JP2001279440A - Co CONTAINING OXIDE FILM DEPOSITION METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method in which the deposition of a Co containing oxide film can be performed with high productivity because the use of a thick target is possible and resultantly the frequency of target replacement can be reduced. SOLUTION: In the process for depositing the Co containing oxide film, magnetron sputtering is performed by using of a metallic target where the magnetic flux density in the inner part is <=0.2 T and the total content of Co and Fe is >=80 atomic % to the whole metal when an external magnetic field is applied at 7.96 kA/m intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for forming a Co-containing oxide film.

[0002]

2. Description of the Related Art A Co-containing oxide film is known as a heat ray reflective film having low solar energy transmittance. For example, for the purpose of improving the cooling efficiency in a vehicle or a building, a Co-containing oxide containing cobalt oxide as a main component and iron oxide as a heat ray reflection glass used for a window glass for a vehicle or a building, for example. Glass with a membrane is known.

As a method for forming such a Co-containing oxide film on the surface of glass or the like, there are a spray method, a CVD method and the like. However, in these methods, in order to form a film having excellent uniformity of film thickness and film quality over a large area and at a stable film forming speed, it is necessary to strictly control film forming conditions.

On the other hand, a magnetron sputtering apparatus is used for forming various kinds of coating films because it has a stable film forming rate, is easy to control, and has excellent uniformity of the obtained film quality and thickness. This is particularly effective when it is required to form a large-area coating uniformly on the surface of the article.

[0005] In a magnetron sputtering apparatus, secondary electrons emitted from a target are trapped by a magnetic field formed between the target and the substrate, causing ionization collision to generate plasma, and ions in the plasma are incident on the target. This is an apparatus for forming a film by sputtering a target material. At this time, a tunnel-like magnetic field is formed between the target and the substrate so that electrons can orbit around the target due to drift in the E × B direction, so that a dense plasma can be formed even at a low gas pressure. Becomes Thereby, loss of the target particles due to collision of the target particles emitted from the target with the gas can be suppressed, and a high deposition rate can be obtained.

However, when a target material containing Co, which is a ferromagnetic material, is used, a closed magnetic circuit is formed by the magnet unit and the magnetic target, and the lines of magnetic force are cut off by the magnetic target and between the target and the substrate. There is a problem that a tunnel-like magnetic field is not formed, no discharge occurs, and no plasma is generated. For example, FIG.
Although the magnetic field line distribution is obtained when an o-20 at% Fe alloy with a thickness of 8 mm is used, the magnetic field lines from the magnet unit cannot pass through the target material, and a tunnel-shaped magnetic field is not formed on the target.

Therefore, it is conceivable to form a film by using a thin target so that the lines of magnetic force pass through the magnetic target to form a tunnel-like magnetic field between the target and the substrate. However, when a thin target is used, the frequency of replacement of the exhausted target is large, and the productivity is significantly reduced. In particular, in the case of a large-scale apparatus, it takes a long time to replace the target, which is a problem. It is also conceivable that a magnetic material is formed by magnetron sputtering by using a special magnet arrangement, but even in this case, a thick target cannot be used.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method capable of forming a Co-containing oxide film with high productivity by performing magnetron sputtering using a thicker target than before. is there.

[0009]

The present inventors have conducted intensive studies on the formation of a magnetic field in magnetron sputtering using a target containing Co, which is a ferromagnetic material.
Even if the composition contains Co which is a ferromagnetic substance, the strength of the external magnetic field is 7.96 kA /
When a target having an improved magnetic property and an internal magnetic flux density of 0.2 T or less at m is used, the magnetic field lines penetrate the target without forming a closed magnetic circuit between the magnet and the target. A tunnel-shaped magnetic field can be formed between the substrate and the substrate, and a magnetic field having a strength required for sputtering can be formed even when a target having a thickness larger than that of the related art, for example, a thickness of 4 mm or more is used. The inventors have found that the present invention can be achieved, and have reached the present invention.

