Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Coating selected area
Reexamination Certificate
2001-04-06
2003-12-16
McDonald, Rodney G. (Department: 1753)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Coating selected area
C205S118000, C204S192150, C430S312000, C430S313000, C430S135000, C430S325000, C438S780000, C427S098300, C427S123000, C427S124000
Reexamination Certificate
active
06663761
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming a fine pattern in which a pattern interval of a resist pattern or a hole diameter is narrowed, and a developing/washing device used for the same, and further, to a plating method (hereinafter referred to as a frame plating method) for forming a plating film by using a mold formed by patterning a resist, and a manufacturing method of a thin film magnetic head provided with an induction type magnetic head as a recording head.
2. Description of the Related Art
A composite type thin film magnetic head including a magnetoresistive (MR) head used for data reproduction and an induction type magnetic head used for data recording is used as a magnetic head of a magnetic disk device.
The MR head includes any one of an AMR (Anisotropic Magnetoresistive) component using an AMR effect, a GMR (Giant Magnetoresistive) component using a GMR effect, and a TMR (Tunneling Magnetoresistive) component using a tunnel junction film indicating a magnetoresistive effect. As the surface recording density of a magnetic recording medium becomes high, a component to be used is changed from the AMR component to the GMR component, and further, to the TMR component.
As one factor for determining the performance of the MR heads, there is optimization of MR height. The MR height is a height of the MR component from an end portion at a side of an air bearing surface (ABS) opposite to a magnetic recording surface of a magnetic recording medium to an end portion at the opposite side, and this height depends on an amount of polishing of the ABS surface in a head manufacturing process.
The induction type magnetic head realizes a ring structure having a narrow gap by a semiconductor process, and includes upper and lower magnetic poles which are laminated through an insulating film and has a gap (write gap) at the side of the ABS surface to form a closed magnetic path, and a thin film coil formed in the insulating film between the upper and lower magnetic poles. A head material is magnetized to high magnetic flux density by a recording current flowing through the thin film coil, and predetermined leakage magnetic field is formed over the gap to record data on the magnetic recording medium.
As one factor for determining the performance of the induction type magnetic head, there is optimization of throat height (TH). The throat height is a height of the magnetic pole from the ABS surface to the end portion of the insulating film, and this height also depends on an amount of polishing of the ABS surface in the head manufacturing process. In order to improve the head efficiency of the recording head, it is necessary to make the throat height as small as possible.
In order to raise the recording density, it is necessary to raise the track density of the magnetic recording medium. For that purpose, it is necessary to realize a recording head in which a magnetic pole width and a gap width at the ABS surface are made narrow, and a semiconductor processing technique is used for realizing this.
The foregoing composite type thin film magnetic head is manufactured through a plurality of manufacturing processes, for example, a sputtering process, a photolithography process, a frame plating process, an etching process, a polishing process, and the like. Herein after,an example of a manufacturing method of the thin film magnetic head will be described in brief.
First, an Al
2
O
3
TiC substrate having high hardness and excellent in wear resistance is used. When the magnetic head is completed, this substrate itself functions as a slider body of the magnetic head. The reason why the substrate having high hardness and excellent in wear resistance is used is to secure floating accuracy of the head and to obtain accurate MR height and throat height.
A film having high adhesiveness, for example, a chromium film is formed on the Al
2
O
3
TiC substrate by sputtering or the like. Next, a lower shield layer made of, for example, Permalloy is formed. Next, an MR component interposed between insulating films is formed on the lower shield layer.
Next, an upper shield layer made of Permalloy or the like is formed. By this, an MR head for reproduction is completed. The upper shield layer is also used as a lower magnetic pole of an induction type magnetic head for recording.
Next, an insulating film for formation of a gap is formed on the lower magnetic pole, and further, an insulating film is formed, and then, a film excellent in adhesiveness to an oxide, for example, a chromium film is formed thereon by sputtering or the like. Next, there is formed a thin film of, for example, copper, which becomes an electrode film when a frame plating method is used. Next, a copper coil of a first layer is formed by the frame plating method. As the need arises, coils of second to third layers are also formed in the same way.
After the formed thin film coil is embedded by an insulating film, an upper magnetic pole made of, for example, permalloy is formed thereon by using the frame plating method. A recording gap layer is formed by carrying out etching, while the upper magnetic pole at the side of the ABS surface is used as a mask. The upper magnetic pole is formed so that it is connected to the lower magnetic pole through the coil at the opposite side of the recording gap layer so as to constitute a closed magnetic path. A protective film is formed on an upper layer of the upper magnetic pole, and the film forming process is completed.
Next, the Al
2
O
3
TiC substrate is cut into rod-like substrates including several tens heads. The ABS formation surface of the rod-like substrate is polished to provide the throat height of a height of several &mgr;m. After the ABS surface is formed, the rod-like substrate is cut, so that a plurality of thin film magnetic heads are completed. In the manufacturing method of the thin film magnetic head as described above, the frame plating method is used for the formation of the thin film coil or the formation of the upper magnetic pole.
A conventional frame plating method will be described in brief with reference to
FIGS. 9A
to
9
E. The frame plating method is a method of patterning a plating film by using a mold formed by patterning a resist, as disclosed in, for example, Japanese Patent Publication No. S56-36706.
FIGS. 9A
to
9
E are sectional views showing a manufacturing process of a plating film using the conventional frame plating method. As shown in
FIG. 9A
, an electrode film
502
is formed on an insulating substrate
500
by using a sputtering method or an evaporation method. At a lower layer of the electrode film
502
, an adhesive layer, for example, a Cr (chromium) film or a Ti (titanium) film, may be formed to raise the adhesiveness to the insulating substrate
500
. Although there is no problem when the electrode film
502
is made of a material having conductivity, if possible, it is desirable to use the same material as a metal material to be plated.
Next, as shown in
FIG. 9B
, a resist is coated on the whole surface to form a resist layer
504
, and as the need arises, a prebake treatment of the resist layer
504
is performed. Next, exposure light is irradiated through a mask
506
on which a predetermined pattern is drawn, so that the resist layer
504
is exposed.
Next, as the need arises, a heat treatment is performed, and then, development is carried out by an alkaline developing solution. As the alkaline developing solution, for example, tetramethylammonium hydroxide (TMAH) of a concentration of 2.38 wt % is used. Next, the developing solution in the resist layer
504
is washed by a washing solution, and a development dissolving reaction in the resist layer
504
is stopped, so that resist frames
508
patterned into a predetermined shape are formed (see FIG.
9
C).
Next, the substrate
500
is immersed in a plating solution
512
in a plating bath, and a plating process is carried out using the resist frames
508
as a mold, so that plating films
514
are formed between the resist frames
50
McDonald Rodney G.
Oliff & Berridg,e PLC
TDK Corporation
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