JP2001264974A - Phenolic resin for photoresist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phenolic resin for a high resolution photoresist having both high heat resistance and high sensitivity. SOLUTION: The phenolic resin is obtained by reacting specified phenols with formaldehyde and/or p-formaldehyde in the presence of an acidic catalyst and has a weight average molecular weight of 1,500-15,000. The following regions (A), (B) and (C) of the resin are 10-45%, 35-85% and 0-40%, respectively, and the area ratio of (the region B)+(the region C) to the region A is 1.2-4.5. The sum of the regions (A), (B) and (C) is 100%. The region (A) is the area of the molecular weight range of 150 to <500 (with the exception of free phenols), the region (B) is the area of the molecular weight range of 500 to <5,000 and the region (C) is the area of the molecular weight range of >=5,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoresist having high heat resistance, high resolution and high sensitivity, which is used as a base resin of a photoresist used for lithography in manufacturing semiconductors and LCDs. The present invention relates to a phenolic resin for a photoresist which enables the production of a phenol resin.

[0002]

2. Description of the Related Art Generally, a positive type photoresist uses a photosensitive agent having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolak 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 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 photoresists containing have been developed and put into practical use, and have achieved great results.

As a phenol resin for a positive photoresist, a novolak phenol resin obtained by reacting metacresol / paracresol with formaldehyde in the presence of an acidic catalyst is generally used. Then, in order to adjust or improve the characteristics of the photoresist, meta-cresol / para-cresol in phenol resin is used.
The ratio, molecular weight, molecular weight distribution, and the like of the metal have been studied and applied to lithography techniques such as semiconductors and LCDs. 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, and applications of monomers such as alkylphenols and aromatic aldehydes are being studied to increase the heat resistance. There are examples of studies on hydroxybenzaldehyde for increasing the sensitivity. However, in each case, although a slight improvement is seen,
No dramatic effect has been obtained.

In order to increase the resolution, there is an example in which a high-ortho resin containing a large number of structures in which a bonding group of a phenol resin is bonded at an ortho-ortho position of an aromatic ring is used from the viewpoint of controlling the molecular structure. When this 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. In addition, there are examples in which various monomers have been studied, but all of them have advantages and disadvantages and have not been put to practical use.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a phenolic resin for a photoresist which enables the production of a photoresist having high heat resistance, high resolution and high sensitivity. The present inventors have proposed that a phenolic resin serving as a base resin preferably has a high-density three-dimensional molecular structure in order to improve the heat resistance of a photoresist, and has a high resolution and a high resolution.
In order to improve the sensitivity, it was considered that the molecular structure should be such that a phenol compound having a high interaction with the photosensitizer is bonded to the terminal portion of the molecule to effectively express the interaction with the photosensitizer. The present invention provides a phenol compound having a high interaction with a photosensitizer at the end by applying a monofunctional phenol in a polycondensation reaction with formalin, among xylenol and trimethylphenols having a strong interaction with a photosensitizer. Have been found to be able to be efficiently arranged and a desirable molecular structure can be obtained, and as a result of further intensive studies, they have been completed.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for preparing 30-70% by weight of meta-cresol, 1-50% by weight of para-cresol and 2,4-xylenol, 2,6-xylenol,
It is obtained by reacting a phenol comprising 1 to 50% by weight of a monofunctional phenol comprising at least one kind of 3,6-trimethylphenol with an aldehyde comprising formaldehyde and / or paraformaldehyde under an acidic catalyst. A phenol resin having a weight average molecular weight of 1500 to 15000, wherein the following (A) region is 10 to 45%,
The (B) region is 35-85%, the (C) region is 0-40%, and the area ratio of (B region + C region) / A region is 1.
It is a phenol resin for photoresists, which is 2-4.5. However, the total of the area (A), the area (B) and the area (C) is 100%. The (A) region is an area having a molecular weight of 150 or more and less than 500 (excluding free phenols), and the (B) region has a molecular weight of 50 or less.
The area is in the range of 0 to less than 5000, and the region (C) is the area in the range of molecular weight of 5,000 or more.

