JPH0659446A - Positive resist composition - Google Patents

Abstract

PURPOSE:To provide a positive resist compsn. excellent in balance of various characteristics such as sensitivity, residual film rate and resolution, causing a small dimensional change to exposure especially in <=1mum fine working and giving an excellent pattern shape. CONSTITUTION:This positive resist compsn. contains alkali-soluble phenolic resin, a quinonediazidosulfonic ester type photosensitive agent and a hydroxy compd. represented by the formula, wherein each of R1-R4 is H, halogen, hydroxyl, 1-8C alkyl, 2-5C alkenyl, 1-4C alkoxy or phenyl substd. alkoxy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist composition, and more particularly to a positive resist composition for microfabrication used for manufacturing semiconductor devices, magnetic bubble memory devices, integrated circuits and the like.

[0002]

2. Description of the Related Art To form a fine pattern using a resist, a solution containing a photosensitive material is applied onto a substrate,
A lithographic technique is employed in which, after being dried to form a photosensitive film, an actinic ray is irradiated through a mask pattern to form a latent image, and then the latent image is developed to form an image. Resist is generally classified into positive type and negative type,
In the positive type, the irradiated portion has a higher solubility in the developing solution than in the unirradiated portion to give a positive type image, and in the negative type, the solubility of the irradiated portion decreases to give a negative type image.

In the case of manufacturing a semiconductor, a silicon wafer is used as a substrate, an image (pattern) is formed on the substrate by the above-mentioned lithography technique, and then etching is performed using the resist film remaining on the substrate as a protective film. After that, a semiconductor element is formed by a method of removing the resist film.

Conventionally, as a resist for forming a semiconductor element, a negative resist composed of a cyclized polyisoprene and a bisdiazide compound has been known. However, since the resist is developed with an organic solvent, the resist film swells greatly and the resolution is high. Since it has a limit in the property, it has a drawback that it cannot be applied to the manufacture of highly integrated semiconductor devices.

On the other hand, a positive resist containing an alkali-soluble novolac resin and a quinonediazide compound and using an alkaline aqueous solution as a developing solution is excellent in resolution because it does not swell with the developing solution. Widely used in the manufacture of integrated semiconductor devices. The improvement in the performance of the positive resist and the improvement in the performance of the exposure device have improved the resolution, and it has become possible to form a fine pattern of 1 μm or less.

By the way, in forming a fine pattern of 1 μm or less, particularly 0.8 μm or less, it is necessary to more strictly control the dimensions of the resist pattern. However, satisfactory results have not always been obtained with the conventional positive resists, and there has been a strong demand for positive resists having good dimensional controllability.

Further, in the formation of a fine pattern of 1 μm or less, particularly 0.7 μm or less, the wavelength is shorter and the resolution and the focus margin are better than those of the minute projection exposure method using g-line (436 nm) which has been widely used conventionally. I line (365
nm) exposure schemes are beginning to be used. However, in the conventional positive type resist, exposure with i-line has low transparency to the exposure light, so that it is difficult to obtain sufficient exposure energy at the resist bottom portion, and as a result, the pattern shape may deteriorate. Yes, there was a need for improvement.

[0008]

An object of the present invention is to provide a positive resist composition having an excellent balance of various characteristics such as sensitivity, residual film ratio and resolution. Another object of the present invention is to provide a positive resist composition which is excellent in so-called exposure margin (exposure latitude), which has a small dimensional change with respect to the exposure amount, particularly in fine processing of 1 μm or less, and which has an excellent pattern shape. .

As a result of intensive studies to overcome the problems of the prior art, the present inventors have found that cyclopentane in a positive resist composition containing an alkali-soluble phenol resin and a quinonediazide sulfonic acid ester-based photosensitizer. It was found that the above object can be achieved by containing a hydroxy compound having a structure in which two aromatic groups having a hydroxyl group are bonded to one carbon atom, and based on this finding, the present invention has been completed.

[0010]

Thus, according to the present invention, an alkali-soluble phenol resin (a), a quinonediazide sulfonic acid ester-based photosensitizer (b), and a hydroxy compound (c) represented by the following general formula [I] are used. The positive resist composition is provided.

[0011]

[Chemical 2] (R _{1 to} R ₄ : hydrogen atom, halogen atom, hydroxyl group, alkyl group having 1 to 8 carbon atoms, alkenyl group having 2 to 5 carbon atoms, alkoxy group having 1 to 4 carbon atoms, or phenyl-substituted alkoxy group And each may be the same or different).

