JP2568867B2 - Positive photoresist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a radiation-sensitive positive photoresist, particularly for fine processing having a high resolution and sensitivity, and a good pattern cross-sectional shape. The present invention relates to a photoresist composition. The positive photoresist according to the present invention is applied to a semiconductor wafer or a substrate made of glass, ceramics, metal or the like by a spin coating method or a roller coating method to a thickness of 0.5 to 3 μm. Then heating,
After drying, a circuit pattern or the like is baked through an exposure mask by ultraviolet irradiation or the like, and developed to obtain a positive image.
Further, pattern processing can be performed on the substrate by performing etching using the positive image as a mask. Typical application fields are semiconductor manufacturing processes such as ICs, manufacturing of circuit boards such as liquid crystals and thermal heads, and other photo-fabrication processes.

<Prior Art> As a positive photoresist composition, a composition containing an alkali-soluble resin and a naphthoquinonediazide compound as a photosensitive material is generally used. For example, US Pat. No. 3,666,473, US Pat. No. 4,115,128, and US Pat. No. 3,666,473 as “Novolak-type phenolic resin / naphthoquinonediazide-substituted compound”
No. 4173470, and the most typical composition is a "novolak resin comprising cresol-formaldehyde /
An example of “trihydroxybenzophenone-1,2-naphthoquinonediazidesulfonic acid ester” is Thompson “Introduction to Microlithography” (L.
F. Thompson "Introduction to Microlithography")
(ACS Publishing, No. 219, pp. 112-121).

Novolak resin as a binder is soluble in an alkaline aqueous solution without swelling, and is particularly useful in this application because it gives high resistance to plasma etching especially when the generated image is used as a mask for etching. It is. Further, the naphthoquinonediazide compound used in the photosensitive material itself acts as a dissolution inhibitor that reduces the alkali solubility of the novolak resin, but when decomposed by irradiation with light, generates an alkali-soluble substance and rather increases the alkali solubility of the novolak resin. It is unique in that it acts to enhance it, and is particularly useful as a photosensitive material for a positive photoresist because of its large property change to light.

From this point of view, a number of positive photoresists containing novolak resin and naphthoquinonediazide-based photosensitive materials have been developed and put into practical use, and sufficient results have been achieved in line width processing down to about 1.5 μm / 2 μm. Was.

Further, US Pat. Nos. 30,46118 and 3130048 disclose a printing plate using, as a photosensitive material, an esterified product of a polyhydroxy compound of biphenyl having 4 or less hydroxyl groups and naphthoquinone (1,2) -diazidesulfonic acid. Although disclosed, these photosensitive materials have insufficient resolving power for a positive photoresist composition for microfabrication, and have insufficient solubility in a commonly used solvent, and when the solution is stored for a long period of time, Precipitates easily. For this reason, there is not much problem with a photosensitive printing plate material which becomes a commercial product in a form in which a photosensitive material is applied on a substrate, but it has been a serious disadvantage in a photoresist composition sold in a solution state.

In addition, integrated circuits have been increasingly integrated,
In the production of semiconductor substrates such as I, it has become necessary to process an ultrafine pattern having a line width of 1 μm or less. In such applications, a photoresist having high sensitivity, particularly from the viewpoint of high resolution, high pattern shape reproduction accuracy that accurately captures the shape of the exposure mask, and high productivity is required, and the conventional positive photoresist described above. In fact, it is not possible to respond.

<Problems to be Solved by the Present Invention> Accordingly, the object of the present invention is particularly to the production of semiconductor devices, (1) a positive photoresist composition having high resolution, and (2) a photomask wire. A positive photoresist composition that accurately reproduces mask dimensions over a wide range.

(3) a positive photoresist composition capable of forming a resist pattern having a cross-sectional shape having a high aspect ratio in a pattern having a line width of 1 μm or less; (5) Positive photoresist composition having a wide exposure and development latitude, (6) Soluble in a commonly used resist solvent, and no generation of foreign matter even during long-term storage An object of the present invention is to provide a positive photoresist composition having excellent storage stability.

<Means for Solving the Problems> The present inventors have paid careful attention to the above-mentioned various characteristics and made intensive studies, and as a result, completed the present invention.

That is, the present invention relates to the general formula [B] Or a polyhydroxybiphenyl compound represented by the general formula [C] in which a part of -OH groups of the polyhydroxybiphenyl compound is modified And a compound having a 1,2-naphthoquinonediazido-5-sulfonyl group or a 1,2-naphthoquinonediazide-4-sulfonyl group, which is obtained by an esterification reaction of the compound represented by the general formula [A] A positive photoresist composition comprising a photosensitive material represented by the formula (I) and an alkali-soluble novolak resin.

Hereinafter, the compound represented by formula (A) will be described in detail.

The aliphatic group represented by R includes an alkyl group, an alkenyl group, and the like, and the aromatic group includes a phenyl group, a naphthyl group, and the like. Further, as a substituent on the aliphatic group, an alkoxy group, an aryloxy group, an aryl group, a hydroxy group, a carboxy group, a sulfo group, an amino group, a nitro group, a silyl group, a silyl ether group, a cyano group, an aldehyde group, Examples include a mercapto group and a halogen atom.

Examples of the substituent on the aromatic group include the aliphatic groups other than those exemplified above as the substituent on the aliphatic group.

In the general formula [A], R ₁ and R ₂ can be selected from those described above, and preferably, R has 1 to 8 carbon atoms.
A substituted or unsubstituted aliphatic group and a substituted or unsubstituted aromatic group having 6 to 15 carbon atoms.

Next, a method for synthesizing the photosensitive material represented by the general formula [A] will be described.

When e = f = 0 in the photosensitive material represented by the general formula [A], the general formula [B] 1,2 to the polyhydroxybiphenyl compound represented by
-Naphthoquinonediazide-5 (or -4) -sulfonyl chloride.

Preferred as the compound represented by the general formula [B] are 2,3,4,2 ', 3'-biphenylpentol, 2,3,4,
2 ', 4'-biphenylpentol, 2,3,4,2', 5'-biphenylpentol, 2,3,4,2 ', 6'-biphenylpentol, 2,3,4 , 3 ', 4'-Biphenylpentol, 2,3,4,
3 ', 5'-biphenylpentol, 2,3,5,2', 3'-biphenylpentol, 2,3,5,2 ', 4'-biphenylpentol, 2,3,5 , 2 ', 5'-biphenylpentol, 2,3,5,
2 ', 6'-biphenylpentol, 2,3,5,3', 4'-biphenylpentol, 2,3,5,3 ', 5'-biphenylpentol, 2,3,6 , 2 ', 3'-biphenylpentol, 2,3,6,
2 ', 4'-biphenylpentol, 2,3,6,2', 5'-biphenylpentol, 2,3,6,2 ', 6'-biphenylpentol, 2,3,6 , 3, ', 4'-Biphenylpentol, 2,3,6,
3 ', 5'-biphenylpentol, 2,4,6,2', 3'-biphenylpentol, 2,4,6,2 ', 4'-biphenylpentol, 2,4,6 , 2 ', 5'-biphenylpentol, 2,4,6,
2 ', 6'-biphenylpentol, 2,4,6,3', 4'-biphenylpentol, 2,4,6,3 ', 5'-biphenylpentol, 2,4,5 , 2 ', 3'-biphenylpentol, 2,4,5,
2 ', 4'-biphenylpentol, 2,4,5,2', 5'-biphenylpentol, 2,4,5,2 ', 6'-biphenylpentol, 2,4,5 , 3 ', 4'-Biphenylpentol, 2,4,5,
3 ', 5'-biphenylpentol, 3,4,5,2', 3'-biphenylpentol, 3,4,5,2 ', 4'-biphenylpentol, 3,4,5 , 2 ', 5'-biphenylpentol, 3,4,5,
Biphenylpentols such as 2 ', 6'-biphenylpentol, 3,4,5,3', 4'-biphenylpentol and 3,4,5,3 ', 5'-biphenylpentol Kind, 2,3,4,2 ', 3', 4 '
-Biphenylhexol, 2,3,5,2 ', 3', 5'-biphenylhexol, 2,3,6,2 ', 3', 6'-biphenylhexol, 2,4, 5,2 ′, 4 ′, 5′-biphenylhexol,
2,4,6,2 ', 4', 6'-biphenylhexol, 2,3,4,
3 ', 4', 5'-biphenylhexol, 3,4,5,3 ',
Biphenylhexols such as 4 ', 5'-biphenylhexol can be mentioned.

These polyhydroxybiphenyl compounds are known from Riedl,
W et al. (Justus Liebigs Ann.Chem., 1955, 597 , P15
3 to 157].

The photosensitive material represented by the general formula [A] having the substituents R ₁ and R ₂ is a compound represented by the general formula [C] by modifying a part of the -OH group of the polyhydroxybiphenyl compound, It is obtained by reacting this with 1,2-naphthoquinonediazide-5 (or -4) -sulfonyl chloride.

A compound of the formula [B] or [C] and 1,2-naphthoquinonediazide-5-sulfonyl chloride or 1,2
The esterification reaction with -naphthoquinonediazide-4-sulfonyl chloride is carried out by a usual method. That is, a predetermined amount of polyhydroxybiphenyl or a derivative thereof represented by the general formula [B] or [C] is combined with 1,2-naphthoquinonediazido-5-sulfonyl chloride or 1,2-
A solvent such as naphthoquinonediazide-4-sulfonyl chloride and dioxane, acetone, and methyl ethyl ketone are charged into a flask, and a basic catalyst, for example, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, triethylamine or the like is dropped and condensed. The product obtained is purified after washing with water and dried. The photosensitive material represented by the general formula [A] can be prepared by the above method.

In the above-mentioned esterification reaction, a mixture of compounds represented by the general formula [A] having various numbers of esterifications and esterification positions is obtained. Therefore, the esterification rate referred to in the present invention is defined as an average value of this mixture.

The esterification rate thus defined can be controlled by the mixing ratio of the raw material compound [B] or [C] and 1,2-naphthoquinonediazide-5 (or -4) -sulfonyl chloride. That is, since the added 1,2-naphthoquinonediazide-5 (or -4) -sulfonyl chloride substantially causes an esterification reaction, in order to obtain a mixture having a desired esterification rate, the starting material must be prepared. The molar ratio may be adjusted.

For example, to obtain a mixture having an esterification rate of 66.7% from biphenylhexol as a raw material, 4 mol of 1,2-naphthoquinonediazide-5 (or -4) per mol of biphenylhexol is used. It is sufficient to add sulfonyl chloride;

The esterification rate defined in the present invention can be identified by a commonly used NMR method regardless of the presence or absence of the substituent R ₁ or R ₂ of the compound represented by the general formula [A].

The alkali-soluble novolak resin used in the present invention is obtained by addition-condensation of 0.6 to 1.0 mol of aldehydes with respect to 1 mol of phenols in the presence of an acidic catalyst. As the phenols, phenol, o-cresol, m-cresol, p-cresol, xylenol and the like may be used alone or in combination of two or more (the proportion of each component may be determined in consideration of the characteristics required for the resist composition, the purpose of use, and the like). Can be appropriately adjusted to a preferable range). In addition, formaldehyde, paraformaldehyde, furfural and the like can be used as aldehydes, and hydrochloric acid, sulfuric acid, formic acid, oxalic acid and acetic acid can be used as the acidic catalyst. The thus obtained novolak resin having a molecular weight of 1,000 to 50,000 shows alkali solubility.

The ratio of the photosensitive material to the alkali-soluble novolak resin in the present invention is 5 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the novolak resin. If the use ratio is less than 5 parts by weight, the residual film ratio is significantly reduced,
On the other hand, if it exceeds 100 parts by weight, sensitivity and solubility in a solvent decrease.

In the present invention, the photosensitive material should be mainly used, but if necessary, a usual photosensitive material such as 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2 , 4,6-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, etc.
An ester compound with 1,2-naphthoquinonediazide-4- or / and -5-sulfonyl chloride can be used in combination. In this case, it can be used in a proportion of 100 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of the photosensitive material [A].

In the present invention, a polyhydroxy compound can be further contained to promote dissolution in a developer. Preferred polyhydroxy compounds include phenols, resorcin, phloroglucin, 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone,
3,4,3 ', 4', 5'-hexahydroxybenzophenone,
Acetone-pyrogallol condensation resin and the like are included.

Examples of the solvent for dissolving the photosensitive material of the present invention and the alkali-soluble novolak resin include ketones such as methyl ethyl ketone and cyclohexanone; alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; ethers such as dioxane and ethylene glycol dimethyl ether. Cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate; fatty acid esters such as butyl acetate, methyl lactate and ethyl lactate; halogenated hydrocarbons such as 1,1,2-trichloroethylene; dimethylacetamide;
-Highly polar solvents such as methylpyrrolidone, dimethylformamide and dimethylsulfoxide can be exemplified.
These solvents can be used alone or as a mixture of a plurality of solvents.

The positive photoresist composition of the present invention may optionally contain a dye, a plasticizer, an adhesion aid, a surfactant, and the like. Specific examples include dyes such as methyl violet, crystal violet, and malachite green; plasticizers such as stearic acid, acetal resins, phenoxy resins, and alkyd resins; and adhesion promoters such as hexamethyldisilazane and chloromethylsilane. And surfactants such as nonylphenoxypoly (ethyleneoxy) ethanol and octylphenoxypoly (ethyleneoxy) ethanol.

