JPH07191461A - Positive resist composition - Google Patents

Abstract

PURPOSE:To provide a positive resist compsn. which is excellent in balance of various performances, such as sensitivity, resolution, heat resistance, profile and depth of focus, and is free from development residues. CONSTITUTION:This positive resist compsn. contains a novolak resin obtd. by bringing a phenol mixture composed of m-cresol, 3,4-xylenon and the phenols expressed by formula (where R1 denotes a lower alkyl group; R2 denotes hydrogen or lower alkyl group, respectively) and aldehydes into condensation reaction, a quinone diazide compsn. and an alkali-soluble compsn. having a mol.wt. of <900.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist composition sensitive to radiation such as ultraviolet rays and deep ultraviolet rays including excimer laser.

[0002]

2. Description of the Related Art In recent years, integrated circuits have become finer with higher integration, and submicron pattern formation is required. As a result, there is a demand for a positive resist composition that is excellent in performance such as resolution, profile, and depth of focus. In particular, 0.5 μm in the production of 16-64M DRAM
It is necessary to resolve the following line width patterns with a good profile and a wide depth of focus. JP 5-27446
In the publication, (a) 100 parts by weight of an alkali-soluble novolac resin having a standard polystyrene equivalent weight average molecular weight in the range of 4000 to 20000, (b) 5 to 100 parts by weight of a phenolic compound having a molecular weight in the range of 100 to 1000 And (c)

[0003]

[Chemical 2]

[Wherein R¹~ R¹⁹Same or different, water
Elementary atoms, hydroxyl groups, alkyl groups having 1 to 6 carbon atoms, 6 carbon atoms
~ 14 aryl groups or C7-18 aralkyl groups
Yes (however, R¹~ R^FiveAt least one of R⁶~ R^Ten
At least one of R and¹⁵~ R ¹⁹At least one of the water
Acid group), R^a, R^bAnd R^cAre the same or different,
A hydrogen atom or an alkyl group having 1 to 6 carbon atoms]
1,2-quinonediazidosulfur, a phenolic compound
Characterized by containing 1 to 85 parts by weight of phosphonate
A positive resist composition is described. However
While this composition is satisfactory from the viewpoint of depth of focus, etc.
Not a thing.

[0005]

The present invention provides a positive resist composition which has an excellent balance of various properties such as sensitivity, resolution, heat resistance, profile and depth of focus and has no development residue (scum).

[0006]

The present invention provides (A) m-cresol, 3,4-xylenol and general formula (I).

[0007]

[Chemical 3]

(Wherein R ₁ represents a lower alkyl group, R ₂ represents a hydrogen atom or a lower alkyl group, respectively) and a novolak obtained by subjecting a phenol mixture of phenols and an aldehyde to a condensation reaction. Resin and (B)
A positive resist composition comprising a 1,2-quinonediazide compound and (C) an alkali-soluble compound having a molecular weight of less than 900.

Examples of the phenols represented by the general formula (I) include o-cresol, o-ethylphenol, o-butylphenol and 2,5-xylenol. At least one selected from o-cresol and 2,5-xylenol is preferable, o-cresol or 2,5-xylenol is more preferable, and 2,5-xylenol is particularly preferable. A preferred composition of the above phenol mixture is m-cresol:
3,4-xylenol: phenols represented by the general formula (I) = 55 to 75: 5 to 10:15 to 30 (mol%) [more preferable composition is 60 to 75: 8 to 10:15 to 30] Is the range.

