JPH0346884B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a magnetic head using a magnetoresistive element made of a ferromagnetic thin film, and particularly relates to a magnetic head that uses a magnetoresistive element made of a ferromagnetic thin film, and in particular a magnetic head that uses a magnetic yoke to guide signal magnetic flux to the magnetoresistive element. This invention relates to a yoke type magnetoresistive thin film magnetic head.

(Prior art) Conventionally, magnetoresistive thin-film magnetic heads (hereinafter referred to as MR thin-film heads) that utilize magnetoresistive elements (hereinafter referred to as MR elements) made of ferromagnetic thin films are electromagnetic heads that utilize coils. Compared to the induction type thin film magnetic head, the reproduction sensitivity when the magnetic tape runs at low speed is high, and the track can be easily narrowed, so it is used as a multi-track magnetic head in high-density magnetic recording. this kind of
Conventional MR thin-film heads include the so-called shielded type and non-shielded type, in which the MR element is directly exposed on the sliding surface of the magnetic tape, and the magnetic yoke that guides the magnetic flux to the internal MR element. ,
There is a so-called yoke type.

FIG. 6 shows a sectional view of a conventional yoke type MR thin film head. In the figure, 1 is the conventional MR
It is a thin film head, and 2 is a magnetic substrate made of Mn-Zn ferrite or Ni-Zn ferrite.
The wall surface 2a that is the sliding surface of the magnetic tape and this wall surface 2a
The plane 2b is substantially perpendicular to the plane 2b.

Reference numeral 3 denotes a magnetic gap made of a magnetically and electrically insulating film such as _SiO2 , which is provided on the flat surface 2b of the magnetic substrate 2 by known thin film forming means.

4 is a conductor for applying a bias magnetic field to the MR element to be described later, and is made of metal such as Al, Al-Cu, Mo, etc.

5 is Al ₂ O 3 or Al 2 O ₃ provided so as to cover the conductor 4.
It is an electrical insulating film made of SiO ₂ .

Reference numeral 6 denotes an MR element made of a thin film of Ni--Fe, Ni--Co, etc., which is provided on the conductor 4 with an electrical insulating film 5 interposed therebetween.

Reference numeral 7 denotes an electrical insulating film made of Al ₂ O ₃ or SiO ₂ for insulating the MR element 6 .

8 is a front magnetic yoke provided on the conductor 4 via the electrical insulating films 3, 5, and 7;
a faces the magnetic substrate 2 through the magnetic gap 3a, and is part of the tape sliding surface 8 along with the wall surface 2a.
b, and has a core width equivalent to the width of a recording track (not shown) in a direction substantially perpendicular to the plane of the paper.

Similar to the front magnetic yoke 8, 9 is an electrical insulating film 3,
It is a rear magnetic yoke provided on the conductor 4 via 5 and 7, and its one end 9a is connected to the front magnetic yoke 8.
Together with the other end 8c, it constitutes a sensor gap SG for supplying magnetic flux to the MR element 6, and
The other end 9b is connected to the flat surface 2b of the magnetic substrate 2. From the above configuration, it is possible to consider one magnetic closed circuit S consisting of the front magnetic yoke 8, the sensor gap SG, the rear magnetic yoke 9, the magnetic substrate 2, and the magnetic gap 3a, and the conductor 4 and the MR element 6.
is arranged in this magnetic closed circuit S.

As mentioned above, since the front magnetic yoke 8 and the rear magnetic yoke 9 are provided on the insulating film 7 having a step, steps d ₁ , d ₂ etc. having a steep slope are generated in these magnetic yokes 8 and 9. There is.

In the above configuration, the tape sliding surfaces 2a, 8b
A signal magnetic flux from a magnetic tape (not shown) running above flows in a magnetic closed circuit S whose starting and ending points are the wall surface 2a and a portion 8b of the tape sliding surface of the front magnetic yoke 8, respectively. A part of the magnetic flux passing through the SG becomes leakage magnetic flux and flows through the MRG element, so due to changes in magnetic flux.
A change in the resistance value of the MR element is outputted to the outside as a change in output voltage, that is, a reproduction output, through a known electric circuit.

