JPH07220240A - Magneto-resistance effect type head and its production - Google Patents

Abstract

PURPOSE:To enhance the insulation characteristic of an MR element and a lower shielding magnetic material and to prevent generation of shorting by forming a groove part in this lower shielding magnetic material and embedding a nonmagnetic oxidized insulating film into this groove part. CONSTITUTION:The groove part is formed by patterning and etching to such a U shape in section that the opening width of the groove is gradually smaller toward the base in a direction orthogonal with the longitudinal direction of the lower shielding magnetic material 3 in the region of the magnetic material 3 existing backward of the depth zero position of the reproducing magnetic gap of the lower layer with respect to a surface for contact with media. The groove part 6 is formed wider in the opening width W2 than the base width W1 of the groove part 6 and is provided with slopes 6a, 6b in the peripheral edge part of the opening in order to flatten the MR element forming surface and to enhance its accuracy at the time of a flattening stage of the nonmagnetic oxidized insulating film. The opening width W2 of the groove in the depth direction of the reproducing magnetic gap is set at <=20mum and the depth H1 of the groove part 6 at 0.5 to 1.0mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head suitable for reading signal information recorded on a magnetic recording medium such as a hard disk, and a method for manufacturing the same.

[0002]

2. Description of the Related Art For example, as a read-only magnetic head mounted in a hard disk drive or the like, a magnetoresistive effect magnetic head (hereinafter referred to as MR
It is called a head. ) Is commonly used.

The MR head has a magnetoresistive effect element (hereinafter referred to as M
It is called an R element. ), A bias conductor that gives the MR element a magnetized state in a desired direction, and a pair of shield magnetic bodies that sandwich them from the film thickness direction.

In this MR head, a lower layer gap film is provided between the lower shield magnetic body and the MR element, and a lower layer magnetic gap is formed between the lower shield magnetic body and the MR element. An upper layer gap film is provided between the MR element and the upper shield magnetic body, and an upper layer magnetic gap is formed between the MR element and the upper shield magnetic body.

In the MR head having the above structure, when the magnetic gap length is narrowed (that is, the lower gap film is thinned) to improve the recording density, the lower shield magnetic body and the MR element are used. The magnetic interaction between the two becomes large, and instability of the head reproduction output is likely to occur.

Therefore, the applicant of the present application has previously proposed an MR head in which a groove is formed in a part of the lower shield magnetic body facing the MR element, and a nonmagnetic material is embedded in the groove. . Specifically, a part of the lower shield magnetic body facing the MR element is etched to form a groove, and a metal non-magnetic material such as Ti, Ta, Cu, or Ni is sputtered or plated in the groove. Embed by the method of. Then, it is flattened by polishing, and an MR element is formed on the flattened surface via a gap film.

According to the MR head having the above structure, by embedding the non-magnetic material in the groove, the facing distance between the MR element and the lower shield magnetic body increases, and as a result, the magnetic interaction is reduced, and the MR element is reduced. The bias magnetic field applied to is uniform.

When a metal non-magnetic material is used as the material for filling the groove, the lower shield magnetic body is also made of permalloy (Ni-Fe) or sendust (Fe-Si-Al).
As described above, since they are made of a magnetic metal material, their hardnesses are almost equal, and therefore the polishing rates of the lower shield magnetic body portion and the groove portion are substantially equal in the flattening step. Therefore, after polishing, there is no step at the boundary between the shield magnetic material portion and the groove portion, and the surface is flat.

[0009]

However, when the groove portion is filled with a metal non-magnetic material, the lower shield magnetic body is also made of a metal material. MR laminated via a film
It becomes difficult to secure insulation between the electrode connected to the element or the MR element and the lower shield magnetic body.

The metal non-magnetic material is embedded in the groove by high-speed polishing using diamond as abrasive grains,
Due to the two stages of low speed polishing using SiO ₂ ,
It takes extra time to polish. Further, when the diamond abrasive grains are used, there is a problem that it is difficult to obtain the surface roughness after polishing due to the scratches caused by the diamond abrasive grains or the abrasive grains themselves being pierced.

Therefore, the present invention has been proposed in view of the above-mentioned problems of the prior art, and it is an object of the present invention to provide an MR head having a high head reproducing output capable of ensuring insulation between the MR element and the lower shield magnetic body. To aim.

A further object of the present invention is to provide a method for manufacturing an MR head which has a flat surface of a gap film forming an MR element and has a very good surface roughness.

[0013]

The MR head of the present invention comprises:
An MR head having a so-called shield type structure in which an MR element is laminated on a lower shield magnetic body via a lower layer gap film, and an upper shield magnetic body is laminated on this MR element via an upper layer gap film. . In this MR head, the above-mentioned problem is solved by forming a groove in the lower shield magnetic body and embedding a nonmagnetic oxide insulating film in this groove.

