JPH01288852A - Positive type photoresist material - Google Patents

Abstract

PURPOSE:To enhance the resolution and heat resistance of the resist without impairing the sensitivity and process stability thereof by using a novolak resin having a specific unit and 1, 2-quinonediazide compd. CONSTITUTION:The resist material consists of the alkaline soluble novolak resin (A) contg. the unit expressed by the formula and the 1, 2-quinonediazide compd. In the formula, R denotes H, alkyl of 1-5C, etc.; (a) denotes 1, 2; X denotes alkyl of 1-5C, phenyl, etc.; B denotes carbonyl, sulfonyl, etc. X is preferably -SO3H and/or -COOH and/or -OH and/or (substd.) alkyl and/or (substd.) phenyl and/or (substd.) naphthyl and/or aralkyl contg. at least >=1 salts thereof.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides an alkali-soluble novolac resin and a 1°2- The present invention relates to a positive photoresist material made of a quinonediazide compound and a pattern forming method.

[Prior Art] In recent years, the density and integration of semiconductor integrated circuits have progressed, and we have entered an era where the degree of integration is 4 Mbits or more, and pattern formation of submicron rules or even smaller ones has become necessary.

The positive photoresist consists of an alkali-soluble novolak resin and a 1°2-quinonediazide compound that functions as an alkali dissolution inhibitor.

In the radiation irradiated part, the 1,2-quinonediazide compound becomes ketene via carbene, reacts with moisture inside and outside the system to produce indene carboxylic acid, and becomes easily dissolved in the alkaline aqueous solution. On the other hand, the unirradiated area is dissolved in an alkaline developer, hardly swells, and maintains a high residual film ratio. As a result, a high resolution resist pattern is obtained. Conventional cyclized polyisoprene-based negative resists have limited resolution due to swelling of the film during development, and recently positive resists have been mainly used.

By the way, in order to meet increasingly stringent requirements, various improvements are being attempted in positive photoresists, and a wide range of detailed studies are being conducted on everything from resins, photosensitizers, developers, and additives. .

In particular, high sensitivity, high resolution, rectangularity of pattern profile, high dry etching resistance, high heat resistance, and process stability are strongly desired and are the goals of improvement.

[Problem to be solved by the invention] However, sensitivity and resolution, sensitivity and heat resistance, and sensitivity,
Resolution, heat resistance and process stability tend to contradict each other. For example, increasing the molecular weight of the resin increases heat resistance, but reduces sensitivity, resolution, pattern profile rectangularity, and process stability. If copolymerization is performed to improve heat resistance, the rectangularity of the pattern profile and process stability will decrease. Furthermore, when the amount of photosensitizer is increased, the resolution improves, but the sensitivity decreases. As described above, since there are many contradictory properties, it has been extremely difficult to achieve high performance without degrading other properties.

[Means for Solving the Problems] As a result of intensive research based on the above background, the present inventors have found that the sensitivity can be improved by using an alkali-soluble novolak resin containing the compound (1) of the present invention. They discovered that the resolution, pattern profile, and heat resistance can be improved while maintaining process stability, and have completed the present invention.

That is, general formula (1), (wherein R represents hydrogen, an alkyl group/alkoxy group having 1 to 5 carbon atoms, a halogen, or a nitro group, and X represents 1 to 5 carbon atoms.
represents an alkyl group or substituted alkyl group, phenyl group, substituted phenyl group, naphthyl group, substituted naphthyl group, or aralkyl group, and a represents 1 or 2. B is a carbonyl group,
Indicates a sulfonyl group. ) unit and a 1,2-quinonediazide compound, and a pattern forming method thereof.

In addition, R in general formula (1) can include, for example, the following. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, amyl group, etc.; examples of the alkoxy group include methoxy group, ethoxy group, etc.; and examples of the halogen include chlorine, fluorine, bromine, etc. . In addition, examples of the alkyl group of Substituents for substituted phenyl or naphthyl groups include methyl, ethyl, trifluoromethyl, carboxyl, nitro, fluorine, chlorine, etc., and aralkyl groups include benzyl and phenethyl. As X, a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group, and an aralkyl group are preferable because they further improve heat resistance. In particular, considering the solubility in the resist solution and the solubility in the developer, X may be -SO3H group and/or -COOH group and/or -0H2! and/or an alkyl group containing at least one salt thereof and/or
or a substituted alkyl group and Cj/or a phenyl group and/or a substituted phenyl group and/or a naphthyl group and/or a substituted naphthyl group and/or an aralkyl group. Cationic groups that can be converted into salts include, but are not particularly limited to, ammonium groups, alkyl ammonium groups having 1 to 4 carbon atoms, sia alkyl ammonium groups having 1 to 4 carbon atoms, and 1 to 4 carbon atoms.
Examples include a trialkylammonium group, a tetraalkylammonium group having 1 to 4 carbon atoms, and the like.

