JP6386764B2 - Method for producing novolac-type phenolic resin, novolac-type phenolic resin, and photoresist composition - Google Patents

Description

  The present invention relates to a method for producing a novolak-type phenol resin, a novolac-type phenol resin, and a photoresist composition that enable the production of a photoresist composition having high heat resistance, high sensitivity, a high residual film ratio, and high resolution.

  Generally, a positive photoresist composition uses a photosensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin. Since this positive photoresist composition has a high resolving power when developed with an alkaline solution, it is suitably used for the production of semiconductors such as IC and LSI and the production of circuit substrates such as LCD. In particular, when a novolac type phenol resin having heat resistance is used as the alkali-soluble resin, dry etching after exposure can be suitably performed. Many positive photoresists containing novolac type phenolic resins have been developed and put into practical use.

  A novolak type phenolic resin used for a positive photoresist composition is a resin obtained by subjecting m-, p- or o-cresol and formaldehyde to a condensation polymerization reaction in the presence of an acid catalyst. The ratio of m-, p- or o-cresol used is adjusted in accordance with the required characteristics. Further, in order to adjust or improve the characteristics of the photoresist, studies have been made on molecular weight, molecular weight distribution, and the like.

  By the way, in the field of LCDs, the line width of an image becomes narrower with the progress of technologies such as TFT, STN, etc., and the tendency of further miniaturization is intensifying. Recently, the design dimensions of high-definition TFT display elements have been improved to a few μm level. In such applications, a photoresist composition having a well-balanced high heat resistance, high sensitivity, high residual film ratio, and high resolution is required, so that conventional positive-type photoresist compositions cannot be used. Further, for photoresist compositions used for semiconductors, there has been a demand for a photoresist composition having a high level of high heat resistance, high sensitivity, high residual film ratio, and high resolution in a balanced manner.

  For this reason, for example, as a method for improving the heat resistance of a novolac type phenol resin, studies using alkylphenols such as xylenol and trimethylphenol have been made. However, with this method, the heat resistance is only slightly improved and a sufficient effect cannot be obtained.

  As another method for improving heat resistance, a method using an aromatic aldehyde has been studied. Patent Document 1 proposes that salicylaldehyde, which is an aromatic aldehyde, and formaldehyde are used in combination as a crosslinking group. However, the novolak type phenolic resin using salicylaldehyde and formaldehyde in combination has a problem that the rate of remaining film after development is low because the dissolution rate in an alkaline developer is too fast during exposure and development. This is described in Patent Document 2 (see paragraph 0002 and Examples) by the same inventor as Patent Document 1.

  In Patent Document 3, as a phenolic resin for a photoresist that achieves both high heat resistance, high resolution, and high sensitivity, phenols containing m-cresol, p-cresol, and naphthol, and formaldehyde and / or cross-linking groups are used. A novolak phenolic resin for photoresist containing paraform is described. As an example of this document, an example using phenols containing m-cresol, p-cresol and 1-naphthol and formaldehyde as a crosslinking group is disclosed. However, in the method in the literature, removal of naphthol, which is an unreacted high boiling point substance, may be troublesome in operation, and only a certain amount of naphthol can be taken into the resin skeleton, and heat resistance is the target. Therefore, it is insufficient as a phenol resin for photoresist. A photoresist using a novolac type phenolic resin in the literature is not sufficient in terms of heat resistance, sensitivity, remaining film ratio, resolution, etc., and there is room for further improvement. (See Comparative Example 2 and Comparative Example 3 of this application)

Japanese Patent Application No. 2-84414 JP 2008-88197 A JP 2009-227926 A

  However, in the field of LCDs or the like, the line width of an image becomes narrower with the progress of technologies such as TFT and STN, and the tendency of miniaturization becomes stronger. Recently, the design dimension of high-definition TFT display elements has been improved to several μm level. In such applications, a photoresist having a particularly high resolving power, high heat resistance, high sensitivity, and a high residual film ratio is required, and the conventional positive photoresist cannot cope with the present situation.

  Accordingly, the present invention provides a method for producing a novolak-type phenol resin, a novolac-type phenol resin, and a photoresist composition that enable the production of a photoresist composition having high heat resistance, high sensitivity, high residual film ratio, and high resolution. The purpose is to provide.

  In order to achieve the above object, as a result of intensive research, the present inventors have reacted naphthols (a1), cresols (b1) and formaldehydes (c1) to form a compound represented by Formula 1. A first step for obtaining an intermediate reactant containing 10 to 80% by mass of a nucleus, and an unreacted naphthol content of the unreacted naphthols (a1) in the intermediate reactant obtained in the first step up to 10% by mass or less Is produced by a second step of removing the alcohol and a third step of reacting the intermediate reactant, cresols (b2) and formaldehydes (c2) treated in the second step to obtain a novolak type phenol resin. It has been found that when a novolac type phenolic resin is used in a photoresist composition, it has high heat resistance, high sensitivity, a high residual film rate and high resolution. That is, the present invention provides a first intermediate product obtained by reacting naphthols (a1), cresols (b1) and formaldehydes (c1) to contain 10 to 80% by mass of the trinuclear compound represented by Formula 1. Processed in the step, the second step of removing the unreacted naphthols to the content of the unreacted naphthols (a1) in the intermediate reaction product obtained in the first step to 10% by mass or less, and the second step. And a third step of obtaining a novolak-type phenol resin by reacting an intermediate reactant, cresols (b2) and formaldehydes (c2), and a method for producing a novolak-type phenol resin for a photoresist.

