JPH10334412A - Thin film magnetic head and magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic head capable of reducing the warpage of a substrate caused by the inner stress of an insulated film. SOLUTION: A first insulated film 9, magnetic recording/reproducing elements 90 and 91 and a second insulated film 3 are provided in sequence on a substrate 17. At least one of the first and second insulated films 9 and 3 includes a film 7 where inner stress is tensile stress. Normally, since compressive stress occurs in the insulated film of the magnetic head, the film 7 of tensile stress and the film of compressive stress in the other part counter each other and thus the warpage of the substrate is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a thin-film magnetic head used in a magnetic disk drive.

[0002]

2. Description of the Related Art A method for manufacturing a thin film magnetic head is disclosed in
The methods described in 76013 and JP-A-3-80410 are known. The configuration and manufacturing method of a general thin-film magnetic head will be described with reference to FIGS. 7, 8, and 9. FIG.

First, as shown in FIGS. 8 and 9, an insulating film (called an undercoat) 9 is formed on the surface of a wafer-like substrate 17 made of a slider material, and a sputtering mask is formed and etched thereon. The magnetic recording / reproducing elements 90 and 91 such as coils are formed by a thin film process represented by, for example, and an insulating film (called overcoat) 3 is formed thereon to protect the elements 90 and 91 (step 811). ). Further, an external connection terminal 71 is formed thereon.

[0004] The wafer-like substrate 17 on which the magnetic recording / reproducing elements 90 and 91 are formed is cut into a row bar 8 using a diamond grindstone (step 812). The row bar 8 has a shape in which a plurality of magnetic heads are arranged horizontally. Next, the surface of the row bar 8 serving as the air bearing surface of the magnetic head is polished by lapping, the tip of the magnetic recording element exposed on the air bearing surface is processed by a predetermined amount, and the air bearing surface is processed into a smooth plane (step 813). . Next, a jig to which the row bar 8 is fixed is inclined at a predetermined angle with respect to the polishing platen and polished, thereby forming a taper 6 having a predetermined angle at a portion serving as an inflow end of the floating surface of the magnetic head (step). 81
4).

[0005] Next, a mask having a predetermined shape is formed on the surface of the row bar 8 serving as a floating surface, and a portion exposed from the mask is processed by a predetermined amount to form a floating surface rail 806 (step 815). Finally, the row bar 805 is cut with a diamond grindstone, and the magnetic heads are separated one by one, thereby completing the magnetic head having the shape shown in FIG. 7 (Step 816).

As described above, in the element forming step 811,
Two insulating films 9 and 3 are formed. These are usually Al
_Although the same material such as ₂ O ₃ is formed by a sputtering process, these insulating films 9 and 3 generate internal stress (generally, compressive stress) at the time of film formation, so that the magnetic recording element and the insulating film are formed. The substrate 17 is warped due to the internal stress of the insulating films 9 and 3. For this reason, when the substrate 17 is cut into the row bar 8, a warp S occurs on the end surface of the row bar 8 as shown in FIG. 2.

[0007]

In recent years, magnetic heads have
It tends to be smaller. For example, the slider size is currently 2 × 1.6 × 0.4 mm (50% slider)
Slider size is the mainstream, but 1.2 × 1.0 ×
It is shifting to 0.3 mm (30% slider) and is expected to be 1.0 × 0.8 × 0.2 mm (10% slider) in the future. As the size of the magnetic head is reduced, the thickness of the row bar 8 becomes thinner. Therefore, when the length of the row bar 8 is the same, the rigidity of the row bar 8 against bending stress also decreases. Therefore, as shown in Table 1, the warpage S in the direction of the end face of the row bar 8 tends to increase. In addition, the length of the row bar 8 tends to be increased in order to improve the throughput. Since the rigidity of the row bar 8 against bending is inversely proportional to the cube of the length of the row bar, when the length of the row bar is doubled, the rigidity of the row bar against bending decreases to 1/8. Therefore, if the internal stress of the insulating film is the same, the warpage S in the direction of the end face of the row bar becomes eight times.

[0008]

[Table 1]

As described above, the warpage S of the row bar 8 in the end face direction is obtained.
The following problem arises when is larger.

