KR100585536B1 - Negative-type photoresist composition comprising casein, and process for preparing same - Google Patents

Abstract

The present invention relates to a negative type photoresist composition containing casein and a method for preparing the same, comprising: a) acid casein, b) a mixture of strong alkalis and weak alkalis, and c) according to the present invention. The aqueous photoresist composition including the sensitivity control additive has little change in sensitivity and pH in the course of preservation for a period of time, and has excellent resolution, which is advantageously used as photoresist materials such as shadow masks, IC lead frames, color filters, and printed circuit boards. Can be used.

Negative photoresist, casein, casein aqueous solution, sensitivity

Description

Negative photoresist composition comprising casein and a method for manufacturing the same {NEGATIVE-TYPE PHOTORESIST COMPOSITION COMPRISING CASEIN, AND PROCESS FOR PREPARING SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative type photoresist composition containing casein and a method of manufacturing the same. Specifically, the present invention is environmentally friendly, and has excellent resolution and adhesion to a film. The present invention relates to a photoresist composition containing an aqueous casein solution having the advantage of being completely dissolved in water, and a method of preparing the same.

 In general, in the manufacturing process of electronic components, including shadow masks, IC leadframes, color filters, printed circuit boards, etc., fine patterns are formed using photolithography techniques, and these techniques require a resist to protect the material during the etching process. Do.

The process of forming the fine pattern will be described in detail. First, a resist composition is applied onto a substrate to form a photoresist thin film, and the photoresist film is exposed using a photomask having a desired pattern, followed by development, cleaning, and the like. The treatment of is performed to form a resist pattern. Subsequently, the surface of the substrate on which the resist pattern is formed is etched with a strong acid or the like to open fine lines and windows, thereby forming a desired pattern on the substrate, and finally removing the resist film remaining on the substrate. A substrate on which a pattern is formed can be obtained.

Examples of the water-soluble polymer used as the photoresist material include polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, gelatin, casein, and the like, and polyvinyl alcohol, polyvinyl pyrrolidone, and polyacryl. Amide-based and gelatinous polymers have high sensitivity, making it difficult to control the sensitivity to form fine patterns. The resolution and adhesion are significantly lower than casein, and are greatly affected by temperature and humidity. It is the cause of defects. However, casein, which is a kind of protein, is easy to control sensitivity, has excellent resolution and adhesion between membranes, and is excellent for forming a fine pattern. Compared with the advantages of being environmentally friendly, it has been widely used as a photoresist material in manufacturing processes such as shadow masks, IC lead frames, color filters, and printed circuit boards requiring high resolution patterns.

Casein, also known as casein, is the main ingredient in milk, is best studied for casein in milk, and human or sheep casein is known to have similar properties. Casein is about 3% in milk and accounts for about 80% of the total protein in milk and is available in two forms: acid casein and caseinate.

Acid casein can be obtained by adding acid to milk with a pH of 6.2 to 6.8 and adjusting the pH to 4.6 to reach the isoelectric point and to separate the precipitate which precipitates as the casein micelle loses charge and solidifies, depending on the type of acid used. Casein sulfate, casein hydrochloride, and the like. On the other hand, the caseinate salt is an alkali salt, and examples thereof include sodium caseinate and calcium caseinate, and are easy to be soluble, but due to severe changes in general physical properties such as viscosity, it is difficult to control the coating thickness when used as a photoresist material. However, they are relatively expensive compared to acid casein and are not widely used in recent years.

In addition, casein used as a photoresist material that requires high resolution must be high purity casein with a fat content of less than 0.2% (by weight) and a protein content of 88% (by weight).

Conventional methods for preparing the casein-containing photoresist composition include the addition of a sensitizer, specifically, casein powder, nonvolatile alkali (e.g., borax), and a surfactant in which casein is adsorbed. Thereafter, there is a method of preparing a photoresist composition containing casein by adding a sensitizer (for example, thioxanthone-4-sulfonic acid salt and N-methylol acrylamide, etc.) to a certain amount, and adding a photosensitizer such as ammonium dichromate. However, although this method can adjust the sensitivity by using a sensitizer, experiments show that the sensitivity of the sensitizer is very weak in terms of storage stability since the cancer reaction caused by the sensitizer is severe over time. Can be.

