TW201403229A - Photoresist composition, photoresist and manufacturing of liquid crystal device - Google Patents

Abstract

This invention provides a resin composition for potoresist that has a superior balance among sensitivity, pattern shape, resolution, and residual film. The resin composition for potoresist of this invention is characterized by comprising: (A) a high ortho phenolic novolak (high-orthonovolac) type phenolic resin, which has an ortho rate more than 23% and is obtained by letting phenols that contains M-cresol, p-cresol and 2,5 - dimethyl phenol to react with aldehyde in the present of acid catalyst at a temperature between 110 and 220 degrees Celsius; (B) Naphthoquinone diazide derivatives; and (C) a solvent.

Description

Resin composition for photoresist, photoresist, and method of manufacturing liquid crystal device

The present invention relates to a resin composition for a resist, a photoresist, and a method for producing a liquid crystal device.

A circuit pattern such as a liquid crystal display device circuit or a semiconductor integrated circuit is formed by the following method. First, a photoresist composition is uniformly coated or coated on an insulating film or a conductive metal film formed on a substrate. Next, the applied photoresist composition is exposed and developed in the presence of a mask of a specific shape, thereby producing a photoresist pattern of a target shape. Thereafter, a photoresist film formed with a pattern is used as a mask to remove the metal film or the insulating film. Next, the remaining photoresist film is removed to form a fine circuit on the substrate. Further, the photoresist composition is classified into a positive type in the case of forming a soluble photoresist film, and is classified as a negative type in the case of forming an insoluble photoresist film.

In general, the positive-type resist composition uses a sensitizing agent having a quinonediazide group such as a naphthoquinone diazide compound and an alkali-soluble resin (for example, a novolac type phenol-based resin). Since the positive-type photoresist composition having such a composition exhibits high resolution by development using an alkaline solution after exposure, it is used for semiconductor manufacturing such as ICs and LSIs, and manufacturing of liquid crystal display screen devices such as LCDs and printing original plates. Manufacturing, etc.

Further, the novolac type phenol-based resin has high heat resistance due to a structure containing a large amount of aromatic rings for plasma dry etching. Therefore, a large number of positive-type photoresists containing a novolac type phenol-based resin and a naphthoquinone diazide-type sensitizer have been developed and applied, and have been obtained so far. Results.

From a practical point of view, the important characteristics required by the industry for the photoresist composition for a liquid crystal display device circuit are the sensitivity of the formed photoresist film, development contrast, resolution, adhesion to the substrate, residual film ratio, and heat resistance. Sex, and circuit uniformity (CD uniformity).

In particular, the photoresist composition for a thin film transistor liquid crystal display device is required to have a higher sensitivity because it is characterized by a large area of the substrate and thus a long exposure time on the production line. Further, since the sensitivity is inversely proportional to the residual film ratio, it is shown that the residual film ratio tends to decrease if the sensitivity is high.

In the positive-type photoresist for a liquid crystal display device circuit, a novolac type phenol-based resin obtained by the following reaction is used: a phenol such as m-p-cresol and an aldehyde such as formaldehyde are reacted in the presence of an acid catalyst. Further, in order to adjust or enhance the characteristics of the photoresist, research has been conducted on the ratio of the ratio of the phenols to the p-cresol, the type of the raw material phenols, the molecular weight of the phenol resin, and the molecular weight distribution.

As a technique for adjusting or improving the characteristics of the photoresist, there are, for example, the techniques described in Patent Documents 1 and 2.

Patent Document 1 discloses a phenol-based resin for a photoresist having a ratio of an ortho-bond/para-position bond (O/P ratio) between the internuclear methylene bonds and a specific value of the dinuclear component. Further, Patent Document 1 discloses that a positive photoresist having a high ortho-type novolak resin having a small dinucleotide component is used in order to improve the photoresist characteristics. According to the photoresist described in Patent Document 1, the image forming ability (pattern shape) is excellent, the heat resistance and the sensitivity are good, and the oven contamination by the low molecular weight volatile component is small in the drying step of the photoresist coating film. Good workability is obtained.

Patent Document 2 discloses a method of separating a novolac resin and providing a film-forming novolak resin which exhibits a faster dissolution rate, a faster photospeed in a photosensitive composition, and excellent lithographic properties. . According to the technique described in Patent Document 2, the novolak resin is subjected to fractionation treatment in order to improve the photoresist characteristics, and the method is applied to the present technology. It is more common for practitioners in the field.

