JP2017025236A - Novolac type phenolic resin, production method of the same, and photoresist composition comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novolac type phenolic resin and a production method of the novolac type phenolic resin capable of giving a good balance among high heat resistance, high sensitivity, a high residual film rate, and high resolution at higher levels when the resin is prepared into a photoresist composition, and exhibiting excellent storage stability when the resin is prepared into a photoresist composition, and to provide a photoresist composition comprising the novolac type phenolic resin.SOLUTION: The novolac type phenolic resin is obtained by the reaction of a phenol component (a1) comprising m-cresol and/or p-cresol, a phenol component (a2) comprising 2,3,5-trimethyl phenol and/or 3,5-xylenol, and a formaldehyde component (b) in the presence of an acid catalyst (c). The reaction is carried out in the presence of the acid catalyst (c) together with a mercapto group-containing compound as a cocatalyst (d).SELECTED DRAWING: None

Description

  The present invention relates to a novolak type phenol resin used for the production of a photoresist used for lithography in the production of semiconductors and LCDs, a method for producing the same, and a photoresist composition containing the novolac type phenol resin.

  In general, for a positive photoresist, a photosensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolac phenolic resin) are used. A positive type photoresist having such a composition exhibits high resolving power when developed with an alkaline solution, and is used for the production of semiconductors such as IC and LSI, and circuit substrates such as LCDs. In addition, novolak-type phenolic resins have high heat resistance due to the structure with many aromatic rings against dry etching after exposure, and so far contain novolak-type phenolic resins and naphthoquinone diazide photosensitizers. Many positive photoresists have been developed and put to practical use.

  The novolak type phenolic resin for photoresist is a resin obtained by reacting m-, p- or o-cresol and formaldehyde in the presence of an acid catalyst, in order to adjust or improve the characteristics of the photoresist. , M-, p- or o-cresol ratio and molecular weight have been studied. In particular, in a photoresist for a semiconductor, a phenol resin that maintains a high balance between high heat resistance, high sensitivity, a high residual film rate, and high resolution is regarded as important.

  As a method for improving the heat resistance, there are examples studied using alkylphenols such as xylenol and trimethylphenol. However, this method only slightly improves the heat resistance, and a novolak type for photoresist that meets the purpose. It is insufficient as a phenol resin.

  Patent Document 1 discloses that one or two selected from m-cresol, p-cresol, 3,5-xylenol and 2,3,5-trimethylphenol, and aldehydes are used to improve the photoresist characteristics. Is disclosed in which a high ortho novolac type phenol resin is produced by reacting at a temperature of 110 to 220 ° C. in the presence of an acid catalyst.

International Publication No. 2012/115029

  However, 3,5-xylenol or 2,3,5-trimethylphenol described in Patent Document 1 inhibits the reaction at the para-position due to the steric hindrance of the methyl group. Although effective, there is a problem that the crosslinking density is low and heat resistance is insufficient as a novolak type phenol resin for photoresists.

  Furthermore, in the field of LCDs and the like, the line width of images has become narrower with the progress of technologies such as TFT and STN, and the tendency for miniaturization has become 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 resolution, high heat resistance, high sensitivity, and a high residual film ratio is required, and the conventional positive photoresist cannot cope with the situation.

  Further, in the course of the study for solving the above problems, the present inventors have disclosed that novolac type phenol resins containing 3,5-xylenol and / or 2,3,5-trimethylphenol as a constituent component are photoresists. It was found that the storage stability when the composition was obtained was poor. Specifically, there is no problem with respect to the storage stability of a composition in which a general-purpose novolak type phenol resin composed of m-cresol, p-cresol and formaldehyde is dissolved in a solvent. 3,5-xylenol and / or 2 In the case of a composition using a novolac type phenol resin containing 1,3,5-trimethylphenol as a constituent component, it was found that the physical properties (alkali dissolution rate) change (deteriorate) with time. That is, from this, the novolak-type phenol resin having a specific chemical composition obtained by using 3,5-xylenol and / or 2,3,5-trimethylphenol has newly found a problem that storage stability is poor. .

  The present invention has been made in view of the above problems, and can have a high level of high heat resistance, high sensitivity, high residual film ratio and high resolution in a balanced manner when used as a photoresist composition, and An object of the present invention is to provide a novolak-type phenol resin excellent in storage stability when used as a photoresist composition, a method for producing the same, and a photoresist composition containing the novolak-type phenol resin.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a photoresist comprising a photoresist composition using a novolac-type phenolic resin obtained by using a specific promoter during the reaction. The present inventors have found that it has a high level of high heat resistance, high sensitivity, high residual film ratio and high resolution, and has achieved the present invention.

