JPH05290325A - Production of thin-film magnetic head - Google Patents

Abstract

PURPOSE:To relieve the level difference at the time of forming an upper coil layer and an upper magnetic layer. CONSTITUTION:A recessed part is provided on an insulating layer 20 formed on a ceramic substrate 19 and a lower magnetic layer 23 is formed thereon. A magnetic gap layer 24 is formed by sputtering and a lower insulating layer 25 is embedded into the recessed part. Further, a lower coil layer 26 is embedded thereon in the recessed part by electroplating of copper, etc., and a middle insulating layer 28 is formed by using the same material as the material of the lower insulating layer 25. A protective material 29 is patterned and formed in the track forming part 21 and back gap part 22 of the lower magnetic layer 23 and thereafter, an inorg. insulator 30 is stuck over the entire surface of the substrate. An upper coil layer 27 is formed in the same manner as with a lower coil layer 26 on the inorg. insulator 30 subjected to flattening. The protective material 29 is removed by chemical etching and an upper insulating layer 31 is formed of the material similar to the material of the lower insulating layer 25. The upper magnetic layer 32 is then formed by the same method as for the lower magnetic layer 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film magnetic head for a magnetic disk device such as a computer.

[0002]

2. Description of the Related Art As the performance of magnetic disk devices has become higher, thin film magnetic heads have been required to have various performances. In order to improve the areal recording density of the magnetic disk device, it is necessary to increase the linear recording density and the track density. The former requires high frequency operation and the latter requires narrower tracks.

In an inductive thin-film magnetic head, the head output decreases as the track becomes narrower, so it is necessary to increase the number of coil turns. At that time, simply increasing the number of coil turns increases the magnetic path length, which causes a decrease in head efficiency due to an increase in magnetic resistance, a decrease in resonance frequency due to an increase in inductance, and an increase in noise due to an increase in electric resistance. Not only will the characteristics of the magnetic head be impaired, but it will not function as a magnetic head. Further, in order to narrow the track, it is necessary to reduce the track size and at the same time improve the accuracy of controlling to the target size. As described above, in order to improve the performance of the thin film magnetic head, the pattern forming technique for forming the coil and the track with higher accuracy and the head structure have become very important factors.

A conventional thin film magnetic head is shown in FIG. In the figure, reference numeral 1 denotes a slider in which elements are formed on a ceramic substrate, and a gimbal is adhered to the levitation rail 2 in parallel to the back surface side to be mounted on a magnetic disk device to form a magnetic head assembly state. The thin film magnetic head element is formed on the front side of the slider 1, and 3 is an upper insulating layer and 4 is an upper insulating layer.
Indicates an upper magnetic layer, and 5 indicates a terminal. FIG. 3 is an enlarged view of a portion A in FIG. 2, in which 6 is a back gap portion for adhering the upper magnetic layer 4 and the lower magnetic layer, and TW is a track width. 4 is a sectional view taken along line BB in FIG. 3, in which the ceramic substrate 7 is covered with an insulator 8 such as alumina by sputtering or the like, and the lower magnetic layer 9 is formed thereon by electroplating or sputtering. A non-magnetic magnetic gap layer 10 is laminated on the lower part, a lower insulating layer 11 made of a resin such as a novolac resin or a polyimide resin, and a lower coil layer 12 are sequentially laminated by electroplating or the like, and a lower insulating layer 11 is formed thereon. Middle insulating layer 13 and upper coil layer 1 made of the same resin
4, the upper insulating layer 3 and the upper magnetic layer 4 are sequentially laminated and finally protected by an insulator 15 such as alumina.

The problems of the conventional thin film magnetic head will be described below with reference to FIG.
The coil shown in will be described. In the figure, a lower magnetic layer 9 and a magnetic gap layer 10 are formed after an insulating layer 8 is attached to a ceramic substrate 7 to eliminate a step generated by the lower magnetic layer 9 and to insulate the lower coil layer 12 from a novolac system. Alternatively, the lower insulating layer 11 made of a resin such as polyimide is formed. A lower coil layer 12 is formed on the flat surface by electroplating, and further, insulation between the lower coil layer 12 and the upper coil layer 14 is obtained, and a middle portion is made of a resin having the same composition as that of the lower insulating layer 11 in order to obtain a flat surface. Insulating layer 13
To provide. Next, to form the upper coil layer 14, a metal film 16 for use as an electrode for electroplating is deposited on the entire surface of the substrate by sputtering or vapor deposition, and a photoresist 17 for forming a coil pattern is applied on the entire surface and dried. The coil pattern is formed by irradiating only the optically transparent region through the photomask 18 with ultraviolet rays, and dissolving and removing the ultraviolet rays by development. The photoresist 17 of the coil pattern is removed, and the upper coil layer 14 is attached to the exposed portion of the metal film 16 by copper electroplating. The photoresist 17 and the metal film 16 that are no longer needed are removed to remove the upper coil layer. 14
Can be formed.

