JP2814721B2 - Positive radiation-sensitive resist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is sensitive to radiation such as ultraviolet rays, far ultraviolet rays (including excimer lasers, etc.), electron beams, ion beams, X-rays, etc. The present invention relates to a positive resist composition suitably used.

<Prior Art> In recent years, integrated circuits have been miniaturized in accordance with high integration, and submicron pattern formation has been demanded, and improvement in resolution is desired. Conventionally, a mask contact method has been used for forming an integrated circuit, but this method is said to have a limit of 2 μm.
Attention has been paid to a reduced projection exposure method. This is a method in which a pattern of a master mask (reticle) is reduced and projected by a lens system and exposed, and it is said that a resolution of up to submicron is possible on an apparatus. However, one of the problems of the reduced projection exposure method is that the throughput is low. In other words, unlike the conventional batch exposure method such as the mask contact method, the reduced projection exposure method involves repeated repetition exposure, which causes a problem that the total exposure time per wafer becomes long. As a method to solve this, while improving the device,
The most important thing is to increase the sensitivity of the resist used. If exposure time can be shortened by increasing sensitivity, throughput can be improved,
Consequently, an improvement in yield can be achieved.

On the other hand, as the integration degree of the LSI is improved, the width of the wiring is becoming finer. Therefore, the dry etching is becoming the mainstream instead of the conventional wet etching. For this reason, the dry etching resistance (heat resistance) of the resist has been required more than before.

<Problems to be Solved by the Invention> Positive photoresists currently used from such a viewpoint are not always satisfactory in sensitivity, resolution and heat resistance. In general, positive photoresists have lower sensitivity than negative photoresists, and improvements are desired. In order to achieve high sensitivity,
For example, the simplest method is to lower the molecular weight of the alkali-soluble resin used in the positive photoresist, thereby increasing the dissolution rate in an alkali developer and apparently increasing the sensitivity of the resist. However, in this method, the film loss in the non-exposed area becomes large (so-called residual film ratio is reduced), the pattern shape is deteriorated, and the difference in the dissolution rate of the exposed part and the non-exposed part in the developing solution is reduced. In addition to the problems such as a decrease in the so-called γ value (a decrease in the developing power), there arises an inconvenience that the heat resistance of the resist decreases. As described above, at present, there is no positive resist having all of sensitivity, resolution and heat resistance, and in order to improve one property, it is necessary to sacrifice any of the other properties.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a positive-type radiation-sensitive resist composition excellent in sensitivity, resolution and heat resistance as an integrated circuit manufacturing operation.

<Means for Solving the Problems> The present inventors have found that the above problems can be solved by using a phenol compound having a specific structure as one component of a resist composition, and have completed the present invention.

That is, the present invention provides a positive radiation-sensitive resist composition containing a 1,2-quinonediazide compound and an alkali-soluble resin, wherein the alkali-soluble resin contains a phenol compound represented by the following general formula (I). Is what you do.

In the formula, R represents an alkyl group or an alkoxy group, and n represents a number of 0 or more and 3 or less. Here, particularly as R, C ₁
Alkyl group -C _5, a methoxy group or an ethoxy group is preferred. Further, n is preferably 1 or more.

Among the phenol compounds represented by the general formula (I),
Particularly, a compound represented by the following formula (II) is preferable.

The phenol compound of the general formula (I) is represented by the formula
And a phenol corresponding to a benzene ring having-(R) n and terephthalaldehyde can be produced by a dehydration bond in the presence of an acid catalyst. Examples of phenols used here include, for example, phenol, cresol, xylenol, 2,3,5-trimethylphenol,
Ethyl phenol, t-butyl phenol, methoxy phenol, ethoxy phenol and the like can be mentioned. Examples of the acid catalyst used in the condensation reaction include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as oxalic acid and p-toluenesulfonic acid. The amount of the phenol used is usually 4 to 80 mol, preferably 8 to 40 mol, per 1 mol of terephthalaldehyde. The acid catalyst is used in an amount of 0.1 to 1 mole of terephthalaldehyde.
01-0.7 mol is preferred.

