TW201434942A - Etching-masking composition and pattern formation method - Google Patents

Abstract

The purpose of the present invention is to promote the printability of an etch-masking composition, when printed on the substrate in a solar cell. The solving means is an etch-masking composition used for the substrate in the solar cell, as an embodiment of the present invention, which is non-photosensitiv and contains 100 parts by mass of novolac resin (A), 20-100 parts by mass of SiO2 particles (B) and solvent (C).

Description

Etching mask composition and pattern forming method

The present invention relates to a composition for an etching mask used as a masking agent when etching a substrate for a solar cell.

In the solar cell manufacturing step, a masking agent is used in the local etching process of the substrate. Conventionally, although a photoresist has been used in this step, the application of the printed resist has been discussed for the purpose of reducing the number of steps. A strong acid such as hydrofluoric acid or nitric acid is used as the etching liquid for etching the substrate for a solar cell. Therefore, the characteristics required for the printing type resist are required to be resistant to acidity of the etching liquid at the time of etching, and can be formed by patterning by a printing method.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 9-293888

In the past printing resists, to ensure adequate acid resistance There is still room for improvement, while at the same time faithfully reproducing the printed design to form a good pattern. In addition, there is room for improvement in terms of printing stability when performing continuous printing.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a technique for improving printability when a composition for an etching mask is printed on a substrate for a solar cell.

The same state of the present invention is a composition for etching a mask. The etch mask composition includes an etch mask of 100 parts by mass of the novolak resin (A), 20 to 100 parts by mass of the SiO ₂ particles (B), and a non-photosensitive solar cell substrate of the solvent (C). Use the composition.

According to the above composition for etching the mask, the printability at the time of printing on the substrate for a solar cell can be improved.

In the composition for etching the mask described above, the solvent (C) may also contain a solvent (C1) having a boiling point of 190 ° C or higher. The SiO ₂ particles (B) may also be hydrophilic. Further, a lanthanide, acrylic or fluorine-based surfactant (D) may be further provided.

Other aspects of the invention are pattern forming methods. The pattern forming method includes a step of forming a mask pattern on a substrate by a printing method using a composition for an etching mask of a substrate for a solar cell of any of the above-described states, and baking the mask pattern. The steps of etching the substrate, transferring the mask pattern, and removing the mask pattern.

According to the present invention, it is possible to improve the acid resistance and printability when the composition for an etching mask is printed on a substrate for a solar cell.

10‧‧‧Solid cell substrate

20‧‧‧ mask pattern

[Fig. 1] Fig. 1 (A) to Fig. 1 (C) are schematic cross-sectional views showing a pattern forming step of a substrate.

The composition for an etching mask of the embodiment is non-photosensitive, and is suitable for use as an etching mask used for performing local etching treatment on a substrate for a solar cell.

The composition for an etching mask of the embodiment includes 100 parts by mass of the novolak resin (A), 20 to 100 parts by mass of the SiO ₂ particles (B), and a solvent (C). Hereinafter, each component of the composition for an etching mask of the embodiment will be described in detail.

The novolac resin (A) is obtained by reacting the phenols exemplified below and the aldehydes exemplified below with an acidic catalyst such as hydrochloric acid, sulfuric acid, formic acid, oxalic acid or p-toluenesulfonic acid. Novolak resin, etc.

Examples of the phenolic compound include phenol; cresols such as m-cresol, p-cresol, and o-cresol; 2,3-xylenol, 2,5-xylenol, and 3,5-di a xylenol such as cresol or 3,4-xylenol; m-ethylphenol, p-ethylphenol, o-ethylphenol, 2,3,5-trimethylphenol, 2,3, 5-triethylphenol, 4-tert-butylphenol, 3- Tert-butyl phenol, 2-tert-butyl phenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, etc. alkylphenols; p-methoxy Alkoxyphenols such as phenol, m-methoxy phenol, p-ethoxy phenol, m-ethoxy phenol, p-propoxy phenol, m-propoxy phenol, etc.; o-isopropenyl An isopropenylphenol such as phenol, p-isopropenylphenol, 2-methyl-4-isopropenylphenol or 2-ethyl-4-isopropenylphenol; or an arylphenol such as phenylphenol; Polyhydroxyphenols such as 4,4'-dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone, and gallic phenol. These may be used alone or in combination of two or more. Among these phenols, m-cresol and p-cresol are particularly preferred.

