JP2529194B2 - Thin film magnetic head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head capable of achieving high recording density and high reliability in a magnetic recording / reproducing apparatus using a magnetic tape or a magnetic disk as a magnetic recording medium. It is a thing.

2. Description of the Related Art Recently, in a magnetic recording / reproducing apparatus, a thin film magnetic head has been widely used as a recording / reproducing head with a marked increase in recording linear density and track density. In particular, for the purpose of improving the sound quality and quality of conventional compact cassette tape recorders, or aiming to increase the storage capacity while maintaining high reliability in computer magnetic tape devices and magnetic disk devices, conventional bulkheads have been adopted. Instead, digital recording and reproduction with thin-film magnetic heads are progressing. Compared with conventional bulkheads, the thin-film magnetic head has the advantages that the recording magnetic field distribution is steeper during recording, the peak shift of the reproduction output waveform during reproduction is small, and that multitracking is easy. I have many. On the other hand, with regard to the manufacturing of thin film magnetic heads, semiconductor thin film microfabrication methods have made significant progress by making full use of semiconductor IC manufacturing technology, and the social demand for high density magnetic recording, such as narrower tracks, narrower magnetic gaps, and multi-tracks. Is becoming available.

Many proposals have been made for the structure of the thin film magnetic head. FIG. 4 shows a thin-film magnetic head having a two-layer multi-turn coil structure as the most representative conventional structure example.
A conventional thin film magnetic head will be described below with reference to the drawings.

FIG. 4 is a sectional view of a conventional thin film magnetic head. Fourth
In the figure, 1 is a ferromagnetic substrate having a high magnetic permeability such as Mn-Zn single crystal ferrite, 2 is SiO ₂ , Si ₃ N ₄ formed on the ferromagnetic substrate 1 by a sputtering method, a plasma CVD method or the like.
Is the first insulating layer. The first insulating layer 2 has a first
The thin film coil 3 has a structure of 4 turns in FIG. The thin film coil 3 is made of copper, aluminum, gold or the like, and is formed into a desired shape by a photolithography technique after being formed by a sputtering method, a vapor deposition method, an electroplating method, or the like. Reference numeral 4 is a second insulating layer for insulating the first thin film coil 3. The second insulating layer 4 can be patterned into a desired shape by using the same material as that of the first insulating layer 2 or a heat-resistant photoresist can be used. In this case, after patterning, heat curing is performed to obtain a coil insulating material. It is a thing. The surface of the second insulating layer 4 is planarized by an appropriate method, and then the second thin film coil 5 of the second layer is formed. The first thin-film coil 3 of the first layer and the second thin-film coil 5 are connected by a coupling conductor 6, and as a result, the thin-film coil structure has a spiral shape around a through hole 8 forming a back gap. Is wound around. The second thin-film coil 5 is formed of the same material and the same process as the first thin-film coil 3. Reference numeral 7 is a third insulating layer that insulates the second thin-film coil 5, is made of the same material and has the same process as the second insulating layer 4, and has a flattened surface. In the method of forming the through holes 8 described above at the patterning step of each insulating layer, there are problems in dimensional accuracy and the number of steps. Therefore, at the time of patterning the first insulating layer 2 and when the third insulating layer 7 is formed and planarized, the second and third insulating layers 4 and 7 are collectively formed into a desired shape. A method of completing the step of patterning is preferable. A back magnetic pole 9 is formed in the through hole 8 prior to the formation of the magnetic pole 10 and is connected to the ferromagnetic substrate 1. 10 is a magnetic pole, which is a soft magnetic thin film made of permalloy, sendust or an amorphous alloy having high magnetic permeability. As a manufacturing method, a sputtering method, an electron beam evaporation method, an electroplating method, or the like is used. Patterned by photolithography technique. Reference numeral 11 is a protective layer that protects the magnetic pole 10, and is composed of SiO ₂ , Si.
Insulating films such as O ₂ and Al ₂ O ₃ are laminated by vapor deposition or sputtering. After that, a bulky protective substrate 13 made of ceramic, glass or the like is adhered via an adhesive material 12, and head tip processing and mirror polishing are performed for the purpose of stable running with the magnetic recording medium 15 and creation of the magnetic gap depth.