The condensation reaction is usually performed at 30 to 150 ° C. for 1 to 30 hours.
This reaction may be performed in bulk or using a suitable solvent. As the solvent used at this time, for example,
Water, ethyl cellosolve acetate, ethyl cellosolve,
Examples include methyl cellosolve, methyl isobutyl ketone, methyl ethyl ketone, hexane, cyclohexane, heptane, benzene, toluene and the like. Among these,
Hexane, cyclohexane, heptane, toluene, etc.
Those which are poor solvents for the raw materials are particularly preferred. When a solvent is used, its amount is preferably from 10 to 700 parts by weight per 100 parts by weight of the total of phenols and terephthalaldehyde.

The compound represented by the formula (II) can be synthesized by a condensation reaction between 2,5-xylenol and terephthalaldehyde. In this case, using p-toluenesulfonic acid as a catalyst,
Preferably, toluene is used as the solvent. A preferred amount of the solvent is 50 to 500 parts by weight based on 100 parts by weight of 2,5-xylenol.
Parts by weight. The preferred use amount of 2,5-xylenol is 4 to 10 moles per 1 mole of terephthalaldehyde, and the preferred use amount of p-toluenesulfonic acid is 0.01 to 0.1 mole, more preferably 1 mole of terephthalaldehyde. Is from 0.02 to 0.06 mol. This condensation reaction is
The reaction is carried out at a temperature of 50 ° C. to reflux temperature for 5 to 30 hours.

The condensation product obtained by the above reaction can be purified by recrystallization or reprecipitation after demetalization. The demetalization ion can be performed by dissolving the product in an organic solvent which is mixed with water and separated, and washed with ion-exchanged water. Examples of the organic solvent used here include methyl isobutyl ketone, ethyl cellosolve acetate, and ethyl acetate. Demetalized ions can also be obtained by separately dissolving the product in an organic solvent which is not separated by mixing with water and charging the ion-exchanged water (reprecipitation). Examples of the organic solvent used here include methanol, ethanol, acetone and the like. The latter method has the advantage that demetalization and purification can be performed simultaneously.

In the positive radiation-sensitive resist composition of the present invention,
The alkali-soluble resin contains the phenol compound represented by the general formula (I), and usually contains other alkali-soluble resins in addition to the phenol compound. Since the phenol compound of the general formula (I) is obtained by condensation of phenols and terephthalaldehyde and is alkali-soluble, it is considered to be included in the resin component especially in a positive radiation-sensitive resist composition. For convenience, it will be considered herein as part of the alkali-soluble resin.

The content of the phenol compound represented by the general formula (I) is
4 parts by weight or more, more preferably 1 part by weight, based on the total amount of the alkali-soluble resin containing it, that is, 100 parts by weight of the total amount of the phenol compound of the general formula (I) and the other alkali-soluble resin.
It is preferably from 0 to 40 parts by weight. When the content of the phenolic compound represented by the general formula (I) is less than 4 parts by weight based on 100 parts by weight of the total amount of the alkali-soluble resin, the solubility in a developing solution composed of an alkaline aqueous solution is reduced, so that development becomes difficult. If the amount exceeds 40 parts by weight, the portion not irradiated with the radiation is easily dissolved in the developing solution, so that patterning becomes difficult.

The alkali-soluble resin used together with the phenol compound of the general formula (I) is not particularly limited, and examples thereof include polyvinyl phenol and novolak resin.

Novolak resins are, for example, phenol, o-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, 2,3,
5-trimethylphenol, 4-t-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 3-ethylphenol, 2-ethylphenol,
4-ethylphenol, 2-naphthol, 1,3-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,5
-A resin obtained by condensing phenols such as dihydroxynaphthalene alone or in combination of two or more with aldehydes such as formaldehyde by an ordinary method. This condensation reaction is usually performed at 60 to 120 ° C for 2 to 30 hours. In this reaction, an organic acid, an inorganic acid, a divalent metal salt, or the like is used as a catalyst. Specific examples of the catalyst include oxalic acid, hydrochloric acid, sulfuric acid, perchloric acid, p-toluenesulfonic acid, trichloroacetic acid, phosphoric acid, formic acid, zinc acetate, and magnesium acetate. Further, the reaction may be performed in bulk or using an appropriate solvent.

