JPH03179353A - Positive type radiation sensitive resist composition - Google Patents

Abstract

PURPOSE:To improve sensitivity, resolving power and heat resistance by incorporating an alkaline-soluble resin contg. a specific phenolic compd. and 1, 2- quinonediazide compd. into the above compsn. CONSTITUTION:This compsn. contains the 1, 2-quinonediazide compd. and the alkaline-soluble resin. The phenolic compd. expressed by formula I is incorpo rated into the alkaline-soluble resin. In the formula I, R denotes an alkyl group, alkoxy group; (n) denotes 0 to 3. This phenolic compd. is synthesized by subjecting phenols and terephthalaldehyde into dehydration condensation in the presence of an acid catalyst. The positive type radiation sensitive resist compsn. having the excellent sensitivity, resolving power and heat resistance is obtd. in this way.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a positive resist composition sensitive to radiation such as ultraviolet rays, deep ultraviolet rays (including excimer lasers, etc.), electron beams, ion beams, and X-rays. It is related to.

<Prior art and problems with the invention> In recent years, integrated circuits have become increasingly finer due to higher integration.
Submicron pattern formation is now required, and positive photoresists with excellent resolution are required. Conventionally, a mask contact method has been used to form integrated circuits, but this method is said to have a limit of 2 μm, and a reduction projection exposure method is attracting attention as an alternative. This method is a method in which the pattern of a master mask (reticle) is reduced and projected using a lens system for exposure, and the resolution can be down to submicrons. However, one of the problems with this reduction projection exposure method is that the throughput is low.

That is, unlike the conventional batch exposure method such as the mask contact method, the reduction projection exposure method uses divided and repeated exposure, resulting in a problem that the total exposure time per wafer becomes long.

The most important way to solve this problem is to improve the sensitivity of the resist used, as well as improving the equipment. If exposure time can be shortened by increasing sensitivity, throughput and yield can be improved. On the other hand, LSI
As the degree of integration improves, the width of wiring becomes finer, and as a result, dry etching has become mainstream instead of conventional wet etching. Because of this dry etching, heat resistance of the resist has become more required than before.

Looking at the positive photoresists currently used from this point of view, they are not necessarily satisfactory in terms of sensitivity, resolution, and heat resistance. Generally, positive photoresists have lower sensitivity than negative photoresists, and improvements are desired.

For example, in order to achieve high sensitivity, the simplest method is to lower the molecular weight of the novolak resin used in positive photoresists, which increases the rate of dissolution in alkaline developers and makes the apparent sensitivity of the resist lower. Go up. However, with this method, film loss in non-exposed areas increases (
(so-called decrease in residual film rate), pattern shape worsens,
In addition to problems such as a decrease in the so-called γ value (decreased resolution) due to the small difference in dissolution rate in the developer between exposed and non-exposed areas, this is an extremely serious disadvantage in that the heat resistance of the resist decreases. occurs. That is, at present, there is no positive resist that has all of sensitivity, resolution, and heat resistance, and we are in an extremely disadvantageous situation in which an attempt to improve one will worsen the other.

An object of the present invention is to provide a positive radiation-sensitive resist composition for use in the production of integrated circuits, which solves the problems of the prior art and has excellent sensitivity, resolution, and heat resistance.

Specific Means for Solving the Problems> The present inventors have completed the present invention by discovering that the above problems can be solved by adding a phenol compound with a specific structure to a resist composition. The present invention provides a positive radiation-sensitive resist composition containing a 1,2-quinonediazide compound and an alkali-soluble resin, in which the alkali-soluble resin contains a phenol compound (I) represented by the following general formula (I). The present invention provides a positive radiation-sensitive resist composition characterized by containing:

[In the formula, R represents an alkyl group or an alkoxy group, and n is 0
Represents a number greater than or equal to 3 and less than or equal to 3. ] Here, R is particularly preferably an alkyl group of 01 to Cs, a methoxy group, or an ethoxy group.

Among these, the compound represented by the following formula (II) is particularly preferred. (Left below) General formula (
The phenolic compound I) is synthesized by dehydration condensation of phenols and terephthalaldehyde in the presence of an acid catalyst.

