JP2752199B2 - Magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a magnetic head.

(Prior Art) Recently, as a magnetic film for a magnetic head in the future, research on an Fe-based alloy film having a high saturation magnetic flux density (Bs) of about 20 kG has been actively conducted. On the other hand, about 10% of CoFe alloy film
It shows the above high Bs. A CoFe alloy film containing a large amount of Co has an advantage of being superior in corrosion resistance as compared with an Fe-based alloy film. In addition to high Bs, the magnetic film for the head has a coercive force (Hc) and magnetostriction (λ
s) is required to be small, but it has been reported that a Co-10% Fe alloy film produced by plating exhibits low Hc and low λs comparable to Fe-based alloy films (IEEE Trans. Magn. , M
AG-23 (1987) 2981). Here, in the manufacturing process of various thin film patterns of the magnetic head, a dry process such as sputtering or vapor deposition is considered to be desirable in the future instead of the wet process of plating as in the semiconductor field. Furthermore, when performing recording and playback at a high transfer rate,
To reduce the eddy current, a magnetic film having a multilayer structure with an insulating layer (SiO ₂ or the like) interposed therebetween is desirable, but it is difficult to produce such a multilayer film by plating. Therefore, it is desirable that a CoFe alloy film of low Hc and low λs can be produced by sputtering or vapor deposition. In view of this point, as a result of our intensive research on the production of CoFe alloy films by sputtering, even CoFe alloy films that were not considered to exhibit low Hc (J. Ap
pl.Phys., 43 (1972) 3542), it has been shown that a CoFe alloy film having an Fe concentration of around 18% exhibits the same low Hc as the above-mentioned plating film. Summary 2pD-4). However, the λs of the Co-18% Fe alloy film is 1
It is a large value of × 10 ⁻⁵ or more, and it is desirable to reduce λs when applied to a magnetic head.

(Problems to be Solved by the Invention) As is apparent from the above description, although the CoFe alloy film has a high saturation magnetic flux density of about 20 kG, the sputtering method and the vapor deposition method require low Hc and low Hc required for the head magnetic polar film. At present, a magnetostrictive film cannot be produced. For this reason, high-density recording was not possible with a conventional magnetic head using a CoFe alloy film.

The present invention has been made in view of such problems, and has a high saturation magnetic flux density, low coercive force and low magnetostriction.
It is an object of the present invention to provide a magnetic head capable of performing high-density recording by using an alloy as a magnetic film.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a substrate, a magnetic film formed on the substrate,
In a magnetic head having a coil formed on the magnetic film via an insulating film, the main component of the magnetic film is Co.
Made of Fe, Fe concentration is 15at% or more and 24at% or less, (100)
Fcc (face-centered cubic lattice) with preferential growth in the direction perpendicular to the film surface
A magnetic head using a CoFe alloy containing the largest number of phases.

The above structure can be realized by sputtering in an atmosphere containing nitrogen (however, the amount of nitrogen mixed into the film is kept at less than 2 at%) or by sputtering on a magnesium oxide substrate.

(Function) The ferromagnetic film used in the present invention exhibits a high Bs of 19 kG,
Further, it shows low Hc of 2-3 Oe and low magnetostriction of 1 × 10 ^-6 . As a result, if such a CoFe alloy film is used as a magnetic film for a magnetic head, a magnetic head that is extremely advantageous for high-density recording and reproduction can be expected.

(Example) An example of the present invention will be described below in more detail with reference to the drawings.

The CoFe alloy film was formed on a glass substrate (0211 substrate manufactured by Corning Incorporated) by two-pole RF sputtering in an atmosphere in which nitrogen gas was mixed with argon gas, using the nitrogen gas content and the Fe concentration as parameters. The target was a composite target in which a plurality of Fe chips were arranged on a Co disk. The Fe concentration was controlled by changing the ratio of the Fe chip to the Co plate. In order to impart uniaxial magnetic anisotropy in the film plane, an external magnetic field was applied in one direction in the film plane by a permanent magnet arranged near the substrate during film formation. The sputtering was performed under the following conditions.