The alkali-soluble novolac resin of the present invention can be produced by mixing the corresponding monomer and aldehydes such as formaldehyde, paraformaldehyde, and acetaldehyde in the presence of an acidic catalyst such as formic acid, oxalic acid, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, and Lewis acid. It can be synthesized by polycondensing according to the method described above, and then esterifying a part of the phenolic hydroxyl group with a sulfonyl group or a carbonyl group. Esterification is obtained by reacting phenols with sulfonyl halides or carbonyl halides in the presence of a base such as potassium hydroxide, sodium hydroxide, alkali carbonate, triethylamine, pyridine, or the like. Alternatively, an alkali-soluble novolak resin can also be synthesized by copolycondensing the compound of the present invention and a corresponding monomer. The weight average molecular weight of the resin is preferably 2,000 to 30,000 (in terms of polystyrene).

Further, the esterification rate or copolymerization ratio with respect to OH groups in the resin may be any from 0.01 to 99.99 mol%, but preferably the content of the compound (1) of the present invention is 1.
~20 mol% is good. With regard to molecular weight, esterification rate, and copolymerization ratio, sensitivity, resolution, heat resistance, and process stability are excellent when the molecular weight, esterification rate, and copolymerization ratio are within the above ranges.

As monomers used in the alkali-soluble novolak resin of the present invention, for example, the following phenols can be used singly or in combination of two or more. Phenols include phenol, 0-cresol, m-cresol, p-cresol, 0-ethylphenol, m-
Ethylphenol, p-ethylphenol, o-n-butylphenol, m-n-butylphenol, p-n-
Butylphenol, o-t-butylphenol, m-1
-butylphenol, pt-butylphenol, 0-
Methoxyphenol, m-methoxyphenol, p-methoxyphenol, 0-fluorophenol, m-fluorophenol, p-fluorophenol, 0-chlorophenol, m-chlorophenol, p-chlorophenol, 〇-nitrophenol, m-nitrophenol,
p-nitrophenol, 2,4-xylenol, 2゜5
-xylenol, 3,4-xylenol, 3°5-xylenol and the like.

The 1,2-quinonediazide compound used in the present invention is, for example, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5
- It is a sulfonic acid ester, and the ester component is:
Polyhydroxybenzophenones such as trihydroxybenzophenone, tetrahydroxybenzophenone, hexahydroxybenzophenone, alkyl gallates such as methyl gallate, flavones such as quercetin, polyhydroxyphenylalkyl ketones such as trihydroxybenzene, trihydroxyphenyl-n-hexyl ketone, etc. , dihydroxydiphenylmethane, dihydroxydiphenylpropane, dihydroxydiphenylhexafluoropropane, dihydroxydiphenylsulfone, dihydroxydiphenylamine, and the like. 1.2-quinonediazide compound is an alkali-soluble novolac resin 1
It is preferably 20 to 50 parts by weight based on 00fffR parts. Within this range, a sufficient difference in solubility in the developer between exposed and unexposed areas can be obtained, and a pattern with excellent sensitivity and resolution can be obtained.

The positive photoresist material of the present invention is obtained by dissolving the alkali-soluble novolac resin and the 1,2-quinonediazide compound in a suitable solvent so that the solid content is 20 to 40 parts by weight. Examples of the solvent include ethylene glycol monoalkyl ether and its acetates, propylene glycol monoalkyl ether and its acetates, diethylene glycol dialkyl ethers, ketones such as methyl ethyl ketone and cyclohexanone, acetic acid esters such as ethyl acetate and butyl acetate, Examples include aromatic hydrocarbons such as toluene and xylene, dimethylacetamide, and dimethylformamide. These solvents can be used alone or in combination of two or more. Furthermore, if necessary, a nonionic, fluorine-based, silicone-based surfactant, etc. can be added to improve coating properties. Furthermore, compatible additives such as sensitizers, colorants, stabilizers, etc. can be blended.

