JPH06338409A - Mangetic thin film and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture an excellent magnetic thin film by a method wherein C and O are added to an Fe-Al-Si-based alloy thin film and at least one out of Ti, Zr, Hf, V, Nb and Ta as group IVa elements and group Va elements is added or, in addition, also Ru is added. CONSTITUTION:Symbols (a) to (g) represent comsition ratios in atomic %, and a symbol T represents at least one out of Ti, Zr, Hf, V, Nb and Ta as group IVa elements and group Va elements. The title magnetic thin film is composed of a soft magnetic alloy which is indicated by a composition formula of FeaAlbSicCdOeTf, where respective values for the symbols (a) to (f) are a+b+c+ d+e+f=100, 8<=b<=12, 14<=c<=18, 0.5<=d<=8, 0.2<=e<=6 and 0.1<=f<=5. Alternatively, the title magnetic thin film is featured in such a way that it is composed of a soft magnetic alloy which is indicated by a composition formula of FeaAlbSicCdOeTfRug, where respective values for the symbols (a) to (g) are a-b+c+d+e+f+g+=100, 8<=b<=12, 14<=c<=18, 0.5<=d<=8, 0.2<=e<=6, 0.1<=f<=5 and 0.1<=g<=3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic thin film and a method for manufacturing the same, and more particularly to Fe, Si and Al as main components, and C and O.
The present invention relates to a magnetic thin film made of a soft magnetic alloy containing, for example, a magnetic thin film suitable for a magnetic head for high density recording, and a method for manufacturing the magnetic thin film.

[0002]

2. Description of the Related Art In recent years, in the field of magnetic recording, along with the increase in recording density, there is a trend toward narrower tracks, shorter wavelengths, and higher frequency bands. In response to this increase in recording density, a metal tape using magnetic powder such as Fe, Co, and Ni powder of ferromagnetic metal as a magnetic recording medium, or a ferromagnetic metal material is deposited on the base film by vapor deposition. Vapor deposition tape has come to be used. Since this type of magnetic recording medium has a high residual magnetic flux density Br, the material of the magnetic core of the magnetic head used for recording / reproducing is also required to have a high saturation magnetic flux density Bs.

As a conventional soft magnetic material having a high saturation magnetic flux density, a so-called sendust alloy of the Fe-Al-Si system is typical, but the sendust alloy thin film has a relatively high hardness, but is, for example, a ferrite material. Compared with this, it is inferior in wear resistance, and since it is a metal material, it has drawbacks such as easy rust. Further, when the metal vapor deposition tape is made to run still, corrosive wear occurs due to some influence from the tape, making it unusable.

For this reason, in addition to Fe, Al, and Si which are the main components of the sendust thin film, additives such as Ti, Cr, Nb, and platinum group metals are added to prevent the above-mentioned rust, and increase hardness to improve wear resistance. There is a method to improve the sex.

However, the addition of the above-mentioned additives lowers the saturation magnetic flux density Bs of the sendust alloy thin film, which is disadvantageous in dealing with a magnetic recording medium having a high residual magnetic flux density such as a metal tape.

Therefore, by adding nitrogen or oxygen instead of the above-mentioned additives, it is possible to significantly improve hardness and magnetic permeability without lowering the saturation magnetic flux density.
60-220913, JP-A-60-218820, JP-A-60-218821
And JP-A-60-220914.

[0007]

However, the above-mentioned conventional example has the following problems.

First of all, the stress during film formation becomes a problem.
When the thin film 11 is formed on the substrate 10 as shown in FIG. 9, when the stress is positive as shown in (a), the stress causes the substrate 10 to warp so that the film forming surface side of the thin film 11 becomes concave, When the stress is negative as in (b), the film formation surface side warps so as to be convex.

The warp caused by this stress becomes a serious problem in the manufacturing process of the magnetic head. For example, taking a manufacturing process of a so-called metal-in-gap head in which a soft magnetic alloy thin film is formed facing the magnetic gap of the magnetic core, as shown in FIG.
The pair of ferrite blocks 15 having the track groove 13 for determining the track width T and the winding groove 14 for the coil winding as shown in FIG. 2 are sputtered in an atmosphere in which Ar is mixed with nitrogen or oxygen. When the soft magnetic alloy thin film of the example is formed, the block 15 warps due to the negative stress from the thin film. Then, in the step of abutting a pair of the ferrite blocks 15 on which the film has been formed and bonding them by glass bonding, the blocks 15
If it is warped, gaps are formed at both ends of the blocks 15 as indicated by reference numeral 12 in FIG. 11, and the formation of the magnetic gap g becomes uneven. Further, when the amount of warp is further large, the ferrite block 15 may be cracked.