[Patent Document 1] Japanese Patent Laid-Open No. 07-110576

[Patent Document 2] Japanese Patent Publication No. 2002-508415

Previously, in order to increase the sensitivity of the photoresist, the molecular weight of the novolak resin was lowered. However, when the molecular weight of the novolak resin is lowered, the heat resistance is deteriorated, and the residual film ratio of the unexposed portion is lowered, and the difference in the dissolution rate from the exposed portion cannot be obtained. Therefore, the development contrast between the exposed portion and the unexposed portion is lowered. Bad conditions such as reduced resolution.

On the other hand, when the molecular weight of the novolak resin is increased, the heat resistance or the resolution is improved, but there is a problem that the sensitivity is lowered.

That is, according to the prior art, by improving any of various photoresist characteristics such as heat resistance, residual film ratio, and resolution, some characteristics may cause some problems. Therefore, a resin composition for a photoresist for a liquid crystal display device circuit which is balanced and excellent in various photoresist characteristics such as excellent sensitivity, residual film ratio, development contrast, resolution, adhesion to a substrate, and uniformity of circuit line width has not been obtained. .

Further, compared with the applications of Patent Documents 1 and 2, the technical level required for various characteristics such as sensitivity, pattern shape, resolution, and residual film property of the resist resin composition is improved.

Therefore, an object of the present invention is to provide a resin composition for a photoresist which is excellent in balance between sensitivity, pattern shape, resolution, and residual film property.

The inventors of the present invention provide a resin composition for a photoresist having a good balance between sensitivity, pattern shape, resolution, and residual film properties, and composition or blending of monomers. Various manufacturing conditions of the ortho-ration ratio of the novolac type phenol-based resin have been intensively studied. As a result, it was found that, in the case of the monomer obtained by mixing m-cresol and p-cresol, a good sensitivity cannot be obtained, and there is no such a pattern shape. In addition, when the ortho-ration ratio of the novolak-type phenol-based resin is, for example, a resist resin composition exhibiting a low value of about 20%, a good pattern shape, residual film property, and resolution cannot be obtained.

Therefore, in view of the above, the inventors of the present invention have found that in order to obtain a resin composition for photoresist which is excellent in balance between sensitivity, pattern shape, resolution, and residual film property, the present invention has been completed by using the following materials: A novolac type phenol-based resin having a relative ratio of m-cresol, p-cresol and 2,5-xylenol as an essential component, and an ortho-ation ratio of a specific value or more, and a naphthoquinone diazide derivative It is more effective to use together with the solvent.

According to the invention, there is provided a resin composition for a photoresist comprising: (A) a high ortho-novolak-type phenol-based resin, which is a phenol containing m-cresol, p-cresol and 2,5-xylenol And the aldehydes are obtained by reacting in the presence of an acid catalyst at a temperature of 110 ° C or more and 220 ° C or less, and the ortho-position ratio thereof is 23% or more; (B) a naphthoquinone diazide derivative; (C) Solvent.

Further, according to the present invention, it is possible to provide a photoresist which is obtained by using a resin composition for a photoresist.

Further, according to the present invention, there is provided a method of producing a liquid crystal device comprising the step of performing photolithography using the resin composition for a photoresist.

According to the present invention, a resin composition for a photoresist which is excellent in balance between sensitivity, pattern shape, resolution, and residual film property can be obtained.

Hereinafter, the resin composition for a photoresist of the present embodiment will be described in detail.

<Resist composition for photoresist>

The resistive resin composition of the present embodiment contains: (A) a high-ortho-novolak-type phenol-based resin, which contains m-cresol (hereinafter also referred to as "m-cresol") and p-cresol (hereinafter also The phenols and aldehydes of "p-cresol" and 2,5-xylenol are obtained by reaction in the presence of an acid catalyst at a temperature of 110 ° C or higher and 220 ° C or lower, and are ortho-formed. The rate is 23% or more; (B) a naphthoquinonediazide derivative; and (C) a solvent. As a result, a resin composition for a photoresist which is excellent in balance between sensitivity, pattern shape, resolution, and residual film property is obtained. Further, the resist resin composition of the present embodiment is preferably used as a positive resist.

First, the resin composition for a photoresist according to the present embodiment is characterized by a good balance between sensitivity, pattern shape, resolution, and residual film properties. Further, the resin composition for a photoresist according to the present embodiment is preferably used as a resin composition for a positive resist. Hereinafter, a case where the resist resin composition is used as a positive photoresist will be described as an example.

