JPS6129822A - Production of thin transparent iridium oxide film - Google Patents

Abstract

PURPOSE:To obtain a thin transparent Ir film having a large area with one stage by subjecting metallic Ir together with other metal or the transparent oxide thereof or the fluoride thereof to multi-element vapor deposition or multi- element sputtering under specific conditions. CONSTITUTION:The metallic Ir is subjected together with the other metal M or the oxide thereof or the fluoride thereof to the multi-element vapor deposition under the conditions of 1X10<-4>-1X10<-2>Torr O2 partial pressure and >=0.02 film forming speed ratio: Ir/M weight ratio or to multi-element sputtering under the conditions of 5X10<-2>-1X10<-1>Torr O2 partial pressure and >=0.02 film forming speed ratio: Ir/M weight ratio to form the thin transparent iridium oxide film on the substrate. Sn, In, Ta, Zn, Ti, Si, Mg, Ca, W, Mo or Sb is used for the metal. The oxide or fluoride of the metal M is colorless and transparent and does not make opaque the thin Ir film. The resulted thin Ir oxide film has the finely porous structure to absorb moisture from the atm. or the adjacent layers and has the state equal to hydroxide. The greater part of the Ir existing in the thin film is thus contributed to an EC characteristic. The durability is improved and the Ir is economized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for producing a transparent iridium oxide thin film.

(Background of the Invention) Electrochromic (GC) display devices (hereinafter referred to as ECD), which develop color by applying a voltage similar to that of a dry cell battery and fade to their original colorless and transparent state by applying a reverse voltage, have been developed in Japan. Active research is being carried out to put this into practical use as a means of displaying numbers and other things using the letter-shaped seven segments.

One of them is reduction color development B such as wo, , Moo□, etc.
There is an RCD using C substance.

In order for these EC substances to develop color, simultaneous injection of kameko (e-) and cation (X+) is required, and the reaction formula involved in color development and decolorization is believed to be as follows.

When decoloring: WOs +ne-+nX+ ↓↑ ↓↑ When developing color: XnWOa And as the cation (X+), I (10), which has a small ionic radius and is easy to move, is mainly used. These cations are always cations. It is not necessary that cations are generated when a voltage is applied and an electric field is formed, so especially in the case of H0, water is used as a cation source.Water changes from HO to H+- in an electric field. It decomposes according to 1-OH-.It seems that a very small amount of water is sufficient;
Water that is naturally taken up by the WO and N from the atmosphere often suffices.

However, even if the WO8 layer is simply sandwiched between a pair of electrodes and a voltage is applied to develop color, the color cannot be easily erased. This is because even if a reverse voltage is applied to erase the color, electrons (e'-) will flow in from the electrode side connected to the cathode, so if there is H+, WO, -)ne--1- nH
Ten→HnWO.

This is because the reaction takes place and the color develops.

Therefore, an ECD was proposed in which an insulating layer such as Sin, MgF, etc. was provided between the WO8 layer and one electrode (
#Koshō 52-46098). The insulating layer of this BCD is
Electrons cannot move, but OH- ions can move freely, and these OH- ions carry electricity, resulting in OH-+ 1/2H,0+ (1/4) 0. ↑＋e
It is thought that electrons are released to the receiving side according to the - reaction.

In other words, when developing color, (cathode side) WO, +ne--1-nH+-+ HnW
The reaction Oa (anode side) n (OH-) → n/2 H, o + (n/4) 02↑+ne- is estimated, and at the time of decolorization, (anode side) HnWO, -+WO, +ne- + nH+
(Cathode side) It is estimated that the following reaction occurs: nH,0+ne--+n0H-10(n/2) Ht↑.

It is clear from these formulas that in reality
The ECD No. 46098 consumes water when it is driven, so if water is not quickly supplied from the atmosphere, it will not produce color. Also, as 02 gas and 11° gas are released as it is driven, it will cause delamination. There were drawbacks.