The groove portion is formed at least rearward of the depth zero position of the magnetic gap with respect to the contact surface with the magnetic recording medium. Further, the shape of the groove is such that the groove opening width is wider than the groove bottom width. Further, the width of the groove portion in the depth direction of the magnetic gap is preferably 20 μm or less.

As the non-magnetic oxide insulating film embedded in the groove, it is desirable to use, for example, an Al ₂ O ₃ film having excellent insulating properties.

The surface roughness of the lower gap film on which the MR element is formed is preferably 1 nm or less in terms of center line average roughness Ra.

On the other hand, in order to manufacture the MR head, after forming a groove in the lower shield magnetic body, a nonmagnetic oxide insulating film is formed on the lower shield magnetic body including the groove. Next, the nonmagnetic oxide insulating film is polished by a mechanochemical polishing means to expose the lower shield magnetic body, and the groove is filled with the nonmagnetic oxide insulating film. Subsequently, after forming a lower layer gap film on the lower shield magnetic body, the lower layer gap film is polished by a mechanochemical polishing means to a predetermined film thickness. Then, a magnetoresistive effect element is formed on the polished lower layer gap film, and the upper layer gap film and the upper shield magnetic body are laminated on the magnetoresistive effect element with an insulating film interposed therebetween.

When forming the non-magnetic oxide insulating film,
It is desirable to form an Al ₂ O ₃ film.

[0019]

In a shield type MR head having an MR element sandwiched between a lower shield magnetic body and an upper shield magnetic body, a groove portion is formed in the lower shield magnetic body, and a non-metal nonmagnetic oxide insulating film is embedded in the groove portion. Therefore, the insulation between the lower shield magnetic body and the MR element formed on the lower shield magnetic body via the lower gap film or the electrode connected to the MR element and the lower shield magnetic body is enhanced, and a short circuit occurs between them. Is avoided in advance. In particular, when an Al ₂ O ₃ film having excellent insulating properties is used as the non-magnetic oxide insulating film, the magnetic interaction between the two becomes smaller.

On the other hand, in the method of manufacturing the MR head,
After forming a groove on the lower shield magnetic body and forming a non-magnetic oxide insulating film on the lower shield magnetic body including the groove, the non-magnetic oxide insulating film is exposed by the mechanochemical polishing means. If you polish until
The polished surface becomes smooth and has excellent surface roughness, and the non-magnetic oxide insulating film is embedded in the groove portion without a step. In particular, when this mechanochemical polishing means is used for polishing, an extremely smooth surface having a center line average roughness Ra of 1 nm or less can be obtained.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings. In this example,
The present invention is applied to a composite magnetic head in which a so-called inductive head, which is a recording head, is laminated on an MR head.

To manufacture the composite type magnetic head, first,
As shown in FIG. 1, on a substrate 1 called a slider made of Al ₂ O ₃ —TiC (so-called Altic material) or the like,
A film thickness of 10 μm for the purpose of insulating the substrate 1 and improving the surface property.
An Al ₂ O ₃ film 2 of m is formed by sputtering.

Next, the lower shield magnetic body 3 is formed on the Al ₂ O ₃ film 2. This lower shield magnetic body 3
Is, for example, permalloy (Fe-Ni) or sendust (F
e-Al-Si) and other magnetic materials having a film thickness of 1.5
It is formed by forming a film by a method such as sputtering or plating so as to have a thickness of μm to 3.0 μm, and then processing the film into a predetermined shape.

Next, as shown in FIG. 2, a lead electrode 4 having a predetermined wiring pattern for supplying a current to an MR element and a bias conductor, which will be described later, is formed on the Al ₂ O ₃ film 2 as a lower shield magnetic body. It is formed in the part that does not overlap 3. In addition,
The lead electrode 4 is formed by Cu pattern plating having a film thickness of 1.5 μm to 3.0 μm.

As a result, as shown in FIG. 3, Al ₂ O ₃
A lower shield magnetic body 3 having a predetermined shape and a lead electrode 4 having a predetermined wiring pattern are formed on the film 2 around the lower shield magnetic body 3.

Next, in order to flatten the lower shield magnetic body 3 and the lead electrode 4, as shown in FIG. 4, a flattening film 5 made of Al ₂ O ₃ is formed on the lower shield magnetic body 3 and the lead electrode ₃ to a thickness of 3 μm.
It is formed by sputtering so as to have a thickness of 6 μm.

Thereafter, the flattening film 5 is surface-polished by a mechanical polishing method using diamond abrasive grains. The surface is ground so that the MR element or the like to be laminated on the lower shield magnetic body 3 and the lower shield magnetic body 3 in the next step eliminate a short circuit or a disconnection defect due to a step or the like on the surface of the lower shield magnetic body 3. Is.

