JP2006208658A - Photoresist composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoresist composition having superior features, such as sensitivity, resolution and heat resistance, in the lithographic processes in the manufacturing an electrode pattern of a semiconductor or a flat panel display. <P>SOLUTION: The photoresist composition contains, as an essential component, a novolac resin prepared by reacting a hydroxynaphthalene compound expressed by general Formula (I) with an aldehyde compound in the presence of an acidic catalyst, wherein a part or all of hydroxyl groups in the resin are protected by alkoxy alkyl groups. In Formula (I), m represents an integer of 1 to 2 and n represents an integer of 0 to 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photoresist composition used for lithography in manufacturing electrode patterns of semiconductors and thin panel displays using radiation such as g-line and i-line.

  In general, a positive photoresist uses a photosensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolac-type phenolic resin). A positive photoresist having such a composition exhibits high resolving power when developed with an alkaline solution, and is used for manufacturing semiconductors such as IC and LSI, and circuit patterns such as LCD. In addition, novolak type phenolic resin has high post-exposure plasma dry etching property and heat resistance caused by having a large number of aromatic rings, and so far contains novolac type phenolic resin and naphthoquinone diazide photosensitizer. Many positive photoresists have been developed and put to practical use, and have achieved great results in line width processing up to about 2.0 to 0.3 μm (for example, see Patent Documents 1 and 2).

  However, in recent years, in the manufacturing process of a semiconductor integrated circuit, a photoresist material having high resolution, high sensitivity, and heat resistance of a resist pattern has been demanded as the circuit pattern becomes finer.

Japanese Patent Laid-Open No. 11-349653 JP 05-142770 A

  The present invention provides a photoresist composition having high resolution and high sensitivity and excellent heat resistance when formed into a resist pattern.

一般式（Ｉ）中、ｍは１〜２の整数、ｎは０〜１の整数を示す。
（２） 前記ヒドロキシナフタレン化合物が、下記化学式（ＩＩ）で表される化合物である前記（１）に記載のフォトレジスト組成物。

（３） 前記酸の作用により脱離可能な基が、ｔｅｒｔ−ブトキシカルボニル基、エトキシエチル基、テトラヒドロピラニル基、及びｔｅｒｔ−ブチル基のいずれかである前記（１）または（２）に記載のフォトレジスト組成物。
（４） 前記酸の作用により脱離可能な基による前記ノボラック樹脂中の水酸基の保護率が、５〜９０モル％である前記（１）ないし（３）のいずれかに記載のフォトレジスト組成物。 Such an object is achieved by the following present inventions (1) to (4).
(1) A novolak resin obtained by reacting a hydroxynaphthalene compound represented by the following general formula (I) with an aldehyde compound under an acidic catalyst, wherein a part or all of the hydroxyl groups in the resin are removed by the action of an acid. A photoresist composition comprising a novolak resin protected with a separable group as an essential component.

In general formula (I), m represents an integer of 1 to 2, and n represents an integer of 0 to 1.
(2) The photoresist composition according to (1), wherein the hydroxynaphthalene compound is a compound represented by the following chemical formula (II).

(3) The group which can be eliminated by the action of the acid is any one of a tert-butoxycarbonyl group, an ethoxyethyl group, a tetrahydropyranyl group and a tert-butyl group, as described in (1) or (2) above Photoresist composition.
(4) The photoresist composition according to any one of (1) to (3), wherein a protection rate of a hydroxyl group in the novolak resin by a group removable by the action of an acid is 5 to 90 mol%. .

  As described above, the present invention is a novolak resin obtained by reacting a hydroxynaphthalene compound having a specific structure with an aldehyde compound in the presence of an acidic catalyst, and a part or all of the hydroxyl groups in the resin are eliminated by the action of an acid. A photoresist composition containing a novolak resin protected with a possible group (hereinafter referred to as an acid dissociable group) as an essential component, and has a resolution, sensitivity, heat resistance and wide focus as a chemically amplified resist. The present invention provides a photoresist composition that enables the production of a photoresist having excellent features such as a margin and a wide exposure margin.

In the photoresist composition of the present invention (hereinafter sometimes simply referred to as “composition”), the novolak resin to be blended contains a hydroxynaphthalene compound represented by the following general formula (I) as a phenol source, and A part or all of the hydroxyl groups in the novolak resin are protected with an acid-dissociable group.
First, in the present invention, a hydroxynaphthalene compound that is a phenol source of the novolak resin will be described.

