JPH0465102A - Ferromagnetic film and manufacture thereof, and magnetic head - Google Patents

Abstract

PURPOSE:To obtain a high performance magnetic head using a ferromagnetic film which is expressed by a particular formula and partially shows a crystal structure consisting of fcc phase. CONSTITUTION:As a ferromagnetic film, a film of crystal property expressed by the formula, (CoxFeyTz)aNb is used. Where, T is at least a kind of atom selected from a group consisting of Al, B, Si, Ga, Ge; x, y, z respectively indicate atom% and 66<x<94, 5<y<=24, 1<z<10, x+y+z=100; a, b are respectively atom% and 85<a<99, 1<b<15, a+b=100. Moreover, at least a part of this film is a crystal structure consisting of fcc phase. The ferromagnetic film having the composition explained above can be obtained by executing the reactive sputtering (nitrogen added sputtering) for a metal forming CoFeT system alloy in the mixed gas ambience of argon and nitrogen and a partial pressure of N2 is controlled. When the heat processing is carried out after forming a film, a soft magnetic characteristic can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a ferromagnetic film, a method for manufacturing the same, and a magnetic head using this ferromagnetic film.

(Prior art) Future magnetic films for magnetic heads will have high saturation magnetic flux density Bs and soft magnetic properties (low coercive force Hc and low magnetic distortion λ
S) is required.

Conventionally, known crystalline magnetic films exhibiting good soft magnetic properties include NiFe alloy films and Sendust (FeAIJSi) alloy films.

However, the Bs of these magnetic films is 15 kG at maximum. Furthermore, many Fe-based or Co-based alloys exhibit low Hc when made amorphous. However, the maximum Bs of the amorphous alloy film is 15 kG.

In contrast, the present inventor has focused on a CoFe-based alloy that exhibits a high Bs of 19 kG or more over a wide composition range, and has been conducting research on making this film soft magnetic. As a result, when the fcc phase (100) orientation is achieved by the nitrogen-added sputtering method, a relatively small He, + I
reported that a magnetic film with the following low magnetostriction could be obtained (J, Appl, Phys, 67(9)
), pp. 5120-5122 (1990)). Furthermore, it has been reported that a CoFe alloy having Hc similar to that described above and a magnetostriction of approximately 0 was obtained using the Metsuki method.

However, when considering application to magnetic heads, 10e is comparable to NiFe alloy film, Sendust film, and amorphous film.
It is desired to reduce He to the following level.

(Problems to be Solved by the Invention) An object of the present invention is to provide a ferromagnetic film that exhibits high Bs, low He, and low λS and is suitable for magnetic heads and the like.

(Means and effects for solving the problem) The ferromagnetic film of the present invention has at least one type of atom selected from the group of the general formula %, x, y,
z indicates atomic %, H< x < 94.5 <
ySz4.1<Z<10, x + y 10z -100
, a, b each indicate atomic %, 85 < a < 9
9.1<b<15, a+b-100) It is a crystalline ferromagnetic film expressed by the formula 9.1<b<15, a+b-100), and is characterized by exhibiting a crystal structure in which at least a portion thereof consists of a fee phase.

The method for producing a ferromagnetic film of the present invention includes sputtering a metal constituting an alloy represented by CoxFeyTz (where T, x, and ySz are as defined above) in a sputtering gas containing nitrogen. It is characterized by:

The magnetic head of the present invention is characterized by comprising the ferromagnetic film, a coil electromagnetically coupled to the ferromagnetic film, and a layer electrically insulating the ferromagnetic film and the coil. It is.

In the ferromagnetic film of the present invention, the content of Fe in the alloy
The reason for setting 5<ySz4 is as follows.

When Fe is 5 at% or less, Hc increases because the film contains an hcp phase. When Fe exceeds 24 at%, high Bs and low He can be obtained, but the bee phase is included in the film, so λS increases.

When Fe is 5 to 24 at%, RCC single phase or BCC and FEE phase with (IOD) plane oriented in the direction perpendicular to the film surface are formed.
The coexistence of two phases can be realized, and as a result, a low magnetostriction of 2×10−6 or less is exhibited. However, if Fe exceeds IBat%, the bee phase is likely to be generated, so for example, MgO
It is preferable to use a method such as providing a base layer such as the above to preferentially grow the fcc phase.

