JPH0468683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thin film magnetic head that is compatible with higher recording density and higher reliability in magnetic recording and reproducing apparatuses that use magnetic tapes and magnetic disks as magnetic recording media. It is something.

2. Description of the Related Art Recently, thin film magnetic heads have been widely used as recording and reproducing heads in magnetic recording and reproducing apparatuses due to remarkable improvements in recording density and track density.
In particular, for the purpose of improving the sound quality and quality of conventional compact cassette tape recorders, or for increasing storage capacity while maintaining high reliability in magnetic tape devices and magnetic disk devices for computers, it is recommended to replace conventional bulkheads. Digital recording and reproduction using thin film magnetic heads is progressing. Compared to conventional bulk heads, thin-film magnetic heads have a steeper recording magnetic field distribution during recording, and a smaller peak shift in the reproduced output waveform during reproduction.
It also has many excellent advantages, such as the ease of multi-tracking. On the other hand, with regard to manufacturing thin-film magnetic heads, significant progress has been made in thin-film microfabrication methods by making full use of semiconductor IC manufacturing technology, and social demands for high-density magnetic recording, such as narrower tracks, narrower magnetic gaps, and multi-tracks, have been made. We are beginning to be able to respond to these demands.

Many structures for thin film magnetic heads have been proposed. FIG. 3 shows a thin film magnetic head having a two-layer multi-turn coil structure as the most typical conventional structure example. Hereinafter, a conventional thin film magnetic head will be explained with reference to the drawings.

FIG. 3 is a sectional view of a conventional thin film magnetic head. In FIG. 3, 1 is a ferromagnetic substrate with high magnetic permeability such as Mn/Zn single crystal ferrite, and 2 is SiO ₂ , Si, etc. formed on the ferromagnetic substrate 1 by sputtering, plasma CVD, etc. ₃ N ₄ etc. 1st
It is an insulating layer. A first thin film coil 3 is provided on the first insulating layer 2, and has four turns in FIG. 3. The thin film coil 3 is made of copper, aluminum, gold, etc., and is formed into a film by sputtering, vapor deposition, electroplating, etc., and then patterned into a desired shape by photolithography. 4 is a second insulating layer for insulating the first thin film coil 3; The second insulating layer 4 may be made of the same material as the first insulating layer 2 and patterned into a desired shape, or may be made of heat-resistant photoresist, in which case it is thermally cured after patterning to form the coil insulating material. It is something. After the surface of the second insulating layer 4 is planarized by an appropriate method, a second layer of the second thin film coil 5 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 has a through hole 8 forming a back gap.
It is wound in a spiral shape around the center. The second thin film coil 5 is formed of the same material and through the same process as the first thin film coil 3. A third insulating layer 7 insulates the second thin film coil 5, which is made of the same material and formed by the same process as the second insulating layer 4, and whose surface is planarized. The method of forming the above-mentioned through holes 8 at the step of patterning each insulating layer has problems with dimensional accuracy, number of steps, etc. Therefore, the first
The second,
It is preferable to complete the process by patterning the third insulating layers 4 and 7 into a desired shape all at once. A back magnetic pole 9 is formed in the through hole 8 prior to the formation of the magnetic pole 10, and the ferromagnetic substrate 1
It is connected with. Reference numeral 10 denotes a magnetic pole, which is a soft magnetic thin film made of permalloy, sendust, or amorphous alloy having high magnetic permeability. Manufacturing methods include sputtering, electron beam evaporation, and electroplating, and patterning is performed using photolithography. Reference numeral 11 denotes a protective layer for protecting the magnetic pole 10, in which an insulating film of SiO, SiO ₂ , Al ₂ O ₃ or the like is laminated using a vapor deposition method or a sputtering method. Thereafter, a bulk protective substrate 13 made of ceramic, glass, or the like is bonded via an adhesive 12, and the tip of the head is processed and mirror-polished for the purpose of stable running with the magnetic recording medium 15 and creation of a magnetic gap depth.

The operation of the thin film magnetic head constructed as described above will be explained. The magnetic gap 14 as a thin film magnetic head is formed with the thickness of the first insulating layer 2. During a recording operation, a recording current is applied to the thin film coils 3 and 5, and the magnetic pole 10→magnetic gap 1
An induced magnetic flux is generated that flows through the path 4→magnetic recording medium 15→ferromagnetic substrate 1→back gap magnetic pole 9→magnetic pole 10, and a signal is recorded on the magnetic recording medium 15. During reproduction operation, the signal magnetic flux from the magnetic recording medium 15 on which information is recorded flows through the magnetic circuit and interlinks with the thin film coils 3 and 5, so that the reproduction signal is generated between both terminals of the thin film coils 3 and 5. get the output.