  As described above, according to the present invention, the novolak-type phenolic resin that can be used for a photoresist composition having high heat resistance, high sensitivity, high residual film ratio, and high resolution, a method for producing the same, and a photo using the same A resist composition can be provided. That is, when the novolac type phenol resin obtained by this production method is used, a photoresist composition having a high balance of high heat resistance, high sensitivity, high residual film ratio and high resolution can be obtained. For this reason, it can be suitably used as a material for lithography or a material for a semiconductor insulating film when manufacturing a highly integrated semiconductor or a thin film transistor (TFT) for liquid crystal.

(First step)
In the production method according to the present invention, the first step includes 10 to 80% by mass of the trinuclear compound represented by Formula 1 by reacting naphthols (a1), cresols (b1), and formaldehydes (c1). In this step, an intermediate reaction product is obtained. That is, in the first step, for example, naphthols (a1) composed of 1-naphthol, cresols (b1) composed of m-cresol and / or p-cresol and formaldehydes (c1) are subjected to a condensation polymerization reaction. 1-naphthol (a1) and cresols (b1) produce a segment (S1) in which polymer units of a phenol resin obtained by condensation polymerization with formaldehyde (c1) are blocked.

  In the reaction formula of the first step, l represents the degree of polymerization of the polymer units of the phenol resin obtained by condensation polymerization of naphthols (a1), cresols (b1) and formaldehydes (c1) in the first step. Indicates an integer.

  In the first step, the naphthols (a1) are preferably one or more of 1-naphthol and 2-naphthol, more preferably 1-naphthol.

  In the first step, the cresol (b1) is a cresol that is any one or more of ortho-cresol (2-methylphenol), meta-cresol (3-methylphenol), and para-cresol (4-methylphenol). is there. Preferred is metacresol alone, paracresol alone, or a mixture of metacresol and paracresol, and more preferred is paracresol alone.

  In the first step, the formaldehyde (c1) is not particularly limited in form, and in addition to an aqueous formaldehyde solution, a polymer that decomposes in the presence of an acid such as paraformaldehyde or trioxane to formaldehyde can also be used.

  In the first step, the blending amount of the naphthols (a1) is preferably 1 to 10 mol, more preferably 3 to 6 mol, relative to 1 mol of the cresols (b1). Moreover, the compounding quantity of formaldehyde (c1) becomes like this. Preferably it is 1.0-3.0 mol with respect to 1 mol of cresols (b1), More preferably, it is 2.0-2.5 mol.

  In the first step, naphthols (a1), cresols (b1), and formaldehydes (c1) are blended in the above range to obtain a trinuclear represented by Formula 1 in which naphthols are incorporated into the resin structure. The intermediate reactant containing the body can be stably obtained.

  The intermediate reaction product obtained in the first step contains 10-80% by mass of a trinuclear compound represented by the formula 1 in a skeleton derived from naphthols (a1) in the resin structure, and 20-70% by mass. It is preferable to contain, and it is more preferable to contain 30-60 mass%. As mentioned above, when naphthols (a1), cresols (b1) and formaldehydes (c1) are blended, the naphthols are excessive with respect to cresols and formaldehydes, so that they have a low molecular weight like trinuclear bodies. Easy to produce components.

  The weight average molecular weight of the intermediate reactant obtained in the first step is preferably 400 to 2000, more preferably 500 to 1500.

  In the first step, the method for subjecting the naphthols (a1), the cresols (b1) and the formaldehydes (c1) to a polycondensation reaction is not particularly limited. A known catalyst, a solvent, a reaction temperature, a reaction time, and the like that can cause a polycondensation reaction of naphthol (a1), cresols (b1), and formaldehydes (c1) can be employed. Moreover, also about the post-process after completion | finish of reaction, well-known methods, such as neutralization, water washing, dehydration, and reduced pressure distillation, are employable.

  One preferred embodiment of the first step is, for example, a step A in which cresols (b1) and formaldehydes (c1) are reacted in the presence of a basic catalyst to obtain a dimethylol form of cresols, and then the cresols obtained. There exists an aspect provided with the process B which makes the dimethylol body and naphthol (a1) of this react with an acid catalyst.

  Specifically, cresols (b1) and formaldehydes (c1) are reacted in water in a basic catalyst such as sodium hydroxide at a reaction temperature of 40 to 50 ° C. for 3 to 6 hours. A dimethylol body was obtained, and then the obtained dimethylol body and naphthols (a1) were used in a solvent-free or solvent such as water, methanol, ethanol, propanol, butanol, toluene, methyl isobutyl ketone, oxalic acid, benzenesulfonic acid, An intermediate reaction product can be obtained by reacting at a reaction temperature of 40 to 85 ° C. for 2 to 15 hours under an acid catalyst such as paratoluenesulfonic acid, methanesulfonic acid, hydrochloric acid, sulfuric acid, or phosphoric acid.

