular weight of the novolak resin is reduced in order to improve the sensitivity, problems such as deterioration of the pattern shape, generation of scum, reduction of the remaining film ratio and heat resistance occur, and the like. At present, products that satisfy all performances have not yet been obtained.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive photoresist composition which eliminates the above-mentioned disadvantages of the prior art, has excellent resolution, sensitivity and heat resistance and is suitable as a resist for high-density integrated circuits. The purpose is to provide.

[0005]

The above object is achieved by the present invention described below.

The present invention relates to a novolak resin, a quinonediazide compound, and a phenol compound represented by the general formula (I) .
It is a positive photoresist composition characterized by containing a compound .

[0007]

Embedded image (Wherein R1 to R4 are a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and the sum of m and n is 5 or 6. ) The novolak resin used in the positive photoresist composition of the present invention is Any of those known in the art can be used. Such a novolak resin can be obtained by condensing a phenol, an aldehyde or a polymer of an aldehyde using an acid or a metal salt as a catalyst according to a conventional method.

Specific examples of phenols used as a raw material of the novolak resin include phenol, cresol, chlorophenol, xylenol, ethylphenol, butylphenol, resorcinol, naphthol, and the like. These may be used alone or in combination. Can be used. It is preferable to use cresol as the phenol, and particularly preferable is a mixture of m-cresol and p-cresol at a molar ratio of 20/80 to 80/20, and a mixture of m-cresol and 30/70 to 70/30. Is more preferred.

The aldehydes used as raw materials for the novolak resin include formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and the like, and the polymers of the aldehydes include paraformaldehyde, 1,3,5-trioxane, paraaldehyde and the like. Is mentioned. These can be used alone or as a mixture. It is particularly preferable to use formaldehyde as the aldehyde. It is also preferable to use paraformaldehyde or 1,3,5-trioxane as the polymer.

[0010] The condensation reaction is carried out without a solvent or in an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol and 1-butanol; cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate; Tetrahydrofuran,
Ethers such as 1,4-dioxane are preferably used.

As the catalyst for the condensation reaction, acids such as oxalic acid, formic acid, hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid and p-toluenesulfonic acid, and metal salts such as zinc acetate and magnesium acetate are preferably used.

The novolak resin thus obtained generally contains a low molecular weight component such as a binuclear product obtained by condensing two phenol units and a trinuclear product obtained by condensing three phenol units.
Among these low molecular weight components, there are components that cause scum and degrade the pattern shape. Therefore, the low molecular weight components are removed by an appropriate operation, and the binuclear and trinuclear components are contained. It is preferable that the total amount be 10% or less.

The following method can be used to remove low molecular weight components from the novolak resin. (1) Extraction method Novolak resin is pulverized finely, and benzene, toluene,
A low molecular weight component is extracted by stirring at a certain temperature with an organic solvent such as xylene, chlorobenzene and dichlorobenzene, or water, or a mixed solution of water and an organic solvent such as methanol and ethanol. (2) Reprecipitation method Novolak resin was treated with methanol, ethanol, acetone,
Dissolve in organic solvents such as ethyl cellosolve. Then
A poor solvent such as water, petroleum ether, or hexane is dropped into the novolak solution, or a novolak solution is dropped into the poor solvent to precipitate and separate a novolak resin, followed by drying. (3) Separation method Novolak resin was treated with methanol, ethanol, acetone,
Dissolve in a mixed solvent of a water-miscible organic solvent such as ethyl cellosolve and a water-immiscible organic solvent such as ethyl cellosolve acetate and propylene glycol monomethyl ether acetate, add water dropwise to separate two layers, and separate the organic layer. And concentrate.