In the ferromagnetic film of the present invention, T in the alloy, that is, B, A
The reason why the content Z of at least one atom selected from the group consisting of O, Si, Ga, and Ge is set to 1<Z<10 is as follows.

When T becomes less than lat%, Hc increases. T is 10
When it exceeds at%, Bs decreases and He increases. T
is 1 to 1 oat%, high Bs of 15 to 19 kG
, and exhibits low He of less than 10e.

The reason why the nitrogen content relative to the alloy components in the ferromagnetic film of the present invention is set to l<b<15 is as follows. When N becomes less than fat%, the crystal grain size increases and He increases. When N exceeds 15 at%, the lattice constant increases and λS increases. When N is 1 to 15 at%, N is suppressed to less than 1.5 times T, and as a result, increase in lattice constant can be suppressed, and low Hc below foe,
A low λS of 2×10 −6 or less can be obtained.

The ferromagnetic film of the present invention having the composition described above exhibits heat resistance of 500° C. or higher.

The ferromagnetic film of the present invention can be manufactured by reactive sputtering (nitrogen-added sputtering) of the metal constituting the CoFeT-based alloy in a mixed gas atmosphere of argon and nitrogen. At this time, by controlling the N2 partial pressure in the atmosphere, a ferromagnetic film having the above-mentioned composition can be obtained. Furthermore, if necessary, by performing heat treatment after film formation, the soft magnetic properties can be improved.

In addition to this method, sputtering using a composite target of CoFe alloy and Al)N; method of irradiating the substrate with nitrogen ions during film formation by various types of sputtering or vapor deposition; etc. can be adopted. Note that in film formation by sputtering, the film naturally contains trace amounts of oxygen and argon.

The ferromagnetic film of the present invention can be used for thin film magnetic heads capable of longitudinal recording.
It can be applied to any thin film magnetic head that supports perpendicular recording. Since this ferromagnetic film has high Bs, low He, and low λS, high-density recording can be realized. Further, since the ferromagnetic film of the present invention has heat resistance of 500° C. or more, it can be applied to metal-in-gap heads that require a glass welding process.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Example] Using a Co-11,5at%Fe-4at%Ai1 alloy target, a glass substrate (0211 substrate manufactured by Corning Co., Ltd. ) film thickness 0, 3. A magnetic film was formed. Sputtering was performed under the following conditions.

High frequency current density, 5W/(2)2 Total sputtering gas pressure: I X 1O-2Torr Nitrogen gas partial pressure
: 0-2X 1O-3Torr distance between electrodes
:40■ Preliminary evacuation 21×1O-6 Torr The physical properties and magnetic properties of the obtained magnetic film were measured as follows. The coercive force is up to 2500e in the hard axis direction of the magnetic material.
Measurements were made by applying a magnetic field of The magnetostriction was determined from the relationship between the unidirectional stress applied to the substrate and the anisotropic magnetic field Hk. The crystal structure was investigated by the θ-2θ scan X-ray diffractometer method (using CuKa rays). The average crystal grain size is
It was determined from the half-width of the line diffraction curve. The nitrogen concentration in the film was investigated by steam distillation and Nessler spectrophotometry. C in the membrane
o5Fe5Aj) was determined by ICP emission spectrometry.

Magnetic properties of the magnetic film, namely coercive force HC1 saturation magnetization Bs
FIG. 1 shows the dependence of magnetostriction λS on nitrogen partial pressure. The following can be seen from Figure 1. A magnetic film formed in pure argon sputtering has a high BS but a high Hc, making it difficult to apply to a magnetic head. Even if the nitrogen partial pressure is increased, the Bs of the obtained magnetic film does not change much, and the high B
s is maintained. In addition, the nitrogen partial pressure is 0.1 to about 1 m
In the Torr range, Hc and λS of the magnetic film decrease as the nitrogen partial pressure increases. And the nitrogen partial pressure is 0.5~
The magnetic film obtained in the range of about 1 mTorr is 17 to 18
High Bs of kG, low Hc of about 1,50 e, +0.5 ~
It exhibits good soft magnetic properties with a low λS of 0.0, 7X 10-6. However, when the nitrogen partial pressure becomes about 1 mTorr or more, Hc and λS of the magnetic film tend to increase as the nitrogen partial pressure increases. For example, if the nitrogen partial pressure is 1.5m
In the case of Torr, a magnetic film with low Hc and low λS cannot be obtained.

