JP3319366B2 - Method for manufacturing thin-film magnetic head - Google Patents

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 used in a magnetic recording apparatus having a magnetic disk or the like.

[0002]

2. Description of the Related Art Conventional thin-film magnetic heads include the following. That is, a protective film 2 is formed on a non-magnetic ceramic substrate, and a lower magnetic core layer, a predetermined gap, an MR section for reading, a common pole, an interlayer insulating film, and a predetermined conductor are formed on the protective film. A coil is formed. An upper magnetic core layer is formed on the interlayer insulating film. In addition, the interlayer insulating film maintains insulation between the conductor coils and between each magnetic layer and the conductor coil,
Another object of the present invention is to reduce the level difference between the magnetic layers and the conductor coils.

Here, as a specific example of the interlayer insulating film,
For example, IBM Technical DisclosureBulletin Vol.23, P2
584 (1980). According to this method, a novolak resin-based positive photoresist is used as the interlayer insulating film 6, and is applied to the entire surface by a method such as spin coating, and then ultraviolet rays are applied to portions other than the portion desired to remain as the interlayer insulating film. Then, by developing with an aqueous alkali solution, a pattern of the interlayer insulating film is formed.

The photoresist pattern of the interlayer insulating film is
It is necessary to be stably present in various steps performed thereafter. Therefore, for the purpose of stabilizing the interlayer insulating film, heat treatment is performed at about 250 ° C. or more and firing is performed.

[0005] After this heat treatment, an upper magnetic core layer is formed on the interlayer insulating film, and an overcoat layer as a protective film is adhered thereon by means such as sputtering to form a thin film magnetic head structure.

[0006]

Here, when heat-treating a photoresist as a material of an interlayer insulating film, it is important to control the temperature of the heat treatment. This is because the heat treatment temperature has a great effect on the shape management of the photoresist pattern and the magnetic domain change of the plated NiFe film as the upper magnetic core layer formed on the interlayer insulating film. In other words, care must be taken because the expansion and contraction caused by the heat treatment of the photoresist cause disturbance of the magnetic domains due to the effect of the magnetic anisotropy of the plated NiFe film.

In particular, the contraction of the interlayer insulating film exerts a great influence on the upper magnetic core layer having a positive magnetostriction, which causes a magnetic domain disturbance. Here, when the heat-treated photoresist is once again heat-treated,
The examination result of deformation characteristics in that the second time heat treatment (change of linear expansion coefficient) shown in FIG.

As a specific condition for detecting the deformation characteristic shown in FIG. 4, the photoresist was once hardened at a temperature of about 250 degrees. Then, after that, heat treatment was performed again by heating to a temperature of 250 degrees, and deformation characteristics were examined. Here, a horizontal axis represents time in FIG. 4, the left vertical axis represents linear expansion <br/> rate (shrinkage). The vertical axis, a state before the start of the heat treatment is linear expansion rate is set to zero. The right vertical axis indicates the temperature at which the heat treatment is performed.

The change in the temperature of the heat treatment is the first 60
The temperature is gradually raised for about a minute, and raised to about 250 degrees. Then, the temperature was maintained at about 250 degrees for about 60 minutes, and then the temperature was lowered to room temperature over about 60 minutes. As described above, it has been found that large deformation (shrinkage) of the photoresist occurs in a temperature region lower than the once-baked temperature. It was also confirmed that this deformation corresponds to a temperature near the glass transition point of the photoresist.

[0010] Incidentally, linear expansion rate of the left vertical axis is arbitrary units, the value if, as a matter of course changes the load changes with a change in film thickness, for example, to change or stack of stress applied to the thin film magnetic head . As described above, since this deformation causes disturbance of the magnetic domain structure of the upper magnetic core layer 10, it is actually necessary to set a high deformation temperature and a small amount of deformation.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a thin-film magnetic head capable of improving the disadvantages of the above-mentioned conventional example and suppressing the deformation of a photoresist.
With that purpose.

[0012]

According to a first aspect of the present invention, there is provided a method of manufacturing a thin film magnetic head in which a coil and an interlayer insulating film are interposed between a lower magnetic body and an upper magnetic body. together with configuring a photoresist novolac resin, heated to tighten temperature <br/> degree burn photoresist, once returned to room temperature, and heated again at a temperature near the glass transition point of the photoresist thereafter, Thereafter, the photoresist is hardened by cooling.

