JPH07331180A - Paste for forming thin film pattern - Google Patents

Abstract

PURPOSE:To obtain a paste which can form a thin film which can be released from the support by washing with water, is excellent in releasability, capable of patterning and proof against contamination with gas and, when released, leaves the support without surface cloudiness and spiking by mixing a water-soluble inorganic salt with a thickener comprising a water-soluble polymer, a filler having a specified mean particle diameter, an alcoholic organic solvent and water. CONSTITUTION:This paste is prepared by mixing 3-15wt.% water-soluble inorganic salt (e.g. sodium tripolyphosphate) with 0.5-6wt.% thickener comprising a water-soluble polymer (e.g. sodium alginate), 0.1-10wt.% filler having a mean particle diameter of 0.1-2mum (e.g. CeO2 as an inorganic filler or polyvinyl chloride as an organic filler), 1-20wt.% alcoholic organic solvent (e.g. ethanol) and 50-95wt.% water. Unlike a conventional paste, this paste forms a dense filled film having a thickness of about 1-2mum when applied to a support, dried and fired.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a water-soluble paste used in a lift-off method.

[0002]

2. Description of the Related Art As a method for forming a pattern on a thin film, after forming (masking) a pattern-shaped shield containing inorganic fine particles as a main component on a substrate, a thin film is formed by an appropriate means, and then the shield is formed. The lift-off method of removing the upper thin film together with the shield by physical or chemical means is known as an industrially useful method.

In Japanese Patent Laid-Open No. 49-113573, powders of magnesium oxide, aluminum oxide, etc. are also disclosed.
Japanese Examined Patent Publication No. 61-43806 proposes to use calcium carbonate alone or a mixture of calcium carbonate and graphite as a shield.

These oxides and carbides are especially useful for thermal CVD.
When a thin film is formed by the method, it is exposed to a strong oxidizing atmosphere and reacts slightly with the glass of the substrate on which the thin film is formed, resulting in fogging on the surface of the substrate obtained by removing the shield after forming the thin film. However, it cannot be used for applications that require a clean appearance. Furthermore, the so-called spike phenomenon in which the edge of the thin film such as the transparent conductive film remaining after removing the shield is lifted easily occurs.

Japanese Unexamined Patent Publication (Kokai) No. 2-75536 proposes a device that uses mesophase carbon microspheres as a shield. This method has the advantage of reducing spikes, but it is clear that carbon is vaporized by exposure to a strong oxidizing atmosphere, especially when forming a thin film by the thermal CVD method, and a slight clouding occurs on the substrate glass surface. It has become.

Further, since these conventional shields mainly consist of an inorganic compound and a filler, they do not have a dense film structure. Therefore, on these shields, for example, heat C
When a thin film is formed by the VD method, the raw material gas may not be completely blocked, and a slight wraparound of the raw material gas is observed under the shield. Further, if the amount of this wraparound increases, the shield itself will be burned onto the substrate, so the thickness of the thin film that can be lifted off was about 500 nm.

On the other hand, the present applicant filed Japanese Patent Application No. 5-16
The thin film removal method using a water-soluble inorganic salt coating proposed in Japanese Patent No. 6512 has an excellent feature that spikes are not observed. In addition, it is also proposed to pattern a thin film by screen printing in combination with sodium alginate or the like. However, it was found that fine patterning is difficult to achieve when this ink is used in the screen printing method.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paste for forming a thin film pattern, which is applicable to the screen printing method and in which spikes are not observed.

[0009]

According to the present invention, a water-soluble inorganic salt is contained in an amount of 3 to 15% by weight, and a thickener comprising a water-soluble polymer is added.
5 to 6% by weight, 0.1 to 10% by weight of filler having an average particle size of 0.1 to 2 μm, and 1 to 20% of alcohol organic solvent
%, And 50 to 95% by weight of water, which is a thin film pattern forming paste.

The paste of the present invention is printed with high accuracy by a screen printing method on the surface of the substrate in a portion which is not a place for forming a thin film. Then, by drying and baking, a dense water-soluble inorganic salt film composed of a water-soluble inorganic salt and a filler is formed, and then a thin film is formed on the surface of the substrate by an appropriate method. Then, the substrate with a thin film is washed with water to remove only the water-soluble inorganic salt film and the thin film on the upper surface of the film, thereby forming a high-definition thin film pattern.

The water-soluble inorganic salt in the present invention has generally desirable properties such as high solubility in water, high water-solubility, low cost, etc., as well as a thin and uniform pattern on a substrate with a desired pattern. It is desirable that it can be closely covered without being scattered.

As such a substance, those having a strong covalent bond and forming a network structure are preferable. For example, phosphates, borates, silicates, sulfates, inorganic salts containing sulfur, and these salts. A double salt of a salt etc. are mentioned. Particularly, phosphates and borates are preferable because good results can be obtained. More specifically, sodium tripolyphosphate, sodium hexametaphosphate, sodium tetraborate, potassium tetraborate and the like can be mentioned.

