JPH04321911A - Production of thin-film magnetic head - Google Patents

Abstract

PURPOSE:To obtain high-accuracy coil patterns by flattening a coil layer forming surface including the gap layer on a lower magnetic layer and forming a coil layer via a contrast enforcing layer on a photoresist on a flat surface. CONSTITUTION:After the lower magnetic layer 4 is formed on a substrate, the gap layer 5 is formed and further a protective layer 10 consisting of a material having selectivity in chemical etching with the layer 4 and the layer 5 is formed in the region which does not exist right under the coil layer 9. An insulating layer 7 is then stuck to the entire part of the substrate and thereafter, a substrate electrode film 6 and a photoresist layer 13 are formed. The contrast enforcing layer(CEL) 16 is then formed on the layer 13. The layer 16 and the layer 13 are simultaneously exposed by UV rays via a photomask 14. The UV rays blurred by the effect of the layer 16 are cut by the layer 16 and exposed regions 15 having the size faithful with the size of the mask 14 are formed in the layer 13. The film 6 is exposed to the shape to form coils and coil layers 9 are selectively stuck by electroplating to these parts. The layer 13 is removed.

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 thin film magnetic head with simple steps.

0002

2. Description of the Related Art In recent years, as the performance of magnetic disk drives has improved, the thin film magnetic heads used therein have also been required to have various improvements in performance. For example, narrower tracks are being considered to improve the areal recording density of magnetic disk drives. At this time, it is necessary to increase the number of turns of the coil, but this increases magnetic resistance, causing deterioration of head efficiency and deterioration of head characteristics due to an abnormal increase in inductance. Therefore, increasing the number of coil turns without increasing the magnetic path length of the thin film magnetic head has become a major challenge.

A conventional method for manufacturing a thin film magnetic head will be described below. FIG. 3 is a perspective view of a conventional thin-film magnetic head, FIG. 4(a) is an enlarged side view of a transducer element, and FIG. 4(b) is a cross-section of a main part taken along line A-A' in FIG. 4(a). It is a diagram.

11 is an upper insulating layer, 12 is an upper magnetic layer, 1
3 is a back gap portion where the upper magnetic layer and the lower magnetic layer are joined, 17 is a terminal layer, 18 is a slider, and 19 is a floating rail.

A method of manufacturing the conventional thin film magnetic head constructed as described above will be described below.

FIG. 5 is a process diagram showing the manufacturing process of a conventional thin film magnetic head, and FIG. 6 is a process diagram showing the manufacturing process of a conventional thin film magnetic head.
7(a) is a state diagram during exposure with a conventional pattern, and FIG. 7(b) is a cross-sectional view of a main part of a thin film magnetic head formed with a conventional CEL (hereinafter abbreviated as CEL). FIG. 4 is a state diagram during pattern exposure. In FIG. 5, (a
) After forming the lower magnetic layer 4 with a magnetic film such as permalloy in the process, a magnetic gap layer 5 is formed thereon, the lower magnetic layer 4 and the coil layer 9 are insulated, and the lower magnetic layer 4 generates a An insulating layer 8 made of photoresist or polyimide resin is formed to reduce the step difference and make it easier to form the coil layer 9. Although the insulating layer 8 has viscosity, the lower magnetic layer 4 is quite thick (usually 4 to 5 μm), so the step cannot be completely eliminated.

Next, in step (b), a base electrode film 6 for forming a coil layer is deposited with a thickness of 0.1 to 0.2 μm by sputtering or the like by electroplating, and a coil pattern is formed thereon. Apply photoresist and dry. In the step (c), the photoresist layer 13 is irradiated with ultraviolet rays through the photomask 14, and the photoresist layer 13 is
A photosensitive area 15 is formed in the area.

Next, in step (d), the photoresist layer 1 is
The photosensitive area 15 of No. 3 is dissolved and removed by development to expose the base electrode film 6 in a patterned shape, and the coil layer 9 is formed on that portion by electroplating.

Next, in step (e), the photoresist layer 1 is
After removing the coil layer 3, the unnecessary base electrode film 6 that short-circuits the coil layer 9 is removed by ion beam etching, and the formation of the coil layer 9 is completed. When a coil layer is formed using the above-described conventional technique, the coil layer 9 must be formed on the undulating insulating layer 8, so the thickness of the photoresist layer 13 for creating the coil pattern must be adjusted. Figure 5 (
As shown in b), if T1 is T1 in the flat part of the insulating layer 8, and T2 is T2 near the sloped part, then T1 > T2, and the film thickness is non-uniform and the optimum exposure conditions within the pattern are different, and the substrate for optimum exposure is The upper focus position also differs. As a result, wide and narrow parts are created in the pattern width, causing fluctuations in the pattern width, and as shown in the process in FIG.
<S2), and the coil spacing cannot be made smaller than the dimensional difference between S1 and S2.

As shown in FIG. 7(a), when forming a pattern, the ultraviolet rays that reach the photoresist layer 13 through the photomask 14 form a width a1 wider than the initial width A due to the light diffraction phenomenon. This is due to the fact that At this time, the intensity of the ultraviolet rays exhibits a distribution in which the intensity is strongest in a certain range at the center of the pattern and becomes weaker toward the periphery. Therefore, the intensity of the ultraviolet light at the outer periphery of the pattern decreases as it goes below the photoresist layer 13.

The resulting exposed photoresist layer 13
The upper dimension a1 and the lower dimension a2 are different. In FIG. 5(e), this state is further promoted. If you simply increase the number of coil turns without increasing the length of the magnetic layer (magnetic path length), you can increase the number of coil layers, but this would complicate the manufacturing process and make it difficult to form, increasing manufacturing costs. Not suitable for mass production.

Furthermore, if the number of coil turns is increased while the coil dimensions remain the same as before, it is necessary to increase the magnetic path length of the thin film magnetic head, which leads to a decrease in head efficiency due to an increase in magnetic resistance and an abnormal increase in inductance. This results in a loss of functionality as a thin film magnetic head.

Next, a conventional thin film magnetic head formed with CEL will be explained. As shown in FIG. 6, the lower magnetic layer 4
A base electrode film 6 is formed on the step formed by the insulating layer 8 and the insulating layer 8.
Since the photoresist for forming the coil pattern is applied through the photoresist layer 13, the photoresist layer 13 is undulated, and the CEL 16 applied thereon is also affected by the undulations of the photoresist layer 13, resulting in uneven film thickness.

As a result, the thickness t2 of the CEL 16 near the sloped portion of the insulating layer 8 is thinner than the thickness t1 of the flat portion of the insulating layer 8.

[0015] If the CEL 16 is applied unevenly, not only will the function of the CEL not be fully utilized, but it will also increase the cause of instability in pattern formation. Here, the function of the CEL is as shown in FIG. 7(b), when the ultraviolet rays having a width A that have passed through the photomask 14 are projected onto the CEL coated on the photoresist layer 13, similar to that in FIG. 7(a). The width a1 has a certain spread due to the diffraction phenomenon of light, but C
Since the EL 16 has lower sensitivity than the photoresist layer 13, the ultraviolet rays cannot reach the photoresist layer 13 through the CEL 16 unless the energy of the ultraviolet rays exceeds a certain level.

As a result, the weak-intensity ultraviolet rays are cut by the CEL 16, and the width b2 of the ultraviolet rays that finally reaches the photoresist layer 13 has the effect of forming approximately the same dimension as the width A of the photomask.

[0017]

[Problems to be Solved by the Invention] However, with the above-mentioned conventional configuration, when forming a coil pattern, the coil pattern cannot be formed with ideal precision due to the steps created by the lower magnetic layer and the insulating layer. CEL is also unable to fully demonstrate its function due to the difference in level. Therefore, there has been a problem in that it is difficult to increase the number of coil turns without impairing the performance of the thin-film magnetic head, making it impossible to manufacture a high-performance thin-film magnetic head.

The present invention solves the above-mentioned conventional problems, and is a simple method for forming a pattern on a smooth surface without uneven coating of photoresist or CEL, and has a narrow coil pitch and a thick coil film thickness. An object of the present invention is to provide a method for manufacturing a high-performance thin-film magnetic head that is suitable for mass production at low cost and can significantly increase the number of coil turns by forming a coil layer.

[0019]

[Means for Solving the Problems] In order to achieve this object, the method for manufacturing a thin film magnetic head of the present invention includes a portion forming a magnetic gap on a gap layer formed on a lower magnetic layer and a coil layer. After patterning a protective layer made of a material that is selective to the lower magnetic layer and the gap layer in chemical etching to a thickness equal to or thicker than that of the lower magnetic layer in an area that is not located directly below, an insulating material is formed. It is deposited on the entire substrate to a thickness equal to or thicker than that of the lower magnetic layer, and then the entire substrate is mechanically polished to flatten the surface on which the coil layer is formed, and then the base electrode film, photoresist layer, CEL
It has a structure in which a coil pattern is formed by stacking layers in this order, exposing and developing them.

[0020]

[Operation] With this structure, the thickness of the photoresist layer for forming the coil pattern can be made uniform, and the thickness of the CEL coated thereon can also be made uniform. As a result, the performance of CEL can be utilized to its fullest, making it possible to transfer an image faithful to the photomask dimensions onto the photoresist, making it possible to obtain a highly accurate coil pattern with no variation in pattern dimensions. , it is also possible to increase the number of turns of the coil without impairing the performance of the thin-film magnetic head.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing a method for manufacturing a thin film magnetic head according to an embodiment of the present invention, and FIG. 2 is a process diagram thereof.

In FIG. 2, in step (a), a magnetic film such as permalloy is formed on the substrate as the lower magnetic layer 4 by electroplating or sputtering, and then a gap layer 5 is formed from an insulating material such as alumina. In a region including the magnetic gap portion and not located directly under the coil layer 9,
A protective layer 10 made of a material that is selective to the lower magnetic layer 4 and the gap layer 5 in chemical etching is formed into a pattern shape to be thicker than the film thickness P of the lower magnetic layer (FIG. 1 (1)).
). The material of the protective layer 10 is copper, gold, titanium, etc., which can be removed by chemical etching, and the etching solution is used for the lower magnetic layer 4.
Alternatively, a material that does not etch the gap layer 5 or an organic material such as a photoresist may be used.

Next, an insulating layer 7 made of alumina or the like is deposited on the entire substrate by sputtering to a thickness greater than the film thickness P of the widest region of the lower magnetic layer 4 (FIG. 1 (2)), and then the entire substrate is flattened by mechanical polishing. process to form a coil layer forming surface (Figure 1
(3) ). Next, in step (b), a base electrode film 6 is formed with a thickness of 0.1 to 0.2 μm by sputtering or vapor deposition. When copper is used for the coil layer, copper, which is the same material, is usually used for the base electrode film 6, but in order to strengthen the adhesion to the substrate, a layer of titanium, chromium, etc. is placed between the copper and the substrate to a thickness of several hundred Å. A film may be formed to form a two-layer film.

Next, a photoresist layer 13 for forming a coil pattern is applied onto the base electrode film 6 using a spin coater or the like to a thickness greater than the intended thickness of the coil film, and is dried using a hot plate or dryer (FIG. 1). (4)
). For example, if the coil thickness is desired to be 6 μm, the photoresist layer 13 may be formed to have a thickness of 7 μm to 8 μm. As the photoresist layer 13, it is desirable to use a positive type photoresist that has relatively good pattern accuracy even when the film thickness is increased. Next, in step (c), the photoresist layer 13
CEL16 is applied onto the surface using a spin coater and then dried (Fig. 1 (5)). At this time, if CEL and photoresist have affinity, a barrier-like intermediate layer may be formed between the photoresist and CEL.

Next, ultraviolet rays are irradiated through the photomask 14 to simultaneously expose the CEL 16 and the photoresist layer 13. At this time, due to the effect of the CEL shown in FIG. 7(b), the ultraviolet rays that pass through the photomask and blur due to the diffraction phenomenon, and the ultraviolet rays that become blurred due to a shift in focus when projected onto the substrate, are cut by the CEL 16. An exposed region 15 having dimensions faithful to the dimensions of the photomask is formed in the photoresist 13. Next, in step (d), CEL1
6 is removed using pure water or a solvent, the exposed area 15 of the photoresist layer 13 is dissolved and removed using an alkaline developer to expose the base electrode film 6 in a shape that forms a coil, and the exposed area 15 of the photoresist layer 13 is removed by electroplating. A coil layer 9 is selectively deposited (FIG. 1(6)). Copper is preferred as the coil material from the viewpoint of having the lowest specific resistance, and is produced using a copper sulfate-based plating solution.

Next, in step (e), the photoresist layer 13 is
After removing the unnecessary base electrode film 6 that short-circuits the coil layer 9, the coil layer 9 is created by removing the unnecessary base electrode film 6 that short-circuits the coil layer 9 by dry etching such as ion beam milling.

As described above, according to the present invention, the coil width W was 4 μm, the coil spacing S was 2 μm, and the coil thickness H
The technical limit was about 4 μm, but each W was 2 μm.
~3 μm, S is 1 to 2.5 μm, and H is 6 to 10 μm, making it possible to create a coil with flexibility. As a result, the coil pitch can be made narrower than before and the coil thickness can be formed thicker, so the number of turns of the coil can be increased without abnormally increasing the magnetic path length or increasing the inductance and DC resistance.

[0029]

As described above, the method for manufacturing a thin-film magnetic head of the present invention flattens the coil layer formation surface including the gap layer on the lower magnetic layer, and the contrast enhancement layer coated on the photoresist on the flat surface. Since the coil layer is formed through the coating, a pattern can be formed on an ideally smooth surface with no uneven application of photoresist or contrast enhancement layer, so the performance of the contrast enhancement layer can be maximized. It is possible to form a coil layer with a narrow coil pitch and a thick coil thickness, which was previously impossible. As a result, it has become possible to increase the number of coil turns without abnormally increasing the magnetic path length or significantly increasing inductance or DC resistance. In addition, when there is no need to increase the number of coil turns, the coil layer has conventionally had a two-layer structure, but in the present invention, the coil pitch of the thin-film magnetic head is narrowed and the coil film thickness is thickened. This is an excellent thin-film magnetic head that allows the coil layer to be made into a single layer without major dimensional changes, making it possible to manufacture a high-performance thin-film magnetic head suitable for mass production with a simple process and at low cost. This manufacturing method can be realized.

[Brief explanation of drawings]

FIG. 1 is a flow diagram of a method for manufacturing a thin film magnetic head in an embodiment of the present invention.

FIG. 2 is a process diagram of a method for manufacturing a thin film magnetic head in an embodiment of the present invention.

[Figure 3] Perspective view of a conventional thin film magnetic head

[Figure 4] (a)
is an enlarged side view (b) of the transducer element section, and FIG.
A-A′ cross-sectional view of a)

[Figure 5] Manufacturing process diagram of a conventional thin film magnetic head

[Fig. 6] Cross-sectional view of main parts of a thin-film magnetic head with a conventional contrast enhancement layer formed thereon.

[Figure 7] (a) is a state diagram during exposure with a conventional pattern (
b) is a state diagram during exposure using a pattern with conventional CEL.

[Explanation of symbols]

1 Board 2 Insulating layer 4 Lower magnetic layer 5 Gap layer 6 Base electrode film 7 Insulating layer 8 Insulating layer 9 Coil layer 10 Protective layer 13 Photoresist layer 14 Photomask 15 Photoresist photosensitive area 16 Contrast enhancement layer 17 Terminal layer 18 Slider 19 Floating rail

Claims (2)

[Claims] 1. A method for manufacturing a thin film magnetic head in which a lower magnetic layer, a gap layer, a conductive layer, an insulating layer, and an upper magnetic layer are sequentially laminated on a substrate, including the magnetic gap portion and immediately below the conductive layer. A process of forming a protective layer selective to the lower magnetic layer and the gap layer by chemical etching in areas not located on the substrate, a process of forming an insulating layer over the entire substrate, and a process of flattening the entire substrate to form a coil layer forming surface. A method of manufacturing a thin film magnetic head, comprising the steps of: 2. The method according to claim 1, further comprising the step of sequentially laminating a base electrode film, a photoresist layer, and a contrast enhancement layer on the flattened coil layer formation surface, followed by exposure and development. A method for manufacturing a thin film magnetic head.