At this time, a current is applied to the conductor 4 to provide a bias magnetic field that maximizes the rate of change in resistance of the MR element 6.

The problems with the conventional yoke-type MR thin film head described above are: (1) When forming the patterns of the front and rear magnetic yokes 8 and 9 on the insulating film 7 by photo-etching, the insulating film 7 is attached to the conductor 4; The pattern of the front and rear magnetic yokes 8 and 9 provided on top of the magnetic yokes 8 and 9 has an uneven portion, and as a result, the pattern of the front and rear magnetic yokes 8 and 9 that is provided on top of the magnetic yokes 8 and 9 creates steps d ₁ and d ₂ , and as a result, the above-mentioned pattern is formed with high precision. I can't do that.

(2) Steps d ₁ and d ₂ between the front and rear magnetic yokes 8 and 9
The magnetic properties, especially the magnetic permeability μ, tend to deteriorate in these parts, resulting in a decrease in the reproducing efficiency of the magnetic head.

(3) When a flat protective substrate (not shown) is provided on the surfaces of the front and rear magnetic yokes 8 and 9 via adhesive to form a highly wear-resistant magnetic head, the steps d ₁ and d ₂ The adhesive layer formed on the tape is easily abraded as the tape runs, and the dents caused by abrasion tend to attract dust, causing problems such as spacing loss and reduced playback output. It was hot.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and the first invention includes a wall surface serving as a sliding surface for a magnetic tape, and a wall surface substantially perpendicular to the wall surface. a magnetic substrate having a flat surface formed thereon, a cutout portion having a flat portion formed on the plane including the wall surface, a conductor for applying a bias magnetic field, and a sensor gap for applying magnetic flux to the magnetoresistive element. and the magnetic yoke through electrical insulating films that are to become magnetic gaps, respectively, so as to be at the same height as the plane of the magnetic substrate, and
A second magnetoresistive thin film magnetic head, characterized in that the sensor gap is configured to be exposed on this plane, and the magnetoresistive element is disposed near the exposed surface of the sensor gap. In this invention, a magnetic substrate having a wall surface serving as a sliding surface for a magnetic tape and a plane formed almost perpendicular to the wall surface is provided, a cutout portion having a flat portion is formed on the plane including the wall surface, and a bias A conductor for applying a magnetic field and a first magnetic yoke having a first sensor gap for applying magnetic flux to the magnetoresistive element are connected to each other through an electrically insulating film and an electrically insulating film to serve as a magnetic gap, respectively. so that it is at the same height as the plane of the magnetic substrate, and
A second magnetic yoke having a second sensor gap is provided so as to cover the first sensor gap, and the magnetoresistive element is connected to the second sensor gap. It is an object of the present invention to provide a magnetoresistive thin film magnetic head which is characterized in that it is provided nearby.

(Embodiment) FIG. 1 is a partially cutaway perspective view showing a first embodiment of a yoke type MR thin film head according to the present invention.
This figure shows the case where multiple thin film heads are provided. FIG. 2 is a sectional view of a main part taken along the - line in FIG. 1.

This will be explained below using FIGS. 1 and 2.

In the figure, 10 is an MR thin film head according to the present invention. Reference numeral 11 denotes a magnetic substrate made of, for example, Mn--Zn ferrite, and has a wall surface 11a serving as the sliding surface 12 of the magnetic tape and a flat surface 11b formed substantially perpendicular to the wall surface 11a.

A notch 13 is provided in a plane 11b that includes the wall surface 11a, and has a rectangular flat surface 13a that is substantially perpendicular to the wall surface 11a.

Reference numeral 14 denotes an insulating film made of SiO ₂ or the like, which is provided on the inner wall of the notch 13, and is connected to a conductor 17 to be described later.
It plays the role of electrical insulation between the inner wall of the cutout 13 and the inner wall of the notch 13.

Reference numeral 15 denotes a front magnetic yoke made of a soft magnetic film such as Sendust, which connects the tape sliding surface 15a formed together with the wall surface 11a and the magnetic substrate 11.
A front plane part 15 having the same height as the plane 11b of
It has b.

Reference numeral 16 denotes a rear magnetic yoke, which is made of the same material as the front magnetic yoke 15, and is provided inside the notch 13 so as to face it.Similarly to the front magnetic yoke 15, the rear magnetic yoke has a rear plane at the same height as the plane 11b. It has a section 16a. The front and rear magnetic yokes 15 and 16 have an electrical insulating film 14 inside the notch 13.
A required number of magnetic heads are provided via a to 14c, etc.

Note that the electrical insulating film 14a has a magnetic gap function.

17 is a conductor for applying a bias magnetic field to the MR element 18, and is made of metal such as Al, and the front and rear magnetic yokes 15 and 16 are connected to the insulating film 14.
The notch 1 is electrically and magnetically insulated through the
Similar to the magnetic yokes 15 and 16, its upper surface 17a is provided inside the magnetic substrate 11 plane 1.
It has the same height as 1b.

19, the flat part 15b of the front magnetic yoke 15 and the flat part 16a of the rear magnetic yoke 16 have a gap length.
The sensor gap 19 is formed by facing each other with W ₁ in between, and insulating films 14c and 14d and a conductor 17 are interposed between the sensor gap 19.

The sensor gap 19 is shown in the main part sectional view taken along the - line in FIG. 1 shown in FIG. 2, and as is clear from the figure, the sensor gap 19 is wider at the bottom than at the top. 20 is the plane 11b
magnetic yokes 15, 16 having planes at the same height as
and an insulating film made of, for example, SiO ₂ provided on the conductor 17. The MR element 18 is made of, for example, Ni
It consists of a magnetic flux detecting section 18a made of a thin film of -Fe and having a width P, and connecting sections 18b and 18c extending from this magnetic flux detecting section 18a.
a, 19b are provided. The magnetic flux detection part 18a having a width P is formed by an insulating film 2 having a flat plane.
Sensor gap 19 with width W ₁ through 0
provided above.

In this embodiment, values of W ₁ =3 to 4 μm and P = about 2 to 3 μm are used, but it goes without saying that these specific values vary depending on the specifications.

As mentioned above, the configuration of the present invention is most different from the conventional configuration in that the front magnetic yoke 15 and the rear magnetic yoke 16 have flat planes 15b and 16a.
MR on the sensor gap 19 made by
This is the point where the element 18 is arranged. In other words, the magnetic yokes 15 and 16 are the MR elements 1 outside the magnetic closed circuit 21 made of the magnetic substrate 11 etc.
This is the point where the number 8 was set.

The operation of the above configuration is similar to that of the prior art example, so a description thereof will be omitted.

Figures 3a to 3f are the first diagrams shown in Figure 1 that constitute the present invention.
FIG. 1 is a manufacturing process explanatory diagram of an example of FIG.
The explanation will be based on a cross-sectional view taken along a line.

The manufacturing process will be described below with reference to the same figure.

In FIG. 3a, 31 is a magnetic substrate having a flat plane 31a on its upper surface.

32 is a groove formed in the plane 31;
The bottom part 32a of 2 has a smooth plane that is substantially parallel to the plane 31a. As a method for forming the grooves 32, there is a method in which only the grooves 32 are removed from the resist portion on the substrate surface by photolithography, and then etched using a liquid such as phosphoric acid.

As will be described later, the bottom 32a of the groove 32 needs to be smooth because it is provided with a magnetic gap, but if an ion milling method using an inert gas such as argon is used as an etching method, the etching surface can be made smooth. You can.

Next, as shown in FIG. 3b, an electrical insulator 33 such as Al ₂ O ₃ or SiO ₂ is deposited on the magnetic substrate 31 having the groove portion 32 by means such as sputtering or vapor deposition.

Subsequently, after depositing a non-magnetic metal material 35 such as Al or Mo on the electrical insulator 33, the non-magnetic metal material 35 is etched using the sensor gap pattern 34 formed by photolithography as a mask. do.