Therefore, an all-solid-state FtCD was proposed in which an ``electronic insulating layer that is a good ion conductor/oxidation color-forming gc layer'' was provided in the gap between the WO layers (Japanese Patent Application Laid-Open No. 56-4679).

This uses iridium hydroxide as the oxidative color-forming I3C layer, and when coloring WO3, Ir(OH)m +
n (OH-) (colorless and transparent) ↓ Ir (OR) L-pH20+ qH,O+ r (
e″″) reacts with the colored species, and when WO3 is decolored, Ir (OH) t ” pHρ+qHP+r(e″′
)↓ Ir (OH) m + n (It is thought to react with OI(-''). Therefore, water is regenerated, so no water is consumed, and no HQ gas or 0□ gas is generated. .

In this case, iridium hydroxide can be regarded as a hydrate of an oxide, just like general hydroxides. Particularly in thin films, water easily penetrates from the atmosphere, so it may be referred to as an oxide rather than a hydroxide. On the other hand, even if you obtain an iridium oxide thin film, it is difficult to distinguish it from hydroxide in a strict sense in the atmosphere.

By the way, in the past, transparent iridium hydroxide or iridium oxide thin films were produced by forming a thin film of metallic iridium by vacuum evaporation, sputtering, or other vacuum thin film forming techniques.
The thin film was produced by anodic oxidation in an acid or alkaline aqueous solution.

Therefore, since two steps are required, the manufacturing cost is high and the manufacturing time is long.

In addition, an electrode is required on the base for anodic oxidation, and if a transparent electrode (essential for a transmission type ECU) is selected as the electrode, there is currently no transparent electrode material with low electrical resistance. When attempting to anodize a large-area metallic iridium thin film, the central metallic iridium is not anodized and remains opaque or transparent black, resulting in a large-area transparent iridium hydroxide or oxide thin film. This has never been possible before.

(Object of the Invention) An object of the present invention is to provide a method that requires only one step and can produce a large-area transparent iridium oxide thin film.

(Summary of the Invention) As a result of intensive research, the present inventors have discovered that metal iridium and "other metals whose oxides or fluorides are transparent, or their oxides or fluorides" can be used together with specific oxygen partial pressures and film formation. We have discovered a method for producing a transparent iridium oxide thin film by performing multi-component evaporation or multi-component sputtering under conditions of speed ratios, and have accomplished the present invention.

Therefore, the present invention provides metallic iridium (Ir), together with another metal (M) or its oxide or fluoride, (a) O, partial pressure: lXl0-' to lXl0-2T
orr.

Film formation rate ratio: Ir7M Multi-component vapor deposition under conditions of weight ratio = 0.02 or more, or (b) o, partial pressure: 5X10-8 to lXl0-'
Torr.

A method is provided for manufacturing a transparent iridium oxide thin film on a substrate by performing multi-source sputtering under conditions of a film-forming rate ratio: I r Af overlap ratio=0.02 or more.

To carry out the present invention, a substrate on which a counter electrode is generally formed is prepared. However, if the oxide of the other metal (goods) is conductive and the resulting iridium oxide thin film itself is conductive, it is not necessary to form a counter electrode. In addition, as a counter electrode, 8nO, In,
Transparent conductive materials such as O,, ITO (In2O mixed with about 5% 8 n Ot), ZnO, At,
Metal materials such as Ag, A, and U are used. Further, other films may be formed in addition to the counter electrode.

Using such a substrate, metal Ir and other metals M or their oxides or fluorides are subjected to multi-component vapor deposition or multi-component sputtering according to the present invention. Other metals M used together with metal Ir include, for example, Sn, In, and Ta.
, Zn, TI, Si, Mg, Ca, W, λ
(0 or 8b, etc.) These gold AMs do not use themselves as an evaporation source or target as described above,
The oxide or fluoride may be used as an evaporation source or target. In any case, these oxides or fluorides of metal M are colorless and transparent and do not make the iridium oxide thin film opaque.