As shown in FIG. 5, planar polishing is carried out until the lower shield magnetic body 3 and the lead electrode 4 are exposed, and finally the thickness of the lower shield magnetic body 3 and the lead electrode 4 is 1 μm to 2.5 μm. Until it becomes.

Next, the lower shield magnetic body 3 and the MR described later.
A groove portion for reducing magnetic interaction with the element or the like is formed in a portion excluding a region where the lower layer reproducing magnetic gap is formed. That is, as shown in FIG. 6, in the region of the lower shield magnetic body 3 behind the depth zero position a of the lower layer reproducing magnetic gap with respect to the medium contact surface, in the longitudinal direction of the lower shield magnetic body 3. Then, predetermined patterning and etching (dry etching) are performed so as to form a straight groove having a substantially U-shaped cross section such that the opening width of the groove is gradually narrowed toward the bottom surface in a direction orthogonal to each other.

Regarding the shape of the groove portion 6, the groove bottom width W ₁ of the groove portion 6 is used for the purpose of flattening the MR element forming surface and increasing the surface roughness in the flattening step of the non-magnetic oxide insulating film described later. On the other hand, the groove opening width W ₂ is made wider, and the peripheral edges of the groove are provided with the inclined surfaces 6a and 6b.

Further, the groove opening width W ₂ in the depth direction of the reproducing magnetic gap is set to 20 μm or less. The depth H ₁ of the groove 6 is 0.5 μm to 1.0 μm in order to ensure reliable insulation between the lower shield magnetic body 3 and the MR element.
It is desirable to set the degree. Therefore, the film thickness H ₂ of the remaining lower shield magnetic body 3 in the groove portion 6 is 1 μm to
2 μm. The angles θ ₁ and θ ₂ formed by the inclined surfaces 6a and 6b and the flat surface 3a of the lower shield magnetic body 3 are preferably 45 degrees.

Next, as shown in FIG. 7, a nonmagnetic oxide insulating film 7 is formed on the lower shield magnetic body 3 including the groove portion 6. As the nonmagnetic oxide insulating film 7, for example, an Al ₂ O ₃ film having excellent insulating properties is suitable. To form such a non-magnetic oxide insulating film 7, it is formed by sputtering with Al ₂ O ₃ as a target.

The thickness of the nonmagnetic oxide insulating film 7 is set to be large so that at least the groove 6 is filled,
For example, it is about 600 nm to 800 nm.
As a result, the nonmagnetic oxide insulating film 7 is laminated on the lower shield magnetic body 3. The portion of the non-magnetic oxide insulating film 7 where the groove 6 is formed has a concave shape depending on the shape of the groove 6.

Next, by the mechanochemical polishing means,
The nonmagnetic oxide insulating film 7 is polished to fill the groove 6 with the nonmagnetic oxide insulating film 7. Mechanochemical polishing means is simply a polishing liquid in which colloidal silica (SiO ₂ ) ultrafine particles are dispersed in a weak alkaline solution, and a foaming polyurethane-based suede-type artificial leather polishing cloth made of polymer resin or the like. Is a method of polishing a substrate that is an object to be polished by combining the above.

According to such mechanochemical polishing, the surface roughness becomes the center line due to the interaction of the two by the combined polishing in which the mechanical polishing by the SiO ₂ abrasive grains in the polishing liquid and the chemical etching by the weak alkaline solution are combined. Mirror polishing with an average roughness Ra of about 1 nm or less is possible.

Further, in the mechanochemical polishing, it is possible to change the chemical polishing rate by changing the pH of the polishing liquid, and the abrasive grains in the polishing liquid are changed to, for example, diamond or ZrO ₂ . Alternatively, it is possible to change the mechanical polishing rate by changing the abrasive grain size or the abrasive grain concentration and change the overall polishing rate by changing the type of polishing cloth.

The optimum conditions for the mechanochemical polishing and the polishing apparatus will be described later in detail after explaining a series of steps in order to clarify the manufacturing process.

By this mechanochemical polishing, the nonmagnetic oxide insulating film 7 is planarly polished. Then, first, the convex portions of the nonmagnetic oxide insulating film 7 other than the groove portions 6 are polished,
Eventually, as shown in FIG. 8, it is ground to the same height as the concave portion of the portion facing the groove portion 6. After that, the polishing is performed without any step, and the polishing is performed until the lower shield magnetic body 3 is finally exposed.

As a result, the nonmagnetic oxide insulating film 7 is embedded only in the groove portion 6. When performing the mechanochemical polishing, the polishing speed ratio between the convex portion and the concave portion in the groove 6 is set by setting the optimum conditions such as the abrasive grain size, the polishing liquid concentration, and the polishing cloth described later and the groove shape under the above conditions. It becomes almost the same, and an extremely smooth polished surface without steps can be obtained.

