JP2000319346A - Production of phenolic resin for photoresist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phenolic resin for photoresist, excellent in resolution and having both highly thermal resistance and high sensitivity. SOLUTION: This method for producing a novolak-type phenolic resin for photoresist is featured that the novolak-type phenolic resin is obtained by reacting phenols (P1) having three or more functionalities with aldehydes (A) in the presence of a basic catalyst at pH 7-12 as a primary reaction to obtain a resol resin and by reacting the resol resin with added phenols (P2) in the presence of an added acid catalyst in an adjusted state at pH 1-6 as a secondary reaction, and has a weight average molecular weight of 100-5,000 when the primary reaction ended and a weight average molecular weight of 1,500-20,000 when the secondary reaction ended respectively in terms of polystyrene measured with GPC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a base resin for a photoresist used for lithography in manufacturing semiconductors and LCDs, and has a high heat resistance, a high residual film ratio, a high sensitivity and a high resolution. The present invention relates to a method for producing a novolak type phenol resin for a photoresist, which enables the production of a resist.

[0002]

2. Description of the Related Art In general, a positive photoresist uses a photosensitive agent having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolak-type phenol resin). Positive photoresists having such a composition exhibit high resolution by exposure to an alkaline solution after exposure, and are used in the manufacture of semiconductors such as ICs and LSIs and the manufacture of circuit substrates such as LCDs. In addition, novolak type phenolic resins also have high heat resistance to plasma dry etching due to the structure with many aromatic rings, and many positive type phenolic resins containing novolak type phenolic resins and naphthoquinonediazide-based photosensitizers have been used. Photoresists have been developed and put into practical use, and have achieved great results.

In general, a positive photoresist is a novolak phenol resin obtained by reacting a mixture of meta-cresol and para-cresol with formaldehyde in the presence of an acid catalyst. In order to adjust or improve the characteristics of the photoresist, the ratio, the molecular weight, the molecular weight distribution, and the like of the meta-cresol-para-cresol mixture in the phenol resin have been studied.

However, in recent years, with higher integration of LSIs, it has become necessary to form finer patterns with higher precision. Therefore, there is an increasing demand for photoresists to improve various characteristics. In the field of photoresists for semiconductors, characteristics such as high heat resistance, high resolution, and high sensitivity are required. For higher heat resistance, monomers such as alkylphenols such as xylenol and trimethylphenol and aromatic aldehydes are being studied. There is an example in which hydroxybenzaldehyde and the like have been studied for higher sensitivity. However, in each case, although some improvement was observed, no dramatic effect was obtained. From the viewpoint of controlling the molecular structure, there is an example in which a high-ortho resin containing a large number of structures in which the bonding groups of a phenol resin are bonded by ortho-ortho on an aromatic ring has been applied for higher resolution. When such a resin is used, high resolution can be achieved, but disadvantages such as a decrease in heat resistance and a decrease in sensitivity occur, and the resin has not been put to practical use.

[0005] As a method for improving the reaction formula, Japanese Patent Laid-Open No.
No. 29950 describes an example of a photoresist novolak resin using a resole resin as a raw material. However, the novolak reaction is carried out using a bifunctional monomer, resole, paracresol, which is not suitable for practical use because of poor heat resistance and low resolution and sensitivity.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a phenolic resin for a photoresist, which enables the production of a photoresist having excellent resolution, high heat resistance and high sensitivity. . The present inventors have found that, in a photoresist, the molecular structure of a phenol resin serving as a base resin is preferably a high-density three-dimensional molecular structure in order to improve the heat resistance of the photoresist, and to improve the resolution and sensitivity. It was considered that the binding of a monomer having a high interaction with the photosensitizer to the terminal portion is a good molecular structure because the photosensitizer bonded to the resin effectively exerts a dissolution inhibiting effect during development after exposure. Therefore, the present invention has been obtained as a result of intensive studies for achieving such a molecular structure.

[0007]

Means for Solving the Problems The present invention is obtained by reacting a phenol (P1) and an aldehyde (A) having a functionality of 3 or more at a pH of 7 to 12 (primary reaction) in the presence of a basic catalyst. A novolak-type phenol resin obtained by adding a phenol (P2) and an acid catalyst to a resole resin to adjust the pH to 1 to 6, and further performing a reaction (secondary reaction).
The weight average molecular weight in terms of polystyrene by PC measurement is
A method for producing a novolak-type phenolic resin for a photoresist, wherein the end of the primary reaction is from 100 to 5000 and the end of the secondary reaction is from 1500 to 20,000.