A second problem is that air bubbles are generated during the above glass bonding, which is also a serious problem in the head manufacturing process.

A third problem is that when the sendust film is formed by sputtering in an atmosphere in which Ar gas is mixed with nitrogen or oxygen, the magnetic anisotropy of the sendust film increases and a magnetic field is applied in a certain direction. When applied, the magnetic permeability is large, but when a magnetic field is applied in the direction orthogonal to that, the magnetic permeability decreases.

A method of generating this anisotropy will be described. For example, when a film is formed with a sufficient amount of nitrogen and oxygen added in consideration of corrosion resistance and wear resistance in a sputtering apparatus shown in FIG. In the rotating substrate holder 3, the magnetic permeability in the a direction (circumferential direction) and the b direction (radial direction) in the a direction is higher when the magnetic permeability is measured, and the magnetic permeability is smaller in the b direction. That is, the a direction is the hard axis direction and the b direction is the easy axis direction.

Then, as a result of investigating the relationship of the change of the anisotropy with respect to the added amount of nitrogen, the result is as shown in FIG. 13, and the anisotropy is reversed when the addition amount of 2.7 atomic% or more. However, the corrosive wear due to the running of the vapor deposition tape described above occurs unless the amount of nitrogen added exceeds 3 atomic%. Therefore, it is inevitable that the corrosive wear will be prevented in the area where the corrosive wear can be prevented by adding nitrogen. The direction becomes a difficult axis.

It is not determined in which direction the magnetic permeability is higher when the magnetic head is used, depending on the structure of the head, but it is possible to bring the hard axis in the desired direction (anisotropy It is more advantageous to design and manufacture the magnetic head.

The present invention has been made in view of the conventional problems as described above, and not only has a high saturation magnetic flux density and excellent corrosion resistance, but also has a small stress during film formation and generates bubbles during glass bonding. It is another object of the present invention to provide a magnetic thin film in which magnetic anisotropy can be controlled and a manufacturing method thereof.

[0016]

In order to solve the above problems, the magnetic thin film of the present invention is formed by sputtering in an atmosphere into which CO2 gas is introduced, and Fe, Al, Si
In addition to adding C and O to the system alloys, group IVa or Va
A soft magnetic alloy to which at least one of the group elements Ti, Zr, Hf, V, Nb, and Ta is added, or Ru is further added.
Is added to the soft magnetic alloy, and the content of each element is 8 to 12 atom% of Al, 14 to 18 atom% of Si, 0.5 to 8 atom% of C, and 0.2 to O of O. 6 atom%, IV
0.1 to 5 atomic% of Group a to Va elements and Ru of 0.
1 to 3 atomic% and the rest is Fe.

[0017]

According to the composition of the magnetic thin film described above, the addition of C and O increases the hardness and the electrical specific resistance of the magnetic thin film and reduces the stress during film formation. However, although the magnetic permeability deteriorates,
It can be improved by the addition of Group IVa or Group Va elements. Further, the magnetic anisotropy can be controlled by the addition amount of these. Furthermore, by adding Ru, the corrosion resistance and wear resistance can be further improved.

Further, according to the sputtering in the atmosphere in which the CO2 gas is introduced, the added amounts of C and O can be adjusted by the flow rate ratio between the CO2 gas and the gas in another atmosphere.

[0019]

EXAMPLE The present inventor solves the above-mentioned problems by
As a result of earnest studies, C, O was added to the alloy of the magnetic thin film containing Fe, Al, Si as the main components, and IVa group or V group was added.
By adding at least one of Ti, Zr, Hf, V, Nb, and Ta of the group a element, hardness, permeability, and corrosion resistance can be improved without lowering the saturation magnetic flux density, and the stress during film formation is also reduced. I knew I could do it. In addition, Ru
It was also found that the corrosion resistance and the wear resistance can be further improved by adding. Hereinafter, an example in which the film is formed will be described with reference to the drawings.

First, FIG. 1 shows a sputtering apparatus used for forming the magnetic thin film of the embodiment. This apparatus forms a film by a facing target type sputtering method. In this sputtering apparatus, a pair of targets 1 are arranged to face each other in a vacuum chamber 2, and a negative potential is applied to each of them by a DC power source 6. And
The gas in the sputtering atmosphere introduced into the vacuum in the vacuum chamber 2 via the mass flow meter 5 is ionized, accelerated by a negative electric field and collided with the target 1, thereby sputtering the target 1. At that time, the plasma of gas ions in the sputtering atmosphere is focused by the magnetic field H generated by the magnet 9 arranged on the back side of the target 1. As a result, the magnetic thin film can be efficiently and rapidly formed on the substrate 4 of the sample held on the rotating substrate holder 3. In FIG. 1, 7 is a shield plate and 8 is an insulating and vacuum seal portion.

