JPH0520640A - Production of thin-film magnetic head - Google Patents

Abstract

PURPOSE:To improve the performance of the thin-film magnetic head by providing an insulating layer and recessed part formed on a substrate and forming and embedding a part of a lower magnetic layer as well as a lower insulating layer or lower coil layer therein. CONSTITUTION:The recessed part is provided in the position corresponding to the coil forming region of the insulating layer 2 which is formed on the substrate 1 and consists of aluminum, etc. A part of the lower magnetic layer 3 exclusive of a track forming part X and a back gap part & as well as the lower insulating layer 4 and the lower coil layer 6, etc., are embedded and formed in this recessed part. The steps to be generated before the formation of the above-mentioned layers are eliminated or decreased at the time of forming the upper coil layer 8 and the upper magnetic layer 10 if these layers are formed in such a manner. The fluctuation in the film thickness distribution of the photoresist for forming the upper coil layer 8 and the upper magnetic layer 10 is suppressed in this way and the high-accuracy patterns are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high performance thin film magnetic head.

[0002]

2. Description of the Related Art As the performance of magnetic disk devices increases, the thin film magnetic heads used therein are 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 (BPI) and the track density (TPI). For the former, the high frequency operation of the thin film magnetic head, and for the latter, Narrower track is required.

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, if the number of coil turns is simply increased by extending the conventional technology, the magnetic path length of the head increases, so the head efficiency decreases due to an increase in magnetic resistance, and the high frequency operation is disabled due to an abnormal increase in inductance (resonance frequency decreases). ) And increase in noise due to increase in direct current resistance, not only impairing the characteristics of the thin film magnetic head but also failing to function as a magnetic head.

Further, when narrowing the track, it is necessary to reduce the 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 coil pattern, the pattern forming technique for forming the track with higher precision, and the head structure capable of improving the coil pattern with higher precision are extremely important factors. It has become to.

2A and 2B are a conceptual diagram (a) and a sectional structure (b) of a thin film magnetic head. The thin film magnetic head is formed on a ceramic substrate by a thin film forming technique. When the thin film magnetic head is mounted on the magnetic disk device, a parallel gimbal is attached to the flying rail 21 in parallel with the back surface side to bond the parallel magnetic gimbal to the magnetic head. Set to the assembled state. The thin film magnetic head element portion B is formed on the front side of the slider 12, 9 is an upper insulating layer, 10 is an upper magnetic layer, and 13 is a terminal.

FIG. 2B is an enlarged cross-sectional view of the thin film magnetic head element portion B, where 14 is a back gap portion where the upper magnetic layer 10 and the lower magnetic layer are joined, and T. W. Indicates the track width.

FIG. 3 is a sectional view taken along the line AA 'of FIG.
This is a specific structure of the thin film magnetic head. This thin film magnetic head is manufactured by forming a lower magnetic layer 3 formed by an electroplating method or a sputtering method on a ceramic substrate 1 covered with an insulating layer 2 such as alumina formed by a sputtering method, and a magnetic layer formed by the sputtering method. The gap layer 5 is laminated, and the lower insulating layer 4 made of a novolac-based or polyimide-based resin and the lower coil layer 6 formed by electroplating or the like are sequentially laminated thereon. Further, similarly to the lower insulating layer 4, a middle insulating layer 7, an upper coil layer 8, an upper insulating layer 9 and an upper magnetic layer 10 are sequentially laminated thereon, and finally protected by a protective layer 11 made of an insulating material such as alumina. It has become a shape.

Problems of the conventional thin film magnetic head having the above-mentioned structure will be described. First, the thin film magnetic head is shown in FIG.
A coil is formed in the shape shown in. That is, after depositing the insulating layer 2 on the ceramic substrate 1, the lower magnetic layer 3 and the gap layer 5 are formed, and the lower magnetic layer 3 and the lower coil layer 6 are formed.
A lower insulating layer 4 made of photoresist or polyimide resin is formed in order to facilitate the insulation between the lower magnetic layer 3 and the lower magnetic layer 3 and to facilitate the formation of the lower coil layer 6.

Next, the lower coil layer 6 is formed on the lower insulating layer 4.
It is formed by electroplating on the flat surface formed by. Further, in order to insulate the lower coil layer 6 from the planned upper coil layer 8 (see FIG. 3) and to flatten the upper coil layer formation surface, the middle insulating layer 7 is made of the same material as the lower insulating layer 4. Form.

Next, in forming the upper coil layer 8, first, a metal film 15 made of copper or the like is deposited on the entire surface of the ceramic substrate 1 by sputtering or vapor deposition to serve as an electrode during electroplating. After that, photoresist 16 for coil pattern formation
Is applied to the entire surface, dried, and is irradiated with ultraviolet rays through a photomask 17 only on the optically perforated portions.