Above all, as a novolak resin, the pattern area ratio of components having a polystyrene-equivalent molecular weight of 900 or less by gel permeation chromatography (hereinafter abbreviated as GPC) (using a UV254 nm detector) by crystallization, fractionation, etc. It is preferable that the ratio is 25% or less based on the area.

The 1,2-quinonediazide compound used in the positive radiation-sensitive resist composition of the present invention is not particularly limited,
For example, 1,2-benzoquinonediazide-4sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester and the like can be mentioned. These esters can be obtained by a known method, for example, by condensing 1,2-naphthoquinonediazidosulfonyl chloride or benzoquinonediazidosulfonyl chloride with a compound having a hydroxyl group in the presence of a weak alkali. these
The 1,2-quinonediazide compounds can be used alone or as a mixture of two or more.

Here, examples of the compound having a hydroxyl group to be quinonediazide sulfonic acid esterified include hyloquinone, resorcin, phloroglucin, 2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, and 2,3,4,4. '-Tetrahydroxybenzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone, bis (p-hydroxyphenyl) methane, bis (2,4-cyhydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2 2,2-bis (p-hydroxyphenyl) propane, 2,2-bis (2,4-dihydroxyphenyl) propane, 2,2-bis (2,3,4-trihydroxyphenyl) propane, formula (In the formula, q represents a number of 0 or more and 4 or less, r represents a number of 1 or more and 5 or less, and R ₁ , R ₂ and R ₃ each represent a hydrogen atom, an alkyl group, an alkenyl group, a cyclohexyl group or an aryl group. Oxyflavans represented by the following formulas:

The preparation of the positive radiation-sensitive resist composition is carried out by mixing and dissolving an alkali-soluble resin containing a phenol compound of the general formula (I) and a 1,2-quinonediazide compound in a suitable solvent. The ratio of the alkali-soluble resin to the 1,2-quinonediazide compound is determined by the ratio of the alkali-soluble resin containing the phenol compound of the general formula (I) to 10%.
The amount of the 1,2-quinonediazide compound is usually 5 to 5 parts by weight.
It is 100 parts by weight, preferably 10 to 50 parts by weight. When the compounding amount of the 1,2-quinonediazide compound is less than 5 parts by weight, it becomes easy to dissolve in a developing solution composed of an alkaline aqueous solution, so that patterning becomes difficult. However, all of the 1,2-quinonediazide compounds cannot be decomposed, and as a result, the radiation dose must be increased, resulting in a decrease in sensitivity.

The solvent used is preferably one that evaporates at an appropriate drying rate to give a uniform and smooth coating film. Examples of such a solvent include ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether acetate, butyl acetate, methyl isobutyl ketone, and xylene. These solvents can be used alone or in combination of two or more.

The positive-working radiation-sensitive resist composition obtained as described above may further contain a small amount of a resin or a dye as an additive if necessary.

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

<Examples> Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The percentages and parts in the examples are by weight unless otherwise indicated.

Synthesis Example 1 500m equipped with stirrer, cooling pipe, water separator and thermometer
l A three-necked flask was charged with 97.74 g of 2,5-xylenol, 10.73 g of terephthalaldehyde, 195.5 g of toluene, and 0.8 g of p-toluenesulfonic acid, and reacted under reflux for 5 hours while removing condensed water. 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 the obtained product was 45.2 g, and the yield was 96.2% (based on terephthalaldehyde).

Mass spectrum: m / e 586 (M ⁺ ) Synthesis Example 2 Metacresol 14 was placed in a three-necked flask with an internal volume of 1000 ml.
9 g, paracresol 121 g, ethyl cellosolve acetate
252 g and 30.4 g of a 5% oxalic acid aqueous solution were charged, and 147.8 g of 37% formalin was added dropwise over 40 minutes while heating and stirring under reflux, and then the mixture was further heated and stirred for 7 hours to react. Then, the mixture was neutralized, washed with water and dehydrated to obtain a solution of novolak resin in ethyl cellosolve acetate. The weight average molecular weight in terms of polystyrene measured by GPC was 9,600.