That is, the present invention provides an external magnetic field of 7.96.
The internal magnetic flux density when applied at an intensity of kA / m is 0.
Provided is a method for forming a Co-containing oxide film by magnetron sputtering using a metal target having a content of 2 T or less and a total content of Co and Fe of 80 at% or more with respect to all metals. In particular, it is preferable to use a target having a total content of 80 at% of Co and iron since the magnetic field strength required for magnetron discharge and the characteristics of the formed film can be compatible. Further, the internal magnetic flux density is preferably 0.1 or less, and more preferably 0.01 T or more. In addition, the present invention can perform magnetron sputtering by forming plasma on a target using a target having a thickness of 4 mm or more, and more particularly, 6 mm or more. is there.

The metal target used in the present invention is C
It contains o and Fe at the above contents and has the above-mentioned magnetic properties. In the present invention, the target material having the magnetic characteristics can be manufactured by various methods. For example, the magnetic properties can be achieved by adding a second component such as Cr or Ti. At this time,
The addition amount of the second component varies depending on the type of the second component, and the addition amount is appropriately determined within the range of 20 at% or less based on the total metal in accordance with the type. Further, by devising a method of manufacturing the target material, the magnetic characteristics of the target material can be reduced. For example, when the target material is melted and cooled, by controlling the cooling rate, etc.
Magnetic properties can be improved.

Further, the targets are Co and Fe,
Further, other components may be included in addition to Cr, Ti, and the like. For example, Ni, Ta, Nb, Mo, Mn, Si,
It may contain Cu, Ba, Zn, Zr, C and the like. These are desirably 5 at% or less with respect to all metals from the viewpoint of magnetic properties.

The magnetron sputtering apparatus used in the present invention is not particularly limited, and may be any of direct current (DC) and high frequency (RF) magnetron sputtering apparatuses.
Sputtering conditions (discharge power, strength of a magnetic field by a magnet unit, gas pressure, film formation time, and the like) can be selected according to the surface properties of the film formation target, the film formation area, required film characteristics, and the like. For example, in a DC magnetron sputtering apparatus, it can be performed under a reduced pressure of about 0.4 Pa, a magnetic field strength of about 0.02 T, and a discharge power of about 1 kW. Non-reactive sputtering or reactive sputtering can be performed by introducing a reactive gas between the substrate and the target. The reactive gas used is not particularly limited, and oxygen, nitrogen, hydrogen, and the like can be used.

The object of film formation according to the present invention is not particularly limited. For example, the method of the present invention can be applied to glass, plastic,
It can also be used as a method for forming a Co-containing oxide film on the surface of a base material such as a metal or ceramic.

The method of the present invention is useful as a method for forming a Co-containing oxide film on the surface of various articles. In particular, a large-area and uniform Co-containing oxide film can be formed at a high deposition rate. For example, it is useful as a method for forming a Co-containing oxide film as a heat ray reflective film of a window glass for vehicles or buildings.

[0016]

The present invention will now be described more specifically with reference to examples of the present invention. The present invention is not limited to this embodiment.

Embodiment 1 FIG. 1 is a schematic sectional view showing a main structure of a magnetron sputtering apparatus used in an embodiment of the present invention. The apparatus shown in FIG. 1 includes a magnet unit 1 and a backing plate 3 that supports and fixes a target 2 disposed below the magnet unit 1 and is electrically integrated with the target.
The substrate 4 is arranged in a lower part facing the substrate. The vacuum chamber containing the magnetron sputtering apparatus and the backing plate 3 supporting the target 2 are DC
An anode and a cathode are connected to a power supply and a voltage is applied between them.

The magnet unit 1 has a substantially disk-shaped SUS43.
The yoke 6 is made up of a magnetic yoke 6 (having a diameter of 136 mm) and a samarium-cobalt-based permanent magnet 5 arranged on the lower surface of the magnetic yoke 6. The permanent magnet 5 includes a columnar magnet 5a disposed below the lower central protrusion 6a of the magnetic yoke 6, and an annular magnet 5b disposed on the lower peripheral protrusion 6b of the magnetic yoke 6. The height of the magnet unit 1 including the permanent magnet 5 and the magnetic yoke 6 is 22 mm. This device is
The whole is housed in a vacuum chamber (not shown).

The targets are Co 72%, Fe 8%, Cr
Made of 20% (at%) alloy, thickness 8 mm, diameter 152.
4 mm circular target. FIG. 2 shows the results obtained by using a magnetic ring to measure the internal magnetic characteristics of a 3 mm square sample produced by cutting out the target material. The magnetic properties of a conventional alloy target of 80% Co and 20% Fe (at%) are also shown. CoFe
By adding Cr to the alloy, the magnetic properties of the target material were improved, and the magnetic flux density inside the target material at an external magnetic field of 7.96 kA / m was 0.0175 T.