The magnetic properties of the magnetic film depend on the composition of the magnetic film, as shown below.
It depends on the crystal layer, lattice constant, and average grain size.

FIG. 2 shows the relationship between the nitrogen partial pressure and the composition of the formed magnetic film. For comparison, the figure also shows the nitrogen concentration when a CoFe-based alloy film is formed by nitrogen-added sputtering. The following can be seen from Figure 1. As the nitrogen partial pressure increases, the nitrogen concentration increases monotonically. In the case of the CoFeAF alloy film according to the present invention, Co
The nitrogen concentration in the film is higher than that of the Fe-based alloy film. On the other hand, as the nitrogen partial pressure increases, the concentrations of Co and Fe decrease slightly. Furthermore, as the nitrogen partial pressure increases, the AΩ concentration increases slightly and then decreases. The reason for the change in composition as shown in FIG. 2 is thought to be as follows. Af! teeth,
Compared to Co and Fe, Al)N has a stronger bonding force with nitrogen, and as the nitrogen partial pressure increases, Al)N is formed. Since this A11N is difficult to be sputtered, re-sputtering of nitrogen and An) from the substrate is suppressed. It is thought that such a phenomenon occurs when the nitrogen partial pressure is in the range of 0.1 to about 0.7 mTorr. On the other hand, when the nitrogen partial pressure is about 0.7m Tor
When increasing above r, the Ajll concentration begins to decrease even though the nitrogen concentration increases. This means that the amount of nitrogen that does not combine with Al increases.

As a result, for example, when the nitrogen partial pressure is 1.5 m Torr, the nitrogen concentration in at% is 1.5 times the All concentration. The changes in the composition of the magnetic film as described above approximately correspond to the changes in the magnetic properties of the magnetic film shown in FIG.

Regarding the relationship between the crystal phase of a CoFe-based alloy film and λS, the following findings have been obtained (J.

Appl, Phys, 67(9), pp, 51
20-5122 (1990)).

That is, in a structure mainly exhibiting the bcc phase, the positive high λ
Indicates S. On the other hand, when nitrogen-added sputtering is performed at an appropriate nitrogen partial pressure, the fee phase in which the (100) plane is oriented perpendicular to the film surface is mixed into the bee phase, so that the λS of the magnetic film tends to decrease. However, when the nitrogen concentration in the film further increases and the lattice constant of the fee phase increases as a result, the fe phase
Even in the e-phase (100) oriented film, λS shows a large value.

Based on such knowledge, C o F according to the present invention
e The crystal structure and lattice constant of the All alloy film were also investigated. Nitrogen partial pressure and X-ray diffraction curve of magnetic film (θ
-1″ fixed 2θ scan method and θ-2θ scan method)
Figure 3 shows the results of investigating the relationship between Figure 4 shows the results of investigating the dependence of the lattice constant on nitrogen partial pressure.

The following can be seen from the results shown in Figure 3. In the pure argon sputtered film, unique diffraction peaks of the fee, hcp, and bee phases are detected, indicating a crystal structure in which these three phases coexist. As the nitrogen partial pressure increases, only diffraction peaks from the fee phase are detected. From this, it can be seen that the fee phase is stabilized by nitrogen-added sputtering, as in the case of the CoFe-based alloy film. In FIG. 2, the reason why a low λS was obtained when the nitrogen partial pressure was 0.5 to 1 m Torr is considered to be that the crystal structure of the magnetic film changed to a structure mainly consisting of the fee phase.

From the results shown in Figure 4, the following can be seen. That is, (
The lattice constant obtained from (200) reflection has a larger value than the lattice constant obtained from 111) reflection.

