KR102012053B1 - Photoresist resin composition - Google Patents

Abstract

It is characterized by using a novolak-type phenolic resin having a weight average molecular weight of 200 or more and less than 500 measured by GPC measurement using o-cresol alone or in combination with p-cresol as phenols, as an additive for improving photoresist sensitivity. The resin composition for photoresists to do.

Description

Resin composition for photoresist {PHOTORESIST RESIN COMPOSITION}

The present invention relates to a resin composition for photoresist.

The fine circuit pattern used for a liquid crystal display circuit or a semiconductor integrated circuit coats or apply | coats a photoresist composition uniformly to the insulating film or conductive metal film formed on the board | substrate, and exposes this photoresist composition in presence of a mask of a predetermined shape. And developing to obtain a photoresist film having a pattern of a desired shape, and then using the photoresist film having the pattern as a mask, the conductive metal film or the insulating film is removed, and the remaining photoresist film is removed. Such a photoresist composition is classified into a negative type and a positive type depending on whether the part to be exposed or the photoresist film of the exposed part is soluble or insoluble in the developer.

Generally, a positive photoresist composition contains the photosensitizer which has quinonediazide groups, such as a naphthoquinone diazide compound, and alkali-soluble resin (for example, novolak-type phenol resin). Such a positive photoresist composition exhibits high resolution in the exposure treatment and the development process by an alkaline solution, and therefore, semiconductor production such as IC and LSI, production of liquid crystal display devices such as LCD, production of printed discs, and the like. It is used. Moreover, the novolak type phenol resin has high heat resistance resulting from the structure which has many aromatic rings with respect to plasma dry etching. Therefore, many positive photoresists containing novolak-type phenol resins and naphthoquinone diazide-based photosensitizers have been developed and put to practical use, and have achieved great results.

Important characteristics in practical use of the photoresist composition for liquid crystal display circuits are the sensitivity, development contrast, resolution, adhesion to the substrate, residual film ratio, heat resistance, and circuit uniformity (CD uniformity) of the formed resist film. Especially, application of monomers, such as alkylphenols and aromatic aldehyde, is examined for high heat resistance. But none showed a slight improvement, but no dramatic effect was obtained. In addition, with the evolution of the photoresist formation technology, heat resistance at high temperatures is required even more. Patent Literature 1 discloses a method of treating a novolak-type phenol resin with a fractionation treatment in order to improve photoresist characteristics. Although the classification treatment is widely known in the art, it can be said that mass production is insufficient due to the low sensitivity, which is an important characteristic of the photoresist, and the long process time.

Japanese Patent Publication No. 2002-508415 Japanese Unexamined Patent Publication No. Hei 6-59445

An object of the present invention is to provide a resin composition for photoresist having high heat resistance, residual film ratio and sensitivity.

This object is achieved by the following invention [1].

[1] (A) 100 parts by weight of a novolak type phenolic resin containing no o-cresol component,

(B) The weight average molecular weight obtained by reacting phenols which consist of 30-100 weight% of o-cresols and 0-70 weight% of p-cresols with formaldehyde in presence of an acidic catalyst, and measured by GPC is 200 or more 1 to 10 parts by weight of novolac-type phenol resin less than 500,

(C) photosensitizers, and

(D) solvent

A resin composition for photoresist, characterized in that it contains.

According to the present invention, the sensitivity of the photoresist can be improved without lowering general physical properties such as heat resistance and residual film ratio.

EMBODIMENT OF THE INVENTION Below, the resin composition for photoresists of this invention is demonstrated in detail.

The resin composition for photoresists of the present invention,

(A) 100 parts by weight of a novolac phenolic resin containing no o-cresol component,

(B) The weight average molecular weight obtained by reacting phenols which consist of 30-100 weight% of o-cresols and 0-70 weight% of p-cresols with formaldehyde in presence of an acidic catalyst, and measured by GPC is 200 or more 1 to 10 parts by weight of novolac-type phenol resin less than 500,

(C) photosensitizers, and

(D) It contains a solvent.

Below, the novolak-type phenol resin (A) which does not contain the o-cresol component used for this invention is demonstrated.

The novolak-type phenol resin (A) which does not contain the o-cresol component used by this invention means the novolak phenol resin in which the monomer component which comprises a novolak-type phenol resin does not contain o-cresol.

The novolak type phenol resin (A) which does not contain the o-cresol component used by this invention is obtained by making phenols other than o-cresol react with aldehydes.

As phenols used as a monomer component which comprises the novolak-type phenol resin (A) used by this invention, if it is phenols other than o-cresol, it will not specifically limit. Examples include cresols such as phenol, m-cresol and p-cresol; 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol Elenols; Trimethyl phenols such as 2,3,5-trimethyl phenol and 2,3,6-trimethyl phenol; ethyl phenols such as o-ethyl phenol, m-ethyl phenol and p-ethyl phenol; Alkyl phenols such as isopropyl phenol, butyl phenol and p-tert-butyl phenol; Polyhydric phenols such as resorcin, catechol, hydroquinone, pyrogallol, and phloroglucin; Alkyl polyhydric phenols (all alkyl groups have 1 to 4 carbon atoms), such as alkyl resorcin, alkyl catechol, and alkyl hydroquinone, are mentioned. These can be used individually or in combination of 2 or more types.

Among the above phenols, a combination of m-cresol and p-cresol and a combination of m-cresol and 2,3,5-trimethylphenol are preferable. By using these combinations in the production of a novolak-type phenol resin (A) by adjusting the blending ratio of each component, various physical properties such as heat resistance, resolution, and residual film ratio of the resulting photoresist resin composition can be adjusted. When using a combination of m-cresol and p-cresol as phenols, the ratio of each component is not specifically limited, Preferably weight ratio (m-cresol / p-cresol) = 9/1-2/8, Furthermore, Preferably it is 8/2-3/7. When the ratio of m-cresol is small, the sensitivity of the resin composition for photoresists obtained will fall. Moreover, when the ratio of p-cresol is small, the heat resistance, the resolution, and the residual film rate of the resin composition for photoresist obtained will fall.

The aldehydes used in the novolak-type phenol resin used in the present invention are not particularly limited, but for example, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexa Methylenetetramine, furfural, glyoxal, n-butylaldehyde, caproaldehyde, allylaldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde and the like. Among these, using formaldehyde and paraformaldehyde is most preferable in the characteristic of the novolak-type phenol resin obtained.

In this invention, although the reaction molar ratio (A / P) of the said aldehyde (A) with respect to the said phenol (P) is not specifically limited, Preferably it is 0.5-1.5, More preferably, it is 0.6-1.2 to be.

By setting it as said molar ratio, the novolak-type phenol resin which has a weight average molecular weight especially suitable for photoresists can be obtained.

Next, the novolak-type phenol resin (B) used by this invention is demonstrated. The novolak-type phenol resin (B) is obtained by reacting a phenol consisting of 30 to 100% by weight of o-cresol and 0 to 70% by weight of p-cresol with formaldehyde in the presence of an acidic catalyst, and gel permeation chromatography. It is a novolak-type phenol resin whose weight average molecular weight measured by photography (GPC) is 200 or more and less than 500.

The novolak type phenol resin (B) used by this invention contains o-cresol or the combination of o-cresol and p-cresol as a monomer component. By adjusting the compounding ratio of each component of the said monomer component, the property, especially a sensitivity of the resin composition for photoresists obtained can be adjusted. The ratio of o-cresol and p-cresol is preferably a weight ratio (o-cresol / p-cresol) = 30/70 to 100/0.

It is preferable in the characteristic of the novolak-type phenol resin (B) to use that formaldehyde and paraformaldehyde are used as aldehydes used for novolak-type phenol resin (B).

The molecular weight of novolak-type phenol resin (B) is 200 or more and less than 500 weight average molecular weight measured based on GPC method. When the molecular weight is less than 200, the content of the low molecular weight component increases and becomes volatilized during baking of the resin composition for photoresist. When molecular weight is 500 or more, the effect of improving the sensitivity of the resin composition for photoresists will become weak.

The compounding quantity of (B) component used for this invention is 1-10 weight part with respect to 100 weight part of novolak-type phenol resins of (A) component, More preferably, it is 1-7 weight part. Component (B) is used in small amounts as an additive.

In addition, the said weight average molecular weight is computed based on the analytical curve prepared using the polystyrene standard material by the gel permeation chromatography (GPC) measurement. GPC measurement was performed on tetrahydrofuran as an elution solvent on the conditions of 1.0 mL / min of flow volume, and the column temperature of 40 degreeC.

The device,

Body: TOSOH, HLC-8020

Detector: manufactured by TOSOH, set at a wavelength of 280 nm, "UV-8011"

Analysis column: Showa Denko Co., Ltd., "SHODEX KF-802, KF-803, KF-805" was used, respectively.

As an acidic catalyst used in reaction of phenols and aldehydes at the time of synthesize | combining (A) and (B), For example, inorganic acids, such as hydrochloric acid, a sulfuric acid, phosphoric acid, a boric acid, oxalic acid, an acetic acid, paratoluenesulfonic acid Organic acids, such as these, are mentioned, These can be used individually and in mixture. In addition, an acidic catalyst which can be easily removed from the reaction system by decomposition, sublimation or the like at the time of monomer removal is preferable. Although the usage-amount differs according to the kind of catalyst, it is preferable to set the amount which becomes pH in the range of 1-6 in a reaction system.

The manufacturing method of the novolak-type phenol resin of this invention is demonstrated according to reaction sequence.

The reaction inject | pours phenols and an acidic catalyst into the reaction apparatus provided with a stirrer, a thermometer, and a heat exchanger, and heats up at predetermined temperature. After reaching the predetermined temperature, successive addition of formaldehyde is started. Sequential addition temperature and time can be suitably set according to the reactivity of the monomer to be used, and the objective characteristic of the novolak-type phenol resin obtained. Moreover, it can set so that manufacture of a novolak-type phenol resin may be stable and economical.

30-300 minutes are preferable, and, as for the sequential addition time of formaldehyde, More preferably, it is 60-180 minutes. By setting it as the said addition time, reaction can advance at an appropriate speed, without a rapid temperature rise.

Moreover, as for the sequential addition temperature of formaldehyde, 70-130 degreeC is preferable, More preferably, it is 90-110 degreeC. By setting it as said sequential addition temperature, reaction can be advanced at an appropriate speed | rate without a rapid temperature rise.

After completion of the sequential addition, the reaction can be continued as needed. In addition, at the time of sequential addition and reaction, reaction solvent can be added as needed. The kind of solvent will not be specifically limited if it is a solvent in which a phenol resin is dissolved. Examples include ketones such as methyl ethyl ketone and methyl isobutyl ketone, alcohols such as butanol, and ether alcohols such as ethoxyethanol.

After the reaction, dehydration and demonomerization can be performed under normal pressure and reduced pressure to obtain a novolac phenol resin. Although the conditions of dehydration and a demonomer are not limited, Considering the stability (deviation) and viscosity of the novolak-type phenol resin obtained, about 0-200 Torr is especially preferable, and the extraction temperature from a reaction apparatus is 130- 200 ° C. is preferred.

Next, the photosensitive agent (C) used for this invention is demonstrated.

Although it does not specifically limit as said photosensitive agent, For example, the following is mentioned.

(1) 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,6-trihydroxybenzo Phenone, 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3 ', 4,4', 6-pentahydroxybenzophenone, 2,2 ', 3,4,4'-pentahydroxybenzophenone, 2,2', 3,4,5-pentahydroxy Polyhydroxybenzoates such as benzophenone, 2,3 ', 4,4', 5 ', 6-hexahydroxybenzophenone, and 2,3,3', 4,4 ', 5'-hexahydroxybenzophenone Phenon,

(2) bis (2,4-dihydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4'-hydroxyphenyl Propane, 2- (2,4-dihydroxyphenyl) -2- (2 ', 4'-dihydroxyphenyl) propane, 2- (2,3,4-trihydroxyphenyl) -2- ( 2 ', 3', 4'-trihydroxyphenyl) propane, 4,4 '-{1- [4- [2- (4-hydroxyphenyl) -2-propyl] phenyl] ethylidene} bisphenol, 3 Bis [(poly) hydroxyphenyl] alkanes such as 3'-dimethyl- {1- [4- [2- (3-methyl-4-hydroxyphenyl) -2-propyl] phenyl] ethylidene} bisphenol ,

(3) tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl)- 4-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane , Bis (4-hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane Tris (hydroxyphenyl) methanes such as methyl substituents thereof,

(4) bis (3-cyclohexyl-4-hydroxyphenyl) -3-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxyphenyl) -2-hydroxyphenylmethane, bis (3-cyclo Hexyl-4-hydroxyphenyl) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -2-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy Hydroxy-2-methylphenyl) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-2-hydroxyphenyl ) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-3-methylphenyl) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-3-methylphenyl)- 3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-3-methylphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-2-hydroxyphenyl) -4-hydroxyphenyl Methane, bis (3-cyclohexyl-2-hydroxyphenyl) -2 -Hydroxyphenylmethane, bis (5-cyclohexyl-2-hydroxy-4-methylphenyl) -2-hydroxyphenylmethane, bis (5-cyclohexyl-2-hydroxy-4-methylphenyl) -4-hydroxy Bis (cyclohexyl hydroxyphenyl) (hydroxyphenyl) methane, such as oxyphenylmethane, or a methyl substituent, etc. Naphthoquinone-1,2-diazide-5-sulfonic acid or naphthoquinone-1,2-dia Fully ester compounds, partial ester compounds, amidates or partial amidates of quinonediazide group-containing sulfonic acids such as zide-4-sulfonic acid and orthoanthraquinonediazidesulfonic acid.

In the resin composition of this invention, although the compounding quantity of a photosensitive agent (C) is not specifically limited, It is 5-70 weight part normally with respect to 100 weight part of novolak-type phenol resins (A), Preferably it is 10-50 weight part. When there is much compounding quantity of the photosensitizer, the sensitivity of the resin composition for photoresists obtained will fall, and when there is little, the photoresist which is faithful to a mask pattern will not be obtained.

Next, the solvent (D) used by this invention is demonstrated.

As said solvent, ethylene glycol alkyl ethers, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol di, for example Diethylene glycol dialkyl ethers such as ethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, ethylene glycol alkyl ether acetates such as methyl cellosolve acetate, and ethyl cellosolve acetate, and propylene glycol monomethyl Propylene glycol alkyl ether acetates such as ether acetate, propylene glycol monoethyl ether acetate and propylene glycol monopropyl ether acetate, ketones such as acetone, methyl ethyl ketone, cyclohexanone and methyl amyl ketone, and cyclic ethers such as dioxane And 2-hydroxypropion Methyl acid, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl oxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3 Esters such as -methyl-3-methoxybutyl acetate, ethyl formate, ethyl acetate, butyl acetate, methyl acetoacetate and ethyl acetoacetate. These may be used individually by 1 type, and may mix and use 2 or more types.

Although content of the said solvent is not specifically limited, It is preferable to adjust so that solid content concentration may be 30 to 65 weight% with respect to the whole resin composition. By making solid content concentration into the said range, the fluidity | liquidity of a resin composition can be made favorable and a uniform resist film can be obtained.

Moreover, the resin composition of this invention can contain various additives, such as surfactant, an adhesion improving agent, a dissolution accelerator, in addition to the component demonstrated above.

Although it does not specifically limit as a preparation method of the resin composition of this invention, In the case of not adding a filler and a pigment to a resin composition, it only needs to mix and stir the said component by a conventional method, and when adding a filler and a pigment What is necessary is just to disperse | distribute and mix using dispersing apparatuses, such as a dissolver, a homogenizer, and three roll mills, for example. Moreover, you may filter using a mesh filter, a membrane filter, etc. further as needed.

