JP2003292557A - Resin for photoresist and photoresist composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin enabling the production of a photoresist excellent in transparency and dry etching property toward a radiation especially to such as a Kr excimer laser, as a chemically amplifying type resist and further having excellent characteristics such as resolution, sensitivity, heat resistance, wide focus margin, wide exposure margin to light, etc. <P>SOLUTION: This resin for the photoresist is obtained by protecting at least a part of hydroxy group of a novolak phenolic resin obtained by the reaction of phenols with an aldehyde in the presence of an acid catalyst, with a group eliminable by an action of an acid. The phenols are characterized by containing meta-cresol and a phenol expressed by a specific structural formula as indispensable components. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoresist resin and a photoresist compound used for lithography when manufacturing a semiconductor.

[0002]

2. Description of the Related Art Generally, for a positive photoresist, a sensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolac phenolic resin) are used. A positive photoresist having such a composition exhibits a high resolution when developed with an alkaline solution, and is used in the manufacture of semiconductors such as IC and LSI, and L
It is used to manufacture circuit patterns such as CDs. In addition, novolac type phenolic resin has high plasma dry etching property and heat resistance after exposure due to having many aromatic rings, and so far contains novolac type phenolic resin and naphthoquinonediazide type photosensitizer. Many positive photoresists have been developed with great success.

As a phenol resin for photoresist, a phenol resin obtained by reacting meta-paracresol and formaldehyde in the presence of an acid catalyst is generally used. In order to adjust or improve the characteristics of the photoresist, the ratio of meta-paracresol, the molecular weight and the molecular weight distribution have been studied and applied to lithography techniques such as semiconductors and LCDs. Photoresists for semiconductors are required to have properties such as high heat resistance, high resolution, and high sensitivity. To improve heat resistance, it is considered to use alkylphenols such as xylenol and trimethylphenol, and monomers such as aromatic aldehydes. In addition, there is an example in which hydroxybenzaldehyde and the like have been studied for higher sensitivity, but the present situation is that it does not have a sufficient effect.

In recent years, in the process of manufacturing a semiconductor integrated circuit, a photoresist material having high resolution and high sensitivity has been demanded as the circuit pattern becomes finer. As the circuit pattern becomes finer, the wavelength of light used as an exposure source needs to be shortened. For lithography applications using an excimer laser having a wavelength of 250 nm or less, polyvinylphenol resin, alicyclic acrylic resin, poly Norbornene-based resins and the like have been proposed, but at present, they do not have sufficient resist characteristics (resolution, sensitivity, etc.).

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a chemically amplified resist which is particularly excellent in transparency to radiation such as KrF excimer laser and in dry etching resistance, and further in resolution, sensitivity, heat resistance, wide focus margin, and wide exposure. It is intended to provide a resin that enables production of a photoresist having excellent characteristics such as a margin.

[0006]

Such an object is achieved by the following inventions (1) to (10). (1) A photoresist resin in which at least a part of hydroxyl groups in a novolac type phenol resin obtained by reacting a phenol and an aldehyde with each other in the presence of an acid catalyst is protected by a group capable of being eliminated by the action of an acid. The photoresist resin contains meta-cresol and the phenols represented by the general formula (I) as essential components.

[Chemical 3] R in the general formula (I)₁Is fluorine, the part having 1 to 10 carbon atoms
Or fully fluorinated alkyl groups, partially or fully fluorinated
Alkoxy group and partial or complete C3-15
It is one of fluorinated cycloalkyl groups, and l is 1 to 4
Is an integer, and when l = 2 to 4, R ₁Are the same but different
It may be. (2) As the phenols, 2,3,5-toluene is further added.
Limethylphenol and / or 3,5-xylenol
The photoresist tree according to (1) above, which includes
Fat (3) The aldehydes are represented by the general formula (II)
The photo resist according to (1) or (2) above, which is a dehydrate.
Gist resin.

[Chemical 4] In the general formula (II), R ₂ is hydrogen, an alkyl group having 1 to 10 carbon atoms, a partially or completely fluorinated alkyl group, and 3 to 1 carbon atoms.
5 is a cycloalkyl group, a partially or fully fluorinated cycloalkyl group, and a group represented by the general formula (III). In the general formula (III), R ₃ is hydrogen, fluorine, a hydroxyl group,
A partially or completely fluorinated alkyl group having 1 to 10 carbon atoms,
Partially or fully fluorinated alkoxy group and carbon number 3 to
15 is a partially or fully fluorinated cycloalkyl group, m is an integer of 1 to 5, and when m = 2 to 5,
R ₃ may be the same or different. (4) The photoresist resin according to any one of (1) to (3), wherein the aldehyde is formaldehyde and / or fluorinated benzaldehyde. (5) The group capable of leaving by the action of the acid is tert-
The photoresist resin according to any one of (1) to (4) above, which is any one of a butoxycarbonyl group, an ethoxyethyl group, a tetrahydropyranyl group, and a tert-butyl group. (6) The rate of protection of the hydroxyl groups in the novolak type phenolic resin by the groups capable of leaving by the action of the acid is 5 to 9
The resin for photoresist according to any one of (1) to (5) above, which is 0 mol%. (7) The weight average molecular weight obtained by GPC measurement is 1
The resin for photoresist according to any one of (1) to (6) above, which is 000 to 50,000. (8) 248 nm measured by UV-visible spectrophotometer
The resin for photoresist according to any one of (1) to (7) above, which has a transmittance of 20% or more. (9) A photoresist composition containing the following (X) to (Z) as essential components. (X) The photoresist resin according to any one of (1) to (8) above, (Y) a compound that generates an acid by the action of light, and (Z) (X),
A solvent that dissolves (Y) and (Z). (10) The photoresist according to (9), wherein the compound that generates an acid by the action of light (Y) is 0.5 to 5 parts by weight with respect to 100 parts by weight of the resin for photoresist (X). Composition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a photoresist resin and a photoresist composition. First,
The photoresist resin of the present invention will be described.