Here, the upper coil layer 14 is a laminated film of about 5 μm in the lower magnetic layer 9, about 3 μm in the lower insulating layer 11, about 4 μm in the lower coil layer 12, and about 2 μm in the middle insulating layer 13 so as to have a total thickness of about 14 μm. Is located at a position having a step T formed by. Upper coil layer 1 at this position
Photoresist 1 for making 4 coil patterns
7 must be applied on such a high step, but since the photoresist 17 is a viscous fluid at the time of application, the applied film thickness is thin above the step and thick below the step. This change in film thickness is most noticeable near the rise of the step,
Even on the same step, the film thickness t1 at the rising portion of the step and the film thickness t2 at the central portion of the step are different, and the former is always thinner. The important parameters here are the exposure energy, the concentration of the developing solution and the developing time, and controlling them to be optimum and making them uniform are important points for making the pattern more accurate.

However, since the thickness of the photoresist 17 varies, the optimum pattern forming conditions are different for each position where the thickness is different. Therefore, when such regions of the photoresist 17 having different film thicknesses are present at the same time, if the conditions are adjusted to the places where the film thickness is thin, the region where the film thickness is thick is underexposed and underdeveloped, and a resist residue occurs. Therefore, it is necessary to match the pattern forming conditions with the thick film. Then, the thin film portion is overexposed and overdeveloped with respect to the optimum conditions, and the remaining width of the photoresist 17 is narrowed,
The pattern width fluctuates, and the fidelity of the pattern dimension with respect to the dimension of the photomask 18 decreases. In an extreme case, the photoresist 17 is reduced in film thickness, resulting in a short circuit of the coil and a reduction in yield. Due to the above reasons, it is difficult to reduce the coil pitch.

Further, as the number of turns of the coil is increased, the electric resistance of the coil is increased.
Although it must be made thicker, it is difficult to apply a thicker photoresist 17 with a conventional thin film magnetic head having a step structure, and the phenomenon of fluctuation of the film thickness on the step and waviness of the photoresist 17 is more remarkable. Will be. Although the above causes a technical limit when creating a coil, if the coil pitch remains unchanged and the number of coil turns is simply increased without increasing the magnetic path length, the number of layers of the coil can be reduced. The number of layers is more than two, but this is a complicated solution, and the coil patterns of the third layer and above only make the above problems more conspicuous, and it is more difficult to make and the cost increases, which is a good solution. It doesn't help.

Next, as another problem, pattern formation of the upper magnetic layer 4 will be described with reference to FIG. In the figure, an insulating layer 8 is formed on a ceramic substrate 7, and a lower magnetic layer 9, a magnetic gap layer 10, a lower insulating layer 11, a lower coil layer 12, a middle insulating layer 13, an upper coil layer 14, and an upper insulating layer 3 are sequentially formed. The layers are laminated and the upper magnetic layer 4 is formed by electroplating. In this case, the electrode metal film 16 for electroplating is deposited and formed on the entire surface of the substrate by sputtering or vapor deposition. Next, the upper magnetic layer 4
A photoresist 17 for forming the above is applied, dried, and the substrate is irradiated with ultraviolet rays through a photomask 18 and then developed to form a pattern of the upper magnetic layer 4. At this time, the upper magnetic layer 4 is about 4 μm thicker than the step T of about 14 μm when the upper coil layer 14 is formed,
And the step height H of about 2 μm of the upper insulating layer 3 is 20 μm
It must be created with a level difference of about m.

Although the important dimension of the upper coil layer 14 is formed on the step, the important dimension of the upper magnetic layer 4 is formed on the rising portion of the step. The photoresist 17 for forming the upper magnetic layer 4 has a back gap portion 6 (see FIG. 3) where the upper and lower magnetic layers come into contact with each other at a portion where the thickness is thickest due to the influence of the step H, and a portion where a thicker portion is next to form a track. Then, the film thicknesses h2 and h1 are considerably thicker than the film thicknesses applied to the flat portions. The track width TW (see FIG. 3), which is an important dimension in the magnetic head, must be formed at the position of the film thickness h1 at the rising part of the step, but this part is where the film thickness changes abruptly, so the pattern width Is difficult to control strictly,
Considering the film thickness distribution in the substrate, a variation of about ± 1 μm occurs. Such a variation increases the variation in the characteristics as the track width becomes narrower, which is beyond the purpose of a high-performance drive device.