Hereinafter, the present invention will be described in detail. First, the phenolic resin of the present invention will be described along the reaction procedure. In the synthesis reaction, phenols, aldehydes, and an acidic catalyst are charged into a reaction vessel equipped with a stirrer, a thermometer, and a heat exchanger to start the reaction. The reaction temperature and time of the reaction are pheno-
The reaction time and the reaction temperature are particularly preferably 0.5 to 8 hours and the reaction temperature of 40 to 120 ° C. as stable and economical production levels. In the reaction, a reaction solvent can be added and used if necessary. The type of the solvent is not particularly limited, but a solvent that dissolves the phenol resin is preferable. Generally, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, alcohols such as methanol, ethanol, propanol and butanol, ether alcohols such as ethyl cellosolve and the like.
And cyclic ethers such as tetrahydrofuran and dioxane, and esters such as ethyl acetate and butyl acetate.

After the completion of the reaction, dehydration and de-monomerization are carried out under normal pressure and reduced pressure to obtain a phenol resin for photoresist. The conditions for dehydration and demonomerization are not limited. However, considering the stability (variability) and viscosity of the obtained phenol resin, the degree of pressure reduction is from 0.1 torr to 20 torr.
It is particularly preferable to perform the process at about 0 torr. The temperature at which the phenol resin is removed from the reactor after the dehydration and de-monomerization can be appropriately set depending on the characteristics and viscosity of the phenol resin, but is preferably from 150 to 250 ° C. from the viewpoint of the stability of the resin. In some cases, it can be dissolved in a solvent used for a photoresist and discharged as a liquid.

Next, the raw materials used in the present invention will be described. Phenols include meta-cresol, para-cresol, and monofunctional phenols (2,4-xylenol, 2,6-xylenol for xylenol, 2,3,6-trimethylphenol for trimethylphenol)
Use). The monofunctional phenols may be used alone or in combination of two or more. The proportion of metacresol in phenols is 30-70% by weight, and 40-60%.
If the amount is less than 30% by weight, the sensitivity of the photoresist is too low. If the amount is more than 70% by weight, the sensitivity is too high and the resolution is lowered, which is not suitable for practical use. The proportion of paracresol is 1-5
0% by weight, particularly preferably 20-40% by weight.
When the content is more than 0% by weight, the sensitivity of the photoresist is lowered, and when the content is less than 1% by weight, the resolution is reduced. The proportion of monofunctional phenol is 1-50% by weight, 20-
40% by weight is particularly preferred. 50 monofunctional phenols
When the content is more than 10% by weight, the molecular weight does not increase so that the heat resistance is low and the sensitivity of the photoresist is low, which is not suitable for practical use. When the amount is less than 1% by weight, the effect of the monofunctional phenol cannot be brought out, and the heat resistance and the resolution cannot be satisfied.

As aldehydes, formaldehyde and / or paraformaldehyde are used. Formaldehyde is usually used as an aqueous solution (formalin). The molar ratio of aldehydes to phenols is 0.1-1.0, particularly preferably 0.2-0.9.
It is. When it is lower than 0.1, the weight average molecular weight is too small to obtain heat resistance. When it is higher than 1.0, the weight average molecular weight becomes too large and the sensitivity is too low, which is not suitable for practical use.

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 paratoluenesulfonic acid. Can be used.
In general, the amount used is preferably from 0.01% by weight to 5% by weight based on the phenol. However, if the amount is more than 5% by weight, the reaction proceeds excessively and is difficult to control.
When the amount is less than 0.1% by weight, the progress of the reaction is slow, 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.

Next, the characteristics of the phenol resin of the present invention will be described. The weight average molecular weight is measured by GPC and calculated based on a calibration curve created using a polystyrene standard substance. GPC measurement uses tetrahydrofuran as an elution solvent, flow rate 1.0 ml / min,
The test was performed at a column temperature of 40 ° C. The device is: T
OSLC HLC-8020, detector: wavelength 280 nm
UV-8011 made by TOSOH, analytical column: 1 SHOdex KF-802 made by Showa Denko, K
One F-803 and one KF-805 were used.

