JP2013254193A - Resin composition for photoresist, photoresist and method of manufacturing liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for photoresist which has excellent sensitivity, pattern shape, resolution and film retaining properties with good balance.SOLUTION: A resin composition for photoresist contains (A) a high-orthonovolac phenol resin having ortho-form ratio of 23% or more, obtained by reacting phenol including metacresol, p-cresol and 2,5-xylenol with aldehyde in the presence of an acid catalyst under the temperature condition of 110°C or more and 220°C or less, (B) a naphthoquinonediazido derivative, and (C) a solvent.

Description

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

  A fine 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 applied to an insulating film or a conductive metal film formed on a substrate. Next, in the presence of a mask having a predetermined shape, the coated photoresist composition is exposed and developed to form a resist pattern having a target shape. Thereafter, the metal film or the insulating film is removed using the photoresist film on which the pattern is formed as a mask. Next, the remaining photoresist film is removed to form a fine circuit on the substrate. The photoresist composition is classified into a positive type when forming a soluble photoresist film and a negative type when forming an insoluble photoresist film.

  Generally, for a positive photoresist composition, a photosensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolac-type phenol resin) are used. A positive photoresist composition having such a composition exhibits high resolving power by development with an alkaline solution after exposure, and therefore, manufacture of semiconductors such as IC and LSI, manufacture of liquid crystal display screen devices such as LCD, and manufacture of printing masters Etc. are used.

  Further, the novolac type phenol resin has high heat resistance due to the structure having many aromatic rings with respect to plasma dry etching. For this reason, a number of positive photoresists containing a novolac type phenolic resin and a naphthoquinone diazide photosensitizer have been developed and put to practical use, and great results have been achieved so far.

In terms of practical use, important characteristics required for a photoresist composition for a liquid crystal display device circuit are sensitivity of the formed resist film, development contrast, resolution, adhesion to the substrate, residual film ratio, heat resistance, and Circuit line width uniformity (CD uniformity).
In particular, a photoresist composition for a thin film transistor liquid crystal display device is required to improve sensitivity because of its long exposure time in a production line due to the large area of the substrate, which is a feature of the photoresist composition. Further, since the sensitivity and the remaining film rate are in an inversely proportional relationship, the higher the sensitivity, the lower the remaining film rate tends to decrease.

  A novolak type phenol resin obtained by reacting phenols such as m / p-cresol and aldehydes such as formaldehyde in the presence of an acid catalyst is generally used for positive photoresists for liquid crystal display circuits. Yes. And in order to adjust or improve the characteristic of a photoresist, examination of the ratio of m / p-cresol used as raw material phenols, the kind of raw material phenols, the molecular weight of a phenol resin, molecular weight distribution, etc. has been made.

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

  Patent Document 1 discloses a phenol resin for a photoresist in which the ratio of ortho bond / para bond (O / P ratio) of the internuclear methylene bond and the content of the binuclear component show specific values. Further, Patent Document 1 describes that a positive photoresist mixed with a high-ortho type novolac resin having a small number of binuclear components is used in order to improve the photoresist characteristics. According to the photoresist described in Patent Document 1, it has excellent resolving power (pattern shape), good heat resistance and sensitivity, and has good workability with little oven contamination due to low molecular weight volatile components during the resist coating drying process. Can be obtained.

  Patent Document 2 discloses a method for separating a novolak resin to provide a film-forming novolak resin that exhibits a high dissolution rate, a high photospeed in a photosensitive composition, and excellent lithographic performance. A method for fractionating a novolak resin to improve the photoresist characteristics as in the technique described in Patent Document 2 is generally used by those skilled in the art.

Japanese Patent Application Laid-Open No. 07-110576 Special table 2002-508415 gazette

  Conventionally, in order to improve the sensitivity of the photoresist, the molecular weight of the novolak resin has been lowered. However, when the molecular weight of the novolak resin is lowered, the heat resistance is deteriorated, the remaining film ratio of the unexposed part is lowered, and the difference in dissolution rate from the exposed part cannot be obtained. There is a disadvantage that the contrast is lowered and the resolution is lowered.

