JP2596010B2 - Magnetoresistive magnetic head - Google Patents

Description

The present invention relates to a magneto-resistance effect type magnetic head, particularly to a shield type magneto-resistance effect type magnetic head.

[Summary of the Invention]

The present invention provides a shielded magnetoresistive magnetic head in which a magnetically sensitive portion having a magnetoresistive effect is provided on a substrate, and a shielded magnetic layer is arranged to cover the magnetically sensitive portion.
A pair of electrode conductive layers derived from both ends of the magneto-sensitive portion extend on both sides in a direction orthogonal to the direction in which the signal magnetic field is applied to the magneto-sensitive portion, and both extending ends are connected as a loop, By performing terminal derivation from this loop portion, it is possible to reduce the electric resistance as described later,
Further, the magnetic characteristics can be stabilized and the reliability can be improved.

[Conventional technology]

In a magneto-resistance effect type magnetic head (hereinafter referred to as an MR type magnetic head), its magnetic sensing part, that is, a magneto-resistance effect (hereinafter, referred to as an MR type magnetic head).
The device is called an MR effect).
Thin film with MR effect or one with MR effect and the other
An MR type magnetic head constituted by a laminated body of magnetic thin films having no or little MR effect and having both thin films pass a sense current in the same direction is disclosed in, for example, JP-A-61-182620 and JP-A-62-182620. No. 52711 and Japanese Patent Application No. 60-247752. MR with this configuration
In the type magnetic head, the magnetoresistive thin film constituting the magnetic sensing portion has a single magnetic domain configuration, and the generation of domain walls is avoided, so that the generation of Barkhausen noise can be suppressed.

Such an MR type magnetic head has at least one MR effect on a substrate (1) as shown in an enlarged plan view of FIG. 4 and a sectional view taken along the line AA of FIG. 4 in FIG. Magnetically sensitive part (2) comprising first and second ferromagnetic thin films (11) and (12) having a layer laminated via a non-magnetic intermediate layer (13)
The front end face faces the surface (8) facing or facing the magnetic recording medium and extends rearward so as to be orthogonal to the surface (8). A) a direction perpendicular to the track width direction with respect to the magnetically sensitive portion (2), extending in a so-called track width direction that crosses the direction perpendicular to the extending direction of the magnetically sensitive portion (2) upward or downward; The bias magnetic field generating conductor (5) for applying a bias magnetic field to the magnetic field sensitive part (2) in a range where the magnetoresistive characteristic has a linearity by applying a bias magnetic field to the direction of application of the signal magnetic field to the part (2) is insulated. It is formed by lamination via the layer (14). On the other hand, the front end and the rear end of the magnetically sensitive portion (2) have a direction substantially perpendicular to the surface (8) in contact with or facing the magnetic recording medium with respect to the magnetically sensitive portion (2). The front and rear electrode conductive layers (3) and (4) for applying a sense current i in the direction along the signal magnetic field direction obtained from are formed on the ferromagnetic thin films (11) and (12). The direction of the hard axis is selected so as to be along the direction in which the signal magnetic field and the sense current i flow. In this configuration, a change in resistance of the magnetic sensing portion (2) due to a signal magnetic field based on recording information from the magnetic recording medium is detected as a voltage change at both ends due to the sense current i, and recording on the magnetic recording medium is reproduced. It is done as follows.

In the MR type magnetic head having such a configuration, in order to increase the resolution as a magnetic head, a shield type structure in which magnetic materials are arranged above and below an MR effect element, that is, a magnetic sensing part (2) is often adopted. In this case, a magnetic material is used as the substrate (1) to serve as a lower magnetic material, while a magnetic metal such as permalloy is provided on the substrate (1) via an insulating layer (6) so as to cover the magnetosensitive portion (2). A (sputtered or plated) shield magnetic material layer (7) having a thickness of several micrometers (Ni-Fe alloy) is arranged.

[Problems to be solved by the invention]

The present invention aims to further improve the characteristics and stabilize the characteristics in the above-mentioned shield type MR magnetic head.

That is, in the present invention, in the shield type MR magnetic head described with reference to FIGS. 4 and 5, the lead-out mode of the electrode conductive layer and the magnetic domain state of the upper shield magnetic layer (7) due to this are as follows. We investigate that it has a significant effect on the characteristics, and aim to improve and stabilize the characteristics based on this investigation.

That is, in the above-mentioned shield type MR type magnetic head, as shown in FIG. 5, the surface to which the shield magnetic layer (7) is attached has the bias magnetic field generating conductor (5) and the electrode conductive layer (3). ) And (4) make the surface uneven. That is, in the above-described configuration, the magneto-sensitive portion (2) has a relatively small thickness of, for example, about 800 mm, so that its edge exists under the shield magnetic layer (7). Although the step does not matter much in the above, the electrical reliability of the conductor (5) for generating the bias magnetic field and the electrode conductive layers (3) and (4), that is, avoiding the occurrence of disconnection, and the resistance Considerably large thickness for reasons such as reduction
In order to select a thickness of about Å or more, if the edges of the bias magnetic field generating conductor (5) and the electrode conductive layers (3) and (4) are under the shield magnetic layer (7), the insulation Despite the formation of the shield magnetic layer (7) through the layer (6), the step at the edge becomes relatively severe, and the bending of the shield magnetic layer (7) at this point becomes remarkable. Become.

Now, for example, looking at the magnetic domain state when the shield magnetic layer (7) is formed as a flat surface, as shown in FIG. 6, the main magnetic domain extends substantially along the easy axis. As a result, a 180 ° magnetic domain configuration is arranged in parallel. Incidentally, in this case, the shield magnetic layer (7) has a thickness of several μm, and has a magnetostriction of the order of 10 ⁻⁷ , which is considered to be almost zero magnetostriction. However, as shown in FIG. 4, the conductor (5) and the electrode conductive layers (3) and (4) exist under the shield magnetic layer (7) as shown by the broken lines in FIG. In this case, the bending caused by the step formed by the edges of the conductor (5) and the electrode conductive layers (3) and (4) causes distortion in the 180 ° magnetic domain as shown by a chain line in FIG. If the disturbance of the magnetic domain occurs especially in the vicinity of the magnetically sensitive portion (2), the unstable magnetic domain operation has a great effect on the magnetoresistive characteristics of the magnetically sensitive portion (2), which immediately leads to the deterioration of the output of the head. However, the error rate of the magnetic recording / reproducing apparatus system deteriorates.

The generation of the random magnetic domain does not greatly affect the generation of the random magnetic domain with respect to the bending of the shield magnetic layer (7) due to the step along the domain wall direction of the 180 ° magnetic domain, but has a large effect in the direction orthogonal to the direction. affect. That is, for example, when the front electrode conductive layer (3) is extended only one side from the front of the magneto-sensitive portion (2) as shown in FIG. )
In the case where the rear electrode conductive layer (4) is further extended rearward in the direction of extension of the magnetic sensing portion (2), the seventh step is caused by the step formed by the left and right side edges (4a) and (4b).
As shown in the figure, when there are these steps, especially steps crossing the easy axis direction, the magnetic domain disturbance caused by these steps greatly affects the magnetic sensing part (2). For example, when the front electrode conductive layer (3) and the bias conductor (5) have a bent portion in the pattern under the shield magnetic layer (7),
The step corresponding to the bent shape causes distortion in the 180 ° magnetic domain, that is, greatly affects the generation of random magnetic domains. In particular, the random magnetic domain is located near the surface (8) of the magnetic sensing portion (2) in contact with or facing the magnetic recording medium, that is, on the side where the signal magnetic field from the magnetic recording medium is introduced, that is, in the magnetic sensing portion (2). This has a significant effect on the main operating section.

Furthermore, when the electrode conductive layer (3) is configured to extend in one direction only on one side as shown in the figure, a magnetic field is generated by the sense current i passing through the electrode conductive layer (3) only on this one side. Therefore, depending on whether the direction of the energization is parallel or anti-parallel to the direction of the energization to the bias magnetic field generating conductor (5), the manner of applying the substantial bias to the magneto-sensitive portion (2) greatly differs. , Large left-right asymmetry.

 The present invention seeks to solve the above-mentioned problems.

[Means for solving the problem]

In the present invention, as shown in FIG. 1 as a plan view and FIG. 2 as a cross-sectional view taken along the line AA in FIG. 1, at least one of the pair having a magnetoresistive effect is formed on the substrate (1). A magnetic sensing part (2) in which magnetic thin films (11) and (12) are laminated via a non-magnetic intermediate layer (13), and a sense current from both ends of the magnetic sensing part (2) in the same direction as the signal magnetic field. i, and the electrode conductive layers (3) and (4) derived in a direction substantially perpendicular to the direction of the sense current i in the magnetic sensing part (2) and the insulating layer (14). And a bias magnetic field generating conductor (5) extending so as to traverse therethrough, and an MR type having a shield magnetic layer (7) arranged so as to cover an arrangement portion of the magnetic sensing portion (2). In the magnetic head, the electrode conductive layers (3) and (4) and the bias magnetic field generating conductor (5) are arranged on the shield magnetic layer (7). In the lower part, substantially in the entire region, particularly in the main operating part near the front side of the magneto-sensitive part (2) on the side facing or facing the magnetic recording medium (8),
In the direction in which the signal magnetic field is applied from the magnetic recording medium, that is, in the direction of the hard axis, that is, in the direction orthogonal to the direction in which the sense current is applied, in other words, in the direction of the easy axis, almost the entire area where the shield magnetic layer (7) is disposed. To extend so that there is almost no edge or bent portion. In other words, at least the bias magnetic field generating conductor (5) and the electrode conductive layers (3) and (4) are provided at least under the shield magnetic layer (7) in the direction in which the magnetically sensitive portion (2) extends (that is, in the hard axis direction). In other words, the electrode conductive layers (3) and (4) are also symmetrical from the front and rear ends of the magnetic sensing portion (2) to both sides, that is, left and right. Extended extension.

Further, in the present invention, both electrode conductive layers (3)
And both ends extended to both sides of (4) are connected to each other so as to reach outside the arrangement of the shield magnetic layer (7) or a part thereof under the arrangement of the shield magnetic layer (7). Loop portions (33) and (34) are formed to extend rearward to derive sense current conducting terminals t _SF and t _SB , respectively.

Further, terminals t ₁ and t ₂ through which a bias magnetic field generating current flows are derived from both ends of the bias magnetic field generating conductor (5).

In FIGS. 1 and 2, parts corresponding to those in FIGS. 4 and 5 are denoted by the same reference numerals, and redundant description is omitted.

[Action]

According to the configuration of the present invention described above, at least the vicinity of the magnetic sensing portion (2) under the shield magnetic layer (7), particularly, the side facing or facing the magnetic recording medium (8), that is, from the magnetic recording medium. In the vicinity of the effective operating portion to which the signal magnetic field is applied, there is no edge in the direction along the hard axis direction (the direction of the signal magnetic field and the sense current i) so that a step is formed in the shield magnetic layer (7). By avoiding this, the generation of random magnetic domains is effectively avoided, thereby stabilizing the characteristics of the magnetic sensing portion (2) and improving the error rate of the reproducing apparatus.

In addition to this, the electrode conductive layers (3) and (4) extend in parallel with the bias magnetic field generating conductor (5), and extend from the magneto-sensitive part to both sides thereof, and form a loop part ( Since 33) and (34) are provided so as to supply the sense current i, the portion near the magneto-sensitive portion (2) is clearly seen in FIG. And the sense current is divided into two, i.e., a current of i / 2 is applied to both sides thereof, thereby reducing the magnetic field generated. Further, the front electrode conductive layer (3) and the rear electrode conductive layer (4) Asymmetry of the magnetic field is alleviated by making the energizing directions of each i / 2 opposite to each other,
The influence on the characteristics of the magnetic sensing portion (2) is reduced, and the characteristics are stabilized.

