JPH11349654A - Preparation of photoresist phenolic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a photoresist phenolic resin having higher heat resistance and higher resolution and higher sensitivity than conventional photoresist phenolic resins. SOLUTION: This method for preparing a photoresist phenolic resin comprises reacting a phenolic composition comprising 55-98 wt.% m-cresol, 1-20 wt.% p-cresol, and 1-25 wt.% xylenol and/or trimethylphenol with an aldehyde having an alkenyl group in an aldehyde composition comprising formaldehyde and the aldehyde having an alkenyl group at a weight ratio of the formaldehyde to the aldehyde of 1/9 to 9/1 in the presence of an acid catalyst, then reacting the resulting product with the formaldehyde in the aldehyde composition, neutralizing the acid catalyst with an amine after completion of the reaction, and washing the product thus obtained with water to remove the acid catalyst to such a small amount as not to adversely affect practical use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a photoresist having high heat resistance, a high residual film ratio, a high sensitivity and a high resolution for a photoresist used in lithography for producing semiconductors and LCDs. The present invention relates to a method for producing a phenolic resin.

[0002]

2. Description of the Related Art In general, a positive photoresist is composed of a sensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolak-type phenol resin).
Resin) is used. Positive photoresists having such a composition exhibit high resolving power upon development with an alkaline solution, 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 resin also has high heat resistance to plasma dry etching after exposure due to the structure having many aromatic rings, so far novolak type phenolic resin and naphthoquinonediazide-based photosensitizer Numerous positive-type photoresists containing have been developed and put into practical use, and have achieved great results.

Generally, a phenol resin obtained by reacting meta-paracresol and formaldehyde in the presence of an acid catalyst is used as a phenol resin for a photoresist. In order to adjust or improve the characteristics of photoresist, the ratio and molecular weight of meta-paracresol have been studied.
Technology has been applied. In semiconductor photoresists,
Characteristics such as high heat resistance, high resolution and high sensitivity are required, and to improve heat resistance, monomers such as alkylphenols such as xylenol and trimethylphenol and aromatic aldehydes have been studied. There is an example in which hydroxybenzaldehyde and the like have been studied for higher sensitivity. In each case, although a slight improvement effect was obtained, a sufficient effect was not obtained.

In recent years, there has been an extremely high demand for high integration of semiconductors, and accordingly, there has been an extremely high demand for high resolution of photoresists. In order to improve the resolution, a phenolic resin to be used has been studied to improve the phenolic resin, such as a high-ortho-modified resin. However, it has not been put to practical use due to poor heat resistance. In addition, various monomers
There are cases where the types have been studied, but all have their advantages and disadvantages and have not yet been put to practical use.

A phenolic resin for a photoresist is obtained by reacting a phenol with an aldehyde in the presence of an acid catalyst. However, since the remaining acid catalyst greatly affects the performance of the photoresist, it is removed. Oxalic acid is generally used as an acid catalyst which is easy to be used. However, when a special aldehyde other than formaldehyde is applied for the purpose of improving performance, the reaction does not proceed with a weak acid such as oxalic acid,
Strong acids such as organic sulfonic acids and inorganic acids are used. When an organic sulfonic acid or the like is used as an acid catalyst, it is difficult to be removed by decomposition and sublimation like oxalic acid, so that a large amount thereof remains in the phenol resin, hindering the production of the phenol resin, and the performance of the photoresist. Is a factor that greatly reduces the In addition, because of its strong corrosiveness, impurities such as metal from the phenolic resin reaction vessel also increase, and only those that are not suitable as photoresist phenolic resins can be obtained. Not practical.

[0006]

DISCLOSURE OF THE INVENTION The present invention has a high heat resistance.
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 both high resolution and high sensitivity.

[0007]

According to the present invention, the composition of the phenols (P) is 55-98% by weight of meta-cresol, 1-20% by weight of para-cresol, xylenol and / or trimethylphenol. 1 to 25% by weight, the composition of the aldehyde (A) is an aldehyde containing formaldehyde and an alkenyl group, and the weight ratio thereof is 1 / 9-9 / 1;
An alkenyl group-containing aldehyde is reacted with phenols in the presence of an acid catalyst, and then with formaldehyde,
A method for producing a phenolic resin for photoresists, comprising neutralizing an acid catalyst with amines after completion of the reaction, and removing the acid catalyst by washing with water until the amount of the acid catalyst becomes small enough not to affect practical use. The present invention makes it possible to manufacture a photoresist having high heat resistance, high resolution and high sensitivity.

