JPH06348007A - Photosensitive resin composition and production thereof - Google Patents

Abstract

PURPOSE:To provide the photosensitive resin composition enhanced in various characteristics, such as sensitivity, resolution, profile, focal depth, and heat resistance, and free from occurrence of scum and its manufacturing method. CONSTITUTION:This invention comprises the photosensitive resin composition and its manufacturing method, and this composition is characterized by containing a resist solvent, an o-naphthoquinonediazido compound, and a novolak having a weight average molecular weight of 200-900 obtained by reaction of phenols represented by formula I with formaldehyde on the presence of a catalyst, or an alkali-soluble novelak resin obtained by condensation reaction of 3 of a compound having a molecular weight of 200-900 and a phenol cccmpound represented by formula II and formaldehyde. In formulae I and II, each of R1-R6, is, independently, H, hydroxy, or 1-6 C alkyl.

Description

Detailed Description of the Invention

[0001]

The present invention relates to ultraviolet rays, far ultraviolet rays (including excimer lasers, etc.), electron beams, ion beams, X-rays.
The present invention relates to a photosensitive resin composition sensitive to radiation such as rays and a method for producing the same.

[0002]

2. Description of the Related Art Today, submicron pattern formation is required with the high integration of integrated circuits, and various performances such as sensitivity, resolution, profile, depth of focus and heat resistance are excellent, and scum (development residual) is excellent. There is a need for positive resists. Particularly in the manufacture of 16 to 64 MDRAM, it is necessary to resolve a pattern having a line width of 0.5 μm or less with a good profile and a wide depth of focus. For example, JP-A-60-164740 discloses m-cresol and p.
-Cresol mixed cresol with xylenol and / or
Or the following general formula

[0003]

[Chemical 3]

(Wherein R ₁ and R ₂ are the same or different,
A hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, R ₃ and R ₄ are the same or different, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and R _{5 to} R ₇ are the same or different, a hydrogen atom, a carbon atom Number 1 to 4 alkyl group, hydroxyl group, and n is 0 or 1
Represents ) Compound of 3) and aldehydes
A positive type photosensitive resin composition containing a 1,2-quinonediazide compound as well as a novolak resin condensed with the above is described. Further, in claim 1 of JP-A-62-227144, m-cresol 6 to 94 mol% and the following general formula

[0005]

[Chemical 4]

[In the formula, X is --CH ₃ , --C ₂ H ₅ , --C
(CH _{3) 3,} means -CO ₂ CH ₃ or -CO ₂ C ₂ H _5, a 3 ≧ n ≧ 1,3 ≧ m ≧ 1. ] The compound represented by the formula (excluding m-cresol) is obtained by condensing phenols containing formaldehyde of 94 to 6 mol% and formaldehyde, and has a polystyrene reduced molecular weight of 6300 as determined by the GPC method using monodisperse polystyrene as a standard. ~ 25000, 25
When the maximum height values of peaks in the range of 00 to 6000 and 150 to 900 are a, b, and c, respectively, a / b = 0 to
A positive-type radiation-sensitive resin composition containing an alkali-soluble novolac resin in the range of 1.5 and c / b = 0.4 to 2, and a 1,2-quinonediazide compound is described, page (4) of the publication. In the upper left column, as a reaction method for obtaining an alkali-soluble novolac resin, a method of reacting by adding phenols to formaldehyde and an acid catalyst as the reaction progresses is illustrated. In this method, a part of phenols, formaldehyde and an acid catalyst are charged and polymerized,
After that, the remaining phenols are added and reacted as the reaction progresses. Further, claim 5 of JP-A-2-84414 describes a positive photosensitive photoresist containing a novolac resin and a photosensitizer, wherein (a) phenol, a phenol derivative or a mixture thereof is used as the novolac resin. And (b) a novolak resin which is a condensation product of an aldehyde, wherein the condensation product of formaldehyde or an aldehyde mixture comprising a formaldehyde precursor and a monohydroxyaromatic aldehyde is used as the aldehyde. Photosensitive photoresists are described. However, these compositions and photoresists are not satisfactory in terms of resolution, profile, depth of focus, etc.

[0007]

The present invention provides a photosensitive resin composition which is excellent in various properties such as sensitivity, resolution, profile, depth of focus and heat resistance and has no scum, and a method for producing the same.