Examples of the phenols used here include phenol, cresol, xylenol, 2°3.5-trimethylphenol, t-butylphenol, methoxyphenol, and ethylphenol.

Examples of the acid catalyst used in this condensation reaction include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as oxalic acid and p-)luenesulfonic acid. The amount of phenol used is 4 to 80 mol, preferably 8 to 40 mol, per 1 mol of terephthalaldehyde. The amount of acid catalyst used is preferably 0.01-0.7 mol per 1 mol of terephthalaldehyde. The condensation reaction is usually carried out at 30-150°C, 1-
It will be done in 30 hours. Further, the reaction may be carried out in bulk or an appropriate solvent may be used. Examples of solvents used at this time include water, ethyl cellosolve acetate,
Examples include ethyl cellosolve, methyl cellosolve, methyl isobutyl ketone, methyl ethyl ketone, hexane, cyclohexane, heptane, benzene, and toluene.

Among these, hexane, cyclohexane, heptane,
Particularly preferred are those that are poor solvents for the raw materials, such as toluene. The amount of these solvents is preferably from 10 to 100 parts by weight of the total amount of the phenolic compound and carbonyl compound.
It is 700 parts by weight. The compound represented by formula (IF) is
It can be synthesized by a condensation reaction between 2,5-xylenol and terephthalaldehyde.

In this case, toluene in the presence of a p-toluenesulfonic acid catalyst is preferred. The amount of solvent is 50 to 500 parts by weight per 100 parts by weight of 2,5-xylenol. The molar ratio of 2,5-xylenol is 1:1 of terephthalaldehyde.
The molar ratio of p-toluenesulfonic acid is from o, oi to 0.1 mol, preferably from 0.02 to 0.03 mol. The condensation reaction is 5
The reaction is carried out at 0°C to reflux temperature for 5 to 30 hours.

After the condensation product is demetallized, it can be purified by recrystallization or reprecipitation.

Demetallization can be carried out by dissolving the product in an organic solvent that is separated by mixing it with water, and washing with ion-exchanged water. Examples of the organic solvent include methyl isobutyl ketone, ethyl cellosolve acetate, and ethyl acetate.

Demetallation ions can also be carried out by mixing the product with water, dissolving it in an organic solvent that does not separate the product, and charging it into ion-exchanged water (re-precipitation). Here, examples of the organic solvent include methanol, ethanol, acetone, and the like. This method is preferable because demetal ionization and purification can be performed simultaneously.

The positive radiation-sensitive resist composition of the present invention may contain other alkali-soluble resins in addition to the phenol compound (I). The content of the phenolic compound (1) is based on 100 parts by weight of the total amount of the alkali-soluble resin (i.e., the phenol compound CI) and other alkali-soluble resins,
4 parts by weight or more, preferably 10 to 40 parts by weight.

If the amount of phenol compound (I) is less than 4 parts by weight, the solubility in a developer consisting of an alkaline aqueous solution will be reduced, making development difficult; if it exceeds 40 parts by weight, even the areas not exposed to radiation will dissolve in the developer. This makes patterning difficult.

Other alkali-soluble resins used in this case are not particularly limited, but include, for example, polyvinylphenol, novolak resin, and the like.

Novolac resins include, for example, phenol, O-cresol, m-cresol, p-cresol, 25-xylenol, 3,5-xylenol, 34-xylenol, 2
．． 3.5-) Limethylphenol, 4-t-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 3-ethylphenol, 2-ethylphenol, 4-ethylphenol, 2-naphthol, 1. 3
Examples include resins in which phenols such as -dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and 1,5-dihydroxynaphthalene are condensed alone or in combination with formalin by a conventional method.

This condensation reaction is usually carried out at 60 to 120°C for 2 to 30 hours. As the catalyst, organic or inorganic acids, divalent metal salts, etc. are used. Specific examples include oxalic acid, hydrochloric acid, sulfuric acid, perchloric acid, p-toluenesulfonic acid, trichloroacetic acid, phosphoric acid, formic acid, zinc acetate, magnesium acetate, and the like. Further, the reaction may be carried out in bulk or an appropriate solvent may be used.