High frequency power density: 5 W / cm ² Total sputtering gas pressure: 9 × 10 ^-3 Torr Nitrogen gas partial pressure: 0-1.35 × 10 ^-3 Torr Distance between electrodes: 40 mm Preliminary evacuation: 1 × 10 ^-6 Torr or less Fe for Co Concentration: 9.5-31 at% The film thickness was about 0.3 μm. The coercive force was measured by applying a maximum magnetic field of 250 Oe in the hard axis direction. The crystal structure was examined by the X-ray diffractometer method (using CuKα rays). The nitrogen concentration in the film was measured by steam distillation / Nessler absorption photometry.

Coercive force Hc in CoFe alloy film prepared under the above conditions
Was measured using the Fe concentration as a parameter, and the results shown in FIG. 1 were obtained.

When produced by sputtering in a pure argon gas atmosphere containing no nitrogen, only the 15-24 at% Fe film shows a low Hc of 5 Oe or less, and the film of 12 at% or less or 31 at% Fe concentration has a low Hc.
It showed a relatively high Hc of more than 10 Oe. On the other hand, when the sputtering was performed by adding nitrogen gas, the Fe concentration was 12 at%.
In the following films, although there was a nitrogen partial pressure in which Hc was lower than that of the pure argon sputtered film, relatively high Hc of 10 Oe or more was shown. However, in a film having an Fe concentration of 15 at% or more, when the nitrogen partial pressure increases to about 7.2-9 × 10 ^-4 Torr, H
c fell below 3 Oe. From the above results, it was found that the film with a Fe concentration of 15 at% or more has a low Hc
It turns out that a film can be produced.

Next, when the dependency of λs on the nitrogen partial pressure was examined for a film having a low Hc and an Fe concentration of 15 at% or more, the results shown in FIG. 2 were obtained. The film having an Fe concentration of 15 to 24 at% showed a high λs of 1 × 10 ⁻⁵ or more when produced by pure Ar sputtering, but when the film was produced at a nitrogen partial pressure near 3.8 × 10 ⁻⁴ Torr, Low λs of 3 × 10 ⁻⁶ or less was exhibited. In this range of nitrogen partial pressure showing a low λs, a high Bs of 19 kG was shown. On the other hand, λs of the film having the Fe concentration of 31 at% is still 3.8 × 10 ^-4 Tor
Although it became the minimum at the nitrogen partial pressure near r, its value was 1 × 1
0 was a great value of ^-5 or more.

From the above results, by setting the Fe concentration to 15 to 24 at%, and further performing sputtering by adding nitrogen gas,
It can be understood that a magnetic film having good Bs of 19 kG, low Hc and low λs and excellent soft magnetic properties can be obtained.

By the way, in Fe-based films, λs is known to depend on the crystal orientation. Then, in order to clarify the reason why the low λs was obtained at the Fe concentration of 15 to 24 at%, the crystal orientation was examined, and the following results were obtained.

FIG. 3 shows an example of an X-ray diffraction curve of a film produced by ordinary pure argon sputtering. For 9.5at% Fe film, bcc
No phase peak was observed, indicating a high intensity fcc phase (111) peak. This film is considered to be a film in which the (111) plane is preferentially grown in the direction perpendicular to the film surface, that is, a (111) oriented film. As the Fe concentration increased, the (111) peak intensity decreased, and the newly emerged bcc phase (110) peak intensity increased. In the case of the 31% Fe film, no peak of the fcc phase was recognized, and a high intensity bcc phase (110) peak was exhibited. This film is (110)
It is considered an alignment film. From the above results, in the ordinary argon gas sputtering, the fcc phase (111) oriented film or the bcc phase (1
10) It can be understood that an alignment film is obtained.

