JPS5929304A - Method of forming transparent conductive 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 Technical Field of the Invention The present invention focuses on a method of forming a transparent conductive material, particularly a low-resistance transparent material mainly composed of indium oxide (N203).
This invention relates to a method for forming a tl14γ1 film with good reproducibility by sputtering.

(b) Prior art and problems Transparent conductive films used in optical devices such as display springs, for example, In2O to which about 1 to 10% of indium oxide (N203) or tin oxide (5nu2) is added
Reactive sputtering is generally used as a method for forming a transparent conductive film mainly composed of No. 3. .

Conventionally, as a method for forming a transparent conductive film by the above-mentioned reactive sputtering, an inert gas such as argon (Ar) and oxygen (02) gas of several lθ% are mixed in a mixed gas atmosphere, for example. A metal target layer, which is an alloy of In and Sn in a predetermined ratio, and which will serve as a cathode, and a nail plate support on the anode side, which supports a substrate to which a transparent conductive film is to be applied, are arranged facing each other at a predetermined interval, and first, a shutter is placed. With the substrate covered by 6iJ.

After performing press sputtering by applying a predetermined discharge voltage between the shutter and the metal target, main sputtering is performed by applying a required discharge voltage between the two electrodes without heating the substrate using the shutter and the metal target. By doing this, a transparent conductive film mainly composed of nBO3 is formed on the surface of the substrate. & Shading formation.

By the way, the transparent conductive T film formed by the above-mentioned sputtering method has a smoother and smoother film surface than that obtained by sputtering by heating the substrate to a high temperature, or by the IC beam evaporation method. Although it has the advantage of having a uniform film thickness, the range of sputtering conditions (sputtering power, gas composition ratio, gas pressure, etc.) to obtain a transparent conductive layer with low resistance and good transmittance is extremely narrow, making it difficult to reproducibly It has the disadvantage that it is not easy to form well. That is,
This type of transparent conductivity is disappointing; in the case of an over-oxidized metal oxide film, the transmittance improves but the resistance becomes high; in the case of an under-oxidized metal oxide film, on the other hand, the transmittance is low and the resistance is low. Therefore, in order to form a transparent conductive film made of an optimal metal oxide film that can satisfy both of the above characteristics, the range of sputtering conditions is naturally narrowly limited, making reproducibility difficult.

(C) @Ming's Purpose The present invention solves the conventional drawbacks described in 1 above by controlling the oxidation state during the formation of a transparent conductive film to easily reproduce a transparent conductive film with low resistance and good transmittance. It is intended for good use.

(4) Structure and object of the invention According to the present invention, in a method for forming a transparent conductive film made of a metal oxide on the surface of a substrate by sputtering, the sputtering power during the formation of the transparent conductive film is periodically switched. , characterized in that an underoxidized metal oxide layer and an overoxidized metal oxide layer are alternately and successively deposited, and then the conductive film is heat-treated in a vacuum at a temperature of 300C or higher to homogenize it. Transparent 4
This is achieved by providing a method for forming an electrical film.

(e) Embodiment of the Invention An embodiment of the method for forming a transparent conductive film according to the present invention will be described in detail below with reference to the drawings.

In the present invention, as shown in the relationship diagram between sputtering power (discharge voltage, etc.) and film quality (film resistance and transmittance) when a transparent conductive film mainly made of InQ03 is formed by sputtering as shown in FIG. From the transmittance curve and the resistance curve E, it is clear that the optimum sputtering power range A (gas composition ratio and gas pressure are constant) in which the film can be formed with the lowest resistance and good transmittance is not %. narrow, (
Since this makes reproducibility difficult, we set the Nubatsuta ring power conditions during the formation of the transparent conductive film as follows: a metal oxide layer that is underoxidized compared to the optimal metal oxide layer, and a metal oxide layer that is also overoxidized. A metal oxide film, which will become a transparent conductive film, is formed using sputtering powers faB and C, which can be formed with relatively good reproducibility.

Equipment 1: First, we prepare a metal target that will serve as the negative glue, which is an alloy of Sn and Sn in a predetermined ratio, and a substrate support that will serve as the anode, which will hold the substrate that will protect the transparent 4-ray image. The insides of the bell jar type vacuum valley devices, which are arranged facing each other at a predetermined interval, are evacuated to a vacuum.

Subsequently, a mixed gas consisting of regulated Ar and 02 is introduced into the nuclear power container and adjusted to a predetermined gas pressure. Thereafter, sputtering was performed between the metal target and the substrate support by periodically alternating or changing the sputtering powers C and B explained in FIG. 1, as shown in FIG. 2. The substrate 1 is placed on a substrate support (not shown) (in this case, the substrate 1 is
(without heating), an underoxidized metal oxide M2 mainly composed of indium oxide and an overoxidized metal oxide layer 3 are alternately and successively deposited.

Thereafter, the substrate l is heat-treated in a vacuum at a temperature of, for example, 400°C for about one hour, so that the oxidation state of each stacked metal oxide layer is uniformly unified on average due to the diffusion reaction of oxygen between each layer. As shown in FIG. 8, a transparent conductive film 4 in an optimum oxidation state with low resistance and good transmittance can be easily obtained. In this way, the transparent conductive film in the optimal oxidation state is formed with a nil K'Q sputtering power of 1n.
It can be easily formed by controlling lc and B and the layer thickness ratio of each metal oxide layer stacked accordingly.
It becomes possible to obtain the transparent conductive film with good reproducibility, and the manufacturing yield is significantly improved.

In the following examples, we have explained an example in which sputtering is performed without heating the substrate to which a conductive film is to be applied, but the same effect can be obtained when applying sputtering to a method in which the substrate is heated to a high temperature. is obtained. Further, as the applied discharge voltage waveform, a regular direct current is used, but it goes without saying that the waveform can be used without distinction between direct current and alternating current.

ffl Effects of the Invention As is clear from the above explanation, the transparent conductive IJ according to the present invention
: According to the method of forming the L film, it is possible to easily obtain a high-quality transparent conductor with good transmittance and high reproducibility by reducing the resistance through well-controllable puttering conditions and heat treatment in vacuum. , it has excellent effects such as significantly improving the manufacturing yield of the conductive film.

[Brief explanation of the drawing]

Figure 1 shows the transparent conductor [+5. Explanatory diagram showing the relationship between sputtering power, film resistance, and transmittance when a film is formed by sputtering, 2nd
3 and 3 are cross-sectional views illustrating one embodiment of the method for forming a transparent 24-layer 1@ according to the present invention. In FIG. 1m, D is a transmittance curve, ratio is a resistance curve, ■ is a substrate, 2 is an underoxidized metal oxide layer, 8 is an overoxidized metal oxide layer, and 4 is a transparent conductive film. 21

Claims (1)

[Claims] In a method of forming a transparent conductive film made of a metal oxide on the surface of a substrate by sputtering, the sputtering power eX1 is periodically switched during the formation of the transparent conductive film to form an underoxidized metal oxide layer and an overoxidized metal oxide layer. 1. A method for forming a transparent conductive film, comprising depositing the conductive films alternately and continuously, and heat-treating the conductive film in a vacuum at a temperature north of 300° C. to homogenize it.