JP2002170430A - Base body with conductive film and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base body with a conductive film whose surface requires no complicated manufacturing processes such as heat treatment after forming a film and grinding of a film surface, and its manufacturing method. SOLUTION: In the base body with a conductive film, a substrate film mostly composed of a zirconium oxide is formed 1 nm and 150 nm thick. A conductive film mostly composed of oxides of an indium and zinc is formed on the substrate film, wherein average roughness Ra of the conductive film surface is 3.0 nm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate with a conductive film and a method for producing the same.

[0002]

2. Description of the Related Art A conductive film mainly containing an oxide of indium and tin (hereinafter, also referred to as an ITO film) is used for a display device such as an LCD (Liquid Crystal Display), an organic EL (Electroluminescence) element, a solar cell, and the like. Are used as transparent conductive films for the electrodes. While the ITO film has excellent conductivity, high visible light transmittance, and chemical resistance,
Since it is soluble in certain kinds of acids, it has an excellent feature that it is easy to pattern.

[0003] From the viewpoint of conductivity and chemical resistance, ITO
Preferably, the film is crystalline. However, a crystalline film tends to have irregularities on its surface. When an ITO film is used for an organic EL device or the like, a large unevenness on the surface of the ITO film causes a problem such as a leak current or a dark spot.

After forming an ITO film at a relatively low temperature of 10 to 150 ° C., a heat treatment is performed at 100 to 450 ° C. to form an ITO film.
It has been proposed that the crystal orientation of the film be (111) orientation to suppress the leak current and dark spot of the organic EL element (Japanese Patent Laid-Open No. 11-87068). However, heat treatment after film formation complicates the manufacturing process and is not preferable in terms of productivity. Attempts have also been made to reduce the irregularities on the surface of the ITO film by polishing or acid treatment of the surface of the ITO film, but in any case, the manufacturing process becomes complicated and the productivity is also poor.

[0005]

SUMMARY OF THE INVENTION The present invention eliminates the need for complicated manufacturing steps such as heat treatment after film formation and polishing of the film surface.
It is an object of the present invention to provide a substrate with a conductive film having few irregularities on the surface and a method for manufacturing the same.

[0006]

According to the present invention, an acid is provided on a substrate.
The underlayer mainly composed of zirconium fluoride is 1 nm or more and 15
0 nm or less, and an indium oxide film is formed on the base film.
Conductive film (ITO film) whose main component is an oxide of tin and tin
The average surface roughness R of the formed ITO film surface _aIs 3.
Substrate with a conductive film, characterized in that the thickness is
Offer.

According to the present invention, there is further provided a base film containing zirconium oxide as a main component with a thickness of 1 nm or more and 150 nm or less on a substrate, and then forming an ITO film on the base film. Average surface roughness _Ra of 3.0 nm
The present invention provides a method for producing a substrate with a conductive film, characterized by obtaining the following substrate with a conductive film. In the present invention, I
The average surface roughness of the surface of the TO film means the average surface roughness of the surface of the substrate with a conductive film.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate in the present invention is not particularly limited, and examples thereof include an inorganic substrate such as a glass substrate and an organic substrate such as a plastic substrate. Examples of the glass substrate include an alkali-containing glass substrate such as a soda lime silicate glass substrate and a non-alkali glass substrate such as a borosilicate glass substrate. The average surface roughness R _a of the alkali-free glass substrate is about 0.1 to 5 nm. The average surface roughness R _a of the alkali-containing glass substrate is about 0.1 to 10 nm. In the present invention,
The average surface roughness _Ra is measured according to JIS B0601, the cutoff value is 0.8 μm, and the evaluation length is 2.4 μm.
m.

When an alkali-containing glass substrate is used, silicon oxide is used as a layer (alkali barrier layer) in order to prevent alkali ions contained in the glass substrate from diffusing into the ITO film and affecting the resistance value of the ITO film. (SiO
₂ ) It is preferable to form a film or the like. The average surface roughness R _a of the alkali-containing glass substrate alkali barrier layer is formed is preferably about 0.1 to 10 nm.

The method for forming the alkali barrier layer on the glass substrate is not particularly limited, and includes a pyrolysis method (a method of forming a film by applying a raw material solution and then heating), a CVD method, a sputtering method, a vapor deposition method, and an ion plating method. For example. For example, in the case of a SiO ₂ film, a film formation method such as an RF (high frequency) sputtering method using a SiO ₂ target or an RF or DC (direct current) sputtering method using a Si target is used. When a Si target is used, it is preferable to use an Ar-O ₂ mixed gas as a sputtering gas and determine the gas ratio of Ar and O ₂ so that the SiO ₂ film becomes a transparent film without absorption. The thickness of the SiO ₂ film is preferably 10 nm or more from the viewpoint of alkali barrier performance, and is suitably 500 nm or less from the viewpoint of cost.

The underlayer in the present invention is a film containing zirconium oxide as a main component. Hf, Fe,
Although impurities such as Cr, Y, Ca, and Si may be contained, the total amount of the impurities is 10 atomic% or less, particularly 1 atomic% or less based on the total amount of Zr and the impurity element. Is preferred.

