JP2727274B2 - Soft magnetic thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film having a high saturation magnetic flux density and a high-frequency magnetic permeability and suitable for a core material of a magnetic head for high density recording and reproduction.

[0002]

BACKGROUND OF THE INVENTION For example, audio tape recorders and VTs
In magnetic recording / reproducing apparatuses such as R (video tape recorder), recording signals have been increased in density and quality, and in response to this increase in recording density, Fe has been added to magnetic powder as a magnetic recording medium. So-called metal tapes using powders of metals or alloys such as Co, Ni, etc., and so-called vapor-deposited tapes in which a ferromagnetic metal material is directly applied on a base film by a vacuum thin film forming technique have been developed. Has been put to practical use.

[0003]

2. Description of the Related Art In order to exhibit the characteristics of a magnetic recording medium having such a predetermined coercive force, the core material of a magnetic head must have a high saturation magnetic flux density and the same magnetic head. In the case of performing reproduction, it is required to have a high magnetic permeability as well.

Recently, it has been reported that FeBZr and an alloy to which Cu is added exhibit high saturation magnetic flux density and high magnetic permeability in a ribbon-shaped sample (Summary of the General Lecture Meeting of the Japan Institute of Metals, Autumn Meeting (1990)). (107th meeting) pp. 419 and 420).

[0005] It is reported that a FeBZr alloy ribbon-shaped sample is obtained by melting a raw material having a predetermined composition into an arc shape, forming it into a ribbon shape by a single roll quenching method, and heat-treating it under a certain condition.

The FeBZrCu alloy ribbon-shaped sample is made of Fe
It is manufactured in the same manner as the BZr alloy ribbon-shaped sample, and it is reported that the presence of Cu improves the soft magnetic properties and expands the composition region where a high magnetic permeability can be obtained.

[0007]

The permeability in the summary of the lecture is measured on a ribbon-shaped sample, and is considered to be a value at low frequency or direct current. In the ribbon shape, the eddy current loss is large and the high-frequency magnetic permeability is considered to be a small value in principle.

By the way, even if a thin film having the composition described in the above-mentioned lecture summary is formed on a substrate by using a thin film forming means such as sputtering vapor deposition, and the thin film is subjected to a predetermined heat treatment, the thin film after the heat treatment remains No excellent soft magnetism was shown.

An object of the present invention is to provide a soft magnetic thin film which has solved the above-mentioned problems of the prior art. More specifically, it is an object of the present invention to provide a soft magnetic thin film having a high saturation magnetic flux density and a high-frequency magnetic permeability and suitable for a core material of a magnetic head for high-density recording and reproduction.

[0010]

According to a first aspect of the present invention, the above object can be achieved by the following soft magnetic thin film.

[0011] _{Fe a X b Zr c B d} ( where, a, b,
c and d each represent atomic%, and X represents Co, Ni, Cr, V
Of indicated at least representative of one) a composition formula, the composition range, 86 ≦ a + b ≦ 93 0 <b ≦ 10 4 ≦ c ≦ 9 1 ≦ d ≦ 8 range der of is, the coercive force Hc ≦ 6 Oe, Saturation magnetic flux density Bs
≧ 17 kG, and after a temperature history of 500 ° C.
However, the coercive force Hc and the saturation magnetic flux density Bs are still maintained.
THIS that soft magnetic thin film (corresponding to claim 1).

B is preferably 0.5 or more.

Incidentally, Fe is iron, Zr is zirconium, and B is
Represents boron, Co represents cobalt, Ni represents nickel, Cr represents chromium, and V represents vanadium.

According to a second aspect of the present invention, Fe _a Z _f N
i _e Zr _c B _d (where, a, f, e, c , d each atomic%
And Z represents at least one of Co, Cr and V)
The composition range is as follows: 86 ≦ a + e + f ≦ 93, 0 ≦ f ≦ 10, 0 <e ≦ 20, e + f ≦ 20, 4 ≦ c ≦ 9, 1 ≦ d ≦ 8. The above object is achieved by the soft magnetic thin film described above.

[0015]

Preferred Embodiments and Functions (First Aspect) In addition to Fe, Zr and B, the soft magnetic thin film of the present invention can be made of Co, Ni, C
Since at least one of r and V exists in the above specific composition range, good soft magnetic properties are exhibited even when formed by a thin film forming means by a vapor deposition method such as sputtering deposition. In particular, the coercive force is small.