[0008]

The present invention has the general formula (I
a)

[0009]

[Chemical 5]

(Wherein R _{1 to} R ₃ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) and formaldehyde are reacted in the presence of an acid catalyst. A novolak having a weight average molecular weight of 200 to 900 or a compound having a molecular weight of 200 to 900, which is a reaction product obtained, and a general formula (Ib)

[0011]

[Chemical 6] (In the formula, R _{4 to} R ₆ each independently represents a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 6 carbon atoms) and a formaldehyde and 3 are condensed, Moreover, an alkali-soluble novolac resin, a resist solvent and an o-naphthoquinonediazide compound having a GPC pattern area ratio in the range of molecular weight of 900 or less to 25% or less (in terms of polystyrene) of the total pattern area excluding the pattern area of unreacted phenol compound And a reaction mixture obtained by reacting the phenols represented by the general formula (Ia) with formaldehyde in the presence of an acid catalyst,
Further, it is a process for producing a photosensitive resin composition, which comprises mixing an alkali-soluble novolac resin obtained by condensation with a phenol compound represented by the general formula (Ib) and formaldehyde, a resist solvent and an o-naphthoquinonediazide compound. .

The phenols represented by the general formula (Ia) include xylenols such as 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 3,4-xylenol and 3,5 xylenol, 3,3. 5-diethylphenol, 2,5-diethylphenol, 2,3-
Diethylphenol, 2,4-diethylphenol,
Diethylphenol such as 2,6-diethylphenol and 3,4-diethylphenol, trimethylphenol such as 2,3,5-trimethylphenol, and 2-t
-Butyl-5-methylphenol and 3-t-butyl-
Preferred is t-butylcresol such as 5-methylphenol. Among them, at least one kind selected from the group consisting of 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, 2,3,5-trimethylphenol and 2-t-butyl-5-methylphenol. Phenols are particularly preferred. Examples of the acid catalyst include organic acids (acetic acid, oxalic acid, p-toluenesulfonic acid, etc.), inorganic acids (hydrochloric acid, sulfuric acid, phosphoric acid, etc.), and divalent metal salts (zinc acetate, etc.). The preferable reaction molar ratio of the phenols represented by the general formula (Ia) and formaldehyde is 1: 0.2 to 1: 0.6. The reaction is preferably carried out in the presence of an organic solvent, and preferred organic solvents include, for example, alcohols (methanol, ethanol, etc.),
Examples thereof include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.) and ethers (ethyl cellosolve, ethyl cellosolve acetate, tetrahydrofuran, etc.). The reaction temperature is usually 50 to 160.
℃ (preferably 60 to 120 ℃), the reaction time is usually 2
30 hours. After completion of the reaction, the reaction mixture as it is may be further condensed with a phenol compound represented by the general formula (Ib) and formaldehyde, or by reacting from an unreacted substance, an acid catalyst and an organic solvent present in the reaction system. The product novolak or compound may be isolated using known means such as recrystallization. When obtaining novolac as the reaction product, the molar ratio of formaldehyde to phenols is preferably 0.6 times or less, while when obtaining the compound, it is also preferably 0.4 times or less. . When the weight average molecular weight of the reaction product novolac (excluding unreacted substances) is less than 200, the performance as a positive resist is deteriorated.
When it exceeds 0, the solubility of the alkali-soluble novolac resin obtained by condensation with the phenol compound represented by the general formula (Ib) and formaldehyde in the resist solvent decreases. Preferred compounds include, for example, di- (4
-Hydroxy-3,6-dimethylphenyl) -methane,
Di- (4-hydroxy-2,6-dimethylphenyl)-
Methane, di- (2-hydroxy-4,5-dimethylphenyl) -methane, di- (3-t-butyl-4-hydroxy-6-methylphenyl) -methane.

Examples of the phenol compound represented by the general formula (Ib) include o-cresol, m-cresol,
p-cresol, 4-t-butylphenol, 2-t-
Butylphenol, 3-t-butylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-
Methylresorcinol, 4-t-butylcatechol, 3
-Ethylphenol, 2-ethylphenol, 4-ethylphenol, 2,3,5-triethylphenol, and the xylenol, diethylphenol, trimethylphenol, and t-butylcresol described above. As the phenol compound represented by the general formula (Ib), one kind selected from the group consisting of m-cresol, p-cresol and a mixture thereof is particularly preferable. An organic solvent and an acid catalyst are preferably used in the condensation, and examples thereof include those used in the reaction between the phenols represented by the general formula (Ia) and formaldehyde. The reaction temperature and reaction time are the same as above. The preferable molar ratio of the phenols represented by the general formula (Ia) and the phenol compound represented by the general formula (Ib) is 1: 1 to 1: 6, and the preferable molar ratio of the total of the above phenols and phenol compounds and formaldehyde is Is from 1: 0.6 to 1: 1.5.