At this time, if a wet etching method is used, the electrical insulator 33 can be used as an etching stopper, and the conductor 35a made of a non-magnetic metal part shown by the dotted line
get.

After that, the non-magnetic metal part 3 obtained by etching the sensor gap pattern as a mask.
The electrical insulator 33 is removed using 5a as a mask. When the electrical insulator 33 is made of SiO ₂ , for example, plasma etching with CF4 can be used, and the magnetic substrate 31 is used as an etching stopper. You can.

As described above, after the sensor gap pattern 34 made of photoresist is peeled off from the non-magnetic metal part 35a provided in the groove part 32 of the magnetic substrate 31 via the electrical insulator 33, as shown in FIG. As shown, after depositing the electrical insulating film 36 that will become the magnetic gap 14a, the magnetic yokes 15, 1
A soft magnetic film 37 made of, for example, Sendust is deposited on the electrical insulating film 36. after that,
By removing most of the deposited soft magnetic film 37 and electrical insulating film 36 (up to the broken line 38) by polishing, a substrate 40 having a polished surface 39 shown in FIG. 3d is obtained. 37a and 37b are front and rear magnetic yokes, respectively, and 35a is a conductor that provides a bias current.

Next, as shown in FIG. 3e, an electrical insulating film 41 made of SiO ₂ or the like is deposited on the polished surface 39 of the substrate 40, and an MR element 42 made of, for example, Ni-Fe is deposited thereon by sputtering means or the like. Form using. Thereafter, the end portion 44 of the substrate 40 is cut along the broken line 43 to reveal the magnetic gap 36a, and an MR thin film head 50 equivalent to the yoke type MR thin film head 10 shown in FIGS. 1 and 2 is obtained.

FIG. 3f shows an example of an MR thin film head in which a protective substrate 47 is provided on the plane having the MR element 42 in FIG. 3e via a protective film 45 made of SiO ₂ or the like and an adhesive layer 46. , it can be seen that since the thickness of the MR element 42 is as thin as about 0.01 to 0.06 μm, no step is formed in the adhesive layer 46.

As described above, according to the present invention, when forming the pattern of the magnetic yoke, the pattern can be formed with high accuracy because there are few steps, and the magnetic yoke obtained by polishing after depositing the soft magnetic film can be formed with high precision. Since there is no step in the yoke, there is no deterioration in magnetic properties. Even when a highly wear-resistant magnetic head is constructed by bonding a protective substrate to the magnetic yoke surface, there is no step, so the adhesive layer can be made thinner, making the MR thin-film head unaffected by adhesive layer wear. This makes manufacturing possible.

FIG. 4 and FIG. 5 respectively show the second embodiment of the present invention.
and FIG. 9 is a cross-sectional view of a third embodiment, the purpose of which is to form a sensor gap accurately near an MR element.

In FIG. 4, 60 is the second embodiment.
It is an MR thin film head. Reference numeral 61 denotes a second magnetic yoke made of a magnetic thin film such as Sendust, which magnetically connects the front magnetic yoke 15 and rear magnetic yoke 16 from which part of the electrical insulating film 20 has been removed in the MR thin film head 10 shown in FIG. It is provided on both yokes 15 and 16 so as to be coupled to each other, and also provided on the MR element 18a via an electrical insulating film 62 made of SiO ₂ or the like.

Reference numeral 63 denotes a second sensor gap provided on the second magnetic yoke 61, and by using the above patterning method, the second sensor gap having a gap length W ₂ can be precisely aligned with the MR element 18a.
It becomes possible to form on the top.

In FIG. 5, 70 is the third embodiment.
It is an MR thin film head. Reference numeral 71 designates a second magnetic yoke made of a magnetic thin film such as sendust, and is provided so as to form a sensor gap 72 having a gap length _W3 on the conductor 35a of the polished surface 39 of the substrate 40 shown in FIG. 3d.

73 is provided on the second magnetic yoke 71
It is an electrical insulating film made of SiO ₂ or the like, and 74 is an MR element provided on the sensor gap 72 via the electrical insulating film 73.

In this configuration, the sensor gap length W ₃
The second magnetic yoke 7 can be formed with high precision.
1 has less surface irregularities than the second magnetic yoke 61 shown in FIG. have.

(Effects of the Invention) As described above, the magnetoresistive thin film magnetic head according to the present invention has a groove section provided on the plane of a magnetic substrate having a plane section, and a sensor gap formed inside the groove section, which is made of a ferromagnetic thin film. A magnetic yoke and a conductor that provides a bias magnetic flux to the sensor gap are buried, and the same plane is formed by polishing so that the height of these is the same as that of the flat part of the magnetic substrate, and the exposed part on this same plane is buried. By providing the MR element near the sensor gap, (1) the magnetic yoke is not subject to deterioration of magnetic properties due to differences in level, making it possible to manufacture an MR thin-film head with excellent reproduction efficiency;

(2) When configuring the protection board, the magnetic head bonded to the magnetic yoke surface is on the same plane.
The adhesive layer on the tape sliding part can be made thinner, so it is not affected by wear caused by tape running.
Enables the production of MR thin film heads.

Furthermore, by providing a second magnetic yoke having a second sensor gap on the same plane and configuring the MR element near the second sensor gap, (3) A highly accurate configuration of the sensor gap and MR element can be achieved. MR with less manufacturing variation
This has effects such as making it possible to manufacture thin film heads.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a yoke type MR thin film head according to the present invention, FIG. 2 is a cross-sectional view of main parts taken along the line - in FIG. 1, and FIGS. 3 a to e
3 is an explanatory diagram of the manufacturing process of the embodiment of the yoke type MR thin film head according to the present invention, and FIG. 4 and 5 are cross-sectional views showing the second and third embodiments of the present invention, respectively, and FIG. 6 is a cross-sectional view of the constructed MR thin-film head, and FIG. 6 is a cross-sectional view showing the conventional yoke type magnetoresistive thin film head. FIG. 3 is a sectional view of the head. 11...Magnetic substrate, 11a...Wall surface, 11b...
...Plane, 12...Magnetic tape sliding part, 13...Notch, 14, 20...Electric insulating film, 15, 37a
...Front magnetic yoke, 16, 37b... Rear magnetic yoke, 17... Conductor, 18, 42, 74... Magnetoresistive element (MR element), 19... Sensor gap, 61, 71... Second magnetism York, 6
3...Second sensor gap.

Claims (1)

[Claims] 1. A magnetic substrate having a wall surface serving as a sliding surface for the magnetic tape and a flat surface formed substantially perpendicular to the wall surface, and a cutout portion having a flat portion on the flat surface including the wall surface. A conductor for applying a bias magnetic field and a magnetic yoke having a sensor gap for applying magnetic flux to the magnetoresistive element are connected to the magnetic substrate through an electrical insulating film and an electrical insulating film to serve as the magnetic gap, respectively. The sensor gap is arranged so as to be at the same height as a plane, and the sensor gap is exposed on this plane, and the magnetoresistive element is disposed near the exposed surface of the sensor gap. Magnetoresistive thin film magnetic head. 2. A magnetic substrate having a wall surface serving as a sliding surface for the magnetic tape and a flat surface formed almost perpendicular to the wall surface is provided, a cutout portion having a flat portion is formed on the flat surface including the wall surface, and a bias magnetic field is applied. A conductor for supplying magnetic flux to the magnetoresistive element and a first magnetic yoke having a first sensor gap for supplying magnetic flux to the magnetoresistive element are connected to the magnetic substrate through an electrical insulating film and an electrical insulating film to serve as a magnetic gap, respectively. The sensor gap is configured and provided so as to be at the same height as a plane, and the sensor gap is exposed on this plane,
A magnetoresistive thin film magnet, further comprising: a second magnetic yoke having a second sensor gap so as to cover the first sensor gap; and the magnetoresistive element provided near the second sensor gap. Head.