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

  That is, according to the prior art, by improving any one of various photoresist characteristics such as heat resistance, remaining film ratio, and resolution, some inconvenience may occur in other characteristics. For this reason, the resin composition for photoresists for liquid crystal display device circuits, which is excellent in balance in various photoresist properties such as sensitivity, residual film ratio, development contrast, resolution, adhesion to the substrate and circuit line width uniformity, It has not been obtained yet.

  Compared with the time of filing of Patent Documents 1 and 2, the technical level required for various characteristics such as sensitivity, pattern shape, resolution, and remaining film property of the resin composition for photoresist is higher.

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

  In order to provide a photoresist resin composition having excellent balance in sensitivity, pattern shape, resolution, and residual film property, the present inventor has various blending compositions of monomers and various orthorification rates of novolak-type phenolic resins to be blended. The manufacturing conditions were studied earnestly. As a result, it has been found that a conventional monomer obtained by mixing m-cresol and p-cresol does not provide good sensitivity and does not have an excellent pattern shape. In addition, it was found that a resin pattern for a photoresist showing a low value of, for example, a low value of about 20% for a novolak-type phenol resin cannot obtain a good pattern shape, residual film property and resolution.

  Therefore, in view of the above circumstances, the present inventor has obtained a resin composition for a photoresist having a good balance of sensitivity, pattern shape, resolution, and residual film properties, respectively, so that metacresol, paracresol and 2,5-xylenol are obtained. The present inventors have found that it is effective to use a novolak-type phenol resin having an ortho-conversion rate of a specific value or more together with a naphthoquinone diazide derivative or a solvent, using a monomer having the above three components as essential components. .

According to the present invention, (A) a phenol and a aldehyde containing metacresol, paracresol and 2,5-xylenol are reacted in the presence of an acid catalyst at a temperature of 110 ° C. or higher and 220 ° C. or lower. A high ortho novolac type phenolic resin having an ortho-conversion rate of 23% or more,
(B) a naphthoquinonediazide derivative;
(C) a solvent;
A resin composition for photoresists is provided.

  Furthermore, according to this invention, the photoresist characterized by using the resin composition for photoresists is provided.

  Furthermore, according to this invention, the manufacturing method of the liquid crystal device characterized by including the process of performing photolithography using the said resin composition for photoresists is provided.

  According to the present invention, it is possible to obtain a resin composition for a photoresist having excellent balance of sensitivity, pattern shape, resolution, and residual film properties.

  Hereinafter, the photoresist resin composition according to the present embodiment will be described in detail.

<Resin composition for photoresist>
The resin composition for photoresists according to this embodiment includes (A) metacresol (hereinafter also referred to as “m-cresol”), paracresol (hereinafter also referred to as “p-cresol”), and 2,5-. A high ortho novolak type phenol resin having an ortho-conversion rate of 23% or more obtained by reacting xylenol-containing phenols and aldehydes in the presence of an acid catalyst under a temperature condition of 110 ° C. or higher and 220 ° C. or lower; B) A naphthoquinonediazide derivative and (C) a solvent are included. Thereby, it becomes the resin composition for photoresists with which the sensitivity, the pattern shape, the resolution, and the remaining film property are each excellent in a good balance. The photoresist resin composition according to this embodiment is preferably used as a positive resist.

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

Hereinafter, the resin composition for photoresists according to this embodiment will be described in detail.
In the photoresist resin composition according to the present embodiment, (A) a high ortho novolac type phenol resin having an ortho conversion rate of 23% or more can be used. This (A) high ortho novolak type phenol resin having an ortho conversion rate of 23% or more is obtained by adding phenols and aldehydes containing metacresol, paracresol and 2,5-xylenol in the presence of an acid catalyst to 110 ° C. or higher. It is a resin obtained by reaction under a temperature condition of 220 ° C. or lower.

  (A) A high ortho novolac type phenol resin having an ortho-conversion rate of 23% or more can preferentially cause a reaction in the vicinity of the phenolic hydroxyl group by reacting at a high temperature of 110 ° C. or higher and 220 ° C. or lower. . For this reason, it is easy to obtain a resin having a higher ortho-ratio compared to a normal one.