  Furthermore, the photoresist composition containing the novolak type phenol resin obtained by the above specific reaction method has a specific chemical composition obtained by using 3,5-xylenol and / or 2,3,5-trimethylphenol. In spite of a photoresist composition containing a novolac-type phenolic resin, the inventors have found that the deterioration of alkali dissolution rate with time is suppressed and the storage stability is excellent, and the present invention has been achieved.

That is, the present invention relates to the following matters.
(1) A phenol component (a1) composed of m-cresol and / or p-cresol, a phenol component (a2) composed of 2,3,5-trimethylphenol and / or 3,5-xylenol, and a formaldehyde component (b ) In the presence of an acid catalyst (c) in the presence of a mercapto group-containing compound which is a cocatalyst (d) together with the acid catalyst (c). It is related with the novolak type phenol resin characterized by having been performed by this.

(2) The present invention relates to the novolac type phenol resin according to (1), wherein the weight average molecular weight is 1000 or more.

(3) The present invention relates to a photoresist composition comprising the novolac type phenol resin described in (1) or (2) above.

(4) A phenol component (a1) composed of m-cresol and / or p-cresol, a phenol component (a2) composed of 2,3,5-trimethylphenol and / or 3,5-xylenol, and a formaldehyde component (b ) In the presence of an acid catalyst (c), the method comprising the step of reacting a mercapto group-containing compound that is a cocatalyst (d) together with the acid catalyst (c). The present invention relates to a method for producing a novolac type phenolic resin, characterized in that it is carried out in the presence.

  As described above, according to the present invention, when a photoresist composition is used, it can have a high level of balance between high heat resistance, high sensitivity, high residual film ratio, and high resolution, and the photoresist composition. It is possible to provide a novolak type phenol resin excellent in storage stability when prepared, a method for producing the same, and a photoresist composition containing the novolak type phenol 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

[Novolac type phenolic resin]
The novolak-type phenol resin of the present invention is obtained by subjecting a phenol component (a1), a phenol component (a2), and an aldehyde component (b) to a resin condensation reaction in the presence of an acid catalyst (c) and a cocatalyst (d). The obtained novolak type phenol resin, wherein the promoter (d) is a mercapto group-containing compound.

The weight average molecular weight of the novolak type phenolic resin of the present invention is not particularly limited, but is preferably 1000 or more, more preferably 1000 to 50000, and still more preferably 2000 to 30000, from the performance of the photoresist composition and the handling properties in production. , 3000-20000 are particularly preferred. Moreover, from a viewpoint of the remaining film rate of a photoresist composition, the resolution, and heat resistance, 7000-20000 are preferable and 7000-15000 are especially preferable. If the weight average molecular weight is less than 1000, the sensitivity may be too high and the heat resistance may be poor.
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, particularly preferably 160 ° C. or higher, from the viewpoint 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.

[Production of novolak-type phenolic resin]
<Phenol component (a1)>
The phenol component (a1) used in the production of the novolak type phenolic resin of the present invention comprises m-cresol and / or p-cresol. That is, the phenol component (a1) is either m-cresol alone, p-cresol alone, or a mixture of m-cresol and p-cresol.
In the present invention, the phenol component (a1) is preferably a mixture containing both m-cresol and p-cresol. In that case, the ratio of m-cresol and p-cresol in the phenol component (a1) ( m-cresol / p-cresol) is preferably 20/80 to 90/10, more preferably 40/60 to 80/20. The sensitivity can be adjusted by adjusting the ratio of m-cresol and p-cresol. When the ratio of m-cresol and p-cresol is in the above range, the resolution and the remaining film ratio are improved in the high sensitivity region, which is preferable.

<Phenol component (a2)>
The phenol component (a2) in the present invention comprises 2,3,5-trimethylphenol and / or 3,5-xylenol. That is, the phenol component (a2) is either 2,3,5-trimethylphenol alone, 3,5-xylenol alone, or a mixture of 2,3,5-trimethylphenol and 3,5-xylenol. .
The phenol component (a2) in the present invention is preferably 2,3,5-trimethylphenol alone from the viewpoint of heat resistance.