The thickness (geometric thickness) of the underlayer is 1 nm or more and 150 nm or less. By the base film of the film thickness is present, can be easily controlled average surface roughness R _a of the surface of the resulting conductive film-coated substrate below 3.0 nm. The base film in the present invention affects the crystal growth of the ITO film formed thereon, can change the crystal orientation of the ITO film, and contributes to the flatness of the surface of the obtained substrate with a conductive film.

When the base film is relatively thin, it is considered that the base film is an island-shaped discontinuous film, and the island-shaped base film is such that the ITO film is easily oriented to the (400) plane. It is thought to promote nucleation. On the other hand, when the base film is relatively thick, the base film is considered to be in a continuous film state. In this case, the epitaxial action causes ITO
It is considered that the film is easily oriented to the (222) plane.

If the thickness of the underlayer is less than 1 nm, the effect as the underlayer of reducing the average surface roughness of the ITO film surface cannot be obtained. If the thickness of the underlying film exceeds 150 nm,
The effect as a base film is reduced, and the average surface roughness _Ra is 3.
It becomes difficult to obtain a substrate with a conductive film of 0 nm or less.
The thickness of the base film described above is an average film thickness, and the same applies to a case where a continuous film is not formed.

[0015] When the thickness of the base film of 15nm ultra 30nm or less, (400) / (222) diffraction intensity ratio is 0.1 or more and 1.0 or less, the average surface roughness R _a of the ITO film surface
Is 2.5 nm or less. The thickness of the underlayer is more than 30 nm1
For 50nm or less, (400) / (222) by the diffraction intensity ratio becomes 0.1 or less, the stronger the orientation of the (222) plane of the ITO film, the average surface roughness R _a of the ITO film surface It becomes 3.0 nm or less.

When the thickness of the underlayer is 1 nm or more and 15 nm or less, the main orientation plane of the ITO film is (400). That is, (400) diffraction intensity of the plane and (222) plane ratio of the diffraction intensity of the (400) / (222) Average surface roughness R _a of the diffraction intensity ratio is 1.0 ultra next, ITO membrane surface 2. It is preferable because it becomes 0 nm or less. Further, the thickness of the base film is 5 nm.
In the range of 10nm inclusive, the average surface roughness R _a of the ITO film surface becomes smallest, so excellent flatness can be obtained, particularly preferred.

The method for forming the underlayer is not particularly limited, and examples thereof include a thermal decomposition method, a CVD method, a sputtering method, a vapor deposition method, and an ion plating method. For example, metal Z
formed by an RF or DC sputtering method using an r target, or formed by an RF sputtering method using a stabilized zirconia target. Since a stabilized zirconia target has many impurities such as Y and Ca, it is more preferable to use a metal Zr target.

As a sputtering method, a DC sputtering method is preferable from the viewpoint of a film forming speed. As a sputtering gas, an Ar—O ₂ mixed gas is preferably used, and the gas ratio of Ar and O ₂ is preferably determined so that the underlying film becomes a transparent film without absorption.

In the present invention, as the ITO film, In ₂
A film composed of O ₃ and SnO ₂ may be mentioned, and the composition thereof is such that SnO ₂ is 1 to the total amount of (In ₂ O ₃ + SnO ₂ ).
Preferably, it is contained in an amount of up to 20% by mass. The thickness of the ITO film is preferably 100 nm or more and 500 nm or less from the viewpoint of resistance value, transmittance, and the like. The specific resistance value is 4 ×
The sheet resistance is preferably 10 ⁻⁴ Ωcm or less, and the sheet resistance value is preferably 20 Ω / □ or less.

The method of forming the ITO film is not particularly limited.
Examples include a thermal decomposition method, a CVD method, a sputtering method, an evaporation method, and an ion plating method. For example, IT
A method in which an O target is used and RF or DC sputtering is used. The sputtering gas is
It is preferable to use an Ar-O ₂ mixed gas and determine the gas ratio between Ar and O ₂ so that the specific resistance of the ITO film is minimized.

The film forming temperature during sputtering is 100 ° C.
It is preferable to carry out at a temperature of at least 500 ° C. If the temperature is lower than 100 ° C., the ITO film tends to be amorphous, and the chemical resistance of the film is reduced. When the temperature is higher than 500 ° C., crystallinity is promoted,
Irregularities on the film surface increase.

The substrate with a conductive film of the present invention can be used for electrodes of display devices such as LCDs, inorganic EL elements, and organic EL elements,
It is suitable as an electrode of a solar cell. In particular, in an organic EL device having a hole injection electrode, an electron injection electrode, and an organic light emitting layer between these electrodes, an organic EL device using the substrate with a conductive film of the present invention as the hole injection electrode is a preferable example. It is one of.

[0023]

[Example 1] A washed soda lime silicate glass substrate (average surface roughness _Ra : 0.5 nm) was set in a sputtering apparatus, and the substrate was heated to 250 ° C. Was kept at 250 ° C.
On this substrate, an SiO ₂ film was formed as an alkali barrier layer by an RF sputtering method. At this time, a disk-shaped Si target having a diameter of 150 mm was used as the target. An Ar—O ₂ mixed gas was used as a sputtering gas. The gas ratio of Ar to O ₂ is Ar: O ₂ = 70: 30
(Volume ratio), and the total pressure was 0.6 Pa. 0.5kW
And a film was formed. The film thickness was 20 nm. The average surface roughness R _a of the SiO ₂ film surface of the SiO ₂ film-coated substrate
Was 0.5 nm.