Embodiment An example of the present invention will be described in further detail with reference to FIGS. 1 and 2. The substrate (1) can be composed of a magnetic substrate of, for example, Ni-Zn ferrite or Mn-Zn ferrite, and has an MR effect, for example, via an insulating layer (not shown) on this as necessary. A ferromagnetic thin film (11) or (12) made of a metal thin film such as permalloy (Ni-Fe alloy) or Ni-Fe-Co alloy or Ni-Co alloy is used as a non-magnetic insulating intermediate layer (13) such as Al After the entire surface is vapor-deposited via ₂ O ₃ , these are patterned to form a magnetically sensitive portion (2) extending, for example, in a belt shape.

The nonmagnetic intermediate layer (13) is composed of ferromagnetic thin films (11) and (12)
In the meantime, the thickness is selected to be several hundred mm or less so that the magnetostatic interaction acts dominantly compared to the exchange interaction. Each of the ferromagnetic thin films (11) and (12) is selected to have a thickness of several hundreds of mm, and the entire thickness of the magneto-sensitive portion (2) is formed to be, for example, about 800 mm.

One of the two ferromagnetic thin films (11) and (12) is a ferromagnetic thin film having little or no MR effect, for example, a high-permeability ferromagnetic soft magnetic thin film such as Sendust, a Co-based amorphous alloy, or Mo permalloy. May be configured. However, in this case, both thin films (11) and (12) can be selected by selecting their saturation magnetic flux density and thickness.
The amount of magnetic flux in 2) is matched so that the magnetic flux
Regarding 1) and (12), it is made to be able to be totally closed so that the generation of magnetic domains does not occur.

An insulating layer (14) such as Si ₃ N ₄ or SiO ₂ is formed on the magnetic sensing part (2), and an electrode contact window (14a) is formed on both front and rear ends of the magnetic sensing part (2). And (14b) are drilled, and the front and rear electrode conductive layers (3) and (4) are applied through these contact windows (14a) and (14b), respectively.
Further, a conductor (5) for generating a bias magnetic field is applied across the magnetic sensing part (2) via the insulating layer (14). These electrode conductive layers (3) and (4) and the bias conductor (5) are made of Mo,
It can be formed simultaneously by depositing a metal layer of W, Ti, etc. over the entire surface and patterning by photolithography. The electrode conductive layers (3) and (4) and the bias magnetic field generating conductor (5) are respectively arranged in a direction orthogonal to the extension direction of the magneto-sensitive portion (2) (that is, the direction in which the sense current i flows, the hard axis). Direction and a direction perpendicular to the direction in which the signal magnetic field is applied from the magnetic recording medium) on both sides of the magnetic sensing portion (2). Both ends of the bias magnetic field generating conductor (5) is, derivation of terminals t ₁ and t ₂ for energizing the bias magnetic field generating current is performed as usual.

Then, both ends of each of the front and rear electrode conductive layers (3) and (4) are separated from each other so that the outside or a part of the outside of the shield magnetic layer (7) exists below the shield magnetic layer (7). forms a loop connecting the end performs derivation of terminals t _SF and t _SB from the respective loop portion (33) and (34).

Then, a shield magnetic layer (7) made of, for example, permalloy having a high magnetic permeability is coated to a thickness of several μm on the arrangement part of the magnetic sensing part (2) via an insulating layer (6) by sputtering or plating. Is formed.

In this configuration, especially under the shield magnetic layer (7), the electrode conductive layers (3) and (4) and the bias magnetic field generating conductor (5) are parallel to each other, that is, in the longitudinal direction of the magnetic sensing part (2), that is, the sensor. It extends linearly in a direction perpendicular to the direction of current i, the direction of the hard axis, and the direction of application of the signal magnetic field so that no bend or edge exists in the entire extension direction. That is, the edges of the electrode conductive layers (3) and (4) on the side opposite to the terminal lead-out end side are located outside the shield magnetic layer (7). Then, the front end is polished from the substrate (1) to the shielded magnetic layer (7) to form a contact or facing surface (8) with the magnetic recording medium facing the front end face of the magnetosensitive portion (2). Is done.