By exposing through the mask to the resin composition of this invention obtained in this way, a structural change arises in a resin composition in an exposure part, and the solubility with respect to alkaline developing solution can be promoted. On the other hand, in the non-exposed part, since the low solubility with respect to alkaline developing solution is maintained, the resist function can be provided by the difference in the solubility which generate | occur | produced in this way.

However, the novolak-type phenol resins used for high heat resists are generally high molecular weight, and it is difficult to prepare resists having both heat resistance and sensitivity. By adding a small amount of the novolak-type phenol resin (B) synthesize | combined by this invention, a sensitivity can be improved, without reducing characteristics, such as heat resistance of a resin composition.

Example

Hereinafter, an Example demonstrates this invention. However, the present invention is not limited by these examples. In addition, "part" described in a synthesis example, an Example, and a comparative example shows a "weight part" and "%" represents the "weight%." In addition, content of a free monomer is computed from the area ratio by GPC measurement.

1. Synthesis of Novolac Phenolic Resin (B)

Synthesis Example 1

1000 parts of o-cresols and 5 parts of oxalic acid were poured into the 3-liter four-necked flask provided with the stirrer, the thermometer, and the heat exchanger, and it heated up to internal temperature 97-103 degreeC. After reaching the temperature, 750 parts of 37% formalin (injection molar ratio to total phenols, formalin (A) / total phenols (C) = 1.000) were added for 3 hours while maintaining the internal temperature of 97 to 103 ° C, followed by 2 After performing time reflux reaction, dehydration and demonomerization were performed to 180 degreeC under normal pressure, and 800 parts of novolak-type phenol resins (1) were obtained. Obtained resin was the weight average molecular weight 400.

Synthesis Example 2

500 parts of o-cresols, 500 parts of p-cresols, and 5 parts of oxalic acid were injected | poured to the 3-liter four-necked flask provided with the stirrer, the thermometer, and the heat exchanger, and it heated up to internal temperature 97-103 degreeC. After reaching the temperature, 750 parts of 37% formalin (injection molar ratio to all phenols, A / C = 1.000) were added for 3 hours while maintaining the internal temperature of 97 to 103 ° C, and then refluxed for 2 hours, Under normal pressure, dehydration and demonomerization were performed to 180 degreeC, and 850 parts of novolak-type phenol resins (2) were obtained. The weight average molecular weight of obtained resin was 400.

2. Preparation of resin composition for photoresist

Example 1

5 parts by weight of the novolak-type phenol resin (1) synthesized in Synthesis Example 1 was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 25,000, and naphthoquinone-1,2 20 parts by weight of 2,3,4-trihydroxybenzophenone ester of -diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by a membrane filter having a pore diameter of 1.0 μm. Filtration was carried out to prepare a resin composition for positive photoresist.

Example 2

5 parts by weight of novolak-type phenol resin (2) synthesized in Synthesis Example 2 was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 25,000, and naphthoquinone-1,2 20 parts by weight of 2,3,4-trihydroxyphenzophenone ester of -diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by a membrane having a pore diameter of 1.0 mu m. It filtered using the filter and prepared the resin composition for positive photoresists.

Example 3

5 parts by weight of the novolak-type phenol resin (1) synthesized in Synthesis Example 1 was added to 100 parts by weight of a resin having m-cresol / 2,3,5-trimethylphenol = 8/2 and Mw = 20,000. 20 parts by weight of 2,3,4-trihydroxybenzophenone ester of quinone-1,2-diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by pore diameter. It filtered using the 1.0 micrometer membrane filter, and prepared the resin composition for positive photoresists.

Example 4

5 parts by weight of the novolak-type phenol resin (2) synthesized in Synthesis Example 2 was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 20,000, naphthoquinone-1,2 20 parts by weight of 2,3,4-trihydroxybenzophenone ester of -diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by a membrane filter having a pore diameter of 1.0 μm. Filtration was carried out to prepare a resin composition for positive photoresist.