The magnetic thin film of the example was formed with such a sputtering apparatus. Here, as the target 1, Fe72.
An alloy target composed of 22 atomic%, Al 10.68 atomic% and Si 17.10 atomic% was used. Further, as a gas for the sputtering atmosphere, CO2 gas was introduced into pure Ar gas, and the addition amounts of C and O were adjusted by the flow rate ratio between the two. Further, by placing a metal tip (5 × 5 × 1 mmt) of any one of Ti, Zr, Ta, etc. of the IVa group to the Va group elements on the target 1, the above elements are added,
The composition was adjusted. The film thickness is 5 μm, and the heat treatment is 5
It was carried out at 50 ° C. for 25 minutes in nitrogen.

The process of selecting the composition of the magnetic thin film of the embodiment will be described below.

First, regarding C and O, the amount of CO2 gas added to the sputtering atmosphere (flow rate ratio with Ar gas)
2 to 4 show the relationship among the hardness of the magnetic thin film to be formed (Knoop hardness), the stress during film formation, the electrical resistivity, and the magnetic permeability. As can be seen from these figures, the addition of C and O increases the hardness, increases the electrical resistivity, and the stress during film formation acts on the compression side (minus). The stress is smaller than that in the case of adding nitrogen and oxygen of the conventional example described above and is about 1/4.
Is. On the other hand, the magnetic permeability decreases due to the addition of C and O.

By the way, when O2 is added, the hardness and electric resistivity increase to some extent as in the case of adding C and O, but the stress is large on the compression side (minus) like N2, and when the flow rate ratio is 3%, -8. It was 0 × 10 ⁹ dyn / cm ² .

The relationship between the flow rate ratio of CO2 and the amounts of C and O contained in the magnetic thin film is as shown in FIG.

Here, considering a digital VTR or the like,
The frequency band used becomes 20 to 30 MHz, and in order to secure the magnetic permeability at such a high frequency, it is necessary to reduce the loss due to the eddy current. And 30M for a film thickness of 5 μm
Electrical resistivity 100μΩ without eddy current loss up to Hz
The amount of C and O added to be cm is required to be at least 2.3 atomic% of C and 0.6 atomic% or more of O.

However, the addition of C and O deteriorates the magnetic permeability. Therefore, T which is an IVa group or Va group element
When at least one of i, Zr, Hf, V, Nb and Ta was added to the magnetic thin film, the magnetic permeability characteristics were improved as shown in FIGS. 6 and 7. In addition, in FIG. 6, the amount of CO2 added is 3
The relationship between the number of Ti, Zr, and Ta chips placed on the target and the magnetic permeability is shown when%. FIG. 7 shows the relationship between the amount of Ti added and the magnetic permeability, and shows the relationship when the amount of CO2 added is 3% and 6% and when Ru is further added.

From the results of X-ray diffraction, it is considered that Fe3C and FeO are produced and the magnetic domain walls are caught and the rotation of the magnetic domains is hindered by the fact that the magnetic permeability decreases when C and O are added at the same time. On the other hand, when an element such as IVa group or Va group that easily bonds with C or O is added, the peak corresponding to Fe3C or FeO disappears as a result of X-ray diffraction, and this seems to improve the characteristics. .

The change in crystal grain size due to X-ray diffraction becomes finer by adding C and O to Fe, Al and Si, and tends to become finer by adding IVa group and Va group. However, the grain size is larger than the bond length of the magnetic moment (about 400 Å), and has a crystal structure different from that of microcrystals (about 100 Å) which has been actively performed in recent years. It is said that an excess of C and a transition metal is added to Fe in the so-called microcrystals, and a compound of the transition metal and C is present around the grain boundary of Fe (αFe) to suppress the grain growth of Fe. There is something. This refinement reduces the apparent crystal magnetic anisotropy and obtains soft magnetic characteristics. But,
If αFe appears on the surface, it easily rusts and is insufficient in terms of corrosion resistance. On the other hand, the magnetic thin film of the present invention is composed of Fe, Si,
C, O, transition metal (group IVa, Va)
Group) is added, which is different from the above microcrystalline film.

As described above, the addition of C and O increases the hardness and the electrical resistivity, but when C is 0.5 atom% or less and O is 0.2 atom% or less, the effect is obtained. Not seen, and when C exceeds 8 atom% and O exceeds 6 atom%, the magnetic permeability lowers.