一般式（Ｉ）中、ｍは１〜２の整数、ｎは０〜１の整数を示す。
ナフタレン骨格に水酸基をもつ化合物がβ−ナフトールで、ベンゼン環にアルデヒド基をもつ化合物がベンズアルデヒドの場合、下記化学式（ＩＩ）で表されるヒドロキシナフタレン化合物が得られる。この場合、特に副生成物の発生が少なく高収率で所望のヒドロキシナフタレン化合物が得られるため経済的に有利となる。

The hydroxy naphthalene compound represented by the general formula (I) is obtained by reacting a compound having a hydroxyl group with a naphthalene skeleton and an aromatic aldehyde compound having an aldehyde group on a benzene ring. When used, the hydroxynaphthalene compound of the present invention can be obtained in a high yield with little generation of by-products.

In general formula (I), m represents an integer of 1 to 2, and n represents an integer of 0 to 1.
When the compound having a hydroxyl group on the naphthalene skeleton is β-naphthol and the compound having an aldehyde group on the benzene ring is benzaldehyde, a hydroxynaphthalene compound represented by the following chemical formula (II) is obtained. In this case, since a desired hydroxy naphthalene compound is obtained in a high yield with little generation of by-products, it is economically advantageous.

In the photoresist composition of the present invention, the novolak resin protected with an acid-dissociable group using the hydroxy naphthalene compound as a phenol source contains a naphthalene skeleton in its structure, so that the photoresist used in the photoresist composition is used. Compared to the novolac type phenolic resin protected with a general acid-dissociable group used in resist compositions, resolution and heat resistance are not reduced, and the balance of resist properties such as sensitivity, resolution and heat resistance is achieved. An excellent photoresist composition can be obtained.

一般式（ＩＩＩ）中、ｍは１〜２の整数を示す。

一般式（ＩＶ）中、ｎは０〜１の整数を示す。 Next, the manufacturing method of the said hydroxy naphthalene compound is demonstrated.
The aromatic aldehyde compound represented by the general formula (IV) is added in the range of 0.5 mol to 1.5 mol with respect to 1 mol of the compound having a hydroxyl group on the naphthalene skeleton represented by the general formula (III), Add solvent if necessary. A basic catalyst is added to this system in a range of 0.2 mol or more and 0.8 mol or less with respect to 1 mol of a compound having a hydroxyl group in the naphthalene skeleton, and the mixture is heated and heated to react. After completion of the reaction, the basic catalyst is neutralized with an acid and removed by washing with water, and then the temperature is further raised to remove water produced by the reaction in the system and unreacted monomers to obtain the hydroxynaphthalene compound of the present invention.

In general formula (III), m shows the integer of 1-2.

In general formula (IV), n shows the integer of 0-1.

  Examples of the compound having a hydroxyl group in the naphthalene skeleton represented by the general formula (III) include α-naphthol, β-naphthol, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2, Examples include 3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene. These compounds may be used alone or in combination of two or more. Among these compounds, β-naphthol, which is easy to obtain the hydroxynaphthalene compound of the present invention in a high yield and is economically advantageous, is preferable.

  Examples of the aromatic aldehyde compound represented by the general formula (IV) include benzaldehyde, salicylaldehyde, parahydroxybenzaldehyde and the like. These aromatic aldehyde compounds may be used alone or in combination of two or more. Among these compounds, benzaldehyde is particularly preferable because it easily obtains the hydroxynaphthalene compound in a high yield.

  The blending ratio of the compound having a hydroxyl group in the naphthalene skeleton and the aromatic aldehyde compound is not particularly limited, but it is 0.5 mol or more and 1.5 mol or less of the aromatic aldehyde compound with respect to 1 mol of the compound having a hydroxyl group in the naphthalene skeleton. It is preferable to make it react by the ratio, and especially the ratio of 0.8 mol or more and 1.0 mol or less is preferable. When the number of moles of the aromatic aldehyde compound relative to 1 mole of the compound having a hydroxyl group in the naphthalene skeleton is less than the above lower limit, a large amount of unreacted monomers remain, and a long distillation process is required to remove this. In addition, since the yield decreases, it tends to be economically disadvantageous. On the other hand, when the number of moles of the aromatic aldehyde compound relative to 1 mole of the compound having a hydroxyl group in the naphthalene skeleton exceeds the above upper limit value, an unreacted aromatic aldehyde compound remains, and a distillation process takes a long time to remove it. And the yield is also reduced, which is likely to be economically disadvantageous.