Hereinafter, the present invention will be described in detail. First, the raw materials used in the present invention will be described. Pheno
(P) include metacresol and paracresol.
Xylenol, trimethylphenol, and xylenol are 2,3-xylenol, 2,4-
Xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol and 3,5-xylenol can be used, and they can be used alone or in combination of two or more. Good.
As trimethylphenol, 2,3,5-trimethylphenol and 2,3,6-trimethylphenol can be used, and they may be used alone or as a mixture of two kinds. The proportion of meta-cresol in the phenols (P) is 55-98% by weight, particularly preferably 70-95% by weight. If it is less than 55% by weight, the sensitivity of the photoresist becomes too low,
If the content is more than 98% by weight, on the contrary, the sensitivity is too high and the resolution is lowered, so that it is not suitable for practical use. The proportion of paracresol is particularly preferably from 1 to 20% by weight and more preferably from 3 to 15% by weight. If it is more than 20% by weight, the sensitivity of the photoresist is low, and if it is less than 1%, the resolution is low. The proportion of xylenol and / or trimethylphenol is preferably 1-25% by weight and more preferably 3-20% by weight. Further, xylenol and trimethylphenol may be used alone or in combination. When xylenol and / or trimethylphenol is more than 25% by weight,
If the sensitivity of the photoresist is low, if it is low, the heat resistance and the resolution are lowered, so that it is not suitable for practical use.

As the aldehyde (A), a mixture of formaldehyde and an aldehyde containing an alkenyl group is used. By using an aldehyde containing an alkenyl group, a double bond is introduced into the molecule, and the structure of the aldehyde moves. The effect of improving the characteristics of the photoresist can be obtained by limiting the ratio, and the ratio is 9 / 1-1 / 9 and 8 / 2-2 / 9 by weight.
8 is particularly preferred. As formaldehyde, either formalin (aqueous solution) or paraformaldehyde (solid) may be used, and it may be used alone or in combination. Examples of the aldehyde containing an alkenyl group include propenal (acrolein), butenal (crotonaldehyde and the like), pentenal, hexenal, heptenal, octenal, cinnamaldehyde, and the like.
It is not limited to these, and any aldehyde containing an alkenyl group can be used. Also, the molar ratio of aldehydes (A) to phenols (P) (A / P)
Is 0.1-0.9, preferably 0.2-0.8. When it is lower than 0.1, the weight average molecular weight is small and the sensitivity is too high to obtain heat resistance. When it is higher than 0.9, the weight average molecular weight is large, and the sensitivity is too low to be suitable for practical use.

[0010] The acid catalyst is not particularly limited,
Any alkenyl-containing aldehyde and phenols (P) can be used as long as they have the ability to react. Organic carboxylic acids such as acetic acid and oxalic acid do not have the ability to react aldehydes containing an alkenyl group with phenols (P). Therefore, benzenesulfonic acid, paratoluenesulfonic acid, methanesulfonic acid and the like are generally used. It is preferable to use inorganic acids such as organic sulfonic acid, hydrochloric acid and sulfuric acid. The amount used is generally preferably from 0.01% by weight to 5% by weight based on the phenols (P), but is preferably 5% by weight.
If the amount is too large, the reaction will proceed too sharply, making it difficult to control. If the amount is less than 0.1% by weight, the reaction will proceed slowly, which is not economically preferable. However, for the characteristics of the photoresist resin, it is preferable that the amount is as small as possible even within the above range. As amines for neutralizing the acid catalyst, trimethylamine, triethylamine, diethylamine, tributylamine and the like can be used, but there is no particular limitation, and the acid catalyst is neutralized and soluble in water. Any substance that forms a salt can be used.
The amount used depends on the amount of the acid catalyst, but is preferably used in such an amount that the acid catalyst is neutralized and the pH in the reaction system falls within the range of 4-8.