The operation of the thin film magnetic head configured as described above will be described. The magnetic gap 14 as a thin film magnetic head is formed with the thickness of the first insulating layer 2. At the time of recording operation, a recording current is applied to the thin film coils 3 and 5, and an induced magnetic flux flows through the path of the magnetic pole 10 → magnetic gap 14 → magnetic recording medium 15 → ferromagnetic substrate 1 → back gap magnetic pole 9 → magnetic pole 10. Occurs, and a signal is recorded on the magnetic recording medium 15.
A magnetic recording medium on which information is recorded during a reproducing operation.
The signal magnetic flux from 15 flows in the above magnetic circuit and interlinks with the thin film coils 3 and 5, whereby a reproduction output is obtained between both terminals of the thin film coils 3 and 5.

Problems to be Solved by the Invention However, the structure as described above has some problems due to the following reasons.

(1) Due to the head structure, the film thickness of each of the thin film coils 3 and 5 and the coil insulating films (the second and third insulating layers 4 and 7 in FIG. 4) is required to be about 2 μm. This results in a magnetic pole
A large step portion a, b or a concave portion c is formed at 10. In the magnetic pole formed by the sputtering method or the like, the film thickness of the step portions a and b is smaller than that of the other flat portion, the cross-sectional area through which the magnetic flux flows is small, and magnetic saturation is likely to occur. Further, as shown in FIG. 4, as the number of layers of the coil is increased like the two-layer thin film coil structure, the step difference value of the step portions a and b increases. This causes a large deterioration in the magnetic permeability of the magnetic pole 10 in the step portion.
The above phenomenon is the main cause of the decrease in recording efficiency and reproducing efficiency in the thin film magnetic head.

In order to prevent magnetic saturation, it is necessary to form a thick magnetic film of the magnetic pole 10. However, when the magnetic film becomes thicker, the difference in thermal expansion coefficient from the underlying material, cracks in the magnetic pole or the substrate due to long-time sputtering, etc. This causes harmful effects such as cracking or peeling. Further, it is difficult to perform highly accurate patterning when a thick film is formed.

On the other hand, there is no suitable means for preventing the deterioration of the magnetic permeability of the magnetic pole step portion, and the present situation is left to the structural design to reduce the step amount.

(2) Even when the surface of the protective layer 11 of the magnetic pole 10 is flattened, the film thickness of the protective layer 11 exposed at the tip of the head sliding on the magnetic recording medium 15 is at least the level difference of the magnetic pole 10. Appears only in quantity. As a result, as the foreign thin film material exposed at the tip of the head, in the case of FIG. 4, the first insulating layer 2 made of SiO _{2 and the} like, the protection 11 and the magnetic pole 10 are formed, which are accompanied by contact sliding with the magnetic recording medium 15. Uneven wear on the tip of the head is likely to occur. This uneven wear amount is due to the magnetic pole 10 and the protective layer 11.
It increases as the film thickness increases.

(3) The magnetic recording medium capable of high-density digital recording has recently been improved in coercive force. In order to increase the coercive force, the conventional thin film magnetic head technology is dealt with by increasing the number of thin film coil layers and increasing the thickness of the magnetic pole, as described above (1),
In particular, in (2) cracks in the substrate or thin film layers consisting of multiple layers,
The problems of cracking, peeling, difficulty of high-precision patterning, uneven wear of the head tip, and deterioration of the magnetic permeability of the stepped portion become significant.

In view of the above problems, the present invention makes it possible to apply a magnetic recording medium having a high coercive force capable of recording and reproducing high density digital data, while improving recording efficiency and reproducing efficiency of a thin film magnetic head, and further, uneven wear characteristics. It is intended to provide a highly reliable thin film magnetic head capable of significantly improving the above.

Means for Solving the Problems In order to solve the above-mentioned problems, the thin film magnetic head of the present invention has a step portion so that the step portion of the magnetic pole and the thick protective layer generated by the step are removed. The head magnetic gap and the recess in the back magnetic gap, which had been the cause, were filled with a high-permeability ferromagnetic thin film material, and it was optimal that the surface be flush with the upper surface of the uppermost insulating layer of the thin-film coil. A bulk-shaped ferromagnetic substrate having a high magnetic permeability is arranged on the filled ferromagnetic thin film material and the thin film coil uppermost insulating layer by adjusting and processing according to a manufacturing process. As a result, the ferromagnetic thin film material filled in the tip magnetic gap and the back magnetic gap is magnetically coupled by the bulk ferromagnetic substrate.

The present invention has the above-described structure, and the large step portions or recesses formed at the stage of pattern etching after the formation of the thin film coil insulating layer on the uppermost surface are the tip magnetic gap portion and the back magnetic gap portion. The back magnetic gap can be formed in a state where the tip magnetic gap length and the magnetic resistance on the magnetic circuit are almost zero by filling the high magnetic permeability ferromagnetic thin film material with. The above ferromagnetic thin film material is flattened so as to be flush with the thin film coil insulating layer on the uppermost surface to form a tip magnetic pole piece and a back magnetic pole piece, respectively. At this point, the step of the ferromagnetic thin film material is removed. Has been. The separated tip magnetic pole piece and back magnetic pole piece are connected by a bulky high-permeability ferromagnetic substrate arranged thereon. Furthermore, another role of this ferromagnetic substrate is the operation as a protective substrate, which is said in the conventional structure. According to the above-described head structure of the present invention, unlike the conventional magnetic pole, there is no stepped portion on the magnetic flux propagation path, the magnetic pole insulating layer is not required, and high-precision patterning of the magnetic pole is not required. It can be expected to improve efficiency, regeneration efficiency, high reliability and excellent productivity.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 3 conceptually shows a cross section of the thin film magnetic head of the present invention. In FIG. 3, 40
Reference numerals 60 and 60 respectively denote a substrate made of a bulk material and a protective substrate. Reference numeral 50 is a thin film layer which is provided between the two and is laminated and composed of a plurality of materials. A high permeability thin film magnetic material, a thin film coil, an insulating layer and the like are mixed in the thin film layer 50, and cooperate with the substrate 40 and the protective substrate 60 to form a magnetic head. 70 is a connecting member for connecting to an external electric circuit. The tip of the head is ground and mirror-finished in a shape according to the purpose. In FIG. 3, a dotted line portion 80 is a magnetic medium sliding surface.

FIG. 1 is a sectional view of a thin film magnetic head having a two-layer four-turn coil structure according to an embodiment of the present invention.

In FIG. 1, reference numeral 20 is a ferromagnetic substrate made of Mn-Zn single crystal ferrite, Ni-Zn ferrite or the like having a high magnetic permeability, and its surface is mirror-polished. A first insulating layer 21 made of SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ or the like is formed on the ferromagnetic substrate 20 with a film thickness corresponding to the magnetic gap length. As a thin film forming method, a sputtering method, a plasma CVD method, etc. are generally used. After this, a small window 22 serving as a back magnetic gap is opened by an etching technique. Reference numeral 23 is a first thin-film coil which is the first layer and has four turns in FIG.
A conductive metal body such as l is deposited by a sputtering method, an electroplating method, or the like, and then patterned into a coil shape by an etching method. A second insulating layer 24 is attached on the thin film coil 23 for the purpose of insulating the thin film coil.
The second insulating layer 24 can be used as an interlayer insulating material by using a heat resistant photoresist in addition to SiO ₂ , Al ₂ O ₃ , Si ₃ N _{4, and the} like. The surface of the second insulating layer 24 is flattened. twenty five
Is a second thin-film coil formed on the second layer, and is connected to the first thin-film coil 23 by a through hole 39 formed in the second insulating layer 24. A third insulating layer 26 is formed on the second thin-film coil 25 by the same manufacturing method as that for the second insulating layer 24.
Since the third insulating layer 26 is also flattened by an appropriate means in the same manner as the second insulating layer 24 to form a through hole of the rear magnetic tip 27 and the through hole 22 to be the back magnetic gap, The second and third insulating layers 24 and 26 are collectively etched into a desired shape. The maximum etching step generated at this point is h as shown in FIG. After this, sendust,
A ferromagnetic thin film material having a high magnetic permeability such as an amorphous alloy or permalloy is deposited with a film thickness equal to or larger than the step h using a sputtering method or an electroplating method. This ferromagnetic thin film material is flush with the surface of the uppermost insulating layer (third insulating layer 26 in FIG. 1) of the thin film coil using suitable means (discussed below with reference to FIG. 2). To process. By this processing, the tip end magnetic pole piece 28 and the back magnetic pole piece 29 are formed in the ferromagnetic thin film material. After this tip magnetic pole piece 28
It is advisable to form an extremely thin protective layer for the purpose of protecting the back magnetic pole piece 29. A ferromagnetic protection substrate 31 made of the same material as the ferromagnetic substrate 20 is adhered by an adhesive 30. The adhesive 30 is preferably formed in the thinnest possible layer, and needs to be sufficiently thinner than the length of the tip magnetic gap 27. As this manufacturing method, an epoxy adhesive or a glass film having a relatively high melting point previously attached to the ferromagnetic protective substrate 31,
There is a method of fusion bonding an SiO ₂ film or the like, but it can be used properly according to the design. 38 is a magnetic recording medium.

FIG. 2 shows an example of the main manufacturing process after the steps or through holes are formed in the second and third insulating layers 24 and 26 by collective etching. The same number is attached.

In FIG. 2A, the high permeability ferromagnetic thin film material 32 has a thickness h '.
(H '> h) shows the state of being attached.
The surface of the ferromagnetic thin film material 32 has a step difference reflecting the shape of the base. A photoresist material 33 is coated on the ferromagnetic thin film material 32 so that the surface is flat. After that, etching is performed by irradiation with the ion beam 34. The incident angle θ ₁ of the ion beam is the photoresist material 33 and the ferromagnetic thin film material.
The etching rates of 32 are adjusted to be equal. The etching depth is performed up to the dotted line in FIG.

FIG. 3B shows an unnecessary ferromagnetic thin film material when the tip magnetic pole piece 28 and the back magnetic pole piece 29 are formed.
The process of removing 35 is shown. Unwanted ferromagnetic thin film material 35
Except for the exposed parts of the
At 37, the ferromagnetic thin film material 35 is removed. At this time, the ion beam incident angle θ ₂ is adjusted.

In FIG. 6C, the ferromagnetic protection substrate 31 is a resin or a ferromagnetic substrate.
Figure 31 shows the time when the glass film, SiO ₂ film, etc., which were previously attached, were melt-bonded.

The operation of the thin film magnetic head having the above structure will be described below.

The greatest feature of the present invention is that abrupt steps are removed in the magnetic flux transmission path made of a highly permeable magnetic material. In particular, the step of the magnetic thin film is removed to suppress deterioration of magnetic permeability and magnetic saturation. A detailed description will be given according to this embodiment shown in FIG.

The third insulating layer 26 on the second thin film coil 25 is etched by the process described in FIG. As a result,
A step or a recess is formed by the third insulating layer 26 on the first insulating layer 21 which will be the tip magnetic gap 27 and on the small window 22 which will be the back magnetic gap. The tip magnetic pole piece 28 and the back magnetic pole piece 29 are formed by filling the stepped portion or the small window with a high magnetic permeability material. The tip magnetic pole piece 28 forms a gap depth with the tip magnetic gap 27 which is important in head design. On the other hand, the back magnetic pole piece 29 is short-circuited with the ferromagnetic substrate 20, and the magnetic resistance generated between the two is brought close to zero to improve the magnetic circuit efficiency. Ferromagnetic protection substrate
31 is the tip magnetic pole piece 28 and the back magnetic pole piece
29 and are connected to form a closed magnetic circuit. That is, regarding recording, when a recording current flows through the thin-film coils 23 and 25, the ferromagnetic protective substrate 31 → the tip magnetic pole piece 28 → the ferromagnetic substrate 20.
→ Back magnetic pole piece 29 → Induction magnetic flux flowing in the path of the ferromagnetic substrate 31 is generated. As a result, the tip magnetic gap 27
The signal magnetic field leaks from the recording medium and a signal is recorded on the magnetic recording medium 38. Next, consider the time of playback. The signal magnetic flux from the magnetic recording medium 38 in which the signal is written is generated by the tip magnetic pole piece 28 →
Ferromagnetic protection substrate 31 → Pack magnetic pole piece 29 → Ferromagnetic substrate 20 in the path, interlink with the thin-film coils 23, 25, and change with time of the total magnetic flux interlinking between both terminals of the thin-film coils 23, 25. A corresponding output is induced.

As described above, according to the present embodiment, the tip magnetic pole piece 28 and the back magnetic pole piece 29 are formed by stacking the high-permeability thin film material on the step portion or the concave portion, and then forming the bulk magnetic material having a high magnetic permeability. (1) It is possible to realize a magnetic circuit having high magnetic flux propagation efficiency without degrading the magnetic permeability of the thin film magnetic body by removing the stepped portion of the thin film magnetic body on the magnetic flux propagation path. it can.

(2) The gap depth can be arbitrarily set without causing magnetic saturation at the head tip.

(3) Unlike the conventional structure, it is not necessary to separately use a protective substrate made of a non-magnetic material on the magnetic pole, and the protective substrate itself can be used so as to operate as a part of the magnetic circuit, and the manufacturing process can be shortened. .

(4) The thickness of the thin film layer exposed at the tip of the head that slides on the magnetic recording medium does not need to be interposed between the magnetic pole and the protective substrate, which is seen in the conventional structure. Can be reduced, and uneven wear characteristics can be significantly improved. Also, due to the large difference in thermal expansion coefficient between the thin film protective layer (eg, SiO ₂ ) which required several tens of μm and the ferromagnetic substrate or the thin film magnetic material, cracks in the substrate that occur after the thin film protective layer is formed. , Cracks, peeling of the thin film layer, and other troubles associated with the inclusion of the thin film protective layer are completely eliminated.

(5) Since the area occupied by the thin film magnetic material in the head chip is significantly reduced as compared with the conventional structure, the internal stress peculiar to the thin film can be reduced and high magnetic permeability can be maintained.

In the embodiment, the single track structure has been described, but the same applies to the multi-track head.

EFFECTS OF THE INVENTION The present invention removes a stepped portion of a thin film magnetic body by forming a tip magnetic pole piece and a back magnetic pole piece having flat surfaces by an etching method, and stacking a bulk ferromagnetic protection substrate on top of them. Therefore, the recording efficiency or the reproducing efficiency can be improved. Further, the thick protective layer can be removed, and a thin film magnetic head can be realized which can achieve various excellent effects such as improved uneven wear characteristics, improved production yield, and shortened manufacturing process. .

[Brief description of drawings]

FIG. 1 is a sectional view of a thin film magnetic head according to an embodiment of the present invention, FIG. 2 is a process drawing showing an example of a manufacturing process of the present invention, FIG. 3 is a conceptual diagram for explaining the present invention, and FIG. The figure is a cross-sectional view of a conventional thin film magnetic head. 20 ... ferromagnetic substrate, 21 ... first insulating layer, 22 ... small window,
23 …… first thin film coil, 24 …… second insulating layer, 25 ……
Second thin-film coil, 26 ... Third insulating layer, 27 ... Tip magnetic gap, 28 ... Tip magnetic pole piece, 29 ... Back magnetic pole piece, 31 ... Ferromagnetic protective substrate, 32, 35 ...
… Ferromagnetic thin film material, 33, 36 …… Photoresist, 34, 37 …… Ion beam, 38 …… Magnetic recording medium, 39 …… Through hole, 40 …… Substrate, 50 …… Thin film layer, 60 …… Protective substrate , 70 ...
... connection member.

Claims (2)

(57) [Claims] 1. A first insulating layer is formed on a bulky high-permeability ferromagnetic substrate, a thin film coil and an insulating layer of the thin film coil are sequentially laminated on the insulating layer, and a thin film coil insulating layer is formed. A flat tip magnetic pole piece and a back magnetic pole piece whose height is adjusted to be flush with the uppermost surface, a bulk high magnetic permeability ferromagnetic protective substrate and the ferromagnetic substrate arranged on the plane. And the thin film coil generates a magnetic field in the tip magnetic gap formed by the first insulating layer or the coil insulating layer, and the signal on the magnetic recording medium is generated. A thin film magnetic head with a structure wound to read. 2. A high-permeability ferromagnetic protection substrate, wherein a SiO ₂ film and a low-melting point glass film are laminated in advance on the bonding surface side and bonded to the ferromagnetic substrate by a heat fusion method. The thin film magnetic head according to claim 1.