  During the reaction, a solvent is added as necessary. In general, since a compound having a hydroxyl group in the naphthalene skeleton is solid at room temperature, it is desirable to make the reaction system uniform by adding a solvent. In particular, when the aromatic aldehyde compound is parahydroxybenzaldehyde that is solid at room temperature, it is preferable to add a solvent. As the solvent used in the present invention, a solvent inert to the reaction is used. Specific examples include alcohols such as butanol and octanol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and water. Among these solvents, water that is readily available and economically advantageous is preferable. The amount of the solvent used is preferably in the range of 100 parts or less based on the compound having a hydroxyl group in the naphthalene skeleton. When the amount exceeds 100 parts, it takes a long time to remove the solvent, which increases the amount of waste and tends to be economically disadvantageous.

Next, an example of the reaction process will be described.
A system of a compound having a hydroxyl group in the naphthalene skeleton, an aromatic aldehyde compound, and a solvent is heated and heated, and a basic catalyst is added when the temperature in the system reaches 60 to 80 ° C. When the temperature in the system is lower than 60 ° C., a compound having a hydroxyl group in the naphthalene skeleton or an aromatic aldehyde compound may not be completely dissolved. When the temperature in the system exceeds 80 ° C., the reaction proceeds rapidly and there is a risk of bumping.
The basic catalyst used in the above reaction is not particularly limited, but is an aqueous solution of an inorganic base such as sodium hydroxide, barium hydroxide, calcium hydroxide, 1,8-diazabicyclo [5.4.0] undecene-7, etc. These are strong organic bases. Among these basic catalysts, sodium hydroxide and 1,8-diazabicyclo [5.4.0] undecene-7, which are easy to obtain the hydroxynaphthalene compound of the present invention in a high yield, are particularly preferable.

  The amount of the basic catalyst used is not particularly limited, but is 0.2 mol or more and 0.8 mol or less, preferably 0.3 mol or more and 0.6 mol or less with respect to 1 mol of the compound having a hydroxyl group in the naphthalene skeleton. It is a range. When the amount of the basic catalyst used is less than 0.2 mol relative to 1 mol of the compound having a hydroxyl group in the naphthalene skeleton, the reactivity may be poor and a large amount of unreacted monomers may remain. When the amount of basic catalyst used exceeds 0.8 moles per mole of the compound having a hydroxyl group in the naphthalene skeleton, there is no problem in the reaction, but the catalyst removal process takes a long time and the amount of catalyst waste increases. Prone to economic disadvantage.

If an acidic catalyst is used, a compound having a xanthene structure in which hydroxyl groups are condensed, for example, a compound represented by the general formula (V) is formed, and it is difficult to obtain a target hydroxynaphthalene compound in a high yield. Therefore, it is not preferable.

  After adding the basic catalyst, the system is heated and heated to react at 100 to 140 ° C. for 3 to 20 hours. When the reaction temperature is less than 100 ° C., the reaction proceeds slowly and unreacted monomers remain. Moreover, it does not usually occur that the reaction temperature exceeds 140 ° C. due to the reflux of the solvent or condensed water produced by the reaction.

  After completion of the reaction, the basic catalyst is neutralized with an acid and removed by washing with water. The acid used here is not particularly limited as long as it can form a basic catalyst and a neutralized salt, but an organic acid that does not cause ionic impurities is preferable, and acetic acid is particularly preferably used. . The amount of acid added is preferably equivalent to the basic catalyst.

  The method of washing with water is not particularly limited as long as the aqueous layer can be removed from the system after separation into an organic layer containing the hydroxynaphthalene compound produced by the reaction solution and an aqueous layer containing a neutralized salt. It is efficient and preferable to dissolve the target compound layer in an organic solvent such as methyl isobutyl ketone and separate it from the aqueous layer.

After completion of the water washing, the compound having a hydroxyl group on the unreacted naphthalene skeleton and the aromatic aldehyde compound are removed. The removal method is not particularly limited, but it can be removed by distillation under reduced pressure, a method in which water vapor is blown into the system for azeotropic removal, or a recrystallization method. Among these, the recrystallization method is preferable for obtaining a hydroxynaphthalene compound with high purity.
As described above, the hydroxynaphthalene compound used for the novolak resin which is the main component of the composition of the present invention can be obtained.