Hereinafter, the resin composition for a photoresist of the present embodiment will be described in detail. In the resistive resin composition of the present embodiment, (A) a high-ortho-novolak-type phenol-based resin having an ortho-ration ratio of 23% or more can be used. The (A) ortho-novolak-type phenol-based resin having a ortho-ration ratio of 23% or more is a phenol and an aldehyde containing m-cresol, p-cresol and 2,5-xylenol in an acid catalyst. A resin obtained by reacting at a temperature of 110 ° C or higher and 220 ° C or lower.

(A) The high-ortho- novolak-type phenol-based resin having an ortho-ration ratio of 23% or more can be preferentially caused to react in the vicinity of the phenolic hydroxyl group by first reacting at a high temperature of 110 ° C or higher and 220 ° C or lower. Therefore, it is easy to obtain a resin having a high ortho-ration ratio as compared with the usual one.

The reaction temperature of the high-ortho- novolak-type phenol-based resin of the present embodiment is preferably from 110 ° C to 220 ° C, more preferably from 120 ° C to 150 ° C. Thereby, (A) a high-ortho-novolak type phenol system having an ortho-ration ratio of 23% or more can be obtained. Resin. When the resist resin composition contains a novolak-type phenol-based resin having an ortho-chemical ratio of a specific value or more, the phenolic nucleus has a vacancy component, and is formed. When used as a photoresist, it is excellent in pattern shape or resolution.

Further, the ratio of the mixing ratio of cresol to p-cresol between the (A) high-ortho-novolak type phenol-based resin is not particularly limited, and is preferably 90:10 to 50:50 by mass ratio, and further Good for 80:20~60:40. Thereby, the resolution and the residual film ratio in the high sensitivity region can be made more excellent. Further, by setting the blending ratio of p-cresol to the above range, it is possible to prevent the sensitivity from being lowered when used as a photoresist.

Further, in the present embodiment, as a monomer used for the synthesis of the (A) high ortho novolac type phenol resin, m-cresol, p-cresol and 2,5-xylenol are used as essential components. Mixed by. Thereby, a resin composition for a photoresist which is excellent in balance between sensitivity, pattern shape, resolution, and residual film property can be obtained. Further, it is also possible to suppress a decrease in sensitivity or an excellent pattern shape when a monomer obtained by mixing a mixture of cresol and p-cresol previously described in the means for solving the above problems is used.

Further, in the monomer used for the synthesis of the (A) high-ortho- novolak-type phenol resin, it is preferred to further contain 3,5-xylenol in addition to the above three components. Thereby, a resin composition for a photoresist which is further balanced and excellent in sensitivity, pattern shape, resolution, and residual film property can be obtained.

Further, in the monomer used for the synthesis of the (A) high-ortho- novolak-type phenol-based resin, the ratio of the ratio of 2,5-xylenol to 3,5-xylenol is not particularly limited, and the mass ratio is calculated. Preferably, the ratio is 100:0 to 50:50, and more preferably 95:5 to 60:40. Thereby, a resin composition for a photoresist which is further balanced and excellent in sensitivity, pattern shape, resolution, and residual film property can be obtained. Further, by controlling the mixing ratio of the dimethylphenol isomer, that is, 2,5-xylenol and 3,5-xylenol, within the above range, it is possible to prevent deterioration of sensitivity or deterioration of pattern shape. In particular, when the ratio of 3,5-xylenol is large, the decrease in sensitivity or the shape of the pattern can be remarkably prevented.

Further, (A) the total amount of m-cresol and p-cresol in the monomer used for the synthesis of the high-ortho-novolak-type phenol resin, and 2,5-xylenol and 3,5-dimethyl The ratio of the total amount of phenol is preferably 90:10 to 60:40, and more preferably 85:15 to 65:35 by mass ratio. By setting the compounding ratio within the above range, the pattern shape, the resolution, and the residual film ratio in the high sensitivity region can be further improved. Further, by controlling the ratio of the total amount of 2,5-xylenol and 3,5-xylenol to be within the above range, it is possible to prevent the sensitivity which is generated when the photoresist is used and which is greatly reduced. In particular, when the ratio of 3,5-xylenol is large, the sensitivity caused by the use of the photoresist can be remarkably prevented from being greatly lowered.