In recent years, casein powders are mixed with casein powder, borax as nonvolatile alkali, and ammonia water as volatile alkali, and then the additives such as surfactants, adhesion enhancers, and plasticizers are added to form a photoresist composition containing casein. Manufacture. However, the photoresist composition prepared by this method can adjust the sensitivity by adjusting the pH to an appropriate range of 7.7 to 8.3 using volatile alkali, but the pH of the aqueous casein solution evaporates over time as the volatile alkali ammonia water evaporates over time. It can be seen through the experiment that there is a disadvantage that the storage stability is insufficient because the decrease and the sensitivity is changed. Such changes in pH and sensitivity can cause many problems. For example, when the pH is lowered to 7.5 or lower during preservation, the casein solubility becomes unstable, and when combined with a photosensitive agent, it is combined with a photosensitive liquid having a pH lower than any reference pH, so that the development process does not proceed smoothly. If the sensitivity is poorly formed and the sensitivity, which is adapted to be used under any process conditions, changes over time, problems such as making it impossible to form a desired pattern under existing process conditions occur. On the other hand, when the pH is 8.5 or more, there is a problem that when the photosensitive agent is mixed, the photosensitive agent is converted into ions that do not react under ultraviolet light.

Accordingly, an object of the present invention is to provide a casein-containing negative photoresist composition and a method for producing the same, having excellent resolution without changing pH and sensitivity even after time passes.

In order to achieve the above object, the present invention provides an aqueous negative photoresist composition comprising a) acid casein, b) a mixture of strong alkalis and weak alkalis, and c) sensitivity control additives and a method for producing the same.

Hereinafter, the present invention will be described in more detail.

Specifically, the negative photoresist composition according to the present invention uses nonvolatile alkali instead of volatile alkali so as not to cause changes in pH and sensitivity over time, and adjusts sensitivity instead of conventional sensitizers so as not to deteriorate storage by causing a dark reaction. It is characterized by including an additive.

In addition, the photoresist composition of the present invention, in addition to the above components, the adhesion enhancer for increasing the adhesion to the substrate to improve the etching resistance in the etching process; Preservatives to prevent deterioration of sensitivity and resolution due to propagation of microorganisms such as yeast and bacteria; And other additives such as surfactants, plasticizers, and the like to increase the applicability to the substrate and the dispersibility of each of the substances contained in the aqueous casein solution.

Hereinafter, each component is demonstrated.

Examples of a) acid casein used in the present invention include high-purity hydrochloric acid casein and sulfuric acid casein having a fat content of less than 0.2% (by weight) and a protein content of 88% (by weight) or more. It is preferably included in an amount ranging from 10 to 15% by weight based on the total weight of the silver photoresist composition.

As a mixture of the non-volatile strong alkali and weak alkali of b), a mixed alkali aqueous solution of strong alkali and weak alkali in a weight ratio of 1: 1 to 1: 5 can be preferably used. The strong alkali may be lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and the like, and the weak alkali may be a borax compound such as sodium tetraborate pentahydrate and sodium tetraborate decahydrate, and the non-volatile strong alkali and The mixture of weak alkalis is preferably included in amounts ranging from 0.1 to 10% by weight, based on the total weight of the photoresist composition. According to the present invention, the photoresist composition including the nonvolatile alkali has little change in pH and sensitivity over time, and thus has excellent storage stability.

The sensitivity adjusting additive of c) is added to increase the resolution of the photoresist composition and to facilitate the sensitivity control. Examples of the sensitivity adjusting additive used in the present invention include orthoboric acid, metaborate, sodium metaborate, and sodium tetraborate. Boric acid-based compounds such as potassium metaborate, potassium pentaborate, and the like, and are preferably included in an amount ranging from 0.1 to 10% by weight based on the total weight of the photoresist composition.

As other additives, the adhesion enhancer is added to increase the adhesion of the photoresist composition to the substrate to improve the etching resistance in the etching process, for example, γ-aminopropyltrimethoxysilane, γ-aminopropyl Silane compounds such as triethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, and the like, and the like based on the total weight of the photoresist composition. It is preferably included in amounts ranging from 0.1 to 10% by weight.

Preservatives are added to prevent the growth of bacteria and fungi, such as yeast, bacteria, and the like, and triazine-based preservatives such as N-trishydroxyethylhexahydro-S-triazine, hexahydrotriazine, and the like. It is preferably included in an amount ranging from 0.1 to 10% by weight based on the total weight of the resist composition.

In addition, as other additives, polyoxyethylene-based nonionic surfactants such as polyoxyethylene oleate to increase the applicability of the prepared photoresist composition to the substrate and the dispersibility of each component contained in the aqueous casein solution One ester), and a plasticizer (eg, ketone-based compounds such as camphor, and glycol-based compounds such as ethylene glycol, propylene glycol, etc.) for alleviating the hard properties of casein; Their total addition amount is preferably included in an amount ranging from 1 to 20% by weight based on the total weight of the photoresist composition.