If the composition is out of the above-mentioned specific composition range, the coercive force is often large, and good soft magnetic properties are not exhibited.

It is preferable that at least one of Co, Ni, Cr, and V is present in an amount of 0.5 atomic% or more, because the effect of its existence becomes clearer. A preferred composition range of the soft magnetic thin film of the present invention is a coercive force in the easy axis direction of 5.5 [Oe] or less, and a more preferred composition range is a coercive force of 3 [Oe] or less, and more preferably 2 [Oe]. O
e] or less, and particularly preferably 1.5 [Oe] or less (see FIG. 2).

The soft magnetic thin film of the present invention can contain a small amount of Cu.

The soft magnetic thin film of the present invention is formed, for example, by forming a thin film of the above-mentioned specific composition by a vapor deposition method such as an RF sputtering method, and heat-treating the thin film at, for example, 500 to 600 ° C. for about one hour (necessary) Heat treatment in a magnetic field).

(Second viewpoint) According to the second viewpoint, the first viewpoint
The presence of Ni in the X component in the viewpoint of
Ni can be present up to 20 at%. (E + f) corresponds to (b) of the first viewpoint. Actions from the first viewpoint-
Except for special changes due to the presence of Ni, the effect may generally be valid for the second viewpoint unless otherwise specified.

The special composition range based on the second viewpoint provides sufficient soft magnetic properties in a desired high-frequency range. That is, Ni
, The coercive force Hc becomes a low value of 2 Oe or less,
Stabilizes over a wide range of i amount. Thus, Ni is preferably contained at least 0.5 at%, more preferably at least 1.5 at%. Also, the presence of Ni greatly improves the corrosion resistance.

[0022]

[Example] (First viewpoint)

Embodiments 1 to 3 A Zr chip and a Co chip are appropriately arranged on a Fe ₉₅ B ₅ (at%) target, and the pressure is set to 2.
Three types of FeCoZrB thin films having a thickness of about 1 μm were formed on a sapphire substrate by an RF sputtering method under an Ar gas atmosphere of 0 [Pa] and a cathode power of 200 [W]. These thin films were heated at 550 ° C. in a magnetic field of about 1 [kOe] for 1 hour.
Heat treatment was performed for a time to obtain a soft magnetic thin film.

Table 1 shows the composition of the obtained soft magnetic thin film, the coercive force in the easy axis direction, and the positive / negative judgment of magnetostriction. The coercive force was measured using a BH tracer of 50 [Hz] with a measurement magnetic field of 25 [Oe] (the coercive force of the following Examples and Reference Examples was also measured in the same manner). The test was performed by changing the BH characteristics when stress was applied to the soft magnetic thin film. The magnetostriction is a measured value in the in-plane direction of the film, and it is considered that the magnetostriction in the in-plane is uniform.

[0024]

[Reference Example 1] Except that the Co chip was not provided.
3, a FeZrB thin film was formed. This thin film was heat-treated in the same manner as in Examples 1 to 3. Table 1 shows the composition of the thin film after heat treatment, the coercive force in the easy axis direction, and the positive / negative judgment of magnetostriction. Positive / negative determination of magnetostriction was performed in the same manner as in Examples 1-3.

[0025]

[Table 1]

[0026]

Embodiments 4 to 12 In the same manner as in Embodiments 1 to 3 except that four Co chips of 5 mm × 5 mm were arranged on targets of various compositions of FeZrB ternary system, FeC of various compositions was used.
An oZrB thin film was formed. These thin films were prepared in Examples 1 to 3.
In the same manner as in the above, a soft magnetic thin film was obtained.

Table 2 shows the composition and coercive force in the easy axis direction of the obtained soft magnetic thin film. In Example 5, the saturation magnetic flux density Bs was 17.6 kG.

[0028]

[Table 2]

[0029]

Reference Examples 2 to 13 FeZrB thin films of various compositions were formed in the same manner as in Examples 4 to 12, except that no Co chip was provided. These thin films were heat-treated in the same manner as in Examples 1 to 3. Table 3 shows the composition of the thin film after the heat treatment and the coercive force in the easy axis direction.