(X) Resin for Photoresist The resin for photoresist of the present invention comprises at least a part of hydroxyl groups in a novolac type phenol resin obtained by reacting phenols and aldehydes in the presence of an acid catalyst.
A photoresist resin protected by a group capable of being removed by the action of an acid, wherein the phenols contain meta-cresol and the phenols represented by the general formula (I) as essential components. Characterize. R in the general formula (I)
₁ is either fluorine, a partially or fully fluorinated alkyl group having 1 to 10 carbon atoms, a partially or fully fluorinated alkoxy group, and a partially or fully fluorinated cycloalkyl group having 3 to 15 carbon atoms, and l is 1 Is an integer of 4 and l = 2
In the case of ~ 4, R ₁ may be the same or different. The phenol represented by the general formula (I) is not particularly limited as long as it is within the above range, and examples thereof include 2-fluorophenol, 3-fluorophenol, 2,3-difluorophenol, 2,4-difluorophenol, 2,5
-Difluorophenol, 2,6-difluorophenol, 3,4-difluorophenol, 3,5-difluorophenol, 2,3,4-trifluorophenol,
Fluorinated phenols such as 3,4,5-trifluorophenol, or fluorinated 2-trifluoromethylphenol, 3-trifluoromethylphenol, 4-trifluoromethylphenol, 3,5-bistrifluoromethylphenol Examples thereof include alkylphenols. Among these, it is preferable to use 3,5-difluorophenol and 3,5-bistrifluoromethylphenol. As a result, when used as a photoresist, the transparency to transmitted light can be improved and high resolution can be achieved.

Further, as the phenols, those other than the phenols represented by the general formula (I) can be used in combination. Although these phenols are not particularly limited, for example, phenol, orthocresol, paracresol, 2,3-xylenol,
2,4-xylenol, 2,5-xylenol, 2,6
-Xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,4-trimethylphenol, 2,
3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,4,5-trimethylphenol,
3,4,5-Trimethylphenol, ethylphenol, propylphenol, butylphenol, octylphenol, nonylphenol, 1-naphthol, 2-
Examples include naphthol and phenylphenol. Among these, it is preferable to use 2,3,5-trimethylphenol and / or 3,5-xylenol.
This makes it possible to improve transparency and heat resistance while maintaining high sensitivity when used as a photoresist.

The blending amount of the phenols is not particularly limited, but when metacresol and the phenols represented by the general formula (I) are used,
The content of meta-cresol is preferably 50 to 95% by weight, more preferably 70 to 90% by weight. Also,
The phenol represented by the general formula (I) is 5 to 50% by weight.
Is preferable, and more preferably 10 to 30% by weight. Thereby, when used as a photoresist, high sensitivity can be obtained and transparency can be improved. Further, when 3,5-xylenol and / or 2,3,5-trimethylphenol is used together with meta-cresol and the phenol represented by the general formula (I), the content of meta-cresol is 50 to 90% by weight. Is preferable, and more preferably 60 to 80% by weight. The phenols represented by the general formula (I) are 5
It is preferably 40% by weight, more preferably 1
It is 0 to 30% by weight. And 3,5-xylenol and / or 2,3,5-trimethylphenol is 5 to 3
It is preferably 0% by weight, more preferably 10 to 20% by weight. Thereby, in addition to the above effects, heat resistance can be improved.

The aldehyde used in the photoresist resin of the present invention is not particularly limited, but the aldehyde represented by the general formula (II) is preferable.
In the general formula (II), R ₂ is hydrogen, an alkyl group having 1 to 10 carbon atoms, a partially or completely fluorinated alkyl group, and 3 to 1 carbon atoms.
5 is a cycloalkyl group, a partially or fully fluorinated cycloalkyl group, and a group represented by the general formula (III). In the general formula (III), R ₃ is hydrogen, fluorine, a hydroxyl group,
A partially or completely fluorinated alkyl group having 1 to 10 carbon atoms,
Partially or fully fluorinated alkoxy group and carbon number 3 to
It is selected from 15 partially or completely fluorinated cycloalkyl groups, m is an integer of 1 to 5, and when m = 2 to 5, R ₃ may be the same or different.

Examples of the aldehydes represented by the general formula (II) include formaldehyde, acetaldehyde,
Propyl aldehyde, butyraldehyde, etc. may be mentioned, and as the group to which the group represented by the general formula (III) is bound, for example, benzaldehyde, salicylaldehyde, 2-fluorobenzaldehyde, 3-fluorobenzaldehyde, 4-fluorobenzaldehyde, 2 , 4
Fluorinated benzaldehydes such as -difluorobenzaldehyde, 2,6-difluorobenzaldehyde, and 3,4-difluorobenzaldehyde.
Of these, formaldehyde and fluorinated benzaldehydes are preferable. Thereby, when used as a photoresist, high sensitivity can be achieved while maintaining transparency. When formaldehyde is used, the formaldehyde source is not particularly limited,
Formalin (aqueous solution), paraformaldehyde, hemiformal with alcohols, trioxane, and the like can be used as long as they generate formaldehyde.