[Function] The positive photoresist material comprising the alkali-soluble novolak resin and 1°2-quinonediazide compound of the present invention can be used for resist pattern formation using ultraviolet rays, deep ultraviolet rays, electron beams, X-rays, etc., and has a high sensitivity. ,resolution,
Excellent heat resistance and process stability.

There are no particular limitations on the method of using the positive photoresist material comprising the alkali-soluble novolac resin and 1゜2-quinonediazide compound of the present invention to form a resist pattern using radiation, and it can be carried out according to a conventional method. .

For example, the positive photoresist solution of the present invention is prepared by dissolving an alkali-soluble novolak resin, a 1,2-quinonediazide compound, and additives in a solvent, and filtering the solution through a 0.degree. 2 .mu.m filter. A resist film is obtained by spin-coding a resist solution onto a substrate such as a silicon wafer and bre-baking. Thereafter, a resist pattern can be formed by performing exposure using a reduction projection exposure device, an electron beam exposure device, or the like, and developing.

As a developer, for example, an organic alkali aqueous solution such as a quaternary ammonium salt such as tetramethylammonium hydroxide, choline, amines, or an inorganic alkali aqueous solution such as sodium hydroxide, potassium hydroxide, sodium carbonate, or aqueous ammonia is used. Can be used. Other methods such as coating, blebake, exposure, development, etc. can be carried out by conventional methods.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Synthesis Example 1 30 g of 0-cresol, m
- 50 g of cresol, 50 g of p-cresol, and 1.75 g of oxalic acid dihydrate were added. Under a nitrogen atmosphere, the mixture was immersed in an oil bath without stirring, and the humidity was increased until the internal temperature reached 100°C. While maintaining the internal temperature at 100° C., 86 g of a 35% aqueous formalin solution was added dropwise over 90 minutes. Thereafter, the reaction was continued for 10 minutes to synthesize a novolac resin. After the reaction, 115 g of resin powder was obtained by repeating dissolution and precipitation and drying.

As a result of GPC measurement, the weight average molecular weight of the novolac resin was 4850 in terms of polystyrene. Further, the degree of dispersion (weight average molecular weight/number average molecular m) was 4.62.

Synthesis Example 2 In a 500rd 4-tube flask, 20 g of the novolak resin synthesized in Synthesis Example 1 and 150 m of acetone were added and dissolved. Next, a solution of 1.0 g of triethylamine and 25 d of acetone was added dropwise over 20 minutes while stirring at room temperature. Furthermore, p-chlorosulfonylbenzoic acid 1.8
4g, acetone 25mj! dropwise solution over 20 minutes,
Thereafter, the reaction was continued for 1 hour. After the reaction, the reaction solution was dropped into a large amount of pure water to precipitate the resin, which was then washed with water and dried to obtain 20.8 g of resin powder.

Elemental analysis values are C77.8%, H6.6%, 81.0%
The esterification rate was 4 mol% (based on the resin).

Synthesis Example 3 According to Synthesis Example 2, 20 g of the novolak resin synthesized in Synthesis Example 1, 1.0 g of triethylamine, and 1.84 g of m-chlorosulfonylbenzoic acid were reacted in acetone,
20.6 g of resin powder was obtained.

Elemental analysis values are C77.6%, H6.7%, 81.0%
The esterification rate was 4 mol% (based on the resin).

Synthesis Example 4 According to Synthesis Example 2, 20 g of the novolac resin synthesized in Synthesis Example 1, 2.0 g of triethylamine, and 3.68' g of m-chlorosulfonylbenzoic acid were reacted in acetone to obtain 21.7 g of resin powder. I got g.

Elemental analysis values are C75.7%, H6.4%, 82.0%
The esterification rate was 8.5 mol% (based on the resin).

Synthesis Example 5 According to Synthesis Example 2, 20 g of the novolac resin synthesized in Synthesis Example 1, 1.0 g of triethylamine, and 1.46 g of benzenesulfonyl chloride were reacted in acetone.
20.6 g of resin powder was obtained.

Elemental analysis values are C78.2%, H6.8%, Sl, 1%
The esterification rate was 4.5 mol% (based on the resin).