In addition, the aldehyde to be used for the synthesis of the (A) high-ortho- novolak-type phenol-based resin is not particularly limited, and examples thereof include formaldehyde, para-formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, and willow. Aldehyde, etc. Among these, formaldehyde, paraformaldehyde, acetaldehyde, and salicylaldehyde are preferred. Thereby, when it is used as a resin composition for photoresist, the sensitivity is improved, and the balance between the pattern shape, the resolution, and the residual film property is good and excellent. Further, when formaldehyde is used as the aldehyde, the source of formaldehyde is not particularly limited, and hemicin (aqueous solution), paraformaldehyde, hemiformal such as alcohol, and the like may be used. A person who produces formaldehyde such as trioxane.

Further, an acid catalyst is used for the reaction of the phenols and the aldehydes in the synthesis of the (A) high-ortho- novolak-type phenol-based resin. In the present embodiment, the acid catalyst for synthesizing the (A) high-ortho- novolak-type phenol-based resin is not particularly limited, and examples thereof include weak acids such as oxalic acid and acetic acid. These may be used alone or in combination of two or more.

In addition, the amount of the acid catalyst to be used is not particularly limited, and may be 0.01% by mass or more and 5% by mass or less based on the phenol. When the (A) high-ortho- novolak-type phenol-based resin is contained in the resist resin composition, in order to exhibit the characteristics of the photoresist, it is preferred that the catalyst remaining in the resin be a small amount. Thereby, a resin composition for a photoresist which is further balanced and excellent in sensitivity, pattern shape, resolution, and residual film property can be obtained. Of course, in the process of synthesizing the resin, it can also be removed by a usual removal method (neutralization, water washing or filter filtration, etc.).

Further, the reaction solvent used for the synthesis of the (A) high-ortho- novolak-type phenol-based resin may be a solvent which is moderately non-polar, and examples thereof include hexane, benzene, and xylene. By using these, the ortho-position ratio of the resin can be maintained high.

Further, the ortho-position ratio of the (A) high-ortho- novolak-type phenol-based resin used in the resist resin composition of the present embodiment is preferably 23% or more and 40% or less, and more preferably 25%. Above and below 35%. Thereby, when the photoresist is used, the sensitivity and the residual film ratio can be maintained at a high level, and the pattern shape is also good, and a high resolution can be formed. Further, the ortho rate is generally used ^{13 C-NMR (Nuclear Magnetic Resonance} , NMR) analysis.

Further, the weight average molecular weight in terms of polystyrene obtained by GPC (Gel Permeation Chromatography) of (A) high-ortho- novolak-type phenol-based resin is preferably 1,000 or more and 10,000 or less. More than 2,500 and more than 8,000 are more preferable. By setting the weight average molecular weight of the (A) high-ortho- novolak-type phenol-based resin to the above range, the sensitivity, the residual film ratio, and the resolution can be improved.

Further, the weight average molecular weight of the present embodiment is calculated based on a calibration curve prepared by gel permeation chromatography (GPC) and using polystyrene as a standard material. This GPC measurement was carried out using tetrahydrofuran as a dissolution solvent under the conditions of a flow rate of 1.0 ml/min and a column temperature of 40 °C. Further, the apparatus and column used for GPC measurement are as follows. As a chromatograph, "HLC-8020" manufactured by TOSOH Co., Ltd. was used as a detector, and "UV-8011" manufactured by TOSOH Co., Ltd., which is set to a wavelength of 280 nm, was used as the column for analysis, and "Showa Electric Co., Ltd." was used. SHODEX KF-802, KF-803, KF-805".

Next, a method for producing the (A) high ortho-novolac phenol-based resin of the present embodiment will be described in accordance with the reaction sequence.

(A) The production reaction of the high-ortho-novolak-type phenol-based resin is first added to a reaction apparatus equipped with a stirrer, a thermometer, and a heat exchanger, and a minimum amount of m-cresol, p-cresol, and 2,5-di are added in a specific amount. Phenols and acid catalysts of cresol. Second, to make the temperature inside the reaction device After the temperature is raised to a specific temperature, the aldehydes are sequentially added. Further, the temperature or time of the addition may be appropriately set depending on the reactivity of the monomer and the characteristics of the target, and is set to a level that can be stably and economically produced.

The sequential addition temperature of the aldehyde is preferably from 70 to 130 ° C, more preferably from 90 to 110 ° C. Thereby, it is possible to carry out the reaction at an appropriate speed without raising the temperature rapidly.

The sequential addition time of the aldehyde is preferably from 30 to 300 minutes, and more preferably from 60 to 180 minutes. Thereby, it is possible to carry out the reaction at an appropriate speed without raising the temperature rapidly.

Furthermore, after the end of the sequential addition, the reaction can be continued as needed. In addition, the reaction solvent may be added as needed in the case of the addition and the reaction, and the type of the solvent is not particularly limited, and it is preferably a solvent in which the phenol resin is dissolved. Examples of such a solvent include ketones such as methyl ethyl ketone and methyl isobutyl ketone; alcohols such as butanol; and ether alcohols such as ethoxylated ethanol.

Next, after the above reaction, dehydration and demonomerization were carried out under normal pressure and under reduced pressure. Thereby, a novolak type phenol type resin can be obtained. Further, the conditions for dehydration and demonomerization are not particularly limited, and from the viewpoint of stability (unevenness) or viscosity of the obtained novolak-type phenol resin, it is preferred that the degree of pressure reduction is 0 to 200 Torr. The extraction temperature in the left and right, from the reaction apparatus is 150 to 200 ° C.

Next, the (B) naphthoquinonediazide derivative will be described.

The (B) naphthoquinonediazide derivative contained in the resist resin composition of the present embodiment is not particularly limited, and examples thereof include a ballast such as an alcohol or a phenol derivative, and tetrahydrofuran or two. In a solvent such as an alkane, a derivative of diazonaphthoquinone-5-sulfonyl chloride or diazonaphthoquinone-4-sulfonyl chloride is obtained by reacting and esterifying in the presence of a basic catalyst such as triethylamine. As the chemical structure of the above-mentioned support, compounds of various chemical structures can be used. For example: polyhydroxydiphenyl ketone such as hydroxydiphenyl ketone or dihydroxydiphenyl ketone; naphthol; hydroquinone; pyrogallol; bisphenol A; p-cresol polymer and derivatives thereof Things. Further, in this reaction, the esterification ratio can be controlled by adjusting the molar ratio of sulfonic acid chloride to the carrier of diazonaphthoquinone. These naphthoquinonediazide derivatives may be one kind or a mixture of two or more types.

Next, the (C) solvent will be described.

The solvent (C) contained in the resist resin composition of the present embodiment is not dissolved in the (A) high ortho-novolak-type phenol resin and (B) naphthoquinone diazide derivative. Specially limited. The resistive resin composition of the present embodiment is obtained by dissolving the components in (C) a solvent.

The solvent (C) contained in the resin composition for photoresist of the present embodiment is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone, γ-butyrolactone, and N,N-dimethyl group. Acetamine, dimethyl hydrazine, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate Ester, methyl lactate, ethyl lactate, butyl lactate, methyl-1,3-butylene glycol acetate, 1,3-butanediol-3-single Methyl ether (1,3-butylene glycol-3-monomethyl ether), methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, etc. may be used singly or in combination.

Further, in the resin composition for a resist according to the present embodiment, in addition to the components described above, a stabilizer such as an antioxidant, a plasticizer, a surfactant, an adhesion improver, and a dissolution promoter may be used as needed. And other additives.

The method for producing the resin composition for a photoresist according to the present embodiment is not particularly limited. When the filler or the pigment is not added to the resin composition for a resist, the components may be mixed and stirred by a usual method. When a filler or a pigment is added, it may be dispersed and mixed using a dispersing device such as a dispersing mixer, a homogenizer or a three-roll mill. Further, it may be further filtered using a sieve filter, a membrane filter or the like as needed. By exposing the photoresist composition for a photoresist obtained in this manner to a mask, a structural change occurs in the resin composition for the exposed portion photoresist, and the solubility in the alkaline developer can be promoted. On the other hand, the lower solubility of the alkaline developing solution is maintained in the non-exposed portion, and the photoresist function can be imparted by the difference in solubility generated in this manner.

<light resistance>

Next, the photoresist of this embodiment will be described.

The photoresist of this embodiment is characterized in that the resist resin composition is used. Thereby, it is possible to produce a photoresist suitable for the fabrication of a fine circuit of a liquid crystal display device circuit or a semiconductor integrated circuit.

In the case of using the photoresist of the present embodiment, the (B) naphthoquinonediazide derivative in the resist resin composition is chemically changed by the irradiation of light, and in the subsequent development step and (A) The high-ortho-novolak-type phenol-based resin is dissolved in the alkaline developing solution, and a clear difference in dissolution speed is generated between the unexposed portion, and thus the target pattern can be obtained by development.

<Method of Manufacturing Liquid Crystal Device>

When the resin composition for photoresist of this embodiment is used for the photolithography method, the method described below is used.

First, (A) a novolak-type phenol-based resin, (B) a naphthoquinonediazide derivative as a sensitizer, and (C) a solvent are mixed. The resist resin composition obtained by mixing is applied onto an object subjected to photolithography to form a photoresist pattern. In the case where the resist resin composition of the present embodiment is a positive photoresist, it is not dissolved in the developer as long as it is not exposed.

