JPH0644836A - Manufacture of transparent conductive thin film and its device - Google Patents

Abstract

PURPOSE:To manufacture a transparent conductive thin film of low resistance factor. CONSTITUTION:In a method of manufacturing a transparent conductive thin film on a substrate under a sputtering gas and reactive gas atomosphere with setter filming, sputter filmings are tried on the substrate several times intermittently. In this case, the first device allows a target 11 to be placed on the side of a polygonal rotary target holder 8 and the substrate 4 to be carried around there. The second device allows the substrate 4 to be carried on the plural targets 11 placed in series at certain spaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for producing a transparent conductive thin film.

[0002]

2. Prior Art and Problems to be Solved by the Invention IT
Transparent conductive thin films using conductive materials such as O (In ₂ O ₃ with Sn added), ZnO, and SnO ₂ are widely used in fields such as liquid crystal displays, touch panels, sensors, and transparent electrodes in solar cells. Demand is expected to increase in the future. The quality of the transparent conductive thin film is determined by the specific resistance value of the film. For example, in a liquid crystal display, a transparent conductive thin film having a smaller specific resistance value has been required with the increase in area and display density. . Similarly, in other applications, it is required to make the specific resistance value smaller.

Conventionally, such a transparent conductive thin film has been prepared by using a vacuum deposition method, an ion plating method, a sputtering method or the like (Plastic processing technology, Volume 17, Volume 3).
No. 1, pp. 1-5 (1990)), the sputtering method is most commonly used from the viewpoint of good controllability and reproducibility.

In the film forming method using the sputtering method, a metal oxide target having the same film composition or a metal target such as In—Sn alloy, Sn, Zn is sputtered in a mixed atmosphere of an inert gas and an oxygen gas. (Vacuum 30, Volume 6, No. 6, pages 546-554 (1987)
Year)). This oxygen is added in a trace amount as a reaction gas for adjusting the amount of oxygen vacancies acting as a donor. The conductivity of the obtained film depends on the amount of oxygen vacancies.

In order to reduce the specific resistance of the film, it is effective to apply high power to activate the plasma and promote the reaction in the film. However, in the normal sputtering method, it is necessary to apply a high potential difference between the target and the substrate for this purpose, and as a result, the sputtering atmosphere or high energy oxygen atoms or oxygen negative ions dissociated from the target damage the film, There is a problem that the specific resistance of the film cannot be lowered.

Therefore, the opposite target method (Journal of the Institute of Electronics, Information and Communication Engineers, C-II, Vol. J72-C-II, No. 4,321 (198)
As represented by 9)), the substrate surface is arranged at an angle from the face-to-face parallel to the target surface to suppress the incidence of high-energy particles described above, or as disclosed in Japanese Patent Laid-Open No. 2-232358. As described above, a method of improving the magnetic flux density on the target to reduce the potential difference between the target and the substrate and suppressing the incidence of high energy particles has been attempted.
Furthermore, there is also a method of using arc discharge plasma as a plasma activation method. However, in any of the methods, there are problems that the device becomes complicated, controllability is difficult, and the effect of reducing the resistance of the film is insufficient.

Therefore, an object of the present invention is to provide a method and apparatus for producing a transparent conductive thin film having a low specific resistance (resistivity).

[0008]

The present invention provides a method for producing a transparent conductive thin film on a substrate by a sputter film forming method in an atmosphere of a sputter gas and a reaction gas, wherein the sputter film is formed on the substrate. It is intended to provide a method characterized by being performed a plurality of times intermittently.

The present invention is a film forming method by a sputtering method. Any sputtering method such as a direct current sputtering method, a high frequency sputtering method, and a reactive high frequency sputtering method can be used.

The substrate used in the present invention includes glass, plastics such as polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides, polyvinyl chloride, polycarbonates, polystyrenes, polypropylenes, polyethylenes (copolymers other than homopolymers Substrates (including coalesce). Further, the substrate may be a laminated body containing two or more of these. The thickness of the substrate is not particularly limited because it depends on the application.