(Second step)
In the production method according to the present invention, in the second step, the content of unreacted naphthols (a1) in the intermediate reaction product obtained in the first step is 10% by mass or less, more preferably 5% by mass or less, Preferably, it is a step of removing unreacted naphthols to 3% by mass or less, most preferably 1% by mass or less. Since the intermediate reactant obtained in the first step has a low molecular weight and a low viscosity at the time of melting, unreacted naphthol can be easily removed by heating under reduced pressure. As a specific method for removing unreacted naphthol, a known method such as a method by heating under reduced pressure, a method by steam distillation, or a method using a thin film distillation apparatus can be used.

  Specifically, the intermediate reaction product is washed with water as a post-treatment in the first step, and then unreacted naphthols (a1) and the like are unreacted using a heated vacuum distillation or steam distillation (vacuum steaming) or thin film distillation apparatus. The reaction raw material can be removed. By this method, an intermediate reaction product in which naphthols are incorporated into the resin structure can be stably obtained.

(Third step)
In the production method according to the present invention, the third step is a step of obtaining a novolac type phenol resin by reacting the intermediate reactant, cresol (b2) and formaldehyde (c2) treated in the second step. That is, in the third step, for example, cresols (b2) composed of m-cresol and / or p-cresol, formaldehyde (c2), and the segment (S1) generated in the first step are further subjected to a condensation polymerization reaction. Then, a segment (S2) in which a polymer unit of a phenol resin obtained by condensation polymerization of cresols (b2) and formaldehyde (c2), 1-naphthol (a1) and cresols (b1) are converted into formaldehyde ( A novolak-type phenol resin having a segment (S1) in which the polymer units of the phenol resin polycondensed in c1) are blocked is obtained.

《第２工程》

<< Second process >>

  In the reaction formula of the third step, m is the degree of polymerization when the segments (S1) are subjected to condensation polymerization in the third step, and n is the condensation polymerization of cresols (b1) and formaldehydes (c1) in the third step. The degree of polymerization of the polymer unit of the phenol resin, z represents the degree of polymerization in which the segment (S1) and the segment (S2) were polycondensed in the third step, and m, n, and z each independently represents an integer of 1 to 100. Show.

  Thus, according to the production method of the present invention, polymer units and / or cresols (b2) of a phenol resin obtained by condensation polymerization of naphthols (a1), cresols (b1) and formaldehydes (c1) in the molecule. A novolak-type phenol resin in which polymer units of a phenol resin obtained by condensation polymerization of aldehyde and formaldehyde (c2) are blocked can be produced. That is, the novolak type phenolic resin of the present invention has a structure such as... S2S2S1S1S1S2..., S2S1S2S1S2S2S1. This is different in chemical structure from the novolak type phenol resin produced by so-called random condensation polymerization reaction.

  In addition, according to the condensation polymerization reaction in the production method of the present invention, the distribution of the degree of polymerization of each polymer unit present in a blocked state becomes narrow, and the molecular weight can be easily controlled. In addition, since naphthol can be reliably consumed and taken into the resin and the reaction can be completed, the operation of removing unreacted naphthol having a high boiling point in the second step can be omitted, and quality can be reduced. It also leads to stabilization. In addition, a desired novolac-type phenol resin that has high heat resistance, high sensitivity, and high resolution when formed into a photoresist composition can be obtained.

  The novolak type phenolic resin of the present invention is a phenolic resin obtained by condensation polymerization of naphthols (a1), cresols (b1) and formaldehydes (c1) as compared with the novolak type phenolic resin obtained by random condensation polymerization reaction. Random polycondensation reaction is sufficient if the polymer units of the phenol resin in which the polymer units and / or the cresols (b2) and the formaldehydes (c2) are polycondensed are adjacent to each other and repeatedly bonded. Compared to the above case, it is preferable that the bonding is repeated adjacently at a high ratio of preferably 1.1 times or more, more preferably 1.3 times or more, and still more preferably 1.5 times or more.

  The third step may be continuously performed in the same reaction system following the first step and the second step. In the case where the third step is continuously performed, the cresols (b2) are added to the intermediate reaction product from which raw materials such as unreacted naphthols (a1) have been removed in the second step and mixed uniformly, and then formaldehydes ( The method of adding c2) and carrying out a condensation polymerization reaction can be taken.

  In addition, the third step may be performed in a reaction system different from the first step and the second step, once taking out the intermediate reactant processed in the second step. In that case, after adding the intermediate reaction material processed at the 2nd process to cresol (b2) and mixing it uniformly, the method of adding formaldehyde (c2) and carrying out a polycondensation reaction is preferable.

  In the third step, the cresol (b2) is at least one cresol selected from the group consisting of ortho-cresol, meta-cresol, and para-cresol, and preferably a mixture of meta-cresol and para-cresol.

  When the cresol (b2) is a mixture of metacresol and paracresol, the molar ratio of metacresol to paracresol (metacresol / paracresol) is preferably 1.0 to 4.5. More preferably, it is 1.2-4.3, More preferably, it is 1.4-4.1.

  In the third step, the cresols (b2) can contain other well-known phenol compounds within the scope of the effect of the present invention. Specific examples of other known phenol compounds include phenol, o-cresol, xylenol, and trimethylphenol. Xylenol is 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol. Each structural isomer can be used, and also in trimethylphenol, each isomer such as 2,3,5-trimethylphenol, 2,3,6-trimethylphenol and the like can be used. Divalent phenols such as catechol, resorcinol and hydroquinone can also be used.

  The content of other known phenol compounds is preferably less than 20% by mass when the cresol (b2) is 100% by mass.

  In the third step, the formaldehyde (c2) is not particularly limited in form, and in addition to an aqueous formaldehyde solution, a polymer that decomposes in the presence of an acid such as paraformaldehyde or trioxane to formaldehyde can also be used.

  In the third step, the method for adding formaldehydes (c2) may be batch addition in which formaldehydes (c2) are added all at once or sequential addition by dropping or the like, but the intermediate and cresols treated in the second step ( Since reaction heat may be difficult to control due to reaction heat generated in the reaction with b2), sequential addition by dropping or the like is preferable.

  In the third step, the amount of the intermediate reactant treated in the second step and the cresol (b2) is 100% by mass of the intermediate reactant and the cresol (b2). The blending amount is preferably 5 to 50% by mass, more preferably 6 to 40% by mass, further preferably 7 to 35% by mass, further preferably 8 to 30% by mass, and most preferably. 9 to 25% by mass. By setting the mass ratio of the intermediate reaction product and the cresols (b2) within the above range, a novolac type phenol resin having heat resistance when used as a photoresist composition can be obtained.

  In the third step, the blending amount of formaldehydes (c2) is a mass ratio (mass of formaldehydes (c2) with respect to the total blending amount of the intermediate reactant and cresols (b2) treated in the second step. / Total mass of intermediate reaction product and cresols (b2)), preferably 0.140 to 0.200, more preferably 0.150 to 0.190, and even more preferably 0.150 to 0.185. Preferably in the molar ratio with the cresols (b2) (number of moles of formaldehydes (c2) / number of moles of cresols (b2)), 0.65 to 0.85, more preferably 0.68 to 0.83, More preferably, it is 0.70-0.82. By making the compounding quantity of formaldehydes (c2) into the said range, it can be set as the novolak-type phenol resin which has heat resistance, when it is set as a photoresist composition.

  In the third step, the amount of the intermediate reaction product, the cresols (b2) and the formaldehydes (c2) treated in the second step is adjusted, and the components of the cresols (b2) such as metacresol and paracresol By adjusting the composition, it is possible to adjust characteristics such as heat resistance, sensitivity, remaining film rate, and resolution when a novolac type phenol resin is used as a resist composition.

  In the third step, an acid catalyst can be used as a catalyst for reacting the intermediate reaction product treated in the second step with the cresols (b2) and the formaldehydes (c2). Examples of the acid catalyst include organic sulfonic acids such as oxalic acid, benzenesulfonic acid, paratoluenesulfonic acid, and methanesulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid. The amount of acid catalyst used varies depending on the type, but in the case of oxalic acid, about 0.3 to 1.0% by mass, in the case of sulfuric acid, about 0.05 to 0.1% by mass, and paratoluenesulfonic acid In this case, it is preferable to use about 0.1 to 0.5% by mass. As the acid catalyst, oxalic acid is preferable.

  In the third step, the reaction temperature for reacting the intermediate reactant treated in the second step with the cresols (b2) and the formaldehydes (c2) is not particularly limited, but is preferably 60 to 160 ° C. Preferably it is 80-140 degreeC. If the reaction temperature is lower than 50 ° C., the reaction does not proceed. If the reaction temperature is higher than 200 ° C., it may be difficult to control the reaction, and it may be difficult to stably obtain the target novolac phenol resin. .

  In the third step, when the intermediate reaction product, the cresols (b2) and the formaldehydes (c2) treated in the second step are reacted, a reaction solvent can be used as necessary. The reaction solvent is preferably water that dissolves cresols and formaldehyde, but in some cases, an organic solvent that does not affect the reaction can also be used. Examples of such organic solvents include ethers such as diethylene glycol dimethyl ether, 1,2-dimethoxyethane, and 1,2-diethoxyethane; esters such as propylene glycol monomethyl ether acetate; and cyclic ethers such as tetrahydrofuran and dioxane. Can be mentioned.

  The amount of these reaction solvents used is usually 20 to 1000 parts by mass per 100 parts by mass of the reaction raw material.

  In the third step, the reaction time for reacting the intermediate reactant treated in the second step with the cresols (b2) and the formaldehydes (c2) depends on the reaction temperature, but is usually within 20 hours. . The reaction pressure is usually carried out under normal pressure, but it can also be carried out under slight pressure or reduced pressure.

  After completion of the reaction in the third step, as a post-treatment, it is preferable to add a base to neutralize the acid catalyst, and subsequently add water to remove the acid catalyst and carry out water washing.

  The base for neutralizing the acid catalyst is not particularly limited, and any base that neutralizes the acid catalyst and forms a salt that is soluble in water can be used. Examples of the base include inorganic bases such as metal hydroxides and metal carbonates, and organic bases such as amines and organic amines. Specific examples of the inorganic base include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, and calcium carbonate. Specific examples of organic base amines or organic amines include ammonia, trimethylamine, triethylamine, diethylamine, and tributylamine. Preferably organic amines are used. It is preferable to use the base in such an amount that the acid catalyst is neutralized and the pH in the reaction system is in the range of 4-8.

  The amount of washing water and the number of washings are not particularly limited. In order to remove the acid catalyst to an amount that does not affect the actual use as a resist composition, the number of washings is about 1 to 5 times.

