Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-06-26
2004-01-20
Chang, Richard (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603140
Reexamination Certificate
active
06678941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for manufacturing a thin film magnetic head usable for a magnetic recording and reproducing drive device such as a magnetic disk drive device.
2. Related Art Statement
For realizing a high recording density in a magnetic disk using a thin film magnetic head, it is required that data amount (data density) to be restored in the unit area of the magnetic disk is enhanced. The surface recording density depends on performance of a recording element, and can be enhanced by shortening the gap length between the recording poles of the recording element.
The surface recording density can be also enhanced by increasing the track number to be recorded in the magnetic disk. The track number recordable in the magnetic disk is normally represented as “TPI (track per inch)”. The TPI performance of the recording element can be enhanced by downsizing the recording head to determine the width of the data track. The size of the recording head is normally known as a track width.
However, the shortening of the gap length between the recording poles and the narrowing of the track width decrease the magnetic flux in between the recording poles, resulting in the degradation of the overwrite performance. Therefore, in view of recording performance, the shortening of the gap length and the narrowing of the track width can not employed for a high density recording magnetic disk having a high coercivity Hc.
To solve this problem, the recording pole structure in which in a recording pole portion, a magnetic film having a high saturated magnetic flux density (a first magnetic film) is provided adjacent to a gap film and a second magnetic film having a smaller saturated magnetic flux density than the first magnetic film is provided on the first magnetic film is suggested and practically used. For example, the specification of U.S. Pat. No. 5,606,478 discloses that the part of the recording pole portion adjacent to the gap film is made of a magnetic material having a higher saturated magnetic flux, for example Ni
55
Fe
45
, than the magnetic material having a NiFe composition which is usually used for the pole portion of the above thin film magnetic head. However, the Ni
55
Fe
45
material has only 1.4T to 1.5T, so that the recording performance is restricted.
In addition, the specification of Kokai Publication Kokai Hei 5-73839 (JP A 5-73839) discloses that an underfilm to plate a bottom magnetic core and a top magnetic core is made of a magnetic material having a higher saturated magnetic flux density than the magnetic materials constituting the bottom magnetic core and the top magnetic core.
In defining the track width of the recording pole portion using the above means in those related documents, the underfilm made of the magnetic film having the higher saturated magnetic flux density has to be etched by milling, etc. In the etching process, the part of the magnetic material constituting the underfilm is re-stuck on the side surfaces, etc. of the pole portion, resulting in the increase of the track width. This means the opposite result to the narrowing of the track width. Moreover, the re-stuck portion of the pole portion usually has inferior magnetic characteristics, so that the electromagnetic conversion characteristics of the pole portion is deteriorated.
If the underfilm is thinner, the re-sticking can be reduced. However, the thinner underfilm can not realize the essential object of enhancing the recording performance by making the underfilm of the magnetic material having a high saturated magnetic flux density. The above related documents do not disclose the means for solving the above problems due to the re-sticking.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for manufacturing a thin film magnetic head in which the re-sticking is almost never brought about if a magnetic film, provided adjacent to a write gap film, having a high saturated magnetic flux density is thicker.
It is another object of the present invention to provide a method for manufacturing a thin film magnetic head having a recording pole structure of high recording performance.
For accomplishing the objects, this invention is directed to a method for manufacturing a thin film magnetic head including a recording pole portion. The recording pole portion includes a first pole portion, a gap film adjacent to the first pole portion and a second pole portion adjacent to the gap film. The second pole portion has a first magnetic film and a second magnetic film. The first magnetic film has a higher saturated magnetic flux density than the second magnetic film and is provided adjacent to the gap film, and the second magnetic film is provided adjacent to the first magnetic film.
In manufacturing the above thin film magnetic head, the manufacturing method of the present invention has the steps of forming, on the gap film, the first magnetic film in a primary pattern after forming the first pole portion and the gap film and of forming the second magnetic film by a frame-plating method.
In the above steps, the primary pattern is formed so that its size can be larger than the definitive pattern of the first magnetic film and its edges can be located within frames to be used in the frame-plating method.
According to the manufacturing method, the etching of the first magnetic film in the definitive pattern by dry-etching such as RIE or milling using the second magnetic film as a mask can remove the re-stuck magnetic material of the first magnetic film from the both side surfaces of the first and second magnetic films in the track direction. After the first magnetic film is etched in the definitive pattern, the re-sticking does not occur. Consequently, even if the first magnetic film having a high saturated magnetic flux density is thicker, the re-sticking almost never occur.
Moreover, this invention discloses two modes of the manufacturing method concretely.
First Mode-Manufacturing Method
The first mode-manufacturing method includes the following steps.
First of all, a magnetic film to be the first magnetic film is formed on the gap film. Then, a mask having a pattern larger than the definitive pattern of the first magnetic film is formed on the magnetic film. The part of the magnetic film uncovered with the mask is removed to form the first magnetic film having the primary pattern.
Subsequently, an plate underfilm is formed on the first magnetic film having the primary pattern and the gap film. Then, frames for frame-plating the second magnetic film is formed on the plate underfilm. The frames are separated on the first magnetic film in the parallel track direction thereto and cover the both edges of the first magnetic film and the gap film around the both edges in the track direction.
Subsequently, a plate film to be the second magnetic film is stuck on the part of the plate underfilm uncovered with the frame, and thereafter, the frame is removed.
Next, the part of the plate underfilm which is exposed followed by the removing of the frame is removed. Since the plate underfilm is extremely thin, the material constituting the plate underfilm is not stuck on the both side surfaces of the first and second magnetic films in the track direction even if the plate underfilm is removed by dry-etching such as milling or reactive ion etching (hereinafter, abbreviated to “RIE”). Moreover, since the first magnetic film is patterned to have the primary pattern, in removing the plate underfilm, only the plate underfilm has to be etched and the first magnetic film dose not have to. Therefore, the above conventional problems due to the re-sticking of magnetic material constituting the first magnetic film can be prevented.
Furthermore, although the second magnetic film is exposed to the dry-etching in the above removing process of the plate underfilm by the dry-etching, the extremely thin plate underfilm can repress the reduction of the second magnetic film to the utmost. Therefore, the thin film magnetic head having the recording p
Ito Noriyuki
Kanakubo Katsuya
Mino Tetsuya
Terunuma Koichi
Chang Richard
Oliff & Berridg,e PLC
TDK Corporation
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