Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-12-19
2003-01-21
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S320000
Reexamination Certificate
active
06510029
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thin film magnetic head, in which magnetic resistance (MR) element sections are formed on an insulating layer formed on a surface of a magnetizable metal substrate, and a method of manufacturing the thin film magnetic head.
Thin film magnetic heads for reproducing data, each of which includes magnetic resistance element sections for reproducing data, which are formed on an insulating layer formed on a surface of a magnetizable substrate, are assembled in magnetic tape memory devices.
A conventional thin film magnetic head, which is a separate type magnetic head assembled in a magnetic tape memory device, is shown in FIG.
6
.
FIG. 6
is an explanation view showing a summarized structure of the head. The separate type magnetic head has a magnetic resistance element section
10
for reproducing data (hereinafter referred to as “reproducing head section”) and a magnetic resistance element section
12
for writing data (hereinafter referred to as “writing head section”), which are arranged side by side, on a surface of a magnetizable substrate
14
(e.g., Ni—Zn-Ferrite substrate) for shielding a lower part, with a proper separation. In
FIG. 6
, one reproducing head section
10
and one writing head section
12
are shown, but many reproducing head sections
10
and many writing head sections
12
are formed on the magnetizable substrate
14
of the actual magnetic head.
Firstly, the reproducing head section
10
will be explained.
The head sections
10
and
12
are formed on the magnetizable substrate
14
, and the substrate
14
acts as a lower shielding layer of the reproducing head section
10
.
A first insulating layer
16
, which is made of a non-magnetizable GAP material (e.g., alumina), is formed on the surface of the magnetizable substrate
14
. The first insulating layer
16
acts as a half-GAP.
An MR element section
18
(e.g., SAL/Ta/MR type) is formed on a surface of the first insulating layer
16
.
A pair of Co—Cr—Pt/MR terminals
20
(hereinafter referred to as “MR terminals”) are respectively provided on both sides of the MR element section
18
.
A second insulating layer
22
, which is made of a non-magnetizable GAP material (e.g., alumina), is formed on the surface of the first insulating layer
16
so as to cover over the MR element section
18
and the MR terminals
20
.
Namely, the MR element section
18
and the MR terminals
20
are sandwiched between the two insulating layers
16
and
22
. The second insulating layer
22
acts as an insulating film of an upper shielding layer
24
and the half-GAP.
An upper shielding layer
24
, which is made of a soft magnetic metal film, is formed on a surface of the second insulating layer
22
.
A protection layer
26
is formed on a surface of the upper shielding layer
24
.
Next, the writing head section
12
will be explained.
The magnetizable substrate
14
supplements a lower magnetic pole
28
.
The lower magnetic pole
28
, which is a soft magnetic metal film, is formed on the surface of the magnetizable substrate
14
.
A write-GAP
30
is made of a non-magnetizable GAP material (e.g., alumina).
An upper magnetic pole
32
, which is a soft magnetic metal film, is formed on a surface of the write-GAP
30
.
The protection layer
26
is formed on a surface of the upper magnetic pole
32
.
The Ni—Zn-Ferrite substrate is employed as the magnetizable substrate
14
, on which the reproducing head section
10
and the writing head section
12
are formed, by following reasons.
Firstly, the Ni—Zn-Ferrite material is a stable oxide which has superior magnetic property (e.g., greater specific resistance) and superior high frequency property. Secondly, the Ni—Zn-Ferrite material has greater hardness, so it is a proper material to contact a magnetic tape, which is pressed there onto with high contact pressure. Namely, the Ni—Zn-Ferrite material has superior tape-touch property and tape-slide property. Thirdly, the Ni—Zn-Ferrite material has high reliability and superior records of employment. Besides the head of the magnetic tape memory device, magnetic heads employing the Ni—Zn-Ferrite substrates have been assembled in heads for flexible memory media (e.g., VTR tapes, flexible disks).
However, the Ni—Zn-Ferrite substrate has following disadvantages.
These days, required memory density of the magnetic tape memory is higher and higher, so that the first insulating layer
16
and the second insulating layer
22
of the reproducing head section
10
must be thinner.
But the Ni—Zn-Ferrite material is a sintered material, so a large number of fine holes
34
(see
FIG. 7
) are formed therein. With this structure, the fine holes
34
are opened in the surface of the magnetizable substrate
14
when the surface of the magnetizable substrate
14
is abraded. In
FIG. 7
, the fine hole
34
is opened in the surface of the magnetizable substrate
14
. The fine hole
34
is a hollow hole and formed by a HIP manner. A maximum diameter of the fine hole
34
is about 5 &mgr;m.
If the first insulating layer
16
, the MR element section
18
and the second insulating layer
22
are directly formed on the surface of the magnetizable substrate
14
, in which the fine holes
24
are opened, by sputtering, the films
16
,
18
and
22
fall into the fine holes
34
. Therefore, the films
16
,
18
and
22
are partially depressed, so that thickness of the films
16
,
18
and
22
are made partially thinner.
If the first insulating layer
16
and the second insulating layer
22
are made thinner so as to make the memory density of the magnetic tape memory higher, the thickness of the films
16
,
18
and
22
are made further partially thinner. By making the thin insulating layers
16
and
22
further partially thinner, enough insulating strength cannot be gained between the upper shielding layer
24
and the MR element section
18
, so that number of bad products, whose insulating strength are lower than a prescribed strength, must be increased.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a thin film magnetic head, in which insulating layers and an MR element having uniform thickness can be formed on a surface of a magnetizable substrate, which includes fine holes, with enough insulating strength. Another object of the present invention is to provide a method of manufacturing said thin film magnetic head.
To achieve the objects, the thin film magnetic head of the present invention comprises: a magnetizable substrate; a magnetizable metal layer being formed on a surface of the magnetizable substrate; a first insulating layer being formed on a surface of the magnetizable metal layer; a magnetic resistance effect (MR) element section for reproducing data being formed on a surface of the first insulating layer; a second insulating layer being formed on the magnetic resistance element section so as to sandwich the magnetic resistance element section between the first insulating layer and the second insulating layer; and a shielding layer being formed on a surface of the second insulating layer.
With this structure, the insulating layers and the MR element section are formed on the flat surface of the magnetizable metal layer, which has been formed on the magnetizable substrate, so that the insulating layers and the MR element section are not partially depressed even if fine holes are formed in the surface of the magnetizable substrate. Unlike the conventional magnetic head in which the insulating layers and the MR element section are directly formed on the uneven surface of the magnetizable substrate, the thickness of the insulating layers and the MR element section of the magnetic head of the present invention can be uniform. Therefore, the insulating strength of the MR element section can be improved, and number of the bad products, whose insulating strength are lower than the prescribed strength, can be reduced.
Another thin film magnetic head of the present invention comprises: a thin film magnetic head section for reproducing data; and another thin f
Kamiizumi Hiroya
Umehara Toshio
Fujitsu Limited
Greer Burns & Crain Ltd.
Miller Brian E.
LandOfFree
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