3. Synthesis of Novolac Phenolic Resin (Comparative Objects of B)

Comparative Synthesis Example 1

500 parts of o-cresols, 500 parts of p-cresols, and 5 parts of oxalic acid were injected | poured to the 3-liter four-necked flask provided with the stirrer, the thermometer, and the heat exchanger, and it heated up to internal temperature 97-103 degreeC. After reaching the temperature, 688 parts of 37% formalin (injection molar ratio A / C = 1.100 to all phenols) were added for 3 hours while maintaining the internal temperature of 97 to 103 ° C, followed by refluxing for 2 hours, followed by atmospheric pressure. Dehydration and demonomerization were performed to 180 degreeC below, and 850 parts of novolak-type phenol resins (3) were obtained. The weight average molecular weight of obtained resin was 600.

Comparative Synthesis Example 2

500 parts of o-cresols, 500 parts of p-cresols, and 5 parts of oxalic acid were injected | poured to the 3-liter four-necked flask provided with the stirrer, the thermometer, and the heat exchanger, and it heated up to internal temperature 97-103 degreeC. After reaching the temperature, 750 parts of formalin 37% (injection molar ratio A / C = 1.200 to all phenols) were added for 3 hours while maintaining the internal temperature of 97 to 103 ° C, followed by refluxing for 2 hours, followed by atmospheric pressure. Dehydration and demonomerization were performed to 180 degreeC below, and 850 parts of novolak-type phenol resins (4) were obtained. The weight average molecular weight of obtained resin was 1200.

4. Preparation of Photoresist Composition

Comparative Example 1

2,3,4-trihydroxybenzophenone ester of naphthoquinone-1,2-diazide-5-sulfonic acid was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 25,000. 20 weight part was mixed, and it melt | dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), and filtered using the membrane filter of 1.0 micrometer of pore diameters, and prepared the resin composition for positive type photoresists.

Comparative Example 2

5 parts by weight of a novolac-type phenol resin (3) synthesized in Comparative Synthesis Example 1 was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 25,000, naphthoquinone-1, 20 parts by weight of 2,3,4-trihydroxybenzophenone ester of 2-diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by a membrane having a pore diameter of 1.0 μm. It filtered using the filter and prepared the resin composition for positive photoresists.

Comparative Example 3

5 parts by weight of a novolak-type phenol resin (4) synthesized in Comparative Synthesis Example 2 was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 25,000, naphthoquinone-1, 20 parts by weight of 2,3,4-trihydroxybenzophenone ester of 2-diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by a membrane having a pore diameter of 1.0 μm. It filtered using the filter and prepared the resin composition for positive photoresists.

Comparative Example 4

12 parts by weight of the novolak-type phenol resin (1) synthesized in Synthesis Example 1 was added to 100 parts by weight of a resin having m-cresol / p-cresol = 5/5 and Mw = 25,000, and naphthoquinone-1,2 20 parts by weight of 2,3,4-trihydroxybenzophenone ester of -diazide-5-sulfonic acid was mixed and dissolved in 300 parts of propylene glycol monomethyl ether acetate (PGMEA), followed by a membrane filter having a pore diameter of 1.0 μm. Filtration was carried out to prepare a resin composition for positive photoresist.

In addition, the weight average molecular weight of a novolak-type phenol resin is computed based on the analytical curve created using the polystyrene standard material by the gel permeation chromatography (GPC) measurement. GPC measurement was carried out under tetrahydrofuran as the elution solvent, under the conditions of a flow rate of 1.0 mL / min and a column temperature of 40 ° C.

The device,

Body: TOSOH, HLC-8020

Detector: manufactured by TOSOH, set at a wavelength of 280 nm, "UV-8011"

Analytical column: Manufactured by Showa Denko, 「SHODEX KF-802, KF-803, KF-805」

Were used respectively.

The characteristic evaluation shown below was performed using the photoresist resin composition obtained in Examples 1-4 and Comparative Examples 1-4. The results are shown in Table 1.