Next, the present invention will be described along the reaction (production) procedure. The reaction of the phenol resin is performed by using a stirrer, a thermometer,
A phenol (P), an aldehyde containing an alkenyl group, and an acid catalyst are charged into a reaction vessel equipped with a heat exchanger, and a primary reaction is started. The reaction temperature and time can be appropriately set depending on the reactivity of the monomer, but the reaction time is 2 to 10 hours and the reaction temperature is 70 to 15 as stable and economical production levels.
0 ° C. is preferred. After completion of the primary reaction, a secondary reaction is performed by adding formaldehyde (formalin and / or paraformaldehyde). The formaldehyde may be added in its entirety initially or may be added dropwise over time, and may be selected according to the degree of heat generated when formaldehyde is added. The reaction temperature and time of the secondary reaction can be appropriately selected depending on the properties of the resin to be produced and the reactivity of the monomer. However, the reaction time is 1 to 10 hours and the reaction temperature is 50 and 50 as stable and economical production levels. -150 ° C is preferred. At the time of the primary reaction and the secondary reaction, a reaction solvent can be added and used as necessary. The type of the solvent is not particularly limited, but a solvent that dissolves the phenol resin is preferable. Generally, acetone, ketones such as methyl ethyl ketone, ether alcohols such as ethyl cellosolve,
Examples thereof include alcohols such as methanol, ethanol, propanol and butanol, cyclic ethers such as tetrahydrofuran and dioxane, and esters such as ethyl acetate, butyl acetate and ethyl lactate.

After completion of the reaction, amines are added to stop the reaction to neutralize the acid catalyst, and then water is added to remove the acid catalyst, followed by washing with water. Although the amount and the number of times of washing water are not particularly limited, the number of times of washing to remove the acid catalyst to an amount that does not affect actual use is preferably about 1 to 5 times from the viewpoint of economy. The amount that the acid catalyst does not affect the actual use is an amount that does not adversely affect the performance of the photoresist when the phenolic resin is used for the photoresist, and the amount of the acid catalyst does not affect the actual use.
5,000p, although it depends on how the resin is used)
pm or less can be used for photoresist,
Especially preferably, it is 1000 ppm or less. Further, the temperature at the time of washing with water is not particularly limited, but it is preferable to perform the washing at 40 to 95 ° C from the viewpoint of the efficiency of removing the acid catalyst and the workability. If the separation of the resin and the washing water is poor during washing, it is effective to add a solvent that reduces the viscosity of the resin or to increase the washing temperature. At this time, the kind of the solvent is not particularly limited, but any solvent can be used as long as it dissolves the phenol resin and lowers the viscosity. Generally, ketones such as acetone and methyl ethyl ketone, ether alcohols such as ethyl cellosolve, methanol
Alcohols such as toluene, ethanol, propanol and butanol; cyclic ethers such as tetrahydrofuran and dioxane; and esters such as ethyl acetate, butyl acetate and ethyl lactate.

After the completion of the washing, dehydration and de-monomerization are carried out under normal pressure and reduced pressure to obtain a phenol resin for photoresist. Although the degree of pressure reduction can be set as appropriate, it is preferable to perform the pressure reduction at about 0.1 to 200 torr. The temperature at which the phenol resin is taken out of the reaction vessel after the dehydration and de-monomerization can be appropriately set depending on the properties and viscosity of the phenol resin, but from the viewpoint of the stability of the resin, the temperature is preferably from 150 to 250 ° C. . In some cases, it can be dissolved in a solvent used for a photoresist and discharged as a liquid.

Next, the pheno obtained by the production method of the present invention.
The characteristics of the resin will be described. The weight average molecular weight is measured by gel permeation chromatography (GPC) and calculated based on a calibration curve prepared using a polystyrene standard substance. GPC measurement uses tetrahydrofuran as an elution solvent, flow rate 1.0 ml
/ Min at a column temperature of 40 ° C. Body: TO
HLC-8020 manufactured by SOH, detector: UV-8011 manufactured by TOSOH set to a wavelength of 280 nm, analytical column: SHOdex KF-802 manufactured by Showa Denko, one K
F-8031 pieces and KF-805 1 piece were used.

