JP2001262339A - Method for depositing magnetic material film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for depositing a magnetic material film by which film deposition can be performed at a high film deposition rate by magnetron sputtering with a thick magnetic material target. SOLUTION: In this method for depositing a magnetic material film, magnetron sputtering is performed by using a magnetic material target in which the maximum magnetic permeability in the thickness direction is double or above the maximum magnetic permeability in the direction vertical to the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a magnetic material film by magnetron sputtering.

[0002]

2. Description of the Related Art In a magnetron sputtering apparatus, a secondary electron emitted from a target is trapped by a magnetic field formed between the target and a substrate, causing ionization collision to generate plasma, and ions in the plasma to the target. This is an apparatus that forms a film by sputtering a target material by being incident. 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 generated when the target particles emitted from the target collide with the gas can be suppressed, and a high deposition rate can be obtained.

[0003] However, when a magnetic material is used as the target material, a closed magnetic circuit is formed by the magnet unit and the magnetic target, and the magnetic field lines are cut off by the magnetic target, and a tunnel-like magnetic field is generated between the target and the substrate. Since it is not formed, there is a problem that it is not discharged and no plasma is generated.

[0004] Therefore, film formation is performed using a thin target in such a manner that lines of magnetic force penetrate the magnetic target and a tunnel-like magnetic field is formed between the target and the substrate. However, when a thin target is used, the frequency of replacement of the exhausted target is high, and the productivity has been significantly reduced. In particular, in the case of a large-scale apparatus, it takes time to replace the target, which has been a problem. Further, by using a special magnet arrangement, a magnetic material can be formed by magnetron sputtering, but even in this case, a thick target could not be used.

In the case where a magnetic material target is used, in the portion where the target becomes thin due to erosion, the leakage of the lines of magnetic force increases, so that the strength of the magnetic field locally increases, and the portion where the target is eroded more steeply. As a result, there is a problem that the use efficiency of the target is lowered, and the film forming speed corresponding to the portion is increased, and the uniformity of the obtained film is deteriorated.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a magnetic material film which can form a magnetic material film at a high film forming rate by magnetron sputtering using a thick magnetic material target. It is in.

[0007]

The present inventors have SUMMARY OF THE INVENTION As a result of intensive studies on the formation of the magnetic field in the magnetron sputtering using a magnetic material target, even a magnetic material target, the maximum permeability in the thickness direction (mu _V ) Is greater than the maximum magnetic permeability (μ _H ) in the direction perpendicular to the thickness direction,
In other words, as long as the magnetic permeability shows anisotropy, the lines of magnetic force pass through the target and a tunnel-like magnetic field is formed between the target and the substrate without forming a closed magnetic circuit between the magnet and the target. Yes, and μ _V is μ
If it is more than twice _H , it is thicker than before, for example, thickness 4
The inventors have found that a magnetic field having a strength required for sputtering can be formed even when a magnetic material target having a thickness of not less than mm is used, and a film can be formed with high productivity.

That is, according to the present invention, magnetron sputtering is performed using a magnetic material target whose maximum magnetic permeability in the thickness direction is at least twice, more preferably at least four times, the maximum magnetic permeability in the direction perpendicular to the thickness direction. A method for forming a magnetic material film is provided. In particular, the present invention can perform a magnetron sputtering by forming a plasma on a target using a magnetic material target having a thickness of 6 mm or more, particularly 10 mm or more. is there. Further, the present invention provides a magnetic material film formed by the above method.

The target used in the method of the present invention is:
From the viewpoint of suppressing the formation of a closed magnetic circuit by the target and the magnet unit, and forming a tunnel-shaped magnetic field between the target and the substrate through the lines of magnetic force passing through the target, the maximum permeability in the direction perpendicular to the thickness direction is obtained. permeability (μ _H) is 2.
It is preferably at most 51 × 10 ⁻⁵ H / m, more preferably at most 1.5 × 10 ⁻⁵ H / m. The maximum magnetic permeability (μ _V ) in the thickness direction is 3.77 × 10
^-5 H / m or more, and more preferably 6.0 × 1
It is preferably at least 0 ^-5 H / m.

As long as the magnetic permeability shows the above specific anisotropy, a film made of any magnetic material can be formed using a target made of any magnetic material. For example,
A target composed of Co, Ni, Fe and a mixture thereof can be used. The target is N
b, Mo, Mn, Si, Cu, Ba, Zn, Zr, C
r, Ti, Ta or the like may be contained. In particular, the present invention
When a magnetic material is formed using a target having a hexagonal crystal structure as a target, it is effective because magnetic permeability is easily made anisotropic.

A magnetic material target having anisotropy in magnetic permeability is formed, for example, by subjecting a cobalt ingot to composition processing and then performing cold working to form a processed texture, and the target remains in a processed texture without being recrystallized. It can be obtained by, for example, a method of molding the raw material, or a method of applying a magnetic field in one direction when cooling after melting the raw material.

The magnetron sputtering apparatus used in the present invention is not particularly limited, and may be a direct current (DC) or high frequency (RF) magnetron sputtering apparatus. Sputtering conditions (discharge power, strength of a magnetic field by a magnet unit, gas pressure, film formation time, etc.) can be selected according to properties, film formation area, required film characteristics, and the like. For example, in a DC magnetron sputtering apparatus, the amount of 0.1.
With a magnetic field strength of about 0.02 T under reduced pressure of about 4 Pa,
It can be performed with 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.