Next, when the photoresist 16 is a positive type, only the portion irradiated with ultraviolet rays is dissolved by development,
After the removal, the coil pattern formation is completed.

The portion of the coil pattern formed as described above where the photoresist has been removed is the metal film for the electrode.
Since 15 is exposed, the metal film 15
The plating film selectively adheres only to the exposed portion.

Since copper, which has the lowest specific resistance among metals, is usually used for the coil layer, a copper sulfate-based plating solution is often used as the plating solution. After plating, the photoresist 16 and the metal film 15 for electrodes that are no longer needed are removed, and the formation of the upper coil layer 8 (not shown) is completed. Here, the upper coil layer was formed of a laminated film of about 5 μm in the lower magnetic layer 3, about 3 μm in the lower insulating layer 4, about 4 μm in the lower coil layer 6, and about 2 μm in the middle insulating layer 7 as a whole, about 14 μm. It must be formed on the head element having the step T.

By the way, the photoresist 16 for forming the coil pattern of the upper coil layer must be applied on such a high step, but since the photoresist is a viscous fluid at the time of application, its coating film The thickness is thin above the step and thick below the step. This change in the film thickness becomes most pronounced at the rising edge vicinity of the step, as shown in FIG. 4, even the same steps on different film thickness t ₂ of the central portion of the film thickness t ₁ and the step of the rising portion of the step, the former t ₁ is always lighter.

Here, the important parameters for pattern formation are the exposure energy, the concentration of the developing solution and the developing time, and it is important to control them to optimum conditions and make them more uniform in order to make the pattern more accurate. It is a point.

However, as shown in FIG. 4, since the upper coil layer has a distribution of the film thickness of the photoresist at the place where the pattern is to be formed, the optimum pattern forming condition is that the film thickness is different for each position. Will be different.

Therefore, when regions having different photoresist film thicknesses are present at the same time, when the conditions for pattern formation are adjusted to the thin film thicknesses, the thick film thicknesses result in insufficient exposure and insufficient development. Since a resist residue is generated, it is necessary to match the pattern forming conditions with the thick film.

Then, where the film thickness is thin, overexposure and overdevelopment are performed under the optimum conditions, and the remaining width of the photoresist becomes small, resulting in fluctuation of the pattern width.
The fidelity of the pattern dimension with respect to the photomask dimension decreases. In an extreme case, the film thickness of the photoresist is reduced, resulting in a short circuit of the coil and a reduction in the yield, which makes it difficult to shorten the coil pitch.

When the number of turns of the coil is increased, the DC resistance of the coil is increased.
Although it must be thicker than m, it is difficult to apply a thicker photoresist with the 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 are more remarkable. Will be.

Although the above has reached the technical limit in producing a coil, if the coil pitch is simply increased and the number of turns of the coil is simply increased without increasing the magnetic path length, the number of turns of the coil can be increased. The number of layers may be larger than the general number of two layers, but with that, the process is complicated, and the above-mentioned problems become more prominent for the coil patterns of the third layer and above, and it is more difficult to make and the cost increases. It cannot be a good solution because it does.

Next, as another problem, a problem in forming the pattern of the upper magnetic layer will be described with reference to FIG. Figure 5 (a)
3B is a shape diagram of the upper magnetic layer 10, and FIG. 4B is a cross-sectional view of the upper magnetic layer 10 in a pattern forming step. A lower magnetic layer 3, a lower insulating layer 4, a gap layer 5, a lower coil layer 6, a middle insulating layer 7, an upper coil layer 8 and an upper insulating layer 9 are sequentially laminated on a ceramic substrate 1 having an insulating layer 2 formed on the entire surface. After doing
When the upper magnetic layer 10 is formed by electroplating, the metal film 18 for the electroplating electrode is deposited and formed on the entire surface of the ceramic substrate 1 by the sputtering method or the vapor deposition method.

Next, a photoresist for forming the upper magnetic layer 10
19 is applied, dried, irradiated with ultraviolet rays through the photomask 20, and then developed to form an upper magnetic layer pattern. At this time, the upper magnetic layer 10 has a step H of about 4 μm of the upper coil layer 8 and about 2 μm of the upper insulating layer 9 than the step T (about 14 μm) at the time of forming the upper coil layer described above. It must be created with a level difference of about 20 μm. The important dimension of the coil layer is formed on the step, while the important dimension of the upper magnetic layer 10 is formed on the rising portion of the step.