The positive photoresist composition of the present invention contains a quinonediazide compound as a photosensitizer component. Here, the quinonediazide compound is a compound in which one carbonyl oxygen of orthoquinone is substituted with a diazo group. Examples of the quinonediazide compound preferably used include an ester of a compound having a hydroxyl group and naphthoquinonediazidesulfonic acid. Specific examples of the compound having a hydroxyl group include hydroquinone, resorcinol, pyrocatechol, phloroglucin, pyrogallol,
4,4'-dihydroxybenzophenone, 2,4'-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2 ', 4,4'-tetra Hydroxybenzophenone, 2,3,3 ′, 4-tetrahydroxybenzophenone, 2,2 ′, 3,4-tetrahydroxybenzophenone, 2,2 ′, 3,4,4′-pentahydroxybenzophenone, 2,3,3 ', 4,4',
5'-hexahydroxybenzophenone, alkyl gallate, 2,4'-dihydroxybiphenyl,
4,4′-dihydroxybiphenyl, 2,4′-dihydroxydiphenylmethane, 2,2′-dihydroxydiphenylmethane, bisphenol F, bisphenol A,
Examples include bisphenol B, bisphenol Z, bisphenol S, quercetin, low molecular weight novolak, and the like. In the ester of a compound having a plurality of hydroxyl groups and naphthoquinonediazidosulfonic acid, the hydroxyl group may be completely esterified or partially esterified, or may be a mixture of those having different degrees of esterification. These may be used alone or in combination of a plurality of different structures.

Among the ester of a compound having a hydroxyl group and naphthoquinonediazidosulfonic acid, the hydroxyl groups of trihydroxybenzophenone, tetrahydroxybenzophenone, pentahydroxybenzophenone and hexahydroxybenzophenone are on average 75% or more, and 1,2-naphthoquinonediazide- Those esterified with 5-sulfonic acid or 1,2-naphthoquinonediazide-4-sulfonic acid are particularly preferably used.

The content of the quinonediazide compound in the solid content of the positive photoresist composition of the present invention is preferably from 10 to 50% by weight, and more preferably from 15 to 30% by weight.

The positive photoresist composition of the present invention further contains a phenol compound represented by the general formula (I) . Next, specific examples of the compound represented by formula (I) are shown below, but the present invention is not limited thereto.

[0018]

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Embedded image The phenol compounds represented by the general formula (I) may be used alone or in combination. The total content of the phenolic compound represented by the general formula (I) in the solid content of the positive photoresist composition of the present invention is 3 to 3 because the effect of improving sensitivity is large and the composition has good heat resistance.
It is preferably 30% by weight, more preferably 5 to 15% by weight.

The positive photoresist composition of the present invention comprises:
Above mentioned novolak resin, quinonediazide compound, one
It is obtained by dissolving a phenol compound represented by the general formula (I) in a solvent. Further, additives such as a dye, a surfactant, a stabilizer, and a sensitizer can be appropriately added to the positive photoresist composition of the present invention.

As the solvent, an organic solvent capable of dissolving each of the above components is used. Specifically, ethyl acetate, butyl acetate, amyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl benzoate,
Esters such as methyl lactate and ethyl lactate; cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; cellosolve esters such as methyl cellosolve acetate, ethyl cellosolve acetate and butyl cellosolve acetate; propylene glycol monomethyl ether acetate; propylene glycol monoethyl ether acetate Propylene glycol ether esters such as 1,2-dimethoxyethane, 1,2-
Diethoxyethane, tetrahydrofuran, 1,4-dioxane, ethers such as anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ketones such as isophorone, dimethylformamide, dimethylacetamide, amides such as N-methylpyrrolidone, dimethyl sulfoxide, Solvents selected from aprotic polar solvents such as sulfolane, or solvents obtained by mixing a plurality of these solvents.

When a fine pattern is formed using the positive photoresist composition of the present invention, it is preferable to perform an operation of heating the substrate after exposure and before development, that is, post exposure baking. By this operation, sensitivity and contrast are increased, and a pattern with less scum and a good cross-sectional shape can be obtained. The heating method in the post-exposure bake operation is not particularly limited,
For example, there is a method using a hot plate or an oven. The heating temperature is preferably in the range of 90 to 140C,
The range of 100-130 degreeC is more preferable. When using a hot plate as the heating means, the heating time is 0.5
5 minutes is preferable, and 0.7-2 minutes is more preferable.
When an oven is used, the heating time is preferably from 1 to 60 minutes, more preferably from 5 to 30 minutes.

[0022]

The present invention will be specifically described below with reference to examples. Example 1 A novolak resin was obtained from 35 parts of m-cresol, 65 parts of p-cresol, 0.5 part of oxalic acid and 46 parts of 37% formalin by a conventional method. 10 parts of this novolak resin was dissolved in 50 parts of methanol, and 40 parts of water was added dropwise with stirring.
Novolak was precipitated. The supernatant was removed by decantation, and the precipitated novolak was taken out.
Dried for hours. 8.6 parts of novolak resin were obtained.
Next, using this novolak, a positive photoresist composition having the following composition was prepared.

(1) Novolak resin obtained by the above method
18.98 parts (2) Exemplary compound (I-1) 1.82 parts (3) Photosensitizer (2,3,4,4'-tetrahydroxybenzophenone is averaged with 1,2-naphthoquinonediazide-5-sulfonic acid 3.8 mol esterified) 5.2
0 parts (4) Surfactant ("Troysol" 366, TOROY CH
(Manufactured by EMICAL) 0.05 part (5) Solvent (ethyl cellosolve acetate) 74.0 parts This positive photoresist composition was filtered using a 0.2 μm membrane filter, and then filtered using a spinner.
After spin coating on an inch silicon wafer, it was prebaked on a hot plate at 90 ° C. for 1 minute to form a coating film having a thickness of 1.16 μm. Next, after exposing the test pattern using a g-line stepper (NSR1505G6E manufactured by Nippon Kogaku Co., Ltd.), post-exposure bake is performed on a hot plate at 110 ° C. for 1 minute, and a 2.38% aqueous solution of tetramethylammonium hydroxide is used. Paddle development was performed at 23 ° C. for 1 minute, followed by washing with water and spin drying. The obtained resist pattern was evaluated with a scanning electron microscope. As a sensitivity evaluation, an exposure amount required for resolving a 0.5 μm line and space at 1: 1 was obtained.
It was 140 mJ / cm ² . 3μ as heat resistance evaluation
The line and space pattern of m was 130 ° C. when the highest temperature at which the pattern was not rounded by heat treatment on a hot plate for 5 minutes was found. The residual film ratio determined from the ratio of the film thickness before and after the development was 99.5%.

Comparative Example 1 The novolak resin used in Example 1 was used in an amount of 20.8 parts by weight.
Add 5.2 parts by weight of lightening agent and do not add phenolic compound.
Other than that, the positive photoresist assembly was the same as in Example 1.
The product was prepared and evaluated in a similar manner. For heat resistance evaluation
Was 130 ° C. The residual film ratio is 99.7%.
However, a 0.5 μm line as shown in Example 1
Exposure required to resolve 1: 1 space and space
The dose required 217 mJ / cm ² .

[0025]

Positive photoresist composition of the present invention exhibits, by adopting a novel composition that contains a phenol compound represented by the general formula (I), the resolution, sensitivity and heat resistance conventional positive It will be better than the photoresist composition. Therefore, according to the present invention, a positive photoresist composition suitable as a highly integrated resist for integrated circuits can be easily obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-44439 (JP, A) JP-A-2-248955 (JP, A) JP-A-2-163740 (JP, A) JP-A-2- 275453 (JP, A) JP-A-2-248954 (JP, A) JP-A-2-191248 (JP, A) JP-A-3-279959 (JP, A) JP-A-5-34911 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03F 7/022 G03F 7/004 H01L 21/027

Claims (1)

(57) [Claims] 1. A novolak resin, a quinonediazide compound,
And a phenol compound represented by the general formula (I)
A positive photoresist composition, comprising: Embedded image (In the formula, R1 to R4 are a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and the sum of m and n is 5 or 6. )