Next, the novolak resin protected with an acid dissociable group used in the present invention will be described.
First, the novolak resin before being protected with an acid dissociable group will be described.
The novolak resin can be obtained by polycondensation of a hydroxy naphthalene compound and an aldehyde compound under acidic conditions. Although it does not specifically limit as an aldehyde compound, For example, formaldehyde, acetaldehyde, propyl aldehyde, butyraldehyde, benzaldehyde, salicylaldehyde, etc. are mentioned. When formaldehyde is used, the formaldehyde source is not particularly limited, but any formaldehyde can be used as long as it generates formaldehyde, such as formalin (aqueous solution), paraformaldehyde, hemi-formal with alcohols, and trioxane.

The acidic catalyst used for producing the novolak resin is not particularly limited, and examples thereof include organic carboxylic acids such as oxalic acid and acetic acid, organic sulfonic acids such as benzenesulfonic acid, paratoluenesulfonic acid, methanesulfonic acid, and hydrochloric acid. And inorganic acids such as sulfuric acid. Among these, it can also be used individually or in mixture of 2 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 may be small for the characteristics of the novolak resin protected with the acid dissociable group. preferable. Moreover, the reaction solvent can be used as needed. The type is not particularly limited and can be used as long as it does not dissolve the resin and contribute to the reaction.

Next, the novolak resin protected with an acid dissociable group used in the present invention will be described.
This novolak resin protected with an acid-dissociable group has a structure in which the hydroxyl groups in the novolak resin before being protected with the acid-dissociable group have a structure protected at least in part with an acid-dissociable group. And Here, the acid-dissociable group (group that can be removed by the action of an acid) is stable in the absence of an acid and is easily removed by an acid, and is not particularly limited. , Alkyl group, alkoxylcarbonyl group, acyl group, cyclic ether group, etc., specifically, tert-butoxycarbonyl group, ethoxyethyl group, tert-butyl group, isopropyloxyethyl group, propyloxyethyl group, isobutyloxyethyl Group, butyloxyethyl group, cyclohexyloxyethyl group, hydroxybutoxyethyl group, tetrahydropyranyl group, tetrahydrofuranyl group and the like. Among these, a tert-butoxycarbonyl group, an ethoxyethyl group, a tetrahydropyranyl group, and a tert-butyl group are preferable. Thereby, when it uses as a photoresist, it can be set as high sensitivity and heat resistance improves.

  Although the protection rate of the hydroxyl group in the novolak resin by an acid dissociable group is not specifically limited, It is preferable that it is 10-90 mol%, More preferably, it is 15-50 mol%. When the protection rate is lower than the lower limit, the remaining film property tends to be lowered because the protection rate is easily dissolved in the alkaline aqueous solution. On the other hand, when the value is higher than the upper limit, although the remaining film property with respect to the irradiation light is good, the heat resistance may be lowered due to a decrease in the sensitivity of the photoresist or a decrease in the softening point of the resin. What is necessary is just to select a preferable range for the said protection rate by the characteristic of the group to be used. For example, when a tert-butyl group or a tert-butoxycarbonyl group is used as a protecting group, these protecting groups are eliminated by a strong acid, and even if the protection rate is high, the heat resistance tends not to decrease. is there. In addition, when an ethoxyethyl group is used, it is eliminated by a weak acid. Therefore, in order to maintain heat resistance and suppress a change in pattern shape from exposure to heat treatment, the protection rate is reduced to a low value. It is preferable to do. The protection rate due to the acid-dissociable group can be calculated by, for example, using a thermogravimetric analyzer (TG-DTA6300 manufactured by SEIKO ELECTRONICS) and calculating the weight loss corresponding to the acid-dissociable group from the obtained results. As a measurement condition, the heating rate can be 10 ° C./min under a nitrogen atmosphere.

  The compound used for protecting the hydroxyl group in the novolak resin with an acid-dissociable group is not particularly limited. For example, when a tert-butoxycarbonyl group is introduced as a protecting group, di-tert-butyl dicarbonate is used. Similarly, when introducing an ethoxyethyl group, ethyl vinyl ether can be used, and when introducing a tetrahydropyranyl group, 3,4-dihydro-2H-pyran can be used.

