JPH01287278A - Formation of thin ito film - Google Patents

Abstract

PURPOSE:To form a thin ITO (indium tin oxide) film having superior transmittance and preventing easy exfoliation by forming a thin film of a mixed soln. contg. In methoxide, Sn methoxide, amine and methanol on a heat resistant substrate, drying the film and calcining the dried film in an oxidizing atmosphere. CONSTITUTION:A mixed soln. contg. an In compd. such as In methoxide, ethoxide or butoxide, an Sn compd. such as Sn methoxide, ethoxide or butoxide, amine such as monoethanolamine or diethanolamine and alcohol such as methanol or ethanol is prepd. A heat resistant substrate is dipped in the soln. to form a thin film of the soln. and this thin film is dried and calcined in an oxidizing atmosphere. By this method, a thin film is formed at a stroke while inhibiting the hydrolysis of the In and Sn compds. by the amine, so a thin ITO film having superior transmittance and preventing easy exfoliation can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application The present invention is suitable as an electrode for display elements such as liquid crystal display elements and electroluminescence display elements, and as an electrode for photosensitive elements such as photovoltaic cells and image pickup tubes. Suitable, furthermore,
ITO (Indium T
The present invention relates to a method for forming a thin film of i+) oxide on a substrate.

Prior Art There are various methods for forming an ITO thin film on a substrate by dissolving a small amount of 3n in In2O3.

For example, the 26th Ceramics Industry Basics Conference Lecture Abstracts, No. 15
9 (1988), an aqueous solution of InCl3 and 5nC1q was dropped into aqueous ammonia to form hydrated fine particles, which were centrifuged, washed with water, and dried to form a powder.
A method is described in which the paste is dispersed in distilled water and polyvinyl alcohol is added to form a paste, which is then applied onto a glass substrate, dried, and fired to obtain an ITO film. However, this method is not suitable for InCl3 or s
Since an aqueous solution of an inorganic salt such as nc l 4 is first powdered and then applied in the form of paste 1, the thin film may become cloudy and translucent, or the adhesion to the substrate may be weak and the thin film may There is a problem that it easily peels off.

Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned problems of the conventional method and to provide an IT(]ij To provide a method for forming a film.

Means for Solving the Problems In order to achieve the above object, the present invention includes a3 a step of preparing a mixed solution containing a compound selected from the following groups A, 8, 0 and D, respectively; Group A: In, methoxide, 1-cyto, propoxide, butoxide, methoxide, 1-hexide or 1-xyel]hexite Group B: Methoxide, 1-cyto of Sn;・Xide, Butoxide, Butoxide, Me1~Xie1~Xide or
~Xyethoxyto group 0: monoethanolamine, jetanolamine, 1
~liethanolamine, 7) 2-propanolamine,
Di-2-propanolamine, acedelacetin, nethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol Group D: methanol, ethanol, propanol, butanol, methoxyethanol, polyoxyethanol on a heat-resistant substrate A method for forming an ITO thin film is provided, which includes the steps of: forming a thin film of the mixed solution; drying the thin film; and firing the dried thin film in an oxidizing atmosphere.

Hereinafter, this invention will be explained in more detail for each step.

Preparation process of mixed solution: In this invention, first, a mixed solution containing a compound selected from the following Δ, B, and C1D is prepared.

Group A: In, Me1-Gyside, Ethoxide, Propoxide, Butoxide, Me1-Hexy1-Gyside or Tech1-Hexy-1 Hexy1 Group 8; Sn, Me1-Gyside, ■1-oxide, Propoxide , butoxide, me1~xie1~oxide or
Hexie 1 to oxide = 5 = 0 group; monoethanolamine, jetanolamine, 1
~liethanolamine, mono-2-propanolamine,
di-2-butyl]panolamine, acetylacetone, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol Group D: methanol, ethanol, propanol, butanol, methoxyethanol, etc. The propoxide may be either 1-propoxide or 2-propoxide. In addition, Bu[]-gide may be any of 1-butoxide, 2-butoxide, isobutoxide, and t-butoxide. It may be either propanol or 2-propanol. Furthermore, butanol includes 1-butanol, 2-butanol,
It may be any of butanol, isobutanol, and 1X-butanol.