<Phenol component (a1) and phenol component (a2)>
In this invention, when the sum total of the mass of a phenol component (a1) and the mass of a phenol component (a2) is 100 mass%, the ratio of a phenol component (a2) becomes like this. Preferably it is 5-50 mass%, More preferably Is 10-30 mass%. When the mass ratio of the phenol component (a2), that is, 2,3,5-trimethylphenol and / or 3,5-xylenol is in the above range, the resolution and the remaining film ratio are improved in a high sensitivity region, which is preferable.
In the present invention, the phenol component (a1) and the phenol component (a2) are both essential components and are main components, but within the scope of the effect of the present invention, other phenols are contained as the phenol component. Also good. In that case, when the total of the mass of the phenol component (a1), the mass of the phenol component (a2) and the mass of other phenols is 100% by mass, the mass of the phenol component (a1) and the phenol component (a2) The ratio of the total mass with respect to the mass is preferably 50% by mass or more, more preferably 75% by mass or more, still more preferably 95% by mass or more, and most preferably 100% by mass. When the total content of m-cresol and / or p-cresol of the phenol component (a1) and 2,3,5-trimethylphenol and / or 3,5-xylenol of the phenol component (a2) is too small, Since resolution and heat resistance are inferior, it is not preferable.

  In the present invention, specific examples of other phenols include phenol, polyhydric phenol, o-cresol, xylenol, and trimethylphenol. As xylenol, structural isomers of 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, and 3,4-xylenol can be used, and as trimethylphenol, 2,3 An isomer such as 1,6-trimethylphenol can be used.

  Examples of the polyhydric phenol include divalent phenols such as catechol, resorcin, hydroquinone, 3-methylcatechol, 4-methylcatechol, 2-methylresorcinol, 4-methylresorcinol, methylhydroquinone, 3-ethylcatechol, 4 -Ethylcatechol, 2-ethylresorcinol, 4-ethylresorcinol, ethylhydroquinone, n-propylhydroquinone, isopropylhydroquinone, t-butylhydroquinone, 4-n-hexylresorcinol, 4-hexanoylresorcinol, 3,5-dimethylcatechol, 2,5-dimethylresorcinol, 2,3-diethylhydroquinone, 2,5-dimethylhydroquinone, 3,5-diethylcatechol, 2,5-diethylresorcinol, , 5-diethylhydroquinone, 3,5-diisopropylcatechol, 2,5-diisopropylresorcinol, 2,3-diisopropylhydroquinone, 2,5-diisopropylhydroquinone, 3,5-di-t-butylcatechol, 2,5-di (Poly) alkyl-substituted dihydric phenols such as -t-butylresorcinol, 2,3-di-t-butylhydroquinone, 2,5-di-t-butylhydroquinone; as trihydric phenols, pyrogallol, phloroglucinol 1,2,4-benzenetriol and the like. Of these polyphenols, resorcin is particularly desirable. These polyhydric phenols may be used alone or in combination of two or more.

<Formaldehyde component (b)>
In the present invention, the form (state) in which the formaldehyde component (b) is used is not particularly limited. In addition to an aqueous formaldehyde solution, a polymer that decomposes in the presence of an acid, such as paraformaldehyde and trioxane, to formaldehyde can be suitably used.
A formaldehyde aqueous solution that is easy to handle is preferable, and a commercially available 42% formaldehyde aqueous solution can also be used as it is.

<Molar ratio of phenol component (a1), phenol component (a2) and aldehyde component (b)>
In the present invention, when the phenol component (a1), the phenol component (a2) and the aldehyde component (b) are reacted, the total number of moles of the phenol component (a1) and the phenol component (a2) [(a1) The amount of the aldehyde component (b) is preferably 0.1 to 1.0 mol, more preferably 0.6 to 0.9 mol, with respect to the case where + (a2)] is 1 mol.

<Acid catalyst (c)>
The acid catalyst (c) in the present invention is not particularly limited as long as it is an acid capable of causing a polycondensation reaction between a phenol component and a formaldehyde component. For example, oxalic acid, benzenesulfonic acid, p-toluenesulfonic acid and Organic sulfonic acids such as methanesulfonic acid and inorganic acids such as hydrochloric acid and sulfuric acid can be used alone or in combination of two or more. In the method for producing a novolak type phenolic resin of the present invention, the acid catalyst (c) is particularly preferably sulfuric acid, oxalic acid or p-toluenesulfonic acid.