[0030]

[Table 3]

[0031]

Embodiments 13 to 15 Three kinds of FeXZrB thin films (where X is Cr, Ni, etc.) in the same manner as in Embodiments 4 to 12 except that Cr chips, Ni chips or V chips are provided instead of Co chips, respectively. Or V.). Heat treatment of these thin films as in Examples 1 to 3,
A soft magnetic thin film was obtained.

Table 4 shows the composition and the coercive force in the easy axis direction of the obtained soft magnetic thin film.

[0033]

Reference Example 14 FeMnZrB was prepared in the same manner as in Examples 4 to 12 except that a Mn chip was used instead of a Co chip.
A thin film was formed. This thin film was heat-treated in the same manner as in Examples 1 to 3. Table 4 shows the composition of the thin film after the heat treatment and the coercive force in the easy axis direction.

[0034]

[Table 4]

Tables 1 to 4 show that Co, Cr, Ni and V are particularly selected elements.

[0036]

Embodiment 16 A glazed polished alumina substrate having a diameter of 2 inches was used in place of the sapphire substrate, and the film formation time was increased by the RF sputtering method.
A 1.8 μm thick FeCoZrB thin film was formed. This thin film was heat-treated in the same manner as in Examples 1 to 3 to obtain a soft magnetic thin film.

The magnetic permeability of the obtained soft magnetic thin film in the hard axis direction with respect to the frequency was measured. The result is shown in FIG. μ ′ and μ ″ indicate a real part and an imaginary part, respectively.

[0038]

[Distribution of Coercive Force] Based on the data of Example 2 and Examples 4 to 12, the distribution of coercive force in the easy axis direction was calculated as Fe + C
FIG. 2 shows a pseudo ternary system of o, Zr, and B.

[0039]

[X-ray Diffraction] An X-ray diffraction diagram of the FeCoZrB thin film before heat treatment formed in the same manner as in Example 5 is shown in FIG. An X-ray diffraction diagram of a soft magnetic thin film obtained by heat-treating this thin film in the same manner as in Examples 1 to 3 is shown in FIG. Further, the heat-treated FeZr formed in the same manner as in Reference Example 6.
The X-ray diffraction diagram of the B thin film is shown in FIG. The X-ray used was a Kα ray of Cu.

FIGS. 3A and 3B show that what was amorphous immediately after the film formation was considerably crystallized (α-Fe (bcc) structure) by the heat treatment. 3 (b) and 3 (c) are almost the same pattern, but when viewed carefully, the peak showing the (110) plane is slightly shifted to the left from (c) in (b). It can be seen that the lattice spacing of the (110) plane in (b) is slightly larger than in (c). Note that this tendency is observed for X = Co and Ni, but Cr and V show a tendency to shrink conversely.

For bulk materials (conventional ribbon samples)
FeBZr ternary system (or Cu added)
Although a thin film material (for example, a thin film formed by a vapor deposition method such as a sputtering method) despite exhibiting soft magnetism, a quaternary system in which X (= Co, Ni, Cr, V) is added thereto (or Excellent soft magnetism is not shown unless Cu is used (quinary system). Although this mechanism is not clear, it is presumed as follows.

First, there is a possibility that the magnetostriction is different from that of the bulk material due to the orientation characteristic of the thin film (it is considered to be mainly oriented in the (110) plane direction from FIG. 3).

Next, even if the magnetostriction is not so different from that of the bulk material, a thin film is generally formed on a substrate and is often bound by it, and is easily affected by elastic energy. There is a possibility that it is necessary to bring the value closer to zero without indicating the value, but this is also possible in the present invention. The above estimation is possible.

According to the embodiment described above, the following preferred embodiments are shown. That is, the magnetostriction is a low value, and can be set to near zero (Table 1). The coercive force is a moderate value indicating soft magnetism and can be selected as desired from (1) 3 Oe or less, (2) 2.0 Oe or less, or (3) 1.5 Oe or less (see FIG. 2). The values of the coercive force of (1) to (3) include the following (i)
(Iii) correspond to the composition ranges shown in FIG.