An acid catalyst is generally used for the reaction between the phenols and the aldehydes. The acid catalyst is not particularly limited, but examples thereof include organic carboxylic acids such as oxalic acid and acetic acid, organic sulfonic acids such as benzenesulfonic acid, paratoluenesulfonic acid and methanesulfonic acid, and inorganic acids such as hydrochloric acid and sulfuric acid. Among these, it is also possible to use a single type or a mixture of two or more types.
The amount of the acid catalyst used is not particularly limited, but is preferably 0.01 to 5% by weight with respect to the phenols, and is preferably a small amount for the characteristics of the photoresist resin. Further, the reaction solvent can be used as necessary, but the kind is not particularly limited, and it dissolves the resin,
Any substance that does not contribute to the reaction can be used.

The photoresist resin of the present invention is characterized by having a structure in which at least a part of the hydroxyl groups in the novolac type phenol resin is protected by a group capable of being eliminated by the action of an acid. Here, the group capable of being eliminated by the action of an acid is stable in the absence of an acid, and is easily eliminated by an acid, and is not particularly limited, for example,
And an alkyl group, an alkoxyl carbonyl group, an acyl group, a cyclic ether group, and the like, specifically, a tert-butoxycarbonyl group, an ethoxyethyl group, a tert-butyl group, an isopropyloxyethyl group, a propyloxyethyl group, an isobutyloxyethyl group. , A butyloxyethyl group, a cyclohexyloxyethyl group, a hydroxybutoxyethyl group, a tetrahydropyranyl group, a tetrahydrofuranyl group and the like. Among these, tert
-Butoxycarbonyl group, ethoxyethyl group, tetrahydropyranyl group and tert-butyl group are preferred. Thereby, when used as a photoresist, high sensitivity can be obtained, and transparency and heat resistance are improved.

The rate of protection of the hydroxyl groups in the novolak type phenolic resin by the group capable of leaving by the action of the acid is not particularly limited, but is preferably 10 to 90 mol%, more preferably 15 to 50 mol. %.
When the protection rate is lower than the lower limit value, the transparency to irradiation light is lowered and the protective layer tends to be dissolved in an alkaline aqueous solution, so that the residual film property tends to be lowered. On the other hand, when the amount is higher than the upper limit, although the transparency to the irradiation light and the residual film property are good, the sensitivity of the photoresist may be lowered and the softening point of the resin may be lowered to lower the heat resistance.
The protection rate may be selected within a preferable range depending on the characteristics of the group used. For example, tert-butyl group, ter
When a t-butoxycarbonyl group is used, these protecting groups are deprotected by a strong acid, and thus the heat resistance tends not to decrease even if the protection rate is high. Also,
When an ethoxyethyl group is used, it is deprotected by a weak acid. To maintain the heat resistance and suppress the change in pattern shape from exposure to heat treatment, lower the protection rate. Is preferred. The protection rate by the group capable of being removed by an acid is determined by using, for example, a thermogravimetric analyzer (TG-DTA6300 manufactured by SEIKO Denshi), and from the obtained results, the weight reduction corresponding to each substituent removable by an acid is obtained. Can be calculated. As the measurement conditions, the temperature rising rate is 10 ° C /
min, under a nitrogen atmosphere.

The compound used for protecting the hydroxyl group in the novolak type phenolic resin with a group capable of being removed by an acid is not particularly limited. For example, when a tert-butoxycarbonyl group is introduced as a protecting group, a -Tert-butyl dicarbonate, likewise ethyl vinyl ether when an ethoxyethyl group is introduced,
When introducing a tetrahydropyranyl group, 3,4 dihydro-2H-pyran or the like can be used.

The molecular weight of the photoresist resin of the present invention is not particularly limited, but the weight average molecular weight (Mw) measured by GPC is preferably 1,000 to 50,000, more preferably 2,000 to 30,000. This makes it possible to obtain a resin having a good balance of resist properties such as alkali solubility and heat resistance. If the weight average molecular weight is less than the lower limit, the heat resistance may decrease, and if it exceeds the upper limit, the sensitivity of the photoresist resin may be insufficient. The method for controlling the weight average molecular weight is not particularly limited, but it is preferable to adjust the reaction molar ratio (F / P) of the aldehydes (F) to the phenols (P). In the case of producing a photoresist resin having the above-mentioned weight average molecular weight, the reaction molar ratio is preferably 0.5 to 1.5, more preferably 0.7 to 1.2. Thereby, the weight average molecular weight of the obtained resin can be made appropriate, and the alkali solubility and heat resistance of the resin can be made preferable.

The weight average molecular weight is 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 4
It was carried out under the condition of 0 ° C. Body: TOSOH HLC-8
020, detector: TOSO set to a wavelength of 280 nm
UV-8011 manufactured by H, analytical column: SHO manufactured by Showa Denko
DEX KF-802, KF-803 and KF-805 were used, respectively.

The photoresist resin of the present invention is not particularly limited, but it is measured by an ultraviolet-visible spectrophotometer 24.
The transmittance at 8 nm is preferably 20% or more. More preferably, it is 40% or more. Thereby, a good pattern can be drawn when used as a photoresist. When the transmittance is smaller than the lower limit value, when it is used as a photoresist, it has a K value as a light source.
When rF is used, the transparency may be reduced, the sensitivity may be reduced, and pattern formation may be insufficient.

The transmittance is measured by using, for example, a UV spectrophotometer (U-2000 manufactured by Hitachi, Ltd.), and the wavelength is 248 n.
It can be evaluated by measuring the transmittance for light of m. A sample for evaluation was prepared by applying a resin solution dissolved in a solvent on quartz glass by a spin coater,
Desolventize for 100 seconds on a 0 ° C hot plate,
It can be prepared by forming a resin film on quartz glass so as to have a thickness of about 0.5 μm.