  In the method for producing the novolak type phenol resin of the present invention, the amount of the acid catalyst (c) used is about 0.01 to 1% by mass relative to the total mass of the phenol component (a1) and the phenol component (a2). It is. When a novolac type phenol resin is used in a photoresist composition, the acid catalyst remaining in the resin may affect the characteristics of the photoresist. The preferred amount used varies depending on the type, for example, 0.3 to 1.0% by mass in the case of oxalic acid, 0.05 to 0.1% by mass in the case of sulfuric acid, and p-toluenesulfonic acid. In this case, it is preferable to use about 0.05 to 0.5% by mass.

<Promoter (d)>
The method for producing a novolak type phenolic resin of the present invention is characterized in that the cocatalyst (d) is used together with the acid catalyst (c). The promoter (d) is not particularly limited as long as it is a mercapto group-containing compound. For example, ethanethiol, butanethiol, dodecanethiol, benzenethiol, toluenethiol, α-toluenethiol, phenethyl mercaptan, mercaptoethanol, 3 -Mercaptopropanol, thioglycerin, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, α-mercaptoisobutyric acid, methyl mercaptopropionic acid, ethyl mercaptopropionic acid, thioacetic acid, thiomalic acid, thiosalicylic acid, etc. It is done. The promoter (d) may be used alone or in combination of two or more. Of these, 3-mercaptopropionic acid is preferable from the viewpoints of reactivity and availability.

  Although the usage-amount of a co-catalyst (d) changes also with the kind, Preferably it is 0.01-5.0 mass% with respect to the total mass of a phenol component (a1) and a phenol component (a2). Preferably it is 0.1-1.0 mass%.

  By performing the condensation polymerization reaction in the presence of the mercapto group-containing compound as the promoter (d), the novolak type phenol resin of the present invention can be obtained. This is because the carbonyl compound in the mercapto group-containing compound produces hemithioacetal, thereby causing steric hindrance of the methyl group of 3,5-xylenol or 2,3,5-trimethylphenol, which is difficult to react by conventional methods. It is presumed that the reaction at the easy para position can proceed. When the mercapto group-containing compound as the promoter (d) is not used, the reaction at the para-position hardly occurs due to the steric hindrance of the methyl group of 3,5-xylenol or 2,3,5-trimethylphenol. It becomes difficult to obtain the novolac type phenol resin of the invention.

<Reaction solvent>
In the production method of the present invention, water contained in formaldehyde used as the aldehyde component (b) can play the role of a solvent. In addition to water, an organic solvent that does not affect the reaction is used if necessary. You can also. Examples of these 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. It is done.
The amount of these reaction solvents used is preferably 20 to 1000 parts by mass per 100 parts by mass of the reaction raw material.

<Reaction temperature>
The reaction temperature of the condensation polymerization reaction in the production method of the present invention is not particularly limited, and is usually 50 to 200 ° C, preferably 70 to 180 ° C, more preferably 80 to 170 ° C. If the temperature is lower than 50 ° C, the reaction is difficult to proceed, and if it exceeds 200 ° C, it becomes difficult to control the reaction, and it becomes difficult to stably obtain the desired novolak type phenol resin.

<Reaction time, reaction pressure>
The reaction time of the condensation polymerization reaction in the production method of the present invention is usually about 0.1 to 20 hours, although it depends on the reaction temperature. The reaction pressure for the condensation polymerization reaction is usually carried out under normal pressure, but it may be carried out under pressure or under reduced pressure.

<Post-processing>
The post-treatment after completion of the polycondensation reaction is to neutralize the acid catalyst by adding a base in order to completely stop the reaction, and subsequently to remove the acid catalyst (c) and the cocatalyst (d). It is preferable to carry out water washing by adding water.
The base for neutralizing the acid catalyst (c) is not particularly limited, and any acid can be used as long as it neutralizes the acid catalyst (c) and forms a salt that is soluble in water. is there. Examples 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, calcium carbonate and the like. Specific examples of the organic base include ammonia, trimethylamine, triethylamine, diethylamine, tributylamine and the like. Preferably organic amines are used. The amount of the base used depends on the amount of the acid catalyst (c), but is preferably used in such an amount that the acid catalyst (c) is neutralized and the pH in the reaction system falls within the range of 4-8. .

  The amount of water used in the water washing and the number of times of water washing are not particularly limited. In order to remove the acid catalyst (c) and the cocatalyst (d) to an amount that does not affect actual use, including the economic viewpoint, The number of times is preferably about 1 to 5 times. The temperature for washing with water is not particularly limited, but it is preferably 40 to 95 ° C. from the viewpoint of the efficiency and workability of removing the acid catalyst (c) and the cocatalyst (d). When the novolac type phenolic resin and the washing water are poorly separated during washing, it is effective to add a solvent or raise the washing temperature in order to reduce the viscosity of the mixed solution. The solvent species is not particularly limited, and any solvent can be used as long as it dissolves the novolak type phenol resin and lowers the viscosity.

  After the removal of the acid catalyst (c) and the cocatalyst (d), the temperature of the reaction system is usually raised to 130 to 230 ° C., for example, unremained in the reaction mixture under a reduced pressure of 20 to 50 torr. By distilling off volatile components such as reaction raw materials and organic solvents, the desired novolac phenolic resin can be suitably separated and recovered.

[Photoresist composition]
The photoresist composition of the present invention preferably contains 5-40% by mass, more preferably 10-25% by mass of the novolak type phenolic resin of the present invention.

  The photoresist composition of the present invention preferably contains a photosensitizer in addition to the novolak type phenol resin of the present invention. As the photosensitizer, those known as photosensitizers for photoresists containing novolak type phenol resins can be used, but quinonediazide compounds having a quinonediazide group are preferred, and 1,2-quinonediazide compounds or derivatives thereof are particularly preferred. 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 preferable.

  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.

  5-50 mass parts is preferable with respect to 100 mass parts of novolak-type phenol resins, and, as for the compounding quantity of a photosensitive agent, 10-40 mass parts is more preferable. When the blending amount of the photosensitizer is less than 5 parts by mass, sufficient sensitivity as a photosensitive tree composition may not be obtained, and when it is greater than 50 parts by mass, a problem of precipitation of components may occur. This is not preferable.

  The photoresist composition of the present invention is a stabilizer, such as an antioxidant, a plasticizer, a surfactant, and an adhesive, which are conventional components of a photoresist composition, in addition to the novolak type phenol resin and the photosensitive agent of the present invention. A property improver, a dissolution accelerator, a dissolution inhibitor and the like can be added.

[Usage]
The photoresist composition using the novolak-type phenolic resin of the present invention can be used for a thin film film transistor (TFT) material for lithography and liquid crystal when manufacturing a highly integrated semiconductor.

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

1. Synthesis of Novolak Type Phenolic Resin First, examples and comparative examples of the novolak type phenolic resin of the present invention are shown.

The analysis methods for the content of each component of the novolac-type phenol resin and the physical properties of the resin are as follows.
(1) Weight average molecular weight (GPC measurement method)
Model: HLC-8220 Tosoh Corporation 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: 254 nm and RI
Injection volume: 100 μL
Sample concentration: 5 mg / mL

(2) Evaluation method of alkali dissolution rate of novolak-type phenol resin 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 (2.38% 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.

(3) Storage stability test 3 g of novolak-type phenol resin was dissolved in 9 g of PGMEA (propylene glycol monomethyl ether acetate) to prepare a resin solution. The solution was stored at 40 ° C. for 1 week, 2 weeks, and 1 month, and the alkali dissolution rate was measured using the resin solution at the start of the test and after each storage. It shows that it is excellent in storage stability, so that the rate of change of the alkali dissolution rate is close to 100%. Here, the rate of change was within 10% from the start of the test.

[Example 1 Synthesis of novolak-type phenolic resin]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 2,3,5-trimethylphenol ( 0.294 mol), 95.04 g (1.331 mol) of 42% formaldehyde aqueous solution, 0.24 g of p-toluenesulfonic acid and 0.24 g of 3-mercaptopropionic acid were added, the temperature was raised to 100 ° C., and the reaction was performed for 10 hours. I let you. After completion of the reaction, the mixture was cooled to 90 ° C., 0.24 g of triethylamine was added, 240 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 195g of novolak type phenol resins.

[Example 2 Synthesis of novolak-type phenolic resin]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 2,3,5-trimethylphenol ( 0.294 mol), 42% aqueous formaldehyde solution 111.90 g (1.567 mol), 0.24 g of p-toluenesulfonic acid and 0.24 g of 3-mercaptopropionic acid were added, and the temperature was raised to 100 ° C. I let you. After completion of the reaction, the mixture was cooled to 90 ° C., 0.24 g of triethylamine was added, 240 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 198g of novolak-type phenol resins.

Example 3 Synthesis of novolak type phenolic resin
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 66.67 g (0.617 mol) of p-cresol, 2,3,5-trimethylphenol 33.33 g (0.245 mol), 42% aqueous formaldehyde solution 86.86 g (1.216 mol), p-toluenesulfonic acid 0.20 g and 3-mercaptopropionic acid 0.20 g were added, and the temperature was raised to 100 ° C. The reaction was allowed for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 0.20 g of triethylamine was added, 200 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 162 g of novolak-type phenol resins.