Examples of the aldehydes include at least one selected from formaldehyde, paraformaldehyde, acetaldehyde, glyoxal, benzaldehyde, p-hydroxybenzaldehyde, terephthalaldehyde and salicylaldehyde. Formaldehyde is preferred as the aldehyde. The condensation reaction is performed by a conventional method. The reaction temperature and time are usually 60 to 120 ° C and 2 to 30 hours, and the catalyst is an inorganic acid (hydrochloric acid, sulfuric acid, phosphoric acid, etc.), an organic acid (oxalic acid, acetic acid, p-toluenesulfonic acid, etc.) or a divalent metal. A salt (zinc acetate or the like) is used, and the condensation is performed in the presence or absence of a reaction solvent. The novolac resin obtained by the condensation reaction has a GPC pattern area ratio (detector: UV 254 nm) in the range of a molecular weight of 900 or less in terms of polystyrene, measured by means such as fractionation. Is preferably adjusted to 25% or less (more preferably 20% or less). Fractionation is carried out by using a novolak resin obtained by condensation, using a good solvent (for example, alcohols such as methanol or ethanol, ketones such as acetone, methyl ethyl ketone or methyl isobutyl ketone, ethylene glycol ethers, ether esters such as ethyl cellosolve acetate, or tetrahydrofuran. Etc.) and then the resulting solution is poured into water for precipitation, or a solution is poured into a solvent such as pentane, hexane or heptane for liquid separation.

As the 1,2-quinonediazide compound,
Examples thereof include compounds in which a phenol compound and 1,2-naphthoquinonediazide-4- or -5-sulfonic acid chloride are condensed in the presence of a weak alkali such as triethylamine or sodium carbonate. Examples of the phenol compound include compounds described by the general formula on page 3 of JP-A-2-103543, compounds described by general formula (I) or (II) in JP-A-2-32352, 2-26
The compounds described by the general formula (I) in 9351, JP-A-4
Compounds described by formula on page 4 of -50851, compounds described by formula (1) in JP-A-5-27446 and compounds represented by general formula (I) in JP-A-3-185447. Examples include oxyflavans containing the above compounds. These 1,2-quinonediazide compounds may be used alone or in combination of two or more. The preferable amount of the 1,2-quinonediazide compound used is 10 to 10% of the total solid content of the positive resist composition.
50% by weight.

The alkali-soluble compound having a molecular weight of less than 900 is preferably a compound having at least two phenolic hydroxyl groups. More preferable alkali-soluble compounds are the compounds described in JP-A-2-275955 and JP-A-4-275851, the compounds described in JP-A-4-50851 and JP-A-3-50851. Examples thereof include compounds described by the general formula (I) in JP-A-179353. The preferred amount of the alkali-soluble compound having a molecular weight of less than 900 is 3 to 40 in the total solid content of the positive resist composition.
% By weight. If desired, the positive resist composition of the present invention may contain additives commonly used in the art, such as dyes and adhesion improvers.

As the solvent used for preparing the positive resist solution, those having an appropriate drying rate and evaporating the solvent to give a uniform and smooth coating film are preferable. As such a solvent,
For example, glycol ether esters such as ethyl cellosolve acetate and propylene glycol monomethyl ether acetate, solvents described in JP-A-2-220056, ethyl pyruvate, esters such as n-amyl acetate or ethyl lactate, 2-heptanone, γ. -Butyrolactone and other ketones. These solvents may be used alone or in admixture of two or more.

[0014]

The positive resist composition of the present invention has sensitivity,
Excellent balance of performance such as resolution, profile, heat resistance and depth of focus, and no scum.

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “part” means “part by weight”.

Synthesis Example 1 3,4-xylenol 16.8 g, 2,5-xylenol 33.6 g, m in a three-necked flask having an internal volume of 1000 ml.
-Cresol 133.8 g, methyl isobutyl ketone 1
40.2 g, oxalic acid dihydrate 4.2 g and 90% acetic acid 56.
Charge 2g and stir it with 37% formalin aqueous solution 1
22 g was added dropwise over 60 minutes. Then, at 95 ℃ 10
Reacted for hours. Then, it was washed with water and dehydrated to obtain a methyl isobutyl ketone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 5,123. Synthetic Example 2 3,4-xylenol 14.4 g, 2,5-xylenol 57.6 g, m in a three-necked flask having an internal volume of 1000 ml.
-Cresol 114.7 g, methyl isobutyl ketone 1
20.1 g, oxalic acid dihydrate 4.2 g and 90% acetic acid 56.
Charge 2g and stir it with 37% formalin aqueous solution 1
22 g was added dropwise over 60 minutes. Then, at 95 ℃ 10
Reacted for hours. Then, it was washed with water and dehydrated to obtain a methyl isobutyl ketone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 5423. Synthesis Example 3 3,4-xylenol 16.8 g, m-cresol 133.8 g, o-cresol 29.7 g, and methyl isobutyl ketone 336 were placed in a three-necked flask having an internal volume of 1000 ml.
g, 4.2 g of oxalic acid dihydrate and 56.2 g of 90% acetic acid were added, and 122 g of a 37% formalin aqueous solution was added dropwise over 60 minutes while stirring. Then, it was made to react at 95 degreeC for 12 hours. Then, it was washed with water and dehydrated to obtain a methyl isobutyl ketone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 5002. Synthesis Example 4 3,4-xylenol 16.8 g, m-cresol 133.8 g, o-cresol 59.5 g, and methyl isobutyl ketone 391 were placed in a three-necked flask having an internal volume of 1000 ml.
g, 4.9 g of oxalic acid dihydrate and 65.5 g of 90% acetic acid were added, and 140 g of 37% aqueous formalin solution was added dropwise over 60 minutes while stirring. Then, it was made to react at 95 degreeC for 12 hours. Then, it was washed with water and dehydrated to obtain a methyl isobutyl ketone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 5,207.

Synthesis Example 5 Methyl isobutyl ketone solution of the novolak resin obtained in Synthesis Example 1 (novolac resin content 46.9% by weight)
Charge 200g into a 5L bottomed separable flask,
Further, 269 g of methyl isobutyl ketone and 319 g of normal heptane were added, and the mixture was stirred at 60 ° C. for 30 minutes and then allowed to stand,
The layers were separated. After the liquid separation, 2-heptanone 30 was added to the obtained lower layer.
0 g was charged, and then methyl isobutyl ketone and normal heptane were removed by an evaporator to obtain a 2-heptanone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 7632, and the area ratio in the polystyrene reduced molecular weight range of 900 or less was 16.4% with respect to the entire pattern area. Synthesis Example 6 Methyl isobutyl ketone solution of the novolak resin obtained in Synthesis Example 2 (novolac resin content 40.5% by weight)
Charge 200g into a 5L bottomed separable flask,
Further, 205.3 g of methyl isobutyl ketone and 276.2 g of normal heptane were added, and the mixture was stirred at 60 ° C. for 30 minutes, allowed to stand, and separated. After liquid separation, 300 g of 2-heptanone was charged to the obtained lower layer, and then methyl isobutyl ketone and normal heptane were removed by an evaporator to obtain a 2-heptanone solution of novolak resin. GPC
The polystyrene reduced weight average molecular weight was 7802, and the area ratio in the polystyrene reduced molecular weight range of 900 or less was 16.4% with respect to the entire pattern area. Synthesis Example 7 Methyl isobutyl ketone solution of the novolac resin obtained in Synthesis Example 3 (novolac resin content 37.7% by weight)
Charge 150g into a 5L bottomed separable flask,
Further, 140 g of methyl isobutyl ketone and 183 g of normal heptane were added, and the mixture was stirred at 60 ° C. for 30 minutes and then allowed to stand,
The layers were separated. After the liquid separation, 2-heptanone 20 was added to the obtained lower layer.
0 g was charged, and then methyl isobutyl ketone and normal heptane were removed by an evaporator to obtain a 2-heptanone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 7362, and the area ratio in the polystyrene reduced molecular weight range of 900 or less was 18.3% with respect to the entire pattern area. Synthetic Example 8 Methyl isobutyl ketone solution of the novolak resin obtained in Synthetic Example 4 (novolac resin content 42.5% by weight)
Charge 150g into a 5L bottomed separable flask,
Further, 127 g of methyl isobutyl ketone and 189 g of normal heptane were added, and the mixture was stirred at 60 ° C. for 30 minutes and then allowed to stand,
The layers were separated. After the liquid separation, 2-heptanone 20 was added to the obtained lower layer.
0 g was charged, and then methyl isobutyl ketone and normal heptane were removed by an evaporator to obtain a 2-heptanone solution of novolak resin. The polystyrene reduced weight average molecular weight by GPC was 7052, and the area ratio in the polystyrene reduced molecular weight range of 900 or less was 20.5% with respect to the entire pattern area.

