JPS63103060A - Production of substrate with transparent electrode - Google Patents

Abstract

PURPOSE:To produce a substrate with transparent electrodes by sticking a translucent film to the surface of a transparent glass plate with a sintered In2O3 body contg. SnO2 as a target, then removing the unnecessary parts of the translucent film in the atm., and heat treating the substrate. CONSTITUTION:The transparent glass substrate 13 and the target 3 consisting of the sintered In2O3 body contg. 3-15wt% SnO2 are disposed in a vacuum vessel 1 of a magnetron sputtering device S. Gaseous Ar contg. 0.2-3.0vol% O2 is supplied from a supply pipe 5 into the vacuum vessel 1 in such a manner that 5X10<-4>-5X10<-3>Torr atmospheric pressure is maintained therein. The glass substrate 13 is heated to <=100 deg.C by a heater 12 and a negative voltage is impressed to the target 3 to sputter the target by the ionized gaseous Ar, by which the translucent film is formed on the substrate 13. The substrate is taken out into the atm. and is etched with a dilute acidic soln. by using a masking material to remove the unnecessary parts of the opaque film, by which the glass substrate with the translucent film of a desired pattern is obtd. The substrate is heated in an N2 atmosphere to clarify the translucent film. The glass substrate with the transparent electrodes is thus produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a substrate with a transparent electrode, and particularly to a method of manufacturing a substrate with a transparent electrode suitable as a transparent electrode of a liquid crystal display device.

[Conventional technology]

In recent years, solid-state devices such as liquid crystal, electroluminescence, and plasma have been put into practical use as solid-state display elements. Among them, liquid crystal display elements are widely used as display devices, and the demand for higher display performance, ie, high-definition display and large-area display, is increasing. In order to obtain a high-definition, large-area liquid crystal display element, the conductive film forming the electrodes must be microfabricated and a transparent substrate with transparent electrodes having low resistance is required.

As such a substrate with a transparent electrode, a glass or plastic substrate to which an indium oxide film doped with tin oxide (hereinafter referred to as an ITO film) or a tin oxide film is attached is used. For large items, ITO is used because of its excellent electrical resistance and workability of electrode patterns.
A membrane is used as a transparent electrode.

There are two methods for producing a substrate with an ITO film electrode attached to it: one is to process a transparent fluoride ITO film into an electrode pattern using a concentrated acid solution, and the other is to process a semitransparent, amorphous half oxide ITO film using acid. There is a method of changing the electrode pattern from translucent to transparent by heat treatment after processing the electrode pattern.

The former method involves depositing an indium oxide film pellet containing tin oxide on a transparent substrate heated to 300°C or higher using a vacuum evaporation method to create a transparent fluoride IT film.
In this method, an O conductive film is directly formed. The TO transparent conductive film obtained by this method has continuous crystallinity, so
% hydrochloric acid aqueous solution at a temperature of ≠0° C. or higher during patterning. Etching unnecessary portions of the transparent conductive film using high temperature, high concentration acid weakens the adhesion between the masking material and the transparent conductive film, making it difficult to process minute electrodes with good dimensional accuracy. In addition, since high temperature and highly concentrated acid are used, a large amount of equipment is required due to equipment maintenance and environmental problems, resulting in an increase in costs.

In the latter method, an alloy of indium and tin is sputtered onto a transparent substrate without heating in a mixed gas of argon and oxygen under reduced pressure to form a semitransparent half-oxide IT.
Once an O conductive film is formed, it is made transparent and the electrical resistance is stabilized by heat treatment.
This is to form an O conductive film. I obtained by this method
For the same reason as the former method, it is not easy to perform fine heavy electrical processing on the TO transparent conductive film with good dimensional accuracy.

In addition, with this method, electrode patterning can be performed using an extremely dilute aqueous solution by performing electrode patterning treatment before heat treatment of the half oxide translucent ITO conductive film.
Microfabrication of electrodes becomes easier.

However, by reactive sputtering targeting an alloy of indium and tin, half-oxide I
When forming a TO film, it has been difficult to improve the degree of oxidation with good reproducibility. Furthermore, since it is necessary to increase the film thickness of low-resistance transparent mW, in that case, the method described above has the drawback that it is difficult to diffuse oxygen into the interior of the film by heat treatment, making it impossible to obtain an electrode with high transmittance. Ta.

[Problem that the invention seeks to solve]

The present invention has been made in order to eliminate the drawbacks of the conventional method for manufacturing a substrate with transparent electrodes as described above. The present invention relates to a method for manufacturing a substrate with transparent electrodes, which allows fine processing of electrodes using an aqueous acid solution.

[Means to solve the problem]

That is, the present invention uses a target made of a sintered body of indium oxide containing 3% to 75% by weight of tin oxide!
;X/ 0-4'l'orr~jX/0-3To
A translucent film was deposited on a transparent substrate kept below 700°C by sputtering in an argon gas containing 0.2 volume Stt% to 3.0 volume Stt% of oxygen, and then exposed to the atmosphere. After removing the removed transparent substrate by etching unnecessary parts of the translucent film on the transparent substrate with an acidic solution using a masking material, the transparent substrate with the translucent film attached in the desired pattern is heat-treated to form a transparent electrode. This is a method of manufacturing a substrate.

In the present invention, the sputtering target used is a sintered target made of a mixture of tin oxide and indium oxide, which allows the degree of oxidation of the semitransparent film to be easily adjusted and the properties of the semitransparent film to be controlled with good reproducibility. The sintering target has a tin oxide content of 3% to 75% by weight, preferably 3% to 10% by weight. If the content of tin oxide is less than 3% by weight or more than lj weight, a translucent film attached to a low-temperature substrate cannot have a low resistance value even after heat treatment.

Further, when forming a semitransparent half oxide film, the temperature of the transparent substrate is set to 0.000'C or less. This temperature is 1
When the temperature exceeds 00°C, crystallization of the membrane progresses, and dilute) acid,
For example, it becomes difficult to remove the film by etching with a 5% hydrochloric acid aqueous solution at 33°C.

Furthermore, the content of oxygen gas contained in the sputtering gas is 0.2% by volume to 3.0% by volume. When the amount of oxygen gas is less than 0.2%, the degree of opacity due to oxygen deficiency becomes too large, and complete transparency cannot be achieved at a heat treatment temperature of 250°C to 350°C. On the other hand, if the amount of oxygen gas exceeds 3%, the oxidation of the film progresses too much, and although the film can be made transparent in the above temperature range, it is not possible to lower the resistance of the film after heat treatment. That is, by sputtering an indium oxide target containing tin oxide in the range described above within the sputtering gas composition and substrate temperature range described above, a semitransparent film mainly composed of amorphous material is formed at COSO°C to 3SO°C. By heat treatment at ℃, a film with 6 brightness and low resistance can be obtained.

In the present invention, the heat treatment is preferably carried out in a nitrogen atmosphere, and when the substrate with transparent electrodes according to the present invention is used as a transparent electrode of a liquid crystal display device, after applying a liquid crystal aligning agent to the electrode, the aligning agent is The heat treatment can be performed at 300°C to 330°C simultaneously with the heat curing process.

[For production]

The present invention involves sputtering a target of a sintered body of indium oxide containing tin oxide, depositing a semi-transparent film on a transparent substrate kept at 100°C or less, and removing unnecessary parts of the semi-transparent film deposited on the transparent substrate. Since it is removed with an acidic solution and then heat-treated, it is possible to stably form an amorphous semitransparent film on a transparent substrate. Unnecessary parts can be removed in a short time, and then heat treatment can make the membrane transparent and stabilize the electrical resistance.

Example In the vacuum chamber of the magnetron sputtering apparatus S,
The glass substrate /3 was set to face the target 3 using a holder /l so that the distance between the glass substrate /3 and the target 3 was 90 -. The target 3 is mounted on the backing plate of a magnetron cathodeco, which is mounted to the vacuum chamber 7 via an insulating vacuum seal 9.
A permanent magnet 7 is provided below the backing plate t, and in order to cool the backing plate t, a sputtering power source is connected to the magnetron cathode and a negative voltage is applied between the magnetron cathode and the vacuum chamber. pipe 1
Cooling water is circulated through 0a and 10b.

On the other hand, a heater 12 is provided above the glass substrate 13 to adjust the temperature of the glass substrate 13.

The size of the glass substrate 13 is 200mm x 2sOx 8/y.
A glass made of soda-lime glass of 500 ml was used and was washed with a neutral detergent. Target 3 is tin oxide! A sintered body containing 9/j% of indium oxide by weight was used.

The inside of the sputtering apparatus S was evacuated from the exhaust port 6 to 5×10″″5 Torr, and then 2.0×/0-3 Torr.
While introducing a mixed gas of argon and oxygen from the gas introduction pipe 5 using a mass flow controller (not shown), the internal pressure was stabilized and 5 amperes was supplied to the target 3 from the sputtering Ta source 11 so that The translucent film attached to glass substrate/3 was controlled by sputtering time. In addition, the temperature of the glass substrate /3 is adjusted to 9 by the heater 12.
I played 11 verses. Yuzu's sputtering time, glass humidity introduction oxygen gas? Samples /~/2 were obtained by changing. Then 250°C 1300”C, J!; 0°C and ≠o in air
A heat treatment was performed at a temperature of o'c for 20 minutes, and the resistance and transmittance of the transparent conductive film were measured.