4. Evaluation method of characteristics

(1) Evaluation method of heat resistance

The resin composition for photoresist was apply | coated so that the film thickness at the time of drying might be set to 1.5 micrometers on a hexamethyldisilazane treated silicon wafer, and it dried at 110 degreeC for 100 second on a hotplate. Then, it exposed through the test chart mask using the reduced projection exposure apparatus, and developed for 60 second using the developing solution (2.38% tetramethylammonium hydroxide aqueous solution). The obtained silicon wafer was left to stand on a hot plate having a different temperature for 3 minutes, and the shape of the resist pattern on the silicon wafer was observed with a scanning electron microscope, and the temperature at which the normal resist pattern could not be obtained was made into a heat resistant temperature.

(2) measuring method of sensitivity

The resin composition for photoresist was apply | coated to a 4-inch silicon wafer with a spin coater so that it might be set to about 1 micrometer, and it dried for 100 second on the 110 degreeC hotplate. Subsequently, a test chart mask was stacked on this silicon wafer, and 20 mJ / cm 2, 40 mJ / cm 2, 60 mJ / cm 2 and 80 mJ / cm 2 ultraviolet rays were irradiated, respectively, to use a developer (2.38% tetramethylammonium hydroxide aqueous solution). And developed for 60 seconds. The following references | standards evaluated the obtained pattern by observing a pattern shape with a scanning electron microscope.

An image can be formed at less than A 20 mJ / cm 2.

The image can be formed at B 20 mJ / cm 2 or more and less than 40 mJ / cm 2.

The image can be formed at C 40 mJ / cm 2 or more and less than 60 mJ / cm 2.

An image can be formed at D 60 mJ / cm 2 or more and less than 80 mJ / cm 2.

No image can be formed above E 80 mJ / cm 2.

It is preferable that the sensitivity of a resist is A or B area | region in the process, and when it becomes C or more, sensitivity will become too low and use will become difficult.

(3) residual film rate

The resin composition was applied on a 4 inch silicon wafer with a spin coater to a thickness of about 1 μm, and dried for 100 seconds on a 110 ° C. hot plate. The wafer was immersed in a developing solution (2.38% tetramethylammonium hydroxide aqueous solution) for 60 seconds, washed with water, and dried for 100 seconds on a 110 degreeC hotplate. The film thickness after immersion in the developer was expressed as a percentage of the film thickness before immersion in the developer. Therefore, a large residual film ratio indicates good residual film properties.

From the result of Table 1, Examples 1-4 are the composition for photoresists of this invention, and compared with Comparative Examples 1-4 which do not use this, it was confirmed to improve a sensitivity, without reducing various physical properties, such as heat resistance.

Since the resin composition of the comparative example 1 did not use the novolak-type phenol resin (B) for a sensitivity improvement, the result was low sensitivity.

The resin compositions of Comparative Examples 2 and 3 had a high molecular weight of the novolak-type phenol resin (B) for sensitivity improvement and a small sensitivity improvement effect.

Since the resin composition of the comparative example 4 had many addition amounts of the novolak-type phenol resin (B) for sensitivity improvement, the residual film rate fell significantly.

By adding an appropriate amount of novolak-type phenol resin (B) having a predetermined monomer configuration and molecular weight, it is possible to improve the sensitivity without lowering the overall physical properties of the resist.

Since the resin composition for photoresists of this invention using the novolak-type phenol resin of this invention has all the physical properties of resists, such as favorable thermal stability, and is highly sensitive, it manufactures the microcircuits of a liquid crystal display device circuit and a semiconductor integrated circuit. It can be used preferably.

Claims (1)

(A) 100 parts by weight of a novolac phenolic resin containing no o-cresol component,
(B) The weight average molecular weight obtained by reacting phenols which consist of 30-100 weight% of o-cresols and 0-70 weight% of p-cresols with formaldehyde in presence of an acidic catalyst, and measured by GPC is 200 or more 1 to 10 parts by weight of novolac-type phenol resin less than 500,
(C) photosensitizers, and
(D) solvent
A resin composition for photoresist, characterized in that it contains.