As the transparent conductive film formed on the above-mentioned substrate, metal films such as Pt, Au, Ag, Cu,
Single layer film such as Ni, Au / Bi ₂ O ₃ , Au / Cr, Ti
O ₂ / Ag / TiO ₂ , Bi ₂ O ₃ / Au / Bi
₂ O ₃ , ZnS / Ag / ZnS, SnO ₂ / Ag / Sn
Multi-layered film such as O ₂ ; oxide film such as SnO ₂ or In
₂ O ₃ , CdO, ZnO, CTO system (CdSnO ₃ , C
d ₂ SnO ₄ , CdSnO ₄ ), CdIn ₂ O ₄ , In
₂ TeO ₆ , WO-based, MoO ₃ -based, NiO-based, IrO-based single-phase films, Sn-added In ₂ O ₃ (ITO),
Was added Sb In ₂ O _3, W was added In ₂ O _3,
In ₂ O ₃ with Mo added, SnO ₂ with Sb added,
SnO _2, Al was added SnO _2, As with the addition of F
SnO ₂ (ATO) with addition of Al, ZnO with addition of Al
Composite (doped) phase film such as (AZO); chalcogenide (Cu ₂ S, CdS, ZnS), LaB as non-oxide film
₆ , a single layer film of TiN, TiC, ZrN, ZrB ₂ , HfN, etc., a _two- layer film of TiO ₂ / TiN, ZrO ₂ / TiN, etc .;

Sputtering is performed in a sputtering gas and reactive gas atmosphere. As the sputtering gas, for example, Ar,
An inert gas such as He, Ne, Kr and Xe can be used, and these gases may be used alone or in a mixture. As the reaction gas, for example, oxygen, nitrous oxide gas, or a mixed gas thereof can be used. The gas pressure of the gas atmosphere (sputtering gas + reaction gas) used is preferably 1.0 × 10 ⁻³ to 10 × 10 ⁻³ Torr. Further, the ratio of the sputtering gas to the reaction gas is preferably such that the amount of the reaction gas is 1 to 30% by volume in the total gas.

The substrate temperature during film formation is preferably as high as possible within the range where the substrate does not deteriorate, and is determined by the material of the substrate.
In the case of a plastic substrate, the temperature is usually room temperature to 100 ° C. Further, as other conditions for film formation, the conditions commonly used in each thin film forming method can be used.

The method of the present invention is characterized in that sputtering film formation is intermittently performed a plurality of times on the substrate.
Intermittently performing sputter film formation means that sputter film formation is not continuously performed at any place on the substrate, and sputter film formation-pause-sputter film formation is repeated.
In order to perform the sputter film formation intermittently in this way, for example, a method of preventing the continuous sputter film formation on the substrate by moving a sputter target, or a method of sequentially passing the substrate over a plurality of targets , Or a combination thereof. When the sputter target is moved, one or a plurality of sputter targets may be moved, for example, in a reciprocating motion or a rotating motion. At this time, the substrate may be stationary or may be transported. Further, it is also possible to carry two or more sets of substrates, and a plurality of targets reciprocate or rotate between the substrates. Further, a method of repeating the operation of turning on / off the voltage applied between the substrate and the vacuum container (ground) and the facing target is also possible.

Further, it is preferable that the substrate is always exposed to the atmosphere of the reaction gas even when the substrate is not subjected to the sputtering film formation, that is, in the rest state. For example, one or a plurality of reaction gas introduction pipes may be provided with gas outlets in the vicinity of the substrate so that the reaction gas is constantly blown onto the substrate. The gas blowing direction may be vertical or parallel to the substrate surface.

The transparency of the film obtained by the above method is required to have a visible light transmittance of at least several tens% or more, and practically about 80% or more is usually required. The conductivity is proportional to the product of carrier concentration (density of carrier electrons) and mobility (mobility). In the present invention, the carrier concentration and mobility of the obtained film are not particularly limited, and the higher the better, the lower the resistivity the better. The film thickness is usually several thousand angstroms, though it varies depending on the use.

