JPH0242613A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To control the increase of a coil resistance value with an increase of number of turns by forming an aluminum oxide layer in such a manner as to protect a CU plating layer even if the front surface of a core is ion etched over a long period of time at the time of ion etching of a plating substrate removing stage. CONSTITUTION:The ion etching rate of aluminum oxide in a gaseous Ar atmosphere is extremely low and if the aluminum oxide layer 5 is laminated on the Cu plating layer 3, the layer protects the Cu plating layer 3 so that the etching of the Cu plating layer 3 is completely prevented at the time of ion etching in the plating substrate removing stage. Namely, the ion etching rate of the aluminum oxide is 50Angstrom /min when the plating substrate removing stage requires 25 minutes and, therefore, the ion etching of the Cu plating layer 3 is completely prevented by forming the magnetic head into the structure in which the aluminum oxide layer 5 having at least about 1,250Angstrom thickness is laminated on the Cu plating layer 3. The increase of the coil resistance value with the increase of the number of turns is controlled in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inductive thin film magnetic head used in magnetic disk devices, magnetic tape devices, etc., and particularly relates to a coil fabricated using integrated thin film technology. It's about structure.

[Conventional technology]

In recent years, in the field of magnetic recording, recording densities have been increasing rapidly, and in magnetic heads that support magnetic recording as well as recording media, thin-film magnetic heads manufactured using integrated thin-film technology have been put into practical use, replacing conventional ferrite heads. It has been. This thin-film magnetic head has excellent frequency characteristics and is manufactured using a manufacturing process based on semiconductor chip technology, making it possible to manufacture high-precision, high-density magnetic heads at low cost. It is becoming the mainstream of heads.

FIG. 5 is a schematic cross-sectional view showing the structure of such a thin film magnetic head. In FIG. 5, an insulating layer 12 of Al2O3 or the like is formed on a ceramic substrate 10 of A1203TiC or the like by sputtering or the like. Next, NiF
e alloys and Co-metallic amorphous materials (e.g. Co Z r
A lower magnetic layer 13 made of a soft magnetic material such as Nl))
is formed using integrated thin film technology. Thereafter, an insulator 14 having a thickness equal to a predetermined gap length is formed. Next, an organic layer 15 is formed to eliminate the step difference in the lower magnetic layer 13, and the coil 1 made of a conductive material is formed.
6 is formed. Thereafter, the organic layer 17, which becomes a layer for eliminating the one-step difference in the coil 16, is formed again. Next, an upper magnetic layer 18 made of a soft magnetic material such as a NiFe alloy or a Co-metallic amorphous material (e.g. CoZrNb) is applied to the lower magnetic layer 1.
A protective layer (not shown) made of an insulating material is formed to complete the transducer of the thin film magnetic head.

The coil 16 of the thin-film magnetic head described above is usually made of a Cu film formed by electroplating, and its rough cross-sectional structure is shown in the second figure.
It is as shown in the figure. In other words, the coil 16 is C
r A plating base layer consisting of a laminate of Ml and Cu layer 2, and C
It has a laminated structure of U-plated N3. FIG. 4 shows such a conventional coil manufacturing process. In FIG. 4(a), a Cr layer 1 and a Cr layer are deposited on the base body 11 by sputtering.
A laminate of the u layer 2 is formed to form a plating base layer. Then, as shown in FIG. 4(b), a photoresist pattern (hereinafter abbreviated as PR pattern) 4 having a predetermined shape is formed using a known exposure and development technique. Then the fourth
As shown in Figure (c), Cu is precipitated in a plating medium containing copper sulfate as a main component to form a Cu plating layer 3. Next, the PR pattern 4 is peeled off (Fig. 4(d)),
As shown in FIG. 4(e), it was covered with a PR pattern 4 by ion etching in an Ar gas atmosphere. A portion of the metal underlayer is removed to form a coil. As is clear from FIG. 4(e), the Cu plating layer 3 is also ion-etched in this plating base layer removal process, so the thickness of the Cu plating layer 3 is reduced by the time taken to remove the plating base layer. .

Incidentally, reflecting the trend toward higher recording densities in recent years, the leakage magnetic field from information recorded on a medium is becoming smaller and smaller, and there is a concern that the reproduction output of the head will decrease. Since the reproduction output of an inductive thin-film magnetic head is approximately proportional to the number of turns of the coil, one effective way to compensate for this decrease in reproduction output is to narrow the coil spacing as much as possible to form a dense coil and increase the number of coil turns. It is considered a useful method.

[Problem to be solved by the invention]

However, with the conventional structure and manufacturing method described above, there are problems as described below when increasing the number of coil turns. That is, in dense coils, the coil spacing is naturally narrower than the conventional coil spacing (about 4 μm), and is usually about 2 μm or less. on the other hand,
The coil thickness (the sum of the plating base layer, Cu, and three plating layers) is currently around 3 μm, but in order to reduce the effect of increased coil resistance due to an increase in the number of coil turns, it has been made thicker (for example, 4 μm or more). In such a dense coil with narrow coil spacing and thick coil thickness,
When removing a part of the plating base layer covered with the PR pattern 4 by ion etching in the step of FIG. 4(e), the plating base layer is The time required for the layer removal process increases significantly. This is because the coil spacing is narrow and the coil thickness is large, so the plating base layer that should be removed is the top surface of the coil (second layer).
This means that the Ar particles reach the plating base layer less frequently, and the plating base that has been knocked out by the Ar particles re-attaches to the side surface of the coil. This phenomenon is thought to be caused by the fact that the effective etching rate in the area sandwiched between the coils decreases due to the fact that the etching does not easily separate from the gap between the coils. .

The process of removing the plating layer of such a dense coil takes a lot of time to complete, and as a result, two sides of the coil are ion-etched for a long time.
Coil thickness is significantly reduced.

Therefore, the effect of increasing the coil thickness and controlling the increase in the coil resistance value due to the increase in the number of turns cannot be sufficiently obtained, which has been a problem. This problem becomes more pronounced as the coil thickness becomes thicker or as the coil spacing becomes narrower, and has become a major problem in the head manufacturing process.

An object of the present invention is to solve the problems in the coil forming process of a thin film magnetic head that have been described previously.

[Means to solve the problem]

According to the present invention, a magnetic circuit made of a soft magnetic material, a magnetic gap made of a non-magnetic material formed in the magnetic circuit, and a conductive thin film formed to intersect the magnetic circuit. In the induction type thin film magnetic head comprising a coil, the coil is comprised of a laminate in which a plating underlayer, a Cu plating layer, and an aluminum oxide layer are formed in this order.

r Effect] By employing the above-described structure, the present invention has made it possible to provide a thin film magnetic head that solves the conventional problems. That is,
According to studies by the present inventors, by laminating aluminum oxide layers, the Cu plating layer is protected during ion etching in the plating base layer removal process, and the Cu plating layer is completely prevented from being etched. It has become clear that this can be prevented. For example, in the plating base layer removal process,
If the ion etching rate of aluminum oxide is 50 A/min (Ar gas pressure 1 x 10
-'T, , r, accelerating voltage 500V), the C11 plating layer can be ion-etched by forming a structure in which an aluminum oxide layer with a thickness of at least about 125 OA is laminated on the Cu plating layer. This can be completely prevented. On the other hand, in a conventional coil, the ion etching rate for Cu is about 500 A/min (the ion etching conditions are the same as for aluminum oxide), and the Cu plating layer is directly exposed to Ar particles, so it is about 1.25 A/min.
The Cu plating layer is ion-etched, and the coil resistance value increases by this amount. Incidentally, if the plating layer removal step requires a longer time, the thickness of the aluminum oxide layer may be increased as appropriate.

〔Example〕

Next, the present invention will be explained in detail using the drawings. As already mentioned, the present invention is characterized by the coil structure of the inductive thin film magnetic head.The general structure of the thin film magnetic head according to the present invention is largely different from the structure of the conventional thin film magnetic head shown in FIG. Therefore, in the following embodiments, components other than the coil portion will be explained using FIG. 5.

1) In Example 5, A1□03-TiC ceramic substrate 1
0 on top of the insulating layer 12 made of Al2O and film by sputtering method (throwing type crab 600W, A1-gas pressure crab 5X10
ZuT. rr) to form a film with a thickness of 10 μm. Then, a CO87Zr5Nb8 film with a film thickness of 3 μm cr) was formed using a sputtering method, and a lower magnetic layer 13 was formed using a known photolithography technique. In addition, Cog7Zr5Nb
The film formation conditions for the 6 films were injection type crab 600W, Ar gas pressure crab 5 x 10-3 Torr, and 4800e after film formation.
The magnetic properties were improved by annealing for 1 hour at 250° C. in a rotating magnetic field.

After that, the film thickness (0,z) equal to the predetermined gap length is 1 m.
) Sputtered Al2O3 film was deposited (Immersion type crab 300W, Ar gas pressure crab 5X10-3 Torr) l,
It was set as the insulating layer 14. Next, a photoresist made of novolac resin is applied on the lower magnetic layer 13 to a thickness of 4/4.
1 m of the coating was coated and cured by heat treatment at 250° C. for 1 hour to form an organic layer 15 serving as a step eliminating layer for the lower magnetic layer 1-3, and then a coil 6 was formed.

Hereinafter, the manufacturing method and structure of the coil 16 will be explained in detail using FIG. 3 and FIG. 1. In Figure 3, the base body 1
1 (corresponding to the organic layer 15 in this example) -H was sputtered to form a Cr layer 1 (thickness 30A) and C11.
A plating base layer consisting of a laminated film having a thickness of 2000 Å was formed (FIG. 3(a)). Next, using a known photolithography technique, a PR plated frame is formed.
Pattern 4 was formed (FIG. 3(b)). The photoresist used was a commercially available novolac resin-based resist I. Moreover, the film thickness of PR pattern 4 is 6 μm, and the pattern width is 1
．． 5 μm, and the pattern interval was 3 μm. Note that since the pattern width of the PR pattern 4 is 1.5 μm, the coil interval is 1.5 μm. Thereafter, electroplating was performed in copper sulfate to form a CU plating layer 3 (FIG. 3(C)). Here, the plating current density was IA/cm2, and the thickness of the Cu plating layer 3 was 5 μm. Next, an aluminum oxide layer 5 having a thickness of 200 OA was formed on the Cu plating layer 3 by a vapor deposition method using an electron beam (FIG. 3(d)). The emission current of the electron gun at this time was 60 mA. Next, PR pattern 4 was peeled off in an organic solvent (Figure 3 (
e)). Finally, the unnecessary plating base layer is removed by ion etching in an Ar atmosphere (Fig. 3(f)).
was formed. The conditions for ion etching are an Ar gas pressure of 1 x 10-' Torr and an acceleration voltage of 500V. Also, the time required for this plating base layer removal process was about 25 minutes, and during this time, the aluminum oxide layer 5 was etched by 1250A out of a film thickness of 200OA because the ion etching rate was 50A/min. The Cu plating layer 3 was not ion-etched at all. The schematic structure of the coil formed in this way is shown in FIG.
It has a structure in which the plating layer 3 and the aluminum oxide layer 5 are stacked in this order.

After forming the coil 16 in the manner described above, a photoresist layer 17 serving as a step eliminating layer of the coil 16 was formed in the same manner as the photoresist layer 15 described above. Next, film thickness 3
The upper magnetic layer 18 made of a 1 tm Cog7Zr5Nl)8 film is made in the same manner as the lower magnetic layer 13. Finally, a protective film (not shown; film thickness: 25 /Z m ) consisting of an A I 20 g film was formed by sputtering. The film forming conditions were: injection type crab 800W, Ar gas pressure crab 5X
10-'Torr.

In the thin film magnetic head of this example manufactured as described above, the coil spacing was narrow to 15 μn1 because the aluminum oxide film protects the Cu plating layer during the removal process by ion etching of the plating underlayer as described above. ,
Although the coil thickness was as thick as approximately 5 μm, the Cu plating layer was not etched at all. Therefore, the conventional problems of decreasing the coil thickness and increasing the coil resistance value do not occur. Note that the PR pattern forming step (see FIG. 3(b) In the step>, it is desirable that the cross-sectional shape of the PR pattern 4 is a stencil shape.

2) Comparative Example In the same manner as in the example, an insulating film 12, a lower magnetic layer 13, an insulating layer 14 serving as a gap, and an organic layer 15 are formed on an A1□03-Tic ceramic substrate 1.0, and then a coil 16 is formed. was formed. The coil 16 was formed using the conventional coil forming method shown in FIG. That is, the fourth
In the figure, the base body 11 (in this example, the organic material layer in Figure 5) 5
Cr layer 1 (corresponding to
It consists of a laminated model of a Cu layer 2 (film thickness 200 OA) and a Cu layer 2 (film thickness 200 OA). Figure 4 (a)) to form a plating base layer.

Next, using a known photolithography technique, a PR pattern 4 that will become a plating frame is formed (see FIG. 4).
b)). The photoresist used was a commercially available novolak resin resist. Further, the PR pattern 4 had a film thickness of 6 μm, a pattern width of 1.5 μm, and a pattern interval of 3) i m, as in the example. In addition, since the pattern width of PR pattern 4 is 1.5 μm, the coil spacing is 1.5tt'
It is m. Thereafter, the Cu plating layer 3 is formed by electroplating in copper sulfate (Fig. 4(C)). Here, the plating current density is 0.5 A/cm2, and the film thickness of the Cu plating layer 3 is 5 μm. And so. Next, the PR pattern 4 is peeled off in an organic solvent (FIG. 4(d)). After that, the unnecessary plating base layer was removed by ion etching in an Ar atmosphere (FIG. 4(e)), and the coil 16 was formed. The conditions for ion etching are Ar gas pressure 1. X 10-4T 6rr
The acceleration voltage is 500V. The time required for this plating base layer removal process was approximately 25 minutes, but under the above-mentioned ion etching conditions, the Cu ion etching rate was 600%.
Since the etching rate is A/min, the Cu plating layer 3 was etched by 1.5 μm during this time.

After forming the coil 16 as described above, a photoresist layer 17 and a C0872
An upper magnetic layer 18 made of an r5N bs film was formed in the same manner as in the example. Finally, a protective film (not shown, 25 μm in film thickness) consisting of an A1□03 film was formed by sputtering. The film forming conditions in this case are also the same as in the embodiments of the present invention.

In the thin-film magnetic head of this comparative example manufactured in the above manner, as described above, Cu with a thickness of 1.5 μm was etched in the plating underlayer removal process by ion etching, and the thickness of the Cu plating layer 3 was increased. Diminished. For this reason, it was originally supposed to have almost the same coil resistance value as the coil of the thin-film magnetic head mentioned in the example, but about 3
The coil resistance value was greater than 0%.

〔Effect of the invention〕

As described above, according to the present invention, even in a thin film magnetic head having a dense coil with narrow coil spacing and large coil thickness, the top surface of the coil remains exposed for a long time during ion etching in the plating base removal process. Since the aluminum oxide layer protects the Cu plating layer even after ion etching, the coil thickness cannot be reduced. Therefore, the effect of increasing the coil thickness and controlling the increase in coil resistance value due to an increase in the number of turns is fully exhibited.

As described above, according to the present invention, it is possible to solve problems in the coil forming process of a thin film magnetic head having a dense coil with a large number of turns, and it is considered to have high industrial value.

Incidentally, in the above explanation, only an example in which a vapor deposition method was used as a method for forming an aluminum oxide film was mentioned.
A sputtering method may also be used. Further, in the embodiment, only an example in which the magnetic circuit is formed entirely from a soft magnetic thin film is mentioned, but the present invention can also be applied to a magnetic head in which a part of the magnetic circuit is formed from a bulk material, such as by using a ferrite substrate. Of course, the intended purpose of this is not compromised.

[Brief explanation of the drawing]

1 and 3 are diagrams for explaining the present invention, and FIGS. 2 and 4 are diagrams for explaining the conventional technology. FIG. 5 is a schematic diagram showing the structure of an inductive thin film magnetic head according to the present invention. In the figure, 1...Cr layer, 2...Cu layer, 3...
・Cu plating layer, 4...PR pattern, ), 5...aluminum oxide layer, 10...substrate, 11...base body, 12.14...insulating layer, 13...lower part Magnetic layer, 15.17 Organic layer, 16 Coil, 18
...Top magnetic layer.

Claims (1)

[Claims] An inductive thin film comprising a magnetic circuit made of a magnetic material, a magnetic gap made of a non-magnetic material formed in the magnetic circuit, and a coil made of a conductive thin film formed to intersect the magnetic circuit. In magnetic heads,
A thin-film magnetic head characterized in that the coil is made of a laminate in which a plating base layer, a Cu plating layer, and an aluminum oxide layer are formed in this order.