JPS6068508A - Method of forming zinc oxide-tin oxide mixture transparent conductive thin film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming a transparent conductive film used in a photoelectric conversion device. In particular, the present invention relates to a method for forming a zinc oxide-tin oxide mixed transparent conductive thin film, which is extremely useful when forming a tapered transparent conductive film by laminating films having different dissolution rates in the same etching solution.

(Structure of conventional example and its problems) Transparent conductive films are used in various photoelectric conversion devices including electroluminescence (EL) display devices. Among these, in dot matrix type thin film EL elements,
A spot field is applied to the light-emitting layer and the insulating layer by a striped transparent conductive film and a reflective electrode that intersect with each other. Therefore, if the cross-sectional shape of the stripes of the transparent conductive film is close to rectangular, a high electric field will be applied to the edges, causing dielectric breakdown and causing serious problems such as disconnection of the striped electrodes and deterioration of image quality. . This becomes more noticeable as the thickness of the transparent conductive film increases.

If the cross-sectional shape has a gentle curve, the problem of dielectric breakdown can be solved. Conventionally, the method of processing the edge of a zigzag into a gentle chi/p shape is to use a photoresist with an arc-shaped cross section as a mask and to etch the tin oxide film (as described in "Vacuum" Vol. 24). 12
No. 653-659 (1981)), a method has been proposed in which, for example, two types of transparent conductive films having different dissolution rates in an etching solution are laminated, masked with a photoresist, and chemically etched at the same time. In the former sputter etching method, it is necessary to place the samples side by side on the cathode, making it impossible to etch all the elements at once, and to increase the etching rate. When the battering discharge power is increased, the photoresist is heated and hardened, making it impossible to remove it, resulting in extremely low productivity.On the other hand, the latter chemical etching method In order to make the edges of the turns gently tapered, a transparent conductive film is required whose dissolution rate in the etching solution is 10 times different. As a transparent conductive film, a film made of indium oxide (ITO) with all tin oxide added is widely used.As a transparent conductive film, the dissolution rate of this transparent conductive film is about 10 times higher than that of the etching solution. Zinc oxide
There is a mixed film of tin oxide, but in this system, the composition ratio of the two in Tarquet 9t varies greatly depending on the composition ratio: about 180 times when it is 1:1, and about 1.3 times when it is 3:7. It is important to accurately control the composition ratio.

When a powder mixture of zinc oxide and tin oxide is used as a target, the composition of the target surface changes from time to time due to the different sputtering speeds of zinc oxide and tin oxide during the snocutter, making it difficult to reproduce. It had the disadvantage of being bad. However, in terms of productivity, if this zinc oxide-tin oxide mixed film can be produced with good reproducibility, it is more advantageous than the former sputter etching method.

(Objective of the Invention) An object of the present invention is to provide a method for forming a zinc oxide-tin oxide mixed film that can improve the productivity of a transparent conductive film having a silicon oxide. The dissolution rate in the etching solution used when performing chemical etching is 200% that of indium oxide (ITO) added with tin oxide.
To provide a method for forming a zinc oxide-tin oxide transparent conductive thin film, which has the feature that the composition ratio of zinc oxide and tin oxide can be freely adjusted so that the dissolution rate can be controlled at a constant rate in the range of 5 times to 5 times. .

(Structure of the Invention) In order to achieve the above object, the present invention uses a composite target gold composed of zinc oxide porcelain and tin oxide porcelain, and uses a smearing method in a mixed gas of inert gas and oxygen. A thin film is completely formed on the substrate.

Alkon can be used as the unoccupied gas.

In particular, the present invention uses a composite target because the suction speeds of zinc oxide porcelain and tin oxide porcelain exhibit different partial pressure ratio dependencies when the partial pressure ratio of argon and oxygen is changed. This is based on the discovery that when used, the composition of the thin film formed on the substrate can be controlled by the partial pressure ratio of argon and oxygen. Therefore, when performing chemical etching, the dissolution rate in the etching solution can be freely controlled within a range of about 200 patties, and a wide pattern of the transparent conductive film can be chemically etched in a gentle taper shape.

(Description of an Example) An example of the method of the present invention will be described below. As film formation conditions, a case will be described in which the distance between the target and the substrate is about 7 cn1, and the gas pressure is in the range of 10-' Torr to 10-2 Torr. Figure 1 shows a composite target of zinc oxide and tin oxide porcelain according to the present invention;
The porcelain plates of zinc oxide porcelain 2 and tin oxide porcelain 2 were arranged in a strino shape so that the area ratio of zinc oxide to tin oxide was 1:J to form a composite target. The porosity of zinc oxide porcelain is approximately 35%, and the porosity of tin oxide porcelain is approximately 15%.
Met.