The compounds of the = 6-0 group suppress the precipitation of indium and tin as particulate hydroxides and oxides due to hydrolysis in each step up to firing. Also,
Group D compounds are those that act as solvents.

One type is selected and used from each group of Δ, B, C, and D.

Although it is possible to select and use two or more types, there is almost no significant difference in the properties of the resulting thin film, and there are many disadvantages such as complicating the process and increasing loss. It's much bigger.

Further, no matter which compound is selected from each group A and B, there is hardly any significant difference in properties between the obtained thin films.

That is, no significant difference in properties of the resulting thin film due to differences in alkoxy groups or alkoxyalkoxy groups was observed.

Similarly, no matter which compound is selected from Groups C and D, there is almost no significant difference in the properties of the resulting thin film.

Although the mixing ratio of the compounds of each group A, B, C, and D differs slightly depending on their type, the compound of the Δ group is a mole,
When the compound of group B is b mol, the compound of group 0 is C mol, and the compound of group D is d phosphorus 1 her, the formula is, 0.1≦fc/ (a + b)]≦0 0.01≦[ (a+b)/d ] ≦3 is preferably satisfied at the same time. [C/ (a + b)]
<0.1, it may not be possible to sufficiently suppress the hydrolysis of the compounds of each group A and B.
)]>10, the viscosity of the mixed solution may become too high to form a film.

Furthermore, [(a+b>/d]<0.01 is not practical because there is too much solvent. Also, [(a-+-b)/d
When l>3, compounds of each group A and B may remain dissolved.

In addition, the mixing ratio of the compounds of each group A and B is 0.05≦[
b/(a+b)]]≦2. Outside this range, the resulting thin film will have poor conductivity.

The mixing operation may be to simultaneously add and mix the compounds of each group A and B to a mixed solution of the compound of group 0 and the compound of group D, or the compound of group 0 and the compound of group D may be mixed together. It is also possible to separately prepare solutions by adding the compounds of each group A and B to a mixed solution of , and then take a predetermined amount from each solution and mix them.

Note that until the mixing operation is completed, it is preferable to avoid exposing the compounds of each group Δ and B to moisture as much as possible, and it is preferable to carry out the mixing in a glove box purged with dry nitrogen or the like.

However, further operations can be carried out in air.

Step of forming a thin film of the mixed solution: In the present invention, next, a thin film of the mixed solution is formed on the heat-resistant substrate. In other words, a film is formed.

The substrate may be of any type as long as it can withstand the firing temperature described below.
Metals such as nickel, copal, chromium, titanium, gold, silver, platinum, alloys containing at least one of these metals as a main component, glass, carbon, gooey element, silver, alumina, magnesia, Zirconia, ditania, boron nitride,
Inorganic materials such as phosphorus nitride and boron carbide can be used. .

The shape may be fibrous, film, plate, bulk, or the like. It is preferable that the surface of these substrates [, Jl, i15<] is polished to make it smooth, or washed to remove stains due to oil or the like.

The thin film can be formed by coating with a brush, roller, etc., by spray coating, or by a dip coating method in which the substrate is immersed in a mixed solution and then pulled up. Among these, the dip coding method is preferred because it is simple and allows the film thickness to be changed relatively freely.

Drying step: In this invention, next, the thin film formed on the substrate is dried, and the compound of group D is evaporated to form a gelled thin film consisting of compounds of groups Δ, B, and C. It may be carried out at room temperature or at a constant temperature of about 50-100°C.

Firing step: In the present invention, the dried thin film is then fired together with the substrate in an oxidizing atmosphere to decompose and blow off the organic components and to avoid oxidation of the compounds A and B each of 4 yen. Thus, a 1TO thin film is obtained. This firing is performed, for example, as follows.

That is, the thin film is placed together with the substrate in a heating furnace, heated to a firing temperature in an oxidizing atmosphere, maintained at that temperature for a certain period of time, and then cooled to room temperature. The firing atmosphere is air or 20-
The concentration of oxygen is 100%. Also, firing is from 400~
It is carried out at 900'C for about 5 to 1000 minutes. Firing temperature is 40
If the temperature is below 0°C, it may not be possible to completely remove organic components. Furthermore, if the temperature exceeds 900°C, the thin film may partially dissolve or evaporate.