The transparent conductive film produced by the present invention is used for photoelectric conversion such as solar cells and photosensors; for display devices such as liquid crystal, electroluminescence, electrochromic and EL; for buildings, automobiles, aircraft and furnaces. It can be used in a wide range of fields such as heat ray reflection of various windows such as peep windows, variable light shielding of visible light, anti-fog / anti-ice applications; antistatic applications; touch switch applications; optical communication applications.

The present invention also provides an apparatus for performing the above method. One of them is a sputtering film forming apparatus that has a substrate transfer means, a sputtering target, a gas introduction means, and an exhaust means in a vacuum chamber, and forms a film on a substrate by plasma discharge generated between the substrate and the target. ,
The substrate transfer means is installed so as to surround a rotatable target holder, and the target holder is a polygonal column that rotates about a central axis, and the side face of the polygonal column faces the substrate. The apparatus is characterized in that a sputter target is provided on at least one of the side surfaces.

A method for carrying out the method of the present invention with respect to the above apparatus will be described with reference to FIG. First,
All elements are inside the vacuum chamber 1, which is constantly evacuated by the exhaust ports 2 and 3. The substrate 4 is delivered by the substrate delivery core 5, is transported around the target holder 8 by the guide roller 6 and then the touch roller 7, and reaches the winding core 10 via the guide roller 9. On the surface of the target holder 8 facing the substrate,
A target 11 is provided. Target holder 8
Is a polygonal column that rotates about its central axis. Examples of the polygonal prism include a triangular prism, a quadrangular prism, a pentagonal prism, a hexagonal prism, a heptagonal prism, and an octagonal prism. Sputter gas introduction tube 12 and reaction gas introduction tube
The gas introduced from 13 is ionized under the voltage (DC power supply: not shown) applied to the target 11 to generate plasma, and the target film material substance splashed by the plasma is deposited on the substrate. The film is formed. At this time, since the target holder 8 is rotating, the target 11 sequentially forms a film on the substrate being conveyed as the target holder 8 moves. Looking at an arbitrary place on the substrate 4, film formation is not performed for a certain period of time from the film formation by one target to the film formation by the next target, that is, sputter film formation is performed intermittently. .

In order to exert the effects of the present invention, the rotation speed of the target holder and the transfer speed of the substrate are not particularly limited. Practically, the substrate transfer speed is 1.0 to 1
The rotation speed of the target holder is 5.
It is 0-60 rpm. However, when the target holder is rotating in the same direction as the substrate transport direction, it is necessary to rotate the target holder at a rotation speed different from the substrate transport speed.

The present invention further provides the following device. That is, in a sputtering film forming apparatus that has a substrate transporting unit, a sputtering target, a gas introducing unit, and an exhausting unit in a vacuum chamber, and forms a film on a substrate by plasma discharge generated between the substrate and the target, at intervals. The apparatus is characterized in that the substrates are sequentially transported on two or more sputter targets arranged in series, and a reaction gas outlet is provided near the substrates between the targets.

A method for carrying out the method of the present invention with respect to the above apparatus will be described with reference to FIG. First,
All elements are inside the vacuum chamber 1, which is constantly evacuated by the exhaust ports 2 and 3. The substrate 4 is delivered by a substrate delivery core 5, passes through a guide roller 6, then a touch roller 7, a guide roller 9, and then a take-up core 10 and is conveyed. The substrate 4 is transported and sequentially passes over two or more targets 11 provided at intervals, and a film is formed when passing over the targets 11.
The number of targets is preferably 2-5. On the target, the gas introduced from the sputter gas introduction tube 12 and the reaction gas introduction tube 13 is ionized under the voltage (DC power supply 14) applied to the target 11 to generate plasma, which is splashed by the plasma. The target film material material is formed on the substrate, and ordinary sputter film formation is performed. Since the film is not formed on the substrate until it passes through one target after passing through the next target, the film is intermittently formed on the transported substrate 4. In a preferred embodiment, in the section where the substrate 4 is not formed, the reaction gas is blown from the reaction gas introducing pipe 13 ′ to cause the substrate 4 to flow.
Are constantly exposed to reactive gases.