Among them, as a novolak resin, G
It is preferable that the area ratio of a component having a polystyrene equivalent molecular weight of 900 or less measured by PC (using a UUV-254n detector) to the total pattern area is 25% or less.

Next, the I,2-quinonediazide compound used in the positive radiation-sensitive resist composition of the present invention is not particularly limited, but examples include 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide- 4-
Sulfonic acid ester 1,2-naphthoquinone diazide-5
-sulfonic acid esters and the like. These esters can be obtained by a known method, for example, by condensing 1,2-naphthoquinonediazide sulfonic acid chloride or benzoquinonediazide sulfonic acid chloride with a compound having a hydroxyl group in the presence of a weak alkali. Here, examples of compounds having a hydroxyl group include hydroquinone, resorcinol, -fu(loroghisin, 2,4-dihydroxybenzophenone, 2.3.4-)lyhydroxybenzophenone, 2,3.4.4°- Tetrahydroxybenzophenone, 2.2'4.4' -tetrahydroxy-dihydric phenone, bis(p-hydroxyphenyl)methane, bis(2,4-dihydroxyphenyl)methane, bisCZ, 3.4-)rihydroxy phenyl)methane, 2,2-bis(p-hydroxyphenyl)propane, 2,2-bis(2,4-dihydroxyphenyl)propane, 2,2-bis(23,,4-)lihydroxyphenyl)propane, In the middle, l represents a number from 0 to 4, and m represents a number from 1 to 5. R+, R*, and R* represent a hydrogen atom, an alkyl group, an alkenyl group, a cyclohexyl group, or an aryl group. ) etc. 1 of these
．． The 2-quinonediazide compound may be used alone or in a mixture of 2f1 or more. The positive radiation-sensitive resist composition is prepared by mixing and dissolving the 1,2-quinonediazide compound and the alkali-soluble resin containing the phenol compound (I) in an appropriate solvent. The ratio of the alkali-soluble resin to the 1.2-quinonediazide compound is usually 5 to 100 parts by weight, preferably 10 to 100 parts by weight of the 1.2-quinonediazide compound per 100 parts by weight of the alkali-soluble resin.
It is 50 parts by weight. If this amount is less than 5 parts by weight, it will easily dissolve in a developer consisting of an alkaline aqueous solution, making patterning difficult; if it exceeds 100 parts by weight, all of the added 1,2-quinonediazide compound will be removed by short-term radiation irradiation. cannot be decomposed, and as a result, the amount of radiation irradiation must be increased, resulting in a decrease in sensitivity. The solvent used is preferably one that evaporates at an appropriate drying rate and provides a uniform and smooth coating film.

Such ones include ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether acetate, butyl acetate, methyl isobutyl ketone, xylene, and the like. These solvents may be used alone or in combination of two or more. The positive radiation-sensitive resist composition obtained by the above method may further contain a small amount of a resin, dye, etc. as an additive, if necessary.

<Effects of the Invention> The radiation-sensitive resist composition of the present invention has excellent sensitivity and improved resolution and heat resistance compared to existing resist compositions.

<Examples> Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Synthesis Example 1 5 equipped with a stirrer, cooling tube, water separator, and thermometer
2.5-xylenol 97 in a 00ml Mitsuro flask
．． 74 g, terephthalaldehyde 10.73 g, toluene 195.5 g, p-toluenesulfonic acid 0.
8 g was charged, and the reaction was carried out for 5 hours while removing condensed water under reflux. Thereafter, the mixture was cooled to room temperature, filtered, washed three times with 350 cc of toluene, and dried at 60°C.

The amount of insertion was 45.2 g, and the yield was 96.2% (in terms of terephthalaldehyde).