Next, as shown in FIG. 10, a lower gap film 8 is formed on the lower shield magnetic body 3. The lower gap film 8, for imparting both functions of securing the function of the gap film, the insulation between the electrode connected to the MR element and this and the lower shield magnetic body 3, for example, Al ₂
It is desirable to use an O ₃ film. Here, since the lower gap film 8 is mechanochemically polished in the next step, it is formed thicker than a predetermined lower magnetic gap length.

Next, as shown in FIG. 11, the lower gap film 8 is flat-polished by mechanochemical polishing until it has a predetermined thickness. As a result, the polished surface 8a of the lower gap film 8 becomes the MR element formation surface. Since the MR element formation surface is polished by mechanochemical polishing,
No step is observed in the portion formed on the lower shield magnetic body 3 and the portion formed on the groove portion 6, and the surface is substantially uniform. Further, the MR element forming surface has an extremely smooth surface roughness with a center line average roughness Ra of 1 nm or less.

As described above, according to the mechanochemical polishing, high speed polishing using conventional diamond abrasive grains and S
Compared with low-speed two-step polishing using iO ₂ fine particles, problems such as polishing marks and scratches caused by using diamond grains can be avoided, and the polishing time is one step Can be significantly shortened. Further, since the lower gap film 8 after polishing has no unevenness and the polishing surface 8a is a flat surface,
The film thickness of the lower gap film 8 can be made extremely thin, and a narrow gap corresponding to high density recording can be achieved.

In this embodiment, the thickness of the lower gap film 8 is set to 100 nm or less in order to narrow the gap.

Next, contact holes (not shown) for electrically connecting the lead electrodes 4 are formed in the lower gap film 8. By this step, a structure having a predetermined gap length and having a sufficient distance between the MR element and the lower shield magnetic body 3 having a depth of zero or less to reduce the magnetic interaction is formed.

Then, as shown in FIG. 12, an MR element 9 is formed on the flattened lower gap film 8. M
To form the R element 9, permalloy (Fe—Ni) is formed into a film by sputtering or vapor deposition and then processed into a predetermined shape. In this embodiment, the thickness of the MR element 9 is 100 nm.
Below.

Next, as shown in FIG. 13, an insulating film 10 such as SiO ₂ is formed on the MR element 9 by sputtering in order to electrically insulate the MR element 9 from the bias conductor formed in the next step. To film. Then, as shown in FIG. 14, at the rear end 9a of the MR element 9 and the end of the lead electrode 4,
A part of the insulating film 10 is removed to form a contact hole 11 (a contact hole for a lead electrode is not shown) for electrical connection.

Then, as shown in FIG. 15, a bias conductor 12 for generating a bias magnetic field and a conductor 13 for flowing a sense current through the MR element 9 (hereinafter referred to as a rear end electrode 13) are formed. To do. The bias conductor 12 is
It is provided on the insulating film 10 at a position facing the MR element 9,
It is formed as a strip-shaped pattern perpendicular to the longitudinal direction of the MR element 9. On the other hand, the rear end electrode 13 is partially provided on the rear end edge side of the MR element 9 on the insulating film 10 and is electrically connected to the MR element 9 in the contact hole 11.

These bias conductor 12 and rear end electrode 13
Considering the adhesion between the insulating film 10 and the insulating layer formed in the next step, it is desirable to have a laminated film structure in which Ti / Cu / Ti is sputtered in this order. Of course, only Cu may be used if there is no problem of adhesion.

Next, as shown in FIG. 16, an insulating layer 14 such as SiO ₂ is sputtered in order to insulate the bias conductor 12 and the rear end electrode 13 from the upper shield magnetic body formed in a process described later. These bias conductors 12
And the rear end electrode 13 are completely laminated and formed.
Next, as shown in FIGS. 17 and 18, the insulating film 10 and the insulating layer 14 laminated on the tip portion 9a of the MR element 9 are removed, and the contact hole 15 exposing the tip portion 9a of the MR element 9 is removed. To form.

Next, as shown in FIG. 19, an upper gap film 16 is formed on the insulating layer 14 including the tip portion 9a of the MR element 9 facing the contact hole 15. The upper gap film 16 functions as a gap film and also functions as a tip electrode for passing a sense current to the MR element 9, and is therefore a metal film such as Ti.

Then, the upper shield magnetic body 17 is formed on the upper gap film 16. Upper shield magnetic body 17
Like the lower shield magnetic body 3, is formed by sputtering a metallic magnetic material. The forming method is the same as that of the lower shield magnetic body 3. As a result, as shown in FIG. 20, a shield type MR head, which is a reproducing head in which the MR element 9 is sandwiched between the lower shield magnetic body 3 and the upper shield magnetic body 17, is completed.