The present invention will be described in detail below. Alkali-soluble phenol resin (a) Examples of the alkali-soluble phenol resin used in the present invention include condensation reaction products of phenols and aldehydes, condensation reaction products of phenols and ketones, and vinylphenol polymers. , Isopropenylphenol-based polymers, hydrogenation reaction products of these phenolic resins, and the like.

Specific examples of the phenols used here include monohydric phenols such as phenol, cresol, xylenol, ethylphenol, propylphenol, butylphenol and phenylphenol, resorcinol, pyrocatechol, hydroquinone, bisphenol A and phlolog. Examples include polyphenols such as lucinol and pyrogallol. Specific examples of aldehydes include formalin, paraformaldehyde, acetaldehyde, benzaldehyde, and terephthalaldehyde. Specific examples of the ketones include acetone, methyl ethyl ketone, diethyl ketone, diphenyl ketone and the like. These condensation reactions can be performed according to a conventional method.

The vinylphenol polymer is selected from a homopolymer of vinylphenol and a copolymer of vinylphenol and a component copolymerizable with vinylphenol. Specific examples of the copolymerizable component include acrylic acid, methacrylic acid, styrene, maleic anhydride, maleic imide, vinyl acetate,
Examples thereof include acrylonitrile and derivatives thereof.

The isopropenylphenol-based polymer is selected from homopolymers of isopropenylphenol and copolymers with a component copolymerizable with isopropenylphenol. Specific examples of the copolymerizable component include acrylic acid, methacrylic acid, styrene, maleic anhydride, maleic imide, vinyl acetate, acrylonitrile, and derivatives thereof.

The hydrogenation reaction product of the phenolic resin is
It can be produced by any known hydrogenation reaction, specifically, a phenol resin is dissolved in an organic solvent,
It can be obtained by introducing hydrogen in the presence of a homogeneous or heterogeneous hydrogenation catalyst.

These alkali-soluble phenolic resins can be used as they are, but those having a controlled molecular weight or molecular weight distribution by fractionation by known means may be used. As a method of separating the resin for the purpose of controlling the molecular weight and the molecular weight distribution, the resin is crushed and solid-liquid extracted with an organic solvent having an appropriate solubility, or the resin is dissolved in a good solvent,
Drop it into the poor solvent or drop the poor solvent to
Examples include liquid or liquid-liquid extraction methods. These alkali-soluble phenol resins may be used alone or in combination of two or more.

The positive resist composition of the present invention contains, for example, styrene and acrylic acid, methacrylic acid or maleic anhydride in order to improve developability, storage stability, heat resistance and the like, if necessary. A copolymer, a copolymer of an alkene and maleic anhydride, a vinyl alcohol polymer, a vinylpyrrolidone polymer, rosin, shellac and the like can be added. The addition amount of these is usually 0 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the alkali-soluble phenol resin.

Quinonediazidesulfonic acid ester-based photosensitizer (b) The photosensitizer used in the present invention is not particularly limited as long as it is a quinonediazidesulfonic acid ester. Such a quinonediazide sulfonic acid ester is obtained by converting quinonediazide sulfonic acid to sulfonyl chloride with chlorosulfonic acid according to a conventional method and condensing the obtained quinone diazide sulfonyl chloride with a hydroxy compound. For example, a hydroxy compound and 1,2
-Dissolve a predetermined amount of naphthoquinonediazide-5-sulfonyl chloride in a solvent such as dioxane, acetone or tetrahydrofuran, and add a basic catalyst such as triethylamine, pyridine, sodium carbonate, sodium hydrogen carbonate, sodium hydroxide or potassium hydroxide. A quinonediazide sulfonic acid ester can be prepared by reacting and washing the resulting product with water and drying.