Synthesis Example 3 120 g of a solution of the novolak resin obtained in Synthesis Example 2 in ethyl cellosolve acetate (novolak resin content: 41.2 g)
Into a separable flask without bottom, and further add 868.8 g of ethyl cellosolve acetate and 54 of normal heptane.
4.6 g was added, and the mixture was stirred at 20 ° C. for 30 minutes, allowed to stand, and separated.
Normal heptane in the lower layer obtained by liquid separation was removed by an evaporator to obtain a solution of novolak resin in ethyl cellosolve acetate. The weight average molecular weight in terms of polystyrene by GPC was 15,000. In addition, 75% of the low molecular weight novolak was removed by this separation operation. The obtained novolak resin has a polystyrene equivalent molecular weight of 9 by GPC.
The area ratio of the components below 00 was 7%.

Examples 1-2 Phenol compounds obtained in Synthesis Example 1 and Synthesis Example 2
Alternatively, each of the novolak resins obtained in 3 was dissolved together with a photosensitive agent in ethyl cellosolve acetate with the composition shown in Table 1 to prepare a resist composition. The solvent amount is
The film thickness was adjusted to 1.28 μm under the following coating conditions. Each of these compositions was filtered through a 0.2 μm Teflon filter to prepare a resist solution.

These resist solutions were applied at 4,000 rpm to a silicon wafer cleaned by a conventional method using a spin coater. Next, the silicon wafer was baked on a vacuum suction type hot plate at 100 ° C. for 1 minute. Thereafter, patterning exposure was performed using a reduction projection exposure apparatus using an ultra-high pressure mercury lamp as a light source while changing the exposure time stepwise for each shot.
Next, a developer SOPD (trade name) manufactured by Sumitomo Chemical Co., Ltd.
And then rinsed and dried.

The sensitivity was determined by plotting the amount of film loss and the exposure time for each shot. The remaining film ratio was determined from the remaining film thickness of the unexposed portion. The silicon wafer with the developed resist pattern is left in a clean oven set at various temperatures in an air atmosphere for 30 minutes, and then observed with a scanning electron microscope. The heat resistance was evaluated at the temperature in the oven. Further, the reduced line width for resolving the line and space was defined as the resolution.

Comparative Examples 1-2 A resist solution was prepared, coated, exposed and developed in the same manner as in Example 1 except that no phenol compound was added. Then, in the same manner as in Example 1, the sensitivity, the remaining film ratio, and the resolution were determined, and the heat resistance was evaluated.

Table 1 summarizes the results of the above Examples and Comparative Examples. As is clear from Table 1, it was recognized that the resist compositions of the examples had a better balance of sensitivity, resolution, residual film ratio and heat resistance than those of the comparative examples.

Claims (4)

(57) [Claims] 1. The compound of the general formula (I) [Wherein, R represents an alkyl group or an alkoxy group, and n represents a number of 0 or more and 3 or less] characterized in that it contains an alkali-soluble resin containing a phenolic compound represented by the formula: and a 1,2-quinonediazide compound. Positive radiation-sensitive resist composition. 2. The phenolic compound of the general formula (I) has the following formula (II) The positive radiation-sensitive resist composition according to claim 1, wherein 3. The positive-type impression according to claim 1, wherein the phenol compound represented by the general formula (I) or (II) is contained in an amount of 4 to 40 parts by weight based on 100 parts by weight of the total amount of the alkali-soluble resin. Radiation resist composition. 4. The alkali-soluble resin contains a novolak resin, and the pattern area of a component having a molecular weight of 900 or less in terms of polystyrene determined by gel permeation chromatography (using a detector of UV 254 nm) of the novolak resin is determined by gel permeation of the novolak resin. 4. The positive radiation-sensitive resist composition according to claim 1, wherein the content is 25% or less based on the total pattern area of the chromatography.