Next, FIG. 4 shows the dependence of the X-ray diffraction curve on the Fe concentration in the film formed at a nitrogen partial pressure of 3.8 × 10 ⁻⁴ Torr. The film having an Fe concentration of 24 at% or less exhibited a diffraction curve mainly composed of a high-intensity fcc phase (200) peak. On the other hand, the Fe concentration is 31at%
Although the fcc phase (200) peak was observed in the film of, the bc was similar to that produced by pure argon gas sputtering.
The c-phase (110) peak intensity exhibited the maximum diffraction curve. From the above results, it can be understood that the bcc phase (110) oriented film shows a high λs and the fcc phase (100) oriented film shows a low λs. Note that the half width of the rocking curve of the fcc phase (200) peak
FIG. 5 shows the relationship between the Fe concentrations. The half-width became minimum (about 6 °) in the film having the Fe concentration of 18 at%. That is, a film with the best (100) orientation was obtained with an 18 at% Fe film.

By the way, when the dependency of the X-ray diffraction curve on the nitrogen partial pressure of the 18 at% Fe film was examined in detail, the results shown in FIG. 6 were obtained. At a nitrogen partial pressure of 3.8 × 10 ⁻⁴ Torr or less, as the nitrogen partial pressure increases, the peak intensity of the fcc phase (200) increases, ie, (10
0) An improvement in the degree of orientation was observed. In this case, the decrease in λs was associated with an increase in the degree of (100) orientation. On the other hand, when the nitrogen partial pressure is increased to 5.2 × 10 ^-4 Torr or more, the fcc phase (100)
No change was observed in the peak intensity, and the (100) orientation was maintained. However, in this case, λs has increased and (10
0) No relation was found between the degree of orientation and λs. In order to clarify the reason, the results of examining the dependence of the lattice constant and the specific resistance on the nitrogen partial pressure are shown in FIGS. 7 and 8, respectively. Focusing on the lattice constant first, when the nitrogen partial pressure is increased, bc
Although the lattice constant of the c-phase tended to decrease slightly, the change was slight. On the other hand, the lattice constant of the fcc phase hardly changed even when the nitrogen partial pressure was increased to 3.8 × 10 ^-4 Torr, but when the nitrogen partial pressure was further increased to 5.2 × 10 ^-4 Torr or more, it increased to 0.361 nm or more. Increased. Next, paying attention to the specific resistance, when the nitrogen partial pressure was increased to 3.8 × 10 ⁻⁴ Torr, the specific resistance showed a value that was slightly different from that of the pure argon gas sputtered film, though slightly increased. However, when the nitrogen partial pressure was increased to 5.2 × 10 ⁻⁴ Torr or more, the specific resistance increased rapidly and showed a value of 40 μΩcm or more. here,
It is considered that the increase in the lattice constant and the specific resistance described above is due to nitrogen contamination in the film. Then, the result of measuring the nitrogen content in the film is shown in FIG. From this figure, 3.8 × 10 ^-4 Torr
At the following nitrogen partial pressure, the nitrogen concentration was less than 2 at%,
At a nitrogen partial pressure of 5.2 × 10 ⁻⁴ Torr or more, the nitrogen concentration was 2 at% or more. From the above results, it can be seen that low λs is not exhibited unless the nitrogen concentration in the film is controlled to less than 2 at%.

