Magnetic recording head with dielectric layer separating...

Details Magnetic recording head with dielectric layer separating... Magnetic recording head with dielectric layer separating...

2001-06-01

2004-08-10

Davis, David (Department: 2652)

Dynamic magnetic information storage or retrieval

Head

Core

Reexamination Certificate

active

06775098

ABSTRACT:

TECHNICAL FIELD
This invention relates to improved magnetic recording heads. More particularly, the invention relates to magnetic recording heads with a dielectric layer, and to methods for utilizing this layer to reduce magnetic flux leakage in the recording head.
BACKGROUND
Magnetic recording heads are commonly used to record data to a magnetic data storage medium, such as a computer hard drive. A computer hard drive uses at least one disc coated with magnetic material and a recording head suspended over the surface of the disc. The surface of the recording head that is substantially parallel to the surface of the disc is known as an air bearing surface. The recording head has a pair of opposing poles, known as a top pole and a bottom pole, that are made of a magnetic material. The poles are separated by a nonmagnetic gap layer in a region near the air bearing surface known as the pole tip region. The recording head includes at least one inductive coil that generates magnetic flux through the top pole and the bottom pole. A magnetic field is formed across the gap layer at the air bearing surface to record data to the disc.
A portion of the magnetic flux generated by the inductive coil is often transmitted between the top and bottom poles in a region outside the pole tip region. The leakage of magnetic flux in the recording head impacts the magnetic field at the air bearing surface, and may degrade the performance of the recording head.
A cross-sectional view of a conventional magnetic recording head
3
is shown in FIG.
1
. The conventional recording head
3
has a bottom pole layer
10
of a magnetic material, such as permalloy. The bottom pole layer
10
may serve as a magnetic shield layer for a magnetoresistive sensor (not shown in FIG.
1
), in which case the bottom pole layer
10
is known as a shared pole layer
10
. To insulate the inductive coils
26
of the recording head
3
from the magnetic material of the bottom pole layer
10
, a zero throat
20
is formed on a selected region
15
of the bottom pole layer
10
. The zero throat
20
provides a base
25
on which the inductive coils
26
may be formed. The zero throat
20
is typically made of a nonconductive material, such as a cured photoresist material. The inductive coils
26
are surrounded by insulative material
27
, such as a cured photoresist material, that is formed over the zero throat
20
.
A bottom pole extension
40
, a gap layer
50
and a top pole extension
60
are formed in succession on the bottom pole layer
10
. The bottom pole extension
40
is plated over a selected portion
11
of the bottom pole layer
10
not overlain by the zero throat
20
. The gap layer
50
, which is made of a nonmagnetic material such as PdNi (Palladium nickel), is plated over the bottom pole extension
40
. Both the bottom pole extension
40
and the gap layer
50
extend from an air bearing surface
80
and overlie a region
23
on the zero throat
20
. The top pole extension
60
is plated over the gap layer
50
and also extends from the air bearing surface
80
and overlies the region
23
of the zero throat
20
. A top pole layer
70
is formed over a portion
63
of the top pole extension
60
and the insulation layer
27
that surrounds the inductive coils
26
.
To write data to the magnetic media, the inductive coils
26
generate magnetic flux, and a magnetic field is formed between the top pole extension
60
and the bottom pole extension
40
at the air bearing surface
80
.
Referring to
FIG. 2
, to make the magnetic recording head
3
of
FIG. 1
, an optional seed layer
12
may be deposited over an exposed region
11
of the bottom pole layer
10
that is not overlain by the zero throat
20
, as well as over a surface
21
of the zero throat
20
. The seed layer
12
is a thin layer of magnetic material that provides a base for plating additional layers. After the seed layer
12
is deposited, the bottom pole extension
40
, the gap layer
50
and the top pole layer
60
are electroplated in a pole tip region
14
, as well as over the region
23
of the zero throat
20
. Subsequently, the gap layer
50
is plated over the bottom pole extension
40
, and the top pole extension
60
is plated over the gap layer
50
. After the top pole layer
70
is deposited (FIG.
1
), a lapping process may be used to form the air bearing surface
80
of the recording head
3
.
SUMMARY
Referring to
FIGS. 1-2
, the magnetic flux generated by the inductive coils
26
should completely and uninterruptedly transmit in a path between the bottom pole extension
40
and the top pole extension
60
at the air bearing surface
80
. However, since the bottom pole extension
40
and the gap layer
50
are plated over the region
23
of the zero throat
20
, some of the magnetic flux is lost in a flux leakage region
16
between the bottom pole extension
40
and the top pole extension
60
. The flux leakage region
16
is located at the interface between the overlapping areas of the layers
40
,
50
, and
60
over the region
23
of the zero throat
20
. The magnetic flux at the air bearing surface
80
is essential to the writing capabilities of the recording head, and the loss of magnetic flux in the flux leakage region
16
(
FIG. 2
) may degrade the performance of the recording head.
In general, the invention is directed to improved recording heads with reduced magnetic flux leakage, and methods for their manufacture.
In one embodiment, the invention is a magnetic recording head including a zero throat formed over a region of a bottom pole layer, a pole tip region with a bottom pole extension and a gap layer, and a dielectric layer that separates the zero throat from the bottom pole extension and the gap layer. The dielectric layer reduces the magnetic flux leakage of the magnetic recording head.
In a second embodiment, the invention is a magnetic recording head including a zero throat formed over a region of a bottom pole layer, a bottom pole extension, a top pole extension, and a means for reducing overlapping area between the bottom pole extension and the top pole extension over the zero throat.
In a third embodiment, the invention is a method of manufacturing a magnetic recording head including forming a zero throat on a bottom pole layer; forming a dielectric layer over a portion of the bottom pole layer and over a portion of the zero throat; and plating a first layer on the bottom pole layer to in a pole tip region. The dielectric layer separates the first layer in the pole tip region from the zero throat.
In a fourth embodiment, the invention is a method for selective multi-layer plating including depositing a dielectric material over a region of a seed layer, masking a pattern over the seed layer and the dielectric material, plating at least one plated layer in the seed layer region, removing at least a portion of the dielectric material to form an exposed area of the seed layer; and plating over the plated layer and the exposed area of the seed layer.
The dielectric layer occupies an area over the zero throat in the magnetic flux leakage region that otherwise may be occupied by the components of the pole tip region, such as the bottom pole extension, the gap layer, and the top pole extension. The dielectric layer prevents the bottom pole extension and gap layer from contacting the zero throat, so the magnetic flux loss in the flux leakage region may be reduced or substantially eliminated. In addition, the dielectric layer may be used in combination with a photoresist pattern during the manufacturing process to more precisely control the plating of the bottom pole extension, the gap layer, and the top pole extension using a self-aligned selective plating process.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.


REFERENCES:
patent: 4199415 (1980-04-01), Sterling et al.
patent: 4486273 (1984-12-01), Lutfy et

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