  The temperature of the reaction for producing the high ortho novolak type phenolic resin according to this embodiment is preferably 110 ° C. or higher and 220 ° C. or lower, and more preferably 120 ° C. or higher and 150 ° C. or lower. Thus, (A) a high ortho novolac type phenol resin having an ortho conversion rate of 23% or more can be obtained. By including the novolak type phenol resin having the ortho-ratio obtained in this way with a specific value or more in the photoresist resin composition, the number of components in the vacancies in the para position of the phenol nucleus increases, and it is used as a photoresist. The pattern shape and resolution are excellent.

  The blending ratio of metacresol and paracresol used for the synthesis of (A) high ortho novolak type phenol resin is not particularly limited, but is preferably 90:10 to 50:50 by mass ratio. 80:20 to 60:40 is more preferable. By doing so, the resolution and the remaining film ratio in the high sensitivity region can be further improved. Moreover, it can prevent that a sensitivity falls, when it uses as a photoresist by making the mixture ratio of paracresol into the said range.

  Moreover, in this embodiment, (A) As a monomer used for the synthesis | combination of a high ortho novolak type phenol resin, the monomer formed by mixing three components of metacresol, paracresol, and 2, 5- xylenol as an essential component is used. . By carrying out like this, the resin composition for photoresists with which the sensitivity, the pattern shape, the resolution, and the remaining film property were each excellent in a good balance can be obtained. In addition, as in the case of using a monomer obtained by mixing conventional m-cresol and p-cresol described in the means for solving the above problems, the sensitivity is not lowered and the pattern shape is not excellent. Can also be suppressed.

  Moreover, it is preferable that the monomer used for the synthesis of the (A) high ortho novolak type phenol resin further includes 3,5-xylenol in addition to the above three components. By carrying out like this, the resin composition for photoresists which was excellent in each of the sensitivity, the pattern shape, the resolution, and the remaining film property with an even better balance can be obtained.

  In addition, the blending ratio of 2,5-xylenol and 3,5-xylenol in the monomer used for the synthesis of (A) the high ortho novolac type phenol resin is not particularly limited, but is 100: 0 by mass ratio. The ratio is preferably 50:50, and more preferably 95: 5 to 60:40. By carrying out like this, the resin composition for photoresists which was excellent in each of the sensitivity, the pattern shape, the resolution, and the remaining film property with an even better balance can be obtained. In addition, it can prevent that a sensitivity fall or a pattern shape deteriorates by controlling so that the compounding ratio of the 2, 5- xylenol which is xylenol isomer, and 3, 5- xylenol may become in the said range. . In particular, when the ratio of 3,5-xylenol is large, it is possible to remarkably prevent a decrease in sensitivity and a deterioration in pattern shape.

  The ratio of the total blending amount of metacresol and paracresol in the monomer used for the synthesis of (A) high ortho novolak type phenol resin and the total blending amount of 2,5-xylenol and 3,5-xylenol is a mass ratio. Is preferably 90:10 to 60:40, and more preferably 85:15 to 65:35. When the blending ratio is in the above range, the pattern shape, resolution, and remaining film ratio can be further improved in the high sensitivity region. In addition, 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 a significant decrease in sensitivity that occurs when used as a photoresist. . In particular, when the ratio of 3,5-xylenol is large, it is possible to remarkably prevent a significant decrease in sensitivity that occurs when used as a photoresist.

  In addition, aldehydes used for the synthesis of (A) high ortho novolak type phenol resin are not particularly limited, and examples thereof include formaldehyde, paraformaldehyde, acetaldehyde, propyl aldehyde, butyraldehyde, benzaldehyde, salicylaldehyde, and the like. Among these, formaldehyde, paraformaldehyde, acetaldehyde, and salicylaldehyde are preferable. Thereby, when it uses as a resin composition for photoresists, a sensitivity can be improved and it can be excellent with good balance with pattern shape, resolution, and residual film property. When formaldehyde is used as the aldehyde, the formaldehyde source is not particularly limited, and those that generate formaldehyde such as formalin (aqueous solution), paraformaldehyde, hemi-formal with alcohols, and trioxane can be used.