Further, since the back gap portion 6 becomes thickest, the photoresist 17 cannot be completely removed under the same pattern forming conditions as the track portion, which requires a highly accurate dimension. Therefore, again the back gap part 6
It is necessary to perform multiple exposure for re-exposure and development only in the area. This multiple exposure not only complicates the pattern forming process, but also causes a decrease in the operating efficiency of the pattern forming exposure device of the device which is one of the most expensive of thin film process steps. Such a problem becomes more and more remarkable when the coil thin film is increased in order to suppress the increase in the electric resistance due to the increase in the number of coil turns, and the number of coil layers is set to three.
If the number of layers is greater than or equal to the number of layers, the level difference H becomes higher, which becomes a greater problem.

[0012]

As described above, when the upper coil layer 14 is formed, the film thickness distribution of the photoresist 17 for forming the upper coil layer 14 is generated due to the influence of the step formed in the lower layer, and the coil pattern is formed. Causes width variation. Also, the formation of the upper magnetic layer 4 has a problem that the track width varies due to the influence of the step formed in the lower layer.

[0013]

In order to achieve this object, a thin film magnetic head of the present invention is provided with a recess at a position corresponding to a coil forming region of an insulating layer made of alumina or the like formed on a substrate to form a track. Part of the lower magnetic layer excluding the lower part and the back gap part, the lower insulating layer, the lower coil layer, and the middle insulating layer are buried in the recess, and the back gap is in contact with the track forming region of the lower magnetic layer and the upper magnetic layer. In the later chemical etching, the lower magnetic layer is patterned with a protective material that is selectively etched, and an inorganic insulator is deposited over the entire surface of the substrate to a thickness greater than that of the lower magnetic layer, followed by flattening and then the upper coil. A layer, an upper insulating layer, and an upper magnetic layer are formed.

[0014]

By embedding a part of the lower magnetic layer, the lower insulating layer, the lower coil layer, and the middle insulating layer in the recess, it is possible to reduce the step difference when forming the upper coil layer and the upper magnetic layer.

[0015]

EXAMPLE An example of the present invention will be described below with reference to FIGS.
This will be described with reference to (f). In the figure, 19 is a ceramic substrate, 20 is thicker than L1 to be etched with an insulating layer made of alumina or the like, and is attached to the ceramic substrate 19 by sputtering to form a lower magnetic layer 23 excluding the track forming portion 21 and the back gap portion 22. The insulating layer 20 corresponding to a part of the region and the formation region of the lower coil layer 24 is removed by etching to a depth L1. For this etching, a photoresist or the like is used as a mask to perform chemical etching or ion beam etching to remove a necessary step. Next, the lower magnetic layer 23 is formed in a recess other than the track forming portion 21 and the back gap portion 22 so that a magnetic film such as permalloy is embedded by electroplating or sputtering. {Fig. 1
(See (a)) Next, the magnetic gap layer 24 is formed by sputtering, and the lower insulating layer 25 is filled with a novolac-based or polyimide-based resin in the recess like a part of the lower magnetic layer 23.
Further, the lower coil layer 26 is embedded in the recess by electroplating of copper or the like, and the middle insulating layer 28 is formed on the lower insulating layer 28 to facilitate formation of the upper coil layer 27 after alleviating the unevenness of the lower coil layer 26. It is formed by using the same material as 25.
{Refer to FIG. 1B} The track forming portion 21 and the back gap portion 22 of the lower magnetic layer 23 are patterned with a protective material 29 which is selectively etched with respect to the lower magnetic layer 23 and the gap layer 24 in a later chemical etching. After the formation, an inorganic insulator 30 such as alumina having a thickness greater than that of the lower magnetic layer 23 and the protective material 29 is attached to the entire surface of the substrate. The lower magnetic layer 23 is used as the protective material 29.
When is a permalloy, iron-based or cobalt-based material, amorphous, or the like, copper, gold, titanium, or the like is used. The thickness of the protective material 29 is set to be at least larger than the maximum thickness of the lower magnetic layer 23. Next, in order to make the pattern of the upper coil layer 27 more precise, it is desirable that the surface formed of the inorganic insulator 30 be flat. If the formation surface of the upper coil layer 27 is flat, the upper coil layer 27
The film thickness of the photoresist for formation is substantially uniform, and as a result, the accuracy of pattern formation is improved. {Refer to FIG. 1C} Therefore, when the entire substrate is flattened until the protective material 29 appears, the lower magnetic layer 23 and the magnetic gap layer 24 are formed.
It doesn't damage. Like the lower coil layer 26, the upper coil layer 27 is formed on the flattened inorganic insulator 30 by electroplating with copper or the like. {Refer to FIG. 1D} The protective material 29 is removed by chemical etching to expose the undamaged track forming portion 21 and the back gap portion 22, and then the upper insulating layer 31 is made of the same material as the lower insulating layer 25. To form. {Refer to FIG. 1E} Next, the upper magnetic layer 32 is formed by the same method as the lower magnetic layer 23, but the thickness of the lower layer is the same as the conventional step H, but the insulating layer 20 is formed. Since the concave portion provided in 1 reduces the step difference of L1, the remaining step difference is only L2. Since the photoresist for forming the upper magnetic layer 32 has only the film thickness variation caused by the step of L2,
The film thickness variation is greatly improved, the track width accuracy of the upper magnetic layer 32 is greatly improved, and the back gap portion 22 is consequently raised when the insulating layer 20 is etched. Therefore, the photoresist in the back gap portion 22 does not become abnormally thick, and there is no need to perform multiple exposure that reduces the operating efficiency of the exposure apparatus. Next, an insulator 33 such as alumina is attached by sputtering so as to protect the entire element, thereby completing the fabrication of the thin film magnetic head. {Refer to FIG. 1 (f)} As described above, in the present embodiment, the lower magnetic layer 23, the lower insulating layer 25, and the lower coil layer 26 are basically formed as the recesses in the insulating layer 20, but the cross-sectional structure of the head is vertically symmetrical. In order to improve the characteristics of the thin-film magnetic head, and this purpose is not limited to this for the purpose of merely mitigating the step difference, the present embodiment can be used to reduce the step difference from only the lower magnetic layer 23 to the upper insulating layer 31. It can be widely applied to alleviate steps.
Further, in the present embodiment, the effect becomes greater when the coil film thickness is increased in order to prevent an increase in electric resistance due to an increase in the number of turns, or when the number of coil layers is more than two.