The results are shown in Table 1.

For samples 1 to 9, the film thickness is /390A to /3;2OA
Sample 10-/2 is an example of a thick film, and sample 10-/2 is an example of a thin film. Sample 11B is a case where the glass is not heated, Samples 2 to 5 are examples according to the present invention, and Sample 11B is a comparative example. In the as-devo state, the transmittance of sample/-j is low and it is a half oxide film. This indicates that In2O3 is sputtered with decomposition and becomes a lower oxide. These films are
It has been clearly shown that heat treatment at C to 3SO° C. lowers the resistance and makes the material transparent. Sample / is a sample sputtered with argon gas only, and in this heat treatment temperature range,
Since the film is made of metal lynch, it is difficult to make it transparent. On the other hand, Sample B was sputtered in an oxidizing atmosphere containing 3.5% of 02 gas, and it can be seen that the resistance does not become low at the curing temperature of the liquid crystal alignment film.

It is important to note that the substrate temperature affects the etching properties of the film.
shown in the table. The resistance after heat treatment decreases when the substrate temperature reaches 100°C, and
Etching can be removed in minutes. When the substrate humidity exceeds 100° C., the time required to remove the film by etching increases rapidly.

In sample 9, where the substrate temperature was 130°C, the crystallization of the film progressed and the etching speed (
It was not possible to ensure that the film could be removed in about 5 minutes. The property that the film can be etched and removed in a short time with a 5% or less hydrochloric acid aqueous solution at IIO°C is useful for forming thin IT electrodes with a width of 15 to 20 μm without impairing the adhesion between the photosensitive resist and the film. It was possible to remove unnecessary portions of the film without causing the so-called shoulder of the cross section of the electrode to become rounded.

Although direct current sputtering has been described in the embodiments of the present invention, it goes without saying that thermal high frequency sputtering can also be used.

〔Effect of the invention〕

Table 2 ×: The film cannot be removed by etching As described above, the present invention has the characteristic that it can be easily etched when patterned because it is an amorphous semi-transparent film that is easy to process and is deficient in oxygen. With a 1% to 3% aqueous solution of hydrochloric acid, the film thickness can be increased in about 3 to 5 minutes! ; The thick film of OOA can be removed by etching without deteriorating the adhesion with the masking material and without causing any thinning of the pattern. As the acid-resistant masking material used in the manufacturing process according to the present invention, any of the screen printing method, intaglio printing method, and photolithography method can be used.

The electrode-processed semi-transparent film is heated to a temperature of 3, which is a typical temperature for hardening the alignment film, which is one of the manufacturing steps of a liquid crystal display cell.
It can become transparent and have low resistance at temperatures of 00°C to 330°C. Therefore, the present invention makes possible for the first time a manufacturing process in which the alignment film is cured and at the same time the film is made transparent and low in resistance.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of a magnetron sputtering apparatus used in the present invention. /') IC empty chamber, 2: Mag Atron cathode,
3: Target t: Sputtering power supply. j: gas introduction pipe, 6: exhaust port. 7: permanent magnet, lr: packing plate. ri: Insulated vacuum seam), / (7a, b: Water-cooled vibrator. //: Holder, /2; Heater 13 glass substrate

Claims (3)

[Claims] (1) A target made of a sintered body of indium oxide containing 3% by weight to 15% by weight of tin oxide was heated to 5×10^-^4 Torr to 5×10^-^3 Torr.
A semitransparent film was deposited on a transparent substrate kept at 100°C or less by sputtering in an argon gas containing 0.2% to 3.0% by volume of oxygen, and then taken out into the atmosphere. After removing unnecessary parts of the semi-transparent film on the transparent substrate by etching with a dilute acidic solution using a masking material, the transparent substrate with the semi-transparent film attached in the desired pattern is heat-treated to form a substrate with transparent electrodes. How to manufacture. (2) The method for manufacturing a transparent electrode-equipped substrate according to claim 1, wherein the heat treatment is performed in a nitrogen atmosphere. (3) The method according to claim 1 or 2, wherein after applying a liquid crystal aligning agent to the transparent substrate on which a semi-transparent film of the desired pattern is attached, the heat treatment is performed at the same time as the heat curing treatment of the aligning agent. A method of manufacturing a substrate with transparent electrodes.