The alkali-soluble novolac resin obtained by condensation is subjected to an operation such as fractionation to give a GPC pattern area ratio (detector U in the range of 900 or less of the molecular weight of the resin).
V254 nm) is 25% or less (in terms of polystyrene) of the total pattern area excluding the pattern area of the unreacted phenol compound, and more preferably 20% or less. For fractionation, for example, a method of dissolving an alkali-soluble novolac resin obtained by condensation in an organic solvent used in the above reaction and then pouring the obtained solution into water to precipitate the solution or n-pentane, n-hexane or It is carried out by a method such as pouring into a solvent such as n-heptane for liquid separation.

Examples of the o-naphthoquinonediazide compound include compounds having two or more phenolic hydroxyl groups and 1,2-naphthoquinonediazide-4- (or -5).
-) Those obtained by reacting with a sulfonic acid halide in the presence of a weak alkali or an organic base.
The photosensitive resin composition of the present invention may contain an alkali-soluble polyhydric phenol having a molecular weight of less than 900, and examples of the polyhydric phenol include those described in JP-A-2-275955. Examples of the resist solvent include glycol esters such as propylene glycol monomethyl ether acetate, ethyl cellosolve acetate, and methyl cellosolve acetate, and JP-A-2-220056.
Examples thereof include solvents such as ethyl pyruvate, n-amyl acetate, ethyl lactate and the like, and ketones such as 2-heptanone and γ-butyrolactone, which are described in the publication.

The proportion of the o-naphthoquinonediazide compound and the alkali-soluble polyhydric phenol having a molecular weight of less than 900 is usually 10 to 50 in the total solid content of the photosensitive resin composition.
And 0 to 40 (preferably 3 to 40)% by weight. The ratio between the total solid content and the resist solvent is set appropriately.

[0017]

The photosensitive resin composition of the present invention has an excellent balance of various performances such as resolution, profile, heat resistance, sensitivity and depth of focus. Further, the production method of the present invention is a reaction product containing a novolak or a compound, which is a reaction product of a phenol represented by the general formula (Ia) and formaldehyde, as it is, and a phenol compound represented by the general formula (Ib). Since it is condensed with formaldehyde, the photosensitive resin composition can be produced industrially advantageously.

[0018]

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

Reference Example 1 2,5-xylenol 91.6 g, methyl isobutyl ketone 264.6 g, oxalic acid 13.4 g and 90% acetic acid 6
24.5 g of 37% formalin was added dropwise to the mixture of 3.8 at 80 ° C. over 30 minutes. After the dropping was completed, the reaction was performed at 100 ° C. for 6 hours. As a result of sampling and analyzing a part of the reaction mixture, the weight average molecular weight of the reaction product, novolak, was 330. M in the resulting reaction mixture
-Cresol is 162.2 g, p-cresol 40.6
g was added. Then, it takes 37 minutes at 100 ° C.
% Formalin 128.5 g was added dropwise. Furthermore, the reaction was carried out at the same temperature for 15 hours. Then, after washing with water, it was dehydrated by azeotropic distillation. When the obtained methyl isobutyl ketone solution of the alkali-soluble novolac resin was analyzed by GPC, the weight average molecular weight was 4350 (in terms of polystyrene).

Reference Example 2 2,5-xylenol 91.6 g, methyl isobutyl ketone 264.6 g, oxalic acid 13.4 g and 90% acetic acid 6
24.5 g of 37% formalin was added dropwise to the mixture of 3.8 at 80 ° C. over 30 minutes. After the dropping was completed, the reaction was performed at 100 ° C. for 6 hours. As a result of sampling and analyzing a part of the reaction mixture, the weight average molecular weight of the reaction product, novolak, was 330. M in the resulting reaction mixture
-Cresol is 162.2 g, p-cresol 40.6
g was added. Then, it takes 37 minutes at 100 ° C.
% Formalin 147.4 g was added dropwise. Furthermore, the reaction was carried out at the same temperature for 15 hours. Then, after washing with water, it was dehydrated by azeotropic distillation. When the methyl isobutyl ketone solution of the obtained alkali-soluble novolac resin was analyzed by GPC, the weight average molecular weight was 4400 (polystyrene conversion).

