JPH10247308A - Method for forming gap layer of thin film magnetic head - Google Patents

Abstract

(57) [Problem] To make electrical insulation performance not deteriorate even if an alumina gap layer formed on a magnetic layer is thinned, and to be able to cope with a narrow gap. SOLUTION: This is a gap layer forming method for manufacturing a thin film magnetic head having a structure in which a plurality of magnetic layers provided on a ceramic substrate are separated by a gap layer made of alumina. When forming a gap layer on the surface of the magnetic layer on the substrate 44 by RF bias sputtering, a sputtering mode in which RF power is supplied to the alumina target 40 side to perform RF sputtering film formation, and a supply of RF power to the target side And an etching mode in which RF etching is stopped and
This process is repeated alternately a plurality of times to form an alumina film serving as a gap layer while flattening the protrusions on the surface of the magnetic layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an alumina film to be a magnetic gap layer by RF (high frequency) bias sputtering in a manufacturing process of a thin film magnetic head. More specifically, the present invention provides a sputtering mode in which RF power is supplied to the alumina target side to perform RF sputtering film formation during sputtering film formation, and an RF etching is performed by stopping the supply of RF power to the target side. The present invention relates to a method for forming a gap layer of a thin-film magnetic head capable of coping with a narrow gap by improving the electrical insulation performance of an alumina gap layer by alternately repeating the etching mode to be performed a plurality of times. This technique is particularly useful for manufacturing an MR type thin film magnetic head for a hard disk drive.

[0002]

2. Description of the Related Art There are various types of thin-film magnetic heads for hard disk drives, and typical examples thereof include an induction type and an MR composite type. The induction type has a configuration in which two upper and lower magnetic poles provided on a substrate are separated by a gap layer, and a coil layer for generating a magnetic field and for inducing an induced current is formed between the two magnetic poles. The MR composite type uses the MR effect (magnetoresistive effect) for reading (reproducing) information, and uses the upper and lower magnetic poles and the magnetic field generating coil layer similar to the induction type for writing information. A read element section having an MR element is provided thereon, and a write element section is stacked on the read element section. This MR composite thin-film magnetic head has a separated type in which an upper shield layer of a read element section and a lower magnetic pole of a write element section are separately provided via an isolation layer (gap between elements), and an upper shield layer of a read element section. There is a shared type which also serves as the lower magnetic pole of the write element unit. The shared type is currently the mainstream of MR type thin film magnetic heads because the number of layers to be formed is small and the process is correspondingly simplified.

FIG. 4 shows an example of a main part of a shared type MR thin film magnetic head. A represents a cross section parallel to the air bearing surface, and B represents an xx cross section perpendicular thereto. As described above, the read element section 12 is provided on the ceramic substrate 10, and the write element section 14 is provided thereon. The read element unit 12
MR element 16 and leads 1 provided at both ends of the MR element 16
8 are located between the lower shield layer 20 and the upper shield layer / lower magnetic pole 22, with a gap layer 24 interposed therebetween. The write element section 14 includes the upper shield layer and lower magnetic pole 22, a write gap layer 26,
It has an upper magnetic pole 28, and a single or plural coil layers 32 are disposed between the upper shield layer / lower magnetic pole 22 and the upper magnetic pole 28 via an insulating layer 30 at a position recessed from the air bearing surface. is there.

The gap layers 24 and 26 of the thin film magnetic head as shown in FIG. 4 are usually made of an alumina (Al ₂ O ₃ ) film, and have a desired film thickness by RF (high frequency) sputtering using an alumina target. The film is formed as follows.

[0005]

With the recent increase in recording density of a hard disk drive, the gap of an MR thin film magnetic head has been narrowed, and the thickness of an alumina film serving as a gap layer has become extremely thin. I have. For example, the gap length on the read element portion side is currently about 3000 °, but since the MR element 16 is arranged in the gap, the gap length between the lower shield layer 20 and the MR element 16 is about 1000 °. Become.

