Dynamic magnetic information storage or retrieval – Head – Coil
Reexamination Certificate
2001-04-27
2004-08-03
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Coil
C360S125330
Reexamination Certificate
active
06771463
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film coil that is incorporated in a thin-film magnetic head and so on and a method of manufacturing such a thin-film coil, and to a thin-film magnetic head incorporating a thin-film coil and a method of manufacturing such a thin-film magnetic head.
2. Description of the Related Art
Performance improvements in thin-film magnetic heads have been sought as areal recording density of hard disk drives has increased. Such thin-film magnetic heads include composite thin-film magnetic heads that have been widely used. A composite head is made of a layered structure including a write (recording) head having an induction-type electromagnetic transducer for writing and a read (reproducing) head having a magnetoresistive (that may be hereinafter called MR) element for reading.
The induction-type electromagnetic transducer of the above-mentioned thin-film magnetic head incorporates a thin-film coil. In terms of the number of layers of the coil, there are coils made up of one layer, such as the one disclosed in Published Unexamined Japanese Patent Application Showa 55-84019 (1980), coils made up of two layers, such as the one disclosed in Published Unexamined Japanese Patent Application Showa 61-255523 (1986), and coils made up of three layers or more. There are thin-film coils having a variety of designs, such as those having different numbers of turns, pitches of turns (hereinafter called a coil pitch), and coil thicknesses, in addition to the different numbers of layers.
In the prior-art coils having a plurality of layers, the layers are connected in series, regardless of the number of layers.
As areal recording density of hard disk drives has increased, an improvement in writing rate and a reduction in track width of the write head have been sought.
In order to make a thin-film magnetic head that achieves a high writing rate, the inductance of the write head is required to be reduced. To achieve this, a reduction in magnetic path length (yoke length) is required.
As the track width has been reduced, an improvement in the writing capability of the write head in a high frequency region has been required. One of the factors that determine the writing capability is the number of turns of the coil. The greater the number of turns, the higher the writing capability.
A reduction in coil pitch is required to satisfy both of the above-mentioned two requirements, that is, a reduction in inductance of the write head and an increase in the number of turns.
However, if the coil pitch is reduced while the coil thickness is kept constant, the cross-sectional area of the coil is reduced. As a result, the resistance of the coil is increased. Consequently, the coil produces heat, which results in electromigration and may cause a break in the coil.
To solve this problem, the coil pitch may be reduced and the coil thickness may be increased. Since the coil is generally formed through frame plating, the thickness of the resist frame is required to be increased, too, so as to increase the coil thickness. However, it is difficult to form a fine resist frame by patterning a thick resist layer. It is therefore difficult in prior art to form a thick coil whose coil pitch is small.
In Published Unexamined Japanese Patent Application Heisei 6-215329 (1994), a technique is disclosed for making a fine patterned conductor layer. According to this technique, a patterned resist is formed on the top surface of an insulating layer. A first etching step is then performed to etch the insulating layer downward, based on the shape of the patterned resist. A second etching step is further performed to etch at least a portion near the upper end of the sidewall of the trench portion formed through etching of the insulating layer. The second etching is performed toward sides of the portion near the upper end. An overhang portion is thereby formed at the lower edge of the patterned resist. A conductor is deposited on the overhang portion to form a conductor film. A portion of the conductor film located on the top surface of the patterned resist is lifted off. The fine patterned conductor layer is thus formed.
However, even if a coil is formed through this technique, it is difficult to greatly increase the thickness of a one-layer coil.
It is possible that a patterned thin film for a coil is formed through frame plating, and on this film another patterned thin film having the same design is formed through frame plating, so as to increase the coil thickness. However, it is difficult to form the other fine patterned thin film on the fine patterned thin film with accuracy, and it is difficult to align the two upper and lower patterned thin films.
In Published Unexamined Japanese Patent Application Showa 63-204504 (1988), a technique is disclosed for making a coil in which a plurality of patterned low-resistance films are stacked. According to this technique, a first low-resistance film, a metal protection film, and a second low-resistance film are stacked one by one on an insulating layer. The second low-resistance film is photo-etched to form a coil pattern. Side protection films are then formed on side faces of the patterned second low-resistance film. The first low-resistance film is then etched. The coil is thus formed.
However, although this technique is capable of preventing the promotion of side etching of the side faces of the patterned second low-resistance film after the side protection films are formed, it is not capable of preventing side etching itself when each of the low-resistance films is etched. Therefore, it is difficult to greatly reduce the coil dimensions through this technique.
OBJECTS AND SUMMARY OF THE INVENTION
It is a first object of the invention to provide a thin-film coil that has a small coil pitch and a large cross-sectional area and that is easily fabricated, and a method of manufacturing such a thin-film coil.
It is a second object of the invention to provide a thin-film magnetic head incorporating a thin-film coil that has a small coil pitch and a large cross-sectional area and that is easily fabricated, and a method of manufacturing such a thin-film magnetic head.
A first thin-film coil of the invention comprises: a first patterned conductor layer and a second patterned conductor layer that are coil-shaped and stacked; an insulating layer located between the first and second patterned conductor layers; a first connecting portion connecting one of ends of the first patterned conductor layer to one of ends of the second patterned conductor layer; and a second connecting portion connecting the other of the ends of the first patterned conductor layer to the other of the ends of the second patterned conductor layer.
A first method of manufacturing a thin-film coil of the invention comprises the steps of: forming a coil-shaped first patterned conductor layer; forming an insulating layer on the first patterned conductor layer; and forming a coil-shaped second patterned conductor layer on the insulating layer, and connecting one of ends of the first patterned conductor layer to one of ends of the second patterned conductor layer, and connecting the other of the ends of the first patterned conductor layer to the other of the ends of the second patterned conductor layer.
According to the first thin-film coil or the method of manufacturing the same of the invention, the insulating layer is located between the first and second patterned conductor layers. The first connecting portion connects one of the ends of the first patterned conductor layer to one of the ends of the second patterned conductor layer. The second connecting portion connects the other of the ends of the first patterned conductor layer to the other of the ends of the second patterned conductor layer. Therefore, the first and second patterned conductor layers are connected in parallel.
According to the first method of manufacturing the thin-film coil of the invention, the first and second patterned conductor layers may be formed through frame plating.
Miller Brian E.
TDK Corporation
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