[0013] The film formation target of the method of the present invention is not particularly limited. A magnetic material film can be formed on the surface of a substrate made of any material such as glass, plastic, metal, and ceramics.

The method of the present invention is useful as a method for forming a magnetic material film on the surface of various articles. In particular, a large-area and uniform magnetic material film can be formed at a high film formation rate. For example, it is useful as a method for forming a film containing a magnetic material such as Co, Ni, Fe, or an oxide thereof as a heat ray reflective film of a window glass for a vehicle or a building.

[0015]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples of the present invention. The present invention is not limited to these examples.

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 has a magnet unit 1 and a backing plate 3 that supports and fixes a target 2 disposed above the magnet unit 1 and is electrically integrated with the target.
The substrate 4 is arranged on the upper 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 permanent magnet 5 disposed on the upper surface of the magnetic yoke 6. The permanent magnet 5 includes a columnar magnet 5a disposed on the upper central protrusion 6a of the magnetic yoke 6, and an annular magnet 5b disposed on the upper peripheral rim 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).

Using this apparatus, an experiment on film formation on a glass substrate was performed. As a target, 99.9% pure Co
Disc target (20mm thick, 152.4m diameter)
m) was used. This target has a maximum magnetic permeability in the thickness direction of 6.28 × 10 ⁻⁵ H / m and a maximum magnetic permeability in the direction perpendicular to the thickness direction of the target of 1.25 × 10 ⁻⁵ H / m.

First, a soda-lime glass plate having a thickness of 2 mm × 100 mm and washed and dried with distilled water and ethanol as a substrate is placed 60 mm above a target, and then placed in a vacuum chamber in which a magnetron sputtering apparatus is installed. Was reduced to a back pressure of 1.0 × 10 ⁻⁴ Pa by a turbo molecular pump. Next, oxygen gas 5
0 sccm was introduced and the gas pressure in the vacuum chamber was 2.6 × 1
0 ^-1 Pa, backing plate as cathode,
Using a vacuum chamber as an anode, a voltage is applied (discharge power: 0.5 kW), plasma is generated above the target, sputtering is performed for 150 seconds, and a 30-nm-thick Co oxide film is formed on a soda-lime glass plate. did. At this time, the stability of the discharge was good. The magnetic field strength was measured at the most eroded position on the target surface. Table 1 shows the results. Further, the film properties (visible light transmittance, visible light reflectance) of the obtained Co oxide film were evaluated to be good.

Comparative Example 1 As a target, the maximum magnetic permeability in the thickness direction was 6.28 ×
Use in 10 ^-5 H / m, Co Ltd. target material maximum permeability in the thickness direction and the vertical direction has a high magnetic permeability isotropic is 6.28 × 10 ^-5 H / m (thickness 20 mm) Except for this, film formation was attempted in the same manner as in Example 1, and the magnetic field intensity was measured. However, the magnetic field intensity on the target became 0.01 T or less, discharge was not possible, and a film could not be formed.

[0021] Comparative Example 2 maximum permeability in the thickness direction is 1.25 × 10 ^-5 H / m, the maximum magnetic permeability in the thickness direction and the vertical direction is 1.25 × 10 ^-5 H /
A film was formed in the same manner as in Example 1 except that a Co target material (thickness: 20 mm) having a low magnetic permeability and an isotropic low magnetic permeability was measured, and the presence or absence of discharge and the magnetic field intensity were measured. As a result, a magnetic field strength sufficient for the discharge of the magnetron was obtained on the target, but the magnetic field strength was lower than that of Example 1. At this time, a stable discharge cannot be performed at a gas pressure of 0.26 Pa.
It was necessary to increase the gas pressure to a degree. Further, as the gas pressure rises, the film formation rate becomes slower, and it was necessary to perform sputtering for 300 seconds in order to obtain a desired film thickness.

[0022]

[Table 1]

[0023]

According to the method of the present invention, it is possible to perform magnetron sputtering using a magnetic material target thicker than in the prior art, to reduce the frequency of target replacement and to form a magnetic material film at a high deposition rate. A film can be formed. In particular, in an industrial production facility that performs continuous discharge, according to the method of the present invention, as compared to a conventional target having a thickness of about 3 mm, which is the limit at which discharge is possible, only continuous discharge of about several days was possible. By using a target having a thickness of about 20 mm, continuous discharge for one week or more is possible, which is effective for improving productivity in actual operation. In addition, the method of the present invention can suppress a decrease in target use efficiency and a local increase in film formation rate due to erosion, maintain a high target use efficiency, and form a film with excellent uniformity. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main configuration of a magnetron sputtering apparatus according to an embodiment.

[Explanation of symbols]

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

Claims (3)

[Claims] A magnetron sputtering method using a magnetic material target having a maximum magnetic permeability in a thickness direction that is at least twice the maximum magnetic permeability in a direction perpendicular to the thickness direction. Method. 2. The method according to claim 1, wherein the target material has a maximum magnetic permeability of 2.51 × 10 ⁻⁵ H / m or less in a direction perpendicular to the thickness direction of the target. 3. A magnetic material film formed by the method according to claim 1.