In this apparatus, the ratio of the sputter gas to the reaction gas can be the same as the conventional one in the vicinity of the substrate, that is, in the sputter gas introduction pipe 12 and the reaction gas introduction pipe 13, but also in the vicinity of the substrate. When the reaction gas is introduced (reaction gas introduction pipe 13 '), it is preferable that the total reaction gas content is 1.0 to 30% by volume.

[0024]

In the method of the present invention, since the film formation is performed intermittently, the substrate is not subjected to the sputter film formation for a certain period of time from one film formation by sputtering to the next film formation. As a result, damage to the membrane is reduced. As a result, high power can be input and high plasma activity can be obtained.
The resistivity of the film can be lowered.

[0025]

The present invention will be described in more detail by the following examples. Examples 1 to 4 100 μm thick polyethylene terephthalate (hereinafter,
A film was formed on a substrate (sometimes referred to as PET) using the sputtering apparatus shown in FIG. 1A under the following conditions: Initial vacuum degree: 2 × 10 ⁻⁶ Torr, introduced from 12 Sputtering gas: Ar gas, reaction gas introduced from 13: O ₂ gas, total gas pressure: 10 × 10 ⁻³ Torr (Ar: O ₂ partial pressure = 100:
3), Substrate temperature 30 ° C, Target holder: Hexagonal column with a bottom of 50 cm on each side and a height of 70 cm, and targets are installed on every other side of the six sides (one target area:
2400 cm ² ), number of rotations 20 rpm (rotation in the opposite direction to the substrate transfer), substrate transfer speed: 7.0 m / min in Example 1, and varied appropriately in the following Examples to keep the film thickness constant.

Target: a powder sintered body of In ₂ O ₃ and SnO ₂ (weight ratio 90:10). Table 1 shows the film forming speed and the input power.

Thus, the ITO film (film thickness 150) is formed on the substrate.
0 angstrom). The resistivity and visible light transmittance of this film were measured, and the results are shown in Table 1.

The resistivity was measured by the four-terminal method.
The visible light transmittance is a value obtained by measuring with a simple device with a fixed wavelength (680 nm) and subtracting the absorption in the PET substrate.

[0029]

[Table 1]

* 1 The exposure time is the effective time for film formation.

* 2 Unit: × 10 ⁻⁴ Ω · cm Comparative Examples 1 to 4 In the apparatus used in Examples 1 to 4 (the apparatus of FIG. 1 (A)), a hexagonal cylindrical target holder was used instead of the target holder. Sputtering was performed on the same PET substrate as in Example 1 under the same film forming conditions as in Examples 1 to 4 except that a target was used and a target was circulated around the circumference of the cylinder (area: 5000 cm ² ). The film was formed. The input power and the film forming speed are shown in Table 2.

Thus, the ITO film (film thickness 150) is formed on the substrate.
0 angstrom). The resistivity and visible light transmittance of this film were measured, and the results are shown in Table 2.

[0033]

[Table 2]

* 1 The exposure time is the effective time for film formation.

* 2 Unit: × 10 ⁻⁴ Ω · cm Examples 5 to 8 The same PET substrate as in Example 1 was used to form a film by sputtering using the apparatus shown in FIG. The film forming conditions were as follows.

Initial degree of vacuum: 2 × 10 ^-6 Torr, sputter gas introduced from 12: Ar gas, reaction gas introduced from 13, 13 ': O ₂ gas, sputter gas introduced from 12, reaction introduced from 13 Gas (volume ratio) = 100: 3 Total gas pressure: 10 × 10 ⁻³ Torr (Ar: O ₂ partial pressure = 100:
3) Substrate temperature 30 ° C., Substrate transport speed: 7.0 m / min in Example 5, and in the following examples, the film thickness was appropriately changed to make the film thickness uniform.

Target installation interval: 200 cm Area of one target: 2400 cm ² Target: Sintered powder of In ₂ O ₃ and SnO ₂ (weight ratio 90:10) It was as it was.

Thus, the ITO film (film thickness 150) is formed on the substrate.
0 angstrom). The resistivity and visible light transmittance of this film were measured, and the results are shown in Table 3.