Regarding the IVa group and Va group elements, if the added amount is less than 0.1 atom%, the above-mentioned magnetic permeability is not improved, and if it exceeds 5 atom%, the magnetic permeability deteriorates.

Regarding the contents of Al and Si, A
If 1 is larger or smaller than the range of 8 to 12 atomic% and Si is 14 to 18 atomic%, the characteristics are deteriorated.

From these facts, the content and addition amount of each element are as follows: Al is 8 to 12 atomic%, Si is 14 to 18 atomic%, C is 0.5 to 8 atomic%, and O is 0.2 to. 6 atom%, IV
The elements of group a to Va are 0.1 to 5 atomic%, and the rest is Fe.

When Ru is further added, the effect of improving the corrosion resistance is not obtained if the added amount is 0.1 atomic% or less, and the soft magnetic characteristics are deteriorated if the added amount exceeds 3 atomic%. The amount is 0.1 to 3 atom%. In this case, without changing the range of the addition amount of elements other than Fe,
Fe is reduced by the amount of Ru added.

14 kinds of magnetic thin film samples of the examples were formed by changing the composition ratio of each element within the composition ratio range determined as described above. Further, as a comparative example (conventional example), Fe,
A magnetic thin film in which only N was added to Al and Si and a magnetic thin film in which only O was added were formed.

The composition of each sample was analyzed, and the magnetic permeability μ and coercive force H at 100 KHz and 6 MHz were measured.
c, saturation magnetic flux density Bs, film thickness, stress during film formation, Knoop hardness, and electrical resistivity were measured, and a corrosion resistance test was conducted.
The composition of the thin film was measured by EPMA (X-ray microanalyzer method). The magnetic permeability μ was measured by the ferrite yoke method. The saturation magnetic flux density Bs was measured by a VSM (sample vibration type magnetometer) by applying a magnetic field of 15 K Oersted, and the coercive force Hc was also measured by the VSM. The Knoop hardness was measured by applying a weight of 25 g for 15 seconds. In addition, the corrosion resistance was evaluated by coating the thin film with 1N HCl aqueous solution.
It was immersed for a period of time and the residual ratio of the saturation magnetic flux density Bs before and after the immersion was shown. The respective measurement results are shown in Tables 1 and 2 below.
The results of the corrosion resistance test are shown in FIG.

[0037]

[Table 1]

[0038]

[Table 2]

As can be seen from Tables 1 and 2, the stress during film formation was -8.3 to -10.5 × 10 ⁹ d for the sample of Comparative Example.
yn / cm ² is large on the compression side, whereas the sample of this example is remarkably small, −1.0 to −2.4 × 10 ⁹ dyn / cm ² .

The hardness and the electrical resistivity are almost the same in the comparative example and this example.

Regarding the magnetic permeability, in the comparative example, only those having a high magnetic permeability in the circumferential direction and a low magnetic permeability in the radial direction were obtained. On the other hand, in this example, as shown in Samples 1 and 2, the direction in which the magnetic permeability increases can be controlled by the composition. As described above, in the case of adding nitrogen in the conventional example, the magnetic permeability in the circumferential direction is inevitably increased when adding more than the amount that suppresses the corrosive wear due to the metal tape. The magnetic permeability in the circumferential direction and the radial direction can be increased by the amount of C and O that can be suppressed.

Further, a metal-in-gap type magnetic head was produced using the magnetic thin films of the respective samples, and the state of bubbles was examined. When the magnetic thin films shown in Comparative Examples 1 and 2 were used, the bonding glass Bubbles were generated in. On the other hand, the magnetic thin film of this example was almost absent. The possible causes are as follows.

Surface analysis of samples of Comparative Example 1 (containing nitrogen) and Example 1 (containing C, O, Ti) formed on a ferrite substrate heat-treated in nitrogen at 550 ° C. for 25 minutes was performed by Auger analysis. went. From this depth profile, it was found that when nitrogen was contained, the surface was easily oxidized and was easily bonded to oxygen. On the other hand, it was found that the sample formed in Example 1 had a passive film formed on the surface and was less likely to be oxidized than Comparative Example 1. Here, the bonded glass is
Upon contact with the film surface, the nitrogen-added film absorbs oxygen in the glass and the glass is easily reduced. When it is easily reduced, it is considered that oxygen in the glass is released, and this becomes bubbles, and in the case of the example, this is not the case, and bubbles are unlikely to occur.

As can be seen from FIG. 8, the corrosion resistance of this example is superior to that of the comparative example.

As described above, the magnetic thin film of this example has a remarkably smaller stress during film formation than that of the comparative example, the magnetic anisotropy can be controlled, and bubbles are not generated during glass bonding. It was also excellent in corrosion resistance.