Examples of the aldehydes include formaldehyde, polyoxymethylene, and trisole. , acetaldehyde, propionaldehyde, butyraldehyde, trimethyl acetaldehyde, acrolein, crotonaldehyde, cyclohexyl aldehyde, furfural, furan acrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, α- Phenylpropyl aldehyde, β-phenylpropyl aldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methyl Benzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, cinnamaldehyde, and the like. These may be used alone or in combination of two or more. Among these aldehydes, formaldehyde is preferred from the viewpoint of easiness of availability.

The novolak resin (A) may be composed of one type of novolak resin, or may be composed of two or more types of novolak resins. When the novolac resin (A) is composed of two or more kinds of novolak resins, the Mw of the novolak resin is not particularly limited, but it is preferably adjusted to a total of M-100 of the novolak resin (A) to be 1000 to 100,000. . Further, the novolak resin (A) is a solvent for etching the composition for the mask. The component (solid content) other than (C) is preferably contained in an amount of 20 to 80% by mass, more preferably 60 to 80% by mass.

The property common to the novolac resin (A) described above is excellent in acid resistance.

The content of the SiO ₂ particles (B) is 20 to 100 parts by mass based on 100 parts by mass of the novolak resin (A). When the content of the SiO ₂ particles (B) is less than 20 parts by mass based on 100 parts by mass of the novolak resin (A), it is difficult to obtain sufficient printability. On the other hand, when the content of the SiO ₂ particles (B) is more than 100 parts by mass based on 100 parts by mass of the novolak resin (A), it is difficult to ensure sufficient acid resistance. The average particle diameter of the SiO ₂ particles (B) is preferably from 7 nm to 30 nm. When the average particle diameter of the SiO ₂ particles (B) is less than 7 nm, the particles are less likely to aggregate. On the other hand, when the average particle diameter of the SiO ₂ particles (B) is more than 30 nm, the viscosity increasing property and the thixotropy are lowered. Further, the SiO ₂ particles (B) are preferably hydrophilic. Here, "hydrophilic" means that a hydroxyl group (OH group) is present on the surface of the particle. Printing accuracy can be improved by making the SiO ₂ particles (B) hydrophilic.

The content of the solvent (C) is preferably from 30 to 70% by mass based on the entire composition for the etching mask.

The solvent (C) is preferably a solvent (C1) having a boiling point of 190 ° C or higher. Specific examples of the solvent (C1) include ethylene glycol, hexanediol, propylene glycol diacetate, 1,3-butylene glycol diacetate, diethylene glycol, dipropylene glycol, and diethylene glycol alone. Methyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monophenyl ether, Diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol single Methyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monophenyl ether acetate, dipropylene glycol monomethyl ether Acid ester, diethylene glycol monobutyl ether acetate, glycerol, benzyl alcohol, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl Acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl Acid ester, 3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate Dihexyl ether, benzyl acetate, ethyl benzoate, diethyl maleate, γ-butyrolactone, terpineol, and the like. These may be used alone or in combination of two or more.

The etching composition of the embodiment may further contain a solvent other than the above solvent (C1). However, the content of the solvent (C1) relative to the entire solvent is 70% by mass or more, and more preferably 90% by mass or more.

The solvent other than the solvent (C1) (solvent (C2) having a boiling point of less than 190 ° C) may, for example, be a ketone such as cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone or 2-heptanone. Polyols such as ethylene glycol and propylene glycol; polyols such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), dipropylene glycol dimethyl ether, and propylene glycol propyl ether Derivatives; other esters of butyl acetate, ethyl acetate, butyl lactate, diethyl oxalate, and the like. Among these, propylene glycol monomethyl ether acetate, 2-heptanone, and butyl acetate are preferred.

The composition for etching the mask of the embodiment may further It has a lanthanide, acrylic or fluorine-based surfactant (D).

The surfactant (D) of the lanthanoid series is BYK-310 (manufactured by BYK-Chemie Co., Ltd.) which has a polyester modified polydimethyl siloxane as a main component, and an aralkyl modified polymethylalkane. BYK-323 (manufactured by BYK) containing hydroxy oxane as a main component, BYK-SILCLEAN 3720 (manufactured by BYK) containing a polyether modified polydimethyl methoxy siloxane containing a hydroxyl group as a main component, and a polyether modified methyl group KF-353 (manufactured by Shin-Etsu Chemical Co., Ltd.) having a polysiloxane as a main component. The acrylic surfactant (D) is exemplified by BYK-354 (manufactured by BYK). In addition, examples of the fluorine-based surfactant (D) include KL-600 (manufactured by Kyoeisha Chemical Co., Ltd.). Among these, a surfactant of a lanthanoid system is preferred, and a surfactant of a polydimethyl siloxane is preferred. The amount of the surfactant (D) to be added is preferably 0.001% by mass to 1.0% by mass, and more preferably 0.01% by mass to 0.1% by mass based on the entire composition for the etching mask.

