JP2002367107A - Method for flattening substrate, magnetic head and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve head characteristics by highly flattening a slope, a side face, even a bottom surface or the like inside a groove, which is difficult by a wrapping process to form a metal magnetic thin film, in the manufacturing method of a bulk thin film type magnetic head. SOLUTION: A glass thin film 3 is preformed on the surface of a non- magnetic substrate 2, the non-magnetic substrate 2 is treated with heat until the glass thin film 3 is softened to a specified viscosity, and then the non- magnetic basal plate 2 is cured until the glass thin film 3 becomes rigid to increase the flatness the non-magnetic substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of flattening a substrate suitable for highly flattening a surface, a magnetic head manufactured by using such a flattened substrate, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, high integration of various electronic devices,
Along with miniaturization, devices manufactured on a substrate by using a thin film technology have become widespread. In devices using such thin film technology, in order to achieve improved characteristics and higher integration,
It is important that the surface of the substrate be mirror-finished, that is, highly planarized.

As a device manufactured on a substrate by using a thin film technique, a pair of magnetic core half-blocks each formed by diagonally forming a metal magnetic thin film on a non-magnetic substrate are used. The surfaces of the non-magnetic substrate on which the metal magnetic thin film was formed were non-parallel to the magnetic gap, with the magnetic gap formed between the butted surfaces. There is a so-called bulk thin film magnetic head.

In this bulk thin film magnetic head, the impedance can be reduced by shortening the magnetic path of a magnetic core made of a metal magnetic thin film formed on a nonmagnetic substrate.

[0005]

In fabricating the above-mentioned bulk thin film magnetic head, a metal magnetic thin film is formed on a surface of a non-magnetic substrate having grooves having a plurality of slopes at predetermined intervals. Thus, the metal magnetic thin film is made non-parallel to the magnetic gap. Conventionally, the surface of the non-magnetic substrate on which the metal magnetic thin film is formed is mirror-finished by lapping using abrasive grains.

However, when manufacturing this bulk thin-film magnetic head, it is difficult to make the inner surface of the groove formed in the surface on which the metal magnetic thin film is formed mirror-finished by the above-described lapping process. Specifically, in the lapping process, since the surface on which the metal magnetic thin film is formed on the non-magnetic substrate is mirror-finished by a polishing operation using a grinding abrasive, the inner surface of the groove formed on the surface of the non-magnetic substrate, that is, Slope inside the groove,
It was difficult to make the side surfaces, bottom surfaces, etc. highly flat. In addition, in the lapping process, it takes an excessive amount of time to mirror the inner surface of the groove formed on the surface of the non-magnetic substrate. Further, in the lapping process, there is a possibility that the processing accuracy of the groove formed on the surface of the non-magnetic substrate is increased and the process of making the inner surface of the groove mirror-finished becomes extremely complicated. Furthermore, in the lapping process, it is difficult to make the inner surface of the groove formed on the surface into a mirror surface depending on the material of the non-magnetic substrate.

Accordingly, the present invention provides a method of flattening a substrate which makes it possible to highly flatten the surface of the substrate, and a magnetic head which makes it possible to greatly improve the head characteristics by using such a substrate. And a method for producing the same.

[0008]

According to the method of flattening a substrate according to the present invention, a glass thin film is previously formed on the surface of a substrate, and heat treatment is performed on the substrate until the glass thin film softens to a predetermined viscosity. After the application, the substrate is cured until the glass thin film is cured.

In the method of flattening a substrate according to the present invention,
After subjecting the substrate to heat treatment until the glass thin film softens to a predetermined viscosity, and curing the substrate until the glass thin film hardens, the surface of the glass thin film due to heat shrinkage when the softened glass thin film hardens. Due to the pull, the surface of the substrate is highly planarized.

Further, in the magnetic head according to the present invention, a pair of magnetic core halves each having a metal magnetic thin film formed on a non-magnetic substrate are joined and integrated by abutting the metal magnetic thin films on each other. In the magnetic head in which the magnetic gap is formed between the butting surfaces of the magnetic head and the surface on which the metal magnetic thin film of the non-magnetic substrate is formed is non-parallel to the magnetic gap, the metal magnetic thin film of the non-magnetic substrate Is characterized in that a glass thin film is formed on the surface on which is formed.

In the magnetic head according to the present invention, since the glass thin film is formed on the surface of the non-magnetic substrate on which the metal magnetic thin film is formed, the surface of the non-magnetic substrate is highly planarized. The soft magnetic characteristics of the metal magnetic thin film formed on the non-magnetic substrate whose surface is highly flattened are improved, and the characteristics of the magnetic head are improved.

Further, in the method of manufacturing a magnetic head according to the present invention, a glass thin film is previously formed on a surface of a non-magnetic substrate having a plurality of grooves formed at predetermined intervals, and the glass thin film is softened to a predetermined viscosity. After performing a heat treatment on the non-magnetic substrate until it is, by curing the non-magnetic substrate until the glass thin film is cured, a step of flattening the surface of the non-magnetic substrate,
Step of forming a metal magnetic thin film on a non-magnetic substrate, forming a glass layer so as to cover the non-magnetic substrate on which the metal magnetic thin film is formed, and forming the glass layer on the surface of the flattened glass layer Forming a pair of magnetic core half-blocks by forming a thin-film coil in the recessed portion, and forming a pair of magnetic core half-blocks such that end faces of the metal magnetic thin films oppose each other via a nonmagnetic thin film. And a step of manufacturing a magnetic core block by abutting and joining, and a step of cutting the magnetic core block to cut out a magnetic head.

In the method of manufacturing a magnetic head according to the present invention, the surface of the glass thin film is pulled by heat shrinkage when the softened glass thin film is hardened, and includes the inner surface of the groove formed on the surface of the non-magnetic substrate. Since the surface of the non-magnetic substrate is highly planarized, the soft magnetic properties of the metal magnetic thin film formed on the non-magnetic substrate whose surface is highly planarized are improved. Then, a pair of magnetic core half blocks is manufactured, and end faces of the metal magnetic thin films of the pair of magnetic core half blocks are joined to each other via a nonmagnetic thin film to manufacture a magnetic core block. By cutting, a large number of magnetic heads with improved magnetic head characteristics can be manufactured.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As a method of flattening a substrate to which the present invention is applied, as shown in FIG. 1, for example, a surface of a non-magnetic substrate 1 used for a bulk thin-film magnetic head having a groove formed on the surface by grinding using a grindstone. Will be described.