In an MR thin-film magnetic head, a gap layer is formed on a lower shield layer. This lower shield layer is made of a Fe-based metal (eg, Ni—Fe or Fe—).
Since the plating layer is made of Al-Si or the like, there is a defect that the surface properties are poor (the irregularities are large). If an attempt is made to form a thin gap layer (alumina film) on the lower shield layer having such poor surface properties, the alumina film becomes extremely thin at the projections of the lower shield layer, and the electrical insulation performance is reduced. Occurs. Therefore, in order to secure sufficient electrical insulation performance, the RF power is supplied to the substrate (wafer) side as well.
Although the F bias sputtering method is employed, a sufficient effect is not necessarily obtained depending on the degree of unevenness of the lower shield layer (a sufficient flattening effect cannot be obtained due to a relationship between a film forming rate and an etching rate).

In order to solve such a problem, the surface of the substrate is subjected to RF etching in advance to planarize the projections of the lower shield layer, and then an alumina film serving as a gap layer is formed by sputtering. It is possible. However, if the RF etching is performed before forming the alumina film, the resist for pattern formation is etched, and contamination inside the sputtering apparatus occurs. As a result, the state of formation of the alumina film deteriorates, and the electrical insulation performance is deteriorated.

An object of the present invention is to reduce the electrical insulation performance of a gap layer made of a thin alumina film by flattening minute projections on the surface of the magnetic layer together with the formation of alumina when the gap layer is formed by the RF bias sputtering method. An object of the present invention is to provide a method for forming a gap layer of a thin-film magnetic head which can prevent the occurrence of a gap and thereby can cope with a narrow gap.

[0009]

SUMMARY OF THE INVENTION The present invention is a method of forming a gap layer when manufacturing a thin film magnetic head having a structure in which a plurality of magnetic layers provided on a ceramic substrate are separated by a gap layer made of alumina. Here, the features of the present invention are as follows.
When forming the gap layer by the RF bias sputtering method, the RF power is supplied to the alumina target side to perform RF sputtering film formation, and the sputtering mode in which the supply of the RF power to the target side is stopped and the RF etching is performed. An etching mode is alternately repeated a plurality of times to form an alumina film serving as a gap layer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is carried out by using, for example, an RF bias sputtering film forming apparatus as shown in FIG. RF power is supplied from an RF (high frequency) power supply 42 to an alumina (Al ₂ O ₃ ) target 40, and an RF (high frequency) bias power supply 46 is connected to a substrate (wafer) 44 side to supply RF power. The alumina target 40 and the RF power supply 42
A configuration is provided in which a switch device 48 can be interposed to control the supply / stop of the RF power. 13.56 MHz is generally used as the RF frequency. Note that an argon gas (Ar) is supplied into the inside of the sputtering apparatus.

By turning on the switch device 48 and supplying RF power to the alumina target 40, alumina is formed on the surface of the lower shield layer on the substrate 44 by RF bias sputtering. In this sputtering mode, after forming an extremely thin alumina film (thickness which is about a fraction of the originally required thickness), the switch device 48 is turned off to stop the supply of the RF power to the alumina target 40, RF etching is performed. These sputtering mode and etching mode are alternately repeated a plurality of times. When RF etching is performed on the lower shield layer having a small convex portion on the surface, charges converge on the distal end of the convex portion due to an edge effect, and the etching is selectively performed. At this time, the resist on the surface is not etched because it is covered with the alumina film, and does not contaminate the inside of the sputtering apparatus. By selective etching,
The protruding tip of the projecting lower shield layer is flattened. Thereby, the convex portion of the lower shield layer is flattened,
An alumina film is easily formed thereon, and is finally formed to a required thickness.

FIG. 2 shows a state of forming an alumina film by the method of the present invention, and FIG. 3 shows a state of forming an alumina film by a conventional method. When the lower shield layer 52 is formed on the substrate (wafer) 44 on which the alumina protective film 50 is formed, the surface properties are poor because the lower shield layer 52 is a plating layer of an Fe-based metal. When this is schematically depicted, as shown in FIG. 3, the surface state is such that a large number of minute projections 52a having a sharp tip are dispersed. In the conventional method, since the alumina film 54 is formed by the RF sputtering method as it is, the film thickness becomes thin at the sharp tip of the convex portion, and the electrical insulation performance is inevitably reduced. On the other hand, in the method of the present invention, by alternately performing the sputtering mode and the etching mode a plurality of times, the tips of the projections of the lower shield layer 52 are selectively etched, and as shown in FIG. Is flattened, and as a result, an alumina film 54 having a sufficient film thickness can be formed also on the projection 52b.

