JP2692403B2 - Positive radiation-sensitive resist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to ultraviolet rays, far infrared rays (including excimer lasers, etc.), electron beams, ion beams,
The present invention relates to a positive type radiation sensitive resist composition which is sensitive to radiation such as X-rays.

[0002]

2. Description of the Related Art In recent years, integrated circuits have become finer with higher integration, and nowadays, submicron pattern formation is required, and a positive photoresist having excellent resolution is required. Conventionally, a mask contact method has been used to form an integrated circuit, but it is said that the limit is 2 μm in this method. So, instead of the mask contact method,
Attention has been paid to a reduced projection exposure method. This is a method in which a master mask (reticle) pattern is reduced and projected by a lens system to be exposed, and the resolution can be up to submicron. However, in the case of this reduced projection exposure method, one of the problems is that the throughput is low. That is, unlike batch exposure as in the conventional mask contact method, the reduced projection exposure method requires divided repetitive exposure, and therefore the total exposure time per wafer becomes long.

As a method for solving this, it is most important to improve the sensitivity of the resist used as well as to improve the apparatus. If the exposure time can be shortened by increasing the sensitivity, the throughput can be improved and the yield can be improved. On the other hand, as the degree of integration of LSI has been improved and the width of wiring has been miniaturized, dry etching has become the mainstream instead of conventional wet etching. Due to this dry etching, the heat resistance of the resist is required more than ever.

[0004]

Looking at the positive photoresists currently used from this viewpoint, it cannot be said that they are all sufficiently satisfactory in terms of sensitivity, resolution and heat resistance. In general, positive photoresist is
Since the sensitivity is lower than that of the negative type photoresist, improvement in this respect is desired.

For example, as the simplest method for achieving high sensitivity, it is known to lower the molecular weight of the alkali-soluble resin used for the positive photoresist, and according to this method, the dissolution rate in an alkali developing solution is improved. The resist sensitivity is apparently improved. However, in this method, the film loss in the non-exposed area becomes large (so-called residual film rate decreases), the pattern shape deteriorates, and the difference in dissolution rate between the exposed area and the non-exposed area in the developing solution becomes small. In addition to the problem of so-called decrease of γ value (reduction of resolution), there is a very serious inconvenience that the heat resistance of the resist decreases. That is, at present, the sensitivity,
There is no positive resist that has all of resolution and heat resistance, and there is a problem that if any one of them is improved, another property becomes worse.

An object of the present invention is to manufacture an integrated circuit,
It is an object of the present invention to provide a positive-type radiation-sensitive resist composition which is excellent in sensitivity, resolution and heat resistance and which solves the problems of the conventional techniques.

[0007]

The present inventors have found that the above problems can be solved by adding a polyphenol having a specific structure to a resist composition, and have completed the present invention.

That is, the present invention comprises an alkali-soluble novolac resin and a 1,2-quinonediazide compound,
Further, the following general formula (I)

[0009]

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(Wherein n is a number exceeding 1; a, b, c, d, e and f are each independently 0 or more and 3
The following numbers are shown, and d + f is 1 or more; R ₁ , R ₂ and R ₃ are each independently a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ alkoxy group, a carboxyl group, methoxycarbonyl. Represents a hydrogen atom, an ethoxycarbonyl group or a halogen atom; R ₄ represents a hydrogen atom, a C _{1 to} C ₆ alkyl group or C ₆ to
A positive radiation-sensitive resist composition containing a polyphenol represented by C ₁₀ aryl group) and having a polystyrene-equivalent weight average molecular weight of 550 or less by GPC.

In the general formula (I), the groups represented by R ₁ , R ₂ and R ₃ are particularly preferably C _{1 to} C ₅ alkyl groups, methoxy groups, ethoxy groups and carboxyl groups. R ₄ is preferably a hydrogen atom, a C ₁ -C ₅ alkyl group or an aryl group.

Those having a small value of n in the general formula (I), that is, those having a polystyrene-equivalent weight average molecular weight of 550 or less by GPC, are particularly excellent in sensitivity, resolution and heat resistance in combination with existing alkali-soluble resins. It is preferable because a resist composition can be provided.