The hydroxy compound used here is not particularly limited and, for example, a known compound having a phenolic hydroxyl group can be used. As a typical example, 2,3,4-trihydroxybenzophenone,
2,4,4'-trihydroxybenzophenone, 2,
3,4,4'-tetrahydroxybenzophenone, 2,
4,2 ', 4'-tetrahydroxybenzophenone,
Polyhydroxybenzophenones such as 2,3,4,2 ′, 4′-pentahydroxybenzophenone; gallic acid esters such as methyl gallate, ethyl gallate, propyl gallate; 2,2-bis (4-hydroxyphenyl) )
Polyhydroxybisphenylalkanes such as propane and 2,2-bis (2,4-dihydroxyphenyl) propane; tris (4-hydroxyphenyl) methane, tris (3-methyl-4-hydroxyphenyl) methane, 1,
1,1-tris (4-hydroxyphenyl) ethane,
1,1-bis (3-methyl-4-hydroxyphenyl)
Polyhydroxytrisphenylalkanes such as -1- (4-hydroxyphenyl) ethane; 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,
Polyhydroxytetrakisphenylalkanes such as 2,2-tetrakis (3-methyl-4-hydroxyphenyl) ethane and 1,1,3,3-tetrakis (4-hydroxyphenyl) propane; α, α, α ′, α ′ -Tetrakis (4-hydroxyphenyl) -3-xylene, α,
Polyhydroxytetrakis such as α, α ′, α′-tetrakis (4-hydroxyphenyl) -4-xylene, α, α, α ′, α′-tetrakis (3-methyl-4-hydroxyphenyl) -4-xylene Examples include phenylxylenes.

The quinonediazide sulfonic acid ester moiety of the photosensitizer used in the present invention is not particularly limited, but for example, 1,2-benzoquinonediazide-4-
Sulfonic acid ester, 1,2-naphthoquinonediazide-
O-quinonediazide sulfone such as 4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,1-naphthoquinonediazide-4-sulfonic acid ester and 2,1-naphthoquinonediazide-5-sulfonic acid ester Examples thereof include acid esters and other quinonediazide sulfonic acid esters.

The quinonediazide sulfonic acid ester type photosensitizer used in the present invention may be used alone or in combination of two or more kinds. The amount of the photosensitizer is usually 1 to 100 parts by weight, preferably 3 to 40 parts by weight, based on 100 parts by weight of the alkali-soluble phenol resin.
Parts by weight. If the amount is less than 1 part by weight, it becomes difficult to form a pattern, and if it exceeds 100 parts by weight, the sensitivity is lowered and the undeveloped portion is apt to occur.

In the present invention, the hydroxy compound (c) represented by the general formula [I] is excellent in balance of various characteristics such as sensitivity, residual film rate and resolution, and particularly, the exposure margin (exposure latitude) and the pattern shape are improved. In order to obtain the positive resist composition described above, the hydroxy compound represented by the above general formula [I] is used. Specific examples of the hydroxy compound (c) used in the present invention include the following compounds.

[0024]

[Chemical 3]

[0025]

[Chemical 4]

[0026]

[Chemical 5]

[0027]

[Chemical 6]

[0028]

[Chemical 7]

[0029]

[Chemical 8]

[0030]

[Chemical 9]

[0031]

[Chemical 10]

[0032]

[Chemical 11]

[0033]

[Chemical 12]

[0034]

[Chemical 13]

[0035]

[Chemical 14]

[0036]

[Chemical 15]

[0037]

[Chemical 16]

[0038]

[Chemical 17]

[0039]

[Chemical 18]

[0040]

[Chemical 19]

[0041]

[Chemical 20]

[0042]

[Chemical 21]

The hydroxy compound (c) can be used alone or in combination of two or more kinds. Further, it can be used in combination with other hydroxy compounds as long as the effects of the present invention are not impaired. The amount of the hydroxy compound (c) used in the present invention is usually in the range of 1 to 100 parts by weight with respect to 100 parts by weight of the alkali-soluble phenol resin. The preferred blending amount of the hydroxy compound (c) varies depending on the composition, the molecular weight, the molecular weight distribution of the alkali-soluble phenol resin (a), the kind of the photosensitizer (b), etc., but is generally 3 to 6.
A range of 0 parts by weight is preferred. If this blending amount is too small, the effect of the present invention cannot be exhibited, and conversely, if it is too large,
The resolution and heat resistance may decrease.

Positive Resist Composition The positive resist composition of the present invention is usually used by dissolving each of the above components in a solvent in order to form a resist film by coating on a substrate. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, cyclohexanone, and cyclopentanone; alcohols such as n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, and cyclohexanol; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dioxane. Ethers such as; ethylene glycol monomethyl ether, alcohol ethers such as ethylene glycol monoethyl ether; propyl formate, butyl formate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl lactate,
Esters such as ethyl lactate; cellosolve acetate,
Cellosolve esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate; propylene glycol such as propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monobutyl ether. Diethylene glycols such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether;
Halogenated hydrocarbons such as trichlorethylene; aromatic hydrocarbons such as toluene and xylene; polar solvents such as dimethylacetamide, dimethylformamide, N-methylacetamide; and the like. These solvents may be used alone or in combination of two or more. The amount of solvent used is sufficient to uniformly dissolve the above components.