Furthermore, a thin film magnetic head having a different structure has been proposed in Japanese Patent Application Laid-open No. 119613/1983.
A sectional view thereof is shown in FIG.

A recent thin film magnetic head will be explained below with reference to FIG. In FIG. 4, a Sendust film is formed as a lower magnetic layer 21 by sputtering on a nonmagnetic substrate 20 made of alumina or the like. The head tip side on this lower magnetic layer 21 has a film thickness corresponding to the magnetic gap length.
A back magnetic pole piece 24 is formed by patterning on the tip magnetic pole piece 23 and the back gap portion, sandwiching a gap layer 22 such as SiO ₂ . Further, between the tip magnetic pole piece 23 and the bag magnetic pole piece 24 and on the lower magnetic layer 21, a thin film coil 26 and a coil insulating layer 27 are filled with a first insulating layer 25 interposed therebetween. At this point, the coil insulating layer 27, the tip magnetic pole piece 2
3. The upper surfaces of the bag magnetic pole pieces 24 are adjusted so that they are in the same plane. On this flattened plane, an upper magnetic layer 28 made of a permalloy film is formed by sputtering to connect the tip magnetic pole piece 23 and the bag magnetic pole piece 24. Thereafter, a protective layer 29 made of a SiO ₂ film or the like is formed, and a nonmagnetic protective substrate 31 is bonded with an adhesive 30.

Regarding the operation, it is the same as the configuration shown in FIG. 3, but the magnetic circuit in the configuration shown in FIG. It is formed of.

Problems to be Solved by the Invention However, the structure described above has several problems for the following reasons.

(1) Due to the head configuration shown in FIG. 3, the thickness of each of the thin film coils 3 and 5 and the coil insulating film (second and third insulating layers 4 and 7 in FIG. 3) is
Approximately 2 μm is required. As a result, large stepped portions a, b or recessed portions c are formed in the magnetic pole 10. In a magnetic pole formed by a sputtering method, etc., the film thickness at the stepped portions a and b is thinner than the other flat portions, and the cross-sectional area through which magnetic flux flows becomes smaller, making magnetic saturation more likely to occur. . Further, as the coil becomes more multi-layered, as in the case of a two-layer thin film coil structure as shown in FIG. 3, the step value of the step portions a and b increases. This causes a large deterioration in the magnetic permeability of the magnetic pole 10 at the stepped portion. The above phenomenon is the main cause of the decline in recording efficiency and reproduction efficiency in thin film magnetic heads.

In order to prevent magnetic saturation, the magnetic film on the stepped portion of the magnetic pole 10 should be formed thickly. Otherwise, problems such as cracking and peeling of the substrate may occur. A structure shown in FIG. 4 was proposed as a method for solving this problem, that is, a structure for removing the step difference in the magnetic film. However, the problem described in the next section is shown in Figure 3.
The conventional structure shown in FIG. 4 remains.

(2) Even when the surfaces of the protective layers 11 and 29 on the magnetic pole 10 or the upper magnetic layer 28 are flattened, the protective layers 11 or 29 and the adhesive layer exposed at the tip of the head that slides on the magnetic recording medium. 30 appears at least by the amount of step of the magnetic pole 10 or the thickness step of the upper magnetic layer 28. As a result, different thin film materials are alternately exposed at the tip of the head. In the case of FIG. 3, the first insulating layer 2 made of SiO ₂ etc., the protection 11, and the magnetic pole 10 are used, and in the case _of FIG. 2
9, adhesive 30, etc., and uneven wear of the tip of the head is likely to occur due to sliding contact with the magnetic recording medium. The amount of uneven wear increases as the thicknesses of the magnetic pole 10, the protective layer 11 or 29, and the adhesive layer 30 increase. In particular, in the structure shown in Figure 3, as the number of laminated thin film coils increases, the amount of step increases, and naturally the magnetic pole 1
The film thickness required for the protective layer 11 on 0 must be large. Generally, the protective layers 11 and 29 shown in FIGS. 3 and 4 are made of materials such as SiO ₂ and Al ₂ O ₃ , but they are not compatible with the ferromagnetic substrate 1, the nonmagnetic substrate 20, or the magnetic thin film constituting the magnetic circuit. Due to the large difference in coefficient of thermal expansion, troubles during manufacturing caused by the protective layers 11 and 29 occur frequently, such as cracks and cracks in the substrate that occur during or after the formation of the protective layer, and peeling of the underlying thin film layer.

(3) In the structure shown in FIG. 4, the tip magnetic pole piece 23 and the back magnetic pole piece 24 are formed of sendust film prior to the formation of the thin film coil 26. As a result, the conductor of the thin-film coil 26 is formed in the recessed portion, which limits the accuracy of coil patterning, making it difficult to perform fine coil patterning. Furthermore, the tip magnetic pole piece 23
and the upper magnetic layer 28 are connected in such a way that they partially overlap. This is a major cause of magnetic saturation, as it becomes necessary to reduce the length and area of the overlapping portion when the gap depth is shortened as a means to improve recording/reproducing sensitivity.

In view of the above-mentioned problems, the present invention aims to improve the recording and reproducing efficiency of thin-film magnetic heads, and in particular, makes it possible to apply a magnetic recording medium with high coercive force that enables high-density digital recording and reproduction, and also has uneven wear characteristics. The object of the present invention is to provide a thin film magnetic head that can improve the performance and production yield.

Means for Solving the Problems In order to solve the above-mentioned problems, the thin film magnetic head of the present invention removes the step of the magnetic thin film and the thick protective layer that is caused by the step. The recesses of the head tip magnetic gap and back magnetic gap are filled with a high permeability magnetic film, and adjusted according to an optimal manufacturing process so that its surface is flush with the top surface of the uppermost insulating layer of the thin film coil. A high permeability magnetic film is attached on this plane, and this high permeability magnetic film extends to the tip of the head. After coating this surface with a thin insulating film, a non-magnetic protection substrate is overlaid. ing.

Effects of the present invention: After a single-layer or multilayer thin-film coil insulating layer on the uppermost surface is formed according to the above-described structure, the coil insulating layer is pattern-etched to form a tip magnetic gap portion and a back magnetic gap. At this point, the step or recess formed in the coil insulating layer is filled with a high permeability magnetic film material to form a back magnetic gap in a state where the tip magnetic gap length and magnetic path magnetic resistance are approximately zero. The magnetic film material is flattened to be flush with the uppermost surface of the coil insulating layer to form a tip magnetic pole piece and a back magnetic pole piece, and at this point the step of the magnetic film is removed. The separated tip magnetic pole piece and back magnetic pole piece are connected by an upper magnetic layer consisting of a high permeability magnetic film deposited thereon. As a result of the tip magnetic pole piece and the upper magnetic layer being stacked flat on the tip magnetic gap, there are no steps on the magnetic flux propagation path, and there is no thick film protective layer and thick film adhesive that are exposed at the tip of the conventional head. becomes unnecessary.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a second embodiment of the present invention.
1 shows a cross-sectional view of a thin film magnetic head with a layered four-turn coil structure.

In Figure 1, 40 is Mn with high magnetic permeability.
-A ferromagnetic substrate made of Zn single crystal ferrite, Ni-Zn ferrite, etc., and its surface is mirror polished. On the ferromagnetic substrate 40, SiO ₂ , Al ₂ O ₃ ,
A first insulating layer 41 made of Si ₃ N ₄ or the like is formed with a thickness corresponding to the magnetic gap length. The sputtering method, plasma CVD method, etc. are commonly used as a thin film forming method. Thereafter, a small window 42, which serves as a back magnetic gap, is opened using an etching technique.
Reference numeral 43 denotes the first thin film coil which is the first layer, which has four turns in Fig. 1, after a conductive metal such as Cu or Al is attached by sputtering, vapor deposition, electroplating, etc. , is patterned into a coil shape using an etching method. A second insulating layer 4 is provided on the thin film coil 43 for the purpose of insulating the thin film coil.
4 is given. This second insulating layer 44 is made of SiO ₂ ,
In addition to Al ₂ O ₃ , Si ₃ N ₄ , etc., heat-resistant photoresists can also be used as interlayer insulation materials. Second
The surface of the insulating layer 44 is flattened. 45 is a second thin film coil formed in the second layer;
It is connected to the thin film coil 43 through a through hole 59 formed in the second insulating layer 44 . A third insulating layer 46 is formed on the second thin film coil 45 using the same manufacturing method as the second insulating layer 44 . This third insulating layer 46 is also planarized by appropriate means in the same way as the second insulating layer 44, and then the tip magnetic gap 4 is flattened.
7 and a through hole 42 that becomes a back magnetic gap.
In order to form a through hole, the second and third insulating layers 44 and 46 are etched together in a desired shape. The maximum etching step difference occurring at this point is h as shown in FIG. After this Sendust,
A ferromagnetic film material having high magnetic permeability, such as an amorphous alloy, is deposited using a sputtering method or the like to a film thickness that is equal to or larger than the step h. This ferromagnetic film material is
The uppermost coil insulating layer (in the case of FIG. 1, the third insulating layer 4) of the thin-film coil is
6) Flatten the surface so that it is flush with the surface.
Through this processing, a tip magnetic pole piece 48 and a back magnetic pole piece 49 are formed from the ferromagnetic film material. Sendust,
An upper magnetic layer 50 having high magnetic permeability such as an amorphous alloy is laminated. After this, the thickness is sufficient to completely cover at least the surface of the upper magnetic layer 50.
A thin protective layer 51 of 1 μm or less is coated. Finally, a non-magnetic protection substrate 53 is placed with adhesive 52. The bonding method includes a glass film with a relatively high melting point that is attached to the non-magnetic protective substrate 53 in advance;
An extremely thin adhesive layer can be created by melt-bonding SiO ₂ film, etc.

FIG. 2 shows the main manufacturing process after the second and third insulating layers 44 and 46 are etched to form a step or through-hole small window 42, and is similar to FIG. Identical members are given the same numbers. Figure 2 A shows the thickness of the high permeability magnetic film 54 made of Sendust, amorphous alloy, etc.
It is attached at h'(h'>h). The surface of this magnetic film 54 has a step reflecting the shape of the underlying layer, and is coated with photoresist 55 to flatten the surface. Thereafter, etching is performed by irradiation with an ion beam 56. The incident angle θ of the ion beam 56 is adjusted so that the etching rates of the photoresist 55 and the magnetic film 54 are equal. Etching is performed to a predetermined depth (dotted line). In Figure B, an unnecessary magnetic film 57 remains where the tip magnetic pole piece 48 and the back magnetic pole piece 29 have been formed. Figure C shows the point at which a high permeability magnetic film 58 has been deposited to form the upper magnetic layer 50. In the figure D, the magnetic film 5
8 is patterned into a predetermined shape to form the upper magnetic layer 5.
0 is formed. At this time, unnecessary magnetic film 57 is also removed. The surface of the upper magnetic layer 50 is covered with a thin protective layer 51 such as SiO ₂ .

The operation of the thin film magnetic head constructed as described above will be explained below.

The feature of this embodiment is that the sharp step in the magnetic flux transmission path made of a high permeability magnetic material is removed to increase magnetic efficiency, and as a result of the magnetic path being made of a member with a flat surface, the tip of the head The purpose is to improve uneven wear characteristics due to the thin film composite layer exposed to the surface. This will be explained in detail with reference to FIG.

After the third insulating layer 46 on the second thin film coil 45 is formed, it is etched into a predetermined shape as described in the process of FIG. As a result, a step or a recess is created by the third insulating layer on the first insulating layer 41 which becomes the tip magnetic gap 47 and on the small window 42 which becomes the back magnetic gap. The tip magnetic pole piece 48 and the back magnetic pole piece 49 are formed by filling this step or recess with a high magnetic permeability magnetic film to maintain high magnetic permeability. 47 and the gear depth is determined, and the latter is short-circuited with the ferromagnetic substrate 40 to improve the magnetic circuit efficiency. The upper magnetic layer 51 extending to the tip of the head is the tip of the magnetic pole piece 4.
8 and the back magnetic pole piece 49 to form a closed magnetic path, magnetic saturation is prevented at the joint with the tip magnetic pole piece 48 near the tip of the head, and the gear depth can be set arbitrarily. Moreover, since the upper surface of the upper magnetic layer 51 is flat up to the tip of the head, the bonding member to the bulk nonmagnetic protective substrate 53 can be made thin. In other words, there is no need for a thick protective layer or a thick adhesive that is exposed at the tip of the head, as seen in conventional structures.

The members used for magnetic flux propagation during both recording and reproduction are comprised of a tip magnetic pole piece 48, an upper magnetic layer 50, a back magnetic pole piece 49, and a ferromagnetic substrate 40. Although the tip magnetic gap 47 is formed of the first protective layer 41 in the embodiment of FIG. 1, it may be formed of the second insulating layer 44 or the third insulating layer 45. When an amorphous alloy or sendust is used as the thin film magnetic material, an annealing treatment is required to obtain high magnetic permeability, but this is performed after the thin protective layer 51 on the upper magnetic layer 50 is formed, or annealing is performed on the protective substrate. It can also be performed at the same time as bonding 53.