The non-magnetic substrate 1 is made of, for example, CaO--Ti
It is made of an O ₂ —NiO system or the like, and the surface including the slope portion 1a of the groove is subjected to lapping or the like. However, as shown in FIG. 2, the surface state is rough and has excessive unevenness. At this time, the surface of the non-magnetic substrate 1 on which the lapping process has been performed is placed on an atomic force microscope (AFM).
The center line average roughness (hereinafter, referred to as a surface roughness Ra) measured using a chromoscope) was 43 nm.
Conventionally, the surface roughness Ra of the inner surface of the groove formed on the surface of the non-magnetic substrate by mechanical processing such as lapping is set to 30 n.
It is considered difficult to reduce the value to m or less. In addition, FIG.
FIG. 3 is a diagram illustrating a state in which a slope 1a formed on a non-magnetic substrate 1 is observed by AFM.

Therefore, the flattening method of the substrate to which the present invention is applied is performed until the glass thin film 3 previously formed on one main surface of the non-magnetic substrate 2 softens to a predetermined viscosity as shown in FIG. After the non-magnetic substrate 2 is subjected to heat treatment, the non-magnetic substrate 2 is cured until the softened glass thin film 3 is hardened, so that the surface of the non-magnetic substrate 2 including the inner surface of the groove is mirror-finished, that is, highly planarized. Let it.

Specifically, in the method of planarizing a substrate, first,
A glass thin film 3 having a thickness of about 500 nm is previously formed on one main surface of the non-magnetic substrate 2 by, for example, sputtering or the like. The glass thin film 3 generally has a softening point viscosity of about 700 ° C. 10 ^{6 . 76} Pa. A borosilicate glass (YSK-60329, manufactured by Izumiyo Glass Industry Co., Ltd.) is used. The glass thin film 3 is not necessarily limited to using a borosilicate glass, but may be a glass material such as a low melting point glass having a low softening point.

FIG. 4 shows the relationship between the temperature when the non-magnetic substrate 2 is subjected to a heat treatment until the glass thin film 3 is softened and the viscosity of the glass thin film 3.

As shown in FIG. 4, this glass thin film 3
Viscosity 10 ^6.76 P which is generally regarded as the softening point of glass
a. s at about 700 ° C. and a viscosity of 10 ³ Pa. s is reached at about 900 ° C.

In the method of flattening a substrate according to the present invention,
The heat treatment temperature for softening the glass thin film 3 to be applied to the non-magnetic substrate 2 is set at a temperature of 10 ^6.76 Pa. s (softening point) or lower, 700 ° C. or higher, and the viscosity of the glass is 10 ³ P
a. It is performed in a range of 900 ° C. or lower which is equal to or higher than s (work point). This will be described later in detail.

Next, a heat treatment is applied to the non-magnetic substrate 2 until the formed glass thin film 3 softens to a predetermined viscosity.
The non-magnetic substrate 2 is cured, that is, aged until the softened glass thin film 3 is hardened.

Next, the surface of the glass thin film 3 is pulled by heat shrinkage when the softened glass thin film 3 is hardened, so that the surface of the non-magnetic substrate 2 is flattened.

Thus, in the method for planarizing a substrate to which the present invention is applied, as shown in FIG. 5, after the non-magnetic substrate 2 is subjected to a heat treatment until the glass thin film 3 softens to a predetermined viscosity, By curing the non-magnetic substrate 2 until the glass thin film 3 is cured, the surface of the glass thin film 3 is pulled by heat shrinkage when the softened glass thin film 3 is cured. Even the slope 2a, the side 2b, and the bottom 2c inside the groove shown in FIG. 3 can be highly flattened. FIG. 5 is a diagram showing a state in which the slope 2a of the groove formed on the surface of the nonmagnetic substrate 2 after heat treatment and curing is observed by AFM.

On the non-magnetic substrate 2, a base film (not shown) made of chromium or chromium oxide may be formed on the surface on which the glass thin film 3 is formed. Thereby, in the non-magnetic substrate 2, it is possible to prevent the glass thin film 3 from reacting and becoming crystalline during the heat treatment for softening the glass thin film 3. In addition, since the non-magnetic substrate 2 has poor wettability to the glass thin film 3 depending on its material and may repel the softened glass thin film 3, the softened glass thin film is formed by forming such a base film. The repelling of the thin film 3 can be prevented.

Here, a glass thin film shown in FIG. 4 is applied to each of the nonmagnetic substrates 2 on which chromium, chromium oxide, gold, platinum, copper, titanium, silicon dioxide, and aluminum oxide are formed as base films. The viscosity of 3 is 10 ^6.76 P
a. The viscosity of the glass thin film 3 shown in 700 ° C. and 4 serving as s is ¹⁰ 4.4 Pa. The heat treatment is performed for 1 minute at a temperature of 800 ° C., and the surface roughness R of the nonmagnetic substrate 2 after the nonmagnetic substrate 2 is cured until the glass thin film 3 is hardened.
a was measured. FIG. 6 shows the measurement results of the surface roughness Ra of the non-magnetic substrate 2 after the non-magnetic substrate 2 having the different underlying films is heat-treated at the respective temperatures and cured. FIG. 6 is a characteristic diagram showing the relationship between the type of the underlying film and the surface roughness Ra of the non-magnetic substrate 2. The reference value is also applied to the case of the non-magnetic substrate 2 having no underlying film. .

From the measurement results shown in FIG. 6, when the underlying film is made of chromium or chromium oxide, the surface roughness Ra is 20 nm or less and the surface is highly planarized.