  The washing temperature is not particularly limited, but is preferably 40 to 95 ° C. from the viewpoint of catalyst removal efficiency and workability. When the resin and the washing water are poorly separated during washing with water, it is effective to add a solvent that lowers the viscosity of the resin and raise the washing temperature. Such a solvent can be used without particular limitation as long as it dissolves the phenol resin and lowers the viscosity.

  After removing the acidic catalyst by neutralization and washing with water, for example, the temperature of the reaction system is raised to 130 ° C. to 230 ° C., and the unreacted raw materials, organic solvents, etc. present in the reaction system under a reduced pressure of 20 to 50 torr. The novolak type phenol resin of the present invention can be obtained by distilling off the volatile components.

  As described above, the production method according to the present invention can provide a novolak-type phenol resin having a small content of unreacted naphthols and incorporating naphthols in the resin skeleton. In addition, a novolak-type phenol resin is obtained in which a polymer unit composed of naphthols, cresols and formaldehydes obtained in the first step and a polymer unit composed of cresols and formaldehydes are blocked in the resin structure. be able to.

(Novolac type phenolic resin)
The novolak-type phenol resin produced by the above production method is a novolac-type phenol resin obtained by condensation polymerization reaction of naphthols, cresols, and formaldehydes, and includes naphthols (a1) in the molecule. Polymer units of cresols and phenolic resins obtained by condensation polymerization of (b1) and formaldehydes (c1) and / or phenolic resin units obtained by condensation polymerization of cresols (b2) and formaldehydes (c2) The proportion of the structure derived from the naphthols (a1) contained in the structure is 2.5% or more and 40% or less when the mass of the novolac-type phenol resin is 100% by mass. Features.

  The weight average molecular weight of the novolak-type phenolic resin according to the present invention is not particularly limited, but is preferably 4000 to 50000, more preferably 5000 to 30000, and more preferably 7000 to 20000 in view of the performance of the photoresist composition and manufacturing handleability. Further preferred. When the weight average molecular weight is less than 4000, the sensitivity may be too high or the heat resistance may be poor, and when it is more than 50000, the sensitivity may be low. The weight average molecular weight of the novolak type phenolic resin according to the present invention is a molar ratio (formaldehydes (c2) / cresols (b2)) or a mass ratio (formaldehydes (c2) / (intermediate reactant + cresols (b2))). ) Can be adjusted. Specifically, the weight average molecular weight of the novolak type phenol resin is increased by increasing the blending amount of the formaldehydes (c2) as the crosslinking component, that is, by increasing the molar ratio or the weight ratio.

  The softening point of the novolak type phenolic resin of the present invention is preferably 140 ° C. or higher, more preferably 150 ° C. or higher, and most preferably 160 ° C. or higher in view of heat resistance. When the softening point is lower than 140 ° C., it is not preferable because it is inferior in heat resistance when used for a photoresist.

(Resist composition)
The photoresist using the novolak-type phenolic resin according to the present invention can be used for lithography in the production of highly integrated semiconductors and thin film transistor (TFT) materials for liquid crystals.

  The resist composition according to the present invention preferably contains 5-40% by mass, more preferably 10-25% by mass, of the novolac type phenol resin (A) obtained by the production method according to the present invention.

The resist composition according to the present invention preferably further contains a photosensitive agent (B). As the photosensitizer (B), known photosensitizers for photoresists containing novolak-type phenolic resins can be used. As the photosensitizer (B), a quinonediazide compound having a quinonediazide group is preferable, and a 1,2-quinonediazide compound or a derivative thereof is particularly preferable.
By using a quinonediazide compound, the exposed portion has a higher alkali dissolution rate due to the dissolution promoting effect, and conversely, the non-exposed portion has a lower alkali dissolution rate due to the dissolution inhibiting effect. Due to the difference, a sharp resist pattern with high contrast can be obtained.

  As the quinonediazide compound, known compounds conventionally used in quinonediazide-novolak resists can be used. Examples of the compound containing a quinonediazide group include compounds obtained by reacting naphthoquinonediazidesulfonic acid chloride, benzoquinonediazidesulfonic acid chloride, and the like with a compound having a functional group capable of undergoing a condensation reaction with these acid chlorides. preferable. Here, examples of the functional group capable of condensing with an acid chloride include a hydroxyl group and an amino group, and a hydroxyl group is particularly preferred. Examples of the compound having a hydroxyl group capable of condensing with acid chloride include hydroquinone, resorcin, 2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,4,4 '-Trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 2,2 ', 3,4,6'-pentahydroxybenzophenone, etc. Hydroxyphenyl alkanes such as hydroxybenzophenones, bis (2,4-dihydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, bis (2,4-dihydroxyphenyl) propane, 4,4 ′ , 3 ", 4" -tetrahydroxy-3,5,3 ', Hydroxytriphenylmethanes such as' -tetramethyltriphenylmethane, 4,4 ', 2 ", 3", 4 "-pentahydroxy-3,5,3', 5'-tetramethyltriphenylmethane These may be used alone or in combination of two or more.

  Specific examples of naphthoquinone diazide sulfonic acid chloride and benzoquinone diazide sulfonic acid chloride which are acid chlorides include, for example, 1,2-naphthoquinone diazide-5-sulfonyl chloride, 1,2-naphthoquinone diazide-4-sulfonyl chloride and the like are preferable. As mentioned.