The photoresist composition containing casein of the present invention is prepared by making the viscosity of the aqueous casein solution used be about 100 to 200 cps with a Brookfield viscometer, and performing under optimum mixing conditions.

The method for preparing the photoresist composition of the present invention comprises the steps of: i) dispersing acid casein in ion-exchanged water, and then adding the mixed alkali aqueous solution to solubilize the casein; ii) sterilizing the reaction solution obtained in step i); And iii) adding the sensitivity adjusting additive, and other additives such as adhesion enhancers and preservatives to the aqueous solution obtained in step ii), and then mixing them.

Specifically, the method of preparing the photoresist composition, in step i), the acid casein powder is placed in ion-exchanged water and stirred for about 30 minutes to disperse, and then the strong alkali and weak alkali A mixed aqueous alkali solution is added and an aqueous reaction is carried out at 75 to 85 ° C. for 5 to 7 hours. Here, when the solubilization reaction temperature is less than the above range, casein solubilization does not proceed smoothly, and when it exceeds the above range, casein degeneration is induced such that the casein molecule is disconnected while the casein is carbonized.

In step ii), the treated casein is sterilized at 90 to 95 ° C. for 1 to 2 hours to remove bacteria or yeast present in the aqueous casein solution, thereby maximizing the effect of the preservative added thereafter.

In addition, in step iii), after cooling the temperature of the sterilized casein aqueous solution to 70 ℃ or less, and then mixed by adding a sensitivity control additive, adhesion enhancer, preservatives and other additives.

The negative photoresist composition of the present invention is very excellent in storage stability, sensitivity and resolution compared to the casein aqueous solution used as a conventional photoresist material.

Hereinafter, the present invention will be described in more detail based on the following Examples and Comparative Examples. However, the following examples are not intended to limit the invention only.

Example 1

13% by weight of hydrochloric acid casein powder was added to 63.25% by weight of ion-exchanged water, stirred and dispersed for about 30 minutes, and then 1% by weight of lithium hydroxide dissolved in about 20% by weight of ion-exchanged water and sodium tetraborate decahydrate 1 The weight percent was added to solubilize at 80 DEG C for 5 hours. Subsequently, the solubilized casein aqueous solution was sterilized at 90 ° C. for 1 hour, and then the temperature was cooled to 70 ° C. or lower, 0.6% by weight of potassium metaborate, 0.3% by weight of γ-aminopropyltriethoxysilane, and polyoxyethylene A photoresist composition was prepared by adding and mixing 0.35% by weight of oleyl ester and 0.5% by weight of N-trishydroxyethylhexahydro-S-triazine. The components and contents included in the photoresist composition prepared in Example 1 are summarized in Table 1 below.

 ingredient Content (% by weight) Ion exchange water 83.25 Hydrochloric acid casein 13.00 Sodium tetraborate decahydrate 1.00 Lithium hydroxide 1.00 Potassium metaborate 0.60 γ-aminopropyltriethoxysilane 0.30 Polyoxyethylene oleyl ester 0.35 N-trishydroxyethylhexahydro-S-triazine 0.50

Example 2

To the photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 2 below.

 ingredient Content (% by weight) Ion exchange water 82.75 Hydrochloric acid casein 13.00 Sodium tetraborate decahydrate 2.00 Lithium hydroxide 1.00 Potassium metaborate 0.30 γ-aminopropyltriethoxysilane 0.30 Polyoxyethylene oleyl ester 0.35 N-trishydroxyethylhexahydro-S-triazine 0.30

Example 3

To a photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 3.

 ingredient Content (% by weight) Ion exchange water 83.60 Hydrochloric acid casein 13.00 Sodium tetraborate decahydrate 1.00 Sodium hydroxide 1.00 Sodium metaborate 0.60 3-chloropropylmethyldimethoxysilane 0.20 Polyoxyethylene oleyl ester 0.30 N-trishydroxyethylhexahydro-S-triazine 0.30

Example 4

To a photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 4.

 ingredient Content (% by weight) Ion exchange water 84.35 Hydrochloric acid casein 12.00 Sodium tetraborate decahydrate 1.00 Sodium carbonate 1.00 Orthoboric acid 0.60 3-chloropropylmethyldimethoxysilane 0.30 Polyoxyethylene oleyl ester 0.40 N-trishydroxyethylhexahydro-S-triazine 0.35