Next, an inductive head for recording is formed on the MR head. The inductive head formed here is a so-called three-pole structure composite magnetic head in which the upper shield magnetic body 17 of the MR head is used as one recording magnetic core.

In order to form the inductive head, first, as shown in FIG. 21, A is formed on the upper shield magnetic body 17.
The recording gap film 18 is formed by sputtering l ₂ O ₃ . Then, a part of the recording gap film 18 is removed to form a contact hole 19 for magnetically coupling a recording thin-film magnetic core (described later) and the upper shield magnetic body 17.
To form.

Next, in order to insulate the upper shield magnetic body 17 from the recording coil described later and to obtain a flat coil forming surface, the first flattening layer 20 made of an organic material is provided with the recording gap film 18. Form on top. Then, the recording coil 21 is spirally formed on the first flattening layer 20 by patterning Cu.

Next, in order to insulate the recording coil 21 from a recording thin-film magnetic core described later on the recording coil 21 and to obtain a flat magnetic core formation surface, a second organic material is used. The flattening layer 22 is formed on the first flattening layer 20 and the recording coil 21. Next, the other recording thin-film magnetic core 23 is plated or sputtered with a magnetic material such as permalloy on the second flattening layer 22, and then processed into a predetermined shape to complete the inductive head.

Then, on the recording thin-film magnetic core 23, a protective film 2 made of Al ₂ O ₃ or the like is provided for protecting the element.
4 is formed. Next, a connection terminal to an external circuit (not shown) is formed, and slider processing is performed to complete a composite magnetic head having a 3-pole structure.

In the composite magnetic head completed through the above steps, the lower layer reproducing magnetic gap g ₁ is formed between the lower shield magnetic body 3 and the MR element 9, and the upper shield magnetic body 17 and the MR element are formed. An upper reproducing magnetic gap g ₂ is formed between the upper layer and the upper layer 9. Then, a recording magnetic gap g ₃ is formed between the upper shield magnetic body 17 and the recording thin film magnetic core 23.

Next, the mechanochemical polishing apparatus and optimum conditions for performing the mechanochemical polishing will be described below together with experimental results. The mechanochemical polishing device is shown in FIG.
As shown in, the surface plate 25 that mainly functions as a polishing plate
And a swing mechanism 27 for swinging the substrate 26 placed on the surface plate 25 in the left-right direction.

On the surface of the surface plate 25, a polishing cloth 28 made of artificial artificial leather of polyurethane type, which has been soaked with a weak alkaline polishing liquid such as KOH, is attached.

A substrate 26 is placed on the surface plate 25. The substrate 26 is covered with the jig 2 for the purpose of guiding the substrate 26 or applying pressure to increase the polishing rate.
9 is provided.

The jig 29 has a recess 30 for fitting the substrate 26 on the surface facing the surface plate 25.
The depth of the recess 30 is shallower than the thickness of the substrate 26 so that the jig 29 is not polished by the surface plate 25. Therefore, when the substrate 26 is fitted into the recess 30 and placed on the surface plate 25, only the substrate 26 comes into contact with the polishing cloth 28 of the surface plate 25.

Since the substrate 26 and the jig 29 are not adhered by wax or an adhesive, warpage or undulation of the substrate due to adhesive distortion does not occur, and uneven wear of the substrate 26 occurs during polishing. Does not occur.

On the other hand, the swinging mechanism 27 includes a holding portion 31 formed of a shaft for holding the jig 29 rotatably in the X direction in the figure, and the holding portion 31 along the center line of the surface plate 25. It is composed of an electric motor 32 that functions as a drive source for rocking in the left-right direction indicated by an arrow M, a cam 33 that converts the rotational motion of the electric motor 32 into a rocking motion, a crankshaft 34, and a slider 35.

The holding portion 31 is connected to a slider 35 for swinging the holding portion 31 in the left-right direction via a support body 36 and a spindle rod 37. The slider 35 is provided with a cam 33 and a crankshaft 34 for converting the rotary motion of the electric motor 32 into a swing motion. Therefore, the rotational movement of the electric motor 32 is transmitted to the cam 33 and converted into swinging movement by the crankshaft 34 engaging with the cam 33. As a result, the holding portion 31 swings in the left-right direction.

When performing the mechanochemical polishing using the mechanochemical polishing apparatus configured as described above,
While rotating the surface plate 25, the electric motor 32 is driven to swing the substrate 26. Then, the substrate 26 is polished over the entire substrate 26 by the rotational movement of the surface plate 25 and the swinging movement of the holding portion 31. The rotation of the substrate 26 is
For example, it is about 60 rpm.