  The blending amount of the photosensitizer (B) is preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight with respect to 100 parts by weight of the novolak type phenol resin (A). When the blending amount of the photosensitive agent (B) is less than 5 parts by weight, sufficient sensitivity as a photosensitive tree composition may not be obtained, and when it exceeds 50 parts by weight, a problem of precipitation of components occurs. This is not preferable.

  The resist composition of the present invention comprises a stabilizer such as an antioxidant, a plasticizer, and a surfactant, which are conventional components of the resist composition, in addition to the above-described novolak-type phenol resin (A) and photosensitive agent (B). Adhesion improvers, dissolution promoters, dissolution inhibitors and the like can be added.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

A method for measuring the characteristics used in the following examples is shown below.
[1] Novolak-type phenolic resin First, examples of novolac-type phenolic resin are shown. In addition, the analysis method and evaluation method of resin are as follows.
(1) Weight average molecular weight GPC measurement was performed under the following conditions to determine the weight average molecular weight in terms of polystyrene.
Model: HLC-8220 Tosoh Co., Ltd. Column: TSK-GEL H type G2000H × L 4
1 G3000H x L
One G4000H × L Measurement condition: Column pressure 13.5 MPa
Eluent: Tetrahydrofuran (THF)
Flow rate: 1 mL / min
Temperature: 40 ° C
Detector: Spectrophotometer (UV-8020) RANGE 2.56
WAVE LENGTH: 254nm
Injection volume: 100 μmL
Sample concentration: 5 mg / mL
(2) Alkali dissolution rate 3 g of novolak-type phenol resin was dissolved in 9 g of PGMEA (propylene glycol monomethyl ether acetate) to prepare a resin solution. These were filtered through a 0.2 micron membrane filter. This was coated on a 4 inch silicon wafer with a spin coater to a thickness of about 1.5 μm and dried on a hot plate at 110 ° C. for 60 seconds. Next, using a developing solution (1.60% tetramethylammonium hydroxide aqueous solution), the time until the film completely disappeared was measured. The value obtained by dividing the initial film thickness by the time until dissolution was taken as the dissolution rate.

Synthesis Example 1 P-cresol 108 g (1 mol), paraformaldehyde 60 g (2 mol) and pure water 44 g were placed in a 1000 mL glass flask equipped with a thermometer, a charging / distilling outlet and a stirrer, and nitrogen was blown into the flask. And stirred. At room temperature, 44 g of 25% caustic soda water was added, and the solution was slowly added dropwise so as not to exceed 50 ° C. while paying attention to heat generation. Then, it heated up to 50 degreeC in the water bath, and reacted for 4 hours. After completion of the reaction, pure water was added, the mixture was cooled to room temperature, and a 25% aqueous hydrochloric acid solution was added until the pH reached 4. After adding pure water and washing with water, the reaction product was obtained by standing and separation.

  To the obtained reaction product, 20 g of methanol and 463 g of 1-naphthol were added, and the temperature was raised to 60 ° C. with stirring in a nitrogen atmosphere to dissolve 1-naphthol. Then, 0.8 g of p-toluenesulfonic acid was gradually added while paying attention to heat generation, then heated to 70 ° C. on the oil bath and reacted for 4 hours, and further heated to 80 ° C. for 3 hours. Went. After completion of the reaction, pure water was added and washed with water. After dehydrating by raising the temperature to 185 ° C., steam distillation was performed to remove unreacted 1-naphthol and the like, and 345 g of an intermediate reaction product was obtained. The obtained intermediate reaction product has a weight average molecular weight of 730, the proportion of the trinuclear compound represented by the formula 1 is 43% in area% of the GPC measurement result, and the amount of unreacted 1-naphthol is 0.9%. Met. Further, 1-naphthol incorporated into the intermediate reactant by the reaction was 70% by mass with respect to 100% by mass of the intermediate reactant (70% is a theoretical value).

[Example 1]
In a glass flask having a capacity of 500 mL equipped with a thermometer, a charging / distilling outlet and a stirrer, 200 g (1.85 mol) of m-cresol, 133.3 g (1.23 mol) of p-cresol, intermediate synthesized in Synthesis Example 1 33.3 g of the reaction product, 157.1 g (2.22 mol) of 42% formalin, and 2.34 g of oxalic acid were added and reacted at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydrated, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 330 g of a novolac type phenol resin. The obtained novolac type phenol resin had a weight average molecular weight of 10,800 and an alkali dissolution rate of 254 angstroms / second.

[Example 2]
In a glass flask having a capacity of 500 mL equipped with a thermometer, a charging / distilling outlet and a stirrer, 200 g (1.85 mol) of m-cresol, 133.3 g (1.23 mol) of p-cresol, intermediate synthesized in Synthesis Example 1 66.7 g of the reaction product, 163.6 g of 42% formalin (2.50 mol) and 2.34 g of oxalic acid were added and reacted at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydration was performed, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 360 g of a novolac type phenol resin. The obtained novolak type phenol resin had a weight average molecular weight of 10,700 and an alkali dissolution rate of 218 angstroms / second.