In the present invention, the number of times of repeating the RF bias sputtering mode and the RF etching mode is 3 to 7
The number is preferably about five times, particularly preferably about five times. If the number of times is small, the effect of flattening the convex portion is small, and it is difficult to improve the electrical insulation performance. This is because they are mixed into the film, and as a result, the electrical insulation performance is reduced.

According to the present invention, it is desired to form a very thin alumina film on the surface of the underlayer, such as a gap layer on the read element portion side of the MR composite thin film magnetic head, which has poor surface properties such as irregularities. This is particularly effective in cases. The present invention can be applied to the formation of a gap layer on the write element portion side and the formation of a gap layer of an inductive type thin film magnetic head. It is possible to ensure an excellent electrical insulation performance.

[0015]

[Example] Substrate (wafer) with alumina protective film formed
Bias sputtering mode in which a lower shield layer is formed by plating an Fe-based metal on an aluminum layer, and an alumina film serving as a gap layer is formed, and an RF etching mode in which a convex portion of the lower shield layer is etched to planarize. Were performed alternately. As a method, using an apparatus shown in FIG. 1, an alumina film is formed by an RF bias sputtering method, RF power on a target side is cut off during the film formation, the mode is shifted to an RF etching mode, and a certain amount of RF etching is performed. And then R again
The mode shifts to the F bias sputtering mode. By repeating this, an alumina film was formed to a required thickness. Table 1 shows the relationship between the number of repetitions and the electrical insulation performance. The final alumina film thickness was about 1000 °, and the transition from the sputtering mode to the etching mode was time-adjusted so that the film thickness in each sputtering mode was constant. In Table 1,
The number of repetitions of 0 means the case where only sputtering is performed and etching is not performed (conventional method).

[0016]

[Table 1]

From these results, it was found that the most effective effect was obtained when the number of repetitions was about five. On the other hand, when the number of repetitions is too large (for example, 10 times), the electrical insulation performance is deteriorated because the film-forming jig is etched and the metal powder generated by the etching is mixed into the alumina film. It is thought to be. Therefore, too many repetitions will have undesirable results.

[0018]

As described above, the present invention is a method of alternately performing a sputtering mode for performing RF bias film formation and an RF etching step a plurality of times to form an alumina film serving as a gap layer. The protrusions on the surface of the layer are flattened, so that the electrical insulation performance can be prevented from deteriorating even if the alumina film is thin. This makes it possible to cope with the narrowing of the gap of the MR thin-film magnetic head.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a sputtering film forming apparatus used in the method of the present invention.

FIG. 2 is an explanatory view of an alumina film formation state by the method of the present invention.

FIG. 3 is an explanatory view of a state of forming an alumina film by a conventional method.

FIG. 4 is an explanatory view showing an example of a main part of the MR composite thin film magnetic head.

[Explanation of symbols]

 Reference Signs List 40 alumina target 42 RF power supply 44 substrate 46 RF bias power supply 48 switch device 52 lower shield layer 52a, 52b convex portion 54 alumina film

Claims (3)

[Claims] 1. A gap layer forming method for manufacturing a thin film magnetic head having a structure in which a gap layer made of alumina separates a plurality of magnetic layers provided on a ceramic substrate, wherein the gap layer is formed by an RF bias sputtering method. In this case, a sputtering mode in which RF power is supplied to the alumina target side to perform RF sputtering film formation, and an etching mode in which RF power supply to the target side is stopped to perform RF etching are alternately repeated a plurality of times. Forming a gap layer in the thin film magnetic head by forming an alumina film to be a gap layer. 2. The method according to claim 1, wherein the sputtering mode and the etching mode are alternately repeated three to five times. 3. The method according to claim 1, wherein the gap layer to be formed is a gap layer on the read element portion side of the MR composite type thin film magnetic head.