(1) If the row bar 8 has a warp S in the end face direction, the width B (FIG. 3) of the taper 6 becomes narrow at the center of the row bar 8 as shown in FIG. A variation B 'occurs in the width. If the warpage S of the row bar 8 in the end face direction increases, the taper width variation B 'also increases. This taper 6 is
Since the elevation angle θ (FIG. 6) of the magnetic head floating above is set, if the taper width varies, the elevation angle θ of each slider varies.

(2) The air bearing surface rail 806 is formed by ion milling after forming a mask of a predetermined shape on the air bearing surface of the row bar 8 as in step 815 of FIG. At this time, if the row bar 8 has a warp S in the direction of the end face, this causes a variation P in the positional relationship between the floating surface rail 806 and the end face of the slider as shown in FIG. The variation P in the position of the flying surface rail causes a variation in the flying height h (FIG. 6) depending on each magnetic head.

As described in (1) and (2) above, variations in the elevation angle θ and the flying height h of the magnetic head affect the flying height h of the magnetic head. If the flying height is too small, the disk 5 rotating at high speed and the magnetic head 1 are likely to come into contact with each other. When the magnetic disk 5 and the magnetic head 1 come into contact with each other, noise may be generated in a reproduced signal, and a failure may be caused. On the other hand, if the flying height is too large,
Since the reproduction efficiency is reduced, data reading failure is likely to occur, and the reliability of the magnetic disk device is reduced.

Japanese Patent Application Laid-Open No. 6-76244 discloses that, in order to compensate for distortion of a substrate due to film stress of a protective film of a magnetic head, a compressive stress is generated by processing a back surface of a substrate into a rough surface, thereby forming a film. Methods for antagonizing stress are described. Japanese Patent Application Laid-Open No. 3-113817 describes a method of forming an insulating film having the same film configuration as the upper surface on the back surface of the substrate in order to prevent the substrate from warping due to the insulating film of the magnetic head.

However, the method described in Japanese Patent Application Laid-Open No. 3-113817 discloses two methods of undercoat and overcoat.
A film composed of layers and having the same configuration as the thick insulating film must be formed on the rear surface of the substrate, which is costly.

A method of reducing the stress of the insulating film by changing the film forming conditions and a method of reducing the stress of the insulating film by reducing the thickness of the insulating film are conceivable. Is likely to be unstable, resulting in a problem that insulation properties are reduced.

An object of the present invention is to provide a magnetic head capable of reducing the warpage of a substrate due to the internal stress of an insulating film.

[0017]

According to the present invention, in order to achieve the above object, a first insulating film,
A thin-film magnetic head comprising a magnetic recording / reproducing element and a second insulating film, wherein at least one of the first and second insulating films includes a film having an internal stress of tensile stress.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.

First, the structure of the magnetic head according to the first embodiment of the present invention will be described with reference to FIG.

In the present embodiment, the overcoat of the magnetic recording / reproducing element has a two-layer structure, one layer being a film having a compressive stress, and the other being a film having a tensile stress. As a result, the film thickness of the compressive stress film becomes thinner than the case where the entire overcoat is formed of a compressive stress film, so that the amount of warpage caused by the compressive stress can be reduced. Since a tensile stress film can be partially introduced, the compressive stress and the tensile stress can be balanced without increasing the thickness of the film formed on the substrate.

More specifically, as shown in FIG. 10, an insulating film (called an undercoat) 9, a magnetic reproducing element 90, and a magnetic recording element 9 are sequentially formed on the surface of a substrate 17 made of a slider material.
1. An insulating film (called overcoat) 3 is formed. The magnetic reproducing element 90 is an element for reading data from a magnetic disk, and includes a lower shield film 10, an MR element 12 sandwiched between insulating films, and an upper shield film 11. The magnetic recording element 91 is an element for writing data on a magnetic disk, and includes the coil 13 and the upper magnetic film 14.

The overcoat 3 is made of a compressive stress film 103.
And two layers of the tensile stress film 7. In this embodiment, the material of the compressive stress film 103 of the undercoat 9 and the overcoat 3 is Al ₂ O _3, which is generally used as an insulating film of a magnetic head, and the film forming method is sputtering. When Al ₂ O ₃ is formed by sputtering, it generally has a compressive stress as is well known. The material of the tensile stress film 7 of the overcoat 3 was polyimide, which is an organic insulating material. The film formation method is
A method of baking after application by spin coating was adopted.