Example 3
In a glass flask having a capacity of 500 mL equipped with a thermometer, a charging / distilling outlet and a stirrer, 200 g (1.85 mol) of m-cresol, 133.3 g (1.23 mol) of p-cresol, intermediate synthesized in Synthesis Example 1 100 g of the reaction product, 176.7 g (2.31 mol) of 42% formalin, and 2.34 g of oxalic acid were added and reacted at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydrated, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 390 g of a novolac type phenol resin. The obtained novolac type phenol resin had a weight average molecular weight of 11,500 and an alkali dissolution rate of 153 Å / sec.

Example 4
In a glass flask having a capacity of 500 mL equipped with a thermometer, a charging / distilling outlet and a stirrer, 200 g (1.85 mol) of m-cresol, 133.3 g (1.23 mol) of p-cresol, intermediate synthesized in Synthesis Example 1 100 g of the reaction product, 152.7 g (2.16 mol) of 42% formalin, and 2.33 g of oxalic acid were added, and the reaction was performed at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydrated, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 385 g of a novolac type phenol resin. The obtained novolac type phenol resin had a weight average molecular weight of 5000 and an alkali dissolution rate of 696 angstroms / second.

Example 5
In a glass flask having a capacity of 500 mL equipped with a thermometer, a charging / distilling outlet and a stirrer, 250 g (2.31 mol) of m-cresol, 62.5 g (0.58 mol) of p-cresol, and the intermediate synthesized in Synthesis Example 1 93.8 g of the reaction product, 165.7 g (2.35 mol) of 42% formalin, and 2.19 g of oxalic acid were added and reacted at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydration was performed, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 380 g of a novolac type phenol resin. The obtained novolac type phenol resin had a weight average molecular weight of 6000 and an alkali dissolution rate of 671 angstroms / second.

Example 6
In a 500 mL glass flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 153 g (1.41 mol) of m-cresol, 102 g (0.94 mol) of p-cresol, 37.8 g of 2,5-xylenol ( 0.31 mol), 2,4-xylenol 14.2 g (0.12 mol), intermediate reaction product 93 g synthesized in Synthesis Example 1, 42% formalin 142.9 g (2.03 mol), and oxalic acid 2. 17 g was added and reacted at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydration was performed, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 360 g of a novolac type phenol resin. The obtained novolak type phenol resin had a weight average molecular weight of 4500 and an alkali dissolution rate of 662 angstroms / second.

[Comparative Example 1]
In a glass flask having a capacity of 500 mL equipped with a thermometer, a charging / distilling outlet and a stirrer, 80 g (0.74 mol) of m-cresol, 120 g (1.11 mol) of p-cresol, 80.8 g of 42% formalin (1. 15 mol) and 0.7 g of oxalic acid were placed in a three-necked flask and reacted at 100 ° C. for 10 hours. Thereafter, the temperature was raised to 185 ° C. and dehydration was performed, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 150 g of a novolac type phenol resin. The obtained novolak type phenol resin had a weight average molecular weight of 5,700 and an alkali dissolution rate of 380 angstroms / second.

[Comparative Example 2]
In a 500 mL glass flask equipped with a thermometer, charging / distilling outlet and stirrer, m-cresol 100 g (0.93 mol), p-cresol 111.1 g (1.03 mol), 1-naphthol 11.1 g ( 0.08 mol), 90.1 g (1.28 mol) of 42% formalin, and 0.44 g of oxalic acid were added and reacted at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydration was performed, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 360 g of a novolac type phenol resin. The obtained novolac type phenol resin had a weight average molecular weight of 5200 and an alkali dissolution rate of 733 angstroms / second.

[Comparative Example 3]
In a 500 mL glass flask equipped with a thermometer, charging / discharging outlet and stirrer, m-cresol 50 g (0.46 mol), p-cresol 30 g (0.28 mol), 1-naphthol 20 g (0.14 mol) ), 46.44 g (0.66 mol) of 42% formalin and 0.2 g of oxalic acid were added, and the reaction was carried out at 100 ° C. for 20 hours. Thereafter, the temperature was raised to 185 ° C. and dehydration was performed, followed by distillation under reduced pressure at 30 torr for 2 hours to remove unreacted raw materials and the like to obtain 360 g of a novolac type phenol resin. The obtained novolac type phenol resin had a weight average molecular weight of 6,300 and an alkali dissolution rate of 705 angstroms / second.

[2] Photoresist Composition Next, examples of the photoresist composition using the novolak type phenolic resin of the present invention are shown. In addition, the evaluation method of a photoresist composition is as follows.

(1) Evaluation of sensitivity, remaining film ratio, and resolution A photoresist composition was coated on a 4-inch silicon wafer with a spin coater, dried on a hot plate at 110 ° C. for 60 seconds, and a coating film having a thickness of 1.5 μm. Formed. Thereafter, using a reduced projection exposure apparatus, the exposure time was changed stepwise to confirm the optimum exposure amount, and then exposure was performed so that the optimum exposure amount was obtained. Next, using a developer (2.38% tetramethylammonium hydroxide aqueous solution), development was performed for 60 seconds, followed by rinsing and drying.

The sensitivity was evaluated based on the following criteria by observing the pattern shape of the obtained pattern with a scanning electron microscope.
AA: An image can be formed at less than 3 mJ / cm 2.
A: An image can be formed at less than 5 mJ / cm 2.
B: An image can be formed at 5 to 60 mJ / cm2.