Examples (Example Nos. 1 to 4) Novolak resins (abbreviated as resins in the table), 1,2-quinonediazide compounds (abbreviated as photosensitizers in the table) and alkali-soluble compounds (additives in the table) (Abbreviated as) is mixed and dissolved in 51 parts of 2-heptanone with the composition shown in the table below. The solution was filtered through a Teflon filter having a pore size of 0.2 μm to prepare a resist solution. 1. Using a spin coater, apply the above resist solution to a silicon wafer washed by a conventional method.
It was applied to a thickness of 06 μm and baked at 90 ° C. for 1 minute on a hot plate. Next, a reduction projection exposure device having an exposure wavelength of 365 nm (i-line) (manufactured by Nikon Corporation, NSR1755i
7ANA = 0.5) and the exposure amount was changed stepwise for exposure. Then, this wafer was baked on a hot plate at 110 ° C. for 1 minute. This was developed with SOPD [alkali developer; product of Sumitomo Chemical Co., Ltd.] for 1 minute to obtain a positive pattern. The resolution was 0.5 .mu.m. The dimension of the smallest line-and-space pattern that can be separated without film loss at the exposure amount (effective sensitivity) at which the line-and-space pattern becomes 1: 1 was evaluated by a scanning electron microscope. The profile and scum of the 0.5-μm and 0.35-μm line-and-space patterns, respectively, were observed with a scanning electron microscope for cross-sectional shape and development residue at effective sensitivity. For the heat resistance, the degree of dripping of the resist pattern when heated on a hot plate at 124 ° C. for 3 minutes was evaluated on a five-point scale.
(5 indicates the best heat resistance, and 1 indicates the poor heat resistance.)

[0019]

[Table 1]

In the above table, additive C is represented by the following formula

[0021]

[Chemical 4]

An alkali-soluble compound having a molecular weight of less than 900 represented by

In the above table, the photosensitizers B and A are 1,2-naphthoquinonediazide-5-sulfonic acid chloride and the following formulas.

[0024]

[Chemical 5]

[0025]

[Chemical 6]

It is a condensation product with a phenol compound represented by: 1,2-
The amounts of naphthoquinonediazide-5-sulfonic acid chloride used are 2 mol and 2.8 mol, respectively.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Hashimoto Sumitomo Chemical Co., Ltd. 3-98 Kasugadeka, Konohana-ku, Osaka, Osaka

Claims (6)

[Claims] 1. (A) m-cresol, 3,4-xylenol and the general formula (I): (Wherein R ₁ represents a lower alkyl group, R ₂ represents a hydrogen atom or a lower alkyl group, respectively), and a novolak resin obtained by subjecting a phenol mixture of phenols and an aldehyde to a condensation reaction, A positive resist composition comprising (B) a 1,2-quinonediazide compound and (C) an alkali-soluble compound having a molecular weight of less than 900. 2. The composition of the phenol mixture is in the range of m-cresol: 3,4-xylenol: phenols represented by the general formula (I) = 55 to 75: 5 to 10:15 to 30 (mol%). The positive resist composition according to claim 1, wherein the positive resist composition is present. 3. The polystyrene reduced molecular weight of novolac resin
The positive resist composition according to claim 1 or 2, wherein the GPC pattern area ratio in the range of 900 or less is 25% or less with respect to the total pattern area excluding the pattern area of the unreacted phenol mixture. 4. A phenol represented by the general formula (I) is o.
-The positive resist composition according to any one of claims 1 to 3, which is at least one selected from cresol and 2,5-xylenol. 5. A phenol represented by the general formula (I) is o.
-Cresol or 2,5-xylenol
The positive resist composition as described in any one of 3 to 3. 6. The positive resist composition according to claim 1, wherein the alkali-soluble compound having a molecular weight of less than 900 is a compound having two or more phenolic hydroxyl groups.