On the other hand, other gold, platinum,
At least the surface roughness Ra of each of the base films of oxides of copper, titanium, silicon dioxide, and aluminum is 50 n.
It can be seen that it is very coarse at m or more. this is,
When gold, platinum, or copper is used for the underlayer, the non-magnetic substrate 2
When the heat treatment is performed, the softened glass film 3 is repelled by these base films, and the surface roughness Ra of the nonmagnetic substrate 2 is deteriorated. When an oxide of aluminum is used, when the non-magnetic substrate 2 is subjected to a heat treatment, the softened glass thin film 3 reacts with these base films to precipitate crystals in the glass thin film 3, resulting in non-magnetic This is because the surface roughness Ra of the substrate 2 is deteriorated.

Therefore, in the method of flattening a substrate to which the present invention is applied, chromium or chromium oxide is used as a base film between the nonmagnetic substrate 2 and the glass thin film 3 so that the surface roughness Ra of the nonmagnetic substrate 2 is increased. It has been clarified that deterioration of the nonmagnetic substrate 2 can be suppressed, in other words, the surface of the nonmagnetic substrate 2 can be highly flattened.

Next, the non-magnetic substrate 2 on which no underlying film is formed
And a non-magnetic substrate 2 on which a base film made of chromium is formed, a heat treatment is performed for one minute while changing the temperature to 400 ° C. to 1,000 or more, and the surface roughness Ra of each non-magnetic substrate 2 Was measured. FIG. 7 shows the measurement results of the surface roughness Ra of each nonmagnetic substrate 2 at each heat treatment temperature. FIG. 7 is a characteristic diagram showing the relationship between the temperature of the heat treatment performed on the non-magnetic substrate 2 and the surface roughness Ra of the non-magnetic substrate 2. 2 is also attached.

From the measurement results shown in FIG. 7, the heat treatment temperature of the non-magnetic substrate 2 having no underlying film is 700 ° C. or more,
The viscosity of the glass thin film 3 indicated by 10 ^6.76 Pa. s or less, the heat treatment temperature is 800 ° C. or less, i.e., a viscosity of ¹⁰ 4.4 Pa glass thin film 3 shown in FIG. s
The surface roughness Ra is improved to about 19 nm, and the surface is highly planarized.

[0032] In contrast, in no underlayer nonmagnetic substrate 2, the heat treatment temperature is lower than 700 ° C., i.e. the viscosity of the glass thin film 3 shown in FIG. 4 is ¹⁰ 6.76 Pa. When harder than s, the surface roughness Ra is not seen advanced planarization follows made such surfaces 30 nm, the heat treatment temperature is 800 ° C. or higher, i.e. 10 ^4.4 P viscosity of the glass thin film 3 shown in FIG. 4
a. It can be seen that, when the surface softens from s, the surface roughness Ra sharply increases, and the surface state is deteriorated.

[0033] This is, the viscosity of the glass thin film 3 shown in FIG. 4 is ¹⁰ 6.76 Pa. If the glass thin film 3 is harder than s, it hardly flattens the surface of the non-magnetic substrate 2 because the surface of the glass thin film 3 is less likely to be appropriately pulled when the glass thin film 3 is softened and hardened. It is thought to be.
The viscosity of the glass thin film 3 shown in FIG. 4 is ^{10 4.4} P
a. If the softened glass thin film 3 is softened, the softened glass thin film 3 and the nonmagnetic substrate 2 react with each other, and the crystalline is precipitated in the glass thin film 3. Therefore, it is difficult to flatten the surface of the nonmagnetic substrate 2. Conceivable.

Therefore, the flatness of the substrate to which the present invention is applied
In the method, the base film is not formed on the non-magnetic substrate 2.
In this case, the viscosity of the glass thin film 3 formed on the non-magnetic substrate 2 is
10 ^6.76Pa. s or less, 10^4.4Pa. more than
Softens within a certain range, that is, the film is formed on the non-magnetic substrate 2
Heat treatment temperature to soften the thin glass film 3
Above, the surface is highly flat by setting the temperature below 800 ° C
It became clear that it could be.

On the other hand, the non-magnetic substrate 2 underlying film made of chromium is deposited, heat treatment temperature of 700 ° C. or higher, i.e. viscosity ^{10 6.76} P of the glass thin film 3 shown in FIG. 4
a. s or less, and the heat treatment temperature is 900 ° C. or less, ie, FIG.
And the viscosity of the glass thin film 3 is 10 ³ Pa. If it is s or more, the surface roughness Ra is improved to about 11 nm, and the surface is highly flattened.

[0036] In contrast, in the non-magnetic substrate 2 underlying film made of chromium is deposited, heat treatment temperature is lower than 700 ° C., the viscosity of the glass thin film 3 shown in FIG. 4 is 10 ^6.76
Pa. If it is harder than s, no high degree of flattening of the surface such that the surface roughness Ra becomes 30 nm or less is observed, the heat treatment temperature is higher than 900 ° C., and the viscosity of the glass thin film 3 shown in FIG.
0 ³ Pa. It can be seen that when softened from s, the surface roughness Ra increases, and the surface state is degraded.

[0037] This is, the viscosity of the glass thin film 3 shown in FIG. 4 is ¹⁰ 6.76 Pa. If the glass thin film 3 is harder than s, it hardly flattens the surface of the non-magnetic substrate 2 because the surface of the glass thin film 3 is less likely to be appropriately pulled when the glass thin film 3 is softened and hardened. It is thought to be.
The viscosity of the glass thin film 3 shown in FIG. 4 is ¹⁰ 3 Pa. s
When the softening is further performed, the temperature of the heat treatment becomes excessive, the underlying film is deteriorated, and the softened glass thin film 3 reacts with the nonmagnetic substrate 2, and the crystalline is precipitated in the glass thin film 3. It is considered that it becomes difficult to flatten the surface.

Therefore, in the method of flattening a substrate to which the present invention is applied, in the case of the non-magnetic substrate 2 on which a base film made of chromium is formed, the viscosity of the glass thin film 3 formed on the non-magnetic substrate 2 is reduced. 10 ^6.76 Pa. s or less, 10 ³ Pa.
s or more, that is, the non-magnetic substrate 2
Heat treatment temperature for softening the glass thin film 3 formed on
It has been clarified that the surface can be highly flattened by setting the temperature between 00 ° C and 900 ° C. In the above measurement, chromium was used for the base film. However, the same result can be obtained when chromium oxide is used for the base film.

Next, the thickness of the base film made of chromium is set to 5 n
The viscosity of the glass shown in FIG. 4 is about 10 ^4.5 Pa.s for the non-magnetic substrate 2 changed from m to 100 nm. A heat treatment was performed for 1 minute at 800 ° C., which is the temperature at which the non-magnetic substrate 2 was cured, and the surface roughness Ra of the non-magnetic substrate 2 after the curing was measured. And
The surface roughness Ra of the non-magnetic substrate 2 after being subjected to a heat treatment to cure the non-magnetic substrate 2 with the thickness of the underlying film changed and cured.
FIG. 8 shows the measurement results. FIG. 8 is a characteristic diagram showing a relationship between the thickness of the underlayer made of chromium and the surface roughness Ra of the non-magnetic substrate 2.

From the measurement results shown in FIG. 8, the surface roughness Ra of the non-magnetic substrate 2 is the smallest when the base film made of chromium is 10 nm, and the surface roughness Ra of the non-magnetic substrate 2 becomes smaller when the base film is thicker than 20 nm. It can be seen that it grows up.

Thus, in the non-magnetic substrate 2, if the thickness of the base film made of chromium is more than 20 nm, the amount of chromium mixed into the glass thin film 3 becomes excessive when heat treatment for softening the glass thin film 3 is performed. Since the glass thin film 3 is separated on the surface on which the film 3 is formed, it is difficult to suppress the surface roughness Ra.

Therefore, according to the method of flattening a substrate to which the present invention is applied, when a base film made of chromium is formed on the surface on which the glass thin film 3 is formed, the thickness of the base film is set to 20 n.
m or less. In the method of flattening a substrate to which the present invention is applied, the base film formed with an appropriate thickness is excessively mixed into the glass thin film 3 without separating the glass thin film 3 and the softened glass thin film 3 is cured. The surface of the nonmagnetic substrate 2 is highly flattened by the surface of the glass thin film 3 being pulled by the heat shrinkage. Thereby, the surface of the non-magnetic substrate 2 including the inner surface of the groove formed on the surface of the non-magnetic substrate 2 can be mirror-finished. In the above measurement, chromium was used for the base film. However, the same result can be obtained when chromium oxide is used for the base film.

Next, a description will be given of a magnetic head manufactured by using the above-described method of flattening a substrate to which the present invention is applied.

The magnetic head 10 shown in FIG. 9 comprises a pair of magnetic core halves 11 joined by metal diffusion bonding. The pair of magnetic core halves 11 is made of CaO—Ti
Non-magnetic substrate 12 made of O ₂ —NiO-based non-magnetic material
And a metal magnetic thin film 13 formed on one main surface of the non-magnetic substrate 12 on which the slope 12a is formed, and a low-melting glass 14 covering the metal magnetic thin film 13. Further, at least one of the pair of magnetic core halves 11 has a thin-film coil 15 for excitation and / or detection of dielectric electromotive voltage formed thereon.

In the magnetic head 10, as shown in FIG. 10, the metal magnetic thin film 13 forms the magnetic core 17 with the pair of magnetic core halves 11 joined via the non-magnetic thin film 16. In FIG. 10, the thin film coil 15 is omitted.

The magnetic head 10 reproduces a signal magnetic field recorded on the magnetic recording medium by sliding the magnetic recording medium (not shown) in a direction indicated by an arrow A in FIG. Recording on a magnetic recording medium.

In order to adjust the contact state of the magnetic head 10 with the magnetic recording medium, the sliding surface 10a for the magnetic recording medium is parallel to the sliding direction of the magnetic recording medium indicated by arrow A in FIG. Has an arc shape. The magnetic head 10 has a contact width regulating groove 18 for adjusting the contact area with the magnetic recording medium. The contact width regulating groove 18 is parallel to the direction indicated by the arrow A in FIG.
Both sides of the magnetic head 10 are formed.

In the magnetic head 10, the non-magnetic substrate 12
Is made of a CaO—TiO ₂ —NiO-based nonmagnetic material, but is not necessarily limited thereto. For example,
It may be composed of calcium titanate, barium titanate, zirconium oxide, alumina, alumina titanium carbide, Zn ferrite, or the like.

This nonmagnetic substrate 12 has a surface of 10 n
A glass thin film 31 is previously formed on a base film 30 made of chromium formed to a thickness of about m. The non-magnetic substrate 12 is subjected to a heat treatment until the glass thin film 31 formed in advance is softened to a predetermined viscosity, and then cured until the glass thin film 31 is hardened, so that the surface thereof has a high degree. It has been flattened. That is, the non-magnetic substrate 1
2 is that the surface of the glass thin film 31 is pulled by heat shrinkage when the softened glass thin film 31 is hardened,
The surface is mirror-finished to the slope 12a.

The glass thin film 31 has a softening point of 700 ° C.
Borosilicate glass is formed to a thickness of about 500 nm. Note that the glass thin film 31 is not necessarily limited to using borosilicate glass, and a glass material having a low softening point and a low melting point, for example, may be used.

In the magnetic head 10, the metal magnetic thin film 1
Numeral 3 is formed of a material exhibiting soft magnetism such as Sendust (Fe-Al-Si alloy). Metal magnetic thin film 13
Is a slope 12a of the non-magnetic substrate 12 at a predetermined angle.
Is formed on the mirror-finished surface on which is formed.
For this reason, since the metal magnetic thin film 13 is formed on the mirror-finished surface of the nonmagnetic substrate 12, the soft magnetic characteristics can be improved.

The metal magnetic thin film 13 has a concave portion 13a at a substantially central portion of the end surface on the side to which the magnetic core half 11 is joined.
It is said. For this reason, the metal magnetic thin film 13 has a front butting surface 19 and a rear butting surface 20 which are separated and exposed by the low melting point glass 14 filled in the recess 13 a at the joining surface 11 a of the magnetic core half 11. Becomes The front butting surfaces 19 of the pair of magnetic core halves 11 are butted via the nonmagnetic thin film 16 to form a front gap 21. Also, a pair of magnetic core halves 1
The rear abutment surfaces 20 are abutted with each other via the non-magnetic thin film 16 to form a back gap 22.

The magnetic core half 11 has a joint surface 11a,
A coil-forming recess 23 is formed in which a thin-film coil 15 having a center on the rear abutting surface 20 is formed. A coil connection terminal 24 is formed in the coil forming recess 23 near the rear butting surface 20.
The thin film coil 15 is formed in the coil forming concave portion 23, and the end on the central portion side is connected to the coil connecting terminal 24.

The coil connection terminals 24 are formed by adjusting their heights so as to be flush with the joint surfaces 11a of the pair of magnetic core halves 11. Then, in the magnetic head 10, when the pair of magnetic core halves 11 are joined, the pair of coil connection terminals 24 are also joined. Thus, in the magnetic head 10, when the pair of magnetic core halves 11 are joined, the pair of thin-film coils 15 are electrically connected.

The outer peripheral end of the thin-film coil 15 is
The magnetic recording medium is led out to the side opposite to the sliding surface 10a. The pair of magnetic core halves 11 includes the thin film coil 15
The external connection terminals 25 are respectively formed at the parts from which are derived. The ends on the outer peripheral side of the thin-film coil 15 are connected to the external connection terminals 25, respectively.

The external connection terminals 25 have a function of electrically connecting the outside and the thin-film coil 15 by being exposed on the side surface of the magnetic head 10. The pair of external connection terminals 25 are formed at positions where they do not contact each other when the pair of magnetic core halves 11 are joined so that a short circuit does not occur.

In the magnetic head 10 configured as described above, the glass thin film 31 is formed on the surface of the non-magnetic substrate 12 on which the metal magnetic thin film 13 is formed.
The glass thin film 31 is softened by heat shrinkage during curing.
The surface of the non-magnetic substrate 12 is highly flattened by pulling the surface of the metal magnetic thin film 1 formed on the non-magnetic substrate 12 whose surface is highly flattened.
The soft magnetic characteristics of the magnetic head 10 can be improved, and the characteristics of the magnetic head 10 can be improved.

In the present embodiment, the thickness of the glass thin film 31 is set to about 500 nm. However, if the glass thin film 31 is formed on the surface on which the metal magnetic thin film 13 is formed, It is possible to flatten the surface. However, as the thickness of the glass thin film 31 increases, the time required for forming the glass thin film 31 on the non-magnetic substrate 12 increases excessively. For this reason, it is preferable that the thickness of the glass thin film 31 be 1000 nm or less.

Next, a method for manufacturing the above-described magnetic head 10 will be described in detail with reference to the drawings.

In manufacturing the magnetic head 10, first, a plurality of magnetic core halves 11 are formed on a same substrate in a plurality of rows. Next, the substrate is separated for each row in which the plurality of magnetic core halves 11 are formed, and the magnetic core halves 11 are separated.
Is made. Next, the block of the magnetic head 10 is manufactured by joining and integrating the blocks of the magnetic core half 11 by metal diffusion bonding. Then, the block of the magnetic head 10 is cut into individual magnetic heads 10, whereby the magnetic head 10 is completed. Below,
These steps will be described in order.

First, as shown in FIG. 11, a substantially flat substrate 40 is prepared. The substrate 40 is to be the non-magnetic substrate 12 of the magnetic head 10 and is, for example, CaO—Ti
It is made of an O ₂ —NiO-based nonmagnetic material. The substrate 40 has, for example, a thickness of about 2 mm and a length and width of 30 m.
m.

Next, as shown in FIG. 12, a plurality of magnetic core forming grooves 41 are formed on one main surface of the above-described substrate 40 by a grindstone or the like so as to have an angle of, for example, 45 ° with respect to 40a. Form parallel to each other. Thus, the magnetic core forming groove 41 formed by the first groove processing is formed in the substrate 40.
Thereby, a plurality of slope portions 40b are formed. In addition,
The slope portion 40b formed here has, for example, an arc shape,
It may be on a polygon. Further, it is preferable that the slope portion 40b has an inclination angle of about 25 ° to 60 ° with respect to the main surface of the substrate 40, but in consideration of prevention of pseudo gap and track width accuracy, about 35 ° to 50 °. It is more desirable to have a tilt angle. In the present embodiment, the depth of the magnetic core forming groove 41 is about 130 μm and the width is about 150 μm.

Next, the substrate 40 on which the slope portion 40b is formed is formed.
A base film 30 made of chromium is formed to a thickness of 10 nm on the entire upper surface.
The film was formed to have a thickness of about.

Next, as shown in FIG. 13, a borosilicate glass thin film 31 having a softening point of about 700 ° C. is applied to the entire surface of the substrate 40 on which the base film 30 is formed, for example, by sputtering. The film is formed to a thickness of about 500 nm. Then, for the substrate 40 on which the glass thin film 31 is formed,
Heat treatment is performed for 1 minute at a temperature of 800 ° C.
Softens. Then, natural cooling is performed until the softened glass thin film 31 is hardened.

As a result, the surface of the glass thin film 31 is pulled by the heat shrinkage when the softened glass thin film 31 is hardened, so that the entire surface of the substrate 40 on which the slope portion 40 b is formed is pulled. Highly flattened to the inner surface.

Next, as shown in FIG. 14, the metal magnetic thin film 13 is formed on the entire surface of the substrate 40 which has been highly flattened even to the inner surface of the magnetic core forming groove 41. Therefore, the metal magnetic thin film 13 is formed on the highly planarized substrate 40.
Since the film is formed thereon, the soft magnetic characteristics can be significantly improved.

In this film forming step, the metal magnetic thin film 1
3 is formed so as to have a laminated structure with a nonmagnetic layer interposed between three layers of metallic magnetic materials. The metal magnetic thin film 13 is formed by, for example, magnetron sputtering, MBE (Mole).
PVD (Physical Vapor Depos) such as a Crop Beam Epitaxy (CVD) method and an evaporation method.
ion) method, CVD (Chemical Vapo)
(r Deposition) method.

Further, the metal magnetic thin film 13 is not necessarily limited to the one having a plurality of metal magnetic layers, and may be constituted by a single metal magnetic layer.
In order to obtain high sensitivity in a higher frequency band, it is preferable that the metal magnetic layer has a laminated structure divided into a plurality. Thereby, the metal magnetic thin film 13 has reduced eddy current loss,
High sensitivity can be obtained in a higher frequency band.

In the present embodiment, the metal magnetic thin film 13
Has a structure having three Fe-Al-Si alloy layers by alternately laminating 4 µm of Fe-Al-Si alloy (Sendust) and 0.15 µm of alumina to be a nonmagnetic layer (not shown). . When the metal magnetic thin film 13 is configured to have a plurality of layers, the nonmagnetic layer may be alumina,
Materials such as SiO2 and SiO are used alone or in combination. The thickness of the non-magnetic layer is such that the adjacent metal magnetic thin film 13 can be easily insulated.

Next, as shown in FIG. 15, a second groove is formed on the surface on which the metal magnetic thin film 13 is formed in a direction substantially orthogonal to the magnetic core forming groove 41. In the second groove processing, a separation groove 42 formed for separating the magnetic core 17 having a predetermined size and a film for forming the thin film coil 15 on each magnetic core 17 separated by the separation groove 42 are formed. The winding groove 43 is formed.

At this time, the metal magnetic thin film 13 formed on the portion other than the slope portion 40b, that is, the metal magnetic thin film 13 formed on the bottom of the magnetic core forming groove 41 is removed by grinding.

The separation groove 42 is used to connect the magnetic core 17 to the substrate 4
Each of the magnetic cores 17 is formed by magnetically separating the magnetic cores 17 from front to back in the front-rear direction and forming a closed magnetic path in each magnetic core 17. Although two separation grooves 42 are formed in the example of FIG. 15, the separation grooves 42 need to be provided by the number of rows of the magnetic core halves 11 to be formed. In addition, the separation groove 42 must be formed to have a depth enough to completely cut the metal magnetic thin film 13 in order to magnetically separate the magnetic cores 17 arranged in the front-rear direction. There is. Specifically, the separation groove 42 is positioned 15 mm from the bottom of the magnetic core formation groove 41.
0 μm depth, that is, 2 μm from the main surface 40 a of the substrate 40.
The depth is set to 80 μm.

On the other hand, the winding groove 43 forms the recess 13 a in the magnetic core 17 in the magnetic head 10 in the magnetic magnetic thin film 13. Therefore, the winding groove 43 forms a magnetic core 17 having the front butting surface 19 and the rear butting surface 20, and has such a depth that the metal magnetic thin film 13 is not cut to form the coil forming recess 23. It is necessary to form with. For this reason,
The cross section of the metal magnetic thin film 13 is exposed on the surface of the winding groove 43.

The shape of the winding groove 43 is determined according to the lengths of the front butting surface 19 and the rear butting surface 20. In the present embodiment, the width is 14 mm.
0 μm, the length of the front butting surface 19 is 30 μm
And the length of the rear butting surface 20 was 85 μm. Note that the winding groove 43 is formed in the metal magnetic thin film 1.
Although the depth may be small enough not to cut 3, if it is too deep, the magnetic path length becomes long and the efficiency of magnetic flux transmission deteriorates. The depth of the winding groove 43 depends on the thickness of the thin-film coil 15 formed in a step described later, but is set to 20 μm in the present embodiment.

Further, although the shape of the winding groove 43 is not limited, in the present embodiment, the side surface on the side of the front abutting surface 19 has an inclined surface 43a having an angle of 45 °.
And Thereby, the magnetic core 17 has a structure in which the magnetic flux is concentrated on the sliding surface 10a, and the sensitivity of the magnetic head 10 can be improved.

Next, as shown in FIG. 16, the substrate 4 on which the magnetic core forming groove 41, the separation groove 42 and the winding groove 43 are formed.
The 0 main surface 40a is filled with the molten low-melting glass 44. Thereafter, the low-melting glass 44 is cooled and solidified,
A flattening process is performed on the surface of the solidified low melting point glass 44.

When the flattening process is performed on the low-melting glass 44, it is desirable that the width of exposing the substrate 40 is smaller than the width of the innermost circumference of the thin-film coil 15. Thereby, when performing an etching process in a later step, the substrate 4
It is possible to prevent the occurrence of a step due to a difference in the etching rate between 0 and the low melting point glass 44.

Next, as shown in FIG. 17, a terminal groove 45 is formed by subjecting the solidified low-melting glass 44 to grinding using a grindstone or the like. This terminal groove 45
It is formed so as to be located immediately above the above-mentioned separation groove 42.
In the present embodiment, the width and the depth of the terminal groove 45 are set to 1
It is set to 00 μm. Then, Cu is inserted into the terminal groove 45.
Is filled by a plating method or the like. After that, the surface of the low-melting glass 44 is subjected to the flattening process again. The conductor such as Cu filled in the terminal groove 45 becomes the external connection terminal 25 in the magnetic head 10 described above.

Next, as shown in FIG. 18, the low-melting glass 44 is subjected to etching to form the coil-forming recess 23, and the thin-film coil 15 is formed in the coil-forming recess 23. Film.

The coil forming concave portion 23 has a substantially rectangular shape with the center of the normal portion abutting surface 20 substantially at the center. By etching the portion excluding the rear abutting surface 20 and the coil connecting terminal 24, etching is performed. It is formed. Further, the coil forming concave portion 23 is provided with a terminal groove 45 from one end thereof.
To form a groove 23a.

Next, as shown in FIG. 19, a side groove 46 which is a square groove is formed so as to cross the front abutting surface 19 facing the main surface of the substrate 40 in parallel. Thereafter, the substrate 40 on which the magnetic core halves 11 are formed in a plurality of parallel rows is cut so as to be arranged in each row, thereby forming the magnetic core block halves 47.

