Dynamic magnetic information storage or retrieval – Head – Coil
Reexamination Certificate
2000-03-27
2003-02-25
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Coil
C360S125330, C360S317000
Reexamination Certificate
active
06525901
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates to a thin film magnetic head including a slider and a thin film magnetic head element and a method for manufacturing the same.
2) Related Art Statement
In manufacturing of a thin film magnetic head, normally, a first magnetic film (bottom magnetic film), a gap film and a thin film coil separated and supported by an insulating film are formed, and thereafter, a second magnetic film to constitute a top magnetic film is formed. The thin film coil is formed in a constant thickness so as to wind around the backward joining portion (back gap)to join the first magnetic film and the second magnetic film.
In the formation of the second magnetic film, a plate underfilm for the second magnetic film is formed entirely on a wafer including the insulating film by sputtering, etc. Then, a photoresist is applied on the plate underfilm and processed by a photolithography process to form a resistframe having the desired pattern for the second magnetic film. Subsequently, the second magnetic film is formed by electroplating, etc., in the area enclosed by the resistframe.
One of the problems in the manufacturing process of the second magnetic head is that in the photolithography process to form the resistframe, a part of an exposing light is reflected at the insulating film, reaches the area beyond a photomask, and exposes the part of the photoresist except to be defined by the photomask, resulting in the degradation of the pattern precision in the resistframe and the second magnetic film.
The degradation of the pattern precision appears at its pole portion conspicuously. In the pole portion, the second magnetic film is opposed to the first magnetic film via the gap film. The insulating film is located backward from the pole portion, and rises up at a given angle on the gap film with inclination. The start point of the rising up corresponds to a Throat Height zero point and the angle of the rising up corresponds to an Apex Angle.
The part of the second magnetic film up to the Throat Height zero point constitutes the pole portion parallel to the gap film and the first magnetic film, and the remainder is inclined at the Apex Angle toward the upper surface of the insulating film from the Throat Height zero point. Therefore, in forming the resistframe for the second magnetic film by the photolithography, the part of the photoresist stuck on the inclined portion of the insulating film which is inclined at the Apex Angle toward the upper surface of the insulating film from the Throat Height zero point has to be exposed. In this case, since the plate underfilm is stuck on the inclined portion, the exposing light is reflected at the plate underfilm, and then, the part of the exposing light leaves for the pole portion. Accordingly, the exposed pattern of the pole portion differs from the exposing pattern of the photomask, resulting in the pattern deformation of the resistframe.
The pattern deformation is large obstacle for realizing a high density recording through narrowing a recording track width up to 1.0 &mgr;m and below.
Kokai publication No. 9-180127 (JP A 9-180127) discloses the technique that before applying a photoresist to constitute a mask for a top magnetic film, an antireflection film is formed, and the photoresist is applied on the antireflection film, exposed and developed, to form a resistframe as a mask for a second magnetic film. After forming the resist frame, the part of the antireflection film exposing to the bottom surface of the opening in the resist frame is removed by an ashing means, etc. and the second magnetic film is formed by plating, etc.
In the above conventional technique, the antireflection film exists entirely within the inner pattern enclosed by the resistframe. The inner pattern of the resistframe has a pole portion area corresponding to the pole portion of the top magnetic film and a second yoke portion corresponding to a yoke portion. The part of the antireflection film in the pole portion area and the second yoke portion area has to be removed.
However, the resistframe has extremely different opening areas for the pole portion area and the second yoke portion. Furthermore, for realizing a high density recording, the opening area of the pole portion is required to be narrowed up to a minute size of 1 &mgr;m and below. Consequently, in removing the part of the antireflection film stuck on the inner pattern enclosed by the resistframe, the second yoke portion area has a different etching rate from that of the pole portion area, and the pole portion area requires longer etching time than the second yoke portion. As a result, during the removing of the antireflection film, the resistframe is over-etched to have its too enlarged frame distance. That is, the antireflection which is formed to narrow its pole width enlarges the resistframe distance because it requires the above removing process, which is obstacle for narrowing of the pole width.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thin film magnetic head having a narrowed recording track width by forming a top magnetic film, particularly its pole portion on an insulating film in a precise pattern without the increase of the electric resistance of a thin film coil entirely.
It is another object of the present invention to provide a method for manufacturing the above thin film magnetic head effectively and precisely.
This invention relates to a thin film magnetic head comprising a slider having an air bearing surface opposing to a magnetic recording medium and an inductive type thin film magnetic head element, provided on the end face of the slider in air outflow side, including a first magnetic film, a second magnetic film, a gap film, and thin film coils,
the first magnetic film having a first pole portion of which forefront is exposed to the air bearing surface and a first yoke portion which extends backward from the air bearing surface,
the second magnetic film having a second pole portion which is opposed to the first pole portion of the first magnetic film and of which forefront is exposed to the air bearing surface and a second yoke portion which extends backward from the air bearing surface and magnetically joined with the first yoke portion of the first magnetic film at a back gap portion,
the gap film being provided at least between the first pole portion of the first magnetic film and the second pole portion of the second magnetic film,
the thin film coils winding around the back gap portion so as to pass through the magnetic circuit enclosed by the first and second magnetic films and being supported by insulating films, wherein
the insulating films to support the thin film coils is provided in between the first and the second yoke portions, and the top thin film coil of the thin film coils has a coil winding body portion with a smaller thickness nearest the air bearing surface than that of a coil winding body portion at the middle between the first and second pole portions and the back gap portion.
In the thin film magnetic head, since the top thin film coil has a coil winding body portion with smaller thickness nearest the air bearing surface than the middle coil winding body portion between the pole portion and the backward joining portion to constitute the back gap portion, the top insulating film may have the thickness distribution that it is thinnest nearest the air bearing surface and thicker at the middle between the pole portion and the backward joining portion. Therefore, the top insulating film to cover the second magnetic head can have a gentle rising inclination angle, and then, the exposed pattern of the photoresist to define the pattern of the resistframe corresponding to the second pole portion can be almost determined by the exposing pattern of the photomask. As a result, the pattern of the resistframe corresponding to the second pole portion can be formed precisely, and thus, the second pole portion can be formed so as to have a precise pattern. Moreover, since the pattern of the
Hokushin Jun-ichi
Kamijima Akifumi
Miller Brian E.
Nguyen Dzung C
Oliff & Berridg,e PLC
TDK Corporation
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