  In addition, an acid catalyst is used for the reaction between phenols and aldehydes in the synthesis of (A) high ortho novolac type phenol resin. In this embodiment, the acid catalyst for synthesizing (A) the high ortho novolak type phenol resin is not particularly limited, and examples thereof include weak acids such as organic carboxylic acids such as oxalic acid and acetic acid. You may use these individually or in mixture of 2 or more types.

  Moreover, although the usage-amount of the said acid catalyst is not specifically limited, What is necessary is just 0.01 mass% or more and 5 mass% or less with respect to phenols. In addition, when (A) a high ortho novolak type phenol resin is included in the resin composition for a photoresist, it is preferable that a small amount of catalyst remains in the resin in order to exhibit the characteristics of the photoresist. By carrying out like this, the resin composition for photoresists which was excellent in each of the sensitivity, the pattern shape, the resolution, and the remaining film property with an even better balance can be obtained. Of course, in the process of synthesizing the resin, it may be removed by a general removal method (neutralization, water washing, filter filtration, etc.).

  Moreover, the reaction solvent used for the synthesis | combination of (A) high ortho novolak type phenol resin should just be a moderately non-polar solvent, for example, hexane, benzene, xylene, etc. are mentioned. By using these, it becomes possible to keep the ortho-ratio of the resin high.

Further, the ortho-ratio of the (A) high ortho novolak type phenol resin used in the photoresist resin composition according to the present embodiment is preferably 23% or more and 40% or less, and 25% or more and 35% or less. More preferably. Thereby, when used as a photoresist, the sensitivity and the remaining film ratio can be kept high, the pattern shape is good, and high resolution can be achieved. In addition, the orthorification rate can generally be analyzed using ¹³ C-NMR.

  The weight average molecular weight in terms of polystyrene by GPC of the (A) high ortho novolak type phenol resin is preferably 1000 or more and 10000 or less, and more preferably 2500 or more and 8000 or less. (A) By making the weight average molecular weight of a high ortho novolak type phenol resin into the said range, a sensitivity, a remaining film rate, and the resolution can be improved.

  The weight average molecular weight according to the present embodiment is calculated based on a calibration curve prepared using polystyrene as a standard substance by gel permeation chromatography (GPC) measurement. This GPC measurement was performed using tetrahydrofuran as an elution solvent under conditions of a flow rate of 1.0 ml / min and a column temperature of 40 ° C. Moreover, the apparatus and column used for GPC measurement are as follows. As a chromatograph, manufactured by TOSOH, "HLC-8020", as a detector, manufactured by TOSOH, set at a wavelength of 280 nm, "UV-8011", as an analytical column, manufactured by Showa Denko Co., Ltd., "SHODEX" KF-802, KF-803, KF-805 "were used respectively.

  Next, the manufacturing method of the (A) high ortho novolak type phenol resin which concerns on this embodiment is demonstrated along the reaction procedure.

  (A) The reaction of producing a high ortho novolac type phenol resin is first made with respect to a reaction apparatus equipped with a stirrer, a thermometer, and a heat exchanger, phenols containing at least metacresol, paracresol and 2,5-xylenol, acidic A predetermined amount of the catalyst is charged. Next, after the temperature in the reactor is raised to a predetermined temperature, sequential addition of aldehydes is started. The sequential addition temperature and time can be appropriately set depending on the reactivity of the monomer and the desired characteristics, but are set to a level at which stable and economical production is possible.

  The sequential addition temperature of aldehydes is preferably 70 to 130 ° C, more preferably 90 to 110 ° C. By carrying out like this, reaction can be advanced at a suitable speed | rate, without raising temperature rapidly.

  The sequential addition time of aldehydes is preferably 30 to 300 minutes, more preferably 60 to 180 minutes. By carrying out like this, reaction can be advanced at a suitable speed | rate, without raising temperature rapidly.

  In addition, after completion | finish of sequential addition, reaction can be continued as it is as needed. Further, during sequential addition and reaction, a reaction solvent can be added and used as necessary. The type of the solvent is not particularly limited, but a solvent that dissolves the phenol resin is preferable. Examples of such a solvent include ketones such as methyl ethyl ketone and methyl isobutyl ketone, alcohols such as butanol, ether alcohols such as ethoxyethanol, and the like.