The content of the water-soluble inorganic salt in the paste is 3 to
It is set to 15% by weight. If it exceeds 15% by weight, a uniform and dense coating cannot be obtained after drying and firing.

Examples of the thickener composed of a water-soluble polymer include water-soluble polymers capable of optimizing viscosity, such as polysaccharides such as hydroxyethyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose, sodium alginate and ammonium alginate. Organic acid salt, polyvinyl alcohol, polyethylene glycol,
Polyacrylamide, sodium polyacrylate, etc. can be used. Particularly good results are obtained with sodium alginate and ammonium alginate.

The content of the thickener made of a water-soluble polymer is 0.5 to 6% by weight in the paste, preferably 1.5.
~ 4% by weight.

In addition to the thickener made of a water-soluble polymer, it is necessary to impart appropriate thixotropy to the paste in order to achieve fine patterning. For this reason, a paste is included in the paste. An inorganic filler or an organic filler can be used as this filler.

For example, when a thin film is formed at about 500 ° C. by the thermal CVD method, CeO ₂ , TiO ₂ , ZrO is used.
Inorganic fillers such as ₂ , Nb ₂ O ₃ and carbon are preferable because they hardly stick to the substrate. When forming the thin film at a low temperature, an organic filler such as polyvinyl chloride, polymethylmethacrylate, or polystyrene can be used.

The average particle size of the filler must be 0.1 to 2 μm, preferably 0.1 to 1.5 μm. If it exceeds 2 μm, a dense coating cannot be obtained after heat treatment.

The content of the filler is 0.1 to 1 in the paste.
The content is 10% by weight, preferably 0.4 to 7% by weight. If it exceeds 10% by weight, the coating does not have a dense structure after heat treatment and the shielding property is lowered, or after the film is lifted off, it remains as a spike on the edge.

The content of water used in the present invention is 50 to 95% by weight in the paste, preferably 75 to 95% by weight.
It is set to 95% by weight.

When the solvent is only water, the solid content adheres to the screen printing plate when screen printing, so that the number of continuously printed sheets is limited. In order to improve that point, it is necessary to add an alcoholic organic solvent to the paste.

Examples of the alcohol-based organic solvent include ethanol, 2-propanol, ethylene glycol, propylene glycol and glycerin. The content of the alcoholic organic solvent in the paste is 1 to 20% by weight, preferably 5 to 10% by weight.

In addition to the filler of the present invention, a dispersant for the filler and a defoaming agent for printing the paste can be added. Suitable examples include surfactants such as condensed sodium naphthalene sulfonate and ammonium polycarboxylate.

The substrate to which the water-soluble inorganic salt is applied is not particularly limited, and examples thereof include glass, plastics, ceramics, single crystals, metals, and those having various coatings on their surfaces.

The method of forming the thin film to be patterned is not particularly limited, and examples thereof include vapor deposition method, sputtering method, spray method, dip method, CVD method, casting method and the like.

[0026]

In the present invention, unlike the conventional paste, the paste applied on the substrate becomes a dense film having a thickness of about 1 to 2 μm containing the filler after drying and firing. Therefore, there is no gas wraparound when forming the thin film. Also,
Since the coating film is a water-soluble inorganic salt, it can be easily peeled off by washing the substrate with water, and lift-off of a thin film having a thickness of 1 μm or more, which has been difficult in the past, is also possible. Also, the spike phenomenon does not occur.

[0027]

【Example】

Example 1 6.4% by weight of sodium tripolyphosphate,
Ammonium alginate 3.0% by weight, average particle size 0.6
μm cerium oxide 0.85% by weight, ethanol 4.2
After printing a paste consisting of 5% by weight, 85.1% by weight of water and 0.4% by weight of ammonium polycarboxylate on a glass substrate with a desired pattern by screen printing, 12
When dried at 0 ° C. for 10 minutes and further baked at 450 ° C. for 20 minutes, a dense coating film without cracks was formed.

This glass substrate is heated to 500 ° C., SiH ₄ and O ₂ gas are blown onto the substrate surface to form a SiO ₂ film (film thickness of about 100 nm), and then the glass substrate is heated to 530 ° C. Gaseous SnCl ₄ and H ₂ O were sprayed onto the SiO ₂ film on the surface to form a SnO ₂ film (film thickness of about 150 nm). When this substrate is brush washed under running water, the SiO ₂ film, S and S formed on the water-soluble film
The nO ₂ film flowed down together with the water-soluble film, and a patterned SnO ₂ conductive thin film with a SiO ₂ underlayer was formed on the glass substrate. There was no SiO ₂ film or SnO ₂ film on the glass where the water-soluble coating was present, and it was colorless and transparent. No spike was observed.