(I) Hc ≦ 3Oe 86.5 ≦ a + b ≦ 92.5 0.5 ≦ b ≦ 6.6 0.5 ≦ c ≦ 8.6 1 ≦ d ≦ 7.7

(Ii) Hc ≦ 2Oe 87.5 ≦ a + b ≦ 91.6 1.5 ≦ b ≦ 6.6 5 ≦ c ≦ 8 1.5 ≦ d ≦ 6.8

(Iii) Hc ≦ 1.5 Oe 89 ≦ a + b ≦ 91.3 2.5 ≦ b ≦ 6.6 5.3 ≦ c ≦ 72 ≦ d ≦ 5.4

(Second viewpoint)

Embodiments 17 to 20 and Reference Example 15 In the same manner as in the embodiment and reference example from the first viewpoint described above, except that the alloy of each composition is used as a target instead of the chip of each element.
Samples were prepared by changing the value of e (Ni) from 0 to 20 or more according to the composition of the following formula. (91-e)% Fe-e% Ni-6% Zr-3% B (a
Table 5 shows the results.

Incidentally, if Ni exceeds 20 at%, the saturation magnetic flux density Bs decreases, which is not preferable. Example 20
Shows less than 10% Bs reduction compared to lower Ni.

[0050]

[Table 5]

(Summary of Preferred Embodiments) The first aspect includes the following embodiments. (1) b ≧ 0.5 (Effect of X content becomes clearer) (2) Coercive force Hc ≦ 6Oe, saturation magnetic flux density Bs ≧ 17k
G (3) Coercive force Hc ≦ 3 Oe (corresponding to the aforementioned composition range (i)) (4) Coercive force Hc ≦ 2 Oe (corresponding to the aforementioned composition range (ii)) (5) Coercive force Hc ≦ 1.5 Oe (described above) (6) Those having a magnetic permeability of 6000 or more in a high frequency range of 1 to 10 kHz. (7) Fe-Zr-B having fine crystallites oriented in the direction of the (110) plane. The lattice spacing of the (110) plane is larger than that of the system (X = Cr, Ni)

From the second viewpoint, there are the following modes. (8) Coercive force Hc ≦ 2Oe and Bs ≧ 17 kG, (9) (e + f) ≧ 0.5 (10) Same as (7) above (because X = Ni is essential)

[0053]

According to the first aspect (claim 1), the soft magnetic thin film of the present invention can be formed of Co, N, in addition to Fe, Zr and B.
Since at least one of i, Cr and V exists in the above-mentioned specific composition range, good soft magnetic properties are exhibited even when formed by a thin film forming means by a vapor deposition method such as sputtering deposition. That is, the soft magnetic thin film of the present invention has a saturation magnetic flux density of at least about 17 (kG), a coercive force of 6 (Oe) or less, and has a high magnetic permeability.

According to the second aspect of the present invention (Claim 2), the presence of Ni makes the coercive force low and stable over a wide range of Ni content (preferably 2 Oe or less). It also shows a degree of effect. Note that Ni also increases corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a frequency characteristic of magnetic permeability in a hard axis direction of an example of a soft magnetic thin film of the present invention.

FIG. 2 is a diagram showing a distribution of coercive force in an easy axis direction of a soft magnetic thin film according to an example of the present invention as a pseudo ternary system of Fe + Co, Zr, and B.

FIG. 3 is three types of X-ray diffraction diagrams.

Claims (2)

(57) [Claims] 1. A _{Fe a X b Zr c B d} ( where, a, b,
c and d each represent atomic%, and X represents Co, Ni, Cr, V
Of indicated at least representative of one) a composition formula, the composition range, 86 ≦ a + b ≦ 93 0 <b ≦ 10 4 ≦ c ≦ 9 1 ≦ d ≦ 8 range der of is, the coercive force Hc ≦ 6 Oe, Saturation magnetic flux density Bs
≧ 17 kG, and after a temperature history of 500 ° C.
However, the coercive force Hc and the saturation magnetic flux density Bs are still maintained.
THIS soft magnetic thin film characterized Rukoto. Wherein _{Fe a Z f Ni e Zr c} B d ( where, a, f,
e, c, and d each represent atomic%, and Z represents at least one of Co, Cr, and V), and the composition ranges are 86 ≦ a + e + f ≦ 93, 0 ≦ f ≦ 10, 0 <E ≦ 20, e + f ≦ 20, 4 ≦ c ≦ 9, 1 ≦ d ≦ 8.