When the substrate 26 is not rocked,
Due to the peripheral speed difference between the inner and outer peripheries of the substrate 26, uneven wear occurs in the central portion of the substrate 26.

Then, using the mechanochemical polishing apparatus having the above structure, the optimum conditions for mechanochemical polishing for filling the nonmagnetic oxide insulating film 7 in the groove 6 were investigated as follows.

Experiment 1 In this experiment, changes in the surface roughness of the Al ₂ O ₃ film when the particle size of SiO ₂ in the polishing liquid was changed were examined. FIG. 23 shows SiO in a weak alkaline polishing liquid having a pH of about 10.
₂ shows the surface roughness Ra of the Al ₂ O ₃ film after polishing when the particle diameter of the ₂ abrasive grains (abrasive grain concentration: about 10 wt%) was changed. Particle size is 10nm, 50n
m and 100 nm. The polishing cloth is a foamed polyurethane suede type, the polishing surface pressure is 120 g / cm ² ,
The polishing amount was fixed at 50 nm. The material to be polished is Al ₂ O
It is ₃ membranes.

As can be seen from the results of this experiment, the smaller the particle size, the smaller the surface roughness and the particle size of 5
A surface roughness Ra of 1 nm or less is achieved at 0 nm or less.

Experiment 2 In this experiment, changes in the surface roughness of the Al ₂ O ₃ film when the length of the bristles of the foamed polyurethane suede, which is the polishing cloth, were changed were examined. FIG. 24 shows a SiO ₂ particle size of 50.
nm, SiO ₂ Abrasive Grain Concentration: Al ₂ O ₃ after polishing when a length of hair of suede of a foamed polyurethane suede type polishing cloth is changed by using a weak alkaline polishing solution having a pH of about 10 at about 10 wt%. The surface roughness Ra of the film is shown. Suede hair length is 0.9 μm, 0.
There are three types, 66 μm and 0.6 μm. Polishing surface pressure is 12
The polishing amount was 0 g / cm ² and the polishing amount was 50 nm. The material to be polished is an Al ₂ O ₃ film.

As can be seen from the results shown in FIG. 24, the surface roughness is 1 n for any suede hair length of any polishing cloth.
m or less is achieved, and the polishing liquid and the material to be polished are Al ₂ O ₃
There is no problem with the combination of membranes.

Experiment 3 In this experiment, a change in the polishing rate ratio when the size of the groove formed in the lower shield magnetic body was changed was examined. FIG. 25 shows a magnetic gap after polishing when the pattern width (area) of the groove is changed by using a weak alkaline polishing liquid having a SiO ₂ particle diameter of 50 nm and a SiO ₂ abrasive grain concentration of about 10 wt% around pH 10. shows the relationship between the Al ₂ O ₃ film polishing rate ratio of the layer and the groove (polishing rate of the Al ₂ O ₃ film polishing rate / groove of the Al ₂ O ₃ film of the magnetic gap layer). The pattern shape of the groove is elliptical, and the groove width is 12 μm from the depth zero position in the direction opposite to the medium sliding surface,
There are five types, 15 μm, 30 μm, 40 μm, and 50 μm. The polishing cloth is foamed polyurethane suede type, and the polishing surface pressure is kept constant at 120 g / cm ² .

As can be seen from the results of this experiment, the width of the groove
The smaller is the polishing rate ratio, the greater is the polishing rate of the groove.
Becomes smaller. At this time, the length of the suede bristles on the polishing cloth
Is about 0.9 μm. In addition, the pattern width of the groove is 50
μm (15.7 × 10 in area ³μm²) Polishing speed
The degree ratio is about 1.0, while the pattern width of the groove is
12 μm (252 μm in area²The polishing rate ratio for
It will be as large as 4.5. The value of the polishing rate ratio is large
The further it is, the more difficult the groove is to be polished.

Experiment 4 In this experiment, the change in the polishing rate ratio when the length of the bristles of the foamed polyurethane suede, which is the polishing cloth, was changed was examined. In FIG. 26, the SiO ₂ particle size is 50 nm and the S
iO ₂ Abrasive Grain Concentration: About 10 wt% of a weak alkaline polishing liquid having a pH of about 10 was used to change the magnetic gap layer and the Al ₂ O ₃ film in the groove portion after polishing when the length of the foamed polyurethane suede hair was changed. The relationship between polishing rate ratios (the same as in Experiment 3) is shown. Suede hair length is 0.9μ
m, 0.66 μm, and 0.6 μm. Polishing surface pressure is 120 g / cm ² , pattern width of groove is 15 μm
The area was kept constant at 2.2 × 10 ³ μm ² .