Next, Zr is formed on the SiO ₂ film as a base film.
An O ₂ film was formed by a DC sputtering method. At this time,
As the target, a disk-shaped Zr target having a diameter of 150 mm was used. The sputtering gas was used Ar-O ₂ mixed gas. The gas ratio of Ar to O ₂ is Ar: O ₂ = 7
0:30 (volume ratio) and the total pressure was 0.6 Pa.
Discharge was performed at 0.3 kW to form a film. The film thickness was 8 nm.

Next, an ITO film was formed by a sputtering method in contact with the base film. The target is 150m in diameter
A m-disk shaped ITO target was used. The composition of the ITO target was such that SnO ₂ was 10% by mass based on the total amount of (In ₂ O ₃ + SnO ₂ ). The sputtering gas was used Ar-O ₂ mixed gas. The gas ratio between Ar and O ₂ was Ar: O ₂ = 99.5: 0.5 (volume ratio), and the total pressure was 0.6 Pa. Discharge was performed at 0.3 kW to form a film. The film thickness was 150 nm. The obtained ITO
The composition of the film was the same as the composition of the target. When the conductivity was measured by a four-point probe method, the specific resistance of the ITO film was 2.5 × 10 ⁻⁴ Ω · cm (the sheet resistance was 16.
7Ω / □).

With respect to the obtained substrate with a conductive film, θ / 2
X-ray diffraction measurement was performed by the θ method. The measurement conditions were as follows: a Cu source radiation source, a tube voltage of 40 kV and a tube current of 20 m
A, the sampling width was 0.02 °, the scanning speed was 4 ° / min, the divergence slit was 1.0 °, the scattering slit was 1.0 °, and the light receiving slit was 0.15 mm. In the diffraction intensity obtained from the peak height after subtracting the background, the ratio of the obtained diffraction intensity of the (400) plane to the diffraction intensity of the (222) plane, and the ratio of the (400) / (222) diffraction intensity is 2. It was 0. From this, it was found that this ITO film was oriented in the (400) plane. Moreover, as a result of measuring the state of irregularities on the surface of the obtained substrate with a conductive film by AFM (atomic force microscope), the average surface roughness _Ra was 1.4 nm. At this time, the cutoff value was 0.8 μm, and the evaluation length was 2.4 μm.

Example 2 A substrate with a conductive film was produced in the same manner as in Example 1 except that the thickness of the ZrO ₂ film (underlying film) in Example 1 was changed to 45 nm. As a result of performing X-ray diffraction measurement in the same manner as in Example 1, the (400) / (222) diffraction intensity ratio was 0.0
It was 4. From this, this ITO film is (22
2) It was found that they were oriented in the plane. The surface roughness was measured by AFM in the same manner as in Example 1. As a result, the average surface roughness _Ra was 1.8 nm.

Example 3 (Comparative Example) ZrO ₂ film (underlying film)
A substrate with a conductive film was prepared in the same manner as in Example 1 except that no was formed. The surface roughness was measured by AFM in the same manner as in Example 1, and as a result, the average surface roughness _Ra was 5.0 nm.

[0029]

According to the present invention, heat treatment after film formation and I
A substrate with a conductive film having few irregularities on the surface and excellent flatness can be obtained without going through complicated manufacturing steps such as polishing and acid treatment of the surface of the TO film. Since the conductive film-attached film of the present invention has excellent flatness, it is suitable for an electrode of an organic EL device, and can suppress a leak current and a dark spot.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1343 G02F 1/1343 5G323 H01B 13/00 503 H01B 13/00 503B F term (reference) 2H090 HA04 HB02X HC01 HC03 JB02 JB03 2H092 HA04 MA04 MA05 NA16 NA19 4F100 AA17C AA20 AA27B AA33C AG00 AT00A BA03 BA07 BA10A BA10C EH66 GB41 JG01 JG01C JK15 YY00B YY00C 4G059 AA08 AB11 AC12 GA01 GA01 FA03 GA02

Claims (3)

[Claims] An underlayer mainly composed of zirconium oxide is formed on a substrate in a thickness of 1 nm to 150 nm, and a conductive film mainly composed of an oxide of indium and tin is formed on the underlayer. There are formed, a conductive film substrate with an average surface roughness R _a of the conductive film surface is equal to or less than 3.0 nm. 2. The substrate with a conductive film according to claim 1, wherein said base film has a thickness of 1 nm or more and 15 nm or less. 3. A base film containing zirconium oxide as a main component is formed on a substrate to a thickness of 1 nm or more and 150 nm or less.
Then, a conductive film containing an oxide of indium and tin as a main component is formed on the base film to obtain a substrate with a conductive film having an average surface roughness _Ra of 3.0 nm or less on the conductive film surface. A method for producing a substrate with a conductive film, comprising: