JP3279435B2 - Paste for thin film pattern formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-soluble paste used for a lift-off method.

[0002]

2. Description of the Related Art As a method of forming a pattern on a thin film, a pattern-like shield mainly composed of inorganic fine particles is formed (masked) on a substrate, and then a thin film is formed by an appropriate means. 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.

JP-A-49-113573 discloses powders of magnesium oxide, aluminum oxide, etc.
JP-B-61-43806 proposes to use calcium carbonate alone or a mixture thereof with graphite as a shielding material.

[0004] These oxides and charcoal salt, particularly a thermal CVD
When a thin film is formed by the method, it is slightly exposed to a strong oxidizing atmosphere and reacts slightly with the glass of the base on which the thin film is formed. It cannot be used for applications requiring a clean appearance. Further, a so-called spike phenomenon in which the edge of the thin film such as the transparent conductive film left after the removal of the shield is lifted easily occurs.

[0005] Japanese Patent Application Laid-Open No. 2-75536 proposes a device using a small mesophase carbon sphere as a shield. This method has an advantage that spike is reduced, particularly when forming a thin film by a thermal CVD method, carbon is evaporated by exposure to strong oxidizing atmosphere, that is Ri cloudy slightly substrate glass surface occurs It is clear.

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 the thin film is formed by the VD method, the source gas may not be completely shut off in some cases, and a small amount of the source gas may be observed under the shield. Further, when the wraparound amount increases, shielding itself for rather image sticking to the substrate, the thickness of the lift-off can be thin films were in in 500n m until.

On the other hand, the present applicant has filed Japanese Patent Application No.
The thin film removal method using a water-soluble inorganic salt coating proposed in No. 6512 has an excellent feature that no spike is observed. It has also been proposed to pattern a thin film by screen printing in combination with sodium alginate or the like. However, it was found that when this ink was used for the screen printing method, it was difficult to perform fine patterning.

[0008]

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

[0009]

According to the present invention, a water-soluble inorganic salt is used in an amount of 3 to 15% by weight, and a thickener comprising a water-soluble polymer is used in an amount of 0.1 to 0.1%.
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 alcoholic organic solvent.
It is a paste for forming a thin film pattern, comprising 50% by weight and 50 to 95% by weight of water.

[0010] The paste of the present invention is printed with high precision by a screen printing method on the surface of the substrate other than where the thin film is to be formed. Thereafter, a dense water-soluble inorganic salt film composed of the water-soluble inorganic salt and the filler is formed by drying and baking, and then a thin film is formed on the surface of the substrate by an appropriate method. Thereafter, the substrate with the 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.

As the water-soluble inorganic salt in the present invention, in addition to generally desirable properties such as high solubility in water, easy water-solubility and inexpensiveness, a thin, uniform and desired pattern on a substrate can be obtained. What can be covered densely without being scattered is desirable.

[0012] Such materials, strong covalent, is preferable to form a network structure, for example, phosphates, borates, silicates, sulfates, inorganic salt including sulfur, and their And the like. In particular, phosphates and borates are preferable since 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 is 3 to 3 in the paste.
It is 15% by weight. If it exceeds 15% by weight, a uniform and dense film cannot be formed after drying and firing.

Examples of the thickener comprising a water-soluble polymer include water-soluble polymers which are water-soluble and whose viscosity can be adjusted appropriately, for example, polysaccharides such as hydroxyethylcellulose, hydroxypropylcellulose and carboxymethylcellulose, sodium alginate and ammonium alginate. Organic acid salts, polyvinyl alcohol, polyethylene glycol,
Polyacrylamide, sodium polyacrylate and the like can be used. Particularly good results are obtained with sodium alginate and ammonium alginate.

The content of the thickener comprising a water-soluble polymer is 0.5 to 6% by weight in the paste, preferably 1.5.
４4% by weight.