The present invention is not limited to the specific examples shown above, and for example, the back gap portion 22 of the lower magnetic layer 23 is not required to be as accurate as the track forming portion 21. Therefore, the insulating layer 20 below the track forming portion 21 or the lower insulating layer 25 itself may be made thicker than the others so that the lower magnetic layer 23 of the back gap portion 22 appears during the flattening process.

[0017]

As described above, according to the present invention, a part of the lower magnetic layer, the lower insulating layer, and the lower coil layer are formed so that the insulating layer formed on the substrate is provided with the concave portion and buried in the concave portion. , By eliminating or reducing the step when forming the upper coil layer or the upper magnetic layer,
Also, the film thickness distribution and fluctuation of the photoresist for forming the upper magnetic layer can be reduced, and the performance of the thin film magnetic head can be improved by making the upper coil layer and the upper magnetic layer highly accurate. .. Further, since it is possible to suppress unnecessary approach of the upper and lower magnetic layers other than the track portion and the back gap portion, the magnetic efficiency of the thin film magnetic head is improved.

[Brief description of drawings]

1A is a schematic diagram of a manufacturing process of a thin film magnetic head of the invention, FIG. 1B is a schematic diagram of a manufacturing process of a thin film magnetic head of the invention, and FIG. 1C is a manufacturing process of a thin film magnetic head of the invention. Schematic diagram (d) is a schematic diagram of the manufacturing process of the thin film magnetic head of the present invention (e) is a schematic diagram of the manufacturing process of the thin film magnetic head of the present invention (f) is a schematic diagram of the manufacturing process of the thin film magnetic head of the present invention

FIG. 2 is a schematic diagram of a conventional thin film magnetic head.

3 is an enlarged view of part A of FIG.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a schematic diagram of a conventional thin film magnetic head.

FIG. 6 is a schematic diagram of pattern formation of an upper magnetic layer of a conventional thin film magnetic head.

[Explanation of symbols]

 1 slider 2 levitation rail 3 upper insulating layer 4 upper magnetic layer 5 terminal 6 back gap part 7 ceramic substrate 8 insulator 9 lower magnetic layer 10 magnetic gap layer 11 lower insulating layer 12 lower coil layer 13 middle insulating layer 14 upper coil layer 15 Insulator 16 Metal film 17 Photoresist 18 Photomask 19 Ceramic substrate 20 Insulating layer 21 Track forming part 22 Back gap part 23 Lower magnetic layer 24 Magnetic gap layer 25 Lower insulating layer 26 Lower coil layer 27 Upper coil layer 28 Middle insulating layer 29 Protective material 30 Inorganic insulator 31 Upper insulating layer 32 Upper magnetic layer 33 Insulator

Claims (1)

[Claims] 1. A recess is provided in a coil layer forming region of an insulating layer formed on a substrate, and a part of a lower magnetic layer, a lower insulating layer, a lower coil layer and a middle insulating layer are buried in the recess, and a gap layer is formed. The protective material is deposited on the track forming region of the lower magnetic layer and the lower magnetic layer and the upper magnetic layer in contact with each other, and the back gap region on the lower magnetic layer is thicker than the film thickness of the lower magnetic layer. A pattern is formed, an insulating material having a thickness larger than that of the lower magnetic layer is deposited on the entire substrate, and then flattening is performed, and an upper coil layer, an upper insulating layer, an upper magnetic layer, and the like are sequentially laminated on the pattern. A method of manufacturing a thin film magnetic head, comprising: