Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1998-09-09
2001-02-13
Letscher, George J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Core
C360S317000
Reexamination Certificate
active
06188544
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thin-film magnetic head provided with at least an inductive recording transducer element and to a method of manufacturing the head.
DESCRIPTION OF THE RELATED ART
FIG. 1
is a cross-sectional view perpendicular to the plane of the air bearing surface (ABS), illustrating an example of a conventional composite type thin-film magnetic head with an inductive recording head part and a magnetoresistive (MR) reproducing head part.
In the figure, the reference numeral
10
denotes a lower shield layer of the MR reproducing head part,
11
denotes an upper shield layer of the MR head part, which also acts as a lower pole of an inductive recording head part,
12
denotes a MR layer provided through an insulating layer
13
between the lower shield layer
10
and the upper shield layer
11
,
14
denotes a recording gap layer of the recording head part,
15
denotes an upper pole,
16
denotes a lower insulating layer deposited on the recording gap layer
14
,
18
denotes a coil conductor formed on the lower insulating layer
16
, and
17
denote an upper insulating layer deposited so as to cover the coil conductor
18
. The upper pole
15
is magnetically connected with the lower pole (upper shield layer)
11
at its rear portion so as to constitute a magnetic yoke together with the lower pole
11
.
As apparent from the figure, since the recording gap layer
14
of the conventional thin-film magnetic head is formed even under the coil conductor for generating a recording magnetic field, it is necessary to use materials having a high thermal conductivity. Thus, as the material of the recording gap layer
14
, aluminum oxide (Al
2
O
3
) with comparatively high thermal conductivity has typically been used.
Recently, demand for higher recording density has made a recording track width narrower, and therefore a submicron width of the pole of the recording head part has been needed. To cope with such narrower pole width, a thin-film magnetic head is formed in a manner that only the recording pole portion is separated from other portions. That is, a three-layer pole structure with a lower pole tip element, a recording gap layer and an upper pole tip element is formed at only a pole tip region located between the ABS and a position at a predetermined height from the ABS in the recording head part, and an upper yoke and a lower yoke are magnetically connected to the top surface and the bottom surface of this pole tip structure, respectively.
FIGS. 2 and 3
illustrate an example of a conventional composite type thin-film magnetic head having such a three-layer pole tip structure.
FIG. 2
is a cross-sectional view perpendicular to the plane of the ABS, and
FIG. 3
is a schematic ABS view. In these figures, the reference numeral
20
denotes a lower shield layer of the MR reproducing head part,
21
denotes an upper shield layer of the MR head part, which also acts as a lower auxiliary pole of an inductive recording head part,
22
denotes a MR layer provided through an insulating layer
23
between the lower shield layer
20
and the upper shield layer
21
,
24
denotes a lower pole tip element of the inductive recording head part,
25
denotes an upper pole tip element,
26
denotes a recording gap layer formed between the lower pole tip element
24
and the upper pole tip element
25
,
27
denotes a lower insulating layer deposited on the upper shield layer
21
and around a three-layer pole structure consisting of the lower pole tip element
24
, the recording gap layer
26
and the upper pole tip element
25
,
28
denotes a coil conductor formed on the lower insulating layer
27
,
29
denotes an upper insulating layer deposited so as to cover the coil conductor
28
, and
30
denotes an upper auxiliary pole formed on the upper insulating layer
29
and deposited to contact with the upper pole tip element
25
. The upper auxiliary pole
30
is magnetically connected with the lower auxiliary pole (upper shield layer)
21
at its rear portion so as to constitute a magnetic yoke together with the lower auxiliary pole
21
.
In manufacturing the above-mentioned thin-film magnetic head in which only the recording pole portion is separated from other portions, when three-layer pole structure consisting of the lower pole tip element
24
, the recording gap layer
26
and the upper pole tip element
25
is formed by a dry etching process such as ion milling, conventional use of Al
2
O
3
as a material of the recording gap layer causes its shape control to become difficult. That is, since Al
2
O
3
has a lower etching rate than that of magnetic materials used for the lower and upper pole tip elements
24
and
25
of the three-layer pole structure, shape control, such as formation of the side surface of the three-layer pole structure to make perpendicular to the top surface of the upper shield layer
21
is very difficult. In other words, when the three-layer pole structure is patterned by a dry etching process, the side surface of the Al
2
O
3
gap layer
26
is not easily etched due to the lower etching rate of Al
2
O
3
than that of the magnetic material of the upper pole
25
. Thus, the side surfaces of the patterned recording gap layer
26
incline with respect to that of the upper pole layer as shown in FIG.
3
. In addition, the side surfaces of the lower pole layer
24
below the recording gap layer
26
also incline as well as the recording gap layer
26
, thereby generating problems such as increase of recording track width and side fringing.
In order to enhance the etching rate of Al
2
O
3
, use of a reactive ion etching (RIE) may be considered. However, when the three-layer pole structure mentioned above is etched, not only etching gas must be changed for every layer, but also an etching device should be formed so as to correspond to the etching gas for Al
2
O
3
such as chlorine series. Additionally, a countermeasure for corrosion should be also considered.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a thin-film magnetic head and a method of manufacturing the same, whereby a little side fringing and stable recording properties can be realized even in a narrower track.
According to the present invention, a thin-film magnetic head includes an ABS and a three-layer pole tip structure located between the ABS and a position at a predetermined height from the ABS. The structure consists of a first pole, a recording gap layer and a second pole. The recording gap layer is made of a material having a etching rate equal to or higher than that of a material for making the first and second poles.
According to the present invention, furthermore, a thin-film magnetic head has a MR reproducing head part, an inductive recording head part multilayered with the reproducing head part, and an ABS. The recording head part includes a three-layer pole tip structure located between the ABS and a position at a predetermined height from the ABS. The structure consists of a first pole, a recording gap layer and a second pole. The recording gap layer is made of a material having a etching rate equal to or higher than that of a material for making the first and second poles.
Also, according to the present invention, a method of manufacturing a thin-film magnetic head includes a step of sequentially depositing a first magnetic layer, a non-magnetic layer and a second magnetic layer, and a step of forming a three-layer pole tip structure located between an ABS and a position at a predetermined height from the ABS by dry etching the first magnetic layer, the non-magnetic layer and the second magnetic layer. The non-magnetic layer is made of a material having an etching rate equal to or higher than that of a material for making the first and second magnetic layers.
The first and second pole tip elements may correspond to a lower pole tip element and an upper pole tip element, respectively, or correspond to an upper pole tip element and a lower pole tip element respectively, depending upon the layered order of each la
Arent Fox Kintner & Plotkin & Kahn, PLLC
Letscher George J.
TDK Corporation
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