The above-mentioned positive photoresist composition is applied on a substrate (eg, silicon / silicon dioxide coating) to be used in the manufacture of precision integrated circuit devices by an appropriate application method such as a spinner or a coater, and then exposed through a predetermined mask. Then, a good resist can be obtained by developing.

Examples of the developer for the positive photoresist composition of the present invention include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, inorganic alkalis such as aqueous ammonia, ethylamine, n-propylamine and the like. Primary amines, diethylamine, di-n
Secondary amines such as -butylamine, triethylamine,
Tertiary amines such as methyldiethylamine; alcoholamines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and cyclic amines such as pyrrole and piperidine. Aqueous solutions of alkalis can be used. Further, an appropriate amount of an alcohol or a surfactant may be added to the aqueous solution of the above alkalis for use.

<Effect of the Invention> The positive photoresist of the present invention has high resolution, faithful reproducibility of a mask pattern, cross-sectional shape of a resist image, exposure and development latitude, sensitivity, excellent heat resistance, and is dissolved in a commonly used solvent. The positive photoresist solution of the present invention is excellent in long-term storage stability.

<Examples> Examples of the present invention will be described below, but the present invention is not limited thereto. In addition,% shows weight% unless otherwise specified.

Examples (1) to (3) and Comparative Examples (1) and (2) (1) <Synthesis of Photosensitive Material a> 2,4,6,3 ', 5'-Biphenylpentol (Phlorogluci)
de) 10 g, 40.2 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 500 ml of acetone were charged into a three-necked flask and uniformly dissolved. Next, a mixed solution of triethylamine / acetone = 15.2 g / 50 ml was gradually added dropwise, and reacted at 25 ° C. for 3 hours. The reaction mixture was poured into 2500 ml of a 1% aqueous hydrochloric acid solution, and the resulting precipitate was separated, washed with water and dried (40 ° C).
And 2,4,6,3 ', 5'-biphenylpentol (Phlor
oglucide) 38.7 g of 1,2-naphthoquinonediazide-5-sulfonic acid ester.

(2) <Synthesis of Photosensitive Material b> 2,4,6,3 ', 5'-biphenylpentol (Phlorogluci
de) 10 g and 400 ml of acetone were charged into a three-necked flask and uniformly dissolved. Next, 7 g of acetic anhydride was added with stirring, and then a mixed solution of triethylamine / acetone = 6.9 g / 100 ml was gradually added dropwise, and the mixture was reacted at 25 ° C. for 1 hour. After the completion of the reaction (according to NMR measurement, an average of 1.5 hydroxyl groups in one molecule was modified to an acetyl group), 60 ml of distilled water was added, and the pH of the reaction mixture was adjusted to 7.0 with 36% HCl. . Then
1,2-naphthoquinonediazide-5-sulfonyl chloride 3
4.4 g was added and uniformly dissolved. Triethylamine / acetone = 13.0 g / 50 ml was gradually added dropwise, and reacted at 25 ° C. for 2 hours. After completion of the reaction, the reaction mixture was poured into 2000 ml of a 1% aqueous hydrochloric acid solution, and the precipitate was separated, washed with water and dried (40 ° C.).
Acetyl-modified 2,4,6,3 ', 5'-biphenylpentol (P
Thus, 39.5 g of 1,2-naphthoquinonediazide-5-sulfonic acid ester of hloroglucide) was obtained.

(3) <Synthesis of Photosensitive Material c> 2,4,6,3 ', 5'-biphenylpentol (Phlorogluci
de) 10 g, diethyl sulfate 21.7 g, triethylamine 14.3
g, acetone 300 ml and distilled water 60 ml were charged into a three-necked flask. Next, the temperature was raised and the reaction was carried out for 3 hours under acetone reflux. As a result of NMR measurement, an average of 1.7
Each hydroxyl group was modified with ethyl. 36% after completion of reaction
The pH of the reaction mixture was adjusted to 7.0 with HCl. Furthermore, 1,2-
34.4 g of naphthoquinonediazide-5-sulfonyl chloride
Was uniformly dissolved. A mixture of triethylamine / acetone = 13 g / 50 ml was gradually added dropwise, and reacted at 25 ° C. for 3 hours. After completion of the reaction, the content was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, and the resulting precipitate was separated, washed with water and dried (40%).
C), and 38.6 g of 1,2-naphthoquinonediazide-5-sulfonic acid ester of 2,4,6,3 ', 5'-biphenylpentol modified with ethyl was obtained.