As a vapor deposition method, a method is used in which Ir can be activated by applying high frequency waves or heat. In this sense, high frequency ion blating is also preferably used as a type of vapor deposition method.

As the sputtering method, high frequency or direct current sputtering is used.

In any case, place the substrate in a vacuum chamber and once reach the vacuum level: I X 10-' ~ 5 X 10-' Torr
After creating a vacuum to a certain degree, the partial pressure at the time of vapor deposition: 1xto-' ~
1×1O-2Torr or 0□ partial pressure during sputtering =
02 gas of 5 x 10-8 to I At the same time, vacuum evaporation or sputtering is performed.

In this case, if 02 partial pressure is I x 10-'To
rr or lower than 5 x 10-” Torr during sputtering, ■ Discharge is unstable ■ The film absorbs visible light due to insufficient oxidation, resulting in defects such as loss of transparency. On the contrary, vapor deposition Time I x 10-”'
I'orr or I X 10-'To during sputtering
If it is higher than rr, ■ it becomes difficult to grow a film with a uniform structure; ■ adhesion becomes poor.

There are drawbacks such as.

In addition, the film formation rate ratio is 0.0 in terms of I r /h4 heavy rat ratio.
If it is less than 2, the electrode reaction will not deviate smoothly, resulting in a decrease in EC properties (the amount of reaction charge will be too small). On the other hand, if it is too high, the transparency will be lost, so it is generally preferred that it be about 10 or less.

In this way, a transparent iridium oxide thin film is obtained, which has a microporous structure and easily absorbs moisture from the atmosphere or from adjacent layers, so that in a sense it can be called a hydroxide. It can be.

Although the coloring density of the iridium oxide thin film obtained according to the present invention decreases as the Ir content decreases,
It is effective in suppressing the generation of gas and H2 gas.

Although the thickness of the iridium oxide film is arbitrary, it is generally about 0.005 μm to 1 fin for use in ECD.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example 1) A glass substrate on which an ITO transparent conductive layer (CB) with a thickness of 0.15 μm was formed was prepared, and the following conditions were applied on the conductive layer (E): Evaporation source: binary system of metal an and metal Ir Ultimate vacuum:
5 X 10-'TorrO8 partial pressure: 3 X 10-
A transparent iridium oxide thin film (D) having a film thickness of about 120 OA was formed by high frequency ion blasting under a 'Torr substrate temperature: 20° C. and a film formation rate ratio: Ir/Sn weight ratio of −0.3.

Then, apply the following conditions: Evaporation source: T a * Oa + U Vacuum degree: 5 x 10-'Torr02 Partial pressure:
A transparent ion conductive layer (C) having a thickness of 500 l was formed by vacuum deposition under 4 x 10'' Torr substrate temperature: 150°C.

In addition, the following conditions: Evaporation source: WOa Ultimate vacuum: 5 x 10" Torr Partial pressure:
A transparent amorphous WO2 layer (B) with a thickness of 5000 Å was formed by vacuum deposition under 4×10-'Torr substrate temperature=150°C.

Finally, on the WO2 layer (B), the following conditions: Evaporation source: In
,0. Achieved vacuum degree of mixture of and SnO: 5 x 1
0 ”” Torr02 partial pressure: 3 X 10-' Torr
rSubstrate temperature: 150°C by high frequency ion blating to create a film thickness of 250°C.
A transparent display electrode (A) of 0 A was formed.

In this way, an FICD having a five-layer structure was obtained.

After sealing this ECD with epoxy resin, the electrode (A),
When a coloring voltage of 14 ports is applied through (E), 1
Color develops blue at 50m5ec, transmittance (Tc) when color develops
was 20% at a wavelength of 600 nm, and this coloring state was maintained even after the voltage application was stopped. Next, when a decoloring voltage of -1.4 volts was applied, the original colorless and transparent state was restored in 100 mlce, and the transmittance (Tb) at the time of decolorization was 85%.

(Example 2) The glass substrate used in Example 1 was prepared, and its conductive layer (E
) on top of the following conditions: Evaporation source: Binary system of MgF and metal Ir Ultimate vacuum:
5 X 10-@TartO1 partial pressure: 3 X 10-
A transparent iridium oxide thin film (D) with a film thickness of 1500 Å was formed by high frequency ion blasting under 'Torr substrate temperature: room temperature film formation rate ratio: IrA1g Shigemachi ratio=0.4.

Hereinafter, as in Example 1, transparent ion conductive layer (C), WO
, layer (B) and H*pole (A) are formed, 1
iicD was created.

After sealing with epoxy resin, a color development/discoloration test was performed, +1
．． 150m5ec at 4V, Tc=25%,
100m5ec at -1,4V, 'rb=s 5% (
λ-600 nm).

(Example 3) The glass substrate used in Example 1 was prepared, and its conductive layer (E
) on top of the following conditions: Target: Binary system of metal Ir and metal 8n Achieved vacuum degree:
I X 10-'TorrO1 partial pressure: 3 X 1
RF sputtering was performed at a weight ratio of 0'' Torr substrate temperature: room temperature film formation rate ratio: Ir/Sn of 1.0 to form a transparent iridium oxide thin film (D) with a film thickness of 20 OA.

Hereinafter, as in Example 1, transparent ion conductive layer (C), WO
A layer (8) and display electrode (A) were formed to create a BCD. After sealing with epoxy resin, a color development and fading test was performed and the result was +1
．． 100m5ec at 4V, Tc=15%, -1
, 50m5ec%Tb=85%(λ=600am
)Met.

(Comparative Example 1) The glass substrate (8) used in Example 1 was prepared, and the following conditions were applied on the conductive layer (l): Evaporation source: metal Ir Degree of vacuum: 5 X 10-'Torr lr partial pressure: 3 X 10-'Torr substrate temperature = 20
C. Anodizing was performed by applying an alternating current voltage (0.5 Hz) with a film thickness of scg using high-frequency ion blating at a film formation rate of a I X 10-' A/sec.
It was changed to a transparent iridium oxide thin film (D).

On the iridium oxide thin film (D), (C
) layer, (B) layer, and (A) J'i# were laminated to form an ECU and sealed. The obtained ECD was colored slightly brown even before the coloring voltage was applied, and it did not work in the atmosphere. Even when a 0.5 Hz AC voltage of ±1.5 volts was applied for 500 minutes, it did not become completely colorless and transparent.

After decoloring, we conducted a decoloring test and found that 200m5
Tc = 20% in ec, 'rb = in 150 m5ec
It was 75%.

(Effects of the Invention) As described above, according to the present invention, a transparent iridium oxide thin film with a large area can be obtained in one step because anodization is not required.

Furthermore, in the obtained iridium oxide thin film, most of the Ir atoms present are involved in BC properties, and the film has excellent durability. Another advantage is that rare and expensive Ir can be saved.

Claims (1)

[Claims] 1 Metal iridium (Ir) together with another metal (M) or its oxide or fluoride, (a) O_2 partial pressure: 1×10^-^4 to 1×10^-^
2Torr, film formation rate ratio: Ir/M, weight ratio = 0.02 or more, or (b) O_2 partial pressure: 5 x 10^-^3 ~ 1 x 10^-^
A method of manufacturing a transparent iridium oxide thin film on a substrate by performing multi-source sputtering under the conditions of 1 Torr, film formation speed ratio: Ir/M weight ratio = 0.02 or more. 2 The metal (M) is Sn, In, Ta, Zn, Ti,
The method according to claim 1, characterized in that the material is Si, Mg, Ca, W, Mo or Sb.