The thickness of the undercoat 9 is 10 μm.
m, the thickness of the overcoat 3 is 1
0 μm, and the tensile stress film 7 was about 15 μm.

Next, a method of manufacturing the magnetic head according to the first embodiment will be described with reference to FIG.

The undercoat film 9 is formed on the surface of the wafer-like substrate 17 by Al ₂ O ₃ to a thickness of about 10 μm by sputtering.
m (Step 1101). Next, on the undercoat film 9, a lower shield film 10, an MR element 12, an upper shield film 11, a coil 13, and an upper magnetic film 13 sandwiched between insulating films are sequentially formed by sputtering, mask formation, etching, and the like. It is formed using a thin film manufacturing technique (step 1102). A compressive stress film 103 of the overcoat 3 is formed on the upper magnetic film 13 by sputtering using Al ₂
O ₃ is formed to a thickness of about 10 μm (step 1103).
Next, polyimide is applied to the surface of the compressive stress film 103 to a thickness of about 6 to 8 μm by spin coating.
Is baked at a low temperature (intermediate baking) to evaporate the solvent in the polyimide (steps 1104 and 1105). On top of this,
Again, polyimide is applied by spin coating to make the overall thickness of the polyimide 13 to 16 μm (step 11).
06). The substrate 17 is baked at a high temperature and the polyimide is solidified, so that the tensile stress layer 7 of the overcoat 3 is formed.
To form On this, terminals for external connection are formed (Step 1108). Thus, the magnetic recording / reproducing elements 90 and 91 sandwiched between the undercoat 9 and the overcoat 3 are formed on the wafer-like substrate 17. Thereafter, the magnetic head slider is completed by performing a machining process (step 1109) consisting of steps 812 to 816 in FIG.

The magnetic head of the first embodiment manufactured as described above has a compression stress film 103 of the overcoat 3.
The film thickness of the conventional overcoat is the same as the compressive stress of Al.
_Since the thickness is reduced to about 1/4 as compared with the film thickness (normally 40 μm) formed of a ₂ O ₃ film, the amount of warpage due to compressive stress can be reduced as compared with the conventional case. Further, a tensile stress is introduced by forming a part of the overcoat 3 as a tensile stress film 7. This makes it possible to antagonize the tensile stress of the tensile stress film 7 with the sum of the compressive stress of the undercoat 9 and the compressive stress film 103, so that the insulating property of the overcoat 3 is not reduced, and The warpage of the substrate 17 can be reduced without increasing the thickness of the substrate 3.

Specifically, Table 2 shows the measurement results of the warpage of the substrate of the magnetic head of the first embodiment and the warpage of the substrate of the conventional magnetic head. However, in the conventional magnetic head used for comparison, the entire undercoat film 9 and overcoat film 3 are formed of Al ₂ O ₃ , and the thicknesses of the films are 10 μm and 40 μm, respectively.

[0028]

[Table 2]

As shown in Table 2, in the magnetic head of this embodiment, the warpage of the substrate 17 in the wafer state is set to 3 to 10 μm.
The warpage S (FIG. 2) in the row bar end face direction after cutting is 1 to 3 μm.
m. On the other hand, in the conventional magnetic head, the warpage of the substrate in the wafer state is 40 to 60 μm, and the warpage S in the direction of the end surface of the row bar after cutting is 8 to 15 μm. It is clear that warpage can be reduced.

Further, in the magnetic head of the present embodiment, in the row bar of the 30% slider having the size shown in Table 1, the variation B 'of the taper width and the displacement P of the air bearing surface rail are shown.
Can be suppressed to 5 μm or less, so that the variation in the flying height can be reduced.

In the above-described first embodiment, polyimide is used as the tensile stress film 7, but SiO ₂ ,
An oxide insulating film of Ta ₂ O ₅ or the like formed under sputtering conditions in which internal stress becomes tensile stress can also be used.