  Next, after the reaction, dehydration / demonomerization is performed under normal pressure and reduced pressure. By doing so, a novolac type phenol resin can be obtained. The conditions for dehydration / demonomer are not particularly limited, but from the viewpoint of stability (variation) and viscosity of the obtained novolak type phenol resin, the degree of vacuum is about 0 to 200 Torr, and the temperature taken out from the reactor is It is preferable to carry out at 150 to 200 ° C.

Next, (B) naphthoquinonediazide derivative will be described.
The (B) naphthoquinonediazide derivative contained in the photoresist resin composition according to the present embodiment is not particularly limited. For example, diazonaphthoquinone-5-sulfonic acid chloride or diazonaphthoquinone-4-sulfonic acid chloride is used. It can be obtained by reacting the derivative with a ballast such as an alcohol or a phenol derivative in a solvent such as tetrahydrofuran or dioxane in the presence of a basic catalyst such as triethylamine. As the chemical structure of the ballast, compounds having various chemical structures can be used. For example, polyhydroxybenzophenone such as hydroxybenzophenone and dihydroxybenzophenone, naphthol, hydroquinone, pyrogallol, bisphenol A, p-cresol polymer, and derivatives thereof. In this reaction, the esterification rate can be controlled by adjusting the molar ratio of diazonaphthoquinone sulfonic acid chloride to ballast. These naphthoquinonediazide derivatives may be one kind or a mixture of two or more kinds.

Next, (C) the solvent will be described.
The (C) solvent to be contained in the photoresist resin composition according to the present embodiment is not particularly limited as long as it dissolves (A) a high ortho novolak type phenol resin and (B) a naphthoquinone diazide derivative. The photoresist resin composition according to this embodiment is obtained by dissolving these components in the solvent (C).
The (C) solvent to be contained in the photoresist resin composition according to this embodiment is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylacetamide, and dimethyl. Sulfoxide, 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, methyl lactate, ethyl lactate, butyl lactate, methyl-1,3-butylene glycol acetate, 1 , 3-butylene glycol-3-monomethyl ether, methyl pyruvate, ethyl pyruvate, methyl-3-methoxypropionate, etc. These can be used singly or as a mixture.

  In addition to the components described above, the photoresist resin composition according to the present embodiment includes a stabilizer such as an antioxidant, a plasticizer, a surfactant, an adhesion improver, and a dissolution accelerator, if necessary. Various additives such as an agent may be used.

  The method for preparing the photoresist resin composition according to the present embodiment is not particularly limited, but when no filler or pigment is added to the photoresist resin composition, the above components are mixed and stirred by a usual method. In the case of adding a filler or a pigment, it may be dispersed and mixed using a dispersing device such as a dissolver, a homogenizer, or a three roll mill. Moreover, you may further filter using a mesh filter, a membrane filter, etc. as needed. When the photoresist resin composition thus obtained is exposed through a mask, a structural change occurs in the photoresist resin composition in the exposed portion, and the resist composition with respect to the alkaline developer is used. Solubility can be promoted. On the other hand, in the non-exposed area, low solubility in an alkali developer is maintained, so that a resist function can be imparted due to the difference in solubility thus generated.

<Photoresist>
Next, the photoresist according to this embodiment will be described.
The photoresist according to this embodiment is characterized by using the above-described photoresist resin composition. Thereby, it can be set as the photoresist which can be used suitably for fine circuit manufacture of a liquid crystal display device circuit or a semiconductor integrated circuit.

  When the photoresist according to the present embodiment is used, the (B) naphthoquinone diazide derivative in the photoresist resin composition undergoes a chemical change by irradiation with light, and (A) a high ortho novolac type phenol resin in a later development step. At the same time, it dissolves in an alkaline developer and produces a clear difference in dissolution rate from the unexposed portion, whereby a desired pattern can be obtained by development.

