JP2722991B2 - Magnetoresistive head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head for reading information from a magnetic recording medium, and more particularly, to a magneto-resistive head characterized in that the information is read by a magneto-resistive (hereinafter referred to as MR) effect. About.

[0002]

2. Description of the Related Art A magnetic head using a magnetoresistance (MR) effect capable of reading information from a magnetic recording medium with high sensitivity has been limited in its practicality due to Barkhausen noise generated in an MR element. This noise is caused by a plurality of magnetic domains being generated in a portion (MR layer) of the MR element where the magnetoresistance effect is generated, and a random change occurs. A solution to this problem is described in U.S. Pat.
istive Head Transducer Having Patterned Longitudin
al Bias ”. This generates a one-way exchange coupling bias magnetic field by the antiferromagnetic film only in the end region of the MR layer, thereby turning the end region of the MR layer into a single magnetic domain. A single magnetic domain state is used to induce a single magnetic domain state in the central region where reading is performed.
Barkhausen noise disappears. Further, it has been pointed out that this Barkhausen noise is also generated by the instability of the magnetization state of a soft magnetic layer (transverse bias film) provided to improve the response performance of the MR layer from an external magnetic field. A solution to this problem is described in U.S. Pat. No. 4,713,708. This is intended to stabilize the magnetization of the soft magnetic layer by applying the one-way exchange coupling bias magnetic field by the antiferromagnetic film to the soft magnetic layer together with the MR layer.
In each of the above conventional examples, FeM is used as the antiferromagnetic film.
An n alloy film is used. An FeMn alloy film suitable for making the MR layer into a single magnetic domain is disclosed in US Pat.
No. 5, No. 4,782,413 and No. 5,014,147. In these, the composition, thickness and crystal phase of the FeMn film are specified.

[0003]

FIG. 2 is a sectional view of a conventional MR element. FIG. 2 (a) shows U.S. Pat.
This is an element configuration shown in US Pat. An exchange coupling bias magnetic field (Hex) is applied to the NiFe-based alloy film (MR film) indicated by 22 by the FeMn antiferromagnetic film indicated by 21, but the soft magnetic film indicated by 23 is a transverse bias film. Hex is not applied to the film, and Barkhausen noise is generated. FIG. 2 (b) shows a U.S. Pat.
No. 708. In this case F
Hex is applied to the soft magnetic film 23 by the eMn antiferromagnetic film 21 and Hex is applied to the MR film 22 as it is. However, Hex is applied when the soft magnetic film is made of an alloy containing NiFe as a main component, but Hex is zero when an amorphous soft magnetic film made of Co as a base material is used. A soft magnetic film containing Co as a base material has an extremely good soft magnetic characteristic and a high specific resistance of 150 μΩcm, and is therefore most suitable as a film for a lateral bias. However, in the element having the configuration shown in FIG. 2B, no bias can be applied to the Co-based amorphous film because Hex due to the FeMn film is essentially zero, and no Hex is applied to the MR film. As a result, an element having much Barkhausen noise is obtained. 2 (c) and 2 (d) show elements having a large amount of Barkhausen noise when a Co-based amorphous film is used for the lateral bias film for the same reason as in FIG. 2 (b). FIG.
(E) is an element configuration shown in U.S. Pat. No. 4,771,340. The configuration is such that noise from the soft magnetic film is prevented by shortening the soft magnetic film. However,
It is necessary to use a lift-off method in the device fabrication process,
The process is complicated. Further, the device is poor in film configuration, and the production yield and device reliability are low. Further, when the antiferromagnetic film 21 contains a large amount of Mn, the oxidation of the film is remarkable. Therefore, when there is a step of processing the antiferromagnetic film 21 by etching or the like during the process, the manufacturing yield is reduced. Therefore, the configuration of FIG. 2E lacks practicality. The process of processing the antiferromagnetic film 21 by etching or the like is shown in FIG.
2B, and are included in the element of FIG. 2C, and in these cases, the production yield is also reduced.

As described above, in the case of the conventional device configuration shown in FIG. 2, if an attempt is made to use a Co-based amorphous film having good soft magnetic characteristics and high resistance as the lateral bias film, the exchange by the antiferromagnetic film is required. A bias magnetic field cannot be applied, and Barkhausen noise of the element cannot be suppressed. Further, a conventional device having a low Barkhausen noise configuration has a low production yield and low device reliability. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a high MR resistance without a Barkhausen noise even when a Co-based amorphous film is used as a lateral bias film while maintaining the reliability and manufacturing yield of an MR element. It is an object to provide an effect type head.

[0005]

According to the present invention, there is provided a magnetoresistive head having a magnetoresistive film, a soft magnetic film for lateral bias and an antiferromagnetic film, wherein the soft magnetic film for lateral bias is C
o and M (M is Ti, V, Cr, Zr, Nb, Mo, H
f, Ta, Y, Ru, Rh, Pd, Cu, Ag, Au,
And at least one element selected from the group of pt)
Is an amorphous alloy whose main component is FeM
n alloy or FeMn with Ti, Cr, Ni, Zr, N
b, Mo, Ru, Rh, Hf, Ta, W, Re, Os
And at least one element selected from the group of Ir
An alloy added, wherein the crystal structure of the antiferromagnetic film is
Crystal structure including the face-centered cubic lattice
Characterized in that the ratio of occupying in the film changes in the direction of the film surface.
Between the soft magnetic film for lateral bias and the antiferromagnetic film.
Film containing Ni and Fe as main components, Ni film or Ni
It must have a structure in which a film as the main component is sandwiched in the thickness direction.
Or a magnetoresistive head or horizontal bar
The soft magnetic film for EAS is an alloy containing Ni and Fe as main components.
The antiferromagnetic film is made of FeMn alloy or FeMn
i, Cr, Ni, Zr, Nb, Mo, Ru, Rh, H
selected from the group of f, Ta, W, Re, Os and Ir
Alloy containing at least one element selected from the group consisting of
The crystal structure of the antiferromagnetic film includes a face-centered cubic lattice.
The proportion of the crystal structure consisting of the centered cubic lattice in the film is the film surface
Magnetoresistive head characterized by changing in direction
It is.

[0006]

Further, in the above invention, it is preferable that the antiferromagnetic film is a magnetoresistive head having a structure sandwiched between a magnetoresistive film and a soft magnetic film for lateral bias in the film thickness direction.

[0008]

Next, an embodiment of the present invention will be described. Embodiment 1 FIG. 1A shows an MR of a magnetoresistive head according to the present invention.
It is sectional drawing of one Example of an element part. An MR element having the structure shown in FIG. 1A was formed on an Al ₂ O ₃ —TiC-based ceramic substrate. The film was formed by sputtering various alloy targets by argon plasma using a sputtering method.
The soft magnetic film 13 is a CoZrMo amorphous film and has a thickness of 40 nm. Film thickness 7 as bias auxiliary film 14
A NiFe film having a thickness of nm was formed. Further, the NiFe film 1
4 was patterned. In FIG. 1A, the pattern interval of 14 is 3 μm. As the antiferromagnetic film 11, Fe
A Mn film was formed to a thickness of 15 nm. Thus, the exchange coupling magnetic field (Hex) applied to the CoZrMo film by the FeMn film via the bias auxiliary film becomes 20 Oe as shown in FIG. Further, a 30 nm thick NiFe film was formed as the MR film 12 to obtain an MR element. When formed on the NiFe film 14, the FeMn film 11 forms a face-centered cubic lattice (γ phase) and generates Hex. The γ phase is formed in the FeMn film because the NiFe film has a face-centered cubic lattice.
This is because the eMn film is epitaxially grown on the NiFe film. Therefore, in FIG.
Of the CoZrMo film 13 in the vertical direction of the
Hex occurs in two parts. On the other hand, no γ phase is formed in the portion of the FeMn film 11 in contact with the amorphous film 13 and a body-centered cubic lattice (α phase) or an amorphous phase which does not contribute to Hex is formed. A certain portion of the CoZrMo film 13 and the MR film 12 have H
ex does not occur. Therefore, a portion without the NiFe film 14 functions as a reproducing portion (track) of the MR head, and the MR film and the CoZrMo film on both sides thereof are made into a single magnetic domain by Hex. When the reproduction characteristics of an MR head having electrodes formed of Au at both ends of the MR element were examined, a good reproduction waveform without Barkhausen noise was obtained.

In the MR element having the structure shown in FIG. 1A, a good reproduction waveform free of Barkhausen noise was also obtained in an MR head using a Ni film as the bias auxiliary film 14. . When a Ni film is used, Hex applied to the CoZrMo film is as large as 30 Oe even at a thin film thickness of 1 nm, which is efficient.

Embodiment 2 FIG. 1B shows an MR of a magnetoresistive head according to the present invention.
It is sectional drawing of one Example of an element part. An MR element having the structure shown in FIG. 1B was formed on an Al ₂ O ₃ —TiC-based ceramic substrate. The film was formed by sputtering various alloy targets by argon plasma using a sputtering method.
The soft magnetic film 13 is a NiFeNb film having a thickness of 40 nm.
It is. As the nonmagnetic film 15, a Ta film having a thickness of 5 nm was formed. Further, this Ta film 15 was patterned into a width of 3 μm. Next, an FeMn film is formed as the antiferromagnetic film 11 by 15 n.
m was formed. Further, a 30 nm thick NiFe film is applied to the MR film 1.
2 as an MR element. The FeMn film 11 is made of N
When formed on the iFeNb film 13, a face-centered cubic lattice (γ phase) is formed to generate Hex. Γ on FeMn film
The phase is formed by the epitaxial growth of the FeMn film on the NiFeNb film because the NiFeNb film has a face-centered cubic lattice. In contrast, the Ta film 1
The FeMn film 11 on No. 5 does not form a γ phase, and generation of Hex is eliminated. This is presumably because the Ta film surface did not have a factor for epitaxially growing the γ phase of the FeMn film, or was extremely diluted. One example is the existence of an amorphous oxide layer formed on the surface of the Ta film when the Ta film is patterned. Therefore, in FIG. 1B, the portion of the NiFeNb film 13 in contact with the FeMn film 11 and the MR film 12 in the upper portion thereof
Hex is applied to. On the other hand, Hex is not applied to the NiFeNb film 13 in contact with the Ta film 15 and the MR film 12 above the NiFeNb film 13 and functions as a track portion. When the reproduction characteristics of an MR head having electrodes formed of Au at both ends of the MR element were examined, a good reproduction waveform without Barkhausen noise was obtained.

Embodiment 3 FIG. 1C shows the MR of a magnetoresistive head according to the present invention.
It is sectional drawing of one Example of an element part. An MR element having the configuration shown in FIG. 1C was formed on an Al ₂ O ₃ —TiC-based ceramic substrate. The film was formed by sputtering various alloy targets by argon plasma using a sputtering method.
In this configuration, first, the MR film 12 is formed first. The MR film 12 was a 30 nm thick NiFe film. Next, a Ta film having a thickness of 5 nm was formed as the nonmagnetic film 15. Further, this Ta film 15 was patterned into a width of 3 μm. Next, a 15 nm FeMnCr film was formed as the antiferromagnetic film 11. Further, a 7 nm-thick Ni
An Fe film was formed, and a CoTaZr amorphous film 13 was formed thereon. The FeMnCr film 11 is a NiFe film 12
When formed above, a face-centered cubic lattice (γ phase) is formed to generate Hex. The γ phase is formed in the FeMnCr film because the NiFe film has a face-centered cubic lattice.
This is because the FeMnCr film grows epitaxially on the NiFe film. On the other hand, FeMn on the Ta film 15
The Cr film 11 does not form a γ phase, and generation of Hex is eliminated. This is presumably because the Ta film surface did not have a factor for epitaxially growing the γ phase of the FeMnCr film, or was extremely diluted. One example is the existence of an amorphous oxide layer formed on the surface of the Ta film when the Ta film is patterned. Therefore, FIG.
In (c), Ni in contact with the FeMnCr film 11
The Fe film 12 and the bias assist film 14 on the Fe film 12
Hex in the CoTaZr amorphous film 13
Is applied. On the other hand, Ni in contact with the Ta film 15
Hex is not applied to the FeTa film 12 and the CoTaZr film 13 via the bias auxiliary film 14 above the Fe film 12, and functions as a track portion. When the reproduction characteristics of an MR head having electrodes formed of Au at both ends of the MR element were examined,
A good reproduced waveform without Barkhausen noise was obtained. Furthermore, since this MR element configuration does not cause a step in the MR film, it is effective in improving the reliability and performance of the element.

The MR element shown in FIG.
FIG. 1C shows a case where the bias auxiliary film 14 is patterned, and is essentially equivalent to FIG. 1C. However, in the case of FIG. 1D, the CoTaZr amorphous film 1
No step is generated in 3 as well, which is useful for improving the performance and reliability of the device.

Embodiment 4 FIG. 3 is a sectional view of an embodiment of an MR element portion of a magnetoresistive head according to the present invention. An MR element having the configuration shown in FIG. 3 was formed on an Al ₂ O ₃ —TiC-based ceramic substrate.
The film was formed by sputtering various alloy targets by argon plasma using a sputtering method. In this configuration,
First, the MR film 32 is formed. The MR film 32 has a thickness of 30 n
m NiFe film. Next, a Ta film having a thickness of 5 nm was formed as the nonmagnetic film 35. Further, this Ta film 35 is
Patterned to a μm width. Thereafter, a CoNbHf film having a thickness of 40 nm was formed as the soft magnetic film 33, and a NiFe film having a thickness of 10 nm was formed thereon as the bias auxiliary film. This N
The iFe film 34 was patterned corresponding to the Ta film. Finally, a 20 nm FeMn film was formed as the antiferromagnetic film 31. The portion of the FeMn film 31 formed on the NiFe film 34 forms a face-centered cubic lattice (γ phase) to generate Hex. The γ phase is formed in the FeMn film because the NiFe film has a face-centered cubic lattice, and the FeMn film grows epitaxially on the NiFe film. On the other hand, the FeMn film 31 on the CoNbHf film 33 does not form a γ phase, and does not generate Hex. This is CoNbHf
This is because the γ phase of the FeMn film cannot be epitaxially grown on the surface of the amorphous film. At this time, the FeMn film was a mixture of the α phase and the amorphous phase. Therefore, FIG.
A CoNbHf film 33 via a NiFe film 34 as a bias auxiliary film in contact with the FeMn film 31;
Hex is applied to the lower MR film 32. On the other hand, the MR film 32 in contact with the Ta film 35 and the C
Hex is not applied to the oNbHf film 33 and functions as a track portion. When the reproduction characteristics of an MR head having electrodes formed of Au at both ends of the MR element were examined, a good reproduction waveform without Barkhausen noise was obtained.

[0014]

As described above, according to the present invention,
In a magnetoresistive head having a magnetoresistive effect (MR) element comprising a magnetoresistive film, a soft magnetic film for lateral bias, and an antiferromagnetic film, the reliability and yield of the MR element are kept high, and the Co amorphous is used. Even when the film is a soft magnetic film for lateral bias, an element free of Barkhausen noise can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an MR element portion of a magnetoresistive head according to the present invention.

FIG. 2 is a sectional view of a conventional MR element.

FIG. 3 is a sectional view of an MR element portion of the magnetoresistive head according to the present invention.

FIG. 4 shows a case where a bias assist film is made of a NiFe film;
FIG. 4 is a diagram showing the dependence of the exchange coupling magnetic field (Hex) applied from the Mn film to the CoZrMo amorphous film via the bias auxiliary film on the bias auxiliary film thickness.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Antiferromagnetic film 12 MR film 13 Soft magnetic film 14 Bias auxiliary film 15 Nonmagnetic film 21 Antiferromagnetic film 22 MR film 23 Soft magnetic film 24 Nonmagnetic film 31 Antiferromagnetic film 32 MR film 33 Soft magnetic film 34 Bias Auxiliary film 35 Non-magnetic film

Claims (3)

(57) [Claims] In a magnetoresistive head having a magnetoresistive film, a soft magnetic film for lateral bias and an antiferromagnetic film, the soft magnetic film for lateral bias is Co and M (M is Ti, V,
Cr, Zr, Nb, Mo, Hf, Ta, Y, Ru, R
h, Pd, Cu, Ag, Au and Pt.
Alloy containing at least one element selected from the group consisting of
Gold, and the antiferromagnetic film is made of FeMn alloy or FeMn
, Ti, Cr, Ni, Zr, Nb, Mo, Ru, Rh,
Selected from the group of Hf, Ta, W, Re, Os and Ir
An alloy to which at least one element is added,
The crystal structure of the antiferromagnetic film includes a face-centered cubic lattice,
The proportion of the crystal structure consisting of the face-centered cubic lattice in the film
Characterized in that it varies in the plane direction,
Ni and Fe as main components between the magnetic film and the antiferromagnetic film
Film, Ni film or Ni-based film
A magneto-resistive head having a structure sandwiched in a direction . 2. A magnetoresistive film and a soft magnetic film for lateral bias.
Of a magnetoresistive head having a magnetic layer and an antiferromagnetic film
The soft magnetic film for lateral bias is an alloy containing Ni and Fe as main components, and the antiferromagnetic film is a FeMn alloy or FeMn.
n is Ti, Cr, Ni, Zr, Nb, Mo, Ru, R
an alloy to which at least one element selected from the group consisting of h, Hf, Ta, W, Re, Os, and Ir is added, wherein the crystal structure of the antiferromagnetic film includes a face-centered cubic lattice;
A magnetoresistive head, wherein the proportion of the crystal structure composed of the face-centered cubic lattice in the film changes in the film surface direction. 3. A process according to claim antiferromagnetic film has a structure sandwiched between the film thickness direction and the magnetoresistive film and the transverse bias soft magnetic film
3. The magnetoresistive head according to 1 or 2 .