Hereinafter, the present invention will be described in detail.
First, the raw materials will be described. The trifunctional phenols (P1) include phenol, metacresol, 3,5
-Xylenol, metaethylphenol, catechol,
Examples include resorcinol, metachlorophenol, and metaphenylphenol, and are not particularly limited as long as they are phenols having three or more reaction points capable of reacting with aldehydes, and may be used alone or in combination. Can be. Practically particularly preferred trifunctional phenols (P1) include meta-cresol and phenol.

The aldehydes (A) include formaldehyde (formalin), paraformaldehyde, acetaldehyde, propylaldehyde, butyraldehyde,
Alkyl aldehydes such as isobutyraldehyde, isovaleraldehyde, hexyl aldehyde, octyl aldehyde, unsaturated alkyl aldehydes such as acrolein and crotonaldehyde, hydroxybenzaldehydes such as salicylaldehyde and parahydroxybenzaldehyde, and aromatics such as benzaldehyde and phthalaldehyde Examples thereof include dialdehydes such as aldehydes, glyoxal, and glutaraldehyde, but are not limited thereto, and may be used alone or as a mixture. Aldehydes that are particularly effective in practical use include formaldehyde (formalin) and paraformaldehyde.

The phenols (P2) used in the novolak reaction (secondary reaction) include phenol, orthocresol, metacresol, paracresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol , 2,6-xylenol, 3,4-xylenol,
3,5-xylenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, ethylphenol, propylphenol, butylphenol, phenylphenol, halogenated phenol and the like are used, and aldehydes and resole type There is no particular limitation on phenols having one or more reaction points that react with the methylol group of the phenolic resin, and they may be used alone or in combination of two or more. Phenols (P2) particularly preferred for practical use include paracresol, xylenols, and trimethylphenols.

The molar ratio (A / P1) of the aldehyde (A) and the phenol (P1) in the primary reaction is 0.5 to
3.0, particularly preferably 0.7 to 2.5.
When the amount of the aldehyde (A) is less than 0.5, the density of the molecule formed after the primary reaction decreases, and the heat resistance decreases. On the other hand, if it is more than 3.0, the amount of free aldehyde after the primary reaction is large, so that it is difficult to control the secondary reaction, and in some cases, it gels. The molar ratio (A / P1 + P2) of the aldehyde (A) and the phenol (P1 + P2) in the secondary reaction is 0.1.
It is 2 to 1.5, especially preferably 0.5 to 1.2. When the aldehyde (A) is O.D. If it is less than 2, the molecular weight is too small and the heat resistance decreases. If it is more than 1.5, gelation occurs during the secondary reaction, which may hinder production.

The molar ratio between P1 and P2 (P1 / P2) is
0.2 to 3.0, particularly preferably 0.5 to 2.5
It is. When P1 is more than 3.0, although there are many molecular terminals (methylol groups) after the primary reaction, P2 reacting with the terminal is insufficient, and the molecular terminal reacts with another molecular terminal and is crushed, and P2 is crushed. Effectively loses interaction with the photosensitizer, causing a decrease in sensitivity. Also,
If P1 is less than 0.5, the molecular weight after the secondary reaction will be small, and the heat resistance will be reduced.

The basic catalyst used in the primary reaction includes tertiary amines such as trimethylamine, triethylamine and tributylamine; aromatic amines such as pyridine, dimethylaminopyridine and pyrrolidinopyridine; diazabicyclononene (DBN); Zabicycloundecene (DB
Although alicyclic amines such as U) can be used,
There is no particular limitation, and it can be used as long as it has sufficient basicity to carry out the resolving reaction. Particularly effective ones in production are tertiary amines, and practically, triethylamine and tributylamine are most preferable. The amount used is not particularly limited, but the pH in the system
Should be about 7 to 12. Practically, it is preferably 5 to 20% by weight with respect to the phenol, and 5% by weight.
When the amount is less than the above, the progress of the reaction is slow, which is inappropriate from an economic viewpoint. When the amount is more than 20% by weight, the reaction is too fast to control, and the basic catalyst is difficult to obtain from the finally obtained resin. Is difficult to remove, which can adversely affect the properties of the photoresist.

Examples of the acidic catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and boric acid, and organic acids such as oxalic acid, acetic acid, benzoic acid and p-toluenesulfonic acid. Can be used.
Preferably, a salt which is soluble in washing water by neutralization with a basic catalyst and which can be easily removed from the reaction system by decomposition, sublimation, etc. when removing the monomer is preferable. Although the amount used depends on the type of the catalyst, it is preferable to set the amount so that the basic catalyst is neutralized and the pH in the reaction system is in the range of 1 to 6.

Next, the weight average molecular weight in the present invention will be described. The weight average molecular weight is a value calculated by gel permeation chromatography (GPC) based on a calibration curve prepared using a polystyrene standard substance. GPC measurement uses tetrahydrofuran as an elution solvent, a flow rate of 1.0 ml / min, and a column temperature of 40.
The test was performed under the condition of ° C. The device is the main body: HL made by TOSOH
C-8020, detector: T set at a wavelength of 280 nm
OSOH UV-8011, Analytical column: Showa Denko SHOdex; KF-802 one, KF-803 1
And KF-8051 were used.

The weight average molecular weight of the phenolic resin in the present invention is 100 to 5,000 at the end of the primary reaction, and is particularly preferably 300 to 4,000. If it is less than 100, the molecular weight of the phenol resin finally obtained is too small, and heat resistance is impaired. If it exceeds 5,000, the viscosity in the reaction system is too high, which causes problems such as inability to stir uniformly. When the secondary reaction is completed, 150
0 to 20000, particularly preferably 2000 to 1800
0. If it is smaller than 1500, the heat resistance is insufficient, and in some cases, the photoresist may not be applied uniformly. If it exceeds 20,000, the heat resistance is good, but the sensitivity is lowered, which is not practical.

Further, the present invention will be described along the reaction (production) procedure. In the reaction, a phenol (P1), an aldehyde (A), and a basic catalyst are charged into a reaction vessel equipped with a stirrer, a thermometer, and a heat exchanger to start a primary reaction.
The reaction temperature and time can be appropriately set depending on the reactivity of the monomer and the desired characteristics. However, the reaction time is 0.5 to 8 hours and the reaction temperature is 4
0-100 ° C is preferred. After completion of the reaction, a phenol (P2) and an acidic catalyst are added, and a secondary reaction is performed. The reaction temperature and time of the secondary reaction can be appropriately selected depending on the characteristics of the phenol resin to be produced and the reactivity of the monomer.
Time and reaction temperature are preferably 50 to 150 ° C. At the time of the primary reaction or the secondary reaction, a reaction solvent can be added and used if necessary. Although the type of the solvent is not limited, any solvent can be used as long as it dissolves the phenol resin. Examples include ketones such as methyl ethyl ketone and methyl isobutyl ketone, alcohols such as butanol, and ether alcohols such as ethoxyethanol.

After completion of the reaction, it is preferable to add water and wash with water in order to remove the acid and base catalyst added for the reaction. Although the amount and the number of times of the washing water are not particularly limited, the number of times of the washing is preferably about 1 to 5 times from the viewpoint of the amount of the residual catalyst and the economy. The washing temperature is not particularly limited, but is preferably 40 to 95 from the viewpoint of the efficiency of removing the catalyst species and the workability.
C. is preferably performed at a temperature of. During the washing, if the separation of the resin and the washing water is poor, it is effective to add a solvent for lowering the resin viscosity or raise the washing temperature. The type of solvent is not particularly limited, but any solvent can be used as long as it dissolves the phenolic resin and lowers the viscosity. Examples include ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, alcohols such as methanol, ethanol and butanol, and ether alcohols such as ethoxyethanol.

After washing, dehydration and demonomerization are performed under normal pressure and reduced pressure to obtain a phenol resin for a photoresist. The conditions for dehydration and demonomerization are not limited. However, considering the stability (variability) and viscosity of the obtained phenolic resin, the degree of decompression is 0.1 to 200 torr.
It is particularly preferable to carry out the reaction at a temperature of about 150 to 250 ° C.

Finally, it is one of the important required characteristics that the phenolic resin for the photoresist contains as little metal impurities as possible. In the production according to the present invention, the phenolic resin is made of glass lining and / or tantalum, hafnium, zirconium. It is preferable to use a manufacturing apparatus using a metal material made of a metal selected from niobium, niobium and titanium and / or an alloy thereof and containing substantially no other material as a reaction facility material.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.
All “parts” and “%” described herein indicate “parts by weight” and “% by weight”, and the present invention is not limited by these examples.

Example 1 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
1) 810 g, 851 g of 37% formalin (A) (molar ratio: A / P1 = 1.4) and 40 g of triethylamine
And reacted at pH 8.5 and a reaction temperature of 78 to 82 ° C. for 75 minutes. Thereafter, 220 g of 10% aqueous oxalic acid was added to neutralize (pH = 6.0), and 1620 g of paracresol (P2) (molar ratio: A / P1 + P2 = 0.4)
7, P1 / P2 = 0.5) and 41 g of oxalic acid.
The reaction was carried out at H1.5 at a reaction temperature of 98 to 102 ° C for 4 hours. After completion of the reaction, the mixture is cooled to 70 ° C. and acetone 350
g, and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, acetone 350 g,
The water washing operation was performed again using 1250 g of ion-exchanged water. Thereafter, dehydration is performed under normal pressure to an internal temperature of 140 ° C., and further dehydration and demonomerization is performed to 195 ° C. under a reduced pressure of 60 torr.
I got The weight average molecular weight of the reaction product after the primary reaction is 100
At 0, the weight average molecular weight of the obtained resin was 4,800, and the free monomer was 1.0%.

Example 2 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
1) 810 g, 92% paraformaldehyde (A) 5
63 g (molar ratio: A / P1 = 2.3) and 40 g of triethylamine were charged, the pH was 8.5, and the reaction temperature was 78 to 82.
The reaction was performed at 60 ° C. for 60 minutes. Then, 10% oxalic acid water 2
20 g was added for neutralization (pH = 6.2), and 450 g of paracresol (P2) (molar ratio: A / P1 + P2)
= 1.48, P1 / P2 = 1.8) and 41 g of oxalic acid were added and reacted at pH 2.5 at a reaction temperature of 98 to 102 ° C for 4 hours. After completion of the reaction, the mixture was cooled to 70 ° C. and acetone 3
50 g and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, acetone 350
g, and 1250 g of ion-exchanged water, the washing operation was performed again. After that, dehydrate to an internal temperature of 140 ° C under normal pressure,
Further, under reduced pressure of 60 torr, dehydration and demonomerization were performed to 195 ° C.
0 g was obtained. The weight average molecular weight of the reaction product after the primary reaction is 3
500, the weight average molecular weight of the obtained resin was 1800
0, free monomer was 1.5%.

Example 3 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
1) 810 g, 486 g of 37% formalin (A) (molar ratio: A / P1 = 0.8) and 50% of tributyllamine
g, pH 9.0, reaction temperature 78-82 ° C and 75
The reaction was performed for minutes. Thereafter, 240 g of 10% aqueous oxalic acid was added for neutralization (pH = 6.4), and 305 g of 2,3-xylenol (P2) and 2,4-xylenol (P
2) 305 g (molar ratio: A / P1 + P2 = 0.48, P
1 / P2 = 1.5) and 41 g of oxalic acid.
2. The reaction was performed at a reaction temperature of 98 to 102 ° C. for 4 hours. After the completion of the reaction, the mixture was cooled to 70 ° C., 350 g of acetone and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, a water washing operation was performed again using 350 g of acetone and 1250 g of ion-exchanged water. After that, it was dehydrated under normal pressure to an internal temperature of 140 ° C, and further 60t
Dehydration and demonomerization were performed at 195 ° C. under reduced pressure of orr to obtain 1300 g of a phenol resin for a photoresist. The weight average molecular weight of the reaction product after the primary reaction is 500,
The weight average molecular weight of the obtained resin was 2500 and the free monomer was 2.5%.

Example 4 800 g of 3,5-xylenol (P1) and 957 g of 37% formalin (A) were placed in a 5 L four-necked flask having a stirrer, thermometer and heat exchanger.
(Molar ratio: A / P1 = 1.8) and triethylamine 3
5 g, pH 7.5, reaction temperature 78-82 ° C.
The reaction was performed for 5 minutes. Thereafter, 200 g of 10% oxalic acid water
For neutralization (pH = 6.5), and 1012 g of paracresol (molar ratio: A / P1 + P2 = 0.74)
(P1 / P2 = 0.7) and 35 g of oxalic acid were added to adjust the pH.
The reaction was carried out at 3.0 at a reaction temperature of 98 to 102 ° C. for 4 hours.
After the completion of the reaction, the mixture was cooled to 70 ° C., 350 g of acetone and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, a water washing operation was performed again using 350 g of acetone and 1250 g of ion-exchanged water.
After that, dehydrate to 140 ° C under normal pressure and further 60
Dehydration and demonomerization were performed at 195 ° C. under a reduced pressure of torr to obtain 1500 g of a phenol resin for a photoresist. The weight average molecular weight of the reaction product after the primary reaction is 2500
The weight average molecular weight of the obtained resin was 9,000 and the free monomer was 2.0%.

Example 5 Phenol (P1) 7 was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
00 g, 1268 g of 37% formalin (A) (molar ratio: A / P1 = 2.1) and 50 g of triethylamine were charged and reacted at pH 10.0 at a reaction temperature of 78 to 82 ° C. for 45 minutes. Thereafter, 260 g of 10% aqueous oxalic acid was added for neutralization (pH = 6.0), and 350 g of paracresol (molar ratio: A / P1 + P2 = 1.46, P1 /
P2 = 2.3), 40 g of trifluoroacetic acid was added and p
The reaction was conducted at H1.8 at a reaction temperature of 98 to 102 ° C for 4 hours. After completion of the reaction, the mixture is cooled to 70 ° C. and acetone 350
g, and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, acetone 350 g,
The water washing operation was performed again using 1250 g of ion-exchanged water. Thereafter, dehydration is performed under normal pressure to an internal temperature of 140 ° C., and further dehydration and demonomerization is performed to 195 ° C. under a reduced pressure of 60 torr, and phenol resin for photoresist is 1000 g.
I got The weight average molecular weight of the reaction product after the primary reaction is 280
At 0, the weight average molecular weight of the obtained resin was 8,500 and the free monomer was 1.0%.

Example 6 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
1) 810 g, 912 g of 37% formalin (A) (molar ratio: A / P1 = 1.5) and 45 g of triethylamine
And reacted at pH 9.0 and a reaction temperature of 78 to 82 ° C. for 75 minutes. Thereafter, 240 g of 10% oxalic acid aqueous solution was added to neutralize (pH = 6.3), and 1020 g of 2,3,5-trimethylphenol (molar ratio: A / P1 + P
2 = 0.75, P1 / P2 = 1.0) and 41 g of oxalic acid were added and reacted at pH 1.8 at a reaction temperature of 98 to 102 ° C. for 4 hours. After completion of the reaction, the mixture was cooled to 70 ° C. and acetone 3
50 g and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, acetone 350
g, and 1250 g of ion-exchanged water, the washing operation was performed again. After that, dehydrate to an internal temperature of 140 ° C under normal pressure,
Further, dehydration and demonomerization were performed to 195 ° C. under a reduced pressure of 60 torr.
0 g was obtained. The weight average molecular weight of the reaction product after the primary reaction is 2
And the weight average molecular weight of the obtained resin was 1200.
0, free monomer was 3.5%.

Example 7 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer, and a heat exchanger.
1) 810 g, 1216 g of 37% formalin (A)
(Molar ratio: A / P1 = 2.0) and triethylamine 5
After charging 0 g, the reaction was carried out at a pH of 10.5 and a reaction temperature of 78 to 82 ° C. for 45 minutes. Then, 10% oxalic acid water 260
g and neutralized (pH = 6.6), and 2,6-
763 g of xylenol (molar ratio: A / P1 + P2 = 1.
09, P1 / P2 = 1.2), 40 g of oxalic acid was added and p
The reaction was carried out at H1.5 at a reaction temperature of 98 to 102 ° C for 4 hours. After completion of the reaction, the mixture is cooled to 70 ° C. and acetone 350
g, and 1250 g of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. After removing the separated water, acetone 350 g,
The water washing operation was performed again using 1250 g of ion-exchanged water. Thereafter, dehydration is performed at an internal temperature of 140 ° C. under normal pressure, and dehydration and demonomerization is performed at 195 ° C. under a reduced pressure of 60 torr.
I got The weight average molecular weight of the reaction product after the primary reaction is 260
At 0, the resulting resin had a weight average molecular weight of 15,000 and free monomer of 1.5%.

Example 8 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
1) 810 g, 730 g of 37% formalin (A) (molar ratio: A / P1 = 1.2) and 40 g of triethylamine
And reacted at pH 8.5 and a reaction temperature of 78 to 82 ° C. for 60 minutes. Thereafter, 240 g of 10% oxalic acid water was added to neutralize (pH = 6.2), and 1,275 g of 2,3,6-trimethylphenol (molar ratio: A / P1 + P
2 = 0.53, P1 / P2 = 0.8) and 15 g of oxalic acid, and the mixture was reacted at pH 4.0 and a reaction temperature of 98 to 102 ° C. for 4 hours. After the completion of the reaction, the mixture was cooled to 70 ° C, and 350 g of acetone and 1250 g of ion-exchanged water were added.
And left to stir. After removing the separated water, acetone 35
The water washing operation was performed again using 0 g and 1250 g of ion-exchanged water. After that, dehydrate to 140 ° C under normal pressure and further to 195 ° C under reduced pressure of 60 torr.
Phenol resin 1 for photoresist after demonomerization
300 g were obtained. The weight average molecular weight of the reaction product after the primary reaction is 1500, and the weight average molecular weight of the obtained resin is 600.
0, free monomer was 2.5%.

Example 9 Metacresol (P) was placed in a 5 L four-necked flask having a stirrer, a thermometer and a heat exchanger.
1) 700 g, 420 g of 37% formalin (A) (molar ratio: A / P1 = 0.8) and 45 g of triethylamine
And reacted at pH 9.0 and a reaction temperature of 78 to 82 ° C. for 80 minutes. Thereafter, 240 g of 10% aqueous oxalic acid was added for neutralization (pH = 6.4), and 1977 g of 3,4-xylenol (molar ratio: A / P1 + P2 = 0.2).
3, P1 / P2 = 0.4) and 45 g of trichloroacetic acid were added, and the mixture was reacted at pH 1.3 and a reaction temperature of 98 to 102 ° C for 4 hours. After the completion of the reaction, the mixture was cooled to 70 ° C, and 350 g of acetone and 1250 g of ion-exchanged water were added.
And left to stir. After removing the separated water, acetone 35
The water washing operation was performed again using 0 g and 1250 g of ion-exchanged water. After that, dehydrate to 140 ° C under normal pressure and further to 195 ° C under reduced pressure of 60 torr.
Phenol resin 1 for photoresist after demonomerization
300 g were obtained. The weight average molecular weight of the reaction product after the primary reaction is 2000, and the weight average molecular weight of the obtained resin is 700.
0, free monomer was 2.0%.

Comparative Example 1 400 g of meta-cresol (P) and para-cresol (P) were placed in the same reactor as in Example 1.
600 g, 412.9 g of 37% formalin (A) (molar ratio: A / P = 0.55) and 2 g of oxalic acid were charged, and 98-
After a reflux reaction at 102 ° C. for 4 hours, dehydration was performed under normal pressure to raise the internal temperature to 140 ° C., and then dehydration and demonomerization were performed at an internal temperature of 195 ° C. under a reduced pressure of 80 Torr.
A phenolic resin for a photoresist was obtained. The weight average molecular weight of the obtained resin was 2,200 and the free monomer was 3.3%.

Comparative Example 2 400 parts of meta-cresol (P) and para-cresol (P) were placed in the same reactor as in Example 1.
96 parts, 563.1 parts of 37% formalin (A) (molar ratio: A / P = 0.75) and 7 parts of oxalic acid were charged, and 96 to
After performing a reflux reaction at 100 ° C. for 5 hours, dehydration is performed under normal pressure, the internal temperature is raised to 150 ° C., and then 80 Torr
The mixture was dehydrated and demonomerized to an internal temperature of 195 ° C. under reduced pressure to obtain a phenol resin for a photoresist. The obtained resin has a weight average molecular weight of 9300 and a free monomer of 2.6.
%Met.

Evaluation Example 1: Evaluation method of heat resistance 100 parts of novolak type phenol resin and naphthoquinone-
30 parts of 2,3,4-trihydroxybenzophenone ester of 1,2-diazide-5-sulfonic acid was dissolved in ethyl lactate to prepare a resist solution. These are 0.2
The solution was filtered through a micron membrane filter to obtain a resist solution. This was applied by information and dried on a hot plate at 110 ° C. for 90 seconds. Thereafter, exposure was performed through a test chart mask using a reduction projection exposure apparatus, and development was performed for 50 seconds using a developing solution (2.38% aqueous solution of tetramethylammonium hydroxide). The obtained silicon wafer was left for 30 minutes on a hot plate where the temperature was changed, and the change in the shape of the resist pattern on the silicon wafer was observed with an electron microscope to evaluate the heat resistance.

Evaluation Example 2: Evaluation method of critical resolution and depth of focus In the same manner as in Evaluation Example 1, solution preparation, pretreatment, coating, exposure and development using a test chart mask were performed, and the resist pattern shape was observed with an electron microscope. Depth of focus is 0.30μ
A photograph when the focus was changed at a line width of m was visually observed, and a resolvable focus fluctuation width was measured. The limit resolution was determined and measured by visually observing the limit that could be resolved from a photograph under optimal exposure and development conditions.

Evaluation Example 3: Evaluation method of alkali dissolution time (ADR) Using a 25% resin-ethyl cellosolve acetate solution, a silicon coater was applied to a silicon wafer by a spin coater so as to have a thickness of about 1 micrometer. 90 at 110 ° C
Dry on a hot plate for 2 seconds. Thereafter, the resin applied to the silicon wafer is dissolved with a developing solution (2.38% aqueous solution of tetramethylammonium hydroxide),
The dissolution time was measured visually.

Table 1 Type Weight average molecular weight ADR Depth of focus Limit resolution Heat resistance Mw sec / μm μm μm ° C. Example 1 4800 18 1.2 0.228 160 Example 2 18000 60 1.0 0.30 165 Example 3 2500 4 1.4 0.25 150 Example 4 9000 25 1.4 0.28 160 Example 5 8500 24 1.2 0.226 160 Example 6 12000 45 1.0 0.30 160 Example 7 15000 55 1.0 0.30 165 Example 8 6000 20 1.2 0.228 160 Example 9 7000 21 1.4 0.25 160 Comparative Example 1 2200 3 0.7 0.40 140 Comparative Example 2 9300 30 0 .6 0.35 145

[0037]

According to the present invention, it is possible to provide a phenolic resin for a photoresist which has excellent resolution which cannot be obtained by the conventional method and which has both high heat resistance and high sensitivity.
The photoresist obtained by using the phenolic resin of the present invention is used for lithography when manufacturing a highly integrated semiconductor, and is expected to be useful for further increasing the integration of semiconductors in the future.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA01 AA02 AA10 AB16 AB17 AC01 AD03 BE01 BJ10 CB28 CB55 EA10 FA01 FA03 FA17 4J033 CA02 CA03 CA11 CA12 CA29 CB01 CB04 CB25 CC07 CC09 CC14 HA12 HA13 HB10

Claims (5)

[Claims] 1. A phenol (P1) and an aldehyde (A) having a functionality of 3 or more are converted to a phenol (P) having a pH of 7 or more in the presence of a basic catalyst.
A phenol (P2) and an acid catalyst are added to the resole resin obtained by the reaction (primary reaction)
And a novolak-type phenol resin obtained by a further reaction (secondary reaction). The weight average molecular weight in terms of polystyrene measured by GPC measurement is 100 at the end of the primary reaction.
A method for producing a novolak type phenolic resin for photoresist, wherein the secondary reaction is completed at a temperature of from 5,000 to 5,000 at the end of the secondary reaction. 2. P1 is phenol, meta-cresol,
P2 consists of one or more of 3,5-xylenol, and P2 is paracresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 3,4-xylenol, 2,6-xylenol, 5-xylenol,
2. The method for producing a novolak type phenolic resin for a photoresist according to claim 1, comprising at least one of 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, and A comprising formaldehyde and / or paraformaldehyde. . 3. The method for producing a novolak type phenol resin for a photoresist according to claim 1, wherein the basic catalyst at the time of the primary reaction is a tertiary amine, and the acid catalyst at the time of the secondary reaction is an organic carboxylic acid. 4. The method according to claim 1, wherein the molar ratio (P1 / P2) of P1 and P2 is from 0.2 to 3.0. 5. The molar ratio (A / P1) of the aldehyde (A) to the phenol (P1) in the primary reaction is 0.5 to 5.
3.0, and the molar ratio (A / P1 + P2) of the aldehyde (A) to the phenol (P1) and the phenol (P2) in the secondary reaction is 0.2 to 1.5. The method for producing a novolak-type phenol resin for a photoresist according to claim 1.