[0039]

[Table 3]

* 1 The exposure time is the effective time for film formation.

* 2 Unit: × 10 ^-4 Ω · cm Examples 9 to 12 Same as Examples 5 to 8 except that gas was not introduced from reaction 13 'in the apparatus used in Examples 5 to 8. Under the film forming conditions, a film was formed on the same PET substrate as in Example 1 by sputtering. The input power and the film forming speed are shown in Table 4.

Thus, the ITO film (film thickness 150) is formed on the substrate.
0 angstrom). The resistivity and visible light transmittance of this film were measured, and the results are shown in Table 4.

[0043]

[Table 4]

* 1 The exposure time is the effective time for film formation.

* 2 Unit: × 10^-FourΩ ・ cmComparative Examples 5-8  On the same PET substrate as in Example 1, the DC plate shown in FIG.
Continuous sputter using a magnetor magnetron sputter device
The film was formed. The film forming conditions were as follows.

Initial degree of vacuum: 2 × 10 ^-6 Torr, sputtering gas introduced from 12: Ar gas, reaction gas introduced from 13: O ₂ gas, total gas pressure: 10 × 10 ^-3 Torr (Ar: O ₂ Partial pressure of = 100:
3) Substrate temperature 30 ° C. Substrate transport speed: 7.0 m / min in Comparative Example 5, and varied appropriately in the following Comparative Examples in order to keep the film thickness constant.

Target area: 2400 cm ² Target: In ₂ O ₃ and SnO ₂ powder sintered body (weight ratio 90:10) Table 5 shows the film forming rate and the input power.

Thus, the ITO film (film thickness 150) is formed on the substrate.
0 angstrom). The resistivity and visible light transmittance of this film were measured, and the results are shown in Table 5.

[0049]

[Table 5]

* 1 The exposure time is the effective time for film formation.

* 2 Unit: × 10 ^-4 Ω · cm

[0052]

According to the present invention, a transparent conductive film having a low resistance can be manufactured. High-speed film formation is also possible.
Therefore, the transparent conductive film obtained by the method of the present invention is industrially very useful and can be used in a wide variety of fields.

[Brief description of drawings]

1 (A) is a schematic cross-sectional view of an apparatus of the present invention used in Examples 1 to 4, and FIG. 1 (B) is a schematic sectional view of the apparatus of the present invention used in Examples 5-8. It is a schematic sectional drawing of an apparatus.

FIG. 2 is a schematic cross-sectional view of a conventional sputtering apparatus used in Comparative Examples 5-8.

[Explanation of symbols] 1 vacuum chamber 2-3 exhaust port 4 substrate 5 substrate delivery core 6 delivery side guide roller 7 touch roller 8 target holder 9 winding side guide roller 10 winding core 11 target 12 sputter gas introduction pipes 13, 13 ′ Reaction gas introduction pipe 14 DC power supply 15 Cooling can

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // H01B 5/14 A

Claims (3)

[Claims] 1. A method for producing a transparent conductive thin film on a substrate by a sputtering film forming method in an atmosphere of a sputtering gas and a reaction gas, wherein the sputtering film forming is intermittently performed a plurality of times on the substrate. A method characterized by. 2. A sputtering film forming apparatus, which has a substrate conveying means, a sputtering target, a gas introducing means and an exhausting means in a vacuum chamber and forms a film on a substrate by plasma discharge generated between the substrate and the target, The substrate transfer means is installed so as to surround a rotatable target holder, and the target holder is a polygonal column that rotates about a central axis, and the side face of the polygonal column faces the substrate. The apparatus for performing the method of claim 1, wherein at least one of the side surfaces is provided with a sputter target. 3. A sputtering film forming apparatus which has a substrate transfer means, a sputtering target, a gas introducing means and an exhausting means in a vacuum chamber and forms a film on a substrate by plasma discharge generated between the substrate and the target, 2. The substrate is sequentially transported on two or more sputter targets arranged in series at intervals, and a reaction gas outlet is provided near the substrate between the targets. Apparatus for carrying out the method of.