A, b, c, d, e in the general formula (I)
The values of and are as described above, but it is particularly preferable that each of b, d and f is 1 or more. More preferably, b, d and f are each 1.

The polyphenol represented by the general formula (I) can be synthesized, for example, by condensing the corresponding phenol with a carbonyl compound in the presence of an acid catalyst.

Examples of the phenols used here include phenol, o-cresol, m-cresol and p.
-Cresol, 3,5-xylenol, 2,5-xylenol, 2,3-xylenol, 2,4-xylenol, 2,6-xylenol, 3,4-xylenol,
2,3,5-trimethylphenol, 4-t-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, 4-n-hexylresorcinol, 4 -T-butylcatechol, 4
-Methoxyphenol, 3-methoxyphenol, 2-
Methoxyphenol, 3-methoxycatechol, 2-methoxyresorcinol, 4-methoxyresorcinol,
2,3-dimethoxyphenol, 2,5-dimethoxyphenol, 3,5-dimethoxyphenol, 2-chloro-5-methylphenol, methyl gallate, ethyl gallate, 3-methoxy-4,5-dihydroxymethyl benzoate , Ethyl 3-methoxy-4,5-dihydroxybenzoate, methyl 4-methoxy-3,5-dihydroxybenzoate, ethyl 4-methoxy-3,5-dihydroxybenzoate, 3,4-dimethoxy-5-hydroxybenzoate Ethyl acid salt, methyl 3,5-dimethoxy-4-hydroxybenzoate, ethyl 3,5-dimethoxy-4-hydroxybenzoate, 3-ethylphenol, 2-ethylphenol, 4-ethylphenol, 2,3,5- Triethylphenol, 3,5-diethylphenol, 2,5-diethylphenol, 2, 3-diethylphenol etc. are mentioned. These phenols can be used alone or in combination of two or more.

Examples of the carbonyl compound used in this condensation reaction include benzaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 2,4-dihydroxybenzaldehyde, 2, and the like. 5-dihydroxybenzaldehyde,
3,4-dihydroxybenzaldehyde, 4-carboxybenzaldehyde, acetophenone, o-hydroxyacetophenone, m-hydroxyacetophenone, p
-Hydroxyacetophenone, heptanophenone, 2,
4-dihydroxyacetophenone, 2,5-dihydroxyacetophenone, 2,6-dihydroxyacetophenone, o-methoxybenzaldehyde, m-methoxybenzaldehyde, p-methoxybenzaldehyde, 2,
3-dimethoxybenzaldehyde, 2,4-dimethoxybenzaldehyde, 2,5-dimethoxybenzaldehyde, 3,4-dimethoxybenzaldehyde, 2,4-
Dimethoxyacetophenone, 2,5-dimethoxyacetophenone, 3,4-dimethoxyacetophenone, 3,5
-Dimethoxyacetophenone, 2,2'-dihydroxybenzophenone and the like. These carbonyl compounds can also be used alone or in combination of two or more.

As described above, the phenols can be used alone or in combination of two or more, and the carbonyl compounds can be used alone or in combination of two or more, but only one kind of phenol is used. , And when only one carbonyl compound is used, a polyphenol represented by the following general formula (II) is obtained.

[0018]

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In the formula, n, a, b, c, d, R ₁ , R ₂ and R ₄ have the same meanings as described above.

Examples of the acid catalyst used in the condensation reaction include organic acids, inorganic acids, and divalent metal salts. Specific examples include oxalic acid, hydrochloric acid, sulfuric acid, perchloric acid, p
-Toluenesulfonic acid, trichloroacetic acid, phosphoric acid, formic acid, zinc acetate, zinc chloride, magnesium acetate and the like. It is preferable to use a hydrochloric acid catalyst from the viewpoint that the selectivity is good and the reaction rate can be controlled by the concentration.

The amount of carbonyl compound used is preferably 0.02 to 3 mol per mol of phenols, and the amount of acid catalyst used is 0.01 to 3 mol per mol of carbonyl compound.
0.7 mol is preferred. The condensation reaction is usually 30 to 250 ° C.
For 2 to 30 hours.

The reaction may be carried out in bulk or with a suitable solvent. Examples of the solvent used at this time include water, alcohols such as methyl alcohol, ethyl alcohol, iso-propyl alcohol, n-butyl alcohol, and iso-amyl alcohol, or ethyl cellosolve acetate, ethyl cellosolve,
Examples include methyl cellosolve, hexane, cyclohexane, heptane, benzene, toluene and xylene. These solvents are preferably 10 to 1000 per 100 parts by weight of the total amount of phenols and carbonyl compounds.
Used by weight.

In the present invention, it is preferable to use 4 to 40 parts by weight of the polyphenol of the general formula (I) based on 100 parts by weight of the total amount of the alkali-soluble resin and the polyphenol of the general formula (I). The polyphenol of the general formula (I) is 4
If the amount is less than 10 parts by weight, the solubility in a developing solution composed of an alkaline aqueous solution is lowered, so that it becomes difficult to develop, and if it exceeds 40 parts by weight, a portion not exposed to radiation is easily dissolved in the developing solution. It gets harder.

The alkali-soluble resin used in the resist composition of the present invention is, for example, polyvinylphenol or novolac resin, and novolac resin is particularly preferable. Examples of the novolac resin include phenol and 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-
Phenols such as t-butylphenol, 3-ethylphenol, 2-ethylphenol, 4-ethylphenol, 2-naphthol, 1,3-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and 1,5-dihydroxynaphthalene are used alone. Examples thereof include resins that are condensed with formalin by a conventional method, or in combination of two or more kinds.

This condensation reaction is usually carried out at 60 to 120 ° C.
It is carried out for 2 to 30 hours. As the catalyst, an organic acid, an inorganic acid, a divalent metal salt or the like is 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. The reaction may be carried out in bulk or with a suitable solvent.

Particularly, as the novolac resin, low molecular weight novolac corresponding to 30 to 90% by weight of the novolac resin having a weight average molecular weight (polystyrene conversion value by GPC) of 2000 or more is removed by crystallization or fractionation. The high molecular weight novolac obtained by

The 1,2-quinonediazide compound used in the resist composition of the present invention is not particularly limited, but for example, 1,2-benzoquinonediazide-4-sulfonic acid ester and 1,2-naphthoquinonediazide-4-
Sulfonate, 1,2-naphthoquinonediazide-
Examples thereof include 5-sulfonic acid ester.

These esters can be obtained by a known method, for example, by condensing 1,2-naphthoquinonediazidesulfonic acid chloride or benzoquinonediazidesulfonic acid chloride with a hydroxyl group-containing compound in the presence of a weak alkali. . Here, examples of the hydroxyl group-containing compound include hydroquinone, resorcin, phloroglucin, 2,4-dihydroxybenzophenone,
2,3,4-trihydroxybenzophenone, 2,3
4,4'-tetrahydroxybenzophenone, 2,
2 ', 4,4'-tetrahydroxybenzophenone, bis (p-hydroxyphenyl) methane, bis (2,4-
Dihydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2,2-bis (p-hydroxyphenyl) propane, 2,2-bis (2,4-)
Dihydroxyphenyl) propane, 2,2-bis (2,2
3,4-trihydroxyphenyl) propane, oxyflavans

[0029]

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And the like. The 1,2-quinonediazide compounds may be used alone or in combination of two or more.

The positive-type radiation-sensitive resist composition of the present invention is prepared by mixing a 1,2-quinonediazide compound, an alkali-soluble resin and the polyphenol represented by the general formula (I) in a suitable solvent and dissolving the mixture. It can be prepared. The polyphenol represented by the general formula (I) is prepared separately from the alkali-soluble resin, as is clear from the above description. In the resist composition of the present invention, it is usually preferable to use 5 to 100 parts by weight of a 1,2-quinonediazide compound based on 100 parts by weight of the alkali-soluble resin and the polyphenol represented by the general formula (I). More preferably, 10 to 50 parts by weight is used. If the blending amount of the 1,2-quinonediazide compound is less than 5 parts by weight, the entire resist film after coating easily dissolves in a developing solution containing an alkaline aqueous solution, which makes patterning difficult. Further, if the amount of the 1,2-quinonediazide compound added exceeds 100 parts by weight, it is impossible to decompose all of the added 1,2-quinonediazide compound by irradiation for a short time, resulting in a large amount of irradiation. As a result, the sensitivity is lowered.

The solvent used is preferably one which 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, methyl cellosolve, propylene glycol monomethyl ether acetate, butyl acetate, methyl isobutyl ketone, and xylene. These solvents may 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 resin or dye as an additive, if necessary.

[0034]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition,% and parts in the following examples are based on weight unless otherwise specified.

Synthesis Example 1 50 equipped with a stirrer, cooling tube, water separator and thermometer
A 0 ml three-necked flask was charged with 141 g of phenol, 9.2 g of p-hydroxybenzaldehyde, 0.7 g of p-toluenesulfonic acid and 28 g of cyclohexane, and heated at 80 ° C. in an oil bath at 80 ° C. while removing condensed water.
Allowed to react for hours. After further neutralizing and washing with water, the pressure inside the flask was reduced to remove water and unreacted phenol. Then, the obtained compound was collected on a pallet.
The yield was 14.1 g. According to GPC analysis, the weight average molecular weight was 550 in terms of polystyrene.

Synthesis Example 2 50 equipped with a stirrer, a cooling pipe, a water separator and a thermometer
In a 0 ml three-necked flask, 106 g of phenol, 41 g of metacresol, 9 p-hydroxybenzaldehyde
g, p-toluenesulfonic acid 0.7 g, and cyclohexane 29 g were charged, and the mixture was heated and stirred in an oil bath at 80 ° C.
The reaction was carried out for 4 hours while removing the condensed water. Further neutralization,
After washing with water, the pressure inside the flask was reduced to remove water, unreacted phenol and metacresol. Then
The obtained compound was collected on a palette. Earn 17.0
g. According to the analysis by GPC, the weight average molecular weight was 370 in terms of polystyrene.

Synthesis Example 3 50 equipped with a stirrer, cooling tube, water separator and thermometer
In a 0 ml three-necked flask, 162.2 g of metacresol, p
-Hydroxybenzaldehyde (9.2 g), p-toluenesulfonic acid (0.7 g) and cyclohexane (34 g) were charged,
The mixture was reacted in an oil bath with heating and stirring at 80 ° C. for 4 hours while removing condensed water. After further neutralizing and washing with water, the pressure inside the flask was reduced to remove water and unreacted meta-cresol. The compound obtained was then collected on a pallet. The yield was 14.6 g. By GPC analysis, the weight average molecular weight was 340 in terms of polystyrene.

Synthesis Example 4 A three-necked flask having an internal volume of 1000 ml was charged with 149 g of meta-cresol, 121 g of para-cresol, 252 g of ethyl cellosolve acetate and 30.4 g of 5% oxalic acid, and the mixture was heated and stirred in an oil bath at 90 ° C. to form an aqueous formalin solution ( (37.0%) 147.8 g was added dropwise over 40 minutes, and then the mixture was heated and stirred for another 7 hours for reaction. Then neutralization,
After washing with water and dehydration, an ethyl cellosolve acetate solution of the novolak resin was obtained. The polystyrene reduced weight average molecular weight by GPC was 9,600.

Synthetic Example 5 Ethyl cellosolve acetate solution of the novolak resin obtained in Synthetic Example 4 (novolac resin content 41.2%) 1
20 g was placed in a 3-liter bottomed separable flask, and 868.8 g of ethyl cellosolve acetate and n- were added.
After adding 544.6 g of heptane and stirring at 20 ° C for 30 minutes,
The solution was left standing and separated. The n-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 polystyrene reduced weight average molecular weight by GPC was 15,500. In addition, 75% of low molecular weight novolac was obtained by this separation operation.
Removed.

Examples 1 to 3 and Comparative Examples 1 to 2 The polyphenols obtained in Synthesis Examples 1 to 3 and the novolac resins obtained in Synthesis Examples 4 and 5 were each combined with a photosensitizer in the composition shown in Table 1 to give ethyl. A resist composition was prepared by dissolving it in cellosolve acetate. The solvent amount is
Under the coating conditions shown below, the film thickness was adjusted to 1.28 μm. Each of these compositions was filtered through a 0.2 μm Teflon filter to prepare a resist solution.

This resist solution was applied to a silicon wafer washed by a conventional method at 4000 rpm by using a spin coater. Then, the silicon wafer was baked on a vacuum adsorption type hot plate at 100 ° C. for 1 minute. After that, a reduction projection exposure apparatus using an ultra-high pressure mercury lamp as a light source was used, and the exposure time was changed stepwise for each shot for exposure.
Then, development was performed using a developing solution SOPD (trade name of Sumitomo Chemical Co., Ltd.). After rinsing and drying, the film reduction amount of each shot and the exposure time were plotted to determine the sensitivity. The remaining film ratio was determined from the remaining film thickness of the unexposed portion.

Further, the developed silicon wafer with a resist pattern is left in an air atmosphere for 30 minutes in a clean oven set to various temperatures, and then the resist pattern is observed with a scanning electron microscope. The heat resistance was evaluated.

The results are summarized in Table 1. As is clear from Table 1, in Examples, the sensitivity, resolution and heat resistance are well balanced, and the performance is remarkably improved as compared with Comparative Examples.

[0044]

Footnote ^{1 to} Table-1 ^{* 1} Photosensitizer (a): 1,2-naphthoquinonediazide-5-
Condensation product of sulfonyl chloride and 2,3,4-trihydroxybenzophenone Photosensitizer (b): Condensation product of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 2,3,4,4'-tetrahydroxybenzophenone ^{* 2} Temperature in the clean oven when the resist pattern begins to droop ^{* 3} Minimum line width that resolves lines and spaces

[0046]

The radiation-sensitive resist composition of the present invention comprises
Compared with existing resist compositions, it has excellent sensitivity, and has improved resolution and heat resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Hanabata 3-98 Kasugade, Konohana-ku, Osaka City Sumitomo Chemical Co., Ltd. (72) Takeshi Hioki 3-chome, Kasugade, Konohana-ku, Osaka No. 98 in Sumitomo Chemical Co., Ltd. (56) Reference JP-A 63-2044 (JP, A) JP-A 60-50531 (JP, A) JP-A 60-173544 (JP, A) European patent application Publication 239423 (EP, A)

Claims (4)

(57) [Claims] 1. An alkali-soluble resin containing an alkali-soluble resin and a 1,2-quinonediazide compound, and further comprising the alkali -soluble resin.
Formula (I) below prepared separately from fat (In the formula, n is a number exceeding 1; a, b, c, d, e and f are each independently 0 or more and 3
The following numbers are shown, and d + f is 1 or more; R ₁ , R ₂ and R ₃ are each independently a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ alkoxy group, a carboxyl group, methoxycarbonyl. Represents a hydrogen atom, an ethoxycarbonyl group or a halogen atom; R ₄ represents a hydrogen atom, a C _{1 to} C ₆ alkyl group or C ₆ to
A positive radiation-sensitive resist composition containing a polyphenol represented by C ₁₀ aryl group) and having a polystyrene-equivalent weight average molecular weight of 550 or less by GPC. 2. A polyphenol is represented by the following general formula (II): Claim (wherein, n, a, b, c , d, R 1, R 2 Contact and R ₄ are as defined in claim 1) indicated by 1
A composition as described. 3. The composition according to claim 1, wherein the polyphenol is present in an amount of 4 to 40 parts by weight based on 100 parts by weight of the total of the alkali-soluble resin and the polyphenol. 4. The alkali-soluble resin is a novolac resin, and the novolac resin is 30 to 9 out of novolac resins having a weight average molecular weight of 2,000 or more (in terms of polystyrene).
The composition according to any one of claims 1 to 3, which is obtained by removing a low molecular weight novolak corresponding to 0% by weight.