(4) <Synthesis of photosensitive material d>2,3,4,4'-tetrahydroxybenzophenone 10 g,
30 g of 2-naphthoquinonediazide-5-sulfonyl chloride
And 300 ml of acetone were charged into a three-necked flask and uniformly dissolved. Then, triethylamine / acetone = 11.3 g /
50 ml of the mixture was gradually added dropwise, and reacted at 25 ° C. for 3 hours. The reaction mixture was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, and the resulting precipitate was separated, washed with water and dried (40 ° C).
32.8 g of 1,2-naphthoquinonediazidosulfonic acid ester of 3,4,4'-tetrahydroxybenzophenone was obtained.

(5) <Synthesis of Photosensitive Material e> 10 g of 2,2 ', 4,4'-biphenyl tetrol, 33.2 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 300 ml of acetone were charged into a three-necked flask and homogenized. Was dissolved. Then, triethylamine / acetone = 12.6 g / 50 ml
Was gradually added dropwise and reacted at 25 ° C. for 3 hours. The reaction mixture was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, and the resulting precipitate was separated, washed with water and dried (40 ° C.), and subjected to 2,2 ′, 4,4
35.1 g of 1,2-naphthoquinonediazide-5-sulfonic acid ester of 4'-biphenyltetrol was obtained.

(6) <Synthesis of novolak resin> 40 g of meta-cresol, 60 g of p-cresol, 49.5 g of a 37% formalin aqueous solution and 0.05 g of oxalic acid were charged into a three-necked flask, heated to 100 ° C. with stirring, and reacted for 7 hours. Was. After the reaction, the mixture was cooled to room temperature, and the pressure was reduced to 30 mmHg. Then, the temperature was gradually raised to 150 ° C. to remove water and unreacted monomers. The resulting novolak resin has a weight average molecular weight of 8,00
It was 0 (polystyrene conversion).

<Preparation and Evaluation of Positive Photoresist Composition> Each of photosensitive materials a to e 1.25 g shown in Table 1 obtained in the above (1) to (5) and the cresol novolak resin obtained in the above (6) 5 g of (molecular weight: 8,000) was dissolved in 15 g of ethyl cellosolve acetate and passed through a 0.2 μm microfilter to prepare a photoresist composition. The photoresist was applied to a silicon wafer using a spinner and dried in a convection oven under a nitrogen atmosphere at 90 ° C. for 30 minutes to obtain a resist film having a thickness of 1.5 μm. After exposing this film using a reduced projection exposure system (Nikon NSR1505G),
The film was developed with a 2.38% aqueous solution of tetramethylammonium hydroxide for 1 minute, washed with water for 30 seconds and dried. The resist pattern on the silicon wafer thus obtained was observed with a scanning electron microscope to evaluate the resist. Table 2 shows the results.

The sensitivity was defined as the reciprocal of the exposure amount for reproducing a mask pattern of 2.0 μm, and was shown as a relative value of the sensitivity of Comparative Example 1.

The residual film ratio was expressed as a percentage of the ratio of the unexposed portion before and after development. The resolving power indicates a limit resolving power at an exposure amount for reproducing a 2.0 μm mask pattern.

The heat resistance was a temperature at which the resist-patterned silicon wafer was baked in a convection oven for 30 minutes and the pattern did not deform. The shape of the resist
The angle (θ) formed between the resist wall surface and the plane of the silicon wafer in the cross section of the resist pattern of 1.0 μm.
As can be seen, the resists using the photosensitive materials a, b, and c of the present invention were particularly excellent in resolution and resist shape. The photosensitive material of the present invention has excellent solubility in ethyl cellosolve acetate, and the resist composition solution using these photosensitive materials did not precipitate at 40 ° C. for 30 days. After the resist composition solution using the photosensitive materials d and e of the example was left under the same conditions, precipitation of a precipitate was observed.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nomasa Aoya 4,000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Inside Fuji Photo Film Co., Ltd. In-company (56) References JP-A-58-87554 (JP, A) JP-A-57-135947 (JP, A) JP-A-54-63818 (JP, A)

Claims (1)

(57) [Claims] 1. The general formula [B] Or a polyhydroxybiphenyl compound represented by the general formula [C] wherein a part of the -OH group of the polyhydroxyphenyl compound is modified And a compound having a 1,2-naphthoquinonediazido-5-sulfonyl group or a 1,2-naphthoquinonediazide-4-sulfonyl group, which is obtained by an esterification reaction of the compound represented by the general formula [A] A positive photoresist composition comprising a photosensitive material represented by the formula and an alkali-soluble novolak resin.