The side groove 46 is formed by grinding, and has, for example, a depth of 50 μm and a width of 400 μm.
When the side groove 46 is formed, a part of the front abutting surface 19 is exposed on the side surface of the side groove 46. As will be described later, the side grooves 46 are formed to expose the upper end of the front butting surface 19 as a positioning index when the pair of magnetic core half blocks 47 are butted.

After the side grooves 46 are formed, the main surface of the substrate 40 is flattened by mirror polishing. At this time, the front butting surface 19 and the rear butting surface 20 covered with the protective film are exposed to the outside.

Next, as shown in FIG. 20, a pair of magnetic core half blocks 47 is accurately positioned to perform metal diffusion bonding. At this time, a pair of magnetic core half blocks 47
The patterning of Au which becomes the non-magnetic thin film 16 is performed on the bonding portion, and the upper end portions of the front abutting surfaces 19 facing the side grooves 46 are opposed to each other so that accurate positioning is achieved. Then, by applying a predetermined temperature and pressure to the pair of magnetic core half blocks 47 butted against each other, metal diffusion bonding is performed, and a magnetic head block 48 is manufactured. In this embodiment, the metal diffusion bonding is performed by patterning Au. However, for example, a pair of magnetic core half blocks 47 is formed using an adhesive or water glass.
May be joined.

Next, as shown in FIG. 21, the magnetic head block 48 is cut and separated into individual magnetic heads 10. At this time, the magnetic head block 48 is separated into individual magnetic heads 10 by cutting the magnetic head block 48 at a portion indicated by the line BB 'in the figure so that the azimuth angle becomes 20 degrees. Thus, the magnetic head 10 is completed.

As described above, in the method of manufacturing a magnetic head to which the present invention is applied, the surface of the glass thin film 31 is pulled by the heat shrinkage when the softened glass thin film 31 is hardened, so that the glass thin film 31 is formed on the surface of the substrate 40. Since the surface of the substrate 40 including the inner surface of the magnetic core forming groove 41 is highly planarized, the soft magnetic characteristics of the metal magnetic thin film 13 formed on the substrate 40 whose surface is highly planarized are reduced. It can be good. Then, a pair of magnetic core half blocks 47 are manufactured, and the front butting surface 19 and the rear butting surface 2 of the metal magnetic thin film 13 of the pair of magnetic core half blocks 47 are formed.
The magnetic core block 48 is manufactured by joining the non-magnetic thin film 16 so that the magnetic heads 10 abut each other, and the magnetic core block 48 is cut to manufacture a large number of magnetic heads 10 having improved magnetic head characteristics. Can be.

Here, the magnetic head 10 manufactured by using the substrate 40 whose surface is highly flattened by the above-described method of flattening the substrate, and the magnetic head 10 using the substrate that has not been flattened. , The recording / reproducing output of the magnetic head and the optimum recording current were measured. Table 1 shows the results obtained by this measurement. The evaluation conditions of these magnetic heads were based on the DVC (digital video cassette) format.

[0088]

[Table 1]

From the measurement results in Table 1, it can be seen that the magnetic head 10 using the substrate 40 whose surface is highly flattened has a higher recording / reproducing output of the magnetic head than the magnetic head whose substrate has not been flattened. And the optimum recording current of the magnetic head is low.

As described above, in the magnetic head 10, since the metal magnetic thin film 13 is formed on the substrate 40 whose surface is highly planarized, the soft magnetic characteristics of the metal magnetic thin film 13 are improved. In addition, the recording / reproducing output can be increased, and a high recording / reproducing output can be obtained with a smaller recording current.

The device using the substrate 40 whose surface is highly planarized by the above-described substrate planarization method is exemplified by the magnetic head 10, but the substrate 40 whose surface is highly planarized is used. The device is not necessarily limited to the magnetic head 10 described above, but may be a device manufactured using a thin film technology on a highly planarized substrate, for example, a semiconductor device, a thin film head such as an MR head or a MIG head, or the like. Even when used, the characteristics of these devices can be improved.

[0092]

In the method of flattening a substrate according to the present invention, the substrate is subjected to a heat treatment until the glass thin film softens to a predetermined viscosity, and then the substrate is cured until the glass thin film is hardened. Since the surface of the glass thin film is pulled by the heat shrinkage when the formed glass thin film is cured, the surface of the substrate can be easily flattened to a high degree.

In the magnetic head according to the present invention, since the glass thin film is formed on the surface of the non-magnetic substrate on which the metal magnetic thin film is formed, the surface of the non-magnetic substrate is highly planarized. The soft magnetic characteristics of the metal magnetic thin film formed on the non-magnetic substrate whose surface is highly flattened are improved, and the characteristics of the magnetic head can be greatly improved.

In the method of manufacturing a magnetic head according to the present invention,
Because the surface of the glass thin film is pulled by heat shrinkage when the softened glass thin film is cured, the surface of the non-magnetic substrate including the inner surface of the groove formed on the surface of the non-magnetic substrate is highly flattened In addition, the soft magnetic characteristics of the metal magnetic thin film formed on the non-magnetic substrate whose surface is highly planarized can be greatly improved. Then, a pair of magnetic core half blocks is manufactured, and end faces of the metal magnetic thin films of the pair of magnetic core half blocks are joined to each other via a nonmagnetic thin film to manufacture a magnetic core block. By cutting, a large number of magnetic heads with improved magnetic head characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a non-magnetic substrate according to the present invention.

FIG. 2 is a perspective view of a main part of a conventional non-magnetic substrate.

FIG. 3 is a schematic perspective view showing a state in which a glass thin film is formed on a non-magnetic substrate according to the present invention.

FIG. 4 is a characteristic diagram showing a relationship between temperature and viscosity in the glass thin film.

FIG. 5 is a perspective view of a main part of the nonmagnetic substrate.

FIG. 6 is a characteristic diagram showing the relationship between the type of underlayer and the surface roughness of a non-magnetic substrate.

FIG. 7 is a characteristic diagram showing a relationship between a heat treatment temperature and a surface roughness diagram in the nonmagnetic substrate according to the present invention.