The weight-average molecular weight of the phenolic resin for photoresist of the present invention is not particularly limited.
Preferably it is 5000. Weight average molecular weight is 150
If it is smaller than 0, the sensitivity is too high and the heat resistance is poor, and 1
If it is larger than 5000, the sensitivity is too low to be suitable for actual use. The easiest way to control the weight average molecular weight is to change the molar ratio (A / P) of the aldehyde (A) and the phenol (P) depending on the target molecular weight. , A / P is preferably 0.1-0.9. Further, free phenol remaining in the phenol resin
Although the amount of the compound is not particularly limited, it is preferably 5% or less, particularly preferably 3% or less in terms of the peak area of GPC from the viewpoint of handling and the characteristics of the photoresist. The control of free phenols can be carried out under reduced pressure by dehydration and demonomerization.
Is most easily performed depending on the degree of pressure reduction and the end temperature.

The smaller the metal impurities in the phenolic resin for photoresist, the better, but it is necessary that each metal be 1 ppm or less. With a phenol resin containing a metal impurity exceeding 1 ppm, it is difficult to reduce the amount of the metal impurity which can be used as a phenol resin for a photoresist, whatever the treatment after the synthesis. 1pp
In order to produce a phenolic resin having a metal impurity content of not more than m, the phenolic resin is made of glass lining and / or a metal selected from tantalum, hafnium, zirconium, niobium and titanium and / or an alloy thereof, It is preferable to use a manufacturing apparatus using a metal material containing no other material as a material of the reaction equipment, or to use a manufacturing apparatus made of glass lining, and any apparatus may be used.

[0017]

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 In a 5 L four-necked flask (made of zirconium) equipped with a stirrer, a thermometer and a heat exchanger, 1470 parts of metacresol, 82 parts of paracresol, 2,
82 parts of 3,5-trimethylphenol, 128 parts of crotonaldehyde and 16 parts of paratoluenesulfonic acid were charged and reacted at 98 to 102 ° C. for 4 hours. Then, 650 parts of ethyl cellosolve was added, and the internal temperature was 60 ° C. Let it cool down,
Then 690 parts of 37% formalin at 58-62 ° C.
The mixture was added dropwise over 5 hours, and the reaction was further performed for 30 minutes. The molar ratio between the aldehyde (A) and the phenol (P) is 0.69
0. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 2 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 11 parts of triethylamine was added, 170 parts of acetone and 1100 parts of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. The pH of the separated water separated by standing was adjusted to 5.5 to 7.5 with triethylamine and paratoluenesulfonic acid, and the separated water was removed. This washing operation was repeated once again using 170 parts of acetone and 1100 parts of ion-exchanged water, followed by dehydration under normal pressure to an internal temperature of 140 ° C.
Dehydration and demonomerization were carried out at 0 torr at 195 ° C. under reduced pressure to obtain 1650 g of a phenol resin for photoresist. The obtained resin had a weight average molecular weight of 3,500, a free monomer of 2.0%, an iron impurity of 25 ppb, and a residual acid catalyst amount of 3,500 ppm.

Example 2 1306 parts of metacresol, 82 parts of paracresol, and 245 parts of 2,5-xylenol were placed in a 5 L four-necked flask (made of glass) equipped with a stirrer, a thermometer and a heat exchanger. , 132 parts of crotonaldehyde and 16 parts of paratoluenesulfonic acid, and the mixture was reacted at 98 to 102 ° C. for 4 hours. Thereafter, 650 parts of ethyl cellosolve was added to cool the mixture to an internal temperature of 60 ° C., and 712 parts of 37% formalin Was added dropwise at 58-62 [deg.] C. over 1.5 hours, and further reacted for 30 minutes. The molar ratio between the aldehyde (A) and the phenol (P) is 0.718. Thereafter, the temperature is increased stepwise, and finally the reflux temperature (97-103 ° C)
For 2 hours. After completion of the reaction, the mixture was cooled to 90 ° C., and 11 parts of triethylamine was added.
0 parts and 1100 parts of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. P of the separated water separated by standing
H was adjusted to 5.5-7.5 with triethylamine and paratoluenesulfonic acid, and the separated water was removed.
This washing operation was repeated once using 170 parts of acetone and 1100 parts of ion-exchanged water, followed by dehydration under normal pressure to an internal temperature of 140 ° C., and further at 195 ° C. at 80 torr.
Dehydration and demonomerization were performed under reduced pressure to obtain 1750 g of phenol resin for photoresist. The weight average molecular weight of the obtained resin was 4230, the free monomer was 2.9%, the iron impurity was 100 ppb, and the amount of the remaining acid catalyst was 2500 p.
pm.

Example 3 1150 parts of meta-cresol, 200 parts of para-cresol, and 2,5-, were placed in a 5 L four-necked flask (manufactured by tantalum) equipped with a stirrer, thermometer and heat exchanger.
300 parts of xylenol, 132 parts of crotonaldehyde,
Charge 16 parts of p-toluenesulfonic acid, 98-102
After reacting at 4 ° C. for 4 hours, 650 parts of ethyl cellosolve was added and the mixture was cooled to an internal temperature of 60 ° C., and 812 parts of 37% formalin were added dropwise at 58-62 ° C. for 1.5 hours.
The reaction was further performed for 30 minutes. The molar ratio between the aldehyde (A) and the phenol (P) is 0.796. Thereafter, the temperature is raised stepwise, and finally the reflux temperature (97-10
(3 ° C.) for 2 hours. After completion of the reaction, the mixture was cooled to 90 ° C., and 11 parts of triethylamine was added.
The mixture was stirred and allowed to stand at ℃. The pH of the separated water separated by standing was adjusted to 5.5 to 7.5 with triethylamine and paratoluenesulfonic acid, and the separated water was removed. This washing operation was repeated once again using 170 parts of acetone and 1100 parts of ion-exchanged water, followed by dehydration under normal pressure to an internal temperature of 140 ° C., and further at 19 torr at 80 torr.
Dehydration and demonomerization were performed under reduced pressure to 5 ° C. to obtain 1650 g of a phenol resin for photoresist. The weight average molecular weight of the obtained resin is 9000, and the free monomer is 2.5.
%, Iron impurities are 25 ppb, and the amount of remaining acid catalyst is 800
ppm.

Example 4 1320 parts of metacresol, 180 parts of paracresol, and 2 parts of a 5 L four-necked flask (made of hafnium) equipped with a stirrer, a thermometer and a heat exchanger.
After 120 parts of 3,5-trimethylphenol, 320 parts of crotonaldehyde and 16 parts of paratoluenesulfonic acid were charged and reacted at 98 to 102 ° C for 4 hours, 650 parts of ethyl cellosolve was added and the internal temperature was 60 ° C. Let it cool down,
Then 330 parts of 37% formalin at 58-62 ° C.
The mixture was added dropwise over 5 hours, and the reaction was further performed for 30 minutes. The molar ratio between the aldehyde (A) and the phenol (P) is 0.58
5 Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 2 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 11 parts of triethylamine was added, 150 parts of acetone and 1100 parts of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. The pH of the separated water separated by standing was adjusted to 5.5 to 7.5 with triethylamine and paratoluenesulfonic acid, and the separated water was removed. This washing operation was repeated once using 150 parts of acetone and 1100 parts of ion-exchanged water, and then dehydrated to an internal temperature of 140 ° C. under normal pressure.
Dehydration and de-monomerization were performed at 195 ° C. under reduced pressure at 0 torr to obtain 1600 g of a phenol resin for photoresist. The obtained resin had a weight average molecular weight of 2,000, a free monomer of 1.8%, an iron impurity of 50 ppb, and a residual acid catalyst amount of 4,200 ppm.

Example 5 In a 5 L four-necked flask (manufactured by niobium) equipped with a stirrer, a thermometer and a heat exchanger, 1000 parts of metacresol, 300 parts of paracresol and 300 parts of 3,5-xylenol were used. , 250 parts of acrolein and 16 parts of p-toluenesulfonic acid, and reacted at 98 to 102 ° C. for 4 hours. Then, 780 parts of ethyl cellosolve was added, and the mixture was cooled to an internal temperature of 60 ° C.
30 parts were added dropwise at 58-62 ° C. in 1.5 hours, and
The reaction was performed for 0 minutes. The molar ratio between the aldehyde (A) and the phenol (P) is 0.589. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 2 hours. After completion of the reaction, the mixture was cooled to 90 ° C., and 11 parts of triethylamine was added.
And 1100 parts of ion-exchanged water, and the mixture was stirred and allowed to stand at about 70 ° C. PH of separated water separated by standing
Was adjusted with triethylamine and p-toluenesulfonic acid so as to be 5.5 to 7.5, and separated water was removed. Using 300 parts of acetone and 1100 parts of ion-exchanged water,
After repeating this washing operation once again, the internal temperature was reduced to 1 at normal pressure.
After dehydration to 70 ° C, dehydration and demonomerization were performed at 80 torr under reduced pressure to 195 ° C to obtain 1600 g of a phenol resin for photoresist. The obtained resin had a weight average molecular weight of 12,000, a free monomer of 3.5%, an iron impurity of 38 ppb, and a residual acid catalyst amount of 180 ppm.

Comparative Example 1 400 parts of meta-cresol, 600 parts of para-cresol and 3 parts of the same reactor as in Example 1 were used.
412.9 parts of 7% formalin (charged molar ratio 0.5
5) After charging 2 parts of oxalic acid and performing a reflux reaction at 98 to 102 ° C. for 4 hours, dehydration is performed under normal pressure to raise the internal temperature to 140 ° C., and then dehydration is performed under a reduced pressure of 80 Torr to remove the monomer at the internal temperature. The process was continued until the temperature reached 195 ° C. to obtain a phenol resin for photoresist. The obtained product had a weight average molecular weight of 2,200, a free monomer of -3.3%, and an iron impurity of 50 p.
The pb and the amount of the remaining acid catalyst were 3,800 ppm.

Comparative Example 2 400 parts of meta-cresol, 600 parts of para-cresol, 563.1 parts of 37% formalin (charged molar ratio 0.75) were prepared in the same reactor as in Example 1 except that the material was stainless steel. 9 parts of oxalic acid, 96 ~
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
Dehydration and de-monomerization were performed under reduced pressure until the internal temperature reached 195 ° C. to obtain a phenol resin for photoresist. The obtained product had a weight average molecular weight of 9300 and a free monomer of 1
0.6%, iron impurities were 6,800 ppb, and the amount of remaining acid catalyst was 800 ppm.

COMPARATIVE EXAMPLE 3 400 parts of metacresol, 600 parts of paracresol, and 2.5-liter were placed in a 5 L four-necked flask (stainless steel) equipped with a stirrer, thermometer and heat exchanger.
After 600 parts of xylenol, 5 parts of crotonaldehyde, and 16 parts of paratoluenesulfonic acid were charged and reacted at 98 to 102 ° C for 4 hours, 780 parts of ethyl cellosolve was added, and the mixture was cooled to an internal temperature of 60 ° C. 712 parts of 37% formalin were added successively at 58-62 ° C for 1.5 hours, and the mixture was further reacted for 30 minutes. The molar ratio of aldehydes (A) to phenols (P) is 0.624 and the weight ratio of formaldehyde to crotonaldehyde is 52.5 / 1. Thereafter, the temperature is raised stepwise, and finally the reflux temperature (9
(7-103 ° C) for 2 hours. After the reaction, 90
After cooling to 0 ° C, 11 parts of triethylamine was added, 170 parts of acetone and 1100 parts of ion-exchanged water were added, and the mixture was stirred and allowed to stand at about 70 ° C. The pH of the separated water separated by standing was adjusted to 5.5 to 7.5 with triethylamine and paratoluenesulfonic acid, and the separated water was removed. 170 parts of acetone, 110 ion-exchanged water
This water washing operation was repeated once again using 0 parts, and then dehydrated under normal pressure to an internal temperature of 140 ° C.
Dehydrate and remove monomers under reduced pressure at rr to 195 ° C,
1600 g of a phenol resin for a photoresist was obtained. The obtained resin had a weight average molecular weight of 5100 and a free monomer.
Was 2.5%, the iron impurity was 5,500 ppb, and the amount of the remaining acid catalyst was 9,000 ppm.

The properties of the phenolic resin obtained as described above as a photoresist were measured, and are shown in Table 1 together with the weight average molecular weight and the amount of free monomer.
Table 2 shows the amounts of metal impurities.

Evaluation Example 1 Evaluation Method of Heat Resistance 100 parts of a novolak type phenol resin and 30 parts of 2,3,4-trihydroxybenzophenone ester of naphthoquinone 1,2-diazido-5-sulfonic acid were lactic acid. It was dissolved in ethyl to prepare a resist solution. These were filtered through a 0.2 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 shape change of the resist pattern on the silicon wafer was observed with a scanning 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 adjustment, pretreatment, coating, exposure and development using a test chart mask were performed, and the resist pattern shape was changed to a scanning electron beam. Observed under a microscope. The depth of focus was obtained by visually observing a photograph when the focus was changed at a line width of 0.30 μm, and measuring a resolvable focus variation width. 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 Method 3: Method for Measuring Sensitivity Stability] A phenol resin was dissolved in ethyl lactate to prepare a sample solution. These were filtered through a 5B filter paper, applied to a silicon wafer by a conventional method, and dried on a hot plate at 110 ° C. for 90 seconds. Thereafter, it was immersed in a developing solution (2.38% aqueous solution of tetramethylammonium hydroxide), and the time required for the phenol resin to completely dissolve was measured. The measurement was performed at n = 5, and the sensitivity stability was evaluated based on the variation in the dissolution time.

[0030]

[Table 1]

[Evaluation Method 4: Measurement Method of Metal Impurity Amount]
Metal impurities were measured using a frameless atomic absorption spectrophotometer.

[0032]

[Table 2]

[0033]

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

Continuation of the front page (72) Inventor Osamu Onishi 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Durez Corporation

Claims (12)

[Claims] The composition of phenols (P) is 55-98% by weight of meta-cresol, 1-20% by weight of para-cresol, xylenol and / or trimethylphenol 1-.
25% by weight, the composition of the aldehyde (A) is an aldehyde containing formaldehyde and an alkenyl group, the weight ratio of which is 1 / 9-9 / 1;
After reacting an aldehyde containing an alkenyl group with the formaldehyde, formaldehyde is reacted, and after the reaction is completed, the acid catalyst is neutralized with an amine, and then washed with water so that the amount of the acid catalyst becomes small enough not to affect the actual use. A process for producing a phenolic resin for a photoresist. 2. Tantalum, hafnium, zirconium,
The reaction is carried out using a production apparatus using a metal material made of a metal selected from niobium and titanium and / or an alloy thereof and containing substantially no other material as a reaction equipment material and / or a glass lining production apparatus. Pheno obtained by
2. The method for producing a phenolic resin for a photoresist according to claim 1, wherein metal impurities in the phenolic resin are 1 ppm or less in each element. 3. The phenolic resin for a photoresist according to claim 1, wherein the molar ratio (A / P) of the aldehyde (A) and the phenol (P) is 0.1-0.9. Manufacturing method. 4. The method for producing a phenolic resin for a photoresist according to claim 1, wherein the weight average molecular weight in terms of polystyrene by GPC is from 1500 to 15000. 5. Xylenol is 2,3-xylenol,
2,4-xylenol, 2,5-xylenol, 3,4
3. The method for producing a phenolic resin for a photoresist according to claim 1, wherein the phenolic resin is xylenol or 3,5-xylenol. 6. The method for producing a phenolic resin for photoresist according to claim 1, wherein the trimethylphenol is 2,3,5-trimethylphenol. 7. The method for producing a phenolic resin for a photoresist according to claim 1, wherein the aldehyde containing an alkenyl group is propenal (acrolein) or 2-butenal (crotonaldehyde). 8. The method for producing a phenolic resin for a photoresist according to claim 1, wherein the acid catalyst is paratoluenesulfonic acid and the amine for neutralization is triethylamine. 9. The method according to claim 1, wherein the amount of the acid catalyst remaining in the phenol resin is 5,000 ppm or less.
3. The method for producing a phenolic resin for photoresist according to item 2. 10. Among the metal impurities in the phenol resin, each element of lithium, sodium, potassium, calcium, magnesium, barium, iron, nickel, chromium, aluminum, zinc, tin, copper, lead, manganese and silicon 3. The method for producing a phenolic resin for a photoresist according to claim 1, wherein the content of phenolic resin is 1 ppm or less. 11. The method for producing a phenolic resin for a photoresist according to claim 1, wherein ethylene glycol monoethyl ether, butanol, and ethyl lactate are used as a reaction solvent. 12. The method for producing a phenolic resin for a photoresist according to claim 1, wherein free phenols are 5% or less in a peak area of GPC.