Next, the procedure for synthesizing the photoresist resin of the present invention will be described. The synthesis method described below is an example, and the present invention is not particularly limited to this. First, a novolac type phenol resin is synthesized. The synthesis can be performed by charging a reaction vessel equipped with a stirrer, a thermometer, and a heat exchanger with phenols and aldehydes and adding an acid catalyst. In the above reaction, the reaction temperature and time may be appropriately set depending on the reactivity of the above-mentioned raw materials, but the reaction time is set to 2 for stable and economical synthesis.
The reaction temperature is preferably 70 to 150 ° C. for 10 hours. If necessary, a reaction solvent can be used. The type of solvent is not particularly limited, but a solvent that dissolves the resin obtained by the reaction, such as ethyl cellosolve and methyl ethyl ketone, is preferable.

After completion of the above reaction, for example, a basic compound may be added for neutralization to remove the acid catalyst, and the neutralized salt may be removed by washing with water. The amount and number of times of washing water is not particularly limited, but the number of times of washing is 1 to 1 from the economical point of view of removing the neutralized salt in the resin to a level at which there is substantially no effect.
About 5 times is preferable. The washing temperature is not particularly limited, but is 40 to 9 from the viewpoint of neutralizing salt removal efficiency and workability.
It is preferably carried out at 5 ° C.

After completion of the above reaction or washing with water, dehydration / demonomer is carried out under normal pressure and / or reduced pressure. The degree of reduced pressure for dehydration / demonomer is not particularly limited, but 0.1 to
It is preferably about rr to 200 torr. The temperature for taking out from the reaction vessel after dehydration / demonomer is not particularly limited, but can be appropriately set depending on the characteristics and viscosity of the resin. From the viewpoint of resin stability, 150 to 250 ° C is preferable. In this way, the novolac type phenolic resin which is the base of the photoresist resin of the present invention is obtained.

Next, a method for producing a photoresist resin from the novolac resin will be described. A part or all of the hydroxyl groups in the novolak type phenolic resin obtained by the above method are protected with a group capable of being removed by an acid. The photoresist resin thus obtained is capable of easily releasing the protective group by the action of an acid to form a free hydroxyl group, whereby an alkali developing solution is formed between the protective group and a portion where deprotection has not occurred. A resist function is imparted by causing a difference in solubility with respect to. The method of protecting the hydroxyl group in the novolak type phenolic resin with an acid eliminable group is not particularly limited because the starting material and method used differ depending on the acid eliminable group, but for example tert-butoxycarbonyl In the case of protecting with a group, a predetermined amount of di-tert-butyldicarbonate may be added to the above novolac type phenolic resin, and the reaction may be carried out for a predetermined time in the presence of a basic compound for substitution. Further, in the case of protecting with an ethoxyethyl group or a tetrahydropyranyl group, ethyl vinyl ether or dihydropyran can be substituted by reacting for a predetermined time in the presence of an acidic catalyst.

In the synthesis, the material of the equipment such as the reaction vessel is not particularly limited, but from the viewpoint of mixing of impurities, glass lining, Teflon (R), or a metal selected from tantalum, hafnium, zirconium, niobium, and titanium. It is desirable to use a manufacturing apparatus using as a reactor material a metallic material that is made of such alloys and is substantially free of other materials and is resistant to corrosion.

Next, the photoresist composition of the present invention (hereinafter referred to as "composition") will be described. The composition of the present invention comprises the photoresist resin, a compound that generates an acid by the action of light (hereinafter, referred to as “photoacid generator”), and a solvent that dissolves the photoresist resin and the photoacid generator ( Hereinafter, it will be referred to as a "solvent") as an essential component. When the composition of the present invention is used as a photoresist, the photoacid generator generates an acid upon irradiation with light, and the action of this acid causes a deprotection reaction in the polymer. The polymer of the deprotected portion is dissolved in an alkaline developing solution in the subsequent development step, and a clear difference in dissolution rate is generated between the polymer of the portion where the deprotection reaction has not occurred and the target pattern. Can be obtained by development.

(Y) Photo-acid generator The photo-acid generator used in the composition of the present invention is not particularly limited, but a sulfonium salt derivative [sulfonic acid ester (1,2,3-tri (methylsulfonyloxy) benzene] is used. Aryl alkane sulfonates such as C
_6-10 aryl C _1-2 alkane sulfonates); 2,6
Dinitrobenzyltoluene sulfonate, benzoin tosylate nadnoarylbenzene sulfonate (particularly C _6-10 aryltoluene phosphonate optionally having a benzoyl group); 2-benzoyl-2-hydroxy-2
Aralkylbenzene sulfonates such as phenylethyltoluene sulfonate (especially C _6-10 aryl-C _1-4 alkyltoluene sulfonate _optionally having a benzoyl group); disulfonic acid such as diphenyldisulfone; Lewis acid salt (triphenyl Sulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimony, triphenylsulfonium methanesulfonyl and other triarylsulfonium salts (especially triphenylsulfonium salts), etc.)], phosphonium salt derivatives, diarylhalonium salt derivatives [diaryliodonium salts ( Lewis acid salts such as diphenyliodonium hexafluorophosphate, etc.], diazonium salt derivatives (p-nitrophenyldiazonium hexafluorophosphate, etc.) Lewis, etc. salts), such as, diazomethane derivatives, triazine derivatives can be exemplified. In particular, Lewis acid salts (Lewis acid salts such as phosphonium salts) are preferable.

The blending amount of the photo-acid generator is not particularly limited, but it is preferably 0.5 to 5 parts by weight, more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the polymer. This improves the sensitivity and resolution of the composition. If the blending amount of the photo-acid generator is less than the lower limit value described above, the deprotection reaction of the polymer is difficult to proceed, so that an image may not be sufficiently formed. On the other hand, if the upper limit is exceeded, the deprotection reaction will proceed rapidly, and the polymer will be more likely to dissolve during development, making it difficult to form an image, and the melting point of the polymer containing the photoacid generator will be low. Therefore, the heat resistance may decrease.

(Z) Solvent The solvent to be added to the composition of the present invention is not particularly limited as long as it dissolves the polymer and the photo-acid generator, but water, alcohols, glycols, cellosolves. ,
Examples thereof include ketones, esters, ethers, amides #, and hydrocarbons. Specifically, propylene glycol monomethyl ether acetate (PGME
A), propylene glycol monoethyl ether acetate, ethyl cellosolve acetate, methyl cellosolve acetate, butyl cellosolve acetate, methoxyethyl propionate, ethoxyethyl propionate,
Examples thereof include methyl lactate, ethyl lactate, butyl lactate, ethyl acetate, butyl acetate, methyl isobutyl ketone, and methyl pentyl ketone. Among these, PGMEA, ethoxyethyl propionate, and ethyl lactate are particularly preferable from the viewpoints of solubility, coating film stability, safety, environmental impact, human impact, and economic efficiency. These are alone or 2
Used as a mixture of two or more species.

In the composition of the present invention, in addition to the components described above, if necessary, stabilizers such as antioxidants, plasticizers, surfactants, adhesion improvers, dissolution accelerators, etc. Various additives may be used.

[0031]

EXAMPLES The present invention will be described in detail below with reference to examples.
All "parts" and "%" described herein represent "parts by weight" and "% by weight", and the present invention is not limited to these examples.

(1) Synthesis of novolac type phenol resin Synthesis example 1 In a 5 L four-necked flask equipped with a stirrer, thermometer and heat exchanger, 1296 parts of metacresol, 324 parts of 3,5-difluorophenol, 43% formalin. Charge 970 parts, 162 parts of ethyl cellosolve, 3.24 parts of oxalic acid, 98
After reacting at 102 ° C for 4 hours, 162 parts of ethyl cellosolve was further added to dehydrate the mixture to an internal temperature of 170 ° C under normal pressure, and further dehydrated and demonomerized under reduced pressure of 80 torr to 200 ° C to obtain a phenol resin. 1650 parts were obtained. The obtained resin had a weight average molecular weight of 7325 and a free monomer content of 1.5%.

Synthesis Example 2 1296 parts of metacresol, 324 parts of 3,5-bistrifluoromethylphenol, and 43% formalin 98 were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger.
0 parts, 162 parts of ethyl cellosolve and 3.24 parts of oxalic acid were charged, and after reacting at 98 to 102 ° C. for 4 hours, 162 parts of ethyl cellosolve were further added to dehydrate the mixture to an internal temperature of 170 ° C. under normal pressure, and further. 200 under reduced pressure of 80 torr
Dehydrated and demonomerized to ℃, phenol resin 161
I got 0 copies. The weight average molecular weight of the obtained resin is 731.
0, 1.2% of free monomer.

Synthesis Example 3 1134 parts of metacresol, 324 parts of 3,5-difluorophenol, 162 parts of 2,3,5-trimethylphenol, 43% in a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger. Charge 98 parts of formalin, 162 parts of ethyl cellosolve and 3.24 parts of oxalic acid, and 98 to 102 ° C.
After reacting for 4 hours at room temperature, ethyl cellosolve 16 was added.
Two parts were added and dehydration was carried out at an inner temperature of 170 ° C. under normal pressure, and further dehydration / demonomer was carried out under a reduced pressure of 80 torr to 200 ° C. to obtain 1580 parts of a phenol resin. The weight average molecular weight of the obtained resin was 7222, and the free monomer was 1.
It was 2%.

Synthesis Example 4 1324 parts of metacresol, 162 parts of 3,5-bistrifluoromethylphenol, 162 parts of 2,3,5-trimethylphenol were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger. 43% formalin 984 parts, ethyl cellosolve 162 parts, and oxalic acid 3.24 parts were charged, and 98
After reacting at 102 ° C for 4 hours, 162 parts of ethyl cellosolve was further added to dehydrate the mixture to an internal temperature of 170 ° C under normal pressure, and further dehydrated and demonomerized under reduced pressure of 80 torr to 200 ° C to obtain a phenol resin. 1655 parts were obtained. The weight average molecular weight of the obtained resin was 7520, and the free monomer was 1.0%.

Synthesis Example 5 Meta-cresol 972 parts, 3,5-difluorophenol 324 parts, 3,5-xylenol 324 parts, 43 in a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger.
% Formalin 992 parts, ethyl cellosolve 162 parts, and oxalic acid 3.24 parts were charged, and after reacting at 98 to 102 ° C. for 4 hours, 162 parts of ethyl cellosolve was further added, and dehydration was performed under an atmospheric pressure to an internal temperature of 170 ° C. , 80 torr
The mixture was dehydrated and demonomerized under reduced pressure up to 200 ° C to obtain 1588 parts of a phenol resin. The obtained resin had a weight average molecular weight of 7111 and a free monomer of 1.2%.

Synthesis Example 6 1134 parts of metacresol, 324 parts of 3,5-bistrifluoromethylphenol, 162 parts of 3,5-xylenol, 43% formalin were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger. Charge 950 parts, 162 parts of ethyl cellosolve, 3.24 parts of oxalic acid, and 98 to 102 ° C.
After reacting for 4 hours at room temperature, ethyl cellosolve 16 was added.
Two parts were added and dehydration was carried out at an internal temperature of 170 ° C. under normal pressure, and further dehydration / demonomer was carried out under a reduced pressure of 80 torr to 200 ° C. to obtain 1589 parts of a phenol resin. The obtained resin has a weight average molecular weight of 7321 and a free monomer of 1.
It was 1%.

Synthesis Example 7 1458 parts of metacresol, 162 parts of 3,5-difluorophenol, 967 parts of 43% formalin, 162 parts of ethyl cellosolve, 3 parts of oxalic acid were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger. .24 parts charged, 98-
After reacting at 102 ° C. for 4 hours, 162 parts of ethyl cellosolve was further added to dehydrate to an internal temperature of 170 ° C. under normal pressure, and further to 200 ° C. under a reduced pressure of 80 torr.
Demonomerization was performed to obtain 1601 parts of a phenol resin.
The obtained resin had a weight average molecular weight of 7225 and a free monomer content of 1.0%.

Synthesis Example 8 972 parts of meta-cresol, 648 parts of 3,5-difluorophenol, 976 parts of 43% formalin, 162 parts of ethyl cellosolve, and oxalic acid 3 were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger. .24 parts charged, 98-1
After reacting at 02 ° C for 4 hours, 162 parts of ethyl cellosolve was further added to dehydrate the mixture to an internal temperature of 170 ° C under normal pressure, and further dehydrated to 200 ° C under a reduced pressure of 80 torr.
Demonomerization was performed to obtain 1612 parts of a phenol resin.
The weight average molecular weight of the obtained resin was 7530, and the free monomer was 1.3%.

Synthesis Example 9 Metacresol 1458 parts, 3,5-difluorophenol 81 parts, and 2,3,5-trimethylphenol 8 were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger.
1 part, 43% formalin 985 parts, ethyl cellosolve 1
62 parts and 3.24 parts of oxalic acid were charged, and 4 at 98-102 ° C
After reacting for a period of time, 162 parts of ethyl cellosolve was further added, and dehydration was carried out at an internal temperature of 170 ° C. under normal pressure.
Dehydration and demonomerization were performed up to 200 ° C. under reduced pressure of 0 torr to obtain 1620 parts of a phenol resin. The obtained resin has a weight average molecular weight of 7305 and free monomer is 1.1%.
Met.

Synthesis Example 10 810 parts of meta-cresol, 648 parts of 3,5-difluorophenol, and 648 parts of 2,3,5-trimethylphenol were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger.
2 parts, 43% formalin 954 parts, ethyl cellosolve 1
62 parts and 3.24 parts of oxalic acid were charged, and 4 at 98-102 ° C
After reacting for a period of time, 162 parts of ethyl cellosolve was further added, and dehydration was carried out at an internal temperature of 170 ° C. under normal pressure.
It was dehydrated and demonomerized under reduced pressure of 0 torr to 200 ° C. to obtain 1642 parts of a phenol resin. The weight average molecular weight of the obtained resin was 7555, and the free monomer was 1.4%.
Met.

Synthesis Example 11 Metacresol 1134 parts, 3,5-difluorophenol 324 parts, 2,3,5-trimethylphenol 162 parts, 43% in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger. Formalin 930 parts, 2-fluorobenzaldehyde 232 parts, ethyl cellosolve 162 parts,
After charging 3.24 parts of oxalic acid and carrying out a reaction at 98 to 102 ° C. for 4 hours, 162 parts of ethyl cellosolve were further added, and dehydration was carried out under atmospheric pressure to an internal temperature of 170 ° C., and further 80 torr
The mixture was dehydrated and demonomerized under reduced pressure of r to 200 ° C. to obtain 1600 parts of a phenol resin. The obtained resin had a weight average molecular weight of 7420 and a free monomer content of 1.4%.

Synthesis Example 12 1134 parts of metacresol, 324 parts of 3,5-difluorophenol, 162 parts of 2,3,5-trimethylphenol, 43% in a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger. Charge 930 parts formalin, 162 parts ethyl cellosolve, 3.24 parts oxalic acid, 98-102 ° C
After reacting for 4 hours at room temperature, ethyl cellosolve 16 was added.
Two parts were added and dehydrated to an internal temperature of 170 ° C. under normal pressure, and further dehydrated and demonomerized to 200 ° C. under reduced pressure of 80 torr to obtain 1610 g of a phenol resin. The obtained resin has a weight average molecular weight of 3288 and a free monomer of 1.
It was 6%.

Synthesis Example 13 1324 parts of metacresol, 162 parts of 3,5-difluorophenol, and 2,3,5-trimethylphenol 1 were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger.
62 parts, 1160 parts of 43% formalin, 162 parts of ethyl cellosolve, 3.24 parts of oxalic acid were charged, and 98 to 102 ° C.
After reacting for 4 hours at room temperature, ethyl cellosolve 16 was added.
Two parts were added and dehydration was carried out at an internal temperature of 170 ° C. under normal pressure, and further dehydration / demonomer was carried out under reduced pressure of 80 torr to 200 ° C. to obtain 1602 parts of a phenol resin. The obtained resin had a weight average molecular weight of 22272 and a free monomer of 1.1%.

Synthesis Example 14 1620 parts of metacresol and 43% formalin 94 were placed in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger.
2 parts, 162 parts of ethyl cellosolve and 3.24 parts of oxalic acid were charged, and after reacting at 98 to 102 ° C. for 4 hours, 162 parts of ethyl cellosolve was further added to dehydrate the mixture to an internal temperature of 170 ° C. under normal pressure, and further. 200 under reduced pressure of 80 torr
Dehydrated and demonomerized to ℃, phenol resin 158
9 parts were obtained. The weight average molecular weight of the obtained resin was 710.
2. Free monomer was 1.5%.