Larel believes that this is because nitrogen atoms are preferentially contained in crystal grains corresponding to (200) reflection.

In a relatively low nitrogen partial pressure range of about 1 mTorr, no significant change in the lattice constant is observed. In Figure 1, low H
e, the range in which low λS is obtained is within the range in which no significant change in the lattice constant is observed. However, as the nitrogen partial pressure increases above about 1 mTorr, the lattice constant increases. For example, the nitrogen partial pressure is 1.5 m Torr (second
As shown in the figure, nitrogen atoms are 1% of AΩ atoms at at%.
In the case of a magnetic film containing 5 times or more of the lattice constant, the lattice constant is extremely large.

In this range, Hc as shown in FIG.

λS is increasing. Therefore, the increase in λS at high nitrogen partial pressures can be attributed to the increase in the lattice constant.

FIG. 5 shows the nitrogen partial pressure dependence of the average grain size determined from the (111) and (200) peaks. For reference, the figure shows CoFe formed by nitrogen-added sputtering.
The results for the alloy film are also shown.

In the case of a CoFe-based alloy film, even if the nitrogen partial pressure increases,
The average grain size is reduced to only about 160 grains. On the other hand, in the case of a CoFeAfi alloy film, the average crystal grain size decreases to about 100 nm as the nitrogen partial pressure increases. The decrease in Hc as shown in FIG. 1 is thought to be due to the formation of fine crystal grains.

Low H formed at nitrogen partial pressure 0, 5-1 mTorr
e.

FIG. 6 shows the change in Hc when a fixed magnetic field is applied in the easy axis direction to a low λS magnetic film and the film is heat treated at a predetermined heat treatment temperature for 1 hour. As shown in FIG. 6, the Hc of the magnetic film according to the present invention is reduced by heat treatment at around 550°C.
It is reduced to below Oe. Since the magnetic film of the present invention has heat resistance even at 550° C., it can also be applied to heads that require a glass welding process (such as metal-in-gap heads).

Note that it has been confirmed that the characteristics described above are the same even in a magnetic film having a thickness of IJU or more.

Example 2 The same conditions as Example 1 were used, except that a composite target with an AI chip mounted on a CoFe alloy with a constant composition was used, and the concentration ratio of Co and Fe was almost fixed, and the l concentration and N concentration were different. A magnetic film was formed. Table 1 shows the characteristics of these magnetic films. In Table 1, Hc is the value after heat treatment at 550° C. for 1 hour after film formation, and the results are shown for a magnetic film obtained at a nitrogen partial pressure where He is the lowest.

Note that in both cases, as in Example 1, the N concentration and Ag concentration are approximately the same, expressed in at%.

The following can be seen from Table 1. All concentration is 1at%
When the temperature decreases to , He increases. On the other hand, when the Aj7 concentration is 1
When increasing to 0at%, Bs decreases to 14kG or less,
Conventional crystalline magnetic films (N i Fe films and FeAll5
It becomes impossible to achieve a high Bs higher than that of an amorphous film (such as an i-film) or an amorphous film. Moreover, He also increases.

By setting AN concentration 2 in the range of lat% < Z < 10at%, high Bs of 15k G or more, 10e
The following low Hc and low λS of 2 x 10-6 or less can be achieved.

Example 3 Under the same conditions as in Example 1, a magnetic film was formed in which the AII concentration was fixed and the Fe concentration was varied. The magnetic properties of these magnetic films are shown in Table 2, and the X-ray diffraction curves are shown in FIG. Also in Table 2, Hc is the value after heat treatment at 550° C. for 1 hour after film formation, and the results are shown for the magnetic film obtained at the nitrogen partial pressure where Hc is the lowest.

The following can be understood from these results. Fe concentration is 5a
t%, Hc becomes 30e as shown in Table 2.
As shown in FIG. 7, hcp phase (100) reflection is observed in the X-ray diffraction curve. Co hep
The phase is known to have large crystal anisotropy. From this, it is considered that the reason for the increase in Hc is that the film contains an hcp phase and the magnetocrystalline anisotropy increases.

On the other hand, when the Fe concentration increases to 168t%, as shown in Table 2, Bs increases, He decreases to 10e or less, but λS increases to 7×10−6. Moreover, as shown in FIG. 7, a clear ee phase (110) peak is observed in the X-ray diffraction curve. λS increases because
This is thought to be due to the bee phase being included in the film.

Example 4 After forming an MgO film (base layer) on a glass substrate by sputtering, a magnetic film was formed under the same conditions as in Example 1. In this case, even if the Fe concentration is increased compared to the magnetic film of Example 1, the λ
It was found that S could be maintained. The magnetic properties of these magnetic films are shown in Table 3, and the X-ray diffraction curves are shown in FIG. In Table 3 as well, Hc is the value after heat treatment at 550° C. for 1 hour after film formation, and the results are shown for the magnetic film obtained at the nitrogen partial pressure where He is the lowest.

As shown in Table 3, by using MgO as the underlayer, even if the Fe concentration increases to 24 at%, 2
A low λS of 0-6 or less can be obtained. As shown in FIG. 8, a high-intensity fcc phase (200) peak is observed in the X-ray diffraction curve. This indicates that the fcc phase (100) plane preferentially grows in the direction perpendicular to the film surface. It is known that in a CoFe-based alloy film, if the fee phase (100) plane preferentially grows in a direction perpendicular to the film surface, the magnetostriction decreases even if the film contains a bee phase. The magnetic film according to the present invention also contains a bcc phase in a composition region with a high Fe concentration, but if an underlayer of MgO is provided, a fee phase (1
It is considered that the 00) plane can be preferentially grown in the direction perpendicular to the film surface, and as a result, a low λS can be achieved.

Example 5 In the above examples, CoFeA and p-based alloys were explained, but even if AX) is replaced with B, Si, Ga5Ge1:W (conditions are the same as in Example), high BS, low He , low λS
It was discovered that a magnetic film of Table 4 shows some of the results. Also in Table 4, Hc is 550°C after film formation.
, which is the value after 1 hour of heat treatment, and shows the results for the magnetic film obtained at the nitrogen partial pressure where Hc is the lowest.

Next, examples of magnetic heads to which the magnetic film according to the present invention is applied will be described with reference to FIGS. 9 to 11.

FIG. 9 is a sectional view of a thin film magnetic head compatible with a longitudinal recording/1-mode disk. A ferromagnetic film 2 and a first insulating layer 4 are laminated on a substrate 1 so that a predetermined gap 3 is formed on the head tip side, a coil 5 is wound around this first insulating layer 4, and the coil 5 is further wound. A second insulating layer 6 is laminated to cover it. A ferromagnetic film 7 is formed on the surface of the insulating layer so that a part thereof is in contact with the ferromagnetic film 2, and a gap 3 is formed between the ferromagnetic film 2 and the ferromagnetic film 7 on the head tip side. A protective film 8 is formed on the ferromagnetic film 7.

The ferromagnetic film of the present invention has a higher saturation magnetic flux density than conventional ferromagnetic films (such as N i Fe films and Co-based amorphous films), so it is possible to perform sufficient recording even on high coercive force media. As a result, high-density recording becomes possible.

FIG. 10 is a cross-sectional view of a thin film magnetic disk compatible with perpendicular recording. A main pole 12 made of a ferromagnetic film according to the present invention and a first insulating layer 13 are sequentially laminated on a substrate 11.
A coil 14 is wound around the insulating layer 13, and a second insulating layer 15 is further laminated to cover the coil 14.

A return bus magnetic body 16 is formed on the surface of the insulating layer so that a portion thereof is in contact with the main magnetic pole 12. A protective film 17 is formed on the return path magnetic body 16.

The ferromagnetic film of the present invention used for the main pole 12 has a higher saturation magnetic flux density than conventional ferromagnetic films (such as Co-based amorphous films), so it is possible to further reduce the thickness of the main pole. As a result, high-density perpendicular magnetic recording with high linear recording density becomes possible.

FIG. 11 is a perspective view of the metal-in-gap head.