According to the second aspect of the present invention, the interlayer insulating film is made of a metal.
Means of forming by a pin coating method is adopted, and other means are the same as the first aspect of the present invention.

According to a third aspect of the present invention, the first heat treatment is performed at a temperature of 250 to 300 degrees, and the subsequent reheating is performed at a temperature near the glass transition point of the photoresist. Means are the same as those of the second aspect.

The invention according to claim 4 employs means for setting the reheating temperature to approximately 200 degrees, and the other means are the same as the invention according to claim 3.

According to the fifth aspect of the present invention, the interlayer insulating film is made of 1,1-bis [p-chlorophenyl] 2,2,2-trichloroethane and its isomers, analogs, homologues and other residual compounds are reduced to zero. Means are comprised of a negative photoresist containing 1 to 5%, and the other means are the same as those of the first aspect.

According to the sixth aspect of the present invention, the first heat treatment is performed at a temperature of 200 degrees, and the subsequent reheating is performed at a temperature near the glass transition point of the photoresist. This is similar to the fifth aspect of the invention.

In the invention according to claim 7, the reheating is performed for 150 hours.
A means of performing the process at a temperature of degrees is adopted, and the other means are the same as those of the sixth aspect of the present invention.

The invention according to claim 8 employs a means of performing the heat treatment in an argon atmosphere, and the other means are the same as those of the invention described in claim 1, 2, 3, 4, 5, 6, or 7. .

The ninth aspect of the present invention adopts a means of performing the heat treatment in a vacuum, and the other means are the same as those of the first, second, third, fourth, fifth, sixth, and seventh aspects.

As described above, the heat treatment is once performed up to a temperature of 250 ° C.
The photoresist that has been subjected to the heat treatment at
Deformation characteristics when the heat treatment was performed up to 50 degrees showed that the amount of deformation of the photoresist was reduced as compared with the case where the second heating was not performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, in a thin-film magnetic head according to this embodiment, a protective film 2 is formed on a non-magnetic ceramic substrate 1. Ceramic substrate 1 is Al ₂ O
It is composed of _3- TiC. Then, a protective film 2 of alumina or the like is formed on the ceramic substrate 1 by a sputtering method or the like.

On this protective film 2, a lower magnetic core layer 3 as a lower magnetic body is formed. The lower magnetic core layer 3
A soft magnetic layer such as permalloy is formed by a sputtering method or a plating method. Then, a predetermined gap layer 8a is formed on the lower magnetic core layer 3.
The gap layer 8a is an insulating layer having a predetermined thickness and made of alumina or the like.

Next, an MR section 4 for reading magnetic information is formed on the gap layer. M for reading
The R portion 4 is made of, for example, NiO, Co as an antiferromagnetic layer material.
It is composed of a spin valve film using O, a magnetic layer of NiFe, and a nonmagnetic layer of Cu or the like. And this MR
On the portion 4, a predetermined gap layer 8b, which is an insulating layer made of alumina or the like, is formed.

A so-called common pole 5 is formed on the gap layer 8b. The common pole 5 is formed by forming a soft magnetic layer such as permalloy by a sputtering method or a plating method. In addition, common pole 5
A recording gap 9 is formed above the above (step S1 in FIG. 1).

On the recording gap layer 9, the interlayer insulating film 6 is formed (Step S2 in FIG. 1). To form the interlayer insulating film 6, a positive resist such as a novolak resin is applied to the entire surface of the recording gap 9 by spin coating or the like. After that, ultraviolet irradiation is performed on portions other than the portion to be left as the interlayer insulating film 6. Thereafter, a desired pattern of the interlayer insulating film 6 is formed by developing (etching) with an alkaline aqueous solution (Step S3 in FIG. 1).

Thereafter, a heat treatment is performed for about one hour in a nitrogen gas atmosphere at 250 ° C. or higher (step S 4 in FIG. 1).
An interlayer insulating film 6 made of a hardened photoresist is formed. The photoresist of the interlayer insulating film 6 needs to be stably present in various steps performed thereafter. Therefore, for the purpose of stabilizing the interlayer insulating film 6, about 250
It is heated and baked at a temperature of at least ℃.

After the above heat treatment, the heating is stopped and the thin-film magnetic head is once returned to room temperature (step S in FIG. 1).
5). Then, a heat treatment is performed again at a temperature of about 200 degrees for about 1 hour (step S6 in FIG. 1). Next, a coil 7 is formed on the interlayer insulating film 6 by plating.
Step S7). The coils 7 are formed so as to be separated from each other as shown in FIG. However, the cooling does not need to be returned to room temperature, and may be merely lowered to a temperature below the glass transition point.

The interlayer insulating film 6 not only maintains the insulation between the conductor coils 7 and between the magnetic layers and the conductor coil 7 but also reduces the step between the magnetic layers and the conductor coil 7. Has both functions. Therefore, in order to eliminate the step caused by the coil 7, a positive photoresist is applied again by the spin coating method (Step S8 in FIG. 1),
After performing the heat treatment in the above inert gas atmosphere for about 1 hour (Step S9 in FIG. 1), after once cooling (Step S10 in FIG. 1), the reheat treatment is performed again at a temperature of about 200 ° C. for about 1 hour. (Step S11 in FIG. 1). In the present embodiment, since the coil 7 is formed in two layers, the coil forming process is repeated.

After the heat treatment, the interlayer insulating film 6 is formed.
An upper magnetic core layer 10 as an upper magnetic body is formed thereon (step S12 in FIG. 1). Then, an overcoat layer 11 as a protective film made of alumina is adhered from above the interlayer insulating film 6 by means such as sputtering (step S13 in FIG. 1) to obtain a thin film magnetic head structure.

As described above, the present invention is characterized in that the photoresist used as the interlayer insulating layer 6 is subjected to a two-stage heat treatment for stabilization. Specifically, the reheat treatment is performed at a temperature lower than the initial heat treatment temperature (around the glass transition temperature). This allows
Thereafter, experiments have revealed that even when the thin-film magnetic head is heated, the deformation (reduction) of the interlayer insulating film 6 is suppressed as compared with the conventional case.

Next, a second embodiment of the present invention will be described. The second embodiment is characterized in that, unlike the first embodiment, a negative photoresist having good heat resistance is used instead of the novolak- based positive photoresist. About a specific structure, since a main part is common to 1st Embodiment, about the same component,
Use the same reference signs to avoid duplicate descriptions.

The thin-film magnetic head of this embodiment is also made of Al ₂ O
An insulating layer 2 made of alumina or the like is formed on a ceramic substrate 1 made of _3- TiC by a sputtering method or the like, and then a soft magnetic layer made of a permalloy or the like is formed by a sputtering method or a plating method, and the lower magnetic core layer 3 is formed. Form.

Thereafter, a read MR unit, for example, Ni
A spin valve film made of O, CoO, NiFe, Cu or the like is formed. Thereafter, in order to form a predetermined gap layer 8a, an insulating layer made of alumina or the like having a predetermined thickness is formed.

Thereafter, a soft magnetic layer such as permalloy is formed by sputtering or plating to form a common pole. A recording gap 9 is formed on the common pole. Further, a photoresist is applied to the entire surface of the recording gap 9 by a spin coating method. Up to this point, it is the same as in the first embodiment.

Then, using a predetermined mask, patterning is performed on the photoresist to be the interlayer insulating film 6. After that, the photoresist other than the portion remaining as the interlayer insulating film 6 is removed by etching with a developing solution.

Thereafter, the thin film magnetic head is subjected to heat treatment for about one hour in a nitrogen gas atmosphere maintained at a temperature of 200 ° C. or less. Thus, the interlayer insulating film 5 made of the hardened photoresist is formed. After the baking is thus performed, a reheating process is performed again at a temperature of about 150 ° C. for about 1 hour.

Next, the coil 6 is formed by plating. The coil is formed in the same manner as in the first embodiment. Next, in order to eliminate the step due to the coil 6, the 1,1-bis [p-
Chlorophenyl] -2,2,2-trichloroethane and a negative photoresist containing 0.1 to 5% of isomers, analogs, homologues and residual compounds thereof are applied by spin coating.

This negative type photoresist is applied by a spin coating method, subjected to a heat treatment in an inert gas atmosphere of 200 ° C. or more for about 1 hour, and then subjected to a heat treatment at a temperature of about 150 ° C. for about 1 hour. . After that, similarly to the lower magnetic core layer (shield), an upper magnetic core layer is formed, a protective film made of an alumina film is formed, and a composite magnetic head structure is obtained.

In each of the above embodiments, the heat treatment for baking was performed in nitrogen gas. However, this is an example, and the present invention is not limited to this. That is, you may carry out in argon gas which is an inert gas. In this case, it is possible to reduce the amount of deformation even at the same temperature as compared with the case of heat treatment in nitrogen. Further, it is also effective to perform heat treatment for baking in a vacuum. In this case, the deformation amount can be further reduced even at the same temperature as compared with the heat treatment in nitrogen or argon. As described above, the reason why the heat treatment is performed in an inert gas or vacuum is to prevent the degree of polymerization of the photoresist as the interlayer insulating film from being reduced.

[0041]

As described above, according to the method of the present invention, the photoresist is heated to a predetermined temperature, returned to normal temperature, and then heated again at a temperature near the glass transition point of the photoresist. Then, the photoresist was hardened by cooling. Thereby, when heat treatment is performed thereafter, deformation (shrinkage) is effectively suppressed. Therefore, even when the heat treatment is performed after forming the upper magnetic body, the influence of the interlayer insulating layer on the upper magnetic body is suppressed, and the magnetic domain structure of the magnetic film is not disturbed due to the deformation of the photoresist. This produces an excellent effect.

Since the second heat treatment is performed at a temperature lower than the temperature at which the first heat curing treatment was performed, the second heat treatment does not cause deterioration of the magnetic film or the like formed in advance. This produces an excellent effect.

Further, since the above-mentioned heat treatment is performed in an inert gas atmosphere or in a vacuum, the oxidation of the photoresist due to the heat treatment is effectively prevented, and the excellent effect that the photoresist is cured with a high degree of polymerization is obtained. Occurs.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of a thin-film magnetic head according to the present invention.

3 is a graph showing changes in linear Rise expansion coefficient for heat treatment of the thin film magnetic head is constituted by the method of the present invention.

4 is a graph showing changes in linear Rise expansion coefficient for heat treatment of the conventional thin film magnetic head and heat-treated by the method.

[Explanation of symbols]

 Reference Signs List 1 ceramic substrate 2 protective film 3 lower magnetic core layer (shield) 4 MR part 5 common pole made of permalloy 6 interlayer insulating film (photoresist) 7 coil (Cu film) 8 gap (alumina) 9 recording gap (alumina) 10 Upper magnetic core layer 11 Overcoat layer

Claims (9)

(57) [Claims] 1. A method of manufacturing a thin-film magnetic head in which a coil and an interlayer insulating film are interposed between a lower magnetic body and an upper magnetic body, wherein the interlayer insulating film is made of a novolak-based photoresist. tighten temperature burn the photoresist or
And temporarily returning the temperature to normal temperature, and then heating the photoresist again at a temperature near the glass transition point of the photoresist, and then cooling the photoresist to harden the photoresist. 2. The method according to claim 1, wherein the interlayer insulating film is formed by spin coating.
2. The method according to claim 1, wherein the thin film magnetic head is formed. 3. The method according to claim 1, wherein the first heat treatment is performed at a temperature of 250 to 30 degrees.
3. The method according to claim 2, wherein the heating is performed at a temperature of 0 degrees, and the subsequent reheating is performed at a temperature near the glass transition point of the photoresist. 4. The method of manufacturing a thin-film magnetic head according to claim 3, wherein the reheating temperature is set to approximately 200 degrees. 5. A negative type photo-conductive film containing 1,1-bis [p-chlorophenyl] 2,2,2-trichloroethane and its isomers, analogs, homologues and other residual compounds. 2. The method according to claim 1, wherein the head is made of a resist. 6. The method according to claim 5, wherein the first heat treatment is performed at a temperature of 200 degrees, and the subsequent reheating is performed at a temperature near the glass transition point of the photoresist.
The manufacturing method of the thin film magnetic head according to the above. 7. The method according to claim 6, wherein the reheating is performed at a temperature of 150 degrees. 8. The method according to claim 1, wherein the heat treatment is performed in an argon atmosphere. 9. The method according to claim 1, wherein the heat treatment is performed in a vacuum.