As described in detail above, by controlling the Fe concentration to 24 at% or less by sputtering with addition of nitrogen, it is difficult to fabricate by normal argon gas sputtering.
A c-phase (100) oriented film can be realized, and as a result, a low λs film can be obtained. Further, taking into account the composition for obtaining low Hc, the magnetic properties of low Hc and low λs, which are indispensable for application to a magnetic head, are considered to be fcc phase (100) oriented Co with Fe concentration of 15 to 24 at%.
Obtained with Fe film. Some examples of magnetic heads using this magnetic film are shown in FIG. FIG. 10 (a) shows a head corresponding to a longitudinal recording hard disk (cross-sectional view).
This head includes the above-described CoFe magnetic film 10-2 formed on the substrate 10-1, the coil 10-5 formed on the magnetic film 10-2 via the gap layer 10-3 and the insulating layer 10-4, Insulation layer 10-4
CoFe magnetic film fabricated on coil 10-5 via
10-6 and a protective film 10-7. Magnetic films 10-2 and 10-6
Since the saturation magnetic flux density of the CoFe magnetic film described above is higher than that of the conventional magnetic film (NiFe film, Co-based amorphous film, etc.) used in the above, sufficient recording is possible even on a high coercive force medium, As a result, high density recording becomes possible. On the other hand,
FIG. 10B shows an example of a head corresponding to perpendicular recording (cross-sectional view). This head has the above-described Co on the substrate 10-8.
A main magnetic pole 10-9 using a Fe magnetic film is formed, a coil 10-11 is formed thereon with an insulating layer 10-10 interposed, and a return pass magnetic layer is formed thereon further with an insulating layer 10-10 interposed. It has a structure in which a body 10-12 is formed and finally a protective film 10-13 is formed.
Since the saturation magnetic flux density of the CoFe magnetic film described above is higher than that of the conventional magnetic film (Co-based amorphous film, etc.) used for the main pole 10-9, the thickness of the main pole can be further reduced. As a result, high-density perpendicular magnetic recording with a high linear recording density becomes possible. A CoFe film was formed on the (100) plane of magnesium oxide using pure argon gas under the same sputtering conditions as in Example 1. As a result, similarly to Example 1, Bs
= 19 kG, Hc = 3Oe, λs = 1 × 10 ⁻⁶ , and a crystal structure in which the fcc phase (100) plane is oriented in the direction perpendicular to the film surface (the X-ray diffraction curve shows the fcc phase (200) reflection). Only shown). From these results, it is desirable to apply the present invention to a magnetic head by realizing a crystal structure in which the fcc phase (100) plane is oriented in the direction perpendicular to the film surface by not only the sputtering method using nitrogen addition but also other methods. It can be seen that high Bs, low Hc, and low λs are realized.

〔The invention's effect〕

As described in detail above, according to the present invention, it is possible to provide a magnetic head capable of high-density recording by using a ferromagnetic film having a high saturation magnetic flux density, a low coercive force and a low magnetostriction. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing the nitrogen partial pressure dependency of coercive force Hc using Fe concentration as a parameter. FIG. 2 is a diagram showing nitrogen partial pressure dependency of magnetostriction λs using Fe concentration as a parameter. Fig. 4 shows the dependence of the X-ray diffraction curve on the Fe concentration when pure argon gas was used. Fig. 4 shows the dependence of the X-ray diffraction curve on the Fe concentration when produced at a nitrogen partial pressure of 3.8 × 10 ^-4 Torr. FIG. 5 is a diagram showing the dependence of the half-width value of the rocking curve on the fcc phase (200) peak by the Fe concentration, and FIG.
FIG. 7 shows the nitrogen partial pressure dependency of the X-ray diffraction curve in the 18 at% film, FIG. 7 shows the nitrogen partial pressure dependency of the lattice constant in the Fe concentration 18 at% film, and FIG. FIG. 9 shows the nitrogen partial pressure dependence of the specific resistance of the 18 at% film.
FIG. 10 is a diagram showing the relationship between the nitrogen concentration in the film and the nitrogen partial pressure in a film having a concentration of 18 at%, and FIG. 10 is a diagram showing an embodiment of the present invention.

Claims (6)

(57) [Claims] A substrate, a magnetic film formed on the substrate,
In a magnetic head having a coil formed in the form of a magnetic film via an insulating film, the main component of the magnetic film is Co.
Fe and Fe concentration of 15at% or more and 24at% or less, (10
0) A magnetic head characterized in that a CoFe alloy containing the largest amount of the fcc phase whose surface is preferentially grown in the direction perpendicular to the film surface is used. 2. The magnetic head according to claim 1, wherein the CoFe alloy contains N. 3. The magnetic head according to claim 2, wherein the CoFe alloy contains less than 2 at% of N. 4. The magnetic head according to claim 1, wherein said CoFe alloy is formed on magnesium oxide. 5. The magnetic head according to claim 1, wherein said CoFe alloy includes a part of a bcc phase. 6. The magnetic head according to claim 5, wherein the bcc phase has a (110) plane in a direction perpendicular to the film surface.