In addition to the thickener composed of a water-soluble polymer, the paste must have an appropriate thixotropy in order to achieve high-definition patterning. For this purpose, a paste is included in the paste. As the filler, an inorganic filler and an organic filler can be used.

For example, when a thin film is formed at about 500 ° C. by a thermal CVD method, CeO ₂ , TiO ₂ , ZrO
₂ , inorganic fillers such as Nb ₂ O ₅ and carbon are preferable because they hardly stick to the substrate. When a thin film is formed at a low temperature, an organic filler such as polyvinyl chloride, polymethyl methacrylate, and polystyrene can be used.

The average particle size of the filler needs to be 0.1 to 2 μm, and preferably 0.1 to 1.5 μm. If it exceeds 2 μm, a dense film cannot be formed after the heat treatment.

The content of the filler is 0.1 to 0.1% in the paste.
The content is 10% by weight, preferably 0.4 to 7% by weight. If it exceeds 10% by weight, the film does not have a dense structure after the heat treatment and the shielding property is reduced, or after the thin film is lifted off, spikes remain 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 95% by weight.

When the solvent is water alone, the number of continuous prints is limited because solids adhere to the screen printing plate when screen printing is performed. In order to improve this point, it is necessary to add an alcoholic organic solvent to the paste.

[0022] As the alcohol-based organic solvents, ethanol, 2-propanol, ethylene glycol, propylene grayed recall, glycerin and the like. The content of the alcohol-based organic solvent in the paste is 1 to 20% by weight, preferably 5 to 10% by weight.

The paste of the present invention may further contain a filler dispersant or a defoamer for paste printing. Preferred examples include surfactants such as condensed sodium naphthalene sulfonate and ammonium polycarboxylate.

The substrate water-soluble inorganic salt is applied is not particularly limited, glass, plastics, ceramics, single crystal, metal, or the like to that the various coating these surfaces thereof.

The method for forming a thin film to be patterned is not particularly limited, and examples thereof include a vapor deposition method, a sputtering method, a spray method, a dipping method, a CVD method, and a casting method.

[0026]

According to the present invention, the paste applied on the substrate, unlike the conventional paste, after drying and firing, becomes a dense film containing a filler and having a thickness of about 1 to 2 [mu] m. Therefore, there is no gas flow when forming a thin film. Also,
Since the coating is a water-soluble inorganic salt, it is easily peeled off by washing the substrate with water, and it is possible to lift off a thin film of 1 μm or more, which has been difficult in the past. Also, no spike phenomenon occurs.

[0027]

EXAMPLES Example 1 6.4% by weight of sodium tripolyphosphate, 3.0% by weight of ammonium alginate, 0.85% by weight of cerium oxide having an average particle size of 0.6 μm, 4.25% by weight of ethanol, and 85 of water A paste consisting of 0.1% by weight and 0.4% by weight of ammonium polycarboxylate was printed on a glass substrate in a desired pattern by screen printing, dried at 120 ° C. for 10 minutes, and further baked at 450 ° C. for 20 minutes. A dense water-soluble coating without cracks was formed.

The glass substrate was heated to 500 ° C., and a SiH ₄ and O ₂ gas was blown onto the substrate surface to form a SiO ₂ film (about 100 nm thick). Subsequently, the glass substrate was heated to 530 ° C. Gaseous SnCl ₄ and H ₂ O were sprayed on the surface SiO ₂ film to form a SnO ₂ film (about 150 nm thick). When this substrate was brush-cleaned under running water, the SiO ₂ film formed on the water-soluble film, S
The nO ₂ film flowed down together with the water-soluble coating, 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 in the portion where the water-soluble film was present, and the glass was colorless and transparent. No spikes were 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, water 8
A paste composed of 5.5% by weight and 0.43% by weight of ammonium polycarboxylate was printed on a glass substrate by screen printing, dried at 120 ° C. for 10 minutes, and further heated at 500 ° C.
For 10 minutes, a dense water-soluble coating without cracks was formed.