As can be seen from the results of FIG. 26, the shorter the suede bristles of the polishing cloth, the higher the polishing rate ratio, and the more difficult the groove is to be polished. Suede hair length is 0.6μm
The polishing rate ratio becomes about 6.0.

From the results of Experiments 1 to 4, the following can be said. When the polishing rate ratio is large, a step or the like on the MR element formation surface is reduced when the MR element is formed in the next step.
If there is a step on the MR element formation surface, a magnetically discontinuous layer is generated in the MR element, which causes a problem such as a decrease in magnetic permeability. To solve this, in the groove, the convex portion of the step after the Al ₂ O ₃ film is formed is first removed by polishing at the initial stage of polishing until the step disappears, and the Al ₂ O ₃ film in the groove is started from there. Is preferably a polishing process in which is removed at the same polishing rate as other portions. At that time, the pattern shape of the groove formed in the lower shield magnetic body is changed in various sizes from the depth zero position in the direction opposite to the medium sliding surface, and the length of the suede bristles on the polishing cloth surface is changed. It is possible to control the polishing rate ratio of the step in the groove by changing the thickness.

Specifically, the optimum polishing conditions for the mechanochemical polishing are as follows.
A combination of weak alkaline such as OH, a SiO ₂ particle diameter of about 50 nm, a SiO ₂ abrasive grain concentration of about 10 wt%, and a polishing cloth of a foamed polyurethane type suede type artificial leather is preferable. The pattern width (area) of the groove is 20 μm or less in the direction opposite to the medium sliding surface from the depth zero position, and the length of suede bristles on the surface of the polishing cloth is 0.7 μm or less.

Under the above conditions, if the non-magnetic oxide insulating film is mechanochemically polished and the non-magnetic oxide insulating film is embedded in the groove, the thickness of the magnetic gap layer (lower gap film) and M
It is possible to control the flatness of the R element formation surface (the surface of the lower gap film) and its surface roughness Ra with a precision of 1 nm or less. Further, by using an oxide insulating film such as an Al ₂ O ₃ film instead of a metal film as a material to be embedded in the groove,
The insulation between the lower shield magnetic body and the MR element or the electrode connected to the MR element can be improved. Further, since the non-magnetic oxide insulating film serves as a magnetic interaction reducing layer, the characteristics of the MR element are improved and the head reproduction output is improved.

[0079]

As is apparent from the above description, in the MR head of the present invention, since the groove portion is formed in the lower shield magnetic body and the nonmagnetic oxide insulating film is embedded in the groove portion, the lower shield magnetic material is formed. It is possible to improve the insulation between the lower shield magnetic body and the MR element formed on the body through the lower gap film or the electrode connected to the MR element, and reduce the magnetic interaction between them. , It is possible to avoid the occurrence of short circuit between them.

In particular, if an Al ₂ O ₃ film having an excellent insulating property is used as the non-magnetic oxide insulating film, the insulating property between the MR element or the electrode connected to the MR element and the lower shield magnetic body can be made more reliable. Therefore, the reliability between the two can be significantly improved.

On the other hand, in the method of manufacturing the MR head,
When embedding a non-magnetic oxide insulating film in the groove formed in the lower shield magnetic body, mechanochemical polishing is performed with the optimal combination of the groove pattern shape and polishing conditions, so the polishing rate ratio at the step of the concave pattern in the groove is It can be controlled with high precision. Further, the thickness of the non-magnetic oxide insulating film and the thickness of the magnetic gap layer in the groove can be controlled with high accuracy, and the surface roughness of the MR element formation surface is Ra of 1 nm or less, which is an extremely smooth surface. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a step of forming a lower shield magnetic body, showing the manufacturing steps of an MR head in order.

FIG. 2 is a cross-sectional view showing a lead electrode forming step, showing the manufacturing steps of the MR head in order.

FIG. 3 is a plan view showing a lead electrode forming step, showing the manufacturing steps of the MR head in order.

FIG. 4 is a cross-sectional view showing a step of forming a flattening film, showing the manufacturing steps of the MR head in order.

FIG. 5 is a cross-sectional view showing a flattening step, showing the manufacturing steps of the MR head in order.

FIG. 6 is an enlarged cross-sectional view of an essential part showing a step of forming a groove in the lower shield magnetic body, showing the manufacturing steps of the MR head in order.

FIG. 7 is an enlarged sectional view of an essential part showing a step of forming a non-magnetic oxide insulating film, showing the manufacturing steps of the MR head in order.

FIG. 8 is a fragmentary enlarged cross-sectional view showing a step of polishing the step portion in the groove in the step of polishing the nonmagnetic oxide insulating film by mechanochemical polishing, showing the manufacturing steps of the MR head in order.