Synthesis Example 6 According to Synthesis Example 2, 20 g of the novolak resin synthesized in Synthesis Example 1, 1.0 g of triethylamine, and 1.0 g of methanesulfonyl chloride were reacted in acetone to obtain 20.4 g of resin powder.

Elemental analysis values are C77.6%, H6.8%, 81.3%
The esterification rate was 5 mol% (based on the resin).

Example 1 Benzoic acid p of cresol novolak resin obtained in Synthesis Example 2
- 8 g of a sulfonic acid ester, and 2.24 g of an ester of 2,3゜4.4-1-tetrahydroxybenzophenone and 1゜2-naphthoquinonediazide-5-sulfonyl chloride (3 hydroxyl groups on average are esterified). It was dissolved in 24 g of ethylene glycol monoethyl ether acetate and filtered through a 0.2 μm membrane filter to obtain a resist solution. The resist solution was spin-coated onto a 4-inch silicon wafer using a spinner.
1. Brebake at 0°C for 30 minutes in a circulating constant temperature bath.
A resist film with a thickness of 5 μm was obtained.

Next, a reduction projection exposure device (manufactured by GCA, DSW-6300A
SN, A, -0,35) through the reticle. A 2.15% aqueous solution of tetramethylammonium hydroxide was used as a developer at 25°C.
Immersion development was performed for 1 minute. The exposure amount to resolve 1.0 μm line/space one to one is 156 mJ/
cm2.

Also, even in 0.8 μm line/space, 156
A one-to-one pattern could be resolved with mJ/cm2, and the mask fidelity was good.

Furthermore, the exposure amount at which resolution of 1.0 μm in/space begins is 108 mJ/cm”, which is 100 to 156 mJ/cm”.
No scum generation was observed within the exposure dose range of mJ/cm2.

Regarding the resolution, a 0.65 μm line/space could be resolved, and the pattern was rectangular.

Next, resist patterns with 2 μm lines/spaces of 140, 145, 150, 155°160.16
Baking was performed at each temperature of 5,170''C for 30 minutes in a circulating constant temperature bath, and the heat resistance was evaluated based on the presence or absence of pattern deformation.As a result, the heat resistance was 165°C.

Examples 2 to 5 The resins obtained in Synthesis Examples 3 to 6 were subjected to an exposure test and a heat resistance test according to Example 1.

Table 1 shows the results.

Comparative Example In the -10 cresol novolak resin obtained in Synthesis Example 1 after undergoing the esterification process, according to Example 11,
An exposure test and a heat resistance test were conducted. Table 11 shows the results.

[Effects of the Invention] The positive photoresist material comprising an alkali-soluble novolak resin and a 1°2-quinonediazide compound of the present invention is a material in which a phenolic hydroxyl group is esterified with a sulfonyl group or a carbonyl group as part of the novolak resin. By introducing the method into the process, it is possible to improve the resolution, heat resistance, and pattern shape without impairing sensitivity and process stability, so it is suitable for manufacturing semiconductor integrated circuit elements such as VLSI.

Claims (6)

[Claims] (1) General formula (1), ▲ Numerical formulas, chemical formulas, tables, etc. ~5
represents an alkyl group or substituted alkyl group, phenyl group, substituted phenyl group, naphthyl group, substituted naphthyl group, or aralkyl group, and a represents 1 or 2. B is a carbonyl group,
Indicates a sulfonyl group. ) A positive photoresist material comprising an alkali-soluble novolac resin containing units and a 1,2-quinonediazide compound. 2. The positive photoresist material according to claim 1, comprising an alkali-soluble novolak resin in which (2) X is an alkyl group and/or a phenyl group and/or a naphthyl group and/or an aralkyl group. (3) X is an alkyl group and/or a substituted alkyl group and/or a phenyl group and/or a substituted phenyl group containing at least one -SO_3H group and/or -COOH group and/or -OH group and/or a salt thereof 2. The positive-working photoresist material according to claim 1, comprising an alkali-soluble novolak resin having a naphthyl group and/or a naphthyl group and/or a substituted naphthyl group and/or an aralkyl group. (4) The positive photoresist material according to claim 1, comprising an alkali-soluble novolak resin containing 0.01 to 99.99 mol % of the component of general formula (1). (5) The positive photoresist material according to claim 1, comprising an alkali-soluble novolak resin containing 1 to 20 mol% of the component represented by formula (1). (6) A resist pattern forming method using the positive photoresist material according to any one of claims 1 to 5.