Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-03-31
2001-03-13
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603140, C029S603120, C029S603160, C029S603180, C430S320000, C216S022000, C216S066000, C204S192340
Reexamination Certificate
active
06199267
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a magnetic head and a method for the production thereof. More particularly, this invention relates to a magnetic head for use in a magnetic disk drive or a magnetic tape drive and a method for the production thereof.
2. Field of the Invention
The magnetic disk drive or the magnetic tape drive has come to be improved markedly in track density in consequence of the increase in the device's recording is density and, therefore, is in need of a magnetic head which features a narrow core width and suffers only sparing recording obscurity. Particularly when the MR head (magnetoresistive head) which has been finding growing acceptance is to be used, since shared use of a magnetic layer of a large width destined to form a magnetic shield for the MR head as one of the two recording magnetic poles opposed to each other across a recording write gap layer is popular and also is liable to aggravate recording obscurity, it is preferred to adopt a magnetic head which suffers only sparing recording obscurity and enjoys a perfect off-track characteristic.
It is known that equalization of the upper and lower recording magnetic poles in width is effective in realizing such a magnetic head featuring a narrow core width and suffering only sparing recording obscurity as mentioned above. Various methods have been proposed for the production of magnetic heads of this description.
An example of trimming a magnetic pole from the air bearing surface (ABS), i.e. the face opposite a magnetic medium, side with a focused ion beam (FIB) will be cited. The magnetic head disclosed in JP-A-03-296,907, for example, is claimed to be a magnetic head of a perfect off-track characteristic which is obtained by trimming the upper and lower magnetic poles with the FIB from the air bearing surface (ABS) side of the magnetic head:
Specifically, after a slider
101
possessed of a rail face (air bearing surface (ABS))
102
is formed as illustrated in
FIG. 1A
, the lateral part of an upper magnetic pole
104
of a magnetic head
103
formed on the slider
101
is trimmed by exposure to a focused ion beam and, at the same time, the upper layer part of a lower magnetic pole
105
is simultaneously trimmed to equalize the lower magnetic pole
105
and the upper electrode
104
in width as illustrated in
FIGS. 1B and 1C
.
Besides this method, the method which comprises forming the upper magnetic pole and subsequently trimming the lower magnetic pole as by ion milling with the upper magnetic pole itself as an etching mask during the course of a wafer process has been known. Since this method avoids adjusting the width of the upper magnetic pole by the trimming, the accuracy of the width of the upper magnetic pole depends on the accuracy of a plating pattern to be used for the formation of the upper magnetic pole.
The method which effects the trimming of the upper magnetic pole
104
and the lower magnetic pole
105
as illustrated in
FIGS. 1A-1C
, however, entails the following problems.
First, since the exposure to the focused ion beam is carried out after a given wafer has been cut into blocks and the rail face
102
has been formed on such a block, the handling of the substrate and the location of the focused ion beam are complicated. Further, this method is highly problematic in terms of reliability because depressions
106
formed in the rail face
102
as illustrated in
FIG. 1C
are fated to collect dust and lubricant therein when the rail face
102
contacts the face of the recording medium in the contact start and stop (CSS) area.
JP-A-03-296,907 (KOKAI) teaches to cope with this problem by filling the depressions with a nonmagnetic material. The work of filling the depressions itself is very difficult because the substrate on which the rail face is fabricated is no longer a wafer but a small block.
Further, the edges of the depressions which are formed by the focused ion beam are liable to form R's, approximately 0.1-0.2 &mgr;m in size. This size of the R's does not deserve to be ignored when the core width approximates closely to 1 &mgr;m.
Moreover, since the FIB electrically charges the rail face
102
being fabricated unless this face completely undergoes a treatment for electric neutralization, it inevitably breaks the MR element which is vulnerable to static electricity.
The method which consists in coping with this problem by subjecting the magnetic shield layer to ion milling with the upper magnetic pole as an etching mask during the course of wafer process has been known. Though this method allows easy handling of the substrate which has the unit size of a wafer, it is still at a disadvantage in inevitably etching parts other than the magnetic pole, suffering the redeposited film of the etched part to adhere to the lateral face of the magnetic pole, and rendering it difficult to improve the accuracy of core width.
SUMMARY OF THE INVENTION
This invention has for an object thereof the provision of a magnetic head which inhibits formation of any depression in the side opposed to a magnetic recording medium, withstands static charging strongly, and allows exaltation of the accuracy of the width of a magnetic pole and a method for the production thereof.
The present invention contemplates forming an upper magnetic pole on a wafer, then projecting a focused ion beam in the direction of thickness of film thereby trimming the opposite lateral parts of the pole tip of the upper magnetic pole and, at the same time, forming depressed parts in the upper layer of a lower magnetic pole directly underlying the upper magnetic pole, and filling the depressed parts with a nonmagnetic protective layer.
When the wafer is divided so as to expose the leading end of the pole tip, therefore, the leading end of the pole tip and the vicinity thereof, namely the face of the magnetic head opposed to the magnetic recording medium, cannot suffer the occurrence of a depressed part. The face opposed to the magnetic recording medium does not allow easy adhesion of dust.
Since the upper magnetic poles and the lower magnetic poles still in the form of a wafer are simultaneously exposed to the focussed ion beam, at least one of the lower magnetic pole, the upper magnetic pole, and the plating conducting film on the wafer can be easily grounded. By this grounding, the magnetoresistive element, if existing under the lower magnetic pole, can be precluded from electrostatic breakdown.
Further, since the focussed ion beam is moved to the lateral part of the pole tip from outside, the material of the magnetic pole scattered by the impingement of the focussed ion beam does not easily adhere to the lateral part of the pole tip and, therefore, cannot degrade the accuracy of the width of the pole tip.
When the surface of the lower electrode directly underlying the pole tip of the upper magnetic pole is covered with a layer of a higher saturated magnetic flux density or higher resistance than in the other area, it is enabled to inhibit a change in signal due to magnetic saturation of the lower magnetic pole or prevent deterioration of the frequency characteristic due to eddy current.
When the area of the upper face of the lower magnetic pole which is opposed to the upper magnetic pole and the vicinity thereof are raised for the purpose of leveling the depressed part possibly formed in the lower magnetic pole in consequence of the exposure to the focussed ion beam, the possibility of the depressed part gaining the greatest depth in the part approximating most closely to the pole tip can be prevented. When a depressed part is preparatorily formed in the side area of the lower magnetic pole which is separated from the pole tip of the upper magnetic pole, this depressed part can be given an increased depth at the center and the possibility of the depressed part assuming the greatest depth in the area approximating most closely to the pole tip can be precluded.
REFERENCES:
patent: 4436593 (1984-03-01), Osborne et al.
patent: 4936968 (1990-06-01), Ohnishi et al.
Koshikawa Takao
Nagai Atsuhiko
Fujitsu Limited
Greer Burns & Crain Ltd.
Tugbang A. Dexter
Young Lee
LandOfFree
Method for the production of a magnetic head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for the production of a magnetic head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for the production of a magnetic head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2495271