By the way, in the above-mentioned embodiments, the addition of C and O to the magnetic thin film was carried out by introducing CO2 gas into the sputtering atmosphere. However, with the introduction of CO2 gas, a carbon chip is placed on the target. It is possible to increase the amount of C with respect to O in this way.

However, if the amount of C exceeds 8 atom% in the film content, the characteristics deteriorate. The cause of this is that when X-ray diffraction of this film is measured, a peak corresponding to Fe3C is seen, so that it is considered that the rotation of magnetic domains is hindered by the generation of cementite (Fe3C).

[0048]

As described above, according to the present invention,
In addition to adding C and O to the Fe, Al, and Si-based alloy thin film, Ti, Zr, Hf, V, and
By adding at least one of Nb and Ta, or by further adding Ru, the hardness is high, the electrical resistivity is large, the corrosion resistance is excellent, the stress during film formation is small, and the bubbles during glass bonding are formed. It is possible to provide an excellent magnetic thin film that does not occur at all and whose magnetic anisotropy can be controlled.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a sputtering apparatus used for forming a magnetic thin film according to an example of the present invention.

FIG. 2 CO2 gas addition amount in sputtering atmosphere (A
FIG. 6 is a diagram showing a relationship between a flow rate ratio to r gas) and hardness and stress of a magnetic thin film to be formed.

FIG. 3 is a diagram showing the relationship between the amount of CO 2 added and the electrical resistivity of the magnetic thin film.

FIG. 4 is a diagram showing the relationship between the amount of CO2 added and the magnetic permeability of the magnetic thin film.

FIG. 5: CO against Ar gas in a sputtering atmosphere
FIG. 3 is a diagram showing the relationship between the flow rate ratio of 2 gases and the contents of C and O in a magnetic thin film to be formed.

FIG. 6 shows how the magnetic properties are improved by the additive element of the magnetic thin film. Ti, Z when the amount of CO2 added is 3%
FIG. 6 is a diagram showing a relationship between the number of r and Ta chips placed on a target and magnetic permeability.

FIG. 7 is a diagram showing how magnetic properties are improved by adding Ti to a magnetic thin film, and is a diagram showing the relationship between the amount of Ti added and magnetic permeability.

FIG. 8 is a graph showing the results of a corrosion resistance test performed on magnetic thin films of Examples and Comparative Examples.

FIG. 9 is an explanatory diagram showing the state of warpage of the substrate due to the stress during the formation of the magnetic thin film.

FIG. 10 is a perspective view showing a ferrite block of a core material in which a track groove and a winding groove are processed in a magnetic head manufacturing process.

FIG. 11 is an explanatory view exaggeratingly showing a state where warped ferrite blocks are butted against each other.

FIG. 12 is an explanatory view showing the arrangement and direction of the substrate on the rotating substrate holder of the sputtering apparatus.

FIG. 13 is a diagram showing the relationship between the nitrogen content of the magnetic thin film and the magnetic permeability in the circumferential direction and radial direction of the substrate holder during film formation.

[Explanation of symbols]

 1 Target 2 Vacuum Chamber 3 Rotating Substrate Holder 4 Substrate 5 Mass Flow Meter 6 DC Power Supply 7 Shield Plate 8 Insulation and Vacuum Seal 9 Magnet

Claims (3)

[Claims] 1. A, b, c, d, e, and f are atomic% composition ratio values, and T is Ti or Z of a group IVa or Va group element.
At least one of r, Hf, V, Nb, and Ta is represented by the composition formula FeaAlbSicCdOeTf, and each value of a, b, c, d, e, and f is a + b + c + d + e + f = 100 8 ≤ b ≤ 12 14 ≤ c ≤ 18 0.5 ≤ d ≤ 8 0.2 ≤ e ≤ 6 0.1 ≤ f ≤ 5 A magnetic thin film comprising a soft magnetic alloy. 2. A, b, c, d, e, f, and g are atomic% composition ratio values, and T is Ti of the IVa group or Va group element.
At least one of Zr, Hf, V, Nb, and Ta is represented by a composition formula FeaAlbSicCdOeTfRug, and the respective values of a, b, c, d, e, f, and g are: , A + b + c + d + e + f + g = 100 8 ≦ b ≦ 12 14 ≦ c ≦ 18 0.5 ≦ d ≦ 8 0.2 ≦ e ≦ 6 0.1 ≦ f ≦ 5 0.1 ≦ g ≦ 3 Magnetic thin film characterized by. 3. A method for producing a magnetic thin film, which comprises depositing the magnetic thin film according to claim 1 by sputtering in an atmosphere in which CO 2 gas is introduced.