Using this apparatus, an experiment on film formation on a glass substrate was performed. First, a soda lime glass plate having a thickness of 2 mm x 100 mm square, which has been washed and dried with distilled water and ethanol as a substrate, is placed 60 mm below the target, and the inside of a vacuum chamber in which a magnetron sputtering device is installed is turbocharged. The pressure was reduced to 1.0 × 10 ⁻⁴ Pa by a molecular pump. Next, 50 sccm of oxygen gas was introduced to increase the gas pressure in the vacuum chamber to 2.
The pressure was maintained at 6 × 10 ⁻¹ Pa, the backing plate was used as a cathode, the vacuum chamber was used as an anode, a voltage was applied (discharge power: 0.5 kW), plasma was generated under the target, sputtering was performed for 150 seconds, and soda lime glass was used. A Co-containing oxide film having a thickness of 30 nm was formed on the plate. When the magnetic field line distribution at this time was calculated, FIG.
As shown in (1), since the target material was a magnetic material, the magnetic field lines were affected by the magnetic material, but it was found that a tunnel-like magnetic field was formed above the target. Note that FIG.
3 is upside down from the schematic sectional view shown in FIG.
The z axis in the middle is the central axis of the circular target, with the surface of the permanent magnet 5a as the origin and the direction of the substrate 4 as the positive direction. The r-axis in FIG. 3 indicates the radial direction with the center of the target as the origin. Further, the square in FIG. 3 indicates the position of the target.

The obtained glass with the film was heated at 650 ° C. for 15 minutes.
The film characteristics of the sample that had been heat-treated in an air atmosphere for minutes were evaluated. As a result, first, regarding the optical characteristics, the visible light reflectance of the surface with the film was 33%, the visible light reflectance of the surface without the film was 22%, and the visible light transmittance was 34%. As for electrical characteristics, the sheet resistance of the film was 4.3 × 10 ⁸ Ω / □. The change in visible light transmittance when immersed in 0.05 mol / L sulfuric acid for 24 hours was + 3% or less, and 0.1 mol / L or less.
The change in visible light transmittance when immersed in L sodium hydroxide for 24 hours was + 1% or less. Furthermore, as a result of analyzing the composition of the film, it was found that Co, Fe and Cr were contained in the same ratio as the target material.

Comparative Example 1 As a target, 80 at% C
A film was formed under the same conditions as in Example 1 except that an o-20 at% Fe alloy having a thickness of 8 mm (internal magnetic flux density of 1.7 T at an external magnetic field strength of 7.96 kA / m) was used. However, discharge was not possible and a film could not be formed. Also, as a result of calculating the magnetic field line distribution at this time,
As shown in FIG. 4, it was found that the lines of magnetic force from the magnet unit could not penetrate the target material and a tunnel-like magnetic field could not be formed on the target.

[0023]

According to the method of the present invention, it is possible to form a film by magnetron sputtering using a thicker target than before, so that the frequency of replacement of the target can be reduced, which is effective for improving the productivity. In particular, in an industrial production facility that performs continuous discharge, compared to a conventional target having a thickness of about 3 mm, which is the limit at which discharge is possible, a continuous discharge of only about several days was possible.
By using a target having a thickness of about 6 mm, the continuous discharge time can be doubled, which is effective for improving productivity in actual operation.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main configuration of a magnetron sputtering apparatus.

FIG. 2 is a diagram illustrating magnetic properties of a target material used in an example.

FIG. 3 is a diagram showing a magnetic field line distribution near a target used in an example.

FIG. 4 is a diagram showing a magnetic field line distribution near a target used in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet unit 2 Target 3 Backing plate 4 Substrate 5 Permanent magnet 6 Magnetic yoke

Claims (1)

[Claims] An internal magnetic flux density of 0.2 T or less when an external magnetic field is applied at an intensity of 7.96 kA / m.
And a method of forming a Co-containing oxide film by magnetron sputtering using a metal target having a total content of Fe and 80 at% or more with respect to all metals.