<Manufacturing method of liquid crystal device>
When the photoresist resin composition according to the present embodiment is used for photolithography, the method described below is used.
First, (A) a novolak type phenol resin, (B) a naphthoquinonediazide derivative and (C) a solvent are mixed as a photosensitizer. The resin composition for photoresist obtained by mixing is applied onto an object to be subjected to photolithography to form a resist pattern. When the photoresist resin composition according to this embodiment is a positive resist, it does not dissolve in the developer unless it is exposed.
Next, after exposing the resist pattern, the resist pattern is developed. In the resist pattern, the exposed portion becomes carboxylic acid due to a chemical change of the photosensitive agent. For this reason, only the exposed part can be dissolved in the developer. Further, when dissolved in a developing solution, it is possible to make a difference in solubility by the action of a photosensitive agent, whereby a contrast pattern can be formed.
Thereafter, the layer structure of the liquid crystal device can be formed by etching a predetermined film using the manufactured resist pattern as a mask.

  Hereinafter, the present invention will be described with reference to synthesis examples and examples. However, the present invention is not limited by these synthesis examples and examples. In the synthesis examples, examples and comparative examples, “part” means “part by weight” and “%” means “% by weight”. However, the concentration (%) of the formalin aqueous solution is excluded.

<Synthesis of novolac type phenolic resin>
(Synthesis Example 1)
In a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 750 parts of m-cresol, 250 parts of p-cresol, 200 parts of 2,5-xylenol, 50 parts of 3,5-xylenol, 200 parts of hexane, 12.5 parts of oxalic acid was charged, and the internal temperature of the 4-neck flask was raised to 130 ° C. Next, 706 parts of 37% formalin was gradually added over 3 hours, followed by reaction for 2 hours while dehydrating. Thereafter, dehydration was performed under normal pressure until the internal temperature of the four-necked flask reached 170 ° C., and dehydration / demonomerization was further performed to 200 ° C. under a reduced pressure of 9.3 × 10 ³ Pa. In this manner, 1190 parts of a novolac type phenol resin A having a weight average molecular weight of 4000 was obtained.

(Synthesis Example 2)
The same method as in Example 1 was used except that 900 parts of m-cresol and 100 parts of p-cresol were used and 733 parts of 37% formalin were used. By this method, 1200 parts of a novolak type phenol resin B having a weight average molecular weight of 5400 was obtained.

(Synthesis Example 3)
The same method as in Example 1 was used except that 600 parts of m-cresol and 400 parts of p-cresol were used and 687 parts of 37% formalin were used. By this method, 1025 parts of a novolak type phenol resin C having a weight average molecular weight of 3,500 was obtained.

(Synthesis Example 4)
The same method as in Example 1 was used except that 150 parts of 2,5-xylenol, 100 parts of 3,5-xylenol were used, and 687 parts of 37% formalin were used. By this method, 1160 parts of a novolak type phenol resin D having a weight average molecular weight of 3600 was obtained.

(Synthesis Example 5)
Except for 700 parts of m-cresol, 300 parts of p-cresol, 250 parts of 2,5-xylenol, no blending of 3,5-xylenol, and 687 parts of 37% formalin, The same method as in Example 1 was used. By this method, 1190 parts of a novolak type phenol resin E having a weight average molecular weight of 400 was obtained.

(Synthesis Example 6)
The same method as in Example 1 was used except that 100 parts of 2,5-xylenol, 25 parts of 3,5-xylenol and 642 parts of 37% formalin were used. By this method, 1024 parts of a novolak type phenol resin F having a weight average molecular weight of 4400 was obtained.

(Synthesis Example 7)
The same method as in Example 1 was used except that 400 parts of 2,5-xylenol, 100 parts of 3,5-xylenol and 823 parts of 37% formalin were used. By this method, 1350 parts of a novolac type phenol resin G having a weight average molecular weight of 3600 was obtained.

(Comparative Synthesis Example 1)
The same as Example 1 except that 2,5-xylenol and 3,5-xylenol were not blended, 160 parts of hexane, 10 parts of oxalic acid, and 600 parts of 37% formalin were used. The method was used. By this method, 900 parts of a novolak type phenol resin H having a weight average molecular weight of 6000 was obtained.

(Comparative Synthesis Example 2)
The same method as in Example 1 was used except that 2,5-xylenol was not blended, 250 parts of 3,5-xylenol was used, and 641 parts of 37% formalin was used. By this method, 1130 parts of a novolak type phenol resin I having a weight average molecular weight of 3100 was obtained.

(Comparative Synthesis Example 3)
Other than using 700 parts of m-cresol, 300 parts of p-cresol, 250 parts of 2,5-xylenol, not using 3,5-xylenol and hexane, and using 600 parts of 37% formalin. The same method as in Example 1 was used. By this method, 1163 parts of a novolak type phenol resin J having a weight average molecular weight of 5500 was obtained.

<Evaluation of novolac type phenolic resin>
Measurement of Orthogonalization Rate (o'o Bond Rate) by ¹³ C-NMR Nuclear magnetic resonance spectroscopy (NMR) was performed on the obtained phenol resins A to I. Note that JNM-AL300 manufactured by JEOL Datum was used for NMR measurement.
From the result obtained by NMR measurement, each bond rate of op, pp ′, and oo ′ of the resin was obtained. The ratio of the op bond was 40 to 35 ppm, the ratio of the pp ′ bond was 35 to 28.5 ppm, and the ratio of the oo ′ bond was determined from the area at the time of integration at 28.5 to 25 ppm. As measurement conditions, the number of integrations was 10,000.

  The orthorectification rates of the phenol resins A to G obtained in Synthesis Examples 1 to 7 were 30%, 28%, 32%, 33%, 28%, 25%, and 30%, respectively. Moreover, the ortho-rectification rates of the phenol resins H to J obtained in Comparative Synthesis Examples 1 to 21 were 21%, 38%, and 18%, respectively. In addition, the orthoification rate of phenol resin AJ is also shown in the following Table 1.

<Preparation of resin composition for photoresist>
Example 1
20 parts of the novolak type phenol resin A obtained in Synthesis Example 1 and 5 parts of 2,3,4-trihydroxy-benzophenone ester of naphthoquinone 1,2-diazide-5-sulfonic acid were mixed with 75 parts of propylene glycol monomethyl ether acetate (PGMEA). Dissolved in the part. Then, it filtered using a 0.1 micrometer membrane filter, and prepared the resin composition for photoresists.

(Examples 2 to 7)
A resin composition for photoresist was prepared in the same manner as in Example 1 except that the novolak type phenol resins B to G obtained in Synthesis Examples 2 to 7 were used as the novolak type phenol resin.

(Comparative Examples 1-3)
A resin composition for a photoresist was prepared in the same manner as in Example 1 except that the novolak type phenol resins H to J obtained in Comparative Synthesis Examples 1 to 3 were used as the novolak type phenol resin.

  About the resin composition for photoresists obtained in Examples 1-7 and Comparative Examples 1-3, the measurement and evaluation shown below were performed.

<Evaluation method of characteristics>
(1) Residual film ratio measuring method The photoresist resin composition was applied onto a 3 inch silicon wafer with 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. . The silicon wafer was then immersed in a developer (2.38% tetramethylammonium hydroxide aqueous solution) for 60 seconds, washed with water, and dried on a 110 ° C. hot plate for 100 seconds. The ratio of the film thickness after development to the film thickness before development was expressed as a percentage, and was defined as the remaining film ratio. Thus, the degree of residual film (resistance) when used as a photosensitive agent and a photoresist can be understood. The higher the numerical value, the higher the remaining film rate. The unit is%.

(2) Sensitivity Measurement Method The photoresist resin composition was applied to a 3-inch silicon wafer with 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, repeated test chart mask on the silicon ^{wafer, 5mJ / cm 2, 10mJ /} cm 2, 15mJ / cm 2 of ultraviolet irradiation, respectively, then developing solution (2.38% tetramethylammonium hydroxide aqueous solution) Developed for 60 seconds. The obtained pattern was observed with a scanning electron microscope and the pattern shape was evaluated according to the following criteria.
A An image can be formed at 5 mJ / cm ² .
B 5 mJ / cm in the ^two images can not be formed, the image can be formed at 10 mJ / cm ^2.
C 10 mJ / cm at ² image can not be formed, the image can be formed at 15 mJ / cm ^2.