In the above, the composition for the etching mask is formed in a state in which it is formed as a mask on the solar cell substrate by printing by using a novolac resin (A) excellent in acid resistance as a resin component. Improve resistance to etchant. In addition, the printing property can be improved by containing 20 to 100 parts by mass of the SiO ₂ particles (B) per 100 parts by mass of the novolak resin (A). Further, by the solvent (C), particularly a solvent (C1) having a boiling point of 190 ° C or higher, drying of the composition for etching the mask (ink) during printing can be suppressed, and reprintability (printing stability) can be improved or Ink spit.

In addition, the composition for etching the mask contains interfacial activity In the case of printing the composition for an etching mask on a substrate for a solar cell, the agent (D) can effectively suppress the width of the pattern to be printed with respect to the width of the printing pattern to be set, that is, it can suppress Printing bleed is produced.

(pattern formation method)

As shown in FIG. 1(A), the metal film, an oxide film such as SiO ₂ or a nitride film such as SiN is deposited on a metal substrate or a germanium substrate such as a germanium substrate or copper, nickel or aluminum. On the solar cell substrate 10, the above-described etching mask composition is used, and a printing method such as a screen printing method, an inkjet printing method, a roll coating printing method, a letterpress printing method, a gravure printing method, or a lithography method is used. To form a mask pattern 20. In addition, before the mask pattern 20 is formed, the substrate may be processed as needed. The pretreatment is a step of forming a liquid-repellent layer, and examples thereof include the procedures described in JP-A-2009-253145. Next, the mask pattern 20 is heated and the mask pattern 20 is baked. The heating conditions are appropriately set depending on the composition of the composition for etching the mask, the film thickness of the mask pattern 20, and the like, but are, for example, 200 ° C for 3 minutes.

Then, as shown in FIG. 1(B), an etching liquid such as a mixed acid of hydrofluoric acid and nitric acid is used to selectively remove the solar cell substrate exposed in the opening of the mask pattern 20, and the mask pattern 20 is etched. The solar cell substrate of the opening (exposed portion) is transferred by a mask pattern.

Next, as shown in FIG. 1(C), after the etching process, the mask pattern 20 is removed. The removal method can be exemplified: impregnation at room temperature A method of peeling off in an aqueous alkali solution, an organic solvent, a commercially available peeling liquid, or the like for about 5 minutes to 10 minutes. The aqueous alkali solution is an aqueous solution of sodium hydroxide or an aqueous solution of tetramethylammonium hydroxide (TMAH). The organic solvent is propylene glycol monomethyl ether acetate (PGMEA), dimethyl hydrazine (DMSO) or the like. As the commercially available peeling liquid, an organic solvent-based peeling liquid 105 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) or the like can be used. As a result, a pattern in which the convex portion corresponding to the mask pattern 20 is transferred onto the solar cell substrate 10 can be obtained. Moreover, the function of the convex part formed in the substrate for solar cells is an electrode, a diffusion layer, etc. are mentioned.

According to the above steps, the convex portion of the specific pattern can be formed on the substrate for a solar cell. Since the composition for an etching mask described above is excellent in acid resistance and pattern formation accuracy, it is possible to form a desired pattern on a substrate for a solar cell with high precision. In addition, since the pattern can be formed on the substrate for a solar cell by a printing method without a complicated step like the photolithography method, the manufacturing process of the solar cell can be simplified, and the manufacturing cost of the solar cell can be reduced.

[Examples]

The embodiments of the present invention are described below, but the examples are merely illustrative of the invention and are not intended to limit the invention.

(Examples 1-11 and Comparative Examples 1-12)

Table 1 shows the groups for etching masks of Examples 1-11 and Comparative Examples 1-12. The composition of the adult. The novolak resin 1 and the novolak resin 2 used in the compositions for etching masks of Examples 1 to 11 and Comparative Examples 1 to 12 each had a mass average molecular weight of 12,000 (m/p = 60/40) and a mass average molecular weight. 2100 (m/p = 36/64) novolak resin. Table 2 shows the details of the fillers used in Examples 1-11 and Comparative Examples 5-12. Further, Table 3 shows the details of the surfactants used in Examples 1, 2, 4-11 and Comparative Examples 3-12.