In the first embodiment described above, the upper part of the overcoat 3 is formed of a tensile stress film. However, the entire overcoat 3 may be formed of a tensile stress film, or the overcoat 3 may be formed of a tensile stress film. It is of course possible to form part or all of 9 with a tensile stress film.

Next, a magnetic head according to a second embodiment of the present invention will be described. In the second embodiment, a compressive stress is generated by forming a processing mark on the end surface of the inflow end of the magnetic head (the surface on the back side of the substrate surface on which the magnetic recording / reproducing element is formed) by machining. Antagonizes the compressive stress of the undercoat and overcoat.

As a method of forming a processing mark, grinding using a diamond grindstone as a tool is suitable. By using the grinding process, it is possible to process in a wafer state, and since the processing time is several minutes, the throughput in forming a processing mark is very high.

In the grinding process, compressive stress is reduced depending on the processing conditions.
Control is required. Then cut
The speed was changed, and the amount of warpage of the wafer at that time was measured. So
FIG. 12 shows the results. However, the grinding conditions are as follows
It is. In addition, the wafer used for grinding is as shown in FIG.
Undercoat 9 and magnetic recording / reproducing element 9 on substrate 17
0, 91 and overcoat 3 were formed. Base
The material of the plate 17 is Al_TwoO_Three-TiC. Underco
The coating film 9 and the overcoat film 3 are made of Al_TwoO _ThreeFormed with
The thickness of each film is 10 μm, 40 μm
It is.

Processing method: Infeed grinding Grinding wheel: SD800N100M Grinding wheel rotation speed: 2500 r / min Workpiece shaft rotation speed: 300 r / min Cutting speed: 10 to 100 μm / min From FIG. If close, 52μ
Although the amount of warpage of m occurs, it can be seen that the amount of warpage decreases as the cutting speed increases. This is considered to be because, in the grinding process, when the cutting speed is increased, the grinding force at the time of machining increases, and the compressive stress also increases.

The above conditions (cutting speed: 100 μm / mi)
Table 3 shows the result of grinding the back surface of the substrate according to n).

[0038]

[Table 3]

As shown in Table 3, the back surface of the wafer is ground and a compressive stress is applied to reduce the warpage of the wafer by one.
The warp S in the direction of the end face of the row bar after cutting could be set to 2 to 25 μm and 2 to 10 μm. As a result, in the row bar of the 30% slider having the size shown in Table 1, the variation B 'of the taper width and the displacement P of the air bearing surface rail can be suppressed to 15 μm or less.

When the back surface of the substrate is ground, either of the two processes shown in FIGS. 13A and 13B can be used. In the process (a), the undercoat 9, the magnetic recording / reproducing elements 90 and 91, and the overcoat 1303 are formed on the wafer-like substrate 17 (steps 1301 to 1303). Grinding is performed (step 1304). Then, as in the conventional process, the substrate is cut into row bars,
After the air bearing surface is polished to form a taper and a floating surface rail is formed, the row bar is cut, and the magnetic heads are cut off one by one to complete the magnetic heads (steps 1305 to 1309).

On the other hand, in the process (b), the wafer-shaped back surface is ground before film formation (step 131).
1) After that, the undercoat 9, the magnetic recording / reproducing elements 90 and 91, and the overcoat 1303 are formed on the substrate 17, the substrate 17 is cut into row bars, the floating surface is polished, and a taper is formed. After the rails are formed, the row bars are cut, and the magnetic heads are cut off one by one to complete the magnetic heads (steps 1312 to 131).
9).

In both processes, substrate warpage (warpage in the direction of the end surface of the row bar) can be reduced without any particular problem.

Finally, a CSS (Contact Sta) using the magnetic heads of the first and second embodiments described above.
The configuration of an (rt Stop) type magnetic disk drive will be described with reference to FIG.

The magnetic head 1 is fixed near the tip of the leaf spring 15 such that the air bearing surface rail 806 contacts the magnetic disk 5. The other end of the leaf spring 15 is
6 attached. The actuator 16 moves the magnetic head 1 in the radial direction of the magnetic disk 5. The magnetic disk 1 is rotationally driven by a rotation driving device (not shown). The magnetic head 1 flies by a very small amount from the surface of the disk 5 by the dynamic pressure generated by the rotation of the magnetic disk 5, and data is recorded / reproduced by the magnetic recording / reproducing elements 90 and 91 in the floating state.