In the photoresist 19 for forming the upper magnetic layer shown in FIG. 5B, the thickest part is the back gap portion 14 where the upper and lower magnetic layers contact each other due to the step H, and the second thickest part is the track. In the part where the film is formed, the film thicknesses h ₂ and h ₁ are considerably thicker than the film thicknesses applied to the flat parts.

The track width (TW), which is an important dimension in the thin film magnetic head, is the film thickness h _{1 at} the rising portion of the step.
However, it is difficult to precisely control the pattern width because the film thickness changes abruptly at this position. Considering the film thickness distribution in the ceramic substrate, the variation is about ± 1 μm. May occur.

Such variations are caused by the track width (T.
As W.) becomes smaller, the variation in characteristics of the thin film magnetic head becomes larger and the purpose of a high performance drive device is not met.

Further, since the photoresist in the back gap portion 14 is thickest, the photoresist 19 cannot be completely removed under the same pattern forming conditions as the track portion, which requires highly accurate dimensions. Therefore, it is necessary to perform multiple exposure for exposing and developing only the area of the back gap portion 14 again. This multiple exposure not only complicates the pattern forming process, but also causes a decrease in the operating efficiency of the exposure device for pattern formation, which is one of the most expensive devices in the thin film process. Such a problem is more remarkable as the coil film thickness is increased in order to suppress the increase in DC resistance due to the increase in the number of coil turns, and when the number of coil layers is three or more, the step H
Is higher, which is a bigger problem.

[0028]

According to the above-mentioned conventional manufacturing method, there is a problem that the pattern accuracy of the upper layer is lowered due to the influence of the step formed in the lower layer. That is, due to the influence of the step formed in the lower layer during the formation of the upper coil layer, the film thickness distribution of the photoresist for forming the upper coil layer is generated, which causes the variation of the pattern width and limits the accuracy of the coil pattern creation. And there was a problem with poor yield.

Similarly, due to the influence of the step formed in the lower layer during the formation of the upper magnetic layer, the variation of the film thickness of the photoresist for forming the upper magnetic layer is caused, and the variation of the track width which causes the deterioration of the yield. And also reduces the operating efficiency of the exposure apparatus. If the number of coil layers is three or more for the purpose of improving the performance of the thin-film magnetic head, the above problem will be further increased. It is an object of the present invention to provide a method of manufacturing a thin film magnetic head that solves the above problems.

[0030]

According to the present invention, a concave portion is provided at a position corresponding to a coil forming region of an insulating layer made of alumina or the like formed on a substrate, and a lower magnetic layer except for a track forming portion and a back gap portion is formed. It is characterized in that a part thereof, a lower insulating layer, a lower coil layer and the like are formed so as to be buried in the recess.

[0031]

According to the present invention, the upper coil layer and the upper magnetic layer are formed by providing a recess in the coil forming region and burying a part of the lower magnetic layer, the lower insulating layer, the lower coil layer and the like in the recess. At this time, it is possible to eliminate or reduce the step generated before forming each of these layers, and as a result, it is possible to suppress the film thickness distribution and fluctuation of the photoresist for forming the upper coil layer and the upper magnetic layer. As a result, a highly accurate pattern is formed.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a thin film magnetic head formed according to an embodiment of the present invention. First, an insulating layer 2 made of alumina or the like is deposited on a ceramic substrate 1 by a sputtering method. At this time, the film thickness is made thicker than the desired etching amount L ₁ in the next etching process. Next, a part of the formation region of the lower magnetic layer 3 excluding the back gap portion Y (the pattern is shown in FIG. 5 (a) 14) where the track forming portion X and the upper and lower magnetic layers contact each other, and the upper and lower coil layers And 6
The insulating layer 2 corresponding to the formation region is removed by etching to a certain depth L ₁ .

For this etching, chemical etching or ion beam etching is used, and the thin film magnetic head having the conventional structure is etched and removed by the step difference to be reduced. For example, when it is desired to reduce the step difference of the lower magnetic layer 3,
The thickness corresponding to the film thickness 5 μm of the lower magnetic layer 3 is removed.
Similarly, the lower magnetic layer 3, the lower insulating layer 4, and the lower coil layer 6 are formed.
If you want to mitigate the level difference, the total film thickness is 12
Remove about μm. As described above, according to the present invention, only by adjusting the film thickness of the insulating layer 2 to be removed by etching, it is possible to reduce a desired step difference without any additional step.

Next, the lower magnetic layer 3 is formed in such a manner that the portion other than the track forming region and the back gap portion is buried in the concave portion of the insulating layer 2. At this time, as the lower magnetic layer 3, a magnetic film such as permalloy is formed by electroplating or sputtering.

Next, after the gap layer 5 is formed by the sputtering method, the lower insulating layer 4 is made of a novolac resin or a polyimide resin in the same manner as a part of the lower magnetic layer 3 as the insulating layer 2.
It is formed so as to be embedded in the concave portion of. Further thereon, the lower coil layer 6 is formed by electroplating with copper or the like so as to be embedded in the concave portion of the insulating layer 2 like the lower two layers.

Next, the middle insulating layer 7 is formed by using the same material as the lower insulating layer 4 in order to ease the unevenness of the lower coil layer 6 and facilitate the formation of the upper coil layer 8 later. In order to make the pattern of the upper coil layer 8 more precise, it is desirable that the surface formed by the middle insulating layer 7 be substantially flush with the flat surface on the substrate. This is because if the formation surface of the upper coil layer 8 is flat, the film thickness of the photoresist for forming the upper coil layer will be substantially uniform, and as a result, the accuracy of pattern formation will be improved. After forming the upper coil layer 8 on the middle insulating layer 7 by electroplating of copper or the like like the lower coil layer 6, the upper insulating layer 9 is formed on the lower and middle insulating layers 4, 4.
It is formed of the same material as 7.

Next, the upper magnetic layer 10 is formed by a method similar to that of the lower magnetic layer 4, but the thickness of the lower layer is H as a whole as in the conventional case, but the concave portion provided in the insulating layer 2 is L ₁ As a result, the remaining step is only L ₂ . Since the photoresist for forming the upper magnetic layer 10 has only the film thickness variation caused by the step difference of L ₂ , the film thickness variation is significantly improved as compared with the conventional case.

As a result, the track width accuracy of the upper magnetic layer 10 is greatly improved. Further, since the back gap portion Y is to be raised as a result when the insulating layer 2 is etched, the photoresist in the back gap portion Y does not become abnormally thick, and the operating efficiency of the exposure apparatus is increased. It is no longer necessary to perform multiple exposure that lowers

Next, an insulating material such as alumina is attached by a sputtering method to form a protective layer 11 so as to protect the entire element,
The fabrication of the thin film magnetic head is completed.

As described above, the present invention is basically based on the fact that the lower magnetic layer 3, the lower insulating layer 4, and the lower coil layer 6 are buried in the recess formed in the insulating layer 2. This is because the cross-sectional structure of the head becomes vertically symmetrical, which is convenient for improving the characteristics of the thin film magnetic head. For the purpose of merely relaxing the step, the present invention is not limited to this. It can be widely applied from the step relief of only the magnetic layer 3 to the step relief to the upper insulating layer 9.

Further, according to the present invention, in order to prevent an increase in coil resistance due to an increase in the number of turns, the coil film thickness is increased,
When the number of coil layers is greater than two, the effect becomes even greater.

[0043]

As described above, according to the method of manufacturing a thin film magnetic head of the present invention, the insulating layer formed on the substrate is provided with a recess, and a recess is formed so as to be partially embedded in the lower magnetic layer or the lower insulating layer. By forming the upper coil layer and the lower coil layer, the step difference when forming the upper coil layer and the upper magnetic layer can be eliminated or made small, so that the film thickness distribution and fluctuation of the photoresist for forming the upper coil layer and the upper magnetic layer can be reduced. Becomes smaller. As a result, the upper coil layer and the upper magnetic layer can be dimensioned with high accuracy, and the performance of the thin film magnetic head can be improved.

Further, according to the present invention, it is possible to suppress unnecessary proximity of the upper and lower magnetic layers other than the track portion and the back gap portion, so that the efficiency of the thin film magnetic head can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thin film magnetic head formed according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating a configuration of a conventional thin film magnetic head.

FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 4 is a cross-sectional view illustrating a problem with a conventional method of manufacturing a thin film magnetic head.

FIG. 5 is a cross-sectional view illustrating another problem related to the conventional method of manufacturing a thin film magnetic head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Insulating layer, 3 ... Lower magnetic layer, 4 ... Lower insulating layer, 5 ... Gap layer, 6 ... Lower coil layer,
7 ... Middle insulating layer, 8 ... Upper coil layer, 9 ... Upper insulating layer, 10 ... Upper magnetic layer, 11 ... Protective layer, X ... Track forming part, Y ... Back gap part, H ... Step,
L ₁ , L ₂ ... Depth.

Claims (1)

1. A recess is provided in a coil layer forming region of an insulating layer formed on a substrate, and then a part of the lower magnetic layer and the lower insulating layer and the lower coil layer are buried in the recess. 7. A method of manufacturing a thin film magnetic head, which is characterized in that a middle insulating layer, an upper coil layer, an upper insulating layer, an upper magnetic layer, and the like are sequentially laminated on each other.