[0013] Pheno for photoresist in the present invention
The weight average molecular weight of the resin is not particularly limited.
It is preferably from 0 to 15000. When the weight average molecular weight is less than 1500, the sensitivity is too high and the heat resistance is inferior. When it is more than 15,000, the sensitivity is too low and it is not suitable for practical use. The following (A) region is 10-45%,
The (B) region is 35-85%, the (C) region is 0-40%, and the area ratio of (B region + C region) / A region is 1.
2-4.5. However, the total of the area (A), the area (B) and the area (C) is 100%. The (A) region is an area having a molecular weight of 150 to less than 500 (excluding free phenols), and the (B) region has a molecular weight of 500
The area (C) is an area having a molecular weight of 5,000 or more. (B area + C
When the area ratio of the (area) / A area is smaller than 1.2, the sensitivity is too high and the heat resistance is inferior. When the area ratio is larger than 4.0, the sensitivity is too low and not suitable for practical use. Further, the amount of free phenols remaining in the phenol resin is not particularly limited.
The peak area of C is preferably 8% or less, particularly preferably 4% or less. Control of free phenols
It is easiest to perform dehydration and demonomerization under reduced pressure depending on the degree of reduced pressure and the end temperature.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.
All “%” described herein indicate “% by weight”. The present invention is not limited by these embodiments. In each example, the weight average molecular weight of the resin and the value of (B region + C region) / A region were determined by the GPC measurement.

Example 1 Metacresol 658 was placed in a 3 L four-necked flask equipped with a stirrer, thermometer and heat exchanger.
g, paracresol 392 g, 2,4-xylenol 3
50 g (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 47/28/25), 553.4 g of 37% formalin (A / P molar ratio = 0.630), and 2.8 g of oxalic acid were charged, and the reaction temperature was increased. The reaction was performed at 58-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After the completion of the reaction, the mixture was dehydrated under normal pressure to an internal temperature of 140 ° C.
Dehydration and demonomerization were carried out to an internal temperature of 195 ° C. under a reduced pressure of rr to obtain a phenol resin for photoresist. The weight average molecular weight of the obtained resin is 3400, and the A region is 22.0.
%, The B region was 64.9%, the C region was 10.0%, and the area ratio of (B region + C region) / A region was 3.40.

Example 2 658 g of meta-cresol and 392 g of para-cresol were placed in the same reactor as in Example 1.
350 g of 2,6-xylenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 47/28 /
25), 733.5 g of 37% formalin (A / P molar ratio = 0.835) and 2.8 g of oxalic acid were charged, and the reaction temperature was 5%.
The reaction was performed at 8-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated to an internal temperature of 140 ° C. under normal pressure, and further dehydrated and de-monomerized to an internal temperature of 195 ° C. under a reduced pressure of 70 torr.
Resin was obtained. The weight average molecular weight of the obtained resin is 680.
0, the A region was 21.7%, the B region was 52.0%, the C region was 24.5%, and the area ratio of (B region + C region) / A region was 3.53.

Example 3 658 g of meta-cresol, 392 g of para-cresol,
350 g of 2,3,6-trimethylphenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol =
47/28/25), 720.6 g of 37% formalin
(A / P molar ratio = 0.840) and 2.8 g of oxalic acid were charged and reacted at a reaction temperature of 58-62 ° C. for 60 minutes. Thereafter, the temperature is increased stepwise, and finally the reflux temperature (97-1)
(03 ° C.) for 4 hours. After completion of the reaction, the mixture was dehydrated under normal pressure to an internal temperature of 140 ° C, and further dehydrated and demonomerized to an internal temperature of 195 ° C under a reduced pressure of 70 torr to obtain a phenolic resin for a photoresist. The weight average molecular weight of the obtained resin is 4100, the A region is 23.5%, and the B region is 5%.
8.1%, C area is 14.3%, (B area + C area) /
The area ratio of the region A was 3.08.