Next, after exposing the photoresist pattern, the photoresist pattern is developed. Further, in the photoresist pattern, the exposed portion becomes a carboxylic acid due to a chemical change of the sensitizer. Therefore, it can be dissolved in the developer only at the point of exposure. Further, when it is dissolved in the developer, the solubility may be different due to the action of the sensitizer, whereby a pattern of contrast can be formed.

Thereafter, a specific film is etched by using the produced resist pattern as a mask, whereby the layer structure of the liquid crystal device can be formed.

[Examples]

Hereinafter, the present invention will be described using a synthesis example and an example. However, the invention is not limited to the synthesis examples and examples. Moreover, the "parts" described in the synthesis examples, examples, and comparative examples Indicates "parts by weight" and "%" means "% by weight". Except for the concentration (%) of the aqueous solution of formalin.

<Synthesis of Novolac Type Phenolic Resin>

(Synthesis Example 1)

750 parts of m-cresol, 250 parts of p-cresol, 200 parts of 2,5-xylenol, and 50 parts of 3,5-xylenol were added to a 3 L four-necked flask equipped with a stirring device, a thermometer, and a heat exchanger. 200 parts of alkane and 12.5 parts of oxalic acid were used to raise the internal temperature of the four-necked flask to 130 °C. Next, 706 parts of 37% formalin was slowly added over 3 hours, dehydrated and reacted for 2 hours thereafter. Thereafter, the mixture was dehydrated under normal pressure until the internal temperature of the four-necked flask became 170 ° C, and dehydration and de-monogenation were carried out under reduced pressure of 9.3 × 10 ³ Pa until the internal temperature of the four-necked flask was 200 °C. Thereby, 1190 parts of the novolak type phenol type resin A of weight average molecular weight 4000 was obtained.

(Synthesis Example 2)

The same procedure as in Example 1 was carried out, except that 900 parts of m-cresol, 100 parts of p-cresol, and 733 parts of 37% fumarine were used. By this method, 1200 parts of a novolac type phenol-based resin B having a weight average molecular weight of 5,400 was obtained.

(Synthesis Example 3)

The same procedure as in Example 1 was carried out, except that 600 parts of m-cresol, 400 parts of p-cresol, and 687 parts of 37% fumarine were used. By this method, 1025 parts of a novolac type phenol-based resin C having a weight average molecular weight of 3,500 was obtained.

(Synthesis Example 4)

The same procedure as in Example 1 was carried out, except that 150 parts of 2,5-xylenol, 100 parts of 3,5-xylenol, and 687 parts of 37% of fumarin were used. By this method, 1160 parts of a novolac type phenol-based resin D having a weight average molecular weight of 3,600 was obtained.

(Synthesis Example 5)

Except that 700 parts of m-cresol, 300 parts of p-cresol, 250 parts of 2,5-xylenol, unadapted 3,5-xylenol, and 687 parts of 37% fumarin were used. Use and embodiment 1 The same method. By this method, 1190 parts of a novolac type phenol-based resin E having a weight average molecular weight of 400 was obtained.

(Synthesis Example 6)

The same procedure as in Example 1 was carried out, except that 100 parts of 2,5-xylenol, 25 parts of 3,5-xylenol, and 642 parts of 37% of formalin were used. By this method, 1024 parts of a novolac type phenol-based resin F having a weight average molecular weight of 4,400 was obtained.

(Synthesis Example 7)

The same procedure as in Example 1 was carried out, except that 400 parts of 2,5-xylenol, 100 parts of 3,5-xylenol, and 823 parts of 37% of formalin were used. By this method, 1350 parts of a novolac type phenol-based resin G having a weight average molecular weight of 3,600 was obtained.

(Comparative Synthesis Example 1)

It is used in the same manner as in Example 1 except that 2,5-xylenol and 3,5-xylenol were not prepared, 160 parts of hexane, 10 parts of oxalic acid, and 600 parts of 37% of formalin. The same method. By this method, 900 parts of a novolac type phenol-based resin H having a weight average molecular weight of 6000 was obtained.

(Comparative Synthesis Example 2)

The same procedure as in Example 1 was carried out, except that 2,5-xylenol was not prepared, 250 parts of 3,5-xylenol was used, and 641 parts of 37% fumarine was used. By this method, 1130 parts of a novolac type phenol-based resin I having a weight average molecular weight of 3,100 was obtained.

(Comparative Synthesis Example 3)

In addition to using 700 parts of m-cresol, 300 parts of p-cresol, 250 parts of 2,5-xylenol, this is not formulated with 3,5-xylenol and hexane, and 600 parts of 37% formalin is used. The same method as in Example 1 was used except for the point. By this method, a 1 1 part of a novolac type phenol-based resin J of a weight average molecular weight of 5,500 was obtained.

<Evaluation of Novolak Type Phenolic Resin>

Determination of ortho-position ratio (o-o' bond ratio) by ¹³ C-NMR

Nuclear magnetic resonance spectroscopic analysis (NMR) was performed on the obtained phenolic resins A to I. Further, NMR was measured using JNM-AL300 manufactured by Nippon Electronics Datum Co., Ltd.

From the results obtained by NMR measurement, the bonding ratios of o-p, p-p', and o-o' of the resin were determined. Furthermore, the ratio of the op key is determined based on the area of the integration of 40 to 35 ppm, and the ratio of the p-p' key is based on the ratio of 35 to 28.5 ppm and the o-o' key according to the integral of 28.5 to 25 ppm. It is obtained by the area of time. In addition, as the measurement conditions, the cumulative number of times was set to 10,000 times.

The ortho-position ratios of the phenolic resins A to G obtained in Synthesis Examples 1 to 7 were 30%, 28%, 32%, 33%, 28%, 25%, and 30%, respectively. Further, the ortho-position ratios of the phenolic resins H to J obtained in Comparative Synthesis Examples 1 to 3 were 21%, 38%, and 18%, respectively. Further, the ortho-ration ratios of the phenolic resins A to J are also shown in Table 1 below.

<Adjustment of Resin Composition for Photoresist>

(Example 1)

20 parts of the novolac type phenol-based resin A obtained in Synthesis Example 1 and 5 parts of 2,3,4-trihydroxy-diphenyl ketone of naphthoquinone 1,2-diazide-5-sulfonic acid were dissolved in propylene glycol. Monomethyl ether acetate (PGMEA) in 75 parts. Thereafter, the film was filtered using a 0.1 μm membrane filter to prepare a resin composition for a photoresist.

(Examples 2 to 7)

A resist resin composition was prepared in the same manner as in Example 1 except that the novolac type phenol-based resin B to G obtained in Synthesis Examples 2 to 7 was used as the novolac type phenol-based resin.

(Comparative examples 1 to 3)

A resist resin composition was prepared in the same manner as in Example 1 except that the novolac type phenol-based resin H to J obtained in Comparative Synthesis Examples 1 to 3 was used as the novolac type phenol-based resin.

The resistive resin compositions obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were measured and evaluated as follows.

<Evaluation method of characteristics>

(1) Method for measuring residual film rate

The resist resin composition was applied onto a 3 inch silicon wafer by a spin coater so as to have a thickness of about 1 μm, and dried on a hot plate at 110 ° C for 100 seconds. Then, the ruthenium wafer was immersed in a developing solution (2.38% aqueous solution of tetramethylammonium hydroxide) for 60 seconds, washed with water, and dried on a hot plate at 110 ° C for 100 seconds. The ratio of the film thickness after development to the film thickness before development is expressed as a residual film ratio. Thereby, the degree of residual film (resistance) when used as a photosensitizer and a photoresist is known. Moreover, a higher value indicates a higher residual film rate. Furthermore, the unit is %.

(2) Method for measuring sensitivity

The resist resin composition was applied onto a 3 inch silicon wafer by a spin coater so as to have a thickness of about 1.5 μm, and dried on a hot plate at 110 ° C for 100 seconds. Then, the silicon wafer in the stack on the test chart reticle were irradiated ^{5mJ / cm 2, 10mJ / cm} 2, 15mJ / cm ² of ultraviolet rays, followed by a developer (2.38% of the aqueous solution of tetramethylammonium hydroxide) Development was carried out for 60 seconds. The pattern shape of the obtained pattern was observed by a scanning electron microscope, and evaluated based on the following criteria.

A to 5mJ / ² cm at an image can be formed.

B at 5mJ / cm ² can not be formed images, while in at 10mJ cm ² / image can be formed.

C could not form an image at 10 mJ/cm ² , and an image could be formed at 15 mJ/cm ² .

(3) Determination of resolution

The obtained resist resin composition was applied onto a tantalum wafer using a spin coater, and prebaked at 110 ° C for 100 seconds to form a photoresist film having a film thickness of 1.5 μm. A pattern mask engraved with a line width of 100 μm to 1 μm is exposed to ultraviolet light. Immediately after the exposure, it was developed with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide at 23 ° C for 60 seconds, washed with water, and dried to obtain a positive pattern. At this time, the minimum photoresist pattern size that is resolved by the specific exposure amount is set as the limit resolution. Furthermore, the unit is μm.

(4) Pattern shape

The resist resin composition was coated on a tantalum wafer using a spin coater and prebaked at 110 ° C. Bake for 100 seconds to form a photoresist film having a film thickness of 1.5 μm. A pattern mask engraved with a line width of 5 μm was exposed to ultraviolet light. Immediately after the exposure, development was carried out by using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide at 23 ° C for 60 seconds, followed by washing with water and drying to obtain a positive pattern. The shape of the photoresist pattern on the germanium wafer was observed by a scanning electron microscope, and the angle of the rectangular pattern of the photoresist at the upper angle of the cross section was measured. The angle of 110 degrees or less was recorded as ○, and the angle of 110 degrees or more was rounded. Those who cannot be clearly determined by the degree are recorded as ×.

The evaluation results related to the above evaluation items are shown in Table 1 below.

According to the results of Table 1, the resistive resin compositions of Examples 1 to 7 have a good balance between sensitivity, pattern shape, resolution, and residual film property as compared with the resistive resin compositions of Comparative Examples 1 to 3. And excellent. The photoresist using the resist resin composition is excellent in fine workability. As a result, when a liquid crystal device is manufactured by actually using the composition for a photoresist described in the examples, a liquid crystal device having a fine circuit similar to that of the design can be obtained.

Further, in Comparative Example 1, phenols in the case of synthesizing a novolak-type phenol-based resin using only m-cresol and p-cresol were used, and the ortho-position ratio was less than 23%. The photoresist composition of Comparative Example 1 had a low residual film ratio and a large limit resolution, and the cross-sectional shape of the pattern was also a substantially semi-elliptical shape, and the angle was not clear.

In Comparative Example 2, m-cresol, p-cresol and 3,5-xylenol were used as the phenols in the synthesis of the novolak-type phenol-based resin, and 2,5-xylenol was not used. The photoresist composition of Comparative Example 2 had a low sensitivity and was not excellent in pattern shape.

In Comparative Example 3, m-cresol, p-cresol and 2,5-xylenol were used as the phenols in the synthesis of the novolak-type phenol-based resin, but the temperature at the time of synthesis was as low as 100 ° C, so the ortho-position ratio was low. At 23%. The photoresist composition of Comparative Example 3 has a low residual film ratio and a large limit resolution, and the cross-sectional shape of the pattern is also a substantially semi-elliptical shape, and the angle is not clear.

[Industrial availability]

The resin composition for photoresist of the present invention has a good pattern shape and has high residual film properties at high sensitivity and high resolution, and thus can be preferably used for microcircuit fabrication of a liquid crystal display device circuit or a semiconductor integrated circuit. .

Claims (8)

A resin composition for photoresist, comprising: (A) a high-ortho-novolak-type phenol-based resin, which is a phenolic phenol and a aldehyde derived from m-cresol, p-cresol and 2,5-xylenol In the presence of a medium, the reaction is carried out at a temperature of 110 ° C or higher and 220 ° C or lower, and the ortho-position ratio is 23% or more; (B) a naphthoquinone diazide derivative; and (C) a solvent. The resin composition for a photoresist according to the first aspect of the invention, wherein the ratio of the above m-cresol to the above-mentioned p-cresol is 90:10 to 50:50 by mass ratio. The resin composition for photoresist according to the first aspect of the invention, wherein the phenol further contains 3,5-xylenol. The resin composition for a photoresist according to the third aspect of the invention, wherein the ratio of the 2,5-xylenol to the 3,5-xylenol is 100:0 to 50:50 by mass ratio. The resin composition for photoresist according to claim 3, wherein the total amount of the above m-cresol and the p-cresol is the same as the above-mentioned 2,5-xylenol and the above-mentioned 3,5-xylenol The ratio of the total blending amount is 90:10 to 60:40 in terms of mass ratio. A resin composition for a photoresist according to the first aspect of the invention, which is a resin composition for a positive photoresist. A photoresist is obtained by using the resin composition for a photoresist according to any one of claims 1 to 6. A method for producing a liquid crystal device, comprising the step of performing a photolithography method using the resin composition for a photoresist according to any one of claims 1 to 6.