  The molecular weight of the novolak resin protected with the acid dissociable group is not particularly limited, but the weight average molecular weight (Mw) by GPC measurement is preferably 1000 to 50000, and more preferably 2000 to 30000. Thereby, it can be set as resin excellent in the balance of resist characteristics, such as alkali solubility and heat resistance. If the weight average molecular weight is less than the lower limit, the heat resistance may be lowered, and if it exceeds the upper limit, the sensitivity of the novolak resin protected with the acid dissociable group may be insufficient. The method for controlling the weight average molecular weight is not particularly limited, but the molar ratio (F / H) of the aldehyde compound (F) to the hydroxy naphthalene compound (H) may be 0.4 to 1.5. Preferably, it is 0.5-1.2. 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 based on a calibration curve prepared using a polystyrene standard substance by gel permeation chromatography (GPC) measurement. GPC measurement was performed under the conditions of using tetrahydrofuran as an elution solvent, a flow rate of 1.0 ml / min, and a column temperature of 40 ° C. Main body: HOS-8020 made by TOSOH, detector: UV-8011 made by TOSOH set at a wavelength of 280 nm, analytical column: SHODEX KF-802, KF-803, KF-805 made by Showa Denko, respectively.

Next, a procedure for synthesizing the novolak resin before being protected with the acid dissociable group will be described. The synthesis method described below is an example and is not particularly limited thereto.
The synthesis is performed by charging the hydroxynaphthalene compound and aldehyde compound into a reaction vessel equipped with a stirrer, a thermometer, and a heat exchanger, and adding an acidic catalyst. In such a reaction, the reaction temperature and time may be appropriately set depending on the reactivity of the raw materials, but in order to synthesize stably and economically, the reaction time is 2 to 10 hours, and the reaction temperature is 70 to 150. It is preferable to set it as ° C. Moreover, a reaction solvent can also be used if necessary. The type of the solvent is not particularly limited, but a solvent that does not participate in the reaction and dissolves the resin obtained by the reaction, such as ethyl cellosolve and methyl ethyl ketone, is preferable.

  Furthermore, after completion of the above reaction, for example, a basic compound may be added for neutralization in order 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 are not particularly limited, but the number of times of washing is preferably about 1 to 5 times from the viewpoint of removing the neutralized salt in the resin to a level that does not substantially affect the washing. The washing temperature is not particularly limited, but is preferably 40 to 95 ° C. from the viewpoint of the removal efficiency of neutralized salt and workability.

  After completion of the above reaction or water washing, dehydration / demonomerization is performed under normal pressure and / or under reduced pressure. The degree of reduced pressure at which dehydration / demonomer is performed is not particularly limited, but is preferably about 0.1 to 200 torr. The temperature for taking out from the reaction vessel after dehydration / demonomer is not particularly limited, and can be set as appropriate depending on the characteristics and viscosity of the resin. From the viewpoint of the stability of the resin, 150 to 250 ° C. is preferable. Thus, the novolak resin before being protected with the acid dissociable group used in the present invention can be obtained.

Next, a method for producing a novolak resin protected with an acid dissociable group from the novolak resin will be described.
A part or all of the hydroxyl groups in the novolak resin obtained by the above method are protected with an acid-dissociable group. In the resin thus obtained, the acid-dissociable group can be easily eliminated by the action of an acid to form a free hydroxyl group. A resist function is imparted by producing a difference in solubility. The method for protecting the hydroxyl group in the novolak resin with an acid-dissociable group is not particularly limited because the raw materials and methods used by the acid-dissociable group are different. For example, when protecting with a tert-butoxycarbonyl group, The hydroxy naphthalene resin can be protected by adding a predetermined amount of di-tert-butyl dicarbonate and reacting in the presence of a basic compound for a predetermined time. Further, when protecting with an ethoxyethyl group or a tetrahydropyranyl group, each can be protected by reacting ethyl vinyl ether or dihydropyran for a predetermined time in the presence of an acidic catalyst.

  In synthesizing the novolak resin protected with such an acid dissociable group, the equipment material such as a reaction vessel is not particularly limited, but from the viewpoint of mixing impurities, glass lining, polytetrafluoroethylene, tantalum, hafnium, zirconium, It is desirable to use a production apparatus that uses a metal selected from niobium and titanium or an alloy thereof and that is substantially free of other materials and uses a metal material resistant to corrosion as a reactor material.