The glass substrate was heated to 500 ° C., and SiH ₄ and O ₂ gas were sprayed on the substrate surface to form an SiO ₂ film (about 100 nm in thickness). Then, the glass substrate was heated to 530 ° C. Gaseous SnCl ₄ and H ₂ O were sprayed onto the surface SiO ₂ film to form a SnO ₂ film (about 1 μm thick). When this substrate was brush-cleaned under running water, the SiO ₂ film formed on the water-soluble film, SnO 2
_{The two} films 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 in the portion where the water-soluble film was present, and the glass was colorless and transparent. No spikes were observed.

Comparative Example 1 A paste consisting of 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 was screen-printed with a predetermined pattern. An attempt was made to print on a glass substrate. However, unlike Example 1, the printed film had portions where a part of the pattern was cut off, such as chips and blurring.
When this substrate was dried at 120 ° C. for 10 minutes and further baked at 500 ° C. for 10 minutes, a crack was found in a part of the water-soluble coating, but a dense film was formed in the other part of the water-soluble coating. Was.

On this glass substrate, S
iO ₂ film, after forming a SnO ₂ film was brush cleaning with running water, SiO ₂ from cracking portion of the water-soluble film
It was found that the film and the SnO ₂ film wrapped around the glass substrate. On the other hand, the SiO ₂ film and the SnO ₂ film were not observed on the glass surface where the uniform water-soluble film was formed.

Comparative Example 2 6.6% by weight of sodium tripolyphosphate, 4.9% by weight of ammonium alginate, 1.6% by weight of cerium oxide having an average particle size of 3 μm, 4.1% by weight of 2-propanol, water 8
A paste consisting of 2.4% by weight and 0.4% by weight of ammonium polycarboxylate was printed on a glass substrate in a predetermined pattern by screen printing, dried at 120 ° C. for 10 minutes, and baked at 500 ° C. for 10 minutes. The water-soluble coating around some cerium oxide particles had cracks.

On this glass substrate, S
iO ₂ film, after forming a SnO ₂ film was brush cleaning with running water, SiO ₂ from cracking portion of the water-soluble film
It was found that the film and the SnO ₂ film wrapped around the glass substrate. Also, CeO ₂ particles remained at the edge of the water-soluble coating, and spikes were formed.

Comparative Example 3 A paste comprising 15.3% by weight of sodium tripolyphosphate, 7.6% by weight of ammonium alginate, 0.8% by weight of cerium oxide having an average particle diameter of 0.6 μm, and 76.3% by weight of water was prepared. After printing on a glass substrate with a predetermined pattern by screen printing, drying at 120 ° C. for 10 minutes,
When calcined at 00 ° C. for 10 minutes, no dense water-soluble coating was formed.

On this glass substrate, S
iO ₂ film, after forming a SnO ₂ film was brush cleaning with running water, SiO ₂ from cracking portion of the water-soluble film
It was found that the film and the SnO ₂ film wrapped around the glass substrate.

[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 free of cracks and chips can be obtained by drying and firing. Since this film is easily soluble in water, the film after the formation of the thin film can be easily peeled off by washing with water. Since the film has excellent peelability, it can be patterned even with a thin film of about 1 μm. The coating prevents the diffraction of dense for gases, surface cloudy Riganaku substrate after the separation, further, does not occur even spiking.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-211768 (JP, A) JP-A-61-106680 (JP, A) JP-A-59-149958 (JP, A) JP-A-55-149958 105331 (JP, A) JP-A-7-908 (JP, A) JP-A-62-256881 (JP, A) JP-A-1-265591 (JP, A) JP-A-2-64172 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 1/00-201/00 B05D 7/24 G03F 1/06 H05K 3/02-3/08

Claims (3)

(57) [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 size of 0.1 to 2 μm in an amount of 0.1 to 1%. 10% by weight, 1-20% by weight of an alcoholic organic solvent, and 50-
A paste for forming a thin film pattern, comprising 95% by weight. 2. The paste for forming a thin film pattern 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.