The magnetic heads of the first and second embodiments are
Since the warpage of the substrate is reduced as described above, there is little variation in the position of the air bearing surface rail for each magnetic head,
The variation in Taber angle is also small. Therefore, when used in a magnetic disk device, the variation in the flying height of the magnetic head can be reduced, and the reliability of the magnetic disk device can be improved.

[0046]

As described above, according to the present invention,
It is possible to provide a magnetic head capable of reducing the warpage of the substrate due to the internal stress of the insulating film.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a magnetic disk drive using a magnetic head according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing warpage of a row bar in a conventional magnetic head manufacturing process.

FIG. 3 is a perspective view showing a state where a taper is formed on a row bar in a conventional magnetic head manufacturing process.

FIG. 4 is an explanatory view showing variations in the width of a taper formed on a row bar in a conventional magnetic head manufacturing process.

FIG. 5 is an explanatory view showing a variation in the position of a floating surface rail formed on a row bar in a conventional magnetic head manufacturing process.

FIG. 6 is an explanatory diagram showing an elevation angle of a conventional magnetic head.

FIG. 7 is a perspective view of a conventional magnetic head.

FIG. 8 is an explanatory view showing a manufacturing process of the magnetic head.

FIG. 9 is an enlarged sectional view of a conventional magnetic head.

FIG. 10 is an enlarged sectional view of the magnetic head according to the first embodiment of the present invention.

FIG. 11 is an explanatory diagram illustrating a manufacturing process of the magnetic head according to the first embodiment.

FIG. 12 is a graph showing the relationship between the warpage of the substrate of the magnetic head according to the second embodiment of the present invention and the cutting speed in the step of grinding the back surface of the substrate.

FIG. 13 is an explanatory view showing a manufacturing process of the magnetic head according to the second embodiment of the invention.

[Explanation of symbols]

1: magnetic head, 3: insulating film (overcoat), 5:
Magnetic disk, 6 ... taper, 8 ... row bar, 9 ... insulating film (undercoat), 10 ... lower shield film, 11 ...
Upper shield film, 12: MR element, 13: coil, 14
... upper magnetic film, 15 ... leaf spring, 16 ... actuator,
17: substrate, 90: magnetic reproducing element, 91: magnetic recording element, 806: air bearing surface rail.

Continued on the front page (72) Inventor Takashi Shibazaki 2880 Kozu, Odawara-shi, Kanagawa Prefecture Storage Systems Division, Hitachi, Ltd.

Claims (7)

[Claims] A first insulating film, a magnetic recording / reproducing element, and a second insulating film on a substrate, wherein at least one of the first and second insulating films has an internal stress of a tensile stress. A thin film magnetic head comprising a film. 2. The thin-film magnetic head according to claim 1, wherein the second insulating film has a two-layer structure, wherein the layer on the side of the magnetic recording / reproducing element is a film having a compressive stress, and Wherein the layer is a film of the tensile stress. 3. The thin-film magnetic head according to claim 1, wherein the tensile stress film is made of a resin-based material. 4. The thin-film magnetic head according to claim 3, wherein said resin-based material is polyimide. 5. A thin-film magnetic head according to claim 1, wherein one of said first and second insulating films is a film of said tensile stress as a whole. 6. A thin film magnetic head, a rotation driving means for rotating a magnetic recording medium, and a thin film magnetic head,
A magnetic recording / reproducing apparatus having a radial moving means for moving the magnetic recording medium in a radial direction, wherein the thin-film magnetic head comprises a first insulating film, a magnetic recording / reproducing element, A magnetic recording / reproducing device comprising a second insulating film, wherein at least one of the first and second insulating films includes a film having an internal stress of tensile stress. 7. A method for manufacturing a thin-film magnetic head comprising a first insulating film, a magnetic recording / reproducing element, and a second insulating film on a substrate in order, wherein a cutting speed of 100 μm / A method for manufacturing a thin-film magnetic head, comprising a step of applying a compressive stress by grinding at a speed of at least min.