JP2702215B2 - Method for manufacturing thin-film magnetic head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductive thin film magnetic head used for a magnetic disk device, a magnetic tape device, and the like, and in particular, an inductive thin film manufactured using an integrated thin film technology. The present invention relates to a structure of a coil of a magnetic head.

[Prior Art] In recent years, in the field of magnetic recording, higher recording densities have been increasing,
In a magnetic head that supports magnetic recording together with a recording medium, a thin film magnetic head manufactured by using integrated thin film technology has been put to practical use instead of a conventional ferrite head. This thin film magnetic head has excellent frequency characteristics,
Since a manufacturing process based on semiconductor technology can be applied, a high-precision magnetic head for high recording density can be manufactured at a low price, and it is becoming the mainstream of magnetic heads in the future.

FIG. 5 is a schematic sectional view of such a thin film magnetic head. In FIG. 5, a ceramic substrate 10 such as Al ₂ O ₃ —TiC
An insulating layer 12 of Al ₂ O ₃ or the like is formed thereon by a sputtering method or the like, and a lower magnetic layer made of a soft magnetic material such as a NiFe alloy or a Co-metal-based amorphous material (eg, CoZrNb) is formed thereon. The body layer 13 is formed using the integrated thin film technology. On the magnetic layer 13, an insulating layer 14 having a thickness equal to a predetermined gap length, an organic layer 15 serving as a step eliminating layer of the lower magnetic layer 13, and a coil 16 made of a conductive material are formed. . On the coil and in the coil gap, an organic material layer 17 is formed again as a step-eliminating layer of the coil 16, and then an upper magnetic layer made of a soft magnetic material such as a NiFe alloy or a Co-metallic amorphous material (for example, CoZrNb). The body layer 18 is formed in the same manner as the lower magnetic layer 13, and a protective layer (not shown) made of an insulator is formed to complete the transducer of the thin-film magnetic head.

The coil 16 of the above-mentioned thin-film magnetic head is usually made of an electrolytic copper (Cu) plating film, and its schematic sectional structure is as shown in FIG. That is, the coil 16 shown in FIG. 5 has a laminated structure of a plating base layer made of a laminate of a Cr layer 5 and a Cu layer 6 (this laminate is usually formed by a sputtering method) and a Cu plating layer 3. ing.

FIG. 4 shows a manufacturing process of such a conventional coil.
First, in FIG. 4 (a), a laminate of a Cr layer 5 and a Cu layer 6 is formed on the base body 11 by a sputtering method to form a plating base layer. Next, as shown in FIG. 4 (b), a photoresist pattern (hereinafter abbreviated as PR pattern) 4 having a predetermined shape is formed by using a known exposure / development technique. Thereafter, as shown in FIG. 4C, Cu is deposited in a plating bath containing copper sulfate as a main component to form a Cu plating layer 3. Next, the PR pattern 4 was peeled off (FIG. 4 (d)), and as shown in FIG. 4 (e), the plating underlayer covered with the PR pattern 4 was ion-etched in an Ar gas atmosphere. Part is removed to form a coil. In this manufacturing process, as is clear from FIG. 4 (e), the Cu plating layer 3 is also ion-etched in the plating underlayer removing step, so that the thickness of the CU plating layer 3 is determined by the time required to remove the plating underlayer. Decrease by minutes.

By the way, in light of the recent trend toward higher recording densities, the leakage magnetic field from information recorded on a medium has become increasingly small, and there is a concern that the reproduction output of the head may be reduced. Since the reproduction output of an inductive type thin-film magnetic head is almost proportional to the number of turns of the coil, forming a dense coil by narrowing the coil interval as much as possible and increasing the number of turns of the coil is one powerful way to compensate for this decrease in the reproduction output. Is considered a means.

[Problems to be Solved by the Invention] However, when the number of coil turns is increased by the above-described conventional structure and manufacturing method, there are the following problems.

That is, in a dense coil, the coil interval is naturally narrower than the conventional coil interval (about 4 μm), and is generally about 2 μm or less. On the other hand, the coil thickness (the sum of the thickness of the plating underlayer and the thickness of the Cu plating layer 3) is also about 3 μm at present, but is increased to reduce the effect of an increase in coil resistance due to an increase in the number of coil turns ( (For example, 4 μm or more).

In such a dense coil having a small coil interval and a large 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. The time required for the plating underlayer removing step is greatly increased as compared with the case where a conventional coil having a large interval is formed.

This is because, since the coil interval is small and the coil thickness is large, the plating underlayer to be removed is located deep from the coil upper surface (the surface indicated by arrow A in FIG. 2), and the Ar particles are removed under the plating. The frequency of reaching the stratum decreases, and the plating ground struck by the Ar particles does not easily come off from the gap between the coils due to reattachment to the side surface of the coil, etc. This is considered to be caused by a decrease in the effective etching rate at the part where the part was removed, and is an inevitable phenomenon.

As described above, in the step of removing the plating underlayer of the dense coil, it takes a long time to complete the step, and as a result, the upper surface of the coil (the surface indicated by arrow A in FIG. 2) is subjected to ion etching for a long time. And the coil thickness is greatly reduced. Therefore, the effect of increasing the coil thickness and suppressing an increase in the coil resistance value due to an increase in the number of windings cannot be sufficiently obtained, which has been a problem. This is more remarkable as the coil thickness is larger and the coil interval is smaller, and has been a serious problem in the head manufacturing process.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thin-film magnetic head having a dense coil having a thick coil and a narrow coil interval by solving the above-described problems in the coil forming step of the thin-film magnetic head and a method of manufacturing the same. It is.

[Means for Solving the Problems] According to the present invention, a coil manufacturing process in a method of manufacturing an inductive type thin film magnetic head includes a step of forming a plating base layer made of Ta or Ti on a substrate; A step of forming a photoresist pattern corresponding to the coil shape, a step of forming an electric Cu plating layer in the photoresist pattern gap, a step of peeling off the photoresist pattern, and a step of removing the exposed plating underlayer. And removing the exposed plating underlayer by a reactive etching in an atmosphere containing CF ₄ gas as a main component.

[Operation] By adopting the above configuration, the present invention has made it possible to provide a thin-film magnetic head that has solved the conventional problems.

That is, according to the study of the present inventors, in reactive ion etching in an atmosphere containing CF ₄ gas as a main component, the etching rate of the Ta thin film and the Ti thin film is very high, while the etching rate of the Cu plating layer is increased. The speed is extremely low, about 1/15 of Ta and about 1/20 of Ti. Therefore,
When the Ta layer or the Ti layer is used as the plating underlayer, it is possible to remove the unnecessary plating underlayer without substantially etching the Cu plating layer.

For example, when a Ta thin film having a thickness of 3000 mm is used as a plating underlayer, the etching rate of Ta in a CF ₄ gas atmosphere is 3
Since it is 00 ° / min (CF ₄ gas pressure 4.5 Pa, input power 100 W), the step of removing the plating underlayer is completed in about 10 minutes. During this time, the Cu plating layer has an etching rate of Cu of about 20 ° / min under the same etching conditions, so that its thickness is reduced only by about 200 °.

On the other hand, when a 3000-mm-thick Ti thin film is used as the plating underlayer, the etching rate of Ti in a CF ₄ gas atmosphere is 400
Å / min (CF ₄ gas pressure 4.5Pa, input power 100W)
The removal process of the plating underlayer is completed in about 8 minutes. During this time,
Since the Cu plating layer has a Cu etching rate of about 20 ° / min under the same etching conditions, its thickness is reduced only by about 160 °.

Therefore, by using a Ta or Ti thin film as a plating underlayer and removing the plating underlayer by reactive etching in a CF ₄ gas atmosphere, during the plating underlayer removal step,
A dense coil having a small coil interval is realized without substantially etching the upper surface of the Cu plating layer.

The etching rate of Ta or Ti in the CF ₄ gas atmosphere is different from that in the case where the plating underlayer is removed by ion milling in the Ar gas atmosphere.
Up to about m, there is almost no coil spacing dependence. Therefore, the time required for removing the plating underlayer hardly changes.

Next, an embodiment of the present invention will be described with reference to the drawings.

As described above, the induction type thin film magnetic head of the present invention is characterized by its coil structure, and the other parts of the thin film magnetic head according to the present invention have a schematic structure shown in FIG. Since there is not much difference from the structure of the thin film magnetic head, the following embodiment will be described with reference to FIG.

Example 1 In FIG. 5, Al ₂ O ₃ —TiC
_The insulating layer 12 made of a ₂ O ₃ film is sputtered (input power:
A film was formed at a film thickness of 10 μm at 600 W under an Ar gas pressure of 5 × 10 ⁻³ Torr). Next, a Co ₈₇ Zr ₅ Nb ₈ film having a thickness of 3 μm was formed by a sputtering method, and the lower magnetic layer 13 was formed by a known photolithography technique. The Co ₈₇ Zr ₅ Nb ₈ film was formed under the following conditions: input power: 600 W, Ar gas pressure: 5 × 10 ⁻³ Torr
After the film formation, the magnetic properties were improved by annealing at 250 ° C. for 1 hour in a rotating magnetic field of 480 Oe.

Thereafter, a film thickness (0.2 μm) equal to the predetermined gap length
Sputtering an Al ₂ O ₃ film having a film formation (input power: 300 W, Ar gas pressure: 5 × 10 ^-3 Torr) and was an insulating layer 14. Next, a 4 μm-thick photoresist made of a novolak resin is applied on the lower magnetic layer 13, and is heat-treated at 250 ° C. for 1 hour to be hardened, thereby forming an organic material serving as a step eliminating layer of the lower magnetic layer 13. Layer 15 was formed, and then coil 16 was formed.

Hereinafter, the manufacturing method and structure of the coil 16 will be described in detail with reference to FIGS.

FIG. 3 is a partial sectional view showing a coil manufacturing method according to the present invention in the order of steps. In the figure, a plating underlayer consisting of a Ta layer 2 (thickness 3000 °) was formed on a base 1 (corresponding to the organic layer 15 in this embodiment) by sputtering (FIG. 3A). . Deposition conditions are input power: 600
W, Ar gas pressure: 5 × 10 ⁻³ Torr. Next, it becomes a plating frame using a known photolithography technique.
A PR pattern 4 was formed (FIG. 3 (b)). The photoresist used was a commercially available novolak resin-based resist. The PR pattern 4 had a thickness of 6 μm and a pattern width of 1 μm.
m, and the pattern interval was 3 μm. RP pattern 4
Is 1 μm, the coil interval is 1 μm
It is. Thereafter, Cu was electroplated in a copper sulfate bath to form a Cu plating layer 3 (FIG. 3 (c)). Here, the plating current density was 1 A, and the thickness of the Cu plating layer 3 was 5 μm. Next, the PR pattern 4 was peeled off in an organic solvent (third
Figure (d). Finally, the unnecessary plating underlayer was removed by reactive etching in a CF ₄ gas atmosphere (FIG. 3 (e)), and the coil 16 was formed. The etching conditions were as follows: CF ₄ gas pressure: 4.5 Pa, input power: 100 W. The time required for the plating underlayer removing step was about 10 minutes,
During this time, the Cu plating layer 4 was etched at about 200 ° out of the film thickness of 5 μm since the etching rate was about 20 ° / min, but the increase in coil resistance value due to this was almost negligible.

The schematic structure of the formed coil is, as shown in a partial sectional view of FIG.
It has a structure in which Cu plating layers 3 are sequentially laminated.

After the coil 16 was formed as described above, an organic layer 17 made of a photoresist to be a step-eliminating layer of the coil 16 was formed in the same manner as the organic layer 15 described above. Next, an upper magnetic layer 18 made of a Co ₈₇ Zr ₅ Nb ₈ film having a thickness of 3 μm was formed in the same manner as the lower magnetic layer 13. Finally, a protective film (not shown, about 25 μm thick) made of Al ₂ O ₃ was formed by a sputtering method. The film formation conditions were as follows: input power: 800 W, Ar gas pressure: 5 × 10
^-3 Torr.

In the thin-film magnetic head of the present embodiment manufactured as described above, the etching amount of the Cu plating layer is about 200 ° (about the coil thickness) despite the coil interval being as narrow as 1 μm and the coil thickness being as thick as about 5 μm. 0.4%), which was almost negligible. Therefore, the conventional problem that the coil thickness decreases and the coil resistance value increases does not occur.

Example 2 A thin-film magnetic head was manufactured in the same manner as in Example 1 except that the Ta layer was changed to the Ti layer.

In this example, the time required for the plating underlayer removal step was about 8 minutes.
Has an etching rate of about 20 ° / min.
Of these, about 160 ° was etched, but the increase in coil resistance due to this was almost negligible. The schematic structure of the formed coil is, as shown in FIG. 1 in a partial cross-sectional view, a plating base layer made of a Ti layer (shown as a Ta layer 2 in the figure) and a Cu plating layer 3 sequentially laminated. It has the structure which was done. Also, the obtained thin film magnetic head is
Despite the coil interval being as narrow as 1 μm and the coil thickness as thick as about 5 μm, the etching amount of the Cu plating layer is about 160 μm.
Å (about 0.3% of coil thickness) was almost negligible. Therefore, the conventional problem that the coil thickness decreases and the coil resistance value increases does not occur.

On Comparative Example 1 Example 1 and 2 in the same manner as Al ₂ O ₃ -TiC ceramic substrate 10, the insulating layer 12, the lower magnetic layer 13, the insulating layer 14 and the organic material layer 15 becomes the gap, then the coil 16
Was formed. The coil 16 was formed using the conventional coil structure shown in FIG. 4 as follows.

That is, in FIG. 4, the base body 11 (the fifth
A plating base layer consisting of a laminated film of a Cr layer 5 (thickness 30 °) and a Cu layer 6 (thickness 2000 °) was formed on the organic material layer 15 shown in FIG. )).
Next, a PR pattern 4 serving as a plating frame was formed by using a known photolithography technique (FIG. 4B). The photoresist used was a commercially available novolak resin-based resist. The PR pattern 4 is the same as in the first embodiment.
Similarly to 2, the film thickness was 6 μm, the pattern width was 1 μm, and the pattern interval was 3 μm. In addition, since the pattern width of the RP pattern 4 is 1 μm, the coil interval is 1 μm.
Then, Cu is electroplated in a copper sulfate bath, and the Cu plating layer 3 is formed.
Was formed (FIG. 4 (c)). Here, the plating current density was 0.5 A / cm ² , and the thickness of the Cu plating layer 3 was 5 μm. Next, the PR pattern 4 was peeled off in an organic solvent (FIG. 4 (d)). Finally, the unnecessary plating underlayer was removed by ion etching in an Ar atmosphere (FIG. 4 (e)), and the coil 16 was formed. The ion etching conditions are Ar gas pressure: 1 × 10 ⁻⁴ Torr and acceleration voltage: 500 V. The time required for the plating underlayer removing step was about 25 minutes. However, under the above ion etching conditions, the Cu ion etching rate was 600 ° / min.
m etched.

After the coil 16 is formed in this manner, a photoresist layer 17 serving as a step eliminating layer of the coil 16 and an upper magnetic layer 18 formed of a Co ₈₇ Zr ₅ Nb ₈ film are formed in the same manner as in Examples 1 and 2. did. Finally, a protective film made of an Al ₂ O ₃ film (not shown,
A film having a thickness of about 25 μm) was formed by a sputtering method. The film forming conditions in this case are the same as those in the embodiment of the present invention.

As described above, in the thin-film magnetic head of this comparative example manufactured as described above, in the plating underlayer removing step by ion etching, Cu having a thickness of 1.5 μm was etched, and the thickness of the Cu plating layer 3 was reduced. Greatly reduced. For this reason, the coil resistance of the thin-film magnetic head should be almost the same as the coil of the thin-film magnetic head mentioned in the embodiment, but the coil resistance is larger by about 30% or more.

Comparative Example 2 A Cu plating layer 3 was formed in exactly the same manner as in Comparative Example 1, and then the PR pattern 4 was peeled off with an organic solvent. Then CF ₄
Unnecessary plating underlayers were removed by reactive etching in a gas atmosphere. The etching conditions were the same as in Example 1, with a CF ₄ gas pressure of 4.5 Pa and an input power of 100 W. Cu and Cr etching rates in CF ₄ gas atmosphere are both 20Å
/ Min, it took about 100 minutes to remove the plating underlayer. During this time, the Cu plating layer 3 was etched by about 2000 °. This etching amount is small as compared with the value in Comparative Example 1, but is about 10 times as large as in Example 1 and about 12 times as large as in Example 2. It is inevitable that the coil resistance value increases by the amount. Also, the time required for the step of removing the plating underlayer was abnormally long, about 100 minutes, and the throughput was extremely low. This proved to be a problem in the manufacturing process of the thin film magnetic head.

In the above description, an example using only CF ₄ gas has been described, but other gases (for example, Ar, Cl ₂ , N ₂₎ may be used as long as the etching rate ratio between Ta and Cu is within a sufficient range. ) May be added in a small amount.

In the embodiment, only the example in which the magnetic circuit is entirely formed of a soft magnetic thin film has been described. However, the present invention is also applicable to a magnetic head in which a part of the magnetic circuit is formed of a bulk material, such as using a ferrite substrate. Naturally, the intention of the invention is not impaired.

[Effects of the Invention] As described above, according to the present invention, it is possible to minimize the decrease in the thickness of the Cu plating layer during the plating underlayer removing step in the coil manufacturing process, to reduce the coil interval,
In addition, a dense coil having a large coil thickness can be manufactured.
Therefore, a thin-film magnetic head for high recording density is realized.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a coil portion according to an embodiment of the present invention, FIG. 2 is a partial sectional view of a coil portion of a conventional thin-film magnetic head, and FIG. FIG. 4 is a partial cross-sectional view of a coil portion showing a method of manufacturing a thin-film magnetic head according to a conventional example in the order of steps, and FIG. 5 is a schematic cross-sectional view of an inductive thin-film magnetic head of the present invention. is there. 1,11 ... underlying body, 2 ... Ta layer 3 ... Cu plating layer 4, ... PR pattern 5 ... Cr layer, 6 ... Cu layer 10 ... substrate, 12,14 ... insulating layer 13 ... … Lower magnetic layer, 15, 17… Organic layer 16… Coil, 18… Upper magnetic layer

Claims (1)

(57) [Claims] In a method of manufacturing an inductive type thin film magnetic head, a coil manufacturing process includes a step of forming a plating base layer made of Ta or Ti on a substrate, and a step of forming a photoresist pattern corresponding to a coil shape on the plating base layer. Forming an electro-Cu plating layer in the photoresist pattern gap, removing the photoresist pattern, and removing the exposed plating underlayer. removal of the method of manufacturing a thin film magnetic head, characterized in that it is performed by reactive etching in an atmosphere mainly composed of CF ₄ gas.