In the example shown in FIG. 1, the width at the front end and the width at the rear end of the shield magnetic material layer (7) facing the magnetic recording medium or facing the facing surface (8) are the same. In this case, the width is rectangular, but in some cases, as shown in FIG. 3, the portion facing the magnetic recording medium or the portion facing the facing surface (8) is larger than the track width. However, the shape may be narrower and wider toward the rear, that is, the shape may widen rearward.

Even when the shield magnetic layer (7) is formed to have a divergent shape at the rear, as shown in FIG. 8, for example, the edges (4a) and (4b) of the rear electrode conductive layer (4) are shielded magnetically. When the magnetic head exists below the body layer (7), the 180 ° magnetic domain is disturbed as shown by the chain line in FIG. 8 and the magnetic domain characteristic is deteriorated. As a result, 180 ° magnetic domains are generated relatively orderly by preventing the steps caused by the edges (4a) and (4b) from being generated in the shield magnetic layer (7), thereby generating random magnetic domains in the shield magnetic layer. Is suppressed.

〔The invention's effect〕

As described above, according to the present invention, despite the fact that a shield type MR magnetic head is employed, at least the upper shield magnetic layer (7) has at least a sense current i of the magnetically sensitive portion (2) and a magnetization difficulty. The step extending in the axial direction and in the direction along the direction in which the signal magnetic field is applied is prevented from being generated in the vicinity of the effective operating portion of the magnetic sensing portion (2).
The unstable operation due to the occurrence of the random magnetic domain is avoided, and the supply of the sense current i to the magnetic sensing part (2) is divided into two parts from the magnetic sensing part (2) and supplied to both sides. Since the imbalance due to the magnetic field generated from the electrode conductive layers (3) and (4) by the supply of the sense current can be reduced, the characteristics can be further stabilized.

Further, in the configuration of the present invention, each of the electrode conductive layers for supplying the sense current to the magnetic sensing portion is divided into a left and a right to form a loop, so that the conduction path is formed of two parallel paths, As a result, when the width and thickness of each electrode conductive layer are selected, for example, to the same level as in the conventional case, the resistance of the entire power supply path to the magneto-sensitive portion is reduced by almost half compared to the conventional case. When the resistance of the entire power supply path is selected to be approximately the same as the conventional one, for example, the thickness can be reduced by half, so that the step on the surface of the shield magnetic body formed thereon can be reduced, Reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic enlarged plan view of an example of a magnetic head according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is an enlarged view of another example of the magnetic head of the present invention. FIGS. 4 and 5 are a schematic enlarged plan view of a conventional magnetic head and a schematic enlarged sectional view taken along line AA of FIG. 4, and FIGS. 6 to 8 are shield magnetic bodies. It is explanatory drawing of the magnetic domain of a layer. (1) is a substrate, (2) is a magnetic sensing part, (3) and (4) are electrode conductive layers, (5) is a bias magnetic field generating conductor, and (7) is a shield magnetic layer.

Claims (1)

(57) [Claims] 1. A substrate, a magnetically sensitive portion having a ferromagnetic thin film having a magnetoresistive effect on the substrate, and a magnetic sensitive portion derived from both ends of the magnetic sensitive portion. A pair of electrode conductive layers for applying a sense current in the same direction as the direction in which the signal magnetic field is applied to the magnetic part; a bias magnetic field generating conductor extending across the magnetic sensitive part via an insulating layer; A shield magnetic layer disposed over the arrangement portion of the magnetic portion is formed, and the pair of electrode conductive layers and the bias magnetic field generating conductor are at least under the arrangement portion of the shield magnetic layer, The direction in which the signal magnetic field is applied to the magneto-sensitive portion is substantially orthogonal to the magneto-sensitive portion, and the symmetrical portion is formed so as to extend symmetrically toward both outer sides of the magneto-sensitive portion. Both ends thereof are located outside the portion where the shield magnetic layer is arranged, or A magnetoresistive head according to claim 1, wherein a part thereof is connected to each other below the portion where the shield magnetic material layer is arranged to form a loop, and terminals are led out from each of the loop portions.