Example 5

To a photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 5.

 ingredient Content (% by weight) Ion exchange water 84.50 Hydrochloric acid casein 12.00 Sodium tetraborate decahydrate 1.50 Lithium hydroxide 1.00 Potassium pentaborate 0.30 3-chloropropylmethyldimethoxysilane 0.20 Polyoxyethylene oleyl ester 0.20 N-trishydroxyethylhexahydro-S-triazine 0.30

Example 6

To a photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 6.

 ingredient Content (% by weight) Ion exchange water 84.65 Casein sulfate 12.00 Sodium tetraborate decahydrate 1.00 Sodium hydroxide 1.00 Orthoboric acid 0.50 N- (2-aminoethyl) -3-aminopropyltrimethoxysilane 0.30 Polyoxyethylene oleyl ester 0.25 N-trishydroxyethylhexahydro-S-triazine 0.30

Example 7

To the photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 7.

 ingredient Content (% by weight) Ion exchange water 84.80 Casein sulfate 12.00 Sodium tetraborate decahydrate 1.10 Sodium carbonate 0.80 Potassium metaborate 0.30 γ-aminopropyltriethoxysilane 0.30 Polyoxyethylene oleyl ester 0.40 N-trishydroxyethylhexahydro-S-triazine 0.30

Comparative Example 1

To the photoresist composition was prepared in the same manner as in Example 1 with the ingredients and contents shown in Table 8.

 ingredient Content (% by weight) Ion exchange water 83.10 Casein sulfate 13.00 Sodium tetraborate decahydrate 2.00 ammonia 1.00 γ-aminopropyltriethoxysilane 0.30 Polyoxyethylene oleyl ester 0.30 N-trishydroxyethylhexahydro-S-triazine 0.30

Comparative Example 2

To a photoresist composition was prepared in the same manner as in Example 1 with the components and contents shown in Table 9.

 ingredient Content (% by weight) Ion exchange water 85.50 Hydrochloric acid casein 12.00 Sodium tetraborate decahydrate 1.50 ammonia 1.20 3-chloropropylmethyldimethoxysilane 0.20 Polyoxyethylene oleyl ester 0.30 N-trishydroxyethylhexahydro-S-triazine 0.30

Test Example 1: Physical property test

The viscosity, pH, sensitivity, adhesion and resolution of each of the photoresist compositions prepared in Examples 1 to 7, and Comparative Examples 1 and 2 were measured by the following test methods. At this time, an iron plate for a shadow mask, a copper plate for an IC lead frame, a board for a printed board, etc. were used as a test substrate.

Physical properties such as viscosity, pH, adhesion, etc. were measured immediately after preparation of the photoresist composition, and the physical properties were measured again three months after the preparation of the photoresist composition to check storage stability; Physical properties such as sensitivity and resolution were measured after adding photosensitizers such as dichromic acid compounds to the prepared photoresist composition. When the casein aqueous solution and the dichromate compound are mixed, the dichromate compound is dissociated in the aqueous solution and exists as a dichromate ion, which is a hexavalent chromium ion, and an ion of another compound, and the hexavalent chromium ion is reduced to trivalent chromium ion by light irradiation such as ultraviolet rays. As a result, crosslinking reactions are known to occur by coordinating functional groups such as amines and carboxyl groups in casein molecules, and more precise mechanisms have not yet been identified.

Casein aqueous solution to which the photosensitizer is added as described above is thickened due to a dark reaction as the time to stand for a long time, and the sensitivity is gradually increased, so it is generally stored in a state in which the photosensitizer is not added during storage. In addition, since the dark reaction is easy to occur when the temperature and humidity is high, all the process conditions after the addition of the photosensitizer to prevent the light, such as ultraviolet rays, to keep the cool and low humidity as possible.

The viscosity was measured at 25 ° C. using a Brookfield viscometer, the pH was measured using an ion titrator, and the adhesion test was measured by comparing the degree of drop by performing a cross-cutting test.

In addition, the test for sensitivity and resolution was performed by mixing 1.5% by weight of ammonium dichromate with respect to 100% by weight of each photoresist composition to impart photosensitivity, and then applying it to the iron mask for shadow mask by a rotary coating method, and then applying the applied photosensitive liquid. The film was dried using hot air in an oven to form a resist film. Subsequently, after exposing with ultraviolet rays using two light sources, such as a mercury lamp and a gallium, sensitivity was measured using Fuji's negative sensitivity measurement film. Next, the exposed resist film was developed using industrial water, and then dried in an oven using hot air to prevent staining due to residual industrial water, and then the resolution was measured. The results are shown in Table 10 below.