Therefore, the preferred embodiment of the positive resist composition of the present invention is 100 parts by weight of the alkali-soluble phenol resin (a), 1 to 100 parts by weight of the quinonediazide sulfonic acid ester type photosensitizer (b), and the above-mentioned general formula [I]. ]
1 to 100 parts by weight of the hydroxy compound (c) represented by
And a composition containing a sufficient amount of a solvent to dissolve each of these components. The positive resist composition of the present invention includes
If necessary, compatible additives such as dyes, surfactants, storage stabilizers, sensitizers, antistriation agents, and plasticizers can be added.

An aqueous solution of alkali is used as a developer for the positive resist composition of the present invention. Specifically, sodium hydroxide, potassium hydroxide, sodium silicate,
Inorganic alkalis such as ammonia; primary amines such as ethylamine and propylamine; secondary amines such as diethylamine and dipropylamine; trimethylamine,
Tertiary amines such as triethylamine, alcohol amines such as dimethylmethanolamine, triethanolamine; tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylhydroxymethylammonium hydroxide, triethylhydroxymethylammonium hydroxide, trimethylhydroxyethylammonium Examples thereof include quaternary ammonium salts such as hydroxide. Further, if necessary, in the alkaline aqueous solution, methanol, ethanol, propanol, a water-soluble organic solvent such as ethylene glycol,
An appropriate amount of a surfactant, a storage stabilizer, a resin dissolution inhibitor, etc. can be added.

[0047]

EXAMPLES The present invention will be specifically described below with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to these examples. The parts and% in these examples are based on weight unless otherwise specified.

The resist evaluation methods in the following examples and comparative examples are as follows. (1) Sensitivity The exposure time (msec) that can form a 1: 1 line & space pattern having a sensitivity of 0.60 μm according to the design dimension is shown. (2) Resolution This represents the limit resolution (μm) under the above exposure conditions. (3) Residual film ratio This represents the ratio (%) of the resist film thickness before and after development. (4) Exposure margin (exposure latitude) The relationship between the exposure time and the pattern dimension of 0.60 μm is graphed, and the variation of the exposure time that can maintain the variation of the pattern dimension within ± 5% of the design dimension is calculated. It is the amount divided by the sensitivity. (5) Pattern shape The results obtained by slicing the wafer on which the resist pattern was formed from the direction perpendicular to the line pattern and observing the cross section of the pattern with an electron microscope were shown. When the side wall of the pattern stood up at an angle of 80 ° or more with respect to the substrate and there was no film reduction, it was judged as “good”. Those with a small amount of film loss are designated as "small film loss", and those with a large amount are designated as "large film loss"
And

[Synthesis Example 1] Synthesis of novolak resin (a-1) In a 2 liter flask equipped with a cooling tube and a stirrer,
356 g of m-cresol, 356 g of p-cresol, 3
348 g of 7% formalin, and oxalic acid dihydrate 2.4
9 g was charged, and the reaction was performed for 2 hours while maintaining the temperature at 95 to 100 ° C. After that, water is distilled off at 100 to 105 ° C. for 2 hours, and the temperature is further raised to 180 ° C. for 10 to 3
After reducing the pressure to 0 mmHg to remove unreacted monomers and water, the molten resin was returned to room temperature and recovered to obtain 525 g of novolak resin (a-1). The polystyrene-converted weight average molecular weight of this novolak resin measured by gel permeation chromatography (GPC) was 7,000.

Synthesis Example 2 Synthesis of Novolac Resin (a-2) In a 2 liter flask equipped with a cooling tube and a stirrer,
m-cresol 392g, p-cresol 320g, 3
380 g of 7% formalin, and oxalic acid dihydrate 2.4
8 g was charged, and the reaction was performed for 2 hours while maintaining the temperature at 95 to 100 ° C. After that, water is distilled off at 100 to 105 ° C. for 2 hours, and the temperature is further raised to 180 ° C. for 10 to 3
After the pressure was reduced to 0 mmHg to remove unreacted monomers and water, the temperature was returned to room temperature to obtain 540 g of novolac resin. To this resin, 400 g of ethyl cellosolve acetate was added and dissolved. Attach the dropping funnel to the flask and adjust the temperature to 80 ~.
Toluene 2700 from the dropping funnel while controlling at 90 ° C
g was added dropwise and heating was continued for another hour. Slowly cool to room temperature,
It was left still for 1 hour. After removing the supernatant liquid of the precipitated resin by decantation, 500 g of ethyl cellosolve acetate was added, and the mixture was added at 10 mmHg to 10%.
Residual toluene was removed by heating at 0 ° C. to obtain a solution of novolak resin (a-2) in ethyl cellosolve acetate.
The polystyrene reduced weight average molecular weight of this novolak resin by GPC was 12,500.