Example 2 4.3% by weight of sodium tripolyphosphate, 2.1% by weight of sodium alginate, 3.4% by weight of titanium oxide having an average particle size of 1.2 μm, 4.3% by weight of 2-propanol and water. After printing a paste consisting of 85.5% by weight and ammonium polycarboxylate 0.43% by weight on a glass substrate by screen printing, the paste was applied at 120 ° C. for 1 hour.
After drying for 0 minutes and baking at 500 ° C for 10 minutes,
A dense film without cracks was formed.

This glass substrate was heated to 500 ° C., SiH ₄ and O ₂ gas were blown onto the substrate surface to form a SiO ₂ film (film thickness of about 100 nm), and then the glass substrate was heated to 530 ° C. Gaseous SnCl ₄ and H ₂ O were sprayed on the SiO ₂ film on the surface to form a SnO ₂ film (film thickness: about 1 μm). When this substrate was brush-washed under running water, the SiO ₂ film, SnO ₂ formed on the water-soluble film
_{The two} films flowed down together with the water-soluble film, and a patterned SnO ₂ conductive thin film with a SiO ₂ underlayer could be formed on the glass substrate. There was no SiO ₂ film or SnO ₂ film on the glass where the water-soluble coating was present, and it was colorless and transparent. No spike was observed.

Comparative Example 1 4.5% by weight of sodium tripolyphosphate, 3.6% by weight of sodium alginate, 91% by weight of water and 0.9% by weight of ammonium polycarboxylate.
An attempt was made to screen-print the paste consisting of the above into a glass substrate with a predetermined pattern by a screen printing. However, unlike Example 1, the film after printing had some portions such as chipping and scraping where the pattern was cut off. This substrate at 10 ° C for 10
After minute drying and further baking at 500 ° C. for 10 minutes, a crack was found in a part of the water-soluble film, but a dense film was formed in the other part of the film.

S was added to this glass substrate in the same manner as in Example 1.
After forming the iO ₂ film and the SnO ₂ film, brush cleaning under running water revealed that the SiO ₂ film and S
It was found that the nO ₂ film wraps around the glass substrate side. On the other hand, no wraparound of the SiO ₂ film and SnO ₂ was observed on the glass surface where the uniform water-soluble coating was formed.

Comparative Example 2 Sodium tripolyphosphate 6.6% by weight, ammonium alginate 4.9% by weight,
A paste composed of 1.6% by weight of cerium oxide having an average particle diameter of 3 μm, 4.1% by weight of 2-propanol, 82.4% by weight of water and 0.4% by weight of ammonium polycarboxylate was screen-printed into a glass having a predetermined pattern. After printing on the substrate, dry at 120 ° C for 10 minutes and then at 500 ° C for 1 minute.
When it was baked for 0 minutes, cracks were found in the coating around some cerium oxide particles.

S was added to this glass substrate in the same manner as in Example 1.
After forming the iO ₂ film and the SnO ₂ film, brush cleaning under running water revealed that the SiO ₂ film and S
It was found that nO ₂ wraps around the glass substrate side. Further, CeO ₂ particles remained on the edge portion of the film, and spikes were formed.

[Comparative Example 3] Sodium tripolyphosphate 1
5.3% by weight, ammonium alginate 7.6% by weight,
0.8% by weight of cerium oxide having an average particle size of 0.6 μm, water 7
After printing a paste consisting of 6.3% by weight on a glass substrate with a predetermined pattern by screen printing, 120 ° C
After drying for 10 minutes and baking at 500 ° C. for 10 minutes, a dense film was not formed.

S was added to this glass substrate in the same manner as in Example 1.
After forming the iO ₂ film and the SnO ₂ film, brush cleaning under running water revealed that the SiO ₂ film and S
It was found that nO ₂ wraps around the glass substrate side.

[0037]

According to the present invention, a water-soluble inorganic salt can be screen-printed on a substrate with high precision, and a dense water-soluble coating film free from cracks and cracks can be obtained by drying and baking it. Since this coating is easily water-soluble, the coating can be easily peeled off by washing with water after the thin film is formed. Since the coating has excellent releasability, even a thin film of about 1 μm can be patterned. Further, since the film is dense, it prevents gas from flowing around, the surface of the substrate after peeling is not clouded, and the spike phenomenon does not occur.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Taneda 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Central Research Laboratory, Asahi Glass Co., Ltd.

Claims (3)

[Claims] 1. A water-soluble inorganic salt in an amount of 3 to 15% by weight, a water-soluble polymer thickener in an amount of 0.5 to 6% by weight, and a filler having an average particle diameter of 0.1 to 2 μm in an amount of 0.1 to 1. 10% by weight, 1 to 20% by weight of alcohol organic solvent, and 50 to 50% of water
A paste for forming a thin film pattern, which contains 95% by weight. 2. The thin film pattern forming paste according to claim 1, wherein the water-soluble inorganic salt is a phosphate and / or a borate. 3. The paste for forming a thin film pattern according to claim 1, wherein the filler is an inorganic filler.