Viscosity (cps) pH Sensitivity (only) Adhesion (test space / remaining space) definition Example 1 131.0 8.02 4.5 100/100 ◎ Example 2 129.5 8.00 6.0 100/100 ◎ Example 3 128.0 8.10 5.0 100/100 ◎ Example 4 115.3 8.05 4.5 100/100 ◎ Example 5 116.1 8.12 5.0 100/100 ◎ Example 6 115.4 8.03 4.3 100/100 ◎ Example 7 112.8 8.00 5.0 100/100 ◎ Comparative Example 1 128.2 8.01 6.0 100/98 ◎ Comparative Example 2 111.9 8.04 10.5 100/95 ◎   ◎: Pattern formation is clean and no residual material remains at the pattern edges △: Pattern formation is not clean and a large amount of residual material remains

In addition, after leaving the prepared photoresist composition for two months to verify the reliability of the storage stability of each photoresist composition, and measuring the viscosity, pH, sensitivity, adhesion and resolution in the same manner as described above, and the results Table 11 shows.

Viscosity (cps) pH Sensitivity (only) Adhesion (test space / remaining space) definition Example 1 129.0 8.00 5.0 100/100 ◎ Example 2 131.0 8.00 6.4 100/100 ◎ Example 3 129.4 8.06 5.0 100/100 ◎ Example 4 114.6 8.06 5.1 100/100 ◎ Example 5 113.0 8.07 6.0 100/100 ◎ Example 6 113.1 8.02 5.0 100/100 ◎ Example 7 110.3 8.00 5.8 100/100 ◎ Comparative Example 1 112.7 7.73 10.2 100/97 △ Comparative Example 2 103.5 7.82 15.0 100/95 △   ◎: Pattern formation is clean and no residual material remains at the pattern edges △: Pattern formation is not clean and a large amount of residual material remains

From Tables 11 and 12, the photoresist composition (Example 1-7) of the present invention is excellent in storage stability and adhesion, such as little change in sensitivity and resolution even after 3 months, while using volatile alkali or adding a sensitivity control additive. If not (Comparative Examples 1 and 2), it can be seen that the storage stability is not good, such as the sensitivity is too high, or the pH, sensitivity and resolution change over time.

The photoresist composition including casein prepared according to the present invention has excellent storage stability and resolution, easy sensitivity control, and excellent adhesion, and thus has excellent etching resistance in the etching process, which is advantageous for forming a fine pattern. Can be used.

Claims (10)

An aqueous negative photoresist composition comprising a) acid casein, b) a mixture of strong and weak alkali, which is nonvolatile, and c) a sensitivity control additive. The method of claim 1, 10-15% by weight of acid casein, Strong alkali from 0.1 to 10% by weight, Weak alkali from 0.1 to 10% by weight, 0.1 to 10% by weight of the sensitivity control additive and the remaining amount of water An aqueous negative photoresist composition comprising a. The method of claim 1, An aqueous negative photoresist composition, wherein the acid casein is selected from casein hydrochloride and casein sulfate. The method of claim 1, An aqueous negative photoresist composition, wherein the strong alkali is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide and sodium carbonate. The method of claim 1, An aqueous negative photoresist composition, wherein the weak alkali is selected from sodium tetraborate pentahydrate and sodium tetraborate decahydrate. The method of claim 1, An aqueous negative photoresist composition, wherein the sensitivity control additive is selected from orthoboric acid, metaboric acid, sodium metaborate, sodium tetraborate, potassium metaborate, and potassium pentaborate. The method of claim 1, Add adhesion promoter selected from γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and 3-chloropropylmethyldimethoxysilane An aqueous negative photoresist composition comprising a. The method of claim 1, An aqueous negative photoresist composition, further comprising a preservative selected from N-trishydroxyethyl hexahydro-S-triazine and hexahydrotriazine. i) solubilizing casein by adding a mixed alkaline aqueous solution of strong and weak alkali to the acid casein water dispersion; ii) sterilizing the reaction solution obtained in step i); And iii) adding a sensitivity control additive to the aqueous solution obtained in step ii) and then mixing the photoresist composition according to claim 1. The method of claim 9, The aqueous solution is added and the aqueous solution is reacted at 75 to 85 ° C. for 5 to 7 hours.