Next, the photoacid generator will be described.
The photoacid generator used in the present invention is not particularly limited, but sulfonium salt derivatives [aryl alkane sulfonates such as sulfonic acid ester (1,2,3-tri (methylsulfonyloxy) benzene (especially C _6-10 aryl C _1-2 alkanesulfonate); 2,6-dinitrobenzyltoluenesulfonate, benzointosylate nadonoarylbenzenesulfonate (especially C _6-10 aryltoluenephosphonate optionally having a benzoyl group); 2-benzoyl-2-hydroxy- Aralkylbenzenesulfonates such as 2-phenylethyltoluenesulfonate (especially C _6-10 aryl-C _1-4 alkyltoluenesulfonate optionally having benzoyl group); disulfonic acid such as diphenyldisulfone; Lewis acid salt (triferate) Nils Triarylsulfonium salts such as triphenylsulfonium hexafluoroantimony, triphenylsulfonium methanesulfonyl (especially triphenylsulfonium salts))], phosphonium salt derivatives, diarylhalonium salt derivatives [diaryliodonium salts Examples include Lewis acid salts (such as diphenyliodonium hexafluorophosphate), diazonium salt derivatives (such as Lewis acid salts such as p-nitrophenyldiazonium hexafluorophosphate), diazomethane derivatives, and triazine derivatives. In particular, Lewis acid salts (Lewis acid salts such as phosphonium salts) are preferable because resist characteristics with excellent balance of sensitivity, resolution, heat resistance and the like of the photoresist composition can be obtained.

]
Subsequently, the solvent will be described.
Although it does not specifically limit as a solvent mix | blended with the photoresist composition of this invention, For example, water, alcohols, glycols, cellosolves, ketones, ester, ethers, amides, hydrocarbons etc. are mentioned, for example. Specifically, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl cellosolve acetate, methyl cellosolve acetate, butyl cellosolve acetate, methoxyethyl propionate, ethoxyethyl propionate, methyl lactate , Ethyl lactate, butyl lactate, ethyl acetate, butyl acetate, methyl isobutyl ketone, methyl pentyl ketone and the like. Among these, PGMEA, ethoxyethyl propionate, and ethyl lactate are particularly preferable from the viewpoints of solubility, coating film stability, safety, influence on the environment, influence on the human body, and economy. These can be used alone or in admixture of two or more.

  In addition to the above-described components, the composition of the present invention may contain various additives such as stabilizers such as antioxidants, plasticizers, surfactants, adhesion improvers, and dissolution accelerators as necessary. Agents can be used.

  Hereinafter, the present invention will be described in detail with reference to examples. “Parts” and “%” described herein all represent “parts by weight” and “% by weight”, and the present invention is not limited by these examples.

(Synthesis of novolak resin protected with acid dissociable groups)
Synthesis example 1
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, and then 100 parts of methyl isobutyl ketone and 120 parts of water were added, stirred for 10 minutes, and allowed to stand to separate the organic layer containing the produced hydroxynaphthalene compound from the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Then, 10 parts of ethyl cellosolve was added and the temperature was raised and dehydrated to an internal temperature of 170 ° C. under normal pressure. Further, dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
In the presence of trimethylamine, 20 parts of di-tert-butyl dicarbonate was added to the resulting novolak resin tetrahydrofuran solution, reacted at 60 ° C. for 6 hours, and then neutralized with acetic acid. After ion-exchanged water was added and washed with water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6130 and a protection rate of tert-butoxycarbonyl group of 15%.

Synthesis example 2
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
25 parts of di-tert-butyl dicarbonate was added to the resulting novolak resin tetrahydrofuran solution in the presence of trimethylamine, reacted at 60 ° C. for 6 hours, and then neutralized with acetic acid. After ion-exchanged water was added and washed with water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6590 and a protection rate of tert-butoxycarbonyl group of 20%.

Synthesis example 3
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
In the presence of trimethylamine, 39 parts of di-tert-butyl dicarbonate was added to the resulting novolak resin tetrahydrofuran solution, reacted at 60 ° C. for 6 hours, and then neutralized with acetic acid. After ion-exchanged water was added and washed with water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 7220 and a protection rate of tert-butoxycarbonyl group of 30%.

Synthesis example 4
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
To the resulting tetrahydrofuran solution of novolak resin, 12 parts of ethyl vinyl ether was added in the presence of p-toluenesulfonic acid and 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 novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 5990, and the protection ratio of ethoxyethyl group was 14%.

Synthesis example 5
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
After 19 parts of ethyl vinyl ether was added to the resulting novolak resin tetrahydrofuran solution in the presence of p-toluenesulfonic acid and reacted at 40 ° C. for 4 hours, neutralization was performed using triethylamine. After washing with ion-exchanged water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6250 and an ethoxyethyl group protection ratio of 20%.

Synthesis Example 6
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
25 parts of ethyl vinyl ether was added to the resulting novolak resin tetrahydrofuran solution in the presence of p-toluenesulfonic acid and reacted at 40 ° C. for 4 hours, followed by neutralization with triethylamine. After washing with ion-exchanged water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6490, and the protection ratio of ethoxyethyl group of the resin was 30%.