As described above, according to this embodiment, after a high permeability magnetic film is laminated on the stepped portion or the recessed portion according to the optimum manufacturing process, the tip magnetic pole piece 48 and the back magnetic pole piece 49 with flat surfaces are formed by etching. Furthermore, by stacking a flat upper magnetic layer 50 having high magnetic permeability and extending to the tip of the head, (1) steps in the magnetic film on the magnetic flux transmission path are removed;
A magnetic circuit with high magnetic flux propagation efficiency can be realized without deteriorating the magnetic permeability of the magnetic film.

(2) Tip magnetic pole piece 48 and upper magnetic layer 50
Since both of them form a gap depth with the tip magnetic gap 47 in a laminated state, the gap depth can be arbitrarily set without causing magnetic saturation at the tip of the head. It is especially effective when increasing head efficiency with a shallow gear depth.

(3) There is no need to interpose a thin film protective layer that is larger than the level difference between the magnetic pole or upper magnetic layer and the protective substrate as seen in conventional structures, and a different type of thin film is exposed at the tip of the head that slides on the magnetic recording medium. Uneven wear characteristics caused by the composite layer and its thickness can be significantly reduced. In addition, high coercive force media (coercive force is approx.
In a recording head compatible with 1000O¨e to 1500O¨e), the conventional magnetic pole step or thickness difference in the upper magnetic layer reaches 6 to 10 μm, and the thickness of the thin film protective layer is approximately 20 μm before planarization. film formation is required. This protective layer is often composed of SiO ₂ , Al ₂ O ₃ , etc., but it is generally made of SiO 2 or Al 2 O 3 during or after the formation of the protective layer due to the large difference in thermal expansion coefficient from the ferromagnetic substrate or magnetic film. Cracks in the board; cracks;
Cracks and peeling of the underlying thin film layer occur frequently. Removing the thick protective layer greatly helps improve production yield and quality.

(4) Because the thin film coil is formed prior to adhesion of the magnetic film in the manufacturing process, fine patterning of the thin film coil is easy.

Although the embodiment has been explained using a single-track structure, it is obvious that the same effect can be obtained in a multi-track head.

Effects of the Invention The present invention forms a tip magnetic pole piece and a back magnetic pole piece with flat surfaces using an etching method, and laminates an upper magnetic layer extending to the tip of the head on top of the top magnetic pole piece, thereby removing the step in the magnetic film. It can contribute to improving recording efficiency and reproduction efficiency. Furthermore, the thick protective layer exposed at the tip of the head can be removed, resulting in a number of excellent effects such as improving uneven wear characteristics, improving productivity, and stabilizing quality due to the composite layer of different thin films and its total thickness. This makes it possible to realize a thin film magnetic head that can obtain the following characteristics.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a thin-film magnetic head according to an embodiment of the present invention, FIG. 2 is a process diagram showing an example of the manufacturing process of the present invention, and FIGS. 3 and 4 are cross-sectional views of a conventional thin-film head. be. 40... Ferromagnetic substrate, 41, 44, 46... First, second, third insulating layer, 43, 45... First,
Second thin film coil, 42...Small window, 47...Tip magnetic gap, 48, 49...Tip magnetic pole piece, back magnetic pole piece, 50...Top magnetic layer, 51...Protective layer, 53... Protection board, 5
4, 57, 58...Magnetic film, 55...Photoresist, 56...Ion beam, 59...Through hole.

Claims (1)

[Claims] 1 A high magnetic permeability ferromagnetic substrate, a first insulating layer is formed on the high magnetic permeability ferromagnetic substrate, a thin film coil and an insulating layer of the thin film coil are sequentially laminated on the insulating layer, and the thin film coil Constructed of a flat optical end magnetic pole piece and a back magnetic pole piece whose height is adjusted to be flush with the top surface of the insulating layer, and a high permeability upper magnetic layer that extends to the tip of the head on the above plane. and a non-magnetic protective substrate provided on the main member via a thin film protective layer and an adhesive layer, and the thin film coil is formed of the first insulating layer or the thin film coil insulating layer. A thin film magnetic head that is wound so as to generate a magnetic field in the formed tip magnetic gap and read signals on a magnetic recording medium.