Synthesis Example 3 Synthesis of Photosensitizer (b-1) Tris (p-hydroxyphenyl) methane was used as the polyhydroxy compound, and 1,2-naphthoquinonediazide was added in an amount corresponding to 85 mol% of this hydroxyl group. -5-sulfonic acid chloride was dissolved in dioxane to give a 10% solution. While controlling the temperature to 20-25 ° C, 1,2-
Triethylamine equivalent to 1.2 equivalents of naphthoquinonediazide-5-sulfonic acid chloride was added dropwise over 30 minutes, and the reaction was completed by maintaining it for 4 hours. The precipitated salt was separated by filtration and put into a 0.2% oxalic acid aqueous solution which was 10 times as much as the reaction solution. The precipitated solid content was filtered, washed with ion-exchanged water, and dried to obtain a quinonediazide sulfonic acid ester-based photosensitizer (b-1).

Synthesis Example 4 Synthesis of Photosensitizer (b-2) 1,1-bis (3-methyl-4-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane was used as the polyhydroxy compound. 1,2-naphthoquinonediazide-5-sulfonic acid chloride corresponding to 80 mol% of this hydroxyl group was dissolved in dioxane to prepare a 10% solution. After this, the photosensitizer (b
-2) was obtained.

[Synthesis Example 5] Synthesis of Photosensitizer (b-3) As the polyhydroxy compound, α, α, α ', α'-tetrakis (p-hydroxyphenyl) -p-xylene was used. Mol% 1,2-naphthoquinonediazide-5-sulfonic acid chloride was dissolved in dioxane to give a 10% solution. After this, Synthesis Example 3
Photosensitizer (b-3) was obtained by the same formulation.

Examples 1 to 10 Alkali-soluble phenolic resin (a) having the composition shown in Table 1, quinonediazide sulfonic acid ester type photosensitizer (b) and hydroxy compound (c) were dissolved in ethyl cellosolve acetate, 1.
The amount of solvent blended was adjusted so that the coating could be applied to a film thickness of 2 μm.
In the case of using the novolac resin (a-2), the solid content concentration of the resin solution was measured in advance, and the solid content was adjusted based on the solid content. These solutions were filtered with a 0.1 μm polytetrafluoroethylene (registered trademark Teflon) filter to prepare a resist solution.

After coating the above resist solution on a silicon wafer with a coater, prebaking was performed at 90 ° C. for 90 seconds to form a resist film having a thickness of 1.17 μm. This wafer was exposed using an i-line stepper NSR1755i7A (manufactured by Nikon Corporation, NA = 0.50) and a test reticle while varying the exposure time, and then at 60 ° C. at 110 ° C.
Second exposure bake (Post Exposure Ba
king). Next, it was developed by a paddle method at 23 ° C. for 1 minute with a 2.38% tetramethylammonium hydroxide aqueous solution to form a positive pattern. This wafer was taken out and observed with an electron microscope, the resolution and the pattern dimension were measured, and the resist was evaluated. The results are shown in Table 1.

Comparative Examples 1-2 Hydroxy compound (c)
A resist solution was prepared and evaluated in the same manner as in Examples 1 to 10 except that was not used. Table 1 shows the composition of the resist and the evaluation results.

[0057]

[Table 1]

[0058]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a positive resist composition having excellent sensitivity, residual film ratio, resolution and dimensional controllability. The positive resist of the present invention is particularly suitable for fine processing of 1 μm or less.

Continued Front Page (72) Inventor Toshiaki Fujii 1-2-1 Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa Inside Zeon Corporation R & D Center

Claims (1)

[Claims] 1. An alkali-soluble phenolic resin (a),
Quinonediazide sulfonic acid ester-based photosensitizer (b) and hydroxy compound (c) represented by the following general formula [I]
A positive resist composition containing: [Chemical 1] (R _{1 to} R ₄ : hydrogen atom, halogen atom, hydroxyl group, alkyl group having 1 to 8 carbon atoms, alkenyl group having 2 to 5 carbon atoms, alkoxy group having 1 to 4 carbon atoms, or phenyl-substituted alkoxy group And each may be the same or different)