Synthesis example 7
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
29 parts of 3,4-dihydro-2H-pyran was added to the resulting novolak resin tetrahydrofuran solution in the presence of p-toluenesulfonic acid and reacted at 40 ° C. for 4 hours, followed by neutralization with triethylamine. . After washing with ion-exchanged water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6470 and a tetrahydropyranyl group protection ratio of 15%.

Synthesis example 8
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
After adding 40 parts of 3,4-dihydro-2H-pyran to the tetrahydrofuran solution of the obtained novolak resin in the presence of paratoluenesulfonic acid and reacting at 40 ° C. for 4 hours, neutralization was performed using triethylamine. . After washing with ion-exchanged water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6740, and the protection ratio of the tetrahydropyranyl group was 21%.

Synthesis Example 9
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 100 parts of β-naphthol, 59 parts of benzaldehyde and 25 parts of water, and when the temperature in the system reached 70 ° C., 50% hydroxylation 30 parts of an aqueous sodium solution were gradually added. Thereafter, the temperature was further raised, and the temperature in the system was kept at 110 ° C. to react for 3 hours. Next, 22 parts of acetic acid was added for neutralization, 100 parts of methyl isobutyl ketone and 120 parts of water were added and stirred for 10 minutes, and then allowed to stand to separate the organic layer and the aqueous layer. After removing the aqueous layer from the system, water and methyl isobutyl ketone were distilled off while raising the temperature in the system to 150 ° C. Further, while maintaining the temperature in the system at 150 ° C., steam was blown into the system at a rate of 500 ml / hour for 2 hours to remove unreacted β-naphthol. Next, 11 parts of 37% formaldehyde and 1.5 parts of oxalic acid were added and reacted at 98 to 102 ° C. for 4 hours. Further, 10 parts of ethyl cellosolve was added and dehydrated to an internal temperature of 170 ° C. under normal pressure. Dehydration / demonomerization was performed to 200 ° C. under a reduced pressure of 80 torr to obtain 57 parts of a novolak resin.
58 parts of 3,4-dihydro-2H-pyran was added to the tetrahydrofuran solution of the resulting novolak resin in the presence of paratoluenesulfonic acid, 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 novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 6910 and a protection rate of the tetrahydropyranyl group of 30%.

Synthesis Example 10
A reactor equipped with a stirrer, reflux condenser and thermometer was charged with 600 parts of metacresol, 400 parts of paracresol, 525 parts of 37% formalin and 2 parts of oxalic acid, and reacted at 60 ° C. for 1 hour and at 100 ° C. for 4 hours. After the dehydration, dehydration was performed up to 170 ° C. under normal pressure, and dehydration / demonomerization was performed up to 200 ° C. under reduced pressure of 80 torr to obtain 850 parts of a novolak resin.
To the resulting tetrahydrofuran solution of novolak resin, 800 parts of di-tert-butyl dicarbonate was added in the presence of trimethylamine, reacted at 60 ° C. for 6 hours, and then neutralized with acetic acid. After ion-exchanged water was added and washed with water, the solvent was removed to obtain a novolak resin protected with an acid-dissociable group. The obtained novolak resin had a weight average molecular weight (Mw) of 8420 and a protection rate of tert-butoxycarbonyl group of 15%.

In addition, the protection rate was calculated by using a thermogravimetric analyzer (TG-DTA6300 manufactured by SEIKO ELECTRONICS) and calculating the weight loss corresponding to each protecting group that can be removed by an acid from the obtained results. As measurement conditions, the temperature elevation rate was 10 ° C./min under a nitrogen atmosphere.
The weight average molecular weight was calculated based on a calibration curve created using a polystyrene standard substance by gel permeation chromatography (GPC) measurement. GPC measurement was performed under the conditions of using tetrahydrofuran as an elution solvent, a flow rate of 1.0 ml / min, and a column temperature of 40 ° C. Main body: HOS-8020 made by TOSOH, detector: UV-8011 made by TOSOH set at a wavelength of 280 nm, analytical column: SHODEX KF-802, KF-803, KF-805 made by Showa Denko, respectively.

