JPS6210809A - Formation of transparent conducting film substrate surface - 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 The present invention relates to a method of forming a transparent conductive film containing indium oxide as a main component, and particularly relates to a method of forming a transparent conductive film containing indium oxide as a main component, which is particularly suitable for use in liquid crystal display elements, EL display elements, etc. The present invention relates to a method of forming a low-resistance transparent conductive film as a component by a sputtering method.

BACKGROUND OF THE INVENTION Reactive sputtering has conventionally been used as a method for forming a transparent conductive film whose main component is indium oxide to which about 20% by weight of tin oxide is added. This method of forming a transparent conductive film by reactive sputtering uses a metal target with an alloy of indium and tin as a cathode in an inert gas such as argon under reduced pressure containing several tens of percent oxygen gas, and an oxide containing tin oxide. In comparison with indium oxide (In202), which has a stoichiometric composition, by generating a discharge between the opposite anode supporting the substrate to which the indium film is to be deposited, After forming a film of indium oxide containing tin oxide on the surface of the substrate, it is then heated in air at 300"C to 500"C.
A conductive film with high light transmittance and low resistance was formed by heat treatment at ℃.

Problems to be Solved by the Invention However, when a relatively thick transparent conductive film of about 1,000 μm or more is formed by the above method, hemispherical indium particles with a diameter of several μm are formed in the conductive film during heat treatment in air. The disadvantage was that the metal particles agglomerated.

If such a transparent conductive film is used in a liquid crystal display element or an EL display element, the opaque metal grains may become an eyesore, or dielectric breakdown may occur in the metal grains, impairing the functionality of those elements. was there.

Means for Solving the Problems The present invention has been made to improve the above-mentioned drawbacks, and is a method for forming a transparent conductive film containing indium oxide as a main component on the surface of a substrate by a sputtering method. An indium oxide-based coating consisting of alternating transparent, relatively thin layers and relatively thick, poorly oxidized, light-absorbing layers is deposited on the substrate surface. Heat treating the deposited film in air (
This is a method of forming a transparent conductive film on the surface of a substrate, which is characterized by making the substrate more transparent and lowering the resistance.

In the present invention, the transparent relatively thin layer that is sufficiently oxidized can be formed by a sputtering method using a target containing indium oxide as a main component, and the relatively thick layer that is insufficiently oxidized and absorbs light. is preferably formed by a sputtering method using a target containing metallic indium as a main component. In the present invention, the transparent relatively thin layer that is sufficiently oxidized preferably has a thickness of 30 to 20 OA. ,
The relatively thick layer with insufficient oxidation and light absorption is 2oo
Preferably, the thickness is between X and 3ooA.

Function The present invention involves depositing a film on a substrate surface, which consists of alternating transparent relatively thin layers that are sufficiently oxidized and relatively thick layers that are insufficiently oxidized and absorbing light. Since it is heat-treated, the sufficiently oxidized layer acts as a barrier to prevent the movement of metallic indium, and the heat treatment makes it difficult for opaque metal particles of indium to aggregate in the film.

The thickness of the transparent, relatively thin layer that has been sufficiently oxidized is 30A.
If it is less than 200K, the effect as a barrier for preventing the movement of metal indium will be insufficient, and if it exceeds 200k, the resistance will not be reduced even after heat treatment.

On the other hand, if the thickness of a relatively thick layer with insufficient oxidation is less than 200 mm, it will be necessary to increase the number of layers, and the resistance will not be low due to heat treatment, and if the thickness is more than 000 mm, agglomeration of metallic indium will tend to occur within the layer. There is.

Hereinafter, embodiments of the present invention shown in the drawings will be described in detail.

/ is a vacuum chamber, and inside the vacuum chamber / there is an electric insulator /4'
A conveyor 12 is provided for moving the magnetron cathodes 2 and 3, which are insulated from the walls of the vacuum chamber and the holder for the substrate 10 on which the film is to be applied, at a predetermined speed above the magnetron cathodes 2 and 3. It is being The vacuum tank 1 can be depressurized by a vacuum pump (not shown) through an exhaust port 13 provided with a barrier pull valve/3. Further, a target is provided on the surface of each of the cathodes 2 and 3.

Gas supply pipes 9 having valves 4 and 7 are provided near each target sensor 4' and j, and the cathodes 2 and 3 are connected to a grounded vacuum tank l. It can be connected to power supplies /l and /7 via switches 7g and /9.

Example / A target plate 41 on the cathode 2 in the vacuum chamber / is an alloy plate of 90 wt % indium and 10 wt % tin, and a glass plate IO with a size / OcmX' / 0 ctn is placed in the substrate holder //. was attached, and the inside of the vacuum chamber was evacuated to 10 Pa using a vacuum pump (not shown). Next, open the valve B and introduce a mixed gas consisting of argon gas of gS volume % and oxygen gas of /S volume % from the gas supply pipe into the vacuum chamber / at 11005 CC while adjusting the barrier pull valve /3. By doing so, the pressure inside the vacuum chamber is maintained at O,llPa, the power supply is set to ttoov, the switch is turned on, and after pre-sputtering is performed for about 70 minutes, the conveyor 72 is started and the glass is sputtered. The plate 10 was moved above the target over a range of 100 to 900 Tn, m7 minutes to form a predetermined thickness of an insufficiently oxidized indium oxide layer mixed with tin oxide, and the switch/g was turned off.

Then, close the valve O, fully open the barrier pull valve 3, and after evacuating the inside of the vacuum chamber to 10"'3 Pa again, open the valve 6 and fill the gas supply pipe with 9 to 75% by volume of argon gas and 23% by volume. Mixed gas with oxygen gas of 1100
5 CCj was introduced into the vacuum chamber/3, the barrier pull valve/3 was adjusted, the pressure inside the vacuum chamber/ was maintained at 0, +pa, the switch/za was turned on, and a negative voltage of tioov was applied to the cathode 2 for 70 minutes. After press battering, the conveyor/,! The glass plate 10 on which the indium oxide layer mixed with tin oxide, which is insufficiently oxidized, is attached is moved in a range of 100 to 900 mm for 1 minute above Targetera+1, and the tin oxide layer, which is sufficiently oxidized, is mixed. form a layer of indium oxide, then turn off the switch/g and valve 6.
did.

Then, the barrier pull valve 3 was fully opened, and the inside of the vacuum chamber was evacuated to about 10-4 Pa. By repeating this operation a predetermined number of times, insufficiently oxidized layers and sufficiently oxidized layers are alternately formed on the glass plate 10'', and then the glass plate with the coating attached is placed in an air atmosphere for about 30 minutes. "Heat-treated at c.

The properties of the coated glass plate thus obtained are shown in Table 1.

Example 2 Using the same sputtering apparatus as described above, a 92% by weight indium and 92% by weight tin alloy plate was placed on the target layer (4') on the cathode 2 in the vacuum chamber. A mixed metal oxide sintered body of indium oxide of 5% by weight and tin oxide of 5% by weight is attached, and the substrate 10 is further attached.
10 glass plates with size 10C1rlX/(l1cm)
After installing, the inside of the vacuum chamber l is pumped using a vacuum pump (not shown).
It was evacuated to o-3Pa. Next, open the valve 6 and add S volume % argon gas and tS volume % through the gas supply pipe.
A mixed gas consisting of a single element gas is introduced into the vacuum chamber/inside using tooscCM, the barrier pull valve 13 is adjusted to maintain the inside of the vacuum chamber at O. After applying a voltage and performing press sputtering for 70 minutes, the conveyor 72 is started and the glass plate IO is moved above the target layer (4Z) in a range of 100 to 900 mm for 1 minute to ensure that the predetermined thickness is not sufficiently oxidized. An indium oxide layer mixed with tin oxide was formed, and switch II was turned off.

Then, close the valve 6, fully open the barrier pull valve 13, and evacuate the inside of the vacuum chamber l again to /0-3Pa.
Open the valve 7 and supply a mixed gas of 75% by volume argon gas and 25% by volume oxygen gas from the gas supply pipe 9. / 00
Introduced into the vacuum chamber with SoCM and barrier pull valve 13
, maintain the pressure inside the vacuum chamber at 0.1 Ipa, turn on the switch 9, apply a negative voltage of 1 I00 to the cathode 3, perform press sputtering for about 10 minutes, and then turn the conveyor 72 on. A glass plate 10 with a poorly oxidized tin oxide mixed indium oxide layer deposited thereon.
was moved above the target S at a rate of 100 to 900 rntn/min to form a sufficiently oxidized indium oxide layer mixed with tin oxide, and then switch/9 and valve 7 were turned off. By repeating this operation a predetermined number of times, insufficiently oxidized layers and sufficiently oxidized layers were alternately formed on the glass plate 10, and then heat-treated at tioo°C for about 30 minutes in an air atmosphere.

The properties of the coated glass plate thus obtained are shown in Table 2.

EFFECTS OF THE INVENTION The present invention deposits a coating on a substrate surface in which a transparent relatively thin layer that is sufficiently oxidized and a relatively thick layer that is insufficiently oxidized and absorbs light is alternately applied to the surface of a substrate. Since the heat treatment is performed in the atmosphere, the sufficiently oxidized layer acts as a barrier to prevent the movement of metallic indium, and the heat treatment makes it difficult for opaque metal particles of indium to aggregate in the film.

Furthermore, as is clear from the examples, the thickness of the transparent relatively thin layer that is sufficiently oxidized is set to 30X to 200X, and the thickness of the relatively thick layer that is insufficiently oxidized and absorbs light is set to 2X.
By setting it to 0OA to 300A, agglomeration of opaque metal particles can be extremely reduced, and at the same time, a transparent conductive film with low resistance can be obtained.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram (side sectional view) for implementing the present invention.
It is. l: vacuum chamber, 2.3 = magnetron cathode.

Claims (3)

[Claims] (1) In a method of forming a transparent conductive film containing indium oxide as a main component on a substrate surface by sputtering method,
A film based on indium oxide, which consists of alternating transparent relatively thin layers that are sufficiently oxidized and relatively thick layers that are insufficiently oxidized and absorbs light, is deposited on the substrate surface, and then 1. A method for forming a transparent conductive film on a substrate surface, the method comprising making the film transparent and reducing resistance by heat-treating the film adhered to the surface of the substrate in air. (2) The relatively thin transparent layer that is sufficiently oxidized is formed by a sputtering method using a target containing indium oxide as a main component, and the relatively thick layer that is insufficiently oxidized and absorbs light is formed using metal. A method for forming a transparent conductive film on a substrate surface according to claim 1, wherein the transparent conductive film is formed by a sputtering method using a target containing indium as a main component. (3) The thickness of the relatively thin transparent layer that is sufficiently oxidized is 30 Å to 200 Å, and the thickness of the relatively thick layer that is insufficiently oxidized and absorbs light is 200 Å to 300 Å.
A method for forming a transparent conductive film on a substrate surface according to claim 1 or 2, wherein the transparent conductive film is formed on a substrate surface.