Mass spectrum + m/e 586 (M') Synthesis Example 2 149 g of metacresol, 121 g of para-cresol, 252 g of ethyl cellosolve acetate, and 30.4 g of 5% oxalic acid were placed in a three-turn flask with an internal volume of 1.000 m1', and heated under reflux. While stirring, add formalin aqueous solution (3
7.0%) was removed over a period of 40 minutes, and the reaction was continued with stirring for 7 hours. Then neutralize, wash with water,
Dehydrated novolak resin ethyl cellosolve acetate-1
・I got it. The weight average molecular weight in terms of polystyrene determined by GPC was 9,600.

Synthesis Example 3 Ethyl cellosolve acetate solution of the novolac resin obtained in Synthesis Example 2 (containing novolac resin ff141.2)
%) 120g is 31! Add ethyl cellosolve acetate 868.8 to a bottomless separable flask and add
g and 544.6 g of normal heptane at 20°C.
After stirring for 30 minutes, the mixture was allowed to stand and the liquid was separated. Normal hemobutane in the lower layer obtained by liquid separation was removed using an evaporator to obtain a solution of novolak resin in ethyl cellosolve acetate. The polystyrene equivalent weight average molecular weight determined by GPC was 15,500. This fractionation operation removed 75% of the low molecular weight novola. The content of components having a polystyrene equivalent molecular weight of 900 or less by GPC was 7%.

Examples 1 to 2 The condensate obtained in Synthesis Example 1 and the novolac resin obtained in Synthesis Example 2.3 were each dissolved in ethyl cellosolve acetate together with a photosensitizer in the composition shown in Table 1 to prepare a resist solution. The amount of solvent was adjusted to give a film thickness of 1.28 μm under the coating conditions shown below. Each of these compositions was filtered through a 0.2 μm Teflon filter to prepare a resist solution. This was applied to a silicone wafer cleaned by a conventional method using a spin coating machine for 4000 r, p, 1.
)1. It was coated with Then, this silicone ueno\- was baked for 1 minute on a vacuum adsorption type hot plate at 100°C. Then, using a reduction projection exposure device with an ultra-high pressure mercury lamp as the light source, the exposure time was changed step by step for each shot.
exposed. Next, developer 5OPD (Sumitomo Chemical ■
It was developed using a commercially available product (trade name). After rinsing and drying, the film loss and exposure time of each shot were measured to determine the sensitivity. Further, the remaining film rate was determined from the remaining film thickness of the unexposed area.

In addition, silicon wafers with resist patterns after development were placed in a clean oven set at various temperatures for 30 minutes.
The resist pattern was left in an air atmosphere for 1 minute, and then the resist pattern was observed with a scanning electron microscope to evaluate heat resistance.

Comparative Examples 1 and 2 Resist compositions were prepared, exposed, and developed in the same manner as in Example 1 except that no phenol compound was added. In addition to determining the sensitivity and residual film rate using the same method as in Example 1,
Heat resistance was evaluated.

These results are summarized in Table-1. As is clear from Table 1, it was recognized that the balance of sensitivity, resolution, and heat resistance of the Examples was significantly improved compared to that of the Comparative Examples.

(Margins below) Table 1 (1) Condensate of 1,2-naphthoquinonediazide 5-sulfonyl chloride and 2.3.4.4°-tetrahydroxybenzophenone (2) Condition in the clean oven when the resist pattern started to sag. temperature

Claims (4)

[Claims] (1) A positive radiation-sensitive resist composition containing an alkali-soluble resin containing a phenol compound represented by general formula (I) and a 1,2-quinonediazide compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [In the formula, R represents an alkyl group or an alkoxy group, and n represents a number from 0 to 3. ] (2) The phenol compound of general formula (I) has the following formula (II)
The positive radiation-sensitive resist composition according to claim 1, which is a compound represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (3) The content of the phenolic compound represented by the general formula (I) is 4 to 4 parts by weight per 100 parts by weight of the total amount of the alkali-soluble resin.
3. The positive radiation-sensitive resist composition according to claim 1, wherein the amount is 40 parts by weight. (4) The alkali-soluble resin is a novolac resin, and the area ratio of a component having a polystyrene equivalent molecular weight of 900 or less according to GPC (using a detector UV-254 nm) of the novolac resin is 25% or less of the total pattern area. The positive radiation-sensitive resist composition according to claim 1, 2 or 3.