Example 4 798 g of meta-cresol and 462 g of para-cresol were placed in the same reactor as in Example 1.
140 g of 2,4-xylenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 57/33 /
10), 518.5 g of 37% formalin (A / P molar ratio = 0.580) and 2.8 g of oxalic acid were charged, and the reaction temperature was 5%.
The reaction was performed at 8-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated to an internal temperature of 140 ° C. under normal pressure, and further dehydrated and de-monomerized to an internal temperature of 195 ° C. under a reduced pressure of 70 torr.
Resin was obtained. The weight average molecular weight of the obtained resin is 360
0, the A region was 22.0%, the B region was 63.2%, the C region was 11.5%, and the area ratio of (B region + C region) / A region was 3.40.

Example 5 798 g of meta-cresol and 462 g of para-cresol were placed in the same reactor as in Example 1.
140 g of 2,6-xylenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 57/33 /
10), 706.3 g of 37% formalin (A / P molar ratio = 0.790) and 2.8 g of oxalic acid were charged, and the reaction temperature was 5%.
The reaction was performed at 8-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated to an internal temperature of 140 ° C. under normal pressure, and further dehydrated and de-monomerized to an internal temperature of 195 ° C. under a reduced pressure of 70 torr.
Resin was obtained. The weight average molecular weight of the obtained resin is 120.
The area A was 16.7%, the area B was 51.2%, the area C was 30.1%, and the area ratio of (area B + area C) / area A was 4.87.

Example 6 798 g of meta-cresol and 462 g of para-cresol were placed in the same reactor as in Example 1.
140 g of 2,3,6-trimethylphenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol =
57/33/10), 699.8 g of 37% formalin
(A / P molar ratio = 0.790) and 2.8 g of oxalic acid were charged and reacted at a reaction temperature of 58 to 62 ° C for 60 minutes. Thereafter, the temperature is increased stepwise, and finally the reflux temperature (97-1)
(03 ° C.) for 4 hours. After completion of the reaction, the mixture was dehydrated under normal pressure to an internal temperature of 140 ° C, and further dehydrated and demonomerized to an internal temperature of 195 ° C under a reduced pressure of 70 torr to obtain a phenolic resin for a photoresist. The weight average molecular weight of the obtained resin is 5200, the A region is 21.6%, and the B region is 5
5.8%, C area is 19.3%, (B area + C area) /
The area ratio of the A region was 3.48.

Example 7 532 g of meta-cresol, 308 g of para-cresol, and
560 g of 2,4-xylenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 38/22 /
40), 629.9 g of 37% formalin (A / P molar ratio = 0.730) and 2.8 g of oxalic acid were charged, and the reaction temperature was 5%.
The reaction was performed at 8-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated to an internal temperature of 140 ° C. under normal pressure, and further dehydrated and de-monomerized to an internal temperature of 195 ° C. under a reduced pressure of 70 torr.
Resin was obtained. The weight average molecular weight of the obtained resin is 200
0, the A region was 25.0%, the B region was 64.3%, the C region was 6.3%, and the area ratio of (B region + C region) / A region was 2.82.

Example 8 532 g of meta-cresol, 308 g of para-cresol, and
560 g of 2,6-xylenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 38/22 /
40), 811.1 g of 37% formalin (A / P molar ratio = 0.940) and 2.8 g of oxalic acid were charged, and the reaction temperature was 5%.
The reaction was performed at 8-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated to an internal temperature of 140 ° C. under normal pressure, and further dehydrated and de-monomerized to an internal temperature of 195 ° C. under a reduced pressure of 70 torr.
Resin was obtained. The weight average molecular weight of the obtained resin is 880.
0, the A region was 18.5%, the B region was 51.8%, the C region was 27.4%, and the area ratio of (B region + C region) / A region was 4.28.