Reference Example 3 492.8 g of 2-t-butyl-5-methylphenol,
492.8 g of methanol and p-toluenesulfonic acid 2
60.1 g of 37% formalin was added dropwise to the mixture of 8.5 g at 60 ° C. over 30 minutes. After the dropping was completed, the reaction was carried out at 80 ° C. for 6 hours. The reaction mixture was concentrated, the residue was dissolved in ethyl acetate, the resulting solution was washed with water, and then dehydrated by azeotropic distillation. Pour the ethyl acetate solution into 1 liter of n-hexane,
The precipitate was filtered. Then, after drying at 65 ° C. for 24 hours, 24.9 g of a crystalline compound was obtained. The molecular weight of this compound by FD-MS was 328.

Reference Example 4 9.0 g of the compound obtained in Reference Example 3 and m-cresol 23
To a mixture of 7.9 g, p-cresol 237.9 g, methyl isobutyl ketone 252.3 g, oxalic acid 5.8 g and 90% acetic acid 80.9 g, 37% formalin 116 g was added dropwise at 80 ° C. over 60 minutes, and after the addition was completed. And reacted at 93 ° C. for 15 hours. Then, after washing with water, it was dehydrated by azeotropic distillation. When the methyl isobutyl ketone solution of the obtained alkali-soluble novolak resin was analyzed by GPC, the weight average molecular weight was 4680 (polystyrene conversion).

Reference Example 5 A mixture of 300 g of the alkali-soluble novolac resin solution (resin content 40% by weight) obtained in Reference Example 1, 554 g of methyl isobutyl ketone and 692 g of n-heptane was stirred at 60 ° C. for 30 minutes and then separated. 2-heptanone 300 in the lower layer
After the addition of g, n-heptane and methyl isobutyl ketone, which are the solvents at the time of fractionation, were removed by distillation to obtain a 2-heptanone solution of novolak resin. By GPC analysis, the weight average molecular weight was 8000, and the pattern area in the range of molecular weight of 900 or less was 17% with respect to the total pattern area (excluding the pattern area of the unreacted phenol compound).

Reference Example 6 A mixture of 220 g of the alkali-soluble novolac resin solution (resin content 45% by weight) obtained in Reference Example 2, 531 g of methyl isobutyl ketone and 607 g of n-heptane was stirred at 60 ° C. for 30 minutes and then separated. 2-heptanone 240 in the lower layer
After the addition of g, n-heptane and methyl isobutyl ketone, which are the solvents at the time of fractionation, were removed by distillation to obtain a 2-heptanone solution of novolak resin. By GPC analysis, the weight average molecular weight was 8300, and the pattern area in the range of the molecular weight of 900 or less was 18% with respect to the total pattern area (excluding the pattern area of the unreacted phenol compound).

Reference Example 7 A mixture of 240 g of the alkali-soluble novolac resin solution (resin content 39% by weight) obtained in Reference Example 4, 476 g of methyl isobutyl ketone and 572 g of n-heptane was stirred at 60 ° C. for 30 minutes and then separated. 2-heptanone 150 in the lower layer
After the addition of g, n-heptane and methyl isobutyl ketone, which are the solvents at the time of fractionation, were removed by distillation to obtain a 2-heptanone solution of novolak resin. By GPC analysis, the weight average molecular weight was 8500, and the pattern area in the range of the molecular weight of 900 or less was 16% with respect to the entire pattern area (excluding the pattern area of the unreacted phenol compound).

Reference Example 8 153 g of 37% formalin over 60 minutes at 80 ° C. in a mixture of 164 g of m-cresol, 164 g of p-cresol, 264.6 g of methyl isobutyl ketone, 13.4 g of oxalic acid and 63.8 g of 90% acetic acid. Was dripped. After the dropping was completed, the reaction was carried out at 100 ° C. for 15 hours. The reaction mixture was washed with water and then dehydrated by azeotropic distillation. When the methyl isobutyl ketone solution of the obtained novolak resin was analyzed by GPC, the weight average molecular weight was 4520 (polystyrene conversion).