(3) Measurement of resolution The obtained resin composition for photoresist was applied onto a silicon wafer using a spin coater and pre-baked at 110 ° C. for 100 seconds to form a resist film having a thickness of 1.5 μm. This was exposed using ultraviolet rays through a pattern mask in which a line width of 100 μm to 1 μm was engraved. Immediately after the exposure, the film was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, washed with water and dried to obtain a positive pattern. At that time, the minimum resolution of the photoresist pattern that can be resolved with a constant exposure amount is defined as the limit resolution. The unit is μm.

(4) Pattern shape The resin composition for photoresist was apply | coated on the silicon wafer using the spin coater, and it prebaked at 110 degreeC for 100 second, and formed the resist film with a film thickness of 1.5 micrometers. This was exposed using ultraviolet rays through a pattern mask in which a line width of 5 μm was engraved. Immediately after the exposure, the film was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, washed with water and dried to obtain a positive pattern. The shape of the resist pattern on the silicon wafer is observed with a scanning electron microscope, the angle of the upper corner of the cross section of the resist rectangular pattern is measured, ○ for 110 degrees or less, ○, 110 degrees or more, or rounded corners A mark which is clearly marked and cannot be measured was marked as x.

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

  From the results in Table 1, the photoresist resin compositions of Examples 1 to 7 have a good balance of sensitivity, pattern shape, resolution, and residual film properties as compared to the photoresist resin compositions of Comparative Examples 1 to 3, respectively. It was excellent. The resist using this photoresist resin composition was excellent in fine workability. As a result, when a liquid crystal device was actually produced using the photoresist composition described in the examples, a liquid crystal device having a designed fine circuit could be obtained.

  In addition, the comparative example 1 uses only m-cresol and p-cresol as phenols at the time of synthesize | combining a novolak-type phenol resin, Furthermore, an ortho-conversion rate is less than 23%. The composition for photoresist of Comparative Example 1 had a low residual film ratio, a large limit resolution, a pattern having a substantially semi-elliptical shape, and an unclear angle.

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

  In Comparative Example 3, although m-cresol, p-cresol and 2,5-xylenol were used as phenols when synthesizing the novolak type phenol resin, the temperature during synthesis was as low as 100 ° C. Is less than 23%. The photoresist composition of Comparative Example 3 had a low residual film ratio, a large limit resolution, a pattern cross-sectional shape that was substantially semi-elliptical, and the angle was not clear.

  The resin composition for photoresists of the present invention has a good pattern shape, and has high sensitivity, high resolution, and high residual film properties. Therefore, it is suitable for manufacturing fine circuits of liquid crystal display devices and semiconductor integrated circuits. Can be used.

Claims (8)

(A) Orthogonation rate obtained by reacting phenols and aldehydes containing metacresol, paracresol and 2,5-xylenol under the temperature conditions of 110 ° C. or higher and 220 ° C. or lower in the presence of an acid catalyst. More than 23% high ortho novolac type phenolic resin,
(B) a naphthoquinonediazide derivative;
(C) a solvent;
Containing a resin composition for photoresist.   The resin composition for photoresists according to claim 1, wherein a mixing ratio of the metacresol and the paracresol is 90:10 to 50:50 by mass ratio.   The resin composition for photoresists according to claim 1 or 2, wherein the phenol further contains 3,5-xylenol.   The resin composition for photoresists according to claim 3, wherein a mixing ratio of the 2,5-xylenol and the 3,5-xylenol is 100: 0 to 50:50 by mass ratio.   The ratio of the total blending amount of the metacresol and the paracresol and the total blending amount of the 2,5-xylenol and the 3,5-xylenol is 90:10 to 60:40 by mass ratio. 5. The resin composition for photoresists according to 4.   The photoresist resin composition according to claim 1, wherein the photoresist resin composition is a positive resist resin composition.   A photoresist comprising the photoresist resin composition according to any one of claims 1 to 6.   A method for producing a liquid crystal device, comprising a step of performing photolithography using the resin composition for photoresists according to claim 1.