Example 9 The same reactor as in Example 1 was charged with 532 g of metacresol, 308 g of paracresol,
560 g of 2,3,6-trimethylphenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol =
38/22/40), 780.1 g of 37% formalin
(A / P molar ratio = 0.940) and 2.8 g of oxalic acid were charged and reacted at a reaction temperature of 58 to 62 ° C for 60 minutes. Thereafter, the temperature is increased stepwise, and finally the reflux temperature (97-1)
(03 ° C.) for 4 hours. After completion of the reaction, the mixture was dehydrated under normal pressure to an internal temperature of 140 ° C, and further dehydrated and demonomerized to an internal temperature of 195 ° C under a reduced pressure of 70 torr to obtain a phenolic resin for a photoresist. The weight average molecular weight of the obtained resin was 4300, the A region was 22.4%, and the B region was 5
8.3%, C area is 15.6%, (B area + C area) /
The area ratio of the A region was 3.30.

<< Example 10 >> 658 g of meta-cresol, 392 g of para-cresol,
175 g of 2,4-xylenol, 175 g of 2,6-xylenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 47/28/25), 645.7 g of 37% formalin (A / P molar ratio = 0. 735) and 2.8 g of oxalic acid were charged and reacted at a reaction temperature of 58-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, dehydration was performed under normal pressure to an internal temperature of 140 ° C.
Dehydration and demonomerization were performed to an internal temperature of 195 ° C. under a reduced pressure of orr to obtain a phenol resin for photoresist. The weight average molecular weight of the obtained resin is 5100, and the A region is 21.6.
%, The B region was 56.0%, the C region was 18.7%, and the area ratio of (B region + C region) / A region was 3.46.

Example 11 658 g of meta-cresol and 392 g of para-cresol were placed in the same reactor as in Example 1.
175 g of 2,4-xylenol, 175 g of 2,3,6-trimethylphenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 47/28/25),
Formalin 638.1 at 37% (A / P molar ratio = 0.7
35), 2.8 g of oxalic acid was charged, and the reaction temperature was 58-62 ° C.
For 60 minutes. Then, the temperature is increased step by step,
Finally, the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated under normal pressure to an internal temperature of 140 ° C, and further dehydrated and demonomerized to an internal temperature of 195 ° C under a reduced pressure of 70 torr to obtain a phenolic resin for a photoresist. The weight average molecular weight of the obtained resin is 3800, the A region is 22.5%, the B region is 60.1%, and the C region is 12.8.
%, And the area ratio of (B region + C region) / A region was 3.24.

Example 12 In the same reactor as in Example 1, 658 g of meta-cresol, 392 g of para-cresol,
175 g of 2,6-xylenol, 175 g of 2,3,6-trimethylphenol (weight ratio of meta-cresol / para-cresol / 1-functional phenol = 47/28/25),
379.2% formalin 729.2 (A / P molar ratio = 0.8
40), 2.8 g of oxalic acid was charged, and the reaction temperature was 58-62 ° C.
For 60 minutes. Then, the temperature is increased step by step,
Finally, the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After completion of the reaction, the mixture was dehydrated under normal pressure to an internal temperature of 140 ° C, and further dehydrated and demonomerized to an internal temperature of 195 ° C under a reduced pressure of 70 torr to obtain a phenolic resin for a photoresist. The weight average molecular weight of the obtained resin was 5500, the A region was 22.5%, the B region was 53.5%, and the C region was 20.7%.
%, And the area ratio of (B region + C region) / A region was 3.30.

Example 13 658 g of meta-cresol and 392 g of para-cresol were placed in the same reactor as in Example 1.
117 g of 2,4-xylenol, 117 g of 2,6-xylenol, 117 g of 2,3,6-trimethylphenol
(Meta-cresol / para-cresol / 1-functional phenol weight ratio = 47/28/25), 37% formalin 6
71.5 g (A / P molar ratio = 0.770), oxalic acid 2.8
g was charged and reacted at a reaction temperature of 58-62 ° C for 60 minutes. Thereafter, the temperature was raised stepwise, and finally the reaction was carried out at a reflux temperature (97-103 ° C) for 4 hours. After the reaction,
Dehydrate to 140 ° C under normal pressure, and then add 70 torr
Dehydration and de-monomerization to an internal temperature of 195 ° C under reduced pressure of
A phenol resin for photoresist was obtained. The weight average molecular weight of the obtained resin was 4800, the area A was 22.3%,
The area is 56.3%, the area C is 17.9%, (B area + C
The area ratio of (area) / A area was 3.33.

Comparative Example 1 400 g of meta-cresol, 600 g of para-cresol and 3 g of the same reactor were used as in Example 1.
412.9 g of 7% formalin (A / P molar ratio = 0.55)
0), 2 g of oxalic acid were charged, and the reflux temperature (98-102 ° C)
For 4 hours. After the reaction is completed, the internal temperature is 140
And dehydrated to 80 ° C. under reduced pressure of 80 torr.
Dehydration and demonomerization were performed to 5 ° C. to obtain a phenol resin for photoresist. The weight average molecular weight of the obtained resin was 2200, the A region was 44.9%, the B region was 45.3%,
The area C was 4.3%, and the area ratio of (area B + area C) / area A was 1.10.

Comparative Example 2 400 g of meta-cresol, 600 g of para-cresol and 3 g of the same reactor were used as in Example 1.
563.1 g of 7% formalin (A / P molar ratio = 0.75
0), 7 g of oxalic acid was charged, and the reflux temperature (96-100 ° C.)
For 5 hours. After the reaction is completed, the internal temperature is 150
And dehydrated to 80 ° C. under reduced pressure of 80 torr.
Dehydration and demonomerization were performed to 5 ° C. to obtain a phenol resin for photoresist. The weight average molecular weight of the obtained resin is 16000, the A region is 16.9%, and the B region is 48.9.
%, The C region was 32.2%, and the area ratio of (B region + C region) / A region was 4.80.

<< Evaluation Example 1 >> Alkali dissolution time (ADR)
Using a 25% resin-ethyl cellosolve acetate solution, a silicon coater was applied on a silicon wafer to a thickness of about 1 micrometer using a spin coater.
Dry on 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.

Evaluation Example 2 Evaluation Method of Heat Resistance 100 parts of a novolak phenol resin and 30 parts of 2,3,4-trihydroxybenzophenone ester of naphthoquinone 1,2-diazido-5-sulfonic acid were mixed with ethyl lactate. And a resist solution was prepared. These are 0.2
The solution was filtered through a micron membrane filter to obtain a resist solution. This was applied by a conventional method 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 allowed to stand on a hot plate at a varied temperature for 30 minutes, 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 3 >> Evaluation Method of Critical Resolution In the same manner as in Evaluation Example 2, 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. The limit resolution is a visual judgment of the limit that can be resolved from a photograph under optimal exposure and development conditions.
It was measured.

[0033]

[Table 1]

[0034]

According to the present invention, it is possible to provide a phenolic resin for a photoresist having a high resolution and having both high heat resistance and high sensitivity, which cannot be obtained by the conventional method. 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 high integration of the semiconductor in the future. You.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasushi Arita 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Durez Co., Ltd. F-term (reference) 2H025 AA01 AA02 AA10 AB16 AB17 AC01 AD03 BE01 BJ10 CB29 CB55 CB56 FA03 FA17 4J033 CA02 CA03 CA12 CA29 CB03 CC03 CC08 CC09 CD03 HA02 HB10

Claims (1)

[Claims] 1. A composition comprising 30-70% by weight of meta-cresol, 1-50% by weight of para-cresol and 2,4-xylenol;
A phenol comprising 1 to 50% by weight of a monofunctional phenol comprising at least one of 2,6-xylenol and 2,3,6-trimethylphenol, formaldehyde and / or
Or, the weight average molecular weight obtained by reacting with aldehydes composed of paraformaldehyde under an acidic catalyst is 1
500-15000 phenolic resin, wherein the following (A) region is 10-45%, and (B) region is 35-85%
%, (C) area is 0-40%, and (B area + C
A phenolic resin for a photoresist, wherein an area ratio of (area) / A area is 1.2 to 4.5. However,
The total of the (A) area, (B) area and (C) area is 100
%. The (A) region is an area having a molecular weight of 150 to less than 500 (excluding free phenols),
The (B) region has an area with a molecular weight of 500 or more and less than 5000, and the (C) region has an area with a molecular weight of 5000 or more.