An ink composed of the compositions for etching masks of Examples 1 to 11 and Comparative Examples 1 to 12 was produced by a combination of the components shown in Table 1.

In Table 2, the specific gravity of the filler 2 and the filler 3 is different. Since the filler 3 has a large specific gravity, it is easy to handle.

(Printability evaluation of screen printing)

Each of the produced inks was printed on a ruthenium substrate by a screen printing method to form a pattern having a width of 100 μm wide, 150 μm, and 200 μm wide. The pattern formed was dried on a hot plate at 200 ° C for 3 minutes. The line width of the obtained pattern was measured to confirm the printability. The results regarding printability are classified according to the following manner. Will be for printability The results obtained are shown in Table 4.

◎ (good): all patterns of printing bleeding are below 20μm

○ (may): 2 patterns of printing bleeding below 20μm

× (bad): 1 or 0 patterns for printing bleeding below 20μm

In addition, the printing bleeding is calculated by the following formula.

Printing bleeding = complete line width - wide print design

(shake assessment)

The viscosity curve of each ink was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., RE550 type viscometer), and the viscosity index was calculated according to the following formula.

Viscosity at viscosity = 1 rpm / viscosity at 15 rpm

The obtained viscosity index was classified according to the following manner, and the shaking property was evaluated. The results obtained for the shake densification are shown in Table 4.

◎ (good): viscosity index of 3.0 or more

○ (may): viscosity index of 2.0 or higher and less than 3.0

× (bad): viscosity index is lower than 2.0

As shown in Table 4, each of the inks of Comparative Examples 1 to 12 was inferior in printability and shakeability. On the other hand, in each of the inks of Examples 1 to 14, it was confirmed that both the printability and the shakeability had characteristics of ○ or more. In particular, when Example 2 was compared with Example 3, it was confirmed that the printability was further improved by the addition of the surfactant. Comparing Example 1 with Example 6, it was confirmed that the smaller the particle diameter of the filler, the more the printability and the shakeability were improved. Comparing Example 1 with Example 7, it was confirmed that the printability and the shakeability were further improved because the filler was hydrophilic.

(Printing stability evaluation of screen printing)

With respect to each of the inks of Examples 1, 8-10, and 12-14 described above, 7 shot screen printing was continuously performed to confirm printing stability. For the results regarding printing stability, the number of shots that can be printed without printing blur is shown in Table 5. Further, in Examples 9 and 10, the boiling point of the solvent is the average boiling point determined from the boiling point and mixing ratio of the solvent of the two types.

According to Table 5, it was confirmed that the printing stability was good when a solvent having a boiling point (including an average boiling point) of 190 ° C or higher was contained. It was confirmed that the first to seventh shots of the first to seventh shots were free of printing blur, and in particular, the smoothness of the first to seventh hit print patterns of the first, eighth, and ninth embodiments. Also high.

(acid resistance evaluation)

Each of the inks of Examples 1 to 11 was printed on a ruthenium substrate by a screen printing method to form a pattern having a width of 100 μm and a width of 200 μm. The formed pattern was dried on a hot plate at 200 ° C for 3 minutes. In order to confirm the acid resistance of the formed pattern, immerse in a 5% aqueous solution of hydrofluoric acid (Condition 1) or A 10% aqueous solution of sulfuric acid (Condition 2) was observed by an optical microscope to observe the surface state of the pattern. As a result, it was confirmed that each of the inks of Example 1-11 had no change in the film state under Condition 1 and Condition 2, and no peeling or cracking of the pattern was produced.

Claims (5)

A composition for an etching mask of a non-photosensitive solar cell substrate, comprising: 100 parts by mass of a novolak resin (A), 20 to 100 parts by mass of SiO ₂ particles (B), and a solvent (C). The composition for an etching mask according to claim 1, wherein the solvent (C) contains a solvent (C1) having a boiling point of 190 ° C or higher. The etching mask composition according to claim 1, wherein the SiO ₂ particles (B) are hydrophilic. The composition for a mask according to claim 1, further comprising a lanthanide, acrylic or fluorine-based surfactant (D). A pattern forming method comprising: a step of forming a mask pattern on a substrate by a printing method using a composition for an etching mask of a substrate for a solar cell according to claim 1, and a mask pattern A step of baking, a step of etching the substrate, a step of transferring the mask pattern, and a step of removing the mask pattern.