Example 4 Synthesis of novolac type phenol resin
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 66.67 g (0.617 mol) of p-cresol, 2,3,5-trimethylphenol 33.33 g (0.245 mol), 42% formaldehyde aqueous solution 91.97 g (1.288 mol), p-toluenesulfonic acid 0.20 g and 3-mercaptopropionic acid 0.20 g were added, and the temperature was raised to 100 ° C. The reaction was allowed for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 0.20 g of triethylamine was added, 200 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 170 g of novolak-type phenol resins.

Example 5 Synthesis of novolak type phenol resin
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 3,5-xylenol (0.327) Mol), 93.40 g (1.308 mol) of 42% formaldehyde aqueous solution, 0.24 g of p-toluenesulfonic acid and 0.24 g of 3-mercaptopropionic acid were added, and the temperature was raised to 100 ° C. and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 0.24 g of triethylamine was added, 240 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 194g of novolak type phenol resins.

Example 6 Synthesis of novolak type phenolic resin
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 3,5-xylenol (0.327) Mol), 98.07 g (1.373 mol) of 42% aqueous formaldehyde solution, 0.24 g of p-toluenesulfonic acid and 0.24 g of 3-mercaptopropionic acid were added, and the temperature was raised to 100 ° C. and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 0.24 g of triethylamine was added, 240 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 205 g of novolak-type phenol resins.

Example 7 Synthesis of novolak type phenolic resin
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 30 g of 3,5-xylenol (0.246) Mol), a 42% aqueous solution of formaldehyde 89.89 g (1.258 mol), 0.23 g of p-toluenesulfonic acid and 0.23 g of 3-mercaptopropionic acid were added, the temperature was raised to 100 ° C., and the reaction was carried out for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 0.23 g of triethylamine was added, 230 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 186g of novolak type phenol resins.

Example 8 Synthesis of novolak type phenolic resin
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 30 g of 3,5-xylenol (0.246) Mol), 94.38 g (1.321 mol) of a 42% formaldehyde aqueous solution, 0.23 g of p-toluenesulfonic acid and 0.23 g of 3-mercaptopropionic acid were added, and the temperature was raised to 100 ° C. and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 0.23 g of triethylamine was added, 230 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it vacuum-distilled at 30 torr for 2 hours, and obtained 196g of novolak type phenol resins.

[Comparative Example 1 Synthesis of Novolac Type Phenolic Resin]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 2,3,5-trimethylphenol ( 0.294 mol), 95.04 g (1.331 mol) of a 42% aqueous formaldehyde solution, and 0.84 g of oxalic acid were added, heated to 100 ° C., and allowed to react for 10 hours. After completion of the reaction, the mixture was heated to 185 ° C. and dehydrated, and then distilled under reduced pressure at 30 torr for 2 hours to obtain 192 g of a novolak type phenol resin.

[Comparative Example 2 Synthesis of Novolac Type Phenolic Resin]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 2,3,5-trimethylphenol ( 0.294 mol), 95.04 g (1.331 mol) of 42% aqueous formaldehyde solution, and 7.2 g of p-toluenesulfonic acid were added, heated to 100 ° C., and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 7.2 g of triethylamine was added, 240 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 195g of novolak type phenol resins.

[Comparative Example 3 Synthesis of Novolac Type Phenolic Resin (High Ortho Type)]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, m-cresol 100 g (0.926 mol), p-cresol 109.3 g (1.012 mol), 2,3,5-trimethylphenol 58.6 g (0.431 mol), 92% paraformaldehyde 47.75 g (1.373 mol), and oxalic acid 0.27 g were added, and the temperature was raised to 130 ° C. and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 90 ° C., 7.2 g of triethylamine was added, 240 g of ion-exchanged water was added, and the mixture was stirred and allowed to stand. The pH of the aqueous layer separated by allowing to stand was adjusted to 5.5 to 7.0, and the separated water was removed. This operation was performed twice. Then, after heating up to 185 degreeC and dehydrating, it distilled under reduced pressure at 30 torr for 2 hours, and obtained 195g of novolak type phenol resins.

[Comparative Example 4 Synthesis of Novolac Type Phenolic Resin]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 40 g of 3,5-xylenol (0.327) Mol), a 42% aqueous formaldehyde solution 98.07 g (1.373 mol) and oxalic acid 0.88 g were added, and the temperature was raised to 100 ° C. and allowed to react for 10 hours. After completion of the reaction, the mixture was heated to 185 ° C. and dehydrated, followed by distillation under reduced pressure at 30 torr for 2 hours to obtain 193 g of a novolak type phenol resin.

[Reference Example Synthesis of novolac type phenolic resin (m, p-Cr type)]
In a glass three-necked flask equipped with a thermometer, a charging / distilling outlet and a stirrer, 100 g (0.926 mol) of m-cresol, 100 g (0.926 mol) of p-cresol, 85.98 g of a 42% formaldehyde aqueous solution (1. 204 mol) and 0.70 g of oxalic acid were added, and the temperature was raised to 100 ° C. and reacted for 10 hours. After completion of the reaction, the mixture was heated to 185 ° C. and dehydrated, followed by distillation under reduced pressure at 30 torr for 2 hours to obtain 180 g of a novolak type phenol resin.

  As a result of analyzing the resin physical properties of the novolak type phenol resins obtained from Examples 1 to 8, Comparative Examples 1 to 4 and Reference Examples, Examples 1 to 8, Comparative Examples 1 to 4 and Reference Examples Table 2 shows the storage stability test results of a resin solution obtained by dissolving the obtained novolak type phenol resin in PGMEA (propylene glycol monomethyl ether acetate).

From the results in Table 2, the following can be understood.
The novolak type phenol resins of Examples 1 to 8 obtained using a mercapto group-containing compound as a cocatalyst for the reaction were preserved more than the novolak type phenol resins of Comparative Examples 1 to 4 obtained without using the cocatalyst. It turns out that it is excellent in stability.

  Specifically, a composition obtained by dissolving a general-purpose novolac type phenol resin obtained in a reference example composed of m-cresol, p-cresol, and formaldehyde in a solvent does not cause a problem regarding storage stability. , 5-xylenol and / or 2,3,5-trimethylphenol In the case of a composition in which the novolak type phenolic resin of Comparative Examples 1 to 4 was dissolved in a solvent, the physical properties (alkali dissolution rate) Has changed over time (deteriorated), resulting in poor stability. On the other hand, the composition in which the novolak type phenol resin of the present invention of Examples 1 to 8 obtained using a mercapto group-containing compound as a cocatalyst for the reaction was dissolved in a solvent was 3,5-xylenol and / or 2 , 3,5-trimethylphenol obtained using novolak-type phenolic resin having a specific chemical composition, the deterioration of alkali dissolution rate is suppressed over time, and storage stability is excellent. I understand.

  As a factor that the storage stability of the resins of Examples 1 to 8 is superior to the resins of Comparative Examples 1 to 4, in the resins of Examples 1 to 8, 3,5-xylenol or 2,3,5-trimethylphenol Since the reaction at the para position where the steric hindrance of the methyl group is likely to proceed is possible, formaldehyde is cross-linked at the para position, and the phenolic hydroxyl group is less likely to form a quinone structure, resulting in a structure in which the resin is not easily oxidized. It is estimated that this led to quality stabilization. Due to this effect, the photoresist using the novolak type phenolic resin of the present invention can be used for lithography and thin film film transistor (TFT) materials for liquid crystal when manufacturing highly integrated semiconductors, and improving the yield of semiconductors and liquid crystal products. Therefore, it is considered that it can greatly contribute to high integration and storage stability.

2. Photoresist Compositions Next, examples and comparative examples of photoresist compositions 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) Sensitivity, remaining film rate, resolution The photoresist composition was coated on a 4-inch silicon wafer with a spin coater and dried on a hot plate at 110 ° C. for 60 seconds to form a coating film having a thickness of 15000 mm. Thereafter, exposure was performed using a reduced projection exposure apparatus while changing the exposure time stepwise. Next, using a developer (2.38% tetramethylammonium hydroxide aqueous solution), development was performed for 60 seconds, followed by rinsing and drying.

(1-1) Sensitivity Sensitivity was evaluated according to 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 / cm ² .
(1-2) Remaining film ratio The remaining film ratio was calculated | required from the remaining film thickness of the unexposed part. 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
(1-3) Resolution The resolution was evaluated according to the following criteria using a test chart mask.
A: A 1.5 μm line and space can be resolved.
○: A 2.0 μm line and space can be resolved.
X: 2.0 μm line & space cannot be resolved.

(2) Heat resistance The photoresist composition was applied on a 4 inch silicon wafer with a spin coater to a thickness of about 15000 mm, and dried on a hot plate at 110 ° C. for 60 seconds. Thereafter, exposure was performed using a reduced projection exposure apparatus while changing the exposure time stepwise. 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 140 ° C.
A: The pattern shape can be maintained at 135 ° C.
X: The pattern shape cannot be maintained at 135 ° C.

[Example 9]
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), and this was filtered through a 0.2 micron membrane filter. A photoresist composition was obtained.
Table 3 shows the results of the evaluation of the characteristics of this photoresist composition.

[Examples 10 to 16, Comparative Examples 5 to 8]
Instead of using the novolak type phenol resin obtained in Example 1 as the novolak type phenol resin of Example 9, Examples 2 to 8 were used as the novolak type phenol resins of Examples 10 to 16 and Comparative Examples 5 to 8. And the photoresist composition was obtained similarly except having used the novolak type phenol resin obtained by Comparative Examples 1-4 and the reference example.
Table 3 shows the results of evaluating the characteristics of these photoresist compositions.

From the results in Table 3, the following can be understood.
The photoresist compositions of Examples 9 to 16 prepared using the novolak type phenol resins obtained in Examples 1 to 8 were comparative examples prepared using the novolak type phenol resin obtained in Comparative Examples 1 to 4. Compared with the photoresist compositions of 5 to 8, all performances of sensitivity, remaining film ratio, resolution and heat resistance were satisfied with a good balance. That is, it can be seen that the novolak type phenolic resin of the present invention is excellent in storage stability and satisfies all the performances of sensitivity, remaining film ratio, resolution and heat resistance in a balanced manner when used as a photoresist composition. In particular, the remaining film ratio, resolution, and heat resistance are particularly excellent for the photoresist compositions of Examples 10, 12, and 14 prepared using the novolak-type phenolic resins obtained in Examples 2, 4, and 6. .

  Moreover, the photoresist composition of a comparative example is inferior in heat resistance. As in the comparative example, in the novolak synthesized with only the acid catalyst, 3,5-xylenol or 2,3,5-trimethylphenol is inhibited by the steric hindrance of the methyl group, so that the reaction at the para position is inhibited. It becomes difficult to impart heat resistance. On the other hand, in the examples synthesized with the cocatalyst, steric hindrance of the methyl group of 3,5-xylenol or 2,3,5-trimethylphenol, which is difficult to react by the conventional method, easily occurs due to the effect of the cocatalyst. It is presumed that the reaction at the para position can proceed, thereby increasing the crosslinking density in the molecule, and providing resolution and heat resistance.

  Comparing Example 9 with Comparative Examples 5 and 6, the novolak of Example 1 of the present invention obtained by using a cocatalyst was obtained although the blending of raw materials and the molecular weight of the novolac type phenol resin were almost the same. Example 9 using a type phenol resin is excellent in sensitivity and heat resistance. Similarly, also in the example using 3,5-xylenol, when Example 14 and Comparative Example 8 were compared, it was carried out using the novolac type phenol resin of Example 6 of the present invention obtained by using a cocatalyst. It can be seen that Example 14 is excellent in resolution and heat resistance.

  According to the present invention, a novolac 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 resistance. It is possible to propose a novolak-type phenolic resin capable of having a balance between the remaining film ratio and 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 (4)

A phenol component (a1) composed of m-cresol and / or p-cresol, a phenol component (a2) composed of 2,3,5-trimethylphenol and / or 3,5-xylenol, and a formaldehyde component (b) A novolac-type phenolic resin obtained by reacting in the presence of an acid catalyst (c),
The novolak type phenol resin, wherein the reaction is carried out in the presence of a mercapto group-containing compound which is a cocatalyst (d) together with an acid catalyst (c).   The novolak type phenolic resin according to claim 1, wherein the weight average molecular weight is 1000 or more.   A photoresist composition comprising the novolac-type phenolic resin according to claim 1. A phenol component (a1) composed of m-cresol and / or p-cresol, a phenol component (a2) composed of 2,3,5-trimethylphenol and / or 3,5-xylenol, and a formaldehyde component (b) A process for producing a novolac-type phenolic resin comprising a step of reacting in the presence of an acid catalyst (c),
The said reaction is performed in presence of the mercapto group containing compound which is a promoter (d) with an acid catalyst (c), The manufacturing method of the novolak type phenol resin characterized by the above-mentioned.