Synthesis Example 15 In a 5 L four-necked flask equipped with a stirrer, a thermometer and a heat exchanger, 1296 parts of metacresol, 324 parts of 2,3,5-trimethylphenol, 952 parts of 43% formalin, 162 parts of ethyl cellosolve, Charge 3.24 parts of oxalic acid, 98
After reacting at 102 ° C for 4 hours, 162 parts of ethyl cellosolve was further added to dehydrate the mixture to an internal temperature of 170 ° C under normal pressure, and further dehydrated and demonomerized under reduced pressure of 80 torr to 200 ° C to obtain a phenol resin. 1598 parts were obtained. The obtained resin had a weight average molecular weight of 7145 and a free monomer of 1.2%.

Synthesis Example 16 1296 parts of metacresol, 324 parts of 3,5-xylenol, 942 parts of 43% formalin, 162 parts of ethyl cellosolve, and oxalic acid in a 5 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger. Charge 24 parts, 98-102 ° C
After reacting for 4 hours at room temperature, ethyl cellosolve 16 was added.
Two parts were added and dehydrated to an internal temperature of 170 ° C. under normal pressure, and further dehydrated and demonomerized to 200 ° C. under a reduced pressure of 80 torr to obtain 1640 parts of a phenol resin. The weight average molecular weight of the obtained resin was 7628, and the free monomer was 1.
It was 2%.

2. Synthesis of Resin for Photoresist (Examples 1 to 29, Comparative Examples 1 to 3) (1) Introduction of tert-butoxycarbonyl group Synthesis Example 1 in a flask equipped with a stirrer, thermometer, and heat exchanger.
~ 6, 11-13 and 16 to the tetrahydrofuran solution of the resin, di-tert-butyl dicarbonate and triethylamine are added in appropriate amounts, and the mixture is reacted at 60 ° C for 6 hours and then neutralized with acetic acid. went. After ion-exchanged water was added and washing with water was performed, the solvent was removed to obtain a photoresist resin as shown in Table 2. (2) Introduction of ethoxyethyl group Synthesis Example 1 in a flask equipped with a stirrer, thermometer, heat exchanger
To a tetrahydrofuran solution of the resin obtained in ~ 15, ethyl vinyl ether was added in an appropriate amount, a catalytic amount of paratoluenesulfonic acid was added, and the mixture was reacted at 40 ° C for 4 hours, and then neutralized with triethylamine. . After washing with ion-exchanged water, the solvent was removed to obtain a photoresist resin as shown in Table 2. (3) Introduction of tetrahydropyranyl group Synthesis Example 3 in a flask equipped with a stirrer, thermometer, and heat exchanger.
An appropriate amount of 3,4-dihydro-2H-pyran was added to the tetrahydrofuran solution of the resin obtained in step 1, a catalytic amount of paratoluenesulfonic acid was added, and the mixture was reacted at 40 ° C. for 4 hours, and then triethylamine was added to the intermediate solution. I went to sum. After washing with ion-exchanged water, the solvent was removed to obtain a photoresist resin as shown in Table 2.

3. Evaluation of Photoresin Resin The photoresist resins obtained in Examples 1 to 29 and Comparative Examples 1 to 3 were evaluated as follows. (1) Protection rate thermogravimetric analyzer (TG-DTA630 manufactured by SEIKO Denshi)
0) was used and calculated from the results obtained by the weight loss corresponding to each substituent removable by acid. As the measurement conditions, the heating rate was 10 ° C./min and the measurement was performed in a nitrogen atmosphere. (2) Transmittance 3 g of a photoresist resin was dissolved in 9 g of ethyl cellosolve, filtered through a 0.2 μm PTFE filter, and then applied onto quartz glass using a spin coater. The film was baked on a hot plate at 90 ° C. for 60 seconds to form a film having a thickness of about 0.5 μm. The absorption spectrum of this film was measured to evaluate the transmittance at 248 nm. (3) Weight average molecular weight (Mw) The weight average molecular weight (Mw) was 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 4
It was carried out under the condition of 0 ° C. Body: TOSOH HLC-8
020, detector: TOSO set to a wavelength of 280 nm
UV-8011 manufactured by H, analytical column: SHO manufactured by Showa Denko
DEX KF-802, KF-803 and KF-805 were used, respectively.

4. Preparation of Photoresist Compositions As shown in Table 3, Examples 1-29 and Comparative Examples 1-3
A part of the photoresist resin obtained in 1. was dissolved in propylene glycol monomethyl ether acetate to prepare a 15% resin solution, and a photo-acid generator (Midori Kagaku DAM-301 and TPS-105) was prepared. After the addition of the amount shown in No. 3, it was filtered using a 0.2 μm PTFE (polytetrafluoroethylene) filter to obtain a photoresist composition.

5. Evaluation of Photoresist Compositions (Examples 101 to 119, Comparative Examples 101 to 103) (1) Sensitivity (E _OP ) The prepared photoresist composition was applied on a silicon substrate using a spin coater, and 90 ° C. Then, pre-baking was performed for 60 seconds to form a resist film having a film thickness of 0.5 μm. After that, UVES-2000 manufactured by Litho Tech Japan
With a KrF excimer laser at different exposure levels of 18 levels, and then 110 on a hot plate.
Post baking (PEB) was performed at 90 ° C. for 90 seconds. Then, measure the film thickness of each exposed portion with a film thickness measuring device, using RDA-790 manufactured by Lithotec Japan,
Development was performed using a 2.38% tetramethylammonium hydroxide aqueous solution, and the amount of reduction in film thickness and the speed were measured. Leap Set and Pro based on measurement results
Using the simulation software of lith2, the exposure amount that can form a line-and-space pattern with a line width of 0.18 μm (the ratio of line to space is 1: 1) with a line width of 1: 1 is the sensitivity (E _OP ). (2) Focus margin When the focus position is moved up and down, the line width is 0.18 μm when PEB and development are performed by exposure with the minimum exposure amount that reproduces a line and space pattern with a line width of 0.18 μm.
The range of acceptable focus that can reproduce a line and space pattern of m was measured. (3) Critical resolution The resolution is defined as the minimum size of the photoresist pattern that is resolved when exposed with an exposure amount corresponding to the sensitivity obtained in (1). (4) tan θ Discrimination curve (discrimina) in which the horizontal axis shows the exposure amount (mJ / cm ² ) and the vertical axis shows the alkaline dissolution rate (nm / s) of the composition
tion curve) was created. The slope near the inflection point of this curve is represented by tangent (tan θ).

The novolak type phenolic resins of Synthesis Examples 1 to 16 are shown in Table 1, the photoresist resin is shown in Table 2, and the photoresist composition is shown in Table 3.

[0053]

[Table 1]

[Table 2]

[Table 3]

Examples 1 to 29 are photoresist resins of the present invention. And Examples 101-108 and 1
Nos. 18 to 119 are photoresist compositions using a resin having an ethoxyethyl group introduced as a protective group among the photoresist resins, and Comparative Examples 101 to 102 (novolac-type phenol resin, which is different from the examples). It was excellent in sensitivity and resolution, and had a sufficient focus margin, as compared with those in which an ethoxyethyl group was similarly introduced using the same type). Moreover, Example 109-
Similarly, 116 is a photoresist composition using a resin into which a tert-butoxycarbonyl group was introduced as a protecting group, and similar results to Comparative Example 103 were obtained.
Then, Example 117 is a photoresist composition using a resin into which a tetrahydropyranyl group was introduced as a protective group, and also with respect to this, the same good characteristics as described above were obtained.

[0055]

INDUSTRIAL APPLICABILITY According to the present invention, at least a part of hydroxyl groups in a novolak type phenol resin obtained by reacting a specific phenol and an aldehyde in the presence of an acid catalyst can be eliminated by the action of an acid. A resin for photoresist protected by a base, and a chemically amplified photoresist composition using the same was excellent in resolution and sensitivity and had a wide focus margin. Therefore, the present invention is particularly applicable to KrF.
It is useful for lithography applications using excimer lasers, and can be expected to have a cost reduction effect because it can be produced more easily and cheaply than currently used polyhydroxystyrene.

Continued front page    F term (reference) 2H025 AA01 AA02 AA10 AC04 AC08                       AD03 BE00 BG00 FA03 FA12                       FA17                 4J033 CA02 CA05 CA12 CA26 CA29                       CA32 CA36 HB10

Claims (10)

[Claims] 1. An acid catalyst comprising phenols and aldehydes.
Novolac-type phenolic tree obtained by reaction in the presence of
At least some of the hydroxyl groups in fat are eliminated by the action of acid.
A photoresist resin protected by a possible group,
The phenols are represented by meta-cresol and the general formula (I).
That contains phenols that are used as essential ingredients
Characteristic resin for photoresist. [Chemical 1] R in the general formula (I)₁Is fluorine, the part having 1 to 10 carbon atoms
Or fully fluorinated alkyl groups, partially or fully fluorinated
Alkoxy group and partial or complete C3-15
It is one of fluorinated cycloalkyl groups, and l is 1 to 4
Is an integer, and when l = 2 to 4, R ₁Are the same but different
It may be. 2. Further, as the phenols, 2,
The photoresist resin according to claim 1, which contains 3,5-trimethylphenol and / or 3,5-xylenol. 3. The resin for photoresist according to claim 1, wherein the aldehyde is an aldehyde represented by the general formula (II). [Chemical 2] In the general formula (II), R ₂ is hydrogen, an alkyl group having 1 to 10 carbon atoms, a partially or completely fluorinated alkyl group, and 3 to 1 carbon atoms.
5 is a cycloalkyl group, a partially or fully fluorinated cycloalkyl group, and a group represented by the general formula (III). In the general formula (III), R ₃ is hydrogen, fluorine, a hydroxyl group,
A partially or completely fluorinated alkyl group having 1 to 10 carbon atoms,
Partially or fully fluorinated alkoxy group and carbon number 3 to
15 is a partially or fully fluorinated cycloalkyl group, m is an integer of 1 to 5, and when m = 2 to 5,
R ₃ may be the same or different. 4. The aldehydes are formaldehyde and / or fluorinated benzaldehydes.
4. The photoresist resin according to any one of 3 to 3. 5. The group capable of leaving by the action of the acid is t
The photoresist resin according to any one of claims 1 to 4, which is one of an ert-butoxycarbonyl group, an ethoxyethyl group, a tetrahydropyranyl group, and a tert-butyl group. 6. The photoresist according to claim 1, wherein the protection rate of the hydroxyl group in the novolac type phenolic resin by the group capable of leaving by the action of the acid is 5 to 90 mol%. resin. 7. The photoresist resin according to claim 1, wherein the weight average molecular weight obtained by GPC measurement is 1000 to 50,000. 8. Measured by an ultraviolet-visible spectrophotometer 2.
The transmittance at 48 nm is 20% or more.
8. The photoresist resin according to any one of 1 to 7. 9. A photoresist composition containing the following (X) to (Z) as essential components. (X) Claims 1 to 8
The photoresist resin according to any one of (1) to (4), (Y) a compound that generates an acid by the action of light, and (Z) (X),
A solvent that dissolves (Y) and (Z). 10. The photo according to claim 9, wherein the compound (Y) which generates an acid by the action of light is 0.5 to 5 parts by weight with respect to 100 parts by weight of the resin (X) for photoresist. Resist composition.