Reference Example 9 200 g of the novolac resin solution obtained in Reference Example 8 (resin content 40% by weight), 410 g of methyl isobutyl ketone and n
After stirring a mixture of 488 g of heptane for 30 minutes at 60 ° C.,
The layers were separated. After adding 180 g of 2-heptanone to the lower layer, n-heptane and methyl isobutyl ketone, which are solvents for fractionation, were removed by distillation to obtain a 2-heptanone solution of novolak resin. According to GPC analysis, the weight average molecular weight is
It was 8900, and the pattern area in the range of molecular weight of 900 or less was 16% with respect to the entire pattern area (excluding the pattern area of the unreacted phenol compound).

Example (Example Nos. 1 and 2) and Comparative Example (Example No. 3) A novolak resin having the composition shown in the table below, an o-quinonediazide compound (photosensitizer) and an additive were mixed with 50 parts of 2-heptanone, A resist solution was prepared by filtering with a 0.2 μm Teflon filter. This was applied onto a silicon wafer that had been washed by a conventional method to a thickness of 1.1 μm using a spin coater. Then, the silicon wafer was baked on a hot plate at 90 ° C. for 1 minute. After that, a reduction projection exposure apparatus (Nikon NSR1755i 7ANA = 0.5) was used to perform exposure by changing the exposure amount stepwise. Then, it was baked on a hot plate at 110 ° C. for 1 minute. This was developed for 1 minute using an alkaline developer SOPD (manufactured by Sumitomo Chemical Co., Ltd.) to obtain a positive pattern. Then, a 0.4 μm line-and-space (L / S) cross section is observed with a SEM (scanning electron microscope), and the sensitivity (effective sensitivity) is calculated from the exposure amount at which the line-and-space in best focus becomes 1: 1. A profile is obtained from the L / S cross-sectional shape of 0.45 μm at the exposure dose, and the profile is 0.4 at the exposure dose.
The depth of focus was determined from the width of the focal point at which the line and space of μm separates without film thinning, and the resolution from the width of the minimum line and space at which the film was separated without film thinning at the exposure dose. For scum, the presence or absence of development residue in the space portion of the 0.45 L / S pattern at the effective sensitivity was observed. In addition, a silicon wafer with a resist pattern after development is
It was heated on a hot plate at 24 ° C. for 5 minutes, and the degree of dripping of the resist pattern was evaluated in 5 levels. (The larger the number, the better the heat resistance.) The results are shown in the table below.

[0029]

[Table 1]

[0030]

[Table 2]

In the above table, additive B is a compound of the following formula.

[0032]

[Chemical 7]

In the above table, the photosensitizers C and D are reaction products of each of the compounds (C ') and (D') of the following formulas with 1,2-naphthoquinonediazide-5-sulfonic acid chloride.

[0034]

[Chemical 8]

Claims (5)

[Claims] 1. A compound represented by the general formula (Ia): (In the formula, R _{1 to} R ₃ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) and a reaction obtained by reacting formaldehyde with formaldehyde in the presence of an acid catalyst. Novolak having a weight average molecular weight of 200 to 900 or a molecular weight of 200 to 9 which is a product
00 and a compound of the general formula (Ib) (In the formula, R _{4 to} R ₆ each independently represents a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 6 carbon atoms) and a formaldehyde and 3 are condensed, Moreover, an alkali-soluble novolac resin, a resist solvent and an o-naphthoquinonediazide compound having a GPC pattern area ratio in the range of molecular weight of 900 or less to 25% or less (in terms of polystyrene) of the total pattern area excluding the pattern area of unreacted phenol compound A photosensitive resin composition comprising: 2. The composition according to claim 1, wherein the phenol compound represented by the general formula (Ib) is one selected from the group consisting of m-cresol, p-cresol and a mixture thereof. 3. A phenol represented by the general formula (Ia) is 2,5-xylenol, 3,5-xylenol, 3,4.
-The composition according to claim 1 or 2, which is at least one selected from the group consisting of xylenol, 2,3,5-trimethylphenol and 2-t-butyl-5-methylphenol. 4. The composition according to claim 1, which contains an alkali-soluble polyhydric phenol having a molecular weight of less than 900. 5. A reaction mixture obtained by reacting a phenol represented by the general formula (Ia) according to claim 1 with formaldehyde in the presence of an acid catalyst, further comprising the general formula (1) according to claim 1. A method for producing a photosensitive resin composition, which comprises mixing an alkali-soluble novolac resin obtained by condensation with a phenol compound represented by Ib) and formaldehyde, a resist solvent, and an o-naphthoquinonediazide compound.