FIG. 9 is a fragmentary enlarged cross-sectional view showing a state in which a groove is filled with a non-magnetic oxide insulating film by mechanochemical polishing, showing the manufacturing steps of the MR head in order.

FIG. 10 is a fragmentary enlarged cross-sectional view showing a step of forming a lower layer gap film, showing the manufacturing steps of the MR head in order.

FIG. 11 is a fragmentary enlarged cross-sectional view showing a step of polishing the lower gap film by mechanochemical polishing, showing the manufacturing steps of the MR head in order.

FIG. 12 is a flow chart showing the manufacturing process of the MR head in sequence.
It is a principal part expanded sectional view which shows a R element formation process.

FIG. 13 is a cross-sectional view showing an insulating film forming step, which sequentially shows the manufacturing steps of the MR head.

FIG. 14 is a cross-sectional view showing a step of forming a contact hole, showing the step of manufacturing the MR head in order.

FIG. 15 is a cross-sectional view showing a step of forming a bias conductor, showing the manufacturing steps of the MR head in order.

FIG. 16 is a cross-sectional view showing an insulating layer forming step in the order of manufacturing steps of the MR head.

FIG. 17 is a cross-sectional view showing a step of forming a contact hole, showing the manufacturing steps of the MR head in order.

FIG. 18 is a plan view showing a step of forming a contact hole, showing the manufacturing steps of the MR head in order.

FIG. 19 is a cross-sectional view showing the manufacturing process of the MR head in order and showing the upper shield magnetic body forming process.

FIG. 20 is a plan view showing the manufacturing process of the MR head in sequence and showing the upper shield magnetic body forming process.

FIG. 21 is an enlarged cross-sectional view of a main part of a composite magnetic head in which an inductive head is laminated on an MR head.

FIG. 22 is a front view showing a schematic configuration of a polishing apparatus.

FIG. 23 shows SiO ₂ particle size and Al ₂ O in the polishing liquid.
FIG. ₃ is a characteristic diagram showing the relationship between _three film surface roughnesses.

FIG. 24 is a characteristic diagram showing the relationship between the suede bristle length of the polishing cloth and the surface roughness of the Al ₂ O ₃ film.

FIG. 25 is a characteristic diagram showing the relationship between the groove pattern width and the polishing rate ratio.

FIG. 26 is a characteristic diagram showing a relationship between a suede bristle length of a polishing cloth and a polishing rate ratio.

[Explanation of symbols]

 1 Substrate 3 Lower Shield Magnetic Material 4 Lead Electrode 6 Groove 7 Nonmagnetic Oxide Insulating Film 8 Lower Gap Film 9 MR Element 12 Bias Conductor 13 Rear End Electrode 17 Upper Shield Magnetic Material 23 Thin Film Magnetic Core for Recording

Claims (8)

[Claims] 1. A magnetic structure in which a magnetoresistive effect element is laminated on a lower shield magnetic body via a lower layer gap film, and an upper shield magnetic body is laminated on this magnetoresistive effect element via an upper layer gap film. A magnetoresistive effect magnetic head, characterized in that a groove portion is formed in a lower shield magnetic body, and a nonmagnetic oxide insulating film is embedded in the groove portion. 2. The magnetoresistive head according to claim 1, wherein the non-magnetic oxide insulating film is an Al ₂ O ₃ film. 3. The surface roughness of the lower gap film has a center line average roughness Ra of 1 nm or less.
Alternatively, the magnetoresistive effect magnetic head as described in 2 above. 4. The groove portion is formed at least rearward of the depth zero position of the magnetic gap with respect to the surface facing the magnetic recording medium. 2. A magnetoresistive magnetic head according to item 1. 5. The magnetoresistive head according to claim 1, wherein the groove has a groove opening width wider than a groove bottom width. 6. The magnetoresistive head according to claim 1, wherein an opening width of the groove portion in the depth direction of the magnetic gap is 20 μm or less. 7. A step of forming a groove portion on the lower shield magnetic body, a step of forming a nonmagnetic oxide insulating film on the lower shield magnetic body including the groove portion, and a nonmagnetic oxide insulating film by a mechanochemical polishing means. To expose the lower shield magnetic body and bury a nonmagnetic oxide insulating film in the groove, a step of forming a lower layer gap film on the lower shield magnetic body, and a step of mechanically polishing the lower layer gap film by a mechanochemical polishing means. A step of polishing to a predetermined film thickness, a step of forming a magnetoresistive effect element on the polished lower layer gap film, an upper gap film and an upper shield magnetic body on the magnetoresistive element via an insulating film And a method of manufacturing a magnetoresistive effect magnetic head, the method including: 8. The method of manufacturing a magnetoresistive effect magnetic head according to claim 7, wherein an Al ₂ O ₃ film is formed as the non-magnetic oxide insulating film.