Examples Example 1 In a glove box flowing with dry nitrogen, 0.018 mol of In butoxide and 0000 mol of 3N butoxide were added.
Take 2 mol h'' and add 0.0 mol of jetanolamine to it.
Add 2 mol, further add 100 ml of ethanol, stir for 30 minutes using a Stark shaker, and obtain 1 q of a clear mixed solution.

On the other hand, a quartz glass plate with a thickness of 1 mm was ultrasonically cleaned for 3 minutes each using 1~lichlorethylene, 1~acetic acid, ethanol, and pure water, and then was sprayed with high-purity dry nitrogen. Dry.

Next, a quartz glass plate was immersed in the above mixed solution, and after 1 minute,
The mixture solution was pulled up vertically at a speed of 10 cm/min to form a thin film of the mixed solution on the quartz glass.

Next, the thin film was placed in a constant humidity bath at 50'C for 30 minutes to dry.

Next, the dried thin film was placed in an electric furnace together with the quartz glass plate and fired at 500'C for 30 minutes.

The ITO thin film thus obtained had a thickness of approximately 400 mm.
The resistance was 1.1 Ω/port. In addition, when observed with the naked eye, cloudiness and cracks were observed and the result was 4r. Furthermore, I tried rubbing it with my hands, but there was no peeling or denting.

Example 2 In a glove box flushed with dry nitrogen, 0.018 mol of in propoxide and 0.018 mol of 3 n propoxide were added.
．． Measure out 0.002 mole and add 0.00 mol of jetanolamine to it.
．． Added 02 mol of 1-propanol and further added 100 mol of 1-propanol.
ml was added and stirred for 30 minutes using -12= Stark to obtain a transparent mixed solution.

Hereinafter, an ITO thin film was obtained in the same manner as in Example 1.

The resulting ITOI film had a thickness of approximately 4.50 mm and a resistance of 1.3 Ω/mm. In addition, when observed with the naked eye,
No clouding or cracks were observed. Furthermore, I tried rubbing it with my hands, but the thin film did not peel off.

Example 3 In a glove box flowing with dry nitrogen, 0.018 mol of In butoxide and 0.00 mol of 3N butoxide were added.
Measure out 2 moles and add 0.02 mol of jetanolamine to it.
1 mole of 1-propanol was added, and 100 ml of 1-propanol was added, followed by stirring for 30 minutes using a Stark shaker to obtain a transparent mixed solution.

Thereafter, an ITO thin film was obtained in the same manner as in Example 1.

The obtained ITO thin film has a thickness of about 1/1. With 0 people, the resistance was 1.3 Ω/mouth. In addition, no clouding or cracks were observed when observed with the naked eye. Furthermore, I tried checking it with my hands, but the thin film did not peel off.

Effects of the Invention The method of the present invention forms a thin film on a heat-resistant substrate from a mixed solution all at once while suppressing the hydrolysis of the compounds of groups A and B with the compound of group 0, and then drying the film in an oxidizing atmosphere. Since baking is performed, as shown in the examples, an I layer with excellent translucency and not easily peeled off from the substrate is coated on the substrate.
It becomes possible to form a TO thin film.

Claims (1)

[Scope of Claims] (a) A step of preparing a mixed solution containing a compound selected from the following Groups A, B, C, and D, and Group A: In, methoxide, ethoxide, propoxide, Butoxide, methoxyethoxide or ethoxyethoxide Group B: Sn, methoxide, ethoxide, propoxide, butoxide, methoxyethoxide or ethoxyethoxide Group C: Monoethanolamine, diethanolamine, triethanolamine, mono-2-propanolamine, Di2-propanolamine, acetylacetone, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol Group D: methanol, ethanol, propanol, butanol, methoxyethanol, ethoxyethanol (b) Forming a thin film of the above mixed solution on a heat-resistant substrate (c) drying the thin film; and (d) firing the dried thin film in an oxidizing atmosphere.