FIG. 8 is a characteristic diagram showing a relationship between the thickness of the underlayer and the surface roughness of a non-magnetic substrate.

FIG. 9 is an exploded perspective view showing the same magnetic head.

FIG. 10 is an enlarged perspective view of a main part showing a magnetic core of the magnetic head and its vicinity.

FIG. 11 is a diagram for explaining the method for manufacturing the magnetic head, and is a perspective view showing the substrate.

FIG. 12 is a diagram for explaining the method for manufacturing the magnetic head, and is a perspective view showing a state where a magnetic core forming groove is formed on the substrate.

FIG. 13 is a diagram for explaining the method for manufacturing the magnetic head, and is a perspective view showing a state where a glass thin film is formed on the substrate.

FIG. 14 is a view for explaining the method for manufacturing the same magnetic head, and is a perspective view showing a state where a metal magnetic thin film is formed.

FIG. 15 is a view for explaining the method for manufacturing the magnetic head, and is a perspective view showing a state where the separation groove and the winding groove are formed.

FIG. 16 is a view for explaining the method for manufacturing the same magnetic head, and is a perspective view showing a state where low-melting glass is filled.

FIG. 17 is a view for explaining the method for manufacturing the magnetic head, and is a perspective view showing a state where a terminal groove is formed on the substrate.

FIG. 18 is a diagram for explaining the method for manufacturing the magnetic head, and is an enlarged perspective view of a main part showing a state where a thin-film coil is formed.

FIG. 19 is a diagram for explaining the method for manufacturing the same magnetic head, and is a perspective view showing a state where the substrate is cut and separated into magnetic core half blocks.

FIG. 20 is a diagram for explaining the method for manufacturing the magnetic head, and is a perspective view showing a state in which a pair of magnetic core half blocks is being joined.

FIG. 21 is a view for explaining the method for manufacturing the magnetic head, and is a perspective view showing the magnetic head block.

[Explanation of symbols]

Reference Signs List 1 non-magnetic substrate, 1a slope portion, 2 non-magnetic substrate, 2
a slope portion, 2b side portion, 2c bottom portion, 3 glass thin film, 10 magnetic head, 12 non-magnetic substrate, 13
Metal magnetic thin film, 30 underlayer, 31 glass thin film, 4
0 board, 40b slope

Claims (19)

[Claims] 1. A glass thin film is previously formed on a surface of a substrate, and the substrate is subjected to a heat treatment until the glass thin film softens to a predetermined viscosity, and then the substrate is cured. A method of flattening a substrate, characterized by curing the substrate. 2. The softening viscosity of the glass thin film is 10 ³
Pa. s or more and 10 ^{6 . 76} Pa. 2. The method for planarizing a substrate according to claim 1, wherein the range is not more than s. 3. The softening viscosity of the glass thin film is 10
^4.4 Pa. s or more and 10 ^6.76 Pa. 3. The method for planarizing a substrate according to claim 2, wherein the range is not more than s. 4. The method according to claim 1, wherein the thickness of the glass thin film is 1000 nm or less. 5. The method according to claim 1, wherein a base film made of chromium or chromium oxide is formed between the substrate and the glass thin film. 6. The method according to claim 5, wherein the thickness of the base film is set to 20 nm or less. 7. A pair of magnetic core halves each having a metal magnetic thin film formed on a non-magnetic substrate are joined and integrated by abutting the metal magnetic thin films with each other, and a magnetic gap is formed between these abutting surfaces. In the magnetic head, the surface of the non-magnetic substrate on which the metal magnetic thin film is formed is non-parallel to the magnetic gap. A magnetic head comprising a glass thin film formed on a surface to be formed. 8. The non-magnetic substrate according to claim 7, wherein the surface on which the metal magnetic thin film is formed is flattened by pulling the glass thin film by thermal contraction.
The magnetic head as described. 9. The softening viscosity of the glass thin film is 10 ^3.
Pa. s or more, ^{10 6. 76} Pa. 9. The magnetic head according to claim 8, wherein the range is s or less. 10. The softening viscosity of the glass thin film is 10
^4.4 Pa. s or more and 10 ^6.76 Pa. 9. The magnetic head according to claim 8, wherein the range is s or less. 11. The thickness of the glass thin film is 1000 nm.
8. The magnetic head according to claim 7, wherein: 12. The magnetic head according to claim 7, further comprising a base film made of chromium or chromium oxide between said nonmagnetic substrate and said glass thin film. 13. The magnetic head according to claim 12, wherein the thickness of the underlayer is 20 nm or less. 14. A glass thin film is formed on a surface of a non-magnetic substrate in which a plurality of grooves are formed at predetermined intervals, and the glass thin film is softened to a predetermined viscosity. After the heat treatment, curing the non-magnetic substrate until the glass thin film is cured, thereby flattening the surface of the non-magnetic substrate, and forming a metal magnetic thin film on the non-magnetic substrate Forming a glass layer so as to cover the non-magnetic substrate on which the metal magnetic thin film is formed, and forming a thin-film coil in a concave portion formed on the surface of the glass layer subjected to the flattening process. Producing a pair of magnetic core half-blocks by abutting and joining the pair of magnetic core half-blocks such that end faces of the metal magnetic thin films face each other via a nonmagnetic thin film. By magnetic core A method for manufacturing a magnetic head, comprising: a step of manufacturing a lock; and a step of cutting a magnetic head by cutting the magnetic core block. 15. The softening viscosity of the glass thin film is 10
³Pa. s or more, 10 ^6.76Pa. s or less
15. The method of manufacturing a magnetic head according to claim 14, wherein
Method. 16. The glass thin film having a softening viscosity of 10
^4.4 Pa. s or more and 10 ^6.76 Pa. 15. The method according to claim 14, wherein the range is not more than s. 17. The thickness of the glass thin film is 1000 nm.
The method for manufacturing a magnetic head according to claim 14, wherein: 18. The method according to claim 14, wherein a base film made of chromium or chromium oxide is formed between the nonmagnetic substrate and the glass thin film. 19. The method of manufacturing a magnetic head according to claim 18, wherein the thickness of the underlayer is set to 20 nm or less.