The remaining film ratio was determined from the remaining film thickness of the unexposed portion of the remaining film ratio. The remaining film ratio is a ratio between the film thickness of the photosensitive resin after development and the film thickness of the photosensitive resin before development, and is a value represented by the following formula.
Residual film ratio (%) = (photosensitive resin film thickness after development / photosensitive resin film thickness before development) × 100

Resolution The resolution was evaluated according to the following criteria using a test chart mask.
(Double-circle): 1.5 micro | micron | muline & space can be resolved.
○: 2.0 μ line & space can be resolved.
×: 2.0 μ line & space cannot be resolved.

(2) Evaluation of heat resistance The photoresist composition was applied onto a 4-inch silicon wafer by a spin coater and dried on a hot plate at 110 ° C. for 60 seconds to form a coating film having a thickness of 1.5 μm. Thereafter, using a reduced projection exposure apparatus, the exposure time was changed stepwise to confirm the optimum exposure amount, and then exposure was performed so that the optimum exposure amount was obtained. Subsequently, it developed for 60 second using the developing solution (2.38% tetramethylammonium hydroxide aqueous solution). The obtained silicon wafer was left on a hot plate at each temperature for 2 minutes, the shape of the resist pattern on the silicon wafer was observed with a scanning electron microscope, and the heat resistance was evaluated according to the following criteria.
A: The pattern shape can be maintained at 130 ° C.
○: The pattern shape can be maintained at 125 ° C.
X: The pattern shape cannot be maintained at 125 ° C.

Example 7
Using the novolac type phenol resin obtained in Example 1, a photoresist composition was prepared by the following method.
That is, 20 g of novolak type phenol resin and 5 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride were dissolved in 75 g of PGMEA (propylene glycol monomethyl ether acetate) to prepare a resist solution. This was filtered through a 0.2 micron membrane filter to obtain a photoresist composition.

[Examples 8 to 12, Comparative Examples 4 to 6]
A photoresist composition was prepared in the same manner as in Example 7 except that Examples 2 to 6 and Comparative Examples 1 to 3 were used in place of the novolak type phenol resin obtained in Example 1 as the novolak type phenol resin. Obtained.

  Table 1 below shows the analysis and evaluation results of the novolak type phenol resins of Examples 1 to 6 and Comparative Examples 1 to 3, and the photoresist compositions of Examples 7 to 12 and Comparative Examples 4 to 6.

Table 1 shows the following.
The novolak type phenol resin in which the proportion of m-cresol (a1) in the phenol component (a) in the molecules of Examples 1 to 6 is low is excellent in alkali dissolution rate and practical.

  The photoresist composition prepared using the novolac type phenol resin prepared by the two-stage method obtained in Examples 1 to 6 was obtained by comparing the novolac type phenol resin obtained in Comparative Examples 2 to 3 prepared by the one-stage method. Compared with the photoresist composition prepared by using, it had higher sensitivity, remaining film ratio, resolution and heat resistance in a balanced manner.

  In particular, the photoresist composition prepared using the novolak type phenol resin obtained in Example 3 was particularly excellent in the balance of the remaining film ratio, resolution, and heat resistance.

  As described above, the photoresist composition using the novolak-type phenolic resin of the present invention can be used for lithography and thin film film transistor (TFT) materials for liquid crystals when manufacturing highly integrated semiconductors. Can greatly contribute to improvement in yield and high integration.

  According to the present invention, a novolak-type phenolic resin that can be suitably used for a photoresist, and a photoresist comprising a photoresist composition using the phenolic resin has a higher level of high heat resistance, high sensitivity, and high residual film. It is possible to propose a novolak type phenolic resin capable of having a good balance between the ratio and the high resolution, a method for producing the same, and a photoresist composition containing the novolac type phenolic resin.

  The photoresist using the novolak type phenolic resin of the present invention has a high level of high heat resistance, high sensitivity, high residual film ratio and high resolution in a well-balanced manner, which is suitable for manufacturing high-definition LCDs and semiconductors. Can be used for

Claims (3)

A first step of reacting naphthols (a1), cresols (b1) and formaldehydes (c1) to obtain an intermediate reaction product containing 10 to 80% by mass of the trinuclear compound represented by formula 1,

A second step of removing the unreacted naphthols to a content of unreacted naphthols (a1) in the intermediate reactant obtained in the first step to 10% by mass or less;
A third step of obtaining a novolac-type phenol resin by reacting the intermediate reactant, cresols (b2) and formaldehydes (c2) treated in the second step ,
In the third step, when the total amount of the intermediate reactant and cresol (b2) treated in the second step is 100% by mass, the amount of the intermediate reactant is 5 to 50% by mass, and formaldehyde The molar ratio (formaldehyde / cresols) between the class (c2) and the cresol (b2) is 0.65 to 0.85,
A method for producing a novolak phenol resin for a photoresist, wherein the resulting novolak phenol resin has a weight average molecular weight of from 4,000 to 50,000 .   2. The photoresist according to claim 1, wherein in the first step, a blending amount of the naphthols (a1) is 1.0 to 10.0 moles with respect to 1 mole of the cresols (b1). For producing a novolac-type phenolic resin. A photoresist composition comprising a novolak-type phenolic resin for photoresist obtained by the production method according to claim 1 .