Using this composite target in argon gas at 5 x 10 Torr, a thin film was formed on a substrate at room temperature using a madanetron sputtering device, and the composition of the thin film was analyzed using an X-ray microanalyzer.
A composite film of nO-35nOz was formed.

Also, two argon and oxygen gases are used at the same gas pressure and temperature.
When a thin film is formed using a mixed gas with a partial pressure of became. - When looking at the force and etching speed, the 21no-3Sn02 film is less than 1 times smaller than the ITO film produced by electronic vino or vapor deposition, while the 3ZnO-25n02 film is much more than 200 times larger. This is what I found out. Therefore, when the partial pressure ratio of argon and oxygen gases was varied from 400:1 to 10:1 and the rate of dissolution in the etching solution was measured, the results shown in the table were obtained.

The etching rate ratio in the table is the ratio of the etching rate (4.5 nnv' minutes) of the ZnO-SnO2 film and the ITO film produced by electron beam evaporation.

It has been confirmed that even when the same composite target is used, the composition ratio of zinc oxide and tin oxide changes depending on the alcon and oxygen gas pressure ratio, and the etching rate can be controlled within a range of about 40 times. It was also confirmed that the ITO transparent conductive film was chemically etched in a gentle tapered shape even in a wide range of patterns. The results are shown in FIG.

In this way, a zinc oxide-tin oxide transparent conductive thin film 3 of 500× was deposited at a total pressure ratio of 400:1 between alkon and oxygen gases.
When formed and etched on the ITO film 4 with a full film thickness of 500X, the angle 6 becomes a chi-shaped curve of about 11 degrees, and when the force partial pressure ratio is 10:1, the angle 6 becomes a chi-shaped curve of about 0.3 degrees.
Gusty? It was confirmed that a turn was formed. It was also confirmed that by paying sufficient attention to the control of the partial pressure ratio of the alconite and W wave elements according to the present invention, a zinc oxide-tin oxide transparent conductive film 75 (1T) having good H1 properties and a constant composition can be formed.

Furthermore, even if the substrate temperature is changed from room temperature to 200°C, the m composition changes by changing the partial pressure ratio of alkon and oxygen at the same room temperature, and by selecting the conditions of gas pressure and partial pressure ratio, appropriate etching can be achieved. A zinc oxide-tin oxide transparent conductive film with high-speed gold was obtained.

Similar results were obtained when the gas pressure ranged from 10''-''Torr to 10-2 Torr. In the embodiment of the fourth invention, a magnetron gutter ring device was used, but it is presumed that similar results can be obtained even if other strut ring devices Nt are used. Furthermore, since the composite substrate was used, the composition ratio on the surface of the nine particles did not change and was extremely reproducible.

(Effects of the Invention) As described above, according to the present invention, a zinc oxide-tin oxide mixed transparent conductive thin film having an appropriate etching rate can be formed on an ITO film, and the cross section of the transparent conductive film can be formed even in wide and flat turns. Chemical etching can be performed with good reproducibility so that the shape is completely tapered, and the productivity is increased. It should be noted that the zinc oxide-tin oxide mixed transparent conductive thin film according to the present invention can be used alone or as a transparent conductive film.

[Brief explanation of the drawing]

FIG. 1 shows a composite turret 8-sol 1 in an embodiment of the present invention.
FIG. 2 is a plan view of the IIF oxide button-tin oxide transparent conductive thin film of the present invention, which is formed on an ITO film and shown in full horizontal cross-section through etching. 1. Zinc oxide porcelain, 2. Tin oxide porcelain, 3. Zinc oxide-tin oxide transparent conductive thin film, 4. ITO film, 5. Glass substrate. Patent applicant: Matsushita Electric Industrial Co., Ltd. Agent: Hisashi Hoshino Figure 1 Figure 2

Claims (2)

[Claims] (1) Zinc oxide characterized in that a thin film is formed by sputtering in a mixed gas of inert gas and oxygen using a composite target composed of zinc oxide porcelain and tin oxide porcelain by the blowfish method. - Method for forming a tin oxide mixed transparent conductive thin film. (2) The composition ratio of zinc oxide and tin oxide in the thin film formed is 1
．． Formation of a zinc oxide-tin oxide mixed transparent conductive thin film according to claim (1), characterized in that the mixing ratio of the inert gas and oxygen is set within a range of 4 to 0.7. Method.