A ferromagnetic film 24.24 according to the present invention is formed on the opposing surfaces of the pair of ferrite cores 21.22, with an intermediate layer 23.23 interposed therebetween. The intermediate layer 23 is used to strengthen adhesion and prevent mutual diffusion between the ferrite core and the ferromagnetic film, and is made of Cr, 5 inch
2. NiFe etc. are suitable. These ferrite cores 21, 22 are welded with glass 26 so that a gap 25 is formed between the ferromagnetic films 24, 24.

A coil 27 is wound around the ferrite core 21.

When manufacturing such a head, a glass welding process is performed at a high temperature of 500°C or higher, and the ferromagnetic film of the present invention has heat resistance of 500°C or higher, so it can be applied to this head. .

[Effects of the Invention] As detailed above, the ferromagnetic film of the present invention maintains a high Bs of over 15 kG, a low Hc of less than toe, and a high Bs of over 15 kG.
It exhibits a low λS of less than X 10-6. As a result, by using the ferromagnetic film of the present invention, a magnetic head with excellent recording ability can be manufactured. Furthermore, the ferromagnetic film of the present invention has a
Since it has heat resistance of ℃ or more, it can be applied to a wide range of heads including heads that require a glass welding process.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the nitrogen partial pressure dependence of the magnetic properties of the ferromagnetic film according to the present invention, FIG. 2 is a diagram showing the nitrogen partial pressure dependence of the composition of the ferromagnetic film according to the present invention, and FIG. is a diagram showing the nitrogen partial pressure dependence of the X-ray diffraction curve of the ferromagnetic film according to the present invention, FIG. 4 is a diagram showing the nitrogen partial pressure dependence of the lattice constant of the ferromagnetic film according to the present invention, and FIG. FIG. 6 is a diagram showing the dependence of Hc on the heat treatment temperature of the ferromagnetic film according to the present invention. FIG. FIG. 8 is a diagram showing the Fe concentration dependence of the X-ray diffraction curve of the ferromagnetic film according to the invention. FIG. 9 is a cross-sectional view of a thin-film magnetic head capable of longitudinal recording using a ferromagnetic film according to the present invention, and FIG. 10 is a cross-sectional view of a thin-film magnetic head capable of perpendicular recording using a ferromagnetic film according to the present invention. FIG. 11 is a perspective view of a metal-in-gap head using a ferromagnetic film according to the present invention. 1...Substrate, 2...Ferromagnetic film, 3...Gap,
4... First insulating layer, 5... Coil, 6... Second insulating layer, 7... Ferromagnetic film, 8... Protective film, 11... Substrate, 12... Main magnetic pole, 13 ...first insulating layer, 14...
Coil, 15... Second insulating layer, 16... Return path magnetic material, 17... Protective film, 21.22... Ferrite core, 23... Intermediate layer, 24... Ferromagnetic film ,2
5...Gap, 26...Glass, 27...Coil. Applicant's representative Patent attorney Takehiko Suzue Nitrogen M foot (mTorr) Figure 1 0.1 1.0 Nitrogen partial pressure (mTorr) (A) Head 2θ Ge 4゜ Father (A) 2θ Ji) Go to Figure 1. 7 to the first contractor, y to the first contractor ↓ Figure 10

Claims (3)

[Claims] (1) General formula (CoxFeyTz)aNb (T is at least one atom selected from the group consisting of B, Al, Si, Ga, and Ge, x, y, and z each represent atomic %, and 66<x<94,5<y≦24,
1<z<10, x+y+z=100, a and b each indicate atomic %, 85<a<99, 1<b<15, a+b
=100) A ferromagnetic film characterized in that it is a crystalline ferromagnetic film represented by: (2) CoxFe in sputtering gas containing nitrogen
yTz (T, x, y, z are as defined above) The method for producing a ferromagnetic film according to claim 1, characterized in that the metal constituting the alloy represented by: yTz is sputtered. . (3) A ferromagnetic film according to claim (1), a coil electromagnetically coupled to the ferromagnetic film, and a layer electrically insulating the ferromagnetic film and the coil. magnetic head.