(Preparation of photoresist composition)
Examples 1 to 9 and Comparative Example 1
The novolak resin protected with the acid-dissociable group obtained in Synthesis Examples 1 to 10 was dissolved in propylene glycol monomethyl ether acetate to prepare a 15% resin solution, and a photoacid generator (TPS-manufactured by Midori Chemical Co., Ltd.) was prepared. 105) was added to the resin solution at 1%, followed by filtration using a 0.2 μm PTFE (polytetrafluoroethylene) filter to obtain a photoresist composition.
The obtained photoresist composition was evaluated for sensitivity, focus margin, tan θ, and heat resistance. The results are shown in Table 1.

(Evaluation methods)
(1) Sensitivity (E _OP )
The photoresist composition prepared above was applied onto a silicon substrate using a spin coater and pre-baked at 90 ° C. for 60 seconds to form a resist film having a thickness of 0.5 μm. This resist film was exposed using an i-line irradiation device (lens numerical aperture 0.57, exposure wavelength 365 nm) or a KrF excimer laser irradiation device (lens numerical aperture 0.60, exposure wavelength 248 nm). Immediately after the exposure, the substrate was baked at 90 ° C. for 60 seconds, developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, washed with water and dried to obtain a positive pattern. At that time, the sensitivity (E _OP) can be used to form a line-and-space pattern having a line width of 0.50 μm for i-line irradiation and a line width of 0.18 μm for KrF excimer laser irradiation in a one-to-one line width. ).

(2) Focus margin The focus position is moved up and down, and exposure is performed with a minimum exposure amount that reproduces a line and space pattern having a line width of 0.50 μm for i-line irradiation and a line width of 0.18 μm for KrF excimer laser irradiation. Then, when development was performed, an allowable range of focus that can reproduce a line and space pattern with line widths of 0.50 μm and 0.18 μm, respectively, was measured.

(3) tan θ
Taking the exposure amount (mJ / cm ² ) on the horizontal axis and the development rate (nm / s) of the composition on the vertical axis, an identification curve in which alkali dissolution rates with respect to various exposure amounts are plotted was prepared. The slope of the curve near the inflection point was expressed as a tangent (tan θ).

(4) Heat resistance The above-prepared photoresist composition was applied onto a hexamethyldisilazane-treated silicon wafer with a spin coater so that the film thickness when dried was 0.7 μm, and hot pre-treatment was performed at 110 ° C. for 90 seconds. -Dried on top. Thereafter, exposure was performed through a test chart mask using a reduction projection exposure apparatus, and development was performed for 50 seconds using a developer (2.38% tetramethylammonium hydroxide aqueous solution). The obtained silicon wafer is allowed to stand for 30 minutes on a hot plate at a different temperature, and the shape of the resist pattern on the silicon wafer is observed with a scanning electron microscope. A: No change in pattern at 125 ° C. A: No change in pattern at 125 ° C.

  Examples 1 to 9 are photoresist compositions prepared using the hydroxynaphthalene compound of the present invention, which were excellent in sensitivity, resolution and heat resistance and had a sufficient focus margin. Since the comparative example 1 did not use the hydroxy naphthalene compound, both heat resistance and sensitivity were inferior.

  The photoresist composition of the present invention uses a resin in which a novolak resin obtained by reacting a hydroxynaphthalene compound represented by the formula (I) or the formula (II) with an aldehyde compound as a phenol is protected with an acid-dissociable group. Therefore, it has excellent photoresist characteristics such as sensitivity, resolution, and heat resistance. Therefore, the present invention is suitably applied to a photoresist composition that is applied to a lithography process when manufacturing electrode patterns of semiconductors and thin panel displays using radiation such as g-line, i-line, and KrF excimer laser. Is.

Claims (4)

A novolak resin obtained by reacting a hydroxynaphthalene compound represented by the following general formula (I) with an aldehyde compound under an acidic catalyst, wherein a part or all of the hydroxyl groups in the resin can be removed by the action of an acid. A photoresist composition comprising a novolak resin protected with a group as an essential component.

In general formula (I), m represents an integer of 1 to 2, and n represents an integer of 0 to 1. The photoresist composition according to claim 1, wherein the hydroxynaphthalene compound is a compound represented by the following chemical formula (II).

The photoresist composition according to claim 1 or 2, wherein the group capable of leaving by the action of an acid is any one of a tert-butoxycarbonyl group, an ethoxyethyl group, a tetrahydropyranyl group, and a tert-butyl group. The photoresist composition according to any one of claims 1 to 3, wherein a protection ratio of a hydroxyl group in the hydroxynaphthalene resin by a group removable by the action of an acid is 5 to 90 mol%.